Swim bladder inflation as a possible cause of saddleback-like syndrome malformation in hatchery-reared red spotted grouper <Emphasis Type="Italic">Epinephelus akaara</Emphasis>

Saddleback-like syndrome is one of the most frequently observed malformations in hatchery-reared red spotted grouper Epinephelus akaara. Saddleback-like syndrome is characterized by a V-shaped dorsal-profile depression behind the head region accompanied by deformities or misalignments of the first to fourth neural spines on the vertebral column and the first to fourth pterygiophores of the dorsal fin. Abnormal swim bladder inflation in several finfish species leads to malformations, particularly of the vertebral column. The present study examined the influence of swim bladder inflation on saddleback-like syndrome in hatchery-reared red spotted grouper. The incidence of saddleback-like syndrome increased as swim bladder inflation rate increased. Additionally, the incidence of saddleback-like syndrome among juveniles with inflated swim bladders was significantly higher than that among juveniles with uninflated swim bladders. The larval swim bladder is located just below the first to fifth vertebrae and the first to fifth dorsal spines, where saddleback-like syndrome occurs. Our results suggest that an inflated swim bladder increases the risk of saddleback-like syndrome in hatchery-reared red spotted grouper.     

Methods for measuring N2O flux from water surface and N2O dissolved in water from agricultural land

A new chamber method and a stripping method were developed for field measurements of the rate of N₂O emission from the water surface and for determinations of dissolved N₂O in water from agricultural land.

These methods were used for the measurement of drainage canal water and flooded water of rice fields during the period of June 1982 to January 1983. The results demonstrate that aquatic systems of agricultural land may provide both source and sink for atmospheric N₂O.     

利用137Cs示踪农业耕作土壤侵蚀速率的定量模型

建立了一个根据农业耕作土壤剖面中^137Cs的损失量与土壤侵蚀量之间关系的定量模型,在假设^137Cs在耕层中得到充分的混合而变得均一的基础上,根据质量平衡模型推导而成,模型显示^137Cs的衰变常数,年沉降分量,耕层厚和采样年份对年平均土壤侵蚀速率都有重大影响,模型结果还说明,^137Cs的损失量与年平均土壤侵蚀量之间的关系既非线性关系亦非指数关系,而是一种复杂的曲线关系。     

Effects of acrosomal conditions of frozen-thawed spermatozoa on the results of artificial insemination in Japanese Black cattle

The purposes of this study were to examine the relationship between male artificial insemination (AI) fertility and sperm acrosomal conditions assessed by new and conventional staining techniques and to identify possible reproductive dysfunctions causing low conception rates in AI using frozen-thawed spermatozoa with poor acrosomal conditions in Japanese Black bulls. We investigated individual differences among bulls in the results concerning (1) acrosomal conditions of frozen-thawed spermatozoa as assessed by not merely peanut agglutinin-lectin staining (a conventional staining technique) but also immunostaining of acrosomal tyrosine-phosphorylated proteins (a new staining technique), (2) routine AI using frozen-thawed spermatozoa as assessed by pregnancy diagnosis, (3) in vivo fertilization of frozen-thawed spermatozoa and early development of fertilized eggs as assessed by superovulation/AI-embryo collection tests and (4) in vitro fertilization of frozen-thawed spermatozoa with oocytes. The percentages of frozen-thawed spermatozoa with normal acrosomal conditions assessed by the abovementioned staining techniques were significantly correlated with the conception rates of routine AI, rates of transferable embryos in superovulation/AI-embryo collection tests and in vitro fertilization rates. These results are consistent with new suggestions that the distribution of acrosomal tyrosine-phosphorylated proteins as well as the acrosomal morphology of frozen-thawed spermatozoa are AI fertility-associated markers that are valid for the prediction of AI results and that low conception rates in AI using frozen-thawed spermatozoa with poor acrosomal conditions result from reproductive dysfunctions in the processes between sperm insemination into females and early embryo development, probably failed fertilization of frozen-thawed spermatozoa with oocytes.     

Quality Characteristics of Waxy Hexaploid Wheat (Triticum aestivum L.): Properties of Starch Gelatinization and Retrogradation

The viscoelastic properties and molecular structure of the starch isolated from waxy (amylose-free) hexaploid wheat (WHW) (Triticum aestivum L.) were examined. WHW starch generally had lower gelatinization onset temperature, peak viscosity, and setback than the starch isolated from normal hexaploid wheat (NHW). Differential scanning calorimetry (DSC) showed that WHW starch had higher transition temperatures (T_o, T_p, and T_c) and enthalpy (ΔH) than NHW starch. However, when compared on the basis of amylopectin (AP) content, ΔH of WHW starch was almost statistically identical to that of its parental varieties. Typical A-type X-ray diffraction patterns were observed for the starches of WHW and its parental varieties. Somewhat higher crystallinity was indicated for WHW starch. WHW starch was also characterized by having greater retrogradation resistance. The high-performance size-exclusion chromatography (HPSEC) of amylopectin showed that each amylopectin yielded two fractions after debranching. Although WHW amylopectin had somewhat long B chains, little difference was observed in the ratio of Fr.III/ Fr.II between WHW and its parental varieties.     

