动物的的变态

变态是动物学中一个较重要的专用名词,有关内容在中学课本也多处涉及到。现择要介绍一点动物变态的知识,供动物学教学参考。何谓动物的变态动物由于外在和内在的原因,个体形态发生变化,这叫变态。但动物学所讲的变态,是狭义地从发生学角度理解,即胚胎不直接转变为成体,而是在后期发育过程中,先形成形态、生理、生态方面特殊的幼体,行独立生活和生长,以后在某阶段发生急剧变化,转变为成体。青     

活的不可培养的细菌的研究进展

活的不可培养微生物(VBNC)即一些微生物明显地丧失了可培养的特性,但是保留了自身原有的代谢活力,并且在一定条件下,又可以回复到可培养的状态。从VBNC细菌的诱导条件、生物学特性和检测方法3个方面对VBNC细菌研究进展做一综述。     

高频率的波动对于种子的萌发和植物的发育的影响

本文主要是以理论和试验来说明音波对植物的生长发育和种子萌发所起的影响。在农业实践上音波所起的作用,据现在所知:有缩短植物成熟期,加速萌芽和增强植物的生长发育等。这一些非但具有理论和实践上的意义,同时在今後把物理科学应用到农业科学中开辟了极广阔的前程。     

真核细胞的基因的组织

一、真核细胞基因的基本结构 1.转录单位: 从已知的数十种基因的顺序,可得出一个具有功能的基因的共同规律,在基因5’端-25至-75区,有CCAAT和TATAAA区(后者又称ATA box或Hogness box),相当于促进子区(Promotor),为体外转录所必需。     

由吸附的缩氨酸诱导的细胞膜的形变

研究了由一系列相互平行的吸附在细胞膜上的缩氨酸引起的膜的弹性形变,以及膜对缩氨酸的包裹行为,得到膜的平衡方程,用它可以来处理大尺度的形变,弯曲能量、吸附能量和弹性形变的相互竞争导致膜对缩氨酸发生从不吸附到部分吸附乃至完全包裹的结构转变．在膜的形变很小的时候,可以得到系统能量的解析解。     

远古的人们是怎样认识自己的起源的

人是从那里来的? 回答这个问题,你也许会说这有什么困难——人是从古猿变来的;甚至你还会进一步说,在这个从猿到人的转变过程中,劳动起着决定性的作用。然而这个现在看来比较明了的道理,恰是经历了多么漫长的认识过程才达到的呵!现在让我们首先来谈谈,远古的人们是怎样认识自己的起源的。最初的原始人可能还想不到自己的起源在人类诞生的最早时期,“最初的、从动物界分离出来的人,在一切本质方面是和动物本身一样不自由的”(恩格斯:《反杜林论》),这些最初的原始人为艰苦     

敲除pckA基因的结核杆菌引起的免疫反应的研究

研究结核杆菌pckA基因编码的磷酸烯醇型丙酮酸羧激酶(PEPCK)诱导机体产生的保护性免疫反应。用敲除pckA基因的牛结核杆菌BCG和野生型BCG分别感染小鼠,取肝、肺、脾进行病理分析,并进行脾细胞培养,检测CD4 、CD4 /CD8 、细胞因子IFNI-γI、L-12和TNF等。用敲除pckA基因的BCG感染的小鼠比野生型BCG感染的小鼠体内产生的结核结节少且不典型,炎性程度低。野生型BCG感染的小鼠脾脏内的CD4 T细胞和CD4 /CD8 、细胞因子IFN-γ、IL-12、TNF均明显高于敲除pckA基因BCG感染的小鼠。pckA基因为结核杆菌生长所必需,其编码产物PEPCK能够刺激机体产生免疫反应,是一种很好的疫苗候选分子。     

分离的蚕豆细胞核的RNA聚合酶活力的研究

利用Triton X-100对叶绿体膜的作用,可快速地从蚕豆幼叶制备较纯净的细胞核,它具有较高的RNA聚合酶活力。比较了两种分离核的方法,证明利用匀浆法制备的核具有较高的活力。核活力与发育时期有关系,茎端和第1对幼叶的核活力显著高于第2和第3对叶片的核活力。此外,核活力明显地受反应液内锰离子的抑制。     

正红菇的化学成分的研究

采用GC、HPLC、GC／MS、凝胶过滤层析等方法对正红菇(Russula vinosa)的某些成分的分析结果表明：正红菇其色素由红紫色素和黄色素两个组分组成,其中红紫色素对酸稳定,对碱及高温不稳定,而黄色素对它们则表现一定的稳定性。其多糖含量为2.74％,含有五种多糖组分。在脂肪酸组成上,主要是油酸和亚油酸,并有可能存在EPA和DHA。全氨基酸分析表明含有十六种氨基酸,必需氨基酸占总氨基酸的54．4％,所含挥发性物质是a一雪松烯,a一古芸烯及十五到二十烷。正红菇的提取液对细菌、酵母菌、霉菌均有一定抑制作用,对细菌抑制作用优于酵母菌和霉菌,革兰氏阴性细菌优于革兰氏阳性细菌的抑制作用。     

