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Reproduction control in multi-spawning asynchronic Tricho-gaster trichopterus (Pallas) as a model for anabantidae family. Trends in Comp. Biochem. Physiol., 1: 1269-1275
... In this study, it was found that the level of SOX9 transcription was high in mature males before sexual behavior and reproduction. A high level of sperm was found in the testis in both these stages [32], and spermatogenesis was controlled by gonadotropins (FSH and LH) and androgens hormones [20] [33]. Raghuveer and Senthilkumaran [34] observed that in breathing catfish Clarias gariepinus, which underwent an annual reproductive cycle, a dimorphic expression pattern of SOX9a and SOX9b was found in both adult and developing gonads using RT-PCR, indicating that SOX9a retained its function in testis while SOX9b might play a new role in ovary, as was revealed in the current study in blue gourami using real-time PCR. ...
... The synthesis of estrogens from androgens is catalyzed by the heme-binding enzyme, CYP19. Steroids involved in oogenesis and spermatogenesis in the blue gourami have been well described (for review see Degani, 2001, 1993b). ...
In this study, the involvement of the cytochrome P450 aromatase gene (CYP19) in the gametogenesis of the teleost blue gourami (Trichogaster trichopterus) is described. The blue gourami brain CYP19 (bgCYP19b) and gonadal CYP19 (bgCYP19a) aromatase genes were cloned and their expression analyzed during the different reproductive stages. The cloned cDNAs of the bgCYP19b and bgCYP19a were found to contain segments of 1518 bp (an open reading frame encoding a deduced protein of 506 residues) and 489 bp (encoding a peptide of 163 residues), respectively. Although the mRNA levels of bgCYP19b were very low in females until the vitellogenic phase, they were significantly higher in the final oocyte maturation stage. The aromatase gene mRNA levels in the gonads were significantly lower in females in the high vitellogenic stage, as compared to females during early vitellogenesis or maturation. In males, the mRNA levels of bgCYP19b were significantly lower in juveniles than in mature individuals. However, no significant differences were observed between mature non-reproductive and reproductive males. In addition, there was no significant difference between the expression of bgCYP19a in juvenile and non-nest building mature males, although a significant increase was detected in mature reproductive males. Although CYP19b expression was similar in both sexes, the expression of CYP19a was significantly different between males and females.
The purpose of the present study was to examine the genetic variation in Salamandra infraimma-culata from different breeding site habitats using the Amplified Fragment Length Polymorphism (AFLP) method. The results of the dendogram from a hierarchical cluster analysis show that the grouping of S. infraimmaculata as cluster 5 differs from all the other clusters, including the St1 (Tel-Dan stream) population, which was the most predictable. Five Haplogroups (Hg) were characterized. The mean number of alleles per locus in each population (Ne) ranged from 10.566 (Sp1) to 2.720 (Po6). An average estimated heterozygosity (He) by population ranged from 0.100 (Po6) to 0.186 (St1). Population St1, a permanent breeding site where water was available all year round, exhibited the highest level of polymorphism, while population Po6, from the ephemeral breeding site, exhibited the lowest level of polymorphism. Gene flow between clusters showed that clusters 3 and 4 are sources of migrants and also receive gene flow, while clusters 1 and 2 may be a source of migrants but may not receive much gene flow. A phylogenetic analysis, based on clustering using Nei's genetic distance, demonstrated that the Tel-Dan population is located on a separate branch within its sub-population. The conclusion of the present study shows that the genetic divergence among isolated populations is not correlated to distance but is affected by the variation of habitats.
In vertebrates, gonadotropin-releasing hormone (GnRH) and pituitary adenylate cyclase-activating polypeptide (PACAP) are key hormones regulating growth and reproduction in the brain-pituitary axis. The regulating hormonal interactions are of great interest, therefore, the aim of this study is to provide novel insights into the involvement of brain GnRH and PACAP in oogensis and spermatogenesis in a fish model, the blue gourami (Trichogaster trichopterus). cDNA cloning of two GnRH forms combined with phylogenetic analysis revealed that three paralogous GnRH forms exist in blue gourami and evolve as a result of genome duplication. GnRH1 mRNA levels are related to final oocyte maturation (FOM), and this peptide stimulated β follicle-stimulating hormone (βFSH) and growth hormone (GH) gene expression; GnRH2 stimulated β gonadotropins (GtH) gene expression and GnRH analog combined with PACAP-38 synergistically upregulate GH and βFSH gene expression. The data presented, together with previous studies in our lab, enable suggesting mechanisms explaining the physiological relevance of these peptides in the regulation of gametogenesis and steroidogenesis in blue gourami females. These findings support the biological importance of the GnRH and PACAP hormones family, enabling them to stimulate differential biological functions in the regulation of growth and reproduction.
