Native American population history is reexamined using a large data set of pre-Columbian mitochondrial genomes.

SummaryRNA editing changes the sequence of many transcripts in plant organelles, but little is known about the molecular mechanisms determining the specificity of the process. In this study, we have characterized CLB19 (also known as PDE247), a gene that is required for editing of two distinct chloroplast transcripts, rpoA and clpP. Loss-of-function clb19 mutants present a yellow phenotype with impaired chloroplast development and early seedling lethality under greenhouse conditions. Transcript patterns are profoundly affected in the mutant plants, with a pattern entirely consistent with a defect in activity of the plastid-encoded RNA polymerase. CLB19 encodes a pentatricopeptide repeat protein similar to the editing specificity factors CRR4 and CRR21, but, unlike them, is implicated in editing of two target sites.

The discovery of the 2-C-methyl-d-erythritol-4-phosphate pathway for the biosynthesis of isoprenoids raises the important question of the nature and regulation of the enzymes involved in this pathway. CLA1, a gene previously isolated from Arabidopsis, encodes the first enzyme of the 2-C-methyl-d-erythritol-4-phosphate pathway, 1-deoxy-d-xylulose-5-phosphate synthase. We demonstrate this enzyme activity by complementation of the cla1-1 mutant phenotype and by direct enzymatic assays. Based on mRNA and protein expression patterns this enzyme is expressed mainly in developing photosynthetic and non-photosynthetic tissues. The ␤-glucuronidase expression pattern driven from the CLA1 gene regulatory region supports the northern and protein data while also showing that this gene has some level of expression in most tissues of the plant. A mutation in the CLA1 gene interferes with the normal development of chloroplasts and etioplasts, but does not seem to affect amyloplast structure. Microscopic analysis also shows a pleiotropic effect of the CLA1 gene mutation in mesophyll tissue formation.In higher plants isoprenoids are derived from isopentenyl diphosphate (IPP) and synthesized in at least two different compartments, the cytoplasm and the chloroplast. For a long time it was assumed that IPP was synthesized exclusively by the mevalonate pathway in all organisms (Spurgeon and Porter, 1981; Goldstein and Brown, 1990). However, independent studies have demonstrated that in eubacteria, green algae, and plants, IPP is also synthesized by a non-mevalonate pathway designated as the 2-Cmethyl-d-erythritol-4-P (MEP) pathway (for review, see Rohmer, 1998Rohmer, , 1999Lichtenthaler, 1999). Thus in plants cytosolic IPP is synthesized by the mevalonate pathway and plastidic IPP is synthesized by the MEP pathway (Lichtenthaler, 1999). In the MEP pathway IPP is synthesized from pyruvate and glyceraldehyde-3-P via novel intermediates (Rohmer et al

In order to identify nuclear genes required for early chloroplast development, a collection of photosynthetic pigment mutants of Arabidopsis was assembled and screened for lines with extremely low levels of chlorophyll. Nine chloroplast biogenesis (clb) mutants that affect proplastid growth and thylakoid membrane formation and result in an albino seedling phenotype were identified. These mutations identify six new genes as well as a novel allele of cla1. clb mutants have less than 2% of wild-type chlorophyll levels, and little or no expression of nuclear and plastid-encoded genes required for chloroplast development and function. In all but one mutant, proplastids do not differentiate enough to form elongated stroma thylakoid membranes. Analysis of mutants during embryogenesis allows differentiation between CLB genes that act noncell autonomously, where partial maternal complementation of chloroplast development is observed in embryos, and those that act cell autonomously, where complementation during embryogenesis is not observed. Molecular characterization of the noncell autonomous clb4 mutant established that the CLB4 gene encodes for hydroxy-2-methyl-2-(E)-butenyl 4-diphosphate synthase (HDS), the next to the last enzyme of the methylerythritol 4-phosphate (MEP) pathway for the synthesis of plastidic isoprenoids. The noncell autonomous nature of the clb4 mutant suggests that products of the MEP pathway can travel between tissues, and provides in vivo evidence that some movement of MEP intermediates exists from the cytoplasm to the plastid. The isolation and characterization of clb mutants represents the first systematic study of genes required for early chloroplast development in Arabidopsis.

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To determine the surgical time, suture time, presence of postoperative dyspareunia, and complications that occur after closing the vaginal cuff with a barbed suture compared with conventional suture. Design: A randomized, controlled clinical trial (Canadian Task Force classification I). Setting: Private gynecologic clinic in Medellin, Colombia. Patients: One hundred fifty women who underwent total laparoscopic hysterectomy for benign pathology. Interventions: The patients underwent total laparoscopic hysterectomy with intracorporeal closure of the vaginal cuff and were randomized to 2 groups, 1 using a barbed suture (V-Loc 90; Medtronic/Covidien, New Haven, CT) and 1 using polyglactin 910 (coated Vicryl suture; Ethicon/Johnson & Johnson, New Brunswick, NJ). Measurements and Main Results: The total operative time, closing time of the vaginal vault, presence of complications in the cuff, and incidence of postoperative dyspareunia were recorded. The patients were evaluated at a postoperative office visit 2 weeks after the procedure and by telephone interview at 24 weeks. Seventy-five patients were included in the barbed suture group and 75 patients in the polyglactin 910 group. The average time to complete the suture of the vaginal cuff was 12.01 minutes (§ 5.37 standard deviation) for the barbed suture group versus 13.49 minutes (§ 6.48) in the polyglactin 910 group (95% confidence interval, −.44 to 3.4; p = .130). Blood loss was 31.56 § 22.93 mL in the barbed suture group versus 30.82 § 21.75 mL in the polyglactin 910 group (95% confidence interval, −7.95 to 6.47; p = .840). The frequency of postoperative events such as hematoma, cellulitis, cuff dehiscence, fever, emergency consultation, and hospitalization was not statistically significant between groups. No statistically significant difference was found regarding deep dyspareunia at 24 postoperative weeks. Conclusion: No differences were found in surgical time or frequency of adverse events when comparing patients after vaginal cuff closure with barbed suture versus polyglactin 910.

The use of recycled aggregates in structural concrete production has the inconvenience of increasing the fluid transport properties, such as porosity, sorptivity, and permeability, which reduces the resistance against penetration of environmental loads such as carbon dioxide and chloride ion. In this paper, behavior of ten concrete mixtures with different percentages of coarse aggregate replacement was studied. The recycled material was recovered by crushing of concrete rubble and had high absorption values. The results showed that it is possible to achieve good resistance to carbonation and chloride penetration with up to 50% replacement of recycled coarse aggregate for 0.5 water/cement ratio. Finally, new indexes for porosity and sorptivity were proposed to assess the quality of concrete.

Carbon footprint is one of the most widely used tools for assessing the environmental impacts of the production and utilization of concrete as well as of the components derived from it, representing the amount of carbon dioxide and other greenhouse gases associated with this product, expressed as CO2 equivalents. In this paper, carbon footprint was used to compare the environmental performance in the production phase of a concrete made with both recycled and crushed virgin limestone aggregates, using a life cycle analysis methodological approach. Research outcomes revealed, as expected, that carbon dioxide equivalent emissions decreased slightly as the use of recycled aggregates increased. Emissions for concrete with 0.5 w/c were between 347 and 351 kg of CO2-e/m3. It was also corroborated that cement is the material with the greatest influence on greenhouse gas emission generation in the concrete’s production phase, regardless of the use of recycled or virgin aggregates.