The effect of riverine networks on fish β-diversity patterns in a Neotropical system

Hydrobiologia - We investigated how the riverine network influences taxonomic and functional beta diversity patterns of fish assemblages in the mainstem/headwater (lateral) and upstream/downstream...     

On an unknown lamprey holotype (Petromyzon macrostomus Burmeister 1868) and the genus Exomegas Gill 1883 from South America

The taxonomy of the South American genus Exomegas Gill 1883 has been unstable owing to the unknown status of the type specimen of its type species, Petromyzon macrostomus Burmeister 1868. Here the authors announce the finding of the holotype in the Museo Argentino de Ciencias Naturales “Bernardino Rivadavia” ichthyology collection. Whereas Exomegas type species is recognized based on its holotype, Exomegas gallegensis (Smitt 1901) new status is proposed. These preliminary results resolve a century-long taxonomic uncertainty and foster a nomenclatural arrangement for a Southern Hemisphere lamprey genus.     

Cyclic environmental changes during the Early Toarcian at the Mochras Farm Borehole (Wales): a variable response of the foraminiferal community

Cyclostratigraphical analysis of the foraminiferal assemblages from the Early Toarcian at the Mochras Farm Borehole (Wales) was conducted in order to evaluate the incidence of cyclic palaeoenvironmental changes on the foraminiferal community. Different variables such as type of morphogroup, evolutionary strategy, habitat, particular taxa, diversity and abundance were studied using the Lomb–Scargle periodogram implemented in the computer program SLOMBS. A well‐developed cyclostratigraphical pattern is recognized, with the presence of several cycles (in metres) at 3.4–4/7.2–7.5/10.1–10.6/32.1–33.3/104.2–111.2/128.2/166.7, belonging to the high‐, middle‐, middle‐/low‐, and low‐frequency bands. The incidence and relevance of the cycles is found to be related to particular variables marking the global and local character of the involved processes. Cyclic changes in the organic matter input are found to be the most relevant palaeoenvironmental factor, oxygenation being secondary. A correspondence with specific Milankovitch cycles is, at present, difficult to determine.     

Bacillus Toyonensis BCT-7112T Spores as Parenteral Adjuvant of BoHV-5 Vaccine in a Murine Model

Probiotics and Antimicrobial Proteins - Bacterial spores of the genus Bacillus are being evaluated as adjuvant molecules capable of improving the immune response to vaccines. In this study, we...     

Dammarane triterpenes targeting α-synuclein: biological activity and evaluation of binding sites by molecular docking

Parkinson''s disease (PD) is a neurodegenerative disorder that affects adult people whose treatment is palliative. Thus, we decided to test three dammarane triterpenes 1, 1a, 1b, and we determined that 1 and 1a inhibit β-aggregation through thioflavine T rather than 1b. Since compound 1 was most active, we determined the interaction between α-synuclein and 1 at 50 µM (Kd) through microscale thermophoresis. Also, we observed differences in height and diameter of aggregates, and α-synuclein remains unfolded in the presence of 1. Also, aggregates treated with 1 do not provoke neurites'' retraction in N2a cells previously induced by retinoic acid. Finally, we studied the potential sites of interaction between 1 with α-synuclein fibrils using molecular modelling. Docking experiments suggest that 1 preferably interact with the site 2 of α-synuclein through hydrogen bonds with residues Y39 and T44.     

Macrophage-specific responses to human- and animal-adapted tubercle bacilli reveal pathogen and host factors driving multinucleated cell formation

The Mycobacterium tuberculosis complex (MTBC) is a group of related pathogens that cause tuberculosis (TB) in mammals. MTBC species are distinguished by their ability to sustain in distinct host populations. While Mycobacterium bovis (Mbv) sustains transmission cycles in cattle and wild animals and causes zoonotic TB, M. tuberculosis (Mtb) affects human populations and seldom causes disease in cattle. The host and pathogen determinants underlying host tropism between MTBC species are still unknown. Macrophages are the main host cell that encounters mycobacteria upon initial infection, and we hypothesised that early interactions between the macrophage and mycobacteria influence species-specific disease outcome. To identify factors that contribute to host tropism, we analysed blood-derived primary human and bovine macrophages (hMϕ or bMϕ, respectively) infected with Mbv and Mtb. We show that Mbv and Mtb reside in different cellular compartments and differentially replicate in hMϕ whereas both Mbv and Mtb efficiently replicate in bMϕ. Specifically, we show that out of the four infection combinations, only the infection of bMϕ with Mbv promoted the formation of multinucleated giant cells (MNGCs), a hallmark of tuberculous granulomas. Mechanistically, we demonstrate that both MPB70 from Mbv and extracellular vesicles released by Mbv-infected bMϕ promote macrophage multinucleation. Importantly, we extended our in vitro studies to show that granulomas from Mbv-infected but not Mtb-infected cattle contained higher numbers of MNGCs. Our findings implicate MNGC formation in the contrasting pathology between Mtb and Mbv for the bovine host and identify MPB70 from Mbv and extracellular vesicles from bMϕ as mediators of this process.     

