Contents Volume 131 2003

Volume Contents

Contents Volume 131 2003     

Genetic typing of bovine viral diarrhoea virus isolates from India

Thirteen BVDV isolates collected in four geographic regions of India between 2000 and 2002 were typed in 5'-UTR. To confirm results of genetic typing, selected viruses were also analysed in the N(pro) region. Phylogenetic analysis revealed that all Indian BVDV isolates belong to BVDV-1b (Osloss-like group). Despite a long distance between the farms from which the viruses were isolated there was no correlation between the origin of viral isolates and their position in a phylogenetic tree. Higher genetic similarity of Indian BVDV isolates was observed most probably due to the uncontrolled movement of cattle as well as the uncontrolled use of semen from bulls for breeding of local and farm cattle in different states of India.     

Karyotype Analysis of Sesbania rostrata Brem.

The karyotype of Sesbania rostrata, a species endemic to West Africa, which produces nitrogen fixing, nodules on stem and branches, was analysed. The somatic chromosome number was 12 with two pairs of long, submetacentric and four pairs of short, metacentric chromosomes. The chromosome number in another species S. aculeata, which is well adapted as a green manure crop in India but not capable of stem nodulation, was also 2n = 12. The similarity between the chromosome complements of the two species indicates that they may be cross compatible.     

Modification of Leaf Photosynthesis by Foliar Application of Aliphatic Alcohols

A decrease in net photosynthesis (P_n) in leaves of main shoot with age ( 7 -28 days after opening) at two stages of peanut ( Arachis hypogaea L. var. M-13 ) reproductive growth (70 and 90 DAS) is reported. P_n rate decreased with advance in age of leaves, the decline was rapid during peak period of pod filling (90 DAS). Foliar application with aliphatic alcohols, maintained the chlorophyll content and enhanced PEP carboxylase activity. The present studies suggest that aliphatic alcohols enhance functional capabilities of leaf for a larger duration and hence maintain the supply of photoassimilates to the developing kernels of peanut leading to increased yield.     

Toxicity of cyst extract of Sarcocystis fusiformis from buffalo in rabbits and mice

The toxic effect of cysts of Sarcocystis fusiformis (of buffalo origin) in rabbits and mice have been studied. It is shown that inoculation of a 2 mg ml-1 concentration of protein of the macrosarcocyst extract (ME) into rabbits and mice was lethal. The toxic substance was thermolabile at greater than or equal to 60 degrees C for 30 min. Protease and trypsin caused inactivation, while papain did not affect the toxicity. ME was found to be non-dialysable, but precipitable. There was also no effect of a pH of 6-9, while pH 4-5 altered the toxicity and pH 10 only partially affected the toxic effect.     

Factors involved in immunity against Actinobacillus pleuropneumoniae in mice.

Active and passive immunization studies in mice were undertaken to examine the protective efficiency of vaccines prepared from different components of Actinobacillus pleuropneumoniae, or combinations thereof. Subcutaneous immunization using either washed formalinized whole cells, capsular polysaccharide, lipopolysaccharide or purified hemolysin I (105 kDa protein) partially protected mice against intranasal challenge with a lethal dose of homologous or heterologous A. pleuropneumoniae serotypes. However, full protection was obtained if the formalinized whole cells were supplemented with purified hemolysin. Similar protection was obtained when mice were immunized simultaneously with a sublethal dose of live cells by the intranasal route and with formalinized whole cells subcutaneously. Passive immunization using rabbit hyperimmune serum against formalinized whole cells provided almost total protection whereas hyperimmune serum against capsular polysaccharide, lipopolysaccharide or hemolysin alone provided only a partial protection. Cell mediated immunity as detected by the foot pad test may not be implicated significantly in the protein against acute A. pleuropneumoniae infection. However, humoral immune response seems to play an important role in protection. All the antigenic components examined may contribute to the protection to some extent. However, heat-labile components such as hemolysin and outer membrane proteins may play a crucial role in protection against acute challenge infection.