Changes in follicular vascularity during the first follicular wave in lactating cows

Increase in the blood supply to individual follicles appears to be associated with follicular growth rates and the ability to become the dominant follicle, while reduced thecal vascularity appears to be closely associated with follicular atresia. Therefore, this study aimed to determine the real-time changes in the vascularity of the follicle wall during the first follicular wave in cycling Holstein cows. Normally cycling and lactating cows (n=5) were examined by transrectal color Doppler ultrasonography (the sensitivity for velocity: > 2 mm/sec) to determine the changes in the vasculature of the follicle wall (presence or absence of blood flow) and the diameter of follicles. A new follicular wave and ovulation were induced by GnRH injection at 48 h after an injection of PGF2alpha analogue. The ovaries were scanned daily for 7 days after GnRH injection. Follicles >2.5 mm were classified into 3 groups by the changes in diameter as follows: 1) largest follicle, 2) second largest follicle, and 3) small follicles, which included all other follicles >2.5 mm. Before the follicle selection, there was no significant difference in the percentage of follicles with detectable blood flow between the subsequently determined largest and second largest follicles. After the follicle selection, the percentage of follicles with detectable blood flow significantly decreased among the second largest follicles. In addition, small follicles with detectable blood flow kept larger diameters than those without detectable blood flow from one day before the occurrence of follicle selection. It is likely that maintenance of follicle vasculature and appropriate blood supply to the larger follicles is essential for follicle dominance. In small follicles, the presence of blood flow within the wall also appears to be required for recruitment. Consequently, the data suggest that the change of the blood supply to an individual follicle closely relates to the dynamics of follicular growth in the first follicular wave in the cow.     

Relationship between liver disorders and protection against Eimeria stiedai infection in rabbits immunized with soluble antigens from the bile of infected rabbits

Soluble antigens exist in the bile of rabbits infected with Eimeria stiedai (E. stiedai) in the acute phase, and rabbits immunized with the antigens show resistance against the infection. In this study, the liver function of rabbits immunized either with the soluble antigens or PBS were examined following the parasite challenge. Rabbits immunized with PBS shed a number of oocysts and showed an increase in r-glutamyltransferase (GGT) activity and a decrease in blood Indocyanine green (ICG) clearance. However, rabbits immunized with the soluble antigens shed a lower number of oocysts and showed a transient increase of alanine-aminotransferase (ALT) activity on Day 8 post-challenge (p.c.). The blood Indocyanine green clearance of the rabbits showed no change throughout the experiment. By histopathological observation of the liver, a number of merozoites were found in the biliary ducts on Day 8 post-challenge in the non-immunized rabbits. In contrast, a number of lymphocytes and neutrophilic leukocytes assembled around the biliary ducts of the immunized rabbits, but few parasites were found there on Day 8 post-challenge. These results suggest that the soluble antigens stimulate local immune reactions, for example around the biliary ducts, resulting in elimination of the parasite's development.     

TRAIL-decoy receptor 1 plays inhibitory role in apoptosis of granulosa cells from pig ovarian follicles

Previously, we histochemically examined the localization of tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) and its receptors in porcine ovarian follicles, and demonstrated a marked reduction in the expression of TRAIL-decoy receptor-1 (DcRI) in granulosa cells of atretic follicles. In the present study, to confirm the inhibitory activity of DcR1 in granulosa cells, granulosa cells prepared from healthy follicles were treated with phosphatidylinositol-specific phospholipase C (PI-PLC) to cleave glycophospholipid anchor of DcR1 and to remove DcR1 from the cell surface, and then incubated with TRAIL. PI-PLC treatment increased the number of apoptotic cells induced by TRAIL. The present finding indicated the possibility that TRAIL and its receptors were involved in induction of apoptosis in granulosa cells during atresia, and that DcR1 plays an inhibitory role in granulosa cell apoptosis.     

Serum leptin levels during the periparturient period in cows

Serum leptin concentrations were measured in antenatal and postnatal cows housed at two different locations. The mean serum leptin concentration was 9.2 +/- 0.6 ng/m l (n=22) in one group, and was slightly lower in the other (7.4 +/- 0.4 ng/ml, n=54), probably because of the different nutritional conditions between the two groups. There was no consistent variation in relation to the menstrual cycle and the periparturient period in both groups. Moreover, serum leptin concentrations during the periparturient period were independent of the number of delivery and the incidence of mastitis and milk fever. These results are quite different from those in rodents and human, suggesting the different regulatory mechanism of circulating leptin concentration in cows.     

