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41.
干旱区绿洲荒漠交错带土地退化及生态重建 总被引:20,自引:15,他引:20
由于经济的发展,土地资源受到越来越大的压力。当这种压力超过了土地资源的承载能力,就导致了土地退化的发生。作为陆地生态系统的基础,土地资源的退化表现为:土壤肥力降低,生物多样性降低,以及伴随的经济发展的落后。当前世界范围内对土地退化的治理,基本方法仍是基于生态学理论的生物方法。但对土地退化的恢复与生态系统的重建的研究,需要经过谨慎设计的长期实验。绿洲荒漠交错带的重要性,不仅表现为是绿洲的保护屏障,而且在绿洲经济的发展中也起到巨大的作用。通过对国内外大量研究的回顾,讨论了在不同地区进行的长期实验所采用的方法。有人为因素参与的退化土地恢复与生态重建,可以在短期内取得明显效果。产生土地退化的原因,不仅仅是土地资源特点与自然环境这样一些自然因素,还包括一些社会与经济因素。因此退化土地的恢复与生态重建的成功,需要一种考虑自然、社会和经济因素的综合的方法。 相似文献
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AIM:To investigate the effect of metallothionein(MT) on proliferation of rat vascular smooth muscle cells (VSMCs) stimulated by homocysteine and its mechanism. METHODS:VSMCs proliferation was measured by [3-H]-TdR incorporation, mitogen-activated protein kinase(MAPK)activity were determined by immunoprecipitation method, the intracellular contents of MT and malondialdehyde (MDA)were assayed by -hemoglobin saturation method and TBA reaction, respectively, and lactate dehydrogenase (LDH) leakage was measured by NADH oxidation. RESULTS:Hcy(10-6-10-4 mmol/L) stimulated [3-H]-TdR incorporation by the VSMCs in a concentration-dependent manner. Compared with control, [3-H]-TdR incorporation in VSMCs treated with 0.1 mmol/L Hcy was increased by 4.2 fold (P<0.01). Meanwhile, Hcy enhanced MAPK activity, MDA formation and LDH release (P<0.01)in a concentration-dependent manner. Treatment of VSMCs with MT alone did not change above parameters, compared with control. However, MT (10-6-10-4 mol/L)attenuated significantly Hcy-stimulated proliferation of VSMCs (P<0.01)in a concentration-dependent manner. And MT inhibited obviously Hcy-induced activation of MAPK activity, MDA formation and LDH release. Preincubation of VSMCs with 0.5 mmol/L ZnCl2 for 6 h induced an increase cellular MT content by 5.7-fold (P<0.01). The MT-overexpressed VSMCs resisted Hcy-stimulating action on MAPK activity, MDA formation and LDH leakage (P<0.01). CONCLUSION:These results show that MT has an inhibitory effect on Hcy-induced VSMCs proliferation, and that MT could inhibit Hcy-stimulated MAPK activity and lipid peroxidation. 相似文献
44.
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. 相似文献
45.
CHEN Ya-hong ZHAO Ming-wu FU Min-gui YAO Wan-zhen WANG Xiao-hong WANG Jian-li TANG Chao-shu 《园艺学报》2002,18(2):157-160
AIM:To investigate the role of calcineurin (CaN) in airway remodeling in guinea pig model of asthma.METHODS:Male guinea pigs were randomly divided into three groups: control, asthma group and CsA group. The following parameters were measured: 1. The protein content, cell count and differential count of BALF; 2. The amount of [3H]-TdR incorporation into central airway smooth muscle; 3. The mean thickness of airway wall and airway smooth muscle of small airwaysl; 4.CaN activity of trachea and lung tissue.RESULTS:1. The protein content, cell count and eosinophil of BALF in CsA group were 46%, 51% and 60% lower than those in asthma group, respectively (P<0.01); 2. [3H]-TdR incorporation in CsA group was 22% lower than that in asthma group (P<0.05);3. The mean thickness of airway wall and airway smooth muscle were 34% and 37% less in CsA group than those in asthma group, respectively (P<0.01); 4. CaN activity of lung tissue and trachea were 52% and 44% lower in CsA group than those in asthma group, respectively (P<0.01).CONCLUSION:CsA reduced airway remodeling in guinea pig model of asthma, indicating the role of CaN in the airway remodeling. 相似文献
46.
