Different effects of ionic and non-ionic compounds on the freeze denaturation of myofibrils and myosin subfragment-1

The effects of non-ionic (sorbitol, maltose, trehalose) and ionic compounds (Na-glutamate, Na-acetate, Na-sulfate, ammonium sulfate) on freeze denaturation of myosin subfragment-1 (S-1) and of myofibrils were compared. Sugars, Na-glutamate and Na-acetate well suppressed the freeze denaturation of myofibrils as well as S-1 in a concentration dependent manner. Although sulfate suppressed freeze denaturation of S-1 irregularly, it accelerated myofibril denaturation. It was concluded that sulfate salts were useless as cryoprotectant for myofibrils. Stabilization extent by F-actin in frozen storage was much less than that in heating.     

X-irradiation Removes Endogenous Primordial Germ Cells (PGCs) and Increases Germline Transmission of Donor PGCs in Chimeric Chickens

Primordial germ cells (PGCs) are embryonic precursors of germline cells with potential applications in genetic conservation, transgenic animal production and germline stem cell research. These lines of research would benefit from improved germline transmission of transplanted PGCs in chimeric chickens. We therefore evaluated the effects of pretransplant X-irradiation of recipient embryos on the efficacy of germline transmission of donor PGCs in chimeric chickens. Intact chicken eggs were exposed to X-ray doses of 3, 6 and 9 Gy (dose rate = 0.12 Gy/min) after 52 h of incubation. There was no significant difference in hatching rate between the 3-Gy-irradiated group and the nonirradiated control group (40.0 vs. 69.6%), but the hatching rate in the 6-Gy-irradiated group (28.6%) was significantly lower than in the control group (P<0.05). No embryos irradiated with 9 Gy of X-rays survived to hatching. X-irradiation significantly reduced the number of endogenous PGCs in the embryonic gonads at stage 27 in a dose-dependent manner compared with nonirradiated controls. The numbers of endogenous PGCs in the 3-, 6- and 9-Gy-irradiated groups were 21.0, 9.6 and 4.6% of the nonirradiated control numbers, respectively. Sets of 100 donor PGCs were subsequently transferred intravascularly into embryos irradiated with 3 Gy X-rays and nonirradiated control embryos. Genetic cross-test analysis revealed that the germline transmission rate in the 3-Gy-irradiated group was significantly higher than in the control group (27.5 vs. 5.6%; P<0.05). In conclusion, X-irradiation reduced the number of endogenous PGCs and increased the germline transmission of transferred PGCs in chimeric chickens.     

Production of stem cell factor in canine mast cell tumors

Mast cell tumor (MCT) is the most common cutaneous tumor in dogs. We recently revealed that production of stem cell factor (SCF) contributes to the proliferation of neoplastic mast cells in an autocrine/paracrine manner. The aim of the present study was to determine the contribution of the mechanism in clinical MCTs. In consequence, high SCF expression (>10 times compared to HRMC cells) was observed in 5 of 7 MCT samples used in the study regardless of KIT mutation, which was confirmed in immunohistochemical analysis. In addition, production of SCF was observed in Ki-67-positive cells in the MCT xenograft. These results indicate the broad contribution of SCF autocrine/paracrine mechanism on clinical MCTs, providing the rationale for the clinical use of KIT inhibitors regardless of KIT mutation.     

Background data of 2-year-old male and female F344 gpt delta rats

Although gpt delta rats, as reporter gene-transgenic rats, were originally developed for in vivo mutation assays, they have also been used to evaluate chemical carcinogenesis and comprehensive toxicity. Therefore, it is necessary to accumulate background data on carcinogenicity and general toxicity in gpt delta rats. Here, we investigated the background data of 110-week-old male and female F344 gpt delta rats and wild-type rats. There was no effect of reporter gene transfection on animal survival rates and body weights during the experiment. The relative weight of male gpt delta rat adrenals was significantly higher than that of wild-type rats, possibly due to the higher incidence of pheochromocytoma. There were no intergenotype differences in the incidence of nonneoplastic lesions in both sexes, including chronic progressive nephropathy and focus of cellular alteration in the liver, which had a higher incidence in both genotypes. Additionally, the significantly higher incidence of adrenal pheochromocytoma in male gpt delta rats than that in wild-type rats was likely incidental because of the lack of differences in the incidences of preneoplastic (male and female) and neoplastic (female) adrenal lesions in both genotypes. Other neoplastic lesions in both sexes showed no intergenotype differences in incidence rates, although large granular lymphocytic leukemia in the spleen and Leydig cell tumors in the testes of males showed higher incidence rates. Overall, there were no effects of reporter gene transfection on the spectrum of spontaneous lesions in F344 gpt delta rats, thus supporting their applicability in evaluating chemical toxicity and carcinogenicity.     

