The heterochromatin block that functions as a rod cell microlens in owl monkeys formed within a 15 million year time span

In rod cells of many nocturnal mammals, heterochromatin localizes to the central region of the nucleus and serves as a lens to send light efficiently to the photoreceptor region. The genus Aotus (owl monkeys) is commonly considered to have undergone a shift from diurnal to nocturnal lifestyle. We recently demonstrated that rod cells of the Aotus species A. azarae possess a heterochromatin block at the center of its nucleus. The purpose of the present study was to estimate the time span in which the formation of the heterochromatin block took place. We performed three-dimensional hybridization analysis of the rod cell of another species, A. lemurinus. This analysis revealed the presence of a heterochromatin block that consisted of the same DNA components as those in A. azarae. These results indicate that the formation was complete at or before the separation of the two species. Based on the commonly accepted evolutionary history of New World monkeys and specifically of owl monkeys, the time span for the entire formation process was estimated to be 15 million years at most.

Rejection in early life is associated with high and long-lasting stress and higher incidence of infections in owl monkeys

1.SUMMARYBackgroundThe mothers of owl monkeys sometimes reject their new-borns. When this occurs in captive colonies, the rejected infants are manually raised by veterinarians, allowing them to survive. However, maternal rejection can induce chronic stress, which in turn is associated with infectious diseases. Rescued, rejected owl monkeys might experience high rates of stress and infections which go undetected.MethodologyTo test this hypothesis, we evaluated the connection between maternal rejection, stress and infections in owl monkeys (Aotus nancymaae) from the IVITA Center for Conservation and Reproduction of Primates (UNMSM, Peru). Specifically, we compared the stress rates and frequency of infection treatment in juveniles (19-24 months) rejected in the first month of life and controls. To assess stress, we compared cortisol levels in hair using a competitive ELISA and recorded behaviours using cameras. We analysed past medical treatments and medication to compare incidence of infection treatment in subjects. We then studied the correlation between the frequency of infection treatments and cortisol using a linear regression.ResultsRejected owl monkeys showed significantly higher cortisol levels (p=0.0123), a higher incidence of stereotypical behaviour and overeating (pacing p=0.0159; head twirling p=0.0476, eating p=0.0238) compared to controls. Rejected owl monkeys also received significantly more treatment for infections than controls per month lived (p=0.0009). Moreover, infection rates observed in this population were positively although weakly associated with concentration of cortisol in hair (R2=0.307, p=0.0075).ConclusionMaternal rejection in the first month of life is associated with high and long-lasting stress levels and infections in the IVITA owl monkey colony. IVITA owl monkeys will be a useful model for studying the long-term effects of early life stress at the population level.