Taxonomic status of the species of the green algal genusNeochloris

Komárek has recently reviewed the various species assigned to the green algal genusNeochloris Starr (Chlorococcales, Chlorococcaceae) and removed those with uninucleate vegetative cells to a new genus,Ettlia. Watanabe & Floyd, unaware ofKomárek's work, also reviewed the species ofNeochloris and distributed them among three genera—Neochloris, Chlorococcopsis gen. nov., andParietochloris gen. nov.—on the basis of details of the covering of the zoospore and the arrangement of the basal bodies of the flagellar apparatus. This paper reconciles these two treatments and makes additional recommendations at the ranks of genus, family, order, and class.     

Application of flow karyotyping in prenatal detection of chromosome aberrations

This paper describes the application of bivariate flow karyotyping to (1) classification of chromosomes isolated from cultures of cells taken by amniocentesis and (2) detection of numerical and structural aberrations. Chromosomes were isolated from primary cultures 2-5 wk after amniocentesis, stained with Hoechst 33258 and chromomycin A3, and analyzed using dual beam flow cytometry. Information about chromosome DNA content and DNA base composition was derived from the locations of the peaks in the flow karyotypes, each peak being produced by one or more chromosome types with similar DNA content and DNA base composition. Information about the relative frequency of each chromosome type was determined on the basis of the relative volume of the peak for that chromosome type. Cytogenetic information determined on the basis of flow karyotypes was compared with that obtained by visual analysis following G-banding. Variability among the peak means and volumes in flow karyotypes was determined from analyses of 50 normal amniocyte cultures. Numerical aberrations involving chromosomes 21, 18, and Y were detected correctly in all of 28 analyses, including eight in a blind study. Structural aberrations involving chromosomes 1, 2, 3, 6, 9-12, 13, 14, 15, 21, and 22 were detected in all of seven cultures in a blind study. Flow karyotypes proved to be insensitive to small, normally occurring chromosome polymorphisms detected by banding analysis. In addition, a few samples were erroneously scored as having numerical aberrations.     

Movements of some indigenous riverine fish in Sri Lanka

The migratory movements of reproductive potamodromus fish established in man-made tropical lakes in the dry zone of Sri Lanka were determined. It was shown that the nine indigenous riverine species do not spawn in these lakes but move into the upstream channels when sexually mature. The pattern of upstream movement was found to be species-specific although most species showed a diurnal periodicity. It is suggested that the development of totally lacustrine forms of riverine species is very unlikely to occur in the man-made lakes of Sri Lanka because of their relatively short duration time.     

Comparison of crude and affinity purified cytosolic epoxide hydrolases from hepatic tissue of control and clofibrate-fed mice

An affinity purification procedure was developed for the cytosolic epoxide hydrolase based upon the selective binding of the enzyme to immobilized methoxycitronellyl thiol. Several elution systems were examined, but the most successful system employed selective elution with a chalcone oxide. This affinity system allowed the purification of the cytosolic epoxide hydrolase activity from livers of both control and clofibrate-fed mice. A variety of biochemical techniques including pH dependence, substrate preference, kinetics, inhibition, amino acid analysis, peptide mapping, Western blotting, analytical isoelectric focusing, and gel permeation chromatography failed to distinguish between the enzymes purified from control and clofibrate-fed animals. The quantitative removal of the cytosolic epoxide hydrolase acting on trans-stilbene oxide from 100,000g supernatants, allowed analysis of remaining activities acting differentially on cis-stilbene oxide and benzo[a]pyrene 4,5-oxide. Such analysis indicated the existence of a novel epoxide hydrolase activity in the cytosol of mouse liver preparations.     

Pigment patterns in mutants affecting the biosynthesis of pteridines and xanthommatin in Drosophila melanogaster

Eye-color mutants of Drosophila melanogaster have been analyzed for their pigment content and related metabolites. Xanthommatin and dihydroxanthommatin (pigments causing brown eye color) were measured after selective extraction in acidified butanol. Pteridines (pigments causing red eye color) were quantitated after separation of 28 spots by thin-layer chromatography, most of which are pteridines and a few of which are fluorescent metabolites from the xanthommatin pathway. Pigment patterns have been studied in 45 loci. The pteridine pathway ramifies into two double branches giving rise to isoxanthopterin, drosopterins, and biopterin as final products. The regulatory relationship among the branches and the metabolic blockage of the mutants are discussed. The Hn locus is proposed to regulate pteridine synthesis in a step between pyruvoyltetrahydropterin and dihydropterin. The results also indicate that the synthesis and accumulation of xanthommatin in the eyes might be related to the synthesis of pteridines.Support for this work was provided to J.F. in part by a grant from the Ministerio de Universidades e Investigación (Spain) and to F.J.S. by a grant from the Ministerio de Educación y Ciencia (Spain).     

