• Title/Summary/Keyword: Early sexual maturation

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Maturation and Spawning of the Korean Anchovy Coilia nasus on the West Coast of Korea (한국 서해산 웅어, Coilia nasus 암컷의 성숙과 산란)

  • Jun, Je-Cheon;Kang, Hee-Woong;Lee, Bong-Woo
    • Development and Reproduction
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    • v.13 no.2
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    • pp.123-132
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    • 2009
  • The gonadosomatic index (GSI), fatness, ovarian development, first sexual maturity, and fecundity of the Korean anchovy Coilia nasus were investigated by histological observations and morphometric analysis from January to December, 2007. The GSI and fatness began to increase in February, and reached the maximum in June when the ovary was getting mature and spawning occurred. Thereafter these parametes rapidly decreased in July when spawning occurred. Therefore, monthly changes in the GSI and fatness were closely related to ovarian maturation and spawning. The duration of ovarian development in females can be classified into five successive stages: early growing stage (February to March), late growing stage (March to April), mature stage (May to June), ripe and spent stage (June to July), and recovery and resting stage (December to January). Maturation and spawning of this species occurred between June and July during the period of high seawater temperature-long day length. Percentages of first sexual maturity in female individuals were over 50% for fish ranging 24.1 to 27.0 cm in total length, and 100% for fish over 30.1 cm in total length. The number of total eggs and mature eggs in the absolute fecundity were increased with the increase of total length and body weight, respectively. The number of total eggs and mature eggs in relative fecundity were also proportional to total length, but rather these numbers decreased in the maximum body weight (126.0${\sim}$150.0 g).

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Inhibitory Conditions of Asexual Development and their Application for the Screening of Mutants Defective in Sexual Development (Aspergillus nidulans에 있어서 무성분화(無成分化)의 억제조건(抑制條件)과 이를 이용(利用)한 유성분화결손(有性分化缺損) 돌연변이주(突然變異株)의 대량분리(大量分離))

  • Han, Dong-Min;Han, Yoo-Jeoung;Lee, Young-Hoon;Jahng, Kwang-Yeop;Jahng, Seung-Hwan;Chae, Keon-Sang
    • The Korean Journal of Mycology
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    • v.18 no.4
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    • pp.225-232
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    • 1990
  • In order to find an useful condition under which the mutants defective in sexual development could be isolated, the effects of several cultural conditions on the developments of Aspergillus nidulans were examined. Among several conditions found to restrict the asexual sporulation but enhance the sexual process, the interference of aeration by sealing the plates with sealing film was the most useful one for the purpose of mutant isolation. Sealing at any time before 20 hours from inoculation prevented both sexual and asexual process. When the seal was removed after 24 hours, however, the mycelia developed only to sexual organs. Using this properity, the early morphogenic process of sexual development could be easily observed and a number of mutants that showed some defects in the process could be isolated. The mutants were divided into 3 groups, NSD (never in sexual development), BSD (block in sexual development) and ASD (abnormal in sexual development). NSD mutants never produced either the $H{\ddot{u}}lle$ cells or cleistothecia and some produced the asexual organs even when the aeration was restricted. BSD mutants were blocked in the process of $H{\ddot{u}}lle$ cell, cleistothecia, crozier, asci or ascospore formation. ASD mutants had defects in the amount of cleistothecia, time of cleistothecial maturation or color of ascospores.

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Sexual Maturation and Artificial Spawning of the Hard Clam, Meretrix Iusoria (Bivalvia: Veneridae) on the West Coast of Korea

  • Chung, Ee-Yung;Kim, Yong-Min;Hur, Young-Baek;Ryu, Dong-Ki
    • The Korean Journal of Malacology
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    • v.21 no.2 s.34
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    • pp.81-93
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    • 2005
  • Reproductive cycle with the gonadal phases, first sexual maturity, artificial spawning amount by the size and spawning interval of the hard clam, Meretrix lusoria were investigated by histological observations and morphometric data by artificial spawning induction. Meretrix lusoria is dioecious and oviparous. The reproductive cycle of this species can be classified into five successive stages: early active stage (January to March), late active stage (February to May), ripe stage (April to August), partially spawned stage (June to September), and spent/inactive stage (September to February). The spawning period was from June to September, and the main spawning occurred between July and August when the seawater temperature exceeds over $20^{\circ}C$. Percentage of first sexual maturity of female and male clams ranging from 40.0 to 45.0 mm in shell length was over 50%, and all clams over 50.0 mm in shell length sexually matured. Female and male clams ranging from 40.0 to 45.0 mm in shell length are considered to be two years old. Therefore, we assume that the hard clams of both sexes begin reproduction from two years of age. The mean number of the spawned eggs increased with the increase of size (shell length) classes. In case of artificial spawning induction, the number of spawned eggs from the clams of a sized class was gradually decreased with the increase of the number of the spawning frequencies (the first, second, and third spawnings). In the experiments of artificial spawning induction during the spawning season, the interval of each spawning was estimated to be 15-18 days (average 17 days).

