A tooth at the border of two morphogenetic fields

A tooth at the border between two morphogenetic fields (mandibular canine and honing premolar) may become morphologically similar to and/or functionally incorporated with the teeth of either field. In light of this, observations of the morphology and occlusion of female anthropoid C1s from 58 extant species are presented to assess whether and to what extent they exhibit incisor-like form and function. Female C1s in 74% of the taxa observed exhibit well developed incisor-like traits which may reflect field border phenomena. In another 9%, incisor traits are present but they are not examples of field border phenomena. Interspecies variation in female C1 morphology is related to behavior, function, natural selection and phyletic inertia. A selection model, derived from the data, is used to explain C1 sexual dimorphism and the evolution of male and female human canines. The data's relevance to the field vs clone theory debate is also discussed.     

Molecular cloning and sequencing of infC, the gene encoding translation initiation factor IF3, from four enterobacterial species

Abstract Translation initiation factor IF3 plays a crucial role in initiation of protein synthesis in bacteria. In order to elucidate the IF3 structural elements required for these functions, the evolutionary conservation of IF3 and its gene, infC , was investigated. Homologous infC sequences from Salmonella typhimurium, Klebsiella pneumoniae, Serratia marcescens and Proteus vulgaris were amplified by the polymerase chain reaction and sequenced. Analysis of these sequences, as well as that from Bacillus stearothermophilus , revealed several regions (e.g. residues 62–73 and 173–177) of absolute sequence conservation, suggesting an important role for these regions in IF3 function.     

Algae in mosquito breeding sites and the effectiveness of the mosquito larvicide Bacillus thuringiensis H-14

The presence of cyanobacteria generally decreased the effectiveness of Bacillus thuringiensis H-14 (BTI) as a mosquito larvicide. The effect was more pronounced when the mosquito larvae were exposed to BTI in the presence of several cyanobacterial strains. No synergistic or antagonistic effect between the -endotoxin from BTI and the hepatotoxin from cyanobacteria was seen. Neurotoxic cyanobacterial strains caused very fast paralysis in mosquito larvae; the decreases in the effectiveness of BTI when tested in combination with a neurotoxic strain might be due to the effect of this paralytic action on the feeding rate of the mosquito larvae.     

Association between barium exposed,CYP19A1 and central obesity: A cross-sectional study in rural China

Backgroundobesity is a major risk factor for many metabolic diseases such as diabetes and cardiometabolic diseases. This study aimed to evaluate the association of plasma and urinary barium concentrations, CYP19A1 gene polymorphisms, and their interaction with central obesity in a rural Chinese population.Methodsrestricted cubic spline model was used to explore the dose-response relationship between barium and the risk of developing central obesity and waist circumference; logistic regression model was used to assess the association between barium, CYP19A1 gene polymorphisms and their interaction with central obesity.Resultsthe results of the restricted cubic spline model showed that plasma barium concentration was linearly associated with the risk of developing central obesity and non-linearly associated with waist circumference. Logistic regression analysis showed that participants with Q4 plasma barium concentration exhibited a higher risk of central obesity compared to participants with Q1 barium concentration; participants carrying the rs10046-AA gene exhibited a lower risk of central obesity than those carrying the rs10046-G(GG+GA) gene; participants carrying the rs10046-GA genotype showed 1.754 times higher risk of central obesity than those carrying rs10046-GG+AA genotype. There was a significant interaction between plasma barium and CYP19A1 gene polymorphism on central obesity.Conclusionthe development of central obesity was associated with plasma barium and CYP19A1.     

HPLC separation of the enantiomers of nicotine and nicotine-like compounds

A sensitive and reproducible HPLC method utilizing a commercially available chiral α₁-acid glycoprotein (AGP) phase has been developed to separate and quantify the enantiomers of nicotine. The method is suitable for routine use as indicated by column life. The quantification of (R/S:0.05/99.95)-nicotine or (R/S:99/1)-nicotine was possible. In addition, the separation or at least partial separation of the enantiomers of nornicotine and nornicotine-derived compounds was achieved. © 1993 Wiley-Liss, Inc.     

Acid-Catalyzed nucleophilic substitution and racemization of 3-methoxy-N-desmethyldiazepam enantiomers in methanol

pK_a1 values of 3-methoxy-N-desmethyldiazepam in acetonitrile and methanol containing various acid concentrations were determined by spectrophotometry to be 3.5 and 1.3, respectively. Temperature-dependent racemization of enantiomeric 3-methoxy-N-desmethyldiazepam in methanol containing 0.5 M H₂SO₄ was studied by circular dichroism spectropolorimetry and the racemization reactions were found to follow apparent first-order kinetics. Thermodynamic parameters of the racemization reaction were found to be: E_act = 18.8 kcal/mol, and at 25°C: ΔH^? = 18.3 kcal/mol, ΔS^? = ?14.8 entropy unit, and ΔG^? = 22.7 kcal/mol, respectively. The racemization had an isotope effect (k_H/k_D) of 1.6 at 42°C. Based on the results of this report and those of earlier reports by other investigators, a nucleophilically solvated C3 carbocation intermediate resulting from either a P (plus) or an M (minus) conformation is proposed to be an intermediate and responsible for the stereoselective nucleophilic substitution and the subsequent racemization of 3-methoxy-N-desmethyldiazepam enantiomers. © 1993 Wiley-Liss, Inc.     

Influence of phosphate ion on the fluorescence of 3-fluorotyrosine

Summary 3-Fluorotyrosine fluorescence is quenched effectively by phosphate ions not only by a dynamic but also by a static mechanism owing to H-bond complex formation in ground state. 3-Fluorotyrosine pK_a values both in the ground and first excited state (8.3 and 4, respectively) are appreciably lower than those of tyrosine, thus promoting 3-fluorotyrosinate ion formation in the excited state. Additional emission owing to 3-fluorotyrosinate ion (near 350 nm) may be taken erroneously for tryptophan fluorescence.