• Fisheries and Aquatic Sciences
• /
• 제24권12호
• /
• pp.437-445
• /
• 2021

Roughscale sole (Clidoderma asperrimum) is only wild caught because basic reproductive research on this species is lacking and gamete production in an artificial setting has not been successful. Exogenous hormone treatment has been used to induce gonadal maturation and final spermiation in wild-caught individuals. In this study, the effects of an exogenous hormone on spermiation in roughscale sole was investigated by implanting different concentrations of a salmon gonadotrophin-releasing hormone analog (sGnRH; 0, 25, 50, and 100 ㎍/kg body weight) into male fishes. The control group did not produce sperm after 21 days post-implantation, and the duration of spermiation was shorter compared to the other groups. The spermiation period and milt amount differed among the hormone-treated groups according to the hormone concentration used. Milt volumes in the groups treated with 25 and 100 ㎍/kg sGnRH increased compared to the control group, whereas exogenous hormone treatment had no effect on the movable sperm ratio. The spermatocrit was high at the beginning of spermiation in all groups and then tended to decrease gradually over time except in the experimental group treated with 100 ㎍/kg sGnRH. Plasma levels of testosterone, 11-ketotestosterone, 17α, 20β-dihydroxy-4-pregnen-3-one were not significantly affected by the sGnRH treatments. Our results demonstrate that it is possible to prolong the spermiation period and increase milt volume by treating male roughscale soles with an exogenous hormone. In addition, the artificial hormone treatment did not affect sperm motility.

• Animal cells and systems
• /
• 제16권2호
• /
• pp.127-134
• /
• 2012

We investigated the effects of fadrozol, an aromatase inhibitor (AI), and $17{\alpha}$-methyltestosterone (MT) on the induction of sex change in juvenile longtooth grouper $Epinephelus$ $bruneus$, via histological observation of gonads. Changes in the mRNA expression of GtH subunits (FSH-${\beta}$ and LH-${\beta}$) in the pituitary, and estradiol-$17{\beta}$ (E2) and 11-ketotestosterone (11-KT) levels in the blood were also surveyed after AI and MT treatment. Juvenile longtooth groupers ($113{\pm}17g\;body\;weight$; $16.2{\pm}1.2cm\;body\;length$) received intramuscular injections of AI at 3 (3-AI) and 5 (5-AI) mg/kg BWdoses and MT at a 5 mg/kg BW (5-MT) dose. At week 7 post-injection, 3-AI and 5-MT oocytes were degenerated, and gonads of the 5-AI group initiated spermatogenesis. At week 21 post-injection, 3-AI- and 5-MT-treated gonads contained spermatogonia and spermatocytes, while 5-AI treatment induced advanced stages of spermatogenesis. The serum E2 level showed no significant differences throughout the experimental period, whereas that of 11-KT was significantly elevated in the 5-AI group at weeks 7 and 21 post-injection. A significant increase in the expression of FSH-${\beta}$ mRNA was evident in the 5-AI group at week 21 post-injection. In contrast, LH-${\beta}$ mRNA expression did not significantly differ among groups during the experimental period. These results imply that sex change has two stages in the longtooth grouper. In the first stage, oocytes are degenerated by the stimulation by 11-KT, and in the second stage spermatogenesis occurs, owing to the co-effects of 11-KT and FSH-${\beta}$.

• 한국수산과학회지
• /
• 제34권1호
• /
• pp.13-16
• /
• 2001

수온과 광주기 조절에 따른 볼락, Sebastes inermis의 혈장내 성steroid hormone 변화를 조사하였다. 월별 GSI의 변화에서 암컷은 대조구의 경우 11월부터 증가하기 시작하여 1월에 최고값이 되었다. 수온과 광주기를 조절한 실험구중 조절에 반응한 개체들 (Tr-r)에서는 대조구 보다 1개월 늦은 2월에 최고값을 나타내었다 그러나 수온과 광주기의 조절에 반응하지 않은 개체들 (Tr-n)은 GSI의 발달이 중단되어 전 실험기간동안 1.2 이하의 낮은 값을 유지하였다. 수컷의 월별 GSI 변화는 대조구와 조절구 사이에서 뚜렷한 차이를 나타내지 않았다. 암컷에서 혈장 E2와 T의 변화는 GSI의 변화와 같이 수온과 광주기를 조절한 실험구가 대조구에 비해 2개월 늦게 최고값에 도달하였다. GSI의 월별 변화에서 차이가 없었던 수컷에서 혈장 11-KT와 T의 월별 변화도 대조구와 조절구에서 큰 차이를 보이지 않았다. 수온과 광주기를 자연상태보다 2개월 늦추어 사육한 결과, 자연상태의 대조구에 비해 암컷의 성숙이 지연되었다. 이것은 수온과 광주기의 자극이 시상하부-뇌하수체-생식소 축을 따라 전달되면서 성 steroid의 분비가 영향을 미쳤기 때문에 난소의 성숙이 지연되었다고 생각된다.

