Separation of isoacceptor cysteine transfer ribonucleic acids of bakers' yeasts

Summary Isoacceptor species of certain amino acidspecific transfer ribonucleic acids (tRNAs) were fractionated by gel permeation chromatography using Sephadex G-100. The separation is attributed to the 20% ethanol-1% NaCl solvent and to the characteristics of Sephadex. Isoacceptor tRNAs specific for cysteine, arginine, phenylalanine, and histidine were recovered from commercial tRNA of yeast by this method. Highly purified cysteine-specific tRNA, obtained by a method which would not be expected to separate isoacceptor molecules when fractionated by this procedure, was shown to contain two cysteine isoacceptor tRNAs.This investigation was supported in part by Public Health Service Research Grant AM-09131 from the National Institute of Arthritis and Metabolic Diseases.     

Copper and cobalt in African species ofAeolanthus Mart. (Plectranthinae,Labiatae)

Summary Hyperaccumulators (here defined as species containing at least 500 μg/g dryweight of either copper or cobalt in leaves), are of interest for the fields of mineral exploration and phytochemistry. Reported hyperaccumulation of copper inAeolanthus biformifolius and the presence of two other species on copper/cobalt mineralization in Shaba (Za?re) led to a survey of these elements in 49 species of the African genusAeolanthus Mart.A. biformifolius appears to be also a hyperaccumulator of Co (2520 μg/g in leaves, 4300 μg/g in corms). Cobalt levels for most species ofAeolanthus were considerably above typical values for phanerogams and indicate the favorable potential of the genus for further study.     

The metabolic fate of triamcinolone acetonide in laboratory animals

The metabolic fate of 9-fluoro-11β,16α,17,21-tetrahydroxy-l, 4-pregnadiene-3,20-dione cyclic 16,17-acetal with 2-¹⁴C-acetone, triaacinolone acetonide (TA) was studied in rabbits, dogs, monkeys and rats and found to be qualitatively similar in all species. In the dog, rat and monkey the major excretory route was the feces irrespective of the mode of administration. In the rabbit the excreted radioactivity was equally distributed between urine and feces. The metabolites were isolated by preparative thin layer chroma tography, located by autoradiography, eluted and analyzed by MS, IR, UV and NMR. The major metabolites of triamcinolone acetonide (TA) were identified as the C-21 carboxylic acids of TA and of the 6β hydroxy-TA,(6β-OH-TA) and the previously identified (1,2) 6β-OH-TA. In addition MS and UV data indicate the presence of 9-fluoro-11β,16α, 17-trihydroxy-3,20-dioxo-1,4,6-pregnatrien-21-oic acid cyclic 16,17 acetal with 2-¹⁴C-acetone.     

Meningococcal Disease in California: Epidemiology and Management

Between 1969 and 1975 in California, 1,953 cases of meningococcal disease were reported. For cases reported in 1973, 1974 and 1975, detailed information about chemoprophylaxis of cases and contacts was obtained in addition to demographic and laboratory data. A review of data for the seven years showed a reduction in the case rate from 2.6 to 0.6 per 100,000 population, but this drop was due primarily to a very substantial decline in the military rate from 35.7 to 1.8 per 100,000 population. No reduction was apparent in the case fatality rate. Five groups of associated meningococcal disease cases were identified for a total of nine secondary or coprimary cases among 862 household contacts. Associated cases occurred in 10.4 per 1,000 household contacts—a rate several hundred times greater than that for the general population.The study findings indicate that many physicians are unaware of the following: (1) nonhousehold contacts are at little or no risk of contracting meningococcal disease; (2) prophylaxis should be offered only to household or intimate contacts immediately upon identification of an index case without waiting for test results for meningococcal carriage; (3) valid medical and epidemiologic indications exist for administering prophylaxis to household contacts who are culture negative as well as those who are culture positive; (4) the current drug of choice for prophylaxis is rifampin, but since no drug is completely effective, close medical observation remains the most important factor in the management of household or intimate contacts to meningococcal disease.     

Effects of substrate biodegradability on the mass and activity of the associated estuarine microbiota

Multiple biochemical assays of microbial mass and activities were applied to the estuarine detrital microbiota colonizing morphologically similar polyvinyl chloride needles and needles from slash pine (Pinus elliottii). Biodegradable pine needles consistently showed 2- to 10-fold higher values of extractable adenosine 5'-triphosphate, rates of oxygen utilization, activities of alkaline phosphatase and phosphodiesterase, and the mucopeptide cell wall component muramic acid than did the polyvinyl chloride needles, during a 14-week incubation in a semitropical estuary. The higher activities by the microbiota of the biodegradable substrate correlated with estimates of the microbial density from scanning electron microscopy. The microbial community associated with the nondegradable substrate showed minimal activity of beta-d-galactosidase, beta-d-glucosidase, and alpha-d-mannosidase in contrast to the biota of the degradable substrate, which showed 10- to 100-fold higher activities of these glycoesterases. These enzymes logically could be involved in catabolism of the carbohydrate polymers of the detritus. Assuming equivalent rates of predation, a surface that is also a utilizable substrate supports a three- to fivefold more active microbial population.     

