• Development and Reproduction
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• v.2 no.2
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• pp.141-148
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• 1998

The fine structure of spermatozoa of Pungtungia herzi was examined with scanning and transmission electron microscopies. The spermatozoa of p. herzi are approximately 37.4 ${\mu}{\textrm}{m}$ in length and a relatively simple cell with a spherical nucleus, a short midpiece and a tail. The acrosome is not present as in most teleost fishes. The ultrastructure of spermatozoa represents typical characteristics of cyprinid spermatozoa including the lateral insertion of flagellum, the organization of centriolar complex in shallow nuclear fossa, and the occurrence and asymmetrical arrangement of mitochondria. In the nuclear envelope and mitochondrion, however there were some morphological differences for their ultrastructure. The nuclear envelope is severely undulated and the shallow nuclear fossa contains two centrioles which are at the angle of some 130$^{\circ}$ each other. The most significant feature can be observed with the mitochondrion; five or more mitochondria, which are shown in primary spermatocyte, fuse to form a single one in the mature spermatozoon. The mitochondrial aspect is different from that of other cyprinid spermatozoa, where their mitochondria have a conventional aspect and never fuse to form a mitochondrial derivative. In terms of sperm evolution the fused mitochondria are regarded as the apomorphic character in comparison with the separate mitochondria. The single mitochondrion is not reported in cyprinid spermatozoon except the case of Rhodeus.

• Korean journal of applied entomology
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• v.40 no.1
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• pp.15-21
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• 2001

A new species, Geocenamus seonunensis n. sp. and an unknown species, Geocenamus processes (Siddiqi, 1979) Brzeski, 1991 were newly reported from Korea. The Korean specimens closely related to G. myungsugae Choi & Geraert, 1993 but differ from G. myungsugae in having; Lip region set off by constriction and much longer stylet (Lp region is button-like , set off, stylet 22~$27{\mu}$m in G. myungsugae). It further differs from G. tumensis (Skwiercz, 1984) Brzeski, 1991 in having spermatheca rounded, stylet much longer, from G. superbus (Allen, 1955) Fortuner & Luc, 1990 in having tail terminus annulated, from G. brevicaudatus (Peng & Hunt, 1995) Brzeski, 1998 in having much longer stylet, from G. longus (Wu, 1969) Tarjan, 1973. in having smaller number of longitudinal striae. Another Korean specimens are well corresponded with Geocenamus processus (Siddiqi, 1979) Brzeski, 1991 ex- cept male tail tip which is not flagellum-like.

• Applied Microscopy
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• v.32 no.4
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• pp.303-310
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• 2002

Spermatogenesis and sperm ultrastructure are investigated by means of light and transmission electron microscopy in the equilateral venus, Gomphina veneriformis which is dominant bivalve in the east coast of Korea. In the active spermatogenic season, testis consists of numerous spermatogenic follicles which is contains germ cells in the different developmental stage. The spermatogonia attached to spermatogenic follicle wall and has a large nucleus with electron-dense nucleolus. The spermatocytes are characterized by appearance of synaptonemal complex and well-developed Golgi complex. Nucleus of spermatid consists of numerous heterogeneous granules with high electron density. Karyoplasmic condensation, acrosome and flagellum formations are observed during spermiogenesis. Testicular matured sperms of sperm bundle consists of head, midpiece and tail. The head is about $8.5{\mu}m$ long and comprises a long nucleus and a bullet-like acrosome ($8.5{\mu}m$ in length). Acrosomal rod of microfilaments is observed in the lumen between nucleus and acrosome. The midpiece has four mitochondria. And tail has the typical '9+2' microtubule system.

• Applied Microscopy
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• v.33 no.3
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• pp.243-250
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• 2003

Ultrastructural changes of the male germ cells and structure of spermatozoa in Paralichthys olivaceus were examined by means of the light and transmission electron microscopes. The spermatogonium has a large nucleus with a single nucleus with a single nucleolus in the interphase. Primary spermatocytes are identified by the formation of the synaptonemal complex in the karyoplasm. The secondary spermatocytes are more concentrated and contains numerous cell organelle in the cytoplasm. The nucleus of spermatid in spermiogenesis is more condensed in the karyoplasm, and show spherical structure in shape. Mitochondria of the spermatids are observed in the lower portion of the nucleus. The spermatozoon consists of the head, mid piece and tail. The acrosome is not observed in the head. Axial filaments of the flagellum consists of nine pairs of the peripheral microtubules and one pair of the central microtubules.

