The basic property of biomembranes

In order to explain the experimentally obtained results with biomembranes it has been assumed, that the diameter of all vesicles, defined by a lipid bilayer, form a perfect crystal. Later on it appeared that biomembranes are liquid crystals. Nevertheless already with biomembranes as crystals it was possible to calculate the diameters of all existing vesicles. As shown in the present paper, the results with liquid crystals were identical to those with a perfect crystal-model. Here I demonstrate that the geometric progression of the diameters of vesicles of biomembranes is based on the entropy of the lipids and it is shown that the diameters of biomembranes fit four geometric series. The surface areas of these series of biomembranes can be approximated by the two geometric series published previously. The experiments and the theoretical studies on which this work is based have been carried out at the Netherlands Cancer Institute, Amsterdam, The Netherlands.     

Rational Engineering of Recombinant Picornavirus Capsids to Produce Safe,Protective Vaccine Antigen

Foot-and-mouth disease remains a major plague of livestock and outbreaks are often economically catastrophic. Current inactivated virus vaccines require expensive high containment facilities for their production and maintenance of a cold-chain for their activity. We have addressed both of these major drawbacks. Firstly we have developed methods to efficiently express recombinant empty capsids. Expression constructs aimed at lowering the levels and activity of the viral protease required for the cleavage of the capsid protein precursor were used; this enabled the synthesis of empty A-serotype capsids in eukaryotic cells at levels potentially attractive to industry using both vaccinia virus and baculovirus driven expression. Secondly we have enhanced capsid stability by incorporating a rationally designed mutation, and shown by X-ray crystallography that stabilised and wild-type empty capsids have essentially the same structure as intact virus. Cattle vaccinated with recombinant capsids showed sustained virus neutralisation titres and protection from challenge 34 weeks after immunization. This approach to vaccine antigen production has several potential advantages over current technologies by reducing production costs, eliminating the risk of infectivity and enhancing the temperature stability of the product. Similar strategies that will optimize host cell viability during expression of a foreign toxic gene and/or improve capsid stability could allow the production of safe vaccines for other pathogenic picornaviruses of humans and animals.     

Rapid,gregarious settlement of the larvae of the marine echiuran Urechis caupo Fisher & MacGinitie 1928

Larvae of Urechis caupo Fisher & MacGinitie, reared in the laboratory, were exposed to potential settlement stimuli, including natural sediment from adult burrows, and “scent” obtained from the skin of adult animals. Competent larvae settled rapidly and specifically in response to adult burrow sediment when compared with their responses to other natural and abiotic sediments. Larvae also responded specifically to chemical “scent” from adult animals when the “scent” of another echiuran worm, Listriolobus pelodes Fisher served as a control. Larval responses to chemical “scent” were as great as their responses to natural burrow sediment. Hence, it is likely that larvae settle gregariously in nature in response to “scent” on sediment grains of adult burrows. The chemical “scent” had a molecular weight between ≈3500 and 14000 daltons, as determined by dialysis. It quickly lost its effectiveness in promoting settlement after it was heated to 80 °C, but was relatively stable at ambient ocean temperatures, retaining its effectiveness for several days. It was soluble in sea water. However, larvae did not respond to the chemical “scent”, unless it was adsorbed onto a surface. Purely tactile stimuli, such as the shape, texture, and size-distribution of particles, were not important settlement cues during these experiments.     

A Neuro-Comparative Study between Single/Successive Thorium Dose Intoxication and Alginate Treatment

The adult male albino rats were grouped into five groups (control group and four variably treated groups with thorium (Th) in single or successive with or without alginate treatment). The IP administration of thorium nitrate (13.6 mg/kg b.wt.) induced a regional distribution and accumulation ordered as cerebellum > cerebral cortex > brain stem > hippocampus > hypothalamus > striatum. Also, it induces a significant increase in Na⁺, Ca²⁺, and Fe³⁺ ion content and malondialdehyde (MDA) level while K⁺ ions and glutathione (GSH) level were significantly decreased. On the other hand, the daily oral administration of 5% alginate showed a significant decreasing in the accumulation of thorium in the different brain areas and mitigated its hazardous effects. By the alginate treatment, Na⁺, Ca²⁺, Fe³⁺, and level of MDA were declined while K⁺ ions and GSH level showed a significant increase. The improvement of the investigated parameters was attributed to the specific chelating, regeneration, and antioxidant properties of the alginate. So, alginate administration could ameliorate the hazardous effects of thorium nitrate.     

