Dietary arginine requirement of juvenile kuruma shrimp Marsupenaeus japonicus (Bate)

The requirements for essential amino acids by kuruma shrimp, Marsupenaeus japonicus (Bate) have not yet been determined using the dose–response method due to poor utilization of crystalline amino acids (CAA). In a previous study, we produced coated CAA that could be used to retard leaching losses. Therefore, to determine the arginine requirement of juvenile kuruma shrimp, a growth study was conducted using test diets containing six levels of coated arginine (from 1.20% to 3.19% of diet) for 42 days. Crystalline amino acids was supplemented to correspond to the amino acid pattern in the whole body protein of the kuruma shrimp except for arginine. To reduce leaching losses, CAA were coated with carboxymethylcellulose (CMC) and diets were further bound with CMC and k‐carrageenan. Test diets were fed to triplicate groups of juveniles (0.25±0.02 g) twice a day. Proximate composition and the amino acid composition of shrimp whole bodies were analysed at the end of the feeding trial. Percent body weight gain (WG), specific growth rate, feed intake, feed efficiency ratio and protein retention efficiency were significantly affected by the dietary arginine concentrations. Estimating the arginine requirement of kuruma shrimp using broken‐line analysis of percent WG resulted in a value of 2.66% of diet or 5.32% of protein. After correcting for leaching of arginine from the diets, the optimum dietary value of arginine for kuruma shrimp was a little lower than the estimated value.     

Sequence homogeneity of the ψserA-trmU-tufB-secE-nusG-rplKAJL-rpoB gene cluster and the flanking regions of ‘Candidatus Liberibacter asiaticus’ isolates around Okinawa Main Island in Japan

In Japan and Southeast Asia, ‘Candidatus Liberibacter asiaticus’ (Las) is the dominant causal agent of citrus greening (huanglongbing) disease. Using PCR techniques, we determined the 11168-nucleotide sequence of the ψserA-trmU-tufB-secE-nusG-rplKAJL-rpoB gene cluster and the flanking regions for 51 Japanese, four Taiwanese, four Indonesian, and three Vietnamese isolates of Las. The sequence is identical in 62 isolates collected from Japan, Taiwan, Indonesia, and Vietnam, except for nucleotide substitutions at 11 positions. Some Las isolates from Sakishima Islands near Taiwan had unique nucleotide mutations, but all Las isolates around Okinawa Main Island were homologous. On the basis of the pattern of single nucleotide polymorphisms (SNPs) of the 11 nucleotide substitutions, the 62 Las isolates from Japan, Taiwan, Indonesia, and Vietnam could be divided into 12 pattern groups, and the 51 Japanese isolates consisted of six patterns. The results suggested that one unique genetic group is dominant around Okinawa Main Island, whereas several different are commonly distributed around islands near Taiwan.     

土槿皮乙酸B增加活性氧水平诱导人乳腺癌MCF-7细胞凋亡和衰老的研究

本研究旨在研究土槿皮乙酸B(PAB)诱导人乳腺癌MCF-7细胞凋亡和衰老与活性氧的关系。在相差显微镜下观察4 μmol/L PAB在36 h诱导细胞凋亡小体的出现;LDH方法显示PAB时间依赖性的增加凋亡比率;SA-β-半乳糖苷酶显示4 μmol/L PAB作用3 d后,去药再作用5 d,96%的细胞蓝染,细胞变大且扁平;流式细胞仪检测用DCFH-DA染色后4 μmol/L PAB 时间依赖性增加细胞内活性氧水平。所以4 μmol/L PAB通过增加细胞内活性氧水平促进细胞凋亡和衰老。     

Effects of Susceptibility of Test Plants on Modes of Cucumovirus Transmission by Myzus persicae

In sequential transmission tests of Peanut stunt virus S (PSV-S) and Cucumber mosaic virus V (CMV-V) using Myzus persicae, these viruses behave as a semipersistent virus in Phaseolus vulgaris, but as a nonpersistent virus in Nicotiana tabacum, regardless of the species of plant used as the virus source. In addition, viruliferous aphids retained virus infectivity and transmitted it to P. vulgaris, even after they lost infectivity to N. tabacum. Apparently, the mode of transmission by the aphids differs depending on the plant species used for the assay. After mechanical inoculation with purified PSV-S or CMV-V, P. vulgaris appeared more susceptible to PSV-S than N. tabacum. However, the susceptibility to CMV-V appeared similar in both assay plants. Received 22 May 2000/ Accepted in revised form 14 September 2000     

Conversion of chromosome-specific RAPDs into SCAR-based anchor markers for onion linkage maps and its application to genetic analyses in other Allium species

