Transgene flow in Mexican maize revisited: Socio‐biological analysis across two contrasting farmer communities and seed management systems

The flow of transgenes into landraces and wild relatives is an important biosafety concern. The case of transgene flow into local maize varieties in Mexico (the center of origin of maize) has been intensively debated over the past 15 years, including legal, political, and environmental disputes fanned by the existence of a significant scientific controversy over the methods used for the detection of transgenes. The use of diverse approaches and a lack of harmonized methods specific to the detection and monitoring of transgenes in landraces have generated both positive and negative results regarding contamination of Mexican maize with genetically modified material over the years. In this paper, we revisit the case of transgene contamination in Mexican maize and present a novel research approach based on socio‐biological analysis of contrasting communities and seed management systems. Two communities were used to investigate how different social and biological factors can affect transgene flow and impact transgene spread in Mexico. Our results show the presence of transgenes in one community and thus support the position that transgenes are highly likely to be present in Mexican maize landraces. However, our work also demonstrates that the extent and frequency with which transgenes can be found will significantly depend on the societal characteristics and seed management systems of the local communities. Therefore, we argue that future analysis of transgene presence should include social research on the seed management practices in the sampling area so that more robust and comprehensive understandings and conclusions can be drawn.     

Hydrolysis of peptidoglycan is modulated by amidation of meso‐diaminopimelic acid and Mg2+ in Bacillus subtilis

The ability of excess Mg²⁺ to compensate the absence of cell wall related genes in Bacillus subtilis has been known for a long time, but the mechanism has remained obscure. Here, we show that the rigidity of wild‐type cells remains unaffected with excess Mg²⁺, but the proportion of amidated meso‐diaminopimelic (mDAP) acid in their peptidoglycan (PG) is significantly reduced. We identify the amidotransferase AsnB as responsible for mDAP amidation and show that the gene encoding it is essential without added Mg²⁺. Growth without excess Mg²⁺ causes ΔasnB mutant cells to deform and ultimately lyse. In cell regions with deformations, PG insertion is orderly and indistinguishable from the wild‐type. However, PG degradation is unevenly distributed along the sidewalls. Furthermore, ΔasnB mutant cells exhibit increased sensitivity to antibiotics targeting the cell wall. These results suggest that absence of amidated mDAP causes a lethal deregulation of PG hydrolysis that can be inhibited by increased levels of Mg²⁺. Consistently, we find that Mg²⁺ inhibits autolysis of wild‐type cells. We suggest that Mg²⁺ helps to maintain the balance between PG synthesis and hydrolysis in cell wall mutants where this balance is perturbed in favor of increased degradation.     

The EMBL Nucleotide Sequence Database

The EMBL Nucleotide Sequence Database (aka EMBL-Bank; http://www.ebi.ac.uk/embl/) incorporates, organises and distributes nucleotide sequences from all available public sources. EMBL-Bank is located and maintained at the European Bioinformatics Institute (EBI) near Cambridge, UK. In an international collaboration with DDBJ (Japan) and GenBank (USA), data are exchanged amongst the collaborating databases on a daily basis. Major contributors to the EMBL database are individual scientists and genome project groups. Webin is the preferred web-based submission system for individual submitters, whilst automatic procedures allow incorporation of sequence data from large-scale genome sequencing centres and from the European Patent Office (EPO). Database releases are produced quarterly. Network services allow free access to the most up-to-date data collection via FTP, email and World Wide Web interfaces. EBI’s Sequence Retrieval System (SRS), a network browser for databanks in molecular biology, integrates and links the main nucleotide and protein databases plus many other specialized databases. For sequence similarity searching, a variety of tools (e.g. Blitz, Fasta, BLAST) are available which allow external users to compare their own sequences against the latest data in the EMBL Nucleotide Sequence Database and SWISS-PROT. All resources can be accessed via the EBI home page at http://www.ebi.ac.uk.     

