Identification of the gene encoding the major cellobiohydrolase of the white rot fungus Phanerochaete chrysosporium.

Previous studies have shown that the cellobiohydrolases of the white rot basidiomycete Phanerochaete chrysosporium are encoded by a family of structurally related genes. In this investigation, we identified and sequenced the most highly transcribed gene, cbh1-4. Evidence suggests that in this fungus the dominant isozyme, CBH1, is encoded by chb1-4.     

A 30 kDa functional size for the erythrocyte water channel determined in situ by radiation inactivation.

The functional unit size of the water channel in rabbit erythrocytes was assessed using target size analysis following radiation inactivation. Using Radiochromic nylon dosimetry, accurate values of accumulated dose yielded an absolute target analysis, leading to direct determination of molecular size. The erythrocyte water channel functional size was shown to be 30 kDa, and is identical to the size found in rat renal proximal tubule brush border membranes (1), suggesting close homology of these two water channels. The result suggests that the 28 kDa channel-like intrinsic protein (CHIP28) recently isolated from human erythrocytes and proximal tubule (2), which is believed to form water channels of oligomeric construction may have a functional water channel activity in monomeric form.     

Comparison of proteins from Mycobacterium fortuitum, Mycobacterium nonchromogenicum and Mycobacterium terrae using flat bed electrophoresis.

Polyacrylamide gel electrophoresis of bacterial lysates in a flat bed gives a linear relationship between 1n mol. wt of the proteins and the square root of their migration distances, thereby allowing standardization of different electrophoresis runs and precise comparison between homologous bands. The results obtained with Mycobacterium fortuitum, M. terrae and M. nonchromogenicum strains were used in numerical analysis. Mycobacterium fortuitum and M. nonchromogenicum showed a greater internal similarity than M. terrae, while two strains of the latter clustered with M. nonchromogenicum. The method described allows the comparison of mycobacteria with different generation times and provides a large number of good characters for numerical taxonomy.     

Quantification of short term signaling by the epidermal growth factor receptor.

During the past decade, our knowledge of molecular mechanisms involved in growth factor signaling has proliferated almost explosively. However, the kinetics and control of information transfer through signaling networks remain poorly understood. This paper combines experimental kinetic analysis and computational modeling of the short term pattern of cellular responses to epidermal growth factor (EGF) in isolated hepatocytes. The experimental data show transient tyrosine phosphorylation of the EGF receptor (EGFR) and transient or sustained response patterns in multiple signaling proteins targeted by EGFR. Transient responses exhibit pronounced maxima, reached within 15-30 s of EGF stimulation and followed by a decline to relatively low (quasi-steady-state) levels. In contrast to earlier suggestions, we demonstrate that the experimentally observed transients can be accounted for without requiring receptor-mediated activation of specific tyrosine phosphatases, following EGF stimulation. The kinetic model predicts how the cellular response is controlled by the relative levels and activity states of signaling proteins and under what conditions activation patterns are transient or sustained. EGFR signaling patterns appear to be robust with respect to variations in many elemental rate constants within the range of experimentally measured values. On the other hand, we specify which changes in the kinetic scheme, rate constants, and total amounts of molecular factors involved are incompatible with the experimentally observed kinetics of signal transfer. Quantitation of signaling network responses to growth factors allows us to assess how cells process information controlling their growth and differentiation.     

Age-specific correlation analysis of longitudinal physical fitness levels in men.

This study investigated the age-specific tracking of adult health- and performance-related fitness scores. In addition, the independent contribution of adolescent physical characteristics to the explanation of adult fitness scores was also studied. The sample consisted of 173 adults observed at age 30 years. These subjects had been followed at annual intervals from age 13 to age 18 years and were remeasured at age 30 years. At each age nine fitness tests were administered together with the recording of anthropometric dimensions, biological maturation, sports participation and family characteristics. Tracking was measured by the inter-age correlations at each age between 13 and 18 years and the performance scores at 30 years. The independent contribution of characteristics observed during adolescence to the explanation of adult fitness was investigated through stepwise multiple regression analysis and discriminant analysis with the adult fitness scores as the dependent variables and the fitness, maturation, anthropometric characteristics, sports participation and family background as the independent variables. Tracking between age 13 and age 30 years was moderately high (46% of variance explained) for flexibility, low to moderate (between 19% and 27% of variance explained) for the other fitness parameters and low for pulse recovery and static strength (7% to 11% of variance explained). Between age 18 and age 30 years the tracking was high for flexibility, moderately high for explosive and static strength, and moderate for the other fitness parameters except for pulse recovery. The amount of variance of adult fitness levels explained increased significantly when other characteristics observed during adolescence entered the regressions or discriminant functions.(ABSTRACT TRUNCATED AT 250 WORDS)     

The Social Life of Infants in the Context of Infectious Disease Transmission; Social Contacts and Mixing Patterns of the Very Young

Insight into how humans interact helps further understanding of the transmission of infectious diseases. For diseases such as pertussis, infants are at particular risk for severe outcomes. To understand the contact pattern of infants, especially those too young to be vaccinated, we sent contact diaries to a representative sample of 1000 mothers in the United Kingdom. We received 115 responses with a total of 758 recorded contacts. The average number of daily contacts for an infant was 6.68 overall and 5.7 for those aged ≤10 weeks. Of the latter, 2.1 (37%) contacts were with non-household members and were >15 minutes duration, suggesting that a cocooning programme may miss a substantial proportion of exposures leading to disease transmission. The least contact was between adolescents and infants. Thus the impact of adolescent (pertussis) vaccination on infants would likely be limited, unless it reduces transmission to other age groups whose contact with infants is greater.