LDFF,the large molecular weight DNA fragmentation factor,is responsible for the large molecular weight DNA degradation during apoptosis in Xenopus egg extracts

DNA degradation is a biochemical hallmark in apoptosis. It has been demonstrated in many cell types that there are two stages of DNA fragmentation during the apoptotic execution. In the early stage, chromatin DNA is cut into large molecular weight DNA fragments, although the responsible nuclease(s) has not been recognized. In the late stage, the chromatin DNA is cleaved further into short oligonucleosomal fragments by a well-characterized nuclease in apoptosis,the caspase-activated DNase (CAD/DFF40). In this study, we demonstrate that large molecular weight DNA fragmentation also occurs in Xenopus egg extracts in apoptosis. We show that the large molecular weight DNA fragmentation factor (LDFF) is not the Xenopus CAD homolog XCAD. LDFF is activated by caspase-3. The large molecular weight DNA fragmentation activity of LDFF is Mg2+-dependent and Ca2+-independent, can occur in both acidic and neutral pH conditions and can tolerate 45℃ treatment. These results indicate that LDFF in Xenopus egg extracts might be a new DNase (or DNases) responsible for the large DNA fragmentation.

Racial and Ethnic Analysis of Birth Weight Trends among Full-Term Singleton Newborns Delivered in a Prosperous Multicultural Society

Objectives: This study aims to describe birth weight and its variations concerning maternal characteristics as well as to standardize birth weight curves for Qatari and expatriate’s newborn population born in the state of Qatar. Methods: PEARL-Peristat registry is a National maternal-neonatal observation epidemiologic database project where both maternal and neonatal cohort data are collected to evaluate specified outcomes for a population defined by a disease, conditions, or exposures. Results: Out of 50,535 singleton deliveries, only 44,178 live-born infants were included in this study. The LBW rate has remained constant since 2011 and was reported as 2.4% in males and 3.5% in females. The average total LBW was 3%. The lowest incidence of LBW was seen in maternal age between 30 - 45 years. There was a marginal increase in the incidence of LBW among mothers less than 20 years of age. The incidence of LBW among Qatari mothers was reported as 2.6%, 2.2%, and 2.4% in years 2011, 2012, 2017 respectively with a significant difference when compared to expatriates’ newborns particularly in the year 2017 (p-value < 0.001). Moreover, among Qatari newborns, there is a significant rise in the rate of LBW from 2011 to 2017, 2.9% to 4.1% (p-value ≥ 0.007). The expatriate’s population received 69 % of all maternal hospital services offered in government hospitals. Conclusion: The birth weight of newborns delivered in the state of Qatar is to a large extent consistent with the international birth weight figures for both Qatari and expatriate newborns delivered in Qatar. Low birth weight is increasing particularly among young mothers. The lowest rate of LBW was reported among mothers aged above 29 years old. Large for the date was observed among mothers older than 29 years of age.