Effects of the demographic transition on the genetic variances and covariances of human life‐history traits

The recent demographic transitions to lower mortality and fertility rates in most human societies have led to changes and even quick reversals in phenotypic selection pressures. This can only result in evolutionary change if the affected traits are heritable, but changes in environmental conditions may also lead to subsequent changes in the genetic variance and covariance (the G matrix) of traits. It currently remains unclear if there have been concomitant changes in the G matrix of life‐history traits following the demographic transition. Using 300 years of genealogical data from Finland, we found that four key life‐history traits were heritable both before and after the demographic transition. The estimated heritabilities allow a quantifiable genetic response to selection during both time periods, thus facilitating continued evolutionary change. Further, the G matrices remained largely stable but revealed a trend for an increased additive genetic variance and thus evolutionary potential of the population after the transition. Our results demonstrate the validity of predictions of evolutionary change in human populations even after the recent dramatic environmental change, and facilitate predictions of how our biology interacts with changing environments, with implications for global public health and demography.     

Compensatory growth following transient intraguild predation risk in predatory mites

Compensatory or catch‐up growth following growth impairment caused by transient environmental stress, due to adverse abiotic factors or food, is widespread in animals. Such growth strategies commonly balance retarded development and reduced growth. They depend on the type of stressor but are unknown for predation risk, a prime selective force shaping life history. Anti‐predator behaviours by immature prey typically come at the cost of reduced growth rates with potential negative consequences on age and size at maturity. Here, we investigated the hypothesis that transient intraguild predation (IGP) risk induces compensatory or catch‐up growth in the plant‐inhabiting predatory mite Phytoseiulus persimilis. Immature P. persimilis were exposed in the larval stage to no, low or high IGP risk, and kept under benign conditions in the next developmental stage, the protonymph. High but not low IGP risk prolonged development of P. persimilis larvae, which was compensated in the protonymphal stage by increased foraging activity and accelerated development, resulting in optimal age and size at maturity. Our study provides the first experimental evidence that prey may balance developmental costs accruing from anti‐predator behaviour by compensatory growth.     

Restoration of managed pine fens: effect on hydrology and vegetation

Question: How does restoration affect the hydrology and the understorey vegetation of managed pine fens? Location: Oligotrophic pine fens in Natura 2000 areas in Kainuu, eastern Finland. Methods: Eleven managed pine fens and eight pristine reference pine fens were chosen for the study in 2005. The managed fens, which had been drained for forestry during the 1970s and 1980s, were restored in 2007. The water table was monitored in all fens over four growing seasons during 2006 to 2009, and vegetation was surveyed from permanent sample plots in 2006 and 2009. Results: Before restoration in 2006, the water table was at a significantly lower level in the managed fens compared with the pristine fens. Immediately after restoration, the water table rose to the same level as in the pristine fens, and this change was permanent. Forest drainage had had little impact on the understorey vegetation of the managed fens in the three decades before restoration, with species typical of pristine fens still dominating the sites. Forest dwarf shrubs and feather mosses had started to increase in cover, but mire dwarf shrubs and Sphagnum mosses still dominated the managed fens. Only the typical hollow species Sphagnum majus, Sphagnum balticum and Scheuzeria palustris were missing from the managed fens. Two years after restoration, the changes in species composition were also marginal, with increased cover of mire dwarf shrubs and sedges being the only significant change. Conclusions: The success of restoration of oligotrophic pine fens seems likely, given that changes in hydrological functioning occurred rapidly, and since little change has occurred in the vegetation composition after draining. Speeding up the regeneration process in these peatland types by restoration may, therefore, be recommended, especially if the drainage effect extends to nearby pristine mires and influences their biodiversity.     

Phylogeography of the ant Myrmica rubra and its inquiline social parasite

Widely distributed Palearctic insects are ideal to study phylogeographic patterns owing to their high potential to survive in many Pleistocene refugia and-after the glaciation-to recolonize vast, continuous areas. Nevertheless, such species have received little phylogeographic attention. Here, we investigated the Pleistocene refugia and subsequent postglacial colonization of the common, abundant, and widely distributed ant Myrmica rubra over most of its Palearctic area, using mitochondrial DNA (mtDNA). The western and eastern populations of M. rubra belonged predominantly to separate haplogroups, which formed a broad secondary contact zone in Central Europe. The distribution of genetic diversity and haplogroups implied that M. rubra survived the last glaciation in multiple refugia located over an extensive area from Iberia in the west to Siberia in the east, and colonized its present areas of distribution along several routes. The matrilineal genetic structure of M. rubra was probably formed during the last glaciation and subsequent postglacial expansion. Additionally, because M. rubra has two queen morphs, the obligately socially parasitic microgyne and its macrogyne host, we tested the suggested speciation of the parasite. Locally, the parasite and host usually belonged to the same haplogroup but differed in haplotype frequencies. This indicates that genetic differentiation between the morphs is a universal pattern and thus incipient, sympatric speciation of the parasite from its host is possible. If speciation is taking place, however, it is not yet visible as lineage sorting of the mtDNA between the morphs.     

