Recombinant polypeptides for serology of malaria

We have evaluated 3 molecularly defined polypeptides encoded by encloned Plasmodium falciparum genes for their ability to serve as antigens for detecting antimalaria antibodies. The recombinant proteins correspond to (i) a conserved part of 190-200 kDa schizont merozoite surface component, (ii) the carboxy terminal part of the P. falciparum aldolase, and (iii) the 5·1 antigen. Antibodies were detected using enzyme-linked immunosorbent assays (ELISA) in a high percentage of sera from individuals from a malaria endemic area in The Gambia (up to 99% for some adult groups). These results were further improved, especially for detection of antimalaria antibodies in children, when a pool of all 3 polypeptides (ELISA MIXT) was used as antigen. This ELISA MIXT improves presently available assays for the detection of antimalaria antibodies directed against asexual blood stages in respect of standardization, sensitivity and specificit

Data descriptor: a global multiproxy database for temperature reconstructions of the Common Era

Reproducible climate reconstructions of the Common Era (1 CE to present) are key to placing industrial-era warming into the context of natural climatic variability. Here we present a community-sourced database of temperature-sensitive proxy records from the PAGES2k initiative. The database gathers 692 records from 648 locations, including all continental regions and major ocean basins. The records are from trees, ice, sediment, corals, speleothems, documentary evidence, and other archives. They range in length from 50 to 2000 years, with a median of 547 years, while temporal resolution ranges from biweekly to centennial. Nearly half of the proxy time series are significantly correlated with HadCRUT4.2 surface temperature over the period 1850-2014. Global temperature composites show a remarkable degree of coherence between high-and low-resolution archives, with broadly similar patterns across archive types, terrestrial versus marine locations, and screening criteria. The database is suited to investigations of global and regional temperature variability over the Common Era, and is shared in the Linked Paleo Data (LiPD) format, including serializations in Matlab, R and Python. (TABLE) Since the pioneering work of D'Arrigo and Jacoby1-3, as well as Mann et al. 4,5, temperature reconstructions of the Common Era have become a key component of climate assessments6-9. Such reconstructions depend strongly on the composition of the underlying network of climate proxies10, and it is therefore critical for the climate community to have access to a community-vetted, quality-controlled database of temperature-sensitive records stored in a self-describing format. The Past Global Changes (PAGES) 2k consortium, a self-organized, international group of experts, recently assembled such a database, and used it to reconstruct surface temperature over continental-scale regions11 (hereafter, ` PAGES2k-2013'). This data descriptor presents version 2.0.0 of the PAGES2k proxy temperature database (Data Citation 1). It augments the PAGES2k-2013 collection of terrestrial records with marine records assembled by the Ocean2k working group at centennial12 and annual13 time scales. In addition to these previously published data compilations, this version includes substantially more records, extensive new metadata, and validation. Furthermore, the selection criteria for records included in this version are applied more uniformly and transparently across regions, resulting in a more cohesive data product. This data descriptor describes the contents of the database, the criteria for inclusion, and quantifies the relation of each record with instrumental temperature. In addition, the paleotemperature time series are summarized as composites to highlight the most salient decadal-to centennial-scale behaviour of the dataset and check mutual consistency between paleoclimate archives. We provide extensive Matlab code to probe the database-processing, filtering and aggregating it in various ways to investigate temperature variability over the Common Era. The unique approach to data stewardship and code-sharing employed here is designed to enable an unprecedented scale of investigation of the temperature history of the Common Era, by the scientific community and citizen-scientists alike

A life-history approach to fertility rates in rural Gambia: evidence for trade-offs or phenotypic correlations?

Life history theory predicts that a trade-off will occur between investment in current and future reproduction. We test this hypothesis in a rural Gambian population by determining whether women who have invested heavily in reproduction in the past have lower reproductive rates in the present. We find the opposite: women of high parity for a given age have higher reproductive rates than those of lower parity. We also find no differences in fertility rate between women who began reproducing early and those who began reproducing later, nor does the sex of the child at the start of the birth interval affect subsequent fertility rate. These results suggest that phenotypic correlations are prevalent in this population. Women of high quality are able to reproduce at a high rate throughout their reproductive careers, women of low quality are only able to devote relatively little effort to reproduction throughout their lives. We have tried to control for this heterogeneity among women by including variables for phenotypic condition in our model. Condition was measured by adult height, weight and haemoglobin level. Weight (controlling for height) and haemoglobin were positively correlated with fertility rate, which reinforces the view that phenotypic correlations are prevalent. Even controlling for these variables, a positive correlation was still observed between investment in past and present reproduction. This suggests the heterogeneity between women that leads to these phenotypic correlations is not adequately captured by these measures of female body condition. In this population, some of this unexplained heterogeneity may be related to genetic variance in the ability to resist disease

The effects of kin on female fertility in rural Gambia

Human females reproduce relatively rapidly throughout their reproductive years compared to the other great apes. It has been suggested that women are able to sustain this rapid pace by co-opting family members to help raise their children. We tested the hypothesis that the presence of kin will increase the reproductive rates of women using a longitudinal database collected from rural Gambia. We found that both the husband's mother and, to a lesser extent, the husband's father increased the probability that a woman would give birth. A woman's parents, however, had no effect on her fertility rate, nor did her elder sisters or co-wives. The presence of a woman's elder brothers even decreased her probability of giving birth. There was no evidence that elder children acted as “helpers at the nest,” as the existence of living elder children slowed down rather than increased birth rates. We suggest that the increased fertility in the presence of mothers-in-law may be due to these women helping out their daughters-in-law with domestic and subsistence duties. Given that it is paternal, rather than maternal, relatives who increase fertility, social pressures on women from older kin to bear many children may also be important

Maternal grandmothers improve the nutritional status and survival of children in rural Gambia

Hypotheses for the evolution of human female life–history characteristics have often focused on the social nature of human societies, which allows women to share the burden of childcare and provisioning amongst other members of their kin group. We test the hypothesis that child health and survival probabilities will be improved by the presence of kin using a longitudinal database from rural Gambia. We find that the only kin to improve the nutritional status of children significantly (apart from mothers) are maternal grandmothers, and that this is reflected in higher survival probabilities for children with living maternal grandmothers. There is also evidence that the reproductive status of the maternal grandmother influences child nutrition, with young children being taller in the presence of non–reproductive grandmothers than grandmothers who are still reproductively active. Paternal grandmothers and male kin, including fathers, have negligible impacts on the nutritional status and survival of children

The fitness of twin mothers: evidence from rural Gambia

We used a longitudinal database from a natural fertility population in rural Gambia to compare the overall fertility of mothers who had given birth to twins at some point in their reproductive history and mothers who had only ever given birth to singletons. We found that twin mothers had shorter birth intervals, higher age-specific fertility and more surviving children than singleton mothers. This suggests that, despite the considerably higher mortality of twins found in this population, twin mothers have a fitness advantage over singleton mothers, even in the absence of modern medical care. We ran a simple simulation model to estimate the relative fitness of twin and singleton mothers, and found that the model also estimated higher fitness for twin mothers. Further, girls who went on to become twin mothers were of higher anthropometric status during their teenage years than those who became singleton mothers