Publications

Export 2 results:
Sort by: Author [ Title  (Asc)] Type Year
Filters: First Letter Of Title is D  [Clear All Filters]
A B C [D] E F G H I J K L M N O P Q R S T U V W X Y Z   [Show ALL]
D
Wang, Q., Dooner HK.  2012.  Dynamic evolution of bz orthologous regions in the Andropogoneae and other grasses.. The Plant journal : for cell and molecular biology. 72(2):212-21. Abstract
Genome structure exhibits remarkable plasticity within Zea mays. To examine how haplotype structure has evolved within the Andropogoneae tribe, we have analyzed the bz gene-rich region of maize (Zea mays), the Zea teosintes mays ssp. mexicana, luxurians and diploperennis, Tripsacum dactyloides, Coix lacryma-jobi and Sorghum propinquum. We sequenced and annotated BAC clones from these species and re-annotated the orthologous Sorghum bicolor region. Gene colinearity in the region is well conserved within the genus Zea. However, the orthologous regions of Coix and Sorghum exhibited several micro-rearrangements relative to Zea, including addition, truncation and deletion of genes. The stc1 gene, involved in the production of a terpenoid insect defense signal, is evolving particularly fast, and its progressive disappearance from some species is occurring by microhomology-mediated recombination. LTR retrotransposons are the main contributors to the dynamic evolution of the bz region. Common transposon insertion sites occur among haplotypes from different Zea mays sub-species, but not outside the species. As in Zea, different patterns of interspersion between genes and retrotransposons are observed in Sorghum. We estimate that the mean divergence times between maize and Tripsacum, Coix and Sorghum are 8.5, 12.1 and 12.4 million years ago, respectively, and that between Coix and Sorghum is 9.3 million years ago. A comparison of the bz orthologous regions of Zea, Sorghum and Coix with those of Brachypodium, Setaria and Oryza allows us to infer how the region has evolved by addition and deletion of genes in the approximately 50 million years since these genera diverged from a common progenitor.
Burrows, EH, Bennette NB, Carrieri D, Dixon JL, Brinker A, Frada M, Bakdassabim S N, Falkowski PG, Dismukes GC.  2012.  Dynamics of Lipid Biosynthesis and Redistribution in the Marine Diatom Phaeodactylum tricornutum under Nitrate Deprivation. Bioenerg. Res. 5:876-885. Abstract
One approach to achieve continuous overproduction of lipids in microalgal “cell factories” relies upon depletion or removal of nutrients that act as competing electron sinks (e.g., nitrate and sulfate). However, this strategy can only be effective for bioenergy applications if lipid is synthesized primarily de novo (from CO2 fixation) rather than from the breakdown and interconversion of essential cellular components. In the marine diatom, Phaeodactylum tricornutum, it was determined, using 13C-bicarbonate, that cell growth in nitrate (NO 3 − )-deprived cultures resulted predominantly in de novo lipid synthesis (60 % over 3 days), and this new lipid consisted primarily of triacylglycerides (TAGs). Nearly complete preservation of 12C occurred in all previously existing TAGs in NO 3 − -deprived cultures and thus, further TAG accumulation would not be expected from inhibition of TAG lipolysis. In contrast, both high turnover and depletion of membrane lipids, phosphatidylcholines (PCs), were observed in NO 3 − -deprived cultures (both the headgroups and fatty acid chains), while less turnover was observed in NO 3 − replete cultures. Liquid chromatography-tandem mass spectrometry mass spectra and 13C labeling patterns of PC headgroups provided insight into lipid synthesis in marine diatoms, including suggestion of an internal pool of glycine betaine that feeds choline synthesis. It was also observed that 16C fatty acid chains incorporated into TAGs and PCs contained an average of 14 13C carbons, indicating substantial incorporation of 13C-bicarbonate into fatty acid chains under both nutrient states.