Ultrastructural immunolocalization of periodic pectin depositions in the cell wall ofNicotiana tabacum pollen tubes

Summary The monoclonal antibody (MAb) JIM5, marking acidic pectins, was used to localize ultrastructurally pectin molecules in the pollen tube wall ofNicotiana tabacum. Longitudinal sections of LR-White embedded pollen tubes were exposed to antibody treatment; accumulations of pectins were identified by counting the density of the gold particles representing the pectin epitopes along the pollen tube wall. Significant accumulations of gold grains were marked and the distances between them were measured. In many pollen tubes a more or less regular distribution of the accumulations was observed along the tube indicating a periodical deposition of pectin. The distances between the accumulations were 4–6 m. Most of the label was found in the inner part of the outer layer of the bilayered cell wall. These findings correspond to and confirm the earlier observation by our group reporting ring-shaped periodical deposits in pollen tubes after immunofluorescence labelling with the MAb JIM5 under the confocal laser scanning microscope.Abbreviations Ab antibody - MAb monoclonal antibody     

Preparation and discharge of secretion in the subcommissural organ of the rat

Summary The secretion of the subcommissural organ (SCO) of the rat was studied by means of immunocytochemistry at the electron-microscopic level with the use of (1) the polar embedding medium Lowicryl K4M at -30° C, (2) the protein A-gold technique, and (3) a rabbit antiserum against bovine Reissner's fiber (see Sterba et al. 1981).Two different substructures of the ependymal and the hypendymal SCO-cells display a positive immunocytochemical reaction: (1) sacs containing flocculent secretion, which originate from the granular endoplasmic reticulum, and (2) vacuoles filled with fine granular secretion, which are pinched off from the Golgi apparatus. The secretory material of the sacs and the vacuoles is discharged both (i) apically into the cerebrospinal fluid and (ii) basally into intercellular spaces of the SCO-hypendyma. The apically released secretion is condensed to a lamina-like formation, which more caudally assumes the form of Reissner's fiber. The route of the basally released secretion remains, however, vague. The periodically striated bodies, which were thought to be morphological mediators of the discharge of the secretion into the capillaries, are never labeled by gold particles.Supported by grants from the Ministry for Science and Technology of the German Democratic RepublicThe expert technical assistance of Mrs. B. Wolff, Mrs. S. Mehnert, Mrs. E. Siebert, Mrs. Ch. Schneider, and Mrs. I. Seifert is gratefully acknowledged     

Classification and identification of bacteria by Fourier-transform infrared spectroscopy.

This study describes a computer-based technique for classifying and identifying bacterial samples using Fourier-transform infrared spectroscopy (FT-IR) patterns. Classification schemes were tested for selected series of bacterial strains and species from a variety of different genera. Dissimilarities between bacterial IR spectra were calculated using modified correlation coefficients. Dissimilarity matrices were used for cluster analysis, which yielded dendrograms broadly equated with conventional taxonomic classification schemes. Analyses were performed with selected strains of the taxa Staphylococcus, Streptococcus, Clostridium, Legionella and Escherichia coli in particular, and with a database containing 139 bacterial reference spectra. The latter covered a wide range of Gram-negative and Gram-positive bacteria. Unknown specimens could be identified when included in an established cluster analysis. Thirty-six clinical isolates of Staphylococcus aureus and 24 of Streptococcus faecalis were tested and all were assigned to the correct species cluster. It is concluded that: (1) FT-IR patterns can be used to type bacteria; (2) FT-IR provides data which can be treated such that classifications are similar and/or complementary to conventional classification schemes; and (3) FT-IR can be used as an easy and safe method for the rapid identification of clinical isolates.     

Small and medium-angle X-ray analysis of bacterial lipoteichoic acid phase structure.

