Round robin investigation of methods for recovering human enteric viruses from sludge

To select a tentative standard method for detection of viruses in sludge the American Society for Testing and Materials D19:24:04:04 Subcommittee Task Group initiated round robin comparative testing of two procedures that, after initial screening of several methodologies, were found to meet the basic criteria considered essential by the task group. Eight task group member laboratories agreed to perform round robin testing of the two candidate methods, namely, The Environmental Protection Agency or low pH-AlCl3 method and the Glass or sonication-extraction method. Five different types of sludge were tested. For each particular type of sludge, a single laboratory was designated to collect the sludge in a single sampling, make samples, and ship it to the participating laboratories. In most cases, participating laboratories completed all the tests within 48 h of sample arrival. To establish the reproducibility of the methods, each laboratory tested each sludge sample in triplicate for the two candidate virus methods. Each processed sludge sample was quantitatively assayed for viruses by the procedures of each individual round robin laboratory. To attain a more uniform standard of comparison, a sample of each processed sample from all laboratories was reassayed with one cell line and passage number by a single laboratory (Environmental Protection Agency Environmental Monitoring and Support Laboratory, Cincinnati, Ohio). When the data were statistically analyzed, the Environmental Protection Agency method was found to yield slightly higher virus recoveries for all sludge types, except the dewatered sludge. The precisions of both methods were not significantly different.(ABSTRACT TRUNCATED AT 250 WORDS)     

The Photoperiodic Entrainment and Induction of Reproductive Rhythms in Male Blackheaded Buntings (Emberiza Melanocephala)

Groups of photosensitive, unstimulated or stimulated, male blackheaded buntings were subjected to photoregimes of 15 hr of green light of three intensities and 9 hr of dark per day. In some groups green light was interrupted with 90 min of bright fluorescent light at different times in the subjective day. While gonads did not develop or regressed in some groups, birds in others behaved as if exposed to long daylengths. The results besides suggesting the involvement of endogenous circadian rhythm during initiation and maintenance of gonadal growth indicate that the reproductive rhythms are entrained and induced by environmental photoperiod.     

The postnatal histology of the epididymis in buffalo (Bubalus bubalis).

The epididymis of buffalo is differentiated into 6 regions. The head represents the first 3 regions, the body the 4th region and the tail the 5th and 6th region. At 3-30 weeks, the epithelium is simple high columnar with few basal cells in region I, simple low columnar with few basal cells in region II, pseudostratified low columnar in regions III, IV, V, and pseudostratified low columar in region VI. As age advances, the epithelium increases in height and shows a tendency toward advanced pseudostratification. The basal cells are greater in number in regions III, IV and V than in the other regions of the epididymis. The epithelial cells contain stereocilia in region I at 3 weeks and regions III, IV and V at 30 weeks, whereas they are absent in regions II and VI. The tubules in region I are the smallest in diameter while the tubules in region VI have the largest diameter.     

Microbial production of d-amino acids

The production of d-aminoacylase by Alcaligenes denitrificans and Alcaligenes faecalis has been studied. The enzyme was inducibly produced and N-acetyl-d-leucine and N-acetyl-d-valine were the most effective inducers. d-methionine, d-valine, d-phenylalamine and d-leucine were produced by the enzymic hydrolysis of the appropriate N-acetyl-d-amino-acids with whole cell biomass. The hydrolysis of N-acetyl-d-methionine by A. denitrificans and N-acetyl-d-valine by A. faecalis was preferential. Maximum yields of d-methionine and d-valine were 94.3 and 84.7% at a specific product formation rate of 20.10 and 19.19 μmol min⁻¹ mg⁻¹ of wet cells at 20 mM substrate concentration and 5 mg ml⁻¹ of cell density.     

Two isozymes of dihydroxyacetone phosphate reductase in dunaliella

Two isoforms of dihydroxyacetone phosphate reductase were present in Dunaliella tertiolecta. The major form was located in the chloroplast and the minor form in the cytosol. The chloroplastic reductase eluted first from a DEAE cellulose column followed immediately by the cytosolic form. Both forms were unstable and cold labile. Addition of 5 millimolar dithiothreitol helped to stabilize the enzymes. The cytosolic isoform of DHAP reductase was detected only if the cells were in an active log phase of growth. Then its activity was 20 to 30% of the total reductase activity. When cell cultures entered late log phase of growth the activity of the cytosolic form of the enzyme disappeared, but the chloroplastic form remained. The cytosolic DHAP reductase from Dunaliella has some properties similar to the cytosolic isoform from spinach leaves. Detergents inhibited both enzymes. However, neither form of the algal dihydroxyacetone phosphate reductase was stimulated by fructose 2,6-bisphosphate. In Dunaliella the properties of the chloroplastic form were those expected for glycerol production for osmoregulation, whereas the cytosolic form, like the reductases in leaves, is more likely involved in glycerol phosphate formation for lipid synthesis.     

