The Nutritional Geometry of Resource Scarcity: Effects of Lean Seasons and Habitat Disturbance on Nutrient Intakes and Balancing in Wild Sifakas

Animals experience spatial and temporal variation in food and nutrient supply, which may cause deviations from optimal nutrient intakes in both absolute amounts (meeting nutrient requirements) and proportions (nutrient balancing). Recent research has used the geometric framework for nutrition to obtain an improved understanding of how animals respond to these nutritional constraints, among them free-ranging primates including spider monkeys and gorillas. We used this framework to examine macronutrient intakes and nutrient balancing in sifakas (Propithecus diadema) at Tsinjoarivo, Madagascar, in order to quantify how these vary across seasons and across habitats with varying degrees of anthropogenic disturbance. Groups in intact habitat experience lean season decreases in frugivory, amounts of food ingested, and nutrient intakes, yet preserve remarkably constant proportions of dietary macronutrients, with the proportional contribution of protein to the diet being highly consistent. Sifakas in disturbed habitat resemble intact forest groups in the relative contribution of dietary macronutrients, but experience less seasonality: all groups’ diets converge in the lean season, but disturbed forest groups largely fail to experience abundant season improvements in food intake or nutritional outcomes. These results suggest that: (1) lemurs experience seasonality by maintaining nutrient balance at the expense of calories ingested, which contrasts with earlier studies of spider monkeys and gorillas, (2) abundant season foods should be the target of habitat management, even though mortality might be concentrated in the lean season, and (3) primates’ within-group competitive landscapes, which contribute to variation in social organization, may vary in complex ways across habitats and seasons.     

A Hematogenous Route for Medulloblastoma Leptomeningeal Metastases

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Genetically-encoded fragment-based discovery of glycopeptide ligands for DC-SIGN

We have employed genetically-encoded fragment-based discovery to identify novel glycopeptides with affinity for the dendritic cell receptor DC-SIGN. Starting from libraries of 10⁸ mannose-conjugated peptides, we identified glycopeptides that exhibited up to a 650-fold increase in multivalent binding affinity for DC-SIGN, which is also preserved in cells. Monovalently, our most potent glycopeptides have a similar potency to a Man₃ oligosaccharide, representing a 15-fold increase in activity compared to mannose. These compounds represent the first examples of glycopeptide ligands that target the CRD of DC-SIGN. The natural framework of glycopeptide conjugates and the simplicity of orthogonal conjugation to make these glycopeptides anticipates a promising future for development of DC-SIGN-targeting moieties.     

The origins and early elaboration of projectile technology

The ability of Homo sapiens to kill prey at a distance is arguably one of the catalysts for our current ecological dominance. Many researchers have suggested its origins lie in the African Middle Stone Age or the European Middle Palaeolithic (～300‐30 thousand years ago), but the perishable components of armatures rarely preserve. Most research on this subject therefore emphasises analysis of armature tip size, shape, and diagnostic impacts or residues. Other lines of evidence have included human skeletal anatomy or analyses of the species composition of faunal assemblages. Projectile Impact Marks (PIMs) on archaeofaunal remains offer an ideal complement to this work, but their potential has been restricted mainly to the later Eurasian zooarchaeological record. A review of current evidence and approaches shows that systematic PIM research could add much to our understanding of early projectile technology, especially in Africa.     

Rock lobster hepatopancreas consumption data for dietary exposure assessment among recreational harvesters in Tasmania and South Australia

In 2012 and 2015, blooms of Alexandrium tamarense occurred in Tasmania, Australia, and paralytic shellfish toxins (PST) were identified in the hepatopancreas of Southern Rock Lobsters. The human health risk was unclear, because consumption data were not available for lobster hepatopancreas. Thus, the aim of this study was to investigate the types of lobster tissues consumed, hepatopancreas portion size, and consumption format (boiled, steamed, raw, etc.), for Tasmanian and South Australian recreational harvesters.

A significant proportion of harvesters (15%) eat lobster hepatopancreas, with the majority consuming it as a dipping sauce for cooked (boiled or steamed) lobster meat. Two different methods were used to estimate portion size, a recollection-based food consumption questionnaire (FCQ) and a prospective Food Diary – mean portion size estimates showed good agreement: 3.4 g and 4.8 g, respectively. These results are critical for assessing the exposure of recreational harvesters to acute contaminants, such as PST, in lobster hepatopancreas. Results from the FCQ showed that lobster hepatopancreas is not consumed as often as white meat, suggesting that exposure to contaminants in hepatopancreas may be less frequent than white meat. This should be considered when evaluating human health risk from repeated or long term (chronic) exposure to contaminants in lobsters.     

A practical synthesis of xylo- and arabinofuranoside precursors by diastereoselective reduction using Corey-Bakshi-Shibata catalyst

The Corey-Bakshi-Shibata (CBS) catalyst provides an efficient mechanism to reduce ketones and achieve desired enantiopure alcohols. Herein, the diastereoselective reduction of C-2′ and C-3′-keto ribofuranoside derivatives to the corresponding arabino- and xylofuranosides in greater than 95% diastereomeric excess is reported. The stereo-directed substitution with an azido group as well as the synthesis of prodrugs cytarabine and vidarabine are also described. The reported strategy offers superior diastereoselectivity, shorter reaction times, and obviates cooling required with comparable protocols involving achiral reductants.