Morphological studies on neuroglia

Summary The silver-impregnation procedure of Tsujiyama is suitable for demonstration of all three classical types of neuroglial cells; in the present study it was used for electron microscopic identification of neuroglial cells in the brain of the cat. The aim of the present study was 1) to determine impregnated structural correlates of neuroglial cells at the light- and electron-microscopic levels, and 2) to determine whether the method of Tsujiyama is applicable for the electron microscopic identification of the single types of neuroglial cells. Silver deposits were observed over the cytoplasm and processes of astrocytes where numerous glial filaments were present. Oligodendrocytes and microglial cells may be precisely differentiated by use of Tsujiyama's silver impregnation method at the electron microscopic level due to the pattern of silver-deposition in these two basic types of cells. This silver-impregnation method combined with electron microscopy is thus suitable for a precise identification of neuroglial cells; the technique may prove to be very helpful in identification of such categories of neuroglial cells that encompass also the images of cells which cannot be classified by use of the standard methods.Supported by a grant (No. 437002) from the Ministry of Education, Science and Culture, Japan     

Morphological studies on neuroglia

Summary Electron-microscopic survey of selectively stained microglial cells in the cerebral cortex of the rat reveals that the processes of this cell type often encircle axo-dendritic synapses. Enzyme-histochemical methods for thiamine pyrophosphatase (TPPase) or nucleoside diphosphatase (NDPase) were used for the selective marking of the microglial cells; TPPase and NDPase activities were observed in the plasma membrane of microglial cells. The synapses encircled by microglial processes displayed presynaptic structures containing round clear vesicles (50 nm in diameter) and a prominent thickening of the postsynaptic membrane. In vitro, the above-mentioned enzymatic activities were completely suppressed by neuroactive agents such as catecholamines and phenothiazine derivatives. Examination using enzyme-histochemical techniques suggests that a single enzyme may be responsible for both above-mentioned enzymatic reactions. The functional significance of microglial cells in the normal central nervous tissue is discussed.This work was supported by grant No. 437002 from the Ministry of Education, Science and Culture, Japan     

Taxonomic studies on 'Streptococcuspluton'

Strains of ' Streptococcus pluton ' isolated from honeybee larvae with European foul-brood from widely separate parts of the world represent a relatively homogeneous taxon; all are related serologically. Added cysteine or cystine make a variety of otherwise unsuitable nitrogen sources satisfactory for all strains, which all have the same fastidious culture requirements. Test strains lack respiratory quinones and possess a Group A peptidoglycan based upon lysine, primarily straight-chain and cyclopropane-ring fatty acids, and a DNA base composition of 29–30 G + C mol %. Results obtained indicate that the strains presently designated ' Strep. pluton ' should constitute the nucleus of a new genus.     

Cellular studies on retinoblastoma

Retinoblastoma may be hereditary or non-hereditary. The hereditary form involves either a predisposing gene transmissible as an autosomal dominant or a deletion at chromosome 13q14. An abnormal cellular response to ionizing radiation was suggested by the occurrence of secondary neoplasms within the field of therapeutic radiation in hereditary retinoblastoma patients. Hereditary retinoblastoma patients also show a predisposition to second neoplasms not related to therapy. In vitro studies on the radiation response of cells from retinoblastoma patients have generated conflicting results. Some laboratories, including our own, find that survival following ionizing irradiation of fibroblasts is within the normal range, other laboratories find an abnormal decrease in cell survival. X-ray-induced chromosome damage in G0-irradiated lymphocytes was slightly elevated compared to control subjects. Recent studies using chromosome 13 genetic markers suggest that retinoblastoma tumour cells are homo- or hemi-zygous for the mutant retinoblastoma gene. It seems unlikely that the mutant gene causes sensitivity to ionizing radiation but any tendency to chromosomal rearrangement in a gene carrier would increase the probability of tumour development.     

Conformational studies on actinomycin

A model of the Actinomycin structure is derived on the basis of theoretical calculations taking into account available IR, NMR and x-ray experimental data. This model contains two intercycle hydrogen bonds and accounts for all the experimental evidence.     

