Rachael Sondeno M.S. Genetics 2006 Major Professor: Dr. Alison Van Eenennaam Department: Animal Science Phone: (530)754-4856 (Lab)  FAX:     (530)752-0175 E-mail: rssondeno@ucdavis.edu

Education: 

B.S., Biological Sciences, CSU Stanislaus, Turlock, CA 2003
M.S., Genetics, UC Davis CA 2006

Project: 

Transgenic modification of milk triglyceride structure

Evidence is accumulating that, in addition to the overall fatty acid profile, the triacylglyceride structure and species composition are of importance when considering the nutritional effects of dietary fat. The first step of triacylglyceride biosynthesis is the acylation of glycerol 3-phosphate at the sn-1 position by glycerol 3-phosphate acyl transferase (GPAT) to form lysophosphatidic acid. Lysophosphatidic acid acyltransferase (LPAAT), also known as 1-acyl sn-glycerol-3-phosphate acyltransferase, catalyzes the acylation of lysophosphatidic acid at the sn-2 position to form phosphatidic acid. This product is then dephosphorylated to form diacylglycerol, which is acylated at the sn-3 position by diacylglycerol acyltransferase (DGAT) to form triacylglyceride . Studies carried out on the acyl chain specificities of acyl transferases show that GPAT and DGAT are flexible in their use of acyl CoA substrates, whilst LPAAT is highly selective. This means that the composition of acyl groups at positions sn-1 and sn-3 is largely determined by acyl CoA pool sizes whilst sn-2 occupancy is governed by the acyl chain specificity of the LPAAT. The mammary LPAAT is a prime target for the alteration of milk fat TG composition at the sn-2 position. We are interested in investigating the acyl-chain specificity of the LPAAT enzyme from different species with the aim of increasing the proportion of the healthful unsaturated fatty acids in the sn-2 position of milk fat.