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Sexual Maturation and the Sex Ratio of the Jedo Venus, Protothaca jedoensis (Bivalvia: Veneridae) (살조개, Protothaca jedoensis의 성성숙과 성비)

  • Kim, Ji-Hyun;Chung, Ee-Yung;Kim, Yong-Ho
    • The Korean Journal of Malacology
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    • v.19 no.1
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    • pp.9-17
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    • 2003
  • The gonad index (GI), reproductive cycle with gonad developmental phases, first sexual maturity and the sex ratio of the jedo venus, Protothaca jedensis, on the coastal waters of Boryeong, Korea were investigated by histological study. Samples were collected from the subtidal zone of Boryeong, Korea from January to December, 1999. Monthly changes in the gonad index in femal and male clams gradually increased from February and reached the maximum in May, and then the values rapidly decreased from June and reached the minimum in November as seen in variations of the reproductive cycle. The spawning period of this species was once a year between May and July, there was a spawning peak between June and July when seawater temperature was over 20$^{\circ}C$. The reproductive cycle of this species in female and male clams can be classified into five successive stages: early active stage (December to March), late active stage (February to June), ripe stage (April to July), partially spawned stage (May to July) and spent/inactive stage (July to January). Percentages of first sexual maturity of female and male clams of 30.1-35.0 mm in shell length were 52.6% and 60.0%, respectively, and 100% for the clams over 45.1 mm in shell length. The sex ratio of individuals > 30.1 mm in shell length was 1:1 (X$^2$ = 0.40, p > 0.05).

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Sexual Maturation, Sex Ratio and Hermaphroditism of the Pacific Oyster, Crassostrea gigas, on the West Coast of Korea

  • Chung Ee-Yung;Seo Young-Ho;Park Kwan Ha
    • Fisheries and Aquatic Sciences
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    • v.1 no.1
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    • pp.82-93
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    • 1998
  • Monthly changes of the gonad follicle index (GFI), reproductive cycle, egg-diameter composition, first sexual maturity of the Pacific oyster, Crassostrea gigas, were studied based on the samples which have been collected from the intertidal zone of Poryong west coast of Korea, from January to December, 1996. C. gigas, is dioecious, while a few individuals are alternatively hermaphroditic. Monthly variation of gonad follicle index (GFI) used for determination of spawning period, coincided with the reproductive cycle. GFI increased from April when seawater temperatures gradually increased and reached the maximum in May. And then, GFI sharply decreased from June to September due to spawning. Reproductive cycle of this species can be divided into five successive stages: in females, early active stage (March to April), late active stage (April to May), ripe stage (May to August), partially spawned stage (June to September) and spent/inactive stage (September to February); in males, early active stage (February to March), late active stage (April to May), ripe stage (May to September), partially spawned stage (June to September) and spent/ inactive stage (September to February). The diameter of fully mature eggs are approximately 50um. Spawning occurred from June to September, and two spawning peaks were observed in June and August when the seawater temperature was above $20^{\circ}C$. Percentages of the first sexual maturity of males of 20.1-25.0 mm in shell height were over $50\%$, while those of females of 25.1-30.0 mm in shell height were over $50\%$. All the males of > 30.1 mm and all the females of ^gt; 35.1 mm completed their first sexual maturity. The results suggest that C. gigas has a protandry phenomenon. Sex ratios of 919 oysters observed were 453 females $(49.29\%)$, 429 males $(46.68\%)$, 16 hermaphrodites $(1.74\%)$, and 21 indeterminate individuals $(2.29\%)$. In age class I, sex ratio of males were $64.00\%$, thus, a higher percentage than that of females. It was noted that $64.00\%$ of the young males (age class I) were more functional than females in age class I, but 2-3 year-old oysters showed higher percentage of females. Percentages of hemaphrodites in 2-3 year classes were relatively higher than those in other year classes. Histological pattern of hermaphrodites can be divided into two types: Type I (hermaphrodite having a number of newly formed developing oocytes on the oogenic tissues within a degenerating spermatogenic follicle after discharge of numerous spermatozoa) and Type II (hermaphrodite having two separate follicles in the same gonad).

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Are colony developmental stages of bumblebee, Bombus terrestris (hymenoptera: apidae) affected by different concentrations of sugar and honey solutions?

