禾谷缢蚜对小麦黄矮病传播能力变异的研究

测试结果禾谷缢蚜对小麦黄矮病(BYDV)传播能力显著提高。由此可使该病由北方干旱,半干旱的中、低产麦区往水地高产麦区,甚至南方麦区扩展曼延。已于1988、1989年秋季导致陕西关中西部水地,1989年春季导致南方麦区四川荣县小麦黄矮病发生流行。     

Dispersal Behaviour and Transmission Strategies of the Entomopathogenic Nematodes Heterorhabditis and Steinernema

Entomopathogenic nematodes of the Heterorhabditidae and Steinernematidae appear to be capable of long-distance dispersal and local migration. Their transmission strategies include both highly active seek-and-destroy behaviours and ambusher strategies, and they may be sensitive to sex-related factors in their own populations. Their host-finding abilities are poorly understood, despite the fact that these abilities are fundamental to their success as biocontrol agents in soil. Like the vast numbers of exotic hymenopterans and other natural enemies that have been released for biological control over the past century, they may be used in their ecologically competent wild-type form. On the other hand, because they are applied inundatively, they may be tailored, by breeding or transformation, to their intended purpose and to ecological incompetence, improving both their efficacy and their ecological safety.     

家兔晶状体纤维的超微结构:纤维细胞的间隙连接

本文报道晶状体纤维细胞间间隙连接的形态结构。我们利用冰冻断裂技术,在不同部位的球-和-凹连结的头部以及在纤维细胞和纤维细胞之间都观察到间隙连接的存在。通过极其丰富的上述连接,可实现细胞间代谢物和离子的传递。作者认为:对正常晶状体纤维细胞之间的间隙连接的深入了解,将会为晶状体发病机制的研究提供新的线索。     

The human rete testis

Summary The human rete testis was examined with regard to 1) the number and distribution of entrances of seminiferous tubules, 2) the light microscopic topography and 3) details of the passages as revealed by scanning and transmission electron microscopy. In a newborn 1474 entrances were counted, approximately 50 % entering from the right and 50 % from the left of the central long axis. Three major subdivisions of the rete were distinguished and described: a septal (or interlobular) part represented by tubuli recti, a tunical (or mediastinal) part which is a true network of channels, and an extratesticular part characterized by dilatations (up to 3 mm wide) which we have called bullae retis. In SEM, cylindrical strands running from wall to wall in the tunical and extratesticular rete spaces are a prominent feature. We have called these chordae retis. They are covered by epithelium and are 5–40 m wide and 15 to more than 100 m long. They contain a peculiar tissue consisting of central myoid cells in a fibroelastic matrix. The smaller chordae are avascular. In the light of these findings the rete is interpreted as a highly complex myoelastic sponge. Its function is discussed.Supported in part by USPHS Grant HD-03752 and by a Senior Scientist Award from the Alexander von Humboldt-Stiftung which made the co-authorship possibleSupported by a grant from the Deutsche ForschungsgemeinschaftFor their kind support in supplying us with material, we are indebted to Dr. Janssen (Institut für Rechtsmedizin, Universität Hamburg), Dr. Mairose (Zentralkrankenhaus der Justizbehörde, Hamburg) and Dr. Hubman (Allgemeines Krankenhaus St. Georg, Hamburg). We thank Dr. Kaiser (Zoologisches Institut, Universität Hamburg) for his friendly, generous and competent help with the scanning electron microscopy. Ms. Joanna Davis gave invaluable help with the laborious reconstruction of the rete entrances     

Observations on the marginal ruffles of an established fibroblast-like cell line

Summary LW13K2 cells, a clone of a spontaneously in vitro transformed derivative of embryonic Lewis rat fibroblastic cells, were studied by phase contrast cine-light microscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The ruffles found at the advancing edge of cells grown on glass substrates in vitro form and recede in a period of less than one min if they do not make an attachment of the substrate. If they fail to make an attachment they may form pinocytotic channels near the leading edge as described by Price (1972) and/or collapse, generally backwards, towards the cell body. The spines which appear to reinforce the membranous ruffles are the last structures to disappear, and accumulate in an irregular array behind the ruffling edge; this area is behind that in which pinocytosis occurs. In comparison with the sparse numbers of ribosomes found in the trailing edge, they are present in notable concentrations near the leading, ruffling edge of the cell. No membrane vesicles have been found in or near the ruffling edges at the ruffle-spine concentration zone.     

Ultrastructural alterations in ciliary cells exposed to ionizing radiation

Summary Early effects of ionizing radiation were investigated in an experimental in vitro system using the ciliary cells of the tracheal mucous membrane of the rabbit, irradiated at 30° C and at more than 90% humidity. The changes in physiological activities of the ciliary cells caused by irradiation were continuously registered during the irradiation. The specimens were examined immediately after irradiation electron microscopically. The morphological changes in irradiated material after 10–70 Gy are compared with normal material. After 40–70 Gy, scanning electron microscopy revealed the formation of vesicles on cilia, and club-like protrusions and adhesion of their tips. After 30–70 Gy, a swelling of mitochondrial membranes and cristae was apparent transmission electron microscopically. The membrane alterations caused by irradiation are assumed to disturb the permeability and flow of ATP from the mitochondria, which in turn leads to the recorded changes in the activity of the ciliated cells.This investigation was supported by grants from Konung Gustaf V:s Jubileumsfond, John and Augusta Perssons Stiftelse, B. Kamprads Fond, the Faculty of Medicine, University of Lund, Sweden and the Swedish Medical Research Council (No. B77-17X-03897-05)The authors are greatly indebted to Miss Inger Norling, Miss Marianne Palmegren and Miss Birgitta Sandström for their excellent technical assistance     

