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     

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。     

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。     

强烈的求知欲高度的责任感

中国工程院院士曾溢滔教授是著名的医学遗传学专家。他是我国基因诊断主要开拓者之一,在攻克遗传病的基因诊断和产前诊断;在血红蛋白病领域;在奶牛胚胎性别鉴定和性别控制以及体细胞克隆牛和转基因动物生物反应器等研究领域成绩显著。在科研生涯中,他总结出的“幻想与求实、继承与发扬、责任与动力”的可贵经验,值得借鉴和发扬。他具有“强烈的求知欲和高度的社会责任感”,他的执着追求精神给人以鼓舞和力量。该文经作者同意全文转载自中国工程院学部工作部编发的《中国工程院院士自述》一书。     

On the Systematic Position of Paradombeya Stapf

The systematic position of Paradombeya Stapf has been debated until now. The studies on gross morphology, anatomy, palynology and cytology were undertaken to confirm the systematic position and affinities of this genus. The combination of features, e. g., umbel-like cyme, 2-celled anther, presence of staminodes, staminal tube, 15 stamens, bifid cotyledons, wood anatomy, chromosome number of 2n=20, triporate, spiny and spheroidal pollen grains, suggests that the genus be better placed in the tribe Dombeyeaeof the Sterculiaceae.     

梧桐科翅子树属的亲缘关系

翅子树属传统上均作为梧桐科山芝麻族的成员,但也有少数人将它归到Dombeyeae族中。本文根据对翅子树属的外部形态及花粉形态特征的研究,并结合其解剖、染色体和胚胎发育的资料,对翅子树属的亲缘关系进行了分析。翅子树属与山芝麻族在外部形态上比较接近,但在解剖、花粉形态和染色体基数等特征上则差异显著;与Dombeyeae族在花粉形态上一致,但在外部形态(花结构)、染色体基数和瓦形细胞等特征方面则明显不同,反映了翅子树属在这两个族之间的过渡状态,不宜作为任何一族的成员,应该作为一个独立的族存在,其在梧桐科中的位置在Dombeyeae附近。     

梧桐科一些属的分类位置探讨

梧桐科（Ｓｔｅｒｃｕｌｉａｃｅａｅ）是锦葵目中的一个多型科,科的特征比较比样化。自从Ｅ．Ｐ．Ｖｅｎｔｅｎａｔ（１８３０）建立该科以来,对于该科范围和包含的属种数目,各国学者至今尚存在各种不同的看法。作者认为,火桐属（Ｅｒｙｔｈｒｏｐｓｉｓ）应当从梧桐属（Ｆｉｒｍｉａｎａ）中分出成为单独的属;午时花属（Ｐｅｎｔａｐｅｔｅｓ）不应归入锦葵科（Ｍａｌｖａｃｅａｅ）,应当置于梧桐科;田麻属（Ｃｏｒｃｈｏｒ     

石竹科繁缕属与鹅肠菜属的数量分类

石竹科繁缕属(Stellaria L.)和鹅肠菜属(Myosoton Moench.)的系统关系一直存在争议.为了弄清它们之间的关系及属下分类等问题,选取55个形态特征对繁缕属和鹅肠菜属进行数量分类学研究.聚类分析和主坐标分析结果显示,鹅肠菜(M.aquaticum (L.) Moench.)与繁缕组繁缕亚组的关系较近,故支持将鹅肠菜属并入繁缕属.此外,研究结果还支持将繸瓣组作为独立的组.对性状的主坐标排序分析显示,茎的形状及是否被毛、叶长、叶宽、是否具叶柄、叶形及毛被、上下表皮气孔指数与密度、是否具花瓣及花瓣裂片数、雄蕊数目、蒴果长度、花柱与种子的数目、种子表面纹饰等性状特征是繁缕属与鹅肠菜属分类的重要依据.     

Comparative structure and pollen production of the stamens and pollinator-deceptive staminodes of Commelina coelestis and C. dianthifolia (Commelinaceae)

BACKGROUND AND AIMS: Flowers of Commelina coelestis and C. dianthifolia provide pollen alone as a floral reward, and rely on visual cues to attract pollinators. Three stamen types, all producing pollen, occur in each of these species: two cryptically coloured lateral stamens, a single cryptically coloured central stamen and three bright yellow staminodes that sharply contrast with the blue to purple corolla. The objective was to compare the stamen structure and pollen characteristics of each of the three stamen types, and to test the hypothesis that the staminodes are poor contributors of viable pollen for the siring of seed. The pollination roles of the three stamen types and the breeding systems of both species were also explored. Methods: Light, fluorescence and scanning electron microscopy were utilized to examine stamen morphology and pollen structure and viability. Controlled hand pollinations were used to explore the breeding system of each species. Filament and style lengths were measured to investigate herkogamy and autogamy. KEY RESULTS: Pollen from all stamen morphs is viable, but staminode pollen has significantly lower viability. Pollen polymorphism exists both (a) between the lateral and central stamens and the staminodes, and (b) within each anther. Lateral and central stamens have thicker endothecia with a greater number of secondary cell wall thickenings than the staminodes. CONCLUSIONS: Both species are entomophilous and facultatively autogamous. Lateral stamen pollen is important for cross-pollination, central stamen pollen is utilized by both species as a pollinator reward and for delayed autogamy in C. dianthifolia, and the staminodes mimic, by means of both colour and epidermal features, large amounts of pollen to attract insects to the flowers. Pollen from all three anther morphs is capable of siring seed, although staminode pollen is inferior. The thin staminode endothecium with fewer secondary thickenings retards staminode dehiscence.     