Protein metabolism and strength performance after bovine colostrum supplementation

Summary. This study was designed to determine the responses of muscle protein, serum amino acids, and strength performance to bovine colostrum supplementation in physically active men. The rest (R) group (n=6) and the exercise (E) group (n=6) carried out twice a 2-week experiment randomly assigned in a double-blind fashion with either placebo (PLA; consuming daily 20g maltodextrin) or bovine colostrum (COL; consuming daily 20g colostrum supplement) treatment with one month between. On the test day after the treatment period the measurements were carried out in fasting conditions and E carried out a strength training session (STS). The methods involved the infusion of ring-²H₅-phenylalanine, femoral arterial and venous blood sampling, and biopsies from the vastus lateralis muscle. Serum concentration of essential amino acids during recovery was greater (p<0.05) in the COL groups compared with the PLA groups. Both muscle protein synthesis and breakdown increased (p<0.05) with COL. There were no differences in phenylalanine net balance or strength performance between the PLA and COL groups. It was concluded that a 2-week supplementation with bovine colostrum in physically active men increases serum concentration of essential amino acids but has no effect either on strength performance or protein net balance in fasting conditions during recovery after STS.     

Dimeric galectin-1 binds with high affinity to alpha2,3-sialylated and non-sialylated terminal N-acetyllactosamine units on surface-bound extended glycans

Galectin-1 is a member of the galectin family of glycan-binding proteins and occurs as an approximately 29.5-kDa noncovalent homodimer (dGal-1) that is widely expressed in many tissues. Here, we report that human recombinant dGal-1 bound preferentially and with high affinity (apparent K(d) approximately 2-4 microM) to immobilized extended glycans containing terminal N-acetyllactosamine (LN; Galbeta1-4GlcNAc) sequences on poly-N-acetyllactosamine (PL; (-3Galbeta1-4GlcNAcbeta1-)(n)) sequences, complex-type biantennary N-glycans, or novel chitin-derived glycans modified to contain terminal LN. Although terminal Gal residues are important for dGal-1 recognition, dGal-1 bound similarly to alpha3-sialylated and alpha2-fucosylated terminal LN, but not to alpha6-sialylated and alpha3-fucosylated terminal LN. The binding specificity of human recombinant dGal-1 was similar to that observed with purified bovine heart-derived dGal-1. Unexpectedly, dGal-1 bound free ligands in solution with relatively low affinity and displayed no preference for extended glycans, indicating that dGal-1 preferentially recognizes extended glycans only when they are surface-bound, such as found on cell surfaces. Human dGal-1 also bound to both native and desialylated human promyelocytic HL-60 cells with similar affinity as observed for immobilized long chain PL. Binding to these cells was reduced upon treatment with endo-beta-galactosidase, which cleaves PL sequences, indicating that cell-surface PLs are ligands. To test the role of dimerization in dGal-1 binding, we examined the binding of a mutated form of dGal-1 that weakly dimerizes (monomeric Gal-1 (mGal-1)) and a covalently dimerized (chemically cross-linked) form of mGal-1 (cd-mGal-1). dGal-1 and cd-mGal-1 had similar affinities that were both approximately 3.5-fold higher for immobilized PL than observed for mGal-1, suggesting that dGal-1 acts as a dimer to cross-link terminal LN units on immobilized PL. These results indicate that dGal-1 functions as a dimer to recognize LN units on extended PLs on cell surfaces.     

Bordetella species are distinguished by patterns of substantial gene loss and host adaptation

Pathogens of the bacterial genus Bordetella cause respiratory disease in humans and animals. Although virulence and host specificity vary across the genus, the genetic determinants of this diversity remain unidentified. To identify genes that may underlie key phenotypic differences between these species and clarify their evolutionary relationships, we performed a comparative analysis of genome content in 42 Bordetella strains by hybridization of genomic DNA to a microarray representing the genomes of three Bordetella species and by subtractive hybridization. Here we show that B. pertussis and B. parapertussis are predominantly differentiated from B. bronchiseptica by large, species-specific regions of difference, many of which encode or direct synthesis of surface structures, including lipopolysaccharide O antigen, which may be important determinants of host specificity. The species also exhibit sequence diversity at a number of surface protein-encoding loci, including the fimbrial major subunit gene, fim2. Gene loss, rather than gene acquisition, accompanied by the proliferation of transposons, has played a fundamental role in the evolution of the pathogenic bordetellae and may represent a conserved evolutionary mechanism among other groups of microbial pathogens.     

Nε-Modified lysine containing inhibitors for SIRT1 and SIRT2

Sirtuins catalyze the NAD⁺ dependent deacetylation of N^ε-acetyl lysine residues to nicotinamide, O′-acetyl-ADP-ribose (OAADPR) and N^ε-deacetylated lysine. Here, an easy-to-synthesize Ac-Ala-Lys-Ala sequence has been used as a probe for the screening of novel N^ε-modified lysine containing inhibitors against SIRT1 and SIRT2. N^ε-Selenoacetyl and N^ε-isothiovaleryl were the most potent moieties found in this study, comparable to the widely studied N^ε-thioacetyl group. The N^ε-3,3-dimethylacryl and N^ε-isovaleryl moieties gave significant inhibition in comparison to the N^ε-acetyl group present in the substrates. In addition, the studied N^ε-alkanoyl, N^ε-α,β-unsaturated carbonyl and N^ε-aroyl moieties showed that the acetyl binding pocket can accept rather large groups, but is sensitive to even small changes in electronic and steric properties of the N^ε-modification. These results are applicable for further screening of N^ε-acetyl analogues.