The elucidation of the mechanism of folate catabolism in the rat

It has been demonstrated that after a sufficient equilibration period the principle catabolite of a tracer dose of [³H]pteroylglutamate is acetamidobenzoylglutamate. This catabolite was formed prior to excretion from p-aminobenzoylglutamate, a small amount of which also appears in the urine and indicates that the principle mechanism of cellular folate catabolism proceeds via cleavage of the C9N10 bond. The inability of others to demonstrate this simple catabolic mechanism resides in that they used too short a study period which shows a complex equilibration pattern in the urine or that they may have wrongly identified the other cleavage product, a pteridine, as an intact folate derivative. In addition the further metabolism of p-aminobenzoylglutamate has not been appreciated until now. Apart from the two catabolites mentioned three others have been recognized and preliminary evidence suggests that they may be pteridines which have become labelled during metabolic cleavage.     

Posterior pattern formation in C. elegans involves position-specific expression of a gene containing a homeobox

During postembryonic development in C. elegans, posterior-specific pattern formation requires the gene mab-5. Within the posterior body region, mab-5 activity controls epidermal, neuronal, and mesodermal cell differentiation, and also the direction of cell migration. Here, we show that mab-5 RNA is localized in the posterior body region, indicating that mab-5 activity is targeted to posterior cells, at least in part, by a mechanism that operates at the level of mab-5 RNA synthesis or stabilization. We also show that mab-5 contains a homeobox similar to that of the Drosophila Antennapedia gene. This suggests that mab-5 influences cell differentiation and cell migration by regulating gene expression, and clearly demonstrates that genes containing homeoboxes influence global aspects of pattern formation in organisms other than Drosophila.     

Increased severity and morbidity of acute hepatitis in drug abusers with simultaneously acquired hepatitis B and hepatitis D virus infections.

Hepatitis D virus (delta agent) markers were present in 111 (36%) of 308 intravenous drug abusers who were positive for hepatitis B surface antigen (HBsAg), 52 of these having hepatitis D virus antigenaemia. IgM antibody to hepatitis B core antigen (anti-HBc IgM) was present in 92 out of 95 subjects tested, indicating that hepatitis D virus and hepatitis B virus infections had been acquired simultaneously. Hepatitis D virus markers were present in three out of four patients with fulminant hepatitis, and in 80 of 223 (36%) with mild or moderate hepatitis compared with four of 29 (14%) of those who were asymptomatic. These proportional differences were significant (p less than 0.001). Hepatitis D virus markers were present in twice as many patients positive for anti-HBc IgM requiring admission to hospital with acute hepatitis compared with outpatients attending a drug treatment centre. Tests on one patient showed complete disappearance of HBsAg, but hepatitis D antigen (HDAg or delta antigen) and hepatitis B e antigen (HBeAg) were still present in serum samples. All five patients with chronic active hepatitis had hepatitis D antibody (anti-HD) compared with seven of 24 (29%) with chronic persistent hepatitis (p = 0.008). Blocking anti-HD persisted for long periods after simultaneous infections with hepatitis B virus and hepatitis D virus but at lower titres than in patients with chronic liver disease.     

Genetic variation of phosphoglucose isomerase in some hystricomorph rodents

Phosphoglucose isomerase electrophoretic variation has been studied in hystricomorph rodents. Intraspecies variation was found in chinchilla (Chinchilla laniger) and cuis (Galea musteloides). Interspecies hybridization of Cavia aperea and Cavia porcellus was found to produce hybrid enzymes. In all cases, breeding data indicated an autosomal mode of inheritance, while electrophoretic patterns were consistent with a dimeric structure for the enzyme. Possible evolutionary relationships of phosphoglucose isomerase with respect to taxonomy are discussed.The laboratory studies were supported by the Royal Society and Agricultural Research Council (N. D. C. and M. R. H.) and the Ford Foundation (B. J. W.).