Dispersal behaviour of African wild dogs in Kenya

Dispersal behaviour plays a key role in social organisation, demography and population genetics. We describe dispersal behaviour in a population of African wild dogs (Lycaon pictus) in Kenya. Almost all individuals, of both sexes, left their natal packs, with 45 of 46 reproductively active “alpha” individuals acquiring their status through dispersal. Dispersal age, group size and distance did not differ between males and females. However, only females embarked on secondary dispersal, probably reflecting stronger reproductive competition among females than males. When dispersing, GPS-collared wild dogs travelled further than when resident, both in daylight and by night, following routes an order of magnitude longer than the straight-line distance covered. Dispersers experienced a daily mortality risk three times that experienced by adults in resident packs. The detailed movement data provided by GPS-collars helped to reconcile differences between dispersal patterns reported previously from other wild dog populations. However, the dispersal patterns observed at this and other sites contrast with those assumed in published demographic models for this endangered species. Given the central role of dispersal in demography, models of wild dog population dynamics need to be updated to account for improved understanding of dispersal processes.     

A pluripotent human stem-cell clone isolated from the TERA-2 teratocarcinoma line lacks antigens SSEA-3 and SSEA-4 in vitro, but expresses these antigens when grown as a xenograft tumor

Human embryonal carcinoma (EC) cells generally express the cell-surface, stage-specific embryonic antigens 3 and 4 (SSEA-3 and SSEA-4), the epitopes of which are defined by two monoclonal antibodies that recognize different portions of an extended globoseries oligosaccharide. To examine further the relationship between these epitopes and the human EC phenotype, we investigated the properties of two newly isolated clones from the human teratocarcinoma cell line, TERA-2. One clone expresses SSEA-3 and SSEA-4; the other does not. Nevertheless, these clones otherwise resemble one another, and based upon their morphology, their expression of other cell-surface antigens, and their ability to form xenograft tumors containing a variety of cell types, we conclude that both clones are composed of pluripotent human EC cells. When exposed to retinoic acid in vitro, neither clone differentiates as extensively as other clones that we have previously derived from TERA-2. These observations indicate heterogeneity among stem cells derived from a single human teratocarcinoma, and suggest that SSEA-3 and SSEA-4 are not necessarily integral features of the human EC phenotype. On the other hand, EC cells in xenograft tumors derived from the SSEA-3- and SSEA-4-negative clone re-express these epitopes. Further, this re-expression is stable, since EC cell lines that are SSEA-3- and SSEA-4-positive grow out when the tumors are explanted in vitro. We conclude that the expression of these globoseries epitopes can be modulated by environmental influences.     

Acute moderate-intensity exercise in middle-aged men has neither an anti- nor proinflammatory effect.

Strenuous exercise induces an initial pro- and subsequent anti-inflammatory response, and it has been suggested that this may be one of the ways that regular exercise reduces chronic inflammation and therefore the risk of cardiovascular disease. However, public health recommendations emphasize moderate-intensity physical activity, and it is important to understand whether moderate-intensity exercise has a similar anti-inflammatory effect. Twelve sedentary male volunteers (age 54 +/- 4 yr) completed two main trials, moderate-intensity exercise and rest (30 min at 50% maximal oxygen uptake vs. sitting, respectively). There were no significant changes in circulating neutrophils, lymphocytes, monocytes, or serum interleukin-6, interleukin-10, and C-reactive protein concentration over the 7 days following exercise. Similarly, lymphocyte adhesion to cultured endothelial cells and heme oxygenase-1 (HO-1) expression in lymphocytes and monocytes were not affected by walking at any time point. These results suggest that the long-term anti-inflammatory and antiatherogenic effects of regular moderate-intensity physical activity must be explained by something other than a profound net anti-inflammatory response to each exercise bout since a single bout of walking did not lead to a change in various markers of inflammation or lymphocyte adherence to cultured endothelial cells.     

Convergent Solid-phase Peptide Synthesis Performed in a CHCl3-phenol Mixed Solvent: Synthesis of Amyloid β-peptides as Examples with a Difficult Sequence

Convergent solid-phase peptide synthesis (CSPPS) involving the coupling of protected peptide segments on a solid support performed in a β-sheet disrupting solvent consisting of a mixture of CHCl₃ and phenol (v/v, 3/1), proceeded smoothly without danger of epimerization or of significant phenyl ester formation with the carboxyl component when diisopropylcarbodiimide (DIC) was used in the presence of 1-hydroxy-7-azabenzotriazole (HOAt) or 6-chloro-1-hydroxybenzotriazole (Cl-HOBt). In particular, this synthetic strategy using the CHCl₃ and phenol mixed solvent proved to be essential for coupling sparingly soluble segments even with difficult sequences. The present approach was successfully applied to the synthesis of amyloid β-peptide (Aβ) (1-40) and also its reversed Aβ (40-1) as an inactive control peptide.     

A novel terpene synthase controls differences in anti-aphrodisiac pheromone production between closely related Heliconius butterflies

Plants and insects often use the same compounds for chemical communication, but not much is known about the genetics of convergent evolution of chemical signals. The terpene (E)-β-ocimene is a common component of floral scent and is also used by the butterfly Heliconius melpomene as an anti-aphrodisiac pheromone. While the biosynthesis of terpenes has been described in plants and microorganisms, few terpene synthases (TPSs) have been identified in insects. Here, we study the recent divergence of 2 species, H. melpomene and Heliconius cydno, which differ in the presence of (E)-β-ocimene; combining linkage mapping, gene expression, and functional analyses, we identify 2 novel TPSs. Furthermore, we demonstrate that one, HmelOS, is able to synthesise (E)-β-ocimene in vitro. We find no evidence for TPS activity in HcydOS (HmelOS ortholog of H. cydno), suggesting that the loss of (E)-β-ocimene in this species is the result of coding, not regulatory, differences. The TPS enzymes we discovered are unrelated to previously described plant and insect TPSs, demonstrating that chemical convergence has independent evolutionary origins.

Plants and insects often use the same compounds for chemical communication, but little is known about the convergent evolution of such chemical signals. This study identifies a novel terpene synthase involved in production of an anti-aphrodisiac pheromone by the butterfly Heliconius melpomene. This enzyme is unrelated to other insect terpene synthases, providing evidence that the ability to synthesise terpenes has arisen multiple times independently within the insects.     

The TIM22 complex mediates the import of sideroflexins and is required for efficient mitochondrial one-carbon metabolism

Acylglycerol kinase (AGK) is a mitochondrial lipid kinase that contributes to protein biogenesis as a subunit of the TIM22 complex at the inner mitochondrial membrane. Mutations in AGK cause Sengers syndrome, an autosomal recessive condition characterized by congenital cataracts, hypertrophic cardiomyopathy, skeletal myopathy, and lactic acidosis. We mapped the proteomic changes in Sengers patient fibroblasts and AGK^KO cell lines to understand the effects of AGK dysfunction on mitochondria. This uncovered down-regulation of a number of proteins at the inner mitochondrial membrane, including many SLC25 carrier family proteins, which are predicted substrates of the complex. We also observed down-regulation of SFXN proteins, which contain five transmembrane domains, and show that they represent a novel class of TIM22 complex substrate. Perturbed biogenesis of SFXN proteins in cells lacking AGK reduces the proliferative capabilities of these cells in the absence of exogenous serine, suggesting that dysregulation of one-carbon metabolism is a molecular feature in the biology of Sengers syndrome.