Quantitative Microdialysis: Analysis of Transients and Application to Pharmacokinetics in Brain

The behavior of a microdialysis probe in vivo is mathematically described. A diffusion-reaction model is developed that not only accounts for transport of substances through tissues and probe membranes but also accounts for transport across the microvasculature and metabolism. Time-dependent equations are presented both for the effluent microdialysate concentration and for concentration profiles about the probe. The analysis applies either to measuring the tissue pharmacokinetics of drugs administered systemically, or for sampling of endogenously produced substances from tissue. In addition, an expression is developed for the transient concentration about the probe when it is used as an infusion device. All mathematical expressions are found to be a sum of an algebraic and an integral term. Theoretical prediction of time-dependent probe behavior in brain has been compared with experimental data for acetaminophen administered at 15 mg/kg to rats by intravenous bolus. Plasma and whole striatal tissue samples were used to describe plasma kinetics and to estimate a capillary permeability-area product of 0.07 min-1. Theoretical prediction of transient effluent dialysate concentrations exhibited close agreement with experimental data over 60 min. Terminal decline of the dialysate effluent concentration was slightly overestimated but theoretical concentrations still lay within the 95% confidence interval of the experimental data at 112 min. Microvasculature transport and metabolism play major roles in determining microdialysate transient responses. Extraction fraction (recovery) has been shown to be a declining function in time for five probe operating conditions. High rates of metabolism and/or capillary transport affect the time required to approach steady-state extraction, shortening the time as the rates increase. Conversely, for substances characterized by low permeabilities and negligible metabolism, experimental situations exist that are predicted to have very slow approaches to microdialysis steady state.     

Histochemical analysis of rat testicular glycoconjugates. 1. Subsets of N-linked saccharides in seminiferous tubules

Summary The distribution of N-linked glycans in rat testis has been probed using a panel of lectins derived fromGalanthus nivalis (snowdrop, GNA),Canavalia ensiformis (jack bean, Con A),Lens culinaris (lentil, LCA),Pisum sativum (garden pea, PSA) andPhaseolus vulgaris, erythro- and leucoagglutinins (kidney bean, ePHA and IPHA). Several classes of N-linked glycan were identified in the spermatogenic series, and during differentiation into spermatozoa they altered in both their pattern of distribution and relative abundance. A population of tetra-antennary, non-bisected, complex glycans, detected by IPHA, was lost during the transition from spermatogonia to spermatocytes, while high-mannose structures were acquired; these were most abundant in spermatocytes, as were bi- and tri-antennary complex, non-bisected glycans, the latter becoming increasingly abundant on acrosomes and spermatozoa. Their bisected counterparts were more generally expressed throughout spermatogenic cells, although marked localization onto acrosomes and nuclear caps was again seen. Transition from spermatocytes to spermatids involved mainly changes of the acrosomal granule and nuclear cap, which were carried through to the final stages of differentiation. Sertoli cell surfaces and cytoplasmic granules showed a high level of N-glycan expression.     

Histochemical analysis of rat testicular glycoconjugates. 2. Beta-galactosyl residues in O- and N-linked glycans in seminiferous tubules.

Summary Rat testes have been examined with a panel of lectins that bind specifically to oligosaccharide sequences having terminal or subterminal -galactosyl residues in O-linked glycans, or in the outer chains of complex N-linked glycans:Arachis hypogaea (peanut, AHA),Erythrina cristagalli (coral tree, ECA),Ricinus communis (castor bean, RCA120) andAbrus precatorius (jequirity bean, APA) agglutinins. Pretreatment of sections with neuraminidase, -galactosidase and removal of alkali-labile O-linked sequences by -elimination allowed the structure of these glycans to be further explored. In spermatogonia and spermatocytes there was little evidence of glycans terminating in -galactosyl residues, although these were present at non-reducing terminals as sialylgalactosides. The acrosome contained two subsets of O-linked glycans terminating in sialylgalactosides, while the nuclear cap showed at least two subsets of N-linked sialylgalactosyl as well as O-linked glycans. Spermatozoa exhibited minor changes in the pattern of glycosylation, although the overall pattern of -galactosyl expression was similar. Binding to Sertoli cells showed the presence of some unsubstituted -galactosyl terminals on O-linked glycans but few such N-linked residues, while terminal -galactosides were scanty in tubular basement membranes.     

A simple method of generating axenic derivatives of Dictyostelium strains

We describe a generally applicable method of adapting Dictyostelium from growth on a bacterial food source to axenic growth. Cells are initially selected by growth on a plastic substratum but subsequently acquire the ability to grow in suspension culture. These strains can be transformed efficiently by DNA-mediated gene transfer.