Glycosphingolipid patterns of the gastrointestinal tract and feces of germ-free and conventional rats

Acid and non-acid glycosphingolipids of stomach, small and large intestine, and stimulated feces of germ-free and conventional rats of the same stain have been isolated and characterized. The glycosphingolipid patterns of the intestinal organs were chemically and immunologically very similar between the two groups of rats and relatively unaffected by the presence of an intestinal microbial flora. The major exception was the presence of hematoside with N-glycoloylneuraminic acid (NeuGc) (NeuGc alpha 2----3Gal beta 1----4Glc beta 1----1Cer) in the stomach of conventional rats not found in the stomach of germ-free animals. Glycosphingolipids of stimulated feces of germ-free animals were derived from epithelial cells mainly of the small intestine and showed no signs of degradation. Glycosphingolipids of feces of conventional rats completely retained the pattern of blood group A-, B-, and H-active glycolipids as found in sterile feces but contained less of hematoside and more of lactosylceramide. This effect was probably due to degradation by bacteria, as demonstrated in vitro with the production of lactosylceramide after treatment of the isolated acid glycolipids of sterile feces with neuraminidase from Clostridium perfringens. The amount of total non-acid glycosphingolipids per dry weight was similar for stomach, was 50% higher for small intestine, and 300% higher for large intestine of germ-free animals compared to conventional animals. Due to the presence of large amounts of mucins the dry sterile feces contained 12% less non-acid glycolipids than conventional feces. However, calculated per rat per day the germ-free animal excreted more of non-acid glycosphingolipids (1.8 and 1.2 mg, respectively).     

HLA Haplotypes with C4B5; evidence for further allelic heterogeneity

Twenty-three individuals from various disease groups and normal controls were identified by immunofixation with anti-C4, C4-dependent lysis, determination of Rg (Rodgers) and Ch (Chido) phenotypes, and immunoblotting with C4-specific mouse monoclonal antibody. We found that one haplotype predominates with the C4B ^* 5 allele, HLA-A11, B22(55), Cw3, Bf ^* S, C4A ^* 4B ^* 5, which also carries the Ch ^{1,–2, 3} haplotype. The B5 allotype was also found with HLA-1360, HLA-1335 in Caucasoids, and HLA-B18 in non-Caucasoids; these carried the Ch ^{–1, –2, –3} haplotype. Our results are in accord with an earlier report of two B5 subtypes, B5Rg⁺ and B5Rg^– (Roos et al. 1984). The specificity of the mouse monoclonal antibodies IC4 and 21312 had been previously related to C4A and C4B, respectively, but our results suggest that they relate more closely to Rg and Ch determinants.     

Variation in the ribosomal RNA genes among individuals of Vicia faba

Summary Length heterogeneity in the ribosomal repeat of Vicia faba is due to the presence of variable numbers of a 325 bp subrepetitive element within the nontranscribed spacer region. The distribution of size classes among 88 individuals within a population was investigated by blot-hybridization. We find that individual plants can exhibit more than 20 size classes and that hybridization patterns are highly diverse from individual to individual, more so than for any species so far investigated. In contrast, no such differences are observed in patterns for different tissues from a single plant or from parental to F₁ generation. Some changes were observed in the F₂ generation. We conclude that unequal recombination can give rise to the diversity that we observe for the V. faba rDNA repeats.     

Octopamine receptor subtypes and their modes of action

Octopamine receptor subclasses were first proposed to explain differences in the pharmacological profiles of a range of physiological responses to octopamine obtained in the extensor-tibiae neuromuscular preparation of the locust. Thus, OCTOPAMINE₁ receptors which inhibit an endogenous myogenic rhythm, increase intracellular calcium levels. Also OCTOPAMINE₂ receptors which modulate neuromuscular transmission in this preparation, increase the level of adenylate cyclase activity. The current status of this classification is reviewed by examining the pharmacology of responses to octopamine in a range of preparations. It is concluded that the distinction between OCTOPAMINE₁ and OCTOPAMINE₂ receptor types is still valid, but that OCTOPAMINE₂ receptors exhibit some tissue specific variations. Studies on a clonedDrosophila octopamine/tyramine (phenolamine) receptor are discussed and illustrate many of the difficulties presently encountered in making a definitive classification of octopamine receptors. These include the possibilities that single receptors may activate multiple second messenger systems and that different agonists may differentially couple the same receptor to different second messenger systems.     

EMBRYOLOGY OF CALYPSO BULBOSA. I. OVULE DEVELOPMENT

Calypso bulbosa is a terrestrial orchid that grows in north temperate regions. Like many orchids, the Calypso has ovules that are not fully developed at anthesis. After pollination, the ovule primordia divide several times to produce a nucellar filament which consists of five to six cells. The subterminal cell of the nucellar filament enlarges to become the archesporial cell. Through further enlargement and elongation, the archesporial cell becomes the megasporocyte. An unequal dyad results from the first meiotic division. A triad of one active chalazal megaspore and two inactive micropylar megaspores are the end products of meiotic division. Callose is present in the cell wall of the megaspore destined to degenerate. In the mature embryo sac the number of nuclei is reduced to six when the chalazal nuclei fail to divide after the first mitotic division. The chalazal nuclei join the polar nucleus and the male nucleus near the center of the embryo sac subsequent to fertilization.     

ORGANIZATION AND ONTOGENY OF THE VASCULAR SYSTEM IN THE PETIOLE OF EASTERN COTTONWOOD

The topologic arrangement of petiolar bundles varies within the length of the cottonwood petiole. Each petiolar bundle is formed by the subdivision and aggregation of acropetally differentiating subsidiary bundles in a predictable pattern. The subsidiary bundles provide vascular continuity between the stem and specific portions of the leaf lamina. Spot-labeling of individual veins with ¹⁴CO₂, freeze substitution, and microautoradiography were used to establish the relation between the secondary veins of the lamina and the vasculature of the petiole. Within the petiole vasculature each subsidiary bundle was continuous with a specific portion of the lamina and seemed to have a separate function. Subsidiary bundles continuous with the central leaf trace were closely related functionally to the tip region of the lamina, while the subsidiary bundles continuous with the lateral leaf traces were functionally related to the middle and basal portions of the lamina.     

IV. A model system for mass spectrometric sequencing of orthophthalaldehyde peptide derivatives

Presented is a pilot project describing a new strategy for mass spectrometric peptide sequencing. Using orthophthalaldehyde (OPA), two peptides were derivatized and their fluorescent adducts isolated using reversed phase high performance liquid chromatography. The OPA-peptides were permethylated and the derivatized molecules subjected to direct probe mass spectral analysis. The spectra obtained from the OPA-peptides was analogous to those observed for standard $\text{N}$-acyl permethyl derivatives enabling the complete sequence of the peptides to be determined.