Estela L. Arrese

Bio: Estela L. Arrese is an academic researcher from Oklahoma State University–Stillwater. The author has contributed to research in topics: Lipid droplet & Lipolysis. The author has an hindex of 22, co-authored 44 publications receiving 3103 citations. Previous affiliations of Estela L. Arrese include University of Arizona.

Insect Fat Body: Energy, Metabolism, and Regulation

Abstract: The fat body plays major roles in the life of insects. It is a dynamic tissue involved in multiple metabolic functions. One of these functions is to store and release energy in response to the energy demands of the insect. Insects store energy reserves in the form of glycogen and triglycerides in the adipocytes, the main fat body cell. Insect adipocytes can store a great amount of lipid reserves as cytoplasmic lipid droplets. Lipid metabolism is essential for growth and reproduction and provides energy needed during extended nonfeeding periods. This review focuses on energy storage and release and summarizes current understanding of the mechanisms underlying these processes in insects.

Deep sequencing of small RNA libraries reveals dynamic regulation of conserved and novel microRNAs and microRNA-stars during silkworm development

Abstract: In eukaryotes, microRNAs (miRNAs) have emerged as critical regulators of gene expression. The Silkworm (Bombyx mori L.) is one of the most suitable lepidopteran insects for studying the molecular aspects of metamorphosis because of its large size, availability of mutants and genome sequence. Besides, this insect also has been amply studied from a physiological and biochemical perspective. Deep sequencing of small RNAs isolated from different stages of silkworm is a powerful tool not only for measuring the changes in miRNA profile but also for discovering novel miRNAs. We generated small RNA libraries from feeding larvae, spinning larvae, pupae and adults of B. mori and obtained ~2.5 million reads of 18-30 nt. Sequence analysis identified 14 novel and 101 conserved miRNAs. Most novel miRNAs are preferentially expressed in pupae, whereas more than 95% of the conserved miRNAs are dynamically regulated during different developmental stages. Remarkably, the miRNA-star (miR*) of four miRNAs are expressed at much higher levels than their corresponding miRNAs, and their expression profiles are distinct from their corresponding miRNA profiles during different developmental stages. Additionally, we detected two antisense miRNA loci (miR-263-S and miR-263-AS; miR-306-S and miR-306-AS) that are expressed in sense and antisense directions. Interestingly, miR-263 and miR-306 are preferentially and abundantly expressed in pupae and adults, respectively. We identified 101 homologs of conserved miRNAs, 14 species-specific and two antisense miRNAs in the silkworm. Our results provided deeper insights into changes in conserved and novel miRNA and miRNA* accumulation during development.

Electrophoretic, solubility and functional properties of commercial soy protein isolates

Abstract: The aim was to determine the degree of protein denaturation and the relative amounts of the different protein species and to determine the incidence of the structural features of the proteins on the solubility, water-imbibing capacity, viscosity, and gelation capacity of commercial soy protein isolates

Insect Fat Body: Energy, Metabolism, and Regulation

Abstract: The fat body plays major roles in the life of insects. It is a dynamic tissue involved in multiple metabolic functions. One of these functions is to store and release energy in response to the energy demands of the insect. Insects store energy reserves in the form of glycogen and triglycerides in the adipocytes, the main fat body cell. Insect adipocytes can store a great amount of lipid reserves as cytoplasmic lipid droplets. Lipid metabolism is essential for growth and reproduction and provides energy needed during extended nonfeeding periods. This review focuses on energy storage and release and summarizes current understanding of the mechanisms underlying these processes in insects.

Automated Eukaryotic Gene Structure Annotation Using EVidenceModeler and the Program to Assemble Spliced Alignments

Abstract: EVidenceModeler (EVM) is presented as an automated eukaryotic gene structure annotation tool that reports eukaryotic gene structures as a weighted consensus of all available evidence. EVM, when combined with the Program to Assemble Spliced Alignments (PASA), yields a comprehensive, configurable annotation system that predicts protein-coding genes and alternatively spliced isoforms. Our experiments on both rice and human genome sequences demonstrate that EVM produces automated gene structure annotation approaching the quality of manual curation.

