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的组成,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５     

EFFECTS OF SINGLE AND MULTIPLE EXPOSURES OF FERULIC ACID ON THE VEGETATIVE AND REPRODUCTIVE GROWTH OF PHASEOLUS VULGARIS BBL-290

Phaseolus vulgaris BBL-290 plants were grown in growth chambers in the Southeastern Plant Environment Laboratory and exposed to either single (at seedling, flower, or podfill) or multiple (biweekly or weekly) treatments of ferulic acid (FA). In the first experiment, plants were harvested one week after FA treatment (0, 1.0, 2.0 mM) and at final harvest (56 days old). FA delayed leaf expansion during the seedling and flowering stages. The total plant leaf area and the plant dry weight of plants treated with 1.0 and 2.0 mM FA as seedlings were reduced one week after treatment by 38–48%. The total plant leaf area and the plant dry weight of plants treated at flowering with 2.0 mM FA were reduced by 25% one week after treatment. Treatment with 2.0 mM FA at podfill caused the senescence and abscission of older leaves and reduced total plant leaf area, plant dry weight and mean pod dry weight by 54, 40, and 48%, respectively, one week after treatment. The plants treated at the seedling and flowering stages recovered by final harvest. In a subsequent experiment, FA (0, 0.50, 1.0, 1.5 mM) reduced total plant leaf area at the seedling and flowering stages but not at podfill. The youngest expanding leaves were most sensitive to FA at flowering. The leaf area of these leaves was reduced by 35 and 25%, one and two weeks after treatment, respectively. Their absolute growth rates were reduced from 31 to 56% one week after treatment at flowering. Their relative growth rates were reduced by 50% one week after treatment. Growth rates then recovered within two weeks after treatment. In the final experiment, biweekly exposures of FA (0.25, 0.50, 0.75, 1.0) reduced total plant leaf area but did not affect any other growth parameters. Weekly exposures of FA (0.25, 0.50, 0.75, 1.0) reduced total plant leaf area up to 34%, absolute growth rate up to 58%, leaf number up to 31% and pod number up to 58%. As the frequency of exposure to FA increased, the concentration necessary to affect bean plant growth and development decreased.     

三色马先蒿的引种栽培研究

本文报道三色马先蒿有性繁殖及植株生长与发育的调控技术。种子发芽率达８５％,发芽势４０％。栽培植株能在引种地正常开花结实,株平均开花数４５朵,结实率５０％。     

毛白杜鹃(Rhododendron mucronatum)适生光强的生理、生化研究

研究了毛白杜鹃最适生境的相对光强和其在不同相对光强生境中抗性变化的规律。结果表明:当生境的相对光强处于65%以上时,毛白杜鹃叶子内过氧化物酶和过氧化氢酶活性达到较低值,而还原型 Vc,单宁酸,多酚类的含量达到了较高值。同时,在相对光强为65%以上的生境中,毛白杜鹃类不仅生长发育健壮,抗逆性强,而且,开花指数和观赏价值达到了较高值。因此,推断毛白杜鹃类适生生境的相对光强为65%以上。而且过氧化物酶和过氧化氢酶活性及还原型 Vc、单宁酸、多酚类的含量可以作为衡量植物是否处于适生生境的指标。     

GROWTH AND DEVELOPMENT OF LITCHI CHINENSIS AS AFFECTED BY SOIL-MOISTURE STRESS

The effects of soil-moisture tension on growth and floral development of field-grown Litchi chinensis, a woody subtropical fruit tree, were investigated. Floral initiation and fruit set were promoted by a high soil-moisture tension for 6 months, beginning with June, 1967, or for 4 months, beginning with October, 1967. The normal floral-initiation period in Hawaii is during the period November to January. The apical meristematic tissue, judged from the number of branches flowering, was apparently not adversely affected by a soil-moisture stress, provided adequate water was available during the floral-bud development period. Low soil-moisture tension (0.3 bar) throughout the experimental period was inhibitory for floral bud initiation. High soil-moisture tension inhibited growth of the trunk and the emergence of flush-growths. Flowering was correlated significantly, and negatively, with growth. Leaf nitrogen and potassium levels were unaffected by water stress, but the phosphorus levels in leaf and stem were lowered by high-moisture tension. Hydrolysis of starch under moisture stress, reported for some species, was not evident in the Litchi. No correlation between trophic constituents and flowering was observed.     

ROLE OF PSEUDOBULBS IN GROWTH AND FLOWERING OF CATASETUM VIRIDIFLAVUM (ORCHIDACEAE)

In Catasetum viridiflavum Hook., a drought-deciduous orchid from central Panama that produces unisexual flowers, plants possess up to nine annually-produced pseudobulbs. I investigated the role of these structures in plant growth and flowering by 1) relating annual shoot size and flower production to the size and number of pseudobulbs possessed by plants, 2) experimentally severing connections between young and old pseudobulbs when plants were dormant and monitoring their subsequent vegetative growth and flowering, and 3) determining the seasonal variation in water content, total nonstructural carbohydrates, nitrogen, and phosphorus in pseudobulbs. In small plants (1 to 3 pseudobulbs) pseudobulb stores appeared important to both vegetative growth and flowering. In larger (= older) plants, pseudobulb number was not related to vegetative growth and experimental separations of young from old pseudobulbs did not affect growth. However, flower production by experimental plants was significantly reduced relative to controls. Male plants were usually smaller than female plants in the areas studied; however, experimental reductions of pseudobulb number did not affect the sex expression of plants. All measured nutritional components of pseudobulbs exhibited significant seasonal variation. Carbohydrates appeared most important for supporting growth immediately following dormancy. Nitrogen and phosphorus were less important for this role and may have been more important for determining the number of flowers produced by plants.     

