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1.
土壤健康的生物学表征与调控   总被引:5,自引:0,他引:5  
如何有效判定土壤健康状态是实现农业绿色发展的基本问题。在现有的土壤健康评价体系中,很少考虑土壤生物在维持土壤健康方面的作用。基于此,本文论述了土壤健康的内涵,从土壤生物健康的角度,总结了土壤健康的生物学表征指标,阐述了土壤微生物、土壤酶活性、土壤微食物网及蚯蚓对土壤健康的指示作用。基于上述生物指标,从作物和土壤管理等方面探讨了不同农田管理措施对土壤健康状况的调控途径,并对土壤生物健康的未来发展趋势进行了展望。本文旨在增强科学家和决策者对维护土壤生物健康的认识,充分发挥土壤生物在生态系统服务中的重要作用。  相似文献   

2.
转苏云金杆菌杀虫蛋白(Bt)基因作物的商品化种植可能对土壤生态系统产生不利影响是近10年来颇有争议的问题.转Bt基因作物可通过多种方式向土壤中释放苏云金杆菌杀虫蛋白即Bt蛋白,从而引起土壤生物和生态系统基本功能的变化;蚯蚓可加快动植物残体的降解,促进有机质的分解和矿化,与其他土壤生物相比,蚯蚓对某些污染物更敏感.本文从研究中用到的蚯蚓种类、采用的实验方式、研究的科学问题等方面综述了转Bt基因作物对土壤动物蚯蚓影响的研究进展,并对转Bt基因作物对土壤动物蚯蚓影响研究的发展趋势进行了展望,旨在为转Bt基因作物对非靶标土壤动物的影响提供参考,进而为全面评价转Bt基因作物对土壤生态系统的影响提供依据.  相似文献   

3.
蚯蚓调控土壤微生态缓解连作障碍的作用机制   总被引:1,自引:0,他引:1  
连作障碍不仅严重影响作物产量,而且会导致土壤生物多样性下降、有益微生物减少及病原菌增加等一系列微生态失衡问题。土壤微生态失衡反作用于植物,导致植物发生更严重的病害、减产等。作为土壤生态系统工程师,蚯蚓的取食、掘洞和爬行等活动对土壤微生态具有重要的调控作用,既可以改善土壤环境,又可以强化土壤生物群落功能,有望为缓解作物的连作障碍问题提供一条新途径。本文总结了土壤微生态与土壤功能维持及蚯蚓调控土壤生物作用的研究进展,在此基础上,结合蚯蚓对化感物质降解作用的研究,分析了蚯蚓通过调控土壤微生态缓解作物连作障碍的微生物作用机制的三条途径:直接调控微生物群落、通过改变化感物质组成以及通过调控土壤动物区系调控微生物群落。蚯蚓对微生物群落的调控可改善失衡的土壤根际微生态,有效缓解作物连作障碍。  相似文献   

4.
土壤生物及其对土壤生态学发展的影响   总被引:60,自引:11,他引:49  
土壤生物区系、土壤生物多样性和全球变化已成为土壤生态学研究的肖沿领域,土壤生物以不同的方式改变着土壤的物理、化学和生物学特性,某一等级层次上的土壤生物群落的组成和结构可以对其它等级层次上的资源空间异质性产生影响,而这种空间异质性受到许多生物圈层--土壤功能区域所维持。本文评价了土壤生物区系在土壤生态系统过程中的作用,论述了土壤生物多样性与生态系统功能的关系,讨论了土壤生态系统对全球变化的影响。  相似文献   

5.
蚯蚓生态毒理试验现状与发展趋势   总被引:8,自引:0,他引:8  
蚯蚓是土壤污染状况的重要指示生物之一。近年来,蚯蚓生态毒理试验广泛应用于污染土壤的质量评价,其试验方法及评价指标日趋完善。本文从个体、种群、群落和"模式"生态系统4个水平上,综述了蚯蚓毒理试验方法及评价指标的国内外研究现状及进展。重点介绍了急性试验、慢性试验、污染物复合试验、蚯蚓种间及与其它物种的比较试验,并从形态变化、生理观测和病理观察方面概括了试验评价指标。探讨了不同水平上各毒性试验的优缺点,并指出了结合多种试验进行土壤质量生态评价的实际意义。  相似文献   

