Behind taxonomic variability: The functional redundancy in the tick microbiome

The taxonomic composition and diversity of tick midgut microbiota have been extensively studied in different species of the genera Rhipicephalus, Ixodes, Amblyomma, Haemaphysalis, Hyalomma, Dermacentor, Argas and Ornithodoros, while the functional significance of bacterial diversity has been proportionally less explored. In this study, we used previously published 16S amplicon sequence data sets from three Ixodes scapularis cohorts, two of uninfected nymphs, and one of larvae experimentally infected with Borrelia burgdorferi, to test the functional redundancy of the tick microbiome. We predicted the metabolic profiling of each sample using the state-of-the-art metagenomics tool PICRUSt2. The results showed that the microbiomes of all I. scapularis samples share only 80 taxa (24.6%, total 324), while out of the 342 metabolic pathways predicted, 82.7%, were shared by all the ticks. Borrelia-infected larvae lack 15.4% of pathways found in the microbiome of uninfected nymphs. Taxa contribution analysis showed that the functional microbiome of uninfected ticks was highly redundant, with, in some cases, up to 198 bacterial taxa contributing to a single pathway. However, Borrelia-infected larvae had a smaller redundancy with 6.7% of pathways provided by more than 100 genera, while 15.7–19.2% of pathways were provided by more than 100 genera in the two cohorts of uninfected ticks. In addition, we compared the functional profiles of three microbial communities from each data set, identified through a network-based approach, and we observed functional similarity between them. Based on the functional redundancy and functional similarity of the microbiome of ticks in different developmental stages and infection status, we concluded that the tick gut microbiota is a self-regulating community of very diverse bacteria contributing to a defined set of metabolic pathways and functions with yet unexplored relevance for tick fitness and/or bacterial community stability. We propose a change of focus in which the tick microbiome must be analyzed in all dimensions, highlighting their functional traits, instead of the conventional taxonomic profiling

Plantas de cobertura de solo para sistema plantio direto.

A camada de palha, sobre o solo, e essencial para o sucesso do Sistema Plantio Direto (SPD). Cria um ambiente extremamente favoravel as condicoes fisicas, quimicas e biologicas do solo contribuindo para o controle de plantas daninhas, estabilizacao da producao e recuperacao ou manutencao da qualidade do solo. O sistema de rotacao e sucessao de culturas deve ser adequado para permitir a manutencao de uma cobertura minima do solo com palha. Na escolha destas plantas, e fator decisivo conhecer a sua adaptacao a regiao e sua habilidade em crescer num ambiente menos favoravel, uma vez que as culturas comerciais sao estabelecidas nas epocas mais propicias. Isto e especialmente verdade nas condicoes de Brasil Central, onde o inverno e seco, ao passo que na regiao Sul, de inverno umido, nao existe essa limitacao e ha maior opcao de plantas adaptadas as condicoes do inverno. Existem muitas plantas de cobertura para as diferentes regioes edafoclimaticas do Brasil, e a experiencia local e decisiva nesta selecao. Em qualquer situacao, deve-se ter sempre em mente que nao existe uma planta milagrosa e que o ideal e ter mais de uma dessas especies no sistema de producao, onde busca-se aliar renda a preservacao ambiental

Nested coevolutionary networks shape the ecological relationships of ticks, hosts, and the Lyme disease bacteria of the Borrelia burgdorferi (s.l.) complex

Background: The bacteria of the Borrelia burgdorferi (s.l.) (BBG) complex constitute a group of tick-transmitted pathogens that are linked to many vertebrate and tick species. The ecological relationships between the pathogens, the ticks and the vertebrate carriers have not been analysed. The aim of this study was to quantitatively analyse these interactions by creating a network based on a large dataset of associations. Specifically, we examined the relative positions of partners in the network, the phylogenetic diversity of the tick''s hosts and its impact on BBG circulation. The secondary aim was to evaluate the segregation of BBG strains in different vectors and reservoirs. Results: BBG circulates through a nested recursive network of ticks and vertebrates that delineate closed clusters. Each cluster contains generalist ticks with high values of centrality as well as specialist ticks that originate nested sub-networks and that link secondary vertebrates to the cluster. These results highlighted the importance of host phylogenetic diversity for ticks in the circulation of BBG, as this diversity was correlated with high centrality values for the ticks. The ticks and BBG species in each cluster were not significantly associated with specific branches of the phylogeny of host genera (R 2 = 0.156, P = 0.784 for BBG; R 2 = 0.299, P = 0.699 for ticks). A few host genera had higher centrality values and thus higher importance for BBG circulation. However, the combined contribution of hosts with low centrality values could maintain active BBG foci. The results suggested that ticks do not share strains of BBG, which were highly segregated among sympatric species of ticks. Conclusions: We conclude that BBG circulation is supported by a highly redundant network. This network includes ticks with high centrality values and high host phylogenetic diversity as well as ticks with low centrality values. This promotes ecological sub-networks and reflects the high resilience of BBG circulation. The functional redundancy in BBG circulation reduces disturbances due to the removal of vertebrates as it allows ticks to fill other biotic niches

