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31.
Katsuaki Fujinaga Anthony S Ilano Hirotaka Nomura Richard T Miranda Shigeru Nakao 《Fisheries Science》2006,72(5):995-1003
ABSTRACT: The state of imposex in Neptunea arthritica from seven sites along the coast of Hokkaido, Japan was examined in 2002 based on the criteria: (i) relative penis size index (RPSI); (ii) imposex frequency; (iii) stage frequency distribution of imposex in adult and immature whelks; and (iv) sex ratio. RPSI differed from site to site, although values from all sites were low (0.186–5.294). In particular, the RPSI values for four sites were very low (<1.0). In sites where immature whelks were also collected, the frequency of imposex was considerably lower in immature (7.7%–55.6%) than in adult whelks (50%–95.2%) except at one site. The imposex stage frequency distribution also differed among sites, and the trend in the adult whelks corresponded with their RPSI value. Female whelks showing severe imposex (Stage 3 and 3+) were restricted to large individuals. 相似文献
32.
Biotope roofs in Japan are usually intensive green roofs that primarily include native plants and food plants for invertebrates and a pond and stones to create a wide range of habitats. The study aimed to evaluate the survivability of planted species, and colonisation by plants and invertebrates on a biotope roof and to suggest an appropriate planting design and maintenance scheme to optimize biodiversity benefits. An intensive green roof (150 m2, substrate depth of 50 cm) was installed in 2002 on the ninth storey of a building at Chiba University, Japan. Twelve species of trees, 18 species of shrubs and 8 species of forbs (mainly native species) were planted and volcanic stones were used as mulch and to create habitats for invertebrates. No maintenance and no irrigation were applied for almost 8 years. A limited number of tree species, such as Myrica rubra and Cinnamomum camphora could grew well without maintenance and irrigation at a substrate depth of 50 cm. Overall, shrubs grew successfully and a high density planting seemed effective in increasing wind resistance. Most forbs disappeared, probably because of drought and competition with these colonising plants. Eleven plant species spontaneously colonised resulting in domination by Solidago altissima and Miscanthus sinensis. These two species were too aggressive, and selective weeding is required for species richness. In an invertebrate study, 46 species in 11 orders were observed and the highest number of invertebrate species was observed in the pond and shady areas. 相似文献
33.
34.
Patterns of stable carbon and nitrogen isotopes in the baleen of common minke whale Balaenoptera acutorostrata from the western North Pacific 总被引:3,自引:0,他引:3
ABSTRACT: Stable carbon and nitrogen isotope ratios were determined in the baleen plates of 17 common minke whales Balaenoptera acutorostrata from the north-western Pacific Ocean off Japan, as well as prey species (krill Euphausia pacifica , Japanese anchovy Engraulis japonicus and Pacific saury Cololabis saira ) collected in the stomach contents, to investigate the trophic relationship between the minke whales and their prey. A few δ15 N-depleted peaks occurred along the length of baleen plates for 10 males irrespective of stomach content (anchovies and sauries). Similar δ15 N-depleted peaks were also found for one female and two immature individuals. It was likely that these δ15 N-depleted peaks formed in early summer. The stable nitrogen isotope ratio (δ15 N) values in Pacific saury (9.3 ± 1.4‰) did not differ significantly from that in Japanese anchovy (8.8 ± 0.9‰). In contrast, δ15 N in krill (7.2 ± 0.5‰ in July and 8.0 ± 0.2‰ in September) were significantly lower than in the Pacific saury. Thus, these peaks may reflect the dietary change from krill to fishes in the feeding migration of the whales. Growth rate of the baleen plate was estimated to be 129 mm/y, and it appeared that a dietary record of about 1.4 years remained in the baleen plate. For two immature whales, the maximum value of δ15 N occurred at the tip of baleen. This δ15 N enrichment may possibly be useful for discriminating weanlings and older whales. 相似文献
35.
Effectivness of the hybrid-weakness caused by a complementary interaction of two dominant genes Hwc1 and Hwc2 to suppress the spread of the red-grain gene into ordinary white-grained rice cultivars was investigated using the Monte Carlo computer simulation method. It was shown that the weakness genes, as far as being capable of reducing the fitness of the carrier by 80 percent or more, work quite effectively to suppress the genetic contamination of white-grained cultivars due to inflow of pollen from red-grained cultivars due to inflow of pollen from red-grain gene once the gene has been incorporated in to the population in the form of red-grained progeny produced as a result of the imperfect lethality of the initial hybrid between red-and white-grained cultivars. The weakness genes have little or no effect cultivars. The weakness genes have little or no effect either, when the contamination is initiated by an inflow of seeds or seedlings from ed-grained cultivars in these situations, removal (selection)of red grained plants Is the only countermeasure to exterminate the red-grain gene. The removal of red grained plants need not be intensive if carried out continuously. The spread of the red-grain gene after initial contamination is suppressed if the red-grain gene and weakness genes are linked. The suppressing effect of the linkage, however, is not substantial when the outcrossing rate is around or smaller than 0.01 as can be assumed in most rice cultivars. 相似文献
36.