Identification of a gene encoding an acyl CoA:diacylglycerol acyltransferase, a key enzyme in triacylglycerol synthesis

Abstract: Triacylglycerols are quantitatively the most important storage form of energy for eukaryotic cells Acyl CoA:diacylglycerol acyltransferase (DGAT, EC 23120) catalyzes the terminal and only committed step in triacylglycerol synthesis, by using diacylglycerol and fatty acyl CoA as substrates DGAT plays a fundamental role in the metabolism of cellular diacylglycerol and is important in higher eukaryotes for physiologic processes involving triacylglycerol metabolism such as intestinal fat absorption, lipoprotein assembly, adipose tissue formation, and lactation DGAT is an integral membrane protein that has never been purified to homogeneity, nor has its gene been cloned We identified an expressed sequence tag clone that shared regions of similarity with acyl CoA:cholesterol acyltransferase, an enzyme that also uses fatty acyl CoA as a substrate Expression of a mouse cDNA for this expressed sequence tag in insect cells resulted in high levels of DGAT activity in cell membranes No other acyltransferase activity was detected when a variety of substrates, including cholesterol, were used as acyl acceptors The gene was expressed in all tissues examined; during differentiation of NIH 3T3-L1 cells into adipocytes, its expression increased markedly in parallel with increases in DGAT activity The identification of this cDNA encoding a DGAT will greatly facilitate studies of cellular glycerolipid metabolism and its regulation

Genome-wide gene-based analyses of weight loss interventions identify a potential role for NKX6.3 in metabolism.

Abstract: Hundreds of genetic variants have been associated with Body Mass Index (BMI) through genome-wide association studies (GWAS) using observational cohorts. However, the genetic contribution to efficient weight loss in response to dietary intervention remains unknown. We perform a GWAS in two large low-caloric diet intervention cohorts of obese participants. Two loci close to NKX6.3/MIR486 and RBSG4 are identified in the Canadian discovery cohort (n = 1166) and replicated in the DiOGenes cohort (n = 789). Modulation of HGTX (NKX6.3 ortholog) levels in Drosophila melanogaster leads to significantly altered triglyceride levels. Additional tissue-specific experiments demonstrate an action through the oenocytes, fly hepatocyte-like cells that regulate lipid metabolism. Our results identify genetic variants associated with the efficacy of weight loss in obese subjects and identify a role for NKX6.3 in lipid metabolism, and thereby possibly weight control. Individuals show large variability in their capacity to lose weight and maintain this weight. Here, the authors perform GWAS in two weight loss intervention cohorts and identify two genetic loci associated with weight loss that are taken forward for Bayesian fine-mapping and functional assessment in flies.

Directed self-assembly of monodisperse phospholipid bilayer Nanodiscs with controlled size.

Abstract: Using a recently described self-assembly process (Bayburt, T. H.; Grinkova, Y. V.; Sligar, S. G. Nano Letters 2002, 2, 853−856), we prepared soluble monodisperse discoidal lipid/protein particles with controlled size and composition, termed Nanodiscs, in which the fragment of dipalmitoylphosphatidylcholine (DPPC) bilayer is surrounded by a helical protein belt. We have customized the size of these particles by changing the length of the amphipathic helical part of this belt, termed membrane scaffold protein (MSP). Herein we describe the design of extended and truncated MSPs, the optimization of self-assembly for each of these proteins, and the structure and composition of the resulting Nanodiscs. We show that the length of the protein helix surrounding the lipid part of a Nanodisc determines the particle diameter, as measured by HPLC and small-angle X-ray scattering (SAXS). Using different scaffold proteins, we obtained Nanodiscs with the average size from 9.5 to 12.8 nm with a very narrow size distributi...