Molecular and culture-based analyses of prokaryotic communities from an agricultural soil and the burrows and casts of the earthworm Lumbricus rubellus

The microbial populations in no-till agricultural soil and casts of the earthworm Lumbricus rubellus were examined by culturing and molecular methods. Clone libraries of the 16S rRNA genes were prepared from DNA isolated directly from the soil and earthworm casts. Although no single phylum dominated the soil library of 95 clones, the largest numbers of clones were from Acidobacteria (14%), Cytophagales (13%), Chloroflexi (8%), and gamma-Proteobacteria (8%). While the cast clone library of 102 clones was similar to the soil library, the abundances of several taxa were different. Representatives of the Pseudomonas genus as well as the Actinobacteria and Firmicutes increased in number, and one group of unclassified organisms found in the soil library was absent in the cast library. Likewise, soil and cast archaeal 16S rRNA gene libraries were similar, although the abundances of some groups were different. Two hundred and thirty aerobic bacteria were also isolated on general heterotrophic media from casts, burrows, and soil. The cast isolates were both phenotypically and genotypically different from the soil isolates. The cast isolates were more likely to reduce nitrate, grow on acetate and Casamino Acids, and utilize fewer sugars than the soil isolates. On the basis of their ribotypes, the cast isolates were dominated by Aeromonas spp. (28%), which were not found in the soil isolates, and other gamma-Proteobacteria (49%). In contrast, the soil isolates were mostly Actinobacteria (53%), Firmicutes (16%), and gamma-Proteobacteria (19%). Isolates obtained from the sides of earthworm burrows were not different from the soil isolates. Diversity indices for the collections of isolates as well as rRNA gene libraries indicated that the species richness and evenness were decreased in the casts from their levels in the soil. These results were consistent with a model where a large portion of the microbial population in soil passes through the gastrointestinal tract of the earthworm unchanged while representatives of some phyla increase in abundance.     

种植年限对蔬菜日光温室土壤微生物区系和酶活性的影响

以种植2、4、6、11、13、16、19年的蔬菜日光温室土壤为研究对象,并以露地菜田为对照,测定了土壤微生物区系及酶活性的变化.结果表明: 随着种植年限的增加,土壤中细菌、放线菌和微生物总数均呈现先增加后减少的趋势,在种植11年时达到最大值,分别比对照增加了54.8%、63.7%和55.4%,差异达显著水平;而真菌数量持续上升,种植19年约为对照的2.2倍.微生物生理类群中,纤维素分解菌、自生固氮菌、亚硝酸细菌、反硝化细菌和硫化细菌数量的变化趋势与细菌相似, 种植11年分别为对照的1.5、1.6、1.9、1.4和1.1倍;而氨化细菌数量则呈现先减少后增加的趋势,在种植13年时达到最小值,为对照的56.0%.土壤中脲酶、多酚氧化酶、蔗糖酶、蛋白酶、纤维素酶和碱性磷酸酶活性随种植年限的增加呈现先增强后减弱的趋势,而过氧化氢酶活性较稳定.相关分析表明,细菌、放线菌和微生物总数与各土壤酶均呈显著正相关;而真菌数量与脲酶、蔗糖酶、过氧化氢酶和碱性磷酸酶均呈负相关,其中与过氧化氢酶的相关性达到显著水平.     

蚯蚓对秸秆还田土壤细菌生理菌群数量和酶活性的影响

在连续7a稻麦轮作系统中,通过测定作物收获后表层土壤(0-20cm)中4种细菌生理菌群数量和4种酶活性的变化,研究接种蚯蚓(Metaphire guillelmi)对秸秆(表施或混施)还田土壤的细菌生理菌群数量和酶活性的影响。试验设5个处理:对照、秸秆表施、秸秆混施、秸秆表施且接种蚯蚓、秸秆混施且接种蚯蚓。结果表明,单独秸秆还田促进了土壤氨化细菌、固氮菌、纤维素分解菌和无机磷分解菌数量增加,且土壤酶活性显著地增强;在秸秆表施方式下,接种蚯蚓使得上述4种细菌生理菌群微生物的数量增加;秸秆混施方式下,接种蚯蚓增加氨化细菌和无机磷分解菌数量,且土壤蛋白酶和蔗糖酶活性显著地增强(P0.05)。另外,蚓粪中4种细菌生理菌群微生物数量和水解酶活性都远远高于其周围土壤。在秸秆还田的作物轮作系统中,蚯蚓活动进一步增加土壤微生物数量和酶活性,对改善农田土壤肥力有着重要意义。     

