Temperature control on the post-embryonic growth of Neomysis intermedia Czerniawsky in a hypereutrophic temperate lake

In situ growth of Neomysis intermedia Czerniawsky at the post-embryonicstage was studied by the cohort analysis using the probabilitygraphic technique in a hypereutrophic temperate lake, Lake Kasumigaura.Two overwintering populations and 5 spring cohorts were recognizedover 2-yr field observations performed at 4–15 day intervals.There was no luck in order to follow possible cohorts in mid-summerand autumn. The specific growth rate of the post-embryonic stagedetermined varied between 0.001 and 0.16 (day ^–1) dependingupon the surrounding water temperature, and each individualgrowth showed an almost exponential pattern. Average size ofnew born individuals was {small tilde}2.1 mm in body lengthand was consistent regardless of the difference of seasons,but the average mature size was highly temperature dependent,ranging between 7.6 and 12.0 mm for males and 8.1 and 13.5 mmfor females.     

Molecular cloning and sequencing of cDNA encoding the phosphatidylinositol kinase from rat brain.

A complementary DNA (cDNA) clone that encodes phosphatidylinositol 4-kinase (PI 4-kinase) was isolated from a rat brain cDNA library. The deduced amino acid sequence of 697 residues revealed that the protein contains two putative transmembrane sequences and that the N-terminal part of the protein has several sequences representing potential phosphorylation sites for cAMP- and calmodulin-dependent kinase. The C-terminal region is probably a phosphotransferase domain homologous to the kinase region of protein kinase family proteins. Specific antibody against the protein expressed in Escherichia coli successfully immunoprecipitated rat brain PI 4-kinase. The messenger RNA for PI 4-kinase was found predominantly in brain and rat neural cell lines. This PI kinase may play a specific role in neural signal transduction.     

Isolation and characterization of hemidesmosomes from bovine corneal epithelial cells

The hemidesmosome (HD) is a specialized cell-to-substratum junction of stratified and complex epithelia which is characterized by a cytoplasmic plaque to which intermediate filaments (IFs) are anchored. To identify and characterize HD constituents systematically, we have developed a procedure to isolate and fractionate HDs. When bovine corneal epithelium is peeled off from the extracellular matrix stroma, HDs attached to the basal lamina are left behind, together with tufts of cytokeratin IFs attached to the cytoplasmic HD plaques. After rinsing these residual basal cell elements with EDTA, the HDs could be mechanically detached from the stroma and collected by centrifugation. The fraction obtained was examined biochemically and electron microscopically, showing enrichment of HD structures as well as of a prominent 230-kDa polypeptide, the "pemphigoid antigen" known to be located in the HD plaque. In addition, the HD fraction revealed, besides residual amounts of corneal cytokeratins, major polypeptides of Mr 120, 180, 200, 230, and 480 kDa, of which the first three appeared to be glycoproteins. Using the isolated HDs for immunization, we prepared monoclonal antibodies specific for the 230- and 180-kDa polypeptides, respectively, and showed that both were exclusively located in HDs. This method for isolating HDs and the availability of antibodies to HD proteins will be useful in studies of the molecular organization of HDs and make HD research independent from human autoimmune antibodies.     

Relationship of actin organization to growth in the two forms of the dimorphic yeastCandida tropicalis

Summary Candida tropicalis is a dimorphic yeast capable of growing both as a budding yeast and as filamentous hyphae depending upon the source of the carbon used in the culture medium. The organization of F-actin during growth of the yeast form (Y-form) and the hyphal form (H-form) was visualized by rhodamine-conjugated phalloidin by using a conventional fluorescence microscope as well as a laser scanning confocal fluorescence microscope. In single cells without a bud or non-growing hyphae, actin dots were evenly distributed throughout the cytoplasm. Before the growth of the bud or hypha, the actin dots were concentrated at one site. During bud growth, actin dots were located solely in the bud. They filled the small bud and then filled the apical two-thirds of the cytoplasm of the middlesized bud. During growth of the large bud, actin dots which had filled the apical half of the cytoplasm gradually moved to the tip of the bud. In the formation of the septum, actin dots were arranged in two lines at the conjunction of the bud and the mother cell. During hyphal growth, the majority of actin dots were concentrated at the hyphal apex. A line of clustered spots or a band of actin was observed only at the site where the formation of a new septum was imminent. This spatial and temporal organization of actin in both categories of cells was demonstrated to be closely related to the growth and local deposition of new cell wall material by monitoring the mode of growth with Calcofluor staining. Treatment of both forms of cells with cytochalasin A (CA) confirmed the close relationship between actin and new cell wall deposition. CA treatment revealed lightly stained unlocalized actin which was associated with abnormal cell wall deposition as well as changes in morphology. These results suggest that actin is required for proper growth and proper deposition of cell wall material and also for maintaining the morphology of both forms of cells.Abbrevations FM fluorescence microscopy - EM electron microscopy - rh rhodamine - CA cytochalasin A - CD cytochalasin D - PBS phosphate-buffered saline - DMSO dimethylsulfoxide - GA glutaraldehyde     

Improved culture conditions for somatic embryogenesis from Asparagus officinalis L. using an aseptic ventilative filter

Summary Calli were induced from the crown of seedlings or lateral bud of young spears of Asparagus officinalis L. on Linsmaier and Skoog's (LS) solid-medium supplemented with 5 M 2,4-dichlorophenoxyacetic acid (2,4-D). Embryogenic callus was selected from induced calli and proliferated in LS liquid medium supplemented with 5 M 2,4-D. Non-vitrified somatic embryos were formed and efficiently developed into club-shaped embryos in LS hormone-free medium with 1 % gelrite in a culture vessel capped with an aseptic ventilative filter. Non-vitrified club-shaped embryos developed into normal plants when transferred to half-strength LS medium without hormones, and 0.8 % agar. Carbon dioxide concentration and moisture content inside the culture vessels were measured, and their effect on embryo development is discussed.     