• Microbiology and Biotechnology Letters
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• v.33 no.1
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• pp.1-8
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• 2005

Since Anton van Leeuwen­hoek first observed a surface-associated multicellular structure of bacterial cells in the 17th century, it has been shown to exhibit an ability to form a biofilm by numerous bacterial species. The biofilm formation is composed of distinct developmental stages, which include an attachment/adhesion of a single cell, a proliferation toward monolayered coverage, a propagation to aggregated microcolony, a maturation to 3-dimensional structure, and subsequently a local degradation. Investigation to identify the essential factors for bacterial biofilm formation has been performed via classical genetic approaches as well as recently developed technologies. The initial stage requires bacterial motility provided by a flagellum, and outermembrane components for surface signal interaction. Type IV-pilus and autoaggregation factors, e.g., type I-fimbriae or Ag43, are necessary to reach the stages of monolayer and micro colony. The mature biofilm is equipped with extracellular polymeric matrix and internal water-filled channels. This complex architecture can be achieved by differential expressions of several hundred genes, among which the most studied are the genes encoding exopolysaccharide biosyntheses and quorum-sensing regulatory components. The status of our knowledge for the biofilms found in humans and natural ecosystems is discussed in this minireview.

• Journal of Microbiology and Biotechnology
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• v.20 no.1
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• pp.15-20
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• 2010

A Gram negative, aerobic, nonspore-forming, straight or curved rod-shaped bacterium, designated Gsoil $317^T$, was isolated from soil of a ginseng field in Pocheon Province (South Korea) and was characterized using a polyphasic approach. Cells were dimorphic, with stalk (or prostheca) and nonmotile or nonstalked and motile, by means of a single polar flagellum. Comparative analysis of 16S rRNA gene sequences revealed that strain Gsoil $317^T$ was most closely related to Caulobacter mirabilis LMG $24261^T$ (97.2%), Caulobacter fusiformis ATCC $15257^T$ (97.1 %), Caulobacter segnis LMG $17158^T$ (97.0%), Caulobacter vibrioides DSM $9893^T$ (96.8%), and Caulobacter henricii ATCC $15253^T$ (96.7%). The sequence similarities to any other recognized species within Alphaproteobacteria were less than 96.0%. The detection of Q-10 as the major respiratory quinone and a fatty acid profile with summed feature 7 ($C_{18:1}\;{\omega}7c$ and/or $C_{18:1}\;{\omega}9t$ and/or $C_{18:1}\;{\omega}12t;$ 56.6%) and $C_{16:0}$ (15.9%) as the major fatty acids supported the affiliation of strain Gsoil $317^T$ to the genus Caulobacter. The G+C content of the genomic DNA was 65.5 mol%. DNA-DNA hybridization experiments showed that the DNA-DNA relatedness values between strain Gsoil $317^T$ and its closest phylogenetic neighbors were below 11%. On the basis of its phenotypic properties and phylogenetic distinctiveness, strain Gsoil $317^T$ should be classified as representing a novel species in the genus Caulobacter, for which the name Caulobacter ginsengisoli sp. novo is proposed. The type strain is Gsoil $317^T$ (=KCTC $12788^T=DSM\;18695^T$).

• Asian-Australasian Journal of Animal Sciences
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• v.21 no.2
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• pp.181-189
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• 2008

The aim of this study was to evaluate the effects of $Ca^{2+}$, $HCO_3{^-}$ and BSA on the in vitro capacitation-associated protein tyrosine phosphorylation, hyperactivation and acrosome reaction in guinea pig sperm. Caudal epididymal sperm were incubated in four different groups: modified TALP (Tyrode's albumin lactate pyruvate) or TALP without one of the medium constituents ($Ca^{2+}$, $HCO_3{^-}$ and BSA). After incubation for the required time (0 h, 0.5 h, 1 h, 3 h, 5 h, and 7 h), sperm were removed for further experiment. The capacitation effect was assessed by CTC (Chlortetracycline) staining. Western blotting and indirect immunofluorescence were used to analyze the level and localization of tyrosine phosphorylation. The results showed that guinea pig sperm underwent a time-dependent increase in protein tyrosine phosphorylation during the in vitro capacitation and the percentage of protein tyrosine phosphorylated sperm increased from 36% to 92% from the beginning of incubation to 7 h incubation. Also, there was a shift in the site of phosphotyrosine-specific fluorescence from the head of sperm to both the head and the flagellum. Moreover, an absence of $Ca^{2+}$ or $HCO_3{^-}$ inhibited in vitro hyperactivation and acrosome reaction and decreased the phosphorylation of the proteins throughout the period of in vitro capacitation. However, an absence of BSA could not influence these processes if substituted by polyvinyl alcohol (PVA) in the medium.

