Experimental niche evolution alters the strength of the diversity–productivity relationship

The relationship between biodiversity and ecosystem functioning (BEF) has become a cornerstone of community and ecosystem ecology and an essential criterion for making decisions in conservation biology and policy planning. It has recently been proposed that evolutionary history should influence the BEF relationship because it determines species traits and, thus, species’ ability to exploit resources. Here we test this hypothesis by combining experimental evolution with a BEF experiment. We isolated 20 bacterial strains from a marine environment and evolved each to be generalists or specialists. We then tested the effect of evolutionary history on the strength of the BEF relationship with assemblages of 1 to 20 species constructed from the specialists, generalists and ancestors. Assemblages of generalists were more productive on average because of their superior ability to exploit the environmental heterogeneity. The slope of the BEF relationship was, however, stronger for the specialist assemblages because of enhanced niche complementarity. These results show how the BEF relationship depends critically on the legacy of past evolutionary events.     

Implication of gut microbiota metabolites in cardiovascular and metabolic diseases

Evidence from the literature keeps highlighting the impact of mutualistic bacterial communities of the gut microbiota on human health. The gut microbita is a complex ecosystem of symbiotic bacteria which contributes to mammalian host biology by processing, otherwise, indigestible nutrients, supplying essential metabolites, and contributing to modulate its immune system. Advances in sequencing technologies have enabled structural analysis of the human gut microbiota and allowed detection of changes in gut bacterial composition in several common diseases, including cardiometabolic disorders. Biological signals sent by the gut microbiota to the host, including microbial metabolites and pro-inflammatory molecules, mediate microbiome–host genome cross-talk. This rapidly expanding line of research can identify disease-causing and disease-predictive microbial metabolite biomarkers, which can be translated into novel biodiagnostic tests, dietary supplements, and nutritional interventions for personalized therapeutic developments in common diseases. Here, we review results from the most significant studies dealing with the association of products from the gut microbial metabolism with cardiometabolic disorders. We underline the importance of these postbiotic biomarkers in the diagnosis and treatment of human disorders.     

The Drosophila immune response against Gram-negative bacteria is mediated by a peptidoglycan recognition protein

The antimicrobial defence of Drosophila relies largely on the challenge-induced synthesis of an array of potent antimicrobial peptides by the fat body. The defence against Gram-positive bacteria and natural fungal infections is mediated by the Toll signalling pathway, whereas defence against Gram-negative bacteria is dependent on the Immune deficiency (IMD) pathway. Loss-of-function mutations in either pathway reduce the resistance to corresponding infections. The link between microbial infections and activation of these two pathways has remained elusive. The Toll pathway is activated by Gram-positive bacteria through a circulating Peptidoglycan recognition protein (PGRP-SA). PGRPs appear to be highly conserved from insects to mammals, and the Drosophila genome contains 13 members. Here we report a mutation in a gene coding for a putative transmembrane protein, PGRP-LC, which reduces survival to Gram-negative sepsis but has no effect on the response to Gram-positive bacteria or natural fungal infections. By genetic epistasis, we demonstrate that PGRP-LC acts upstream of the imd gene. The data on PGRP-SA with respect to the response to Gram-positive infections, together with the present report, indicate that the PGRP family has a principal role in sensing microbial infections in Drosophila.     

Conservation of hotspots for recombination in low-copy repeats associated with the NF1 microdeletion

Several large-scale studies of human genetic variation have provided insights into processes such as recombination that have shaped human diversity. However, regions such as low-copy repeats (LCRs) have proven difficult to characterize, hindering efforts to understand the processes operating in these regions. We present a detailed study of genetic variation and underlying recombination processes in two copies of an LCR (NF1REPa and NF1REPc) on chromosome 17 involved in the generation of NF1 microdeletions and in a third copy (REP19) on chromosome 19 from which the others originated over 6.7 million years ago. We find evidence for shared hotspots of recombination among the LCRs. REP19 seems to contain hotspots in the same place as the nonallelic recombination hotspots in NF1REPa and NF1REPc. This apparent conservation of patterns of recombination hotspots in moderately diverged paralogous regions contrasts with recent evidence that these patterns are not conserved in less-diverged orthologous regions of chimpanzees.     

