Next Steps in Business Conversion: Supporting Innovation and Entrepreneurship

Defense conversion is a major issue confronting Maineand other states that are threatened with the loss of major military and civilian defense facilities. The closing of Loring Air Force Base this year has made real to most Mainecitizens the rapidly changing nature of the state’s defense infrastructure. As the anxiety increases about the future of remaining defense facilities, both the public and private sectors are working to develop meaningful conversion programs and policies. The latter was the focus of a statewide conference on defense conversion, From Defense to Offense held last June in Portland. This article by Eric R. Pages is the first of five articles in this issue of Maine Policy Review focused on the defense conversion issue, some of which are based on presentations made at the Maine Science and Technology Foundation-sponsored conference

Gaps and forks in DNA replication: Rediscovering old models

Most current models for replication past damaged lesions envisage that translesion synthesis occurs at the replication fork. However older models suggested that gaps were left opposite lesions to allow the replication fork to proceed, and these gaps were subsequently sealed behind the replication fork. Two recent articles lend support to the idea that bypass of the damage occurs behind the fork. In the first paper, electron micrographs of DNA replicated in UV-irradiated yeast cells show regions of single-stranded DNA both at the replication forks and behind the fork, the latter being consistent with the presence of gaps in the daughter-strands opposite lesions. The second paper describes an in vitro DNA replication system reconstituted from purified bacterial proteins. Repriming of synthesis downstream from a blocked fork occurred not only on the lagging strand as expected, but also on the leading strand, demonstrating that contrary to widely accepted beliefs, leading strand synthesis does not need to be continuous

Translesion synthesis in mammalian cells

DNA damage blocks the progression of the replication fork. In order to circumvent the damaged bases, cells employ specialized low stringency DNA polymerases, which are able to carry out translesion synthesis (TLS) past different types of damage. The five polymerases used in TLS in human cells have different substrate specificities, enabling them to deal with many different types of damaged bases. PCNA plays a central role in recruiting the TLS polymerases and effecting the polymerase switch from replicative to TLS polymerase. When the fork is blocked PCNA gets ubiquitinated. This increases its affinity for the TLS polymerases, which all have novel ubiquitin-binding motifs, thereby facilitating their engagement at the stalled fork to effect TLS

External conditions drive optimal planting configurations for salt marsh restoration

Coastal salt marshes are threatened by erosion from storminess and sea level rise, with resulting losses in flood protection, wildlife and recreational space. Although more than $1 billion has been spent to reconcile losses, restoration has had varying success because of poor survival of planted patches in challenging wave and current conditions. Marsh expansion after colonization or replanting is regulated by positive and negative feedbacks between vegetation density and sediment capture. Dense vegetation stimulates sediment capture and vertical patch growth, but negatively constrains patch expansion by concentrating hydrological energy into erosion gullies along patch edges. Conversely, low-density vegetation may not simulate enough sediment capture, which increases plant dislodgement mortality. The strengths of positive and negative feedbacks will vary with wave exposure, but this has never been tested in natural conditions. We observed density-dependent sediment feedbacks, survival and lateral expansion by Sporobolus anglicus patches (0.8 × 0.8 m) planted at three levels of vegetation density, at each of three levels of wave forcing (three sites). We found interactive effects of plant density and forcing on the strength of positive and negative feedbacks. Density-dependent feedbacks only emerged in moderate and exposed conditions: classic marsh tussock patch shapes, which arise due to combined positive (vertical growth) and negative (gullies) feedbacks, were only associated with high density vegetation under exposed conditions. At high exposure, survival was enhanced by dense planting, which diverted energy away from the vegetation. In sheltered conditions, expansion was the greatest at medium density, while dense patches had high mortality and erosion. Synthesis and applications. Success of wetland restoration clearly hinges on considering interactions between environmental stress and planting density. In challenging high-exposure settings, dense planting in large patches should maximize success, as plant facilitation boosts sediment capture and negative edge effects (gullies) will represent a diminished proportion of larger patches. Yet, benefits of dense planting will switch from positive (facilitation) to negative (competition) with reduced environmental stress, when moderate-density planting might be optimal. Switches along stress gradients between positive and negative feedbacks are common across ecosystems. We call for wider integration of facilitation and stress–gradient principles into restoration design to safeguard restoration successes

Tree-ring reconstructed summer temperature anomalies for temperate East Asia since 800 C.E.