Yoko L. Dupont Dennis M. Hansen Alfredo Valido Jens M. Olesen 《Biological conservation》2004,118(3):301-311
The aim of this study was to investigate effects of introduced honey bees (Apis mellifera) on native pollination interactions of Echium wildpretii ssp. wildpretii in the sub-alpine desert of Tenerife. We selected two study populations, one dominated by honey bees, while the other was visited by many native insects. During peak activity period of insects, nectar was nearly completely depleted in flowers of the first, but not the latter population. Thus, a high abundance of honey bees may have suppressed visitation by native animals due to exploitative competition. Honey bees stayed longer and visited more flowers on the same inflorescence than native bees, thus potentially promoting self-pollination of the plants. Level of seed set and viability was similar in the two study populations. However, we cannot rule out long-term changes in genetic population structure due to changes in gene-flow patterns caused by foraging behaviour of honey bees vs. native flower-visitors. 相似文献
37.
38.
Improvement of the bitter taste of amino acids through the transpeptidation reaction of bacterial gamma-glutamyltranspeptidase. 总被引:1,自引:0,他引:1
Hideyuki Suzuki Yoko Kajimoto Hidehiko Kumagai 《Journal of agricultural and food chemistry》2002,50(2):313-318
The tastes of several bitter amino acids and their gamma-glutamyl derivatives were compared. The bitterness of Phe, Val, Leu, and His was reduced, sourness was produced, and preferences were increased by gamma-glutamylization. Because the effect of gamma-glutamylization of bitter amino acids was most obvious for Phe, which is an atypical bitter amino acid, an enzymatic method for the synthesis of gamma-glutamylphenylalanine (gamma-Glu-Phe) involving bacterial gamma-glutamyltranspeptidase was developed. The optimum reaction conditions were 200 mM Gln, 200 mM Phe, and 0.5 unit/mL GGT, pH 10.4. After 1.5-h of incubation at 37 degrees C, 140 mM gamma-Glu-Phe was obtained, the yield being 70%. gamma-Glu-Phe was purified on a Dowex 1x8 column and then identified by NMR. 相似文献
39.
R. Shishido M. Kikuchi K. Nomura H. Ikehashi 《Genetic Resources and Crop Evolution》2006,53(1):179-186
As a part of an in situ survey of wild rice (Oryza rufipogon Griff.) in Myanmar (Burma), 16 strains of wild rice were collected, and analyzed for allelic diversity over 74 loci with
simple sequence repeat (SSR) markers to obtain a basic information for their conservation. Three each of indica and japonica cultivars were added for a comparison. In the six cultivars and 16 strains of wild rice, three to 15 alleles were detected
per locus with an average of 7.9. The wild rice revealed a large number of unique alleles throughout their chromosomes with
much wider ranges of variation than those detected in the six cultivars of O. sativa L.. The alleles found in the wild rice were classified into those specific to wild rice, common to wild rice and cultivars,
and those similar to indica or japonica cultivars. According to the classification, the genotype of each of the 16 strains of wild rice was schematically depicted.
The genetic variation among individual strains within a collection site was larger than the variation among the collection
sites. 相似文献
40.
Yanagita T Wang YM Nagao K Ujino Y Inoue N 《Journal of agricultural and food chemistry》2005,53(24):9629-9633
We investigated the effect of dietary combination of conjugated linoleic acid (CLA) and docosahexaenoic acid (DHA) to attenuate CLA-induced fatty liver in C57BL/6N mice. Mice were fed semisynthetic diets that contained either 6% high linoleic safflower oil (HL-SAF), 4% HL-SAF + 2% CLA, or 3.5% HL-SAF + 2% CLA + 0.5% DHA for 4 weeks. This 4 week feeding of CLA showed hepatic lipid accumulation concomitant with the decrease in adipose tissue weight in mice. However, 0.5% supplementation of DHA to the CLA diet could alleviate fatty liver without decreasing the antiobesity effect of CLA. The CLA diet promoted fatty acid synthesis in the liver, but DHA supplementation significantly attenuated the increase in enzyme activity induced by CLA. On the other hand, serum adipocytokines, leptin and adiponectin, were drastically decreased by CLA feeding, and DHA supplementation did not affect those levels. These results show that DHA supplementation to the CLA diet can attenuate CLA-induced fatty liver through the reduction of hepatic fatty acid synthesis without affecting adipocytokine production in C57BL/6N mice. 相似文献