Human and Chimpanzee Gene Expression Differences Replicated in Mice Fed Different Diets

Although the human diet is markedly different from the diets of closely related primate species, the influence of diet on phenotypic and genetic differences between humans and other primates is unknown. In this study, we analyzed gene expression in laboratory mice fed diets typical of humans and of chimpanzees. The effects of human diets were found to be significantly different from that of a chimpanzee diet in the mouse liver, but not in the brain. Importantly, 10% of the genes that differ in their expression between humans and chimpanzee livers differed also between the livers of mice fed the human and chimpanzee diets. Furthermore, both the promoter sequences and the amino acid sequences of these diet-related genes carry more differences between humans and chimpanzees than random genes. Our results suggest that the mouse can be used to study at least some aspects of human-specific traits

Mechanical Properties of Plant Underground Storage Organs and Implications for Dietary Models of Early Hominins

The diet of early human ancestors has received renewed theoretical interest since the discovery of elevated d13C values in the enamel of Australopithecus africanus and Paranthropus robustus. As a result, the hominin diet is hypothesized to have included C4 grass or the tissues of animals which themselves consumed C4 grass. On mechanical grounds, such a diet is incompatible with the dental morphology and dental microwear of early hominins. Most inferences, particularly for Paranthropus, favor a diet of hard or mechanically resistant foods. This discrepancy has invigorated the longstanding hypothesis that hominins consumed plant underground storage organs (USOs). Plant USOs are attractive candidate foods because many bulbous grasses and cormous sedges use C4 photosynthesis. Yet mechanical data for USOs—or any putative hominin food—are scarcely known. To fill this empirical void we measured the mechanical properties of USOs from 98 plant species from across sub-Saharan Africa. We found that rhizomes were the most resistant to deformation and fracture, followed by tubers, corms, and bulbs. An important result of this study is that corms exhibited low toughness values (mean = 265.0 J m-2) and relatively high Young’s modulus values (mean = 4.9 MPa). This combination of properties fits many descriptions of the hominin diet as consisting of hard-brittle objects. When compared to corms, bulbs are tougher (mean = 325.0 J m-2) and less stiff (mean = 2.5 MPa). Again, this combination of traits resembles dietary inferences, especially for Australopithecus, which is predicted to have consumed soft-tough foods. Lastly, we observed the roasting behavior of Hadza hunter-gatherers and measured the effects of roasting on the toughness on undomesticated tubers. Our results support assumptions that roasting lessens the work of mastication, and, by inference, the cost of digestion. Together these findings provide the first mechanical basis for discussing the adaptive advantages of roasting tubers and the plausibility of USOs in the diet of early hominins

Measuring Health Utilities in Children and Adolescents: A Systematic Review of the Literature.

BACKGROUND: The objective of this review was to evaluate the use of all direct and indirect methods used to estimate health utilities in both children and adolescents. Utilities measured pre- and post-intervention are combined with the time over which health states are experienced to calculate quality-adjusted life years (QALYs). Cost-utility analyses (CUAs) estimate the cost-effectiveness of health technologies based on their costs and benefits using QALYs as a measure of benefit. The accurate measurement of QALYs is dependent on using appropriate methods to elicit health utilities. OBJECTIVE: We sought studies that measured health utilities directly from patients or their proxies. We did not exclude those studies that also included adults in the analysis, but excluded those studies focused only on adults. METHODS AND FINDINGS: We evaluated 90 studies from a total of 1,780 selected from the databases. 47 (52%) studies were CUAs incorporated into randomised clinical trials; 23 (26%) were health-state utility assessments; 8 (9%) validated methods and 12 (13%) compared existing or new methods. 22 unique direct or indirect calculation methods were used a total of 137 times. Direct calculation through standard gamble, time trade-off and visual analogue scale was used 32 times. The EuroQol EQ-5D was the most frequently-used single method, selected for 41 studies. 15 of the methods used were generic methods and the remaining 7 were disease-specific. 48 of the 90 studies (53%) used some form of proxy, with 26 (29%) using proxies exclusively to estimate health utilities. CONCLUSIONS: Several child- and adolescent-specific methods are still being developed and validated, leaving many studies using methods that have not been designed or validated for use in children or adolescents. Several studies failed to justify using proxy respondents rather than administering the methods directly to the patients. Only two studies examined missing responses to the methods administered with respect to the patients' ages

Aneuploidy as a mechanism of adaptation to telomerase insufficiency

Cells’ survival is determined by their ability to adapt to constantly changing environment. Adaptation responses involve global changes in transcription, translation, and posttranslational modifications of proteins. In recent years, karyotype changes in adapting populations of single cell organisms have been reported in a number of studies. More recently, we have described aneuploidy as an adaptation mechanism used by populations of budding yeast Saccharomyces cerevisiae to survive telomerase insufficiency induced by elevated growth temperature. Genetic evidence suggests that telomerase insufficiency is caused by decreased levels of the telomerase catalytic subunit Est2. Here, we present experiments arguing that the underlying cause of this phenomenon may be within the telomerase RNA TLC1: changes in the expression of TLC1 as well as mutations in the TLC1 template region affect telomere length equilibrium and the temperature threshold for the induction of telomerase insufficiency. We discuss what lies at the root of telomerase insufficiency, how cell populations overcome it through aneuploidy and whether reversible aneuploidy could be an adaptation mechanism for a variety of environmental stresses