Prostaglandin F2α Stimulates Endothelial Nitric Oxide Synthase Depending on the Existence of Bovine Granulosa Cells: Analysis by Co‐culture System of Endothelial Cells,Smooth Muscle Cells and Granulosa Cells

Prostaglandin F_2α (PGF_2α) induces luteolysis in the mid but not in the early luteal phase; despite this, both the early and the mid corpus luteum (CL) have PGF_2α receptor (FPr). We previously indicated that the luteal blood flow surrounding the CL drastically increases prior to a decrease of progesterone (P) in the cows, suggesting that an acute increase of luteal blood flow may be an early sign of luteolysis in response to PGF_2α and that this may be induced by a vasorelaxant nitric oxide (NO). The aim of this study was to investigate the luteal stage‐dependent and the site‐restricted effect of PGF_2α and NO on the mRNA expressions and P secretion. To mimic the local luteal region both of peripheral and central areas of the CL, we utilized co‐cultures using bovine aorta endothelial cells (EC), smooth muscle cells (SMC) and luteinizing granulosa cells (GC) or fully‐luteinized GC. PGF_2α stimulated the expression of endothelial NO synthase (eNOS) mRNA at 0.5 h in mix‐cultures of EC and SMC with fully‐luteinized GC but not with luteinizing GC. The expression of eNOS mRNA in EC was increased by PGF_2α at 1 h only when EC was cultured together with fully‐luteinized GC but not with luteinizing GC. In all co‐cultures, PGF_2α did not affect the mRNA expression of FPr. Treatment of NO donor inhibited P secretion at 0.5 h. In conclusion, the present study suggests that the coexistence of the mature luteal cells (fully‐luteinized GC) with EC/SMC may be crucial for acquiring functional NO synthesis induced by PGF_2α.     

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.     

Factors determining the distribution of a keystone understory taxon, dwarf bamboo of the section Crassinodi, on a national scale: application to impact assessment of climate change in Japan

The objective of this study was to identify climatic factors determining the distribution of a keystone understory taxon, section Crassinodi of the genus Sasa, and assess the impacts of climate change on the taxon. Relationships between the distribution of sect. Crassinodi and five climatic variables were explored using classification tree analysis. Potential habitats under current climate and future climate in 2081–2100 were predicted. Potential habitats were further divided into suitable and marginal habitats. The predictive accuracy of the model was assessed using receiver operating characteristic analysis and by comparing model predictions with an independent dataset. The model was reasonably accurate. It showed that the warmth index (WI) and snow cover were the most important climatic variables for Crassinodi distribution. Potential habitats were limited to cooler regions with WI <102.7°C month. Suitable habitats were limited to even cooler regions with WI <84.8°C month. The model also showed that areas with deeper snow than previously reported would provide suitable habitats for Crassinodi under some climatic conditions. In 2081–2100, 37.4% of current potential habitats are predicted to become non-habitats because of increases in WI. Most currently suitable habitats are predicted to vanish from western Japan by 2081–2100. Meanwhile, Hokkaido and high-elevation areas of eastern Honshu will sustain suitable habitats. Sect. Crassinodi, which is adapted to less snowy climates, is predicted to be more affected by climate change than sect. Sasa and Macrochlamys, which are adapted to snowy climates.     

Influence of autonomic nervous activity on variations in the R-R intervals in adult goats

We used a heart rate memory apparatus to measure 2047 successive R-R intervals with an accuracy of 10 msec in adult goats. For 100 successive stationary R-R intervals out of the 2047 intervals, the R-R intervals sequence was recorded graphically and the means and standard deviations (SD) were calculated. The magnitude of the variation in the R-R intervals was represented by the SD. The usefulness of the analysis of R-R intervals as an indicator of autonomic nervous activity was determined. The diagram of 100 successive R-R intervals at rest showed a conspicuous periodic fluctuation. After the administration of atropine, atropine plus propranolol or after feeding, the R-R intervals were markedly shortened and the variations in the R-R intervals were abolished. After the administration of propranolol only, the R-R intervals were prolonged and the amplitude of the fluctuations in the R-R intervals was conspicuously increased. The respiration curve and the variation in the R-R intervals at rest fluctuated in periodic synchrony. A positive correlation between the mean and the SD of the R-R intervals was highly significant. This indicates that the variations in the R-R intervals in the adult goats are closely related to autonomic nervous activity and that the analysis of the R-R intervals is suitable for the noninvasive assessment of autonomic nervous activity.