Gelatin as a vehicle for food and vitamin administration to marmosets

For a period of three years, gelatin was used as a vehicle for administration of food, vitamin complex and drugs to laboratory maintained Callithrix penicillata and Callithrix jacchus marmosets and a breeding colony of C. penicillata. In both circumstances, results were satisfactory. The animals survived for long periods of time, with adult, young and juvenile primates in the breeding colony showing good physical condition.     

Primary productivity and related parameters in three different types of inland waters in Sri Lanka

Gross and net primary production together with chlorophyll-a biomass were investigated with respect to depth and diurnal changes in three categories of inland waters (reservoirs, temporary ponds, brackish water lagoons) in Sri Lanka. Ten field sites, in both the dry and wet zones of the island, were investigated. Bimodal productivity profiles were recorded in two of the three reservoirs studied. The diel pattern of net photosynthetic rate varied between sites although peak photosynthetic efficiency occurred at solar noon. Surface photoinhibition was characteristic of the reservoirs and brackish water lagoons but not of the temporary ponds. Mean gross primary production was 3.02 g C m^–2 d^–1 but was higher in the temporary ponds than in the reservoirs. The gross primary production in the brackish water Koggala Lagoon at 0.08 g C m^–2 d^–1 is a record low for tropical lagoons and was 2.5 times less than the two other lagoons investigated. Variability in net primary production between sites was similar to the variation in gross production with a relatively low mean value for tropical inland waters of 0.495 C m^–2 d^–1. Mean maximum photosynthetic rate was 0.30 mg C m^–3 h^–1 but was lower in the reservoirs than in the temporary ponds and lagoons.     

Evidence for the presence of muscarinic acetylcholine receptors in bovine brain coated vesicles

Evidence obtained from quinuclidinylbenzilate binding determinations suggested that muscarinic acetylcholine receptor molecules are present in purified bovine brain coated vesicles. Immunoprecipitates formed from coated vesicles with polyclonal antibodies to clathrin bound on the surface of fixed Staphylococcus aureus cells also showed quinuclidinylbenzilate binding activity. The high purity of coated vesicles was established by assays for biochemical markers and by electron microscopy. Muscarinic receptor sites for quinuclidinylbenzilate binding to coated vesicles displayed a Kd of 25 pM and a Bmax of about 191 fmol/mg of protein. Binding competition experiments using atropine, N-methylscopolamine, oxotremorine, and carbamylcholine confirmed the typical muscarinic nature of the binding site. Ranking order of potency for the receptors was: atropine greater than N-methylscopolamine greater than oxotremorine greater than carbachol Analysis of data using a two-site model revealed 13% high-affinity sites for oxotremorine, 66% high-affinity sites for carbachol, and 62% for the antagonist N-methylscopolamine. Heterogeneity of binding affinities for muscarinic drugs detected in the coated vesicles may be related to the presence of coated vesicle subpopulations in brain tissue, (Kohtz, D. S., Kohtz, J. D., Schook, W. J., and Puszkin, S. (1985) J. Cell Biol. 101, 48a; Pfeffer, S. R., and Kelly, R. B. (1985) Cell 40, 949-957).     

Active and passive respiratory mechanics in anesthetized dogs

In six spontaneously breathing anesthetized dogs (pentobarbital sodium, 30 mg/kg) airflow, volume, and tracheal and esophageal pressures were measured. The active and passive mechanical properties of the total respiratory system, lung, and chest wall were calculated. The average passive values of respiratory system, lung, and chest wall elastances amounted to, respectively, 50.1, 32.3, and 17.7 cmH2O X l-1. Resistive pressure-vs.-flow relationships for the relaxed respiratory system, lung, and chest wall were also determined; a linear relationship was found for the former (the total passive intrinsic resistance averaged 4.1 cmH2O X l-1 X s), whereas power functions best described the others: the pulmonary pressure-flow relationship exhibited an upward concavity, which for the chest wall presented an upward convexity. The average active elastance and resistance of the respiratory system were, respectively, 64.0 cmH2O X l-1 and 5.4 cmH2O X l-1 X s. The greater active impedance reflects pressure losses due to force-length and force-velocity properties of the inspiratory muscles and those due to distortion of the respiratory system from its relaxed configuration.     

A comparative immunological investigation of the alkane hydroxylating cytochrome P-450 from the yeast Candida maltosa

The immunological relations of the cytochrome P-450 from the n-alkane utilizing yeast Candida maltosa to cytochrome P-450 forms of other organisms - yeasts, bacteria and mammalia - were investigated using a solid-phase double-antibody radioimmunoassay. Only the microsomal fraction of other n-alkane utilizing yeasts shows a distinct cross-reaction with an antiserum against cytochrome P-450 from Candida maltosa. Neither the tested bacterial nor the mammalian cytochromes P-450 cross-react with the antiserum.