Chemical modification of cytosine residues of U6 snRNA with hydrogen sulfide (nucleosides and nucleotides. Part 49 [1]).

Sulfhydrolysis of cytosine residues to 4-thiouracil residues in mouse U6 snRNA was carried out to examine the secondary structure of U6 snRNA. The cytosine residues at positions 6, 42 and 68 were modified significantly, and at positions 11, 19 (or/and 25), 61 and 66 in moderate extent. Based on the result, the plausible secondary structure of U6 snRNA is discussed.     

Statistical measurement of signal transmission in the central nervous system of the crayfish

Summary Transmission of nerve signals in the crayfish brain was studied by means of the transfer function derived from input-output analysis with random stimulation. The transfer function was measured in the form of frequency-response-function and represented by Bode plot. Two classes of the frequency-response-functions were discriminated, corresponding to two types of response patterns evoked by the constant frequency stimuli. The first type had the characteristics of a band pass filter similar to an underdamped resonant circuit. The second one had the characteristics of a phase lag circuit, occasionally, with additional small positive or negative peak at almost the same frequency as the resonance of the first type. A few possibilities for the resonance and the phase lag mechanisms were discussed.     

Cyclical changes in the fine structure of bovine endometrial gland cells

Summary Cyclical changes in bovine endometrial gland cells were investigated in six heifers, three at estrus and three at day twelve of the estrous cycle in the luteal phase. The epithelium is generally low at estrus but high in the luteal phase. There are ciliated and non-ciliated cells. The ciliated cells are fewer and lighter and show inconspicuous cyclical changes.The secretory cells show more prominent changes. At estrus, their free border is flat with short microvilli. The conspicuous rough-surfaced endoplasmic reticulum may synthesize protein for later secretion. The Golgi complex seems inactive. The high number of cytosegresomes and dense bodies might express cell regression caused by endocrine changes.In the luteal phase, the cells are lighter with long microvilli. The Golgi apparatus shows vacuoles and immature secretory droplets. Secretory vacuoles with light contents occur in the apical cytoplasm. Some of them appear to discharge their contents into the lumen. This is interpreted as evidence of merocrine secretion. Accumulations of tubular, smooth-surfaced endoplasmic reticulum, masses of glycogen granules, and several fat droplets are present.Some lymphocytes and degranulated granulocytes are seen near the basement membrane, more frequently at estrus.Financial support for this study was received from Anslaget för främjande av medicinsk forskning vid Veterinärhögskolan.The authors express their gratitude to Prof. A. Bane and Dr. J.-E. E. Ringmar, Department of Obstetrics and Gynecology, for their help with the selection and clinical control of the animals and for keeping them in good condition.Post doctoral fellow, No. 43-KO-52 (1968) from the Educational Ministry of Japan.     

Nucleic Acid Metabolism Involved in Auxin-induced Elongation of Yeast Cells

The following results were obtained using a variant yeast strain, N55, which can respond to the cell-elongating action of auxin. Base analogs of nucleic acids (2-thiouracil, 8-azaguanine, and 5-fluorouracil) inhibited the auxin-induced elongation of yeast cells only when they were added to the preculture prior to auxin treatment. The inhibitory effect of 2-thiouracil and 5-fluorouracil was reversed by uracil and that of 8-azaguanine by guanine. Actino-mycin D inhibited the auxin-induced elongation when given to the culture containing auxin, but not when given to the preculture. The similarity in these respects between yeast and tissues of higher plants is discussed.     

FINE STRUCTURE OF THE OCTOPUS RETINA

The fine structure of the visual and the supporting cells and of the blood capillaries in the octopus retina is described. Lamellated structures contained in the proximal segment of the visual cell consist of compact arrays of dense membranes each of which is quintuple-layered and divides at its margins into two thinner sheets or membranes which are connected directly with the agranular or granular endoplasmic reticulum. Proximal to the deeper extremities of the rhabdomeres, the lateral plasma membranes of two adjoining visual cells contact each other forming a quintuple-layered compound membrane, which results in occlusion of the intercellular space. The central layer of the compound membrane is of high density, so that the membrane, as a whole, appears to be a single thick layer at low magnifications. The supporting cells are connected with the neighboring visual cells by two types of junctions. Long slender processes extend from the supporting cells to the surface of the retina through narrow spaces among the distal segments of the visual cells. The capillary endothelial cells are characterized by luminal surfaces irregularly contoured and by lateral surfaces elaborately interdigitated. The functional significance of the close contact between adjoining visual cells is discussed.     