  • Imran, Muhammad;Ahmad, Munir;Naeem, Muhammad;Mahmood, Khalid;Nasir, Muhammad;Aslam Sheikh, Umer Ayyaz
    • International Journal of Industrial Entomology and Biomaterials
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    • v.34 no.2
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    • pp.23-31
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    • 2017
  • Bumblebees, more efficient than honeybees, provide important services for pollination especially in tomato, pepper, cucumber, strawberries and other crops grown under tunnel farming or glasshouse conditions to yield maximization. These bees require pollen and nectar to meet their dietary needs and maintain their colony structure, development and reproduction. Keeping in view their economic importance, the effect of five concentrations of sugar and honey solutions (1:1, 1:1.5, 1:2, 2:1,1.5:1) each as alternative to nectar were used to observe their effect on life history parameters of Bombus terrestris. The 1:1 ratio of sugar solution was found most effective followed by 1.5:1, 1:1.5, 1:2 and 2:1 and also more effective of all five concentrations of honey solutions on all three stages of colony development i.e., at colony initiation, colony development and colony maturation stages. At colony initiation stage, early pre-oviposition period ($6.40{\pm}0.97$ days), early emergence of first worker in the first batch ($25.40{\pm}1.21$ days) and maximum numbers of workers ($6.20{\pm}0.24$) emergence in the first batch were observed at 1:1 ratio of sugar solution. Colonies reared on 1:1 ratio of sugar solution reached earlier ($52.13{\pm}1.28$ days) at colony foundation stage with minimum mortality ($3.27{\pm}0.54$ workers). At colony maturation stage, maximum numbers of workers, sexual (males, queens) and maximum mother queen longevity was observed at the same 1:1 ratio of sugar solution. It can be suggested from present study that sugar solution as alternative of nectar at 1:1 ratio was better than other sugar concentration levels and also from those of honey solution.

Histological Study of the Early Gonadal Development and Sexual Differentiation in Rhynchocypris oxycephalus (버들치, Rhynchocypris oxycephalus 초기 생식소 발달과 성분화에 관한 조직학적 연구)

  • 박인석
    • Development and Reproduction
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    • v.2 no.1
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    • pp.69-74
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    • 1998
  • The early gonadal development and sexual differentiation of Rhynchocypris oxycephalus are described from the stage of hatching to 150 days after hatching. During this peroid, the average length of the body grew from 0.64 cm to 5.96 cm. the primordial germ cells (PGCs), which could be recognized at the time of hatching, began to protrude into peritoneal cavity at a standard total length of 1.91 cm. At a standard total length of 2.29cm, initial ovarian differentiation wasidentified by the transformation of PGCs to meiotic oocytes. Finally, at the standard total length of 5.96 cm, the female gonads gradually developed towards migratory nucleus oocytes, characterisiing the maturation. Oocytes proliferated rapidly after sex differentiation while the testis entered a period of quiescence, as they continued to multiply but did not undergo growth until the standard total length of 4.00 cm. At a standard total length of 4.00 cm, spermatocytes arrested in thephase of interkinesis, Sertoli-like cells and sperm duct formation, with signs of meiotic activity, were observed. Therefore it may be concluded that R. oxycephalus belongs to the differentiated type of gonochoristic teleosts.

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Ultrastructural Study of Germ Cells and Reproductive Cycle in Female Neptunea arthritica cumingii

  • Han, Ji-Soo;Chung, Ee-Yung;Park, Gab-Man
    • Proceedings of the Korean Society of Developmental Biology Conference
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    • 2005.07a
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    • pp.52-52
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    • 2005
  • Oogenesis, the gonadosomatic index (GSI), reproductive cycle and first sexual maturation of the female Neptunea (Barbitonia) arthritica cumingii have been investigated by light and electron microscope observations. In the early vitellogenic oocyte, the Golgi complex and mitochondria were involved in the formation of glycogen, lipid droplets and yolk granules. In late vitellogenic oocytes, the rough endoplasmic reticulum and multivesicular bodies were involved in the formation of proteid yolk granules in the cytoplasm. In particular, compared with the results of other gastropods, it is a different result that appearances of cortical granules at the cortical layer and microvilli on the vitelline envelope, which is associated with heterosynthetic vitellogenesis, were not observed in vitellogenic oocytes during oogenesis. A mature yolk granule was composed of three components: main body (central core), superficial layer, and the limiting menbrane, Monthly changes in the gonadosomatic index in females were studied in 2002 and 2003 were closely associated with ovarian developmental phases. Spawning occurred between May and August in 2002 and 2003 and the main spawning occurred between June and July when the seawater temperature rose to approximately 18${\sim}$23${\circ}$C. The female reproductive cycle can be classified into five successive stages: early activestage (Septmber to October), late active stage ( November to February), ripe stage (February to June), partially spawned stage (May to Aygust), and recovery stage (June to August).

