• Fisheries and Aquatic Sciences
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• v.2 no.2
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• pp.142-148
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• 1999

Monthly changes in the gonad index (GI), egg-diameter composition, gonadal development, reproductive cycle of the ark shell, Scapharca subcrenata, were investigated by histological method and morphometric data. This species is dioecious and oviparous. The gonad is located among the subregion of mid-intestinal gland, digestive diverticula and the outer fibromuscular layers compacted by the fibrous connective tissues and muscle fibers. The gonad index sharply increased in May, reached the maximum value in June, and then gradually decreased from July to December. The reproductive cycle of this species can be divided into six successive stages: early active stage (January to May), late active stage (June to July), ripe stage (June to August), partially spawned stage (July to September), degenerative stage (August to December), and resting stage (January to April). S. subcrenata spawns once a year between July and early September, and the main spawning occurred between July and August when the water temperatures were above $20^{\circ}C$. This evidence suggest that timings of maturation and spawning are closely related to water temperatures. Even though the spawning period was once a year, it is assumed that the number of spawning frequencies (broods) may occur more than twice during the spawning season.

• The Korean Journal of Ecology
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• v.10 no.3
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• pp.119-127
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• 1987

On the east slope of the front ranges of the Colorado Rockies, USA, three species of Populus are distributed at different elevations from the Great Plains to the timberline. At elevations 1, 720m (P. sargentii), 2, 335m (P.angustifolia) and 3, 190m (P.tremuloides) chlorophyll cotents of leaves of thses dioecious trees were determined. Total chlorophyll content was in the range of 0.86-1.56mg/g leaf, increasing with elevation as a second-degree polynomial, and the peak content was estimated to be reached at about 2, 800m. Total chlorophyll content was greater in female than in male trees in the two higher elevation species, but not in P. sargentii, the low elevation species. Chlorophyll b content was greater than chlorophyll a content in the same two higher elevation species. The increase of chlorophyll b than to increase of chlorophyll a content. These phenomena appear to be the result of adaptation of these species to different environmental conditional at different elevation. Sequential distribution of plant populations on environmental gradients in such a way that variation in given plant characters paralell the environmental gradient must occur not only in ecotypes of a species, but also in different but closely related species.

• Journal of Aquaculture
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• v.13 no.4
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• pp.353-357
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• 2000

Porphyra pseudolinearis and P. dentata from Korea were crossed and the hybrid was cultured at different temperatures (5, 10, 15, 20 or $25^{\circ}C$), photon flux densities (10, 20, 40 or 80${\mu}$mol m$^{-2}$s$^{-1}$) under photoperiods (14L:10D and 10L:14D). In the hybrids, the conchocelis grew faster at 2$0^{\circ}C$ and 40$\mu$mol m$^{-2}$ s$^{-1}$ at $25^{\circ}C$ only, and were abundant, when cultured under 10L:14D. Foliose thalli of the hybrid grew rapidly at conditions of 10-2$0^{\circ}C$, 10L:14D and 15-2$0^{\circ}C$, 14L:10D but slowly at 5 and 2$0^{\circ}C$. No archeospores were observed any tested culture condition. Spermatangial and zygotosporangial sori were formed at the marginal portion o mature thallus. Zygotospores from the hybrid were released at 10-2$0^{\circ}C$ under both photoperiods, and gave rise to form conchocelis filament. Monoecious thalli were observed at 1$0^{\circ}C$ under 14L:10D. Neither monospores nor protothalli were produced from the conchocelis in culture.

• ALGAE
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• v.21 no.1
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• pp.15-48
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• 2006

The genus Martensia (Delesseriaceae, Rhodophyta) is characterized by thalli composed of one to several blades that consist of proximal membranous sections and distal latticework. Nerves or veins are absent in the membranous sections. The life cycle of Martensia is accomplished by isomorphic alternation of generations. The gametophytes of Martensia are dioecious, and the male and female gametangial plants are morphologically similar. The type species of Martensia is M. elegans Hering. In this study, nine species were confirmed to occur in the subtidal regions of Jeju Island, Korea: M. albida sp. nov., M. australis Harvey, M. bibarii Y. Lee, M. elegans Hering, M. flammifolia sp. nov, M. fragilis Harvey, M. jejuensis Y. Lee, M. palmata Y. Lee, and M. projecta Y. Lee. Three of these, M. australis, M. fragilis, and M. elegans, are new records in the flora of Korea. The results of molecular analyses of the internal transcribed spacer (ITS) 1 region in the nrDNA showed that M. elegans is identical to M. australis, and M. fragilis coincides with M. bibarii. It may be a less effective tool for the species discrimination in Martensia.

• The Korean Journal of Malacology
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• v.4 no.1
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• pp.30-41
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• 1988

The gonadal development, the annual reproductive cycle and the first sexual maturity of surf clam, Mactra veneriformis Reeve were studied histologically. Speciemens were monthly collected at the intertidal zone of Naechodo, Chollabuk-do, Korea, for one year from March 1986 to February 1987. Sexuality of the clam is dioecious. The gonads were located between the subregion of mid-intestinal gland in the visceral cavity and the reticular connetive tissues of the foot, The ovary is composed of a number of ovarian sacs, and the testis comprise several testiculat lobules. The undifferentiated mesenchymal tissues and eosinophilic granular cells function as nutritive cells in the early stage. The ripe eggs were about 50-60${\mu}{\textrm}{m}$ in diameter, and they were wurroundedby the gelatinous membranes. The spawing period was from early June to September the main spawning occurred beetween July and August when the water temperature reached above 24$^{\circ}C$. The annual reproductive cycle of this species could be classified into five successive stages: multiplicative(January to March), growing(March to May), mature(April to August), spent(June to September), degenerative and resting(September to February). The monthly changes of fatness coefficient closely correlated with the annual reproductive cycle. Percentages of the first sexual maturity of female and male clams were over 50% among those individals ranging from 2.1 To 2.5cm, and 100% in those over 2.6cm in shell length.

