Thin-layer chromatographic collector-eluter.

A combination thin-layer chromatographic collector and elution apparatus is described. The device is designed to minimize manipulations and maximize accuracy and can be used for both analytical and small-scale preparative separations.     

Voltage-dependent conductance induced by hemocyanin in black lipid films

When hemocyanin is added to a black lipid film, the conductance increases in discrete steps. For negative potentials the single step conductance is constant, but for positive potentials the step conductance appears to decrease as the potential increases. At high positive potentials the conductance fluctuates between several levels. These data suggest that, in lipid membranes, hemocyanin conducts ions through discrete channels. The voltage-dependent conductance observed at high levels of conductance seems to be a consequence of the properties of the conductance of the single channel.     

The nature of the voltage-dependent conductance of the hemocyanin channel.

The electrical responses of individual hemocyanain channels in oxidized cholesterol membranes demonstrate that the voltage-dependent conductance of many-chanel membranes arises from two different mechanisms. These are the voltage-dependent redistribution of channels among several discrete single-channel conductance states themselves. The relaxation time for the discrete conductance changes is of the order of seconds nd the relaxation time of the continuous conductance changes is of the order 10(-4) seconds. As salt concentration in the bathing medium is increased, the single-channel conductance first increases lineary and then saturates. The characteristics of the saturation curves suggest that the continuous conductance changes occur at the edges of the channel and that the mean time an ion spends in the channel is 4 nanoseconds...     

Distribution of interstitial retinol-binding protein (IRBP) in the vertebrates

Immunoblots of interphotoreceptor matrix preparations from 20 species belonging to six vertebrate classes were probed with antibodies against bovine interstitial retinol-binding protein (b-IRBP). Each preparation displayed an immunoreactive protein band. In the Osteichthyes, the apparent Mr of this band was 67,600 +/- 2,700 (mean +/- SD, n = 8). In two of the Osteichthyes, the band was resolved into a closely spaced doublet. Including previously published data for five mammals and one amphibian, species from the other classes (Chondrichthyes, one species; Amphibia, four species; Reptilia, one species; Aves, one species; Mammalia, nine species) had IRBPs with Mr that averaged 2.0 times that of the Osteichthyes, namely 134,200 +/- 8,600 (mean +/- SD, n = 17). Frog IRBP was very similar to mammalian IRBP in terms of its immunohistochemical distribution (determined with rabbit anti-frog IRBP antibodies), its molecular weight (sodium dodecyl sulfate polyacrylamide gel electrophoresis and gel-filtration chromatography), retinol- and concanavalin A-binding ability, and because it was synthesized and secreted in vitro by the isolated retina but not by the pigmented layers of eye. Goldfish IRBP apparently binds exogenous (3H)-retinol but does not bind concanavalin A and has about half the Mr of frog IRBP. The occurrence of IRBP-like proteins cross-reacting with anti b-IRBP antibodies in the interphotoreceptor matrix of all six major vertebrate classes is consistent with the hypothesis that IRBP is an important element in the vertebrate visual cycle.     

A study on the minimum number of loci required for genetic evaluation using a finite locus model

For a finite locus model, Markov chain Monte Carlo (MCMC) methods can be used to estimate the conditional mean of genotypic values given phenotypes, which is also known as the best predictor (BP). When computationally feasible, this type of genetic prediction provides an elegant solution to the problem of genetic evaluation under non-additive inheritance, especially for crossbred data. Successful application of MCMC methods for genetic evaluation using finite locus models depends, among other factors, on the number of loci assumed in the model. The effect of the assumed number of loci on evaluations obtained by BP was investigated using data simulated with about 100 loci. For several small pedigrees, genetic evaluations obtained by best linear prediction (BLP) were compared to genetic evaluations obtained by BP. For BLP evaluation, used here as the standard of comparison, only the first and second moments of the joint distribution of the genotypic and phenotypic values must be known. These moments were calculated from the gene frequencies and genotypic effects used in the simulation model. BP evaluation requires the complete distribution to be known. For each model used for BP evaluation, the gene frequencies and genotypic effects, which completely specify the required distribution, were derived such that the genotypic mean, the additive variance, and the dominance variance were the same as in the simulation model. For lowly heritable traits, evaluations obtained by BP under models with up to three loci closely matched the evaluations obtained by BLP for both purebred and crossbred data. For highly heritable traits, models with up to six loci were needed to match the evaluations obtained by BLP.     

Nasal Priming with Lactobacillus rhamnosus CRL1505 Stimulates Mononuclear Phagocytes of Immunocompromised Malnourished Mice: Improvement of Respiratory Immune Response

The effect of Lactobacillus rhamnosus CRL1505 (Lr) on macrophages (Ma) and dendritic cells (DC) in the orchestration of anti-pneumococcal immunity was stud