• 한국동물학회:학술대회논문집
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• 한국동물학회 1999년도 한국생물과학협회 학술발표대회
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• pp.172.1-172
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• 1999

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• Journal of Plant Biology
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• 제34권4호
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• pp.267-273
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• 1991

Polyamine levels in the male and female cells as well as DNA methyltransferase activity in the female cells during gametogenesis of Chlamydomonas reinhardtii indicated that both spermidine and spermine levels were decreased while DNA methyltransferase activity was markedly increased about 12 hours after the onset of gametogenesis. In vitro, putrescine and spermine at 1 mM inhibited methylation of chloroplasts DNA isolated from vegetative female cells by 35% and 65%, respectively. Spermine was found to be more inhibitory than putrescine at all concentrations tested. The pattern of the inhibition by polyamines appeared different from that caused by cations. The results obtained in this work suggest that the polyamine inhibition of DNA methylation is due to an action of polyamines on the enzyme involved instead of on the DNA itself.

• Journal of Plant Biology
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• 제38권1호
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• pp.25-32
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• 1995

The distribution of RNA in the anther wall of Brassica napus during male gametogenesis was followed by 3H-uridine autoradiography. Silver grain(SG) density was not above background in the anther wall just after microspore was released from tetrad callose wall. Significant accumulation of SGs occurred in tapetum, endothecium, and epidermis before microspore vacuolation. Accumulation of RNA in the tapetal cells was peak before the vaculation occurred in the microspore. With the onset of tapetal senescence at the partially vacuolated microspore stage, SGs decreased and they completely disappeared in the tapetum at the bicelled pollen stage. Accumulation of RNA in the endothecial cells was peak after the microspore mitosis and continued just after the generative cell mitosis. Appreciable SGs also occurred in cells of epidermis from nonvacuolate microspore stage to bicelled pollen stage. During this period, SG density was almost same and was not high as compared with tapetum or endothecium. At tricelled mature pollen stage, no incorporation occurred in anther wall. SGs were found mostly over the nucleouls and chromation of the cell nuclei.

• Animal cells and systems
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• 제16권2호
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• pp.135-144
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• 2012

$Dendronephthya$ $castanea$ Utinomi, 1952 is a member of the family Nephtheidae, and dominates shallow waters adjacent to the southern part of Jejudo Island, Korea. This species is a gonochoric internal brooder with a sex ratio of 1:1, and releases planulae around the time of the full and new moon from July to September, when the seawater temperature peaks. The gametogenic cycle is annual, and oogenesis (12 months) is longer than spermatogenesis (4-5 months). No difference in reproductive features including sexuality, sex ratio, gametogenesis and gametogenic cycles was found between the sympatric species $D.$ $castanea$ and $D.$ $gigantea$, and there was no temporal reproductive isolation. Investigation of the morphological taxonomy and molecular biology of these species indicates that they have very similar or identical traits, suggesting an absence of speciation and a need for taxonomic reclassification.

• Animal cells and systems
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• 제12권4호
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• pp.231-240
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• 2008

The gorgonian coral Anthoplexaura dimorpha Kukenthal, 1908(Gorgonacea: Octocorallia) is abundant in Jejudo Islands, Korea. To investigate the sexual reproduction of this species, we surveyed the morphology and cycle of gametogenesis. 5-6cm long fragments from 3-7 randomly chosen colonies were collected monthly at a depth of 12-24m in the water surrounding Munseom from August 2003 to August 2005. This species was gonochoric with sex ratio of 1.86:1(female to male), and had one annual reproductive cycle affected by elevation of seawater temperature. Oogenesis was longer than spermatogenesis as 12 months in female and 6 months in male. The planulae were not observed from the field survey and histological sections, which suggested broadcast spawning for the reproductive mode in this species. The possible spawning events may occur after the seawater temperature attain to the annual peak in September.

• 한국패류학회지
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• 제31권2호
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• pp.113-121
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• 2015

Gametogenesis, mating behaviour and spawning of Octopus ocellatus were investigated by histological study. This species is dioecious, and showed a protandry phenomenon. Ooogenesis (in females) and spermatogenesis (in males) can be classified into 3 stages, respectively. O. ocellatus copulates in one of two ways: a male may leap upon a female, mounting her mantle, or a male may sit near the female and extend the hectocotylized third right arm toward her. Spawning occurred between April and June in females, and between March and May in males of O. ocellatus. The spawning period was once a year and the peak took place between May and June. A number of flatened follicle cells, which were attached to an oocyte, were involved in vitellogenesis in the cytoplasm of the vitellogenic oocyte (maturing oocyte), and formation of chorion membrane (secondary egg membrane) of the ovarian eggs. Fecundity per female closely related to GSI was 294-660 eggs (average, 429 eggs). The diameters of the ovarian eggs surrounded by chorion membrane were approximately in the range of 10.10-2.50 mm. Each ovarian egg laid by a female was connected to an egg string. Each egg string was 1-5.5 cm (average 3.6 cm). The total number of eggs laid by a female of this species ranged 218-314, the egg sizes were independent to the size of female adult. this species has a life mode showing some special reproductive characteristics of an annual semelparity as shown in Octopodidae species because we have never seen a female spawning a second time.

