TGF-beta 1 binding protein: a component of the large latent complex of TGF-beta 1 with multiple repeat sequences

TGF-beta occurs in a latent complex of high Mr. We report the cDNA cloning and an initial structural and functional characterization of a component of the large latent TGF-beta 1 complex, denoted TGF-beta 1 binding protein (TGF-beta 1-BP). Most of the sequence of fibroblast TGF-beta 1-BP is made up of cysteine-rich repeats of two different kinds; there are 16 EGF-like repeats and three repeats with a distant resemblance to EGF, but of a distinct type hitherto not found in any other protein. beta-hydroxylated asparagine residues were identified in two of the EGF-like repeats. TGF-beta 1-BP purified from human platelets is considerably smaller than the fibroblast form (125-160 kd vs. 170-190 kd), suggesting that there is alternative splicing of the TGF-beta 1-BP gene or that TGF-beta 1-BP undergoes cell-specific proteolysis. TGF-beta 1-BP was found not to bind and inactive TGF-beta 1; its role in the latent complex is discussed.     

Interaction of antimicrobial dermaseptin and its fluorescently labeled analogues with phospholipid membranes.

Dermaseptin, a 34 amino-acid residue antimicrobial polypeptide [Mor, A., Nguyen, V. H., Delfour, A., Migliore-Samour, D., & Nicolas, P. (1991) Biochemistry 30, 8824-8830] was synthesized and selectively labeled at its N-terminal amino acid with either 7-nitrobenz-2-oxa-1,3-diazole-4-yl (NBD), rhodamine, or fluorescein. The fluorescent emission spectra of the NBD-labeled dermaseptin displayed a blue-shift upon binding to small unilamellar vesicles (SUV), reflecting the relocation of the fluorescent probe to an environment of increased apolarity. Titrations of solutions containing NBD-labeled dermaseptin with SUV composed of zwitterionic or acidic phospholipids were used to generate binding isotherms, from which were derived surface partition constants of (0.66 +/- 0.06) x 10(4) M-1 and (2.8 +/- 0.3) x 10(4) M-1, respectively. The shape of the binding isotherms, as well as fluorescence energy transfer measurements, suggests that some aggregation of membrane-bound peptide monomers occurs in acidic but not in zwitterionic vesicles. The preferential susceptibility of the peptide to proteolysis when bound to zwitterionic but not to acidic SUV suggests that these aggregates might then penetrate a relatively short distance into the hydrophobic region of the acidic membrane. Furthermore, the results provide good correlation between the peptide's strong binding and its ability to permeate membranes composed of acidic phospholipids, as revealed by a dissipation of diffusion potential and a release of entrapped calcein from SUV.     

Ancient dominance of the Quercus calliprinos - Pistacia palaestina association in mediterranean Israel

Abstract. The natural Mediterranean maquis and forest vegetation of Israel is commonly considered to be composed mainly of four, roughly equal components: Pinus halepensis, deciduous oak, evergreen oak, and Ceratonia - Pistacia communities. They represent the past climax and subclimax of this region. Evidence accumulated from pollen analysis and wood remnant research in geological and archaeological excavations, as well as from written historical sources, shows that this view is wrong: the ancient vegetation in this area was dominated by Quercus calliprinos.     

Attachment of Pasteuria penetrans Endospores to the Surface of Meloidogyne javanica Second-stage Juveniles

Pasteuria penetrans spore adhesion to Meloidogyne javanica second-stage juveniles (J2) was examined following several different pretreatments of the latter. The detergents sodium dodecyl sulfate and Triton X-100, the carbohydrates fucose and α-methyl-D-mannoside, and the lectins concanavalin A and wheat germ agglutinin reduced spore attachment. Spores exposed to M. javanica surface coat (SC) extract exhibited decreased adherence to the J2 surface. Second-stage juveniles that had been treated with antibodies recognizing a 250-kDa antigen of J2 SC extract had fewer spores attached to their surfaces, as compared to nontreated J2, except in the head region. This inhibition pattern was similar to that of antibody-labelling on M. javanica J2 as observed by electron microscopy. It is suggested that several SC components, such as carbohydrate residues, carbohydrate-recognition domains, and a 250-kDa antigen, are involved in P. penetrans spore attachment to the surface of M. javanica.     