AIM: To prepare gfp-bcl-XL-contained recombinant adenovirus(rAd-gfp-bcl-XL).METHODS: Bcl-XL gene was amplified from pEGFP-C3-bcl-XL, subcloned into shuttle plasmid and formed transfer plasmid of pAdTrack-CMV-bcl-XL. Then pAdTrack-CMV-bcl-XL was linealinzed with PmeI and co-transformed into BJ5183 bacteria with adenovirus genomic plasmid of pAdEasy-1. The identified recombinant adenovirus plasmid was digested with PacI and transfected into 293 cells to package recombinant adenovirus particles. The target gene was detected by PCR.RESULTS: There were about 35% positive recombinant bacterial clones after the co-transformation of pAdTrack-CMV-bcl-XL and pAdEasy-1 into BJ5183. Recombinant adenovirus particle were produced and further amplified after the transfection of pAdEasy-1-gfp-bcl-XL into 293 cells. PCR test indicated that the recombinant Ad contained bcl-XL gene. The titer of the purified rAd-gfp-bcl-XL was 6.5×1012 PFU/L. CONCLUSIONS: The homologous recombination in bacteria is a convenient and high efficient method to prepare rAd-gfp-bcl-XL. This affords a good gene transfer vector for the gene therapy in human’s diseases. 相似文献
47.
REN Yu-sheng WU Zong-gui CUI Fang JIA Guo-liang YU Shi-qing TANG Chao-wu LI Bo 《园艺学报》2002,18(11):1377-1380
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. 相似文献
48.
TANG Yi-da YANG Yue-jin RUAN Ying-mao LI Yong-li ZHOU Yan-wen TIAN Yi GAO Run-lin CHEN Ji-lin CHEN Zai-jia 《园艺学报》2002,18(9):1115-1118
AIM:To compare the effects of carvedilol, cilazapril and their combination on left ventricular remodeling(LVRM) after acute myocardial infarction(AMI) in rats. METHODS: Twenty-four hours after AMI operation, 100 surviving rats were randomly assigned to: ①AMI control(n= 25), ②AMI+carvedilol(1 mg·kg-1 ·d-1, n= 25)(C1), ③AMI+cilazapril(1 mg·kg-1 ·d-1, n= 25)(Z1), and ④ AMI+combination(n= 25) groups. Sham-operated group(n= 17) were selected randomly. After 4 weeks of therapy with the drugs gastric gavage, hemodynamic and pathological studies were performed. RESULTS: There were no significant differences in MI size among the four AMI groups(all P> 0.05) Left ventricular(LV) end diastolic pressure(LVEDP), volume(LVV), weight(LVW) and septal thickness(STh) were all higher and left ventricular pressure maximal rate of rise and fall(±d p /d t) were lower(all P< 0.01) in AMI group than sham-operated group. The LVEDP, LVV, LVW and STh were all lower and ±dp /dt were higher in Z1, C1, and combination groups than those in AMI group(P< 0.05, P< 0.01), with LVEDP and STh were more lower in the combination group than in the two monotherapy group(P< 0.05, P< 0.01), but there were no significant differences in other variables among the three therapy groups. CONCLUSION: Carvedilol, cilazapril and their combination all can prevent from LVRM after AMI in rats, improve hemodynamics and LV function, with the combination superior. 相似文献
49.
ZHANG Yu-xia YU Lun-yin LIU Ming-qiu ZHANG Zheng-bin TANG Zhi-jiao XIA Dong WANG Ming 《园艺学报》2002,18(1):32-35
AIM:To investigate the protein expression of cyclin D2 and p16 in proliferation and differentiation of cultured cardiac myocytes.METHODS:One-day-old Sparague-Dawley rats were used. Cardiac myocytes(CM) were collected by a trypsin-dispersal method and cultured. Cell growth line and fluorescence activated cell sorting (FACS) were used to investigate the proliferation of CM. Ultra-thin sections were made to observe the ultrastructure of CM under transmission electron microscope. The expression of cyclin D2 and p16 in CM were measured using immunocytochemistry and image analysis.RESULTS:①Results of cell growth line and FACS analysis showed that cultured CM could proliferate in the first 3 cultured days, but the ability decreased quickly, concomitant with differentiation. CM was obseved quiescent in cell cycle three days later. The ultrastructure of CM showed the large amount of myofilaments and mitochondrion. ②The protein expression of cyclin D2 in 3,4,5 day CM group was 0.89 times(P<0.05),0.80 times (P<0.05) and 0.56 times (P<0.01) of that in 1 day group, respectively. The expression of p16 in CM was increased during the culture process, 2,3,4,5 day group were 1.63 times, 1.72 times, 1.99 times and 2.84 times (P<0.01) of that in 1 day group, respectively.CONCLUSION:Cultured neonatal rat cardiac myocytes could proliferate during the first 3 days after incubation, but the ability of proliferation decreased, from the fourth day, concomitant with differentiation. Cyclin D2 and p16 play the key roles in CM postnatal development. Downregulation of cyclin D2 and upregulation of p16 may induce CM differentiation. 相似文献
50.