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Marcial Arellano‐Martínez Bertha Patricia Ceballos‐Vázquez César Ruíz‐Verdugo Edgar Pérez de León Rafael Cervantes‐Duarte Pedro Martin Domínguez‐Valdéz 《Aquaculture Research》2011,42(4):571-582
The lion's paw scallop, Nodipecten subnodosus (Sowerby) has considerable aquacultural potential due to its fast growth and large adductor muscle. Prior investigations throughout northwestern Mexico's littoral have reported highly variable growth rates; furthermore, no studies are available of the environment on growth and gametogenesis in this species under culture conditions. This investigation assesses the effect of food availability and temperature on the growth and gametogenesis of N. subnodosus in a suspended culture system at Guerrero Negro lagoon, Mexico. After 1 year of cultivation, N. subnodosus reached 69.13 mm in shell height (SH) (0.196 mm day?1, 14 months old). Two significant growth spurts were observed: over the two first months of culture (August and September 2001, mean growth rate 0.4 mm day?1) and in September 2002 (0.3 mm day?1), both related to high temperatures and chlorophyll a concentrations. The onset of gametogenesis occurred in April 2002, with an increase in temperature (10‐month‐old scallops, 54.5 mm SH). The first spawning occurred in October and November (86.2 and 93 mm SH), with peak temperatures. These results, together with the analysis of previous reports, indicate that N. subnodosus has a higher preference for temperate areas; therefore, the Guerrero Negro lagoon appears to be a suitable site to culture this species. 相似文献
2.
B. Lal 《Fish physiology and biochemistry》2007,33(4):455-462
Numerous studies are available reporting the effects of pesticides on reproductive activity in Indian fishes. The majority
of these reports deals with histopathological changes in gonads and endocrine glands involved in the regulation of reproduction
following treatment with different pesticides. Pesticides are reported to cause degenerative changes in gonads and arrest
gametogenic processes either by acting directly on the gonads or by interfering with the secretory activity of the hypothalamo-hypophyseal-gonadal/thyroid
axis that regulates various reproductive events. Secretion of hormones such as gonadotropin-releasing hormone (GnRH), gonadotropin,
growth hormone, adrenocorticotropic hormone (ACTH), testosterone, estrogens, 17,20β-dihydroxyprogesterone and thyroid hormones
are in general lowered, leading to cessation of gametogenesis, vitellogenesis, oocyte maturation, ovulation, spermiation,
etc. Adverse effects of pesticides have also been demonstrated on fecundity, fertilization, hatching, and postembryonic development.
The effects are highly variable and depend on the nature, dose, and mode of application of the pesticides. 相似文献
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Sea urchin fisheries are valuable commercial resources in the United States with processed gonads sold in Japanese and American markets and maximum US sales of $150M US dollars in 1996. Wild populations of sea urchins on all coasts of the US have been dramatically over-fished. Aquaculture of sea urchins in land-based facilities can help restore commercial populations and preserve this ecologically important herbivore. In this study, we used invariant summer photoperiod to prevent gametogenesis in the North American green sea urchin (Strongylocentrotus droebachiensis) maintained in a land-based aquaculture system and provided a commercially available formulated feed that promotes maximum growth of intra-gonadal somatic nutrient storage cells called nutritive phagocytes. Results were compared with individuals fed the same formulated feed under ambient photoperiod in cages in the ocean. Monthly samples of gonads from both treatments were evaluated for gonad index, volume fractions of cellular constituents of the germinal epithelium, oocyte diameters and taste. Over the 5 months of this study, gonad indices increased significantly (p < 0.001) in both treatments from 4.8% ± 0.9 (all values ± SE) initially to 20.5% ± 2.1 under invariant and 23.2% ± 1.4 under ambient photoperiod with no significant difference between treatments (p = 0.55). Volume fractions of nutritive phagocytes increased to 80.3% ± 5.9 (initial 37.9% ± 7.1) in males and 71.0% ± 6.7 (initial 10.3% ± 4.0) in females (p < 0.001) only under invariant photoperiod. Nutritive phagocyte lengths increased under both photoperiod treatments, but the volume fraction containing nutrients was higher under invariant photoperiod. Volume fractions of gonial/gametogenic cells increased significantly (p < 0.001) only under ambient photoperiod from 20.4% ± 5.5 to 37.8% ± 1.8 in males and 0% to 22.6% ± 3.6 in females. The volume fraction of residual oocytes from last year's oogenesis increased under invariant photoperiod while that of both residual and new oocytes increased under ambient photoperiod. Residual oocyte diameters increased from 56.2 μm ± 2.2 initially to 93.5 μm ± 3.7 under invariant and those of residual and new oocytes to 126.0 μm ± 7.3 under ambient photoperiod. Invariant photoperiod yields gonads in both sexes of S. droebachiensis that do not initiate fall gametogenesis but attain large size as their nutritive phagocytes grow substantially in size. A Canadian study of wild-collected S. droebachiensis indicated that gonads taste best when they contain pre-dominantly nutritive phagocytes and not copious gametes, however gonad taste in our study was unsatisfactory suggesting that the only commercially available sea urchin diet requires modification to support commercial development of land-based aquaculture. 相似文献
