纳米水雾环境对新鲜农产品采后贮藏过程中失重的调控

质量损失与冷害症状在新鲜农产品冷藏过程中经常发生,并会导致园艺产业巨大的经济损失。本试验分别研究了三种园艺产品,茄子(Solanum melongena)、日本芜青(Brassica rapa)和无花果(Ficus carica)在用两种类型加湿器制造的相对湿度为95%、温度分别为5.5℃和7℃的环境下贮藏10、6和8 d的贮藏品质。由纳米加湿器生成的水雾粒子平均直径小于100 nm,而由超声波加湿器生成的水雾粒子平均直径为216 nm。结果表明,纳米加湿器处理的日本芜菁、茄子和无花果样品的失重率分别为3.7%、5.3%和8.8%,超声波加湿器处理三种样品的失重率分别为7.3%、8.5%和14.7%。在纳米水雾贮藏室内放置的茄子果实的冷害指数要低于在超声波加湿环境中贮藏的果实。纳米水雾中的日本芜菁和无花果的气孔相比其初始状态下分别关闭了34.7μm2和51.5μm2,而在超声波水雾中则分别关闭了15.8μm2和25.5μm2。在纳米水雾中贮藏的日本芜菁的颜色要比在超声波水雾中贮藏的芫菁更绿。     

Endocarditis in chickens caused by subclinical infection of Streptococcus gallolyticus subsp. gallolyticus

Streptococcus gallolyticus subsp. gallolyticus causes endocarditis in humans and acute septicemia in domestic birds. We describe here the infective endocarditis caused by the bacterium found among clinically healthy broilers at two abattoirs in Japan. The chickens were thought to be healthy because of the lack of clinical symptoms and normal levels of mortality before slaughtering. At the time of inspection, some chickens were condemned because of organ disorders characterized by vegetative valvular endocarditis as well as focal necrosis in heart, liver, and spleen. Streptococcus gallolyticus subsp. gallolyticus was isolated from the organs as a pure culture, indicating that the bacterium probably was the causative agent of the disorders. Amplified fragment length polymorphism analysis of the isolates collected at the abattoirs from chickens grown in nine different farms indicated that the isolates were different variants of the same clonal lineage and may have been derived from the same ancestor. These results suggest that S. gallolyticus subsp. gallolyticus causes infectious endocarditis in chickens and that healthy chickens may possess the bacterium in their normal flora as an opportunistic pathogen.     

Serotypes and virulence factors of Escherichia coli strains isolated from dogs and cats

E. coli strains isolated from urine of dogs and cats with urinary tract infections (UTI) and from feces of healthy one's were serotyped, and the serotypes were correlated with uropathogenic virulence factors. The most prevalent O-serotypes, O4 and O6, were isolated from dogs and cats with UTI. In contrast, O11 and O102 strains were the most frequently found from feces of healthy dogs and cats. Most of type O4 and O6 strains possessed such virulence factors as pil, pap, sfa, hly, and cnf1, while most type O11 and O102 strains pil only or pil and aer. All strains of type O75 possessed afaI and aer. K1 antigen was negative in all strains obtained from UTI.     

The zooplankton biomass in the Sea of Japan

We examined seasonal, annual variation and horizontal distribution of zooplankton in the Sea of Japan from 1966 to 1990. Zooplankton was most abundant in the spring. The spring maximum appeared in February–March and in April–May in the southern and eastern parts of the study areas, respectively. In the summer and autumn, a secondary peak was most conspicuous in the eastern part. The difference between the estimated biomass at night and day was large in the spring and small in summer and autumn. The biomass in the offshore southern area peaked about every 3 years between 1966 and 1983, and increased abruptly in 1990. The density in the area north of 39°N or 40°N was high. Total biomass estimated in the upper 150 m layer in the Sea of Japan (10⁶ km²) was 9.5 × 10⁶ t in the daytime and 16.6 × 10⁶ t at night.     

Collembolan community dynamics during deciduous forests regeneration in Japan

The structure and feeding group composition of collembolan communities were studied in secondary deciduous forests of different ages to investigate the collembolan community response to environmental changes associated with forest cycles. The study was carried out at eight sites forming a chronosequence (1, 4, 12, 24, 51, 54, 71 and 128 years after clear cutting) of deciduous forest stands in northern Ibaraki (Japan). Total collembolan density and species richness was low at the 1-year-old site, and there was little difference in density among sites over 4 years of age. The density of sucking feeders was especially low at the 1-year-old site. Species richness of trees of a diameter at breast height (DBH)<5 cm positively correlated with the density of fungal feeders. Species richness of total Collembolans and of sucking feeders correlated positively with the water content of the organic layer. Ordination of the collembolan community with Canonical Correspondence Analysis suggested that species richness of larger trees (DBH 5 cm) contributed to the differences in species composition of fungal feeders and sucking feeders. We conclude that total abundance and species richness of collembolans recovered within 4 years after clear-cutting, but species composition of fungal feeders and sucking feeders took longer to recover.     

