苏铁杉与苏铁杉果伴生化石的发现及意义

苏铁杉属(Podozamites)曾经许多学者研究,认为其可能属松柏纲植物,有人将其置于独立的目和科中,即苏铁杉目(Podozamitales)、苏铁杉科(Podozamitaceae)中。事实上它只是一个形态属,包括外形相同的类似属类,区分种颇为困难;我国以往发表的有关该属资料,几乎全是依据叶的外形来定名的。苏铁杉果属(Cycadocarpidium),一般认为是苏铁杉属的生殖器官。但迄今为止,在世界上很少见到该两属在一起连生或共存的化石标本,而大都是以单独状态保存的。笔者报道该二属化石在同一标本上伴生出现——即大量的线叶铁杉(Podozamites schenkii Heer)和三个完整苏铁杉果的果穗化石,在晚三叠世发现,无疑进一步阐明了这二个属之间的亲密关系,以及它们的地层意义。     

猪屎豆学名的订正及同属药用植物

<正> 作者在编写豆科猪屎豆属植物志过程中,对本属植物进行了较系统的研究和整理,发现猪屎豆及其同类商品中药材名称很不一致,现在本文讨论。 一、概况 猪屎豆为豆科(Leguminosae)蝶形花亚科(Papilionoideae)猪屎豆属(Crotalaria)植物,是近代发掘出来的植物药,《中草药学》(1976)已有记载:“种子甘、涩、凉,可补肝肾、明目,固精”。全草有散结,清湿热等作用。早在《植物名实图考》中记载的野百合(Cro-     

几种单殖吸虫体壁的超微结构研究

用扫描电子显微镜和透射电子显微镜观察了黄颡四锚虫,鳙指环虫,钿锚三代虫,鲶盘虫的体表以及体壁的超微结构。除细锚三代虫外其它的三种单殖吸虫体表均没有明显的微纤毛,它们的体壁是由表皮的合胞体,基板,环肌,纵肌,以及表皮细胞体所组成,这些单有虫的表皮细胞所组成。这些音量     

应用同一细胞进行核型与带型的分析方法

应用同一细胞进行核型与Giemsa带型相对应的分析方法,早已在哺乳动物及人类染色体研究中普遍应用。最近有人开始将此方法应用到植物染色体研究中来,大大提高了植物染色体鉴别的可靠性。为推广此方法,现介绍如下:     

THE ECOLOGY AND GENETICS OF FITNESS IN CHLAMYDOMONAS. IV. THE PROPERTIES OF MIXTURES OF GENOTYPES OF THE SAME SPECIES

The properties of mixtures of genotypes of Chlamydomonas reinhardtii were investigated by growing them in monoculture and in all possible pairwise combinations in chemically defined axenic medium. Two sets of genotypes produced by crossing wild-type isolates were cultured in each of two physical environments. Mixtures were consistently more productive and less variable over environments than were their constituent monocultures. The average performance of a genotype in mixture was tightly correlated with its performance in monoculture. Reisolation of spores from mixtures at the end of growth showed that the mixtures became dominated by the component with the greater performance in monoculture, so that the properties of mixtures were attributable to replacement rather than to complementation. These results differ from those of similar trials using a range of different species of Chlamydomonas, where genetic interactions were found to be important. They are discussed in relation to theories of diversity and diversification, and related to the agronomic use of crop mixtures.     

A COMPARISON OF THE ELECTROPHORETIC VELOCITIES OF CELLOPHANE AND COLLODION SUSPENSIONS WITH ELECTROOSMOTIC VELOCITIES THROUGH MEMBRANES OF THE SAME MATERIALS

It is demonstrated that the isoelectric concentration of ThCl₄ is much greater for electroosmosis in small-pored membranes (cellophane, collodion) than for electrophoresis of particles of the same material. An explanation for the difference is advanced, based on the influence of the small pores in preventing complete development of the electrical double layer.     

同批次细胞基质收获甲肝和麻疹病毒制备联合疫苗的方法

采用同一批次细胞基质收获甲肝和麻疹病毒.应用甲肝L-A-1株和麻疹D3T11株,间隔3周先后感染同一批次人胚肺二倍体细胞2BS株,待两种病毒同时达到增殖高峰期时收获病毒液(以下简称HAM).对HAM分别进行病毒滴定、特异性检查、猴体安全性和免疫效果试验.结果显示,HAM的甲肝和麻疹病毒滴度与同批单价甲肝和麻疹疫苗病毒滴度,差异均无显著意义.该方法用于制备甲肝-麻疹联合疫苗,省时省力,操作简便,并可显著降低疫苗生产成本.     

