Effects of single and repeated heat stress on anxiety-like behavior and locomotor activity in medaka fish

In this study, we examined whether a single heat stress incident and long-term repeated heat stress could affect behavioral and neural responses in male medaka fish Oryzias latipes. By using the novel tank diving test, we found that 7-day repeated heat stress led to anxiety-like behaviors and suppressed locomotor activity, whereas fluoxetine treatment during repeated heat stress led to anxiolytic behaviors. Furthermore, a single heat stress incident increased hyper-locomotor activity. A single heat stress incident decreased mRNA expression of tryptophan hydroxylase 2 (tph2), a rate-limiting enzyme in serotonin biosynthesis, while a single heat stress increased mRNA expression of tyrosine hydroxylase 1 (th1) and tyrosine hydroxylase 2 (th2), catalyzing dopamine biosynthesis in the brain. Plasma cortisol concentration increased after a single stress, repeated stress, and fluoxetine treatment during repeated stress. These results suggest that medaka fish are a good model for assessing anxiety-like behavior induced by long-term repeated stress. Moreover, th1, th2, and tph2 in the brain would be key factors in the exploration of the central regulation of behavioral responses to a single and repeated stress in fish.

     

Relationship between diarrhea and peripheral leukocyte population in neonatal Japanese black calves

Neonatal Japanese Black (JB) calves show a high incidence of diarrhea. The objective of this study was to analyze the immune cell populations of neonatal JB calves in detail and examine its correlation with the incidence of diarrhea immediately after birth. Understanding the immune cell populations is helpful in clinics in order to determine the condition of the immune system for prevention of diseases. Blood samples were obtained from JB calves on the day of birth. The peripheral leukocyte populations were analyzed separately for calves that had diarrhea within 2 weeks after birth (diarrhea group; n = 26) and for calves without diarrhea (control group; n = 74). The numbers of the peripheral blood CD3(+)TcR1-N12(+) and CD8(+) T cells were significantly lower in the diarrhea group compared with the control group. These findings suggest that the congenital lower peripheral γδ and CD8(+) T cells results in a high risk of diarrhea in neonatal JB calves.     

In-situ growth of ZnO particles on bamboo pulp fabric and its anti-UV property

This research presents a simple way to enhance the anti-UV property of bamboo pulp fabric trough in situ synthesis of ZnO particles on the fabric. Bamboo Pulp Fabric was treated by immersion method in Zn(NO₃)₂ and multi-amide compound (RSD) aqueous solution under hydrothermal condition, then the ZnO particles were grown on the surface of bamboo pulp fabric by in-situ method. In this synthesis RSD was applied as a stabilizer, reactant and dispersant agent, the reaction mechanism was investigated. The ZnO particles were characterized by transmission electron microscope (TEM), Xray diffraction (XRD) and ultraviolet/visible light spectrophotometer. The anti-UV property of Bamboo Pulp Fabric was characterized by measuring its UPF. The results indicated that the diameter of ZnO is about 150 nm, the length is about 600 nm. The Bamboo Pulp Fabric treated with ZnO particles showed good anti-UV property and its UPF can reach to 83.59. After washing for 20 times, it can also keep good anti-UV property.     

Histopathologic effect of in ovo exposure to methotrexate at early embryonic stage on optic tectum of Japanese quail (Coturnix japonica)

The optic tectum of Japanese quail embryos with in ovo exposure to methotrexate 100 ng/g egg on embryonic day 4 was examined from 3 to 24 hour after treatment. At 9 hour after methotrexate exposure, several apoptotic neuroepithelial cells appeared in the ventricular zone of the optic tectum; these increased in number and were diffusely distributed throughout all layers of the ventricular zone of the optic tectum at 12 hour. At 24 hour, neuroepithelial cells in the ventricular zone of the optic tectum were eliminated and showed sparse cell density. Throughout the experimental period, proliferation of neuroepithelial cells in the ventricular zone of the optic tectum of methotrexate-treated embryos was inhibited. These results suggest that neuroepithelial cells in the ventricular zone of the optic tectum in Japanese quail embryos can be affected by folic acid antimetabolites, methotrexate, at an early embryonic stage.     

Relationship of the conception rate and the side (left or right) of preovulatory follicle location at artificial insemination in dairy heifers

In this study, we examined the locational effect (left or right ovary) of the preovulatory follicle (PF) on fertility in dairy heifers. In total, 1,111 artificial inseminations (AI) were analyzed. At AI, PF locations were examined using rectal palpation, and heifers were divided into two groups on their PF locations: (i) the PF located in the left ovary (L‐PF); and (ii) the PF located in the right ovary (R‐PF). Pregnancy was diagnosed by rectal palpation 60 days after AI. The conception rate was 50.7% in all heifers. Conception rate was significantly higher in the L‐PF (60.1%) than in the R‐PF (46.2%). The conception rate was significantly lower by sexed semen (48.6%) than conventional semen (59.1%). Conception rates divided by the semen type (sexed: n = 896, conventional: n = 215) were significantly higher in the L‐PF than in the R‐PF for both semen types (sexed; L‐PF vs. R‐PF: 57.3% vs. 44.4%, conventional; L‐PF vs. R‐PF: 72.3% vs. 53.3%). In addition, season, age, AI number, and the number of re‐inseminations at the same estrus did not affect conception rates. In summary, PF development in the left ovary was associated with increased conception rates in dairy heifers.     

Equine coronavirus induces apoptosis in cultured cells

Equine coronavirus (ECoV) was first isolated from a diarrheic foal and was found genetically similar to group II coronaviruses. However, its pathological characteristics were not adequately investigated. In our preliminary in vitro investigation, ECoV-induced cell death was observed in bovine kidney-derived MDBK cells. Based on this finding, we investigated whether the ECoV-induced CPE was apoptosis. Following ECoV infection, MDBK cells showed morphological changes such as cell rounding and detachment from the culture surface. Moreover, syncytium formation was observed as the other type of cytopathic effect in ECoV infection. Morphologic and biochemical features of apoptosis, such as nuclear fragmentation and DNA ladder formation, were also detected in ECoV-infected cells. Moreover, as is commonly observed in coronavirus infection in other animals, the activities of effecter caspases – caspase-3/7 – and initiator caspases – caspase-8 and caspase-9 – that are representative factors in the death receptor-mediated apoptotic pathway and mitochondrial apoptotic pathway, respectively, were increased in ECoV-infected MDBK cells. Therefore, it was suggested that ECoV can induce apoptosis in MDBK cells via a caspase-dependent pathway. Apoptotic death of infected cells is detrimental because it causes cell and tissue destruction and inflammatory responses. Although the pathological characteristics of ECoV are largely unknown, apoptosis may be the pathological basis of lesions of the digestive system in ECoV infection.     

Irradiation history of Itokawa regolith material deduced from noble gases in the Hayabusa samples

Noble gas isotopes were measured in three rocky grains from asteroid Itokawa to elucidate a history of irradiation from cosmic rays and solar wind on its surface. Large amounts of solar helium (He), neon (Ne), and argon (Ar) trapped in various depths in the grains were observed, which can be explained by multiple implantations of solar wind particles into the grains, combined with preferential He loss caused by frictional wear of space-weathered rims on the grains. Short residence time of less than 8 million years was implied for the grains by an estimate on cosmic-ray-produced (21)Ne. Our results suggest that Itokawa is continuously losing its surface materials into space at a rate of tens of centimeters per million years. The lifetime of Itokawa should be much shorter than the age of our solar system.