• 한국패류학회:학술대회논문집
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• 한국패류학회 2003년도 추계학술대회
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• pp.31-31
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• 2003

• 환경생물
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• 제20권3호
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• pp.268-275
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• 2002

Seasonal variation in reproductive condition of the Pacific oyster Crassostrea gigas was investigated from a suspended cultured oyster population in Gosung Bay, South Korea using histological techniques, Gametogenesis of oysters initiated in February when water temperature reached 11 to $13^\circ{C}$. Increase in oocyte size and the number resulting in follicle expansion was observed from March to May First spawning of oysters observed in mid Jun when the surface water temperature reached 22 to $25^\circ{C}$. Spawning activity of oysters extended from mid June to late September with two marked spawning peaks in June and August. Most oysters collected from October to December exhibited few residual eggs in packed follicles exhibiting a typical spent condition. No gametes were observed from December to February from oysters collected in the Bay. Gonadal development of oysters in the Bay seemed to follow a seasonal fluctuation in environmental conditions such as water temperature and food availability in the water column. Spawning of oysters in late June was in part associated with sudden drop in salinity due to vast amount of freshwater input in the Bay after the summer flooding. Sex ratio of oysters was 59.5% male and 39.8% female. Less than 1 percent (0.6%) of the oysters examined were hermaphrodite; few eggs were observed in testis.

• 한국수산과학회지
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• 제36권2호
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• pp.157-162
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• 2003

Ultrastructure of germ cell during gametogenesis of surf clam, Spisula sachalinensis were investigated by electron microscopic observations. Oogonia are oval in shape and 5-6 ${\mu}m$ in diameter. They contain a large nucleus and have several mitochondria in the cytoplasm. Vitellogenic oocytes grew attached by a stalk to the germinal epithelium in the ovarian sac and their cytoplasm contained many yolk granules, lipid granules and mitochondria. Mature oocytes measuring 50-60 ${\mu}m$ in diameter have a nucleus containing an electron dense nucleolus, and a lots of yolk granules, lipid granules, mitochondria, rough endoplasmic reticulum and cortical granules were present in the cytoplasm. The surface of the plasma membrane in mature oocytes was formed of microvilli approximately 1.5 ${\mu}m$ long and enveloped in the vitelline layer. Spematogonia are oval in shape and about 5 ${\mu}m$ in diameter. Sprmatogonia develop into spermatocyte, spermatid and spermatozoon. The spermatozoon consisted of the head, midpiece and tail. The sperm head with diameter of about 1.5 ${\mu}m$ was ovoid, and contained the nucleus which consisted of acrosome. The four mitochondria encircled the centrosome in midpiece. The flagellum measuring about 40 ${\mu}m$ long had the classical 9+2 axoneme structure.

• Clinical and Experimental Reproductive Medicine
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• 제40권3호
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• pp.107-114
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• 2013

Homeobox genes play essential roles in embryonic development and reproduction. Recently, a large cluster of homeobox genes, reproductive homeobox genes on the X chromosome (Rhox) genes, was discovered as three gene clusters, ${\alpha}$, ${\beta}$, and ${\gamma}$ in mice. It was found that Rhox genes were selectively expressed in reproduction-associated tissues, such as those of the testes, epididymis, ovaries, and placenta. Hence, it was proposed that Rhox genes are important for regulating various reproductive features, especially gametogenesis in male as well as in female mammals. It was first determined that 12 Rhox genes are clustered into ${\alpha}$ (Rhox1-4), ${\beta}$ (Rhox5-9), and ${\gamma}$ (Rhox10-12) subclusters, and recently Rhox13 has also been found. At present, 33 Rhox genes have been identified in the mouse genome, 11 in the rat, and three in the human. Rhox genes are also responsible for embryonic development, with considerable amounts of Rhox expression in trophoblasts, placenta tissue, embryonic stem cells, and primordial germ cells. In this article we summarized the current understanding of Rhox family genes involved in reproduction and embryonic development and elucidated a previously unreported cell-specific expression in ovarian cells.