X-ray scattering analysis was performed on various types of bacterial lipoteichoic acid in solution. The X-ray data show that all samples investigated were characterized by a similar micellar ultrastructure (hydrophilic moiety on the outside) with a fatty acid chain conformation of the disordered, alpha-type at all temperatures between 5 degrees-53 degrees C. The size distribution of Staphylococcus aureus lipoteichoic acid micelles was sufficiently homogeneous to determine their size and some related molecular parameters by detailed small-angle X-ray scattering analysis. Nearly independent of the degree of D-alanine substitution and the ionic strength of the aqueous dispersion, an average micelle contained about 150 lipoteichoic acid molecules arranged in a spherical assembly with a diameter of about 22 nm, whereby the hydrophilic region occupied an outer shell of about 8.5 nm thickness. Based on the average chain length of lipoteichoic acid, it could be estimated that each glycerophosphate residue contributed by about 0.34 nm to the thickness of the hydrophilic shell as compared to a theoretical value of approximately 0.8 nm for a fully extended chain conformation, indicating a highly coiled conformation of the hydrophilic chain. The bearing of these findings on the properties of membrane-associated and secreted lipoteichoic acids is discussed.     

Methane oxidation by methanotrophs and its effects on the phosphate flux over the sediment-water interface in a eutrophic lake

The effect of methane oxidation in aerobic sediment on oxygen consumption and phosphate flux was investigated in diffusion chambers. The diffusion chambers consisted of two compartments separated by a Teflon membrane. In the upper chamber a thin sediment layer was present and the lower chamber was continuously flushed with gas. The hydrophobic membrane allowed for diffusion of gases from the lower chamber through the sediment layer toward the headspace of the upper chamber. In experiments with a methane oxidation rate of 9.8 mmol m^–2 day^–1, the oxygen consumption rate increased by a factor of two compared with controls without methane oxidation (8.6 vs 17.7 mmol m^–2 day^–1). Methane oxidation significantly decreased oxygen penetration depth (2.5–4.0 vs 1.0–2.0 mm). However, despite the shrinkage of the oxidized microlayer, no differences were found in phosphate flux across the sediment water interface. Batch experiments with standard additions of methane revealed that the growth of methanotrophic bacteria contributes to the phosphate uptake of aerobic sediment. From the batch experiments a molar ratio of carbon to phosphate of 45 mol:mol was calculated for the growth of methanotrophs. Results suggest that a decrease in chemical phosphate adsorption caused by a decrease in the oxygen penetration depth could be compensated for entirely by the growth of methanotrophic bacteria. Send offprint requests to: A.J.C. Sinke     

Complete cDNA and gene sequence of the developmentally regulated arylphorin of Calliphora vicina and its homology to insect hemolymph proteins and arthropod hemocyanins.

Two cDNA libraries were prepared from poly(A)+ RNA isolated from fat bodies of last instar larvae of the blowfly Calliphora vicina. The libraries were probed with a genomic clone containing the coding sequence for an arylphorin subunit. Two cDNA clones as well as the genomic clone were mapped and their nucleotide sequences were determined. This revealed the presence of an open reading frame corresponding to a polypeptide with 759 amino acid residues. The deduced primary structure of Calliphora arylphorin and hemolymph proteins of other insect species and arthropod hemocyanine show nearly 30% identity. Highly conserved regions could be also identified.     

A locus for familial hypertrophic cardiomyopathy is closely linked to the cardiac myosin heavy chain genes, CRI-L436, and CRI-L329 on chromosome 14 at q11-q12

We report that a gene responsible for familial hypertrophic cardiomyopathy (HC) is closely linked to the cardiac alpha and beta myosin heavy chain (MHC) genes on chromosome 14q11. We have recently shown that probe CRI-L436, derived from the anonymous DNA locus D14S26, detects a polymorphic restriction fragment that segregates with familial HC in affected members of a large Canadian family. Using chromosomal in situ hybridization, we have mapped CRI-L436 to chromosome 14 at q11-q12. Because the cardiac MHC genes also map to this chromosomal band, we have determined the genetic distances between the cardiac beta MHC gene, D14S26, and the familial HC locus. Data presented here show that these three loci are linked within 5 centimorgans on chromosome 14 at q11-q12. The possibility that defects in either the cardiac alpha or beta MHC genes are responsible for familial HC is discussed.