BackgroundAlthough animal mitochondrial DNA sequences are known to evolve rapidly, their gene arrangements often remain unchanged over long periods of evolutionary time. Therefore, comparisons of mitochondrial genomes may result in significant insights into the evolution both of organisms and of genomes. Mammalian mitochondrial genomes recently published in the GenBank database of NCBI show numerous rearrangements in various regions of the genome, from which it may be inferred that the mammalian mitochondrial genome is more dynamic than expected. However, it is alternatively possible that these are errors of annotation and, if so, are misleading our interpretations. In order to verify these possible errors of annotation, we performed a comparative genomic analysis of mammalian mitochondrial genomes available in the NCBI database.ResultsUsing a combination of bioinformatics methods to carefully examine the mitochondrial gene arrangements in 304 mammalian species, we determined that there are only two sets of gene arrangements, one that is shared by all of the marsupials and another that is shared by all of the monotremes and eutherians, with these two arrangements differing only by the positions of tRNA genes in the region commonly designated as “WANCY” for the genes it comprises. All of the 68 other cases of reported gene rearrangements are errors. We note that there are also numerous errors of impossibly short, incorrect gene annotations, cases where genomes that are reported as complete are actually missing portions of the sequence, and genes that are clearly present but were not annotated in these records.ConclusionsWe judge that the application of simple bioinformatic tools in the verification of gene annotation, particularly for organelle genomes, would be a very useful enhancement for the curation of genome sequences submitted to GenBank.Electronic supplementary materialThe online version of this article (10.1186/s12864-019-5447-1) contains supplementary material, which is available to authorized users.

In this study, we analyzed patterns of combined benzodiazepines and alcohol use among the Spanish general population over the age of 16 years. The study was based on information from the 1997 Spanish National Household Health Survey. A total of 6,396 persons over 16 years of age, a representative sample of noninstitutionalized Spaniards, were surveyed. One percent of the population are consumers of benzodiazepines and daily drinkers of alcohol; fundamentally, these consumers are men, of whom 15.4% drink alcohol at a high level (>50 units/week). Findings show the frequency of concurrent use of benzodiazepines and alcohol by the Spanish population.

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As yet, certain aspects of the Africanization process are not well understood, for example, the reproductive behavior of African and European honeybees and how the first Africanized swarms were formed and spread. Drone congregation areas (DCAs) are the ideal place to study honeybee reproduction under natural conditions since hundreds of drones from various colonies gather together in the same geographical area for mating. In the present study, we assessed the genetic structure of seven drone congregations and four commercial European-derived and Africanized apiaries in southern Brazil, employing seven microsatellite loci for this purpose. We also estimated the number of mother-colonies that drones of a specific DCA originated from. Pairwise comparison failed to reveal any population sub-structuring among the DCAs, thus indicating low mutual genetic differentiation. We also observed high genetic similarity between colonies of commercial apiaries and DCAs, besides a slight contribution from a European-derived apiary to a DCA formed nearby. Africanized DCAs seem to have a somewhat different genetic structure when compared to the European.

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Vertebrate mitochondrial genomes have been extensively studied for genetic and evolutionary purposes, these are normally believed to be extremely conserved, however, different cases of gene rearrangements have been reported. To verify the level of rearrangement and the mitogenome evolution, we performed a comparative genomic analysis of the 2831 vertebrate mitochondrial genomes representing 12 classes available in the NCBI database. Using a combination of bioinformatics methods, we determined there is a high number of errors in the annotation of mitochondrial genes, especially in tRNAs. We determined there is a large variation in the proportion of rearrangements per gene and per taxonomic class, with higher values observed in Actinopteri, Amphibia and Reptilia. We highlight that these are results for currently available vertebrate sequences, so an increase in sequence representativeness in some groups may alter the rearrangement rates, so in a few years it would be interesting to see if these rates are maintained or altered with the new mitogenome sequences. In addition, within each vertebrate class, different patterns in rearrangement proportion with distinct hotspots in the mitochondrial genome were found. We also determined that there are eleven convergence events in gene rearrangement, nine of which are new reports to the scientific community.

The 1993 Spanish National Health Survey data were used to estimate how frequently both medication and alcohol were used among 21084 people over 16 years of age. A total of 47.1% of the population, especially women and an increasingly older section, had taken some kind of medication during the previous fortnight. A total of 9.8% of the population took medication and alcohol together. This was more frequently observed among men than among women, and especially so among the older age groups. These data reveal that concomitant alcohol and medication use is frequent among the Spanish population, and suggest a need to devote much more attention to this potential problem.

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