Naturally occurring means the damage happens within the cell as a result of normal metabolic processes, without external factors like UV radiation or cigarette smoke causing the damage.
125-436: The blue mussel ( Mytilus edulis ), also known as the common mussel , is a medium-sized edible marine bivalve mollusc in the family Mytilidae , the only extant family in the order Mytilida, known as "true mussels" . Blue mussels are subject to commercial use and intensive aquaculture . A species with a large range, empty shells are commonly found on beaches around the world. Systematically blue mussel consists of
250-410: A halocline . If a zone undergoes a strong, vertical chemistry gradient with depth, it contains a chemocline . Temperature and salinity control ocean water density. Colder and saltier water is denser, and this density plays a crucial role in regulating the global water circulation within the ocean. The halocline often coincides with the thermocline, and the combination produces a pronounced pycnocline ,
375-489: A mid-ocean ridge , which creates a long mountain range beneath the ocean. Together they form the global mid-oceanic ridge system that features the longest mountain range in the world. The longest continuous mountain range is 65,000 km (40,000 mi). This underwater mountain range is several times longer than the longest continental mountain range – the Andes . Oceanographers state that less than 20% of
500-423: A 5mCp-8-OHdG site recruits TET1 , and TET1 oxidizes the 5mC adjacent to the 8-OHdG. This initiates de-methylation of 5mC. TET1 is a key enzyme involved in de-methylating 5mCpG. However, TET1 is only able to act on 5mCpG if the guanine was first oxidized to form 8-hydroxy-2'-deoxyguanosine (8-OHdG or its tautomer 8-oxo-dG), resulting in a 5mCp-8-OHdG dinucleotide (see figure in this section). This initiates
625-449: A CpG site is oxidation of the guanine to form 8-oxo-dG. The figure in this section shows a CpG site where the cytosine is methylated to form 5-methylcytosine (5mC) and the guanine is oxidized to form 8-oxo-2'-deoxyguanosine (in the figure this is shown in the tautomeric form 8-OHdG). When this structure is formed, the base excision repair enzyme OGG1 targets 8-OHdG and binds to the lesion without immediate excision. OGG1, present at
750-512: A boundary between less dense surface water and dense deep water. DNA damage (naturally occurring) DNA damage is an alteration in the chemical structure of DNA , such as a break in a strand of DNA, a nucleobase missing from the backbone of DNA, or a chemically changed base such as 8-OHdG . DNA damage can occur naturally or via environmental factors, but is distinctly different from mutation , although both are types of error in DNA . DNA damage
875-702: A complex with DDB1 , the ubiquitin ligase protein CUL4A and the RING finger protein ROC1, associates with sites of damage within chromatin. Half-maximum association occurs in 40 seconds. PARP1 also associates within this period. The PARP1 protein attaches to both DDB1 and DDB2 and then PARylates (creates a poly-ADP ribose chain) on DDB2 that attracts the DNA remodeling protein ALC1 . ALC1 relaxes chromatin at sites of UV damage to DNA. In addition,
1000-469: A dense population. In high density aggregations, growth of blue mussels at the centre of the aggregation is reduced, likely due to a reduction in food availability. When possible, mussels will thus migrate to lower densities on larger scales (>7.5 cm), but aggregate on small scales (<2.0 cm). In areas where blue mussels are threatened, such as the Wadden Sea , it is of great importance to enhance
1125-442: A form of DNA damage. The list below shows some frequencies with which new naturally occurring DNA damages arise per day, due to endogenous cellular processes. Another important endogenous DNA damage is M1dG , short for (3-(2'-deoxy-beta-D-erythro-pentofuranosyl)-pyrimido[1,2-a]-purin-10(3H)-one). The excretion in urine (likely reflecting rate of occurrence) of M1dG may be as much as 1,000-fold lower than that of 8-oxodG. However,
1250-579: A gentle breeze on a pond causes ripples to form. A stronger gust blowing over the ocean causes larger waves as the moving air pushes against the raised ridges of water. The waves reach their maximum height when the rate at which they are travelling nearly matches the speed of the wind. In open water, when the wind blows continuously as happens in the Southern Hemisphere in the Roaring Forties , long, organized masses of water called swell roll across
1375-746: A group of (at least) three closely related taxa of mussels, known as the Mytilus edulis complex . Collectively they occupy both coasts of the North Atlantic (including the Mediterranean ) and of the North Pacific in temperate to polar waters, as well as coasts of similar nature in the Southern Hemisphere . The distribution of the component taxa has been recently modified as a result of human activity. The taxa can hybridise with each other, if present at
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#17328519970561500-410: A more important measure may be the steady-state level in DNA, reflecting both rate of occurrence and rate of DNA repair. The steady-state level of M1dG is higher than that of 8-oxodG. This points out that some DNA damages produced at a low rate may be difficult to repair and remain in DNA at a high steady-state level. Both M1dG and 8-oxodG are mutagenic . Steady-state levels of DNA damages represent
1625-451: A result, the photic zone is the most biodiverse and the source of the food supply which sustains most of the ocean ecosystem . Ocean photosynthesis also produces half of the oxygen in the Earth's atmosphere. Light can only penetrate a few hundred more meters; the rest of the deeper ocean is cold and dark (these zones are called mesopelagic and aphotic zones). The continental shelf is where
1750-488: A safeguard mechanism against tumorigenesis. It prevents the increased mutagenesis that excess DNA damage could cause, upon replication. At least 17 DNA repair proteins, distributed among five DNA repair pathways, have a "dual role" in response to DNA damage. With moderate levels of DNA damage, these proteins initiate or contribute to DNA repair. However, when excessive levels of DNA damage are present, they trigger apoptosis. The packaging of eukaryotic DNA into chromatin
1875-472: A second. SIRT6 at the site is required for efficient recruitment of poly (ADP-ribose) polymerase 1 (PARP1) to a DNA break site and for efficient repair of DSBs. PARP1 protein starts to appear at DSBs in less than a second, with half maximum accumulation within 1.6 seconds after the damage occurs. This then allows half maximum recruitment of the DNA repair enzymes MRE11 within 13 seconds and NBS1 within 28 seconds. MRE11 and NBS1 carry out early steps of
2000-496: A shallow area and this, coupled with a low pressure system, can raise the surface of the ocean dramatically above a typical high tide. The average depth of the oceans is about 4 km. More precisely the average depth is 3,688 meters (12,100 ft). Nearly half of the world's marine waters are over 3,000 meters (9,800 ft) deep. "Deep ocean," which is anything below 200 meters (660 ft), covers about 66% of Earth's surface. This figure does not include seas not connected to
