An exception among diatoms: unique organization of genes involved in isoprenoid biosynthesis in Rhizosolenia setigera CCMP 1694.

The marine diatom Rhizosolenia setigera is unique among this group of microalgae given that it is only one of a handful of diatom species that can produce highly branched isoprenoid (HBI) hydrocarbons. In our efforts to determine distinguishing molecular characteristics in R. setigera CCMP 1694 that could help elucidate the underlying mechanisms for its ability to biosynthesize HBIs, we discovered the occurrence of independent genes encoding for two isopentenyl diphosphate isomerases (RsIDI1 and RsIDI2) and one squalene synthase (RsSQS), enzymes that catalyze non-consecutive steps in isoprenoid biosynthesis.

Characterization of marine diatom-infecting virus promoters in the model diatom Phaeodactylum tricornutum.

Viruses are considered key players in phytoplankton population control in oceans. However, mechanisms that control viral gene expression in prominent microalgae such as diatoms remain largely unknown. In this study, potential promoter regions isolated from several marine diatom-infecting viruses (DIVs) were linked to the egfp reporter gene and transformed into the Pennales diatom Phaeodactylum tricornutum.

Light regulation of ascorbic acid biosynthesis in rice via light responsive cis-elements in genes encoding ascorbic acid biosynthetic enzymes.

The ascorbic acid (AsA) content and the mRNA levels of L-galactose-1-phosphate phosphatase (GPPase), and L-galactono-1,4-lactone dehydrogenase (GalLDH) increased by intense light, and decreased in the dark. Moreover, the promoter regions of GPPase and GalLDH contained light responsible cis-elements. These results suggest that in rice, AsA synthesis is regulated by light.

Increase in ascorbate content of transgenic tobacco plants overexpressing the acerola (Malpighia glabra) phosphomannomutase gene.

Phosphomannomutase (PMM; EC 5.4.2.

Formation of unidentified nitrogen in plants: an implication for a novel nitrogen metabolism.

Plants take up inorganic nitrogen and store it unchanged or convert it to organic forms. The nitrogen in such organic compounds is stoichiometrically recoverable by the Kjeldahl method. The sum of inorganic nitrogen and Kjeldahl nitrogen has long been known to equal the total nitrogen in plants.