毛乌素沙地中间锦鸡儿根瘤菌遗传多样性及16S rDNA全序列分析

野生豆科植物中间锦鸡儿是毛乌素沙地的优势种。从蛋白质和DNA水平分析与其共生的根瘤茵的遗传多样性。在蛋白质水平上,24株中间锦鸡儿根瘤菌和9株参比菌株分为2组,A组包含95．8％供试中间锦鸡儿根瘤菌,参比菌株聚为B组,菌株GH72不与其余供试根瘤菌聚类。应用16S　rDNA　PCR—RFLP方法将供试菌株分为22种基因型,中间锦鸡儿根瘤菌组成12种,其余10种由参比菌株构成。表明中间锦鸡儿根瘤菌具高水平遗传多样性。选取代表菌株GH2001进行16S　rDNA全序列测定。与已知相关根瘤菌菌株16S　rDNA进行同源性比较,构建系统发育树状图。GH2001位于Rhizobium分支,与且Agrobacterium radiobacter,Ag.rubi,Rhizobium giardinii,R.mongolense,R.yanglingense,R.galegae和R.huautlense的序列同源性分别达到99％、98．3％、96．3％、95．5％、95．6％、95．27％和95．7％。     

Morphometric classification of the neurosecretory granules in the rat pars nervosa

Summary The distribution of the diameters of the neurosecretory granules in the rat pars nervosa (measured from electron micrographs taken at 40 000 × ) was compared among axons by nonparametric statistical methods and the axons were classified into five groups with median granule diameters of 143, 155, 167, 180 and 193 nm. We suggested that these five axon types carried different secretory substances contained in the pars nervosa. This investigation is supported by a grant from the Population Council, New York and grant from the Ministry of Education. Authors are grateful to Japan Electron Optics Laboratory Company for their technical assistance with the electron microscopy and to Miss Kazue Yamamoto for her help in preparing the figures.     

Ultrastructure of STH cells of the pars distalis of hepatectomized mice

Summary An electron microscopic analysis was performed on the pars distalis of the hypophysis of hepatectomized mice. Intact and sham operated mice served as controls. The STH cells presented striking changes that were most intense and widespread in those animals sacrificed at midnight of the second day after hepatectomy. These changes can be summarized as follows: 1) Hypertrophy of the Golgi complex with increased number of immature granules within the Golgi zone. This change appeared also in otherwise unmodified STH cells. 2) Strong dilatation of the endoplasmic reticulum whose cisternae contained much electron dense material. 3) Granules with partially diminished electron density, some of them in spatial relation with the plasma membrane and others swelling and bursting within the cytoplasm. All transitions between unchanged 350–400 m granules and extremely altered ones, were seen. 4) Release sites, characterized by dense zones in the plasmalemma, close to aggregates of electron lucent microvesicles, and almost empty granule membranes. 5) Increase in the density of the mitochondria which appeared grouped near the Golgi zone. 6) Increase in the number of large lysosomes of the autophagic vacuole type. 7) Irregular nuclear outlines. These data suggest increased synthesis and release of growth hormone in STH cells stimulated by hepatectomy.Work carried out with the financial assistance of a grant of the Comision de Investigation cientifica de la Universidad Nacional de La Plata. Thanks are due to the members of the technical staff of the Institute for their technical assistance.     

Responses of the teleost pituitary (goldfish,eel) to deionized water

Summary The cytological responses of the pituitary gland during adaptation to deionized water (DW) were investigated in the goldfish and the eel. In both teleost species, a stimulation of the prolactin (PRL) cells could not be detected, although the levels of blood electrolytes (Na⁺,Ca²⁺,Cl^–) are reduced in the eel. PRL cells appear less active in DW-adapted eels. A striking stimulation of the PAS-positive cells of the pars intermedia occurs in both species after 3 weeks and, in the eel, is still present after 11 weeks. Cell and nuclear hypertrophy, mitoses and a well-developed endoplasmic reticulum are observed. MSH cells are partially degranulated when pigmentation is affected; a reduced activity of MSH cells is evident after 11 weeks. The amount of neurohypophysial tissue is reduced. In the goldfish and the eel, during adaptation to DW, an unknown factor secreted by the PAS-positive cells of the pars intermedia appears to play a more important role than the secretion of PRL. These two species are able to survive in fresh water without the pituitary. The control of the PAS-positive cells by external sodium or calcium is discussed.     

Structural relationships between parenchymal and stromal elements in the pars intermedia of the rat adenohypophysis as demonstrated by extracellular space markers

Summary The pars intermedia (PI) of the rat adenohypophysis was studied by light and transmission electron microscopy after conventional staining as well as ruthenium red staining, and after systemic injection of horseradish peroxidase. The studies disclose a complex and constant system of two channel types (Type I and Type II channels) formed by PI cells with specific relationships to a very rich nerve supply, to each other, and to a stellate cell type proposed here to represent an element of neuroglia. The channel system could perform a function in the movement of fluids and solutes within the PI which is virtually avascular in the rat as well as in other mammals.Supported by the Medical Research Council of Canada Grant # MA6445We thank Mr. J. Jones and Mr. A.R. Morris for their expert technical assistance     

Endemism,palaeoendemism and migration: the case for the ‘European endemic’, Mallomonas intermedia

