Influence of tectonics on the extent of quaternary glaciation in the Andes

The extent of Quaternary glaciations varies throughout the Andes. Although the lack of radiometric dating in many places precludes precise assessment of these variations, certain spatial patterns are evident. In the N. Andes (N. of 15ºS) glacial landforms and sediments of only the ultimate and penultimate glaciations (O-isotope stages 2, 4, 6) have been identified. In the Central Andes (15-35ºS) successive glaciations since at least the mid-Quaternary have been progressively less extensive. In the Southern Andes successive glaciations since the greatest glaciation at ca. 1.2 Ma have been progressively smaller; also, the Islas Malvinas 800-1,000 km to the east became glaciated for the first time during the penultimate glaciation and developed an even greater number of nivo-glacial features during the last glaciation. The segmented nature of the oceanic and continental crust along the Pacific-South American subduction zone promotes tectonic independence of parts of the Andean chain. It is argued that variations in the extent of glaciation may be largely explained by Quaternary uplift and subsidence in different places and by precipitation-shadow effects related to elevation and air mass source

Is Gestational Diabetes Mellitus an Important Contributor to Metabolic Disorders in Trinidad and Tobago?

Objective. To investigate the incidence of Gestational Diabetes Mellitus at the Mt. Hope Women's Hospital and to describe its epidemiological pattern. Design. A retrospective observational study (Jan 2005 to Dec 2007). Setting. A teaching hospital of The University of the West Indies. Population/Sample. Pregnant women who gave birth. Methods. A sample size of 720. The variables analyzed were: age, ethnicity, BMI of mother, family history of diabetes; history of GDM, obstetric history, birth weight and APGAR score of infant. Main Outcome Measures. (1) Incidence of cases of GDM. (2) Impact of the measured variable. Chi-squares, odds ratios and logistic regression were performed. Results. The incidence of GDM was 4.31% (95% C.I. 2.31%, 6.31%). The proportion of GDM patients for the years 2005, 2006, and 2007 were 1.67%, 4.58%, and 6.67%, respectively. Age, Obesity Ethnicity, Family history of diabetes and a history of GDM were determined risk factors. Associations between GDM and (1) Mode of Delivery and (2) APGAR score of the baby were found. Discussion & Conclusion. There was an apparent increase in the incidence of GDM. Additional studies should be conducted to measure the occurrence of GDM in Trinidad and Tobago. Efforts to promote public awareness and a healthy lifestyle should be made to reverse this trend

Plucking enhanced beneath ice sheet margins: evidence from the Grampian Mountains, Scotland

Concentrations of boulders are a common feature of landscapes modified by former mid-latitude ice sheets. In many cases, the origin of the boulders can be traced in the up-ice direction to a cliff only tens to hundreds of metres distant. The implication is that a pulse of plucking and short boulder transport occurred beneath thin ice at the end of the last glacial cycle. Here we use a case study in granite bedrock in the Dee Valley, Scotland, to constrain theory and explore the factors involved in such a late phase of plucking. Plucking is influenced by ice velocity, hydrology, effective ice pressure, the extent of subglacial cavities and bedrock characteristics. The balance between these factors favours block removal beneath thin ice near a glacier margin. At Ripe Hill in the Dee Valley, a mean exposure age of 14.2 ka on blocks supports the view that the boulder train formed at the end of ice sheet glaciation. The late pulse of plucking was further enhanced by ice flowing obliquely across vertical joints and by fluctuations in sub-marginal meltwater conditions. An implication of the study is that there is the potential for a wave of ice-marginal plucking to sweep across a landscape as an ice sheet retreats

Multimodal optical mesoscopy reveals the quantity and spatial distribution of gram-positive biofilms in ex vivo tonsils

Biofilms are known to be present in tonsils, but little is known about their spatial location and size distribution throughout the tonsil. Studies of the location and distribution of biofilms in tonsil specimens have thus far been limited to either high-magnification methods such as electron microscopy, which enables high resolution imaging but only from a tiny tissue volume, or lower magnification techniques such as light microscopy, which allow imaging of larger specimens but with poor spatial resolution. To overcome these limitations, we report the use of multimodal optical mesoscopy to visualize and quantify the number and spatial distribution of gram-positive biofilms in fresh, excised paediatric tonsils. This methodology supports simultaneous imaging of both the tonsil host and biofilms in whole mounts of tissue up to 5 mm x 5 mm x 3 mm with subcellular resolution throughout. A quantitative assessment of thirty-six tonsil specimens revealed no statistically significant difference between biofilm presence on the tonsil surface and the interior of the tonsil. This new quantitative mesoscale imaging approach may prove useful in understanding the role of biofilms in tonsillar diseases and other infections

