Involvement of GnRH and Gonadotropin Genes in Oocyte Development of Blue Gourami Females (<i>Trichogaster trichopterus</i>)

The goal of this study was to gain a fundamental understanding of RnRH 1 and 3, as well as FSH and LH action, in ovarian follicles during oocyte growth by examining changes in ovarian gene transcription in blue gourami females (Trichogaster trichopterus). The levels of target ovarian mRNAs were determined by quantitative real-time PCR. GnRH1 mRNA levels were higher in oocytes at the previtellogenic stage compared to the vitellogenic and follicular oocytes maturation (FOM) stages. No significant differences in GnRH3 mRNA levels were detected among oocytes during the different stages of development. βLH and βFSH mRNA levels were lower in oocytes at the vitellogenic stage compared to the previtellogenic stage. The high transcription of GnRH 1 and 3 in the brain and of FSH and LH in the pituitary of blue gourami as was found in previous studies in our laboratory, compared to mRNA levels changed in ovary during oogenesis, supporting the hypothesis that differences exist between the function of endocrine and autocrine/paracrine of these hormones.

Somatolactin Transcription during Oogenesis in Female Blue Gourami (<i>Trichogaster trichopterus</i>)

Somatolactin (SL), a specific pituitary hormone belonging to the prolactin (PRL) super family, is involved in background adaptation, osmoregulation, reproduction and fatty acid metabolism. The goal of this study was to examine the gene transcription of SL changes in the ovary of blue gourami females (Trichogaster trichopterus) during oogenesis by quantitative real-time polymerase chain reaction (Real-Time PCR). Somatolactin in the pituitary was higher in females at low vitellogenesis compared to females with oocytes in maturation, and the difference was significant (p < 0.05). No significant differences were found in mRNA levels between low and high vitellogenesis, and high vitellogenesis and maturation. The findings of this and previous studies demonstrate that SL, growth hormone (GH) and PRL are involved in oogenesis in blue gourami;however, considerably more studies are required in order to separate the functions of these hormones.

Expression of SOX3 and SOX9 Genes in Gonads of Blue Gourami

In vertebrates, SOX (SRY-related HMG box) genes are thought to be due to major gene duplication events, initially occurring during early stages of metazoan evolution and later during the transition between non-vertebrate chordates and vertebrates. The aim of this study is to examine SOX3 and SOX9 transcription in oogensis and spermatogenesis in a fish model, the blue gourami (Trichogaster trichopterus). In females during oogenesis, SOX9 mRNA levels were lower compared to SOX3 mRNA levels. In males, SOX9 mRNA levels were higher in testes compared to SOX3 mRNA levels, however no significant differences between SOX3 and SOX9 mRNA levels were observed in the gonads of males that were kept under non-reproductive conditions compared to males kept with females under reproductive conditions and that were nest-builders.

Male Blue Gourami (Trichogaster trichopterus) Nest-Building Behavior Is Affected by Other Males and Females

In this study, we examine male blue gourami (Trichogaster trichopterus) nest-building behavior that is affected by other males and interactions under experimental conditions. Males found in the area control the territory and sexual behavior, and are influenced by the behavior of other males. The results of this study show that the sexual behavior (nest-building) of male blue gourami is affected both by the behavior and pheromones of other males. We suggest that males must defend their territories in order to prevent these two factors from interfering in nest-building.

Acoustic and visual adaptations to predation risk: a predator affects communication in vocal female fish

Predation is an important ecological constraint that influences communication in animals.Fish respond to predators by adjusting their visual signaling behavior,but the responses in calling behavior in the presence of a visually detected predator are largely unknown.We hypothesize that fish will reduce visual and acoustic signaling including sound levels and avoid escalating fights in the presence of a predator.To test this we investigated dyadic contests in female croaking gouramis(Trichopsis vittata,Osphronemidae)in the presence and absence of a predator(Astronotus ocella-tus,Cichlidae)in an adjoining tank.Agonistic behavior in T.vittata consists of lateral(visual)displays,antiparallel circling,and production of croaking sounds and may escalate to frontal displays.We analyzed the number and duration of lateral display bouts,the number,duration,sound pressure level,and dominant frequency of croaking sounds as well as contest outcomes.The number and duration of lateral displays decreased significantly in predator when compared with nopredator trials.Total number of sounds per contest dropped in parallel but no significant changes were observed in sound characteristics.In the presence of a predator,dyadic contests were decided or terminated during lateral displays and never escalated to frontal displays.The gouramis showed approaching behavior toward the predator between lateral displays.This is the first study supporting the hypothesis that predators reduce visual and acoustic signaling in a vocal fish.Sound properties,in contrast,did not change.Decreased signaling and the lack of escalating contests reduce the fish's conspicuousness and thus predation threat.