Bernardo Sachman-Ruiz

Small ruminant production under grazing conditions plays a crucial role in the global primary sector economy. However, these animals are highly susceptible to gastrointestinal nematodes (GINs), which significantly impact their health and welfare. Given the increasing resistance to conventional anthelmintics, there is a pressing need to explore sustainable alternatives, such as plant secondary metabolites. This study aimed to identify phenolic compounds with anthelmintic activity from Tithonia diversifolia aerial parts, using Haemonchus contortus as a biological model. Egg hatching inhibition (EHI) and larval mortality assays were used to evaluate the anthelmintic activity of a hydroalcoholic extract (HA-E), an aqueous (Aq-F) and ethyl acetate fraction (EtOAc-F), and eight bioactive subfractions (TdR1-TdR8) obtained from EtOAc-F. The identification of major compounds was performed using HPLC-PDA. The E-HA and EtOAc-F achieved 100% EHI at 40 and 4 mg/mL, respectively. The subfractions TdR2 (EC₉₀ = 0.55 mg/mL), TdR3 (EC₉₀ = 0.12 mg/mL), and TdR4 (EC₉₀ = 0.26 mg/mL) exhibited the highest ovicidal activity. In the larval mortality test, EtOAc-F showed an LC₈₅ of 56.74 mg/mL. The major identified compounds included cinnamates, hydroxycinnamic acids (e.g., caffeic acid and chlorogenic acid), gallates, flavonoids (flavones and flavanones), and coumarins. These findings support the potential of T. diversifolia as a promising natural source for the control of GINs in small ruminants.

Las garrapatas son ectoparásitos hematófagos que se alimentan de animales y humanos. Se consideran un riesgo zoonótico debido a que son capaces de transmitir agentes patógenos como virus, bacterias y protozoarios. Actualmente, la distribución geográfica de las garrapatas y los patógenos que transmiten está aumentando considerablemente, produciendo una expansión significativa en zonas urbanas y semiurbanas del mundo. Así mismo, de forma global, se han identificado un total de 900 especies de garrapatas. En México, se han descrito 100 especies que comprenden a la familia Ixodidae y Argasidae con particular interés e importancia en la producción animal y salud pública. Un factor importante a considerar es el cambio climático y el impacto positivo en la distribución potencial de estas especies, lo cual ha permitido que puedan parasitar a los humanos debido a la interacción con sus hospedadores naturales causando enfermedades en regiones de clima tropical y subtropical. Adicionalmente, al momento de fijarse la garrapata a la piel facilita la transmisión de patógenos que causan enfermedades de importancia para la salud humana. Ante este escenario, es importante implementar programas de control, capacitaciones y estudios epidemiológicos con el fin de obtener un manejo eficaz y controlado de garrapatas. Finalmente, esta revisión tiene por objeto describir las principales enfermedades transmitidas por garrapatas a los humanos, los agentes causales, el diagnóstico, el tratamiento y las estrategias de prevención para reducir el riesgo de contacto y la infestación por garrapatas.

The taxane molecules extracted from the bark of trees from the Taxus genus demonstrate anticancer activity and are the main components of the drug paclitaxel. Even though a great deal of research has been carried out to produce them synthetically, this manufacturing is still dependent on Taxus cell culture. Furthermore, these processes are not suitable for steady taxane production. Therefore, the search for alternative sources of taxane production has generated growing interest amongst the scientific community. The use of endophytic fungi for the obtention of taxane constitutes an attractive alternative. Here, we present an analysis of the taxane production of several microorganisms through LC–QTOF MS/MS. We isolated 21 endophytic fungus strains, identified through sequencing of their internal transcribed spacer region (ITS). The phylogenetic analysis showed the presence of 11 different Fungus genera, namely Aspergillus, Trichoderma, Neurospora, Penicillium, Curvularia, Arcopilus, Biscogniauxia, Hypoxylon, Sordaria, Xylariales, and Gelasinospora. These fungi have been previously described to synthetize distinct metabolites of medical interest, hence supporting the study of their potential taxane production. Here, we report the production of taxadiene by some of these fungi, namely Aspergillus sp. (1.35 μg/L), TgO (0.7 μg/L), Trichoderma harzianum (0.13 μg/L), and Hypoxylon sp. (0.3 μg/L). Furthermore, we also detected the production of baccatin III, a crucial precursor component of the drug paclitaxel. This is the first report of taxane production by fungi phylogenetically related to the Arcopilus and Endoxyla genera.

