Dietary supplementation with chitin hydrolysates for Anguilla japonica leptocephali

Fisheries Science - This study assessed the effects of diets supplemented with different types of chitin hydrolysate on larval growth of the Japanese eel Anguilla japonica. Larvae were reared for...     

Nuclear proliferation in syncytia during avian reovirus replication.

Cultured chick embryonic fibroblasts formed syncytia after infection with avian reovirus (ARV) strain 58-132. Mitotic figures were occasionally observed within the syncytia. In addition, many nuclei in the syncytia incorporated 5-bromo-2'-deoxyuridine (BrdU), a DNA replication marker, indicating that they were in the S-phase of the cell cycle. These observations suggested that the nuclei within ARV-induced syncytia originated from nuclear endomitosis without cell division, as well as from cell fusion.     

Population structure of the Japanese eel Anguilla japonica as examined by mitochondrial DNA sequencing

SUMMARY: To examine the population structure of the Japanese eel Anguilla japonica , mitochondrial DNA sequence analysis was made for various samples of glass eels that might reflect genetic characteristics of spawning aggregates. The mitochondrial DNA from a total of 51 glass eels collected at Tanegashima Island, Kanagawa and Ibaraki in different periods within an inshore migrating season was sequenced for a 615 base-pair fragment from the tRNA^Thr gene to the central part of the control region. The DNA region was so variable that no individual was found to possess the same sequence, although average sequence differences within samples (1.07–1.63) were not large. Average sequence differences between samples (1.22–1.57) were comparable to those within samples, suggesting no genetic heterogeneity among samples. Tree analysis of the sequences showed neither a geographical nor temporal structure of population. Furthermore, although all DNA sequences from the present study were different from one another, two sequences were found to be the same with those reported from individuals collected in different localities in different years. Altogether, the present mitochondrial DNA sequence analysis of glass eels did not provide any evidence for genetic subdivision of the Japanese eel population.     

First capture of post-spawning female of the Japanese eel Anguilla japonica at the southern West Mariana Ridge

Two adult male freshwater eels, Anguilla japonica, were captured in June 2008 in the West Mariana Ridge (13°N, 142°E) in the North Pacific, but collections of females have yet to be reported. In September 2008, we successfully caught two adult female A. japonica, 55.5 and 66.2 cm in total length, in the adjacent but northern area (14°N, 143°E). Six newly hatched eel larvae (pre-leptocephali) were also collected by subsequent plankton sampling conducted near the female catch area. Female adults appeared to be in the post-spawning state, probably a considerable time after spawning, since a small number of remarkably regressed oocytes (50–250 μm in diameter) were observed in the ovaries. Capture of post-spawning female eels and newly hatched larvae near the Suruga Seamount (14°N) together with the previous collection of mature males in the southern area (13°N) corroborates that the area along the West Mariana Ridge is the spawning area of this species, but suggests that the eel spawning may occur over a wider area than previously expected.     

Properties of soil humic substances in fractions obtained by sequential extraction with pyrophosphate solutions at different pHs

Abstract

Humic acids (HAs) obtained from four different soils by sequential extraction with pyrophosphate solutions at different pH values (i.e. at pH 3, 5, 7, 9, 11, and 13), were examined by ultraviolet and visible (UV-VIS) spectroscopy and elemental analysis. UV-VIS spectra from 230 to 700 nm were measured, and absorbance coefficients of 1% humic acid solutions at 600 nm (E ^1% ₆₀₀) and Δlog K were calculated. The shape of the spectra of humic acids depended on the soil types rather than on the pH values. The (E ^1% ₆₀₀) values were higher in the neutral region, and lower in the alkaline region, for each pH value they decreased in the following order: buried Andosol > Andosol > Histosol ≧ Cambisol. The Δlog K values for each pH value were higher in the following order: Histosol> Cambisol > buried Andosol≧Andosol. Although the linear correlation was found to be significant between the E ^1% ₆₀₀ and Δlog K values, the relation between these optical properties and pH values differed among the soil types. However, in the neutral region, the higher E ^1% ₆₀₀ values of humic acids from buried Andosol and Andosol and the lower Δlog K values of humic acids from Cambisol and Histosol suggest that the humification degree was higher in the neutral region. Data of elemental composition and atomic ratios were obtained for each humic acid. The H/C ratios in the four soils increased gradually with increasing pH values from 5 to 13, and those for each pH value were commonly higher in the following order: Cambisol> Histosol> Andosol> buried Andosol. The O/C and OIH ratios decreased with increasing pH values. The results of the H/C versus O/C diagram suggested that decarboxylated humic acids were extracted at the higher pH values. A highly significant correlation coefficient was obtained between the H/C and OIH ratios (r= ?0.891***). Results showing that the decrease of the pH values corresponded to the order of the humic acids in the correlation curve in the H/C versus O/H diagram suggest that the humic acids with a higher content of unsaturated bonds and a higher degree of oxidation were extracted at the lower pH values within the range from 5 to 13.     

