Structure-Function Analysis of Diacylglycerol Acyltransferase Sequences from 70 Organisms

<p>Abstract</p> <p>Background</p> <p>Diacylglycerol acyltransferase families (DGATs) catalyze the final and rate-limiting step of triacylglycerol (TAG) biosynthesis in eukaryotic organisms. Understanding the roles of DGATs will help to create transgenic plants with value-added properties and provide clues for therapeutic intervention for obesity and related diseases. The objective of this analysis was to identify conserved sequence motifs and amino acid residues for better understanding of the structure-function relationship of these important enzymes.</p> <p>Results</p> <p>117 DGAT sequences from 70 organisms including plants, animals, fungi and human are obtained from database search using tung tree DGATs. Phylogenetic analysis separates these proteins into DGAT1 and DGAT2 subfamilies. These DGATs are integral membrane proteins with more than 40% of the total amino acid residues being hydrophobic. They have similar properties and amino acid composition except that DGAT1s are approximately 20 kDa larger than DGAT2s. DGAT1s and DGAT2s have 41 and 16 completely conserved amino acid residues, respectively, although only two of them are shared by all DGATs. These residues are distributed in 7 and 6 sequence blocks for DGAT1s and DGAT2s, respectively, and located at the carboxyl termini, suggesting the location of the catalytic domains. These conserved sequence blocks do not contain the putative neutral lipid-binding domain, mitochondrial targeting signal, or ER retrieval motif. The importance of conserved residues has been demonstrated by site-directed and natural mutants.</p> <p>Conclusions</p> <p>This study has identified conserved sequence motifs and amino acid residues in all 117 DGATs and the two subfamilies. None of the completely conserved residues in DGAT1s and DGAT2s is present in recently reported isoforms in the multiple sequences alignment, raising an important question how proteins with completely different amino acid sequences could perform the same biochemical reaction. The sequence analysis should facilitate studying the structure-function relationship of DGATs with the ultimate goal to identify critical amino acid residues for engineering superb enzymes in metabolic engineering and selecting enzyme inhibitors in therapeutic application for obesity and related diseases.</p

Variations in the prevalence of point (pre)hypertension in a Nigerian school-going adolescent population living in a semi-urban and an urban area

<p>Abstract</p> <p>Background</p> <p>Hypertension has been shown to start in early life and to track into adulthood. Detecting adolescents with hypertension and prehypertension will aid early intervention and reduce morbidity and mortality from the disorders. This study reports the point-prevalence of the two disorders in a semi-urban and an urban population of school-going adolescents in Nigeria.</p> <p>Methods</p> <p>A total of 843 adolescents from two places of domicile were studied. Their blood pressures and anthropometric indices were measured using standard protocol. Point-hypertension and point-prehypertension were defined with respect to each subject's gender, age and height. The prevalence of the disorders was calculated and reported age-wise and nutritional status-wise.</p> <p>Results</p> <p>The prevalence of point-prehypertension in the semi-urban area was 22.2% (20.7% for girls and 23.1% for boys) while it was 25.0% (21.8% for girls and 29.2% for boys) in the urban area. The prevalence of point-hypertension was 4.6% (4.1% for girls and 4.8% for boys) in the semi-urban area and 17.5% (18.0% for girls and 16.9% for boys) in the urban area. Point-prehypertension was not detected among the thin subjects of both places of domicile. The prevalence of point-prehypertension was similar in both the urban and semi-urban areas among the subjects who had normal BMI-for-age, and over-weight/obese subjects respectively. From the semi-urban to the urban area, the prevalence of point-hypertension increased approximately 3-folds among thin and normal BMI-for-age subjects, and 10-folds among overweight/obese subjects. Systolic hypertension was more preponderant in both the semi-urban and urban areas.</p> <p>Conclusions</p> <p>The prevalence of both disorders is considerably high in the studied populations. Urgent pediatric public health action is needed to address the situation.</p

Two - three loci control scleral ossicle formation via epistasis in the cavefish Astyanax mexicanus.