6.
有机磷农药对土壤动物毒性的影响研究   总被引:16,自引:2,他引:14  
有机磷农药对土壤动物毒性影响的试验结果表明,土壤动物对农药毒性反应敏感,4种有机磷农药处理组的动物种类和数量明显减少,动物种类的减少主要是常见种和稀有种类,动物数量变化则主要是优势类群的数量消长,毒性毒理试验表明,农药对大型土壤动物蚯蚓有明显致死效应,并对蚯蚓,鞘翅目幼虫和等足类鼠妇虫等大型动物的呼吸强度有显著抑制作用,其呼吸代谢强度随着农药处理浓度增加与染毒历时的延长而迅速减弱。  相似文献   

7.
CO_2倍增对植物生长和土壤微生物生物量碳、氮的影响   总被引:8,自引:0,他引:8  
关于大气CO2浓度倍增(即为700μmolCO2·mol-1空气)将对植物生长产生诸多影响,已有大量报道[1,2]。但CO2倍增对植物及所在土壤中微生物影响的研究甚少[3,4]。土壤微生物是陆地生态系统中最活跃的成分,担负着分解动植物残体的重要作用,...  相似文献   

8.
草地群落的土壤呼吸   总被引:56,自引:2,他引:54  
通过土壤呼吸作用向大气释放CO2是陆地生态系统碳循环的一个最主要的环节,也是人类活动影响下陆地生态系统对大气中CO2浓度产生影响,从而导致全球气候变化的关键生态学过程,因而成为全球碳循环研究中倍受关注的核心问题[33,37,38]。1土壤呼吸的测定方...  相似文献   

9.
生物多样性指一个区域、国家乃至整个地球多种多样活有机体(动物、植物和微生物)有规律地结合在一起的总称[1]。它包括生态系统多样性、物种多样性和遗传多样性。在生态学中,多样性或复杂性常指生态系统中相互作用的物种数量[2]。一般认为多样性导致生态系统的稳...  相似文献   

10.
土壤微生物PCR及分子杂交检测   总被引:6,自引:0,他引:6  
PCR技术在环境微生物的检测方面已得到越来越广泛的应用,Stefan等[1]利用PCR技术检测土壤中的转基因细菌,后来用于检测土壤中不可培养的微生物[2],跟踪环境中的特定细菌或DNA[3],揭示土壤生态系统的基因多样性[4]等。利用PCR技术来检测…  相似文献   

11.
Preparations, XPS and electronic spectroscopy, and magnetism of seven new one-dimensional cyano-bridged coordination polymers, chiral [Cu(RR-chxn)2][Pd(CN)4] · 2H2O (1), [Cu(trans-chxn)2][M(CN)4] · 2H2O (2, 4, and 6 for M = Pd, Ni, and Pt), and [Cu(cis-chxn)2][M(CN)4] · 2H2O (3, 5, and 7 for M = Pd, Ni, and Pt) (RR-chxn = cyclohexane-(1R,2R)-diamine, trans-chxn = racemic trans-cyclohexane-(1,2)-diamine, and cis-chxn = racemic cis-cyclohexane-(1,2)-diamine) have been reported in view of tuning of their electronic properties by stereochemistry of chxn ligands and metal-substitution. Comparison of Cu 2p1/2 and 2p3/2 peaks of XPS and broad d-d bands around 18 000 cm−1 of electronic spectra are described systematically for 1-7. Variable-temperature magnetic measurement shows that complexes 1-7 indicate weak antiferromagnetic interactions via cyano-bridges. Because of semi-coordination coupled with pseudo Jahn-Teller elongation and electrostatic interaction for 1, the axial Cu-N coordination bond distances of 2.330(7) and 3.092(8) Å are considerably longer than those of equatorial ones in the range from 2.016(6) to 2.030(6) Å. The former bond distances of 1 are intermediate values among the related Ni (2.324(6) and 3.120(8) Å) and Pt (2.34(1) and 3.09(1) Å) complexes.  相似文献   

12.
多马胺能药物对鲇鱼促性腺激素(GtH)分泌活动的影响   总被引:1,自引:0,他引:1  
以珠江流域鲇鱼(silurus asotus)为实验材料,研究了多巴胺(DA)能药物(DA及其D-2型受体拮抗物 ,DOM)对鲇鱼促性腺激素(GtH)释放的影响,结果表明,在性腺发育的各个时期,单独注射DOM(5ug/g)均不能显著提高鲇鱼血液基础GtH水平,当DOM与LHRH-A联合注射时能显著增强LHRH-A刺激GtH释放的作用;DA只能抑制GnRH诱导的GtH释放,对基础GtH释放无抑制作用,这种生殖内分泌调节方式与鲇形目的革胡子鲇(Clarias gariepinus)和大鳍Hu(Mystus macropterus)相似,而与鲤形目的鲁科(Cyrpindiae)鱼类不同。  相似文献   

