A community-based geological reconstruction of Antarctic Ice Sheet deglaciation since the Last Glacial Maximum

A robust understanding of Antarctic Ice Sheet deglacial history since the Last Glacial Maximum is important in order to constrain ice sheet and glacial-isostatic adjustment models, and to explore the forcing mechanisms responsible for ice sheet retreat. Such understanding can be derived from a broad range of geological and glaciological datasets and recent decades have seen an upsurge in such data gathering around the continent and Sub-Antarctic islands. Here, we report a new synthesis of those datasets, based on an accompanying series of reviews of the geological data, organised by sector. We present a series of timeslice maps for 20 ka, 15 ka, 10 ka and 5 ka, including grounding line position and ice sheet thickness changes, along with a clear assessment of levels of confidence. The reconstruction shows that the Antarctic Ice sheet did not everywhere reach the continental shelf edge at its maximum, that initial retreat was asynchronous, and that the spatial pattern of deglaciation was highly variable, particularly on the inner shelf. The deglacial reconstruction is consistent with a moderate overall excess ice volume and with a relatively small Antarctic contribution to meltwater pulse 1a. We discuss key areas of uncertainty both around the continent and by time interval, and we highlight potential priorities for future work. The synthesis is intended to be a resource for the modelling and glacial geological community

Genomic and phenotypic insights from an atlas of genetic effects on DNA methylation

DNA methylation quantitative trait locus (mQTL) analyses on 32,851 participants identify genetic variants associated with DNA methylation at 420,509 sites in blood, resulting in a database of >270,000 independent mQTLs.Characterizing genetic influences on DNA methylation (DNAm) provides an opportunity to understand mechanisms underpinning gene regulation and disease. In the present study, we describe results of DNAm quantitative trait locus (mQTL) analyses on 32,851 participants, identifying genetic variants associated with DNAm at 420,509 DNAm sites in blood. We present a database of >270,000 independent mQTLs, of which 8.5% comprise long-range (trans) associations. Identified mQTL associations explain 15-17% of the additive genetic variance of DNAm. We show that the genetic architecture of DNAm levels is highly polygenic. Using shared genetic control between distal DNAm sites, we constructed networks, identifying 405 discrete genomic communities enriched for genomic annotations and complex traits. Shared genetic variants are associated with both DNAm levels and complex diseases, but only in a minority of cases do these associations reflect causal relationships from DNAm to trait or vice versa, indicating a more complex genotype-phenotype map than previously anticipated.Molecular Epidemiolog

Prevalence of antibodies to bovine paratuberculosis detected by a LAM-ELISA in Costa Rica

In Costa Rica the diagnosis of Johne's disease has been based on clinical, histopathological and bacteriological evidence and cutaneous testing; however, the prevalence of the disease at the national level is unknown. Since serum ELISA is a well accepted method of testing for antibody response to Mparatuberculosis (Collins and others 1991, Sockett and others 1992), a bovine serum bank collected in 1990 and a lipoarabinomannan antigen ELISA (LAM-ELISA) which included a preabsorption step with Mycobacteriumphlei (Sudgen and others 1987, 1989) was used.En Costa Rica el diagnóstico de la enfermedad de Johne se ha basado en pruebas clínicas, histopatológicas, bacteriológicas y pruebas cutáneas; sin embargo, se desconoce la prevalencia de la enfermedad a nivel nacional es desconocida. Dado que el ELISA en suero es un método bien aceptado de anticuerpos contra la Mparatuberculosis (Collins y otros, 1991). (Collins y otros 1991, Sockett y otros 1992), un banco de suero bovino suero bovino recogido en 1990 y un antígeno lipoarabinomanano ELISA (LAM-ELISA) que incluía un paso de preabsorción con Mycobacteriumphlei (Sudgen y otros 1987, 1989).Universidad Nacional, Costa RicaEscuela de Medicina Veterinari

Abating feral Africanized honey bees (Apis mellifera L) to enhance mating control of European queens

Abatement of local feral honey-bee colonies was tested as a method to increase the mating control of European queens produced in an Africanized area. Feral colonies within 2 km of a commercial mating apiary at Belén, Guanacaste Province, Costa Rica were targeted. Thirty-eight feral colonies were discovered in the 12.5-km2 study plot between 13 May and 6 June 1992. Abatement techniques included dispensing avermectin-ivermectin paste (applied manually to the abdominal tergites of drones captured during mating flights) and acephate-treated sucrose syrup bait (retrieved by foragers), and spraying nests directly with pyrethroids. Twenty-one of the known colonies were killed or severely weakened by treatments made between 27 May and 5 June. Mating control in pre-abatement (n = 27) and post-abatement (n = 26) queens was estimated by measuring changes in morphology and in frequencies of allozymes (malate dehydrogenase-1100 and hexokinase-1100) of worker progeny relative to reference populations of workers from local Africanized (n = 35) and imported European (n =23) colonies. Five of 23 morphological features shifted significantly toward the European form after abatement. Significantly more post-abatement colonies (85%) than pre-abatement colonies (63%) were classified by multivariate discriminant analysis as European (ie with a probability of Africanization of < 50%). Paternal frequencies of both allozymes were shifted significantly toward European frequencies following abatement; malate dehydrogenase decreased 26% and hexokinase increased 43%. Overall the results suggest that abatement may be useful in augmenting other mating control methods (eg, drone flooding and controlling mating times) but that it is probably not feasible as a unilateral approach to achieving acceptable mating control in heavily Africanized areas