根据DNA的序列资料探讨翅子树族的系统位置

采用DNA分子测序技术对梧桐科5个族30个代表种的rbcL基因及核糖体DNA的内转录间隔区ITS序列(包括ITS1、ITS2和5．8srRNA基因)进行了序列分析。使用PAUP4．0b10软件对序列进行统计和分支分析。用启发式搜索方法寻找最简约树。从严格一致性树来看,梧桐科的全部代表类群主要被分为4支,一支仅为Sterculieae所构成;一支包括Helictereae的全部代表种;一支由Byttnerieae代表种所构成;最后一支由Dombeyeae和单属族翅子树族Pterospermeae所构成。rbcL和ITS系统树的不同仅表现在族内个别代表类群的位置和族的分支方式上。分析结果表明,与Helictereae相比,翅子树属,Pterospermum与Dombeyeae有更近的亲缘关系。然而,在外部形态、内部解剖和胚胎学方面,二者之间又存在诸多差异．故支持将Pterospermum另立为Ptcrospermeae的观点。     

爪哇蒙蒿子(Anaxagorea javanica)内轮退化雄蕊形态结构及功能

利用扫描电子显微镜、光学显微镜对爪哇蒙蒿子（Anaxagorea javanica Blume）可育雄蕊、内轮退化雄蕊和雌蕊的形态、结构进行了观察,并利用组织化学染色法对内轮退化雄蕊和柱头顶端腺毛化学成分进行了检测。结果显示,内轮退化雄蕊顶端为长条状腺毛,柱头顶端有头状和盾状腺毛,两者顶端的腺毛形态和结构明显不同,但分泌物成分类似,都含有蛋白质和脂类物质。内轮退化雄蕊的横切面为一层表皮细胞包围着薄壁组织,中央有一束维管束,与可育雄蕊花丝部位的横切面十分相似,是介于可育雄蕊和雌蕊之间的过渡结构。在雌蕊阶段,退化雄蕊顶端腺体释放的黏液供传粉昆虫觅食;在雄蕊阶段,退化雄蕊顶端覆盖柱头,呈S型,防止自花授粉。爪哇蒙蒿子薄片状可育雄蕊、内轮退化雄蕊以及可育雄蕊和退化雄蕊腹面上存在气孔等原始性状,是连接番荔枝科和其外类群的同源特征。     

中国特有种丹霞梧桐的新分布区和形态特征修订

为完善丹霞梧桐(Firmiana danxiaensis)的形态描述,对丹霞和喀斯特地貌4个分布点的植株宏观形态特征进行了比较研究。结果表明,丹霞梧桐的叶柄、叶片、花序、雄蕊、蓇葖果、花萼等特征与其原始文献的描述明显不同,且原始描述缺少败育雄蕊、败育子房、及花萼、果皮、种皮在发育过程中的颜色变化等特征。因此,对丹霞梧桐形态描述进行了修订或补充,并提供图片资料。     

Flower structure and potential bisexuality in Freycinetia reineckei (Pandanaceae), a species of the Samoa Islands

In Freycinetia reineckei the staminate flower (on the staminate spikes) comprises 3 or 4 (sometimes 2) stamens and a pistillode with 2 (sometimes 4) carpellodes, and the pistillate flower (on the pistillate spikes) is formed of a pistil with 2 (sometimes 4) carpels and of 3 or 4 (sometimes 2) staminodes. This perfect floral homology, also observed in all the other species that were studied with both pistillate and staminate material, strongly suggests that the flower of Freycinetia is basically and potentially bisexual, and may explain the occasional sexual lability and bisexuality of that flower (occurrence of both pistillate and staminate inflorescences, and/or of bisexual inflorescences with bisexual flowers and/or unisexual flowers, on the same individuals) in some species, and also the frequent occurrence of bisexual spikes in this species. These may be partitioned into pistillate, staminate, mixed and sterile zones. In the pistillate zones the flowers have the same aspect and structure as the pistillate flowers. In the staminate zones the flowers generally comprise 3 or 4 (sometimes 2) stamens and a ‘semi-pistil’ some have both stamens and staminodes. The semi-pistils are intermediate between pistils and pistillodes in length, aspect and structure, but always have placentas and ovules. In the mixed zones the flowers are generally formed of a pistil and 3 or 4 (sometimes 2) stamens, and are therefore true hermaphrodite flowers; some have both stamens and staminodes. In the sterile zones the flowers comprise a semi-pistil and 3 or 4 (sometimes 2) staminodes. The staminodes are anatomically very similar to the stamens, especially in the staminate, mixed, and sterile zones, in which they exhibit a wide range of variation in length, aspect and structure. The perfect floral homology as generic character on one hand, and the occasional bisexuality both with and without bisexual flowers and other aspects of sex expression (e.g. occurrence of both pistillate and staminate shoots on the same individuals) in some species on the other hand, seem to indicate that Freycinetia is a basically monoecious, sex changing genus.     

蜘蛛抱蛋属的细胞分类学研究Ⅱ

文章报道了13种蜘蛛抱蛋属植物的染色体核型,并对属内核型进化规律作了总结。作者认为随体染色体和第1对染色体可以作为本属核型的特征染色体。染色体数目变异与花部式样密切相关。本属植物原始的染色体基数为x=19。此外,对非整倍性变异的主要机制也进行了讨论。