• Proceedings of the Korean Society of Developmental Biology Conference
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• 2001.02a
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• pp.46-49
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• 2001

R. Philippinarum is dioecious and oviparous. In the early vitellogenic oocyte, the Golgi apparatus and mitochondria present in the perinuclear region are involved in the formation of lipid droplets and in lipid granule formation. In the late vitellogenic oocyte, the endoplasmic reticulum, mitochondria in the cytoplasm are involved in the formation of proteid yolk granules. At this time, exogenous lipid granular substance and glycogen particles in the germinal epithelium are passed into the ooplasm of oocyte through the microvilli of the vitelline envelope. Ripe oocytes are about 55-60 $\mu$ m in diameter. The spawning period was once a year between early June and early October, and the main spawning occurred between July and August when seawater temperature was approximately 20 C. The reproductive cycle of this species can be categorized into five successive stages: early active stage (February to March), late active stage (April to May), ripe stage (April to August), partially spawned stage (June to October), and spent/inactive stage (August to March). Gonad developmental phases by histological qualitative analysis showed similar results with those of quantitative image analysis.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.39 no.5
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• pp.398-403
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• 2006

Gonad development and the gametogenic cycle of pen shells, Atrina pectinata, collected from November 2004 to October 2005 in the coastal waters of Jangheung, Jeollanam-do, Korea were investigated histologically. The clams are dioecious. The gonads consist of a number of gametogenic follicles. The sex ratio (Female:male) was 1:1.2. The gonad index (GI) reached a maximum in May and a minimum in July. The condition index (CI) reached a maximum in April and a minimum in June. The gonadosomatic index (GSI), GI and CI all increased with gonad development. The gametogenic cycle of the clam could be divided into five stages: the degenerative/inactive (August to October), early active (November to March), late active (December to April), ripe (May to June) and spent (June to July) stage.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.39 no.1
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• pp.27-34
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• 2006

Sexual maturation and reproductive cycle of the bat star Asterina pectinifera were investigated by histological method. Specimens were collected monthly in Donghwari, Gosunggun, Korea from January 2004 to February 2005. The bat star was dioecious. The gonads are composed of a number of gametogenic follicles. The gonadosomatic index (GSI) of female and male were reached the maximum in July (5.72, 4.54) and the minimum in December (0.89) and January, February (0.51), and the gonad index (GI) of female and male were reached the maximum in July (3.53, 3.91) and the minimum in August (0.95) and October to December (1.0), respectively. The main spawning was from August to September. The reproductive cycle of the bat star could be divided into five stages: in the female, inactive (November-February), early active (January February), late active (March-June), ripe (July), spent and degenerative (August-November) and in the male, inactive (November-February), early active (January-March), late active (April-June), ripe (July), spent and degenerative (August-October), respectively.

• Journal of Aquaculture
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• v.16 no.4
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• pp.245-251
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• 2003

Sexual maturation and gametogenic cycle of the hard shelled mussel, Mytilus coruscus were investigated by means of histological method. Specimens were collected monthly in Hansan Bay of south coast, Korea from January to December 2002. Sex of the clam was dioecious. The gonads are composed of a number of gametogenic follicles. The gonad index (GI) was reached the maximum in February (3.40), and the minimum in August (1.18). The monthly variation of condition index (CI) coincides with gonad index. The main spawning occurs between February and March. The gametogenic cycle of the clam could be divided into six stages: resting (August to November), multiplicative (November to December), growing (December to January), maturation (January to February), partially spent (February to April) and completely spent/degenerative stage (April to July). Sex ratio (♀/♂) was 1:0.96.

• The Korean Journal of Malacology
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• v.22 no.2
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• pp.143-150
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• 2006

The gonad index, condition index, reproductive cycle and spawning of the pen shell Atrina (Servatrina) pectinata were investigated using samples from the subtidal zone of Nokdo on the Boryeong coastal waters of Korea. Samples were collected monthly by SCUBA divers for one year from January to December, 2001. A. (Servatrina) pectinata is dioecious and oviparous. The spawning season of this species occurred once a year from June to August, with the main spawning occurring between June and July when the seawater temperature was around $20^{\circ}C$. Ripe oocytes were about 60-65 ${\mu}m$ in diameter. The reproductive cycle of this species could be classified into five successive stages; early active stage (November to March), late active stage (February to May), ripe stage (April to July), partially spawned stage (June to August), and spent/inactive stage (August to October). Monthly changes in the gonad index reached a maximum (4.6) in May (ripe stage), thereafter, the GI values gradually decreased from June to August when spawning occurred continuously. Therefore, monthly changes in the GI values showed a similar pattern to the gonadal phase. The condition index (CI) of the meat part without the posterior adductor muscle reached the maximum in June (ripe and partially spawned stage) and the minimum in September (spent/inactive stage), Accordingly, monthly changes in the condition indice of the meat part without the posterior adductor muscle coincided with the gonadal phases.