Germline KRAS and BRAF mutations in cardio-facio-cutaneous syndrome

Cardio-facio-cutaneous (CFC) syndrome is characterized by a distinctive facial appearance, heart defects and mental retardation. It phenotypically overlaps with Noonan and Costello syndrome, which are caused by mutations in PTPN11 and HRAS, respectively. In 43 individuals with CFC, we identified two heterozygous KRAS mutations in three individuals and eight BRAF mutations in 16 individuals, suggesting that dysregulation of the RAS-RAF-ERK pathway is a common molecular basis for the three related disorders.     

Evaluation of Regime Switching Models for Real‐Time Business Cycle Analysis of the Euro Area

In this paper, we aim at assessing Markov switching and threshold models in their ability to identify turning points of economic cycles. By using vintage data updated on a monthly basis, we compare their ability to date ex post the occurrence of turning points, evaluate the stability over time of the signal emitted by the models and assess their ability to detect in real‐time recession signals. We show that the competitive use of these models provides a more robust analysis and detection of turning points. To perform the complete analysis, we have built a historical vintage database for the euro area going back to 1970 for two monthly macroeconomic variables of major importance for short‐term economic outlook, namely the industrial production index and the unemployment rate. Copyright © 2013 John Wiley & Sons, Ltd.     

Progress and prospects in rat genetics: a community view

The rat is an important system for modeling human disease. Four years ago, the rich 150-year history of rat research was transformed by the sequencing of the rat genome, ushering in an era of exceptional opportunity for identifying genes and pathways underlying disease phenotypes. Genome-wide association studies in human populations have recently provided a direct approach for finding robust genetic associations in common diseases, but identifying the precise genes and their mechanisms of action remains problematic. In the context of significant progress in rat genomic resources over the past decade, we outline achievements in rat gene discovery to date, show how these findings have been translated to human disease, and document an increasing pace of discovery of new disease genes, pathways and mechanisms. Finally, we present a set of principles that justify continuing and strengthening genetic studies in the rat model, and further development of genomic infrastructure for rat research.     

Andalò di Negro’s De compositione astrolabii: a critical edition with English translation and notes

In this article, we publish the critical edition of Andalò di Negro’s De compositione astrolabii, with English translation and commentary. The mathematician and astronomer Andalò di Negro (Genoa ca. 1260–Naples 1334) presumably redacted this treatise on the astrolabe in the 1330s, while residing at the court of King Robert of Naples. The present edition has three purposes: first, to make available a text missing from the previous compilations of works by Andalò di Negro (ed. Bonus Opus preclarissimum astrolabij compositum a domino Andalo de nigro genuensi foeliciter incipit…Explicit tractatus astrolabij excellentissimi mathematici Andalonis genuensis, emendatus per celeberrimum et doctissimum astronomum magistrum Petrum Bonum Avogarium in foelici gymnasio ferrariensi. [Ferrara]: magister Johannes Picardus, 1475; Bertolotto II Trattato sull’Astrolabio di Andalò di Negro, riprodotto dall’edizione ferrarese del 1475, con prefazione del socio G. Bertolotto. Atti della società ligure di storia patria 25, 51–141, 1892; Fornaciari and Faracovi Trattato sull’astrolabio di Andalò di Negro, a cura di P.E. Fornaciari e O.P. Faracovi. Pubblicazione del Comune di Livorno in occasione della “Primavera della Scienza a Livorno” (febbraio-maggio 2005). Ospedaletto: Pacini editore, 2005); second, to revise a privately circulated edition of the text (Cesari L’astrolabio di Andalò di Negro, Parte I, edizione critica. Milano: s.n., 1984a; Practica Astrolabii di Andalò di Negro, Parte I. Edizione critica. Bergamo: Istituto Universitario di Bergamo, 1984b); and third, to help disseminating one of the rare Latin texts presenting the principles of the stereographic projection which underlie the construction of the astrolabe.