共查询到20条相似文献，搜索用时 62 毫秒
1.
Norhidayat Kamaruzzaman Nguyen Hong Nguyen A. Hamzah & Raul W. Ponzoni 《Aquaculture Research》2009,40(6):720-728
The growth performance of three experimental groups consisting of mixed sex fish (control), hormone-treated fish and progeny of YY male tilapia, all originated from the genetically improved farmed tilapia (GIFT) strain was evaluated. Masculinization of sexually undifferentiated fry was achieved by providing a supplement of 5 mg of 17-α-methyltestosterone per kg of feed over a period of 21 days (after sac absorption). Both mixed sex and progeny of YY male groups were fed a standard commercial ration. Mixed sex fish did not deviate significantly ( P >0.05) from the 1:1 male to female ratio. Percentages of male averaged 75% in hormone-treated fish and 95% in YY male group over the sampling periods and at final harvest. The effect of sex on weight and length was statistically significant ( P <0.001). The model used to analyse weight and length included experimental group and sex in each culture period as the fixed effects, and replicate cages as the random effect. Over the culture period of 141 days, there were no statistical differences ( P >0.05) in body weight and length between mixed sex, hormonally treated and progeny of YY males. There were also no significant differences in level of variability in harvest weight between three groups of fish when the data were classified into five categories (=<100, 100 to <150, 150 to <200, 200 to <250 and ≥250 g). It is concluded that monosex culture of all male tilapia would be of no advantage over mixed sex culture for the GIFT strain under conditions of cages suspended in earthen ponds. 相似文献
2.
Fabricio F. T. Domingos Ralph G. Thomé Fabio P. Arantes Antonio Carlos S. Castro Yoshimi Sato Nilo Bazzoli Elizete Rizzo 《Fish physiology and biochemistry》2012,38(6):1709-1719
River damming and building of hydroelectric power plants interrupt the reproductive migration routes and change the major physicochemical parameters of water quality, with drastic consequences for populations of migratory fishes. The goal of this study was to evaluate proliferation and cell death during spermatogenesis and serum profiles of sex steroids in Prochilodus argenteus, from the S?o Francisco River, downstream from the Três Marias Dam. A total of 257 adult males were caught quarterly during a reproductive cycle in two sites: the first 34?km of the river after the dam (site 1) and the second 34–54?km after the dam (site 2), after the confluence with a tributary, the Abaeté River. Seasonal changes in the testicular activity associated with morphometric analyses of germ cells as well as proliferation and testicular apoptosis support a more active spermatogenesis in fish from site 2, where higher levels of sex steroids and gonadosomatic index (GSI) were also found. In site 1, fish presented low serum levels of testosterone, 17β-estradiol and 17α-hydroxyprogesterone and a low GSI during gonadal maturation. Spermatogonial proliferation (PCNA) and apoptosis (TUNEL) were more elevated in fish from site 1, but spermatocytes were mainly labelled in fish from site 2. Overall, these data demonstrate changes in testicular activity and plasma sex steroids in a neotropical teleost fish living downstream from a hydroelectric dam, supplying new data on fish reproduction in regulated rivers. Moreover, morphometric analyses associated with sex steroids profiles provide reliable tools to assess fish spermatogenesis under environmental stress conditions. 相似文献
3.
The sex ratios and sex determination mechanism of gynogenetic diploids of ship sturgeon, Acipenser nudiventris, have been investigated to verify the possibilities of sex control by chromosome manipulation in this species. Meiotic gynogenesis was induced in a female ship sturgeon using cold shock after egg activation with UV-irradiated sperm of a male Siberian sturgeon. Microsatellite DNA analysis was applied for verification of uniparental inheritance in the gynogenetic diploid group of fish. All the analyzed gynogenetic diploids possessed only maternal genotype in the examined experimental group of fish. In this study, a minimum of two distinctly selected diagnostic loci in the offspring was used to confirm exclusively maternal contribution. Also, these fish were analyzed for sex diagnostic. Histological analysis of gonads from gynogenetic diploids, obtained from one family, showed 73.3 % of females and 27.7 % of males. The observed sex ratio has suggested that the ship sturgeon have a female heterogametic sex determination system. Gynogenesis in this species with female heterogametic sex determination system will have important role in breeding program and reclamation of its natural population to produce both female and male progeny, while this species has been introduced in the red list of IUCN (International Union for Conservation of Nature and Natural Resources). 相似文献
4.
