A western route of prehistoric human migration from Africa into the Iberian Peninsula.

Being at the western fringe of Europe, Iberia had a peculiar prehistory and a complex pattern of Neolithization. A few studies, all based on modern populations, reported the presence of DNA of likely African origin in this region, generally concluding it was the result of recent gene flow, probably during the Islamic period. Here, we provide evidence of much older gene flow from Africa to Iberia by sequencing whole genomes from four human remains from northern Portugal and southern Spain dated around 4000 years BP (from the Middle Neolithic to the Bronze Age). We found one of them to carry an unequivocal sub-Saharan mitogenome of most probably West or West-Central African origin, to our knowledge never reported before in prehistoric remains outside Africa. Our analyses of ancient nuclear genomes show small but significant levels of sub-Saharan African affinity in several ancient Iberian samples, which indicates that what we detected was not an occasional individual phenomenon, but an admixture event recognizable at the population level. We interpret this result as evidence of an early migration process from Africa into the Iberian Peninsula through a western route, possibly across the Strait of Gibraltar.

Metabolism of diglycine and triglycine by non-filtering kidneys.

We have studied the metabolism of diglycine and triglycine in the isolated non-filtering rat kidney. Kidneys from adult male Wistar Kyoto rats weighing 250-350 g were perfused with Krebs-Henseleit solution containing either 1 mM diglycine or triglycine. The analysis of the peptide residues and their components was performed using an amino acid microanalyzer utilizing ion exchange chromatography. Diglycine was degraded to a final concentration of 0.09 mM after 120 min (91%); this degradation occurred predominantly during the first hour, with a 56% reduction of the initial concentration. The metabolism of triglycine occurred similarly, with a final concentration of 0.18 mM (82%); during the first hour there was a 67% reduction of the initial concentration of the tripeptide. Both peptides produced glycine in increasing concentrations, but there was a slightly lower recovery of glycine, suggesting its utilization by the kidney as fuel. The hydrolysis of triglycine also produced diglycine, which was also hydrolyzed to glycine. The results of the present study show the existence of functional endothelial or contraluminal membrane peptidases which may be important during parenteral nutrition.

Metabolism of glutathione in isolated non filtering rat kidneys.

The aim of this work was to study the metabolism of glutathione in the isolated non-filtering rat kidney. Kidneys were perfused with Krebs-Henseleit solution containing 1 mM of glutathione. The analysis of the peptide residues and their components was done in an aminoacid microanalyzer. The results showed that glutathione was significantly oxidized to a maximal concentration of 0.06 mM at end of 20 minutes (94%). Oxidized glutathione was formed showing a slight elevation in the first 20 minutes and declining thereafter, being degraded to its constituent amino acids to a final concentration of 0.05 mM (5%). The tripeptide produced glutamic acid, glycine and cysteine in increasing concentrations. The hydrolysis of glutathione allowed us to believe that gamma glutamyl transpeptidase, among other enzymes is present in the counterluminal membranes of the rat kidney contributing to the handling of glutathione. Our results open new ways to the study of glutathione metabolism.

Metabolism of diglycine and triglycine by non-filtering kidneys

We have studied the metabolism of diglycine and triglycine in the isolated non-filtering rat kidney. Kidneys from adult male Wistar Kyoto rats weighing 250-350 g were perfused with Krebs-Henseleit solution containing either 1 mM diglycine or triglycine. The analysis of the peptide residues and their components was performed using an amino acid microanalyzer utilizing ion exchange chromatography. Diglycine was degraded to a final concentration of 0.09 mM after 120 min (91 per cent); this degradation occurred predominantly during the first hour, with a 56 per cent reduction of the initial concentration. The metabolism of triglycine occurred similarly, with a final concentration of 0.18 mM (82 per cent); during the first hour there was a 67 per cent reduction of the initial concentration of the tripeptide. Both peptides produced glycine in increasing concentrations, but there was a slightly lower recovery of glycine, suggesting its utilization by the kidney as fuel. The hydrolysis of triglycine also produced diglycine, which was also hydrolyzed to glycine. The results of the present study show the existence of functional endothelial or contraluminal membrane peptidases which may be important during parenteral nutrition.