Structural studies on rhodopsin

Bovine rhodopsin is the prototypical G protein coupled receptor (GPCR). It was the first GPCR to be obtained in quantity and studied in detail. It is also the first GPCR for which detailed three dimensional structural information has been obtained. Reviewed here are the experiments leading up to the high resolution structure determination of rhodopsin and the most recent structural information on the activation and stability of this integral membrane protein.     

Cytotaxonomical studies on AsianAnnonaceae

Chromosome numbers of 42 species and 3 varieties from 24 genera of theAnnonaceae have been determined (Table 1); reports for 15 of the genera are new. Among Asian genera 2n = 14 occurs only in the specializedMezzettia, while 2n = 16 is wide-spread and also has been found inAnaxagorea with some primitive characters. 2n = 18 is reported for 11 genera, and tetraploidy (2n = 36) has been observed inPolyalthia. Therefore, an original basic number of x = 8 or x = 9 is suggested at least for the Asian genera of theAnnonaceae.—Cytotaxonomical notes on the critical speciesPolyalthia rumphii andP. affinis are given, and the new combinationNeouvaria parallelivenia (Boerl.)Okada & Ueda is proposed.     

Morphological studies on neuroglia

Summary Autoradiographic studies showed that in the rat hippocampus microglia-like reactive cells (MRC) and astrocytes are capable of proliferation in response to kainic acid (KA)-induced lesions. A marked increase in the number of labeled MRC was observed during the first four days after the induction of the KA-lesion. A proliferative response of astrocytes occurred at two days after the KA-lesion. After the induction of a KA-lesion brain macrophages and oligodendrocytes were only slightly labeled with ³H-thymidine. It appears likely that MRC is the main cellular element responding to this type of lesion.This work was supported by a grant (No. 437002) from the Ministry of Education, Science and Culture, Japan     

Production studies on protozoa

Summary In the river Saale and in the terrestrial moss Mnium cuspidatum Leyss. in 1974/75 the annual production of Testacea and loricate ciliated protozoa were investigated.The production was estimated in the Saale-Aufwuchs on a -meso ... oligosaprobic (Kaulsdorf, Thuringia, GDR) and on a -mesosaprobic (Rothenstein, Thuringia, GDR) area of the river. The mosses were investigated in a forest near Jena.The production was estimated on slides and in special productionchambers; the time of exposure was 2 weeks. Investigations concerned annual production of individuals and biomass, the ratio of annual production/standing crop (P/B), numbers of generations per year (G) and mortality (M%/d). In the mosses, the rainfall modified the production and dislocation of the protozoa.The values for production are: Aufwuchs Saale (-meso... oligosaprobic): 24·10⁶ i/m²·a (=1,0 g/m²·a=79·10³ i/m²·d); P/B: 12.6. Aufwuchs Saale (-mesosaprobic): 3.2·10⁶ i/m²·a (=0.35 g/m²·a=81·10³ i/m²·d); P/B: 34.9; G: 22; M: 5%/d. Moss: 145·10⁶ i/m²·a (=0.11 g/m²·a=40.6·10³ i/m²·d); P/B: 8.1; G: 16.5; M: 3.0%/d.     

Countercurrent-distribution studies on histones

1. The possibilities of fractionating histones and histone fractions by means of countercurrent distribution between two phases formed by water and butan-2-ol, in the presence of various concentrations of trichloroacetic acid, have been examined. 2. Although the principal histone fractions differ considerably in their partition ratios, a satisfactory resolution of the principal histone fractions from the whole histone has not been achieved. 3. The histone fractions obtained by other methods can be resolved with suitable concentrations of trichloroacetic acid. Besides the main peak several subsidiary peaks are obtained in most cases, the composition of which corresponds with others of the main fractions. 4. The method is therefore capable of removing from the principal fractions as previously prepared contamination by other fractions. 5. Except in one case, no fraction with composition unlike other fractions has been obtained. In several cases the material isolated from the principal peak behaves as a single component on running again. In two cases fractions with similar compositions were distinguished by countercurrent distribution.     

Anatomical studies on ectomycorrhizas

Ectomycorrhizas of 5-month-old Pinus patula plants grown in autoclaved shola soil (forest soil) inoculated with basidiospores of Amanita muscaria, Laccaria laccata and Suillus brevipes are described. The main em phasis is on the organisation of the mantle tissue as seen in plan view and features of associated hyphae and strands. The different layers in the mantle produced by the different fungi are described and illustrated.