In aquaculture, automation of fish processing by computer vision could reduce operating costs, improving product quality and profit. Currently fish are mechanically sorted by size, but market constraints require that externally malformed fish be removed as well. Additionally fish farmers screen for sex, in order to exploit the higher growth potential of females. The aim of this study was the development of methodological tools applicable to the on-line sorting of farmed seabass (Dicentrarchus labrax, L.) for size, sex and presence of abnormalities. These tools are based on image analysis and utilizing outline morphometry (Elliptic Fourier analysis) combined with multivariate techniques (based on partial least squares modelling). Moreover, the integration of these techniques produce size estimation (in weight) with a better regression efficiency (r = 0.9772) than the commonly used log of the measured body length (r = 0.9443). The two partial least squares discriminant analysis models used to select sex and malformed fish also returned high discrimination efficiencies (82.05% and 88.21%, respectively). The implementation of a similar approach within an on-line sorting machine would allow for real-time live fish processing. 相似文献
5.
Takayoshi?Matsunaga Risa?Ieda Sho?Hosoya Miwa?Kuroyanagi Shigenori?Suzuki Hiroaki?Suetake Satoshi?Tasumi Yuzuru?Suzuki Toshiaki?Miyadai Kiyoshi?Kikuchi
The tiger pufferfish (fugu) is one of the most important food fishes in East Asia. Since its testes are regarded as a delicacy, sex determination is economically relevant. Previous studies have identified a missense single-nucleotide polymorphism (SNP) in the Amhr2 (anti-Müllerian hormone receptor type II) gene as a strong candidate for a master sex-determining polymorphism. To distinguish genotypic sex efficiently, we developed a high-resolution melting (HRM) assay for this SNP site. By screening 396 fish from two independent crosses reared under controlled conditions, we observed perfect concordance between the SNP genotype and phenotypic sex. Thus, this method holds great potential for use in high-throughput sexing. When analyzing 293 progeny from a third cross reared under unknown conditions, we unexpectedly found that 25 % of phenotypic males exhibited female genotype. These results suggest that environmental factors such as rearing conditions could influence the sex-determination pathway in pufferfish. Alternatively, genetic modifiers might override the signals from Amhr2. This finding raises a concern regarding enhanced stock management of this species, because sex-reversed fish could compromise the sex ratio in subsequent generations. The HRM assay will also be useful for monitoring the degree of sex reversal before release. 相似文献
6.
7.
Y. Nagahama 《Fish physiology and biochemistry》2005,31(2-3):105-109
We have used various genetic and molecular approaches to investigate the mechanisms of sex determination and gonadal sex differentiation
in fish. DMY was identified as the sex-determining gene of medaka. In tilapia, endogenous estrogens act as natural inducers of ovarian
differentiation, while DMRT1 may be important for testicular differentiation. The roles of these regulators in sex determination and gonadal sex differentiation
were ascertained using a gene or hormonal blockade strategy. 相似文献
8.
