Evidence for autophosphorylation of hyaluronate binding protein and its enhanced phosphorylation in rat histiocytoma.

This report documents for the first time the in vitro autophosphorylation of purified 68 kDa hyaluronate binding protein in presence of [32P] ATP. The rate of phosphorylation is proportional to the concentration of protein and to the time of incubation up to 5 min. By both phosphoamino acid and western blot analysis with antiphosphotyrosine antibodies, we have confirmed that the phosphorylation occurs at tyrosine residues. Immunoprecipitation with anti HA binding protein antibody shows a 5 fold increase in the phosphorylation in macrophage histiocytoma compared to normal macrophage. Supplementing hyaluronate with hyaluronate binding protein in the medium is further shown to enhance total protein phosphorylation in rat histiocytoma.     

Evolutionarily conserved regions in Caenorhabditis transposable elements deduced by sequence comparison.

In this paper we present the sequence of an intact Caenorhabditis briggsae transposable element, Tcb2. Tcb2 is 1606 base pairs in length and contains 80 base pair imperfect terminal repeats and a single open reading frame. We have identified blocks of T-rich repeats in the regions 150-200 and 1421-1476 of this element which are conserved in the Caenorhabditis elegans element Tc1. The sequence conservation of these regions in elements from different Caenorhabditis species suggests that they are of functional importance. A single open reading frame corresponding to the major open reading frame of Tc1 is conserved among Tc1, Tcb1, and Tcb2. Comparison of the first 550 nucleotides of the sequence among the three elements has allowed the evaluation of a model proposing an extension of the major open reading frame. Our data support the suggestion that Tc1 is capable of producing a 335 amino acid protein. A comparison of the sequence coding for the amino and carboxy termini of the 273 amino acid transposase from Caenorhabditis Tc1-like elements and Drosophila HB1 showed different amounts of divergence for each of these regions, indicating that the two functional domains have undergone different amounts of selection. Our data are not compatible with the proposal that Tc1-related sequences have been acquired via horizontal transmission. The divergence of Tc1 from the two C. briggsae elements, Tcb1 and Tcb2, indicated that all three elements have been diverging from each other for approximately the same amount of time as the genomes of the two species.     

Mutagenic activity of antibiotics alone and in conjunction with alkanesulfonates

Differential and combined effects of 0.25 and 0.50% antibiotics (ampicillin, neomycin, furadentine) and alkylating agents (ethyl methanesulfonate, methyl ethanesulfonate, methyl methanesulfonate) were assayed on Phaseolus vulgaris L. (2 n = 22) at the M₂ generation for chlorophyll mutations. The general types scored were Albino, Xantha, Virescens and Maculata. Yellowish-green leaves having red mid-veins and veinlets were observed only amongst the progeny raised after treatment with 0.25% ethyl methanesulfonate or 0.25% methyl ethanesulfonate + 0.25% ampicillin. The frequency of chlorophyll mutation after combined treatments in general was higher than after differential treatments. Methyl methanesulfonate among alkanesulfonates and neomycin among antibiotics induced higher frequencies of chlorophyll mutations. No chlorophyll mutant was produced by ampicillin.Although antibiotics induced a lower frequency of chlorophyll mutation than alkylating agents, the frequency and pattern of spectra of chlorophyll mutants showed an action of antibiotics in inducing mutation similar to that of alkylating agents. Therefore, it is considered that antibiotics are potential mutagens.     

Cyclo (His-Pro): a selective inhibitor of rat prolactin secretion in vitro

Cyclo (His-Pro) (10 ng/ml), inhibits KCl (59 mM) or thyrotropin-releasing hormone (10 ng/ml) stimulated, but not basal, release of prolactin from rat hemipituitaries $\text{in vitro}$. However, cyclo (His-Pro) has no effect on the basal or stimulated release of thyrotropin and growth hormone. Cyclo (His-Pro) does not inhibit the binding of thyrotropin-releasing hormone to pituitary membrane suggesting that cyclo (His-Pro) inhibition of prolactin release is not mediated via the pituitary TRH-receptor.     

Morphological and cytological investigations ofUlothrix zonata and taxonomy of the related species

The present communication deals with the observations made on the morphology, reproduction and cytology ofUlothrix zonata (Weber & Mohr)Kütz. in culture. The alga displays a remarkable phenotypic plasticity in nature as well as in culture. The present study provides additional evidence of karyology in support ofLokhorst andVroman's treatment ofU. zonata which merges a number of earlier described species in it. The cytological details and chromosome number (n = 10) determined for the Indian isolates ofU. zonata agree with those ofSarma for the British material.NBRI Research Publication No. 63 (N.S.)     

Contact inhibition of locomotion and the structure of homotypic and heterotypic intercellular contacts in embryonic epithelial cultures

Epithelia from the early chick embryo have been grown in culture and then fixed for electron microscopy so that the ultrastructure of intercellular contacts could be examined. Epithelia were used which showed various forms of contact inhibition of locomotion upon confrontation with one another. Confrontations of hypoblast with hypoblast after 6 days, and endoblast with endoblast after 24 h showed type 1 contact inhibition and formed desmosomes and zonulae adhaerentes with extensive microfilament collinearity between apposed cells. Hypoblast-hypoblast confrontations after 24 h resulted in type 2 contact inhibition with considerable ruffling and position shifting. In this case desmosomes were absent and microfilament collinearity was restricted. Endoblast cells after 24 h in culture show type 2 inhibition with respect to hypoblast monolayers which they infiltrated upon confrontation. Examination of these heterotypic contacts also showed an absence of desmosomes and reduced adhaerens junctions. Intermediate filaments accumulated at all contact sites examined. It is concluded that whereas type 1 contact inhibition of locomotion in these epithelial cells is accompanied by desmosome formation and extensive zonula adhaerens junctions, type 2 inhibition is not. These junctional deficiences may be responsible in part for the cell motility characteristically observed in monolayers of type 2 inhibited cells.     

Effect of long term starvation on the biochemical composition of the muscles and hepatopancreas in the crab Menippe rumphii (Fabricius) (Crustacea: Brachyura)

During the process of long term starvation both muscles and hepatopancreas are affected in their biochemical composition at different rates. During early days of starvation an increase in the muscular and hepatopancreatic glycogen is observed. At the same time a simultaneous decrease in the muscular lipid content is also observed. At a slightly later period a decrease in the hepatopancreatic lipid content is also noticed. This amount of decrease is slow in the early days of starvation and rapid in later days. Decrease in the muscular and hepatopancreatic protein content is observed when there is not an adequate quantity of hepatopancreatic lipid to be consumed.