Adventitious shoot propagation and cultural inputs in nursery production of a primocane-fruiting blackberry selection

Studies were conducted from January to October 2005 to determine the effect of root-cutting length on adventitious shoot yield and the management practices necessary to produce nurseryquality primocane-fruiting blackberry plants. The first portion of the study measured the average number of shoots produced from 7.6 cm- and 15.2 cm-long root cuttings of APF-44 blackberry—a primocane-fruiting genotype from the University of Arkansas breeding program. Cuttings were forced in a shallow bin containing a soilless potting medium. The average number of shoots per root cutting from 7.6 cm- and 15.2 cm- long root cuttings averaged 1.6 and 2.7 shoots per root cutting, respectively. Rooting percentage for collected shoots was nearly 100% regardless of root-cutting length source. A qualitative comparison of shoots from the two roots lengths was similar. The latter part of the study included various treatments on the rooted shoots that might affect the productivity and quality of the final product intended for nursery sales in early fall. With the aim of producing a flowering/fruiting shrub by late September, three treatments were applied: pot dimension, fertilizer rate, and shoot tipping. Fertilizer rate had the greatest impact of all treatments with the higher rate producing larger and more attractive plants. Above-normal summer/fall temperatures may explain lack of fruiting on APF-44 blackberries, but the dimension and size of some plants provided a portion of the intended aesthetic

Translation inhibition by rocaglates activates a species-specific cell death program in the emerging fungal pathogen Candida auris

Fungal infections are a major contributor to infectious disease-related deaths worldwide. Recently, global emergence of the fungal pathogen Candida auris has caused considerable concern because most C. auris isolates are resistant to fluconazole, the most commonly administered antifungal, and some isolates are resistant to drugs from all three major antifungal classes. To identify novel agents with bioactivity against C. auris, we screened 2,454 compounds from a diversity-oriented synthesis collection. Of the five hits identified, most shared a common rocaglate core structure and displayed fungicidal activity against C. auris These rocaglate hits inhibited translation in C. auris but not in its pathogenic relative Candida albicans Species specificity was contingent on variation at a single amino acid residue in Tif1, a fungal member of the eukaryotic initiation factor 4A (eIF4A) family of translation initiation factors known to be targeted by rocaglates. Rocaglate-mediated inhibition of translation in C. auris activated a cell death program characterized by loss of mitochondrial membrane potential, increased caspase-like activity, and disrupted vacuolar homeostasis. In a rocaglate-sensitized C. albicans mutant engineered to express translation initiation factor 1 (Tif1) with the variant amino acid that we had identified in C. auris, translation was inhibited but no programmed cell death phenotypes were observed. This surprising finding suggests divergence between these related fungal pathogens in their pathways of cellular responses to translation inhibition. From a therapeutic perspective, the chemical biology that we have uncovered reveals species-specific vulnerability in C. auris and identifies a promising target for development of new, mechanistically distinct antifungals in the battle against this emerging pathogen. IMPORTANCE Emergence of the fungal pathogen Candida auris has ignited intrigue and alarm within the medical community and the public at large. This pathogen is unusually resistant to antifungals, threatening to overwhelm current management options. By screening a library of structurally diverse molecules, we found that C. auris is surprisingly sensitive to translation inhibition by a class of compounds known as rocaglates (also known as flavaglines). Despite the high level of conservation across fungi in their protein synthesis machinery, these compounds inhibited translation initiation and activated a cell death program in C. auris but not in its relative Candida albicans Our findings highlight a surprising divergence across the cell death programs operating in Candida species and underscore the need to understand the specific biology of a pathogen in attempting to develop more-effective treatments against it.Published versio

The Stochastic Dynamics of Tethered Microcantilevers in a Viscous Fluid

We explore and quantify the coupled dynamics of a pair of micron scale cantilevers immersed in a viscous fluid that are also directly tethered to one another at their tips by a spring force. The spring force, for example, could represent the molecular stiffness or elasticity of a biomolecule or material tethered between the cantilevers. We use deterministic numerical simulations with the fluctuation-dissipation theorem to compute the stochastic dynamics of the cantilever pair for the conditions of experiment when driven only by Brownian motion. We validate our approach by comparing directly with experimental measurements in the absence of the tether which shows excellent agreement. Using numerical simulations, we quantify the correlated dynamics of the cantilever pair over a range of tether stiffness. Our results quantify the sensitivity of the auto- and cross-correlations of equilibrium fluctuations in cantilever displacement to the stiffness of the tether. We show that the tether affects the magnitude of the correlations which can be used in a measurement to probe the properties of an attached tethering substance. For the configurations of current interest using micron scale cantilevers in water, we show that the magnitude of the fluid coupling between the cantilevers is sufficiently small such that the influence of the tether can be significant. Our results show that the cross-correlation is more sensitive to tether stiffness than the auto-correlation indicating that a two-cantilever measurement has improved sensitivity when compared with a measurement using a single cantilever