《水生生物资源》2003,16(5):408-415
The development of techniques for production of gynogenetic, androgenetic, polyploid, and monosex progenies in common carp (Cyprinus carpio L.) is described from a chronological perspective. Gynogenetic progenies were obtained either by suppression of the second meiotic division in eggs (meiotic gynogenesis) or by suppression of the first mitotic division in haploid embryos (mitotic gynogenesis). As a rule, gynogenetic progenies of common carp were all-female, revealing female homogamety (females—XX, males—XY) in this species. Induced gynogenesis results in increased homozygosity; the rate of increase depends on the type of gynogenesis. Inbreeding coefficient (F) for one generation of meiotic gynogenesis in common carp is about 0.6, while diploids obtained by mitotic gynogenesis are homozygous for all genes (F = 1.0). Mitotic gynogenesis was used for production of clones in common carp. In androgenetic progenies of common carp, YY males were identified, that after crossing with normal females (XX) produced all-male progenies. Triploids of common carp are characterized by a significant reduction in gonad development (especially ovaries). However, the reduction in gonad development did not result in an increase of somatic growth rate of fish. The procedure for androgen treatment to induce phenotypic sex reversal in genotypic females (XX) was elaborated. All-female progenies of common carp were produced on a large scale by crossing normal females (XX) with hormonally sex-reversed males (XX). Rearing of all-female progenies in conditions when fish normally reach sexual maturity before reaching of market size increased production yield by 7–8%. In a few cases distant hybridization resulted in polyploidy of fish without application of any physical treatment. The ability of hybrid females between crucian carp (Carassius auratus) and common carp to produce diploid (with unreduced chromosome number) gametes resulted in opportunities to produce triploid and tetraploid hybrid progenies. 相似文献
9.
This paper describes a novel approach to study the expression of temperature-related reproductive phenomena such as thermolabile sex determination (TSD) and heat-induced germ cell loss in wild fish populations. The proposed approach is based on the reconstruction of the past thermal history of individual fish through the microchemical analysis of the otoliths (mineralized structures responsible for the sense of balance). As an example, we outline the preliminary results of an investigation on the natural occurrence of TSD in pejerrey Odontesthes bonariensis, an atherinid fish in which all-female to all-male populations can be produced by experimental manipulation of the rearing temperature during the critical time of sex differentiation, from Lake Kasumigaura, Japan. 相似文献
10.
Asian Seabass which shows precocious sex inversion in cultured environment is a major impediment to maintain a proper broodstocks. Seabass grown commercially in freshwater were transported to the research facility and held in freshwater at 29°C for 4 weeks and acclimatized to the experimental conditions. Fish were daily fed with a commercial pellet (50% protein, 18 MJ kg?1) to satiety. Blood, brain and gonad collected before and at the end of the experiment were analysed for sex steroids level and aromatase activity. There was an increase in Plasma E2 levels with temperature in fish at 34°C whereas no significant difference was observed at 24 and 29°C although the highest plasma T level was detected in fish at 34°C which had significantly lower level than at the beginning, except those held at 24°C in freshwater. Plasma 11‐KT was significantly greater in fish at 24°C compared with 29 or 34°C which had clear opposite to the E2. Aromatase activity in brain was higher at 29°C than at either 24 or 34°C, whereas gonadal aromatase recorded highest at 34°C. These findings concluded that high temperature in culture facility induces sex inversion of Asian Seabass. 相似文献
11.
Yasuhiro Fujioka 《Fisheries Science》2006,72(5):1034-1041
ABSTRACT: The sex ratios of the offspring of males from broods of honmoroko Gnathopogon caerulescens that displayed thermolabile sex determination (TSD), and those from eggs collected from the wild, strongly suggest that the combination of parents plays an important supplementary role in TSD in this species. The proportion of females in all broods from eight pairings of fish captured in the field decreased significantly at 30°C compared to 20°C, and one brood was entirely female at the lower temperature. These results suggest that phenotypic males (XX-males) exist in nature, probably as a result of sex change from genetic females caused by TSD. Sex ratios in relation to water temperature fall into five patterns, two of which seem to result from normal pairings of XX-females and XY-males, and from pairings of XX-males and XX-females with non-thermosensitivity. Two other patterns are thought to result from the same types of pairing, but with thermosensitivity. The last pattern, which shows male bias at both low and high temperature, is not explained only by the combination of genotypic sex determination (XX/XY) and TSD. Fluctuating temperatures close to natural conditions showed little potential to masculinize broods laid in the field between April and early June. However, the sex ratios of fish spawned in early June showed male bias at low and high temperatures. The sex determination mechanism in G. caerulescens may involve the interaction between temperature and sex-determining genetic factors, and the relative importance of each component differs with breeding season. 相似文献
12.
