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Photomicrographs of histological sections of female gonads of both the "F-Fed" and "S-Starved" conditioning treatments: illustration of maturation state and absence of atresia. Modified Masson's trichrome protocol. 1-Female F2. 2-Female S2. c: cytoplasm, ct: connective tissue, io: immature (pedunculate) oocytes, mo: mature oocytes, n: nucleus, nu: nucleolus, p: peduncule.
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The effect of providing algal food to female Crassostrea gigas broodstock sampled at a favourable time of year was investigated using pre-defined indices of oocyte quality and Subsequent larval and post-larval performances. Broodstock were collected in the Aber Benoit estuary (Brittany, France) at the end of April 2002 and were divided into two gro...
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Context 1
... The four females showed identical maturation states: mature oocytes represented the great major- ity of the tissue volume percentages (means and range of 95% confidence intervals CI) 79 to 80% ± 4 to 6%; pedunculate oocytes represented a smaller tissue fraction (10 to 16% ± 4% and connective tissue was also less present (6 to 11%±2 to 6% -see Fig. 2). All females therefore presented oocyte popula- tions with similar maturity profiles, regardless of conditioning treatment, and were thus in the same maturation state when fertilization was carried out ( Figs. 1 and 2). Mature oocyte mean diameters are presented for each fe- male (Fig. 1). Values were not significantly different ...
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Citations
... Survival at unfavorable trophic conditions depends on the physiological state of the organism, i.e. complex interaction between the level of internal energy supply, stable metabolic rate and the process of gametogenesis. The energy reserves are primarily used to support the metabolism, growth and maturation of gonads (Bayne et al., 1978;Pipe, 1985;Robinson, 1992;Cannuel & Beninger, 2005;Liu et al., 2010). During the starvation of mollusks in the winter, when the process of gametogenesis is enhanced, energy needs are provided by protein catabolism, while specialized cells of the somatic tissue continue to accumulate glycogen. ...
In the present work the influence of oxygen content in sea water and 14-days starvation on respiration rate of the bivalve species, Anadara kagoshimensis (Tokunaga, 1906), has been studied. The blood clams with shell height 25-30 mm have been used for experiments. Respiration rate varied in the wide range, from maximal value 89.9 mgO2·l⁻¹ (at 100% saturation) to 5.0 µgО2·h⁻¹·gww⁻¹ (at 76% saturation) at the salinity 17-18 psu and temperature 18°C. The oxygen consumption of the blood clam was substantially lower compared to other benthic bivalves. Our results suggest the ability of A.kagoshimensis to rapidly transition from aerobic to anaerobic metabolism under conditions that are not critical for them.
Two-weeks starvation led to an increase in respiration rates of the blood clam A. kagoshimensis, which indicates an intensification of oxidative processes of organism by 35 ˗ 55%. The article discusses metabolic processes that require increased oxygen consumption.
... In contrast to vertebrates, C. gigas presents an exceptional mitochondrial resilience to temperature, salinity, hypoxia (Sokolova, 2018), and extreme tolerance to hypoxia was related to mitochondria plasticity ability to maintain respiratory capacity in response to oxygen loss (Donaghy et al., 2013;Sokolov et al., 2019;Sussarellu et al., 2012Sussarellu et al., , 2013. C. gigas can survive fasting for more than 6 months at 14 • C (Whyte et al., 1990) and continue sexual maturation under complete food deprivation at 18 • C (Rozenn Cannuel, 2005). C. gigas possesses unique molecular features to respond to environmental changes in its intertidal stressful habitat, based on a combination of strong cellular homeostasis control, a large number of chaperone heat-shock hsp70 genes (88), and several copies of anti-oxidant enzymes (Zhang et al., 2012(Zhang et al., , 2016. ...
