Pore-forming toxins (PFTs) are virulence factors produced by many pathogenic bacteria and have long fascinated structural biologists, microbiologists and immunologists. Interestingly, pore-forming proteins with remarkably similar structures to PFTs are found in vertebrates and constitute part of their immune system. Recently, structural studies of several PFTs have provided important mechanistic insights into the metamorphosis of PFTs from soluble inactive monomers to cytolytic transmembrane assemblies. In this Review, we discuss the diverse pore architectures and membrane insertion mechanisms that have been revealed by these studies, and we consider how these features contribute to binding specificity for different membrane targets. Finally, we explore the potential of these structural insights to enable the development of novel therapeutic strategies that would prevent both the establishment of bacterial resistance and an excessive immune response.

Pore-forming toxins: ancient, but never really out of fashion

Isolated from a wide range of sources, the genus Paenibacillus comprises bacterial species relevant to humans, animals, plants, and the environment. Many Paenibacillus species can promote crop growth directly via biological nitrogen fixation, phosphate solubilization, production of the phytohormone indole-3-acetic acid (IAA), and release of siderophores that enable iron acquisition. They can also offer protection against insect herbivores and phytopathogens, including bacteria, fungi, nematodes, and viruses. This is accomplished by the production of a variety of antimicrobials and insecticides, and by triggering a hypersensitive defensive response of the plant, known as induced systemic resistance (ISR). Paenibacillus-derived antimicrobials also have applications in medicine, including polymyxins and fusaricidins, which are nonribosomal lipopeptides first isolated from strains of Paenibacillus polymyxa. Other useful molecules include exo-polysaccharides (EPS) and enzymes such as amylases, cellulases, hemicellulases, lipases, pectinases, oxygenases, dehydrogenases, lignin-modifying enzymes, and mutanases, which may have applications for detergents, food and feed, textiles, paper, biofuel, and healthcare. On the negative side, Paenibacillus larvae is the causative agent of American Foulbrood, a lethal disease of honeybees, while a variety of species are opportunistic infectors of humans, and others cause spoilage of pasteurized dairy products. This broad review summarizes the major positive and negative impacts of Paenibacillus: its realised and prospective contributions to agriculture, medicine, process manufacturing, and bioremediation, as well as its impacts due to pathogenicity and food spoilage. This review also includes detailed information in Additional files 1, 2, 3 for major known Paenibacillus species with their locations of isolation, genome sequencing projects, patents, and industrially significant compounds and enzymes. Paenibacillus will, over time, play increasingly important roles in sustainable agriculture and industrial biotechnology.

https://link.springer.com/content/pdf/10.1186%2Fs12934-016-0603-7.pdf

Current knowledge and perspectives of Paenibacillus : a review

The insulin-like growth factors (IGF) are evolutionarily ancient growth factors present in all vertebrates. The central importance of IGF for normal development and growth has been illustrated by the severe growth-retarded phenotype exhibited by IGF-I, IGF-II or IGF-I receptor knockout mice. Although we know much about the gross effects of IGF on the overall size of the fetus and the clinical manifestations that result from fetal and neonatal deficiency of IGF (i.e., severe growth retardation leads to dwarfism), very little is known about the in vivo actions of IGF during embryogenesis at the cellular and molecular levels. Most research on the developmental role of IGF has relied on rodent models, and attempts to elucidate the molecular and cellular basis of IGF actions have been hampered by the inaccessibility of the mammalian fetus enclosed in the uterus. During the past decade, there has been growing support for the concept that the IGF have been highly conserved in all vertebrates. Both IGF-I and IGF-II are present in fish, and their structures are highly conserved. Human and fish IGF-I are equally potent in mammalian and fish bioassay systems. Insulin-like growth factor mRNA is found in all life stages of fish, ranging from unfertilized egg to adult. The temporal and spatial expression pattems of fish IGF-I seem to be similar to those in mammals. Nutritional status and growth hormone both have a profound effect on IGF-I expression in fish, as they do in mammals. These features suggest that the IGF system is highly conserved between teleost fish and mammals. Because fish embryos develop extemally, they provide excellent animal models for understanding the regulatory roles of IGF, IGF receptor and IGF-binding proteins in vertebrate embryonic development. Current research on the developmental and nutritional roles of IGF in fish will undoubtedly contribute to knowledge of the basic physiology of vertebrates in general.

