蕨类植物细胞学概说

<正> 现代蕨类植物细胞学是1950年Irene Manton教授创始的,在她的创造性著作《蕨类植物的细胞学与进化问题》(Problems of Cytology and Evolution in the Pteridophyta.1950)中,提出了主要是产于欧洲的27属和90种蕨类植物的细胞学证据。这本经典著作是相当大的、相当综合的和相当细致的,它激发了这一研究领域中的高潮。现在这     

CYTOLOGY AND MORPHOGENESIS IN THE RHIZOMORPH OF ARMILLARIA MELLEA

Aided by the techniques of thin sectioning and electron microscopy, the apical region of the rhizomorph of Armillaria mellea has been examined. This region is composed of concentric zones of morphologically distinct tissues derived from a subapical meristematic zone designated the apical center. Meristematic activity is of two types: (1) primary, localized in the apical center, in which new hyphal elements are formed from apical initials, and (2) secondary, localized in the lateral regions of the apex, in which elaboration of the hyphal elements by means of elongation and secondary crosswall formation takes place. From these meristematic zones the tissues of the mature rhizomorph are derived and include: (a) peripheral hyphae, (b) cortex, (c) subcortex, and (d) primary and secondary medulla. The manner of differentiation of an apical initial appears unique and involves synchronous nuclear divisions accompanied by segmentation in many planes. The result of this activity is the formation of multinucleate hyphae. Apical initials are usually highly cytoplasmic and possess peculiar non-membrane-bound fibrous bundles, but in all other respects they resemble the hyphae of most Basidiomycetes thus far examined with the electron microscope.     

分子进化研究中的一些问题

本文在强调生物系统的层次结构和非线性特征的基础上,就分子进化研究中存在的某些认识上的和方法学上的问题,提出了作者的观点和简要分析。     

THE CYTOLOGY OF POLLEN ABORTION IN C-CYTOPLASMIC MALE-STERILE CORN ANTHERS

Anther development of the C-cytoplasmic male-sterile (cms C) and the normal cytoplasm version (N) in the W182BN corn inbred was studied by light and electron microscopy. Deviation from normal pollen development was first observed in the tapetal cells at the tetrad stage of development. Two types of tapetal abnormalities were observed in plants with C cytoplasm. The first behaved like the N anther until the tetrad stage, when numerous small vacuoles appeared in the tapetal cells. Inner and radial tapetal cell walls broke down normally, but irregular Ubisch body deposition was observed, and exine development was inhibited and delayed. The tapetum and microspores disintegrated at the intermediate microspore stage. The second type of tapetum was highly vacuolated at the early tetrad stage, with dense inner and radial cell walls that remained intact and enlarged when the tetrads aborted. No organellar abnormalities, such as the mitochondrial changes observed in cms T, were observed in C anthers.     

CHROMOSOME COUNTS,CYTOLOGY, AND REPRODUCTION IN THE CACTACEAE

Chromosome counts and observations of reproduction for 55 taxa of Cactaceae indicate that polyploidy is correlated with self-fertility, adventive embryony, profuse branching, and vegetative reproduction. Six genera (Blossfeldia. Cleistocactus, Frailea, Pelecyphora, Rebutia, and Strombocactus) and 35 species or varieties are reported here for the first time. Preliminary observations of pachytene and diplotene indicate that these stages may be more useful in chromosome recognition than mitotic stages. Secondary association at metaphase I and II is interpreted as a retention of homologue association at interphase I and II (interkinesis). During meiosis of certain species, Feulgen negative bodies are present. The production of an abnormal premeiotic division is suggested as a mechanism for polyploid origin.