A broadly active viral inhibitor in human and animal organ extracts and body fluids

To help assess the possibility that a newly described viral inhibitor from cell cultures might play a natural defensive role in vivo, its distribution and concentration in human and animal organ extracts and body fluids were investigated. The concentration of the inhibitor was high in human liver, heart muscle, splenic extracts, and human serum and milk. The inhibitor in the body was indistinguishable from a previously described inhibitor produced in cell cultures that was characterized by broad antiviral activity, lack of target cell species specificity, lack of induction of stable antiviral activity in cells, rapid reversibility of antiviral action, prevention of virus attachment, and stability at 100 degrees C. Sixteen virus plaque reduction units of the inhibitor diminished the yield of poliovirus in vitro by more than 1000-fold. Additional evidence that contact-blocking viral inhibitor (CVI) inhibits vaccinia virus attachment to cells is presented. A role for the inhibitor in natural defense against viral infections is possible.     

Transbilayer distributions of red cell membrane phospholipids in unilamellar vesicles

The phospholipid organization in unilamellar vesicles comprised of various purified phospholipid components of monkey erythrocyte membrane was ascertained using phospholipase A2 and trinitrobenzenesulfonic acid as external membrane probes. The vesicles were formed by sonication or detergent dialysis and fractionated by centrifugation or gel permeation chromatography. Experiments were done to confirm that the phospholipase A2 treatments did not cause lysis or induce fusion of the vesicles. This enzyme hydrolysed only the glycerophospholipids in the outer surface of the vesicles. The amounts of the external phospholipids determined by this enzymatic method were verified using the chemical probe, trinitrobenzenesulfonic acid. The choline-containing phospholipids and phosphatidylethanolamine localized randomly in the two surfaces of sonicated vesicles (outer diameter, about 30 nm), whereas phosphatidylserine preferentially distributed in the inner monolayer. This phosphatidylserine asymmetry virtually disappeared in detergent dialysed vesicles (outer diameter, about 45 nm). Furthermore, inclusion of cholesterol in both the types of vesicles resulted in more random glycerophospholipid distributions across the plane of vesicles bilayer, presumably due to the cholesterol-induced increases in the size of vesicles. These results demonstrate that the transbilayer distribution of erythrocyte membrane phospholipids in unilamellar vesicles are controlled mainly by the surface curvature rather than by interlipid interactions, and therefore suggest that phospholipid-phospholipid and phospholipid-cholesterol interactions should not play any significant role in determining the membrane phospholipid asymmetry in red cells. It is proposed that this asymmetry primarily originates from differential bindings of phospholipids with membrane proteins in the two leaflets of the membrane bilayer.     

Metalloproteinase inhibitors from bovine cartilage and body fluids

Inhibitors of the mammalian metalloproteinases, collagenase, proteoglycanase and gelatinase were isolated from bovine cartilage (extracts and culture medium) and bovine amniotic fluid and serum. These inhibitors either bind or do not bind to concanavalin-A--Sepharose, with Mr (gel filtration) of about 30 000 and 20 000, respectively. Cartilage and chondrocyte culture media contained only concanavalin-A-binding inhibitors whereas cartilage extracts contained only a non-binding inhibitor: serum and amniotic fluid contained both forms of inhibitory activities. In moist biochemical respects, particularly in their abilities to inhibit metalloproteinases, all of the inhibitors were found to be similar. It is concluded that the forms of the inhibitors that differ in Mr may be closely related to the tissue inhibitor of metalloproteinases (TIMP) previously purified from rabbit and human sources. These findings help to clarify other studies on collagenase inhibitors and support the concept that TIMP-like inhibitors may be important in the control of connective tissue degradation.     

A new species ofLiparis (Orchidaceae) from India

Liparis indiraii spec. nova from India is close toL. alata A. Rich. andL. atropurpurea Lindl.     

