Effect of citral,eugenol, nerolidol and α-terpineol on the ultrastructural changes of Trichophyton mentagrophytes

The antifungal effects of citral, eugenol, nerolidol and α-terpineol on Trichophyton mentagrophytes were investigated. Citral over 0.1 mg/ml strongly inhibited the hyphal growth of T. mentagrophytes, and the antifungal activity of α-terpineol was less effective. The morphological changes of the fungus exposed to the terpenes were observed by electron microscopy. The hyphae were distorted and collapsed at 0.2, 0.4 and 1 mg/ml of eugenol, nerolidol and α-terpineol respectively, and cell membrane and organelles were irreversibly damaged at 0.2 mg/ml citral.     

Diel Variation in RNA/DNA Ratios of Japanese Flounder Paralichthys olivaceus

Laboratory-reared Japanese flounder Paralichthys olivaceus larvae (11.2 ± 0.2 mm total length; age 26 d) were sampled over a 48-h period to determine any diel patterns in RNA/DNA ratios. RNA/DNA ratios were highest during daytime periods (0800, 1100, 1400, 1700, 2000 h) and significantly reduced at night (2300, 0200, 0500 h). Findings from this study indicate a diel variation in biochemical condition and suggest that special care should be taken in sampling design and data analysis to account for this source of variability.     

Changes in the Chemical Characteristics of Gulbi,Salted and Dried Yellow Corvenia,During Drying at Different Temperatures

A few chemical characteristics of Gulbi, a traditional Korean seafood prepared from salted and dried Yellow corvenia (Pseudosciaena manchurica), were investigated during drying at different temperatures. When Gulbi was manufactured by sun-drying (the control), it had the highest thiobarbituric acid reactive substances (TBARS) and volatile basic nitrogen (VBN) values. They increased with increasing drying time at all temperatures in the hot-air drier. The TBARS value of Gulbi was lower when dried at 30 and 35°C than at 40°C and the control. The VBN of the control was higher than that of hot-air dried Gulbi at 30 and 35°C and lower than that of hot-air dried Gulbi at 40°C. The control had a VBN value of 20.8 ± 0.07% and the hot-air dried at 30°C, 18.0 ± 0.06; at 35°C, 18.6 ± 0.06; at 40°C, 23.8 ± 0.08 (p < 0.05), respectively. The salt content of the control and Gulbi dried at 30, 35, and 40°C were 22.9 ± 0.07%, 17.7 ± 0.06%, 18.0 ± 0.06%, and 24.3 ± 0.08%, respectively. The amino nitrogen content was much lower: 63.1 ± 0.80 mg/100 g and 65.5 ± 0.14 mg/100 g at 30 and 35°C than 78.3 ± 0.21 mg/100 g at 40°C. The results of this study also indicate that the Gulbi dried at 30 and 35°C had better chemical characteristics than those dried at 40°C when using hot-air drying and sun drying.     

Ontogenetic changes in RNA,DNA and protein contents of laboratory-reared Pacific bluefin tuna <Emphasis Type="Italic">Thunnus orientalis</Emphasis>

ABSTRACT:     The ontogenetic changes in the growth potential of larval and juvenile laboratory-reared Pacific bluefin tuna were examined based on RNA–DNA and protein–DNA ratios. Experimental fish were reared at the Ohshima Experiment Station of Kinki University Fisheries Laboratory in August 2002. Samples were taken from 13 to 35 days after hatching (DAH). Metamorphosis from larva to the juvenile stage was observed around 23 DAH. Somatic growth of Pacific bluefin tuna was accelerated after metamorphosis. The value of the RNA–DNA ratio from 13 to 19 DAH increased slightly from 3.77 ± 0.58 (mean ± SD) to 7.28 ± 2.23. After that, the ratio markedly increased from 13.89 ± 3.71 on 21 DAH to 19.11 ± 4.27 on 23 DAH, which was the end of the metamorphic period. After 25 DAH, the ratio remained at a high level of 15–20. The protein–DNA ratio showed a similar tendency to the RNA–DNA ratio. These results suggest that the rapid increase in the RNA–DNA ratio in the metamorphic period supports the consequent rapid somatic growth in the juvenile stage. The high ratio after the metamorphic period could be because of the species-specific traits large prey exhibit for their survival and because of the tuna's fast -growth after the juvenile stage.     

