Synthesis of carbamyl and ether analogs of phosphatidylcholines

A complete synthesis of 1-O-hexadecyl-2-O-N-(heptadec-8-cis-enyl)carbamyl-sn-glycero-3-Phosphocholine, a novel analog of phosphatidylcholine, has been described. Each step is simple to perform and gives the desired products in high yield. Also, some of the intermediates formed during the synthesis have been efficiently utilized to prepare 1-O-hexadecyl-2-O-oleyl-sn-glycero-3-phosphocholine, 1-O-hexadecyl-2-oleoyl-sn-glycero-3-phosphochloine and 3-O-hexadecyl-2-oeloyl-sn-glycero-1-phosphocholine. These phosphatidylcholine (PC) analogs are useful for studying the possible role of phospholipases in the capture and lyses of liposomes in vivo.     

Deuterium magnetic resonance study of the interaction between chondroitin sulfate and human plasma low density lipoproteins

[²H]Chondroitin sulfate was prepared by partial $\text{N}$-deacetylation of chondroitin sulfate ($\text{via}$ hydrazinolysis) followed by treatment with [²H₆]acetic anhydride. ²H NMR spectra of [²H]chondroitin sulfate in the presence of human plasma low density lipoprotein provide evidence for a soluble complex stoichiometry of 3 (and possibly 2) lipoproteins per polysaccharide molecule, and allow a rough estimation of the dissociation constant K_d.     

Perception of residential crowding,classroom experiences,and student health

The present research is based on a typology of crowding experiences incorporating two main dimensions: neutral-personal thwartings and primary-secondary environments. The thwarting dimension concerns the degree to which crowding experiences are associated with spatial inconveniences, alone, or with spatial as well as social constraints. The environmental dimension relates to the type of setting in which crowding experiences occur. A major assumption of this typology is that crowding experiences involving social conflict will be more intense and disruptive to the individual than those in which interpersonal conflict is minimal. The reported study examined the relationship between college students' evaluations of the physical amenity, social climate, and crowdedness of their residential environments, on the one hand, and their sensitivity to crowding in a classroom situation, their academic performance, and the frequency of their visits to the campus health center, on the other. Results indicated that perceived residential crowding and negative perceptions of residential social climate were strongly associated with increased sensitivity to crowding in a classroom situation, impaired course performance, and visits to the student health center. The implications of these correlational findings for future field-experimental research are discussed.     

Pleiotropic consequences of mutations towards antibiotic-hypersensitivity in Serratia marcescens

Various mutants (oxa ^s ) were isolated from Serratia marcescens SM-6 by selecting for hypersensitivity towards oxacillin. All mutants found are highly pleiotropic and able to yield spontaneous revertants which behave like the wild-type. Mutant W 1421 mostly studied shows the following phenotypic properties not found in the wild-type: (1) The growth is hypersensitive to various antibiotics, detergents and dyes which differ remarkably in their chemical structure and antibacterial action-mechanism, (2) the cells can be easily solubilized by 0.05% Sodium-dodecylsulfate, (3) the cells allow the adsorption of the roughmutant specific Salmonella phage 6SR, (4) strong cellular binding of crystal violet, (5) agglutination of the cells in 0.3% auramin solution and (6) reduced formation of red pigment. Strain W 1421 is assumed to be a lipopolysaccharide-defective mutant. The outer membrane of mutant W 1421 analyzed by Sodiumdodecylsulfate-polyacrylamide gel electrophoresis possesses a single protein less than that of the wild-type. Mutant W 1421 is further characterized by its low exolipase activity; exoprotease and exonuclease activities are as in the wild-type. This specific exoenzyme deficiency can be overcome either by backmutation to oxacillin-resistance or by growing mutant W 1421 in a medium supplemented with certain non-metabolizable polysaccharides, e.g. glycogen or pectin B. Both polysaccharides increase the exolipase activity of the wild-type too.List of Abbreviations amp ampicillin - LPS lipopolysaccharide - MIC minimal inhibitory concentration - NB nutrient broth - oxa oxacillin - str streptomycin - TBY tryptone broth with yeast extract - SDS sodium-dodecylsulfate - OD optical density This paper is dedicated to Prof. Dr. R. W. Kaplan, University of Frankfurt/M., on the occasion of his 65th birthday     

Molecular and cytological characteristics of nuclear DNA and chromatin for angiosperm systematics: DNA diversification in the evolution of four orchids

The species- and genus-specific DNA content, average base composition of nuclear DNA, presence or absence of satellite DNA, the percentage of heterochromatin and other characteristics of nuclear DNA and nuclear structure allow to deduce the molecular changes which accompanied, or more probably caused, cladogenesis in the orchids studied. It is suggested that saltatory replication (generative amplification) of certain DNA sequenes, diversification of reiterated DNA sequences, and loss of DNA play an important role in the evolution of orchids.—The relationship between changes of genome composition and of nuclear structure and ultrastructure is discussed on the basis of cot curves, heterochromatin staining with Giemsa (C banding), electron microscopy of nuclei, and molecular hybridization in situ.Some aspects of this paper have been presented at the Helsinki Chromosome Conference, August 1977 (Nagl & Capesius 1977).     

A contaminant,Erwinia carotovora,affecting commercial plant tissue cultures

Summary Commercial plant tissue cultures of several ornamental plants exhibiting reduced vigor and chlorosis in stage II were found to contain bacterial contaminants. In most cases, visible evidence of the contaminants in the tissue-culture medium was not easily discernible. Physiological and pathological tests employing pure cultures proved 5 of the 10 isolates obtained to beErwinia carotovora, an important pathogen of many horticultural plants. The tissue cultures from whichE. carotovora was isolated were of plant types nonsusceptible under normal commercial production methods. These results indicate nonhost plants may serve as carriers ofE. carotovora during tissue-culture propagation and also possibly under normal methods of commercial production. Florida Agricultural Experiment Stations Journal Series No. 883. This investigation was supported in part by The Fred C. Gloeckner Foundation.     

Neonatal rat hepatocytes in primary tissue culture free from density-dependent regulation of growth

Summary Studies employing [³H]thymidine and radioautography as well as colchicine and Feulgen staining of DNA showed that up to 19-fold increases in the degree of cell crowding in vitro, i.e. from 1.45 to 27.55×10⁴ cells per specimen, did not change the rates of entry into DNA synthesis and mitosis of cultivated primary neonatal rat hepatocytes.