Osmoregulation in Dunaliella tertiolecta: effects of salt stress,and the external pH on the internal pH

The intracellular pH of the halotolerant green algae Dunaliella tertiolecta, was determined by the distribution of 5,5-dimethyl-2(¹⁴C)-oxalolidine-2,5-dione (DMO) between the cell and the surrounding medium. 5,5-dimethyl-2(¹⁴C)oxalolidine-2,4-dione was not metabolized by the algal cells. The intracellular pH of Dunaliella tertiolecta was 6.8 in the dark and 7.4 in the light. During a salt stress, after two hours, the intracellular pH was increased by 0.2 pH units in both light and dark. The salt stressed cells maintained a constant pH of about 7.5 over the pH range of 6.5 to 8.5. Because of the relatively low permeability coefficient of the plasma membrane for DMO, this technique does not permit rapid pH determinations during the induction period after a salt stress. The magnitude of the salt induced pH changes measured 2 h after the salt stress implies a minor importance of this alkalization in this time range, but does not exclude a larger importance of pH changes for osmoregulation during the induction period.Abbreviations Chl chlorophyll - DMO 5,5-dimethyl-2(¹⁴C)oxalolidine-2,4-dione - PCV packed cell volume - SDS sodium dodecyl sulfate     

Extracellular polysaccharides of cowpea rhizobia: compositional and functional studies

Polysaccharides excreted by cowpea Rhizobium strains JLn(c) and RA-1 were mixtures of complex acidic exopolysaccharides and low molecular weight neutral glucans. These polymers were fractionated using gel filtration chromatography. Purified fractions of the acidic heteropolymer reacted with peanut agglutinin to give precipitin bands when subjected to Ouchterlony gel diffusion. The acidic exopolysaccharide was found to contain mainly glucose, galactose, glucuronic acid, mannose and fucose. The non-carbohydrate substituents of the acidic heteropolymer were pyruvate, acetate and uronate which were identified by infrared and proton nuclear magnetic resonance spectroscopy as well as by chemical analysis.Abbreviations EPS Extracellular polysaccharide - YEM yeast extract mannitol - PNA peanut agglutination - ¹H-NMR proton nuclear magnetic resonance     

Body water relations in two species of gerbil (Tatera indica indica andMeriones hurrianae) of the Indian desert

Summary The relative body water conservation efficiency of two Indian desert gerbil species,Meriones hurrianae (diurnal/crepuscular) andTatera indica (nocturnal), has been examined under near-natural conditons in different seasons.A mean urine osmolarity of 3180 mosmol/l (maximum 4645 mosmol/l) inM. hurrianae and a mean value of 5128 mosmol/l (maximum 7547 mosmol/l) inT. indica have been recorded during summer.Urine osmolarity and urea levels indicated that whileM. hurrianae remain sufficiently hydrated mainly by virtue of their feeding habit,Tatera indica may depend on the relatively higher concentrating capacity of their kidneys.     

Isolation of Intact Chloroplasts from Dunaliella tertiolecta

Cells of Dunaliella tertiolecta from the log phase of growth were broken by rapid extrusion at low pressure through a Yeda press and the chloroplasts were isolated by centrifugation through a Percoll gradient. Osmolarity of the growth media, the suspending media, and the Percoll gradient was kept identical to minimize change in chloroplast volume and mitochondrial entrapment. The isolated intact chloroplasts were obtained in a 30 to 50% yield based on chlorophyll and were stable to washing with buffered medium. Isolated chloroplast yield and purity was dependent on cell culture condition; a cycle of 16 hours light and 8 hours dark with continuous high CO₂ was optimum. Isolated chloroplasts were about 90% intact by microscopic examination, ferricyanide-dependent O₂ evolution, and the distribution of four stromal enzymes. Enzymes associated with glycolate metabolism were not in the chloroplast fraction. The isolated chloroplasts with 10 millimolar bicarbonate evolved 24 micromoles of O₂ and fixed 21 micromoles of CO₂ per hour per milligram of chlorophyll, which rates were about one-third of those by whole cells. The inhibition of oxygen evolution by 10 millimolar phosphate was reversed by P-glycerate. Whole chloroplasts were also isolated from cells adapted to low CO₂ in air for 24 hours. On low CO₂ the cells excreted more gelatinous material, which had to be removed with additional washing of the cells, before it was possible to obtain good chloroplast preparations.