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The putative involvement of insulin-like peptides in the control of the reproduction of the Pacific oyster Crassostrea gigas was investigated using different approaches. In conjunction with a monthly histological analysis of the oyster reproductive cycle, in vitro biological effects of the human recombinant IGF-1 (hrIGF-1) on dissociated germinal cells were mesured over 1 year using [3H]-thymidine and [14C]-amino acid mixture as tracers for DNA and protein synthesis. DNA synthesis was stimulated by hrIGF-1 in November (114 ± 11% for 10− 7M), December (46 ± 6% for 10− 7 M) and January, which was identified as the highest gonial mitosis period. A clear dose-effect was observed in January with a maximum activation of 68 ± 7% for 10− 12 M. Germinal cell protein synthesis was also stimulated in March (20 ± 1% for 10− 10 M), April (41 ± 5% for 10− 13 M), May (25 ± 4% for 10− 13 M), and by almost all of hrIGF-1 doses in June (21.5 ± 2% for 10− 13 M) and July (34 ± 1% for 10− 13 M). This suggests the involvement of insulin-like substances in gonadal tubule rebuilding (December), as well as in the development of germinal cells (March, April), and in the summer maturation of gametes (May, June, July). These insulin-like effects conform with the expression pattern of the recently identified C. gigas insulin receptor-related receptor (CIR): It appeared highly expressed in the gonadal area during gonial mitosis phase, but also in maturating oocytes, suggesting the involvement of an insulin-like system in gonial proliferation and maturation. Moreover, CIR showed differential expression during embryogenesis and larval developmental stages. The expression of maternal CIR during the embryonic and early larval development, followed by the increasing zygotic CIR expression from D larvae to 11-day-old veliger larvae, then a decrease until metamorphosis, also suggest that insulin-like peptide is involved in organogenesis. 相似文献
6.
C. G. Coetzee 《African Zoology》2013,48(2):223-224
Histological examination of gametogenesis revealed that the current staging criteria used to assess gonadal recrudescence of the redeye labeo, Labeo cylindricus, were adequate. Gametogenesis was qualitatively similar to thatof freshwater teleosts with a clearly defined seasonal reproductive cycle. L. cylindricus undergoes seasonal gross morphological and cytological gonadal changes with previtellogenesis dominating during the winter, vitellogenicdevelopment during spring and summer culminating in large-scale spawning at the end of summer. Post-spawning mass atresiaofoocytes was evident in autumn. The histological data presented support macroscopical evidence that L. cylindricus is a synchronous iteroparous spawner, reproducing over a short period each year throughout its life-span. 相似文献
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Opisthopappus taihangensis is an endangered species endemic to China and represents an important genetic resource for chrysanthemum improvement. We describe here its basic reproductive characteristics. The anthers are tetrasporangiate and the anther wall is composed of an epidermis, endothecium, middle layer and tapetum. The middle layer is lost by the microspore tetrad stage, and the tapetum disintegrates at the trinucleate pollen stage. Meiosis in the microspore mother cells is of the simultaneous type, and the tetrad is tetrahedral in shape. Mature pollen grains have three germinal apertures, two sperm nuclei and one vegetative nucleus. The in vitro pollen germination rate is only ∼10%. The ovule is anatropous, dual-integument, tenuinucellatae and the development of the embryo sac follows the Oenothera pattern. The archesporial cell below the nucellus epidermis functions as the megaspore mother cell and forms a linear tetrad. The embryo passes through a globular, heart and torpedo stage before maturing into a cotyledon embryo. The endangerment of O. taihangensis may be associated with low reproductive capacity, as a consequence of poor pollen viability. 相似文献
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毛叶茶小孢子母细胞减数分裂中胞质分裂为同时型,四分体的排列为四面体型,成熟花粉为2-细胞型;花药壁的发育属于基本型,绒毡层为腺质型;倒生胚珠,双珠被,薄珠心,胚囊发育属葱型。 相似文献
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《African Zoology》2013,48(2):281-286
The histology of brain neurosecretory cells and the development of the ovary and oocytes of preclitellate, early clitellate and late clitellate stages of Eudrilus eugeniae reared in clay loam soil and pressmud have been studied. E. eugeniae reared in pressmud showed earlier differentiation of lobules in the ovary, and increasedoocyte numbers with larger cellular and nuclear volumes than those reared in clay loam soil. This indicates the nutritional superiority of pressmud over clay loam soil in supporting gametogenesis. In the preclitellate stage, the brain neurosecretory cell types (A and B) are small and appear to be laden with secretory substances. The neurosecretory cells become vacuolated and show increased cellular and nuclear volumes and nucleocytoplasmic indices during the reproductively active clitellate stages. Secretory activity of neurosecretory cells occurs earlier in worms reared in nutritively rich pressmud which has greater amounts of nitrogens, phosphorus and sugar, than in worms reared in clay loam soil. 相似文献