6-Phospho-{beta}-galactosidases of Gram-positive and 6-phospho-{beta}-glucosidase B of Gram-negative bacteria: comparison of structure and function by kinetic and immunological methods and mutagenesis of the lacG gene of staphylococcus aureus

The 6-phospho-ß-galactosidase of Staphylococcus aureus,Lactococcus lactis and Lactobacillus casei and 6-phospho-ßglucosidaseB of Escherichia coli build a subfamily inside a greater enzymefamily, named the glycosal hydrolase family 1, which, hi addition,contains nine ß-glycosidases of different origins.Kinetic and immunological evidence is provided in this reportwhich strengthens the relationship of the four 6-phospho-ß-glycosidases.It is shown that the 6-phospho-ß-galactosidases and6-phospho-ß-glucosidase B are able to split aromaticß-galactoside phosphates and ß-glucosidephosphates. The turnover numbers of hydrolysis of substrateswith different epimerization at C-4 of the glycon vary up to15-fold only. Two polydonal antisera, one derived against thenative 6-phospho-ß-galactosidase from S.aureus andthe other derived against the 6-phospho-ß-glucosidaseB, cross-reacted with both enzymes. Peptides of the proteinswere separated by reverse phase HPLC. The cross-reacting peptideswere sequenced and shown to be localized at almost the sameposition in the aligned primary structures of both enzymes.An insertion of nine amino adds near these antigenic domainsis unique for the 6-phospho-ß-glycosidases and missingwithin the sequences of the ß-glycoside-specific membersof the family. The lacG gene of a 6-phospho-ß-galactosidasenegative S.aureus mutant was doned into E.coli and sequenced.In the totally inactive mutant protein only the glycine at position332 was changed to an arginine. This amino acid is part of thesequence insertion near the antigenic domain reacting with bothantisera. These data support the assumption that the regionis of great importance for the function of the enzymes and thatit is possible it determines the specificity of the phosphorylatedform of the substrates. In addition, the 6-phospho-ß-galactosidaseof S.aureus was modified by sitedirected mutagenesis of thecorresponding lacG gene hi order to replace residues Glul60and Glu375, which were suspected of being involved hi the generalacid catalysis of substrate hydrolysis, with glutamine residues.The mutant protein 160EQ retained some catalytic activity whilethe protein 375EQ was totally inactive. Glu375 is the activesite nudeophile of the 6-phospho-ß-galactosidase ofS.aureus. It is located in the sequence motif ENG where Glu358was identified as the catalytkally active nudeophile hi theß-glucosidase of Agrobacterium.     

Laser Induced Liquid Phase Reaction Synthesis Assisted Joining of Metal Matrix Composites

A Laser Induced Liquid Phase Reaction Synthesis Assisted Joining technique is employed for SiC-particulate/Al-alloy composite to produce joints. Joints in SiC/Al-alloy composite are produced by synthesis of suitable material product as a result of interaction between composite and Ti (or Ti-alloy) reactive filler material induced by laser energy in the joint region. Such reaction product minimizes or eliminates the formation of deleterious aluminum carbide phase in the joint region depending upon the type and nature of die interfacial reactive filler material and also the laser processing parameters. A laser beam is utilized to both synthesize the interfacial reactant mixture and to heat the base material adjacent to the joint region to minimize the thermal stresses. The technique along with suitable filler material, further can be extended to a variety of metal matrix composite systems including combinations of Gr/Al, B/Al, B₄C/Mg, Steel/Al, W/Al, Al₂ O₃ and Gr/Cu which are excellent for use in various automotive, aerospace and electronic applications. Preliminary observations describing the proof of concept of laser induced reaction joining of metal matrix composites are reported     

Convergence of the inductive and deductive models in the measurement of reasoning abilities.