Progression of the dose-related effects of estrogenic endocrine disruptors, an important factor in declining fertility, differs between the hypothalamo-pituitary axis and reproductive organs of male mice

For the purpose of investigation of working mechanisms in endocrine disruptors, we evaluated the dose-related effects of fetal and/or neonatal exposure to an estrogenic compound on the male reproductive organs in adult mice, particularly with respect to gene expression of steroidogenic acute regulatory protein (StAR). The pregnant ICR mice were given subcutaneous injections of 10 micro g/day/animal of diethylstilbestrol (DES) to subject the fetal mice to in utero exposure (IUE). Subsequently, the newborn male mice were subjected to neonatal exposure (NE) by treatment with vehicle or 0.1-10 micro g/day/animal of DES. Fertility rates of each group were as follows: control, 100%; IUE only, 60%; IUE+NE 0.1 micro g, 25%; IUE+NE 1 micro g, 0%; IUE+NE 10 micro g, 0%. In general histology, germ cell layers in the seminiferous tubules were thinned in the group of IUE+NE 10 micro g. Hypoplasia of the Leydig cells, in which the staining intensity of eosin was diminished, was also observed in the groups of IUE+NE 0.1-10 micro g. The androgen receptor (AR) and estrogen receptor alpha (ERalpha) immunoexpression in the Leydig cells of IUE+NE 1-10 micro g was slightly lower than that in the controls. Long-term dysfunction of the hypothalamo-pituitary-testicular axis, including sustained hypoproduction of gonadotropin and testosterone, and altered expressions of steroid hormone receptors and StAR genes were observed. The hypothalamo-pituitary control of gonadotropin secretion may be affected by the smaller doses of estrogenic agents than the reproductive organs. Furthermore, the fertility rate in the male mice exposed to this estrogenic agent was closely correlated with the testosterone levels, and even more so with the rate-limiting factor of steroidogenesis, StAR. This finding suggests that endocrine disruptors have an important pronounced effect on StAR gene expression.     

SEM observations on larval shell morphology of Manila clam Ruditapes philippinarum and their utility

Manila clam Ruditapes philippinarum is common and abundant on Japanese tidal flats, forming a commercially important clam fishery. However, annual catches of Manila clam have decreased drastically since 1975?C1985. To study larval recruitment processes of Manila clam, we carried out scanning electron microscopy (SEM) observations on larval and juvenile shells of clams reared at 20 and 24?°C. There was no significant difference in final shell length of trochophores between 20 and 24?°C. However, the larval duration was much longer and the shell length of settled size of pediveligers was much larger for clams reared at 20?°C than those reared at 24?°C. These findings suggest that larval duration and growth, as well as settlement size, may vary markedly depending on temperature (and probably on season). The larval shell morphology of Manila clam can provide essential information about larval recruitment processes.     

Assessing decline in physical structure of deciduous hardwood forest stands under sika deer grazing using shrub-layer vegetation cover

For 345 stands of deciduous hardwood forest in Hyogo Prefecture, Western Japan, we assessed the decline of shrub-layer vegetation due to sika deer in each stand by using the shrub-layer decline rank (SDR), determined by combining the shrub-layer vegetation cover and the presence of signs of grazing by sika deer in a stand. Since there was a geographical correlation between SDR and sighting per unit effort (SPUE), which is an index of the relative density of sika deer, it appeared that decline of shrub-layer vegetation in a stand can be accurately evaluated by SDR. There were correlations between SDR and several variables that indicate the status of components in forests (presence of saplings of tall trees, occurrence of bark stripping of tall trees, proportion of bark-stripped stems of Clethra barvinervis, decline of subtree-layer vegetation by bark stripping, cover of litter on the ground, and area of soil surface erosion). These results indicate that the status of these components changes with decline of shrub-layer vegetation by sika deer grazing. It is thought that such synchronizations are caused by sika deer grazing or a direct or indirect effect by decline of shrub-layer vegetation due to sika deer. Therefore, it is reasonable to assess decline in physical structure due to sika deer for stands of deciduous hardwood forests according to SDR.     

Invasions of rainbow trout and brown trout in Japan: A comparison of invasiveness and impact on native species

Many species of salmonids have been stocked into waters outside of their native range. The invasiveness and impact of these species on native species varies depending on their biological traits, and on environmental conditions, such as climate. In Japan, rainbow trout and brown trout, both listed in 100 of the world's worst invasive alien species by the International Union for Conservation of Nature, occur as non-native species. The invasiveness of these two species is thought to be related to seasonal flooding, given flood waters can physically damage fry and prevent population establishment. Rainbow trout have successfully invaded waters in Hokkaido, northern Japan, where the likelihood of flooding is low between June and July, when their fry emerge, but successful invasions are rare in regions south of Hokkaido. Brown trout, however, have successfully invaded waters not only in Hokkaido, but also other regions. Since brown trout have a similar life history to the native white-spotted charr and masu salmon, with fry emerging before the flood season, they are more suited to the Japanese climate than Rainbow trout. Rainbow and brown trout interact with native species in various ways, but a common outcome of these interactions is the displacement of native charr species. Legal regulations of non-native salmonids should be based on understandings of the ecological traits of each invasive species and regional impacts on native species. Given the ongoing nature of climate change, the nature and extent of the effects of rainbow and brown trout on native species might also change.