Strain differences among chickens in tonic immobility: evidence for an emotionality component

Substantial strain differences in tonic immobility were found between different breeds of chickens. Crossbreeding between strains showing different immobility durations yielded hybrids that exhibited intermediate reactions. For purpose of relating the strain differences in tonic immobility to more conventional measures of emotionality, data were collected on open-field activity, defecation, and adrenal weight. Overall, the results implicated strain-specific differences in emotionality as being the basis for the observed differences in immobility. Latency to defecate in an open field, however, was highly correlated with latency to ambulate. It was argued that defecation, rather than being an absolute measure of fear or emotionality, may in fact be an intermediate response to gradual fear reduction.     

Dilute solution properties of randomly branched poly(methyl methacrylate)

Randomly branched poly(methyl methacrylate) samples were prepared by copolymerization with different amounts of ethylene dimethacrylate. The molecular weight distributions, radius of gyration distributions, and intrinsic viscosity distributions were measured by size exclusion chromatography with refractive index, multiangle light-scattering, and viscosity detectors. The effect of branching on the radius of gyration was compared with the effect on the intrinsic viscosity. It was found that the intrinsic viscosity contraction factor gⁱ scales with the radius of gyration contraction factor g, with the exponent, ϵ, having a value in the range 0.8–1.0. © 1996 John Wiley & Sons, Inc.     

High resolution footprinting of a type I methyltransferase reveals a large structural distortion within the DNA recognition site

The type I DNA methyltransferase M.EcoR124I is a multi-subunit enzyme that binds to the sequence GAAN6RTCG, transferring a methyl group from S-adenosyl methionine to a specific adenine on each DNA strand. We have investigated the protein-DNA interactions in the complex by DNase I and hydroxyl radical footprinting. The DNase I footprint is unusually large: the protein protects the DNA on both strands for at least two complete turns of the helix, indicating that the enzyme completely encloses the DNA in the complex. The higher resolution hydroxyl radical probe shows a smaller, but still extensive, 18 bp footprint encompassing the recognition site. Within this region, however, there is a remarkably hyper-reactive site on each strand. The two sites of enhanced cleavage are co-incident with the two adenines that are the target bases for methylation, showing that the DNA is both accessible and highly distorted at these sites. The hydroxyl radical footprint is unaffected by the presence of the cofactor S-adenosyl methionine, showing that the distorted DNA structure induced by M.EcoR124I is formed during the initial DNA binding reaction and not as a transient intermediate in the reaction pathway.     

Effects of hypertonia on voltage-gated ion currents in freshly isolated hippocampal neurons, and on synaptic currents in neurons in hippocampal slices

A NAD-dependent mannitol dehydrogenase (MtlD) was purified to homogeneity from P. fluorescens DSM50106 and the N-terminal amino acid sequence was determined. An oligonucleotide deduced from this peptide sequence was used as a probe to isolate the mannitol dehydrogenase gene (mtlD) from a genomic library of P. fluorescens. Nucleotide sequence analysis of a 1.8 kb NruI fragment containing the entire mtlD gene revealed an open reading frame of 1482 bp encoding a protein with a calculated molecular weight of 54.49 kDa. The enzyme shared a high similarity with a mannitol dehydrogenase from Rhodobacter sphaeroides and a putative mannitol dehydrogenase of Saccharomyces cerevisae with an overall identity in amino acid sequence of 44% and 42%, respectively, whereas the similarity to mannitol-1-phosphate dehydrogenases of Escherichia coli or Enterococcus faecalis was only about 23% of identical amino acids. By construction of inducible expression plasmids the specific activity of the mannitol dehydrogenase synthesized in E. coli was increased from 0.02 U (mg protein)(-1) to 10 U (mg protein)(-1). After fusion of six histidine codons to the 3' end of mtlD gene and expression in E. coli active mannitol dehydrogenase could be purified in a two-step procedure by affinity chromatography using a Ni2+ matrix column. The purified enzyme exhibited a specific activity of 46 U (mg protein)(-1) and was shown to be a polyol dehydrogenase with a broad substrate spectrum oxidizing efficiently mannitol, sorbitol and arabitol.     

