Abnormal functions of Leydig cells in crossbred cattle–yak showing infertility

In Mongolia, yak (Bos grunniens) are able to live in alpine areas and their products greatly influence the lives of the local people. Increased vigour in hybridized yak and cattle can offer benefits for livestock farmers. However, male hybrids show reproductive defects resulting from spermatogenesis arrest, affecting the conservation and maintenance of dominant traits in the next generation. The underlying mechanisms involved in hybrid cattle–yak infertility have recently been investigated; however, the genetic cause is still unclear. Androgens and androgen receptor (AR) signalling are required for spermatogenesis. We, therefore, evaluated the expression of AR, 3β-hydroxysteroid dehydrogenase (3βHSD) and 5α-reductase 2 (SRD5A2) in Leydig cells to investigate their function in cattle–yak spermatogenesis. Testicular tissues from yaks (1–3 years old) and hybrids (F1–F3, 2 years old) were collected and subjected to immunohistochemistry and image analyses to investigate the expression of each parameter in the Leydig cells. After maturation at 2 years, the expression levels of AR increased and the levels of 3βHSD decreased, but the SRD5A2 levels remained constant in yak. However, the cattle–yak hybrid F2 showed immature testicular development and significantly different expression levels of AR and 3βHSD compared with mature yak. These results suggest that the decreased expression of AR and increased expression of 3βHSD in the Leydig cells of cattle–yak hybrid testes may represent one of the causes of infertility. Our study might help in solving the problem of infertility in crossbreeding.     

Genetic differentiation of the bronze featherback Notopterus notopterus between Mekong River and Tonle Sap Lake populations by mitochondrial DNA analysis

ABSTRACT:   Although the bronze featherback Notopterus notopterus is an important fish in South-East Asia, the population structure has not been investigated. In this study, genetic diversity and population structure of the bronze featherback were examined using nucleotide sequence analysis of the mitochondrial DNA control region for 332 fish collected from Tonle Sap Lake and the Mekong River in Cambodia. The average nucleotide diversity (π) of all samples was 0.033, and the Mekong River samples had higher nucleotide diversity (0.034) than Tonle Sap Lake samples (0.028). The nucleotide diversity between the lake and river samples varied from 0.029 to 0.037. The genetic differentiation between the river and lake populations was also supported by the pairwise F -statistic values and hierarchical analysis of molecular variance, indicating that the Tonle Sap Lake population is genetically isolated from the population in main stream of the Mekong River.     

Histopathological studies on viral nervous necrosis of sevenband grouper, Epinephelus septemfasciatus Thunberg, at the grow-out stage

Abstract Viral nervous necrosis caused by sevenband grouper nervous necrosis virus (SGNNV) has occurred in grow-out stages (0-3 years old) of sevenband grouper, Epinephelus septemfasciatus, since the 1980s. In the present study, based on histopathological features of the central nervous system (CNS) in naturally diseased fish, pernasal infection experiments using grow-out fish were performed and pernasal infection was established as a putative invasion route of SGNNV. The definite SGNNV-targeted cells were determined by histopathological studies including indirect fluorescent antibody test and electron microscopy. Nerve cells in the olfactory lobe were most extensively necrotized with vacuolation followed by infiltration of microglia and macrophages. Purkinje cells and Golgi cells were extensively infected in the cerebellum. Megalocells and small nerve cell nuclei were also infected in the preoptic area, thalamus, medulla oblongata and spinal cord. Only a few small nerve cells were infected in the olfactory bulb and optic tectum. The retina of some diseased fish displayed vacuolated bipolar cells of the inner nuclear layer and in the ganglion cell layer. These SGNNV-infected nerve cells displayed viroplasmic inclusions containing virions, vacuoles and myelin-like structures. Based on observed histopathological changes, the lesion of the CNS was characterized by encephalitis but not encephalopathy.     

Application of NaLA,a fishing net configuration and loading analysis system,to bottom gill nets

ABSTRACT:   The net-shape and loading analysis system (NaLA) was developed to determine fishing net configuration and load in a previous study. The system has since been applied to general gill nets and aquaculture nets, and its validity has been proven through model experiments in tanks. In this study, the system was applied to estimate the dynamic behavior of a bottom gill net for walleye pollock, to test the system's applicability of the system to gear operations in the field. To obtain in situ data, four bottom gill net operations were performed in February 2004 off the coast of Sawara, Hokkaido, Japan. During operations, vertical displacements of the bottom gill net's float and sinker lines were measured as representative values of gear behavior, and ocean current direction, and speed at the gear position were observed simultaneously. Then, bottom gill net behavior was simulated using NaLA, incorporating observed environmental conditions and gear specifications. The resulting calculated behavior was compared to measured behavior in terms of the relationship between net height and environmental or setting conditions. Agreement between the calculated and measured net behavior was found. Thus, it is believe that our NaLA calculation model has the potential to simulate the dynamic behavior of bottom gill nets in situ .     

Vertebral deformities in cultured red sea bream, Pagrus major, Temminck and Schlegel

Vertebral deformities were investigated in cultured red sea bream, Pagrus major. In the field, deformities in seedlings were categorized and their incidence was calculated. In the laboratory, the symptoms of major vertebral deformities were examined morphologically using radiographs and by making transparent skeletal specimens. The internal structure of deformed vertebrae was examined histologically. The shortened body condition had the highest incidence (0.9–8.3%) of all deformities in the seedlings. In individuals with the shortened body condition, the ratio of trunk and caudal part length to body height was smaller. These fish had skeletal anomalies in the vertebrae, mainly centrum defects (64.3%) or undersized centrums (25.2%). The specimens with centrum defects had a characteristic anomaly in the vertebrae, with plural pairs of neural and haemal spines on a single centrum. This anomaly was frequently observed in the posterior abdominal vertebrae. The internal skeletal structure of such abnormal centrums was basically the same as that of normal centrums. In all the specimens with undersized centrums, both the centrum length and diameter were shorter than normal except for the first and second centrum, and urostyle.     