The sclera is the protective outer layer of the eye. In fishes, birds, and reptiles, the sclera may be reinforced with additional bony elements called scleral ossicles. Teleost fish vary in the number and size of scleral ossicles; however, the genetic mechanisms responsible for this variation remain poorly understood. In this study, we examine the inheritance of scleral ossicles in the Mexican tetra, Astyanax mexicanus, which exhibits both a cave morph and a surface fish morph. As these morphs and their hybrids collectively exhibit zero, one, and two scleral ossicles, they represent a microcosm of teleost scleral ossicle diversity. Our previous research in F2 hybrids of cavefish from Pachón cave and surface fish from Texas suggested that three genes likely influence the formation of scleral ossicles in this group through an epistatic threshold model of inheritance, though our sample size was small. In this study, we expand our sample size using additional hybrids of Pachón cavefish and Mexican surface fish to (1) confirm the threshold model of inheritance, (2) refine the number of genes responsible for scleral ossicle formation, and (3) increase our power to detect quantitative trait loci (QTL) for this trait. To answer these three questions, we scored surface fish and cavefish F2 hybrids for the presence of zero, one, or two scleral ossicles. We then analyzed their distribution among the F2 hybrids using a chi-square (χ2) test, and used a genetic linkage map of over 100 microsatellite markers to identify QTL responsible for scleral ossicle number. We found that inheritance of scleral ossicles follows an epistatic threshold model of inheritance controlled by two genes, which contrasts the three-locus model estimated from our previous study. Finally, the combined analysis of hybrids from both crosses identified two strong QTL for scleral ossicle number on linkage groups 4.2 and 21, and a weaker QTL on linkage group 4.1. Scleral ossification remains a complex trait with limited knowledge of its genetic basis. This study provides new insight into the number and location of genes controlling the formation of scleral ossicles in a teleost fish species

New Zealand and Louisiana practicing teachers' conceptions of feedback : impact of Assessment of Learning versus Assessment for Learning policies?

Teacher beliefs about feedback matter since they are responsible for its implementation in classrooms. This paper compares the conceptions of feedback of practicing teachers from two very different jurisdictions (Louisiana, USA, n=308; New Zealand, n=518). Responses to a common research inventory were modelled independently but multi-group confirmatory factor analysis produced inadmissible solutions for both models. Joint factor analysis produced a five-factor solution, which was inadmissible for the Louisiana teachers. Inter-correlations around feedback as teacher-grading exceeded 1.00 for Louisiana teachers; whereas, New Zealand teachers had correlations close to zero for this factor. While both groups of teachers endorsed the notion of feedback for improved learning, differences appear related to contrasting assessment policy frameworks (i.e., high-stakes in Louisiana, low-stakes in New Zealand)

The Results (Lessons Learned) of More than 110 Energy Audits for Manufacturers by the Louisiana Industrial Assessment Center

This paper and discussion presents the summary and results of energy audits or assessments conducted by the University of Louisiana Lafayette Industrial Assessment Center, which is sponsored by the US Department of Energy, for the first four years of operation. To insure the confidentiality of our clients, the results are generalized and summarized by industry type and recommendation type. Where the assessment finding and recommendations have been implemented, the implementation rate is shown. For recommendations that have the most significant savings and a high implementation rate, we will show the summarized implementation cost and payback period. The Industrial Assessment Center of the University of Louisiana Lafayette began operation in FY01 and conducted its first industrial energy assessment in December 2000. In this paper we present the results of this energy assessment and those of 112 more through August 2004. By industrial type, these assessments were for: Oilfield Equipment Manufacturing (23%), Food and Food Processing (18%), Petrochemical Manufacturing and Refineries (13%), Other (non-Oilfield) Equipment Manufacturing (12%), Ship Building and Repair (8%), Woodworking, Clothing and Wire Manufacturing (6%), Paper, Cardboard, Boxes and Bag Manufacturing (5%), Machining (4%), Building and Building Materials (4%), Printing (4%), and Glass and Ceramics Manufacturing (3%). The distribution of manufacturers for the State of Louisiana is weighted much higher in the Petrochemical Manufacturing and Refineries, however because of limitations on the amount of energy consumed (restrictions for the Industrial Assessment Centers), many of these are beyond the scope for Industrial Assessment Centers. For most of the recommendations we make, we try to keep the installation cost (parts and labor) within a one-year payback period. However, we have occasionally looked at longer payback periods when suggested by the client. The recommendations for each industry type are summarized in the following ten categories: air leaks and operating compressed air pressure (includes methods to lower cost by lowering the operating air pressure), replace air tools with electric tools (includes grinders, chippers, wrenches, and fans or blowers to replace air horns), installation of insulation (on hot or cold equipment, pipes and buildings), lighting (photo sensors, reductions, occupancy sensors, and LED exit signs), recycling, combustion efficiency and CHP, steam leaks and traps, heating and cooling (people and space), alternative fuels and operations, and productivity improvements (including preventive maintenance and group lighting replacement)