刺激皮肤感受野对大鼠多觉型伤害性感受器诱发放电的影响

在大鼠尾部,重复压力刺激皮肤感受野,当间隔时间小于2min时,多觉型伤害性感受器的单位放电数随间隔时间的缩短而减少。压力与辐射热交叉刺激同一感受野,随后刺激的放电数也显著减少。皮下注射致痛剂引起持续性放电的背景上,分别向感受野施加按压、辐射热或电针刺激,随着放电增多后出现一个放电减少的过程。刺激支配尾部的交感神经则使减少的放电显著增多。结果表明,多觉型伤害性感受器受到刺激兴奋后有个感受性降低的过程。本文讨论了这一过程在按摩、针灸缓解痛机制中的可能作用。     

AFLP─一种DNA分子标记新技术

AFLP──ANovelTechniqueforDNAMolecularMarkerWengYuejin(InstituteofCropGermplasmResourees,ChineseAcademyofAgriculturalSciences,Beijing100081)公司科学家ZabeauMarc和VosPieter发明创建的一种DNA分子标记新技术,它不仅具备了其它DNA分子标记技术所具有的特点,多态性丰富,共显性表达,不受环境影响,无复等位效应,而且还具有带组丰富,用样量少,灵敏度高,快速高效等特殊优点．一个0．5mgDNA样品,可做4000个反应,获得8万个标记,650万条带纹。美国加利福尼亚大学MackillDavid[7]利用14份水稻为材料,比较AF…     

贝氏隐孢子虫在珍珠鸡体内发育的扫描电镜观察

采用扫描电镜观察了贝氏隐孢子虫在珍珠鸡体内的发育。大量球形虫体镶嵌于气管和法氏囊微绒毛丛中。气管纤毛消失,微绒毛生发生融合。法氏囊粘膜表面可观察到宿主细胞突起,在突起的表面有数个虫体寄生。滋养体呈球状,平均大小为１．７μｍ。裂殖体拥有４个或８个香蕉状裂殖子。成熟大配子体大小为 ４.２ × ３．３μｍ,在其侧面可观察到锯齿状突起。偶尔能观察到卵囊,其表 面有一明显裂缝。虫体逸出后所留下的带虫空泡似弹坑状,根据其结构可将其分为两类,其中一类为裂殖子或小配子的形成场所,另一类为卵囊的形成场所。     

石墨烯对植物的生理毒性效应研究进展

石墨烯是当前研究最热的碳纳米材料,具有独特的理化特性,在各领域广泛应用。随着石墨烯生产和使用量的不断增大,其不可避免地进入到环境中,给生态环境和人类健康带来风险。阐明石墨烯的潜在毒性效应及其作用机制对于客观评价石墨烯的生态环境健康风险具有重要意义。迄今为止,已有诸多研究报道了石墨烯的植物生理毒理效应。研究表明,石墨烯对植物的生理学响应及其生理变化过程存在影响,涉及萌芽、幼苗生长、氧化应激、光合特性、植物激素和代谢过程等,且多呈浓度效应。今后亟需构建一套被广泛认可的植物石墨烯毒性评价体系,为石墨烯的安全生产和使用提供指导。     

Bone marrow-derived mesenchymal stem cells improve post-ischemia neurological function in rats via the PI3K/AKT/GSK-3β/CRMP-2 pathway

Background: Transplantation of bone marrow-derived mesenchymal stem cells (BMSCs) is a potential therapy for cerebral ischemia. However, the underlying protective mechanism remains undetermined. Here, we tested the hypothesis that transplantation of BMSCs via intravenous injection can alleviate neurological functional deficits through activating PI3K/AKT signaling pathway after cerebral ischemia in rats.

Methods: A cerebral ischemic rat model was established by the 2 h middle cerebral artery occlusion (MCAO). Twenty-four hours later, BMSCs (1?×?10⁶ in 1 ml PBS) from SD rats were injected into the tail vein. Neurological function was evaluated by modified neurological severity score (mNSS) and modified adhesive removal test before and on d1, d3, d7, d10 and d14 after MCAO. Protein expressions of AKT, GSK-3β, CRMP-2 and GAP-43 were detected by Western-bolt. NF-200 was detected by immunofluorescence.

Results: BMSCs transplantation did not only significantly improve the mNSS score and the adhesive-removal somatosensory test after MCAO, but also increase the density of NF-200 and the expression of p-AKT, pGSK-3β and GAP-43, while decrease the expression of pCRMP-2. Meanwhile, these effects can be suppressed by LY294002, a specific inhibitor of PI3K/AKT.

Conclusion: These data suggest that transplantation of BMSCs could promote axon growth and neurological deficit recovery after MCAO, which was associated with activation of PI3K/AKT /GSK-3β/CRMP-2 signaling pathway.

