The structure of the neutral polysaccharide gum secreted by Rhizobium strain cb744

A previous investigation of the structure of the extracellular polysaccharide gum from the nitrogen-fixing Rhizobium strain cb744 (a member of the slow-growing Cowpea group) indicated that there were two β-(1→4)-linked d-glucopyranosyl residues for each α-(1→4)-linked d-mannopyranosyl residue, and that each mannose was substituted at O-6 by a β-d-galactopyranosyl residue having 71% of the galactose present as 4-O-methylgalactose. The present study shows that, although the gum appeared to have a simple tetrasaccharide repeating unit, it is composed of two closely associated components. One is a (1→4)-linked α-d-mannan substituted at each O-6 by a β-d-galactopyranosyl residue (71% 4-O-methylated). The second component is a (1→4)-linked β-d-glucan. The existence of the two polysaccharides was established by separation of the β-d-galactosidase-treated gum on a column of concanavalin A-Sepharose 4B. The d configurations were determined and the anomeric attribution of the linkages confirmed by the use of enzymes. The interaction between the two gum components is discussed.     

Development of some male characteristics supported by oestrone but not dehydroepiandrosterone in the boar

Prepubertally castrated boars received subcutaneous injections twice weekly, from 13 to 35 weeks of age, of dehydroepiandrosterone (2 mg/5 kg) or oestrone (1 mg/5 kg). Dehydroepiandrosterone did not support the growth and secretory activity of the accessory organs, or induce copulatory behaviour. However, oestrone caused hypertrophy of the prostate, seminal vesicles and bulbourethral glands which was due to an increase in fibrous stromal tissue and not to the secretory epithelium. Oestrone also induced some male mating behaviour patterns in the presence of an oestrous gilt, although penile extrusion and ejaculation did not occur. The morphological and behavioural effects of the steroid treatments were supported by steroid profiles in blood plasma as seen in comparison with androgen and oestrogen values of intact and untreated castrated boars. It is concluded that oestrogen in the intact boar might enhance the secretion of the accessory organs by affecting the neural control of the secretory processes rather than by increasing the amount of secretory epithelium in the glands.     

Neuromuscular correlates of rhythmical cheliped flexion behavior in hermit crabs

Journal of Comparative Physiology A -     

The parasite load of some African game animals

The total parasite load, helminths and arthropods, was measured in wild antelopes (Antilopinae and Alcelaphinae) in Kenya. Two parasite faunas were present, one consisting of endemic species and the other of species introduced into Africa with human livestock, presumably within the last 2000 years. There was little evidence of natural immunity to helminthic infection and gazelle restricted by ranching died of acute helminth infection. The helminth fauna of antelopes was dissimilar from that of zebra and giraffe which graze in the same savannah area, although species of tick were shared. New host records from Kenya are given for Bigalkenema curvispiculum Gibbons, Paracooperia raphicerci Ortlepp, Trichostrongylus axei Cobbold and T. colubriformis Giles from Gazella thomsonii Gilnther, B. curvispiculum from G. granti Brooke, Cooperia fulleborni Hung from Connochaetes taurinus Burchell and Moniezia expansa Rudolphi from Giraffa camelopardalis tippel-skirchi L. The implication of parasitic infection to conservation programmes and the possible future erosion of the conservation areas in East Africa is discussed briefly.     

Effect of pH on the Immunogenicity of Mycoplasma pneumoniae

Mycoplasma pneumoniae harvested from media which had become acid lost the ability both to induce formation of tetrazolium reduction inhibition antibody and to act as antigens in immunodiffusion against human convalescent-phase sera. Incorporation of N-tris(hydroxymethyl)-2-aminoethane sulfonic acid and N-2-hydroxyethylpiperazine-N'-2-ethane sulfonic acid buffers into a new medium containing PPLO Serum Fraction instead of horse serum delayed the pH decline. Tris(hydroxymethyl)aminomethane, triethanolamine, and 3,6-endomethylene-1,2,3,6-tetrahydrophthalic acid buffers inhibited growth. Mycoplasmas obtained from buffered cultures retained antigenicity as measured by immunodiffusion and could stimulate tetrazolium reduction inhibition antibody formation in animals.     

MEASUREMENT OF INFLUENZA VIRUS-ANTIBODY REACTION BY QUANTITATIVE ELECTRON MICROSCOPY

Measurement of the weight of individual virus particles from untreated and antibody-treated populations was made by quantitative electron microscopy. The weight of antibody bound depended on the concentration of antibody in solution. One population of viruses exposed to an antibody concentration which resulted in 95% inhibition of hemagglutination showed a mass increase of 55%, corresponding to an absolute increase of 9.0 x 10^-17 g in the median value. Another population, whose hemagglutination inhibition assay was 64%, showed a 39% increase in mass corresponding to an absolute median increase of 7.3 x 10^-17 g. The larger viruses in each population bound a greater absolute amount of antibody than did the smaller ones, but the latter bound relatively more antibody in proportion to their mass. No cross-reactivity was found between the antibody to influenza A/PR8 and the influenza strain B/LEE. Influenza A/PR8 controls exposed to nonspecific gamma-globulin displayed a significant weight loss, at least in part owing to loss from the core, as judged from the electron micrographs.