Determination of recent sedimentation rates in Lake Michigan using Pb-210 and Cs-137

This paper describes the use of 210Pb and 137Cs radioactivity measurements to determine the rates of sedimentation in the Great Lakes. Cores from eight locations in Lake Michigan were chosen for examination to cover as wide as possible a range of sedimentation rates and representative sedimentary environments. The surficial 210Pb activity in the sediments varies between 7 and 23 pCi/g dry wt and its profile in each core shows the expected exponential decrease with depth consistent with the assumption of uniform sedimentation rate over the last hundred years and secular equilibrium between supported 210Pb and 226Ra (0.5-1.0 pCi/g dry wt). Companion measurements of 137Cs indicate that the coring technique satisfactorily recovered the uppermost levels of the deposit and that the mobility of both radionuclides within the sediment is probably small.Based on the limited number of cores analyzed to date, it appears that modern sedimentation rates are not very different from average rates for the last 7000 yr. The excess 210Pb appears to originate primarily from atmospheric fallout, but a further inventory of the 210Pb distribution over the lake bottom must be made to properly assess the significance of other sources. The spatial distributions of both 137Cs and 210Pb at certain stations suggest that the mode of transport of these radionuclides are comparable and involve attachment to settling particles. A mathematical model is developed which accounts for the observed limited mobility of both 210Pb and 137Cs in several of the cores in terms of post-depositional redistribution by physical or biological mixing processes.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/22118/1/0000545.pd

Enhanced Learnability of Flight Techniques Through the Introduction of Targeted Observation Flights with Ab-Initio through Advanced Flight Training Candidates

Flight training paradigms exist to provide a framework for instructors to relay both technical and applied knowledge to students in the most efficient way possible. Traditional methods imply the use of pre/post flight briefings coincident with flight in either an actual or simulated environments. The demonstration of maneuvers may be accomplished by the instructor followed by the student or solely by the student. In this phase, aeronautical knowledge, procedural knowledge, and performance metrics are usually assessed. With regard to enhanced learnability, the study of effectiveness becomes critical to the application of new methods that could significantly lower the amount of flight time required to meet objectives or performance criteria for a given lesson. As industry continues to evolve with the use of automation, efficient pathways from initial to advanced flight training must be assessed in order to ensure students are receiving the most out of each activity. The direct observation of flights as an in-flight observer may improve performance and enhance the learnability of certain aspects of flight training, therefore reducing the number of flight hours necessary to achieve flight training landmarks. An experiential assessment of this technique will provide insight into the use of observation flights and how they may be correlated to improvement in student retention and performance

Sedimentation and sediment accretion in Michigan coastal wetlands (U.S.A.),

Sediment transport and accretion rates were studied for three different types of coastal wetlands of Lake Michigan, U.S.A. A forested intradunal wetland (Cranberry Bog No. 1) near Stevensville, Michigan, displayed sediments in the form of detritus, and exported them. Very little sedimentary material entered by streamflow. These features of bottom-land wetlands were confirmed by radioisotope studies on cores, which showed low accretion rates of 210Pb. The mass fluxes were found to range from 0.01 to 0.2 g cm-2 yr.-1. The equivalent linear growths are 0.5-9.0 mm yr.-1. The suspended material from this wetland entered a filling shrub--bog--lake complex known as Cranberry Bog No. 2. A considerable fraction of the incoming sediments were retained in this intradunal basin wetland. This was confirmed via radioisotope studies, with cores showing higher accretion rates than in the bottom-land wetland. The river-delta wetland at Pentwater, Michigan, had little sediment trapping ability. Large amounts of water and suspended materials entered this riverine wetland, but no annual average removal was found. Radioisotope studies of cores at selected locations within this system showed little or no accretion in stream channels, and normal accumulation of organic material in non-channel areas. No net annual effect on water quality of the streams as they discharged to Lake Michigan was found. Storm events caused no notable import or export of suspended material. Presumably the sand substrate in the vicinity of all three wetlands caused runoff events to be mediated by subsurface flow through this porous soil. These three sand-based coastal wetlands appear to have little net effect on suspended solids.The 210Pb method proved more valuable than 137Cs because of the small depth of occurrence of the latter isotope. Interpretation of isotope profiles required information on acid-fraction-soluble profiles. Results are expressed in terms of mass units, since compaction of cores distorts the linear accretion rate. Delayed transfers of radionuclides appear to have occurred, perhaps as a result of integration of atmospheric inputs by the watersheds. The total activities of 210Pb and 137Cs are well correlated, which indicates particle trapping efficiency as the primary factor for affecting accumulation of both isotopes.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/24826/1/0000252.pd