Polymer electrolyte membranes from fluorinated polyisoprene-block-sulfonated polystyrene: Structural evolution with hydration and heating

Small-angle neutron scattering (SANS) and ultra-small-angle X-ray scattering (USAXS) have been used to study the structural changes in fluorinated polyisoprene/sulfonated polystyrene (FISS) diblock copolymers as they evolved from the dry state to the water swollen state. A dilation of the nanometer-scale hydrophilic domains has been observed as hydration increased, with greater dilation occurring in the more highly sulfonated samples or upon hydration at higher temperatures. Furthermore, a decrease in the order in these phase separated structures is observed upon swelling. The glass transition temperatures of the fluorinated blocks have been observed to decrease upon hydration of these materials, and at the highest hydration levels, differential scanning calorimetry (DSC) has shown the presence of tightly bound water. A precipitous drop in the mechanical integrity of the 50% sulfonated materials is also observed upon exceeding the glass transition temperature (T_g), as measured by dynamic mechanical analysis (DMA).     

Synthesis and chain flexibility of poly(cyclohexylethyl methacrylate)

The synthesis and characterization of fractions of poly(cyclohexylethyl methacrylate) (PCHEM) are reported. A combination of low-angle laser light scattering and intrinsic viscosity experiments was employed to estimate the characteristic ratio (C_∞) of this polymer. The value of 10.7 obtained for PCHEM is similar to the value of 11.3 found previously for poly(phenylethyl methacrylate) but is smaller than values measured for poly(cyclohexyl methacrylate) and poly(cyclohexylmethyl methacrylate) (C_∞ = 11.6 and 11.9, respectively). Received: 28 October 1996/Revised: 16 December 1996/Accepted: 19 December 1996     

Mark-Houwink-Sakurada coefficients for conventional poly(methyl methacrylate) in tetrahydrofuran

Summary Intrinsic viscosities [] in tetrahydrofuran (THF) at 30°C are reported for ten narrow molecular weight distribution poly(methyl methacrylate) (PMMA) samples covering nearly two orders of magnitude in molecular weight. By combining the viscosity results with absolute weight-average molecular weights determined via low-angle laser light scattering (LALLS) experiments, we have accurately determined the Mark-Houwink-Sakurada (MHS) parameters for this polymer-solvent pair (K=7.56x10⁵ and a=0.731, when [] is in dL g^-1).     

Spatial genetic structure and recruitment dynamics of burbot (Lota lota) in Eastern Lake Michigan and Michigan tributaries

Burbot (Lota lota) are the only freshwater member of the Cod like (Lotidae) family that have a circumpolar distribution and occupy the widest geographic distribution of all Laurentian Great Lakes fish species. Information regarding burbot spatial genetic structure and recruitment dynamics is critical for the development of effective management strategies. Although burbot are a species of conservation concern throughout their range, little demographic or behavioral information exists. We estimated levels of genetic diversity within, and the degree of spatial population structure between samples collected from Lake Michigan and tributaries of the Manistee River, MI. Measures of genetic diversity across 10 microsatellite loci were moderately high. Disparities between adult groups sampled in Lake Michigan and the Manistee River were notable for observed heterozygosity (0.662 vs 0.488) and allelic richness (11.7 vs 6.6). Significant levels of inter-population variance in microsatellite allele frequencies (F_ST 0.154 to 0.208) were detected between Lake Michigan and the Manistee River samples. Results indicate reproductive isolation between what plausibly may be riverine and lacustrine spawning life history types. Pedigree analyses for three cohorts sampled in the Manistee River revealed that a sizeable number of adults contributed reproductively to multiple cohorts, indicating spawning philopatry. While data were collected from restricted areas in lacustrine and river habitats, analyses revealing microgeographic genetic structuring, potentially attributed to life history polymorphisms, have significant implications for burbot management in the Great Lakes.     

Sewer System Design Using Simulated Annealing in Excel

An optimization procedure has been developed for branching storm and sanitary sewer systems with a pre-determined layout for determining the minimum total cost. The model was developed within Microsoft Excel using simulated annealing as the optimization procedure. The total cost of the storm sewer system that was obtained with this optimal design procedure was compared to the total cost of the system as obtained from the conventional straight slope design procedure. Applying the simulated annealing optimizer to the design of the branching storm sewer network resulted in a cost savings of over $77,100 or about 7 % (a reduction from $1,117,700 to $1,040,600). These significant savings were realized by simply going an extra step and implementing an optimization technique during the design phase. Use of Excel should enhance the availability and the usage of such an optimization model for the design of storm and sanitary sewer systems by consulting engineers and various agencies.