Transformation of hemoglobin a into methemoglobin by sesamol

Sesamol (3,4-methylenedioxyphenol), a monophenolic antioxidant in sesame iol, produced methemoglobin from hemoglobin A (oxyhemoglobin and deoxyhemoglobin) and from red cells. The activity of the compound was more extensive than the polyphenolic compounds. The profiles of the methemoglobin formation by the compound were compared with those by nitrite and hydroxylamine. The formation of methemoglobin from oxyhemoglobin by the compound was rather slowly progressed, but the amount of methemoglobin formed was proportional to the concentration of oxyhemoglobin even when the concentration of the compound was low. The sesamol-induced methemoglobin formation was influenced by inositol hexaphosphate, an allosteric effector of hemoglobin. Thus, the phosphate enhanced the transformation of oxyhemoglobin and inhibited the transformation of deoxyhemoglobin.     

Duration of activity of the acid, methyl ester and amide of an orally active platelet aggregation inhibitory prostanoid in the rat

The prostanoid 3-oxa-4,5,6-trinor-3,7-inter- -phenylene PGE₁ (OI-PGE₁) has been shown to be a more potent inhibitor of ADP-induced human platelet aggregation than PGE₁. OI-PGE₁ inhibits ex vivo ADP-induced platelet aggregation for 60 minutes after an oral dose of 20 mg/kg to rats. Present studies compare duration of ex vivo inhibition to ADP-induced platelet aggregation in the rat by OI-PGE₁, its methyl ester and amide after administration by various routes. All oral (p.o.) and intraduodenal (i.d.) doses were 20 mg/kg and all intravenous (i.v.) doses were 1 mg/kg. OI-PGE₁ and its methyl ester had the same duration of activity after i.v. (60 min.) and p.o. (60 min.) administration, however, the methyl ester, when administered i.d., had a longer duration of activity than the free acid i.d. (>90 min. vs. 60 min.). OI-PGE₁-amide had significantly longer duration than the acid or methyl ester after i.v. (>120 min.), p.o. (>240 min.) or i.d. (>240 min.) administration. Present data suggest that in the rat (1) intestinal absorption of OI-PGE₁-methyl ester is more efficient than it is for the free acid and (2) due to metabolic and/or distributional differences between OI-PGE₁ and its amide, the amide has a much greater duration of activity.     

Purification and properties of the Bombyx mori nuclear polyhedrosis virus liberated from polyhedra by dissolution with silkworm gut juice

Occluded virions of the Bombyx mori nuclear polyhedrosis virus were efficiently liberated from polyhedra by dissolution with the silkworm gut juice. The liberated virions were purified by sucrose density gradient centrifugation and the bands of enveloped virions were observed in the gradients. There was no functional difference between the gut juice-liberated and the carbonate-liberated virions. Disruption of enveloped virions by the gut juice was observed, but the formation of nucleocapsids from the degradation of the occluded virions was not detected. High yields of the enveloped virions from the polyhedra dissolved by the gut juice was obtained by separating the virions through sucrose density gradient centrifugation immediately after the dissolution of the polyhedra. Many factors, e.g., rearing seasons, silkworm strains, and rearing conditions, affect the polyhedra-dissolving property of the larval gut juice.     

Changes in the organization and biosynthesis of cell surface acidic sugars during the phytohemagglutinin-induced blast formation of human T-lymphocytes

Use of cell electrophoresis combined with specific enzymes and varying ionic strength revealed a topological change of acidic sugars in lymphocyte membrane treated with a T-cell mitogen, phytohemagglutinin (PHA). The suggested alterations were an early translocation of hyaluronic acid to the cell periphery within 15 min of PHA addition and, 4 h later, the appearance of chondroitin sulphate in T-lymphocytes, but not in B-lymphocytes. As the contribution of chondroitin sulfate to the electrophoretic mobility increased with time up to 24 h, that of sialic acid decreased conversely. Several agents which block blast formation (2 mM ethylene glycol bis-β-aminoethylethyl-N,N,N′,N′-tetraacetic acid, 2 × 10⁻⁷ M ouabain, 0.1 μg/ml colchicine and 1 μg/ml cytochalasin B) also blocked the translocation of hyaluronic acid at the same concentrations. Chemical analysis of [¹⁴C]glycosaminoglycans by means of gel filtration followed by paper chromatography revealed a four-fold enhancement of the biosynthesis of chondroitin sulfate C after PHA stimulation. The presence of chondroitin sulfate in the cell periphery was also detected electrophoretically in T-cell type leukemia cells (MOLT-4B). These results suggest that the reorganization of glycosaminoglycans may be one of the membrane changes associated with blast formation of lymphocytes.     

Difference in the mechanisms of poly(dT) synthesis by DNA polymerases beta and gamma.

Poly(dT) products which were synthesized depending on (rA)n . (dT)12-18 as a template . primer by mammalian DNA polymerases beta and gamma were analyzed by alkaline sucrose gradient centrifugation. The size of the population of poly(dT) chains synthesized by DNA polymerase beta increased slowly and consistently during incubation up to at least 30 min. On the other hand, the product size with DNA polymerase gamma reached the final size (7 s) within 5 min and the number of products increased during further incubation. Comparison of product number per enzyme molecule suggests that DNA polymerase beta acts on multiple primers in a distributive fashion while DNA polymerase gamma completes poly(dT) chains of large size in a one-by-one fashion.