Correlation between pectate lyase activity and ability of diazotrophic Klebsiella oxytoca VN 13 to penetrate into plant tissues

Diazotrophic Klebsiella oxytoca VN 13 was able to lyse pectate, but the lytic activity of cultures grown on non-selective media was weak, and the enzyme was located mainly inside the cells. A small fraction of the population (10^-6 to 10^-5) was able to grow in a selective medium with sodium polygalacturonate as sole carbon source, and produced increased amounts of the pectinolytic enzyme pectate lyase. When wheat seeds were inoculated with these bacteria, increased levels of this enzyme correlated with a higher rate of internal colonization of wheat roots and with stimulation of wheat growth resulting in higher biomass. This suggests that colonization occurs via lyzed pectin layers. This revised version was published online in June 2006 with corrections to the Cover Date.     

Hypoxanthine-guanine phosphoribosyltransferase deficiency: biochemical and molecular findings in six Argentine patients

Hypoxanthine-guanine phosphoribosyltransferase (HPRT) deficiency is an inborn error of purine metabolism responsible for Lesch-Nyhan Disease (LND) and its partial phenotypes, HPRT-related hyperuricemia with neurologic dysfunction (HRND) and hyperuricemia alone. We report here the recognition of six Argentine patients, two with LND and four with HRND. All patients presented elevated excretion of uric acid, hypoxanthine, and xanthine and decreased HPRT enzyme activities <1 nmol/h/mg Hb. The molecular analysis demonstrated in the two LND patients a novel inherited transition mutation, c.203T >C (L68P), in one subject and a germline transition mutation, c.209G >A (G70E), in the other. In the HRND patients a novel transversion mutation, c.584 A >C (Y195S), was found in three related patients and an inherited transition mutation, c.143G >A (R48H), in the fourth subject.     

A revisionist replicon model for higher eukaryotic genomes

The replicon model devised to explain replication control in bacteria has served as the guiding paradigm in the search for origins of replication in the more complex genomes of eukaryotes. In Saccharomyces cerevisiae, this model has proved to be extremely useful, leading to the identification of specific genetic elements (replicators) and the interacting initiator proteins that activate them. However, replication control in organisms ranging from Schizosaccharomyces pombe to mammals is far more fluid: only a small number of origins seem to represent classic replicators, while the majority correspond to zones of inefficient, closely spaced start sites none of which are indispensable for origin activity. In addition, it is apparent that the epigenetic state of a given sequence largely determines its ability to be used as a replication initiation site. These conclusions were arrived at over a period of three decades, and required the development of several novel replicon mapping techniques, as well as new ways of examining the chromatin architecture of any sequence of interest. Recently, methods have been elaborated for isolating all of the active origins in the genomes of higher eukaryotes en masse. Microarray analyses and more recent high-throughput sequencing technology will allow all the origins to be mapped onto the chromosomes of any organism whose genome has been sequenced. With the advent of whole-genome studies on gene expression and chromatin composition, the field is now positioned to define both the genetic and epigenetic rules that govern origin activity.     

Simple ways to measure behavioral responses of Drosophila to stimuli and use of these methods to characterize a novel mutant

The behavioral responses of adult Drosophila fruit flies to a variety of sensory stimuli--light, volatile and non-volatile chemicals, temperature, humidity, gravity, and sound--have been measured by others previously. Some of those assays are rather complex; a review of them is presented in the Discussion. Our objective here has been to find out how to measure the behavior of adult Drosophila fruit flies by methods that are inexpensive and easy to carry out. These new assays have now been used here to characterize a novel mutant that fails to be attracted or repelled by a variety of sensory stimuli even though it is motile.     

Systemic analysis: Individual typological characteristics of the human body

Statistical analysis of the distribution of the mean somatometric, functional, and psychophysiological parameters in the total sample of subjects with the use of the χ² and λ tests and low, medium, and high habitual physical activity (HPA) levels (LHPA, MHPA, and HHPA, respectively) at different ontogenetic stages (junior and senior school students and young adults of both sexes) showed wide quantitative and qualitative ranges of psychophysiological individuality in a healthy population and demonstrated that it is reasonable to distinguish three typological groups or functional constitutional types (FT-1 corresponding to LHPA; FT-2, to MHPA; and FT-3, to HHPA). Typical first- and second-order parameters, as well as the results of third-order tests characterizing the current state, were determined for each FT. In order to comprehensively assess the constitutional type (synthetic constitution) of the subjects with low, medium, and high HPAs, the integrated analysis of the set of their characteristics was performed using the principles of polythetic (multi-variate) classification. The results obtained using multivariate statistical methods confirmed the basic postulate of the concept of typological variability of physiological individuality that a healthy human population is qualitatively heterogeneous in morphological, functional, and psychophysiological traits. The integrated physiological and statistical analyses of the results provided a scientific basis for three functional constitutional types (FT-1, FT-2, and FT-3) corresponding to three synthetic constitutional types (C 0-1, C 00, and C 01). These data indicate that the systemic (constitutional) approach to the estimation of individual typological characteristics confirm a high informativeness of partial constitution (FT-1, FT-2, and FT-3) in the human biological organization, and the set of characters selected for analysis allows the synthetic constitutional types to be adequately differentiated on a formal basis.