Retinoic acid modulates the pattern of cell division in embryos ofLymnaea stagnalis (Mollusca)

All-trans retinoic acid is well known as a modulator of positional specification in vertebrate development. A similar mechanism may operate in molluscan development. Molluscan development is characterized by an invariant pattern of cell divisions, which allows the study of individual cells in the developing organism. Low concentrations of exogenous retinoic acid applied during gastrulation affect the cell division pattern in the early larval stage of the molluscLymnaea stagnalis. A few cells from the apical plate, a larval organ consisting of seven large cleavage-arrested cells, were induced by retinoic acid to resume cell division. They typically formed an area of proliferating small cells that resembles the adjacent areas of precursor cells of adult ectoderm. The identification of individual cells that are transformed by retinoic acid may provide new insights into the mechanisms underlying positional specification within the embryo.     

Impaired cell volume regulation in taurine deficient cultured astrocytes

Taurine concentration was reduced by 40 and 65%, respectively in rat cerebellar astrocytes grown in a chemically defined medium or in culture medium containing a blocker of taurine transport (GES). Cell volume in these taurine deficient cells was 10%–16% higher than in controls. When challenged by hyposmotic conditions, astrocytes release taurine and this efflux contributes to the volume regulatory decrease observed in these cells. Taurine deficient astrocytes showed a less efficient volume recovery as compared to controls with normal taurine levels. Exposed to 50% hyposmotic medium, astrocytes with normal taurine concentration recovered 60% of their original volume whereas taurine deficient cells recovered only 30–35%. Similarly, in 30% hyposmotic medium, taurine deficient astrocytes recovered only 40% as compared to 75% in controls. No compensatory increases in the efflux of other osmolytes (free amino acids or potassium) were observed during regulatory volume decrease in taurine deficient astrocytes.     

Lentil domestication: On the quality of evidence and arguments

The current views on lentil domestication are based on biological attributes of the wild progenitorLens culinaris ssp. orientalis and on assumptions which have never been tested. Seed dormancy, a major factor in the adaptation of ssp.orientalis to its natural habitat, makes it inappropriate for cultivation, because poor germination causes seed yield following cultivation to be equal to the amount of sown seeds. Higher yield, resulting from the evolution of a non-dormant type can be obtained only after five or six cycles of unprofitable cultivation. It is doubtful that incipient farmers would have undertaken such an endeavor without preexisting knowledge that non-dormant types could eventually be obtained. Experiments involving the sowing of wild lentil would have been much more successful if the non-dormant types were present in appreciable quantities in the seed stock. Establishment of that type in the natural population would have required a period of seven to eight years with favorable growing conditions allowing the non-dormant type to become widespread in the population, followed by massive predation by man reducing the hazard of a population explosion. The close similarity between isozyme profiles of the cultivated lentil and its wild progenitor indicates that lentil cultivation was attempted with seeds derived from different populations and in different areas.     

Crystallization and preliminary X-ray analysis of nonglycosylated tissue inhibitor of metalloproteinases-1, N30QN78Q TIMP-1

A nonglycosylated (N₃₀QN₇₈Q) form of the human tissue inhibitor of metalloproteinases, TIMP-1, has been prepared and crystallized in a form suitable for X-ray diffraction analysis. Small single crystals have been grown using sodium tartrate as a precipitant. The crystals are in space group P2₁, with cell dimensions a = 35.28, b = 53.95, c = 48.56, and β = 96.0°. There is a single molecule of TIMP-1 in the asymmetric unit. The crystals diffract to at least 2.3 Å resolution. Complete data have been collected to 2.9 Å and a search for heavymetal derivatives is in progress. © 1993 Wiley-Liss, Inc.     

Activity of single-stranded DNA endonucleases in mung bean is associated with cell division

A single-strand-specific endonuclease from mung bean sprouts is widely usedin molecular biology. However, the biological role of this enzyme is unknown. We studied the spatial and temporal activity of single-stranded DNA endonucleases in mung bean seedling by following enzyme activity that linearizes supercoiled plasmid DNA, a characteristic of this type of enzyme. The formation of a linear molecule from supercoiled DNA was found to occur in two distinguishable steps. The first, which involves introducing a nick into the supercoiled DNA and relaxing it, is very rapid and complete within a few seconds. The second step of cleaving the opposite strand to generate a unit-length linear duplex DNA is a relatively slow process. Analysis of the DNA cleavage sites showed the nuclease preferentially cuts supercoiled DNA at an AT-rich region. Varying levels of nuclease activity could be detected in different tissues of the mung bean seedling. The highest activity was in the root tip and was correlated with histone H1 kinase activity. This implies a link between nuclease activity and cell division. Induction of cell division in mung bean hypocotyls with auxin promoted formation of root primordia and considerably increased the activity of single-stranded DNA endonucleases. The nuclease activity and histone H1 kinase activity were reduced in mung bean cuttings treated with hydroxyurea, but not in cuttings treated with oryzalin. The potential function of single-stranded DNA endonucleases is discussed.