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1.
Kisspeptin(简称Kiss或者Kp)是由KISS1/Kiss1基因编码的一种下丘脑神经肽,通过其受体KissR(也称作GPR54)的介导参与了多种生理过程,如抑制肿瘤转移和参与生殖调控。目前,尽管在鲤形目(Cypriniformes)、鲈形目(Perciforms)、鲽形目(Pleuronectiforms)、鲀形目(Tetraodontiforms)、颌针目(Beloniforms)、鲉形目(Scorpaeniformes)、鲑形目(Salmoniformes)及鳕形目(Gadiformes)等多种鱼类中均鉴定出了kiss/kissr基因,但Kiss/KissR系统在鱼类生殖调控中的精确作用及其分子机制尚未完全阐明。尤其是在鱼类中存在2种kiss及3种kissr基因,Kiss/KissR系统对鱼类生殖调控的作用方式更加复杂。本文简要总结鱼类Kiss及其受体的研究进展,并对Kiss的生理学功能、信号转导机制以及kiss/kissr表达调控研究进行概括讨论,旨在加深对鱼类Kiss/KissR系统的认识和了解,为后续研究指明方向。  相似文献   

2.
Abstract:   The question of whether the ovulation and spawning time in chub mackerel Scomber japonicus is entrained by a circadian rhythm was raised by our previous experiments. Further questions were also raised about whether the time course of human chorionic gonadotropin (hCG)-induced final oocyte maturation (FOM) and ovulation reflected the natural time course induced by endogeneous pituitary gonadotropin (GtH). To address these questions, hCG and gonadotropin-releasing hormone analog (GnRHa) were administered at two 'opposite' times, 14:00 and 02:00 hours, and the time courses of FOM and ovulation were compared. When hCG was injected, ovulation occurred 33 h post-injection in both groups, regardless of the timing of the hCG injection. The timing of ovulation in chub mackerel depends on the timing of hCG injection, but apparently not on circadian rhythms. When GnRHa was injected, ovulation began at 36 h post-injection of GnRHa, regardless of the timing of injection. These results indicate that the time course of FOM and ovulation in the chub mackerel followed a similar pattern whether stimulated by hCG injection or spontaneous luteinizing hormone (LH) surge because GnRHa induces the secretion of endogenous GtH (primarily LH) from the fish pituitary. Thus, it is concluded that the time course of hCG-induced FOM and ovulation in chub mackerel follows the natural time course induced by endogenous pituitary LH.  相似文献   

3.
Gonadotropin (GTH) hormones are glycoprotein which stimulates gonadal maturation in vertebrates. Follicle stimulating hormone is involved in initiation of gametogenesis and regulation of gonadal growth. FSHβ has been cloned and characterized from the brain of Catla catla. The FSHβ full‐length of cDNA sequence of 523 bp comprised 3, 394 and 128 bp of 5′‐UTR, open reading frame (ORF) 3′‐UTR respectively. The coding region of C. catla FSHβ encoded a peptide of 130 amino acids. Phylogenetic analysis of C. catla FSHβ deduced amino acid sequence showed high similarity with Gobiocypris rarus followed by goldfish, Carassius auratus. The qPCR result shows that FSHβ mRNA is mainly expressed in pituitary while moderate and low expression was observed in testis and ovary respectively. Chitosan‐nanoconjugated kisspeptin‐10 (CK‐10) of particle size 125 nm, polydispersity index of 0.335 to 0.65 and zeta potential of ?34.95 mV were synthesized and evaluated at against naked kisspeptin‐10 for their reproductive hormonal profile. Treatment of fish with CK‐10 showed controlled and sustained surge of the reproductive hormones (FSH & LH) with peak at 12 h. The hormone levels of naked kisspeptin‐10 treated fish decline after 6 h. The sustained release of this CK‐10 will help in reducing maturation age, synchronization of ovulation and spawning in fish. This is the first report on use of chitosan‐nanoconjugated kisspeptin‐10 (CK‐10) for reproduction in fish.  相似文献   