13.
The aim of the study has been to determine and compare the influence upon the kidney antioxidative system, exercised by administration of vitamin E, and vitamin E in combination with methionine, under conditions of oxidative stress induced by sodium fluoride. The experiment was carried out on Wistar FL rats (adult males) that, for 35 days, were administered water, NaF, NaF with vitamin E, or vitamin E with methionine (doses: 10 mg NaF/kg of body mass/24 h, 3 mg vitamin E per 10 μl per rat for 24 h, 2 mg methionine per rat for 24 h). The influence of administered sodium fluoride and antioxidants upon the antioxidative system in kidney was examined by analyzing the concentration of malondialdehyde (MDA) and the activity of the most important antioxidative enzymes (SOD, total and both its isoenzymes, GPX, GST, GR, and CAT). The studies carried out confirmed the disadvantageous effect of the administered dose of NaF upon the antixodiative system in rats (increase in the concentration MDA, decrease activity of all antioxidative enzymes). The administration of vitamin E increased the activity of studied enzymes with the exception of glutathione reductase GR; it also reduced the procesess of lipid peroxidation. It has been found that combined doses of vitamin E and methionine were most effective in inhibiting lipid peroxidation processes. The results confirmed the antioxidative properties of methionine.  相似文献   

14.
Auxin-mediated elongation growth of isolated subapical coleoptile segments of maize (Zea mays L.) is controlled by the extensibility of the outer cell wall of the outer epidermis (Kutschera et al., 1987). Here we investigate the hypothesis that auxin controls the extensibility of this wall by changing the orientation of newly deposited microfibrils through a corresponding change in the orientation of cortical microtubules. On the basis of electron micrographs it is shown that cessation of growth after removal of the endogenous source of auxin is correlated with a relative increase of longitudinally orientated microfibrils and microtubules at the inner wall surface. Conversely, reinduction of growth by exogenous auxin is correlated with a relative increase of transversely orientated microfibrils and microtubules at the inner wall surface. These changes can be detected 30–60 min after the removal and addition of auxin, respectively. The functional significance of directional changes of newly desposited wall microfibrils for the control of elongation growth is discussed.  相似文献   

15.
Though the advancement of chemotherapy drugs alleviates the progress of cancer, long-term therapy with anticancer agents gradually leads to acquired multidrug resistance (MDR), which limits the survival outcomes in patients. It was shown that dihydromyricetin (DMY) could partly reverse MDR by suppressing P-glycoprotein (P-gp) and soluble resistance-related calcium-binding protein (SORCIN) independently. To reverse MDR more effectively, a new strategy was raised, that is, circumventing MDR by the coadministration of DMY and ondansetron (OND), a common antiemetic drug, during cancer chemotherapy. Meanwhile, the interior relation between P-gp and SORCIN was also revealed. The combination of DMY and OND strongly enhanced antiproliferative efficiency of adriamycin (ADR) because of the increasing accumulation of ADR in K562/ADR-resistant cell line. DMY could downregulate the expression of SORCIN and P-gp via the ERK/Akt pathways, whereas OND could not. In addition, it was proved that SORCIN suppressed ERK and Akt to inhibit P-gp by the silence of SORCIN, however, not vice versa. Finally, the combination of DMY, OND, and ADR led to G2/M cell cycle arrest and apoptosis via resuming P53 function and restraining relevant proteins expression. These fundamental findings provided a promising approach for further treatment of MDR.  相似文献   

16.
Structure and function of S-adenosylhomocysteine hydrolase   总被引:6,自引:0,他引:6  
In mammals, S-adenosylhomocysteine hydrolase (AdoHcyase) is the only known enzyme to catalyze the breakdown of S-adenosylhomocysteine (AdoHcy) to homocysteine and adenosine. AdoHcy is the product of all adenosylmethionine (AdoMet)-dependent biological transmethylations. These reactions have a wide range of products, and are common in all facets of biometabolism. As a product inhibitor, elevated levels of AdoHcy suppress AdoMet-dependent transmethylations. Thus, AdoHcyase is a regulator of biological transmethylation in general. The three-dimensional structure of AdoHcyase complexed with reduced nicotinamide adenine dinucleotide phosphate (NADH) and the inhibitor (1′R, 2′S, 3′R)-9-(2′,3′-dihyroxycyclopenten-1-yl)adenine (DHCeA) was solved by a combination of the crystallographic direct methods program, SnB, to determine the selenium atom substructure and by treating the multiwavelength anomalous diffraction data as a special case of multiple isomorphous replacement. The enzyme architecture resembles that observed for NAD-dependent dehydrogenases, with the catalytic domain and the cofactor binding domain each containing a modified Rossmann fold. The two domains form a deep active site cleft containing the cofactor and bound inhibitor molecule. A comparison of the inhibitor complex of the human enzyme and the structure of the rat enzyme, solved without inhibitor, suggests that a 17° rigid body movement of the catalytic domain occurs upon inhibitor/substrate binding.  相似文献   

