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1.
The neuropeptide cubifrin-I and its derivative cubifrin-L have recently been shown to be potent substances that induce in vitro oocyte maturation and spawning in the Japanese common sea cucumber Apostichopus japonicus. We have examined the reproductive behavior of A. japonicus in vivo following the injection of cubifrin-L into the body cavity with the aim of determining the practical value of using this peptide to induce spawning in the hatchery setting. The responsiveness of ovarian fragments with oocytes >155 μm in diameter to cubifrin-L in vitro was well correlated with the spawning success induced in vivo by a cubifrin-L injection. Mature sea cucumbers injected with cubifrin-L displayed sequential reproductive behaviors, which comprised climbing up the side wall of the tank toward the water surface, waving of the head, and shedding of gametes. Gamete shedding started about 60 and 80 min after the injection of cubifrin-L in males and females, respectively, and was completed almost simultaneously in the two sexes about 2 h post-injection. Repeated injections of cubifrin-L at intervals of about 10 days successfully induced multiple spawnings in males and females. These results demonstrate that cubifrin-L can be used as an effective inducer of spawning in Japanese sea cucumber cultivation.  相似文献   

2.
用海星鞘神经提取液和二硫苏糖醇对刺参卵母细胞进行了体外人工促熟研究。结果显示,二硫苏糖醇对刺参卵母细胞具有明显的促熟作用。刺参卵母细胞包被在滤泡中发育,卵母细胞通过动物极的卵突起连接到单层细胞构成滤泡膜上,充分发育的卵母细胞处于生发泡期,染色质凝集在核仁周围,处于生发泡期的卵母细胞在海水中不会自发成熟。用二硫苏糖醇处理充分发育的卵母细胞20min,卵母细胞的生发泡开始移动,并锚定在卵母细胞的动物极,继而出现生发泡破裂。此后,减数分裂重新启动,第一、二极体分别排出。但海星鞘神经提取液对刺参卵母细胞没有促熟作用。实验表明,二硫苏糖醇浓度在10-5～10-1mol/L范围内,均可促使刺参卵母细胞发生生发泡破裂,10-2mol/L时诱导卵母细胞成熟率可达90%以上。  相似文献   

3.
We conducted a study to evaluate the effects of holding water temperature on the fecundity and egg quality of photo‐manipulated Atlantic cod broodstock. Adult cod Gadus morhua were distributed among several 25‐m3 tanks. Three separate photoperiods were used for each group to obtain three spawning per year (in May, July and December). While photoperiod was controlled, the temperature was not controlled and followed the ambient seasonal pattern. Due to the uncontrolled seasonal temperature used, each spawning group experienced different temperatures at a particular gonadal developmental stage. Otherwise, all groups were treated the same. Results showed that the May and July spawning groups released significantly more eggs per kg of fish (four and three times more respectively) than the December spawning group. The egg fertilization success and proportion of normal eggs were also higher in the May and July groups. Possible reason for the difference may be that the May and July groups experienced lower temperatures (4–7°C) during oocyte maturation and ovulation than the December group (7–9°C). Our results show the importance of using lower/natural temperatures during oocyte maturation and ovulation to obtain good quality eggs in photo‐manipulated cod broodstock.  相似文献   