Fish are ectothermic vertebrates, and their gonadal development and spawning are affected by changes in environmental temperature. Recent global temperature changes have increased the importance of studying the effect of temperature on reproduction. The aim of this paper was to study the effect of temperature on oogenesis and hormone gene expression related to reproduction and growth in the blue gourami female maintained under non-reproductive and reproductive conditions. In females under non-reproductive conditions, vitellogenic oocytes, gonadotropin-releasing hormone 3 (GnRH3), β luteinizing hormone (βLH) and growth hormone (GH) mRNA levels were affected by temperature changes. In females maintained under reproductive conditions with non-reproductively active males, a percentage of females in the final oocyte maturation (FOM) stage, pituitary adenylyl cyclase activating polypeptide (PACAP and PRP-PACAP), gonadotropins and GH mRNA levels were affected due to temperature changes. In females maintained under reproductive conditions with reproductively active males, also GnRH3 and insulin-like growth factor 1 (IGF-1) were affected by temperature changes. In conclusion, in blue gourami females, changes in environmental temperature affect oogenesis through changes in brain and pituitary hormone mRNA levels.
This study examined the effect of temperature on reproduction and growth-related factors in blue gourami males under nonreproductive and reproductive conditions. Males that were maintained under nonreproductive conditions did not build nest and the gonado-somatic index (% GSI) was significantly higher in fish maintained at 27°C compared with fish maintained at 23°C. The relative mRNA levels of brain gonadotropin-releasing hormone 3 (GnRH3), pituitary adenylate cyclase-activating polypeptide (PACAP), insulin-like growth factor-1(IGF-1), pituitary β-luteinizing hormone (βLH), and prolactin were significantly higher when the fish were maintained at 27°C than at 23°C or 31°C. β-Follicle-stimulating hormone (βFSH) mRNA levels were significantly lower when maintained at 31°C than at the other temperatures. Nests were observed only in males under reproductive conditions. In these fish, higher mRNA levels of GnRH3, PACAP, βFSH, βLH and prolactin were detected at 27°C, and higher mRNA levels of IGF-1 were detected at 23°C, when compared with other temperature of maintenance or with fish that did not build nest. In conclusion, we propose that temperature has more effect on the transcription of genes, associated with reproduction, than on those pertaining to growth.
In order to gain a better understanding of the roles of pituitary adenylate cyclase-activating polypeptide (PACAP) in reproduction and growth, the expression of the PACAP gene during the reproduction cycle and its potential role in regulating gonadotropin and growth hormone (GH) gene transcription in blue gourami were investigated. The cDNA sequences of the full-length blue gourami brain PACAP and that of its related peptide (PRP) were acquired. PACAP cDNA had two variants, obtainable by alternative splicing: a long form encoding for both PRP and PACAP and a short form encoding only for PACAP. In females, mRNA levels of PACAP were very high only in individuals with oocytes in the maturation stage, as compared to levels in unpaired vitellogenic and non-vitellogenic fish. The PACAP mRNA levels in males were high only in nest builders, as opposed to in non-nest building males and juveniles. In pituitary culture cells from high vitellogenic females, PACAP38 (the 38 amino acid form) only brought about an increase in betaFSH levels, without altering GH and betaLH mRNA levels. On the other hand, in adult non-reproductive male pituitary cells, PACAP38 decreased the GH mRNA level. Based on these results, we propose that in the blue gourami, PACAP is involved in the final oocyte maturation stage in females, whereas in males, it is associated with sexual behavior. In addition, the effect of PACAP38 on pituitary hormone gene expression is different in females and males, indicating that PACAP38 is potentially a hypophysiotropic regulator of reproduction, which mediates pituitary hormone expression.
To gain a better insight regarding the roles of gonadotropin releasing hormone3 (GnRH3) in the regulation of reproduction in the suborder Labyrinthici, GnRH3 expression was investigated during the reproduction cycle of the male and female blue gourami (Trichogaster trichopterus). The full-length blue gourami brain GnRH3 gene was sequenced (EMBL acc. no. EU107388) and was found to be expressed in both the brain and pituitary of the blue gourami. High mRNA levels were detected only in the brain of females with oocytes in the maturation stage. Correspondingly, significantly greater mRNA levels of GnRH3 were detected in mature males than in immature ones. In primary cultures of dispersed pituitary cells, GnRH3 significantly increased betaFSH and betaLH subunit mRNA levels in cells from both females and males, whereas GH gene transcription was affected differently by GnRH3 in females, as compared to males. Thus, we propose that GnRH3 can act differentially in the blue gourami females and males. In females, GnRH3 may be involved in the final maturation stage of the oocyte and induces betaFSH, betaLH and GH gene expression; in males, it is engaged in sexual behavior and spermatogenesis regulation via betaFSH and betaLH stimulation and dowregulation of GH transcription.
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