黑河流域荒漠地区梭梭人工林地土壤水分动态研究

梭梭林地土壤剖面的含水量与裸沙地含水量显著不同 ,裸沙地土壤含水量随深度增加而增加 ,林地在 30～ 12 0cm范围内有较高的含水量 ;林地 0～ 30cm的上层土壤含水量受降雨及蒸发的剧烈影响 ,30～ 2 0 0cm范围内的林地土壤各测量层平均含水量与其标准差有二次函数的关系 ;降雨对每月的 0～ 2 0 0cm的土壤贮水量没有明显的影响 ,说明降雨多数在当月就被蒸散和深层渗漏所消耗 ;认为梭梭人工林这种脆弱生态系统能够在严酷的环境条件下存在 ,其根系对土壤水和地下水有吸水和释水的再分配功能是重要的因素之一     

乡村生态学研究的尺度与等级特征

乡村生态学 ( Village ecology)的尺度和等级特征依赖一定空间区域 ,不同尺度所研究村落的特征也不尽相同 ,空间尺度的大小很大程度上决定于所研究村落的复杂性、稳定性及特征。在特定的空间尺度下 ,乡村的组成要素随着时间尺度的变化而变化 ,但变化速率受空间尺度大小的制约。乡村生态学研究具有等级结构 ,空间尺度决定所研究单元的等级位置。行政村 (中心村 )和自然村 (自然屯 )是乡村生态学研究的基本尺度     

麦蚜对吡虫啉的敏感性及吡虫啉有效用量的评价

室内测定结果表明 ,禾谷缢管蚜对吡虫啉的敏感性比麦长管蚜高 ,其LC₅₀之比为1∶3左右。田间试验结果明确 ,吡虫啉持效性好 ,其持效期与吡虫啉用量和麦蚜种类有关。小麦穗蚜发生始盛期是吡虫啉防治麦蚜的最佳时期 ,防治禾谷缢管蚜最佳有效用药量为1g/667m²,麦长管蚜为2g/667m²。     

水稻与稻瘟病菌非亲和性互作中重要防御酶活性变化规律研究

 选以CO39为背景的水稻抗稻瘟病近等基因系,与稻瘟菌生理小种ZC₁₃(菌株97-151a)组成的3类典型非亲和性互作,以亲和性互作为对照,对各互作中过氧化物酶(POD)、苯丙氨酸解氨酶(PAL)、几丁质酶及β-1,3-葡聚糖酶的活性变化规律进行了系统研究。完全非亲和性互作C101A51/97-151a、高度非亲和性互作C101L AC/97-151a及中度非亲和性互作C104 PKT/97-151a,POD比活性接种后即开始明显升高,48h前达到高峰,升高趋势一直持续到7d完全显症时,幅度基本与各互作非亲和程度呈正相关;亲和性互作CO39/97-151a接种后40 h POD比活性才开始升高,4~6 d达到高峰,峰值也较大。3类非亲和性互作PAL比活性在接种后0 h或16 h开始较明显升高,整个互作中形成3~4个较明显的峰;亲和性互作中PAL比活性一直明显下降。3类非亲和性互作外切几丁质酶比活性接种后即开始升高,基本一直保持升高趋势,在40 h前幅度较大,并形成1~3个较高的峰;亲和性互作外切几丁质酶比活性接种后即开始大幅度升高直至完全显症,48h后幅度远高于非亲和性互作。3类非亲和性互作β-1,3-葡聚糖酶比活性在24 h内开始较明显升高,在48h前形成2~3个较明显的峰;亲和性互作在接种后β-1,3-葡聚糖酶比活性即开始升高,在48h后显著高于非亲和性互作。讨论了POD、PAL、几丁质酶及β-1,3-葡聚糖酶参与水稻抗稻瘟病的可能性。     

Changes of K+ channels of outer hair cells in guinea pig cochlea with streptomycin ototoxicity

AIM:To study the changes of K⁺ channels of outer hair cells in guinea pig cochlea with streptomycin ototoxicity. METHODS:Auditory brainstem responses (ABR) and whole-cell patch clamp techniques were used.RESULTS:(1) The body weight of guinea pigs with streptomycin ototoxicity decreased significantly; (2) The ABR threshold markedly increased in streptomycin group (Ⅱ,Ⅲ);(3)The number of dissociated outer hair cells of guinea pigs (Ⅱ,Ⅲ) was lower than that of control (Ⅰ); (4) Streptomycin decreased the Ca²⁺-sensitive K⁺ currents and delayed outward K⁺ currents distinctly; (5) There was no significant difference of K⁺ currents between Ⅰ and Ⅱ/Ⅲ. CONCLUSION:These results suggest that the inhibition of K⁺ channels is the basis of streptomycin ototoxicity, but not the direct reason for cell death.     

