162 research outputs found

    Mitochondrial DNA insertions into the nuclear chromosomes of the maize Mo17 inbred line [abstract]

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    Abstract only availableMitochondria contain their own DNA separate from the nucleus; however, most of their genes have been transferred to the nucleus over evolutionary time. The lateral transfer of DNA from the mitochondria to the nucleus appears to be a continuing process and is more frequent in plants than in animals. Our laboratory has documented extensive variation in the nuclear-mitochondrial sequences (NUMTs) among maize inbred lines using total mitochondrial DNA (mtDNA) as probes onto mitotic metaphase chromosomes, a technique known as fluorescence in situ hybridization (FISH). The mitochondrial genome has been cloned into 20 cosmids, which were used to examine the insertions of individual segments. The focus of the current study was to use FISH with the 20 individual mtDNA-containing cosmids to locate mtDNA within the nuclear chromosomes of the Mo17 inbred line of maize and to compare these locations with those of the B73 line. We studied Mo17 because this line and its derivatives are used in crosses with B73-derived lines to create the most commonly used corn hybrids. Fifteen NUMTs had been detected on the Mo17 chromosomes using a mixture of 19 mtDNA-containing cosmids. However, only nine of the 15 NUMTs were seen when applying individual mtDNA-containing cosmids, suggesting that the portions of nuclear DNA corresponding to the individual mtDNA-containing cosmids were too small to be detected until many cosmids were combined. A large NUMT was previously detected on the long arm of chromosome 9 by 14 of the 20 individually tested cosmids in the B73 inbred line. However, a NUMT present at the same site in Mo17 was detected by only 2 of the 20 cosmids (5 and 20). This suggests that the major insertion in B73 is recent and that it may have inserted by homologous recombination

    A National Strategy for the Conservation of Native Freshwater Mollusks

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    In 1998, a strategy document outlining the most pressing issues facing the conservation of freshwater mussels was published (NNMCC 1998). Beginning in 2011, the Freshwater Mollusk Conservation Society began updating that strategy, including broadening the scope to include freshwater snails. Although both strategy documents contained 10 issues that were deemed priorities for mollusk conservation, the identity of these issues has changed. For example, some issues (e.g., controlling dreissenid mussels, technology to propagate and reintroduce mussels, techniques to translocate adult mussels) were identified in the 1998 strategy, but are less prominent in the revised strategy, due to changing priorities and progress that has been made on these issues. In contrast, some issues (e.g., biology, ecology, habitat, funding) remain prominent concerns facing mollusk conservation in both strategies. In addition, the revised strategy contains a few issues (e.g., newly emerging stressors, education and training of the next generation of resource managers) that were not explicitly present in the 1998 strategy. The revised strategy states that to effectively conserve freshwater mollusks, we need to (1) increase knowledge of their distribution and taxonomy at multiple scales; (2) address the impacts of past, ongoing, and newly emerging stressors; (3) understand and conserve the quantity and quality of suitable habitat; (4) understand their ecology at the individual, population, and community levels; (5) restore abundant and diverse populations until they are self-sustaining; (6) identify the ecosystem services provided by mollusks and their habitats; (7) strengthen advocacy for mollusks and their habitats; (8) educate and train the conservation community and future generations of resource managers and researchers; (9) seek long-term funding to support conservation efforts; and (10) coordinate development of an updated and revised strategy every 15 years. Collectively addressing these issues should strengthen conservation efforts for North American freshwater mollusks

    Measurement of the lateral distribution function of UHECR air showers with the Pierre Auger Observatory

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    We describe how the lateral distribution function (LDF) is measured using the large sample of events recorded with the surface detector (SD) array and with a small sample observed with the fluorescence detectors (FD). For hybrid events, in which SD and FD measurements of the same shower are available, the core position is much better constrained than for SD-onlyevents, thus providing an important cross-check on the LDF determined from SD measurements alone. [Segmento extraĂ­do de la ponencia]Facultad de Ciencias Exacta

    New genetic loci implicated in fasting glucose homeostasis and their impact on type 2 diabetes risk.