4.
Production of sufficient high‐quality eggs of greater amberjack (Seriola dumerili) still constitutes the main bottleneck for commercial production of this species. The main objective of this study was to compare the quality of spontaneous spawn of greater amberjack with those obtained by either GnRHa injection or GnRHa implant protocols. Captive amberjack broodstock were distributed in three circular tanks of 40 m3. Broodstock from Tank 1 were not hormonally induced and spawned spontaneously, whereas those of Tank 2 were intramuscularly injected with GnRHa (20 µg/kg body weight) and those of Tank 3 were given EV‐500 µg GnRHa implants. The number of eggs per spawn obtained in the broodstock without hormonal treatment was larger than in those obtained with injections or implants. Egg quality was best in broodstock with spontaneous spawn, followed by GnRHa‐injected fish and then GnRHa implants. Besides, size of larvae from control and injected broodstock was similar between them and significantly higher (p < 0.01) than those from GnRHa implant spawn. Overall, this study showed that it is possible to obtain very high‐quality spontaneous spawn in greater amberjack, providing the adequate conditions. Furthermore, GnRHa weekly injections lead to similar egg viability and hatching rates than spontaneous spawn and higher fertilization rates than GnRHa hormonal implants, which is better than in previous studies.  相似文献   

5.
The endocrine regulation of reproduction in a multiple spawning fish with an asynchronous-type ovary remains largely unknown. The objectives of this study were to monitor changes in the mRNA expression of three gonadotropin (GtH) subunits (GPα, FSHβ, and LHβ) during the reproductive cycle of the female chub mackerel Scomber japonicus. Cloning and subsequent sequence analysis revealed that the cDNAs of chub mackerel GPα, FSHβ, and LHβ were 658, 535, and 599 nucleotides in length and encoded 117, 115, and 147 amino acids, respectively. We applied a quantitative real-time PCR assay to quantify the mRNA expression levels of these GtH subunits. During the seasonal reproductive cycle, FSHβ mRNA levels remained high during the vitellogenic stages, while GPα and LHβ mRNA levels peaked at the end of vitellogenesis. The expression of all three GtH subunits decreased during the post-spawning period. These results suggest that follicle-stimulating hormone (FSH) is involved in vitellogenesis, while luteinizing hormone (LH) functions during final oocyte maturation (FOM). Both GPα and FSHβ mRNA levels remained high during the FOM stages of the spawning cycle and increased further just after spawning. Thus, FSH synthesis may be strongly activated just after spawning to accelerate vitellogenesis in preparation for the next spawning. Alternatively, LHβ mRNA levels declined during hydration and then increased after ovulation. This study demonstrates that chub mackerel are a good model for investigating GtH functions in multiple spawning fish.  相似文献   

6.
As a crucial step in developing a bioenergetics model for Pacific Chub Mackerel Scomber japonicus (hereafter chub mackerel), parameters related to metabolism, the largest dissipation term in bioenergetics modelling, were estimated. Swimming energetics and metabolic data for nine chub mackerel were collected at 14°C, a low temperature within the typical thermal range of this species, using variable‐speed swim‐tunnel respirometry. These new data were combined with previous speed‐dependent metabolic data at 18 and 24°C and single‐speed (1 fork length per second: FL/s) metabolic data at 15 and 20°C to estimate respiration parameters for model development. Based on the combined data, the optimal swimming speed (the swimming speed with the minimum cost of transport, Uopt) was 42.5 cm/s (1.5–3.0 FL/s or 2.1 ± 0.4 FL/s) and showed no significant dependence on temperature or fish size. The daily mass‐specific oxygen consumption rate (R, g O2 g fish?1 day?1) was expressed as a function of fish mass (W), temperature (T) and swimming speed (U): R = 0.0103W?0.490 e(0.0457T) e(0.0235U). Compared to other small pelagic fishes such as Pacific Herring Clupea harengus pallasii, Pacific Sardine Sardinops sagax and various anchovy species, chub mackerel respiration showed a lower dependence on fish mass, temperature and swimming speed, suggesting a greater swimming ability and lower sensitivity to environmental temperature variation.  相似文献   