The Pacific oyster Crassostrea gigas is established in the marine intertidal zone, experiencing rapid and highly dynamic environmental changes throughout the tidal cycle. Depending on the bathymetry, oysters face oxygen deprivation, lack of nutrients, and high changes in temperature during alternation of the cycles of emersion/immersion. Here we showed that intertidal oysters at a bathymetry level of 3 and 5 m delayed by ten days the onset of mortality associated with Pacific Oyster Mortality Syndrome (POMS) as compared to subtidal oysters. Intertidal oysters presented a lower growth but similar energetic reserves to subtidal oysters but induced proteomic changes indicative of a boost in metabolism, inflammation, and innate immunity that may have improved their resistance during infection with the Ostreid herpes virus. Our work highlights that intertidal harsh environmental conditions modify host-pathogen interaction and improve oyster health. This study opens new perspectives on oyster farming for mitigation strategies based on tidal height.
... To date, assessments of oocyte quality have often been performed retrospectively, through fertilization rates, based on polar body or cell division observations (Uttig and Spencer 1991, Buttner and Weston 2010, Militz and Southgate 2021, analysis of chemical composition, and performance indicators (Caers et al. 1999(Caers et al. , 2002Massapina et al. 1999;Nevejan et al. 2003;Cannuel and Beninger 2005;Corporeau et al. 2012;García-Corona et al. 2018). Histochemical staining of specific oocyte components, in particular lipids, may also yield information on oocyte quality (Valdez-Ramirez et al. 2002). ...
Estimation of realized fecundity (Freal, number of viable oocytes produced) is an essential, yet seldom-achieved element in the understanding of marine animal production and population dynamics. We used the Neutral Red (NR) vital stain to determine oocyte viability in spawns and gonad strippings of four species of commercially-important bivalves: Cerastoderma edule (L), Crassostrea gigas Thunberg, Mytilus edulis L, and Tapes philippinarum (Adams and Reeve). The utility of Trypan Blue as a complementary mortal stain was also assessed, and found to be unnecessary. Normal, live oocytes stained with NR, and were either spherical (mature oocytes) or pedunculated (immature oocytes); atresic/abnormal oocytes also stained with NR, allowing their ready recognition due to their abnormal shapes and cytoplasmic retraction. Dead oocytes did not stain with NR. Across the species studied, a considerable and highly variable proportion of spawned or stripped oocytes was either dead or non-viable; quantitative counts were performed for Cerastoderma edule, the only species for which > 5 spawns occurred. The high level and variability (34–85%) of dead or non-viable oocytes is consistent with a reproductive Red Queen dilemma, in which greater oocyte numbers do not translate to commensurately greater real fecundities, and also with a Sweepstakes Reproductive Success strategy, in which a large range of Freal confronts the considerable variability of intertidal environmental conditions. Neutral Red vital staining is a promising tool for the elucidation and optimization of crucial yet previously intractable aspects of bivalve hatchery production, genetic improvement, restocking, stock management, and conservation.
... Given the considerable cost of abundant feeding during the conditioning of broodstock collected at the end of winter and destined for gamete stripping (the prevalent practice in France), we suggest that feeding be minimal or suppressed altogether when the condition index is favourable." (Cannuel et al 2005). ...
... By no other means than an intimate knowledge of such metabolic mechanisms, will hatchery operators truly be able to dictate when the optimum time to exert microalgal resources on broodstock will be. Cannuel et al. 2005 also raises the strategy of storing oysters before this gamete-building threshold has peaked (Cannuel et al 2005). In this strategy, oysters may be stored in a 'winterperiod' where they would require much less food and could be gradually be deployed for conditioning well-after the natural spawn period was through. ...
... By no other means than an intimate knowledge of such metabolic mechanisms, will hatchery operators truly be able to dictate when the optimum time to exert microalgal resources on broodstock will be. Cannuel et al. 2005 also raises the strategy of storing oysters before this gamete-building threshold has peaked (Cannuel et al 2005). In this strategy, oysters may be stored in a 'winterperiod' where they would require much less food and could be gradually be deployed for conditioning well-after the natural spawn period was through. ...