Down-regulation of IL-2 receptor α (CD25) characterizes human γδ-T cells rendered resistant to apoptosis after CD2 engagement in the presence of IL-12

We recently identified a CD2-mediated, IL-12-dependent signaling pathway that inhibits apoptosis in mitogen-stimulated human gammadelta-T cells. Here we show that gammadelta-T cells which acquire resistance to mitogen-induced apoptosis upregulate IL-12 receptor beta 1 subunit (IL-12Rbeta1); in contrast, gammadelta-T cells which remain sensitive to mitogen-induced apoptosis fail to express IL-12Rbeta1. Next we show that gammadelta-T cells which are rendered resistant to mitogen-induced apoptosis attenuate their expression of the IL-2 receptor alpha chain (IL-2Ralpha/CD25), this in part accounting for their acquired resistance to IL-2-induced death. In contrast, apoptosis-sensitive gammadelta-T cells are shown to persist in their expression of IL-2Ralpha/CD25, thus remaining sensitive to IL-2-induced death. Moreover, we show that apoptosis-resistant, but not apoptosis-sensitive, gammadelta-T cells display an enhanced responsiveness to IL-15, a finding in keeping with the known function of IL-15 as a growth and survival factor. Finally, we present evidence to suggest that this differential responsiveness to IL-15 occurs in part by the increased expression of the IL-15Ralpha chain on apoptosis-resistant gammadelta-T cells, compared to apoptosis-sensitive gammadelta-T cells. The biological and clinical implications of these findings are discussed.     

Ability of the Actiwatch Accelerometer to Predict Free‐Living Energy Expenditure in Young Children

Objective: To determine whether activity counts obtained with the Actiwatch monitor are associated with total expenditure and body composition in young children. Research Methods and Procedures: Actiwatch activity monitors were tested in 29 children 4 to 6 years old under field conditions over eight days. Total energy expenditure (TEE) was assessed with the doubly labeled water (DLW) technique. Correlation analyses were used to identify variables related to energy expenditure and percentage body fat. Multiple linear regression analyses were used to examine the variance in TEE and percentage body fat explained by activity counts after adjusting for relevant covariates. Results: Both average total daily activity counts (658, 816 ± 201, 657) and the pattern of activity were highly variable among subjects. TEE was significantly related to lean body mass (r = 0.45) and age (r = 0.48; p < 0.05 for both). Activity counts alone were not associated with TEE. In multiple linear regression analyses, TEE was independently associated with only lean body mass. Percentage fat mass was independently associated with body weight, being a girl, and being white, but not with average total activity counts. Discussion: Activity counts obtained with the Actiwatch under free‐living conditions do not reflect TEE in 4‐ to 6‐year‐old children and are not correlated with percentage fat mass. Therefore, average total activity counts obtained with the Actiwatch may be of limited value in identifying children at risk for becoming obese.     

1alpha,25-Dihydroxyvitamin D3-induced monocyte antimycobacterial activity is regulated by phosphatidylinositol 3-kinase and mediated by the NADPH-dependent phagocyte oxidase.

We investigated the basis for the induction of monocyte antimycobacterial activity by 1alpha,25-dihydroxyvitamin D(3) (D(3)). As expected, incubation of Mycobacterium tuberculosis-infected THP-1 cells or human peripheral blood, monocyte-derived macrophages with hormone resulted in the induction of antimycobacterial activity. This effect was significantly abrogated by pretreatment of cells with either of the phosphatidylinositol 3-kinase (PI 3-K) inhibitors, wortmannin or LY294002, or with antisense oligonucleotides to the p110 subunit of PI 3-Kalpha. Cells infected with M. tuberculosis alone or incubated with D(3) alone produced little or undetectable amounts of superoxide anion (O(2)). In contrast, exposure of M. tuberculosis-infected cells to D(3) led to significant production of O(2), and this response was eliminated by either wortmannin, LY294002, or p110 antisense oligonucleotides. As was observed for PI 3-K inactivation, the reactive oxygen intermediate scavenger, 4-hydroxy-TEMPO, and degradative enzymes, polyethylene glycol coupled to either superoxide dismutase or catalase, also abrogated D(3)-induced antimycobacterial activity. Superoxide production by THP-1 cells in response to D(3) required prior infection with live M. tuberculosis, since exposure of cells to either killed M. tuberculosis or latex beads did not prime for an oxidative burst in response to subsequent hormone treatment. Consistent with these findings, redistribution of the cytosolic oxidase components p47(phox) and p67(phox) to the membrane fraction was observed in cells incubated with live M. tuberculosis and D(3) but not in response to combined treatment with heat-killed M. tuberculosis followed by D(3). Redistribution of p47(phox) and p67(phox) to the membrane fraction in response to live M. tuberculosis and D(3) was also abrogated under conditions where PI 3-K was inactivated. Taken together, these results indicate that D(3)-induced, human monocyte antimycobacterial activity is regulated by PI 3-K and mediated by the NADPH-dependent phagocyte oxidase.     