GESTIÓN DEL CONOCIMIENTO ORGANIZACIONAL EN LA UNIVERSIDAD: UN ENFOQUE DE DIRECCIÓN CENTRADO EN EL CAPITAL HUMANO (Original)

The contribution of this study to the current literature is the proposal of the theoretical fundamentals that must be assumed for the implementation of the management of organizational knowledge in the university as a strategic management approach, whose essential postulate emphasizes that people, who carry capital Human, are the most important asset these organizations have for the development of their substantive processes in function of the fulfillment of their mission. The research methods used showed that this approach is being approached from isolated perspectives, concerning information management, ICT management, or training and development of people in this context. However, the authors conclude that the same so that it can generate managerial advantages, must be conceived as a process that integrates the aforementioned perspectives and a system of processes that dynamise it and give it a strategic managerial nature.La contribución de este estudio a la literatura actual es la propuesta de los fundamentos teóricos que deben ser asumidos para la implementación de la gestión del conocimiento organizacional en la universidad como enfoque de dirección estratégica, cuyo postulado esencial enfatiza en que las personas, portadoras del capital humano, son el activo más importante con que cuentan estas organizaciones para el desarrollo de sus procesos sustantivos en función del cumplimiento de su misión. Los métodos de investigación empleados, permitieron comprobar que este enfoque está siendo abordado desde perspectivas aisladas, concernientes a la gestión de la información, a la gestión de la TIC, o a la formación y desarrollo de las personas en este contexto. Sin embargo, los autores concluyen que el mismo para que pueda generar ventajas gerenciales, debe que ser concebido como un proceso que integre las mencionadas perspectivas y un sistema de procesos que lo dinamicen y le confieran una naturaleza directiva estratégica

Rapid evolution of a novel protective symbiont into keystone taxon in Caenorhabditis elegans microbiota

Protective microbes have a major role in shaping host–pathogen interactions, but their relative importance in the structure of the host microbiota remains unclear. Here, we used a network approach to characterize the impact of a novel, experimentally evolved ‘protective microbial symbiont’ (Enterococcus faecalis) on the structure and predicted function of the natural microbiota of the model organism Caenorhabditis elegans. We used microbial network analysis to identify keystone taxa and describe the hierarchical placement of protective and non-protective symbionts in the microbiota. We found that early colonization with symbionts produce statistically significant changes in the structure of the community. Notably, only the protective E. faecalis became a keystone taxon in the nematode microbiota. Non-protective lineages of the same bacterial species remained comparatively unimportant to the community. Prediction of functional profiles in bacterial communities using PICRUSt2 showed that the presence of highly protective E. faecalis decreased the abundance of ergothioneine (EGT) biosynthesis pathway involved in the synthesis of the antioxidant molecule EGT, a potential public good. These data show that in addition to direct antagonism with virulent pathogens, keystone protective symbionts are linked to modified bacterial community structure and possible reductions in public goods, potentially driving decreased antioxidant defense. We suggest that this response could suppress infection via wholesale microbial community changes to further benefit the host. These findings extend the concept of protective symbionts beyond bodyguards to ecosystem engineers

Anti-tick microbiota vaccine impacts ixodes ricinus performance during feeding

The tick microbiota is a highly complex ensemble of interacting microorganisms. Keystone taxa, with a central role in the microbial networks, support the stability and fitness of the microbial communities. The keystoneness of taxa in the tick microbiota can be inferred from microbial co-occurrence networks. Microbes with high centrality indexes are highly connected with other taxa of the microbiota and are expected to provide important resources to the microbial community and/or the tick. We reasoned that disturbance of vector microbiota by removal of ubiquitous and abundant keystone bacteria may disrupt the tick-microbiota homeostasis causing harm to the tick host. These observations and reasoning prompted us to test the hypothesis that antibodies targeting keystone bacteria may harm the ticks during feeding on immunized hosts. To this aim, in silico analyses were conducted to identify keystone bacteria in the microbiota of Ixodes nymphs. The family Enterobacteriaceae was among the top keystone taxa identified in Ixodes microbiota. Immunization of a-1, 3-galactosyltransferase-deficient-C57BL/6 (a1, 3GT KO) mice with a live vaccine containing the Enterobacteriaceae bacterium Escherichia coli strain BL21 revealed that the production of anti-E. coli and anti-a-Gal IgM and IgG was associated with high mortality of I. ricinus nymphs during feeding. However, this effect was absent in two different strains of wild type mice, BALB/c and C57BL/6. This result concurred with a wide distribution of a-1, 3-galactosyltransferase genes, and possibly a-Gal, in Enterobacteriaceae and other bacteria of tick microbiota. Interestingly, the weight of I. ricinus nymphs that fed on E. coli-immunized C57BL/6 was significantly higher than the weight of ticks that fed on C57BL/6 immunized with a mock vaccine. Our results suggest that anti-tick microbiota vaccines are a promising tool for the experimental manipulation of vector microbiota, and potentially the control of ticks and tick-borne pathogens

