• 한국수산과학회지
• /
• 제42권1호
• /
• pp.48-55
• /
• 2009

The gonad maturation and spawning of blue crab, Portunus trituberculatus (Miers, 1876) using samples caught by trammer net in the western coast of Korea from January to December. The gonadosomatic index (GSI) showed the highest value of 15.0 in June and lowest value of 1.29 in August. Hepatosomatic index (HSI) showed the lowest in the spawning season from June to July. Thereafter, from August the value started to increase to 5.77 in December, showing an adverse trend against GSI. In the histological studies of the female reproductive organ, the gonad filled with primary oocytes from January to February and secondary oocytes in May. The female gonads mature from June, and mature and immature groups could be distinguished from December to February or March. In August, female developed another cycle of gonad development, showing new primary oocytes in the gonads again. Some of female crabs had receptaculum filled with already active sperm cells in it from March to May. In the time of August to September, almost all the females had the sperm sacs in the receptaculum. From the result, the coupling period estimated from August to September. Total RNA and DNA values of the crabs were highest in May (2.51, $0.57{\mu}g/mg$). The DNA value remained unchanged except for the value in May ($0.09-0.13{\mu}g/mg$). while RNA value was lowest in January ($1.08{\mu}g/mg$). The RAN/DNA ratio was the lowest (6.23%) in May and highest (18.05%) in July. The value of correlations coefficient between body weight and fecundity of the crabs was higher that of between carapace width and fecundity.

• Ocean and Polar Research
• /
• 제43권4호
• /
• pp.365-370
• /
• 2021

Manila clam Ruditapes philippinarum is present at high rates of density in tidal flats in Cheonsu Bay on the west coast of Korea, where clams often exhibit mass mortalities in late summer. We monitored the pathologic condition of clams at Hwangdo tidal flat (HD) to understand the parasitic impacts on clam fitness. Manila clams were fully ripe in July and spawned during August and September, as the histology indicated. The histology revealed that clams in HD tidal flats were heavily infected by the protozoa parasite Perkinsus olseni, as the monthly prevalence ranged from 53% (September) to 93% (August). In addition, Manila clams were co-infected by the metazoan parasite Cercaria tapetis and Parvatrema duboisi with the prevalence of 0-33% and 0-14%, respectively. Massive hemocyte infiltration and subsequent inflammation were commonly observed from the gills of P. olseni infected clams. Clusters of P. olseni trophozoites and heavy hemocyte infiltration were also observed from the female gonad, suggesting that P. olseni interferes with host gonad maturation. The larval trematode occupied almost the entire host gonad, resulting in gonad castration. In addition, Metacercaria of P. duboisi were observed from the subsurface of the mantle. Ray's fluid thioglycollate medium assay (RFTM) indicated that clams collected in August and September contained approximately 4.0×106 P. olseni cells/g gills. Condition Index (CI) declined gradually from spring to early summer, and the decline in CI was interpreted as a consequence of the heavy parasitism, as the parasites drain the host's net energy to be used in somatic growth and gamete production.

• 한국산학기술학회:학술대회논문집
• /
• 한국산학기술학회 2012년도 춘계학술논문집 1부
• /
• pp.173-176
• /
• 2012

본 연구는 빈산소에 의한 둥근 성게 (Strongylocentrotue nudus) 수정란의 수정률 및 발생률에 관한 연구이다. 대조군 (normoxia)과 실험군 (hypoxia) 으로 나누어 수정률과 발생률의 변화를 관찰 하였으며 또한 gonad 세포의 유전자 발현의 차이를 봄으로써 스트레스 관련 유전자와 항산화 관련 유전자의 변화를 확인 할 수 있었다. 결과적으로 수정률에서는 큰 차이를 확인 할 수 없었던데 반해 발생률에 있어서 빈산소의 경우 전혀 발생이 진행되지 않는 것을 확인 할 수 있었으며 또한 빈산소에 노출된 gonad 세포의 경우도 스트레스 또는 항산화 유전자가 많이 발현 되는 것을 관찰 할 수 있었다. 앞의 실험을 토대로 빈산소 환경에서 유전자 발현량의 차이를 더욱더 수행함으로써 빈산소 상태에 따른 죽음의 바다의 증가 얼마나 위험한 것인지 더욱더 관찰 할 수 있을 것이다.