In the present study, the nematicidal and acaricidal activity of three Enterobacter endophytic strains isolated from Mimosa pudica nodules was evaluated. The percentages of mortality of Enterobacter NOD4 against Panagrellus redivivus was 81.2%, and against Nacobbus aberrans 70.1%, Enterobacter NOD8 72.4% and 62.5%, and Enterobacter NOD10 64.8% and 58.7%, respectively. While against the Tyrophagus putrescentiae mite, the mortality percentages were 68.2% due to Enterobacter NOD4, 64.3% due to Enterobacter NOD8 and 77.8% due to Enterobacter NOD10. On the other hand, the ability of the three Enterobacter strains to produce indole acetic acid and phosphate solubilization, characteristics related to plant growth-promoting bacteria, was detected. Bioinformatic analysis of the genomes showed the presence of genes related to IAA production, phosphate solubilization, and nitrogen fixation. Phylogenetic analyzes of the recA gene, phylogenomics, and average nucleotide identity (ANI) allowed us to identify the strain Enterobacter NOD8 related to E. mori and Enterobacter NOD10 as E. asburiae, while Enterobacter NOD4 was identified as a possible new species of this species. The plant growth-promoting, acaricidal and nematicidal activity of the three Enterobacter strains makes them a potential agent to include in biocontrol alternatives and as growth-promoting bacteria in crops of agricultural interest.

Cattle babesiosis is a socio-economically important tick-borne disease caused by Apicomplexa protozoa of the genus Babesia that are obligate intraerythrocytic parasites. The pathogenicity of Babesia parasites for cattle is determined by the interaction with the host immune system and the presence of the parasite’s virulence genes. A Babesia bigemina strain that has been maintained under a microaerophilic stationary phase in in vitro culture conditions for several years in the laboratory lost virulence for the bovine host and the capacity for being transmitted by the tick vector. In this study, we compared the virulome of the in vitro culture attenuated Babesia bigemina strain (S) and the virulent tick transmitted parental Mexican B. bigemina strain (M). Preliminary results obtained by using the Basic Local Alignment Search Tool (BLAST) showed that out of 27 virulence genes described and analyzed in the B. bigemina virulent tick transmitted strain, only five were fully identified in the attenuated laboratory strain. In all cases, the identity and coverture of the identified genes of the wildtype strain were higher than those of the laboratory strain. This finding is putatively associated with the continuous partial loss of virulence genes in the laboratory strain after several passages of the parasite population under optimal in vitro growth conditions. The loss of virulence factors might be reflected in the absence of symptoms of the disease in cattle inoculated with the attenuated strain despite the presence of infection in the bovine host cells.

The pathogen Vibrio cholerae has multiple iron acquisition systems which allow bacteria to exploit a variety of iron sources across the different environments on which it thrives. The expression of such iron uptake systems is highly regulated, mainly by the master iron homeostasis regulator Fur but also by other mechanisms. Recently, we documented that the expression of many of the iron-responsive genes is also modulated by riboflavin. Among them, the open reading frame VCA0231, repressed both by riboflavin and iron, encodes a putative transcriptional regulator of the AraC/XylS family. Nonetheless, the genes or functions affected by this factor are unknown. In the present study, a series of in silico analyses was performed in order to identify the putative functions associated with the product of VCA0231. The STRING database predicted many iron uptake genes as functional partners for the product of VCA0231. In addition, a genomic neighborhood analysis with the Enzyme Function Initiative tools detected many Pfam families involved in iron homeostasis genetically associated with VCA0231. Moreover, a phylogenetic tree showed that other AraC/XylS members known to regulate siderophore utilization in bacteria clustered together and the product of VCA0231 localized in this cluster. This suggested that the product of VCA0231, here named IurV, is involved in the regulation of iron uptake processes. RNAseq was performed to determine the transcriptional effects of a deletion in VCA0231. A total of 52 genes were overexpressed and 21 genes were downregulated in response to the iurV deletion. Among these, several iron uptake genes and other iron homeostasis-related genes were found. Six gene ontology (GO) functional terms were enriched in the upregulated genes, of which five were related to iron metabolism. The regulatory pattern observed in the transcriptomics of a subset of genes was independently confirmed by quantitative real time PCR analysis. The results indicate that IurV is a novel regulator of the AraC/XylS family involved in the repression of iron uptake genes. Whether this effect is direct or indirect remains to be determined.

Recent advancements in genomes sequencing of members of Rickettsiaceae family have led to set a new landmark in the study of these microorganisms. Genomic analyses of Rickettsia and Orientia reveal a history of genome reduction because of the interaction with intermediate and final hosts; the evidence shows that this is an ongoing process. The gene loss, the gain, and loss of plasmids in such an easy way, among other significant processes are the evidence of the evolutionary history of this bacterial group involving reductive processes. In particular, the integrative conjugative element called REIS, was necessary in the process of adaption to an intracellular lifestyle in eukaryotes. We present a genomic focusing on Rickettsia and Orientia species, due to the animal and human importance. In this analysis, the genomic evidence shows that genomes have been extensively shuffled; however, the existence of core genes has also been conserved.

Enterococcus spp. are Gram-positive lactic acid-producing bacteria found in the intestinal tracts of animals, like mammals, birds, and arthropods. Enterococcus spp. may cause oportunistic infections in vertebrate and invertebrate hosts. We report here the draft genome sequence of Enterococcus casseliflavus PAVET15 containing 3,722,480 bp, with 80 contigs, an N ₅₀ of 179,476 bp, and 41.93% G+C content.