Comparison of population density of plant parasitic and free-living nematodes in earthworm casts and adjacent soils of fallow and cultivated land in South Eastern Nigeria

Numbers of nematode species, juveniles, females and males in earthworm casts and in adjacent soils were studied in fallow (FL) and in cultivated lands (CL). In the FL each cast had an average of 5.6 different species of nematodes, while a soil sample of equal weight to the cast and within a 10 cm radius of the cast averaged 2.5 species. The difference between these means was highly significant. In the CL there were 4.7 species/cast and 2.9 species/soil sample. The difference between these two means was also highly significant. A total of 16 plant parasitic species, five omnivorous, two predacious and eight free-living nematode species were observed in the casts and in the adjacent soils of both FL and CL. The results partially contradicted the widely held view that earthworm casts are beneficial because the casts harboured numerous plant parasitic nematodes.     

Changes in physiological groups of microorganisms in soil following wildfire

Abstract: Physiological groups of soil microorganisms were investigated in a forest ( Pinus pinaster Sol.) to asses their response to wildfire-induced soil changes. Microbial fluctuations were recorded 1 month and 1 year after the fire, both in the field and during controlled soil incubations. In both the burned and the unburned soil, starch-mineralizing microbes predominated over cellulose-mineralizing microbes; there were a relatively high number of ammonium-producers, whereas nitrite and nitrate producers were scarce. In the short term, burning produced a decreasing to nearly undetectable number in cellulase-producers whilst amylase-producers, and especially, ammonifying microbes increased, and the nitrifying groups did not change. One year after the wildfire, the burning effect was slightly overcome by cellulolytic microorganisms and the amylolytic population was slightly decreased; the improvement of ammonifiers was reduced, ammonium oxidizers were positively affected and nitrite oxidizers continued to be unaffected by the fire. The trends of populations during soil incubation indicated that, in the long term, the effect of burning will probably be nil on ammonifiers, somewhat negative on cellulolytic and amylolytic microbes and slightly positive on nitrite- and nitrate-formers.     

我国南方红壤矿区复垦土壤的微生物生态特征研究Ⅰ对土壤微生物活性的影响

通过对浙江哩浦铜矿废弃地土壤微生物、土壤酶活性及生化作用强度研究表明,与对照土壤相比,矿区土壤微生物总数下降68．43％～80．32％,细菌、放线菌数量减少,但真菌变化不明显,各主要生理类群硝化细菌、氨化细菌、固氮菌、纤维素分解菌数量均呈下降趋势,土壤基础呼吸速率下降;土壤脲酶、蔗糖酶、蛋白酶、酸性磷酸酶、过氧化氢酶、多酚氧化酶和脱氢酶酶活性均有不同程度减弱;土壤硝化作用、氨化作用、固氮作用和纤维素分解强度降低,抑制了矿区土壤C、N的周转速率和能量循环,土壤微生物活性减弱是矿区复垦土壤微生物生态的重要特征之一。     

Plasmid Transfer between Spatially Separated Donor and Recipient Bacteria in Earthworm-Containing Soil Microcosms

Most gene transfer studies have been performed with relatively homogeneous soil systems in the absence of soil macrobiota, including invertebrates. In this study we examined the influence of earthworm activity (burrowing, casting, and feeding) on transfer of plasmid pJP4 between spatially separated donor (Alcaligenes eutrophus) and recipient (Pseudomonas fluorescens) bacteria in nonsterile soil columns. A model system was designed such that the activity of earthworms would act to mediate cell contact and gene transfer. Three different earthworm species (Aporrectodea trapezoides, Lumbricus rubellus, and Lumbricus terrestris), representing each of the major ecological categories (endogeic, epigeic, and anecic), were evaluated. Inoculated soil microcosms, with and without added earthworms, were analyzed for donor, recipient, and transconjugant bacteria at 5-cm-depth intervals by using selective plating techniques. Transconjugants were confirmed by colony hybridization with a mer gene probe. The presence of earthworms significantly increased dispersal of the donor and recipient strains. In situ gene transfer of plasmid pJP4 from A. eutrophus to P. fluorescens was detected only in earthworm-containing microcosms, at a frequency of (symbl)10(sup2) transconjugants per g of soil. The depth of recovery was dependent on the burrowing behavior of each earthworm species; however, there was no significant difference in the total number of transconjugants among the earthworm species. Donor and recipient bacteria were recovered from earthworm feces (casts) of all three earthworm species, with numbers up to 10(sup6) and 10(sup4) bacteria per g of cast, respectively. A. trapezoides egg capsules (cocoons) formed in the inoculated soil microcosms contained up to 10(sup7) donor and 10(sup6) recipient bacteria per g of cocoon. No transconjugant bacteria, however, were recovered from these microhabitats. To our knowledge, this is the first report of gene transfer between physically isolated bacteria in nonsterile soil, using burrowing earthworms as a biological factor to facilitate cell-to-cell contact.     

