Effects of phosphorus addition with and without ammonium, nitrate, or glucose on N2O and NO emissions from soil sampled under Acacia mangium plantation and incubated at 100 % of the water-filled pore space

An incubation experiment was conducted to examine the effects of phosphorus (P) addition with and without ammonium, nitrate, or glucose on N₂O and NO emissions from soil taken under Acacia mangium plantation and incubated at 100 % water-filled pore space (WFPS). Additions of NO ₃ ^? stimulated the N₂O and NO emissions while NH ₄ ⁺ did not, showing that denitrification was the main process of N₂O and NO production in the study condition. When NO ₃ ^? was added with P significantly (P?<?0.05) increased N₂O emissions regardless of the ratio of the added nitrogen and carbon, suggesting that P addition stimulated denitrification activity. The activation of denitrification by P addition is possibly attributed to two mechanisms: (1) the added-P stimulated denitrification by relieving P shortage for denitrifying bacteria and (2) the added-P stimulated activity of heterotrophic soil microflora with increased O₂ consumption promoting the development of anaerobic conditions with stimulation of denitrification.     

On the volcanic ash soil in Tokachi District,Hokkaido Island,Japan

In Japan, most of the paddy fields are laid out on alluvial plain while other land crop fields are developed on plateau. The greater part of the latter ccnsists of volcanic ash soils.     

Natural diet of grapsoid crab <Emphasis Type="Italic">Plagusia dentipes</Emphasis> de Haan (Decapoda: Brachyura: Plagusiidae) in Tateyama Bay,Japan

The natural diet of Plagusia dentipes de Haan was studied in Tateyama Bay, Japan, between June 2004 and May 2005. A total of 389 specimens were collected for analysis of stomach content during the period, with sizes ranging between 7.1 and 63.1 mm in carapace width. The major dietary item was rhodophycean algae (mostly articulated coralline algae), which was ingested by 91.8% of the crabs and accounted on average for 55.6% (points) of the volume of stomach contents. Chlorophycean algae (mostly Ulvaceae, 39.1% and 8.1 points) and crustaceans (mostly amphipods, 38% and 3 points) came next in feeding frequency and volume. Minor dietary items also included other algae such as Phaeophyceae and animals such as mollusks (bivalves, gastropods), annelids (polychaetes), other crustaceans (caprellids, isopods), and echinoids. Significant seasonal dietary differences were observed and, in general, the diet in spring contained more food items, particularly more animals, compared to other seasons. Feeding of Rhodophyceae was highest and lowest in winter and summer, respectively. The total volume of food consumed was also lowest in summer and likely reflected reduced availability of the main food item in this season. There were no differences in dietary items between male and female crabs. In conclusion. P. dentipes is a primarily herbivorous crab with incidental or opportunistic feeding on animal items, and it is suggested that seasonal shifts in consumption may be related to growth, molting, and reproductive activity.     

The relationship between cellular radiosensitivity and radiation-induced DNA damage measured by the comet assay

The relationship between deoxyribonucleic acid (DNA) damage and the cell death induced by gamma-irradiation was examined in three kinds of cells, Chinese hamster ovary fibroblast CHO-K1, human melanoma HMV-II and mouse leukemia L5178Y. Cell survival was determined by a clonogenic assay. The induction and rejoining of DNA strand breaks induced by radiation were measured by the alkaline and neutral comet assays. L5178Y cells were the most radiosensitive, while CHO-K1 cells and HMV-II cells were radioresistant. There was an inverse relationship between the survival fraction at 2 Gy (SF2) and the yield of initial DNA strand breaks per unit dose under the alkaline condition for the comet assay, and also a relationship between SF2 and the residual DNA strand breaks (for 4 hr after irradiation) under the neutral condition for the comet assay, the latter being generally considered to be relative to cellular radiosensitivity. In the present analysis, it was considered that the alkaline condition for the comet assay was optimal for evaluating the initial DNA strand breaks, while the neutral condition was optimal for evaluating the residual DNA strand breaks. Since the comet assay is simpler and more rapid than other methods for detecting radiation-induced DNA damage, this assay appears to be a useful predictive assay for evaluating cellular clonogenic radiosensitivity of tumor cells.     

