Anti-My-26: a monoclonal antibody inhibiting human phagocyte chemiluminescence

Anti-My-26, a mouse monoclonal IgG1 antibody, was raised against human granulocytes and has been shown to inhibit luminol-enhanced, glucose-independent chemiluminescence (CL) of human granulocytes (or monocytes) responding to the soluble secretagogues A23187 or ionomycin (calcium ionophores) and phorbol myristate acetate (PMA). Anti-My-26 inhibition of CL was reversible and was dependent on both secretatogue and monoclonal antibody concentration. This inhibition appeared to be directed at the component of granulocyte CL that is independent of NAD(P)H-oxidase-catalyzed formation of superoxide anion, because neither opsonized zymosan-stimulated CL nor the PMA-induced decrease in NAD (P)H-associated autofluorescence was affected by anti-My-26. In addition, ionomycin, over a wide concentration range, failed to generate any decrease in granulocyte autofluorescence. The A23187-induced CL inhibited by anti-My-26 was correlated with its depression of oxygen consumption. Furthermore, anti-My-26 was not cytotoxic and did not itself induce oxidative metabolism when used as a stimulant. Binding of anti-My-26 to phagocytic cells was not decreased by pre-exposure of cells to either A23187 or PMA. Evidence is presented to suggest that the binding of anti-My-26 to the granulocyte surface inhibits the oxidative response to calcium ionophore and PMA by blocking a common pathway(s) stimulated by these different secretagogues.     

Mechanism and dynamics of conformational ordering in xanthan polysaccharide

The thermally induced order-disorder transition of xanthan (extracellular bacterial polysaccharide from Xanthomonas campestris) has been investigated by optical rotation, differential scanning calorimetry, stopped-flow reaction kinetics and low-angle laser light scattering, and the results have been analysed in terms of Zimm -Bragg helix-coil transition theory. The reciprocal of the transition midpoint temperature (Tm) varies linearly with the logarithm of cation (K+) the salt dependence of Tm, is in agreement with Manning polyelectrolyte theory the ordered structure. The associated increase in cation binding, calculated from the salt dependence of tm, is in agreement with the Manning polyelectrolyte theory for one of the candidate structures from X-ray diffraction, a 5(1) single helix stabilized by packing of side-chains along the polymer backbone, but not for the alternative double-helix structure that has also been proposed. At each salt concentration, the two fundamental parameters of the Zimm -Bragg theory, s and sigma, were calculated. The equilibrium constant for growth of the ordered structure (s) is derived directly from calorimetric measurement of transition enthalpy (delta Hcal ), and sigma, which quantifies the relative instability of the helix nucleus, is derived from the ratio of delta Hcal to the apparent transition enthalpy (delta Happ ) obtained by van't Hoff analysis of the optical rotation data. The temperature course of conformational ordering calculated theoretically is in good quantitative agreement with experimental results from both optical rotation and scanning calorimetry. The calculated average length of stable, ordered chain-sequences increases with decreasing temperature, but equals or exceeds the total chain length from light scattering only at temperatures more than approximately equal to 70 K below Tm, suggesting that ordered and disordered regions may co-exist within the same xanthan molecule. Consistent with this interpretation, the observed rate of conformational ordering increases sharply under conditions where the starting solution for dynamic measurements is partially ordered, suggesting that ordered sequences within each chain may act as helix nuclei for adjacent disordered regions, so that helix growth, rather than the slower nucleation process, becomes rate limiting.     

Hight performance gel permeation chromatography of proteins

Proteins in the molecular weight range of 10 000–170 000 were separated by high performance gel permeation chromatography. Silica particles with 30 nm or 50 nm pores were derivatized with glycidoxy-propyltrimethoxysilane and used as support. The proteins were eluted with 50% formic acid. A protein fraction which induces endodermal and mesodermal tissues in amphibian gastrula ectoderm was purified by this method.     

On the Robustness of the Geometrical Model for Cell Wall Deposition

All plant cells are provided with the necessary rigidity to withstand the turgor by an exterior cell wall. This wall is composed of long crystalline cellulose microfibrils embedded in a matrix of other polysaccharides. The cellulose microfibrils are deposited by mobile membrane bound protein complexes in remarkably ordered lamellar textures. The mechanism by which these ordered textures arise, however, is still under debate. The geometrical model for cell wall deposition proposed by Emons and Mulder (Proc. Natl. Acad. Sci. 95, 7215–7219, 1998) provides a detailed approach to the case of cell wall deposition in non-growing cells, where there is no evidence for the direct influence of other cellular components such as microtubules. The model successfully reproduces even the so-called helicoidal wall; the most intricate texture observed. However, a number of simplifying assumptions were made in the original calculations. The present work addresses the issue of the robustness of the model to relaxation of these assumptions, by considering whether the helicoidal solutions survive when three aspects of the model are varied. These are: (i) the shape of the insertion domain, (ii) the distribution of lifetimes of individual CSCs, and (iii) fluctuations and overcrowding. Although details of the solutions do change, we find that in all cases the overall character of the helicoidal solutions is preserved.     

New Intercommunity Infanticides by the Chimpanzees of Ngogo,Kibale National Park,Uganda

Hostile intercommunity relations, including attacking and killing extra-community infants of both sexes have occurred at most wild chimpanzee sites. We describe three recent cases of intercommunity attacks on infants committed by members of the Ngogo chimpanzee community in Kibale National Park, Uganda. Two of the attacks resulted in confirmed infanticides while a third attack probably resulted in the infant's death. In common with previous accounts of chimpanzee infanticides, the attacks described here occurred during boundary patrols outside the Ngogo community's usual range, adult and adolescent males were the main participants, one infant was cannibalized after being killed, and the victims’ mothers did not accompany the attacking party back to the Ngogo range. However, the patrol parties during each infanticide were larger than before and included females from the Ngogo community. Our observations indirectly support both the range expansion and imbalance of power hypotheses, which address why and under which conditions chimpanzee intercommunity encounters lead to aggression. These cases of intercommunity infanticide add to the growing database of the phenomenon in wild chimpanzees.