2125-580: A time, they are no longer able to use their defenses and can be killed more easily. Blue mussels are filter feeders and play a vital role in estuaries by removing bacteria and toxins. Mytilus edulis is commonly harvested for food throughout the world, from both wild and farmed sources. Mussels are a staple of many seafood dishes in various cuisines including Spanish (especially Galician ), Portuguese , French , British , Dutch , Belgian , Italian and Turkey as midye dolma . They are also commonly used as lab animals . Blue mussels were also harvested by
2250-468: A variety of mechanisms within and around the genome. The enzyme topoisomerase II , or TOPIIβ plays a key role in DSB formation by aiding in the demethylation or loosening of histones wrapped around the double helix to promote transcription . Once the chromatin structure is opened, DSBs are more likely to accumulate, however, this is normally repaired by TOPIIβ through its intrinsic religation ability that rejoins
2375-403: A wave-cut platform develops at the foot of the cliff and this has a protective effect, reducing further wave-erosion. Material worn from the margins of the land eventually ends up in the sea. Here it is subject to attrition as currents flowing parallel to the coast scour out channels and transport sand and pebbles away from their place of origin. Sediment carried to the sea by rivers settles on
2500-406: A zone undergoes dramatic changes in temperature with depth, it contains a thermocline , a distinct boundary between warmer surface water and colder deep water. In tropical regions, the thermocline is typically deeper compared to higher latitudes. Unlike polar waters , where solar energy input is limited, temperature stratification is less pronounced, and a distinct thermocline is often absent. This
2625-439: Is a bay , a small bay with a narrow inlet is a cove and a large bay may be referred to as a gulf . Coastlines are influenced by several factors including the strength of the waves arriving on the shore, the gradient of the land margin, the composition and hardness of the coastal rock, the inclination of the off-shore slope and the changes of the level of the land due to local uplift or submergence. Normally, waves roll towards
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#17328519970562750-400: Is a barrier to all DNA-based processes that require enzyme action. For most DNA repair processes, the chromatin must be remodeled . In eukaryotes, ATP -dependent chromatin remodeling complexes and histone-modifying enzymes are two factors that act to accomplish this remodeling process after DNA damage occurs. Further DNA repair steps, involving multiple enzymes, usually follow. Some of
2875-526: Is about two million base pairs at the site of a DNA double-strand break. γH2AX does not, itself, cause chromatin decondensation, but within 30 seconds of irradiation, RNF8 protein can be detected in association with γH2AX. RNF8 mediates extensive chromatin decondensation, through its subsequent interaction with CHD4 , a component of the nucleosome remodeling and deacetylase complex NuRD . After rapid chromatin remodeling , cell cycle checkpoints may be activated to allow DNA repair to be completed before
3000-738: Is about −2 °C (28 °F). In all parts of the ocean, deep ocean temperatures range between −2 °C (28 °F) and 5 °C (41 °F). Constant circulation of water in the ocean creates ocean currents . Those currents are caused by forces operating on the water, such as temperature and salinity differences, atmospheric circulation (wind), and the Coriolis effect . Tides create tidal currents, while wind and waves cause surface currents. The Gulf Stream , Kuroshio Current , Agulhas Current and Antarctic Circumpolar Current are all major ocean currents. Such currents transport massive amounts of water, gases, pollutants and heat to different parts of
3125-495: Is aided by the presence of predator cues. Several explanations for aggregate formation have been offered, such as increase of reproductive success in low density populations, resisting of wave action , and defence against predators. It is, however, still unclear what the main purpose is and aggregation might have different purposes under different circumstances. Mussel beds are persistent, dense mussel populations. Beds generally form from fields that persist long enough to establish
3250-538: Is an abnormal chemical structure in DNA, while a mutation is a change in the sequence of base pairs. DNA damages cause changes in the structure of the genetic material and prevents the replication mechanism from functioning and performing properly. The DNA damage response (DDR) is a complex signal transduction pathway which recognizes when DNA is damaged and initiates the cellular response to the damage. DNA damage and mutation have different biological consequences. While most DNA damages can undergo DNA repair , such repair
3375-444: Is an important reference point for oceanography and geography, particularly as mean sea level . The ocean surface has globally little, but measurable topography , depending on the ocean's volumes. The ocean surface is a crucial interface for oceanic and atmospheric processes. Allowing interchange of particles, enriching the air and water, as well as grounds by some particles becoming sediments . This interchange has fertilized life in
3500-509: Is characteristic of planktotrophs. By minimizing nutrients in egg production to the bare minimum they are able to maximize the number of gametes produced. If the adult mussels are stressed during the beginning of gametogenesis, the process is terminated. When stressed while fresh gametes are present, adult mussels reabsorb gametes. Larvae viability is also affected by the condition of parents: high water temperatures, pollutants and scarcity of food, during gamete production. The reduction in viability
3625-573: Is complexed with active OGG1 it may then recruit chromatin remodelers to modulate gene expression. Chromodomain helicase DNA-binding protein 4 (CHD4) , a component of the (NuRD) complex , is recruited by OGG1 to oxidative DNA damage sites. CHD4 then attracts DNA and histone methylating enzymes that repress transcription of associated genes. Oxidation of guanine, particularly within CpG sites , may be especially important in learning and memory. Methylation of cytosines occurs at 60–90% of CpG sites depending on
3750-411: Is customarily divided into five principal oceans – listed below in descending order of area and volume: The ocean fills Earth's oceanic basins . Earth's oceanic basins cover different geologic provinces of Earth's oceanic crust as well as continental crust . As such it covers mainly Earth's structural basins , but also continental shelfs . In mid-ocean, magma is constantly being thrust through
3875-399: Is due to the fact that surface waters in polar latitudes are nearly as cold as deeper waters. Below the thermocline, water everywhere in the ocean is very cold, ranging from −1 °C to 3 °C. Because this deep and cold layer contains the bulk of ocean water, the average temperature of the world ocean is 3.9 °C. If a zone undergoes dramatic changes in salinity with depth, it contains
Blue mussel - Misplaced Pages Continue