Scale regeneration and calcification in goldfish <Emphasis Type="Italic">Carassius auratus</Emphasis>: quantitative and morphological processes

The time-course changes in calcium and phosphorus contents, dry weight, and area during scale regeneration in the goldfish, Carassius auratus L. were quantified. Histological observations were then conducted to understand the mutual relationship between the quantitative and morphological processes of scale regeneration. The quantitative study revealed that regenerating scales grow most rapidly in area during the first 5 days of regeneration. The gradual decrease in the area growth rate coupled with the continuous linear weight growth over the period of 5–28 days suggests a shift in growth priority from area growth to the apposition, of the basal plate. Calcium and phosphorus deposition proceeded almost linearly during scale regeneration. Calcification of the bony layer preceded that of the basal plate and, after 14 days of regeneration, calcification of the basal plate started and gradually progressed. On day 28, recovery of calcium and phosphorus contents in the regenerating scales were approximatley 72% of ontogenetic scales, which is lower than the rates of area and weight regeneration (104 and 85%, respectively). Late initiation and slow progress of calcification in the basal plate is suggested to be responsible for the slow regeneration in calcium and phosphorus contents.     

Degradation of endosulfan and endosulfan sulfate by white-rot fungus <Emphasis Type="Italic">Trametes hirsuta</Emphasis>

Endosulfan, an organochlorine insecticide, and its metabolite endosulfan sulfate are persistent in environments and are considered toxic. We investigate the possible nontoxic bioremediation of endosulfan. An endosulfandegrading fungus that does not produce endosulfan sulfate was selected from eight species of white-rot fungi. High degradation of endosulfan and low accumulation of endosulfan sulfate were found in cultures of Trametes hirsuta. A degradation experiment using endosulfan sulfate as the substrate revealed that T. hirsuta is able to further degrade endosulfan sulfate following the oxidative conversion of endosulfan to endosulfan sulfate. Endosulfan and endosulfan sulfate were converted to several metabolites via hydrolytic pathways. In addition, endosulfan dimethylene, previously reported as a metabolite of the soil bacterium Arthrobacter sp., was detected in T. hirsuta culture containing endosulfan sulfate. Our results suggest that T. hirsuta has multiple pathways for the degradation of endosulfan and endosulfan sulfate and thus has great potential for use as a biocatalyst in endosulfan bioremediation.     

Effect of different droplet size on the knockdown efficacy of directly sprayed insecticides

BACKGROUND: Although insecticidal aerosols have been widely accepted for household use, the discharged amount should be maintained at minimum levels because they contain volatile organic compounds. Hence, it would be valuable to develop a technique whereby insecticide droplets adhere efficiently to an insect's body. The present study was undertaken in order to clarify how differences in the mode of adhesion to the insect body influence the knockdown effect. RESULTS: When the discharged volume of droplets with different diameters was the same, the adhesion volume of larger droplets was twice that of smaller droplets, resulting in a higher insect knockdown. In contrast, when the adhesion volume of the two droplet types was the same, a greater number of smaller droplets than larger droplets adhered, and the smaller droplets caused higher insect knockdown. The knockdown effect of both droplet types was lowered when the mesothoracic spiracles of cockroaches were blocked; however, the effect of larger droplets was lowered to a lesser degree. CONCLUSION: The results suggest that, the probability of adhesion to the more susceptible regions of an insect's body, i.e., areas surrounding the mesothoracic spiracles, was improved when a greater number of smaller droplets were adhered, resulting in higher knockdown. Copyright © 2011 Society of Chemical Industry     

The changes of antioxidative enzyme activities in equine erythrocytes following exercise

The change in activities of 3 major antioxidative enzymes in equine erythrocytes, superoxide dismutase (SOD), glutathione peroxidase (GSHpx), and catalase, was investigated in order to evaluate the effect of exercise. Blood samples were obtained from 11 thoroughbred horses before and immediately after vigorous exercise which induced the increase of plasma lipid peroxide (Lpx) concentration from 1.16 +/- 0.40 nmol/ml to 1.29 +/- 0.34 nmol/ml. Following the exercise, the GSHpx activity in erythrocytes was significantly reduced from 69 +/- 10 IU/gHb to 65 +/- 8 IU/gHb, whereas SOD and catalase activities were not changed. Effects of an antioxidative compound, containing selenium and vitamin E(Se-E), on the response of antioxidative enzyme activities following the exercise were examined. Seven horses were injected intramuscularly with Se-E(Se:25 mg, vitamin E:54.8 mg) and received the same vigorous exercise. After Se-E treatment, plasma Lpx levels before the exercise were decreased from 1.24 +/- 0.09 nmol/ml to 0.86 +/- 0.03 nmol/ml, however, SOD, GSHpx, and catalase activities were not varied. The Se-E treatment slightly prevented the decrease in GSHpx activity and the increase in plasma Lpx level after the exercise, having no effect on SOD and catalase activities. These results suggested that the changes of GSHpx activity in erythrocytes might reflect the protective condition against exercise-induced lipid peroxidation.