Genetic characterization, at the mitochondrial and nuclear DNA levels, of five Canary Island dog breeds.

Many studies presenting genetic analysis of dog breeds have been conducted without the inclusion of island dog breeds, although isolation can be one of the main factors in their origin. Here we report the genetic analysis at the nuclear and mitochondrial DNA levels of five Canary Island dog breeds (Canarian Warren Hound, Canary Island Mastiff, Garafiano Shepherd, La Palma Rat-Hunter and El Hierro Wolfhound) to fill this gap and, at the same time, genetically characterize these breeds. We identified 168 alleles in autosomal microsatellites and 16 mitochondrial haplotypes. Observed and expected heterozygosities ranged from 0.556 to 0.783 and from 0.737 to 0.943 respectively. Furthermore, three haplotypes were newly described and exclusive to a particular breed (A17+ in the Canary Island Mastiff; A33+ in the Canarian Warren Hound; Bi in the La Palma Rat-Hunter). The outcome of our analyses also revealed different breed histories consistent with historical documents and hypothetical origin designations. Although mtDNA haplotypes showed poor breed discriminating power, autosomal markers allowed a clear clustering of each single population. We expect that our results, together with further analyses, will help to make the population histories of island dog breeds clearer.

Using mitochondrial DNA to test the hypothesis of a European post-glacial human recolonization from the Franco-Cantabrian refuge.

It has been proposed that the distribution patterns and coalescence ages found in Europeans for mitochondrial DNA (mtDNA) haplogroups V, H1 and H3 are the result of a post-glacial expansion from a Franco-Cantabrian refuge that recolonized central and northern areas. In contrast, in this refined mtDNA study of the Cantabrian Cornice that contributes 413 partial and 9 complete new mtDNA sequences, including a large Basque sample and a sample of Asturians, no experimental evidence was found to support the human refuge-expansion theory. In fact, all measures of gene diversity point to the Cantabrian Cornice in general and the Basques in particular, as less polymorphic for V, H1 and H3 than other southern regions in Iberia or in Central Europe. Genetic distances show the Cantabrian Cornice is a very heterogeneous region with significant local differences. The analysis of several minor subhaplogroups, based on complete sequences, also suggests different focal expansions over a local and peninsular range that did not affect continental Europe. Furthermore, all detected clinal trends show stronger longitudinal than latitudinal profiles. In Northern Iberia, it seems that the highest diversity values for some haplogroups with Mesolithic coalescence ages are centred on the Mediterranean side, including Catalonia and South-eastern France.

Microwave improved Escherichia coli transformation.

AIMS: The calcium chloride chemical transformation of Escherichia coli is still the most widly used cloning method in small laboratories. Therefore, any practicable improvement in its transformation efficiency seems to be of general interest. METHODS AND RESULTS: We found that giving calcium chloride competent cells a 1 min microwave pulse at the lowest power setting (180 W), instead of the classic 1-2 min 42 degrees C heat-shock step, increases the transformation efficiency around threefold (3.3 +/- 0.5). Moreover, when both treatments were given in a 2-min 42 degrees C - 5 min on ice -1 min microwave pulse sequence, an additional improvement of 1.6 was obtained, resulting in an overall increase in efficiency of approximately 5.3-fold compared to classical heat shock. CONCLUSIONS: This transformation method significantly improves the classical heat shock treatment. SIGNIFICANCE AND IMPACT OF THE STUDY: This method might be useful to those laboratories that cannot afford an electroporation apparatus.