4000-432: Is due to the induction of reactive oxygen species (ROS) by various intracellular inflammatory mediators. HBV and HCV infections, in particular, cause 10,000-fold and 100,000-fold increases in intracellular ROS production, respectively. Inflammation-induced ROS that cause DNA damage can trigger apoptosis, but may also cause cancer if repair and apoptotic processes are insufficiently protective. Bile acids , stored in
4125-781: Is found from French Atlantic coast northwards to Novaya Zemlya and Iceland , but not in the Baltic Sea . In France and in the British Isles , it makes hybrid zones with M. galloprovincialis , and also is sometimes intermixed with M. trossulus . The genetically distinct lineage of M. edulis present in the Southern Hemisphere has been attributed to subspecies Mytilus edulis platensis (now Mytilus platensis ). Blue mussels are boreo-temperate invertebrates that live in intertidal areas attached to rocks and other hard substrates by strong (and somewhat elastic) thread-like structures called byssal threads , secreted by byssal glands located in
4250-500: Is further described in DNA damage theory of aging . Swenberg et al. measured average amounts of selected steady state endogenous DNA damages in mammalian cells. The seven most common damages they evaluated are shown in Table 1. Evaluating steady-state damages in specific tissues of the rat, Nakamura and Swenberg indicated that the number of abasic sites varied from about 50,000 per cell in liver, kidney and lung to about 200,000 per cell in
4375-496: Is half-maximum recruitment of OGG1 to the irradiated line. OGG1 is an enzyme that removes the oxidative DNA damage 8-oxo-dG from DNA. Removal of 8-oxo-dG, during base excision repair, occurs with a half-life of 11 minutes. Ultraviolet (UV) light induces the formation of DNA damages including pyrimidine dimers (such as thymine dimers) and 6,4 photoproducts. These types of "bulky" damages are repaired by nucleotide excision repair . After irradiation with UV light, DDB2 , in
4500-452: Is irregular, unevenly dominating the Earth's surface . This leads to the distinction of the Earth's surface into a water and land hemisphere , as well as the division of the ocean into different oceans. Seawater covers about 361,000,000 km (139,000,000 sq mi) and the ocean's furthest pole of inaccessibility , known as " Point Nemo ", in a region known as spacecraft cemetery of
4625-684: Is not 100% efficient. Un-repaired DNA damages accumulate in non-replicating cells, such as cells in the brains or muscles of adult mammals, and can cause aging. (Also see DNA damage theory of aging .) In replicating cells, such as cells lining the colon, errors occur upon replication of past damages in the template strand of DNA or during repair of DNA damages. These errors can give rise to mutations or epigenetic alterations. Both of these types of alteration can be replicated and passed on to subsequent cell generations. These alterations can change gene function or regulation of gene expression and possibly contribute to progression to cancer. Throughout
4750-475: Is probably due to the lack of lipid reserves distributed to the eggs. Blue mussels are used for monitoring marine pollution based on their tendency to accumulate numerous pollutants from their natural environment. Upon in vivo exposure of blue mussels ( Mytilus edulis ) to either of two metals of environmental concern, cadmium or chromium , it was found that both of these metals induce DNA strand breakage , and also impair different DNA repair capacities in
4875-454: Is produced and magma is forced up creating underwater mountains, some of which may form chains of volcanic islands near to deep trenches. Near some of the boundaries between the land and sea, the slightly denser oceanic plates slide beneath the continental plates and more subduction trenches are formed. As they grate together, the continental plates are deformed and buckle causing mountain building and seismic activity. Every ocean basin has
5000-449: Is projected to reduce the growth and survival of blue mussels; in turn, this could drastically reduce their positive impact on coastal water quality. Marine (ocean) The ocean is the body of salt water that covers approximately 70.8% of Earth . In English , the term ocean also refers to any of the large bodies of water into which the world ocean is conventionally divided. The following names describe five different areas of
5125-407: Is pushed across the surface of the ocean by the wind, but this represents a transfer of energy and not horizontal movement of water. As waves approach land and move into shallow water , they change their behavior. If approaching at an angle, waves may bend ( refraction ) or wrap around rocks and headlands ( diffraction ). When the wave reaches a point where its deepest oscillations of the water contact
Blue mussel - Misplaced Pages Continue
5250-423: Is reflected back out of the water. Red light is most easily absorbed and thus does not reach great depths, usually to less than 50 meters (164 ft). Blue light, in comparison, can penetrate up to 200 meters (656 ft). Second, water molecules and very tiny particles in ocean water preferentially scatter blue light more than light of other colors. Blue light scattering by water and tiny particles happens even in
5375-467: Is sometimes referred to as the World Ocean, global ocean or the great ocean . The concept of a continuous body of water with relatively unrestricted exchange between its components is critical in oceanography . The word ocean comes from the figure in classical antiquity , Oceanus ( / oʊ ˈ s iː ə n ə s / ; Ancient Greek : Ὠκεανός Ōkeanós , pronounced [ɔːkeanós] ),
5500-448: Is specifically for the damage response to double strand breaks. The MRN complex (composed of Mre11, Rad50, and Nbs1) form immediately at the site of double strand break. This MRN complex recruits ATM to the site of damage. ATR and ATM phosphorylate various proteins that contribute to the damage repair system. The binding of ATR and ATM to damage sites on DNA lead to the recruitment of Chk1 and Chk2. These protein kinases send damage signals to
5625-402: Is the ciliated embryo, which in 24-hours for fertilization form the trochophore . At this point although mobile, it is still reliant on the yolk for nutrients. Characterized by a functional mouth and alimentary canal the veliger stage also has cilia which are used for filtering food as well as propulsion. A thin translucent shell is secreted by the shell gland forming the notable straight hinge of
5750-552: Is the open ocean's water column from the surface to the ocean floor. The water column is further divided into zones based on depth and the amount of light present. The photic zone starts at the surface and is defined to be "the depth at which light intensity is only 1% of the surface value" (approximately 200 m in the open ocean). This is the zone where photosynthesis can occur. In this process plants and microscopic algae (free floating phytoplankton ) use light, water, carbon dioxide, and nutrients to produce organic matter. As
5875-546: The BRCA1 gene in human brains, initially tested in transgenic mice, where DSB levels were observed to have increased and memory loss had occurred, suggesting that BRCA1 could "serve as a therapeutic target for AD and AD-related dementia." Similarly, the protein ATM involved in DNA repair and epigenetic modifications to the genome is positively correlated with neuronal loss in AD brains, indicating
