Occurrence and diversity of CRISPR-Cas systems in the genus bifidobacterium

CRISPR-Cas systems constitute adaptive immune systems for antiviral defense in bacteria. We investigated the occurrence and diversity of CRISPR-Cas systems in 48 Bifidobacterium genomes to gain insights into the diversity and co-evolution of CRISPR-Cas systems within the genus and investigate CRISPR spacer content. We identified the elements necessary for the successful targeting and inference of foreign DNA in select Type II CRISPRCas systems, including the tracrRNA and target PAM sequence. Bifidobacterium species have a very high frequency of CRISPR-Cas occurrence (77%, 37 of 48). We found that many Bifidobacterium species have unusually large and diverse CRISPR-Cas systems that contain spacer sequences showing homology to foreign genetic elements like prophages. A large number of CRISPR spacers in bifidobacteria show perfect homology to prophage sequences harbored in the chromosomes of other species of Bifidobacterium, including some spacers that self-target the chromosome. A correlation was observed between strains that lacked CRISPR-Cas systems and the number of times prophages in that chromosome were targeted by other CRISPR spacers. The presence of prophage-targeting CRISPR spacers and prophage content may shed light on evolutionary processes and strain divergence. Finally, elements of Type II CRISPR-Cas systems, including the tracrRNA and crRNAs, set the stage for the development of genome editing and genetic engineering tools. © 2015 Briner et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.This study was supported by startup funds from North Carolina State University. The authors thank GenProbio srl for financial support of the Laboratory of Probiogenomics. DvS is a member of the Alimentary pharmabiotic Centre funded by Science Foundation Ireland (SFI), through the Irish Government’s National Development Plan (Grant number SFI/12/RC/2273). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.Peer Reviewe

Early break-up of the Norwegian Channel Ice Stream during the Last Glacial Maximum

We present 18 new cosmogenic ¹⁰Be exposure ages that constrain the breakup time of the Norwegian Channel Ice Stream (NCIS) and the initial retreat of the Scandinavian Ice Sheet from the Southwest coast of Norway following the Last Glacial Maximum (LGM). Seven samples from glacially transported erratics on the island Utsira, located in the path of the NCIS about 400 km up-flow from the LGM ice front position, yielded an average ¹⁰Be age of 22.0 ± 2.0 ka. The distribution of the ages is skewed with the 4 youngest all within the range 20.2–20.8 ka. We place most confidence on this cluster of ages to constrain the timing of ice sheet retreat as we suspect the 3 oldest ages have some inheritance from a previous ice free period. Three additional ages from the adjacent island Karmøy provided an average age of 20.9 ± 0.7 ka, further supporting the new timing of retreat for the NCIS. The ¹⁰Be ages from Utsira and Karmøy suggest that the ice stream broke up about 2000 years earlier than the age assignment based on ¹⁴C ages on foraminifera and molluscs from marine sediment cores. We postulate that the Scandinavian Ice Sheet flowed across the Norwegian Channel to Denmark and onto the North Sea plateau during early phases of the LGM. When the NCIS started to operate this ice supply to the North Sea was cut off and the fast flow of the NCIS also led to a lowering of the ice surface along the Norwegian Channel and thereby drawdown of the entire ice sheet. This facilitated rapid calving of the ice front in the North Sea and we reconstruct a large open bay across the entire northern North Sea by ∼20 ka based on our ¹⁰Be ages in the east and radiocarbon ages from marine cores in the west. Additional ¹⁰Be ages show that the mainland slightly east of the islands Utsira and Karmøy remained ice covered until about 16 ka, indicating almost no net ice-margin retreat for the 4000 years between 20 and 16 ka. After 16 ka the ice margin retreated quickly up-fjord

Glacier maxima in Baffin Bay during the Medieval Warm Period coeval with Norse settlement

The climatic mechanisms driving the shift from the Medieval Warm Period (MWP) to the Little Ice Age (LIA) in the North Atlantic region are debated. We use cosmogenic beryllium-10 dating to develop a moraine chronology with century-scale resolution over the last millennium and show that alpine glaciers in Baffin Island and western Greenland were at or near their maximum LIA configurations during the proposed general timing of the MWP. Complimentary paleoclimate proxy data suggest that the western North Atlantic region remained cool, whereas the eastern North Atlantic region was comparatively warmer during the MWP—a dipole pattern compatible with a persistent positive phase of the North Atlantic Oscillation. These results demonstrate that over the last millennium, glaciers approached their eventual LIA maxima before what is considered the classic LIA in the Northern Hemisphere. Furthermore, a relatively cool western North Atlantic region during the MWP has implications for understanding Norse migration patterns during the MWP. Our results, paired with other regional climate records, point to nonclimatic factors as contributing to the Norse exodus from the western North Atlantic region

