Western blot analysis of cerebrospinal fluid for detection ofAspergillus antigens

Western-blot immunoassay of cerebrospinal fluid (CSF) specimens of patients with central nervous system (CNS) aspergillosis (3), CNS candidosis (1) and bacterial meningitis (2) was carried out using pooled serum from histopathologically proven deep-seated aspergillosis cases to detect unique antigenic fractions for aspergillosis in CSF. No reactivity was observed in patients with non-fungal meningitis. Four cross-reactive bands (40, 90, 200 and >200 KD) were detectable in CSF from patients with both aspergillosis and candidosis of the CNS. Four additional bands (90–200 KD) were consistently present only in patients with aspergillosis. One prominent band (110 KD) was found only in the patient with aspergillosis who had a fatal outcome and raised the possibility of being a poor prognostic marker.     

Observations on the synaptonemal complex in Armenian hamster spermatocytes by light microscopy

Using the silver staining technique, in somatic and meiotic chromosomes of the Armenian hamster (Cricetulus migratorius), it is possible to stain synaptonemal complexes (SCs) and the nucleolus organizer regions (NORs) in early spermatocytes. There are five pairs of autosomes (Nos. 2, 4, 6, 7, and 8) which have terminally located NORs. Synaptonemal complexes and accessory structures present in the sex chromosomes within the sex vesicle can be easily observed using light microscopy.     

Thiol protease-like active site found in the enzyme dienelactone hydrolase: localization using biochemical, genetic, and structural tools

The active site of dienelactone hydrolase (DLH), a microbial enzyme of the beta-ketoadipate pathway, has been conclusively located using a combination of crystallographic, biochemical, and genetic techniques. DLH hydrolyzes a dienelactone to maleylacetate and has esterase activity on p-nitrophenyl acetate and trans-cinnamoyl imidazole. The identification of Cys-123 as containing the essential thiol confirms the localization of the active site as suggested by the crystal structure of DLH, and disproves an earlier hypothesis regarding its location. Two mutant proteins have been engineered in which Cys-123 has been converted to a serine (C123S DLH) and an alanine (C123A DLH), respectively. C123S DLH (Km = 9900 +/- 2300 microM; Vmax = 4.4 +/- 0.8 mumol/min-mg) displays burst kinetics with p-nitrophenyl acetate and is 10% as active as DLH (Km = 170 +/- 7 microM; Vmax = 21.1 +/- 0.4 mumol/min-mg). C123A DLH is inactive. The structures of DLH, C123S DLH, and C123A DLH have been refined at 1.8, 2.2, and 2.0 A, respectively. Comparison of the structures of these proteins demonstrates that the only differences between them are centered at residue 123. The structures of the active sites of DLH, papain, and subtilisin are similar and are suggestive of the three enzymes having evolved convergently to similar active sites with similar enzymic mechanisms.     

Evaluation of coliforms as indicators of water quality in India

P.W. RAMTEKE, J.W. BHATTACHARJEE, S.P. PATHAK AND N. KALRA. 1992. The total and thermotolerant coliform counts in rural drinking water derived from ground water, piped supplies and surface water are reported for a number of areas in India. To evaluate these counts as indicators of recent faecal contamination the total coliforms and thermotolerant coliforms isolated have been identified. Thermotolerant Escherichia coli formed 11.7% of the total coliforms and 75.1% of the thermotolerant coliforms. Citrobacter sp. (20.4%) and Klebsiella sp. (50.9%) were the other common total coliforms isolated and, among the thermotolerant coliforms, Klebsiella sp. (16.4%) was the only other organism frequently encountered. The total coliform counts were significantly correlated with water temperature. The applicability in tropical areas of standards developed for temperate climates is discussed.