We develop a summer temperature reconstruction for temperate East Asia based on a network of annual tree-ring chronologies covering the period 800–1989 C.E. The East Asia reconstruction is the regional average of 585 individual grid point summer temperature reconstructions produced using an ensemble version of point-by-point regression. Statistical calibration and validation tests indicate that the regional average possesses sufficient overall skill to allow it to be used to study the causes of temperature variability and change over the region. The reconstruction suggests a moderately warm early medieval epoch (ca. 850–1050 C.E.), followed by generally cooler ‘Little Ice Age’ conditions (ca. 1350–1880 C.E.) and 20th century warming up to the present time. Since 1990, average temperature has exceeded past warm epochs of comparable duration, but it is not statistically unprecedented. Superposed epoch analysis reveals a volcanic forcing signal in the East Asia summer temperature reconstruction, resulting in pulses of cooler summer conditions that may persist for several years. Substantial uncertainties remain, however, particularly at lower frequencies, thus requiring caution and scientific prudence in the interpretation of this record

Combining the platinum(ii) drug candidate kiteplatin with 1,10-phenanthroline analogues

Platinum complexes of the type [Pt(PL)(AL)]2+ where PL is a derivative of 1,10-phenanthroline and AL is cis-1,4-diaminocyclohexane (1,4-dach), have been synthesised and characterised by ultraviolet spectroscopy, elemental microanalysis, nuclear magnetic resonance and X-ray crystallography. The calf-thymus DNA binding affinity of these complexes was determined by isothermal titration calorimetry, revealing higher DNA affinity than their 1S,2S-diaminocyclohexane analogues. In vitro cytotoxicity was assessed in eleven human cell lines, revealing unexpectedly low activity for the 1,4-dach complexes

An availability study for a SME

A case study of an availability analysis for a small commercial company is presented. The analysis was carried out to meet a customer requirement for the availability of an electronic ground-based system in a benign environment. Availability calculations were based on failure data provided and an explanation of the methodology and problems encountered and dealt with are discussed. The methodology includes failure classification according to MIL-HDBK-781A and how it may be used to promote and develop internal processes. A commentary on the background to reliability/availability specification is provided and a number of recommendations for monitoring reliability and availability are given

Antibacterial Activities of Selected Cameroonian Plants and Their Synergistic Effects with Antibiotics against Bacteria Expressing MDR Phenotypes

The present work was designed to assess the antibacterial properties of the methanol extracts of some Cameroonian medicinal plants and the effect of their associations with currently used antibiotics on multidrug resistant (MDR) Gram-negative bacteria overexpressing active efflux pumps. The antibacterial activities of twelve methanol extracts of medicinal plants were evaluated using broth microdilution. The results of this test showed that three extracts Garcinia lucida with the minimal inhibitory concentrations (MIC) varying from 128 to 512 μg/mL, Garcinia kola (MIC of 256 to 1024 μg/mL), and Picralima nitida (MIC of 128 to 1024 μg/mL) were active on all the twenty-nine studied bacteria including MDR phenotypes. The association of phenylalanine arginine β-naphthylamide (PAβN or efflux pumps inhibitor) to different extracts did not modify their activities. At the concentration of MIC/2 and MIC/5, the extracts of P. nitida and G. kola improved the antibacterial activities of some commonly used antibiotics suggesting their synergistic effects with the tested antibiotics. The results of this study suggest that the tested plant extracts and mostly those from P. nitida, G. lucida and G. kola could be used alone or in association with common antibiotics in the fight of bacterial infections involving MDR strains