6000-670: The North Sea or the Red Sea . There is no sharp distinction between seas and oceans, though generally seas are smaller, and are often partly (as marginal seas ) or wholly (as inland seas ) bordered by land. The contemporary concept of the World Ocean was coined in the early 20th century by the Russian oceanographer Yuly Shokalsky to refer to the continuous ocean that covers and encircles most of Earth. The global, interconnected body of salt water
6125-472: The South Pacific Ocean , at 48°52.6′S 123°23.6′W / 48.8767°S 123.3933°W / -48.8767; -123.3933 ( Point Nemo ) . This point is roughly 2,688 km (1,670 mi) from the nearest land. There are different customs to subdivide the ocean and are adjourned by smaller bodies of water such as, seas , gulfs , bays , bights , and straits . The ocean
6250-578: The Thames Barrier is designed to protect London from a storm surge, while the failure of the dykes and levees around New Orleans during Hurricane Katrina created a humanitarian crisis in the United States. Most of the ocean is blue in color, but in some places the ocean is blue-green, green, or even yellow to brown. Blue ocean color is a result of several factors. First, water preferentially absorbs red light, which means that blue light remains and
6375-406: The coastline and structure of the world ocean. A global ocean has existed in one form or another on Earth for eons. Since its formation the ocean has taken many conditions and shapes with many past ocean divisions and potentially at times covering the whole globe. During colder climatic periods, more ice caps and glaciers form, and enough of the global water supply accumulates as ice to lessen
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#17328519970566500-591: The ocean floor , they begin to slow down. This pulls the crests closer together and increases the waves' height , which is called wave shoaling . When the ratio of the wave's height to the water depth increases above a certain limit, it " breaks ", toppling over in a mass of foaming water. This rushes in a sheet up the beach before retreating into the ocean under the influence of gravity. Earthquakes , volcanic eruptions or other major geological disturbances can set off waves that can lead to tsunamis in coastal areas which can be very dangerous. The ocean's surface
6625-421: The prodissoconch I shell. The veliger continues to mature forming the prodissoconch II shell. In the end stage of veliger development photosensitive eye spots and elongated foot with a byssal gland are formed. Once the pediveliger is fully developed, its foot extends and makes contact with substrate. The initial contact with the substrate is loose. If the substrate is suitable, the larva will metamorphoses into
6750-400: The 405 nm light is focused along a narrow line within the nucleus of a cell, about 2.5 seconds after irradiation, the chromatin remodeling enzyme Alc1 achieves half-maximum recruitment onto the irradiated micro-line. The line of chromatin that was irradiated then relaxes, expanding side-to-side over the next 60 seconds. Within 6 seconds of the irradiation with 405 nm light, there
6875-470: The DNA damage response system. Some DNA damage does not require the recruitment of ATR and ATM, it is only difficult and extensive damage that requires ATR and ATM. ATM and ATR are required for NHEJ, HR, ICL repair, and NER, as well as replication fork stability during unperturbed DNA replication and in response to replication blocks. ATR is recruited for different forms of damage such as nucleotide damage, stalled replication forks and double strand breaks. ATM
7000-442: The Earth's biosphere . Oceanic evaporation , as a phase of the water cycle, is the source of most rainfall (about 90%), causing a global cloud cover of 67% and a consistent oceanic cloud cover of 72%. Ocean temperatures affect climate and wind patterns that affect life on land. One of the most dramatic forms of weather occurs over the oceans: tropical cyclones (also called "typhoons" and "hurricanes" depending upon where
7125-552: The HRR pathway. γH2AX, the phosphorylated form of H2AX is also involved in early steps of DSB repair. The histone variant H2AX constitutes about 10% of the H2A histones in human chromatin. γH2AX (H2AX phosphorylated on serine 139) can be detected as soon as 20 seconds after irradiation of cells (with DNA double-strand break formation), and half maximum accumulation of γH2AX occurs in one minute. The extent of chromatin with phosphorylated γH2AX
7250-452: The Moon are 20x stronger than the Moon's tidal forces on the Earth.) The primary effect of lunar tidal forces is to bulge Earth matter towards the near and far sides of the Earth, relative to the moon. The "perpendicular" sides, from which the Moon appears in line with the local horizon, experience "tidal troughs". Since it takes nearly 25 hours for the Earth to rotate under the Moon (accounting for
7375-403: The Moon's 28 day orbit around Earth), tides thus cycle over a course of 12.5 hours. However, the rocky continents pose obstacles for the tidal bulges, so the timing of tidal maxima may not actually align with the Moon in most localities on Earth, as the oceans are forced to "dodge" the continents. Timing and magnitude of tides vary widely across the Earth as a result of the continents. Thus, knowing
7500-468: The Moon's gravity, oceanic tides are also substantially modulated by the Sun's tidal forces, by the rotation of the Earth, and by the shape of the rocky continents blocking oceanic water flow. (Tidal forces vary more with distance than the "base" force of gravity: the Moon's tidal forces on Earth are more than double the Sun's, despite the latter's much stronger gravitational force on Earth. Earth's tidal forces upon
7625-400: The Moon's position does not allow a local to predict tide timings, instead requiring precomputed tide tables which account for the continents and the Sun, among others. During each tidal cycle, at any given place the tidal waters rise to maximum height, high tide, before ebbing away again to the minimum level, low tide. As the water recedes, it gradually reveals the foreshore , also known as
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#17328519970567750-643: The Okeanos is represented with a dragon-tail on some early Greek vases. Scientists believe that a sizable quantity of water would have been in the material that formed Earth. Water molecules would have escaped Earth's gravity more easily when it was less massive during its formation. This is called atmospheric escape . During planetary formation , Earth possibly had magma oceans . Subsequently, outgassing , volcanic activity and meteorite impacts , produced an early atmosphere of carbon dioxide , nitrogen and water vapor , according to current theories. The gases and
7875-706: The World Ocean, such as the Caspian Sea . The deepest region of the ocean is at the Mariana Trench , located in the Pacific Ocean near the Northern Mariana Islands . The maximum depth has been estimated to be 10,971 meters (35,994 ft). The British naval vessel Challenger II surveyed the trench in 1951 and named the deepest part of the trench the " Challenger Deep ". In 1960, the Trieste successfully reached
