How the Visual Cortex Handles Stimulus Noise: Insights from Amblyopia

Adding noise to a visual image makes object recognition more effortful and has a widespread effect on human electrophysiological responses. However, visual cortical processes directly involved in handling the stimulus noise have yet to be identified and dissociated from the modulation of the neural responses due to the deteriorated structural information and increased stimulus uncertainty in the case of noisy images. Here we show that the impairment of face gender categorization performance in the case of noisy images in amblyopic patients correlates with amblyopic deficits measured in the noise-induced modulation of the P1/P2 components of single-trial event-related potentials (ERP). On the other hand, the N170 ERP component is similarly affected by the presence of noise in the two eyes and its modulation does not predict the behavioral deficit. These results have revealed that the efficient processing of noisy images depends on the engagement of additional processing resources both at the early, feature-specific as well as later, object-level stages of visual cortical processing reflected in the P1 and P2 ERP components, respectively. Our findings also suggest that noise-induced modulation of the N170 component might reflect diminished face-selective neuronal responses to face images with deteriorated structural information.     

Effect of oxygen and air flow on xylanolytic and cellulolytic activity from bacterial cultures grown on bagasse pith

Summary The xylanolytic and cellulolytic activity fromCellulomanas were reduced by high O₂ concentrations in continous culture as well as by an air flow passed trough the samples, suggesting an inhibition or inactivation of enzymes in such conditions.     

An abnormal terminal X-Y interchange accounts for most but not all cases of human XX maleness

To determine if human XX maleness results from an abnormal chromosomal X-Y interchange, we studied the inheritance of the paternal pseudoautosomal region in nine patients. Those six patients in whom Y-specific DNA was found (Y(+)) inherited the entire pseudoautosomal region from the paternal Y chromosome and lost that of the paternal X chromosome. Moreover, in three Y(+) cases, we observed the deletion of a paternal Xp locus tightly linked to the pseudoautosomal region. These results definitively show that an abnormal and terminal X-Y interchange during paternal meiosis causes Y(+)XX maleness. In contrast, no abnormal X-Y interchange was observed in any of the three Y(-) cases analyzed, suggesting that maleness can occur in the absence of any Y-specific DNA.     

The inheritance of seed peroxidases of wheat and rye: further data

Summary Further data on the inheritance of seed peroxidases of hexaploid wheat (Triticum aestivum L.) and rye (Secale cereale L.) have been obtained from the genetic analysis of several progenies of both species. Additional data on the inheritance and the chromosomal location and linkage have been obtained for peroxidases of wheat embryo and rye endosperm. The general presence of null alleles in peroxidase loci has been confirmed in both species. In addition to simple monogenic inheritance, epistatic segregations have been observed in both species. These epistatic segregations again suggest the presence of regulatory genes controlling the expression of individual peroxidases in both species and also the existence of several duplicate homoeologous genes in wheat. Known linkage relationships have been confirmed and new ones are indicated. Loci for embryo wheat peroxidases seem to be in chromosomes of the homoeology group 3. The rye endosperm ones should be in chromosome 7R, although it is hypothesized that a duplication of gene EPer1 is located in chromosomes 4R and 7R.     

Pyridoxal 5'phosphate binding site of Escherichia coli beta cystathionase and cystathionine gamma synthase comparison of their sequences

The phosphopyridoxyl peptides of beta cystathionase and cystathionine gamma synthase of Escherichia Coli were identified after reduction, carboxymethylation and proteolysis of the holoenzymes. Their comparison with those obtained from rat liver gamma cystathionase (Fearon, C.W., Rodkey, J.A. and Abeles R.H. 1982. Biochemistry 21 3790-3794.) showed a high degree of homology between the three PLP binding sites with the presence of the tripeptide sequence: Thr-Lys(Pxy)-Tyr in their structure. This homology suggests that these enzymes of methionine metabolism have probably the same origin.     

Production and characterization of four monoclonal antibodies against porcine pancreatic colipase

Four monoclonal antibodies directed against porcine colipase have been generated by hybridization of myeloma cells with spleen cells of BALB/c immunized mice. Antibodies were screened by binding to immobilized colipase in a solid-phase assay. Monoclonal antibodies were purified by affinity chromatography on colipase coupled to Sepharose. All monoclonal antibodies are of the IgG1 class with high affinity for the antigen. The dissociation constant of the complex formed in solution between porcine colipase and antibody varied from 1.1 X 10(-10) M to 1.8 X 10(-8) M. Epitope specificity was studied for each antibody and in pairs with an enzyme-linked immunosorbent assay (ELISA). Results indicate that the four monoclonal antibodies react with at least three different antigenic regions of colipase. Finally, three monoclonal antibodies were found to be potent inhibitors of colipase activity. Antiporcine monoclonal antibodies appear to be suitable probes for studying the lipid affinity site of the protein cofactor of pancreatic lipase.