4.
In this article, an in vitro investigation was carried out to ascertain the roles of hormones and growth factor in the inductions of oocyte maturation and steroidogenesis of the postvitellogenic follicles in an Indian estuarine grey mullet, Mugil cephalus L. Oocyte maturation was evaluated by scoring the germinal vesicle breakdown (GVBD) percent of the postvitellogenic follicles. All the sex [17α,20β-dihydroxy-4-pregnane-3-one (DHP), estradiol 17β (E2), progesterone (P), 17α-OH progesterone (17-OH-P) and testosterone] and other [bovine-insulin and salmon-calcitonin, human chorionic gonadotropin (hCG), luteinizing hormone (LH) or hCG+DHP] hormones and insulin-like growth factor-I (IGF-I) significantly increased GVBD% in 9 h culture. DHP had a maximum effect (75 %) compared to other effectors. Some effectors (hCG: 82.14 %, LH: 78.94 %, hCG plus DHP: 81.81 %, E2: 80 % and IGF-I: 74.19 %) including DHP (79 %) further increased GVBD% in 15-h culture. All the hormones (except DHP) and IGF-I increased DHP, E2 and testosterone productions by the postvitellogenic ovarian follicles in vitro. DHP and testosterone productions were increased with the increase of incubation time from 9 h through 15 h. E2 production was not further increased beyond 12 h. DHP production was highest by hCG compared to other effectors. The hCG of all the test compounds was most effective in both the induction of GVBD% and steroid production. DHP is the most potent inducer of oocyte maturation in Indian estuarine flat head grey mullet. Involvement of estrogen in mullet oocyte maturation is indicated. hCG, like DHP, is equally potent and induces oocyte maturation via DHP production in vitro. hCG with DHP has synergistic action on oocyte maturation in mullet ovary. Interplay of several hormones (hCG, LH, and probably E2 and testosterone) and IGF-I on oocyte maturation is suggested in the mullet.  相似文献   

5.
Populations of sea cucumbers, including the Japanese common sea cucumber Apostichopus japonicus, have been seriously depleted worldwide due to overfishing. Mark–recapture study is an efficient means of collecting ecological data. However, the use of such a method in sea cucumbers is difficult because they lack hard tissues in the body wall. Here we tested the viability of various tagging methods on A. japonicus. First, we applied conventional tags using four different methods [single spaghetti (T-bar) tagging, double spaghetti tagging, ribbon tagging, and Atkins tagging] to ten individuals per method in aquaria for 14 days. Of the methods used, single spaghetti tagging had the highest retention rate. Then we examined the retention rate of single spaghetti tags on ten individual sea cucumbers for up to approximately 6 months in rearing conditions. The single spaghetti tagging method showed a retention rate of 100% over at least 7 days, and 50% of the tags remained embedded after 56 days. The longest duration of tag retention was 174 days, at which time the experiment was terminated. These results indicate that single spaghetti tagging is reliable for both short- and longer-term studies, making it a useful tool for ecological and conservation studies in sea cucumbers.  相似文献   

6.
Sea cucumber, Apostichopus japonicus, is the main cultured species in China. The main culture style for this species is the sea ranching model. Field trials were conducted in bottom-cages to preliminary reveal optimal releasing size, as well as maximum density of A. japonicus in an integrated multi-trophic aquaculture sea ranching area. Different sizes (4–30 g ind?1) and densities (336–1342 g m?2) of sea cucumbers were cultured for 13 months in Rongcheng Bay, Shandong Province, China. The size experiment showed that sea cucumber of all sizes grew throughout the experimental period. Sea cucumbers <15 g had high mortality in summer and low SGR in winter, while larger individual (>20 g ind?1) had no advantage of growth. Sea cucumber sizes of 15–20 g may be suitable for release, considering their higher survival rate and SGR. The density experiment showed that the high biomass group had a low SGR and that the maximum release biomass was 793 g m?2 based on a regression analysis. The optimal practical release season for sea cucumber was spring based on the results of two field experiments.  相似文献   

7.
The behavior of juvenile yellowfin tuna Thunnus albacares in southwestern Japan was investigated using archival tag data from five fish (fork length 52.5–92 cm, days at liberty 26–280 days) released near the Nansei Islands (24–29°N, 122–130°E). Vertical behavior was classified into three patterns: “shallow” (≥50 % of daytime hours at depth of <50 m), “deep” (≥50 % of daytime hours at ≥100 m), and “intermediate” (other than “shallow” or “deep”). The pooled proportion of the number of days of each behavior was 29, 25 and 46 %, respectively. The proportion of “shallow” behavior increased with fish size. The proportion of time spent near the surface at nighttime increased in the colder season, when the thermal gradient was relatively small. Surface-oriented behavior (fish remained at a depth of <10 m for more than 10 min) occurred mainly during nighttime and between November and January. Dives exceeding 500 m were occasionally observed (0.02 day?1), and one fish dived to 1230 m. The results of our study show that yellowfin tuna were typically distributed in the mixed layer or upper thermocline where the water temperature was close to the sea surface temperature and that the vertical behavior was variable.  相似文献   

