Genetic and environmental variances on growth and reproductive traits of silver crucian carp Carassius langsdorfii using communal and separate rearing systems

SUMMARY: Five clonal lines of silver crucian carp Carassius langsdorfii were produced from natural maternal fish to estimate the variance and heritability of total length, bodyweight and gonadosomatic index (GSI). The larvae on the 10th day after hatching were reared together in a common rearing system with five duplicate systems. Another system was prepared using a separate system with two replications in each family. Estimation of variance and heritability were done in the first, third, fifth and 10th month for total length and bodyweight. Microsatellite DNA markers were used to identify the clonal lines in each communal rearing tank. Average heritabilities in the first month were 0.105 for total length (ranging from 0.21 to 0.03) and 0.127 for bodyweight (ranging from 0.22 to 0.06) then decreased in the third, fifth and 10th month. In contrast, intermediate levels of heritability from separate systems were observed. Likewise, relative heritability of GSI in the 10th month presented a high level in both rearing systems. Those heritabilities indicated that growth, total length, bodyweight and reproductive performances of silver crucian carp were affected by genetic influence. The results suggest that clonal lines of silver crucian carp are suitable as experimental animals for evaluations of environmental change and various pollutants through quantitative traits such as growth, reproductive and other physiological traits.     

Differentiation of epithelial cells to M cells in response to bacterial colonization on the follicle-associated epithelium of Peyer's patch in rat small intestine

To clarify the relationship between M cells and intestinal microflora, histoplanimetrical investigation into the bacterial colonization and the differentiation to M cells was carried out in rat Peyer's patch under physiological conditions. The follicle-associated epithelium (FAE), except for the narrow area of apical region, was closely covered with both neighboring intestinal villi and a thick mucous layer, the latter of which also filled the intervillous spaces as well as the space between the FAE and the neighboring intestinal villi. Indigenous bacteria adhered almost constantly to the narrow areas of apical regions of both intestinal villi and the FAE. Bacterial colonies were occasionally located on the basal to middle region of FAE, where M cells also appeared, forming large pockets. When bacterial colonies were located on the basal to middle region of FAE, bacteria with the same morphological characteristics also proliferated in the intervillous spaces neighboring the Peyer's patch. In cases with no bacterial colonies on the basal to middle region of FAE, however, M cells were rare in the FAE. Histoplanimetrical analysis showed the similar distribution pattern of bacterial colonies on the FAE and M cells in the FAE. M cells ultrastructurally engulfed indigenous bacteria, which were then transported to the pockets. These results suggest that indigenous bacterial colonization on the FAE stimulates the differentiation of M cells in the FAE under physiological conditions. The uptake of bacteria by M cells might contribute the regulation of the development of indigenous bacterial colonies in the small intestine.     

Pathological findings of Japanese Black Cattle living in the restricted area of the Fukushima Daiichi Nuclear Power Plant accident, 2013–2016

Fifty‐one Japanese black cattle from four farms in the evacuation zone of the Fukushima nuclear accident were examined pathologically during the period, 2013–2016. We found no evidence of a radiation effect on pathological findings in any of these autopsy cases, although nine cases (3.7%) of enzootic bovine leukosis (EBL) and three cases (1.2%) of goiter were diagnosed. Estimated integrating dose of external exposure in EBL cases ranged from a maximum of 1200 mSv to a minimum of 72 mSv. Clinically, five cases showed wobble, dysstasia or paralysis. Exophthalmos was observed in three cases. Macroscopically, enlarged lymph nodes, multiple irregular masses of intra‐abdominal and intrapelvic adipose tissue, diffuse thickening of the abomasal submucosa with ulceration, and numerous white nodules of myocardium were observed. Histologically, neoplastic lymphoid cells were extensively proliferated and infiltrated in the lesions. Lymphoid tumor cells showed mature or large lymphoblastic appearance. Immunohistochemically, tumor cells were positive for BLA‐36, CD20 and CD5, and negative for CD3. Three cases showed diffuse enlargement of the thyroid gland with no mass or nodule lesion. Histologically, diffuse proliferation of follicular epithelium was observed with preservation of normal structures. There were no malignant findings such as cellular atypia or invasion to capsule.     