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    Levels of circulating glucose are tightly regulated. To identify new loci influencing glycemic traits, we performed meta-analyses of 21 genome-wide association studies informative for fasting glucose, fasting insulin and indices of beta-cell function (HOMA-B) and insulin resistance (HOMA-IR) in up to 46,186 nondiabetic participants. Follow-up of 25 loci in up to 76,558 additional subjects identified 16 loci associated with fasting glucose and HOMA-B and two loci associated with fasting insulin and HOMA-IR. These include nine loci newly associated with fasting glucose (in or near ADCY5, MADD, ADRA2A, CRY2, FADS1, GLIS3, SLC2A2, PROX1 and C2CD4B) and one influencing fasting insulin and HOMA-IR (near IGF1). We also demonstrated association of ADCY5, PROX1, GCK, GCKR and DGKB-TMEM195 with type 2 diabetes. Within these loci, likely biological candidate genes influence signal transduction, cell proliferation, development, glucose-sensing and circadian regulation. Our results demonstrate that genetic studies of glycemic traits can identify type 2 diabetes risk loci, as well as loci containing gene variants that are associated with a modest elevation in glucose levels but are not associated with overt diabetes

    Measurement of the lateral distribution function of UHECR air showers with the Pierre Auger Observatory

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    We describe how the lateral distribution function (LDF) is measured using the large sample of events recorded with the surface detector (SD) array and with a small sample observed with the fluorescence detectors (FD). For hybrid events, in which SD and FD measurements of the same shower are available, the core position is much better constrained than for SD-onlyevents, thus providing an important cross-check on the LDF determined from SD measurements alone. [Segmento extraĂ­do de la ponencia]Facultad de Ciencias Exacta

    Measurement of the cosmic ray spectrum above 4×10184{\times}10^{18} eV using inclined events detected with the Pierre Auger Observatory

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    A measurement of the cosmic-ray spectrum for energies exceeding 4×10184{\times}10^{18} eV is presented, which is based on the analysis of showers with zenith angles greater than 60∘60^{\circ} detected with the Pierre Auger Observatory between 1 January 2004 and 31 December 2013. The measured spectrum confirms a flux suppression at the highest energies. Above 5.3×10185.3{\times}10^{18} eV, the "ankle", the flux can be described by a power law E−γE^{-\gamma} with index Îł=2.70±0.02 (stat)±0.1 (sys)\gamma=2.70 \pm 0.02 \,\text{(stat)} \pm 0.1\,\text{(sys)} followed by a smooth suppression region. For the energy (EsE_\text{s}) at which the spectral flux has fallen to one-half of its extrapolated value in the absence of suppression, we find Es=(5.12±0.25 (stat)−1.2+1.0 (sys))×1019E_\text{s}=(5.12\pm0.25\,\text{(stat)}^{+1.0}_{-1.2}\,\text{(sys)}){\times}10^{19} eV.Comment: Replaced with published version. Added journal reference and DO

    Melanocortin-1 receptor, skin cancer and phenotypic characteristics (M-SKIP) project

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    Background: For complex diseases like cancer, pooled-analysis of individual data represents a powerful tool to investigate the joint contribution of genetic, phenotypic and environmental factors to the development of a disease. Pooled-analysis of epidemiological studies has many advantages over meta-analysis, and preliminary results may be obtained faster and with lower costs than with prospective consortia. Design and methods. Based on our experience with the study design of the Melanocortin-1 receptor (MC1R) gene, SKin cancer and Phenotypic characteristics (M-SKIP) project, we describe the most important steps in planning and conducting a pooled-analysis of genetic epidemiological studies. We then present the statistical analysis plan that we are going to apply, giving particular attention to methods of analysis recently proposed to account for between-study heterogeneity and to explore the joint contribution of genetic, phenotypic and environmental factors in the development of a disease. Within the M-SKIP project, data on 10,959 skin cancer cases and 14,785 controls from 31 international investigators were checked for quality and recoded for standardization. We first proposed to fit the aggregated data with random-effects logistic regression models. However, for the M-SKIP project, a two-stage analysis will be preferred to overcome the problem regarding the availability of different study covariates. The joint contribution of MC1R variants and phenotypic characteristics to skin cancer dev

    Effects of antiplatelet therapy on stroke risk by brain imaging features of intracerebral haemorrhage and cerebral small vessel diseases: subgroup analyses of the RESTART randomised, open-label trial

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    Background Findings from the RESTART trial suggest that starting antiplatelet therapy might reduce the risk of recurrent symptomatic intracerebral haemorrhage compared with avoiding antiplatelet therapy. Brain imaging features of intracerebral haemorrhage and cerebral small vessel diseases (such as cerebral microbleeds) are associated with greater risks of recurrent intracerebral haemorrhage. We did subgroup analyses of the RESTART trial to explore whether these brain imaging features modify the effects of antiplatelet therapy
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