Lifespan prolonging mechanisms and insulin upregulation without fat accumulation in long-lived reproductives of a higher termite.

Kings and queens of eusocial termites can live for decades, while queens sustain a nearly maximal fertility. To investigate the molecular mechanisms underlying their long lifespan, we carried out transcriptomics, lipidomics and metabolomics in Macrotermes natalensis on sterile short-lived workers, long-lived kings and five stages spanning twenty years of adult queen maturation. Reproductives share gene expression differences from workers in agreement with a reduction of several aging-related processes, involving upregulation of DNA damage repair and mitochondrial functions. Anti-oxidant gene expression is downregulated, while peroxidability of membranes in queens decreases. Against expectations, we observed an upregulated gene expression in fat bodies of reproductives of several components of the IIS pathway, including an insulin-like peptide, Ilp9. This pattern does not lead to deleterious fat storage in physogastric queens, while simple sugars dominate in their hemolymph and large amounts of resources are allocated towards oogenesis. Our findings support the notion that all processes causing aging need to be addressed simultaneously in order to prevent it.

First catalogue of the Asopinae (Hemiptera, Pentatomidae) from French Guiana.

Nine identified species of Asopinae belonging to seven genera were previously reported from French Guiana. Twelve more species are reported here for the first time. Thus, a total of 21 species in nine genera of Asopinae are now known and reported from French Guiana, which represents about 20 % of all the Asopinae species recorded in South America, and though French Guiana only accounting for half a percent of its surface area. Examined species are photographed; localities, some new hosts and ecological aspects are mentioned. The genera Tylospilus and Tyrannocoris are recorded here for the first time in French Guiana and Tyrannocoris jole for the first time in South America.

Structural basis for substrate selectivity and nucleophilic substitution mechanisms in human adenine phosphoribosyltransferase catalyzed reaction.

The reversible adenine phosphoribosyltransferase enzyme (APRT) is essential for purine homeostasis in prokaryotes and eukaryotes. In humans, APRT (hAPRT) is the only enzyme known to produce AMP in cells from dietary adenine. APRT can also process adenine analogs, which are involved in plant development or neuronal homeostasis. However, the molecular mechanism underlying substrate specificity of APRT and catalysis in both directions of the reaction remains poorly understood. Here we present the crystal structures of hAPRT complexed to three cellular nucleotide analogs (hypoxanthine, IMP, and GMP) that we compare with the phosphate-bound enzyme. We established that binding to hAPRT is substrate shape-specific in the forward reaction, whereas it is base-specific in the reverse reaction. Furthermore, a quantum mechanics/molecular mechanics (QM/MM) analysis suggests that the forward reaction is mainly a nucleophilic substitution of type 2 (SN2) with a mix of SN1-type molecular mechanism. Based on our structural analysis, a magnesium-assisted SN2-type mechanism would be involved in the reverse reaction. These results provide a framework for understanding the molecular mechanism and substrate discrimination in both directions by APRTs. This knowledge can play an instrumental role in the design of inhibitors, such as antiparasitic agents, or adenine-based substrates.

Structural Insights into the Forward and Reverse Enzymatic Reactions in Human Adenine Phosphoribosyltransferase.

Phosphoribosyltransferases catalyze the displacement of a PRPP α-1'-pyrophosphate to a nitrogen-containing nucleobase. How they control the balance of substrates/products binding and activities is poorly understood. Here, we investigated the human adenine phosphoribosyltransferase (hAPRT) that produces AMP in the purine salvage pathway. We show that a single oxygen atom from the Tyr105 side chain is responsible for selecting the active conformation of the 12 amino acid long catalytic loop. Using in vitro, cellular, and in crystallo approaches, we demonstrated that Tyr105 is key for the fine-tuning of the kinetic activity efficiencies of the forward and reverse reactions. Together, our results reveal an evolutionary pressure on the strictly conserved Tyr105 and on the dynamic motion of the flexible loop in phosphoribosyltransferases that is essential for purine biosynthesis in cells. These data also provide the framework for designing novel adenine derivatives that could modulate, through hAPRT, diseases-involved cellular pathways.

Diagnosis of Calagasma Bergroth and Epipedus Spinola with description of Calagasma eclipsa sp. nov. and Epipedus rolstoni sp. nov. (Hemiptera: Heteroptera: Pentatomidae: Pentatominae: Carpocorini).

The genus Calagasma Bergroth synonymized with the genus Epipedus Spinola by Rolston (1987) is reinstated. The diagnostic characters of the genus Calagasma are redefined, pictures of the Calagasma margarita syntype and recently collected specimens from French Guiana, including males hitherto unknown are presented. Calagasma eclipsa, a new species from French Guiana is described. Epipedus is redescribed and a new species Epipedus rolstoni is described.

Taxonomic and functional composition of arthropod assemblages across contrasting Amazonian forests.

Arthropods represent most of global biodiversity, with the highest diversity found in tropical rain forests. Nevertheless, we have a very incomplete understanding of how tropical arthropod communities are assembled. We conducted a comprehensive mass sampling of arthropod communities within three major habitat types of lowland Amazonian rain forest, including terra firme clay, white-sand and seasonally flooded forests in Peru and French Guiana. We examined how taxonomic and functional composition (at the family level) differed across these habitat types in the two regions. The overall arthropod community composition exhibited strong turnover among habitats and between regions. In particular, seasonally flooded forest habitats of both regions comprised unique assemblages. Overall, 17·7% (26 of 147) of arthropod families showed significant preferences for a particular habitat type. We present a first reproducible arthropod functional classification among the 147 taxa based on similarity among 21 functional traits describing feeding source, major mouthparts and microhabitats inhabited by each taxon. We identified seven distinct functional groups whose relative abundance contrasted strongly across the three habitats, with sap and leaf feeders showing higher abundances in terra firme clay forest. Our novel arthropod functional classification provides an important complement to link these contrasting patterns of composition to differences in forest functioning across geographical and environmental gradients. This study underlines that both environment and biogeographical processes are responsible for driving arthropod taxonomic composition while environmental filtering is the main driver of the variance in functional composition.

Morphological, biogeographical and molecular evidence of Carpocoris mediterraneus as a valid species (Hemiptera: Pentatomidae).

Carpocoris mediterraneus Tamanini, 1958, synonymized with Carpocoris fuscispinus (Boheman, 1851) by Ribes et al. (2007), is restored to the species level. The shape of the pronotum is a good diagnostic character to distinguish the two species. The existence of two valid species is supported by geographical distribution patterns in Western Europe: Mediterranean-Atlantic for C. mediterraneus, and Continental for C. fuscispinus. In France and Spain, in some areas, the two species are found in sympatry (sometimes even on the same plant). Morphological observations are confirmed at the molecular level by sequencing of the mitochondrial Cytochrome c oxidase I standard barcode fragment. Indeed, inter-specific divergence largely exceeded intra-specific divergence and our phylogenetic reconstructions reveal that Carpocoris mediterraneus and Carpocoris fuscispinus form two reciprocally monophyletic genetic lineages. A morphological identification key is proposed for all the European species of the genus Carpocoris, to facilitate identification. Carpocoris fuscispinus is first time recorded from Portugal.