Masaru Nakamura Ramji K. Bhandari Mikihiko Higa 《Fish physiology and biochemistry》2003,28(1-4):113-117
Using genetically controlled all-female and all-male tilapia (Oreochromis niloticus), the role steroid hormones play in the sex differentiation was analyzed histologically, ultrastructurally, immunohistichemically and experimenntally. The results strongly suggest that endogenous estrogen acts as an ovarian inducer, and that the lack of steroid hormone including androgen is important for testicular differentiation. Moreover, the roles of steroid hormones in protogynous sex change of three-spotted wrasse (Halichoeres trimaculatus) and saddleback wrasse (Tharassoma duperrey) were examined. The results strongly support the hypothesis that the endogenous estrogen plays an important role in protogynous sex change. 相似文献
13.
14.
金钱鱼(Scatophagus argus)是我国东南沿海名优养殖鱼类, 具有 XY 性别决定系统, Dmrt1 是其性别决定候选基因。金钱鱼生长具有性别二态性, 雌鱼生长快于雄鱼。目前缺乏快速鉴定金钱鱼遗传性别的分子标记, 阻碍了其性别控制育种技术的建立。本研究以公布的金钱鱼基因组数据, 在 Dmrt1 附近设计多对标记引物, 并通过 PCR 扩增验证标记的性别特异性。其中, 标记引物 Dmrt1-Marker-4-F/R 在雌鱼中仅扩增出一条 593 bp X 染色体条带, 而在雄鱼中能扩增出 593 bp 和 693 bp 两条条带, 分别来自 X 和 Y 染色体, 表明该标记为共显性标记。利用该标记检测我国南海沿岸 3 个不同地理群体 213 尾金钱鱼的遗传性别与表型性别完全一致。此外, 快速 DNA 提取试剂盒提取的片段较短 DNA 样品也可用于该对标记引物准确鉴定遗传性别。本研究建立了一种快速、准确、经济可靠的金钱鱼遗传性别鉴定方法, 将旨为促进金钱鱼性别控制育种技术的建立, 并为金钱鱼性别决定与分化机制研究提供依据。 相似文献
15.
K. Ohta J.K. Sundaray T. Okida M. Sakai T. Kitano A. Yamaguchi T. Takeda M. Matsuyama 《Fish physiology and biochemistry》2003,28(1-4):173-174
The protogynous wrasse, Pseudolabrus sieboldi, is a good model for studying the physiological mechanism of sex change in teleosts. We established a way to induce sex change bidirectionally by controlling the social conditions in captivity. This is the first report of a reversed sex change in a promiscuous species. After identifying all the steroid hormones produced in the ovarian follicles and testis, and clarifying their synthetic pathways, we examined the function of the sex steroids in the sex change of P. sieboldi. We concluded that the activation of 17β-HSD-III is the first step in inducing morphological and functional change from an ovary to a testis. 相似文献
16.
17.
The phenomenon of incidental sex reversal was observed in experiments originally designed to determine the importance of feeding duration and feed quality in the optimization of masculinization and feminization treatments of Oreochromis niloticus (L.) fry by oral application of hormones. Four separate experiments were conducted: (1) masculinization and (2) feminization using three feeding durations and (3) masculinization and (4) feminization using three alternative feed mixtures. Masculinization experiments incorporating 17 α-methyltestosterone (MT) into the feed at 40 mg kg?1 were applied to putative monosex male progeny whilst feminization treatments were applied to putative all female fry using diethylstilboestrol (DES) at 1000 mg kg?1. Treatments were applied outdoors in small cages suspended in 900-l circular concrete tanks with a flow through rate of 1-l min?1. Replicate cages for all treatments and the controls in each experiment were reared together in the same tank. Only the first experiment produced significant differences in sex ratio, with the control treatment producing a slightly lower proportion of males than the three MT treatments at different durations. The most significant finding was that in all experiments the sex ratio of the control differed significantly from expectations and in all but experiment 1, did not differ from those of the treated fish in which sex reversal had clearly been effected. It appears likely that incidental sex reversal occurred in the control fish as a result of the accumulation of active metabolites from the treated fish and/or leachates from uneaten food given to fish in the same water body. The results are discussed in the context of improving the efficiency and safety of hormonal sex reversal treatments. 相似文献
18.
