Genomic Approach of Listeria monocytogenes Strains Isolated from Deli-Meats in Mexico.

Listeria monocytogenes is a foodborne pathogen that causes listeriosis worldwide. In México, L. monocytogenes has been identified as a hazard of deli-meats. However, the genomic analysis that supports the transmission of L. monocytogenes strains via deli-meats and its role as a source for virulence and resistance genes is lacking. Here, we present four high-quality genome drafts of L. monocytogenes strains isolated from deli-meats in Mexico. In silico typing was used to determine the serotype, lineage, clonal complexes (CC), and multilocus sequence (ST). Also, comparative genomics were performed to explore the diversity, virulence, mobile elements, antimicrobial resistant and stress survival traits. The genome sequence size of these strains measured 3.05 ± 0.07 Mb with a mean value of 37.9%G+C. All strains belonged to linage I, which was divided into two groups: 4b, CC2, ST1 (n = 3) and 1/2b, CC5, ST5 (n = 1). The pangenome and core genome contained 3493 and 2625 genes, respectively. The strains harbor the L. monocytogenes pathogenicity island-1 (LIPI-1) and the same multidrug resistance pattern (fosX, norB, mprF, lin) via in silico analysis. Comparative analysis delineated the genomes as essentially syntenic, whose genomic differences were due to phage insertion. These results expand what is known about the biology of the L. monocytogenes strains isolated from deli-meats in Mexico and warns of the risk that these strains belong to epidemic linage and harbor virulence genes linked to human disease.

Transcriptome analysis reveals molecular mechanisms underlying chloroplast biogenesis in albino Agave angustifolia plantlets.

Albino plants display partial or complete loss of photosynthetic pigments and defective thylakoid membrane development, consequently impairing plastid function and development. These distinctive attributes render albino plants excellent models for investigating chloroplast biogenesis. Despite their potential, limited exploration has been conducted regarding the molecular alterations underlying these phenotypes, extending beyond photosynthetic metabolism. In this study, we present a novel de novo transcriptome assembly of an albino somaclonal variant of Agave angustifolia Haw., which spontaneously emerged during the micropropagation of green plantlets. Additionally, RT-qPCR analysis was employed to validate the expression of genes associated with chloroplast biogenesis, and plastome copy numbers were quantified. This research aims to gain insight into the molecular disruptions affecting chloroplast development and ascertain whether the expression of critical genes involved in plastid development and differentiation is compromised in albino tissues of A. angustifolia. Our transcriptomic findings suggest that albino Agave plastids exhibit high proliferation, activation of the protein import machinery, altered transcription directed by PEP and NEP, dysregulation of plastome expression genes, reduced expression of photosynthesis-associated nuclear genes, disruption in the tetrapyrrole and carotenoid biosynthesis pathway, alterations in the plastid ribosome, and an increased number of plastome copies, among other alterations.

Pathogenic potential of non-typhoidal Salmonella serovars isolated from aquatic environments in Mexico.

BACKGROUND: River water has been implicated as a source of non-typhoidal Salmonella (NTS) serovars in Mexico. OBJECTIVE: To dissect the molecular pathogenesis and defense strategies of seven NTS strains isolated from river water in Mexico. METHODS: The genome of Salmonella serovars Give, Pomona, Kedougou, Stanley, Oranienburg, Sandiego, and Muenchen were sequenced using the whole-genome shotgun methodology in the Illumina Miseq platform. The genoma annotation and evolutionary analyses were conducted in the RAST and FigTree servers, respectively. The MLST was performed using the SRST2 tool and the comparisons between strains were clustered and visualized using the Gview server. Experimental virulence assay was included to evaluate the pathogenic potential of strains. RESULTS: We report seven high-quality draft genomes, ranging from ~ 4.61 to ~ 5.12 Mb, with a median G + C value, coding DNA sequence, and protein values of 52.1%, 4697 bp, and 4,589 bp, respectively. The NTS serovars presented with an open pan-genome, offering novel genetic content. Each NTS serovar had an indistinguishable virulotype with a core genome (352 virulence genes) closely associated with Salmonella pathogenicity; 13 genes were characterized as serotype specific, which could explain differences in pathogenicity. All strains maintained highly conserved genetic content regarding the Salmonella pathogenicity islands (1-5) (86.9-100%), fimbriae (84.6%), and hypermutation (100%) genes. Adherence and invasion capacity were confirmed among NTS strains in Caco-2 cells. CONCLUSION: Our results demonstrated the arsenal of virulence and defense molecular factors harbored on NTS serovars and highlight that environmental NTS strains are waterborne pathogens worthy of attention.

Genetic Variability in E6 and E7 Oncogenes from Human Papillomavirus Type 58 in Mexican Women.

BACKGROUND/AIMS: The study aimed to describe human papillomavirus (HPV) 58 genetic variability in E6 and E7 oncogenes from women in southeast Mexico and their phylogenetic relationships with the sequences from other geographical regions. METHODS: The E6-E7 region was amplified by nested PCR, and sequenced for identification of polymorphisms, phylogenetic trees construction, and haplotype and fixation tests. RESULTS: HPV58 positive samples were obtained from a repository, 54 were amplified, 47 sequences for the E6 gene, and 51 sequences for the E7 gene were obtained. Fifteen new E6 mutations were found; the most frequent were G279T (G57V; 29.78%), T249G (F47C; 34.04%), and A270G (Y54C; 34.04%), and previously reported c307t (63.82%). For E7, 17 known mutations were found, the most frequent were C632T (T20I), 35.30%, G760A (G63S), 35.30%, and t744g 74.50%. No significant association with the severity of the lesions was found. The polytomy in the E6 tree did not allow proposing phylogenetic relationship, and E7 tree presented defined branches. All sequences were presumably A lineage, most closely related to A1 and/or A3 sublineage. HPV58 variants are not specific for a geographical area. Population and fixation analyses suggest a possible Asian origin of HPV58 from Yucatan. The most frequent E7 haplotype in Yucatan groups with other populations of the world. CONCLUSION: The genetic variability of HPV58 from Mexico was described for the first time. E7 was more conserved than E6. New mutants present exclusively in Yucatan were identified.