• Korean Journal of Ichthyology
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• v.32 no.2
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• pp.63-69
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• 2020

This study investigated spawning characteristics of Hangang bitterling, Rhodeus pseudosericeus inside the host mussel, Unio douglasiae sinuolatus at the Heukcheon Stream in Korea from April to June 2017. 327 mussels were collected, among them, 34 (14.1%) were spawned mussels of R. pseudosericeus with glochidia. The mean number of R. pseudosericeus embryos with or without glochidia by the mussel gill position was 5.0±3.58 (range, 1~8) vs. 2.8±2.13 (1~9) in the left outer demibranch, 1.5±0.96 (1~3) vs. 1.7±0.82 (1~3) in the left inner demibranch, 1.4±0.51 (1~2) vs. 2.1±1.85 (1~6) in the right inner demibranch, and 6.4±4.82 (1~20) vs. 3.0±1.86 (1~6) in the right outer demibranch. The frequency of R. pseudosericeus embryos with or without glochidia by the mussel gill position was 82.6% vs. 73.4% in the left outer demibranch, 17.4% vs. 9.4% in the left inner demibranch, 26.1% vs. 15.6% in the right inner demibranch, and 58.7% vs. 67.2% in the right outer demibranch. The mean number of R. pseudosericeus embryos with or without glochidia was 8.5±6.43 (1~23) vs. 4.5±3.38 (1~14). The number and frequency of R. pseudosericeus embryos were higher in the mussel with glochidia and the outer demibranchs than those without glochidia and with inner demibranchs.

• The Korean Journal of Malacology
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• v.27 no.1
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• pp.15-27
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• 2011

This study was performed to observe ultrastructure of the gill and to ascertain the effect of salinity on histopathological and ultrastructural changes in the gill of the Japanese clam, Corbicula japonica. Experimental period was 7 days. Experimental groups consisted of control, 5, 10, 20 psu. $LC_{50}$ (96 h.) by the probit was 19.55 psu. Mortality was significantly different from the control (p < 0.05). Inner demibranch of the gill of C. japonica was wider 1.37 times than outer demibranch (p < 0.001). The filament zone on the plica can be distinguished by the six epithelial celll cell; frontal ciliated epithelium ($7{\mu}m$), latero-frontal ciliated epithelium ($5{\mu}m$), postlatero-frontal epithelim ($3{\times}8{\mu}m$), and lateral ciliated epithelium ($5{\mu}m$) in the frontal zone, endothelial cellin the intermediate zone, and abfrontal cell in the abfrontal zone. It had one type of secretory cell that was filled with fibrous substances of low electron density. The gill of C. japonica exposed to 5 psu for 7 days was observed partially disappearance of the cilia, and glycogen granule in the filament. In the 10 psu, gill appeared partially modification of epithelial cell and destruction of the glycocalyx. Gill exposed to 20 psu was extended nuclus of the ciliated epithelial cell, destruction of the organelles, and observed glycogen granules infiltration and numerous vacuoles. Moreover, more than 50% filaments were observed that come out chitinous rod from disappearance of epithelial cell in the filament. Therefore, the destruction of the cilia and epithelial cell induce physiological activity and it may be leading directly to death.

• Korean Journal of Ichthyology
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• v.26 no.2
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• pp.83-88
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• 2014

An endemic Korean bitterling, Acheilognathus signifer, known as using freshwater mussels for its spawning activity, much prefers Lamprotula leai in Dalcheon stream (Goesan population) and Unio douglasiae sinuolatus in Gadaecheon (Danyang population) stream, Korea. The spawning pattern between two mussels and one bitterling was carried out in two populations from April to June, 2011 and 2013. L. leai in the Goesan population was bigger shell length and have more eggs, larvae or both with A. signifer than those of U. d. sinuolatus in the Danyang population. Also, A. signifer in the Goesan population appeared to have a longer ovipositor and lay ripen eggs more than those of A. signifer in the Danyang population. Glochidium, a larval stage, of some L. leai in the Goesan population was incubated in all the demibranch, whereas for all of U. d. sinuolatus in the Danyang population was found in the outer demibranch only. For L. leai in the Goesan population, the eggs, larvae or both of A. signifer were much more in the non-breeding mussels (giving no glochidium) than the breeding mussels having the glochidium. For U. d. sinuolatus in the Danyang population, in contrast, the non-breeding mussels have fewer eggs, larvae or both less than the breeding one.