Long-term and recent changes in sea level in the Falkland Islands

Mean sea level measurements made at Port Louis in the Falkland Islands in 1981-2, 1984 and 2009, together with values from the nearby permanent tide gauge at Port Stanley, have been compared to measurements made at Port Louis in 1842 by James Clark Ross. The long-term rate of change of sea level is estimated to have been +0.75 ± 0.35 mm/year between 1842 and the early 1980s, after correction for air pressure effects and for vertical land movement due to Glacial Isostatic Adjustment (GIA). The 2009 Port Louis data set is of particular importance due to the availability of simultaneous information from Port Stanley. The data set has been employed in two ways, by providing a short recent estimate of mean sea level itself, and by enabling the effective combination of measurements at the two sites. The rate of sea level rise observed since 1992, when the modern Stanley gauge was installed, has been larger at 2.51 ± 0.58 mm/year, after correction for air pressure and GIA. This rate compares to a value of 2.79 ± 0.42 mm/year obtained from satellite altimetry in the region over the same period. Such a relatively recent acceleration in the rate of sea level rise is consistent with findings from other locations in the southern hemisphere and globall

Traits associated with innate and adaptive immunity in pigs: heritability and associations with performance under different health status conditions

There is a need for genetic markers or biomarkers that can predict resistance towards a wide range of infectious diseases, especially within a health environment typical of commercial farms. Such markers also need to be heritable under these conditions and ideally correlate with commercial performance traits. In this study, we estimated the heritabilities of a wide range of immune traits, as potential biomarkers, and measured their relationship with performance within both specific pathogen-free (SPF) and non-SPF environments. Immune traits were measured in 674 SPF pigs and 606 non-SPF pigs, which were subsets of the populations for which we had performance measurements (average daily gain), viz. 1549 SPF pigs and 1093 non-SPF pigs. Immune traits measured included total and differential white blood cell counts, peripheral blood mononuclear leucocyte (PBML) subsets (CD4+ cells, total CD8α+ cells, classical CD8αβ+ cells, CD11R1+ cells (CD8α+ and CD8α-), B cells, monocytes and CD16+ cells) and acute phase proteins (alpha-1 acid glycoprotein (AGP), haptoglobin, C-reactive protein (CRP) and transthyretin). Nearly all traits tested were heritable regardless of health status, although the heritability estimate for average daily gain was lower under non-SPF conditions. There were also negative genetic correlations between performance and the following immune traits: CD11R1+ cells, monocytes and the acute phase protein AGP. The strength of the association between performance and AGP was not affected by health status. However, negative genetic correlations were only apparent between performance and monocytes under SPF conditions and between performance and CD11R1+ cells under non-SPF conditions. Although we cannot infer causality in these relationships, these results suggest a role for using some immune traits, particularly CD11R1+ cells or AGP concentrations, as predictors of pig performance under the lower health status conditions associated with commercial farms

Mitochondrial phylogeography and demographic history of the Vicuña: implications for conservation

The vicuña (Vicugna vicugna; Miller, 1924) is a conservation success story, having recovered from near extinction in the 1960s to current population levels estimated at 275 000. However, lack of information about its demographic history and genetic diversity has limited both our understanding of its recovery and the development of science-based conservation measures. To examine the evolution and recent demographic history of the vicuña across its current range and to assess its genetic variation and population structure, we sequenced mitochondrial DNA from the control region (CR) for 261 individuals from 29 populations across Peru, Chile and Argentina. Our results suggest that populations currently designated as Vicugna vicugna vicugna and Vicugna vicugna mensalis comprise separate mitochondrial lineages. The current population distribution appears to be the result of a recent demographic expansion associated with the last major glacial event of the Pleistocene in the northern (18 to 22°S) dry Andes 14–12 000 years ago and the establishment of an extremely arid belt known as the 'Dry Diagonal' to 29°S. Within the Dry Diagonal, small populations of V. v. vicugna appear to have survived showing the genetic signature of demographic isolation, whereas to the north V. v. mensalis populations underwent a rapid demographic expansion before recent anthropogenic impacts

Phospho-epitope binding by the BRCT domains of hPTIP controls multiple aspects of the cellular response to DNA damage

Human (h)PTIP plays important but poorly understood roles in cellular responses to DNA damage. hPTIP interacts with 53BP1 tumour suppressor but only when 53BP1 is phosphorylated by ATM after DNA damage although the mechanism(s) and significance of the interaction of these two proteins are unclear. Here, we pinpoint a single ATM-phosphorylated residue in 53BP1—Ser25—that is required for binding of 53BP1 to hPTIP. Binding of phospho-Ser25 to hPTIP in vitro and in vivo requires two closely apposed pairs of BRCT domains at the C-terminus of hPTIP and neither pair alone can bind to phospho-Ser25, even though one of these BRCT pairs in isolation can bind to other ATM-phosphorylated epitopes. Mutations in 53BP1 and in hPTIP that prevent the interaction of the two proteins, render cells hypersensitive to DNA damage and weaken ATM signalling. The C-terminal BRCT domains of hPTIP are also required for stable retention of hPTIP at sites of DNA damage but this appears to be independent of binding to 53BP1. Thus, the BRCT domains of hPTIP play important roles in the cellular response to DNA damage