The Pacific oyster, Crassostrea gigas (Thunberg, 1975) a native to East Asia, has been introduced to many locations all around the world. Recently, the production of aquaculture oysters is the most massive if compared with other bivalves. High demand for the oyster brings researcher interest to develop the research about supply chain topic because that is an essential issue for food security among producer and consumer. The high survival rate for oysters is one consideration for the farmer to straight-line keep the mollusk to harvest in any condition, which is growing well in the warm temperature. The shell length market of the oyster is about 80 shell length mm with a high-quality product. Aquaculture is more reliable to develop the oyster than wild capture because easier to treat, control, and produce reliably to meet market demand. Pacific oyster is profitable and marketable for seafood consumption. Lastly, traceability research should develop in the future for the oyster to reduce the risk of seafood security, waste, and boost the market value of the high-quality product.
... Given the considerable cost of abundant feeding during the conditioning of broodstock collected at the end of winter and destined for gamete stripping (the prevalent practice in France), we suggest that feeding be minimal or suppressed altogether when the condition index is favourable." (Cannuel et al 2005). ...
... By no other means than an intimate knowledge of such metabolic mechanisms, will hatchery operators truly be able to dictate when the optimum time to exert microalgal resources on broodstock will be. Cannuel et al. 2005 also raises the strategy of storing oysters before this gamete-building threshold has peaked (Cannuel et al 2005). In this strategy, oysters may be stored in a 'winter-period' where they would require much less food and could be gradually be deployed for conditioning well-after the natural spawn period was through. ...
... By no other means than an intimate knowledge of such metabolic mechanisms, will hatchery operators truly be able to dictate when the optimum time to exert microalgal resources on broodstock will be. Cannuel et al. 2005 also raises the strategy of storing oysters before this gamete-building threshold has peaked (Cannuel et al 2005). In this strategy, oysters may be stored in a 'winter-period' where they would require much less food and could be gradually be deployed for conditioning well-after the natural spawn period was through. ...
Achieving year-round conditioning and spawning of American Oyster (Crassostrea virginica) is paramount to expanding the production of the Eastern United States' most lucrative mariculture product. Reliable spawning also allows for the continuation of selective-breeding programs which improve genetic lines in regards to meat/shell quality, growth, environmental tolerance and disease resistance. There is much diversity among the many wild oyster lines, each with its own spawning behavior. Small and large scale hatcheries along the US East Coast have developed spawning practices to manipulate the localized spawning behavior of their oysters. It is key to retain as many of these wild genetics as possible, so as to be able to deploy them in future selective-breeding efforts. Though conventional spawning practices will continue to be the production source of oyster larvae, cryopreservation techniques offer much in the way of organizing and storing wild and selected genetics.
... Although glycogen is widely known as a long-term energy reserve in many aquatic invertebrates (Lucas, 1996), several authors also suggested the importance of lipid stored in oocytes during gametogenesis, as energy sources for embryonic and early larval development in bivalve species (Dorange and Le Pennec, 1989;Le Pennec et al., 1990;Massapina et al., 1999;Cannuel and Beninger, 2005;Joaquim et al., 2016). Part of the lipids, like triglyceride reserves, are used to synthesize vitellogenin-like proteins that promote the formation of the yolk (Arcos et al., 2009). ...
Histological and energetic parameters were evaluated seasonally between bivalves from two tidal levels. Results suggest different reproductive patterns between individuals from two contrasting intertidal zones, having also different spawning timing. Females of the lower level spawned in Spring and Autumn while females of the upper level did in Summer with a lower number of oocytes, possibly due to differential food availability between the two intertidal zones. The lipids content in the oocytes did not vary between seasons but varied in the digestive gland, being higher in Autumn – Winter, and suggesting that the digestive gland is a lipid reservoir. The energy density of females was similar throughout the seasons and levels, while in males it varied seasonally. Additionally, energy condition index is proposed as a proxy of stressful conditions, as air exposure time (therefore, to the food availability), mussels from the lower level reached a greater energy condition index than those from the upper level.
