The composition, metabolism, and significance of fatty acids in insect biology are addressed. Fatty acids enter a number of metabolic pathways not directly related to energy storage and production; the unifying theme is that the fatty acids are not only structurally altered in these pathways, but that the alterations carry them from one area of biological significance into another. This theme is developed by offering a perspective on fatty acids in insects and then reviewing three major areas: 1) fatty acid composition, 2) biosynthesis of fatty acids (including polyunsaturated fatty acids and characteristics of certain biosynthetic enzymes), and 3) the biological significance of fatty acids. This last section includes discussions of the biochemistry of waxes, pheromones, and prostaglandins and the roles of fatty acids as components of defensive secretions. Little is known at the biochemical level about the regulation of fatty acid metabolism, and it is suggested that work in this area represents another frontier in insect biochemistry.

The chemistry, biochemistry, and physiology of insect cuticular lipids are reviewed. The types of components present in cuticular extracts are described with special emphasis on the occurrence and identification of the di-and trimethylalkanes and the newly discovered tetramethylalkanes. The methods used in the extraction of cuticular components are discussed, including recommendations to standardize procedures. The structural elucidation of methylalkanes, particularly the mass spectral interpretation of multi-methylbranched alkanes, is reviewed. The biosynthesis of cuticular lipids is discussed with emphasis on the hydrocarbon components, describing elongation reactions and the origin of the methyl branches. The effects of environment and development on cuticular lipids are reviewed.

IntroductionIdentification of gene expression-based breast cancer subtypes is considered a critical means of prognostication. Genetic mutations along with epigenetic alterations contribute to gene-expression changes occurring in breast cancer. So far, these epigenetic contributions to sporadic breast cancer subtypes have not been well characterized, and only a limited understanding exists of the epigenetic mechanisms affected in those particular breast cancer subtypes. The present study was undertaken to dissect the breast cancer methylome and to deliver specific epigenotypes associated with particular breast cancer subtypes.MethodsBy using a microarray approach, we analyzed DNA methylation in regulatory regions of 806 cancer-related genes in 28 breast cancer paired samples. We subsequently performed substantial technical and biologic validation by pyrosequencing, investigating the top qualifying 19 CpG regions in independent cohorts encompassing 47 basal-like, 44 ERBB2+ overexpressing, 48 luminal A, and 48 luminal B paired breast cancer/adjacent tissues. With the all-subset selection method, we identified the most subtype-predictive methylation profiles in multivariable logistic regression analysis.ResultsThe approach efficiently recognized 15 individual CpG loci differentially methylated in breast cancer tumor subtypes. We further identified novel subtype-specific epigenotypes that clearly demonstrate the differences in the methylation profiles of basal-like and human epidermal growth factor 2 (HER2)-overexpressing tumors.ConclusionsOur results provide evidence that well-defined DNA methylation profiles enable breast cancer subtype prediction and support the utilization of this biomarker for prognostication and therapeutic stratification of patients with breast cancer.

No abstract

Adverse health effect of trans fatty acids (TFAs) are well recognized , which has precipitated efforts to reduce their content in food products. With the decline of dietary TFAs derived from partial oil hydrogenation, interest is focused on the remaining sources of dietary TFAs derived from ruminants (rTFA), deo-dorized vegetable oils, trans isomerization during frying, and synthetic conjugated FA (CFA) supplements. Partial hydro-genation and heat-treated oils result in a random distribution of TFA isomers, whereas rTFAs contain specifi c isomers resulting from enzymatic processes. Reviews of human observational and metabolic intervention studies have suggested that consumption of rTFAs at current levels should not raise health concerns. However, these studies were not based on rTFA levels currently sold in retail markets. Current feeding practices of ruminants result in higher total TFAs with trans-18:1 isomers other than vaccenic acid, and many CFAs other than rumenic acid. The defi nition of TFA adopted by several countries does not distinguish among isolated TFAs of concern and ignores CFAs that should be included in total TFA due to their negative health effects. Accurate TFA defi nition establishment and nutritional assessment of individual TFA isomers is needed for labeling purposes. Also required are adoptions of analytical methods to resolve all TFA isomers. This information can then be used to construct a database and as a basis for meaningful recommendations. Practical applications: Areas that require further investigations have been identifi ed: 1) Establish a uniform TFA nomenclature based on chemical structure 2) Standardize, assess and normalize appropriate method-ologies for the analysis of TFAs 3) Synthesize pure reference standards for TFA identifi cation 4) Report individual TFA levels with different biological activities rather than total TFA content 5) Assess the nutritional characteristics of individual TFAs independent of their origin 6) Develop strategies to increase the content of desirable TFA isomers in ruminants 7) Identify potential bioactive trans metabolites produced from PUFAs in ruminants 8) Develop labeling regulations based on specifi c chemical structures and physiological effects regardless of their origin 9) Construct an accurate database complemented with spe-cifi c surveys of ruminant product FA composition that can be accessed by regulatory agencies to make appropriate TFA recommendations. The fi nal version of this Highlight Article was not available in time for inclusion in this special issue. For this reason only the abstract and graphical abstract are presented here. The full-text can be accessed online via the permanent link http://dx.