Nutritional and developmental regulation of insulin-like growth factors in fish : Nutritional and developmental roles of insulin-like growth factors between species

Over the past decade, a significant increase in the circulation of infectious agents was observed. With the spread and emergence of epizootics, zoonoses, and epidemics, the risks of pandemics became more and more critical. Human and animal health has also been threatened by antimicrobial resistance, environmental pollution, and the development of multifactorial and chronic diseases. This highlighted the increasing globalization of health risks and the importance of the human-animal-ecosystem interface in the evolution and emergence of pathogens. A better knowledge of causes and consequences of certain human activities, lifestyles, and behaviors in ecosystems is crucial for a rigorous interpretation of disease dynamics and to drive public policies. As a global good, health security must be understood on a global scale and from a global and crosscutting perspective, integrating human health, animal health, plant health, ecosystems health, and biodiversity. In this study, we discuss how crucial it is to consider ecological, evolutionary, and environmental sciences in understanding the emergence and re-emergence of infectious diseases and in facing the challenges of antimicrobial resistance. We also discuss the application of the "One Health" concept to non-communicable chronic diseases linked to exposure to multiple stresses, including toxic stress, and new lifestyles. Finally, we draw up a list of barriers that need removing and the ambitions that we must nurture for the effective application of the "One Health" concept. We conclude that the success of this One Health concept now requires breaking down the interdisciplinary barriers that still separate human and veterinary medicine from ecological, evolutionary, and environmental sciences. The development of integrative approaches should be promoted by linking the study of factors underlying stress responses to their consequences on ecosystem functioning and evolution. This knowledge is required for the development of novel control strategies inspired by environmental mechanisms leading to desired equilibrium and dynamics in healthy ecosystems and must provide in the near future a framework for more integrated operational initiatives.

/pdf/the-one-health-concept-10-years-old-and-a-long-road-ahead-3cw8v0vm79.pdf

The one health concept: 10 years old and a long road ahead

'Summary'	347	
I.	'Introduction'	348	
II.	'Origin of the cospeciation concept'	349	
III.	'Theoretical framework and methods for testing for cospeciation'	349	
IV.	'Studies of natural associations reveal the prevalence of host shifts'	355	
V.	'Relationship between host–symbiont coevolution and symbiont speciation'	378	
VI.	'Conclusion'	381	
 	'Acknowledgements'	381	
 	References	381	
 	Glossary	379	


Summary
Hosts and their symbionts are involved in intimate physiological and ecological interactions. The impact of these interactions on the evolution of each partner depends on the time-scale considered. Short-term dynamics – ‘coevolution’ in the narrow sense – has been reviewed elsewhere. We focus here on the long-term evolutionary dynamics of cospeciation and speciation following host shifts. Whether hosts and their symbionts speciate in parallel, by cospeciation, or through host shifts, is a key issue in host–symbiont evolution. In this review, we first outline approaches to compare divergence between pairwise associated groups of species, their advantages and pitfalls. We then consider recent insights into the long-term evolution of host–parasite and host–mutualist associations by critically reviewing the literature. We show that convincing cases of cospeciation are rare (7%) and that cophylogenetic methods overestimate the occurrence of such events. Finally, we examine the relationships between short-term coevolutionary dynamics and long-term patterns of diversification in host–symbiont associations. We review theoretical and experimental studies showing that short-term dynamics can foster parasite specialization, but that these events can occur following host shifts and do not necessarily involve cospeciation. Overall, there is now substantial evidence to suggest that coevolutionary dynamics of hosts and parasites do not favor long-term cospeciation.

https://nph.onlinelibrary.wiley.com/doi/pdf/10.1111/nph.12150

Cospeciation vs host-shift speciation: methods for testing, evidence from natural associations and relation to coevolution

La schistosomiase, ou bilharziose, est une maladie parasitaire tropicale et subtropicale causee par des parasites qui habitent les vaisseaux sanguins humains et sont transmis par des mollusques d’eau douce specifiques. L’infection humaine se produit par la penetration transcutanee du stade larvaire infectieux du parasite emis par le mollusque vecteur, dans l’eau de baignade.

/pdf/changements-globaux-et-infections-parasitaires-a-mollusques-3edsxcin1e.pdf

Changements globaux et infections parasitaires à mollusques vecteurs - Un schistosome hybride atteint l’Europe

Contrary to the majority of other Trematoda, Schistosoma species are gonochoric. Consequently, in endemic areas where several schistosome species overlap and can co-infect the same definitive host, there may be frequent opportunities for interspecific pairing. Our experimental study provides novel insight on the pairing behavior between Schistosoma bovis and S. mansoni in mixed infections in mice. We used six mate choice experiments to assess mating interactions between the two schistosome species. We show that mating between the two Schistosoma species is not random and that S. mansoni exhibits greater mate recognition compared to S. bovis. We also performed reciprocal crosses (male S. mansoni × female S. bovis) and (female S. mansoni × male S. bovis) that produce active swimming miracidia. These miracidia were genotyped by ITS2 sequencing and proposed for mollusc infection. Molecular analyses show that all the miracidia are parthenogenetically produced (i.e., their harbor the mother ITS2 genotype) and as a consequence can only infect the mollusc of the maternal species. Offspring produced by male S. mansoni × female S. bovis pairing can only infect Bulinus truncatus whereas offspring produced by female S. mansoni × male S. bovis can only infect Biomphalaria glabrata snails. Evolutionary and epidemiological consequences are discussed.