Biodecolourization of azo and triphenylmethane dyes by <Emphasis Type="Italic">Dichomitus squalens</Emphasis> and <Emphasis Type="Italic">Phlebia</Emphasis> spp

Nine white-rot fungal strains were screened for biodecolourization of brilliant green, cresol red, crystal violet, congo red and orange II. Dichomitus squalens, Phlebia fascicularia and P. floridensis decolourized all of the dyes on solid agar medium and possessed better decolourization ability than Phanerochaete chrysosporium when tested in nitrogen-limited broth medium. Journal of Industrial Microbiology & Biotechnology (2002) 28, 201–203 DOI: 10.1038/sj/jim/7000222 Received 12 July 2001/ Accepted in revised form 22 October 2001     

Contribution of SELP and PSGL-1 genotypes and haplotypes to the presence of coronary heart disease in Tunisians

P-selectin (SELP) and its counter-receptor, P-selectin glycoprotein ligand-1 (PSGL-1), play key role in the transient attachment of leukocytes to endothelial cells predisposing to coronary heart disease (CHD). In the current report, 293 angiographically proven CHD patients and 327 age, gender, and race-matched controls were included. Our aim was to evaluate the contribution to CHD of the following SNPs: C-2123G, G-1969A and T715P in SELP, Met62Ile and the VNTR variants in PSGL-1 gene in a North African population from Tunisia. While there were no significant differences in the distribution of SELP or PSGL-1 alleles or genotypes between patients and controls, a trend for a significant association of the C-2123G genotypes distribution with incident CHD was observed (P = 0.06). Assuming an additive model of transmission, the risk was 74% higher among subjects carrying the GG genotypes in comparison to those carrying the CC genotype (OR = 1.74 [1.01–2.98], P = 0.04) and 80% higher in the recessive model (OR = 1.80 [1.08–3.01], P = 0.02). Haplotype analysis did not identify any specific SELP or PSGL-1 haplotypes to be associated with CHD. The present study demonstrated no evidence of association between individual SELP or PSGL-1 SNPs or haplotypes with incident CHD. However, this study replicates absence of association of the mostly studied SNP, T715P, previously reported in individuals with African origin.     

Identification of a novel gene, DZIP (DAZ-interacting protein), that encodes a protein that interacts with DAZ (deleted in azoospermia) and is expressed in embryonic stem cells and germ cells

Evidence from diverse organisms, including humans, suggests that the DAZ (Deleted in Azoospermia) gene and a closely related homolog, DAZL (DAZ-like), are required early in germ cell development to maintain initial germ cell populations. Here we report the identification and characterization of the DZIP (DAZ-Interacting Protein) gene, which encodes at least three different protein isoforms that contain a C2H2 zinc-finger domain. The DZIP gene is expressed predominantly in human embryonic stem cells and fetal and adult germ cells; moreover, two DZIP protein isoforms colocalize with DAZ and/or DAZL proteins in these tissues. Finally, we provide evidence indicating that DZIP may associate with DAZ and its other cofactors in an RNA-binding protein complex that functions in both ES cells and germ cells.     

Inversions of chromosome arms 4AL and 2BS in wheat invert the patterns of chiasma distribution

In many species, including wheat, crossing over is distal, and the proximal regions of chromosome arms contribute little to genetic maps. This was thought to be a consequence of terminal initiation of synapsis favoring distal crossing over. However, in an inverted rye chromosome arm, the pattern of metaphase I chiasmata was also inverted, suggesting that crossover frequencies were specific to chromosome segments. Here, wheat chromosome arms 2BS and 4AL, with essentially entire arms inverted in reverse tandem duplications (rtd), were studied in the MI of meiosis. Inversion–duplication placed the recombining segments in the middle of the arms. While the overall pairing frequencies of the inverted–duplicated arms were considerably reduced relative to normal arms, chiasmata, if present, were always located in the same regions as in structurally normal arms, and relative chiasma frequencies remained the same. The frequencies of fragment or fragment + bridge configurations in AI and AII indicated that of the two tandemly arranged copies of segments in rtds, the more distal inverted segments were more likely to cross over than the segments in their original orientations. These observations show that also in wheat, relative crossover frequencies along chromosome arms are predetermined and independent of the segment location. The segments normally not licensed to cross over do not do so even when placed in seemingly most favorable positions for it.