Positive correlation between the number of root nodule primordia and seed sugar secretion in soybean (Glycine max L.) seedlings inoculated with a low density of Bradyrhizobium japonicum

Sufficient rhizobium population in the rhizosphere of legume seedlings is required for early and enough setting of root nodules. Potential of seed and seedling root exudates for proliferation of Bradyrhizobium japonicum PNT119 was evaluated in the soybean cvs. Enrei and Tachinagaha. In both cultivars, seed exudates showed a higher potential than root exudates. In the seed exudates, a low-molecular high-polarity fraction including sugars and amino acids showed a higher potential than both high-molecular fraction and low-molecular low-polarity fraction. The correlations between the sugar or amino acid contents of seed exudates and the number of root nodule primordia at 7 d after sowing were investigated among 12 soybean cultivars. When seeds were inoculated with a low rhizobium density, a high correlation coefficient was detected between them. However, there was no positive correlation in the plants inoculated with a high rhizobium density. These results suggest that the amount of low molecular substances in the seed exudates determines the number of root nodule primordia through rhizobium proliferation around seed and young roots when the rhizobium density is the limiting factor. The genetic trait relating to seed coat secretion should be considered as a possible key factor contributing to adequate root nodulation in soybean seedlings cultivated in fields with a low rhizobium density.     

Individual variations in behavior and free cortisol responses to acute stress in tiger pufferfish Takifugu rubripes

Abstract:   The aim of the present study was for individual variation in behavior to be characterized and related to differences in physiological stress responses in juvenile tiger pufferfish (fugu) Takifugu rubripes . A set of siblings ( n  = 330) from wild parents was subjected to behavior tests, and some were classified into active and inactive groups ( n  = 42 each group). The active animals consisted of those individuals that kept active swimming during 6 min after transfer from one tank to another, and the inactive animals were those that stopped swimming within 6 min. Time-course acute stress responses, which were elicited by anesthesia and subsequent removal of a pectoral fin, were compared between the active and inactive fish. The stress indicators used were free and total plasma cortisol, and plasma glucose. Although no significant difference was observed at each sampling point between groups, the inactive fish required shorter recovery time from acute stress in all three indicators than the active fish. The percentage of free to total plasma cortisol in the pre-stress condition was significantly lower in the inactive group than in the active group. Our findings indicate that fugu has behavioral variation that is associated with stress responsiveness. The inactive fish are expected to be more tolerant of stress and suitable for aquaculture.     

Relationships between critical photon irradiance for growth and daily compensation point of juvenile Sargassum macrocarpum

SUMMARY: This study was designed to determine the critical photon irradiance for growth and daily compensation point of juvenile Sargassum macrocarpum . Sampling and measurement of natural light conditions were carried out in the S. macrocarpum population at a depth of 8 m off Kiwado in Fukawa Bay, Yamaguchi Prefecture, Japan, from April to June 1998. Photosynthesis and respiration of the juvenile thalli, and diurnal changes in solar irradiance were measured for the same period. The critical photon irradiance for growth of the juvenile thalli observed on the population floor was 1.0–1.5% on the sea surface. The photosynthetic rate of leaf of juvenile thalli increased linearly with increasing photon irradiance when light levels were lower than 50 μM/m² per s. The respiratory rate and light compensation point of the juvenile thalli were 2.49 μL O₂/cm² per h and 4.98 μM/m² per s, respectively. The daily compensation point was estimated with a mathematical model based on photosynthesis–light equations and diurnal changes in solar irradiance. For a day of average solar irradiance over the period of the present study, the estimated daily compensation point of the juvenile thalli was 1.3% on the sea surface. This value agreed well with the observed critical photon irradiance for growth of juvenile S . macrocarpum on the population floor. The results of the study confirm that the mathematical model is effective for estimating the daily compensation point.     

Borna disease virus infection in domestic cats: evaluation by RNA and antibody detection

Borna disease virus (BDV) infection has been suggested to cause spontaneous neurological disease in cats referred to as staggering disease. However the evaluation of BDV infection in neurologically asymptomatic cats remained unclear. In the present study, BDV infected, asymptomatic cats in Tokyo were surveyed both by the presence of plasma antibodies against BDV-p24 and -p40 and by RNA detection in peripheral blood mononuclear cells. Seven of 32 domestic cats (21.9%) were serologically or genetically judged to be BDV-infected. Six cats were positive for anti-BDV antibody and two cats were positive for BDV RNA. Within the 2 RNA-positive cats, only one was positive for anti-BDV antibodies. Furthermore, the findings of anti-BDV-p40 and anti-BDV-p24 antibody-positive cats did not completely overlap. These results suggest that there are neurologically asymptomatic domestic cats infected with BDV present in the Tokyo area.     

Myeloma-related disorder with leukaemic progression in a cat

A 10-year-old American Shorthair cat with nasal discharge, anorexia, and weight loss was found to have pancytopenia and hyperproteinaemia. Bone marrow aspiration revealed atypical plasma cells that totalled 50% of the nucleated bone marrow cells. The number of atypical plasma cells progressively increased in the peripheral blood during the observation period of 64 days. The cat did not respond to treatments with melphalan, chlorambucil, and prednisolone, and died 71 days after the initial presentation. Clinical, cytological, histopathological, and immunohistochemical findings in this case supported the diagnosis of myeloma-related disorder (MRD) with leukaemic progression.     

An outbreak of systemic granulomatous disease in cows with high milk yields

Seven of 92 lactating Holstein cows on a dairy farm developed urticaria with alopecia and decreased milk production, and three of the seven died over the course of 7 to 18 days. Pathologic examination of the three cows, including the two dead and one euthanized cow, revealed that the skin, liver, spleen, kidneys, heart, salivary glands, pancreas, adrenal glands, mammary glands, lymph nodes, and trigeminal ganglia had lymphocytic to lymphogranulomatous inflammation. Inflammation predominated by lymphocytic infiltration was prominent in the heart, pancreas, mammary glands, adrenal gland, and trigeminal ganglia. Severe granulomatous inflammation with multinucleated giant cells was present in the spleen and kidneys. These lesions and their distributions were most similar to those seen in suspected cases of citrus pulp toxicosis and hairy vetch toxicosis. The outbreak of this disease resolved with the elimination of Citrus pulp from the feed. Immunohistochemical detection of lymphocytes and macrophage markers confirmed dramatic hyperplasia of CD3-positive T lymphocytes in these lesions. This strongly suggested that a type 4 hypersensitivity reaction played a role in the development of the lesions.     

Long-term treatment effects of Pueraria mirifica phytoestrogens on parathyroid hormone and calcium levels in aged menopausal cynomolgus monkeys

To determine the effect of Pueraria mirifica (PM) on serum parathyroid hormone (PTH) and calcium levels on aged menopausal monkeys (Macaca fascicularis), subjects were treated with 10, 100, or 1,000 mg/day of PM. Blood samples were collected every 5 days for 30, 90, and 60 days during pre-treatment, treatment, and post-treatment periods, respectively. Sera were assayed for PTH, estradiol, and calcium levels. PM-1,000 had the strongest effect on the decrease in PTH (0.001相似文献