Taurine (2-aminoethanesulfonic acid) is an amino acid-like compound widely distributed in animals and an essential nutrient in some species. Targeted metabolomics of marine and freshwater microalgae combined with medium supplementation identified biosynthetic pathway intermediates and necessary catalytic activities. Genomic analysis was then used to predict the first taurine biosynthetic pathway in these organisms. MRM-based electrospray ionization (ESI) LC-MS/MS analysis demonstrated that taurine is synthesized using a carbon backbone from L-serine combined with sulfur derived from sulfate. Metabolite analysis showed a nonuniform pattern in levels of pathway intermediates that were both species and supplement dependent. While increased culture salinity raised taurine levels modestly in marine alga, taurine levels were strongly induced in a freshwater species implicating taurine as an organic osmolyte. Conservation of the synthetic pathway in algae and metazoans together with a pattern of intermittent distribution in other lineages suggests that it arose early in 0 1 5 ) 2 eukaryotic evolution. Elevated levels of cell-associated taurine in algae could offer a new and biorenewable source of this unusual bioactive compound.

Premise of the Study This investigation establishes the first DNA‐sequence‐based phylogenetic hypothesis of species relationships in the coca family (Erythroxylaceae) and presents its implications for the intrageneric taxonomy and neotropical biogeography of Erythroxylum. We also identify the closest wild relatives and evolutionary relationships of the cultivated coca taxa. Methods We focused our phylogenomic inference on the largest taxonomic section in the genus Erythroxylum (Archerythroxylum O.E.Schulz) using concatenation and gene tree reconciliation methods from hybridization‐based target capture of 427 genes. Key Results We show that neotropical Erythroxylum are monophyletic within the paleotropical lineages, yet Archerythroxylum and all of the other taxonomic sections from which we sampled multiple species lack monophyly. We mapped phytogeographic states onto the tree and found some concordance between these regions and clades. The wild species E. gracilipes and E. cataractarum are most closely related to the cultivated E. coca and E. novogranatense, but relationships within this “coca” clade remain equivocal. Conclusions Our results point to the difficulty of morphology‐based intrageneric classification in this clade and highlight the importance of integrative taxonomy in future systematic revisions. We can confidently identify E. gracilipes and E. cataractarum as the closest wild relatives of the coca taxa, but understanding the domestication history of this crop will require more thorough phylogeographic analysis.

When carbohydrates are fermented by the hyperthermophilic anaerobeThermotoga maritima, molecular hydrogen (H2) is formed in strict proportion to substrate availability. Excretion of the organic acids acetate and lactate provide an additional sink for removal of excess reductant. However, mechanisms controlling energy management of these metabolic pathways are largely unexplored. To investigate this topic, transient gene inactivation was used to block lactate production as a strategy to produce spontaneous mutant cell lines that overproduced H2through mutation of unpredicted genetic targets. Single-crossover homologous chromosomal recombination was used to disrupt lactate dehydrogenase (encoded byldh) with a truncatedldhfused to a kanamycin resistance cassette expressed from a native PgroESLpromoter. Passage of the unstable recombinant resulted in loss of the genetic marker and recovery of evolved cell lines, including strain Tma200. Relative to the wild type, and considering the mass balance of fermentation substrate and products, Tma200 grew more slowly, produced H2at levels above the physiologic limit, and simultaneously consumed less maltose while oxidizing it more efficiently. Whole-genome resequencing indicated that the ABC maltose transporter subunit, encoded bymalK3, had undergone repeated mutation, and high-temperature anaerobic [14C]maltose transport assays demonstrated that the rate of maltose transport was reduced. Transfer of themalK3mutation into a clean genetic background also conferred increased H2production, confirming that the mutant allele was sufficient for increased H2synthesis. These data indicate that a reduced rate of maltose uptake was accompanied by an increase in H2production, changing fermentation efficiency and shifting energy management.IMPORTANCEBiorenewable energy sources are of growing interest to mitigate climate change, but like other commodities with nominal value, require innovation to maximize yields. Energetic considerations constrain production of many biofuels, such as molecular hydrogen (H2) because of the competing needs for cell mass synthesis and metabolite formation. Here we describe cell lines of the extremophileThermotoga maritimathat exceed the physiologic limits for H2formation arising from genetic changes in fermentative metabolism. These cell lines were produced using a novel method called transient gene inactivation combined with adaptive laboratory evolution. Genome resequencing revealed unexpected changes in a maltose transport protein. Reduced rates of sugar uptake were accompanied by lower rates of growth and enhanced productivity of H2.

Interstitial deletions of chromosome 4 have been described rarely and have had variable presentations. We describe the phenotypic characteristics associated with interstitial deletion of the p14-16 region of chromosome 4 in 7 patients with multiple minor anomalies in common, and with mental retardation. A review of published cases of interstitial deletions of the short arm of chromosome 4 is provided. These deletions present a distinct phenotype which is different from that of Wolf-Hirschhorn syndrome.