Parametric and Nonparametric Analyses of Repeated Ordinal Categorical Data

We compare two models for the analysis of repeated ordinal categorical data: the classical parametric model for means of scores assigned to the categories of the response variable and a nonparametric model based on relative effects derived from the marginal distribution functions of the response. An example in the field of Dentistry is used to illustrate and to compare the models. We also consider a simulation study to evaluate the type‐I error rates and the power of tests under both models in a balanced design setup. The simulation results suggest that both approaches behave similarly for equally spaced scores but may perform differently otherwise. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Analysis of polyadenylated RNA from brain synaptosomes and mitochondria

We have isolated RNA from sheep brain synaptosomes and mitochondria separated by an aqueous two-phase system composed of dextran and poly(ethylene glycol). RNA was fractionated through oligo(dT)-cellulose columns and analyzed by electrophoresis through agarose slab gels containing methylmercuric hydroxide and stained with ethidium bromide. The electrophoretic patterns of the poly(A)-containing RNA fraction from synaptosomes and mitochondria are very similar although some high molecular weight RNA species, clearly visible in the synaptosomal fraction, are scarcely detected in the mitochondrial preparations. The electrophoretic analysis of a cleaner RNA preparation from digitonin-treated free mitochondria (mitoplasts) showed that all the poly (A)-RNA species of the synaptosomal preparation are also present in mitoplast. These results strongly suggest that all the discrete poly(A)-RNA species identified in brain synaptosomes are of mitochondrial origin.     

Role of the LFA3-CD2 interaction in human specific B cell differentiation

We examined the role of the lymphocyte function-associated (LFA)3 molecule in human B cell response. A mAb to this molecule did not influence B cell proliferation induced by anti-mu antibody and IL. In contrast, the same mAb inhibited the specific T-dependent B cell response induced by a particulate Ag. In the same line, two anti-CD2 mAb (directed toward the T11-1 and T11-2 epitopes) inhibited this response, whether used alone or in association. These inhibitions took place at an early stage of the response, and anti-LFA3 and anti-CD2 mAb acted on B cells and T cells, respectively. In contrast, when T cell help was provided by exogenous IL-2, the B cell response was resistant to the inhibitory effect of anti-LFA3 mAb. Taken together, these results indicate that the LFA3-CD2 pair play a major role in the direct T-B interaction required for T cell help.     

Subcellular localization and glycoprotein nature of the invertase from the fission yeast Schizosaccharomyces pombe

The subcellular localization of the enzyme invertase in Schizosaccharomyces pombe cells, both repressed and derepressed for synthesis of the enzyme, was studied. Most of the invertase was found to be located outside the plasma membrane and only a small percentage was found to be associated to membranes. A substantial portion of the external enzyme remained firmly bound to cell-wall material.All of the invertase recovered in soluble form from cellular extracts reacted with concanavalin A and with the lectin from Bandeiraea simplicifolia seeds, indicating the presence in the enzyme of a carbohydrate moiety which probably contains terminal mannosyl (or structurally related) and galactosyl residues.The possibility of the presence of two different forms of invertase in S. pombe was considered. An intracellular, soluble form of invertase, devoid of carbohydrate, similar to the small invertase of the budding yeast Saccharomyces cerevisiae, was not found in S. pombe. However, the Michaelis constant for sucrose of the enzyme present in repressed cells was smaller than that of the invertase synthesized under derepressing conditions, although this difference could also be the result of a different pattern of glycosylation of the invertase synthesized under different growth conditions.     

Phytosociological characteristics of theRondeletio correifoliae-Andropogonetum multinervosi ass. nova (Sierra de la Siguanea,Isla de la Juventud,Cuba)

The contribution deals with the phytocenological analysis of theRondeletio correifoliae-Andropogonetum multinervosi, an endemic savanna association occuring on the Siguanea Hills (Sierra de la Siguanea) near the Colony Hotel.     

Tubulin and tubulin-colchicine complex bind to brain microsomal membrane in vitro

Brain tubulin was labeled in vitro by post-translational incorporation of [14C]-tyrosine or in vivo by intra-cranial injection of [3H]-leucine. The labeled protein was purified by ion-exchange chromatography. After incubating at 37 degrees C with a microsomal membrane preparation from rat brain, part of the labeled soluble tubulin became sedimentable at high-speed centrifugation. This was independent of the native configuration of tubulin, the state of tyrosination of the COOH-terminus, or the presence of 100 microM colchicine in the mixture. In addition, the double-labeled tubulin-colchicine complex obtained from the binding of [3H]-colchicine to [14C]-tyrosinated tubulin, bound to the membrane preparation to the same extent as [14C]-tyrosinated tubulin. The data show that either tubulin or the complex resulting from its binding to colchicine distributed between the soluble and the membrane fractions when mixed at 37 degrees C with a microsome preparation. Seemingly, the site for colchicine binding to tubulin needs not to be free for the protein-membrane association.