Search for lectins in seeds of tropical trees of Kerala, India

Tissue specific plant lectins were searched in the seeds of 44 tropical trees of Kerala, India. Seeds of only 12 plant species showed lectin activity. N-acetyl-D-galactosamine was the best inhibitor of lectin activity for the majority of the seeds. Lectin activity in the seeds of 4 species were not inhibited by any of the mono- or polysaccharides used. This revised version was published online in July 2006 with corrections to the Cover Date.     

Analysis of mannose-resistant adhesins of Escherichia coli by a naturally occurring glycoprotein receptor analogue

Hydatid cyst fluid (HCF) contains P₁-substance, a glycoprotein with a terminal trisaccharide identical to that of the P₁ blood group antigen. Quantitative and qualitative haemagglutination inhibition tests show that sheep, horse and pig HCF contain a specific inhibitor for the mannose-resistant haemagglutination of human erythrocytes by P-fimbriate Escherichia coli isolated from symptomatic urinary tract infections. Thus, HCF provides a source of receptor material which is invaluable for the detection and analysis of adhesins on uropathogenic organisms. Only the inhibitors in sheep and horse HCF were present in useful concentrations.     

Immunological studies of the mechanism of anaemia in experimental Trypanosama evansi infection in rats

Pathological changes in the blood of rats acutely infected with Trypanosoma evansi and the probable mechanism of the accompanying anaemia, were investigated. A severe anaemia, together with rreticulocytosis and hepato-splenomegaly, were regularly observed. Histological examination of the liver, spleen and bone-marrow confirmed the increasedin erythropoietic activity that the observed anaemia was due to increasedextravascular destruction of erythrocytes rather than by inhibition of haemopoietic activity. All the infected rats showed significant immune responses to the infecting trypanosome peak agglutinin titres occurring 10–12 days after injection, coincidentally with maximun destruction of erythrocytes. Serological examination of sera and erythrocytes from all infected and control rats did not reveal the presence of either circulating or adsorbed erythrocyte auto--antibodies. Furthermore, there was no in vivo trypanosomal antigen coating of the erythrocytes from either infected or multiple antigen-injected rats. Repeated intraveoous injections into rats of more than 100 μg per g body weight of soluble T. evansi antigen resulted in moderately severe, probably antibody-mediated, haemolytic anaemia. It is considered that an immunologically-mediated mechanism may be responsible for the development of the anaemia accompanying T. evansi infection.     

Effects of physico-chemical treatments on hemagglutination activity of Anopheles gambiae haemolymph and midgut extract

Abstract. Anopheles gambiae midgut extracts and haemolymph possessed agglutinins, titre 1:16 to 1:256, against human red blood cells (RBCs). Subjection of both tissues to protein precipitation reagents, organic chemical and selected protease, neuraminidase and other glycosidic hydrolase treatments revealed the haemagglutinins to be protein, most likely glycoprotein, in nature - not lipoprotein, lipid, glycolipid or nucleic acid. An.gambiae agglutinins were thermo-labile >40^oC, affected by freezing and thawing treatments, and contained disulphide and hydrogen bonds on the basis of sensitivity following exposure to dithio-threitol and urea respectively. Optimum haemagglutination depended generally on slightly acid to neutral pH conditions and agglutinin activity was Ca²⁺ ion, albeit to a lesser extent Mg²⁺ ion, dependent. The midgut extract agglutinin subunit molecule had a relative molecular weight (M_r) of 65kDa whilst that of haemolymph was 40kDa.
This study presents the first report on selected physico-chemical properties, the glycoproteinaceous nature and tentative subunit M_r of mosquito midgut extract and haemolymph anti-RBC agglutinin(s).