Integration of previously developed Allium cepa linkage maps requires the availability of anchor markers for each of the eight chromosomes of shallot (A. cepa L. common group Aggregatum). To this end, eight RAPD markers originating from our previous research were converted into SCAR markers via cloning and sequencing of RAPD amplicons and designing of 24-mer oligonucleotide primers. Of the eight pairs of SCAR primers, seven resulted in the amplification of single bands of the original RAPDs, and the remaining primer set amplified an additional band. The results of Southern hybridization using RAPD amplicons from genomic DNA of Japanese bunching onion (Allium fistulosum L.)—shallot monosomic addition lines indicated that five SCAR markers were single shallot chromosome-specific markers and were not detected in genomic DNA of A. fistulosum. The eight SCAR primer pairs were applied to other Allium species and exhibited three types of amplification profiles, namely RAPD amplicons observed only in shallot, in shallot and Allium vavilovii, and in several Allium species. A mapping study using 65 F₂ plants generated by the selfing of one interspecific cross A. cepa × Allium roylei individual integrated the SCAR marker SAOE17₅₀₀ into chromosome 5 as expected. The results of the present study show that the eight SCAR primer sets specific to shallot can facilitate the mapping in A. cepa and can also serve as anchor points between maps of different Allium species.     

Trace Elements in Paddy Soils from the Central Region of the Mekong River,Laos

Extract

Laos (14–22.5°N and 100–107.5°E) is a land-locked country located in the Indo-China Peninsula, adjacent to Vietnam, Cambodia, Thailand, Myanmar, and China. The total area of the country is 236,800 km² and about 70% of the land is occupied by mountains. Paddy fields are distributed in flood plains along the Mekong River and its tributaries and in valley bottom plains dissected by small rivers. The climate is dominated by tropical monsoon.     

Background levels of trace and ultra-trace elements in soils of Japan

Five hundred and fourteen soil samples collected from 78 sites in Japan were analyzed for their contents of trace and ultra-trace elements. We estimated the background levels (natural abundance) of 57 elements in soils. The concentration ranges were so wide that the ratios of the highest values to the lowest values were more than 100 for all the elements, with the exception of Be, Ga, Mo, Ag, In, Sn, and Ba. While the concentrations of the first transition elements (₂₁Sc to ₃₀Zn in atomic numbers) were higher than the concentration of the other elements, those of lighter (₃Li and ₄Be) and heavier elements tended to decrease, with an increase or decrease of atomic numbers, with the apparent exception of Pb, Th, and U. Concentrations of elements with even atomic numbers were, in most of the cases, higher than the concentrations of both adjacent elements with odd atomic numbers. Frequency distribution of most of the elements was strongly positively skewed. Markedly positive correlation coefficients (r>0.9) were observed among the elements within the same group in the Periodic Table in many combinations. The dendrogram obtained by cluster analysis showed that the occurrence and distribution of the elements in soils were mostly controlled by the chemical properties of each element, rather than by the nature and properties of individual soil samples. The total contents of the elements in soils were strongly dependent on the chemical composition of the parent rocks from which respective soils were derived.     

Soil microbial biomass and fluorescein diacetate hydrolytic activity in Japanese acidic tea field soils

The soil microbial biomass (SME) content and fluorescein diacetate (FDA) hydrolytic activity in 21 acidic tea field soils in Japan were determined. SM 3 content in the tea field soils was quantitatively similar to that in 13 arable soils with neutral soil pH previously reported. However, the ratio of the SMB content to organic matter content in the tea field soils classified as red-yellow soil, brown forest soil, and lithosol was clearly lower than that in the neutral arable soils classified as non-volcanic ash soil. FDA hydrolytic activity in the tea field soils was higher than the activity in various soils with neutral soil pH and showed a negative relationship with the soil pH.     

Diluted isoflurane as a suitable alternative for diethyl ether for rat anaesthesia in regular toxicology studies

Despite its explosive properties and toxicity to both animals and humans, diethyl ether is an agent long used in Japan in the anaesthesia jar method of rat anaesthetises. However, in response to a recent report from the Science Council of Japan condemning diethyl ether as acceptable practice, we searched for an alternative rat anaesthesia method that provided data continuous with pre-existing regular toxicology studies already conducted under diethyl ether anaesthesia. For this, we examined two candidates; 30% isoflurane diluted with propylene glycol and pentobarbitone. Whereas isoflurane is considered to be one of the representatives of modern volatile anaesthetics, the method of propylene glycol-diluted 30% isoflurane used in this study was our modification of a recently reported method revealed to have several advantages as an inhalation anaesthesia. Intraperitoneal pentobarbitone has long been accepted as a humane method in laboratory animal anaesthesiology. These 2 modalities were scrutinized in terms of consistency of haematology and blood chemistry with previous results using ether. We found that pentobarbitone required a much longer induction time than diethyl ether, which is suspected to be the cause of fluctuations in several haematological and blood chemical results. Conversely, only calcium ion concentration showed a slight difference from traditional results in the case of 30% isoflurane. Additionally, serum prolactin and corticosterone levels indicated that 30% isoflurane induced less stress than ether, confirming that 30% isoflurane can both provide results consistent with diethyl ether, while at the same time remove its disadvantages. As such 30% isoflurane appears to be a strong alternative anaesthetic agent for future regular toxicology studies in Japan.