Front Matter

The carbohydrate Galα1-3Galβ1-(3)4GlcNAc-R (α-Gal) is produced in all mammals except for humans, apes and old world monkeys that lost the ability to synthetize this carbohydrate. Therefore, humans can produce high antibody titers against α-Gal. Anti-α-Gal IgE antibodies have been associated with tick-induced allergy (i.e. α-Gal syndrome) and anti-α-Gal IgG/IgM antibodies may be involved in protection against malaria, leishmaniasis and Chagas disease. The α-Gal on tick salivary proteins plays an important role in the etiology of the α-Gal syndrome. However, whether ticks are able to produce endogenous α-Gal remains currently unknown. In this study, the Ixodes scapularis genome was searched for galactosyltransferases and three genes were identified as potentially involved in the synthesis of α-Gal. Heterologous gene expression in α-Gal-negative cells and gene knockdown in ticks confirmed that these genes were involved in α-Gal synthesis and are essential for tick feeding. Furthermore, these genes were shown to play an important role in tick-pathogen interactions. Results suggested that tick cells increased α-Gal levels in response to Anaplasma phagocytophilum infection to control bacterial infection. These results provided the molecular basis of endogenous α-Gal production in ticks and suggested that tick galactosyltransferases are involved in vector development, tick-pathogen interactions and possibly the etiology of α-Gal syndrome in humans.This research was supported by the Consejería de Educación, Cultura y Deportes, JCCM, Spain, project CCM17-PIC-036 (SBPLY/17/180501/000185). JJV was supported by Project FIT (Pharmacology, Immunotherapy, nanoToxicology), funded by the European Regional Development Fund.Peer Reviewe

Heat inactivated mycobacteria, alpha-Gal and zebrafish: Insights gained from experiences with two promising trained immunity inductors and a validated animal model

Trained immunity (TRAIM) may be defined as a form of memory where innate immune cells such as monocytes, macrophages, dendritic and natural killer (NK) cells undergo an epigenetic reprogramming that enhances their primary defensive capabilities. Cross-pathogen protective TRAIM can be triggered in different hosts by exposure to live microbes or microbe-derived products such as heat-inactivated Mycobacterium bovis or with the glycan α-Gal to elicit protective responses against several pathogens. We review the TRAIM paradigm using two models representing distinct scales of immune sensitization: the whole bacterial cell and one of its building blocks, the polysaccharides or glycans. Observations point out to macrophage lytic capabilities and cytokine regulation as two key components in non-specific innate immune responses against infections. The study of the TRAIM response deserves attention to better characterize the evolution of host-pathogen cooperation both for identifying the aetiology of some diseases and for finding new therapeutic strategies. In this field, the zebrafish provides a convenient and complete biological system that could help to deepen in the knowledge of TRAIM-mediated mechanisms in pathogen-host interactions.This study was funded by Junta de Comunidades de Castilla-La Mancha, Spain, and EU-FEDER, projects MYCOTRAINING SBPLY/19/180501/000174 and CCM17-PIC-036 (SBPLY/17/180501/000185), Ministerio de Ciencia e Innovación/Agencia Estatal de Investigación MCIN/AEI/10.13039/501100011033, Spain and EU-FEDER (Grant BIOGAL PID2020-116761GB-I00) and by Principado de Asturias, PCTI 2021–2023 (GRUPIN: IDI2021-000102) and FEDER. EFC holds a PhD contract from the UCLM cosupported by the European Social Fund (2020/3836).S

Mediterranean spotted fever-like illness caused by Rickettsia sibirica mongolitimonae, North Macedonia, June 2022

Mediterranean spotted fever-like illness (MSF-like illness) is a tick-borne disease caused by Rickettsia sibirica mongolitimonae first reported in France more than 25 years ago. Until today, more than 50 cases of MSF-like illness have been reported in different regions of Europe and Africa, highlighting variable clinical manifestation. Here we report a case of MSF-like illness following a bite from a Hyalomma tick in the Skopje region of North Macedonia