A METHOD FOR ISOLATING INTACT MITOCHONDRIA AND NUCLEI FROM THE SAME HOMOGENATE,AND THE INFLUENCE OF MITOCHONDRIAL DESTRUCTION ON THE PROPERTIES OF CELL NUCLEI

1. An improved type of ground glass homogenizer for soft tissues has been described which brings about a high degree of cell disruption and liberation of nuclei without causing appreciable damage to mitochondria. The gentleness and effectiveness of the new homogenizer in respect to isolation of mitochondria have been ascertained by comparing the ATP-ase activities of mitochondria isolated in 0.25 M sucrose solution without pH adjustment using a previous type of homogenizer with those of mitochondria isolated under the same conditions with the aid of the new homogenizer. In these experiments sucrose of 0.25 molarity without pH adjustment has been used in order to maintain the mitochondria in a rather sensitive state so as to make slightly deleterious effects of homogenization readily apparent. 2. A new method is described for the isolation of morphologically intact mitochondria and cell nuclei from the same homogenate. In this procedure the pH of the homogenate in 0.44 M sucrose is maintained at 6.0–6.2 with citric acid during the homogenization. An alternative method employing 0.44 M sucrose plus 0.005 M CaCl₂ is given for the isolation of nuclei from tumor cells. However, the latter method does not produce unaltered mitochondria. 3. The α-ketoglutarate, malate, succinate, and hexanoate oxidases of the "intact" mitochondria isolated in 0.44 M sucrose adjusted to pH 6.0–6.2 with very dilute citric acid as described in this paper have been investigated, and it has been shown that the mitochondria compare favorably to those isolated in 0.25 M sucrose by a previously described method. 4. Mitochondria have been found to contain an enzyme which causes nuclei to lose their ability to form gels in dilute alkali. This enzyme is released from the mitochondria when the latter are disrupted. 5. Some properties of nuclei isolated by the new method have been briefly discussed.     

RESPONSE OF IPS GRANDICOLLIS (EICHHOFF) ADULTS (COLEOPTERA;SCOLYTIDAE) TO SITES IN BARK INITIATED BY OTHERS OF THE SAME SPECIES

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Dispersing males and females of Ips grandicollis , whether mated or virgin, initiated galleries on experimental logs held in a naturally infested P. radiata plantation. A few females initiated galleries despite the presence of adjacent male-initiated galleries. Males responded to logs bearing females by entering 41% of the female-initiated galleries. The pattern of entry of these males differed depending on whether the entrance to the female-initiated gallery was blocked by frass or not. The findings of this study has led to interesting speculations about the behaviour and biology of this species.     

采用BSLB(Brine Shrimp Letality Bioassay)法对元宝枫(Acer truncatum Bunge.)及同属植物活性部位的筛选

本文通过BSLB法对元宝枫及同属植物不同部位的水提物进行了活性试验,得知：元宝枫的幼技、种皮的水提物具一定的生物致死活性;同属植物青榨槭叶和种子,秦岭槭、权叶槭果翅的水提物也具一定的生物致死活性。本实验为元宝枫及同属植物进行进一步肿瘤细胞的体外培养试验及动物模型试验提供了科学依据。     

PARSIMONY AND THE CHOICE BETWEEN DIFFERENT TRANSFORMATIONS FOR THE SAME CHARACTER SET

Abstract— When phylogeneticists choose among alternative hypotheses, they choose the one that requires the fewest ad hoc assumptions, i.e. the one that is the most parsimonious. For some systematists, choosing among alternative transformation series for the same set of taxa is equivalent to attaining trees with shorter length and minimal homoplasy. Homoplasy is shown to be composed of hierarchical discordance and scattering, which are recognized and described for the first time. Neither the consistency nor retention indices can be used in assessing different theories of multistate character transformation because both are affected by the shape of the transformation series rather than the character state distribution on a tree. Fits of transformations to a tree are better assessed by comparing the transformation to the cladogram character and the nearest neighbor network. Nearest neighbor networks are graphical representations of the nearest neighbor matrix. Transformations with the closest greatest number of matches between cladogram characters and the least complexity in the nearest neighbor network are preferred. These transformations are shown to make the fewest number of ad hoc statements and hence to be the most parsimonious. A means for obtaining cladogram characters and nearest neighbor matrices using a widely distributed microcomputer program is presented.