8.
The efficacy of four chemical reagents, iodophor, formalin, hydrogen peroxide and bronopol as fish egg surface disinfectants were evaluated in bluefin sea bream (Sparidentex hasta). Fertilized eggs were counted and subjected to a static bath dip treatment in different concentrations of the above chemicals for 4 min before being incubated at 20 ± 0.5°C for 40 h. Treatment efficacy of the different disinfectants was evaluated by assessing the bactericidal activity, egg hatch percentage and survival of larvae up to 3 days post hatch. Results showed that iodophor at medium concentrations (75 and 100 ppm) was the best of all tested disinfectants in bacterial killing ability (12% reduction in the bacterial counts), egg hatching per cent (99.8% and 99.6% respectively) and larval survival up to 3 days post hatch (50.8% and 54.8% respectively). Formalin was the second best disinfectant at levels of 100 and 150 ppm. Hydrogen peroxide gave good results compared with the control while, bronopol showed discouraging results. In conclusion, iodophor appeared to be suitable for bluefin sea bream eggs disinfection with a 4 min exposure to 75–100 ppm when applied 14–16 h after egg fertilization.  相似文献   

9.
Pikeperch, Sander lucioperca (L.), has been identified as one of the most perspective candidates for diversification of freshwater aquaculture. However, some aspects of production are still being developed, and controlled reproduction is one of the bottlenecks. The aim of the present study was to compare the effectiveness of different commercial spawning agents in the induction of final oocyte maturation (FOM) and ovulation in wild spawners. Within the study, four spawning agents [human chorionic gonadotropin (hCG), mixed human and horse gonadotropin (PG-600), carp pituitary (CPH) and mammalian GnRH analogue combined with metoclopramide (Ovopel)] in different thermal regimes (13 and 15 °C) were tested. In both thermal regimes, the highest (P < 0.05) ovulation rate among the treatment groups was obtained after stimulation with hCG (100 % in both cases). Latency time was the shortest in groups where CPH was used (2–3 and 3–4 days for 15 and 13 °C) and was similar in the remaining groups (3–4 and 4–5 days for 15 and 13 °C, respectively). Embryo survival was the highest in groups treated with hCG (78.9 and 81.3 % at hatching stage for 15 and 13 °C, respectively). Hormonal stimulation did not significantly affect spermiation rate or spermatozoa motility (P > 0.05). Based on the obtained results, hCG can be recommended for induction of FOM and ovulation in pikeperch. In addition, the thermal regime within the tested range seemed to have no effect on the reproduction outcome, and the application of lower temperature only prolonged the time of ovulation.  相似文献   

10.
The worldwide demand for sea cucumber is outpacing the sustainable harvest capabilities of fisheries. Sea cucumber ranches and farms are striving to supplement wild harvest, but variable temperature and salinity conditions in pond culture systems make sea cucumber production challenging. In this study, we evaluated how water temperature, salinity and body size affected the energy budget of pond-cultured sea cucumber Apostichopus japonicus Selenka. An orthogonal design was used to identify the most suitable conditions for energy consumption and scope for growth (SFG). After the 42-day experimental period, we found that water temperature, salinity and body size significantly influenced energy consumption, while salinity and body size were the main influencing factors on SFG. Based on these results, we suggest that a water temperature of 16 °C and a salinity of 30 g L?1 are optimal conditions for stocking sea cucumber A. japonicus with a body size of 37.34 ± 4.63 g. As such, the optimum stocking seasons for sea cucumber A. japonicus may be April in the spring and October in the autumn.  相似文献   