/pdf/mating-interactions-between-schistosoma-bovis-and-s-mansoni-bymiwzzh.pdf

Mating Interactions between Schistosoma bovis and S. mansoni and Compatibility of Their F1 Progeny with Biomphalaria glabrata and Bulinus truncatus

AO_SCPLOWBSTRACTC_SCPLOWTo assess the effect of anthropogenic activities on ecosystems, it is of prime importance to develop new tools enabling a rapid characterisation of ecological communities. Freshwater ecosystems are particularly impacted and threatened by human activities and need thorough attention to preserve their biodiversity and the ecological services they provide. Studying such ecosystems is generally difficult because the associated organisms are hard to sample and to monitor. We present a ready to use environmental metabarcoding diagnostic tool to characterise and monitor the freshwater malacofauna from water samples. The efficiency of this new tool was compared to a classical malacological survey at 19 sampled sites from 10 distinct rivers distributed over Corsica Island (France). Our eDNA monitoring tool demonstrated a remarkable ability to reconstitute the local malacofauna compared to the malacological survey, with 97.1% of species detection confirmed by both methods. The present tool successfully detected the 11 freshwater snail species previously reported in Corsica by malacological survey but was limited at the genus level for some species. Moreover, our malacological survey allowed an update of the local distribution of a wide diversity of freshwater snails including invasive species (i.e. Potamopyrgus antipodarum and Physa acuta) as well as snail hosts of pathogens of medical and veterinary importance (i.e. Bulinus truncatus and Galba truncatula).

/pdf/malacological-survey-in-a-bottle-of-water-a-comparative-55okj79thf.pdf

Malacological survey in a bottle of water: A comparative study between manual sampling and environmental DNA metabarcoding approaches

When two species hybridize, the two parental genomes are brought together and some alleles might interact for the first time. To the date, the extent of the transcriptomic changes in first hybrid generations, along with their functional outcome constitute an important knowledge gap especially in non-model organisms. Here we explored the molecular and functional outcomes of hybridization in first-generation hybrid between the blood fluke parasites S. haematobium and S. bovis. To this aim we fist assembled a hybrid reference transcriptome allowing us to measure gene expression in both parental species and hybrids to further described and quantified the profiles of gene expression encountered in hybrids. We identified large-scale gene expression remodeling since up to 55% of genes were differentially expressed in hybrids compared to at least one of the parental species. We further showed that intermediate level of expression in hybrids compared to parental species was the most prevalent expression profile (38% of genes) in agreement with S. haematobium x S. bovis high genomic compatibility and limited divergence. Also, among the differentially expressed genes of each of the identified profiles (intermediate, under-, over-expressed, or matching the expression of one of the parental species), only a few biological processes were found enriched without patterns being consistent through crosses and sexes. Our findings suggest that hybrid heterosis could be due to change in expression of a large portion of random genes which affect various biological processes. Author Summary When two species manage to produce a viable offspring, due to different parental genetic material, new allelic interactions might arise. We do not know much about how genes are expressed in such hybrids compared to their parental species and especially for non-model species. Here we gene expressions in first generation hybrids of two blood flukes’ parasites Schistosoma haematobium and S. bovis. We quantified and categorized gene differentially expressed in first generation hybrids. We showed that more than half the genes of the hybrids were differentially expressed compared to at least one of their parental species, hence showing major gene expression remodeling occurring during hybridization. However, the most common hybrid expression pattern was intermediate level of expression compared to parental species and various but no specific biological processes were associated with hybrids differentially expressed genes. We hypothesized that because S. haematobium and S. bovis remain very compatible, when hybridizing many non-specific genes can have their expression level remodeled hence impacting the overall molecular machinery of the offspring while still sustaining highly operational hybrids.

/pdf/schistosoma-haematobium-and-schistosoma-bovis-first-qaklyqa1.pdf

Jean-François Allienne

Papers

Changements globaux et infections parasitaires à mollusques vecteurs - Un schistosome hybride atteint l’Europe

Mating Interactions between Schistosoma bovis and S. mansoni and Compatibility of Their F1 Progeny with Biomphalaria glabrata and Bulinus truncatus

Malacological survey in a bottle of water: A comparative study between manual sampling and environmental DNA metabarcoding approaches

Schistosoma haematobium and Schistosoma bovis first generation hybrids undergo large gene expressions remodeling consistent with species compatibility

Running head: PHYLOGEOGRAPHY OF NEOBATRACHIAN PLATYHELMINTHS