The Synurophyceae is a well-supported clade of ecologically important heterokont algae found largely in freshwater planktonic habitats worldwide, whose members have cell coverings consisting of species-specific siliceous scales overlapped in a highly organized manner. Many synurophytes have been described as endemic and are found only in specific regions of the world. A thriving population of the European endemic, Mallomonas intermedia, was discovered in a remote desert pond situated in the Virgin Valley, Nevada, USA and in a stratigraphic sequence from the middle Eocene fossil locality known as Horsefly in British Columbia, Canada. Both North American finds were closely compared with populations from Europe, confirming the identifications. Before these discoveries, this species was recorded from numerous waterbodies exclusively in Europe, but was lacking from hundreds of sites examined from other continents. Its presence in western North America during the warm middle Eocene confirms that historically this species had a significantly wider distribution and may be best classified as a palaeoendemic. Additional species uncovered from a second fossil locality that are closely related to M. intermedia further support the presence of this lineage in North America during the Eocene. The living population in northern Nevada presents an enigma. Does this remote desert population represent a remnant population that has gone undetected until now, or is it a recent arrival from an unknown region by an unknown vector?     

Species-specificity of monoclonal antibodies recognising Prevotella intermedia and Prevotella nigrescens

Abstract Prevotella intermedia and Prevotella nigrescens are not easily distinguished, making it difficult to assess their roles in disease. This study examined the specificity of three monoclonal antibodies (mAbs) for these species. Differentiation between P. intermedia (13 isolates) and P. nigrescens (24 isolates) was by the electrophoretic mobility of their malate and glutamate dehydrogenase enzymes or by DNA homology grouping. All P. intermedia reacted strongly with mAb 40BI3.2.2 whereas P. nigrescens strains did not. Monoclonal antibodies 37BI6.1 and 39BI1.1.2 recognised all strains of both species but most P. nigrescens reacted weakly with mAb 39BI1.1.2. Monoclonal antibody 40BI3.2.2 therefore recognises an antigen specific for P. intermedia but not P. nigrescens and provides an easy and reliable means of distinguishing between these species. Three vaginal isolates identified biochemically as P. intermedia had enzymes with mobilities corresponding to neither P. intermedia nor P. nigrescens . These isolates were not recognised by mAbs 39BI1.1.2 or 40BI3.2.2 and may represent an undescribed taxon within this group of organisms.     

Immunohistochemical study of the adenohypophysis of Typhlonectes compressicaudus (Amphibia,Gymnophiona)

Summary The indirect immunofluorescence method was used to identify and locate LTH-, STH-, LH-, TSH-, ACTH- and MSH-immunoreactive cells in the pituitary of Typhlonectes compressicaudus (Gymnophiona). The present study defines the histological and histochemical staining properties of each cell type identified.     

Variation of Breeding Systems in Populations of Caragana intermedia (Leguminosae ) in Maowusu Sandy Grassland

Maowusu sandy grassland locating at an ecotone between typical desert and typical grassland contained several landscape ecotypes or elements where Caragana intermedia Kuang et H.C.Fu naturally distributed as a dominant species in shrub ecosystems. Based on a phenomenon of gene segregation of open-pollinated seeds within each plants similar to Mendel's segregation in F2, a study on testing the breeding systems of populations under 4 landscape ecotypes was conducted. Statistical data showed its availability in estimation of breeding system parameters when isozymes were used as genetic markers. Nei's genetic differentiation GST among 4 ecotypes in Maowusu was estimated at 0.07 from lap loci close to a GST =0.076 reported in the authors' laboratory. The results indicated that breeding systems of populations gradually changed from total outbreeding to partial inbreeding when water conditions worsened. Therefore, the former RAPD data, especially the cline of frequencies for a few polymorphic DNAs in different landscapes can be partially explained by gene fixation caused by selfing or inbreeding probably induced by drought. It was difficult to assess breeding system parameters by using one dimensional SDS polyacrylamide gel electrophoresis of seed proteins of C. intermedia simply due to a difficulty of genetic analysis of seed protein subunits.     

The neurohypophysis of the crested newt

Summary In the crested newt, the ultrastructural organization of the pars nervosa is analogous to that already known in non-mammal tetrapods. An orderly array of ependymal cells makes up the inner limiting layer while less abundant pituicytes are irregularly distributed within this organ. Light and dark pituicytes can be distinguished on the basis of the relative density of the cytoplasmic matrix and the distribution of the cell organelles.Both the ependymal cells and pituicytes are rich in dense bodies and possess extensive processes which ramify among the nerve fibers, often reaching the pericapillary space which they can line for long distances.The main components of the pars nervosa are nerve fibers and nerve terminals (type A), containing electron dense granules 1200–2000 Å in diameter together with clear vesicles averaging 250–400 Å. These fibers are likely to correspond to the aldehyde fuchsin positive neurosecretory fibers revealed by light microscopy. Differences in the granule size within the fibers and terminals lead to further recognition of two subgroups (A₁ and A₂).Other fibers and terminals (type B) containing clear vesicles and granular vesicles 600 to 1000 Å in diameter, possibly of aminergic type, are also encountered. These fibers are rare and can be seen only in the portion of the pars nervosa near the pars intermedia of the adenohypophysis.Lastly, fibers and terminals containing only clear vesicles ranging from 250 to 400 Å (type C) are occasionally found.Nerve endings are often formed by type A fibers on the perivascular space and on the perivascular processes of the ependymal cells and pituicytes. In agreement with recent findings available in the literature, the occurrence of synaptoid contacts between these terminals and both pituicytes and ependymal cells may confirm the active role of these cells in transport and release of neurosecretion.Work supported by a grant from the Consiglio Nazionale delle Ricerche.We are gratefully indebted to Dr. G. Gendusa and P. Balbi for technical assistance, dr. G. E. Andreoletti for statistical analysis.