SUMMARY: Thirty immature juvenile grouper Epinephelus coioides (19–168 g bodyweight, BW) were randomly stocked in four units 6 t tanks to determine if mibolerone can be used to induce sex inversion in groupers. After acclimatization and weaning to artificial feed, the feed given daily (4% BW/day) was supplemented with 0, 50, 100, and 200 μg mibolerone/kg feed for about 18 weeks. Thereafter, the hormone treatment was withdrawn and the experiment was terminated at Week 24. Ten fish were killed for gonad histology at stocking to serve as an initial control while about three to five fish were killed every 8 weeks. In general, ovaries of initial controls showed the presence of moderate stromal cells and gonia and few primary oocytes. At Weeks 8 and 16, ovaries of the control fish (0 μg/kg) were similar to that of the initial control except that primary oocytes increased at Week 24. Gonads of fish fed diets containing 100 and 200 μg/kg had none to moderate spermatocytes and few spermatids at Week 8 and 16, although spermatozoa were not observed, indicating that the fish were undergoing spermatogenesis. Spermatogenesis at 50 μg/kg was not as advanced since only few spermatocytes occurred at Weeks 8 followed by moderate gonia and no spermatocytes and spermatids at Week 16. However, the presence of few primary oocytes was observed when mibolerone was withdrawn suggesting that sex-inversed fish reverted back to a female condition. These results show that sex inversion in juvenile grouper can be induced by oral administration of mibolerone and may have possible application on mature females to produce functional males. 相似文献
19.
Gefeng Xu Tianqing Huang Xian Jin Cunhe Cui Depeng Li Cong Sun Ying Han Zhenbo Mu 《Fish physiology and biochemistry》2016,42(1):193-202
In non-mammalian vertebrates, estrogens and expressions of cyp19a1 and foxl2 play critical roles in maintaining ovary differentiation and development, while dmrt1 and sox9 are male-specific genes in testicular differentiation and are highly conserved. In order to deeply understand the morphological change, sex steroids level and molecular mechanism of triploid female gonadal reversal in rainbow trout, we studied the ovary morphology, tendency of estradiol-17β (E2) and testosterone (T) levels and the relative expressions of dmrt1, cyp19a1, sox9 and foxl2 in juvenile and adult fish. Our results demonstrated that the development of triploid female gonads in rainbow trout went through arrested development, oocytes dedifferentiation, ovary reconstruction and sex reversal finally. During early gonadal development (154–334 days post-fertilization), the expressions of foxl2 and cyp19a1 increased linearly, while expressions of dmrt1 and sox9 were extremely suppressed, and E2 level was higher, while T level was lower. During the mid-to-late period of triploid female gonadal development (574–964 days post-fertilization), the expressions of dmrt1 and sox9 remained high and were very close to the quantity of diploid male genes, and T levels were even reaching diploid male plasma concentrations, while expressions of cyp19a1 and foxl2 were decreased, leading to decrease in E2 level. We realized that the development model of rainbow trout triploid female gonads was extremely rare, and the regulatory mechanism was very special. Genes involved in gonadal development and endogenous estrogens are pivotal factors in fish natural sex reversal. 相似文献
20.
动物从受精卵发育到具有不同性别特征的个体是一个奇妙而又严谨的过程,是人类长期以来试图揭示的自然现象。上世纪90年代初在人类Y染色体上发现了性别决定基因SRY[1],进而发现了一个新的Sox基因家族[2]。上述基因的发现,促进了以哺乳类为代表的动物性别决定和分化机制研究。由于鱼类在脊椎动物中的特殊进化地位、庞大的种类数量以及显著的社会经济价值,鱼类的性别决定研究一直受到遗传和发育学者的重视。尽管离最终阐明鱼类性别决定的机制还有距离,但近20多年来鱼类性别决定的遗传基础研究已取得不少重要进展。本文试图根据现有文献资料,… 相似文献