Reviews evidence concerning the congruence of the inductive and deductive models in logic and presents support for this congruence in the context of new test items designed to exemplify general-to-particular induction. Data from the Professional and Administrative Career Examination corroborate the logical foundations of deduction and induction as convergent models. Factor analysis of the items demonstrated factorial convergence, which lends additional support to the postulate of convergence. Implications for the understanding of cognitive processes and for psychometric practice are discussed in relation to such issues as the use of verbal and nonverbal test media, redundancy of measurement, and problem-solving strategies. (50 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Bending and torsional fatigue of nylon 66 monofilaments

Using newly developed test equipment, the fatigue behavior of nylon 66 monofilaments was studied under two loading conditions, pure bending or simple torsion. For each mode, results are expressed in terms of the measured decay in stiffness with numbers of cycles over a range of maximum applied strain levels. Fatigue lifetimes are presented in S–N format where the log number of cycles of fatigue for a 40% decay in stiffness (N) is plotted as a function of applied strain (S). The failure mechanism for these fibers in each fatigue mode reflects the morphology of semicrystalline-oriented synthetic fibers. In torsion, many longitudinal cracks form around the perimeter of a fiber as the result of cleavage of the relatively weak interfibrillar bonds in nylon 66. In bending, cracks form within kink band boundaries and grow at an oblique angle to the fiber axis. © 1992 John Wiley & Sons, Inc.     

MANOVA method for analyzing repeated measures designs: An extensive primer.

Contends that tests in repeated-measures designs based on MANOVA are free of sphericity assumptions, and with modern computing software, MANOVA is straightforward to use, even for complex designs and nontraditional hypotheses. A general strategy for implementing MANOVA within statistical computing packages is presented. Regular (preplanned) tests and simultaneous (post hoc) tests are illustrated for a variety of designs and hypotheses. Optimal contrasts for unbalanced repeated measures designs are appended. (33 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Dynamic proteome in enigmatic preeclampsia: an account of molecular mechanisms and biomarker discovery

The coevolution of genomics and proteomics has led to advancements in the field of diagnosis and molecular mechanisms of disease. Proteomics is now stepping into the field of obstetrics, where early diagnosis of pregnancy complication such as preeclampsia (PE) is imperative. PE is a multifactorial disease characterized by hypertension with proteinuria, which is a leading cause of maternal and neonatal morbidity and mortality occurring in 5-7% of pregnancies worldwide. This review discusses the probable molecular mechanisms that lead to PE and summarizes the proteomics research carried out in understanding the pathogenicity of PE, and for identifying the candidate biomarker for diagnosis of the disease.     

Rainbow smelt population responses to species invasions and change in environmental condition

Invasive species can cause major disruptions in native food webs, yet the impact of species introductions and whether they will become invasive appears to be context-dependent. Rainbow smelt and alewife co-exist as invasive species in the Laurentian Great Lakes and as native species on the Atlantic coast of North America, but in Lake Champlain rainbow smelt is the dominant native forage fish and alewife are invasive. Alewife became abundant by 2007, providing an opportunity to explore the dynamics of these two species in a system where only one is invasive. We used data from a 28-year forage fish survey to compare demographics of rainbow smelt populations in three basins of Lake Champlain with different volumes, nutrient levels, and predator abundances. Rainbow smelt catch-per-unit-effort (CPUE) remained constant in the large, deep Main Lake before and after alewife invaded, but decreased in the two smaller basins. Declines were primarily a result of increased age-0 and age-1 mortality. Predation by top piscivores, system productivity, and competition for resources alone could not explain the patterns in CPUE across the basins. The mechanisms that allow alewife and rainbow smelt to co-exist could be related to system volume and oxythermal habitat availability, and may explain why the two species do not negatively affect each other in the Great Lakes. Summer hypoxia in the smaller basins could force individuals into smaller habitat volumes with higher densities of competitors and cannibalistic adult rainbow smelt. Habitat availability may mediate the impact of invasive alewife on native rainbow smelt.     

A Historical View of Studies of Women’s Work

Computer Supported Cooperative Work (CSCW) - This paper places observational studies of women’s work in historical perspective. We present some of the very early studies (carried out in the...