This study was undertaken to examine the cell cycle characteristics of bovine fetal and adult somatic cells (fetal fibroblasts, adult skin and muscle cells, and cumulus cells) after culture under a variety of conditions ; 1 ) growth to 60- 70% confluency (cycling) , 2) serum starvation, 3) culture to confluency. Cell -cycle phases were determined by flow cytometry with propidium iodide staining enabling the calculation of percentages of cells in GO /G1, S and G2 /M. The majority was in GO /GI regardless of cell type and treatment. Serumstarved or confluent cultures contained higher percentages of cells in GO /G1 (89.5-95.4% ; P <0.05) . Percentages of cells in GO /G1 increased as cell size decreased regardless of the cell type and treatment. In the serum-starved and confluent cultures, about 98% of small cells were in GO /G1. Serum-starved cultures contained higher percentages of small cells (38.5-66.9%) than cycling and confluent cultures regardless of cell type (P < 0.05) . After trypsinization of fetal fibroblasts and adult skin cells that were serum-starved and cultured to confluency, the percentages of cells in GO /G1 increased (P < 0.05) on incubation for 1.5 (95.7-99.5%) or 3 hr (95.9-98.6%). These results verify that serum starvation and culture to confluency are efficient means of synchronizing bovine somatic cells in GO /G1, and indicate that a more efficient synchronization of the cells in GO /G1 can be established by incubation for a limited time period after trypsinization of serum-starved or confluent cells.

Oligodendrocytes and myelin in the corpus callosum of black tremor and normal hamsters aged over 1.5 years were ultrastructurally examined to determine the myelination index (ratio of myelin thickness/diameter of axon), percentage of naked axons, and proportions of oligodendroglial subtypes (light, medium and dark). The mutant hamsters were remarkably hypomyelinated, with a low myelination index and a high proportion of naked axons, and high proportions of the dark subtypes. Serum concentrations of thyroid hormones (T sub(3) and T sub(4)) in 6-week-old mutant hamsters were 2-fold (T sub(3)) to 3-fold (T sub(4)) higher than those of age-matched normal animals. However, in the aged animals (over 1.5 years old) only T sub(4) levels of the mutant hamsters were higher in the mutant than normal hamsters. The black tremor hamsters were hypomyelinated throughout their life and high serum level of thyroid hormones might have played a role in the hypomyelination.

An inactivated oil-based Newcastle disease vaccine was prepared using Mukteswar vaccine strain. The virus was propagated in 10-day old embryonating eggs and inactivated by 0.12% formalin for 48 hours at 37 degree C. The vaccine was formulated with 1 part antigen (aqueous phase) and 4 parts oil base. The oil base contained Tween-80 1%, Arlacel-A 10% and Mineral oil 89%. The stability of the vaccine was found satisfactory after 6 months and its viscosity and injectability was fairly ideal. The antigenicity of the vaccine was determined in 16 week-old pullets. The seromonitoring of the vaccinated and the control pullets was carried out for three months post- vaccination by Haemagglutination inhibition (HI) test. Blood samples were taken at fortnightly intervals. The Geometric mean HI titre of the vaccinated pullets on the day of vaccination 15, 30, 45, 60, 75, 90, 105 and 120 days post- vaccination was 18.4, 4.9, 87.5, 192.3, 257.6, 111.4, 91.7, 63.9 and 30.0. However, in non-vaccinated control pullets it was found to be 18.4, 3.7, 3.7, 4.3, 3.8, 4.0, 3.5, 2.8 and 2.3 respectively. The inactivated oil-based vaccine induced a marked antibody response which continued upto three months.

Nutrient broth with iron was used for obtaining high yields of epsilon toxin by clostridium perfringens type D. In this study iron balls, iron nails and ferrous sulphate were used as iron source. Results showed that the presence of iron nails and iron balls in nutrient broth slightly increased the bacterial growth but did not show increase in toxin production.

In this study twenty four isolates of Pasteurella multocida were collected from field out breaks of Haemorrhagic septicaemia (H.S) in cattle and buffalo from various regions of the country from 1991-2001. The isolates were subjected to detailed cultural, biochemical and pathogenicity test in albino mice. The stereotyping was done by indirect haemagglutination test for determination of their capsular antigen. Serologically all the isolates were classified on the basis of their capsular antigen as Carter Type B. All the twenty four isolates produced oxidase, catalase and indole and reduced nitrate. They did not produce urease. All the isolates fermented fructose, glucose, sucrose and sorbitol and mannitol with the production of acid whereas dulcitol, lactose, silicon were found negative. Variable results were found among isolates on the fermentation of arabinose and maltose. It was concluded that all the isolates were serologically and immunologically homologous to H.S. vaccine strain produced in the institute.