8000-619: The ability to detach and reattach to a surface allowing the mollusk to reposition itself relative to the water position. Right and left valve of the same specimen: var. flavida Mussels have separate sexes. Once the sperm and eggs are fully developed they are released into the water column for fertilization. Although there are about 10,000 sperm per egg, large proportions of eggs deposited by blue mussels are never fertilized. As few as 1% of larvae that do mature ever reach adulthood. The majority are eaten by predators before completing metamorphosis . The reproductive strategy seen in blue mussels
8125-488: The accurate homologous recombinational repair or by the less accurate non-homologous end joining repair pathway. Here we describe the early steps in homologous recombinational repair (HRR). After treating cells to introduce DSBs, the stress-activated protein kinase, c-Jun N-terminal kinase (JNK) , phosphorylates SIRT6 on serine 10. This post-translational modification facilitates the mobilization of SIRT6 to DNA damage sites with half-maximum recruitment in well under
8250-421: The amounts in other parts of the water cycle. The reverse is true during warm periods. During the last ice age, glaciers covered almost one-third of Earth's land mass with the result being that the oceans were about 122 m (400 ft) lower than today. During the last global "warm spell," about 125,000 years ago, the seas were about 5.5 m (18 ft) higher than they are now. About three million years ago
8375-474: The associated gene. When 8-oxo-dG is formed in a guanine rich, potential G-quadruplex-forming sequence (PQS) in the coding strand of a promoter, active OGG1 excises the 8-oxo-dG and generates an apurinic/apyrimidinic site (AP site). The AP site enables melting of the duplex to unmask the PQS, adopting a G-quadruplex fold (G4 structure/motif) that has a regulatory role in transcription activation. When 8-oxo-dG
8500-479: The atmosphere are thought to have accumulated over millions of years. After Earth's surface had significantly cooled, the water vapor over time would have condensed, forming Earth's first oceans. The early oceans might have been significantly hotter than today and appeared green due to high iron content. Geological evidence helps constrain the time frame for liquid water existing on Earth. A sample of pillow basalt (a type of rock formed during an underwater eruption)
8625-429: The balance between formation and repair. More than 100 types of oxidative DNA damage have been characterized, and 8-oxodG constitutes about 5% of the steady state oxidative damages in DNA. Helbock et al. estimated that there were 24,000 steady state oxidative DNA adducts per cell in young rats and 66,000 adducts per cell in old rats. This reflects the accumulation of DNA damage with age. DNA damage accumulation with age
8750-407: The bottom of the trench, manned by a crew of two men. Oceanographers classify the ocean into vertical and horizontal zones based on physical and biological conditions. The pelagic zone consists of the water column of the open ocean, and can be divided into further regions categorized by light abundance and by depth. The ocean zones can be grouped by light penetration into (from top to bottom):
8875-407: The brain. Proteins promoting endogenous DNA damage were identified in a 2019 paper as the DNA "damage-up" proteins (DDPs). The DDP mechanisms fall into 3 clusters: The DDP human homologs are over-represented in known cancer drivers, and their RNAs in tumors predict heavy mutagenesis and a poor prognosis. In the presence of DNA damage, the cell can either repair the damage or induce cell death if
9000-456: The cell cycle progresses. First, two kinases , ATM and ATR , are activated within 5 or 6 minutes after DNA is damaged. This is followed by phosphorylation of the cell cycle checkpoint protein Chk1 , initiating its function, about 10 minutes after DNA is damaged. The DNA damage 8-oxo-dG does not occur randomly in the genome. In mouse embryonic fibroblasts , a 2 to 5-fold enrichment of 8-oxo-dG
9125-1528: The cell cycle there are various checkpoints to ensure the cell is in good condition to progress to mitosis. The three main checkpoints are at G1/s, G2/m, and at the spindle assembly checkpoint regulating progression through anaphase. G1 and G2 checkpoints involve scanning for damaged DNA. During S phase the cell is more vulnerable to DNA damage than any other part of the cell cycle. G2 checkpoint checks for damaged DNA and DNA replication completeness. Damage to DNA that occurs naturally can result from metabolic or hydrolytic processes. Metabolism releases compounds that damage DNA including reactive oxygen species , reactive nitrogen species , reactive carbonyl species, lipid peroxidation products, and alkylating agents , among others, while hydrolysis cleaves chemical bonds in DNA. Naturally occurring oxidative DNA damages arise at least 10,000 times per cell per day in humans and as much as 100,000 per cell per day in rats as documented below. Oxidative DNA damage can produce more than 20 types of altered bases as well as single strand breaks. Other types of endogeneous DNA damages, given below with their frequencies of occurrence, include depurinations , depyrimidinations , double-strand breaks , O6-methylguanines , and cytosine deamination . DNA can be damaged via environmental factors as well. Environmental agents such as UV light, ionizing radiation, and genotoxic chemicals. Replication forks can be stalled due to damaged DNA and double strand breaks are also
9250-444: The cleaved DNA ends. Failure of TOPIIβ to religase can have drastic consequences on protein synthesis, where it is estimated that "blocking TOPIIβ activity alters the expression of nearly one-third of all developmentally regulated genes," such as neural immediate early genes (IEGs) involved in memory consolidation . Rapid expression of egr-1 , c-Fos , and Arc IEGs have been observed in response to increased neuronal activity in
9375-403: The damage is beyond repair. The seven main types of DNA repair and one pathway of damage tolerance, the lesions they address, and the accuracy of the repair (or tolerance) are shown in this table. For a brief description of the steps in repair see DNA repair mechanisms or see each individual pathway. The schematic diagram indicates the roles of insufficient DNA repair in aging and cancer, and
9500-669: The damaged strand of DNA. Stimulation of neuronal activity, as previously mentioned in IEG expression, is another mechanism through which DSBs are generated. Changes in level of activity have been used in studies as a biomarker to trace the overlap between DSBs and increased histone H3K4 methylation in promoter regions of IEGs. Other studies have indicated that transposable elements (TEs) can cause DSBs through endogenous activity that involves using endonuclease enzymes to insert and cleave target DNA at random sites. While accumulation of DSBs generally inhibits long-term memory consolidation,
9625-508: The de-methylation pathway on the methylated cytosine, finally resulting in an unmethylated cytosine (see DNA oxidation for further steps in forming unmethylated cytosine). Altered protein expression in neurons, due to changes in methylation of DNA, (likely controlled by 8-oxo-dG-dependent de-methylation of CpG sites in gene promoters within neuron DNA) has been established as central to memory formation. Double-stranded breaks (DSBs) in regions of DNA related to neuronal activity are produced by