华西雨屏区天然常绿阔叶林土壤可培养微生物数量对模拟氮沉降的响应

为了解氮沉降对华西雨屏区天然常绿阔叶林土壤微生物数量的影响,从2013年11月至2014年12月,通过野外模拟N(NH_4NO_3)沉降,氮沉降水平分别为对照(CK 0 kg N hm~(-2)a~(-1))、低氮沉降(L 50 kg N hm~(-2)a~(-1))、中氮沉降(M 150 kg N hm~(-2)a~(-1))和高氮沉降(H 300 kg N hm~(-2)a~(-1)),研究了氮沉降对天然常绿阔叶林0—10cm和10—20cm土层土壤可培养微生物数量的影响。结果表明:华西雨屏区天然常绿阔叶林0—10cm土层的细菌、真菌和放线菌数量均显著大于10—20cm土层,氮沉降未改变原有垂直分布格局。L处理对0—10cm和10—20 cm土层土壤微生物总量无显著影响,M和H处理则显著降低了土壤微生物总量。氮沉降降低了0—10cm和10—20cm土层的细菌数量,且抑制作用随氮沉降量的增加而增强。氮沉降降低了0—10cm土层的真菌数量,但下降幅度与氮沉降量之间无明显规律;在10—20cm土层,M和H处理在夏季显著增加了真菌数量,表明适量氮沉降能有效缓解夏季土壤真菌的氮限制状态。氮沉降对0—10cm土层放线菌数量的影响表现为先促进再抑制,L和M处理增加了放线菌数量,H处理降低了放线菌数量;氮沉降增加了10—20cm土层的放线菌数量,其中M处理的促进作用最大。氮沉降对土壤微生物数量的影响随土壤深度的增加而减弱。     

Dehydrogenase activity in Lumbricus terrestris casts and surrounding soil affected by addition of different organic wastes and Zn

A laboratory experiment was conducted to determine the effects of different organic wastes such as wheat straw (WS), tea production waste (TEW), tobacco production waste (TOW), cow manure (CM) and hazelnut husk (HH) on dehydrogenase activity (DHA) in casts of earthworm Lumbricus terrestris and surrounding soil using 5% (dry weight) application rates associated with increasing doses of Zn (0, 50, 100, 250, 500 and 1000 microg g(-1)). Twenty one days after treatment of Zn and organic wastes, the DHA analyses were carried out on collected casts and soil samples. In general, all organic waste treatments influenced the DHA, the contents of organic C, N and available Zn in earthworm L. terrestris casts and the surrounding soil in comparison with the control. DHA in casts exceeded that in the surrounding soil without Zn additions. After Zn application of 50 microg Zn g(-1) in all organic waste treatments and the control, the DHA level in casts and surrounding soil increased significantly. It decreased by application rates of 100, 250, 500 and 1000 microg Zn g(-1) consecutively in all organic waste applications. The addition of wastes with low C/N ratio and high Zn content (TEW, TOW, CM) inhibited the DHA in both cast and surrounding soil.     

大棚蔬菜轮/连作系统土壤肥力与微生物因子综合评价

从土壤肥力与微生物因子探索连茬障碍机理,以期为其提供科学依据。研究草莓番茄轮作(RST)、番茄连作4年(CT4)和番茄连作10年(CT10)3种蔬菜种植模式根际与非根际土壤微生物区系及生理菌群,并对土壤肥力与微生物生物因子进行主成分分析。结果表明根际土壤微生物三大类群和生理菌群数量均高于非根际,根际效应显著。番茄连作根际与非根际土壤细菌和放线菌数量呈现先增加后减少趋势;真菌数量呈线型增加趋势,CT4和CT10在根际与非根际较RST分别增加9.09%和2.11%、75.48%和57.72%。番茄连作根际土壤硝化细菌和好气性自生固氮菌数量的减少,氨化细菌与好气性纤维素分解菌在短期连作表现为增加长期减少的变化趋势;解钾菌、无机磷和有机磷细菌数量在根际与非根际土壤均减少。在6种研究的种植模式中,RST根际土壤状况最好,其次为CT4的根际与RST非根际土壤,CT10的根际土壤、CT4与CT10非根际土壤状况最差。结论是蔬菜连作造成土壤质量下降,连作年限越长下降越显著。