RPR test for serological survey of rabbit syphilis in companion rabbits

Since the RPR (rapid plasma regain) test was found to be useful for the diagnosis of rabbit syphilis, serological survey by this test has been carried out in Japanese companion rabbits. A hundred virgin household rabbits kept alone and without signs and history of syphilis were examined by RPR test from April 2001 to March 2002, in Tokyo, Japan. The test was positive in 35 cases and negative in 65 cases. RPR negative rabbits should be selected for breeding to prevent the spread of rabbit syphilis in companion rabbits in Japan.     

Effects of temperature, salinity and their interaction on growth of toxic Ostreopsis sp. 1 and Ostreopsis sp. 6 (Dinophyceae) isolated from Japanese coastal waters

Some species belonging to Ostreopsis, a benthic dinoflagellate genus, are known to produce palytoxin analogues. Around the coastal regions of Japan, the toxic Ostreopsis sp. 1 and Ostreopsis sp. 6 which are genetically divergent from other species of Ostreopsis are present from the southern to northern regions and in the southern region, respectively. The present study examined the growth responses of these strains to seven temperatures (15–35 °C) in combination with five salinities (20–40) and discusses the effects of temperature and salinity on their distribution and bloom dynamics in Japan. Tolerable temperatures and salinities ranged 15–30 °C and 25–40 for Ostreopsis sp. 1, and 17.5–30 °C and 20–40 for Ostreopsis sp. 6. The optimal temperature ranges which gave growth rates of >90 % of maximal growth rate of each strain were 22–25 °C for Ostreopsis sp. 1 and 24–30 °C for Ostreopsis sp. 6. Therefore, Ostreopsis sp. 1 is putatively tolerant to lower temperatures and thus possesses adaptability to colder waters of relatively higher latitude regions of Japan, whereas Ostreopsis sp. 6 presumably possesses adaptability to warmer waters of the southern region. We conclude that growth responses of Japanese toxic Ostreopsis sp. 1 and Ostreopsis sp. 6 to temperature-salinity affect their distribution and bloom dynamics in Japan.     

Establishment of a model for chemoattraction of <Emphasis Type="Italic">Symbiodinium</Emphasis> and characterization of chemotactic compounds in <Emphasis Type="Italic">Acropora tenuis</Emphasis>

Corals harbor symbiotic dinoflagellates, Symbiodinium spp., acquired from surrounding environments. Because Symbiodinium are present at low densities in the water column, corals may attract these symbionts using chemotactic compounds. To examine whether corals contain chemotactic compounds, we established an assay to measure the chemotactic activity for Symbiodinium using an extract of the coral Acropora tenuis, a major reef-building coral in Japan. Our assay revealed that Symbiodinium strain NBRC102920 (clade A), which is taken up by juvenile A. tenuis polyps, is attracted to crude A. tenuis extracts. We found that the chemotactic compounds are water-soluble, heat-labile macromolecules and that the chemotactic activity was inhibited by N-acetyl-d-glucosamine (GlcNAc). We separated the GlcNAc-binding fraction (Fr-ActL) and identified it as the most plausible candidate for the chemoattractant, since the chemotactic activity of the crude A. tenuis extract appeared to be mainly attributable to the activity of Fr-ActL and was also inhibited by the addition of GlcNAc. These results indicate that chemoattraction is mediated via the binding of Symbiodinium to Fr-ActL.     

An epidemic of caprine arthritis encephalitis in Japan: isolation of the virus

A disease characterized by arthritis of carpal joints and occasionally by pneumonia was seen among goats on a farm in Nagano prefecture of Japan in the summer of 2002. Serological investigation was done on 30 goats, that is one group on the farm by agar gel immunodiffusion tests using maedi-visna virus as the antigen, and 19 goats were positive. The caprine arthritis encephalitis virus genome was detected in peripheral blood leukocytes from several antibody-positive goats. Two goats among them were necropsied and used for pathological tests and virus isolation. The isolated virus was serially propagated in fetal lamb lung cell cultures. Goats inoculated with the culture fluid became antibody positive. These results suggested that a CAEV-infected goat had been introduced accidentally to the farm and that subclinical infection occurred among the flock.