• 한국패류학회지
• /
• 제30권2호
• /
• pp.127-134
• /
• 2014

Gonad maturation of Manila clam, Ruditapes philippinarum was induced in this study using a recirculation system over 8 weeks in early spring. Clams used in the experiment were collected in $15^{th}$ April 2010 from the west coast of Korea, as the surface water temperature remained $11^{\circ}C$. To induce gametogenesis and subsequent maturation seawater temperature was elevated $1^{\circ}C$ per day over 10 days to reach $20^{\circ}C$. For the experiment, clams were raised in 120 L quadrangle tank maintained with re-circulated seawater system over 57 days. Water quality parameters including the water temperature, salinity dissolved oxygen, ammonium ion and nitrate levels in the tanks were monitored daily. Mixture of concentrated microalgae including Tetraselmis, Isochrysis, Pavlova and Thalassiosira weissflogii was supplied to clams twice a day, and quantity of the daily ration was adjusted as 3% of clam body dry weight. Histology was applied to examine gonad maturation. Daily monitoring of the water quality parameters indicated that the recirculation system supplied suitable environment to Manila clam; the nitrogenous components stayed below toxic levels (< 0.2 mg/L). At the beginning of the study, clams were mostly in early developing stage. As the seawater temperature reached $20^{\circ}C$, 10 days after the experiment, 20% of clams reached late development at 12 days. First ripe clams were observed at 42 days and 40% of clams were in ripe and ready for spawning at the end of study, 57 days after the experiment. In this study, gametogenesis of Manila clam was successfully induced by elevating water temperature and supplying commercially produced microalgae in a recirculation tank system.

• 한국어류학회지
• /
• 제21권3호
• /
• pp.141-148
• /
• 2009

Oryzias dancena를 해양생태계 위해성 평가를 위한 해양 생물모델로 연구하기 위한 기초적인 연구로 초기 성분화와 생식소 발달 과정을 조직학적으로 조사하였다. 원시생식세포가 처음 관찰된 시기는 수정 후 5일째이고, 수정 후 9일째에 장과 앞신장관 사이의 생식소 형성 부근으로 이동한 것이 관찰되었다. 부화 후 12일째의 생식소는 암 수로 분화가 이루어졌다. 부화 후 28일째 난소에서는 주변인기의 난모세포가 관찰되었으며, 28일째의 정소에서는 정소 소관의 수와 정원세포의 증가를 확인할 수 있었다. 산란은 부화 후 9주째에 이루어졌으며, 이 시기의 난소에서는 난황과립이 난 전체에 형성되는 성숙난과 배란 직후 성숙난이 빠져나간 흔적이 관찰되었다. 수컷 생식소에서 역시 많은 수의 정세포가 관찰되었으며 사정 직후 정자가 빠져나간 부분이 관찰되었다. 이상의 결과 본 종은 초기 성분화 과정에 자성 단계를 거치지 않고 정소와 난소로 분화하는 분화형 자웅이체에 속한다.

• 한국발생생물학회지:발생과생식
• /
• 제16권4호
• /
• pp.235-251
• /
• 2012

The reproductive activity in male mammals is well known to be regulated by the hypothalamus-pituitary-gonad axis. The hypothalamic neurons secreting gonadotropin releasing hormone (GnRH) govern the reproductive neuroendocrine system by integrating all the exogenous information impinging on themselves. The GnRH synthesized and released from the hypothalamus arrives at the anterior pituitary through the portal vessels, provoking the production of the gonadotropins(follicle-stimulating hormone (FSH) and luteinizing hormone (LH)) at the same time. The gonadotropins affect the gonads to promote spermatogenesis and to secret testosterone. Testosterone acts on the GnRH neurons by a feedback loop through the circulatory system, resulting in the balance of all the hormones by regulating reproductive activities. These hormones exert their effects by acting on their own receptors, which are included in the signal transduction pathways as well. Unexpected aberrants are arised during this course of action of each hormone. This review summarizes these abnormal phenomena, including various mutations of molecules and their actions related to the reproductive function.

• 한국양식학회:학술대회논문집
• /
• 한국양식학회 2003년도 추계학술발표대회 논문요약집
• /
• pp.28-28
• /
• 2003

Viable interspecific hybrids between yellowtail flounder (Pleuronectes ferrugineus, Store.) and winter flounder (Pleuronectes americanus, Walbaum) were produced by artificial insemination of yellowtail flounder eggs with winter flounder sperm. However, mean fertilization rate, hatching success and early survival up to 3 weeks post hatch were significantly lower than those of parental pure cross controls (P<0.01). Overall, cytogenetic traits (karyological analysis and estimation of cellular DNA contents using flow cytometry) of hybrid flounder were intermediate between the two parental species. Microsatellite assay was used to distinguish the parental genomes in the hybrids; in most cases, one allele was specific to each of the parents. Morphometrics assessed by body proportions indicated that hybrids generally displayed a morphology intermediate between the maternal and paternal species. Interspecific hybrids exhibited abnormal and retarded gonad development in both sexes based on histological analysis of gonads from adult fish. The sterility of the hybrids presents a significant advantage for their use in aquaculture, as potential escapees would not be capable of reproducing in the wild and contaminating natural stocks.