New Cytotoxic and Antibacterial Compounds Isolated from the Sea Hare,Aplysia kurodai

The extract of the sea hare, Aplysia kurodai, showed cytotoxicity against HeLa cells and antibacterial activity against Staphylococcus aureus. Bioassay-guided purification afforded four active compounds, which were identified to be laurinterol, laurinterol acetate, debromolaurinterol, and debromolaurinterol acetate by spectroscopic analysis. Although the acetates were derived from laurinterol and debromolaurinterol before, this is the first isolation of the acetates from natural sources.     

Prokinetic effect of the 5-HT4R agonist mosapride on canine gastric motility

We assessed prokinetic action of gastroprokinetic agent, mosapride in dogs. Open-label cross-over study. Six healthy beagles were administered single oral mosapride at doses of 0.5, 0.75, 1, and 2 mg/kg 30 min prior to feeding, followed by 1-week interval. The motility index (MI) of gastric contraction was ultrasonographically evaluated by change rate of antral area and contraction number. Significant increases in MI were observed at doses of 0.75 mg/kg (mean ± SEM, 11.11 ± 0.19), 1 mg/kg (11.65 ± 0.34), and 2 mg/kg (12.04 ± 0.34), compared with that of the control (9.37 ± 0.51). Mosapride administration (2.0 mg/kg, BID) for 1 week had no adverse effects on blood tests or health of the animals. In conclusion, 0.75 to 2 mg/kg of mosapride produces gastric prokinetic actions without adverse effects.     

Genetic identification of <Emphasis Type="Italic">Conger myriaster</Emphasis> leptocephali in East China Sea

ABSTRACT:   A subsample of Conger leptocephali collected in the East China Sea (ECS) was genetically analyzed and most were found to be the larvae of Conger myriaster , the most commercially important marine eel species in East Asia. However, these leptocephali (22.3–74.0 mm total length [TL]) did not have a complete row of lateral pigmentation, like the leptocephali of this species are commonly known to have when they are collected over the continental shelf or in coastal waters as they recruit. These leptocephali were in the western edge of the Kuroshio Current and the mixing zone over the shelf in the northern part of the ECS, and two smaller leptocephali (22.3, 46.5 mm TL) were collected to the south of the Ryukyu Islands. This evidence of an ontogenetic change in the presence of lateral pigmentation of C. myriaster indicates that previous efforts to determine the spawning area and recruitment patterns based on only morphological examination of Conger leptocephali in the region must be reconsidered. New research efforts based on genetic identification methods are needed to understand the spawning ecology and recruitment of this important fishery species.     

Quantitative stand structure of woody components of homestead forests and its implications on silvicultural management: a case study in Sylhet Sadar, Bangladesh

This study determined existing quantitative stand structure and its implication on silvicultural management of homestead forestry. The results showed that fruit and timber species have importance values of 57% and 43%, respectively, in the study area, which is in contrast to the commonly held view of absolute domination of fruit species. The fruit species were only moderately dominant over timber species in relation to the quantitative stand structure of homestead forests. Two fruit species, Mangifera indica and Artocarpus heterophyllus, contribute about one third of the stand structure, while amongst the timber species Samanea saman and Albizia spp. are the most important species. A simulated evaluation of soil expectation value of homestead forest showed that the existing stand structure would not maximize the financial gain perpetually, in contrast, the quantitative stand structure could be effectively regulated to maximize grower benefit without compromising the existing biodiversity. Optimization of the quantitative stand structure of homestead forests could be achieved by changing the species composition, specifically by increasing the percentage of commercially valuable species like Michelia champaca, Tectona grandis, Artocarpus chapalasha, Gmelina arborea, Litchi chinensis, Citrus grandis, Psidium guajava, Lagerstroemia speciosa, Swietenia mahogany, etc., reducing the percentage of species like Mangifera indica, Artocarpus heterophyllus, Cocos nucifera, Samanea saman, Spondias pinnata, Phoenix sylvestris, etc., and eradicating species like Lannea coromandelica and Ficus benghalensis. It was estimated that the optimal relative density of fruit and timber species that would generate optimal financial benefit would be 40.4% and 59.6%, respectively.