Site-directed mutagenesis of the conserved N-glycosylation site on the nicotinic acetylcholine receptor subunits.

The role of the conserved N-glycosylation site on each subunit of the Torpedo acetylcholine receptor (AChR) in the biogenesis and function of the receptor was examined by expressing site-directed mutant subunits in Xenopus oocytes. Different mutant subunits caused different effects. The most striking effect was seen with the mutant gamma subunit which, when co-expressed with alpha, beta, and delta subunits, caused degradation of all the subunits. N-Glycosylation of the other subunits appears to contribute to stability of the subunits and/or efficient insertion of the receptor into the plasma membrane, but is not required for assembly. The AChRs containing the mutant alpha subunit formed functional ion channels in the plasma membrane and their activity could be blocked by alpha-bungarotoxin (alpha-BuTX). Thus, attachment of a carbohydrate moiety at the conserved N-glycosylation site is not an absolute requirement for the formation of ACh and alpha-BuTX binding sites.     

Problems of the diagnosis and differential treatment procedures in congenital dacryocystitis

The paper analyses effectiveness of treatment for dacryocystitis in 223 children, aged from 1 months up to 15 years. In 35 children the process was bilateral. In 232 cases dacryocystitis was congenital, in 26--acquired. Complex examination of lacrimal and upper respiratory tracts has revealed pathology in 53% of cases. In these cases preliminary sanation of upper respiratory tracts was made. A scheme of a staged treatment for congenital dacryocystitis is proposed, and results after treatment by retrograde catheterization in 161 children aged to 1.5 year and by endonasal dacryorhinostomy in 62 children above 2.5 years of life are analysed.     

Identified motoneurons and their innervation of axial muscles in the zebrafish

The organization of spinal cord motoneurons and their innervation of axial (white) muscles in the zebrafish were studied. Motoneurons can be divided into 2 classes, primary and secondary, on the basis of their cell-body sizes and positions. Each side of each spinal segment contains 3 primary motoneurons that are uniquely identifiable as individuals by their stereotyped cell-body positions and peripheral branching patterns. Moreover, these motoneurons precisely innervate cell-specific subsets of contiguous muscle fibers in mutually exclusive regions of their own body segment. Individual muscle fibers receive inputs from a single primary motoneuron and, in addition, from up to 3 secondary motoneurons. The results demonstrate that the precision of innervation previously described in invertebrates is also present in some vertebrates.