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1.
Treatment of cut-throat trout broodfish Salmo clarki (Richardson) with Sulphamerazine at 220 mg/kg (10 g/100 1b) of fish/day for 14 days resulted in severe kidney histopathology and increased mortality among males. Experimental data presented showed that cut-throat trout broodfish were extremely sensitive to Sulphamerazine toxicity. Hydropic degeneration of renal tubule epithelium and haemorrhage into tubule lumens were observed in kidneys of both male and female trout, but was more severe in the former. Death, which occurred only in males, was correlated with spawning stress and impaired renal function.  相似文献   
2.
Extraction of the white matter of pig brain with EDTA, lysolecithin or Triton X-100 gave poor yields of soluble acetylcholinesterase although these agents had proved effective at solubilizing the enzyme in the grey matter. This finding, together with the observation that the strong detergent sodium deoxycholate, was needed to solubilize the enzyme, shows that it is more difficult to remove acetylcholinesterase from the white matter of brain than from the grey. This could mean that the enzyme in the white matter is more firmly bound to the membrane than the enzyme in the grey matter.The difference in binding of the enzyme from the two regions of the brain is also reflected in the affinity chromatography experiments which showed a lower recovery for the acetylcholinesterase of white matter compared with the enzyme from grey matter.Starch-block electrophoresis of acetylcholinesterase showed a single negatively charged peak of activity for both the naturally soluble and the deoxycholate solubilized preparations. The presence of only one form on electrophoresis suggests that the molecular species of acetylcholinesterase do not arise from differences in charge.Sucrose density gradient centrifugation of the two preparations from white matter gave a single peak of activity with a sedimentation constant of about 10 S. This corresponds closely to the major species of molecular weight 260,000 detected by gradient gel electrophoresis. Other forms detected in both enzyme preparations by gradient gel electrophoresis were species with molecular weights of 660,000, 180,000, 130,000 and 115,000. The significance of these species in terms of the formation of oligomers is discussed.A comparison was made with the corresponding preparations of acetylcholinesterase from the grey matter and the results showed that acetylcholinesterase from the white and grey matter of pig brain were very similar. The exception to this was the species with a molecular weight of 68,000 which was present in the grey but not the white matter of pig brain.  相似文献   
3.
Unilateral 6-hydroxydopamine (6OHDA) lesions of the nigrostriatal pathway resulted in contraversive rotation to apomorphine and ipsiversive rotation to amphetamine. Electrolytic lesioning of the nucleus reticularis gigantocellularis or kainic acid lesions of the nucleus tegmenti pedunculopontis on the same side as the 6OHDA lesion did not reduce apomorphine- or amphetamine-induced circling. An electrolesion of the angular complex (periaqueductal grey and adjacent reticular formation) on the same side as the 6OHDA lesion reduced apomorphine-induced circling and increased amphetamine-induced circling. Bilateral electrolesions of the angular complex reduced both apomorphine- and amphetamine-induced rotation. The decrease in rotation was due to a loss of postural asymmetry while locomotor hyperactivity was maintained. A unilateral kainic acid lesion of the angular complex alone caused weak ipsiversive rotation which was enhanced by apomorphine and amphetamine. When a unilateral kainic acid lesion of the angular complex was made on the same side as a prior 6OHDA lesion, both apomorphine and amphetamine induced ipsiversive rotation. The area of the angular complex is critically involved in the mediation of drug-induced circling in unilaterally 6OHDA lesioned rats and in particular the postural component.  相似文献   
4.
Unilateral injection of 6-hydroxydopamine (6-OHDA) into the ascending nigrostriatal pathway caused contraversive circling to apomorphine and ipsiversive circling to amphetamine respectively. An electrolesion of the ventromedial thalamic nucleus on the same side as the 6-OHDA lesion reduced apomorphine-induced circling, but not that to amphetamine. An electrolesion of the ventromedial thalamic nucleus on the side opposite to the 6-OHDA lesion reduced amphetamine circling but not that to apomorphine. Bilateral electrolesions of the ventromedial thalamic nucleus reduced neither apomorphine- nor amphetamine-induced circling. Electrolytic lesions of the parafascicular thalamic nucleus did not reduce apomorphine- or amphetamine-induced circling in animals with a unilateral 6-OHDA lesion of the nigrostriatal pathway. Knife cuts rostral and dorsal to the substantia nigra did not attenuate circling induced by injection of muscimol into the substantia nigra. Circling due to activition of nigral output pathways can be mediated by descending nigro-reticular pathways.  相似文献   
5.
当前因SARS-CoV-2感染而引起的2019新型冠状病毒肺炎(COVID-19)肆虐全球,严重危害人类健康。SARS-CoV-2感染性强,危重症患者死亡率高,尽管各种各样的治疗正在进行临床试验,但目前尚无有效的治疗方法。间充质干细胞(mesenchymal stem cell,MSC)在临床前试验中对多种疾病有良好的治疗效果,因而受到了广泛地关注。MSC可能利用分化潜能诱导分化成功能性肺样细胞、免疫调节与免疫细胞互作、抑制炎症来降低促炎细胞因子分泌、迁移和归巢靶向损伤肺部、抗病毒作用来减少肺上皮细胞中的病毒复制、产生细胞外囊泡来修复受损的组织,进而使COVID-19患者肺功能逐渐恢复正常,缓解并达到治疗COVID-19的目的。综合讨论了COVID-19的基本特征和当前主要治疗手段,同时总结了MSC在COVID-19中的临床研究和当前面临的挑战,探讨了MSC治疗COVID-19的应用前景,为MSC在COVID-19中的治疗提供了理论基础和现实依据。  相似文献   
6.
