Wilaiwan Chotigeat

Bio: Wilaiwan Chotigeat is an academic researcher from Prince of Songkla University. The author has contributed to research in topics: Shrimp & White spot syndrome. The author has an hindex of 20, co-authored 91 publications receiving 1492 citations. Previous affiliations of Wilaiwan Chotigeat include Mahidol University & National University of Singapore.

Role of environmental conditions on the expression levels, glycoform pattern and levels of sialyltransferase for hFSH produced by recombinant CHO cells

Abstract: A recombinant CHO cell line in which the expresison of human follicle stimulating hormone (hFSH) was under the control of the β actin promoter was maintained in steady state perfusion cultures on a protein free medium. The level of expression of the hFSH was controlled by varying the steady state level of dissolved oxygen (10–90% of air saturation) and of sodium butyrate (0–1.5mM). Under these conditions, the specific productivity of hFSH (qFSH) varied from 0.7 to 4.8 ng hFSH/106 cells/h. As the specific productivity of hFSH increased, there was a shift in the FSH isoforms to the lower pI fractions, corresponding to increased sialic acid content. As the specific productivity of hFSH increased, shifting the isoform distribution towards the lower pI isoforms, that the sialyltransferase enzymic activity also increased.

Molecular Evolution of the Odorant and Gustatory Receptor Genes in Lepidopteran Insects: Implications for Their Adaptation and Speciation

Abstract: Lepidoptera (comprised of butterflies and moths) is one of the largest groups of insects, including more than 160,000 described species Chemoreception plays important roles in the adaptation of these species to a wide range of niches, eg, plant hosts, egg-laying sites, and mates This study investigated the molecular evolution of the lepidopteran odorant (Or) and gustatory receptor (Gr) genes using recently identified genes from Bombyx mori, Danaus plexippus, Heliconius melpomene, Plutella xylostella, Heliothis virescens, Manduca sexta, Cydia pomonella, and Spodoptera littoralis A limited number of cases of large lineage-specific gene expansion are observed (except in the P xylostella lineage), possibly due to selection against tandem gene duplication There has been strong purifying selection during the evolution of both lepidopteran odorant and gustatory genes, as shown by the low ω values estimated through CodeML analysis, ranging from 00093 to 03926 However, purifying selection has been relaxed on some amino acid sites in these receptors, leading to sequence divergence, which is a precursor of positive selection on these sequences Signatures of positive selection were detected only in a few loci from the lineage-specific analysis Estimation of gene gains and losses suggests that the common ancestor of the Lepidoptera had fewer Or genes compared to extant species and an even more reduced number of Gr genes, particularly within the bitter receptor clade Multiple gene gains and a few gene losses occurred during the evolution of Lepidoptera Gene family expansion may be associated with the adaptation of lepidopteran species to plant hosts, especially after angiosperm radiation Phylogenetic analysis of the moth sex pheromone receptor genes suggested that chromosomal translocations have occurred several times New sex pheromone receptors have arisen through tandem gene duplication Positive selection was detected at some amino acid sites predicted to be in the extracellular and transmembrane regions of the newly duplicated genes, which might be associated with the evolution of the new pheromone receptors

Characterization and Small RNA Content of Extracellular Vesicles in Follicular Fluid of Developing Bovine Antral Follicles

Abstract: Exosomes and microvesicles (i.e., extracellular vesicles: EVs) have been identified within ovarian follicular fluid and recent evidence suggests that EVs are able to elicit profound effects on ovarian cell function. While existence of miRNA within EVs has been reported, whether EV size and concentration as well as their cargos (i.e., proteins and RNA) change during antral follicle growth remains unknown. Extracellular vesicles isolated from follicular fluid of small, medium and large bovine follicles were similar in size, while concentration of EVs decreased progressively as follicle size increased. Electron microscopy indicated a highly purified population of the lipid bilayer enclosed vesicles that were enriched in exosome biomarkers including CD81 and Alix. Small RNA sequencing identified a large number of known and novel miRNAs that changed in the EVs of different size follicles. Ingenuity Pathway Analysis (IPA) indicated that miRNA abundant in small follicle EV preparations were associated with cell proliferation pathways, while those miRNA abundant in large follicle preparations were related to inflammatory response pathways. These studies are the first to demonstrate that EVs change in their levels and makeup during antral follicle development and point to the potential for a unique vesicle-mediated cell-to-cell communication network within the ovarian follicle.