White sharks exploit the sun during predatory approaches

There is no conclusive evidence of any nonhuman animal using the sun as part of its predation strategy. Here, we show that the world\u27s largest predatory fish-the white shark (Carcharodon carcharias)-exploits the sun when approaching baits by positioning the sun directly behind them. On sunny days, sharks reversed their direction of approach along an east-west axis from morning to afternoon but had uniformly distributed approach directions during overcast conditions. These results show that white sharks have sufficient behavioral flexibility to exploit fluctuating environmental features when predating. This sun-tracking predation strategy has a number of potential functional roles, including improvement of prey detection, avoidance of retinal overstimulation, and predator concealment

Sensitivity of sediment geochemical proxies to coring location and corer type in a large lake: Implications for paleolimnological reconstruction

We compared a suite of geochemical proxies in sediment cores collected in 1982, 1988, 1991, and 2003 from sites near the depocenter of Lake Erie to evaluate the reliability of paleoenvironmental reconstructions derived from lacustrine sediments. Our proxies included the concentrations and carbon isotopic compositions of organic and inorganic carbon (TOC, CaCO 3 , δ 13 C org , and δ 13 C CaCO3 ), augmented by organic C to total N ratios (C org :N tot ), δ 15 N, and carbonate δ 18 O values (δ 18 O CaCO3 ). The three coring sites were clustered within 12 km; two types of corers—a Box corer and a Benthos gravity corer—were used for the 1991 sampling campaign. The variance of most proxies was accounted for not only by temporal environmental changes but also by coring locations and corer type, indicating that sediment spatial heterogeneity and differences in sediment recovery due to the use of different corers also played a part in determining the geochemical compositions of these cores. The TOC, δ 13 C org , and δ 13 C CaCO3 values showed decadal temporal patterns that were consistent between the multiple sampling campaigns. In contrast, the δ 15 N, C org :N tot , CaCO 3 , and δ 18 O CaCO3 exhibited across‐core differences in their temporal variations, making it difficult to extract consistent environment information from different cores. Our findings suggest that in addition to temporal environmental changes, high‐resolution paleolimnological reconstruction is sensitive to many factors that could include spatial sediment heterogeneity, discontinuous sedimentation processes, bioturbation, sediment dating uncertainty, and artifacts associated with analytical and coring procedures. Therefore, multiple‐core sampling and analysis are important in reliably reconstructing environmental changes, particularly for large, heterogeneous lacustrine basins. Key Points Geochemical proxies in five sediment cores from Lake Erie were compared Geochemical record was sensitive to coring location and corer type Multiple cores are necessary for reliable paleolimnological reconstructionPeer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/107562/1/ggge20455.pd

Radioactivity in sediments of the Great Lakes: Post-depositional redistribution by deposit-feeding organisms

At two locations in southern Lake Huron (U.S.A.), twelve 35.5-cm diameter cores of fine-grained sediments were taken for comparison of the vertical distributions of 210Pb and falllout 137Cs with the distributions of benthic macroinvertebrates, mainly oligochaete worms (Tubificidae) and the amphipod, Pontoporeia affinis. Locations were selected on the basis of 210Pb distributions measured a year earlier which indicated contrasting depths of mixing of surface sediments. At one location the activity of 210Pb is uniform down to about 6 cm and 95% of total invertebrates occur within this zone; at the other location the zone of constant activity is only 3 cm deep but 90% of the invertebrates occur within it. Comparison of published tubificid defecation rates with sediment accumulation rates based on 210Pb shows that oligochaetes alone can account for mixing in one case while the effects of amphipods may be required in the case of shallower mixing. If mixing is represented as a diffusional process, eddy diffusion coefficients are at least 5.8 and 3.3 cm2 yr-1 at respective locations. In comparison with bioturbation, molecular diffusion is of minor importance in the post-depositional mobility of 137Cs. The necessity for introducing a diffusion coefficient varying continuously with depth is indicated by characteristics of the distribution of 137Cs. Biological reworking of near-surface sediments is an important process affecting radioactivity and chemical profiles in profundal deposits of this and probably other Great Lakes.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/22852/1/0000413.pd