Multiple high-throughput analyses monitor the response of E. coli to perturbations

Analysis of cellular components at multiple levels of biological information can provide valuable functional insights. We performed multiple high-throughput measurements to study the response of Escherichia coli cells to genetic and environmental perturbations. Analysis of metabolic enzyme gene disruptants revealed unexpectedly small changes in messenger RNA and proteins for most disruptants. Overall, metabolite levels were also stable, reflecting the rerouting of fluxes in the metabolic network. In contrast, E. coli actively regulated enzyme levels to maintain a stable metabolic state in response to changes in growth rate. E. coli thus seems to use complementary strategies that result in a metabolic network robust against perturbations.     

Improvement of larval rearing technique for mass seed production of snow crab <Emphasis Type="Italic">Chionoecetes opilio</Emphasis>

Larval rearing experiments were conducted to examine the potential for mass seed production of the snow crab Chionoecetes opilio using a total of eight 20-kL tanks. Tanks were equipped with agitators, which move the water using a rectangular blade to prevent the zoeas sinking to the bottom of the tank. Larval rearing water was treated with sodium nifurstyrenate once a week to reduce the chance of larval infection by pathogenic bacteria. Zo eas were fed with rotifers and Artemia nauplii. A total of 122 830 megalops and 16 660 first-stage crabs were produced. Thus, the potential for mass seed production of snow crab was determined. Survival rates up to the megalopal stage were high in tanks with a feeding regime that fed rotifers to larvae through an entire zoeal stage. This study also describes the fatty acid composition of snow crab larvae. It revealed that the first zoeas had a high DHA content and DHA/EPA ratio, but these values significantly decreased in the second stage zoeas and megalops. Improving the DHA content and/or DHA/EPA ratio of larvae should be important in studies on mass seed production technology of the snow crab.     

Linkage analysis of rice bacterial blight resistance gene xa20 in XM6, a mutant line from IR24

Bacterial blight caused by Xanthomonas oryzae pv. oryzae (Xoo) is an important disease constraining rice (Oryza sativa L.) production worldwide. The XM6 line was induced by N-methyl-N-nitrosourea from IR24, an Indica cultivar that is susceptible to Philippine and Japanese Xoo races. XM6 was confirmed to carry a recessive gene named xa20, resistant to six Philippine and five Japanese Xoo races. The chromosomal gene location was found using 10 plants with the shortest lesion length in an F₂ population consisting of 298 plants from a susceptible Japonica variety Koshihikari × XM6. Analysis using PCR-based DNA markers covering the whole rice genome indicated the gene as located on the distal region of the long arm of chromosome 3. The IKC3 line carries IR24 genetic background with Koshihikari fragment on chromosome 3 where a resistance gene was thought to be located. The F₂ population from IKC3 × XM6 clearly showed a bimodal distribution separating resistant and susceptible plants. Further linkage analysis conducted using this F₂ population revealed that xa20 is located within the 0.8 cM region flanked by DNA markers KIC3-33.88 (33.0 Mb) and KIC3-34.06 (33.2 Mb). This study yields important findings for resistance breeding and for the genetic mechanism of Xoo resistance.     

日本氮素的循环和流向以及减少N2O散发和NO3-污染的对策

To feed an increasing population, large amounts of chemical nitrogen fertilizer have been used to produce much of our food, feed and fiber thereby increasing nitrogen levels in soils, natural waters, crop residues, livestock wastes, and municipal and agricultural wastes, with national and international concern about its potential adverse effects on environmental quality and public health. To understand these phenomena and problems, first the nitrogen cycle and the environment are described. Then recent trends for nitrogen cycling through the food and feed system, N₂O emissions from fertilized upland and paddy soils, and NO₃^- pollution in ground water in Japan are reported. Finally, mitigation strategies in Japan for reducing N₂O emission and NO₃^- pollution are proposed, including nitrification inhibitors, controlled release fertilizers, utilization of plant species that could suppress nitrification, utilizing the toposequence, government policy, and appropriate agricultural practices. Of all the technologies presented, use of nitrification inhibitors and controlled release fertilizers are deemed the most important with further development of these aspects of technologies being expected. These practices, if employed worldwide, could help reduce the load, or environmental deterioration, on the Earth''s biosphere.     

Huge myxosarcoma arising from the greater omentum in a dog

A 13-year-old intact Pomeranian bitch presented with a 2-month history of abdominal distension and anorexia. Ultrasonography and computed tomography revealed a large tumor in the abdominal cavity without metastases. The tumor was surgically resected and histopathologically characterized by spindle-shaped to atypical-shaped neoplastic cells with basophilic stroma in the omental adipose tissue. Immunohistochemistry revealed that the neoplastic cells were positive for vimentin but negative for cytokeratin, S-100 protein, and α-SMA. The bitch was diagnosed as a myxosarcoma arising from the greater omentum. Postoperatively, metronomic chemotherapy with cyclophosphamide and piroxicam was initiated. The tumor recurred on postoperative day 49. Although the bitch died 102 days after the initial examination, her general condition was maintained until death.