• Korean Journal of Ichthyology
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• v.6 no.1
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• pp.39-50
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• 1994

Spawning of the bitterling, Acheilognathus yamatsutae into the mussel was studied from 1990 to 1992 in Lake Uiam, Korea. This fish preferred to spawn in certain mussel species such as Unio douglasiae, U. douglasiae sinuolatus, Lamprotula gottsehei and Anodonta arcaeformis flavotincta in order of preference. Within the same species of mussel, they preferred the larger size. Eggs and larvae were commonly located in the inner demibranch of mussels. Average number of eggs or larvae per mussel was 3.6(ranged from 1 to 35). The eggs of the bitterling were hatched out within 41 hours when water temperature remained over $20^{\circ}C$ and the larvae already possessed minute tubercles on the skin and yolk projections to prevent themselves being washed out from mussels.

• Korean Journal of Ichthyology
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• v.17 no.2
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• pp.105-111
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• 2005

Most of the eggs and (or) pre-larvae of Acheilognathus signifer were observed from the gills of Unio douglasiae sinuolatus, 30~45 mm in the shell length, that is the host mussel of A. signifer. There was no selectivity in proportion to mussel size at the range observed. One to seven individual eggs and (or) pre-larvae were found in the mussels, with a mean of 2.5 individuals, and the rate of possessing one egg and (or) pre-larva was 50.0%. When the prelarva of A. signifer acquired swimming ability inside the mussel, it moved into the suprabranchial chamber. It was estimated that the growth period was 4~6 weeks. The minute tubercles of the pre-larvae were observed immediately after hatching. Absorption of the minute tubercles was observed starting the 7 th day, with most of tubercles absorbed 13 days after hatching and completed 20 days after the yolk was entirely absorbed.

• Journal of fish pathology
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• v.21 no.1
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• pp.67-79
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• 2008

This study was conducted to find out biological response of bivalves exposed to tributyltin chloride(TBTCl). The results of the study confirmed that TBTCl induce the reduction of oxygen consumption rateand histopathological feature in the gill structure of equilateral venus, Gomphina veneriformis. The experi-mental groups consisted of a control and 3 TBTCl exposure groups (0.4, 0.6 and 0.8 yg TBTCl L') and theexperimental period was 36 weeks. For histological analysis, gill tissues were fixed in Bouin's fluid andthen stained H-E stain, AB-PAS (PH 2.5) reaction and Masson's trichrome stain after having serially sec-tioned the tissue by paraffin method at thickness of 4-6 (an. The oxygen consumption rate was not signifi-cantly different between the control and exposure groups at 4 weeks, but in all exposure groups at 28 weeks,it was significantly different to the control. Gill of G. veneriformis had demibranch that attached two sheetsof lamellae and a lamella was composed of numerous filaments, numbering 25 on average. The frontal fila-ment zone had three types of cilia; frontal, latero-frontal and lateral depending on locations while the lateralcilia were the longest and largest in number. The mucous cells observed in filaments were more abundant in(542c) in AB-PAS (PH 2.5) reaction. Gill exposed to TBTCl was extended hemolymph sinus and increased hemocytes at 4 weeks, and then it showed increases of mucous cells and partially disappearance of frontalcilia. In the group of 0.8 yg TBTCl L' at 12 weeks, hypertrophy of frontal and latero-frontal epithelia wasobserved. Also it observed m decrease of mucous cell containing weekly acid mucosubstance and appearedpartially destruction muscle fiber bundle, In the groups of 0.4 and 0.6 ug TBTCl L' at 36 weeks, it appearedpartially modification of epithelia and in 0.8 us TBTCl L' group, observed filaments that come out chiti-nous rod from disappearance of frontal and latero-frontal epithelia.