Role of angiotensin II and angiotensin II receptors in vascular smooth muscle cells migration

AIM:To determine the effects of Angiotensin II(AngII) on migration of rat smooth muscle cells and to investigate the mechanisms underlying Ang II action in the development of injured vascular disease. METHODS:VSMCs isolated from aortic media of Wistar rats and cultured by the modified explant method were adopted. In prersence and absence of AngII, the expression of AngII receptor and reorganization of the actin cytoskeleton of VSMCs were studied by immunocytochemistry technique, fluorocytochemistry technique. The migration assays were performed by a modified Boyden's chamber. And the effects of AT₁R antagonist (CV-11974), AT₂R antagonist (PD123319) on aforementioned target were studied.RESULTS:VSMCs migration was stimulated by addition of AngII. The dynamic reorganization of actin cytoskeleton may be an important mechanism by which AngII facilitates VSMC motility. The expression of AT₁R in VSMCs can be upregulated after treatment with AngII initially, then decreased gradually. The expression of AT₁R was downregulated by AT₁R antagonist. The effect of AngII on VSMCs migration was mediated by AT₁R, while AT₂R had no significant effect.CONCLUSION:The dynamic reorganization of actin cytoskeleton is required for AngII-induced VSMC migration, and this effect is mediated by AT₁R .     

Effects of external counterpulsation on renin-angiotensin system and hemodynamics in dogs with myocardial ischemia

AIM:To examine the effect of external counterpulsation(ECP) on renin-angiotensin system(RAS) and hemodynamics in dogs with myocardial ischemia and their relationship. METHODS:Acute myocardial ischemia was induced by occluding the left anterior descending of the dogs. The local renin activity, angiotensin Ⅱ(AngⅡ) level, angiotension-converting enzyme(ACE) activity were tested by biochemical methods and hemodynamics was recorded by a 8-channel physiological recorder.RESULTS:Ischemia could actiivate renin,ACE and AngⅡ in cardiovasculature and ECP reduced them except for renin in ischemic myocardium. Ischemia also could activate RAS in lung and kidney, which play an important role on circulating RAS, and ECP reduced them. Furthermore, ECP could improve hemodynamics and there existed a close relationship between local AngⅡlevel and hemodynamics. CONCLUSION:ECP can reduce local RAS and improve hemodynamics in dogs with myocardial ischemia, which might be one of mechanisms underlying the protective effect of ECP on ischemic myocardium.     

Effect of Jiawei Sini Decoction on glucocorticoid receptor in thymocytes of chronic psychological stress rats

AIM: To observe the effect of Jiawei Sini Decoction (JWSND) on glucocorticoid receptor (GCR) in thymocytes of chronic psychological stress rats. METHODS: The rats were randomly divided into 4 groups, control group (C), model group (M), group treated by JWSND C₁, group treated by ginsenosides C₂. The number of thymocyte GCR sites and the GCR nuclear thanslocation rate were detected by radioimmunoassay. RESULTS: Compared with the control group, in the model group, the thymocyte weight index lowered significantly ( P<0.05 ), and the GCR nuclear thanslocation rate was increased significantly ( P<0.01 ), but the number of thymocyte GCR sites was unchanged. Compared with the model group, thymus gland weight indexes of C₁ and C₂ were increased significantly ( P<0.05 ), while the GCR nuclear thanslocation rate lowered significantly ( P<0.01 ). Moreover, no significant difference was found in all indexes between C₁ and control group. CONCLUSION: The inhibitory effect of glucocorticoid on the thymus could be significantly reversed by JWSND via suppressing the thanslocation of GCR from cytoplasm to nucleus in chronic psychological stress rats.     

Effects of platelet-derived growth factor on DNA and collagen protein synthesis in human vascular fibroblasts

AIM: To investigate the effects of platelet-derived growth factor on DNA and collagen protein synthesis in human vascular fibroblasts. METHODS: In the present experiment, the human vascular fibroblasts were cultured and effects of platelet-derived growth factor-BB on DNA and collagen protein synthesis in human vascular fibroblasts were observed by using [³H]-TdR incorporation and [³H]-proline incorporation in vitro. RESULTS: Platelet-derived growth factor-BB significantly promoted NDA synthesis and collagen protein synthesis of quiescent human vascular fibroblasts, with a maximal response at a concentration of 30μg·L^-1at 24 h and 36 h, respectively. CONCLUSION: Platelet-derived growth factor-BB promotes DNA and collagen protein synthesis in cultured human vascular fibroblasts.     

西瓜新品种‘红冠龙’

 ‘红冠龙’为中熟西瓜一代杂种, 全生育期100 d 左右, 果实椭圆形, 平均单瓜质量8 kg 以上, 瓤红色, 可溶性固形物含量12. 2 %, 高抗枯萎病、炭疽病, 抗旱耐湿性均佳, 适合全国主要西瓜产区种植。