9750-564: The degeneration of neurons, hindering the function of memory and learning processes. Due to their lack of cell division and high metabolic activity , neurons are especially prone to DNA damage. Additionally, an imbalance of DSBs and DNA repair molecules for neuronal-activity genes has been linked to the development of various human neurodegenerative diseases including Alzheimer's disease (AD), Parkinson's disease (PD), and amyotrophic lateral sclerosis (ALS). In patients with Alzheimer's disease, DSBs accumulate in neurons at early stages and are
9875-437: The dog whelk, Nucella lapillus . The blue mussel is host to a wide range of parasites, but these parasites usually do not cause much damage. Blue Mussels are able to fight off one species of predator at a time such as sea star ( Asterias rubens (= Asterias vulgaris )) or green crabs ( Carcinus maenas ). They use their inducible defenses to strengthen their adductor muscle or grow thicker shells. When faced with two species at
10000-507: The driving force behind memory loss, a key characteristic of the disease. Other external factors that result in increased levels of activity-dependent DSBs in people with AD are oxidative damage to neurons, which can result in more DSBs when multiple lesions occur close to one another. Environmental factors such as viruses and a high-fat diet have also been associated with disrupted function of DNA repair molecules. One targeted therapy for treating patients with AD has involved suppression of
10125-501: The elder of the Titans in classical Greek mythology . Oceanus was believed by the ancient Greeks and Romans to be the divine personification of an enormous river encircling the world. The concept of Ōkeanós has an Indo-European connection. Greek Ōkeanós has been compared to the Vedic epithet ā-śáyāna-, predicated of the dragon Vṛtra-, who captured the cows/rivers. Related to this notion,
10250-652: The enzyme H3K4me3, which catalyzes the demethylation of the H3K4 histone, was upregulated at the promoter region of the NPAS4 gene during the reconsolidation process, while knockdown (gene knockdown) of the same enzyme impeded reconsolidation. A similar effect was observed in TOPIIβ, where knockdown also impaired the fear memory response in rats, indicating that DSBs, along with the enzymes that regulate them, influence memory formation at multiple stages. Buildup of DSBs more broadly leads to
10375-437: The first responses to DNA damage, with their timing, are described below. More complete descriptions of the DNA repair pathways are presented in articles describing each pathway. At least 169 enzymes are involved in DNA repair pathways. Oxidized bases in DNA are produced in cells treated with Hoechst dye followed by micro-irradiation with 405 nm light. Such oxidized bases can be repaired by base excision repair . When
10500-464: The foot of the mussel. The shape of the shell is triangular and elongated with rounded edges. The shell is smooth with a sculpturing of fine concentric growth lines but no radiating ribs. The shells of this species are purple, blue or sometimes brown in color, occasionally with radial stripes. The outer surface of the shell is covered by the periostracum which as eroded, exposes the colored prismatic calcitic layer. Blue Mussels are semi-sessile, having
10625-412: The formation of unusually high rogue waves . Most waves are less than 3 m (10 ft) high and it is not unusual for strong storms to double or triple that height. Rogue waves, however, have been documented at heights above 25 meters (82 ft). The top of a wave is known as the crest, the lowest point between waves is the trough and the distance between the crests is the wavelength. The wave
10750-459: The gall bladder, are released into the small intestine in response to fat in the diet. Higher levels of fat cause greater release. Bile acids cause DNA damage, including oxidative DNA damage, double-strand DNA breaks, aneuploidy and chromosome breakage. High-normal levels of the bile acid deoxycholic acid cause apoptosis in human colon cells, but may also lead to colon cancer if repair and apoptotic defenses are insufficient. Apoptosis serves as
10875-415: The hippocampus region of the brain where memory processing takes place. As a preventative measure against TOPIIβ failure, DSB repair molecules are recruited via two different pathways: non-homologous end joining (NHEJ) pathway factors, which perform a similar religation function to that of TOPIIβ, and the homologous recombination (HR) pathway, which uses the non-broken sister strand as a template to repair
11000-618: The indigenous peoples of North America. Blue mussels are starting to decline in areas such as the Gulf of Maine. Historical references have shown a decrease of about 40 percent in the last fifty years. This can cause a future problem because mussels are foundation species providing homes and protecting other small animals in the intertidal zone like small fish as well as filtering the water. Mussels filter out bacteria, metals, and toxins, that would increase significantly without mussels around. Ocean acidification due to increasing atmospheric carbon dioxide
11125-421: The interface between water and air is called swell – a term used in sailing , surfing and navigation . These motions profoundly affect ships on the surface of the ocean and the well-being of people on those ships who might suffer from sea sickness . Wind blowing over the surface of a body of water forms waves that are perpendicular to the direction of the wind. The friction between air and water caused by
11250-482: The intertidal zone. The difference in height between the high tide and low tide is known as the tidal range or tidal amplitude. When the sun and moon are aligned (full moon or new moon), the combined effect results in the higher "spring tides", while the sun and moon misaligning (half moons) result in lesser tidal ranges. In the open ocean tidal ranges are less than 1 meter, but in coastal areas these tidal ranges increase to more than 10 meters in some areas. Some of
11375-399: The juvenile form, plantigrade , and attach byssus threads. The mussel will remain in that state until reaching 1-1.5mm in length. This attachment is the prerequisite for the foundation for the blue mussel population. In sheltered environments large masses sometimes form beds which offer shelter and food for other invertebrates. Byssal thread are secreted by byssal glands located in the foot of
11500-710: The largest tidal ranges in the world occur in the Bay of Fundy and Ungava Bay in Canada, reaching up to 16 meters. Other locations with record high tidal ranges include the Bristol Channel between England and Wales, Cook Inlet in Alaska, and the Río Gallegos in Argentina. Tides are not to be confused with storm surges , which can occur when high winds pile water up against the coast in
11625-422: The level of DNA damage exceeds the repair capacity. Apoptosis can prevent cells with excess DNA damage from undergoing mutagenesis and progression to cancer. Inflammation is often caused by infection, such as with hepatitis B virus (HBV), hepatitis C virus (HCV) or Helicobacter pylori . Chronic inflammation is also a central characteristic of obesity. Such inflammation causes oxidative DNA damage. This
