Our objective was to determine the expression of the elements of the Lin28/Let-7 system, and related microRNAs (miRNAs), in early stages of human placentation and ectopic pregnancy, as a means to assess the potential role of this molecular hub in the pathogenesis of ectopic gestation. Seventeen patients suffering from tubal ectopic pregnancy (cases) and forty-three women with normal on-going gestation that desired voluntary termination of pregnancy (VTOP; controls) were recruited for the study. Embryonic tissues were subjected to RNA extraction and quantitative PCR analyses for LIN28B, Let-7a, miR-132, miR-145 and mir-323-3p were performed. Our results demonstrate that the expression of LIN28B mRNA was barely detectable in embryonic tissue from early stages of gestation and sharply increased thereafter to plateau between gestational weeks 7–9. In contrast, expression levels of Let-7, mir-132 and mir-145 were high in embryonic tissue from early gestations (≤6-weeks) and abruptly declined thereafter, especially for Let-7. Opposite trends were detected for mir-323-3p. Embryonic expression of LIN28B mRNA was higher in early stages (≤6-weeks) of ectopic pregnancy than in normal gestation. In contrast, Let-7a expression was significantly lower in early ectopic pregnancies, while miR-132 and miR-145 levels were not altered. Expression of mir-323-3p was also suppressed in ectopic embryonic tissue. We are the first to document reciprocal changes in the expression profiles of the gene encoding the RNA-binding protein, LIN28B, and the related miRNAs, Let-7a, mir-132 and mir-145, in early stages of human placentation. This finding suggests the potential involvement of LIN28B/Let-7 (de)regulated pathways in the pathophysiology of ectopic pregnancy in humans.

-Africanized honey bees (AHBs Apis mellifera) have been reported in NW Mexico since the mid 90s, but no study on the process of admixture with local European honey bees has been conducted. Morphometrics and haplotype analyses were used to investigate the frequency of African markers in honey bees from Sonora (SON), the north and south of Baja California (BCN and BCS). Morphometrics identified 42% of the samples from SON, 44% from BCN and 15% of BCS as Africanized. Honey bees from BCS had larger body size and formed a separate cluster from BCN and SON which were similar to each other. The molecular analysis revealed a higher frequency of African-derived haplotypes in SON (48%) and BCN (50%) compared to BCS (21%). The morphometric and molecular evidence suggests that the colonization of BCS by AHBs may be recent. Nest and food availability in desert areas and beekeeping practices are evoked to explain the reduced introgression of African genes into honey bee populations from this region of Mexico.Apis mellifera / Africanized honey bee / Baja California / hybridization / haplotype / morphometrics