VARIATION IN INDIVIDUAL FLOWERING TIME AND REPRODUCTIVE SUCCESS OF AGALINIS STRICTIFOLIA (SCROPHULARIACEAE)

Field studies on two populations of Agalinis strictifolia were conducted over a 3-year period to investigate the relationship between flowering time of individuals and plant size, flowering duration, flower and fruit production, fruit predation, and growth rate. Seasonal patterns of pollinator visitation were compared with those of individual flowering time, flower density, percent fruit production, and mean seeds/fruit. In general, early and middle flowering individuals (as determined by either first flowering date or peak flowering) were larger, flowered longer, and produced more flowers and fruits than late flowering individuals. Early and middle flowering individuals (based on first flowering date) also grew faster than late flowering individuals. Although early and middle flowering individuals produced more fruits, fruit predators did not damage a disproportionate number of fruits compared to late flowering individuals. Patterns of bee visitation showed no association with seasonal patterns of flower density, percent fruit production, mean seed/fruit, or individual flowering time. In populations of A. strictifolia, it would seem that biotic or environmental determinants of growth rate (hence size and reproductive success) may be more important in generating variation in individual flowering time than patterns of pollinator visitation or fruit predation.     

EFFECTS OF AGE AND SIZE ON LIFE HISTORIES AND POPULATION GROWTH OF RHODODENDRON MAXIMUM SHOOTS

Age- and size-specific shoot life histories were studied with population censuses in June 1984 and June 1985 in an evergreen understory shrub. Rhododendron maximum. Most shoots (65%) survived without branching or flowering, and lesser numbers branched (2%), flowered (20%), or died (23%) during the year between censuses. The probabilities of surviving, branching, flowering or dying were both age- and size-dependent. Small, young shoots increased in leaf area. Flowering occurred most prominently in 3- to 6-year old shoots that had exceeded a leaf area of 200 cm², and the rate of flowering increased proportionately with size above this threshold. Branching normally occurred in the year following flowering. The age and size distributions of the population shifted significantly between years, indicating a nonequilibrium population. The survival schedule was Deevey Type I, indicating a high degree of “parental care” of young shoots. Age- and age + size-based demographic models predicted a rapid decline of the shoot population over a decade, while a size-based model predicted a much slower decline in shoot numbers. A sensitivity analysis of the models showed that overall shoot population growth was positively influenced by branching shoots and shoots that added leaf area, and negatively influenced by shoots that lost leaf area, died, or flowered. The role of shoot life histories in determining individual plant fitness and ecological dominance is discussed.     

内源吲哚乙酸、脱落酸和赤霉酸与棉铃发育及脱落的关系

气相色谱分析的结果表明,开花后5～6天,不受精即将脱落棉铃里IAA和ABA的含量显著高于对照;GA_3处理的铃中IAA和ABA的含量则明显低于对照。IAA和GA_3含量在开花后第10天达到高峰,以后迅速下降,至第30天。又出现第二峰胚珠和纤维里尤为明显。ABA含量在开花后第15天达得高峰,以后下降,到第30天,又逐渐上升。棉纤维伸长及干重增加的最快速率与这三种激素的含量高峰密切相关。     

硝态氮和铵态氮对墨兰生长发育的影响

以无土栽培的方法研究不同氮水平的硝态氮和铵态氮对墨兰［Ｃｙｍｂｉｄｉｕｍｓｉｎｅｎｓｅ（Ａｎｄｒ．）Ｗｉｌｌｄ．］生长发育和某些生理特性的影响。１ｍｍｏｌ／Ｌ和１０ｍｍｏｌ／Ｌ的硝态氮和铵态氮处理都促进叶芽和叶片正常生长,前者似乎比后者好一些。５０ｍｍｏｌ／Ｌ的两种形态的氮均使叶片生长缓慢,尤其是铵态氮。１和１０ｍｍｏｌ／Ｌ硝态氮处理则正常开花,而５０ｍｍｏｌ／Ｌ则例外。铵态氮处理各种浓度均不形成花芽。建议墨兰营养生长期施用１ｍｍｏｌ／Ｌ的硝态氮或铵态氮,但生长后期则应施１—１０ｍｍｏｌ／Ｌ硝态氮,以利花芽分化。作者认为,墨兰生长缓慢与光合速率极慢和硝酸还原酶活性极低有关,墨兰开花与否和Ｅ／Ｎ比大小有关。     

不同水平磷对磷饥饿墨兰生长发育及某些生理特性的影响

将磷饥饿的墨兰无土栽培在5个NaH_2PO_4水平的营养液中,结果表明:0.20mmol/L NaH_2PO_4有利于叶芽生长;当叶片张开后,1mmol/NaH_2PO_4促进光合作用和呼吸作用,叶片生长较快,褐斑病病斑较少,每株花数增多.