Enzyme-linked immunosorbent assay, single radial immunodiffusion, and indirect methods for the detection of failure of transfer of passive immunity in dairy calves

BACKGROUND: Confirmatory tests for failure of transfer of passive immunity (FTPI) in dairy calves require direct measurements of the serum immunoglobulin G concentration. Enzyme-linked immunosorbent assay (ELISA) has advantages over single radial immunodiffusion (SRID) in terms of cost and time. OBJECTIVES: To evaluate the agreement between ELISA and SRID, and to compare the diagnostic performance of ELISA with indirect methods, in the detection of FTPI in calves. ANIMALS: One hundred and fifteen dairy calves (aged 0-10 days) from 23 calf-rearing facilities. METHODS: Prospective, observational study. The agreement between SRID and ELISA was determined by the Bland-Altman method. Fixed bias (SRID - ELISA) was calculated. For comparison of the diagnostic performance of ELISA with indirect methods, sensitivity, specificity, and area under the curve (AUC) of receiver operating characteristic (ROC) curves were calculated at cut-off values of 500 and 1,000 mg/dL. RESULTS: The agreement between SRID and ELISA was 94%. Fixed bias (SRID - ELISA) was 140 +/- 364 mg/dL. The AUC and sensitivity of ELISA at the cut-off value of 1,000 mg/dL were higher than those of indirect methods (P<.004). The specificity of ELISA at the cut-off value of 1,000 mg/dL was not higher than that of indirect methods, except for serum total protein concentration assay. CONCLUSION AND CLINICAL IMPORTANCE: ELISA exhibited good diagnostic performance and good agreement with SRID. ELISA is an adequate method for both screening and confirmatory tests for FTPI in dairy calves at the cut-off value of 500 mg/dL.     

Genetic variation of hatchery and wild stocks of the pearl oyster <Emphasis Type="Italic">Pinctada fucata martensii</Emphasis> (Dunker, 1872), assessed by mitochondrial DNA analysis

In order to provide baseline information for the genetic resources, genetic variation in wild and cultured Pinctada fucata martensii from southern Korea and Japan was studied using nucleotide sequence analysis of 379 base pairs (bp) in the mitochondrial cytochrome oxidase subunit I gene (COI). The study included three hatchery stocks from Korea (Tongyeong) and Japan (Mie and Tsushima) and one wild stock from Korea (Geoje). A total of 3 haplotypes were identified in hatchery stocks of 78 individuals, of which 63 individuals shared 1 haplotype. Overall, nucleotide diversity (π) was low, ranging from 0.000 to 0.002, and haplotype diversity (h) ranged from 0.000 to 0.541. Considerably low haplotype and nucleotide diversities in hatchery stock indicated that low effective population size and consecutive selective breeding of P. fucata martensii could be responsible for the reduction in genetic variation. The wild stock exhibited low haplotype diversity (0.507 ± 0.039) with two shared haplotypes. The results of the present study with first record of wild pearl oyster in Korea support the possibility that the transplanted pearl oyster for overwintering experiments could have survived in winter. In order to enhance and/or maintain genetic diversity in the hatchery stock, further research should be directed toward genetic monitoring and evaluation of the hatchery and wild pearl oysters.     

Effects of shelter on growth and survival in age-0 black sea bass, Centropristis striata (L.)

Black sea bass Centropristis striata (L.) juveniles were reared in aquaria containing either shelter or no shelter to investigate the effects of shelter on growth and survival. The specific growth rates of juveniles were significantly higher in the sheltered aquaria. With shelter present, the average mortality of juveniles caused by agonistic behaviour was 44% compared with no mortality in the unsheltered aquaria. The results provide evidence that shelter is advantageous for growth, but not survival of black sea bass juveniles under culture conditions.     

Genetic variation and population structure of the Pacific cod <Emphasis Type="Italic">Gadus macrocephalus</Emphasis> in Korean waters revealed by mtDNA and msDNA markers

To investigate the extent of genetic differentiation among wild populations of the Pacific cod Gadus macrocephalus, we have examined genetic polymorphism at five locations within Korean waters [Boryeong in the West Sea (WC-BR); Jinhae Bay in the South Sea (SC-JH); Jumunjin (EC-JM), Jukbyeon (EC-JB), and Bangeojin (EC-BJ) off the eastern coast of Korea] using mitochondrial DNA (mtDNA) control region and microsatellite DNA (msDNA) markers. Nucleotide sequence analysis of 584 bp in the variable portion of the 5′ end of the mtDNA control region revealed 27 variable nucleotide sites among 184 individuals, which defined eight, three, and 11 haplotypes in the western, southern, and eastern coast populations, respectively. The mtDNA analysis revealed a low variability but significant local differentiation among populations from these three areas within Korean waters. msDNA analysis also revealed moderate polymorphism in the wild populations, with a mean of 13.8–22.6 alleles per locus for the five msDNA markers and observed (and expected) heterozygosities of 0.755 (0.825) for the WC-BR, 0.793 (0.810) for the SC-JH, 0.920 (0.905) for the EC-BJ, 0.783 (0.865) for the EC-JB, and 0.804 (0.812) for the EC-JM populations. Analysis of msDNA loci indicated that Pacific cod sampled at the WC-BR, SC-JH, and EC-JB sites belong to genetically distinct populations. However, no significant difference was found between the Pacific cod population from SC-JH and that from EC-BJ. Consequently, three genetically distinct populations, namely, WC-BR, SC-JH and EC-BJ, and EC-JB, were identified using msDNA analysis. These results indicate that genetically distinct populations of Pacific cod are present in Korean coastal waters where spawning aggregations occur.