Licht- und elektronenoptische Untersuchungen über den Einfluß von Streptomycin aufSinapis alba L.

Ohne Zusammenfassung Mit 22 Textabbildungen     

Antigen-specific receptors on antibody-forming cells expressing light and heavy chain determinants.

There has been controversy in the past about whether or not antibody-forming cells have antigen-specific receptors. Evidence is presented here which clearly demonstrates that some antibody-forming cells possess receptors while others show no evidence of receptors. Moreover, in this report the receptors are characterized in terms of their light and heavy chain immunoglobulin determinants. Receptors were found on ~50% of the direct PFC 6 days after one injection of sheep red blood cells (SRBC). On Day 4 of the secondary response only 20–33% of the direct PFC were found to possess receptors. Receptors could not be detected on indirect PFC in either the primary or secondary response. Results similar to the above were observed for the primary and secondary anti-hapten response to 3-nitro-4-hydroxy-5-iodophenyl acetic acid coupled to diphtheria toxoid (NIP-TOX). The receptors on the antibody-forming cells were shown to possess a class-specific heavy chain determinant (TgM) as well as two allotypic determinants, one a product of the a locus on the heavy chain and the other a product of the b locus on the light chain. The antigen-binding receptors were modulated to cap formation by antibody directed toward either light or heavy chain immunoglobulin determinants. The antigen-binding activity of the receptors was completely destroyed by trypsin.     

Two cheirosporous hyphomycetes reassessed based on morphological and molecular examination

Based on own collections, two species of cheirosporous hyphomycetes (anamorphic Pleosporales) have been reexamined by morphology and molecular analysis. Cheiromyces inflatus is a new record for England. Transfers of Ch. inflatus to Dictyosporium and of Cheiromoniliophora elegans to Pseudodictyosporium are proposed.     

The Influence of Bubbles on the Perception Carbonation Bite

Although many people naively assume that the bite of carbonation is due to tactile stimulation of the oral cavity by bubbles, it has become increasingly clear that carbonation bite comes mainly from formation of carbonic acid in the oral mucosa. In Experiment 1, we asked whether bubbles were in fact required to perceive carbonation bite. Subjects rated oral pungency from several concentrations of carbonated water both at normal atmospheric pressure (at which bubbles could form) and at 2.0 atmospheres pressure (at which bubbles did not form). Ratings of carbonation bite under the two pressure conditions were essentially identical, indicating that bubbles are not required for pungency. In Experiment 2, we created controlled streams of air bubbles around the tongue in mildly pungent CO₂ solutions to determine how tactile stimulation from bubbles affects carbonation bite. Since innocuous sensations like light touch and cooling often suppress pain, we predicted that bubbles might reduce rated bite. Contrary to prediction, air bubbles flowing around the tongue significantly enhanced rated bite, without inducing perceived bite in blank (un-carbonated) solutions. Accordingly, though bubbles are clearly not required for carbonation bite, they may well modulate perceived bite. More generally, the results show that innocuous tactile stimulation can enhance chemogenic pain. Possible physiological mechanisms are discussed.