Effect of pressure on the sol-gel transition of carrageenans

The effects of pressure on the sol-gel transition of κ- and ι-carrageenans were studied in KCl solutions under high pressures up to 3000 kg/cm². The carrageenan gels were destabilized by pressure: the pressure depression of melting temperature, (dT/dP)_m, was ?5.7 × 10^?3 and ?4.0 × 10^?3 K cm²/kg independent of KCl concentration for κ- and ι-carrageenans, respectively. The enthalpy, entropy and volume changes accompanying the gel formation were calculated from the Eldridge-Ferry's plots and the Clausius-Clapeyron equation. The volume change per unit cross-link (two disaccharide residues) was estimated to be (2.5 ～ 4.9) and (1.7 ～ 3.4) ml/mol for κ- and ι-carrageenans, respectively. The compressibility of both carrageenan molecules appeared to be larger by (1.6 ～ 2.6) × 10^?12 (κ-form) and by (0.8 ～ 1.3) × 10^?12cm²/dyn (i-form) in gel state as compared with in sol state These increases in volume and compressibility on gelation were attributed to a reduction of water of hydration from the carrageenan molecules, which is mainly due to a replacement of the polymer-water hydrogen bond by the polymer-polymer hydrogen bond. These results seemed not inconsistent with the idea that a double helix structure of carrageenan gels may persist in solution as well as in the solid state.     

Social behavior of early emerging males of a Japanese paper wasp,Polistes chinensis antennalis (Hymenoptera: Vespidae)

Summary Five cases of the early emergence of males in a Japanese paper wasp,Polistes chinensis antennalis, in which male emerged together with the first group of workers, were described. In one case of the five where the queen disappeared before the emergence of male, worker(s) produced female offspring. The frequency of the nests where the early emergence of male was observed was 16.7% (5/30 nests). In two colonies, worker(s) and/or queen chased off males. But in an orphan nest where worker(s) produced female offspring, the dominance order among workers which was similar to that of colony without male was observed. The significance of the early emergence of male in the social evolution of wasps was discussed.     

The Genetic System Controlling Homothallism in Saccharomyces Yeasts

There are four types of life cycles in Saccharomyces cerevisiae and its related species. A perfect homothallic life cycle (the Ho type) is observed in the classic D strain. Two other types show semi-homothallism; one of them shows a 2-homothallic diploid:2alpha heterothallic haploid segregation (the Hp type) and another, a 2-homothallic:2a segregation (the Hq type). In the segregants from these Ho, Hp, and Hq diploids, each homothallic segregant shows the same segregation pattern as its parental diploid. The fourth type has a heterothallic life cycle showing a 2a:2alpha segregation and the diploids are produced by the fusion of two haploid cells of opposite mating types. The diploids prepared by the crosses of alpha Hp (an alpha haploid segregant from the Hp diploid) to a Hq (an a haploid from the Hq diploid) segregated two types (Type I and II) of the Ho type homothallic clone among their meiotic segregants. Genetic analyses were performed to investigate this phenomenon and the genotypes of the Ho type homothallic clones of Type I and Type II. Results of these genetic analyses have been most adequately explained by postulating three kinds of homothallic genes, each consisting of a single pair of alleles, HO/ho, HMalpha/hmalpha, and HMa/hma, respectively. One of them, the HMalpha locus, was proved to be loosely linked (64 stranes) to the mating-type locus. A spore having the HO hmalpha hma genotype gives rise to an Ho type homothallic diploid (Type I), the same as in the case of the D strain which has the HO HMalpha HMa genotype (Type II). A spore having the a HO hmalpha HMa or alpha HO HMalpha hma genotype will produce an Hp or Hq type homothallic diploid culture, respectively. The other genotypes, a HO HMalpha hma, alpha HO hmalpha HMa, and the genotypes combined with the ho allele give a heterothallic character to the spore culture. A possible molecular hypothesis for the mating-type differentiation with the controlling elements produced by the HMalpha and HMa genes is proposed.     

Molecular structure of the replication origin of a Bacillus amyloliquefaciens plasmid pFTB14

Summary The structure of a 1.5-kb DNA sequence that is necessary and sufficient for the replication of an 8.2-kb cryptic plasmid, pFTB14, isolated from a strain of Bacillus amyloliquefaciens has been characterized. The 1.5-kb DNA sequence contains an open reading frame, rep, stretching for 1017 bp, a promoter region for rep expression, and a possible replication origin for the plasmid upstream of the promoter. The rep product is trans-active and essential for plasmid replication. The predicted rep protein is a basic protein, as are the RepC protein of pT181, RepB of pUB110 and protein A of pC194 (all these found in staphylococci) and the protein of the R6K plasmid of Escherichia coli. The predicted rep protein has highly homologous amino acid sequences with protein A of pC194 and RepC of pUB110 throughout the protein molecule, but not with RepC of pT181, of R6K or protein RepH encoded by and iniating the replication of pC194.     

The elevation of the cytoplasmic calcium ions in vascular smooth muscle cells in SHR--measurement of the free calcium ions in single living cells by lasermicrofluorospectrometry

We have developed an accurate and sensitive system for the measurement of cytoplasmic free calcium concentrations ([Ca++]i) of a single cell by using UV-laser and Indo-1. By this method, we made the first successful measurement of [Ca++]i of single living vascular smooth muscle cells. [Ca++]i in spontaneously hypertensive rats was elevated and maintained after the 6th passage culture. However, [Ca++]i in Goldblatt hypertensive rats was not elevated. Thus, these results suggest that the maintenance of high [Ca++]i levels of vascular smooth muscle cells in spontaneously hypertensive rats is genetically regulated and that it is one of the mechanisms for hypertension.     

The laser method for efficient introduction of foreign DNA into cultured cells

A minute hole upon a cultured cell, perforated with a finely focused laser beam, was found to repair itself within a short period of time. The procedure constitutes a new way of introducing exogenous gene materials dissolved in medium into cells. The 'laser-aided' DNA transfection is better than the existing methods because it allows the treatment of a large number of cells in a shorter time, and an improved success rate.     

Regio-Selective 10-Hydroxylation of Patchoulol, a Sesquiterpene, by Pithomyces Species

Of some 350 microorganisms screened, four strains of Pithomyces species were found to carry out regio-selective hydroxylation of patchoulol, a sesquiterpene, to 10-hydroxypatchoulol: Pithomyces sp. NRJ201, P. chartarum NRJ210, and, to a lesser extent, P. cynodontis ATCC 26150 and P. atro-olivaceus IFO 6651 were found to catalyze this reaction. A method has been developed by which 10-hydroxypatchoulol was obtained in 25 to 45% yields in 1- to 5-liter fermentation jars at 2 to 4 g of patchoulol per liter and isolated as pure material in 30% yields.