General Medicine

Abstract  The Gemmatimonadota phylum has been widely detected in diverse natural environments, yet their specific ecological roles in many habitats remain poorly investigated. Similarly, the Candidatus ARS69 phylum has been identified only in a few habitats, and literature on their metabolic functions is relatively scarce. In the present study, we investigated the ecological significance of phyla Ca. ARS69 and Gemmatimonadota in the Arctic glacier foreland (GF) ecosystems through genome-resolved metagenomics. We have reconstructed the first high-quality metagenome-assembled genome (MAG) belonging to Ca. ARS69 and 12 other MAGs belonging to phylum Gemmatimonadota from the three different Arctic GF samples. We further elucidated these two groups phylogenetic lineage and their metabolic function through phylogenomic and pangenomic analysis. The analysis showed that all the reconstructed MAGs potentially belonged to novel species. The MAGs belonged to Ca. ARS69 consist about 8296 gene clusters, of which only about 8% of single-copy core genes (n = 980) were shared among them. The study also revealed the potential ecological role of Ca. ARS69 is associated with carbon fixation, denitrification, sulfite oxidation, and reduction biochemical processes in the GF ecosystems. Similarly, the study demonstrates the widespread distribution of different classes of Gemmatimonadota across wide ranges of ecosystems and their metabolic functions, including in the polar region. Key points • Glacier foreland ecosystems act as a natural laboratory to study microbial community structure. • We have reconstructed 13 metagenome-assembled genomes from the soil samples. • All the reconstructed MAGs belonged to novel species with different metabolic processes. • Ca. ARS69 and Gemmatimonadota MAGs were found to participate in carbon fixation and denitrification processes.

AbstractBACKGROUNDCitrus huanglongbing (HLB) is a devastating disease caused by Candidatus Liberibacter asiaticus (CLas) that affects the citrus industry. In nature, CLas relies primarily on Diaphorina citri Kuwayama as its vector for dissemination. After D. citri ingests CLas‐infected citrus, the pathogen infiltrates the insect's body, where it thrives, reproduces, and exerts regulatory control over the growth and metabolism of D. citri. Previous studies have shown that CLas alters the composition of proteins in the saliva of D. citri, but the functions of these proteins remain largely unknown.RESULTSIn this study, we detected two proteins (DcitSGP1 and DcitSGP3) with high expression levels in CLas‐infected D. citri. Quantitative PCR and Western blotting analysis showed that the two proteins were highly expressed in the salivary glands and delivered into the host plant during feeding. Silencing the two genes significantly decreased the survival rate for D. citri, reduced phloem nutrition sucking and promoted jasmonic acid (JA) defenses in citrus. By contrast, after overexpressing the two genes in citrus, the expression levels of JA pathway‐associated genes decreased.CONCLUSIONOur results suggest that CLas can indirectly suppress the defenses of citrus and support feeding by D. citri via increasing the levels of effectors in the insect's saliva. This discovery facilitates further research into the interaction between insect vectors and pathogens. © 2024 Society of Chemical Industry.

Abstract Aims Huanglongbing (citrus greening) is a plant disease putatively caused by the unculturable Gram-negative bacterium Candidatus Liberibacter asiaticus (CLas), and it has caused severe damage to citrus plantations worldwide. There are no definitive treatments for this disease, and conventional disease control techniques have shown limited efficacy. This work presents an in silico evaluation of using specifically targeting anti-microbial peptides (STAMPs) consisting of a targeting segment and an antimicrobial segment to inhibit citrus greening by inhibiting the BamA protein of CLas, which is an outer membrane protein crucial for bacterial viability. Methods and results Initially, a set of peptides with a high affinity toward BamA protein were screened and evaluated via molecular docking and molecular dynamics simulations and were verified in vitro via bio-layer interferometry (BLI). In silico studies and BLI experiments indicated that two peptides, HASP2 and HASP3, showed stable binding to BamA. Protein structures for STAMPs were created by fusing known anti-microbial peptides (AMPs) with the selected short peptides. The binding of STAMPs to BamA was assessed using molecular docking and binding energy calculations. The attachment of high-affinity short peptides significantly reduced the free energy of binding for AMPs, suggesting that it would make it easier for the STAMPs to bind to BamA. Efficacy testing in vitro using a closely related CLas surrogate bacterium showed that STAMPs had greater inhibitory activity than AMP alone. Conclusions In silico and in vitro results indicate that the STAMPs can inhibit CLas surrogate Rhizobium grahamii more effectively compared to AMPs, suggesting that STAMPs can achieve better inhibition of CLas, potentially via enhancing the site specificity of AMPs.