A field test of the dilution effect hypothesis in four avian multi-host pathogens

The Dilution Effect Hypothesis (DEH) argues that greater biodiversity lowers the risk of disease and reduces the rates of pathogen transmission since more diverse communities harbour fewer competent hosts for any given pathogen, thereby reducing host exposure to the pathogen. DEH is expected to operate most intensely in vector-borne pathogens and when species-rich communities are not associated with increased host density. Overall, dilution will occur if greater species diversity leads to a lower contact rate between infected vectors and susceptible hosts, and between infected hosts and susceptible vectors. Field-based tests simultaneously analysing the prevalence of several multi-host pathogens in relation to host and vector diversity are required to validate DEH. We tested the relationship between the prevalence in house sparrows (Passer domesticus) of four vector-borne pathogens–three avian haemosporidians (including the avian malaria parasite Plasmodium and the malaria-like parasites Haemoproteus and Leucocytozoon) and West Nile virus (WNV)–and vertebrate diversity. Birds were sampled at 45 localities in SW Spain for which extensive data on vector (mosquitoes) and vertebrate communities exist. Vertebrate censuses were conducted to quantify avian and mammal density, species richness and evenness. Contrary to the predictions of DEH, WNV seroprevalence and haemosporidian prevalence were not negatively associated with either vertebrate species richness or evenness. Indeed, the opposite pattern was found, with positive relationships between avian species richness and WNV seroprevalence, and Leucocytozoon prevalence being detected. When vector (mosquito) richness and evenness were incorporated into the models, all the previous associations between WNV prevalence and the vertebrate community variables remained unchanged. No significant association was found for Plasmodium prevalence and vertebrate community variables in any of the models tested. Despite the studied system having several characteristics that should favour the dilution effect (i.e., vector-borne pathogens, an area where vector and host densities are unrelated, and where host richness is not associated with an increase in host density), none of the relationships between host species diversity and species richness, and pathogen prevalence supported DEH and, in fact, amplification was found for three of the four pathogens tested. Consequently, the range of pathogens and communities studied needs to be broadened if we are to understand the ecological factors that favour dilution and how often these conditions occur in nature.     

966. CLAVIJA DOMINGENSIS

Clavija domingensis Urb. & Ekman was one of the many Haitian endemics that were described based on collections made by the great Swedish botanist Leonard Ekman between 1924 and 1928. The species is Critically Endangered sensu IUCN (criteria c2a(i); D) and it is currently the focus of conservation initiatives in Jardin Botanique des Cayes (Haiti), Jardín Botánico Nacional Dr. Rafael M. Moscoso (Dominican Republic), and Fairchild Tropical Botanic Garden (U.S.A.). Now known from only six localities from southern Haiti, each locality only represents a single individual. The species is illustrated based on plants grown in Fairchild Tropical Botanic Garden.     

Role of extracellular matrix components in the formation of biofilms and their contribution to the biocontrol activity of Pseudomonas chlororaphis PCL1606

Pseudomonas chlororaphis PCL1606 (PcPCL1606) displays plant-colonizing features and exhibits antagonistic traits against soil-borne phytopathogenic fungi. Biofilm formation could be relevant for the PcPCL1606 lifestyle, and in this study the role of some putative extracellular matrix components (EMC; Fap-like fibre, alginate and Psl-like polysaccharides) in the biofilm architecture and biocontrol activity of this bacterium were determined. EMC such as the Fap-like fibre and alginate polysaccharide play secondary roles in biofilm formation in PcPCL1606, because they are not fundamental to its biofilm architecture in flow cell chamber, but synergistically they have shown to favour bacterial competition during biofilm formation. Conversely, studies on Psl-like polysaccharide have revealed that it may contain mannose, and that it is strongly involved in the PcPCL1606 biofilm architecture and niche competition. Furthermore, the Fap-like fibre and Psl-like exopolysaccharide play roles in early surface attachment and contribute to biocontrol activity against the white root rot disease caused by Rosellinia necatrix in avocado plants. These results constitute the first report regarding the study of the extracellular matrix of the PcPCL1606 strain and highlight the importance of a putative Fap-like fibre and Psl-like exopolysaccharide produced by PcPCL1606 in the biofilm formation process and interactions with the host plant root.