Evidence for multi-copy Mega-NUMTs in the human genome

The maternal mode of mitochondrial DNA (mtDNA) inheritance is central to human genetics. Recently, evidence for bi-parental inheritance of mtDNA was claimed for individuals of three pedigrees that suffered mitochondrial disorders. We sequenced mtDNA using both direct Sanger and Massively Parallel Sequencing in several tissues of eleven maternally related and other affiliated healthy individuals of a family pedigree and observed mixed mitotypes in eight individuals. Cells without nuclear DNA, i.e. thrombocytes and hair shafts, only showed the mitotype of haplogroup (hg) V. Skin biopsies were prepared to generate ρ° cells void of mtDNA, sequencing of which resulted in a hg U4c1 mitotype. The position of the Mega-NUMT sequence was determined by fluorescence in situ hybridization and two different quantitative PCR assays were used to determine the number of contributing mtDNA copies. Thus, evidence for the presence of repetitive, full mitogenome Mega-NUMTs matching haplogroup U4c1 in various tissues of eight maternally related individuals was provided. Multi-copy Mega-NUMTs mimic mixtures of mtDNA that cannot be experimentally avoided and thus may appear in diverse fields of mtDNA research and diagnostics. We demonstrate that hair shaft mtDNA sequencing provides a simple but reliable approach to exclude NUMTs as source of misleading results.     

Flora des Etna

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Flora des Etna

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Flora des Etna

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Flora des Etna

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No impact of neonicotinoids on male solitary bees Osmia cornuta under semi‐field conditions

The ubiquitous use of agrochemicals is one driver for the ongoing loss of insect biomass and diversity. Data show that field‐realistic concentrations of neonicotinoid insecticides can negatively affect both population density and the fitness of solitary bees. However, the underlying mechanisms for these effects remain poorly understood. Here, using an established semi‐field experimental set‐up and Osmia cornuta as a solitary bee model, we examined the effects of field‐realistic concentrations of a common neonicotinoid insecticide (clothianidin) on male larvae and adults. Besides measuring lethal (i.e., overwintering success and adult survival) and sub‐lethal endpoints (i.e., emergence mass and emergence duration), we examined, for the first time, potential effects on the male reproductive physiology of a solitary bee (i.e., sperm quantity and viability). The data revealed no significant effects on any of the measured response variables. This may be due to the low degree of clothianidin exposure (0.56 ng g^?1) and/or the apparent low susceptibility of solitary bee larvae to neonicotinoids. Furthermore, it is conceivable that ideal foraging conditions, combined with optimal weather and lack of other environmental stressors, may have improved the ability of bees to cope with the insecticide. To reliably assess and understand the environmental hazards of agrochemicals, a holistic approach, including laboratory, semi‐field and field data is required. Knowledge of underlying mechanisms will help to mitigate the current global declines of insect populations.     

Flora des Etna

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Flora des Etna

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Flora des Etna

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Flora des Etna

Ohne Zusammenfassung