Mechanism of Linolenic Acid-induced Inhibition of Photosynthetic Electron Transport

The effect of linolenic acid on photosynthetic electron transport reactions in chloroplasts has been localized at a site on the donor side of photosystem I and at two functionally distinct sites in photosystem II.     

Two replantations of severed ear parts.

Two successful cases of replantation of part of an ear are presented; both were done by simple suture. The larger of these replants consisted of a 13 x 43 mm segment of the superior helix and concha. Both were vascularized beofre 48 hours. The greatest problem was venous congestion. In the larger replant we made multiple puncture wounds daily on both sides of the graft with an 18-gauge needle to help relieve this.     

Approximate solution of a model of biological immune responses incorporating delay

A model of the humoral immune response, proposed by Dibrov, Livshits and Volkenstein (1977b), in which the antibody production by a constant target cell population depends on the antigenic stimulation at earlier times, is considered from an analytic standpoint. A method of approximation based on a consideration of the asymptotic limit of large delay in the antibody response is shown to be applicable, and to give results similar to those obtained numerically by the above authors. The relevance of this type of approximation to other systems exhibiting outbreak phenomena is discussed.     

A new method for the production of fine plant cell suspension cultures

Fine, almost single cell, suspensions were produced from both existing suspension cultures containing large cell clumps and from chopped callus pieces by immobilizing the cells in 4–5 mm diameter calcium alginate beads. The immobilized cells continued to divide inside the beads and at the bead surface, and after 2–3 weeks' culture, fine cell suspensions were formed as a result of loss of the surface cells into the medium. After removal of the cell suspensions by filtration, subsequent culture of the beads in fresh medium resulted in the further production of homogeneous cell suspensions after 1–2 weeks. In this way an almost continuous supply of fine cell suspensions could be obtained from cultures containing large clumps of cells. The cells produced by this method remained in this state for at least one culture period, although in some instances repeated subculture resulted in an increase in the size of cell groups. The technique has been successfully applied to the production of fine cell suspensions ofCatharanthus roseus, Nicotiana tabacum andDaucus carota.     

Sexual Therapy of Patients with Cardiovascular Disease

Physical illness or disability inevitably has a damaging effect on sexual relationships. Physicians are usually unaware of the sexual consequences of illness on their patients, and lack experience in treating sexual dysfunctions.The report of treatment of a couple with serious cardiovascular disease illustrates the potential efficacy of brief sex therapy for improving the quality of a patient''s life. If a primary physician lacks the skills to conduct sex therapy, he may collaborate with nonphysician therapists. The physician''s knowledge of the physiological and psychological effects of a specific illness on his patient is essential to successful therapy. Often, simple education, encouragement or reassurance by the physician is enough to overcome the damaging effects of illness on a patient''s sex life.     

Amino acid sequence of beta-galactosidase. IX. Sequence of the central segment, CNBr peptides 10 to 17, residues 378 to 653.

The amino acid sequence in the 8 cyanogen bromide peptides comprising the central segment of beta-galactosidase is presented. This portion of the molecule, about 27% of the protein, contains over 40% of the lysine and tyrosine residues and has a slight excess of basic amino acids.     

Association of spectrin with its membrane attachment site restricts lateral mobility of human erythrocyte integral membrane proteins

Interactions between spectrin and the inner surface of the human erythrocyte membrane have been implicated in the control of lateral mobility of the integral membrane proteins. We report here that incubation of “leaky” erythrocytes with a water-soluble proteolytic fragment containing the membrane attachment site for spectrin achieves a selective and controlled dissociation of spectrin from the membrane, and increases the rate of lateral mobility of fluorescein isothiocyanate-labeled integral membrane proteins (> 70% of label in band 3 and PAS-1). Mobility of membrane proteins is measured as an increase in the percentage of uniformly fluorescent cells with time after fusion of fluorescent with nonfluorescent erythrocytes by Sendai virus. The cells are permeable to macromolecules since virus-fused erythrocytes lose most of their hemoglobin. The membrane attachment site for spectrin has been solubilized by limited proteolysis of inside-out erythrocyte vesicles and has been purified (V). Bennett, J Biol Chem 253:2292 (1978). This 72,000-dalton fragment binds to spectrin in solution, competitively inhibits association of ³²P-spectrin with inside-out vesicles with a K_i of 10^?7M, and causes rapid dissociation of ³²P-spectrin from vesicles. Both acid-treated 72,000-dalton fragment and the 45,000 dalton-cytoplasmic portion of band 3, which also was isolated from the proteolytic digest, have no effect on spectrin binding, release, or membrane protein mobility. The enhancement of membrane protein lateral mobility by the same polypeptide that inhibits binding of spectrin to inverted vesicles and displaces spectrin from these vesicles provides direct evidence that the interaction of spectrin with protein components in the membrane restricts the lateral mobility of integral membrane proteins in the erythrocyte.     

Transference of the high molecular weight carbohydrate sequences of fetuin to the surface of carrot embryo protoplasts

A method is described for the removal of the carbohydrate sequences of glycoproteins, and their covalent attachment to hydrocarbon chains. These synthetic membrane components may then be incorporated into liposome and cell membranes. Pronase-liberated glycopeptides derived from fetuin were linked by a reduced Schiff's base linkage to tetradecyl aldehyde. The resulting glycolipid was incorporated by external addition, into phosphatidylcholine liposomes. Glycolipid transfer to these liposomes rendered them suseptible to agglutination by wheat germ lectin, which binds N-acetylneuraminic acid, the terminal carbohydrate of the high molecular weight fetuin sugar sequence. Sequential removal of the terminal sugars, and subsequent agglutination behaviour towards various lectins, suggests that the carbohydrate sequence had been transfered intact. The glycolipid was incorporated into plant protoplast membranes by incubation with glycolipid-containing liposomes for 2 h at 37°C. These synthetic glycolipids may find a use in the study of carbohydrate-based recognition systems in animal and plant membranes. In addition they may prove useful in the development of cell and membrane tagging and handling techniques, by the insertion of sugar groups not normally present in these membranes.