... In contrast to vertebrates, C. gigas presents an exceptional mitochondrial resilience to temperature, salinity, hypoxia (Sokolova, 2018), and extreme tolerance to hypoxia was related to mitochondria plasticity ability to maintain respiratory capacity in response to oxygen loss (Donaghy et al., 2013;Sokolov et al., 2019;Sussarellu et al., 2012Sussarellu et al., , 2013. C. gigas can survive fasting for more than 6 months at 14 • C (Whyte et al., 1990) and continue sexual maturation under complete food deprivation at 18 • C (Rozenn Cannuel, 2005). C. gigas possesses unique molecular features to respond to environmental changes in its intertidal stressful habitat, based on a combination of strong cellular homeostasis control, a large number of chaperone heat-shock hsp70 genes (88), and several copies of anti-oxidant enzymes (Zhang et al., 2012(Zhang et al., , 2016. ...
The Warburg effect is one of the hallmarks of cancer cells in humans. It is a true metabolic reprogramming to aerobic glycolysis, allowing cancer cells to meet their particular energy needs for growth, proliferation, and resistance to apoptosis, depending on the microenvironment they encounter within the tumor. We have recently discovered that the Crassostrea gigas oyster can naturally reprogram its metabolism to the Warburg effect. Thus, the oyster becomes a new invertebrate model useful for cancer research. Due to its lifestyle, the oyster C. gigas has special abilities to adapt its metabolism to the extreme changes in the environment in which it is located. The oyster C. gigas is therefore a model of interest to study how the environment can control the Warburg effect under conditions that could not be explored in vertebrate model species.
... In O. edulis, microalgae supplements accelerated spawning and increased the number of larvae produced (Millican & Helm 1994). On the other hand, Cannuel and Beninger (2005) and Ch avez-Villalba, Barret, Mingat, Cochard and Le Pennec (2003) reported that under conditions of food limitation, female C. gigas broodstock maintains oocyte quality but reduces the number of oocytes produced. Our results agreed with these authors, the number of released larvae was significantly reduced in the 3% food ration group in autumn but the quality of larvae was not modified, as suggested by the fact that larval survival rates were not different (Table 2). ...
To establish a reliable protocol for the broodstock conditioning of the oyster Ostrea edulis (Linnaeus 1758) in hatcheries is important to obtain the best number of viable larvae all year even outside the natural season for maturation and spawning. Hatchery production of bivalves depends on their initial gonadal maturation state, which is linked to season and several other factors, such as temperature, daylight, salinity and food supply. Ration and diet composition are important in broodstock conditioning because food availability affects fecundity and gametogenic development. In this work, the effect of food ration on O. edulis conditioning was studied in autumn and winter. The results of this study showed that the broodstock conditioned with a food ration of 6% and 9% produces the highest number of larvae in autumn and winter. These food rations produced rapid gonadal development and larval release in a short period with a similar larval production. The oysters conditioned with a food ration of 3% delayed larval release and produced a significantly lower number of larvae in autumn. In the 9% ration treatment, the percentages of mortality were significantly higher in both autumn and winter. Thus, a 6% food ration is likely to be the most suitable for flat oyster conditioning combined with a gradient of temperature (14–18°C) and a gradient of daylight (8–16 h).
