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31.
Sex change in coral reef fish 总被引:1,自引:0,他引:1
Masaru Nakamura Yasuhisa Kobayashi Saori Miura Mohamad Ashraful Alam Ramji Kumar Bhandari 《Fish physiology and biochemistry》2005,31(2-3):117-122
Gonadal differentiation can take many forms in fish, ranging from gonochorism, where individuals directly develop as male
or female and finally possess only testis or ovaries at sexual maturation, to hermaphroditism where the same individuals can
produce mature male and female gametes at some time in their lives. Hermaphrodite fish are, thus, an excellent model for studying
the plasticity of sex determination and differentiation in vertebrates. We have shown that sex steroids play a principal role
in sex differentiation and sex change in fish. Our laboratory implements several fish models that undergo sex change from
female to male or male to female or in both directions. In this review, we will briefly discuss recent advances in our understanding
of the mechanism of sex change in coral reef fish. 相似文献
32.
D.S. Wang B. Senthilkumaran T. Kobayashi H. Kajiura-Kobayashi M. Matsuda M. Yoshikuni Y. Nagahama 《Fish physiology and biochemistry》2003,28(1-4):225-226
Tilapia riboflavin-binding protein (RfBP) cDNA was isolated by library screening. Even though it shows only 31~35% similarity to the reported RfBPs, tilapia RfBP is conserved in amino acid residues that are known to be essential for its protein function. The exclusive expression of RfBP in the brain-pituitary-gonadal axis, as revealed by both RT-PCR and Northern blot, suggested a possible role for RfBP in fish reproduction. 相似文献
33.
Toru Kobayashi Ryo Ishibashi Shinji Yamamoto Satoshi Otani Koichi Ueno Osamu Murata 《Aquaculture Research》2011,42(2):230-239
The timing of primordial germ‐cell (PGC) migration with regard to the gonadal anlagen, gonad formation and sex differentiation was examined histologically in the chub mackerel (Scomber japonicus) at 5–190 days post hatching (dph). At 5 dph, PGCs appeared on the peritoneal epithelium surface or in the mesentery, on the dorsal side of the abdominal cavity. By 10 dph, stromal cells around the PGCs proliferated. The gonadal primordium was formed by 15 dph. The gonadosomatic index was 0.01% at 30 dph and increased thereafter (0.32% in females and 0.04% in males at 160 dph). Ovarian differentiation occurred at 30–40 dph, indicated by ovarian cavity formation (elongation and fusion of the upper and lower ovarian edges). Meiosis was subsequently initiated. A few meiotic oocytes surrounded the cavity at 50 dph; most were in the perinucleolus stage at 60 dph and attained a diameter of 60–70 μm at 190 dph. Testicular differentiation occurred at 30 dph, indicated by the formation of the sperm duct primordium. Spermatogonia gradually proliferated, developing into spermatocytes at the chromatin–nucleolus stage (after 90 dph) and subsequently into spermatids and spermatozoa (160 dph). These data could aid the development of seeding and cell‐engineering technologies for scombrid fish. 相似文献
34.
Yasuo Tomida Toshiya Suzuki Tsutomu Yamada Ryuji Asami Hirofumi Yaegashi Yasufumi Iryu Tsuguo Otake 《Fisheries Science》2014,80(2):273-280
We examined differences in otolith oxygen (δ18Ootolith) and carbon (δ13Cotolith) stable isotope ratios between hatchery and wild pink salmon fry. The δ18Ootolith values of hatchery and wild fry were ?7.7 ± 0.2 ‰ and ?8.3 ± 0.3 ‰ (1σ), respectively. This difference reflected differences in temperature conditions experienced by each fry. The δ13Cotolith values of hatchery and wild fry were ?19.2 ± 0.3 ‰ and ?11.1 ± 1.8 ‰ (1σ), respectively. The lower δ13Cotolith values of hatchery fry were probably related to their intake of artificial diets. Discriminant analysis of δ18Ootolith and δ13Cotolith values demonstrated a highly significant difference between hatchery and wild fry with 95.8 % classification accuracy. Therefore, analysis of δ18Ootolith and δ13Cotolith precipitated in the fry stage may be useful for discriminating the origin of returning adult pink salmon. The discrimination method for returning adult fish would provide important information for evaluating the effect of hatchery release and their impact on the wild population. 相似文献
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36.
The alpha antigen, which is an immunodominant antigen, is a 30 kDa protein secreted by mycobacterial species. The C-terminal regions of alpha antigens are quite divergent. We investigated the question of whether the C-terminal regions of Mycobacterium avium alpha antigen (A-alpha), M. intracellulare alpha antigen (I-alpha) and M. bovis BCG alpha antigen (B-alpha) contained species-specific B-cell epitopes. We investigated the reactions of these peptides with anti-A-alpha, anti-I-alpha and anti-B-alpha sera prepared from BALB/c in a Western blot assay and ELISA. The C-terminal regions of I-alpha reacted exclusively with anti-I-alpha serum. The results of the inhibition assay of antibodies binding to I-alpha by peptides of C-A-alpha, C-I-alpha, and C-B-alpha are that only C-I-alpha inhibited the binding of antibodies to C-I-alpha. We found that the C-terminal region was B-cell epitope-specific to I-alpha in BALB/c mice. 相似文献
37.
Furukawa S Kobayashi K Usuda K Tamura T Miyamoto Y Hayashi K Ikeyama S Goryo M Okada K 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》1999,61(1):41-44
A pinealoma (benign) was found in a 61-week-old male Crj:CD (SD) IGS rat. The neoplasm was located between the cerebral hemispheres and the cerebellum. Histologically, the tumor cells consisted of two cell types: large, pale-staining cells and small dark-staining cells. A fibrovascular stroma divided the tumor cells into incomplete lobules or nest structures. Relatively numerous mitoses were noted in the tumor cells. Ultrastructurally, the tumor cells contained dense-cored vesicles, approximately 120 nm in diameter. 相似文献
38.
K Ohara Y Kobayashi N Tsuchiya H Furuoka T Matsui 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》2001,63(10):1127-1130
A 5-month-old, male, Shih Tzu dog manifesting polyuria and polydipsia since 2-month-old was presented to our hospital with additional clinical complaints of vomiting and depression during recent a few days. Despite the symptomatic therapy for chronic renal failure, he died on the day after medication. Macroscopically, both kidneys were small in size with rough surface. Microscopical examination revealed bilateral renal fibrosis with dysplastic changes consisting of immature glomeruli and tubules, and foci of adenomatoid proliferation of tubular epithelium. In addition, incomplete lobulation of medulla with pelvic structures was also noticed in the right kidney. From these findings, the present case was diagnosed as renal dysplasia in Shih Tzu dog which was documented in the literatures. 相似文献
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