Holocene evolution of the western Greenland Ice Sheet: Assessinggeophysical ice-sheet models with geological reconstructions ofice-margin change

Geophysical ice-sheet models are used to predict future ice-sheet dimensions and, in turn, these projections help estimate the magnitude of eustatic sea-level rise. Before models can confidently predict ice-sheet behavior, they must be validated by being able to duplicate the geological record of ice-sheet change. Here, we review geological records of Greenland Ice Sheet (GrIS) change, with emphasis on the warmer-than-present middle Holocene, and compare these records to published studies that numerically simulate GrIS behavior through the Holocene. Geological records are concentrated in West and Southwest Greenland, which are also the regions where the GrIS margin likely experienced the greatest distance of inland retreat during the middle Holocene. Several records spanning from Melville Bugt to Jakobshavn Isfjord in western Greenland indicate the GrIS achieved its minimum extent between ~5 and 3 ka, and farther south in the Kangerlussuaq region, new data presented here indicate the ice margin reached its minimum extent between ~4.2 and 1.8 ka. In the Narsarsuaq region in southern Greenland, the GrIS likely achieved its minimum configuration between ~7 and 4 ka. We highlight key similarities and discrepancies between these reconstructions and model results, and finally, we suggest that despite some degree of inland retreat, the West and Southwest GrIS margin remained relatively stable and close to its current position through the Holocene thermal maximum

If it does take a village to raise a child, how should the village do it? Insights from the kids in places initiative

Cross-sector collaborations are some of the strategies used to promote early childhood development and wellbeing. Without these collaborations, key services for families with young children may be missed or even duplicated. By drawing from experiences in Canada and Italy, we share findings from a study that aimed to understand the factors that make cross-sector collaborations (CSC) succeed or fail. Specifically, the study focused on understanding how CSC promoting early child development are created, maintained, and consolidated; and on identifying the social psychological, organizational, and economic aspects of CSC that help or hinder their functioning. Based on qualitative analysis of data gathered from four focus groups and thirteen interviews conducted across seven Canadian and Italian communities, we conclude that the success of CSC depend of a series of factors that transcend context, language and culture

A 10Be chronology of south-western Scandinavian Ice Sheet history during the Lateglacial period

We present 34 new cosmogenic 10Be exposure ages that constrain the Lateglacial (Bølling–Preboreal) history of the Scandinavian Ice Sheet in the Lysefjorden region, south-western Norway. We find that the classical Lysefjorden moraines, earlier thought to be entirely of Younger Dryas age, encompass three adjacent moraines attributed to at least two ice sheet advances of distinctly different ages. The 10Be age of the outermost moraine (14.0 ± 0.6 ka; n = 4) suggests that the first advance is of Older Dryas age. The innermost moraine is at least 2000 years younger and was deposited near the end of the Younger Dryas (11.4 ± 0.4 ka; n = 7). After abandonment of the innermost Lysefjorden Moraine, the ice front receded quickly towards the head of the fjord, where recession was interrupted by an advance that deposited the Trollgaren Moraine at 11.3 ± 0.9 ka (n = 5). 10Be ages from the inboard side of the Trollgaren Moraine suggest final retreat by 10.7 ± 0.3 ka (n = 7). The late culmination of the Younger Dryas advance contrasts with other sectors of the Scandinavian Ice Sheet where the margin appears to have culminated earlier during the Younger Dryas stadial, followed by retreat during the middle and late part of the Younger Dryas

LENS Deposition of Complex Geometries

The Laser Engineered Net Shaping (LENS®) system at Sandia National Laboratories, a laser-based direct metal deposition process, was recently used for the fabrication of a complex prototype. The LENS process involved the challenges of adjacent areas of thick and thin cross section, overhanging unsupported features, high aspect ratios, and a hemispherical substrate. These challenges were overcome through the use of closed-loop weld pool control, height monitoring, a strong understanding of build parameters, and unique process planning strategies. The near-net shape LENS part was completed with annealing and conventional machining to produce the complex components in a reduced timeframe.Mechanical Engineerin