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Vasa, which is a conserved member of the DEAD-box protein family, plays an indispensable role in primordial germ cell proliferation. However, the expression of vasa gene during the reproductive cycle in ovoviviparous fish has not been documented. In this study, the full-length sequence of vasa was obtained from the ovary of Korean rockfish ( Sebastes schlegeli) using reverse transcription-PCR and rapid amplification of cDNA ends. The Vasa with a mature protein of 650 amino acids showed greatest homology (84%) with giant gourami ( Osphronemus goramy) and Pacific bluefin tuna ( Thunnus orientalis). The expression of vasa mRNA in Korean rockfish was detected in gonads only, suggesting its specific role in gonadal development. In addition, seasonal changes in the vasa expression levels were examined in gonads by quantitative real-time PCR. The vasa transcript levels in adult testis were found higher during spermatogenesis than during spermiation. The vasa transcript levels remained relatively high at the early ovary stage but declined during ovary maturation in adult female fish. These results suggest that the vasa gene play an important role in spermatogenesis and early oogenesis during the reproductive cycle of Korean rockfish. [ABSTRACT FROM AUTHOR]

As a specific gene of fish, cytochrome P450c17-II ( CYP17-II) gene plays a key role in the growth, development an reproduction level of fish. In this study, the single-stranded conformational polymorphism (SSCP) technique was used to characterize polymorphisms within the coding region of CYP17-II gene in a population of 75 male Japanese flounder ( Paralichthys olivaceus). Three single nucleotide polymorphisms (SNPs) were identified in CYP17-II gene of Japanese flounder. They were c.G594A (p.G188R), c.G939A and c.G1502A (p.G490D). SNP1 (c.G594A), located in exon 4 of CYP17-II gene, was significantly associated with gonadosomatic index (GSI). Individuals with genotype GG of SNP1 had significantly lower GSI ( P < 0.05) than those with genotype AA or AG. SNP2 (c.G939A) located at the CpG island of CYP17-II gene. The mutation changed the methylation of exon 6. Individuals with genotype AA of SNP2 had significantly lower serum testosterone (T) level and hepatosomatic index (HSI) compared to those with genotype GG. The results suggested that SNP2 could influence the reproductive endocrine of male Japanese flounder. However, the SNP3 (c.G1502A) located in exon 9 did not affect the four measured reproductive traits. This study showed that CYP17-II gene could be a potentially useful candidate gene for the research of genetic breeding and physiological aspects of Japanese flounder. [ABSTRACT FROM AUTHOR]

Cytochrome P450 aromatase (P450arom) plays a pivotal role in ovary development. In this study, we used semi-quantitative reverse transcription PCR (RT-PCR) to analyze spatiotemporal expressions of two P450arom genes ( CYP19A and CYP19B) and their responses to temperature stress in female yellow catfish ( Pelteobagrus fulvidraco). Tissue distribution pattern of CYP19 showed that CYP19B was abundantly expressed in fish brain and ovary (brain > ovary), but weakly in intestines, whereas CYP19A was exclusively expressed in ovary. Semi-quantitative RT-PCR analyses showed high transcript abundance of both CYP19A and CYP19B in the ovarian reproductive cycle, corresponding with serum estradiol-17 β (E) levels. Increases in aromatases, serum E and testosterone (T) levels in fish exposed to higher temperature indicated stimulation of ovarian maturation and recrudescence by heat stress in stages II and V during the ovarian cycle, whereas associated decreases in stage III suggested vitellogenesis inhibition by heat stress. Gene expression of CYP19 was closely related to levels of serum E. Results demonstrated CYP19 played a crucial role in the reproductive cycle of female yellow catfish. Different temperature stress affected CYP19 gene expression in the fish ovarian reproductive cycle. Associated P450arom genes could be useful for studying physiological aspects of yellow catfish. [ABSTRACT FROM AUTHOR]

The Hankel transform is an important transform. In this paper, we study the wavelets associated with the Hankel transform, then define the Weyl transform of the wavelets. We give criteria of its boundedness and compactness on the L p — spaces. [ABSTRACT FROM AUTHOR]