A highly antigenic proteoglycan-like component of cholinergic synaptic vesicles

A monoclonal antibody, tor70, recognizes an antigenic determinant on the inside surface of synaptic vesicles, purified from the electric organ of Narcine brasiliensis. The antigenic determinant appears to be unique to vesicles since it co-purifies with vesicle content and is blocked by an antiserum specific for synaptic vesicle antigens. Immunoblotting of vesicle proteins after sodium dodecyl sulfate-polyacrylamide gel electrophoresis shows that the antigen has a low heterogeneous electrophoretic mobility and corresponds to a major protein component of pure synaptic vesicles. Synaptic vesicles contain a proteoglycan-like material since proteolytic digestion yields a ruthenium red-binding material that migrates during electrophoresis with a mammalian heparin standard. The only major vesicle component with which the proteoglycan-like material co-elutes during chromatography on Sepharose 6B is the material recognized by tor70. The antigen adsorbs specifically to beads coated with the lectin wheat germ agglutinin. Isolation of the tor70 antigen by velocity sedimentation in sodium dodecyl sulfate-sucrose gradients shows it to contain glucosamine (0.75 nmol/microgram of protein) and uronic acid but no galactosamine. Earlier work has shown that specific antiserum to pure synaptic vesicles could be used to identify nerve terminals, quantitate vesicle components, purify membranes, and monitor exocytosis. We now know that one of the components recognized by the antiserum is a molecule with properties of a proteoglycan, attached to the inside surface of vesicle membranes.     

Blocking of human T lymphocyte functions by anti-Leu-2 and anti-Leu-3 antibodies: differential inhibition of proliferation and suppression

We have shown previously that monoclonal antibodies to the Leu-2 and Leu-3 T cell antigens block the response of their respective subsets in allogeneic MLR. The present study was an effort to explore the mechanism of inhibition and to determine if anti-Leu-2 and anti-Leu-3 antibodies affect the responses to stimuli in addition to alloantigens. Our results indicate that antibodies to Leu-2 and Leu-3 have profound inhibitory effects on proliferation by their respective T cell subsets responding to a variety of stimuli, including specific soluble antigens and alloantigen. This effect was characterized by the following features: a) For optimal inhibition of proliferation, antibody must be present at the onset of antigenic stimulation. b) Inhibition is augmented by increasing the concentration of antibody or decreasing the concentration of antigen. c) Fab fragments of both anti-Leu-2a and anti-Leu-3a antibodies also block proliferation. In addition to their effects on T cell proliferation, anti-Leu-3 antibody blocked T cell-dependent lg synthesis induced in MLR, and anti-Leu-2 antibody prevented the induction, in vitro, of Leu-2+3- suppressor cells of lg synthesis. Taken together, these results suggest that antibodies to antigenic determinants on the Leu-2 and Leu-3 molecules competitively block segments of these structures that bind to alloantigen or nominal antigen. On the other hand, anti-Leu-2a antibody failed to block suppression of the MLR by in vivo activated, antigen-specific Leu-2+3- suppressor cells, which suggests that the Leu-2a epitope does not transmit antigen-specific signals from these differentiated suppressor T cells.     

The promotion of collagen polymerization by lanthanide and calcium ions.

Ca2+ (1-5 mM) and lanthanide (20-250 microM) ions enhance the rate of polymerization of purified calf skin collagen (1.5 mg/ml) at pH 7.0 in the presence of 30mM-Tris/HCl and 0.2 M-NaCl. Both the nucleation phase and the growth phase of polymerization are accelerated. The activation energy of the growth phase, 239.3 +/- 24.3 kJ/mol (57.2 +/- 5.8 kcal/mol), is decreased to 145.6 +/- 9.6 kJ/mol (34.8 +/- 2.3 kcal/mol) by 5 mM-Ca2+ and to 75.3 +/- 4.6 kJ/mol (18.0 +/- 1.1 kcal/mol) by 25 microM-Sm3+. In contrast, the activation energy of the nucleation phase, 191.6 +/- 23.4 kJ/mol (45.8 +/- 5.6 kcal/mol), is only slightly decreased by Ca2+ or Sm3+. Collagen fibrils formed in the presence of Sm3+ are thinner than control fibrils, and more thermoresistant.     

Leg chaetotaxy and the classification of the Uropodina (Acari: Mesostigmata)

Details of the segmental chaetotaxy of the legs of 47 species of Uropodina are given. On the basis of the ontogenetic development of the chaetotaxy, the Uropodina may be divided into two groups which coincide with the concepts of the Lower (Polyaspidoidea) and Higher (Uropodoidea) Uropodina of certain authors. Chaetotactic criteria do not support the classification of the Polyaspidini and Trachyuropodini sensu Hirschmann and Z-Nicol within the Oplitinae Hirschmann & Z-Nicol, the Diarthrophallini within the Uroactiniinae Hirschmann & Z-Nicol or the genus Trachytes within the Uropodini.
A critical appraisal is given of the classification of the Uropodidae (based on "Gangmerk-male") by Hirschmann and Z-Nicol.     

Complementary Functioning of Nitrogenase Components from a Blue-Green Alga and a Photosynthetic Bacterium

Nitrogenases from Anabaena cylindrica and Chloropseudomonas ethylicum were partially purified into two components. A. cylindrica fraction I protein complemented fraction II protein from C. ethylicum. However, the reciprocal cross between C. ethylicum fraction I and A. cylindrica fraction II was negative.     

A re-evaluation of polypodium bradeorum and P. Colysoides

During field studies on the pteridophytes of Costa Rica, a peculiarly dimorphic polypodioid fern was found in the rain-forests of the Atlantic lowlands near Puerto Viejo. The variation in the fertile frond, ranging from simple and short petiolate to pinnatisect and long petiolate, coupled with peculiarly elongate and irregular sori, prompted further investigations. Additional herbarium specimens from localities in Mexico, British Honduras, Nicaragua, and Costa Rica showed intermixed variations between plants with all leaves simple (typified byPolypodium bradeorum Rosenstock) to plants with all leaves lobed or pinnatisect (typified byP. colysoides Maxon & Copeland). Other characters were judged sufficiently homogeneous to consider these individuals as conspecific underP. bradeorum. Morphological studies indicate parallel evolution of several characters in the Asiatic generaColysis, Microsorium, andLeptochilus on the one hand and the New World members ofMicro gramma, Pleopeltis, andPolypodium bradeorum on the other