11.
Eggs of the Japanese eel Anguilla japonica collected in the western North Pacific were identified by onboard species-specific polymerase chain reaction (PCR) and DNA nucleotide sequencing after the cruise. Fish eggs of various species were collected by large plankton net tows at 12 stations along the southern part of the West Mariana Ridge on 19–25 May 2009. A total of 43 fish eggs were distinguished morphologically as possibly being of A. japonica. Thirty-one of those were analyzed by PCR, which included 15 eggs collected at 12°50–55′N, 141°15–20′E (in 5 tows) that showed positive results. The 16S ribosomal RNA (rRNA) gene sequences of eggs determined after the cruise indicated that 31 A. japonica eggs had been collected. The remaining eggs were of mesopelagic eel species (Serrivomeridae and Derichthyidae), or unidentified species. The morphological characteristics of the A. japonica eggs were consistent with those of artificially spawned eggs, except they had a slightly larger diameter. The egg diameter range did not overlap with those of mesopelagic eels of the Serrivomeridae, which often spawn in the same area as A. japonica. These results suggest that egg diameter and embryo shape can be used to morphologically identify naturally spawned A. japonica eggs.  相似文献   

12.
For recovery of the declining population of pen shells in the wild, the production of pen shell juveniles for transplantation or aquaculture is underway in Japan. For more stable juvenile production, artificial fertilization methods for pen shells are needed, but methods to induce oocyte maturation (meiosis resumption) used in other bivalves, which make oocytes fertilizable, were ineffective for pen shells. Here, we report evidence showing that retinoic acid (RA) has strong activity in inducing oocyte maturation and activating sperm motility in pen shells. Treatment of fully developed oocytes with 1.0 μM all-trans-RA (at-RA) induced germinal vesicle breakdown, a typical morphological sign of oocyte maturation, but 1.0 μM at-retinol and at-retinal, 2 mM ammonia, and 1.0 μM serotonin were ineffective. Treatment with at-RA for 30 min was sufficient for oocyte maturation and was more potent than its isomers, 9-cis- and 13-cis-RA. Parallel results were obtained for sperm motility activation. Oocyte responsiveness to at-RA increased during the final stage of ovary development. Artificial fertilization was successful only with the oocytes treated with at-RA, and fertilized eggs developed to D-shaped (veliger) larvae without apparent morphological abnormalities. These results indicate the possible application of RA for the artificial fertilization of pen shells.  相似文献   

13.
We surveyed the distribution of red sea bream eggs between 2006 and 2010 in the east Seto Inland Sea to determine the location of the spawning grounds and the characteristics of preferred spawning habitats. We identified early-development stage red sea bream eggs using a monoclonal antibody assay. The early-development stage eggs were present in waters around Awaji Island (AW area) and around Ieshima Island, Shodo Island, and Bisan Seto (collectively the ISB area). The mean red sea bream egg density in the AW area was not significantly different from that in the ISB area. Based on the locations where we observed early-development stage eggs and the density of eggs, the ISB and AW areas appeared to be the primary spawning grounds in the east Seto Inland Sea during the survey period. A quotient analysis suggested that spawning fish had clear preferences for physical conditions. The areas suitable for spawning appear to be those with sandy substrate at a depth of 30–70 m. The temperature range suitable for spawning was between 16.5 and 21.5 °C.  相似文献   

14.
One of the most important periods in artificial breeding of sturgeon is incubation. In general, little is known about ontogeny of the stress response in early developmental stages of sturgeon. In this study, cortisol content was measured by radioimmunoassay for the first time in eggs of Persian sturgeon Acipenser persicus to elicit at which times during early developmental stages, that they were particularly sensitive to stressful events. In this study, fertilized eggs of mature Persian sturgeons were placed in special boxes (as replicates) that were put in incubation units of Yushchenko. To assess pre-stress samples (resting cortisol levels), 5 eggs were selected randomly from each box in 7 important stages of incubation (2-cell division, blastula, end of blastula, mid of gastrula, neurula, eyed stage and heart beaten). In another experiment, eggs were exposed to an acute stress (10 min out of water) in 7 developmental stages. For determination of post-stress cortisol, eggs were collected 2 and 6 h after the stress. The results indicated significant difference in various stages of incubation but cortisol levels revealed no differences in whole-body levels between stressed samples (2 and 6 h post-stress) and unstressed samples (P > 0.05). The highest percentage of hatching rate for post-stressed eggs was recorded in 2-cell division stage while this percentage declined steadily in the heart beaten stage when a statistically significant difference was revealed with regard to other stages (P = 0.000). These findings suggested that sturgeon eggs were not so much sensitive in their early developmental stages and relatively resistant to stress. However, significant decrease in survival rate in heart beaten stage showed a sensitivity of this stage to stress. Lack of an increase in cortisol after acute stress indicated that hypothalamus-pituitary-interrenal (HPI) axis for cortisol synthesis was not yet functional. However, further studies seem necessary to clarify when HPI axis is activated in this species.  相似文献   