7.
Decadal changes in northern fur seal (Callorhinus ursinus) diet were examined based on the stomach contents data collected off the Pacific coast of northeastern Japan from January to April, 1953–1988. Seventeen families of fish and seven families of squid were identified from the stomach contents. Dominant prey species in terms of percentage of occurrence and wet weight were Japanese sardine (Sardinops melanostictus), chub mackerel (Scomber japonicus), and myctophid fishes. Demersal fishes, sparkling enope squid (Watasenia scintillans), and oceanic squids were also preyed on at low incidences. Decadal‐scale diet composition of northern fur seals revealed shifts in the significance of Japanese sardine and chub mackerel in parallel with the decadal alternation in the dominance of these species within the pelagic fish community off the Pacific coast of northeastern Japan. These results suggest that northern fur seals can use a variety of prey resources in this wintering area by switching the diet according to the distribution and abundance of prey species.  相似文献   

8.
To optimize broodstock management for Seriola rivoliana, a survey over 5 years was performed to evaluate the effects of successive hormonal inductions with GnRHa or dietary regime on spawning quality. Running males and females with an oocyte diameter > 500 μm were injected with GnRHa. The spawning quality was compared among consecutive years and different moments along the spawning season. Besides, three different feeding regimes were tested. Spawning quality parameters were not significantly affected by time along the spawning season, whereas they were clearly influenced by diet. Particularly, broodfish fed the mackerel regime (M) showed a significantly higher number of eggs than other treatments. Besides, dietary protein content significantly improved broodstock fecundity of S. rivoliana. Moreover, hatching rates were also higher in broodfish fed mackerel and the dietary docosahexaenoic acid (DHA) levels significantly increased this parameter. Despite polar lipids were not significantly affected, neutral lipids fatty acid composition of S. rivoliana eggs showed higher 18:2n‐6 in eggs, whereas ARA content was not affected. The results of this study denoted the high fecundity and good spawning quality of S. rivoliana broodfish and suggested the importance of high protein, energy and DHA levels in broodstock diets.  相似文献   

9.
In the present study, we assessed small fishes as potential feed fishes with the lowest mercury levels. The mercury levels of four small pelagic fishes and a benthic fish from the Pacific Ocean and the Sea of Japan, i.e., spotted chub mackerel Scomber australasicus, chub mackerel Scomber japonicus, horse mackerel Trachurus trachurus, round scad Decapterus punctatus, and bastard halibut Paralichthys olivaceus, were determined. Total mercury levels in fish muscle were measured using a reduction vaporizing atomic absorption method. There were no significant correlations between body weight and mercury levels for these species. However, significant differences were observed in the mercury levels of these species between the two catch locations, with fish caught in the Pacific Ocean having higher mercury levels. This difference may be due to the Pacific Ring of Fire, a highly seismically and volcanically active zone, which is located in the Pacific Ocean. Preference for these fishes for use in aquaculture should refer to the area where they are caught in addition to the species.  相似文献   

10.
A paradigm of proportionality between spawning stock biomass (SSB) and total egg production (TEP) has been largely untested at multidecadal scales mainly because of difficulty in estimating annual TEP. Recently, this paradigm was directly tested for sardine (Sardinops melanostictus) and anchovy (Engraulis japonicus) at a multidecadal scale to reveal that SSB–TEP proportionality was partially distorted by intraspecific (sardine) and interspecific (anchovy) density dependence in total egg production per spawner individual (TEPPS) or unit weight (TEPPSW). In the present study, we demonstrate intraspecific density dependence in TEPPS/TEPPSW for chub mackerel (Scomber japonicus) in the Kuroshio Current system, using a proxy for TEPPS/TEPPSW, calculated from snapshot abundance data based on fishery‐independent egg surveys in combination with fishery‐dependent stock assessment data, at a multidecadal scale (38 years). TEPPS/TEPPSW exponentially declined with SSB, indicating a strong intraspecific density dependence in TEPPS/TEPPSW in chub mackerel. The observed phenomenon for chub mackerel was similar to that for sardine. Hence, intraspecific density dependence in TEPPS/TEPPSW may be a phenomenon that is generally applicable for species with a high maximum biomass and large population fluctuations. Lastly, we recommend the application of a TEP‐based framework to studies on recruitment mechanisms of fish.  相似文献   