11750-466: The majority of Earth's surface. It includes the Pacific , Atlantic , Indian , Southern/Antarctic , and Arctic oceans. As a general term, "the ocean" and "the sea" are often interchangeable. Strictly speaking, a "sea" is a body of water (generally a division of the world ocean) partly or fully enclosed by land. The word "sea" can also be used for many specific, much smaller bodies of seawater, such as
11875-452: The mussel, and are made up of polyphenolic proteins which serve as a bioadhesive. Blue mussels often form aggregations, where they attach to each other using byssus threads . These are collagenous protein strands used for attachment. The type of aggregation depends on population densities . When densities are low, for example in mussel fields – short-lived mussel populations – clumped distribution patterns are seen. The rate of aggregation
12000-408: The ocean faces many environmental threats, such as marine pollution , overfishing , and the effects of climate change . Those effects include ocean warming , ocean acidification and sea level rise . The continental shelf and coastal waters are most affected by human activity. The terms "the ocean" or "the sea" used without specification refer to the interconnected body of salt water covering
12125-423: The ocean meets dry land. It is more shallow, with a depth of a few hundred meters or less. Human activity often has negative impacts on marine life within the continental shelf. Ocean temperatures depend on the amount of solar radiation reaching the ocean surface. In the tropics, surface temperatures can rise to over 30 °C (86 °F). Near the poles where sea ice forms, the temperature in equilibrium
12250-508: The ocean, on land and air. All these processes and components together make up ocean surface ecosystems . Tides are the regular rise and fall in water level experienced by oceans, primarily driven by the Moon 's gravitational tidal forces upon the Earth. Tidal forces affect all matter on Earth, but only fluids like the ocean demonstrate the effects on human timescales. (For example, tidal forces acting on rock may produce tidal locking between two planetary bodies.) Though primarily driven by
12375-469: The ocean. If the wind dies down, the wave formation is reduced, but already-formed waves continue to travel in their original direction until they meet land. The size of the waves depends on the fetch , the distance that the wind has blown over the water and the strength and duration of that wind. When waves meet others coming from different directions, interference between the two can produce broken, irregular seas. Constructive interference can lead to
12500-493: The ocean: Pacific , Atlantic , Indian , Antarctic/Southern , and Arctic . The ocean contains 97% of Earth's water and is the primary component of Earth's hydrosphere and is thereby essential to life on Earth. The ocean influences climate and weather patterns, the carbon cycle , and the water cycle by acting as a huge heat reservoir . Ocean scientists split the ocean into vertical and horizontal zones based on physical and biological conditions. The pelagic zone
12625-419: The oceans absorb CO 2 from the atmosphere , a higher concentration leads to ocean acidification (a drop in pH value ). The ocean provides many benefits to humans such as ecosystem services , access to seafood and other marine resources , and a means of transport . The ocean is known to be the habitat of over 230,000 species , but may hold considerably more – perhaps over two million species. Yet,
12750-425: The oceans could have been up to 50 m (165 ft) higher. The entire ocean, containing 97% of Earth's water, spans 70.8% of Earth 's surface, making it Earth's global ocean or world ocean . This makes Earth, along with its vibrant hydrosphere a "water world" or " ocean world ", particularly in Earth's early history when the ocean is thought to have possibly covered Earth completely. The ocean's shape
12875-434: The oceans have been mapped. The zone where land meets sea is known as the coast , and the part between the lowest spring tides and the upper limit reached by splashing waves is the shore . A beach is the accumulation of sand or shingle on the shore. A headland is a point of land jutting out into the sea and a larger promontory is known as a cape . The indentation of a coastline, especially between two headlands,
13000-533: The oceans may have always been on the Earth since the beginning of the planet's formation. In this model, atmospheric greenhouse gases kept the oceans from freezing when the newly forming Sun had only 70% of its current luminosity . The origin of Earth's oceans is unknown. Oceans are thought to have formed in the Hadean eon and may have been the cause for the emergence of life . Plate tectonics , post-glacial rebound , and sea level rise continually change
13125-451: The photic zone, the mesopelagic zone and the aphotic deep ocean zone: The pelagic part of the aphotic zone can be further divided into vertical regions according to depth and temperature: Distinct boundaries between ocean surface waters and deep waters can be drawn based on the properties of the water. These boundaries are called thermoclines (temperature), haloclines (salinity), chemoclines (chemistry), and pycnoclines (density). If
13250-418: The power of a storm wave impacting on the foot of a cliff has a shattering effect as air in cracks and crevices is compressed and then expands rapidly with release of pressure. At the same time, sand and pebbles have an erosive effect as they are thrown against the rocks. This tends to undercut the cliff, and normal weathering processes such as the action of frost follows, causing further destruction. Gradually,
13375-440: The process of reconsolidation , in contrast, is DSB-dependent. Memory reconsolidation involves the modification of existing memories stored in long-term memory. Research involving NPAS4 , a gene that regulates neuroplasticity in the hippocampus during contextual learning and memory formation, has revealed a link between deletions in the coding region and impairments in recall of fear memories in transgenic rats. Moreover,
13500-399: The promoter of a gene, the oxidative stress may also inactivate OGG1 , an enzyme that targets 8-oxo-dG and normally initiates repair of 8-oxo-dG damage. The inactive OGG1, which no longer excises 8-oxo-dG, nevertheless targets and complexes with 8-oxo-dG, and causes a sharp (~70 ) bend in the DNA. This allows the assembly of a transcriptional initiation complex, up-regulating transcription of
13625-604: The protein is another key component in the intrinsically linked processes of neurodegeneration, DSB production, and memory formation. Most damage can be repaired without triggering the damage response system, however more complex damage activates ATR and ATM, key protein kinases in the damage response system. DNA damage inhibits M-CDKs which are a key component of progression into mitosis . In all eukaryotic cells, ATR and ATM are protein kinases that detect DNA damage. They bind to DNA damaged sites and activate Chk1 , Chk2 , and, in animal cells, p53 . Together, these proteins make up