Globally, carbon‐rich mangrove forests are deforested and degraded due to land‐use and land‐cover change (LULCC). The impact of mangrove deforestation on carbon emissions has been reported on a global scale; however, uncertainty remains at subnational scales due to geographical variability and field data limitations. We present an assessment of blue carbon storage at five mangrove sites across West Papua Province, Indonesia, a region that supports 10% of the world's mangrove area. The sites are representative of contrasting hydrogeomorphic settings and also capture change over a 25‐years LULCC chronosequence. Field‐based assessments were conducted across 255 plots covering undisturbed and LULCC‐affected mangroves (0‐, 5‐, 10‐, 15‐ and 25‐year‐old post‐harvest or regenerating forests as well as 15‐year‐old aquaculture ponds). Undisturbed mangroves stored total ecosystem carbon stocks of 182–2,730 (mean ± SD: 1,087 ± 584) Mg C/ha, with the large variation driven by hydrogeomorphic settings. The highest carbon stocks were found in estuarine interior (EI) mangroves, followed by open coast interior, open coast fringe and EI forests. Forest harvesting did not significantly affect soil carbon stocks, despite an elevated dead wood density relative to undisturbed forests, but it did remove nearly all live biomass. Aquaculture conversion removed 60% of soil carbon stock and 85% of live biomass carbon stock, relative to reference sites. By contrast, mangroves left to regenerate for more than 25 years reached the same level of biomass carbon compared to undisturbed forests, with annual biomass accumulation rates of 3.6 ± 1.1 Mg C ha?1 year?1. This study shows that hydrogeomorphic setting controls natural dynamics of mangrove blue carbon stocks, while long‐term land‐use changes affect carbon loss and gain to a substantial degree. Therefore, current land‐based climate policies must incorporate landscape and land‐use characteristics, and their related carbon management consequences, for more effective emissions reduction targets and restoration outcomes.  相似文献   
7.
The shallow marine and subaerial sedimentary and hydrothermal rocks of the ~3.48 billion‐year‐old Dresser Formation are host to some of Earth's oldest stromatolites and microbial remains. This study reports on texturally distinctive, spherulitic barite micro‐mineralization that occur in association with primary, autochthonous organic matter within exceptionally preserved, strongly sulfidized stromatolite samples obtained from drill cores. Spherulitic barite micro‐mineralization within the sulfidized stromatolites generally forms submicron‐scale aggregates that show gradations from hollow to densely crystallized, irregular to partially radiating crystalline interiors. Several barite micro‐spherulites show thin outer shells. Within stromatolites, barite micro‐spherulites are intimately associated with petrographically earliest dolomite and nano‐porous pyrite enriched in organic matter, the latter of which is a possible biosignature assemblage that hosts microbial remains. Barite spherulites are also observed within layered barite in proximity to stromatolite layers, where they are overgrown by compositionally distinct (Sr‐rich), coarsely crystalline barite that may have been sourced from hydrothermal veins at depth. Micro‐spherulitic barite, such as reported here, is not known from hydrothermal systems that exceed the upper temperature limit for life. Rather, barite with near‐identical morphology and micro‐texture is known from zones of high bio‐productivity under low‐temperature conditions in the modern oceans, where microbial activity and/or organic matter of degrading biomass controls the formation of spherulitic aggregates. Hence, the presence of micro‐spherulitic barite in the organic matter‐bearing Dresser Formation sulfidized stromatolites lend further support for a biogenic origin of these unusual, exceptionally well‐preserved, and very ancient microbialites.  相似文献   
8.
9.
Cellular and Molecular Neurobiology - Stopping opioid medications can result in a debilitating withdrawal syndrome in chronic users. Opioid withdrawal can occur at all ages, but...  相似文献   
10.
The intestinal microbiota is a microbial ecosystem of crucial importance to human health. Understanding how the microbiota confers resistance against enteric pathogens and how antibiotics disrupt that resistance is key to the prevention and cure of intestinal infections. We present a novel method to infer microbial community ecology directly from time-resolved metagenomics. This method extends generalized Lotka–Volterra dynamics to account for external perturbations. Data from recent experiments on antibiotic-mediated Clostridium difficile infection is analyzed to quantify microbial interactions, commensal-pathogen interactions, and the effect of the antibiotic on the community. Stability analysis reveals that the microbiota is intrinsically stable, explaining how antibiotic perturbations and C. difficile inoculation can produce catastrophic shifts that persist even after removal of the perturbations. Importantly, the analysis suggests a subnetwork of bacterial groups implicated in protection against C. difficile. Due to its generality, our method can be applied to any high-resolution ecological time-series data to infer community structure and response to external stimuli.  相似文献   
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