Complex tasks force hand laterality and technological behaviour in naturalistically housed chimpanzees: inferences in hominin evolution.

Clear hand laterality patterns in humans are widely accepted. However, humans only elicit a significant hand laterality pattern when performing complementary role differentiation (CRD) tasks. Meanwhile, hand laterality in chimpanzees is weaker and controversial. Here we have reevaluated our results on hand laterality in chimpanzees housed in naturalistic environments at Fundació Mona (Spain) and Chimfunshi Wild Orphanage (Zambia). Our results show that the difference between hand laterality in humans and chimpanzees is not as great as once thought. Furthermore, we found a link between hand laterality and task complexity and also an even more interesting connection: CRD tasks elicited not only the hand laterality but also the use of tools. This paper aims to turn attention to the importance of this threefold connection in human evolution: the link between CRD tasks, hand laterality, and tool use, which has important evolutionary implications that may explain the development of complex behaviour in early hominins.

Low fatty acid unsaturation: a mechanism for lowered lipoperoxidative modification of tissue proteins in mammalian species with long life spans.

Carbonyl compounds generated by the nonenzymatic oxidation of polyunsaturated fatty acids react with nucleophilic groups in proteins, leading to their modification. It has not been tested whether fatty acid unsaturation is related to steady-state levels of lipoxidation-derived protein modification in vivo. A low fatty acid unsaturation, hence a low protein lipoxidation, in tissues of longevous animals would be consistent with the free radical theory of aging, because membrane lipids increase their sensitivity to oxidative damage as a function of their degree of unsaturation. To evaluate the relationship between fatty acid composition, protein lipoxidation, and maximum life span (MLSP), we analyzed liver fatty acids and proteins from seven mammalian species, ranging in MLSP from 3.5 to 46 years. The results show that the peroxidizability index of fatty acids and the sensitivity to in vitro lipid peroxidation are negatively correlated with the MLSP. Based on gas chromatography and mass spectroscopy analyses, liver proteins of all these species contain malondialdehyde-lysine and Nepsilon-carboxymethyllysine adducts, two biomarkers of protein lipoxidation. The steady-state levels of malondialdehyde-lysine and Nepsilon-carboxymethyl lysine are directly related to the peroxidizability index and inversely related to the MLSP. We propose that a low degree of fatty acid unsaturation may have been selected in longevous mammals to protect their tissue lipids and proteins against oxidative damage while maintaining an appropriate environment for membrane function.

Chromatographic evidence for Amadori product formation in rat liver aminophospholipids.

This work presents data which indicates the presence of Amadori product derived from Maillard reaction in aminophospholipids. The presence of 5-HMF, a stable derivative of acid-treated Amadori product, in the phospholipidic fraction from cell membranes was established by HPLC-UV and subsequent GC/MS analysis. The assay for 5-HMF in rat liver phospholipid revealed the presence of this molecule in membrane phospholipids of euglycemic rats, and showed increased glycation levels in membrane phospholipids from streptozotocin-induced diabetic rats (p < 0.001). This gives a new insight to cell membrane physiology and physiopathology.

Comparison of three methods of determining MICs for filamentous fungi using different end point criteria and incubation periods.

Three different methods were used to determine the in vitro activities of amphotericin B, ketoconazole, itraconazole, and flucytosine against 30 isolates of different genera of filamentous fungi. MICs were determined visually, with or without agitation, and spectrophotometrically by using a broth microdilution method. For amphotericin B, there was one end point reading criterion (the minimum concentration of antifungal that inhibited 100% of growth), but for azoles and flucytosine there were two (the minimum concentrations that inhibited 50 and 75% of fungal growth, respectively) after 48 and 72 h of incubation. All tests were performed in triplicate. An intraclass correlation coefficient (ICC) was used to evaluate the reproducibility of each of the methods and the correlation among them. The reproducibility of the three methods was very high (ICC of 0.808 to 0.992), particularly in the case of azoles and flucytosine. In general, the degree of reproducibility was highest for azoles and amphotericin B after 72 h of incubation and for flucytosine after 48 h of incubation. The degree of correlation among the three methods was very high (ICC of >0.98) with all of the antifungals under all the conditions tested. The end point reading criteria and the time of incubation affected neither the reproducibility of the methods nor their correlation, and their effect on MICs was statistically significant.

Mitochondrial membrane peroxidizability index is inversely related to maximum life span in mammals.

The oxidative stress theory of aging predicts a low degree of fatty acid unsaturation in tissues of longevous animals, because membrane lipids increase their sensitivity to oxidative damage as a function of their unsaturation. Accordingly, the fatty acids analyses of liver mitochondria from eight mammals, ranging in maximum life span from 3.5 to 46 years, show that the total number of double bonds and the peroxidizability index are negatively correlated with maximum life span (r = -0. 88, P < 0.003; r = -0.87, P < 0.004, respectively). This is not due to a low content of unsaturated fatty acids in longevous animals, but mainly to a redistribution between kinds of the polyunsaturated n-3 fatty acids series, shifting from the highly unsaturated docosahexaenoic acid (r = -0.89, P < 0.003) to the less unsaturated linolenic acid (r = 0.97, P < 0.0001). This redistribution pattern strongly suggests the presence of a constitutively low delta6-desaturase activity in longevous animals (r = -0.96, P < 0.0001). Thus, it may be proposed that, during evolution, a low degree of fatty acid unsaturation in liver mitochondria may have been selected in longevous mammals in order to protect the tissues against oxidative damage, while maintaining an appropriate environment for membrane function.

Heart fatty acid unsaturation and lipid peroxidation, and aging rate, are lower in the canary and the parakeet than in the mouse.

Despite their high metabolic rates, birds have a much higher maximum longevity (MLSP) than mammals of similar body size, and thus represent ideal models for identifying longevity characteristics not linked to low metabolic rates. This study shows that the fatty acid double bond content of both canary (MLSP = 24 years) and parakeet (MLSP = 21 years) hearts is intrinsically lower than in mouse (MLSP = 3.5 years) heart. This is caused by a redistribution between types of unsaturated fatty acids, mainly due to a lower content of the most highly unsaturated docosahexaenoic acid (22:6n-3) in the two birds in relation to the mammal. The lower double bond content leads to a lower sensitivity to lipid peroxidation, and to a lower level of in vivo lipid peroxidation in the heart of parakeets and canaries than in that of mice. Similar results have been previously found comparing liver mitochondria of rats and pigeons and tissues of different mammalian species. All these results taken together suggest that a low degree of fatty acid unsaturation is a general characteristic of longevous homeothermic vertebrate animals, both when they have low metabolic rates (mammals of large body size) or high metabolic rates (the studied birds); this constitutive trait protects their tissues and organelles against free radical mediated lipid peroxidation, and can contribute to their slow aging rate.