... Previous works on bivalves such as the oysters C. gigas (Ch avez-Villalba, Barret, Mingat, Cochard & Le Pennec 2002;Ch avez-Villalba, Pomier, Andriamiseza, Pouvreau, Barret, Cochard & Le Pennec 2002;Cannuel & Beninger 2005;Fabioux, Huvet, Le Souchu, Le Pennec & Pouvreau 2005), and Crassostrea virginica (Loosanoff & Davis 1952), the scallops Pecten maximus (Duinker, Saout & Paulet 1999;Saout, Qu er e, Donval, Paulet & Samain 1999) and Argopecten purpuratus (Mart ınez & P erez 2003) and the mussels Perna viridis and Dreissena polymorpha (Borcherding 1995;Sreedevi, Uthayakumar, Jayakumar & Ramasubramanian 2014) have studied the influence of several environmental factors such as temperature, photoperiod, food availability, water flow on gonadal development, although many aspects remain unclear. For scallops, photoperiod may be as important as temperature in gonadal development although few studies have been carried out (Sastry 1966;Devauchelle & Mingant 1991;Paulet & Boucher 1991;Duinker et al. 1999;Saout et al. 1999). ...
The production of the flat oyster Ostrea edulis (L.) natural spat in Europe has decreased almost by 60% in the past ten years. Thus, the importance of the production of oyster spat in hatcheries is evident. One of the critical steps in hatchery production is broodstock conditioning, especially difficult in autumn, when gonadal development is in resting period. Conditioning is influence by temperature, photoperiod and nutrition. In this work, the effects of two temperature and three photoperiod regimes on the conditioning of O. edulis were studied for three years by stereological analyses and registering number and dates of spawning and larval yield. Temperature had a positive effect on the gonadal development of O. edulis during conditioning. The percentages of germinal cells in oysters conditioned with a gradient of temperature (14-18°C) were double compared to oysters conditioned at 15°C. Oysters conditioned with longer photoperiods showed higher percentages of germinal cells. There was no interaction between temperature and photoperiod. Spawning was observed in the oysters treated with daylight (8-16 h) ten weeks from the beginning of conditioning. Flat oysters conditioned with 8 h and 8-12 h of daylight delayed the first spawning for a month. Total larval production was higher in the oysters treated with the longest daylight gradient. Gonadal and gametogenic development was a non-synchronic process and the spawning extended for around two months. A protocol for flat oyster broodstock conditioning in autumn by using both a gradient of temperature (14-18°C) and daylight (8-16 h) is proposed.
... Notably, food availability, nutritional quality, temperature, photoperiod and salinity are key aspects affecting oocyte development as well as pollutants and harmful microorganisms (e.g. [17,[23][24]). In addition, oocyte quality can be also affected by poor husbandry practices (e.g. ...
... Compared with fish species, only a small panel of criteria is used to assess quality in bivalves, including gonad color [30], mean eggs size [23], oocyte organic matter and lipid content [23,31]. Unfortunately, all these indicators did not consistently reflect the quality of gametes (e.g. ...
The king scallop Pecten maximus is a high valuable species of great interest in Europe for both fishery and aquaculture. Notably, there has been an increased investment to produce seed for enhancement programmes of wild scallop populations. However, hatchery production is a relatively new industry and it is still underdeveloped. Major hurdles are spawning control and gamete quality. In the present study, a total of 14 scallops were sampled in the bay of Brest (Brittany, France) to compare transcriptomic profiles of mature oocytes collected by spawning induction or by stripping. To reach such a goal, a microarray analysis was performed by using a custom 8x60K oligonucleotide microarray representing 45,488 unique scallop contigs. First we identified genes that were differentially expressed depending on oocyte quality, estimated as the potential to produce D-larvae. Secondly, we investigated the transcriptional features of both stripped and spawned oocytes. Genes coding for proteins involved in cytoskeletal dynamics, serine/threonine kinases signalling pathway, mRNA processing, response to DNA damage, apoptosis and cell-cycle appeared to be of crucial importance for both oocyte maturation and developmental competence. This study allowed us to dramatically increase the knowledge about transcriptional features of oocyte quality and maturation, as well as to propose for the first time putative molecular markers to solve a major bottleneck in scallop aquaculture.
