Effects of temperature on vitellogenesis in Japanese eel Anguilla japonica

ABSTRACT:   Cultured immature female Japanese eels acclimated to sea water at either 10 or 20°C were treated weekly with salmon gonadotropin fraction (sGTH) in order to investigate the effects of water temperature on artificial induction of ovarian maturation. In eels maintained at 20°C, ovulation was induced in 11 of 18 fish during the experimental period of 13 weeks, whereas at 10°C all fish showed a low gonadosomatic index (GSI) at the end of the experiment. Plasma vitellogenin levels were higher in eels kept at 20°C than in eels at 10°C throughout the experiment. However, no significant differences were observed in the plasma testosterone and estradiol-17β levels between groups. Eels pretreated with sGTHs at 10°C for 13 weeks were separated to two different temperature (10 and 20°C) groups, and received the same weekly sGTH injections. In eels transferred to 20°C, plasma vitellogenin levels, GSI and oocyte diameter were increased, but these values were maintained at low levels in eels that remained at 10°C. These results clearly indicate that water temperature is an important factor regulating vitellogenesis in the Japanese eel.     

Neuronal activation modulates enhancer activity of genes for excitatory synaptogenesis through de novo DNA methylation

Post-mitotic neurons do exhibit DNA methylation changes, contrary to the longstanding belief that the epigenetic pattern in terminally differentiated cells is essentially unchanged. While the mechanism and physiological significance of DNA demethylation in neurons have been extensively elucidated, the occurrence of de novo DNA methylation and its impacts have been much less investigated. In the present study, we showed that neuronal activation induces de novo DNA methylation at enhancer regions, which can repress target genes in primary cultured hippocampal neurons. The functional significance of this de novo DNA methylation was underpinned by the demonstration that inhibition of DNA methyltransferase (DNMT) activity decreased neuronal activity-induced excitatory synaptogenesis. Overexpression of WW and C2 domain-containing 1 (Wwc1), a representative target gene of de novo DNA methylation, could phenocopy this DNMT inhibition-induced decrease in synaptogenesis. We found that both DNMT1 and DNMT3a were required for neuronal activity-induced de novo DNA methylation of the Wwc1 enhancer. Taken together, we concluded that neuronal activity-induced de novo DNA methylation that affects gene expression has an impact on neuronal physiology that is comparable to that of DNA demethylation. Since the different requirements of DNMTs for germ cell and embryonic development are known, our findings also have considerable implications for future studies on epigenomics in the field of reproductive biology.     

Effects of winter barley as a cover crop on the weed vegetation in a no-tillage soybean

The present study clarified the effects of winter barley as a cover crop on the weed vegetation, expressed as a multiplied dominance ratio (MDR), and emergence of summer annual weeds in a no-tillage soybean system. A 3 year field study with treatments consisting of six systems was conducted: no-tillage single cropping, no-tillage cropping following winter barley and tillage single cropping, respectively with and without herbicide application. The MDR of perennial weeds increased annually in the no-tillage fields in spring, but summer annual weeds were abundant in all fields, including the no-tillage fields in summer. Grasses, for example Digitaria ciliaris (Retz.) Koeler, were especially abundant in the no-tillage fields. The MDR of summer annual weeds, especially grasses in the barley and soybean fields, were much lower than for the no-tillage single soybean fields. Densities of D. ciliaris and Echinochloa crus-galli (L.) Beauv. var. crus-galli in the no-tillage single soybean fields were much greater than in the tilled fields, with few exceptions. In contrast, broad-leaved weeds emerged more in tilled fields than in the no-tillage fields. Winter barley suppressed emergence of summer annual weeds, especially during the first 3 years. The MDR for grasses in summer showed a good correlation with the frequency of emergence for grasses every year. These results showed that the increase in the volume of grasses in summer resulted mainly from an increase in the frequency of emergence, and that the suppression of grasses by winter barley resulted mainly from suppression of the emergence frequency. Soybean yields were higher in the barley and soybean fields for the first 2 years.     

Prophylactic treatment with sulphonated immunoglobulin G attenuates development of mechanical allodynia-like response in mice with neuropathic pain

Human immunoglobulin G (IgG) concentrates are immune-modulating,anti-inflammatory plasma-derived products. Clinical studies in recent years have suggestedthat IgG attenuates neuropathic pain. In this study, effects of sulphonated IgG on thedevelopment and maintenance of a mechanical allodynia-like response were examined in micewith neuropathic pain induced by a partial sciatic nerve ligation (PSL). When sulphonatedIgG (400 or 1,000 mg/kg/day, i.p.) was administered for 5 days, from 1 day before surgeryto post-operative day (POD) 3, the development of a mechanical allodynia-like response wasattenuated. On the other hand, sulphonated IgG had little effect on the maintenance of amechanical allodynia-like response when administered for 5 days, from POD 11 to POD 15, atwhich time a mechanical allodynia-like response had already been developed. To explore themechanism of sulphonated IgG, the mRNA expression of inflammatory cytokines was evaluatedin the injured sciatic nerve. Sulphonated IgG (1,000 mg/kg/day, i.p.) that wasadministered for 3 days, from 1 day before surgery to POD 1, significantly attenuated theup-regulation of tumor necrosis factor-α and monocyte chemotactic protein-1 mRNAs on POD1. These results suggest that prophylactic treatment with sulphonated IgG attenuates thedevelopment of mechanical allodynia-like response by inhibition of inflammatory cytokineexpression in mice with PSL.     

Diagnostic imaging of intra-abdominal cyst in heifer using the computed tomography

A 10-month-old Japanese black heifer was diagnosed as having an intra-abdominal cyst using computed tomography (CT). Through a posterior ventral midline incision, the cyst was removed, and the heifer completely recovered after the surgery. CT scans enabled detection of the intra-abdominal cyst and measurements of the diameter of the cyst before the surgery.     

多花黑麦草抗病基因类似物的克隆及CAPS标记

多花黑麦草具有适应性强、生物产量高和品质好等优点,为我国南方及其他温带地区重要的牧草。本研究利用目前已克隆出的抗病基因(R基因)所编码的蛋白质结构上所具有的共同氨基酸基序NBS-LRR设计寡核苷酸简并引物,对多花黑麦草基因组进行抗病基因类似物(RGA)克隆。从克隆中筛选出具代表性的RGA克隆115个,设计RGA-STS引物113对。利用细胞质雄性不育(CMS)F1群体对RGA-STS引物进行筛选,并采用限制性内切酶酶切扩增多态序列(CAPS)法进行抗病类似物的分子标记,共检测到22对RGA-STS引物的扩增产物具多态性,22个RGA-CAPS标记均被标记于多花黑麦草遗传连锁图中。结果还表明RGA在多花黑麦草遗传连锁图中分布范围较广,并具有簇状分布特性。