17.
Tang SN  Huang JF 《FEBS letters》2005,579(6):1441-1445
There are two oligomeric types of glycyl-tRNA synthetases (GlyRSs) in genome, the alpha2beta2 tetramer and alpha2 dimer. Here, we showed that the anticodon-binding domains (ABDs) of dimeric and tetrameric GlyRSs are non-homologous, although their catalytic central domains (CCDs) are homologous. The dimeric GlyRS_ABD is fused to the C-terminal of CCD in alpha-subunit, but the tetrameric GlyRS_ABD is to the C-terminal in beta-subunit during evolution. Generally, one species only contains one oligomeric type of GlyRS, but the both oligomeric GlyRSs with the multiple homologous domains can be observed in Magnetospirillum magnetotacticum genome, nevertheless, these homologous domains are probably from different genomes.  相似文献   

18.
It was earlier hypothesized that the malarial parasite may convert precursors of folate analogues to synthesize de novo inhibitors toxic to itself, but not to the mammalian cell. It was suggested that one such analogue, 2,4-diamino-6-hydroxymethylpteridine (DAP) may be converted to aminopterin (AMP), a known dihydrofolate reductase inhibitor. In the present study, we evaluated the ability of DAP to inhibit proliferation of Plasmodium berghei NK65 in mice, with(out) folinic acid rescue. Cumulative dosages of DAP ranging from 0.1 to 20 mg/kg bw. administered either orally or intraperitoneally showed no suppression of parasite growth, or gave mild activities that were not statistically significant (P > 0.05). Our findings do not seem to support the hypothesis of selective de novo metabolism of DAP to AMP by the malarial parasite.  相似文献   

19.
The mitogenic responses of separated rabbit lymphocyte populations functionally analogous to mouse T and B cells have been tested in vitro. Purified T cells were prepared by passage over nylon wool (NW) and purified B cells prepared by treatment with antithymocyte serum and complement (ATS + C). ATS + C kills 70% of peripheral blood lymphocytes (PBL's) and 50% of the spleen cells while passage over NW yields 40% of the applied PBL's and 5–23% of the applied spleen cells. NW-purified T cells from the spleen or PBL's respond fully to concanavalin A (Con A) but have a reduced response to phytohemaglutinin (PHA) and little or no response to goat anti-rabbit immunoglobulin (anti-Ig). PBL's that survive ATS + C (B cells) are stimulated by anti-Ig but not by Con A or PHA. B cells purified from spleen do not respond to Con A or PHA but will respond to anti-Ig under appropriate conditions. A full spleen B-cell response to anti-Ig required removal of Ig produced by the cultures that blocked anti-Ig stimulation. It is concluded that, for rabbit lymphocytes, Con A and PHA are primarily T-cell mitogens and that anti-Ig is primarily a B-cell mitogen. However, the mitogen response of unfractionated PBL or spleen cell populations indicates an overlap in reactivity. This could be due to cells sharing T and B properties, alteration of cell populations by the fractionation procedures used, or recruitment of one population in the presence of a mitogenic response of the other population.  相似文献   

20.
围隔藻类水华演替过程中二甲基硫化物的含量动态   总被引:3,自引:0,他引:3  
李猛  袁东星  汤坤贤 《生态学报》2007,27(12):5308-5317
于2005年6月至7月,研究了海洋围隔不同藻类水华演替过程中二甲基硫化物的含量动态,并考察了相关环境参数对二甲基硫化物含量的影响。2个围隔实验组均出现未知藻水华-硅藻水华-甲藻水华的演替过程,这3次不同藻类水华分别对应了二甲基硫化物含量的3次高峰,表明藻类水华对二甲基硫化物含量有重要贡献。不同藻类水华的贡献有较大差异,甲藻水华的贡献最大,硅藻次之,未知藻类水华的贡献最小。实验结果还表明PO4^3-、NO2^-和NH4^+主要通过影响藻类生长状态,进而影响DMSP和DMSO的含量;NO2^-和NH4^+亦可能通过调节DMSP和DMSO在藻细胞内的生理功能,影响DMSP和DMSO的含量;PO4^3-、NO2^-和NH4^+与DMS含量无显著相关。  相似文献   

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