11.
Although chub mackerel (Scomber japonicus) is widely distributed all over the world, the relevance of its visual sensitivity to its ecology is not yet fully understood. We investigated spectral sensitivity in juvenile chub mackerel in the range of ultraviolet (UV) to visible light (369–652 nm) by electroretinogram (ERG) using light-emitting diodes (LEDs). Sensitivity peaked at a wavelength of approximately 482 nm in dark-adapted fish and 525 nm in light-adapted fish. A secondary sensitivity peak in the UV range at approximately 382 nm was found in both dark- and light-adapted fish. The UV sensitivity of chub mackerel may be attributable to UV transmissibility of the optical media and to the presence of a beta-band of visible light-sensitive visual pigments, and not to an alpha-band of UV visual pigments. This UV sensitivity may be useful for feeding or communication with other fishes.  相似文献   

12.
Chub mackerel (Scomber japonicus Houttuyn) is one of the most commercially important scombroid fish used as a food resource. Recently, there has been a demand for efficient rearing methods of this fish for a full‐life cycle aquaculture. In the present study, we evaluated the physiological responses in the juvenile S. japonicus to different ambient salinities. A significantly higher gain of the body mass was observed in the juveniles reared in 24 g/L and 13 g/L seawater than in those reared in natural seawater (34 g/L) within 40 days of the experimental period without affecting mortality. A principal enzyme for osmoregulation, Na+/K+‐ATPase, was expressed in the ionocytes located in the gill filaments of the juveniles. The number and the cell size of ionocytes and the enzymatic activity of Na+/K+‐ATPase in the gills decreased within 10 days after the low‐salinity challenge, which implies the reduction of the energy‐consuming active ion secretion under the low‐salinity environment. The physiological capacity for adaptation to low‐salinity seawater in chub mackerel could be basic knowledge to carry out culturing of these fish in coastal sea pens where ambient salinity fluctuates. The improvement of the growth performance by rearing in low‐salinity seawater will contribute to the efficient production of the seed juveniles for aquaculture.  相似文献   

13.
为描述东海中部鲐鱼资源的健康状况,反映鱼类所遭受的外界压力情况,基于2009-2010年在东海中部捕获的鲐鱼的叉长和体质量数据,通过建立鲐鱼的标准体质量,计算得到东海中部鲐鱼的相对体质量指数值。根据叉长和体质量对数中值建立的标准体质量方程为:lgms=0.104574L2+2.945479L-2.014981。相对体质量与叉长的分布情况显示,当叉长小于10cm时,相对体质量指数为45~166,而当叉长为15cm时,相对体质量指数变化范围较小,为82~109。虽然在叉长小于10cm或叉长在20cm时,相对体质量指数的变动性较大,但其频率趋于正态分布。东海中部鲐鱼相对体质量指数的计算为不同海域间鲐鱼资源的相互比较研究提供了便利,也为今后更全面、准确地了解该研究海域鲐鱼群体的资源状况提供了研究基准。该指数不受体长大小所引起的误差的影响,能够较准确地在具有不同时空特征以及来自不同种群的鱼类个体之间进行相互比较,从而能够更好地为鲐鱼资源的开发与管理提出科学建议。  相似文献   

