Effects of combined nitrogen on anapleurotic carbon assimilation and bleeding sap composition in Phaseolus vulgaris L.

Dwarf french beans, Phaseolus vulgaris L., were grown with or without inoculation with rhizobia (strain 3644), and with or without a combined nitrogen source (nitrate or ammonium ions). The distribution of radioactivity into products of dark ¹⁴CO₂ assimilation was studied in roots or nodules from these plants. A detailed study was also made of the distribution and rates of excretion of nitrogen in xylem bleeding sap in 28 day old plants grown on the various sources of nitrogen. Whereas detached nodules accumulated radioactive glycine, serine and glutamate when incubated with ¹⁴CO₂, bleeding sap from plants root fed ¹⁴CO₂ contained low levels of radioactivity in these compounds but higher levels in allantoin. Chemical analysis showed allantoin to be the major compound transported in the xylem of nodulated plants, whether or not they were fed on combined nitrogen. In contrast uninoculated plants accumulated mainly amino acids in the bleeding sap, the amount and chemical composition of which depended on the combined nitrogen source.Abbreviations PEP phosphoenol pyruvate - OAA oxaloacetate     

Direct enzymeimmunoassay of progesterone in bovine milk

A sensitive enzymeimmunoassay has been developed for measuring progesterone in unextracted bovine milk. An N-hydroxysuccinimide ester of 11 alpha -hydroxyprogesterone 11-hemisuccinate has been synthesised and used to form conjugates with beta-galactosidase in buffer at pH 7.0. The degree of incorporation of progesterone into the enzyme was demonstrated using (14C)-labelled steroid and by radioimmunoassay binding inhibition. Standard curves of comparable range and sensitivity to radioimmunoassay were obtained in the presence of whole milk taken from a cow at oestrus. These advances have allowed the development of a simple micro-titre plate enzymeimmunoassay of progesterone in whole milk and will be of particular value in determination of pregnancy, prediction of the day of oestrus and diagnosis of reproductive disorders.     

Korsakoff's Syndrome Associated with Adrenal Virilism

Korsakoff''s syndrome of obscure etiology was observed in a 34-year-old single woman with an 11-year history of hirsutism and mood swings, and previous hospitalizations for mania three years ago and depression 11 years ago.Recently the virilism had intensified with increased muscularity and coarsening of facial features. The 24-hour urinary 17-ketosteroids ranged between 14.4 mg. and 21.5 mg. and were suppressed by dexamethasone. The 17-hydroxycorticosteroid excretion was normal. These and other findings suggested a diagnosis of adrenal virilism due to adrenocortical hyperplasia. In the absence of other discernible causes it appeared that the adrenal pathology was responsible for the Korsakoff''s syndrome. Both conditions responded well to glucocorticoid therapy although low doses were necessary to avoid mania.It is speculated that the encephalopathy was due to an associated adrenal insufficiency. Although hypoadrenalism is accepted as a complication of only the infant form of adrenal virilism, it is noteworthy that this patient had pathological pigmentation of her skin.     

A DNA primer/probe system for the rapid and sensitive detection of Mycobacterium tuberculosis-complex pathogens

A 1·5 kb Eco RI– Bam HI restriction fragment from Mycobacterium tuberculosis was found to hybridize specifically with genomic DNA from M. tuberculosis -complex organisms. Primers were designed from the terminal sequences of this fragment and used to amplify uniquely M. tuberculosis -group DNA in a polymerase chain reaction. It is suggested that a combination of these primers and probe will prove a useful tool for the early diagnosis of tuberculous infections.     

Leucine-rich repeat kinase 2 mutations and Parkinson’s disease: three questions

Mutations in the gene encoding LRRK2 (leucine-rich repeat kinase 2) were first identified in 2004 and have since been shown to be the single most common cause of inherited Parkinson’s disease. The protein is a large GTP-regulated serine/threonine kinase that additionally contains several protein–protein interaction domains. In the present review, we discuss three important, but unresolved, questions concerning LRRK2. We first ask: what is the normal function of LRRK2? Related to this, we discuss the evidence of LRRK2 activity as a GTPase and as a kinase and the available data on protein–protein interactions. Next we raise the question of how mutations affect LRRK2 function, focusing on some slightly controversial results related to the kinase activity of the protein in a variety of in vitro systems. Finally, we discuss what the possible mechanisms are for LRRK2-mediated neurotoxicity, in the context of known activities of the protein.