High-frequency heterokaryon formation by Mucor racemosus.

Heterokaryons from Mucor racemosus were produced from two auxotrophic strains of the fungus. Germlings were converted to spheroplasts by using commercial chitinase and purified Myxobacter AL-1 chitosanase. Spheroplasts from the auxotrophic strains were mixed and fused in solutions of polyethylene glycol and CaCl2. Under optimal conditions, prototrophic heterokaryons were formed at a frequency of about 5%.     

Mistranslation in cells infected with the bacteriophage MS2: Direct evidence of Lys for Asn substitution

Summary The coat protein of the bacteriophage MS2 was found to show an increased level of charge heterogeneity when synthesized in Escherichia coli starved for Asn or Lys. No such increase was found when the host was starved for Arg, His, Ile or Pro. This is the pattern predicted by two-out-of-three codon misreading in the coat protein gene. In the case of Asn starvation, direct measurements of the relative incorporation of Lys demonstrate that the observed charge heterogeneity is the result of mistranslation. Asn starvation increased the error frequency in coat protein to over 0.3 mistake per asparagine codon. The small amount of charge heterogeneity seen in unstarved cells seems also to be the result of misreading Asn codons.     

Presence of HBsAg in the bile of subjects with acute HBsAg viral hepatitis.

During acute HBsAg serum positive viral hepatitis, the surface antigen was not detectable in duodenal bile but was almost always present in gallbladder and hepatic bile when cholecystokinin was intravenously administered. The immunologic nondemonstrability of HBsAg in duodenal bile is probably due to the presence of a factor elaborated by the intestinal mucosa. The possible role played by this factor in the non transmission of type B viral hepatitis via faecal-oral route is suggested.     

Properties of Two Homologous Alkaline Proteases from Streptomyces rectus

Some physicochemical properties of two thermostable proteases from Streptomyces rectus are described. The enzymes were judged to be identical with respect to molecular weight, inactivation with serine protease inhibitors, and in primary structure by peptide analysis. Amino acid analysis indicated the enzymes had identical compositions except for their amide content. The molecular weights of the enzymes were judged to be 28,000 by sedimentation equilibrium, 26,200 by sedimentation diffusion, and 29,100 from amino acid analysis. Titration of the proteases with diisopropylfluorophosphate and phenylmethane sulfonylfuoride indicate equivalent weights of 28,500 and 32,800 g, respectively, for the proteins. The pentapeptide around the serine residue reacting with diisopropylfluorophosphate was isolated and had the composition: Asx(1), Gly(1), Thr(1), Ser(1), Met(1).     

Fibrin clot retractile activity of mouse fibroblasts during growth and aging

This study aimed at evaluating by a quantitative assay the fibrin clot retractile activity (FCR) of C3H embryo fibroblasts during their growth and aging in culture. Cell from primary and subsequent subcultures were tested at defined times from seeding, in a specially devised micromethod. Results indicate that cell-induced FCR has a kinetic similar to platelet-induced FCR; it depends on the number of cells and time of incubation in the system. It is absent or low in cells harvested from primary culture, then increases and remains high in the following doublings decreasing sharply at the end of the replicative life span in culture.     

Bower quality,number of decorations and mating success of male satin bowerbirds (Ptilonorhynchus violaceus): an experimental analysis

Bowerbirds build large bowers of twigs decorated with brightly coloured objects at display sites where males court females. The bower and its decorations are hypothesized to influence female choice in these birds. However, there have been no empirical tests of this hypothesis. Data from two years of field research on the satin bowerbird (Ptilonorhynchus violaceus) show: (1) an extremely skewed distribution of matings among males, and (2) a consistent pattern of female preference for particular males, especially those with well-constructed, highly-decorated bowers. These results support the hypothesis that bower quality is important in influencing female mating preferences. In particular, they support the ‘marker’ hypothesis, which suggests that the construction of bowers evolved to provide females with information about the relative quality of males.     

Blue,not UV,plumage color is important in satin bowerbird Ptilonorhynchus violaceus display

Several studies have suggested that peak plumage reflectance in birds matches color preferences used in mate choice. We tested this hypothesis in adult satin bowerbird males that have a short‐wavelength saturated blue‐black plumage with a peak reflectance in the UV. We found that the chroma of the blue (405–480 nm), but not the peak reflecting UV (320–400 nm) portion of the male plumage spectrum was significantly correlated with male mating success. A plot of correlation coefficients between male mating success and plumage saturation showed a well‐defined peak in the blue. This suggests that: 1) blue plumage coloration is more important in mate choice than UV or other colors, and 2) that there is a mismatch between the peak reflectance of the plumage of male satin bowerbirds and the range of plumage wavelengths that are correlated with male mating success. This indicates that it is not safe to infer a role of UV or other colors in mate choice simply because of a peak in plumage reflectance.     

Hospital cluster of HBV infection: molecular evidence of patient-to-patient transmission through lancing device

Introduction

In western countries the transmission of hepatitis B virus (HBV) transmission through multi-patients lancing devices has been inferred since early ‘90s, however no study has ever provided biological evidence which directly link these device with HBV cross-infection. Here we present results of an outbreak investigation which could associate, by molecular techniques, the use of lancing device on multiple patients with HBV transmission in an Italian oncohematology unit.

Methods

The outbreak investigation was designed as a retrospective cohort study to identify all potential cases. All cases identified were eventually confirmed through molecular epidemiology techniques. Audit of personnel including extensive review of infection control measures and reviewing personnel''s tests for HBV was done identify transmission route.

Results

Between 4 May 2006 and 21 February 2007, six incident cases of HBV infection were reported among 162 patients admitted in the oncohematology. The subsequent molecular instigation proved that 3 out 6 incident cases and one prevalent cases (already infected with HBV at the admission) represented a monophyletic cluster of infection. The eventual environmental investigation found that an identical HBV viral strain was present on a multi-patients lancing device in use in the unit and the inferential analysis showed a statistically significant association between undergoing lancing procedures and the infection.

Discussion

This investigation provide molecular evidence to link a HBV infection cluster to multi-patients lancing device and highlights that patients undergoing capillary blood sampling by non-disposable lancing device may face an unacceptable increased risk of HBV infection. Therefore we believe that multi-patients lancing devices should be banned from healthcare settings and replace with disposable safety lancets that permanently retract to prevent the use of the same device on multiple patients. The use of non-disposable lancing devices should be restricted to individual use at patients'' home.