14.
东海鲐鱼资源合理利用的研究   总被引：4，自引：3，他引：4  
利用1970~2006年每年取样鲐鱼所得叉长体重组构成资料,重点分析了70、80、90年代的鲐鱼生物学表征;并结合我国围网捕捞的发展变化情况,应用体长结构实际种群分析法(LVPA)对各个年代的鲐鱼捕捞死亡系数(F)做了分析对比,研究显示,东海区日本鲭F由70年代的0.68上升为90年代的1.60,开发利用程度在不断地加大中。根据1990年以来的日本鲭渔获量资料,估算了1990~2001年东海区日本鲭资源量,结果表明,东海区日本鲭年平均资源量在(73.34~116.88)×104t之间波动。以LVPA法估算所得的90年代鲐鱼F值和最小开捕叉长的数据,利用B-H动态综合模型估算了不同渔业条件下的单位补充量渔获量(Y/R)的变化,结果显示,以目前的捕捞强度,日本鲭的开捕年龄从0.25龄提高为1.22龄,即最小开捕叉长由185 mm调整为247.61 mm,Y/R可提高15.1%,具有一定增产潜力。建议在实际渔业中,渔期适当推迟,禁止利用日本鲭幼鱼。  相似文献   

15.
ABSTRACT:   Final oocyte maturation and ovulation of captive chub mackerel Scomber japonicus with fully yolk-accumulated oocytes were induced by a single injection of human chorionic gonadotropin. Reproductive parameters, including spawning frequency and batch fecundity, which are required to estimate spawning biomass in pelagic fish by the daily egg production method, were analyzed. Germinal vesicle migration (GVM) occurred at 18–24 h post-injection, and the hydration and ovulation of oocytes were completed at 30 and 36 h post-injection, respectively. The results of the maturation process suggest that fish with GVM-stage ovaries captured in the daytime from the field are capable of spawning on the night following their capture. The oocytes used in the oocyte size-frequency distribution method for batch fecundity estimates should be at late GVM and more advanced stages. The results of sequential artificial insemination showed that the quality of ovulated eggs held in the ovarian lumen rapidly deteriorated as time progressed after ovulation. This indicates that the fertilization window for the ovulated eggs of chub mackerel lasts only a few hours, and spawning behavior should be performed within a few hours after ovulation in the wild population.  相似文献   

16.
To induce synchronized ovulation, migrating wild Caspian brown trout (Salmo trutta caspius) females were treated with two interperitoneal injections of Des‐Gly10, d ‐Ala6 LHRH (LHRHa), given 3 days apart. Two injections of 100 μg kg?1 body weight of this hormone effectively induced ovulation. Within 27 days from the second injection, all fish injected with 100 μg kg?1 LHRHa had ovulated compared with 54.5% of the controls. The mean time to ovulation was reduced significantly (P<0.05) from 31.67±4.84 days in control fish and 28.83±7.31 days in sham‐treated fish to 16.36±1.61 days in fish injected with 100 μg kg?1 LHRHa. The fertilization rate in 50 and 100 μg kg?1 LHRHa‐injected fish was significantly lower than that in the control fish (P<0.05). In fish injected with 50 and 100 μg kg?1 LHRHa, significant (P<0.05) changes in testosterone (T) and 17α‐hydroxyprogestrone (OHP) levels were observed. After the second LHRHa injection, the fish injected with 100 μg kg?1 showed the highest serum levels of testosterone and OHP. These results demonstrate that the use of LHRHa can effectively reduce the mean time to ovulation and induce synchronized ovulation in Caspian brown trout.  相似文献   