Abstract Background Hemotropic mycoplasmas or hemoplasmas are bacteria that attach to the erythrocyte surface and cause bovine hemoplasmosis. Two species, Mycoplasma wenyonii and Candidatus Mycoplasma haemobos, have been identified and shown to be distributed worldwide. However, there is currently no information available on hemoplasmas in cattle in the Republic of Korea. The aim of this study was to investigate the presence of hemoplasmas in Korean native cattle and to evaluate the association between hemoplasma infection and anemia. Methods One farm was selected, at which blood samples were collected from 104 Korean native cattle [grazing cattle (n = 89) and housed cattle (n = 15)]. Hemoplasmas were detected via polymerase chain reaction analysis and complete blood counts were also performed. Results The overall prevalence of hemoplasmas was 34% (35/104); 20.2% (21/104) for M. wenyonii, 3.8% (4/104) for C. M. haemobos, and 9.6% (10/104) for co-infection. Candidatus Mycoplasma haemobos was detected only in grazing cattle. Of red blood cell (RBC) parameters, C. M. haemobos-infected cattle had lower RBC and hematocrit, and higher mean cell volume than hemoplasma-negative cattle, although none of these differences were statistically significant. This is the first study to report the occurrence of M. wenyonii and C. M. haemobos. Mycoplasma wenyonii is more prevalent than C. M. haemobos in Korean native cattle. The results did not show an association between hemoplasma infection and anemia. Conclusions Considering the infection rate of hemoplasmas shown in this study, further studies, such as on the pathogenicity and clinical significance of hemoplasmas are necessary.

O Huanglongbing (HLB) destaca-se como a doença mais significativa que afeta os cultivos de citros, sendo atribuível a três espécies distintas de α-proteobactérias do gênero Candidatus Liberibacter: Ca. Liberibacter asiaticus (CLas), Ca. Liberibacter americanus (CLam) e Ca. Liberibacter africanus (CLaf). No Brasil, o principal vetor para a transmissão de CLas é o psilídeo asiático dos citros, Diaphorina citri (Kuwayama) (Hemiptera: Liviidae). Este estudo tem como objetivo verificar a presença de D. citri na jurisdição da ADAPAR - PR, a Agência de Defesa Agropecuária do Estado do Paraná, e correlacionar sua incidência com o HLB. A pesquisa abrangeu todo o estado do Paraná, incluindo municípios-chave envolvidos em diversas atividades agrícolas relacionadas ao citros, desde pomares comerciais até instalação de pesquisa. Em locais georreferenciados, agentes da ADAPAR instalaram armadilhas adesivas amarelas para monitorar D. citri nos anos de 2018 e 2019. As armadilhas, identificadas com data, local e coordenadas específicas, foram coletadas, acondicionadas em sacos plásticos transparentes e armazenadas sob refrigeração até a identificação. A classificação dos insetos capturados foi realizada utilizando uma lupa binocular. Espécimes adultas de D. citri foram submetidas à extração total de DNA, seguida pela PCR direcionada ao gene 16S rRNA de CLas. Os produtos resultantes da PCR foram analisados em gel de agarose a 2% corado com brometo de etídio. A análise da triagem e classificação de insetos confirmou a presença de D. citri em vários municípios, incluindo Altônia, Ampére, Ângulo, Antonina, Cruzeiro do Oeste, Dois Vizinhos, Faxinal Guaratuba, Iporã, Ivaiporã, Nova América da Colina, Ponta Grossa, Presidente Castelo Branco e Santa Cruz de Monte Castelo. Uma análise adicional dos dados sobre temperatura média anual e precipitação, juntamente com o IDH-Paraná, indicou que Presidente Castelo Branco teve o maior número de psilídeos coletados, totalizando 96 insetos, todos em 2018. Concentrações significativas também foram observadas em Altônia, Ampére, Cruzeiro do Oeste, Iporã, Santa Cruz de Monte Castelo e Vila Rural em Jandaia do Sul em 2018. Em 2019, foram registradas contagens elevadas de psilídeos em Ampére, Foz do Iguaçu e Ponta Grossa. Após a coleta, as amostras foram submetidas à extração de DNA e amplificação por PCR de Candidatus Liberibacter asiaticus. Embora todos os psilídeos coletados tenham testado positivo para a infecção por CLas, aqueles obtidos em armadilhas em Ponta Grossa, Paranavaí, Dois Vizinhos, Ivaiporã e Moreira Sales foram negativos. Isso destaca que fatores como temperatura, umidade relativa, precipitação e disponibilidade de planta hospedeira são determinantes críticos da ocorrência de D. citri em uma determinada região. Além disso, o estudo enfatiza o papel fundamental de uma agência eficaz de defesa agropecuária no monitoramento de doenças e pragas, especialmente em um patossistema que envolve patógeno, hospedeiro e vetor.

The increasing impact of phloem-restricted bacteria on economically important crops has led to renewed interest in understanding the pathogenesis at the genomic and histological levels of these diseases. The genus Candidatus Liberibacter is associated with economically devastating diseases, highlighting Candidatus Liberibacter asiaticus (CLas) and Candidatus Liberibacter solanaceraum (CLso) in citrus and vegetables. Plant-pathogen interaction studies are limited due to the non-culturable nature of the pathogenic species of the genus Ca. Liberibacter, as well as the lack of experimental models. The objective of this work was to implement a model for the study of bacteria of the genus Candidatus Liberibacter, using tomato-CLso as an experimental model. Through a time course analysis of the tomato-CLso infective process, it was determined that there is a direct correlation between the bacterial load and symptom development, differentiated into early, intermediate and late stages. Additionally, a comparative transcriptional analysis of antibacterial defense marker genes (PR-P1, miR160, and miR393) determined that the response of these genes in the tomato-CLso and lime-CLas pathosystems are equivalent. Our results demonstrate that the tomato-CLso system represents an important model for the study of the interaction between plants and non-cultivable phloem restricted bacteria.