Envelope diversity, characteristics of V3 region and predicted co-receptor usage of human immunodeficiency viruses infecting north indians

Subtypes of human immunodeficiency virus type 1 circulating in 21 north Indian patients were characterized based on the partial sequence of the gp120 envelope protein. A majority of viruses (85.7%, 18/21) were subtype C, while 14.3% (3/21) were subtype A. Sequence analysis revealed that the V3 region was highly conserved compared with V4 and V5. The predicted use of co-receptors indicated exclusive usage of R5, except for two subtype A viruses (AIIMS279 and AIIMS281). Our results demonstrate conservation within the V3 loop of subtype C viruses, and suggest the emergence of non-clade C viruses in the north Indian population.     

Polyamines are needed for the differentiation of 3T3-L1 fibroblasts into adipose cells

When non-proliferating 3T3-L1 fibroblasts were stimulated to differentiate into adipose cells, there was a dramatic increase in the intracellular level of the polyamine, spermidine. Addition of α-difluoromethylornithine, an inhibitor of polyamine biosynthesis, depleted the cellular polyamines and prevented triglyceride accumulation and differentiation. The inhibitory effect of α-difluoromethylorinithine was completely abolished by provision of spermidine or putrescine. This suggests that polyamines are needed in the processes of differentiation as well as their established requirement for cell growth.