• Journal of Microbiology and Biotechnology
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• v.20 no.2
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• pp.415-424
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• 2010

The purpose of this study was to investigate the relationship between the global regulatory mechanism known as quorum sensing and expression of virulence factors in Escherichia coli O157:87. A nonpolar luxS deletion was introduced into the chromosome of strain CI03J, a human clinical isolate from South Korea, to create the ${\Delta}luxS$ mutant strain ML03J. Phenotypic characterization of wild-type and mutant strains demonstrated that ML03J had no obvious growth or metabolic defects on 0.2% glucose LB medium, produced a functionally defective flagellum, and could not utilize sorbose; the biological significance of sorbose utilization is unknown. Omics-based analysis revealed the involvement of LuxS in the transcriptional activation of several flagella/chemotaxisrelated genes (flhD; fliA, C, D, S, Z; and cheA, Y, Z), repression of glutamate-dependent acid resistance genes (gadAB), and expression of virulence factors including Shiga toxin, hemolysin, and SepD within the LEE pathogenicity island.

• Animal cells and systems
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• v.11 no.2
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• pp.141-146
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• 2007

Cantharidin is produced by blister beetles (Coleoptera: Meloidae) and smaller oedemerid beetles (Coleopetra: Oedemeridae) and is found in hemolymph and various tissues. The function of cantharidin in the courtship behaviour of meloids had never been fully established. Our studies show a correlation between density of cuticular pores and cantharidin titre of the scape and pedicel segments of male specimens of the East African species of Epicauta nyassensis (Haag-Rutenberg, 1880) (Coleoptera: Meloidae). Light microscopy of semi-thin cross sections of the male scape and pedicel indicates that there are many canal shaped structures that stretch from the antennal hemolymph to the antennomere surface. These structures may be tubules, which transport cantharidin circulating in the hemolymph to the surface, where the compound can be released via cuticular pore openings. Analyses of the head capsule and antennal segments of E. nyassensis females which had been copulated with males revealed low titre of cantharidin in the first two antennal segments. The density of the scape and pedicel pores of females was to some extent higher than the density of these pores on flagellum; however it was considerably lower than that of the males. Interestingly, no tubular cell or other transport structures were found in the cross sectioning of the female antennomeres or on the integument surface. During mating, male antennomeres, as well as cantharidin containing pores which are located on the $1^{st}\;and\;2^{nd}$ antennomeres, come into direct contact with the female antennae and may release cantharidin to their surface. Female E. nyassensis may be able to discriminate the opposite sex with abundant reserves of cantharidin prior to mating. This is another evidence that cantharidin function in close range sexual selection.

• The Korean Journal of Malacology
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• v.21 no.2 s.34
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• pp.95-105
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• 2005

Gonadosomatic index, reproductive cycle, spermatogenesis and first sexual maturity of Chlamys farreri were investigated by cytological and histological observations, from January 1998 to December 1999. The gonadosomatic index (GSI) rapidly increased in April and reached a maximum in May when seawater temperature rapidly increase. Then the GSI gradually decreased from June to August when spawning occur. Accordingly, monthly changes in the GSI in males coincide with the reproductive cycle. The spermatozoon of Chlamys farreri is the primitive type found in external fertilization species. The head of the spermatozoon is approximately $2.75{\mu}m$ in length including the acrosome measuring about $0.50{\mu}m$ in length, and its tail was approximately $20{\mu}m$, the axoneme of the tail flagellum consists of nine pairs of microtubules at the periphery and a pair at the center. Five spherical mitochondria around the centriole (the satellite body) appear in the middle piece of the sperm. The spawning period was from June to August and the main spawning occurs from July to August when seawater temperatures are greater than $20^{\circ}C$ The reproductive cycle of this species can be categorized into five successive stages; early active stage (January to March), late active stage (March to April), ripe stage (April to August), partially spawned stage (June to August), and spent/inactive stage (August to January). Over 50% of male scallops attained first sexual maturity between 50.0 and 60.0 mm in shell height, and 100% of those over 60.0 mm in shell height achieved maturity. Accordingly, we assume that male individuals begin reproduction at three years of age.