Absence of S6K1 protects against age- and diet-induced obesity while enhancing insulin sensitivity. [Erratum: 2004 Sept. 23, v. 431, no. 7007, p. 485.]

Abstract: Elucidating the signalling mechanisms by which obesity leads to impaired insulin action is critical in the development of therapeutic strategies for the treatment of diabetes. Recently, mice deficient for S6 Kinase 1 (S6K1), an effector of the mammalian target of rapamycin (mTOR) that acts to integrate nutrient and insulin signals, were shown to be hypoinsulinaemic, glucose intolerant and have reduced β-cell mass. However, S6K1-deficient mice maintain normal glucose levels during fasting, suggesting hypersensitivity to insulin, raising the question of their metabolic fate as a function of age and diet. Here, we report that S6K1-deficient mice are protected against obesity owing to enhanced β-oxidation. However on a high fat diet, levels of glucose and free fatty acids still rise in S6K1-deficient mice, resulting in insulin receptor desensitization. Nevertheless, S6K1-deficient mice remain sensitive to insulin owing to the apparent loss of a negative feedback loop from S6K1 to insulin receptor substrate 1 (IRS1), which blunts S307 and S636/S639 phosphorylation; sites involved in insulin resistance. Moreover, wild-type mice on a high fat diet as well as K/K Ay and ob/ob (also known as Lep/Lep) micetwo genetic models of obesityhave markedly elevated S6K1 activity and, unlike S6K1-deficient mice, increased phosphorylation of IRS1 S307 and S636/S639. Thus under conditions of nutrient satiation S6K1 negatively regulates insulin signalling.

The evolution of the plastid chromosome in land plants: gene content, gene order, gene function.

Abstract: This review bridges functional and evolutionary aspects of plastid chromosome architecture in land plants and their putative ancestors. We provide an overview on the structure and composition of the plastid genome of land plants as well as the functions of its genes in an explicit phylogenetic and evolutionary context. We will discuss the architecture of land plant plastid chromosomes, including gene content and synteny across land plants. Moreover, we will explore the functions and roles of plastid encoded genes in metabolism and their evolutionary importance regarding gene retention and conservation. We suggest that the slow mode at which the plastome typically evolves is likely to be influenced by a combination of different molecular mechanisms. These include the organization of plastid genes in operons, the usually uniparental mode of plastid inheritance, the activity of highly effective repair mechanisms as well as the rarity of plastid fusion. Nevertheless, structurally rearranged plastomes can be found in several unrelated lineages (e.g. ferns, Pinaceae, multiple angiosperm families). Rearrangements and gene losses seem to correlate with an unusual mode of plastid transmission, abundance of repeats, or a heterotrophic lifestyle (parasites or myco-heterotrophs). While only a few functional gene gains and more frequent gene losses have been inferred for land plants, the plastid Ndh complex is one example of multiple independent gene losses and will be discussed in detail. Patterns of ndh-gene loss and functional analyses indicate that these losses are usually found in plant groups with a certain degree of heterotrophy, might rendering plastid encoded Ndh1 subunits dispensable.

Optimal and consistent protein glycosylation in mammalian cell culture.

Abstract: In the biopharmaceutical industry, mammalian cell culture systems, especially Chinese hamster ovary (CHO) cells, are predominantly used for the production of therapeutic glycoproteins. Glycosylation is a critical protein quality attribute that can modulate the efficacy of a commercial therapeutic glycoprotein. Obtaining a consistent glycoform profile in production is desired due to regulatory concerns because a molecule can be defined by its carbohydrate structures. An optimal profile may involve a spectrum of product glycans that confers a desired therapeutic efficacy, or a homogeneous glycoform profile that can be systemically screened for. Studies have shown some degree of protein glycosylation control in mammalian cell culture, through cellular, media, and process effects. Studies upon our own bioprocesses to produce fusion proteins and monoclonal antibodies have shown an intricate relationship between these variables and the resulting protein quality. Glycosylation optimization will improve therapeutic efficacy and is an ongoing goal for researchers in academia and industry alike. This review will focus on the advancements made in glycosylation control in a manufacturing process, as well as the next steps in understanding and controlling protein glycosylation.

MicroRNAs: Target Recognition and Regulatory Functions

Abstract: MicroRNAs (miRNAs) are endogenous ∼23 nt RNAs that play important gene-regulatory roles in animals and plants by pairing to the mRNAs of protein-coding genes to direct their posttranscriptional repression. This review outlines the current understanding of miRNA target recognition in animals and discusses the widespread impact of miRNAs on both the expression and evolution of protein-coding genes.