Isoenzymes of glutamate-oxalacetate transaminase in the larvae of silkwormsBombyx mori infected with nuclear polyhedrosis virus

Summary Nuclear polyhedrosis virus infection induced changes in the activity and isoenzyme pattern of glutamate-oxalacetate transaminase in the larvae of silkworm,Bombyx mori.The author wish to thank the director of CSRTI, Mysore for providing the virus preparation and the silkworm larvae.     

A comparative study of membrane related phenomena in normal and crown gall tissues of red beet (Beta vulgaris L.)

Summary Divalent metal ions have been found to protect membranes of red beet crown gall tissue more than their adjacent normal regions from thermal or gamma radiation stress, suggesting the possibility of an alteration on the surface charge accompanying tumor formation in plants. Further, tumor tissue has been observed to possess enhanced membrane ATPase activity, a higher tissue sulfhydryl content and increased protein levels, thus suggesting a model of source (normal tissue) and sink (tumor tissue) relationship.Acknowledgments. Thanks are due to Dr Sudhir Sopory, School of Life Sciences, Jawaharlal Nehru University, New Delhi for a critical discussion on this paper. KVAR thanks the Council of Scientific and Industrial Research, New Delhi, for financial assistance in the form of a Senior Research Fellowship.     

Newly identified loci that influence lipid concentrations and risk of coronary artery disease

To identify genetic variants influencing plasma lipid concentrations, we first used genotype imputation and meta-analysis to combine three genome-wide scans totaling 8,816 individuals and comprising 6,068 individuals specific to our study (1,874 individuals from the FUSION study of type 2 diabetes and 4,184 individuals from the SardiNIA study of aging-associated variables) and 2,758 individuals from the Diabetes Genetics Initiative, reported in a companion study in this issue. We subsequently examined promising signals in 11,569 additional individuals. Overall, we identify strongly associated variants in eleven loci previously implicated in lipid metabolism (ABCA1, the APOA5-APOA4-APOC3-APOA1 and APOE-APOC clusters, APOB, CETP, GCKR, LDLR, LPL, LIPC, LIPG and PCSK9) and also in several newly identified loci (near MVK-MMAB and GALNT2, with variants primarily associated with high-density lipoprotein (HDL) cholesterol; near SORT1, with variants primarily associated with low-density lipoprotein (LDL) cholesterol; near TRIB1, MLXIPL and ANGPTL3, with variants primarily associated with triglycerides; and a locus encompassing several genes near NCAN, with variants strongly associated with both triglycerides and LDL cholesterol). Notably, the 11 independent variants associated with increased LDL cholesterol concentrations in our study also showed increased frequency in a sample of coronary artery disease cases versus controls.     

A hybrid recognition sequence in a recombinant restriction enzyme and the evolution of DNA sequence specificity

Early attempts to generate new restriction specificities by recombination between allelic restriction-modification systems have been unsuccessful. Bullas et al. succeeded in isolating a new specificity, SQ, in Salmonella that they interpreted as being the result of a recombination event between the parental strains, Salmonella typhimurium and S. postdam, which encode the SB and SP restriction systems, respectively. This interpretation has recently been confirmed by DNA heteroduplex studies with the SB, SP and SQ structural genes. We have determined the DNA sequences recognized by the SB and SP enzymes and found that, like all type I restriction sequences, they are split into two specific domains by a spacer of nonspecific sequence that, for both SB and SP, is 6 base pairs (bp) long. We have now determined the sequence recognized by the recombinant SQ enzyme and find that it is a hybrid between the SB and SP sequences, containing one specific domain from each parental strain. This result implies that each of the two specific domains is recognized by a physically distinct part of the enzyme.