• Korean Journal of Environment and Ecology
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• v.34 no.4
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• pp.274-281
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• 2020

This study aimed to investigate the autumn spawning by bitterling (A. rhombeus) inside mussel (Unio douglasiae) and the adaptation characteristics at the Bongseocheon Stream of Mankyeonggang River. The survey was carried out between August 2015 and July 2016. The spawning season was from September to November, and 17-75 (36.2 ± 16.44) eggs were found from mature females. During the survey period, 476 mussels were collected, 129 (27.1%) of spawned A. rhombeus. Mussels that spawned eggs, embryos, and larva of A. rhombeus (46.3 ± 4.55 mm, n = 129) were larger than than those that did not spawn (42.6 ± 8.51 mm, n = 347). The appearance frequency of A. rhombeus larva before and after the formation of lens was 99.8% (n = 597) vs. 0.2% (n = 1) from October 2015 to March 2016, 25.6% (n = 23) vs. 74.4% (n = 67) in April 2016, 0% (n = 0) vs. 100% (n = 40) on May 2016. The number of eggs, embryos, and larvae of A. rhombeus inside the mussels were 1-18 (5.6 ± 3.81). The number and appearance frequency of A. rhombeus eggs, embryos, and larvae inside the mussel according to mussel gill demibranchs position were 1 (0.01 ± 0.09, n = 1) and 0.78% in the left outer demibranch, 1-18 (2.33 ± 3.31, n = 63) and 48.84% in the left inner demibranch, 1-15 (2.97 ± 3.79, n = 76) and 58.91% in the right inner demibransh, and 1-12 (0.33 ± 1.71, n = 7) and 5.43% in the right outer demibransh. The highest frequency of the developmental position of eggs, embryos, and larvae occurred 71.8% (n = 445) in lower part 3 (L3) before formation lens and 94.4% (n = 102) in L3 after formation lens, indicating that L3 was dominating position for eggs, embryos, and larvae. More eggs, embryos, and larvae of A. rhombeus were found more often in the inner demibranshs than outer demibranchs. Since A. rhombeus is a species that spawn in the autumn and thus avoids the competition with interspecific and glochidia. However, they have to spend the winter in low water temperature. Consequently, we assume that A. rhombeus have evolved toward embryonic diapause under the low water temperature before the formation of lens and spawning inside the supracranchial cavity to save the transit energy from the water space to the suprabranchial cavity after the achieving movement ability with the formation of lens.

• The Korean Journal of Malacology
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• v.23 no.1
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• pp.39-49
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• 2007

We investigated to understand the differences in the karyotypes and the reproductive characteristics between the diploid clam, Corbicula japonica in the brackish water and the triploid clam, C. fluminea in the freshwater. The number of chromosomes of the diploid C. japonica were 38, which can be grouped into 19 pairs of two homologues. These can be divided into 11 pairs of telocentric, 4 pairs of subtelocentric, 3 pairs of submetacentric and one pair of metacentric chromosomes. C. japonica is oviparous and dioecious. The clam has two pairs of gills, with the inner and outer-demibranchs, however, they do not act mainly as marsupia. External fertilization occurs in the brackish water. The triploid marsh clam, C. fluminea has 54 chromosomes, which can be grouped into 18 sets of three homologues. These 18 sets can be divided into one metacentric group, five submetacentric groups and 12 subtelo- or telocentric groups. C. fluminea is ovoviviparous and functional hermaphrodite. The triploid condition may be closely related to hermaphroditism. This species has the inner-demibranchs acting mainly as marsupia. The depletion of ripe eggs occurred in the inner-demibranchs of the gill during the incubatory periods, and ripe eggs produced in the hermaphroditic follicles in the gonad during the non-incubatory periods. The gonad developmental stages of two marsh clams (C. japonica and C. fluminea) can be divided into five stages: early active stage, late active stage, ripe stage, partially spawned stages, and spent/inactive stage.