Functional conservation of cytosolic proteins required for endosomal vesicle fusion

Recent studies suggest that intracellular membrane traffic relies upon families of related proteins which confer specificity to individual transport reactions but which operate in tandem with a ubiquitous fusogenic complex containing the N-ethylmaleimide-sensitive fusion protein (NSF). The extent to which components of this process are functionally conserved is apparent from the finding that yeast Sec18 protein (Sec18p) can substitute for mammalian NSF in intra-Golgi transport reactions. Here we report that yeast cytosol can support mammalian endosomal vesicle fusion, demonstrating conservation of cytosolic components required for this reaction. Furthermore, under conditions in which the fusion reaction is NSF-dependent we show that yeast Sec18p can functionally substitute for NSF, showing that the yeast protein is capable of catalysing at least two distinct mammalian membrane fusion events. In addition we exploit the complex pattern of sensitivity of the mammalian reaction to N-ethylmaleimide (NEM), coupled with the use of yeast cytosol, to dissect a number of factors required for fusion. We reveal at least three novel NEM-sensitive activities. One of these can be restored by yeast cytosol suggesting that it is functionally conserved.     

Identification of microsatellite markers near the human ob gene and linkage studies in NIDDM-affected sib pairs

Non-insulin-dependent diabetes mellitus (NIDDM) is a complex metabolic disorder with a significant genetic component. Obesity is a frequent complicating factor for NIDDM. In the mouse, a number of single gene defects that result in obesity have been described. Mutations in one of these genes, the ob gene, results in both obesity and NIDDM. Recently, the cloning of the murine ob gene and its human homologue has been reported (Nature 372:425-432, 1994). In the present study, the contribution of genetic variation at the human ob locus to NIDDM susceptibility was assessed by analyzing allele sharing in NIDDM-affected sib pairs (ASPs) for markers located near the human ob gene. Four yeast artificial chromosome clones containing the human ob gene were isolated. These clones colocalized the ob gene and two microsatellite markers, D7S514 and D7S635, to a region of 280 kb on the long arm of human chromosome 7. The microsatellite markers were typed in 346 Mexican-American NIDDM-ASPs derived from 176 families and an additional 110 ethnically and geographically matched controls. No evidence of linkage or association between either microsatellite marker and NIDDM was observed in this population. These results suggest genetic variation in the human ob gene does not play a major role in susceptibility to NIDDM in Mexican-Americans.     

A new decision-directed algorithm for nonstationary priors

A decision-directed receiver uses the estimate of the rate of the discrete-time point process (DTPP) output of the (0-1) detector as the unknown prior probability of the Bernoulli input sequence. This correspondence applies the results of Segall [5] to permit the estimation of a time-varying rate.     

The optic tectum of birds: Mapping our way to understanding visual processing.

Over the past few decades there has been a massive amount of research on the geniculo-striate visual system in primates. However, studies of the avian visual system have provided a rich source of data contributing to our understanding of visual processing. In this paper we review the connectivity and function of the optic tectum (homolog of the superior colliculus) in birds. We highlight the retinotopic projections that the optic tectum has with the isthmal nuclei, and the functional topographic projections that the optic tectum has with the nucleus rotundus and entopallium (homologs of the pulvinar and extrastriate cortex, respectively) where retinotopy has been sacrificed. This work has been critical in our understanding of basic visual processes including attention, parallel processing, and the binding problem. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Stochastic optimization for modeling physiological time series: application to the heart rate response to exercise

Stochastic optimization is applied to the problem of optimizing the fit of a model to the time series of raw physiological (heart rate) data. The physiological response to exercise has been recently modeled as a dynamical system. Fitting the model to a set of raw physiological time series data is, however, not a trivial task. For this reason and in order to calculate the optimal values of the parameters of the model, the present study implements the powerful stochastic optimization method ALOPEX IV, an algorithm that has been proven to be fast, effective and easy to implement. The optimal parameters of the model, calculated by the optimization method for the particular athlete, are very important as they characterize the athlete's current condition. The present study applies the ALOPEX IV stochastic optimization to the modeling of a set of heart rate time series data corresponding to different exercises of constant intensity. An analysis of the optimization algorithm, together with an analytic proof of its convergence (in the absence of noise), is also presented.     

Ultrastructural studies of the female breast: I. 9 + 0 cilia in myoepithelial cells

1 Phenylethanolamine-N-methyltransferase (PNMT) activity in adrenal gland was lower than the control values at day 24 of rabbit pregnancy and fell throughout the gestational period. 2 Catechol-O-methyltransferase (COMT) activity during pregnancy and parturition followed a similar pattern to PNMT. 3 Adrenaline content of the adrenal gland declined significantly during the last few days of pregnancy but at parturition showed a tendency to return towards normal. 4 The biochemical mechanisms which result in a decline in PNMT and COMT activities and adrenaline concentration appear to be the consequence of modifications in endocrine gland secretion during pregnancy.     

Pressure Dependence of the Multiphonon Excitations of Superfluid 4He

The pressure dependence of the multiphonon excitations in superfluid ⁴He has been studied, using neutron inelastic scattering. High-resolution measurements have been made at 0,5 K over a wavevector range 0.6<Q<2.2 Å^–1, at various pressures between 0 and 20 bars. The experimental data are presented and existing theoretical calculations are discussed.