Spiral Plate Method for Bacterial Determination

A method is described for determining the number of bacteria in a solution by the use of a machine which deposits a known volume of sample on a rotating agar plate in an ever decreasing amount in the form of an Archimedes spiral. After the sample is incubated, different colony densities are apparent on the surface of the plate. A modified counting grid is described which relates area of the plate of volume of sample. By counting an appropriate area of the plate, the number of bacteria in the sample is estimated. This method was compared to the pour plate procedure with the use of pure and mixed cultures in water and milk. The results did not demonstrate a significant difference in variance between duplicates at the α = 0.01 level when concentrations of 600 to 12 × 10⁵ bacteria per ml were used, but the spiral plate method gave counts that were higher than counts obtained by the pour plate method. The time and materials required for this method are substantially less than those required for the conventional aerobic pour plate procedure.     

Clinical evaluation and use of urine screening for drug abuse.

Urine drug screening is indicated to evaluate patients who show mental status or behavioral changes and to monitor the abstinence of drug abusers. The appropriate timing for collecting urine specimens may vary depending on the suspected drug of abuse and on laboratory factors. Laboratories use a variety of techniques to do urine screens, and these must be understood by clinicians ordering the screens to interpret results correctly. In treating drug-abusing patients, clinicians must apply structured reinforcement in conjunction with urine screen results to aid patients in achieving abstinence.     

Human B cells secrete predominantly lambda L chains in the absence of H chain expression

Ig H and L chains are independently assembled in B cells and then secreted together as a functional protein. H chains cannot be secreted without assembly to L chains; however, L chains can be secreted in the absence of H chains by both mice and human cells. To examine the influence of H chain expression on human L chain isotype selection (kappa or lambda), we compared the kappa/lambda ratio of L chains unassociated with H chains (free L chains) to the kappa/lambda ratio of L chains associated with H chains. Culture supernatants of human splenocytes were assayed for kappa and lambda L chains. Free L chains were the predominant form of L chains detected in unstimulated cultures, accounting for 68 to 70% of the total. This was in contrast to the minor proportion that free L chains represented (less than 20%) in cultures stimulated with PWM or LPS (p less than 0.01). Furthermore, the kappa/lambda ratio of light chains detected in unstimulated cultures was 0.5 as compared to 1.3 for PWM stimulated cultures (p = 0.0001). To demonstrate that the decreased kappa/lambda ratio of L chains in the supernatants of cultures of unstimulated B cells was due to free L chains, we measured the kappa/lambda ratio of IgG and IgM-associated L chains. In both the stimulated and unstimulated cultures, the kappa/lambda ratio of L chains associated with H chains was greater than the ratio determined for free L chains. Free L chains were shown to be predominantly lambda as compared to the predominantly kappa phenotype of L chains associated with H chains. Thus absence of H chain expression affects selection of L chain isotypes secreted by human B cells.     

North and South: Exploring isotopic analysis of bone carbonates and collagen to understand post-medieval diets in London and northern England

Objectives

We evaluate the potential of paired isotopic analysis of bone carbonate and collagen to examine the diet of post-medieval human and animal populations from England (17th–19th c.), including, for the first time, manufacturing towns in northern England. The potential for identifying C₄ crop consumption is explored alongside regional and local patterning in diet by sex and socioeconomic status.

Materials and Methods

Humans (n = 216) and animals (n = 168) were analyzed from sites in London and northern England for both carbon and nitrogen isotopes of bone collagen (𝛿¹³C_coll, 𝛿¹⁵N_coll). Isotopic analysis of bone carbonates (𝛿¹³C_carb, 𝛿¹⁸O_carb) was carried out on all humans and 27 animals, using Fourier transform infrared spectroscopy–attenuated total reflectance to assess diagenesis.

Results

Variations in diet were observed between and within different populations by geographical location and socioeconomic status. Three pigs and one cow consumed C₄ resources, indicating the availability of C₄-fed animal protein. Londoners consumed more animal and marine protein and C₄ resources. Middle- and upper-class populations from both London and northern populations also had greater access to these foods compared to those of lower status in the same regions.

Discussion

This substantial multi-isotope dataset deriving from bone carbonate and collagen combined from diverse post-medieval urban communities enabled, for the first time, the biomolecular identification of the dynamics of C₄ consumption (cane sugar/maize) in England, providing insight into the dynamics of food globalization during this period. We also add substantially to the animal dataset for post-medieval England, providing further insight into animal management during a key moment of agricultural change.

     

Phenylacetylglycine, a putative biomarker of phospholipidosis: its origins and relevance to phospholipid accumulation using amiodarone treated rats as a model.

Amiodarone was given to male Sprague-Dawley rats at a dose of 150 mg kg(-1) day(-1) for 7 consecutive days to induce phospholipidosis in the lungs of treated rats. Amiodarone was given alone or concurrently with phenobarbitone. Animals given amiodarone had raised total phospholipid in serum, lung and lymphocytes, and elevated lyso(bis)phosphatidic acid (LBPA) in all tissues. Urinary and plasma phenylacetylglycine (PAG) and hepatic portal:aortal phenylacetate (PA) ratio were increased, whereas hepatic phenylalanine hydroxylase (PAH) activity and plasma phenylalanine:tyrosine ratio were not affected. Phenobarbitone treatment increased hepatic total P450 content and induced 7-pentoxyresorufin O-dealkylatian (PROD) activity, as expected, but had no effect on any other biochemical parameter. Plasma amiodarone concentration was reduced in rats co-administered both drugs and phospholipid accumulation in target tissues was attenuated compared with rats treated with amiodarone alone. However, phenobarbitone co-administration failed to alter the magnitude of response with regards to urinary PAG excretion and plasma concentration of its precursors after amiodarone treatment. Increased intestinal absorption of PAG precursors probably resulted in the raised urinary PAG after amiodarone treatment. Urinary PAG correlated weakly with serum, lymphocyte and lung phospholipids. However, urinary PAG excretion was similar in rats dosed solely with amiodarone or in combination with phenobarbitone, despite the fact that the degree of phospholipid accumulation was far less in rats given the combined treatment. Nevertheless, urinary PAG was raised only in animals exhibiting abnormal phospholipid accumulation in target tissues and may thus be useful as a surrogate biomarker for phospholipidosis.     

