Evidence for sexual dichromatisms in spawning aggregations of yellowfin grouper Mycteroperca venenosa and tiger grouper Mycteroperca tigris from the southern Gulf of Mexico

Colour pattern characteristics and gonad histology were used to detect sexual dichromatisms in yellowfin grouper Mycteroperca venenosa and tiger grouper Mycteroperca tigris from the Campeche Bank, Mexico. Specimens were obtained from commercial catches between March and May during 2002 and 2004. All specimens were examined dead. Ninety-seven per cent of males had different sex-associated colour patterns. Male yellowfin grouper displayed a bright yellow blotch on both sides of the lower jaw while females retained a reddish lower jaw. Male tiger grouper had uniform dark pectoral fins while females had bright orange pectoral fins. In situ observations of live fishes at fishing sites showed the lower jaw and pectoral fin colourations to be clearly visible underwater at a depth of 35 m. All males of both species and most females (80% yellowfin grouper and 98% tiger grouper) were sexually active and probably caught during their spawning season. This suggests that distinct colourations observed for male M. venenosa and M. tigris may be seasonal displays associated with spawning. Both the lower jaw and pectoral fin colourations were still visible in dead fishes after several days on ice. Differences observed for ray length of exserted vertical fins in tiger grouper specimens were probably not a sex-associated characteristic.     

Fine Structure of Sperm of Ekphymatodera thomasoni (Heteroderinae,Nemata)

Fine structure of developing sperm of the monospecific genus, Ekphymatodera, was compared with other Heteroderinae as part of a study to recognize diversity and phylogenetically informative characters within the subfamily. Sperm of Ekphymatodera originate from germ cells connected to a central rachis, a character which is shared with Globodera, but not with other Heteoderinae. In Ekphymatodera, and cyst-forming genera, a layer of cortical microtubules lies just beneath the surface of the plasma membrane. Sperm of Ekphymatodera are unique among Heteroderinae examined by the presence of spiral surface elevations on the filopodia, a character that may prove to be a synapomorphy for Sarisoderini. Fibrous bodies are abundant in spermatids; however, they do not persist in sperm of Ekphymatodera as they do in Meloidodera and Verutus. The male gonad of Ekphymatodera is lined by epithelial cells, which are greatly enlarged near the ejaculatory canal. These enlarged cells contain vesicles with concentric lamellar inclusions, not observed in other genera of the subfamily. Sperm of Heteroderinae are rich in diversity, and examination of additional representative species may indicate new phylogenetically informative characters.     

Gonadal development in hermaphrodite mice

Summary The genetic background and morphology of spontaneous mosaic hermaphrodites of mice have been described. Presented in the formal symposium on Sexual Differentiation in Vitro and in Vivo at the 29th Annual Meeting of the Tissue Culture Association, Denver, Colorado, June 4–8. 1978. This work was supported by Grant HD 04083 from the National Institute of Child Health and Human Development.     

DSH-2 regulates asymmetric cell division in the early C. elegans somatic gonad

Like other organs, the C. elegans gonad develops from a simple primordium that must undergo axial patterning to generate correct adult morphology. Proximal/distal (PD) polarity in the C. elegans gonad is established early during gonadogenesis by the somatic gonad precursor cells, Z1 and Z4. Z1 and Z4 each divide asymmetrically to generate one daughter with a proximal fate and one with a distal fate. PD polarity of the Z1/Z4 lineages requires the activity of a Wnt pathway that activates the TCF/LEF homolog pop-1. How the gonadal pathway controlling pop-1 is regulated by upstream factors has been unclear, as neither Wnt nor Dishevelled (Dsh) proteins have been shown to be required. Here we show that the C. elegansdsh homolog dsh-2 controls gonadal polarity. As in pop-1 mutants, dsh-2 hermaphrodites have Z1 and Z4 lineage defects indicative of defective PD polarity and are missing gonadal arms. Males have an elongated but disorganized gonad, also with lineage defects. DSH-2 protein is expressed in the Z1/Z4 gonadal precursor cells. Asymmetric distribution of nuclear GFP::POP-1 in Z1 and Z4 daughter cells is reversed in dsh-2 mutants, with higher levels in distal than proximal daughters. dsh-2 and the frizzled receptor homolog lin-17 have a strong genetic interaction, suggesting that they act in a common pathway. We suggest that DSH-2 functions as an upstream regulator of POP-1 in the somatic gonad to control asymmetric cell division, thereby establishing proximal-distal polarity of the developing organ.     

Rapid DNA extraction and PCR-sexing of mouse embryos

We have devised a PCR-based sexing method that is quick, simple, and highly reproducible. DNA is first extracted from embryonic mouse yolk sac via a 15 min, two-step incubation procedure utilizing PCR-compatible proteinase K buffer. Without any further manipulation the lysate is subjected to 30 cycles of PCR, optimized to run in less than 1 hr. The reaction includes multiplexed primer pairs for Sry and Myog (myogenin) that generate a male specific band of 441 bp and an internal control band of 245 bp, respectively. This robust method is used routinely in our laboratory and gives rapid genotyping results with 98% reliability and 100% accuracy.     

