Lipid Biosynthetic Process Research Articles

Smoking is associated to altered lipid metabolomic pathways in adult men with varicocele

Smoking is associated to altered lipid metabolomic pathways in adult men with varicocele

A region on BTA14 that includes the positional candidate genes LYPLA1, XKR4 and TMEM68 is associated with feed intake and growth phenotypes in cattle1

Feed cost for beef cattle is the largest expense incurred by cattle producers. The development of genetic markers to enhance selection of more efficient animals that require less feed while still achieving acceptable levels of production has the potential to substantially reduce production costs. A genome-wide marker association approach based on the Illumina BovineSNP50 BeadChip™ was used to identify genomic regions affecting average daily feed intake (ADFI), average daily gain (ADG) and residual feed intake traits in a population of 1159 crossbred steers. This approach identified a region on BTA14 from 22.02 to 23.92 Mb containing several single-nucleotide polymorphisms (SNPs) that have significant association with at least one of the traits. Two genes in this region, lysophospholipase 1 (LYPLA1) and transmembrane protein 68 (TMEM68), appeared to be logical positional and functional candidate genes. LYPLA1 deacylates ghrelin, a hormone involved in the regulation of appetite in the rat stomach, while TMEM68 is expressed in bovine rumen, abomasum, intestine and adipose tissue in cattle, and likely affects lipid biosynthetic processes. SNPs lying in or near these two genes were identified by sequencing a subset of animals with extreme phenotypes. A total of 55 SNPs were genotyped and tested for association with the same population of steers. After correction for multiple testing, five markers within 22.79-22.84 Mb, located downstream of TMEM68, and between TMEM68 and the neighbouring gene XKR4, were significant for both ADFI and ADG. Genetic markers predictive of feed intake and weight gain phenotypes in this population of cattle may be useful for the identification and selection of animals that consume less feed, although further evaluation of these markers for effects on other production traits and validation in additional populations will be required.

Hepatic Gene Expression Profiling Reveals Key Pathways Involved in Leptin-Mediated Weight Loss in ob/ob Mice

BackgroundLeptin, a cytokine-like protein, plays an important role in the regulation of body weight through inhibition of food intake and stimulation of energy expenditure. Leptin circulates in blood and acts on the brain, which sends downstream signals to regulate body weight. Leptin therapy has been successful in treating leptin deficient obese patients. However, high levels of leptin have been observed in more common forms of obesity indicating a state of leptin resistance which limits the application of leptin in the treatment of obesity. If the central effect of leptin could be by-passed and genes which respond to leptin treatment could be regulated directly, new therapeutic targets for the treatment of obesity may be possible. The purpose of this study was to identify genes and subsequent pathways correlated with leptin-mediated weight loss.Methodology/Principal FindingsWe utilized microarray technology to compare hepatic gene expression changes after two types of leptin administration: one involving a direct stimulatory effect when administered peripherally (subcutaneous: SQ) and another that is indirect, involving a hypothalamic relay that suppresses food intake when leptin is administered centrally (intracerebroventricular: ICV). We identified 214 genes that correlate with leptin mediated weight loss. Several biological processes such as mitochondrial metabolic pathways, lipid metabolic and catabolic processes, lipid biosynthetic processes, carboxylic acid metabolic processes, iron ion binding and glutathione S-transferases were downregulated after leptin administration. In contrast, genes involved in the immune system inflammatory response and lysosomal activity were found to be upregulated. Among the cellular compartments mitochondrion (32 genes), endoplasmic reticulum (22 genes) and vacuole (8 genes) were significantly over represented.Conclusions/SignificanceIn this study we have identified key molecular pathways and downstream genes which respond to leptin treatment and are involved in leptin-mediated weight loss. Many of these genes have previously been shown to be associated with obesity; however, we have also identified a number of other novel target genes. Further investigation will be required to assess the possible use of these genes and their associated protein products as therapeutic targets for the treatment of obesity.

Metabolic pathways of the wheat (Triticum aestivum) endosperm amyloplast revealed by proteomics

BackgroundBy definition, amyloplasts are plastids specialized for starch production. However, a proteomic study of amyloplasts isolated from wheat (Triticum aestivum Butte 86) endosperm at 10 days after anthesis (DPA) detected enzymes from many other metabolic and biosynthetic pathways. To better understand the role of amyloplasts in food production, the data from that study were evaluated in detail and an amyloplast metabolic map was outlined.ResultsAnalysis of 288 proteins detected in an amyloplast preparation predicted that 178 were amyloplast proteins. Criteria included homology with known plastid proteins, prediction of a plastid transit peptide for the wheat gene product or a close homolog, known plastid location of the pathway, and predicted plastid location for other members of the same pathway. Of these, 135 enzymes were arranged into 18 pathways for carbohydrate, lipid, amino acid, nucleic acid and other biosynthetic processes that are critical for grain-fill. Functions of the other proteins are also discussed.ConclusionThe pathways outlined in this paper suggest that amyloplasts play a central role in endosperm metabolism. The interacting effects of genetics and environment on starch and protein production may be mediated in part by regulatory mechanisms within this organelle.

Lipid Concentration and Composition of Soybean Zygotic Embryos Maturing In Vitro and In Planta

Reliable methods of culturing isolated immature soybean embryos under stringent environmental controls are available, but have not been used to study factors affecting soybean seed lipid biosynthesis. This study compared the changes in lipid composition during seed maturation in planta and in two in vitro culture systems and evaluated both culture systems for studying the developmental regulation of lipid biosynthesis. Immature soybean [Glycine max (L.) Merr. cv. McCall] embryos from three developmental stages (seed length = 2–3, 5–6, or 8–9 ram) were cultured for 5, 15, or 45 d in LSG (modified Linsmaer‐Skoog salts, 50 g kg−1 sucrose) or SHGM (Schenk‐Hildebrandt salts, 10 g kg−1 sucrose) liquid culture media. Lipid concentrations of the cultured embryos ranged from 10 to 179 g kg−1 dry wt. and were consistently lower than that of mature seed (185 g kg−1 dry wt.). Regardless of stage at excision, the mole percent (mol %) of palmitic and linolenic acids declined and the mol % linoleic acid increased when embryos were cultured in LSG. This pattern is consistent with that observed during maturation in planta. In contrast, the mol % of palmitic and stearic acids increased when embryos were cultured in SHGM and the resulting fatty acid profiles bore little resemblance to those of mature seed. Immature embryo culture in LSG medium provides a viable system for examining lipid biosynthetic processes and, with discriminant function analysis of storage lipid composition, can provide a useful estimate of embryo maturation.