     

Consumer-driven nutrient release to the water by a small omnivorous fish enhanced ramet production but reduced the growth rate of the submerged macrophyte Vallisneria denseserrulata (Makino) Makino

Small fish are highly associated with submerged macrophytes but may potentially hamper their growth due to nutrient excretion that stimulate growth of phytoplankton and periphyton growth. We conducted a mesocosm experiment to elucidate the effects of the small omnivore Chinese bitterling Acheilognathus macropterus on the growth of phytoplankton, periphyton and the submerged macrophyte Vallisneria denseserrulata. The treatments were fishless as well as low (LF) and high (HF) fish density. We found that the concentrations of nutrients and the phytoplankton biomass increased substantially in both fish treatments, leading to a significantly higher light attenuation compared with the control. Moreover, bitterling substantially enhanced the biomass of periphyton on plant leaves. Consequently, the relative growth rate (RGR) of V. denseserrulata was significantly suppressed in HF, while RGR in the LF treatment did not differ significantly from the controls. However, the bitterling also stimulated the ramet production of V. denseserrulata, significantly. Our results indicate that Chinese bitterling reduce the RGR of V. denseserrulata under high fish density condition. Therefore, the density of Chinese bitterling should be kept low in order to reduce the negative effects of the fish on the RGR of submerged macrophytes (e.g. V. denseserrulata), when restoring lakes by plant transplantation.

     

100%枸杞汁对递增负荷运动期间机体HPA轴及血糖调节的影响*

目的: 观察在递增负荷运动期间饮用100%枸杞汁对男大学生血清促肾上腺皮质激素(ACTH)、皮质醇(C)、胰岛素(INS)、胰高血糖素(PG)和血糖(Glu)变化,探讨100%枸杞汁在递增负荷运动期间对机体下丘脑-垂体-肾上腺(HPA)轴应激和血糖调节的作用。方法: 将28名健康男性大学生随机分为对照组(C组,16人)和实验组(E组,12人),所有受试者进行为期32 d、4个阶段的递增负荷运动,运动期间E组每人每天睡前饮用100 ml 100%枸杞汁。在实验前和每阶段结束后次日晨采用血糖仪测试受试者Glu及ELISA法测试血清ACTH、C、INS、PG。结果: ①与运动前相比,递增负荷运动期间两组受试者血清ACTH浓度均在第1、2阶段下降后,第3、4阶段持续升高(P＜0.01),且E组稍高于C组;②递增负荷运动期间受试者血清C呈持续下降趋势,E组第4阶段末显著低于对照组(P＜0.05);③递增负荷运动期间受试者血清INS水平先上升再下降,第4阶段末C组的浓度下降明显(P＜0.05);④实验末期E组血清PG显著降低(P＜0.05);⑤实验后期受试者Glu浓度下降,C组的Glu浓度下降趋势明显(P＜0.05)。结论: 100%枸杞汁可改善递增负荷期间机体HPA轴功能,提高机体对大负荷的应激能力,并调节机体血糖平衡。     

IgA肾病患者与健康人肠道菌群的比较

目的通过16S rRNA高通量基因测序方法对IgA肾病患者与健康人的肠道菌群进行比较。方法纳入生活于同一地区的40例IgA肾病患者与10例健康人,收集研究对象的新鲜粪便样本,提取粪便细菌总DNA,通过PCR扩增后上机测序,然后进行可操作分类单元聚类、物种分类分析及Alpha多样性分析、Beta多样性分析,最后比较两组之间的肠道菌群差异。结果与健康人相比,IgA肾病患者肠道菌群丰富度指数(Ace、Chao1)下降(u=2.308,P=0.033;u=2.259,P=0.039),多样性指数(Shannon、Simpson)升高(u=5.370,P0.001;u=4.601,P=0.007);相对丰度方面,IgA肾病患者的厚壁菌门、拟杆菌门、放线菌门细菌数量增加(t=2.301,P=0.037;t=6.729,P=0.005;t=5.285,P=0.006),而变形菌门细菌数量减少(t=4.138,P=0.009);拟杆菌属、链球菌属细菌数量增加(t=9.037,P=0.003;t=6.001,P=0.008),而unidentified_Enterobacteriaceae数量减少(t=2.198,P=0.033)。PCoA图提示两组肠道菌群有显著差异。LDA差异贡献分析发现两组之间共有15个物种存在显著差异,其中造成显著差异影响力最大的5个物种依次是γ-变形菌纲、unidentified_Enterobacteriaceae、肠杆菌科、肠杆菌目、变形菌门(t=9.930,P=0.002;t=2.198,P=0.033;t=2.604,P=0.015;t=2.393,P=0.021;t=4.138,P=0.009),它们刚好落在同一个进化树上,在IgA肾病组的相对丰度显著降低。结论 IgA肾病患者存在肠道菌群失调,显著减少的肠杆菌科的未知属可能是IgA肾病的特征菌,其对机体免疫的影响及在IgA肾病发生发展中的作用尚不清楚,进一步研究可能为IgA肾病的防治提供新的靶点。