Interannual variation in quantitative relationships among egg production and densities of larvae and juveniles of the Japanese mantis shrimp <Emphasis Type="Italic">Oratosquilla oratoria</Emphasis> in Tokyo Bay,Japan

To explore which lifestages affect the stock size of young-of-the-year mantis shrimp Oratosquilla oratoria in Tokyo Bay, Japan, we investigated interannual variations in the quantitative relationships among egg production, larval density, and juvenile density. We collected adult females, larvae, and juveniles during monthly field surveys from 2004 to 2007. The interannual trend for the juvenile density index differed from those for egg production and larval density; although indices of both egg production and larval density were high in 2004 and 2007, the juvenile density index was high only in 2007, suggesting high mortality during the pelagic larval stage or the early phase of the postsettlement juvenile stage in 2004. We found that larval settlement started at the end of August and peaked in October, although larvae from the early spawning season (May–June) should have settled in August or earlier. Juveniles were found throughout the bay except in areas where bottom hypoxia occurred, suggesting that hypoxia restricts the spatial distribution of juveniles. Our results suggest that mortality during the early life history fluctuates among years, probably because of changes in environmental conditions in the bay, resulting in interannual variation in the stock size of young-of-the-year juvenile O. oratoria.     

Foraging dispersion of Ryukyu flying-foxes and relationships with fig abundance in East-Asian subtropical island forests

Background

Figs are widely distributed key resources to many tropical-subtropical animals, and flying-foxes are major consumers and seed dispersers of figs. Bat-fig interrelationships, however, may vary among species differing in fruiting traits, i.e., bat- versus bird-dispersed figs. We examined Ryukyu flying-fox foraging dispersion and the relationships with tree species composition and fig abundance in forests of Iriomote Island.

Results

Bat foraging dispersion showed no spatial patterns with respect to different areas of the island, and was not explained by heterogeneity, density, or basal area (BA) of total trees, nor by relative density or BA of fruiting trees or total fruiting figs among sites. Instead, bat densities were positively dependent on the relative density of total figs, and particularly the relative BA of bat-dispersed figs Ficus septica and F. variegata. Both species were dominant figs in forests, fruiting asynchronously with long crop seasons, and were used as predominant foods. Bats foraged mostly solitarily and the mean density was in a hump-shaped relationship with crop sizes of the dominant bat-figs. These two species and Ficus benguetensis are larger-sized bat-figs, all contained more seeds, higher dry-pulp mass and water mass, but not necessarily water content. By approximate estimation, higher proportions of seeds of these bat-figs would have been removed from fruits through the bat consumption, than that of small-sized bird-figs like F. virgata, F. superba, and F. microcarpa.

Conclusions

The foraging dispersion of Ryukyu flying-foxes in forests depends on the availability of the most abundant bat-figs that serve as predominant foods. Intermediate levels of crop sizes of theses figs appear most fit with their solitary foraging. Our results suggest that as density and BA coverage of these dominant bat-figs are below a certain level, their effectiveness to attract bats may dwindle and so would their chance of dispersal by bats.

     

Morphologic characteristics of a transplantable tumor derived from a spontaneous malignant fibrous histiocytoma in the rat

Malignant fibrous histiocytoma (MFH) developed spontaneously in subcutaneous tissue of the head of a 15-month-old male Fischer 344 rat. The tumor was serially transplanted into syngeneic rats up to the 45th generation and was designated MFH-MT. Light and electron microscopic examinations revealed that the original and serially transplanted tumors were composed of an admixture of fibroblast-like and histiocyte-like cells arranged in a storiform pattern. Neoplastic cells gave positive reactions for acid phosphatase, alkaline phosphatase, nonspecific esterase, alpha-1 antitrypsin and lysozyme. The tumors transplanted into the lungs and cutaneous tissue of the tail had a mixed histologic appearance of storiform, pleomorphic, myxoid and giant cell types. Moreover sclerosing hemangioma-like and osteosarcoma-like structures were also found. MFH-MT grew well in athymic nude mice showing neoplastic proliferation of pleomorphic cells strongly positive for alpha-1 antitrypsin. Development of MFH-MT was significantly retarded by the two antitumor drugs tested. The retarded tumors consisted predominantly of fibroblast-like cells and abundant collagenic fibers, whereas histiocytic cells decreased in number.     