• 한국패류학회지
• /
• 제30권2호
• /
• pp.107-116
• /
• 2014

북한강에 서식하고 있는 엷은재첩의 산란생태를 파악하기 위하여, 생식소 발달단계에 따른 생식주기, 군성숙도, 난경의 월별변화를 조사하였다. 각장에 대한 각고, 각폭, 전중, 육중간 의 상대성장식에서 상관계수 ($R^2$) 는 0.921-0.984로 높은 상관관계를 나타내었다. 엷은재첩은 기수재첩 보다는 소형종이었으며, 동시자웅동체로서 체내에서 수정되어 아가미 보육낭에서 부화되어 체외로 방출하는 난태생종이었다. 월별 비만도는 0.14-0.21 범위로 동계인 12월-2월에 낮은 값을 보이다가 2월부터 서서히 높아지기 시작하여 5월에 0.21로 정점을 보였다. 월별 육중량비는 25.9-38.7%로 비만도의 월별 변화와 같은 경향을 나타내었다. 비만도와 육중량비의 정점이 생식세포의 최성숙기와 1-2개월 차이가 있었다. 생식소의 조직상, 비만도 및 생식세포의 월별 변화를 종합하면 북한강산 엷은재첩 생식년주기는 분열증식기(12-2월), 성장기(2-5월), 성숙기(6-8월), 완숙 및 발생기(8-11월), 회복기(11-12월) 로 구분되어 하계산란종이었다. 군성숙 각장은 12.6 mm 였으며, 16 mm 이상의 개체는 모두 성숙하여 아가미에 보육낭을 형성하였다.

• 한국양식학회지
• /
• 제8권4호
• /
• pp.327-341
• /
• 1995

유도된 3배체 미꾸라지, Misgurnus mizolepis를 재료로 생식소 발달을 조사하여 2배체와 비교하였다. 난소 외부 형태는 융합된 하나의 낭상으로 복강을 향해 horseshoe shape으로 발달하며 짧은 수란관을 통해 비뇨생식공(urogenital pore)으로 개구되는 구조였다. 3배체 난소는 얇은 나뭇잎 모양으로 2배체에 비해 작고, 미발달되었으며, 정소는 2배체보다 다소 작지만, 외형상 2배체와 유사하였다. 난소 발달 및 난자형성과정은 2배체에서 부화 후 100일에 성숙 난소 및 성숙 난모세포가 출현하는 비교적 빠른 발달을 보인 반면, 3배체에서는 부화후 9개월까지 제1차 성장기의 난모세포가 나타났을 뿐 더 이상 발달하지 않았다. 다만, 조사된 1마리의 5년산 3배체에서는 난소내 성숙 난모세포들이 관찰되었다. 비록 정소발달 및 정자형성과정은 3배체 수컷 역시 2배체와 동일하게 진행되었지만 3배체가 2배체에 비해 각 단계별 발달 시기는 지연되었고, 생식세포 핵의 크기는 크게 나타났다.

• 한국패류학회지
• /
• 제29권4호
• /
• pp.313-323
• /
• 2013

Gonad development, the reproductive cycle, first sexual maturty and size at 50% of group sexual maturity (the biological minimum size) of Gomphina (Macridiscus) veneriformis were investigated for clams collected from the coastal waters of Donghae City, the East Sea of Korea by histological, and morphometric analysis. Monthly variations of the gonad index showed a pattern similar to that of the reproductive cycle. The reproductive cycle with the gonad developmental stages in female and male G. (M.) veneriformis can be classified into five successive stages: early active stage (December to March), late active stage (March to June), ripe stage (June to July), partially spawned stage (June to August), and spent / inactive stage (September to December). The spawning period continued from June to August, with a peak between July and August when the seawater temperature exceeds $20^{\circ}C$. The percentages of first sexual maturities of female and male clams ranging from 25.1 to 30.0 mm were 56.3% in females and 61.1% in males, and for clams over 30.1 mm shell length, it was 100%. Shell lengths at 50% of group sexual maturity (biological minimum size, $RM_{50}$) were 27.71 mm in females and 26.31 mm in males. Because harvesting clams < 26.31 mm in shell length could potentially cause a drastic reduction in recruitment, a measure indicating a prohibitory fishing size should be taken for adequate fisheries management.