Prediction of cellular radiosensitivity from DNA damage induced by gamma-rays and carbon ion irradiation in canine tumor cells

Diseases of companion animals are shifting from infectious diseases to neoplasms (cancer), and since radiation therapy is one of the effective choices available for cancer treatment, the application of radiotherapy in veterinary medicine is likely to increase. However tumor tissues have different radiosensitivities, and therefore it is important to determine the intrinsic radiosensitivity of tumors in individual patients in advance of radiotherapy. We have studied the relationship between the surviving cell fraction measured by a clonogenic assay and DNA double strand breaks detected by a comet assay under neutral conditions in three canine tumor cell lines, after gamma-ray and carbon ion irradiation. In all the cell lines, cell death assessed by the clonogenic assay was much higher following irradiation with carbon ions than with gamma-rays. The initial and residual (4 hr) DNA damage due to gamma-ray and carbon ion irradiation were higher in a radiosensitive cell line than in a radioresistant cell line. The surviving cell fraction at 2 Gy (SF2) showed a tendency for correlation with both the initial and residual DNA damage. In particular, the residual damage per Gy was significantly correlated with SF2, regardless of the type of radiation. This indicates that cellular radiosensitivity can be predicted by detection of radiation-induced residual DNA damage.     

Ethylene-enhanced chlorophyllase activity during degreening of Citrus unshiu Marc.

Ethylene induces the degreening of the peel of Citrus unshiu Marc. and simultaneously the increase of chlorophyllase activity, indicating that ethylene accelerates the chlorophyll destruction through the enhancement of chlorophyllase activity. Cycloheximide inhibited the ethylene-enhanced chlorophyll degradation and repressed the enhancement of the chlorophyllase activity, while chloramphenicol did not affect the chlorophyll degradation nor the chlorophyllase activity. Based on these results, the role of ethylene in the chlorophyllase activation and the chloroplast senescence is discussed.     

Arthrogryposis, hydranencephaly and cerebellar hypoplasia syndrome in neonatal calves resulting from intrauterine infection with Aino virus

To determine the teratogenic potential of Aino virus (AINOV) in cattle, pregnant cows and fetal cattle were infected with a fresh isolate of AINOV. Five pregnant cows were inoculated intravenously with the virus at 122 to 162 days of gestation and allowed to give birth. All of the cows developed neutralizing antibodies to the virus, indicating that the cows had been infected with the virus; however, no clinical abnormalities were seen in their six newborn calves, and no specific antibodies to the virus were detected in the precolostral serum of calves. Five fetuses with fetal ages ranging from 132 to 156 days were inoculated in utero with the virus. One weak newborn and four stillborn calves were delivered at gestation days 256 to 263, i.e., less than the standard gestation term; they had congenital abnormalities including arthrogryposis, hydranencephaly and cerebellar hypoplasia. Antibodies specific to AINOV were detected in their precolostral serum. These results demonstrate that AINOV is a potential etiological agent of congenital malformation of cattle.     

Development of a SYBR green real-time polymerase chain reaction assay for quantitative detection of Babesia gibsoni (Asian genotype) DNA.

A real-time fluorogenic polymerase chain reaction (PCR) assay based on SYBR green that allows for sensitive, reproducible, and accurate quantification of Babesia gibsoni (Asian genotype). DNA from peripheral blood of infected dogs was developed. Standard curves were created by plotting the input amount of a standard template, constructed with plasmid DNA containing 182 base pairs (bp) of the p18 gene, against threshold cycle numbers. The curves showed a wide dynamic range (1,000,000-fold input) and high correlation values (>0.99). The PCR amplification efficacy of the standard template was similar to that of intact genomic DNA obtained from peripheral blood with B. gibsoni infection. The detection limit of the assay was 9 parasites/microl of blood with B. gibsoni infection. The intra-assay and interassay coefficients of variation of the threshold cycles ranged from 0.70% to 1.89% and from 1.18% to 1.92%, respectively. This assay system was found to be reproducible and accurate for the quantification of parasite DNA in experimentally infected dogs and far more sensitive than traditional microscopic examination.