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Background. Fatty acids (FA) likely affect human fertility at multiple levels, as deviations from physiological FA profiles are obesogenic, and FA can modify DNA methylation (DNAm). Yet, the interplay of follicular fluid (FF) and serum FA with BMI and percentage body fat (PBF) in human fertility is not completely understood. Also, associations of DNAm with fertility are largely unexplored. Methods. Reproductive parameters ranging from retrieved oocyte number to infant birth weight, were recorded in Mexican women undergoing in vitro fertilization (n=88). Multiple regression analysis sought BMI-adjusted and age-adjusted associations. Receiver operating characteristic analysis tested for discrimination between outcomes. Results. Associations of FF and serum FA were markedly distinct. While various FF FA (C16:1, C18:0, C20:2, C20:3, arachidonic acid) were significantly and inversely associated only with retrieved oocyte number, selected serum FA were associated with a broad range of pre-fertilization and post-fertilization parameters. Associations of BMI and FF FA were complex, as arachidonic acid was inversely associated with both BMI and retrieved oocyte number, while oleic acid (OA) was directly associated with BMI and PBF. Ultrasound-assessed clinical pregnancy outcome (CP) was directly associated with serum OA but inversely with its trans isomer elaidic acid (EA) and with BMI. Compounded BMI, serum EA and OA discriminated CP well (AUC=0.74). Whole blood DNA methylation was significantly associated with and a moderate predictor (AUC=0.66) of percent fertilized oocytes.Conclusions. Overall FF FA pool composition rather than FA identity may impact oocyte production and cellular memory of FF FA is lost as the oocyte exits the follicular environment. The contrasting associations of BMI, FF OA and arachidonic acid suggest that the control of oocyte homeostasis by FF FA is uncoupled from BMI. Further studies are warranted to assess the potential of compounding BMI with serum EA and OA to predict CP.

The Mexican grey wolf (Canis lupus baileyi) is a subspecies of grey wolf with unique morphologic, genetic and historical features. The Mexican grey wolf faced near-extinction during the 70s after decades of predator eradication actions. A binational, United States-Mexico, ex situ management program relying primarily on zoos has enabled a slow recovery for the population. The current population includes approximately two hundred fifty animals in captivity and more than a hundred that have been returned to the wild. One of the components of the recovery program is cryobanking gonadal tissue: initially sperm, and more recently, ovaries and oocytes. During the reproductive season of 2018 our Mexican team cryopreserved sperm obtained by electrojaculation from five males maintained in three facilities (Zoológico San Juan de Aragón, Parque Zoológico de León and Zoológico El Ocotal) and vitrified oocytes and cryopreserved ovaran tissue obtained by ovariohysterectomy in a female maintained at Zoológico de Zacango. Improved methods were introduced, such as the use of a commercial dog sperm extender that enabled superior post-thaw survival and motility rates, the measurement of testosterone and the use of ovary and oocyte cryopreservation techniques based on human procedures. We report the the successful cryopreservation of Mexican grey wolf gametes based only in local resources and expertise contributing, which will impact the population management program’s long-standing efforts to recover a flagship species of Mexican natural richness, the grey wolf. KeywordsBiobank, Oocyte vitrification, ovary cryopreservation, sperm freezing, testis, vitrification. ResumenEl lobo mexicano (Canis lupus baileyi) es una subespecie del lobo gris con características morfológicas, genéticas e históricas únicas. El lobo gris mexicano estuvo cerca de la extinción durante los años 70 después de décadas de acciones para la erradicación de predadores. El programa binacional Estados Unidos-México de manejo ex situ, dependiente principalmente de los zoológicos, ha provisto de una recuperación lenta de la población actualmente con aproximadamente doscientos cincuenta animales en cautiverio y más de una centena de regreso a la vida libre. Uno de los componentes del programa de recuperación es la criopreservación de tejido gonadal, inicialmente espermatozoides y más recientemente ovario y ovocitos. Durante la temporada reproductiva 2018 nuestro equipo en México criopreservó espermatozoides obtenidos por electroeyaculación en tres instituciones (Zoológico San Juan de Aragón, Parque Zoológico de León y Zoológico El Ocotal) y vitrificó ovocitos y criopreservó tejido ovárico después de una ovariohisterectomía en una hembra mantenida en el Zoológico de Zacango. Métodos mejorados fueron introducidos, como el uso de un diluyente comercial para perros con mejores resultados en las tasas de viabilidad y motilidad postcongelación, y el uso de técnicas de criopreservación para ovarios y ovocitos basadas en procedimientos para humanos. Reportamos la criopreservación exitosa de gametos basados solamente en recursos y conocimiento local que impactaran en el programa de manejo de la población con acciones importantes en los esfuerzos de recuperación de una especie emblemática de la riqueza natural mexicana como el lobo gris mexicano.Palabras claveBiobanco, congelación de esperma, criopreservación de ovario, vitrificación de ovocitos, testículos, vitrificación.