Characterization of Bacteriophage S13 suN15 Single-Strand and Replicative-Form Deoxyribonucleic Acid

The deoxyribonucleic acid (DNA) of bacteriophage S13 was shown to be single-stranded by the criteria of reactivity with formaldehyde, dependence of optical density on ionic strength, broad temperature-absorbance profile, and lack of molar equivalence of the purine and pyrimidine bases. The DNA has a molecular weight of 1.8 × 10⁶ daltons, an S°₂₀ of 24.6 in SSC (0.15 m NaCl plus 0.015 m sodium citrate), and a buoyant density of 1.726 g/cc in CsCl. Electron microscopy showed the molecule to be circular. S13 replicative-form DNA was shown to be a double-stranded, circular molecule with a molecular weight of 3.5 × 10⁶ daltons, an S_[ill] of 20.7 in SSC, and a buoyant density in CsCl of 1.710 g/cc. The finding that S13 DNA is slightly more pyrimidine-rich than X174 DNA but is indistinguishable by all other parameters supports the close genetic relationship between the two bacteriophages.     

Marine invasive species: validation of citizen science and implications for national monitoring networks

Approximately 1,000 volunteers assessed the presence of invasive (Carcinus maenas and Hemigrapsus sanguineus) and native crabs within the intertidal zone of seven coastal states of the US, from New Jersey to Maine. Identification of crab species and determination of the gender of the observed crabs was documented at all 52 sites across a 725-km coastal transect. Using quantitative measures of accuracy of data collected by citizen scientists, a significant predictor of a volunteer’s ability was determined and eligibility criteria were set. Students in grade three and seven had the ability to differentiate between species of crabs with over 80% and 95% accuracy, respectively. Determination of gender of the crabs was more challenging and accuracy exceeded 80% for seventh grade students, while 95% accuracy was found for students with at least 2 years of university education. We used the data collected by citizen scientists to create a large-scale standardized database of the distribution and abundance of the native and invasive crabs. Hemigrapsus sanguineus dominated the rocky intertidal zone from Sandy Hook, New Jersey to Boston Harbor, Massachusetts while C. maenas dominated the northern extent of the sampled coastline. A citizen scientist of this monitoring network detected a range expansion of H. sanguineus. We identified obstacles to creating a national monitoring network and proposed recommendations that addressed these issues.     

Synonymous codon usage pattern among the S,M, and L segments in Crimean-congo hemorrhagic fever virus

Crimean-Congo hemorrhagic fever (CCHF) virus is one among the major zoonosis viral diseases that use the Hyalomma ticks as their transmission vector to cause viral infection to the human and mammalian community. The fatality of infectious is high across the world especially in Africa, Asia, Middle East, and Europe. This study regarding codon usage bias of S, M, and L segments of the CCHF virus pertaining to the host Homo sapiens, reveals in-depth information about the evolutionary characteristics of CCHFV. Relative Synonymous Codon Usage (RSCU), Effective number of codons (ENC) were calculated, to determine the codon usage pattern in each segment. Correlation analysis between Codon adaptation index (CAI), GRAVY (Hydrophobicity), AROMO (Aromaticity), and nucleotide composition revealed bias in the codon usage pattern. There was no strong codon bias found among any segments of the CCHF virus, indicating both the factors i.e., natural selection and mutational pressure shapes the codon usage bias.     

Locoweed dose responses to nitrogen: Positive for biomass and primary physiology, but inconsistent for an alkaloid

? Premise of the Study: Plant communities may be influenced by toxic secondary metabolites or enhanced plant growth from plant-symbiont interactions. The C:N hypothesis predicts that carbon or nitrogen constrains plant secondary metabolite production, but it does not consider compounds produced by plant symbionts. Locoweeds are legumes that can have fungal endophyte alkaloid (swainsonine [SWA]) production, which causes livestock poisoning. We studied four locoweed taxa to test whether average SWA concentrations influenced SWA positive dose responses to N fertilizer. ? Methods: We measured locoweed leaf SWA, pigment concentrations and photosynthetic activity, and plant biomass dose responses to N supplementation for 3 mo in two greenhouse experiments. ? Key Results: Leaf photosynthesis, leaf pigment concentrations, and plant biomass had positive, unsaturated dose responses across tested N doses. Although N enhanced primary growth, two moderate-SWA taxa (Astragalus mollissimus var. bigelovii and Oxytropis sericea) had negative SWA dose responses to increasing N, the high-SWA taxon (A. moll. var. mollissimus) had no SWA change, and the very low-SWA taxon (A. moll. var. matthewsii) had a transient positive dose response. ? Conclusions: Supplemented N led to positive dose responses for plant biomass and leaf photosynthesis and pigments, but SWA dose responses differed across locoweed taxa and time. At N levels that enhanced plant growth and reduced antioxidant protective systems, fungal endophyte alkaloid production was not strongly influenced. Production of SWA may be more strongly influenced by factors other than C:N supply (e.g., seasonality, plant age) in the locoweed-endophyte-Rhizobium complex.