• 한국양식학회지
• /
• 제18권3호
• /
• pp.167-172
• /
• 2005

능성어 정자의 안정적 확보를 위하여 MT $0.5{\sim}2.0mg/kg$ BW를 어체 근육내 삽입하여 성전환을 유도하였다 사용한 실험어는 전장 $41.0{\pm}1.3cm$, 체중 $1.4{\pm}0.1kg$이었다. 실험 시작시 능성어 생식소는 주로 gonia cells과 주변인기 단계 난모세포를 가지고 있었다. 실험 종료시 대조구의 생식소는 실험 시작시와 유사하였다. 0.5 mg MT/kg BW 처리구 생식소는 실험 종료 때 소엽내강에 정원세포와 정세포 그리고 정자무리들이 대부분 차지하고 기부에 수정관이 형성되었으나, 일부 어린 난모세포들이 산재하였다. 1.0과 2.0 mg MT/kg BW처리구는 소엽내강과 기부의 수정관에 정자무리들로 가득 차 있었다. 정자는 $1.0{\sim}2.0mg$ MT/kg BW 처리구에서 얻을 수 있었다. MT 처리구의 T혈중농도는 대조구보다 2주 후부터 6주 후까지 높았으나(P<0.05), 배정이 가능한 8주째 대조구와 유사하였다(P>0.05). 11-KT 혈중농도는 MT 1.0처리구는 2주 후부터 6주째까지, 2.0 mg MT/kg BW 처리구는 2주 후부터 실험 종료 때까지 대조구 보다 높았다(P<0.05). $E_2$는 모든 실험어 일부에서 검출되었다.

• 수산해양교육연구
• /
• 제24권6호
• /
• pp.845-853
• /
• 2012

To investigate the role of temperatures and photoperiods as environmental cues regulating reproductive rhythm in Pseudobagrus fulvidraco, rearing experiments were conducted using sveral rearing regimes conbined with photoperiods and water temperatures during gonadal degeneration periods. Gonadosomatic index (GSI) in control was $8.16{\pm}1.50%$, while in other experiment GSI levels in female were lower than that in the control. In case of experimental precinct of 9 light (L) and 15 L, GSI levels were decreased. But GSI level with $20^{\circ}C$ was no diffrence after 40 and 60 days. GSI level in male of control was $0.35{\pm}0.05%$. GSI under 9 L and $25^{\circ}C$ was similar to that in control, whereas its level in other experiments was lower than that in control. Testosterone (T) of female was $3.68{\pm}0.22$ ng/mL at experimental precinct. In case of 9 L and 15 L, concentration of T were lower than experimental precinct in all of water temperature. Estradiol-$17{\beta}$ ($E_2$) and $7{\alpha}$, $20{\beta}$-dihydroxy-4-pregnen-3-one ($17{\alpha}20{\beta}OHP$) levels of female were $0.42{\pm}0.02$ and $0.83{\pm}0.01$ ng/mL at experimental precinct. $E_2$ levels of 9 and 15 L were higher than experimental precinct and $17{\alpha}20{\beta}OHP$ levels of 9 and 15 L were higher than experimental precinct. In case of T and 11-ketotestosterone levels were $0.69{\pm}0.11$ and $.62{\pm}0.03$ ng/mL in male. During the period of gonadal degeneration, gonadal maturation did not occur in any of the experimental regimes. However, comparatively high levels of $E_2$ observed at low temperature regimes ($20^{\circ}C$) regardless of photoperiods.

• Fisheries and Aquatic Sciences
• /
• 제3권1호
• /
• pp.37-43
• /
• 2000

We used a mammalian GnRH antagonist, $[Ac-3,4-dehydro-Pro^1,\;D-p-F-Phe^2,\;D-Trp^{3.6}]$-GnRH, to examine the details of the salmon type gonadotropin-releasing hormone (sGnRH) and GnRH agonist analog $(Des-Gly^{10}$[d-Ala^6]-ethylamide GnRH; GnRHa) functions in the control of maturational gonadotropin (GTH II) secretion, in precocious male rainbow trout, in both in vivo and in vitro experiments. In the in vivo study, plasma GTH II levels increased by sGnRH or GnRHa treatment, but the response was more rapid and stronger in the GnRHa treatment group. The increase in GTH II was significantly suppressed by the GnRH antagonist, while the antagonist had no effect on basal GTH II levels in both groups. The GnRH antagonist showed stronger suppression of GTH II levels in the sGnRH treatment fish than in the GnRHa treatment fish. In addition, plasma androgenic steroid hormones (testosterone and 11-ketotestosterone) increased by the sGnRH or GnRHa treatment. The GnRH antagonist significantly inhibited the increases in plasma androgenic steroid hormone levels stimulated by the sGnRH or GnRHa, while the antagonist had no effect on basal androgenic steroid hormone levels in both groups. In the in vitro study, treatment with sGnRH or GnRHa increased GTH II release from the cultured dispersed pituitary cells, but the response was stronger in the GnRHa treatment group. The increase in GTH II release by GnRH was suppressed by adding the GnRH antagonist, dose­dependently. On the other hand, basal release of GTH II did not decrease by the GnRH antagonist treatment in both groups. These results suggest that the GnRH antagonist, $[Ac-3,4-dehydro-Pro^1,\;D-p-F-Phe^2,\;D-Trp^{3.6}]-GnRH$, used in this study is effective in blocking the action of GnRH-induced GTH II release from the pituitary gland both in vivo and in vitro.