Reactivity of anti-Nipah virus monoclonal antibodies to formalin-fixed, paraffin-embedded lung tissues from experimental Nipah and Hendra virus infections

The immunohistochemical reactivity of seven clones of mouse monoclonal antibodies raised to Nipah virus antigens were investigated using formalin-fixed, paraffin embedded porcine and equine lung tissues from experimental Nipah and Hendra virus infection, respectively. Either microwave irradiation or enzymatic digestion effectively unmasked the viral antigens in formalin-fixed, paraffin-embedded tissue sections. Four clones showed positive reaction to both Nipah virus-infected porcine lung tissue and Hendra virus-infected equine lung tissue. Two clones (11F6 and 13A5) reacted with Nipah virus-infected porcine lung tissue, but not with Hendra virus-infected equine lung tissue. These Nipah virus-specific monoclonal antibodies may therefore be useful for immunohistological diagnosis of Nipah virus infection and for further research on Nipah virus pathogenesis.     

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.     

Proliferative potential of endometrial stromal cells, and endometrial and placental expression of cyclin in the bovine

The objective of the present investigation was to study proliferative activity of fibroblast-like endometrial stromal cells in bovine endometrial caruncular (CAR) and intercaruncular (ICAR) areas that have distinct functions during implantation. Endometrial stromal cells were derived from CAR and ICAR of nonpregnant cows, and their proliferative potential was analyzed in an in vitro cell culture system. In addition, expression of four types of cell cycle regulatory molecules was analyzed by RT-PCR in samples of CAR, ICAR, cotyledon (COT) and fetal membrane of both artificially inseminated (AI) and somatic nuclear transferred (NT) cows on days 30 and 60 of gestation. The proliferation growth curve showed that the cells derived from CAR had higher proliferative activity than that of ICAR-derived cells. No morphological differences were found between the cells derived from CAR and ICAR at population-doubling levels (PDL) of the two. Most of the cells derived from ICAR of nonpregnant cows exhibited expanded shape with no further proliferation at PDL 6 with a lack of cyclin E expression. Of the regulatory molecules, cyclin D1, CDK2 and CDK4 were expressed in both CAR and ICAR cells derived from both nonpregnant, and AI cows on days 30 and 60 of gestation. The expression of cyclin E in both AI and NT cows was confined to COT and fetal membrane on day 30 of gestation. Cyclin E expression on day 60 of gestation in AI cows was observed in all but ICAR areas. In marked contrast, however, cyclin E expression on day 60 of gestation in NT cows was confined to COT, suggesting that poor placentation in these cows is possibly associated with a lack of cyclin E expression. These results suggest that CAR-derived stromal cells have higher proliferative potential, which may be related to cyclin E expression during implantation.     

Experimental assessment of the pathogenicity of H5N1 influenza A viruses isolated in Japan

We examined the pathogenicity for chickens of two H5N1 avian influenza viruses isolated in Japan, A/chicken/ Yamaguchi/7/2004 (Ck/Yamaguchi/7/04) isolated from outbreaks in commercial layer chickens, and A/duck/Yokohama/aq10/ 2003 (Dk/Yokohama/aq10/03) isolated from duck meat imported from China. All chickens inoculated intranasally with either strain died, and the viruses were reisolated from all organs examined. However, both the mean time of onset of clinical signs and the mean death time of Ck/Yamaguchi/7/04 were shorter than those of Dk/Yokohama/aq10/03.     

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.     

Congenital chondrodysplastic dwarfism with dyshematopoiesis in a holstein calf

A holstein calf with congenital chondrodysplastic dwarfism was histopathologically examined. The head of the calf was relatively flat giving a dog-like appearance with its short nose and sloping forehead. Limb bones were dumbbell-like with short diaphysis and hypertrophied metaphyses. Bone marrow was pale, whitish and fatty. In the metaphyseal plates most of chondrocytes were pyknotic with swollen and ghost-like cytoplasm, and were irregularly arranged. Column of calcified cartilage were poorly formed losing comb-like structure. Bone marrow was ischemic with poor hematopoiesis and was moderately replaced by adipose tissue. In articular cartilage, most of chondrocytes were degenerated with ghost-like cytoplasm. Many cartilage canals and occasional bone marrow-like structure were formed. The characteristics lesions of the calf were chondrodysplasia and dyshematopoiesis.