Beauveria bassiana as a pathogen of the Mexican fruit fly (Diptera: Tephritidae) under laboratory conditions

Bioassays were carried out under controlled conditions (27 +/- 2 degrees C, 80 +/- 5% RH, and a photoperiod of 12:12 [L:D] h) to evaluate the effect of eight strains of the entomopathogenic fungus Beauveria bassiana upon larvae, pupae, and adult females of the Mexican fruit fly, Anastrepha ludens (Loew). Mortality of the immature stages was low, 2-8% in larvae and 0% in pupae. However, very high levels of mortality were obtained for adult flies, with values of 100, 98, and 98% for the strains Bb16, Bb24, and Bb26, respectively. LC50 values for these three strains ranged from 3.12 x 10(6) to 9.07 x 10(6) conidia/ml. Lethal time 50 (LT50) was 2.8, 3.7, and 4.2 d for Bb16, Bb26, and Bb24 strains, respectively, with an average LT50 of 4.4 d across all strains. The fungal mycelium emerged through the soft parts of the exoskeleton, such as the wing bases, mouth, intersegmental regions of the legs, and membranous regions of the abdomen, coxae, and neck. Maximum percentage sporulation ranged from 66.4 to 74.7% for the three most virulent strains.     

Effect of decoyinine on peptidoglycan synthesis and turnover in Bacillus subtilis.

The sporulation of Bacillus subtilis can be induced in the presence of amino acids and glucose by partially depriving the cells of guanine nucleotides. This can be achieved, e.g., by the addition of decoyinine, a specific inhibitor of GMP synthetase. To determine the effect of this and other inhibitors on cell wall synthesis, we measured in their presence the incorporation of acetylglucosamine into acid-precipitable material. The rate of wall synthesis decreased by 50% within 5 min after decoyinine addition; this decrease was prevented by the presence of guanosine. A comparison with the effects of other inhibitors of cell wall synthesis indicated that decoyinine inhibited the final portion of the cell wall biosynthetic pathway, i.e., after the steps inhibited by bacitracin or vancomycin. Decoyinine addition also prevented cellular autolysis and cell wall turnover. It is not known whether these two effects of decoyinine on cell wall synthesis are causally related.     

CoQ10 supplementation rescues nephrotic syndrome through normalization of H2S oxidation pathway

Nephrotic syndrome (NS), a frequent chronic kidney disease in children and young adults, is the most common phenotype associated with primary coenzyme Q₁₀ (CoQ₁₀) deficiency and is very responsive to CoQ₁₀ supplementation, although the pathomechanism is not clear. Here, using a mouse model of CoQ deficiency-associated NS, we show that long-term oral CoQ₁₀ supplementation prevents kidney failure by rescuing defects of sulfides oxidation and ameliorating oxidative stress, despite only incomplete normalization of kidney CoQ levels and lack of rescue of CoQ-dependent respiratory enzymes activities. Liver and kidney lipidomics, and urine metabolomics analyses, did not show CoQ metabolites. To further demonstrate that sulfides metabolism defects cause oxidative stress in CoQ deficiency, we show that silencing of sulfide quinone oxido-reductase (SQOR) in wild-type HeLa cells leads to similar increases of reactive oxygen species (ROS) observed in HeLa cells depleted of the CoQ biosynthesis regulatory protein COQ8A. While CoQ₁₀ supplementation of COQ8A depleted cells decreases ROS and increases SQOR protein levels, knock-down of SQOR prevents CoQ₁₀ antioxidant effects. We conclude that kidney failure in CoQ deficiency-associated NS is caused by oxidative stress mediated by impaired sulfides oxidation and propose that CoQ supplementation does not significantly increase the kidney pool of CoQ bound to the respiratory supercomplexes, but rather enhances the free pool of CoQ, which stabilizes SQOR protein levels rescuing oxidative stress.