15.
A 60-day feeding trial was conducted to determine the effects of palm oil blended with oxidized and non-oxidized fish oil on growth performances, hematology, and non-specific immune response in juvenile Japanese sea bass, Lateolabrax japonicas. Japanese sea bass (1.73 ± 0.01 g) were fed seven experimental diets containing 100 g/kg of dietary lipid in forms of palm oil (10P), fish oil (10F), fish oil blended with palm oil at different ratios, 6:4 (6F4P) and 4:6 (4F6P), oxidized fish oil (10OF), and oxidized fish oil blended with palm oil at different ratios, 6:4 (6OF4P) and 4:6 (4OF6P). After the feeding trial, the following results were illustrated. No significant effects were observed in survival, feed conversion ratio, condition factor, and hematocrit after feeding with experimental diets for 60 days. The relatively higher specific growth rate and hematology were observed in 6F4P. Furthermore, both palm oil and oxidized fish oil acted as a negatively on serum lysozyme activity (P < 0.05). This study suggested that a ration of 6F4P is recommended as an innocuous ratio for Japanese sea bass. Furthermore, according to the present investigation, palm oil seems to have the ability to improve the protein efficiency when added to oxidized fish diets as well as a positive trend to the growth performance (P > 0.05).  相似文献   

16.
Different durations of a cytochalasin B (CB) treatment were tested for tetraploid induction by meiosis inhibition in the dwarf surfclam Mulinia lateralis Say. Cytochalasin B, 0.67 mg L?1, was applied to newly fertilized eggs at 8–10‐min post fertilization and removed when in the untreated eggs: (1) Polar body 1 (PB1) was released in 90% of the eggs and polar body 2 (PB2) began to form (T1); (2) Polar body 2 was released in about 25–30% of the eggs (T2); (3) Polar body 2 was released in about 70–75% of the eggs (T3); or (4) eggs began to enter mitosis I or the polar lobe began to form (T4). Three replicates were produced using different sets of parents. The ploidy of resultant larvae and juveniles was determined by flow cytometry. Blocking PB1 alone in T1 groups produced mostly tetraploids, and longer CB treatments in T2 and T3 resulted in increasing numbers of pentaploids. In T4 groups where both PB1 and PB2 were inhibited, larvae were predominantly pentaploids. Pentaploid larvae were arrested at the trochophore stage. The majority of tetraploid larvae died as trochophores, although a small fraction reached D‐stage. Among 478 juvenile clams sampled from a T1 group, three (0.6%) were confirmed as tetraploids. This study shows that tetraploid embryos can be produced at high efficiencies (40–90%) by blocking meiosis I. Tetraploids produced by meiosis inhibition in normal eggs are viable in M. lateralis, but their survival beyond metamorphosis is extremely low.  相似文献   

17.
To determine whether marine mud substrate is suitable for sea cucumber aquaculture, we studied the effects of sea mud on the behavioral characteristics, growth and survival of Apostichopus japonicus, in both the field and laboratory. Our results showed that sea mud is beneficial for the growth of A. japonicus, but was unfavorable for its locomotion and attachment when a water current was present. In the field experiment in Yuehu lagoon, juvenile A. japonicus preferred to inhabit the base of seaweeds or dead leaves, which provide a favorable substrate for both their locomotion and ingestion. The mud substrate was not suitable for the small juveniles to inhabit; therefore, >3.25 g ind?1 is the preferred size for bottom-sowing culture of sea cucumbers on the seabed in a field environment such as the Yuehu lagoon. Water current is a key factor influencing sea cucumber distribution on the bare mud substrate, with 90 % of juvenile sea cucumbers (<40 g ind?1) being unable to keep still in a current speed of 0.115 m s?1 for 10 min. In conclusion, a mud substrate is suitable for A. japonicus aquaculture, although hard substrates or shelters are a prerequisite for successful rearing. The water current is a key factor that influences substrate selection by A. japonicus and, thus, is an important factor to be considered in the bottom-sowing culture of these organisms.  相似文献   