Comparison of enzyme phenotypes in human bladder tumours and experimentally induced hyperplastic and neoplastic lesions of the rat urinary bladder. A combined histochemical and immunohistochemical approach

The expression of a number of enzymes involved in drug metabolism, membrane function etc. was compared in hyperplastic and neoplastic lesions of the rat bladder and in human bladder tumours. Transitional cell carcinomas (TCC) in both rat and Man were characterized by decreased alkaline phosphatase (ALP) and increased gamma-glutamyl transpeptidase (GGT), beta-glucuronidase (beta-G1), succinate dehydrogenase (SD) and glucose-6-phosphate dehydrogenase (G6PD) activities. In addition, binding for antibodies specific for different cytochrome P-450 species (UT50, PB3a, MC1, MC2) and microsomal epoxide hydrolase (mEHb) was elevated in both murine and human tumours. Comparison of the enzyme phenotype in hyperplastic lesions induced by freeze ulceration or uracil administration with that in preneoplastic papillary or nodular hyperplasia (PNH) and TCC suggested, however, that most of the alteration in enzyme content or activity was non-specific and related to requirements for epithelial cell proliferation. On the other hand, the decreased ALP, and increased GGT and beta-G1 activity appeared more directly related to neoplastic transformation. The results suggested that qualitative differences exist between reactive hyperplasia and preneoplastic or neoplastic lesions in the urinary bladder. The finding of increased cytochrome P-450, in clear contrast to the reduction characteristic of preneoplastic hepatic lesions, may be important with regard to the observed difference in neoplastic transformation between the bladder and liver in response to drug metabolising enzyme inducers.     

Molecular analysis of a plasmid-encoded phenol hydroxylase from Pseudomonas CF600

Pseudomonas strain CF600 is able to utilize phenol and 3,4-dimethylphenol as sole carbon and energy source. We demonstrate that growth on these substrates is by virtue of plasmid-encoded phenol hydroxylase and a meta-cleavage pathway. Screening of a genomic bank, with DNA from the previously cloned catechol 2,3-dioxygenase gene of the TOL plasmid pWW0, was used in the identification of a clone which could complement a phenol-hydroxylase-deficient transposon insertion mutant. Deletion mapping and polypeptide production analysis identified a 1.2 kb region of DNA encoding a 39.5 kDa polypeptide which mediated this complementation. Enzyme activities and growth properties of Pseudomonas strains harbouring this fragment on a broad-host-range expression vector indicate that phenol hydroxylase is a multicomponent enzyme containing the 39.5 kDa polypeptide as one component.     

Presence and activity of alkaline phosphatase in two human osteosarcoma cell lines

The presence and activity of alkaline phosphatase in SAOS-2 and TE-85 human osteosarcoma cells grown in culture were examined at the ultrastructural level. A monoclonal antibody raised against purified human bone osteosarcoma alkaline phosphatase was used to localize the enzyme in cultures of the osteosarcoma cells. Similar cultures were analyzed for alkaline phosphatase activity using an enzyme cytochemical method with cerium as the capture agent. Alkaline phosphatase was immunolocalized at the light microscopic level in an osteogenic sarcoma and ultrastructurally on the SAOS-2 cell membrane and the enclosing membrane of extracellular vesicular structures close to the cells. In contrast, the TE-85 cells were characterized by the absence of all but a few traces of immunolabeling at the cell surface. Enzyme cytochemical studies revealed strong alkaline phosphatase activity on the outer surface of the SAOS-2 cell membrane. Much lower enzyme activity was observed in the TE-85 cells. The results support biochemical data from previous studies and confirm that SAOS-2 cells have a significantly greater concentration of alkaline phosphatase at the plasma membrane.     

Stimulatory effect of glycine betaine on l-lysine fermentation

Summary The growth rate, sugar consumption rate, and production rate of an l-lysine producing Brevibacterium lactofermentum mutant were stimulated by addition of exogenous glycine betaine. Glycine betaine stimulated the growth rate especially in media of inhibitory osmotic stress, and the stimulation was independent of any specific solute. Therefore growth stimulation by glycine betaine was considered to be an osmoprotective effect. A strong enhancement of the sugar consumption rate and the l-lysine production rate was observed even with resting cells under osmotic stress as well as in a fermentation with growing cells. These data indicated that the osmoprotective effects of glycine betaine on l-lysine production can be independent of protein synthesis. Offprint requests to: Yoshio Kawahara