Ultrastructural characterization and three-dimensional reconstruction of isolated maize (Zea mays L.) egg cell protoplasts

Summary Isolated egg cell protoplasts ofZea mays L., inbred line A 188, have been studied at the transmission electron microscope level. Their preparation for electron microscopy has been performed by embedding in ultra-low gelling agarose as a preliminary step. Five isolated egg cell protoplasts were serially ultrathin sectioned and studied in detail. One of these protoplasts was reconstructed in three dimensions to provide additional information on its structure. After enzymatic digestion and microdissection, isolated egg cells are true, highly vacuolized protoplasts. The structure of their organelles agrees with in situ observations, indicating an ultrastructural intactness after isolation: the mitochondria are polymorphic, form reticulate networks, and have well developed cristae; the plastids contain starch grains; and the spherical nucleus is euchromatic. As in situ, the organelles of the isolated egg cell protoplasts are aggregated near the nucleus. The complete picture provided by this work should serve as a comparative base for studies on in vitro fertilization products.     

Morphology,morphometry and electron microscopy of HeLa cells infected with bovine Mycoplasma

Summary The host-parasite relationship of HeLa M cells artificially infected with a bovine species of Mycoplasma was studied by light microscopy, transmission electron microscopy and scanning electron microscopy. The use of morphometry to quantitate some of the findings was explored. The parasites were seen in locations extracellular to the cell surface. The detection of small numbers of organisms by light microscopy was well demonstrated by use of the fluorescent antibody technique. Scanning electron microscopy proved to be an excellent method for revealing the surface details of cell-parasite morphology. Ultra-thin sections showed that the parasites are aligned mostly parallel to the plasma membrane of the host cell but separated by a gap of 10 nm. Morphometry indicated an average of 69 organisms per cell surface occupying 1.7% of the surface area. An increase of 26% in diameter of the HeLa cells, possibly as a result of infection, was observed.The authors wish to thank Christiana Ulness and Andrea Erickson for expert technical assistance and Arnold Schmidt for the operation of the scanning electron microscope. This work was supported by grants from the U.S.P.H.S.: AI 09586, AI 10743, and AI 06720     

A combined scanning and transmission electron microscopic study and electron probe microanalysis of human pineal acervuli

Summary Untreated, decalcified and trypsinized acervuli from human pineal bodies were studied with the scanning and transmission electron microscope as well as by electron probe microanalysis. The mulberry-like acervuli are composed of a various number of spherical lobes (135–800 m) between which clustered groups of globuli (4–14 urn in diameter) are observed. The acervular lobes are very probably formed by an aggregation of these globuli. Small round particles 125–500 Å in diameter are observed on the surface of the pineal concretions. These are not influenced by either decalcification or trypsin treatment. The acervular mineral corresponds morphologically to hydroxyapatite. The electron probe microanalysis reveals the existence of calcium and phosphorus as main components of the acervuli. Small quantities of magnesium and strontium were also detected.Dedicated to Professor Berta Scharrer on the occasion of her 70th birthdayWith the technical assistance of Mr. P.A. MilliquetThe author wishes to thank Mr. Bauer and Mr. Fryder (Nestec SA, La Tour de Peilz) for the use of the Cambridge Stereoscan electron microscope and Dr. T. Jalanti (C.M.E., Lausanne) for his help with the use of the X-ray microanalyser     

Studies on silk secretion in the trichoptera (F. Limnephilidae)

Summary The ultrastructure and amino acid composition of the secreted silk of two species of trichopteran larvae, Pycnopsyche guttifer (Walk.) and Neophylax concinnus McL., were investigated. The spinnerets of these two animals were also examined by scanning electron microscopy. The silk consists of double-stranded, flat ribbons (1–4 wide), composed of bundles of 15–25 Å filaments. There are two components of the silk: the fiber proper and a surrounding coat thought to be a silk gum. Only the outer coat is positive to the EM PATP technique of Thiery (1967), which indicated the presence of neutral sugars. Amino acid analyses of Pycnopsyche silk show that, like other silks, two predominant amino acids are glycine and serine. Arginine, unexpectedly, is the third most abundant and there are a large number of basic and long side-chain amino acids. X-ray diffraction studies of the silk indicate that it has a less crystalline, more amorphous structure than that of other silks.Submitted to the Department of Biological Sciences of the State University of New York at Albany in partial fulfillment of the requirements for the degree of Doctor of Philosophy Acknowledgements. This study was supported in part by a National Institutes of Health Graduate Student Traineeship grant # GM-02014. The author would like to express sincere gratitude to Dr. Stephen Brown for his encouragement and help during the course of this study. I would also like to thank Dr. Curtis Hemenway and Mr. Douglas Halgren of Dudley Observatory for the use of their scanning electron microscope as well as Dr. Helen Ghiradella and Mr. William Radigan for help with the scanning electron microscopy. I owe special appreciation to Dr. Y. Myer of the Chemistry Department of SUNYA for doing an amino acid analysis of the silk and to Dr. K.M. Rudall of the University of Leeds for doing the X-ray diffraction studies of the silk samples