17.
Abstract – In 1997 and 1998, sampling was conducted on the Missouri and Yellowstone rivers, North Dakota, to obtain information on the distribution, abundance, and habitat use of the flathead chub (Platygobio gracilis Richardson), sicklefin chub (Macrhybopsis meeki Jordan & Evermann), sturgeon chub (Macrhybopsis gelida Girard), and western silvery minnow (Hybognathus argyritis Girard), four declining fish species (family Cyprinidae) native to the Missouri River basin, USA. The study area consisted of four distinct river segments near the confluence of the Missouri and Yellowstone rivers – three moderately altered segments that were influenced by a main‐stem dam and one quasi‐natural segment. One moderately altered segment was located at the confluence of the two rivers (mixing‐zone segment (MZS)). The other two moderately altered segments were in the Missouri River adjacent to the MZS and extended up‐river (above‐confluence segment (ACS)) and down‐river (below‐confluence segment (BCS)) from this segment. The quasi‐natural segment (Yellowstone River segment (YRS)) extended up‐river from the MZS in the Yellowstone River. Catch rates with the trawl for sicklefin chub and sturgeon chub and catch rates with the bag seine for flathead chub and western silvery minnow were highest in the BCS and YRS. Most sicklefin and sturgeon chubs were captured in the deep, high‐velocity main channel habitat with the trawl (sicklefin chub, 97%; sturgeon chub, 85%), whereas most flathead chub and western silvery minnow were captured in the shallow, low‐velocity channel border habitat with the bag seine (flathead chub, 99%; western silvery minnow, 98%). Best‐fit regression models correctly predicted the presence or absence of sicklefin chub, flathead chub, and western silvery minnow more than 80% of the time. Sturgeon chub presence and absence were predicted correctly 55% of the time. Best‐fit regression models fit to fish number data for flathead chub, sicklefin chub, and sturgeon chub and fish catch‐per‐unit‐effort (CPUE) data for flathead chub also provided good fits, with R2 values ranging from 0.32 to 0.55 (P < 0.0001). The higher density and catch of the four native minnows in the YRS and BCS suggest that these two segments are better habitat than the ACS and MZS.  相似文献   

18.
Female Japanese chub mackerel Scomber japonicus of the Tsushima Current subpopulation were collected during the spawning season from March to May 2001. A total of 137 adult females were caught between midnight and daybreak. A considerable number of fish displayed new postovulatory follicles (POF), whereas there was no evidence of germinal vesicle breakdown or hydrated oocytes in any of the fish collected. This suggests a daily spawning synchronicity toward midnight. To estimate the spawning frequency (S), the female reproductive state was classified into four criteria based on the degenerative stage of the POFs and the developmental stage of the oocytes. To stage the POFs according to age and determine the stage duration, ovaries from S. japonicus were induced to spawn in the laboratory and were sampled 0–72 h after ovulation at appropriate intervals. The average S, which is evaluated from four different indices, was 16.9%, corresponding to the average female chub mackerel spawned every 5.9 days (8.5 times) during the 50 days.  相似文献   

19.
The lipid composition and bioaccessibility in canned sardine (Sardina pilchardus) and chub mackerel (Scomber japonicus) were studied. Triacylglycerols were absent from the bioaccessible fraction in both products and each FA had a different bioaccessibility level. While total fat bioaccessibility was in the 60–64% range, the bioaccessibility of ω6 PUFA and DHA was <55%. Bioaccessibility depended on canned fish product species: fat, EPA, DHA, and ω3 PUFA bioaccessibility levels seemed to be higher in canned sardine than in canned mackerel. Daily consumption of 278 g of canned mackerel or 47 g of canned sardine would ensure the recommended daily intake of EPA+ DHA.  相似文献   

20.
We tested whether the predation dynamics of chub mackerel Scomber japonicus and spotted mackerel S. australasicus on young anchovy Engraulis japonicus relates to individual growth characteristics of the prey and could account for the growth-selective survival predicted by recruitment hypotheses. Juvenile and adult mackerel were sampled along with their young anchovy prey field in 2004 (juvenile mackerel and larval anchovy) and 2005 (adult mackerel and juvenile anchovy) off the Pacific coast of Honshu, Japan. The recent 5-day mean growth rate of larval and juvenile survivors and prey found in the stomach of mackerel was estimated from the otolith microstructure. No significant difference was found between the recent growth of larval or juvenile survivors and that of preyed individuals. We conclude that despite a relatively small body size, the high activity level and predation skills displayed by mackerel prevent fast-growing larvae and early juveniles from benefitting in terms of the expected survival advantage over slow-growers. Hence, growth-selective predation mortality of larval fish would depend on the feeding ecology of the predator rather than predator size. Selection for fast growth is more likely to occur under predation pressure from invertebrate organisms and small pelagic fish specialized on zooplankton, such as herring and anchovy.  相似文献   

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