The metabolome as a biomarker of aging in Drosophila melanogaster.

Many biomarkers have been shown to be associated not only with chronological age but also with functional measures of biological age. In human populations, it is difficult to show whether variation in biological age is truly predictive of life expectancy, as such research would require longitudinal studies over many years, or even decades. We followed adult cohorts of 20 Drosophila Genetic Reference Panel (DGRP) strains chosen to represent the breadth of lifespan variation, obtain estimates of lifespan, baseline mortality, and rate of aging, and associate these parameters with age-specific functional traits including fecundity and climbing activity and with age-specific targeted metabolomic profiles. We show that activity levels and metabolome-wide profiles are strongly associated with age, that numerous individual metabolites show a strong association with lifespan, and that the metabolome provides a biological clock that predicts not only sample age but also future mortality rates and lifespan. This study with 20 genotypes and 87 metabolites, while relatively small in scope, establishes strong proof of principle for the fly as a powerful experimental model to test hypotheses about biomarkers and aging and provides further evidence for the potential value of metabolomic profiles as biomarkers of aging.

Peripheral Plasmodium falciparum Infection in Early Pregnancy Is Associated With Increased Maternal Microchimerism in the Offspring.

BACKGROUND: Placental malaria has been associated with increased cord blood maternal microchimerism (MMc), which in turn may affect susceptibility to malaria in the offspring. We sought to determine the impact of maternal peripheral Plasmodium falciparum parasitemia during pregnancy on MMc and to determine whether maternal cells expand during primary parasitemia in the offspring. METHODS: We conducted a nested cohort study of maternal-infant pairs from a prior pregnancy malaria chemoprevention study. Maternal microchimerism was measured by quantitative polymerase chain reaction targeting a maternal-specific marker in genomic DNA from cord blood, first P falciparum parasitemia, and preparasitemia. Logistic and negative binomial regression were used to assess the impact of maternal peripheral parasitemia, symptomatic malaria, and placental malaria on cord blood MMc. Generalized estimating equations were used to assess predictors of MMc during infancy. RESULTS: Early maternal parasitemia was associated with increased detection of cord blood MMc (adjusted odds ratio = 3.91, P = .03), whereas late parasitemia, symptomatic malaria, and placental malaria were not. The first parasitemia episode in the infant was not associated with increased MMc relative to preparasitemia. CONCLUSIONS: Maternal parasitemia early in pregnancy may increase the amount of MMc acquired by the fetus. Future work should investigate the impact of this MMc on immune responses in the offspring.

Optimization of Chelex 100 resin-based extraction of genomic DNA from dried blood spots.

Dried blood spots (DBS) are widely utilized as part of universal newborn screening and as a means of transporting samples from field sites. We use DBS from African field sites to assess for rare maternal-fetal cell exchange during pregnancy known as microchimerism. We aimed to develop a protocol to maximize the quantity of high-quality genomic DNA (gDNA) extracted from DBS. The total gDNA yield obtained from control DBS utilizing a Qiagen-based protocol and a Chelex® 100 resin-based protocol was first compared. Variations of the Chelex® protocol were subsequently tested to develop an optimized protocol. The gDNA was quantified by qPCR targeting the human beta-globin gene. DNA yield for a given experimental condition was normalized to a Chelex® control performed on the same day, and the total yields were compared using a Student's t-test. The control Chelex® protocol yielded 590% more DNA than the QIAamp® DNA Blood Mini Kit . The absolute efficiency of the control Chelex® protocol was 54%, compared to an absolute efficiency of 9% for the QIAamp® DNA Blood Mini Kit. Modification of the Chelex® protocol to include a second heat precipitation from the same DBS increased the gDNA yield by 29% (P < 0.001). Our optimized protocol including this modification increased the absolute efficiency of extraction to 68%. The gDNA extracted using the Chelex® protocol was stable through repeated freeze-thaw cycles. In a mock microchimerism experiment, rare donor alleles at a frequency of 10 in 100 000 could be identified in gDNA from DBS extracted using the optimized Chelex® protocol. Our findings may be of significance for a diverse range of applications that utilize DBS and require high-quality DNA, including newborn screening programs, pathogen and drug resistance screening from remote field sites, forensics, and rare allele detection.