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Ecological Study on the Seaweed Porphyra pseudolinearis Originated from the East Sea, Korea (동해안 고유종 긴잎돌김(Porphyra pseudolinearis)의 생태학적 연구)

  • Kim, Young-Dae;Lee, Ju;Son, Yong-Soo;Choi, Jae-Seok;Kim, Dong-Sam;Hong, Yong-Ki
    • Journal of Life Science
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    • v.14 no.2
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    • pp.331-338
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    • 2004
  • Growth and sexual differentiation of the seaweed Porphyra pseudolinearis Ueda have been investigated monthly in the intertidal zone of the East Sea, Korea. Young blades of P. pseudolinearis appeared at the beginning of October. Carp os pores were released at the end of November immediately after carposporangia formation. Then the thalli of P. pseudolinearis were extinguished at the end of March. Young thalli were budded through the stages of conchocelis and conchospore. Thalli showed lanceolate type in shape, cordate type in holdfast, absence of microscopic spinulate process and sexual generation. Ratios of length to width in female thalli ranged from 5.6 to 7.4 at the maturation in December and slightly decreased 3.3 to 4.8 in January and 4.9 to 7.3 in December while the ratios of male thalli ranged from 4.2 to 4.8 in January. On October 12, average five individuals were obsered in a quadrate (30 cm ${\times}$ 30 cm), 238$\pm$18 individuals for the maturation stage in December and then it was reduced to 150 individuals in February and 15 individuals in March. Average sex ratios for female, male and vegetative thalli were 31.3% 46.9% and 21.9% respectively in early December, the beginning time of sex maturation. The sex ratio of female and male thalli in December 17, changed to 69.4%, 30.6% respectively.

Genetic Control of Asexual Sporulation in Fusarium graminearum

  • Son, Hokyoung;Kim, Myung-Gu;Chae, Suhn-Kee;Lee, Yin-Won
    • 한국균학회소식:학술대회논문집
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    • 2014.10a
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    • pp.15-15
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    • 2014
  • Fusarium graminearum (teleomorph Gibberella zeae) is an important plant pathogen that causes head blight of major cereal crops such as wheat, barley, and rice, as well as causing ear and stalk rot on maize worldwide. Plant diseases caused by this fungus lead to severe yield losses and accumulation of harmful mycotoxins in infected cereals [1]. Fungi utilize spore production as a mean to rapidly avoid unfavorable environmental conditions and to amplify their population. Spores are produced sexually and asexually and their production is precisely controlled. Upstream developmental activators consist of fluffy genes have been known to orchestrate early induction of condiogenesis in a model filamentous fungus Aspergillus nidulans. To understand the molecular mechanisms underlying conidiogenesis in F. graminearum, we characterized functions of the F. graminearum fluffy gene homologs [2]. We found that FlbD is conserved regulatory function for conidiogenesis in both A. nidulans and F. graminearum among five fluffy gene homologs. flbD deletion abolished conidia and perithecia production, suggesting that FlbD have global roles in hyphal differentiation processes in F. graminearum. We further identified and functionally characterized the ortholog of AbaA, which is involved in differentiation from vegetative hyphae to conidia and known to be absent in F. graminearum [3]. Deletion of abaA did not affect vegetative growth, sexual development, or virulence, but conidium production was completely abolished and thin hyphae grew from abnormally shaped phialides in abaA deletion mutants. Overexpression of abaA resulted in pleiotropic defects such as impaired sexual and asexual development, retarded conidium germination, and reduced trichothecene production. AbaA localized to the nuclei of phialides and terminal cells of mature conidia. Successful interspecies complementation using A. nidulans AbaA and the conserved AbaA-WetA pathway demonstrated that the molecular mechanisms responsible for AbaA activity are conserved in F. graminearum as they are in A. nidulans. F. graminearum ortholog of Aspergillus nidulans wetA has been shown to be involved in conidiogenesis and conidium maturation [4]. Deletion of F. graminearum wetA did not alter mycelial growth, sexual development, or virulence, but the wetA deletion mutants produced longer conidia with fewer septa, and the conidia were sensitive to acute stresses, such as oxidative stress and heat stress. Furthermore, the survival rate of aged conidia from the F. graminearum wetA deletion mutants was reduced. The wetA deletion resulted in vigorous generation of single-celled conidia through autophagy-dependent microcycle conidiation, indicating that WetA functions to maintain conidia dormancy by suppressing microcycle conidiation in F. graminearum. In A. nidulans, FlbB physically interacts with FlbD and FlbE, and the resulting FlbB/FlbE and FlbB/FlbD complexes induce the expression of flbD and brlA, respectively. BrlA is an activator of the AbaA-WetA pathway. AbaA and WetA are required for phialide formation and conidia maturation, respectively [5]. In F. graminearum, the AbaA-WetA pathway is similar to that of A. nidulans, except a brlA ortholog does not exist. Amongst the fluffy genes, only fgflbD has a conserved role for regulation of the AbaA-WetA pathway.

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