产后鳗鲡生殖生理学的研究

产卵后的鳗鲡（Ａｎｇｕｉｌｌａ ｊａｐｏｎｉｃａ）可分为顺产鳗鲡（Ｓｍｏｏｔｈｌｙ ｏｖｕｌａｔｅｄ ｅｅｌｓ,ＳＯＥ）和部分产鳗鲡（Ｐａｒｔｌｙ ｏｖｕｌａｔｅｄ ｅｅｌｓ,ＰＯＥ）两种类型,经组织学检查发现,ＳＯＥ性腺中第Ⅳ＾＋＋＋和第Ⅴ时相的卵细胞较多,而ＰＯＥ性腺中第Ⅳ＾＋＋和第Ⅵ时相的卵细胞较多。ＳＯＥ脑部的ｍＧｎＲＨ、血清ＧｔＨ和雌二醇（Ｅ２）的含量均显著高于ＰＯＥ,但ＳＯＥ脑部ｃＧｎＲＨ－Ⅱ及血清睾酮（Ｔ）含量与ＰＯＥ无显著差异。     

Sexual reproduction in the tropical corallimorpharian Rhodactis rhodostoma

Abstract. Polyps of the tropical corallimorpharian Rhodactis rhodostoma segregate sexes between center and edge positions within aggregations produced by clonal replication. On a reef flat at Eilat, northern Red Sea, infertile polyps and males occur mainly along the edges of clonal aggregations, while females mostly occupy central positions within each aggregation. In addition, on the inner to middle reef flat where polyps of this species are abundant, aggregations consist mostly of females. On the outer reef flat, where polyps are rare, a sampled aggregation consisted mostly of males and infertile polyps. Male polyps are significantly smaller than females, and the smallest polyps are infertile. Fecundity increases significantly with polyp size in females, but testis size and number do not vary with body size in males. Oocytes are present in polyps during most of the year and gradually increase in size until annual spawning in June-July during the period of maximum day length. Testes do not vary significantly in size during the year and remain a small proportion of body mass (>8%). In contrast, females invest up to 30% of their body mass into gonads during the months immediately before spawning. The annual spawning of gametes coincides with a temporary drop in the frequency of clonal replication by polyps. We estimate that each female polyp of R. rhodostoma may release up to 3000 large eggs (500 μm in maximum diameter) each summer. The high investment of this corallimorpharian in sexual production of planktonic propagules may allow rapid dispersal to reef habitats distant from parent populations.     

转反义sGnRH基因败育鲤鱼的性成熟诱导

采用反义转基因技术已成功获得整合CAsGnRHpc-antisense基因的转基因鲤鱼,简称AS-sGnRH F0鲤鱼.通过挤压1年龄AS-sGnRH F0鲤鱼的腹部,发现该群体中有精液/无精液个体比例为33/69,与对照组鲤鱼中有精液/无精液个体比例接近1：1相比存在显著差异.通过注射鲤鱼垂体抽提物诱导无精液AS-sGnRH F0鲤鱼恢复繁殖功能,获得3尾育性被恢复的AS-sGnRH F0鲤鱼.进一步的解剖观察发现,在无精液AS-sGnRH F0鲤鱼群体中,完全无性腺的AS-sGnRH F0鲤鱼比例约31.3%.根据直观的挤精液和解剖学观察,推测在AS-sGnRH F0鲤鱼群体中,雄鱼：雌鱼：＂脂肪型＂性腺个体的比例大约为35：45：20%.受精卵发育12 h后,统计A、B、C系AS-sGnRH F0鲤鱼精子的受精率分别为73.94、59.45和64.05%.从A、B、C系杂交后代F1分别随机取样100尾,PCR检测的阳性率分别为0、78.1和87.8%.研究结果表明通过补充外源激素可以使促性腺激素分泌不足而不育的AS-sGnRH F0鲤鱼恢复具有产生成熟配子的能力.     

Gonad development and evidence of protogyny in the red-throat emperor on the Great Barrier Reef

The gonad development in the red-throat emperor Lethrinus miniatus is described and the first detailed evidence for protogyny in this species provided. The identification of transitional individuals, bimodal sex-specific size-frequency distributions and female biased sex ratios suggest that L. miniatus is most likely a protogynous hermaphrodite. Transitional L. miniatus gonads were characterized by the concurrent degeneration of all oocytes and the proliferation of spermatocysts near the edge of the lamellae, an increase in blood vessels along strands of stromal tissue within the lamellae and the formation of multiple sperm sinuses. The sites of oocyte degeneration and proliferation of spermatocysts were spatially segregated. An increase in blood vessels along strands of stromal tissue within the lamellae of transitional phase gonads is likely to assist in the breakdown of oocytes and the proliferation of spermatocysts. Most mature resting females containing spermatocysts occurred within the transitional size-frequency distribution, suggesting that the presence of spermatocysts in these females may be an early sign of sex change. Oocytes within female gonads were interrupted by filamentous strands of stromal tissue within the lamellae. The testis contained a remanent ovarian lumen but no residual oocytes. Three characteristics of transitional L. miniatus gonads were found to be unusual and described for few other species of coral reef fishes. These included the absence of oocytes within testes, increased numbers of blood vessels, and the presence of strands of stromal tissue within the lamellae.     

Diapause in the life cycle of Calanoides carinatus (Kroyer), (Copepoda, Calanoida)

The distribution and stage composition of Calanoidescarinatus (Kroyer) are described together with changes in protein and lipid content, respiration rate and gonad development in copepodite stages IV and V (CV) and adults in the Northern Benguela current (17°S, 23°S and 25°S).During active upwelling the population consisted of two parts: the surface part over the shelf was represented by all development stages, while the deep part offshore was dominated (90–95%) by diapausal CVs. In the surface CVs the surplus assimilated energy was allocated to structural growth and maturation or to synthesis of reserve lipids. CVs with large oil sacs and high lipid content descended into deeper layers and formed diapausal stock; they were characterized by a dramatic decrease of respiration rate. Increase of gonad size in association with decrease of oil sac volume in diapausal CV suggests that reserve lipids were expended not only for respiration but also for gonad development. The moulting of dispausal CVs into adults took place in deep water.These results are discussed in relation to the life cycle of the C. carinatus population and the factors causing the formation and termination of the diapausal phase.