Target antigens in malaria transmission blocking immunity

Malaria transmission blocking immunity has been found to operate against two distinct phases of development of malaria parasites in the mosquito midgut: (i) against the extracellular gametes and newly fertilized zygotes shortly after ingestion by a mosquito of parasitized blood and (ii) against the zygotes during their subsequent development into ookinetes. Immunity is antibody-mediated and stage-specific. A set of three proteins, synthesized in the gametocytes, expressed on the surface of the gametes and newly fertilized zygotes and subsequently shed during later transformation of the zygotes, has been identified as the target antigens of anti-gamete fertilization blocking antibodies. A single protein, synthesized and expressed on the zygote surface during its development to ookinetes, has been identified as the target of antibodies which block the development of the fertilized parasites in the mosquito. Immunization of human populations against gamete or zygote antigens, while not directly protecting an immunized individual from inflection, would reduce the transfer of malaria within the population. Such immunity, in addition to reducing the overall rate of malaria transmission, would, if combined with a vaccine against the asexual (disease-causing) stages, reduce the chance of selection of parasites that are resistant to the asexual vaccine by preventing their entry into the mosquito population.     

Resonance Raman-spectroscopic studies of the hapten features involved in the binding of 2,4-dinitrophenyl haptens by the mouse myeloma proteins MOPC 315 and MOPC 460.

The binding of four dinitrophenyl haptens to the mouse myeloma proteins MOPC 315 IgA (immunoglobulin A) and MOPC 460IgA was studied by resonance Raman spectroscopy. Isotopic substitution with 15N and 2H was used to assign features in the resonance Raman spectra of the free haptens. Changes in each of these features on binding to the proteins could then be attributed to interactions of the proteins' binding sites with either the p-NO2 or the o-NO2/amine regions of the haptens. The interactions between a given hapten and MOPC 315 IgA are often quite distinct from those between the same hapten and MOPC 460 IgA. Moreover, for both antibodies the nature of the R side chain in a Dnp-NHR (Dnp, 2,4-dinitrophenyl) compound appears to modify the interactions between the Dnp chromophore and the protein. Thus, with the haptens studied, there is no unique set of contacts between the Dnp group and the binding site. The contacts expected between epsilon-2,4-dinitrophenyl-L-lysine and the site on MOPC 315 IgA, on the basis of a recent model for this site [Dwek, Wain-Hobson, Dower, Gettins, Sutton, Perkins & Givol (1977) Nature (London) 266, 31--37] were not detected. However, the contacts between this hapten and the site on MOPC 460 IgA were closer to those predicted by the model for MOPC 315 IgA.     

Axial ranking of residues in collagen in relation to edge association and fibril formation

In our earlier analysis of intermolecular interactions between collagen molecules, a major concern with the program employed is that it compared numbers of interactions between residues located on edges of defined, identical width and thus would not necessarily compare the same number of residues in each edge. This would be particularly true of some values of θ where well-defined vertical ranking of residues occurs. We have examined ranking of residues in relation to intermolecular edge association between bovine skin [α1(I)]₃ model collagen molecules by utilizing two different methods of counting intermolecular interactions between residues. The interaction peaks at θ = 27.69° and 36.00° are absent or relatively less intense in the plots obtained by utilizing radial distances between interacting residues instead of vertical bands of defined width. These studies suggest caution in accepting recently reported analyses of superhelix coiling of the collagen molecule which point to values of 27.69° or 36.00° for the twist of the superhelix. Although intramolecular interactions clearly point to interaction of collagen molecules at D intervals, they are insufficiently restricted in distribution to provide a reliable estimate of the superhelix angle by procedures so far employed.     

Proleptonchoides southindiae n. gen., n. sp., a New Leptonchoid from South India

Proleptonchoides southindiae n. gen., n. sp. (Dorylaimida: Leptonchidae), is described from soil around false tobacco (Lobelia excelsa) and cardamom (Elettaria cardamomurn) in South India. P. southindiae is prodelphic, has a short constricted esophageal bulb and flanged odontophore, and is phylogenetically close to Proleptonchus.