In mammals, the PGC-1 transcriptional co-activators are key regulators of energy metabolism, including mitochondrial biogenesis and respiration, which have been implicated in numerous pathogenic conditions including neurodegeneration and cardiomyopathy. Here, we show that overexpression of the Drosophila PGC-1 homolog (dPGC-1/spargel) is sufficient to increase mitochondrial activity. Moreover, tissue-specific overexpression of dPGC-1 in stem and progenitor cells within the digestive tract extends lifespan. Long-lived flies overexpressing dPGC-1 display a delay in the onset of aging-related changes in the intestine, leading to improved tissue homeostasis in old flies. Together, these results demonstrate that dPGC-1 can slow aging both at the level of cellular changes in an individual tissue and also at the organismal level by extending lifespan. Our findings point to the possibility that alterations in PGC-1 activity in high-turnover tissues, such as the intestine, may be an important determinant of longevity in mammals.

Microalgae have presented themselves as a strong candidate to replace diminishing oil reserves as a source of lipids for biofuels. Here we describe successful modifications of terrestrial plant lipid content which increase overall lipid production or shift the balance of lipid production towards lipid varieties more useful for biofuel production. Our discussion ranges from the biosynthetic pathways and rate limiting steps of triacylglycerol formation to enzymes required for the formation of triacylglycerol containing exotic lipids. Secondarily, we discuss techniques for genetic engineering and modification of various microalgae which can be combined with insights gained from research in higher plants to aid in the creation of production strains of microalgae.

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a b s t r a c tAs the industry surrounding microalgae continues to develop, there is a growing need for reliable, ready-to-use technologies for measuring the growth and composition of algal cultures. These can be new technologies or adapted existing technologies presently used for similar applications in other systems. Here we demonstrate the use of an LED fluorometer for the rapid estimation of dry weight, protein, and lipid content from two strains of microalgae. The instrument was successfully used to determine the dry weight of Chlamydomonas reinhardtii (CC-3491) and Scenedesmus dimorphus (UTEX 1237) cultures, at densities up to 1.58 g/L. Soluble protein was also measured using the instrument, and was highly comparable (average within 3%) to results obtained using both the Bradford and Lowry methods. Lastly, neutral lipid accumulation induced by nitrogen starvation was estimated via BODIPY 495/505 fluorescence. The basic methods developed here can easily be applied to any strain of microalgae or cyanobacteria, and demonstrate reliable, cost-effective, single-instrument methods for the determination of several key parameters in the cultivation of photosynthetic microorganisms.