ABSTRACT Mycetoma is a neglected tropical disease (NTD) declared by the World Health Organization (WHO) in 2016. It is characterized by the progressive growth of nodules and granulomatous lesions on the legs, arms, and trunk. It is potentially disfiguring and causes disability or amputations in working-age people from marginalized areas. The causative agents can be fungi (eumycetoma) or actinobacteria (actinomycetoma), the latter being the most common in America and Asia. Nocardia brasiliensis is the most important causal agent of actinomycetoma in the Americas. Taxonomic problems have been reported when identifying this species, so this study aimed to detect the 16S rRNA gene variations in N. brasiliensis strains using an in silico enzymatic restriction technique. The study included strains from clinical cases of actinomycetoma in Mexico, isolated from humans and previously identified as N. brasiliensis by traditional methods. The strains were characterized microscopically and macroscopically, then subjected to DNA extraction and amplification of the 16S rRNA gene by PCR. The amplification products were sequenced, and consensus sequences were constructed and used for genetic identification and in silico restriction enzyme analysis with the New England BioLabs® NEBcutter program. All study strains were molecularly identified as N. brasiliensis; however, in silico restriction analysis detected a diversity in the restriction patterns that were finally grouped and subclassified into 7 ribotypes. This finding confirms the existence of subgroups within N. brasiliensis. The results support the need to consider N. brasiliensis as a complex species.

En este trabajo se presenta la composición y el porcentaje de ácidos grasos de tres poblaciones mexicanas de Artemia franciscana de aguas epicontinentales; dos provienen de lugares silvestres (Coahuila y San Luis Potosí) y una (Texcoco) de un cultivo alimentado con Spirulina. Para la determinación de los ácidos grasos de cada población se extrajeron los lípidos totales por el método soxhlet y se esterificaron los ácidos grasos; posteriormente, mediante cromatografía de gases se determinó la composición y el porcentaje de los mismos. Los resultados muestran que la población de Texcoco contiene los seis ácidos grasos relevantes para peces y crustáceos en la acuicultura (16:0; 16:1; 18:1; 18:2w6; 18:3w3 y 20:5w3); mientras que la Artemia de San Luis Potosí resultó ser la más pobre en estos ácidos y la población de Coahuila, aunque mostró un perfil amplio, carece del ácido linolénico, ácido esencial y precursor de otros. Al comparar estos resultados, con datos ecológicos de estas tres poblaciones publicados previamente, se puede señalar que el ambiente es determinante para este crustáceo ya que Artemia de Texcoco provenía de un cultivo alimentado con Spirulina y fue la población que mostró mayor variedad de ácidos grasos. Las otras dos poblaciones son silvestres, con hábitats diferentes, la Artemia de Coahuila vive en aguas ricas en sulfatos y la de San Luis Potosí habita en vasos evaporadores de sal construidos con piedra de cantera y por lo tanto con escaso crecimiento de fitoplancton, ambas poblaciones mostraron deficiencias de ácidos grasos esenciales, sobre todo ésta última

In this paper is presented the percentage of fatty acids composition of three Artemia franciscana Mexican populations of epicontinentals waters; two are from natural environments (Coahuila and San Luis Potosí) and one (Texcoco) is a culture fed with Spirulina. Determination of fatty acids composition in each population, was performed by extraction of total lipid by the soxhlet method and the fatty acids methyl esters were determined by gas chromatography. The results show that Artemia of Texcoco contains the six fatty acids recommended for the culture of fish and crustaceans (16:0; 16:1; 18:1; 18:2w6; 18:3w3 and 20:5w3); Artemia from San Luis Potosí showed the poorest content in these acids and Artemia from Coahuila, although it showed a wide profile, it lacks the linolenic acid. When comparing results among the three populations with ecological data that have been published, it can be pointed out that the environment is decisive for this crustacean; Artemia from Texcoco fed with Spirulina showed the largest variety of fatty acids; the other two populations are wild, and lives in different habitats, Artemia of Coahuila is found in waters that are rich in sulfates and Artemia of San Luis Potosí lives in evaporation saltern ponds, built with stone blocks and therefore with scarce phytoplankton growth. Both Artemia populations showed deficiencies in essential fatty acids, mainly the last one