13750-563: The role of apoptosis in cancer prevention. An excess of naturally occurring DNA damage, due to inherited deficiencies in particular DNA repair enzymes, can cause premature aging or increased risk for cancer (see DNA repair-deficiency disorder ). On the other hand, the ability to trigger apoptosis in the presence of excess un-repaired DNA damage is critical for prevention of cancer. DNA repair proteins are often activated or induced when DNA has sustained damage. However, excessive DNA damage can initiate apoptosis (i.e., programmed cell death) if
13875-506: The same locality. The Atlantic blue mussel is native on the North American Atlantic coast, but is found intermixed with M. trossulus north of Maine . In Atlantic Canada, M. trossulus was found to have smaller shell growth values than M. edulis and contain less meat than M. edulis. Keeping this in mind, M. edulis, under raft culture conditions, is estimated to have an economic value of 1.7 times M. trossulus. In Europe it
14000-455: The seabed between adjoining plates to form mid-oceanic ridges and here convection currents within the mantle tend to drive the two plates apart. Parallel to these ridges and nearer the coasts, one oceanic plate may slide beneath another oceanic plate in a process known as subduction . Deep trenches are formed here and the process is accompanied by friction as the plates grind together. The movement proceeds in jerks which cause earthquakes, heat
14125-407: The seabed causing deltas to form in estuaries. All these materials move back and forth under the influence of waves, tides and currents. Dredging removes material and deepens channels but may have unexpected effects elsewhere on the coastline. Governments make efforts to prevent flooding of the land by the building of breakwaters , seawalls , dykes and levees and other sea defences. For instance,
14250-430: The shells becomes stronger, blue mussels are preyed upon by sea stars such as Asterias vulgaris as well as by several species of sea gulls . The capability of shell thickening by mussels has become a very effective defense mechanism. In the presence of predators a mussel is able to increase shell thickness 5 to 10 percent, which in turn makes opening the shell take 50 percent more time. Small mussels are also eaten by
14375-401: The shore at the rate of six to eight per minute and these are known as constructive waves as they tend to move material up the beach and have little erosive effect. Storm waves arrive on shore in rapid succession and are known as destructive waves as the swash moves beach material seawards. Under their influence, the sand and shingle on the beach is ground together and abraded. Around high tide,
14500-469: The site of the DNA damage, and this coincides with the binding of further nucleotide excision repair proteins, including ERCC1 . Double-strand breaks (DSBs) at specific sites can be induced by transfecting cells with a plasmid encoding I-SceI endonuclease (a homing endonuclease ). Multiple DSBs can be induced by irradiating sensitized cells (labeled with 5'-bromo-2'-deoxyuridine and with Hoechst dye) with 780 nm light. These DSBs can be repaired by
14625-402: The survival of mussel fields, of which mussel aggregates are the primary component. Predation of blue mussels is greatest during the three weeks it spends as a planktonic larva. During this stage it is susceptible to jellyfish and fish larvae through adults. Once it metamorphoses the mussel is still restricted by predation, with smaller mussels with thinner, weaker shells most affected. Once
14750-456: The system forms). As the world's ocean is the principal component of Earth's hydrosphere , it is integral to life on Earth, forms part of the carbon cycle and water cycle , and – as a huge heat reservoir – influences climate and weather patterns. The motions of the ocean surface, known as undulations or wind waves , are the partial and alternate rising and falling of the ocean surface. The series of mechanical waves that propagate along
14875-399: The tissue type. In the mammalian brain, ~62% of CpGs are methylated. Methylation of CpG sites tends to stably silence genes. More than 500 of these CpG sites are de-methylated in neuron DNA during memory formation and memory consolidation in the hippocampus and cingulate cortex regions of the brain. As indicated below, the first step in de-methylation of methylated cytosine at
15000-431: The tissues of these mussels. Larval development can last from 15 to 35 days depending environmental conditions including salinity and temperature, as well as location. Larvae originating from Connecticut mature normally at 15–20 °C (59–68 °F), though at 15 °C (59 °F) normal development occurs at salinities between 15 and 35 ppt and at 35 ppt at 20 °C (68 °F). The first stage of development
15125-540: The ubiquitin E3 ligase complex DDB1-CUL4A carries out ubiquitination of the core histones H2A, H3, and H4, as well as the repair protein XPC, which has been attracted to the site of the DNA damage. XPC, upon ubiquitination, is activated and initiates the nucleotide excision repair pathway. Somewhat later, at 30 minutes after UV damage, the INO80 chromatin remodeling complex is recruited to
15250-434: The very clearest ocean water, and is similar to blue light scattering in the sky . Ocean water represents the largest body of water within the global water cycle (oceans contain 97% of Earth's water ). Evaporation from the ocean moves water into the atmosphere to later rain back down onto land and the ocean. Oceans have a significant effect on the biosphere . The ocean as a whole is thought to cover approximately 90% of
15375-476: The world, and from the surface into the deep ocean. All this has impacts on the global climate system . Ocean water contains dissolved gases, including oxygen , carbon dioxide and nitrogen . An exchange of these gases occurs at the ocean's surface. The solubility of these gases depends on the temperature and salinity of the water. The carbon dioxide concentration in the atmosphere is rising due to CO 2 emissions , mainly from fossil fuel combustion. As
15500-810: Was found in genetic control regions, including promoters , 5'-untranslated regions and 3'-untranslated regions compared to 8-oxo-dG levels found in gene bodies and in intergenic regions . In rat pulmonary artery endothelial cells, when 22,414 protein-coding genes were examined for locations of 8-oxo-dG, the majority of 8-oxo-dGs (when present) were found in promoter regions rather than within gene bodies. Among hundreds of genes whose expression levels were affected by hypoxia, those with newly acquired promoter 8-oxo-dGs were upregulated , and those genes whose promoters lost 8-oxo-dGs were almost all downregulated . As reviewed by Wang et al., oxidized guanine appears to have multiple regulatory roles in gene expression. In particular, when oxidative stress produces 8-oxo-dG in
15625-750: Was recovered from the Isua Greenstone Belt and provides evidence that water existed on Earth 3.8 billion years ago. In the Nuvvuagittuq Greenstone Belt , Quebec , Canada, rocks dated at 3.8 billion years old by one study and 4.28 billion years old by another show evidence of the presence of water at these ages. If oceans existed earlier than this, any geological evidence either has yet to be discovered, or has since been destroyed by geological processes like crustal recycling . However, in August 2020, researchers reported that sufficient water to fill
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