18.
Reduction in eel resources and catches of glass eels as seedlings for aquaculture have been a serious concern in recent years in both Europe and East Asia. Thus, technical advancement to produce eel seeds for artificial cultivation is most desired. Fundamental information on oocyte maturation and ovulation and its application to artificial induction of sexual maturation are needed to produce good quality seeds of the Japanese eel. This review introduces hormonal mechanisms of cytoplasmic maturation (such as hydration, lipid coalescence, and clearing of the ooplasm) and the maturational competence (the ability to respond to maturation-inducing steroid) and nuclear maturation (germinal vesicle breakdown). In addition, previous and newly developed methods for induction of spawning have been described.  相似文献   

19.
Intensive and semi-intensive sea cucumber aquaculture produces effluents that impact the quality of the local aquatic environment and sea cucumber growth; such effluents are an important cause of coastal water eutrophication. Integrated aquaculture has been shown to efficiently reduce the release of nutrients during aquaculture and to provide economic benefits. In this study, we report our investigation of a polyculture system utilizing Styela clava (stalked sea squirt) and Stichopus japonicus (Japanese sea cucumber) under two feeding modes. To examine purification of the water in the system, nutrients in the water and the sediment, attached heterotrophic bacteria, and the survival rates and growth rates of S. clava and S. japonicus were determined. Tank cultivation trials showed that, under the same feeding modes, the concentration of nutrients in the polyculture system was approximately 50–60 % of the sum of the nutrients in the S. japonicus mixture and S. clava monoculture systems. The abundance of attached heterotrophic bacteria in the polyculture system was remarkably lower than that of the mixed culture system under the same feeding mode. S. japonicus in the polyculture system grew better than those in the mixed culture system under the same feeding mode. These results demonstrate that the S. clava–S. japonicus integrated culture system offers a means of constraining or reversing the pollutive impacts of coastal sea cucumber aquaculture.  相似文献   

20.
This study aimed to describe the response variability of female silver eels in terms of gonad development and eggs production to a standardized gonadotropic treatment (Carp pituitary extracts—CPE), and to relate this variability to population characteristics. For this purpose, sexual maturation, ovulation, and fertilization were induced in two eel populations coming from different locations in Adriatic Sea (Comacchio—CM and Marano-Grado—MG lagoons), and after that, their reproductive capacity was valuated. External (Silver index—SI, Eye index—EI, Pectoral fin length index—PFLI, Condition factor—K) and hormonal (17β-estradiol—E2, testosterone—T) parameters were measured, and some subject/group were killed for histological and lipid analysis and age determination. Morphometric parameters showed the CM-Group to have highest values of Body weight (BW), Body length (BL), and K, while MG-Group presented highest PFLI and Gonadosomatic index (GSI) values. Regarding hormonal analysis, the CM-Group showed significantly higher T and E2 levels than the MG-Group, both groups showed considerably rapid increase at T5 (5th injection). A positive trend in gonadal development was found through histological evaluation; a more regular maturation was observed in the MG-Group, whereas the CM-Group presented an exponential oocytes development starting from T10 (10th week), which led to an anticipated spawning. Lipid content showed significant differences in T0 (start study), post-ovulation, and Control (30th week) between CM and MG eels. As to zootechnical performances, while MG eels released spontaneously into the water, the CMs were stripped in order to check ovulation. The MG eels were statistically the most productive with 40.1 ± 6.33 % BW of eggs released. Furthermore, CM females ovulated mainly between the 19th and 22nd week (77.8 % spawned eels) instead in the MG’s ovulation goes from the 24th to the 28th week (100 % spawned eels). As fertilization is of concern, in both groups fertilized eggs were obtained with no difference in larvae production. These results seem to indicate that bigger dimensions, higher K, and larger lipid content (Comacchio eels) could fasten gonadic maturation without positively influencing reproductive performance of animals, both in term of quantity and quality of produced eggs. Smaller females with a highest SI (Marano-Grado eels) presented a more regular gonadic development, leading the animals to spontaneous spawning.  相似文献   

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