Influence of cholesterol administration and aging on the development of pulmonary foam cells in F344 rats

The influence of experimentally induced hyperlipidemia and aging on the development of pulmonary foam cells (PFCs) was examined in Fischer 344 rats. The male and female rats were administered orally with cholesterol at a dosage level of 1000 mg/kg/day for 30 days from 6 to 10 weeks or from 33 to 37 weeks of age. The control rats received the vehicle only in the same manner. Plasma levels of total cholesterol, phospholipid, triglyceride (TG), beta-lipoprotein (beta-LP) and calcium in both control and cholesterol-administered groups were higher at 37 weeks than at 10 weeks of age. Plasma beta-LP and TG levels in the treated groups were significantly higher or tended to be higher than those of the controls at 10 and 37 weeks of age. Males of the treated group showed the highest level of beta-LP at 37 weeks of age, positively correlated with the highest incidence of PFCs. PFCs developed singly or in a small cluster in peribronchial and subpleural regions. PFCs had an abundant cytoplasm filled with many fine vacuoles containing neutral lipid and cholesterol. PFCs stained with PAS and reacted immunohistochemically with both anti-rat monocytes/macrophages monoclonal antibody and anti-lysozyme antibody. Moderately swollen macrophages with a foamy appearance were detected in perivascular connective tissues of the lungs and they were considered to represent an initial stage of the development of PFCs. These observations suggest that hyperlipidemic conditions, particularly hyper beta-lipoproteinemia, resulting from cholesterol administration or aging may be involved in the development of PFCs in rats.     

The distributions of phytohemagglutinin-P and concanavalin A binding sites on equine, bovine and canine peripheral blood lymphocytes

The distributions of phytohemagglutinin-P (PHA) and concanavalin A (ConA) binding sites were investigated for equine, bovine and canine peripheral blood lymphocytes (PBL). Non-B lymphocytes were collected from each PBL using a fluorescence-activated cell sorter (FACS), and the numbers of PHA and ConA binding sites on their surfaces were counted. Most PHA binding sites on PBL of the three species were shown on the surfaces of non-B lymphocytes. On the other hand, the ConA binding sites on equine and canine PBL existed mainly on the surfaces of non-B lymphocytes, but B lymphocytes of these two species had many ConA binding sites. These results were confirmed by the results of two-parameter fluorescence analysis using FACS. It is, therefore, concluded that the different optimum concentrations of PHA and ConA in PBL blastogenic responses of each animal depended on the different distributions of their binding sites.     

The prevalent genotypes of bovine viral diarrhea virus in Japan, Germany and the United States of America

Genotypes and subgenotypes of bovine viral diarrhea virus (BVDV) field isolates from Japan, Germany and the United States of America (USA) were identified, and the prevalent pattern of BVDV in individual countries was estimated genetically. Subgenotypes were determined based on phylogenetic analyses of nucleotide sequences of a part of the E2-coding gene of BVDV. Forty-five, 61 and 56 BVDV strains were isolated from naturally infected cattle in Japan, Germany and USA, respectively, between 1980 and 2003. The most prevalent BVDV in these three countries was BVDV-1b. The second most prevalent BVDV strains were 1a, 1d and BVDV-2 in Japan, Germany and USA, respectively. The most prevalent subgenotype 1b in each country constructed individual small clusters in the subgenotype 1b branch in the phylogenetic tree. Although cattle and/or cattle products were moving among the three countries as part of international trade, the distribution of BVDV in the field in each country showed long-standing individual patterns.     

Importance of individual root traits to understand crop root system in agronomic and environmental contexts

Resource acquisition, one of the major functions of roots, can contribute to crop growth and mitigating environmental impacts. The spatio-temporal distribution of roots in the soil in relation to the dynamics of the soil resources is critical in resource acquisition. Root distribution is determined by root system development. The root system consists of many individual roots of different types and ages. Each individual root has specific development, resource acquisition, and transport traits, which change with root growth. The integration of individual root traits in the root system could exhibit crop performance in the various environments via root distribution in the soil. However, the relationship between individual root traits and the pattern of root distribution is complicated. To understand this complicated relationship, we need to evaluate enormous numbers of individual root traits and understand the relationship between individual root development and root distribution as well as the integrated functions of individual root traits along with dynamics of resources in the soil.