Consistent Hotspots Research Articles

RNAi-mediated endogene silencing in strawberry fruit: detection of primary and secondary siRNAs by deep sequencing.

SummaryRNA interference (RNAi) has been exploited as a reverse genetic tool for functional genomics in the nonmodel species strawberry (Fragaria × ananassa) since 2006. Here, we analysed for the first time different but overlapping nucleotide sections (>200 nt) of two endogenous genes, FaCHS (chalcone synthase) and FaOMT (O‐methyltransferase), as inducer sequences and a transitive vector system to compare their gene silencing efficiencies. In total, ten vectors were assembled each containing the nucleotide sequence of one fragment in sense and corresponding antisense orientation separated by an intron (inverted hairpin construct, ihp). All sequence fragments along the full lengths of both target genes resulted in a significant down‐regulation of the respective gene expression and related metabolite levels. Quantitative PCR data and successful application of a transitive vector system coinciding with a phenotypic change suggested propagation of the silencing signal. The spreading of the signal in strawberry fruit in the 3′ direction was shown for the first time by the detection of secondary small interfering RNAs (siRNAs) outside of the primary targets by deep sequencing. Down‐regulation of endogenes by the transitive method was less effective than silencing by ihp constructs probably because the numbers of primary siRNAs exceeded the quantity of secondary siRNAs by three orders of magnitude. Besides, we observed consistent hotspots of primary and secondary siRNA formation along the target sequence which fall within a distance of less than 200 nt. Thus, ihp vectors seem to be superior over the transitive vector system for functional genomics in strawberry fruit.

Identification of Dust Hot Spots from Multi-Resolution Remotely Sensed Data in Eastern China and Mongolia

Aeolian dust from hot spots in eastern China and Mongolia can be carried downwind to provinces in China, neighboring countries, the Pacific islands, and cities far beyond the source region. Although dust sources of huge extent have been identified in several countries, few effective countermeasures are available to combat dust emissions in arid regions. We analyzed Moderate Resolution Imaging Spectroradiometer (MODIS) images (1 km spatial resolution) that captured dust emission and dispersion during 2000–2013 to determine dust sources in eastern China and Mongolia. MODIS level 1B data and the brightness temperature difference (BTD) algorithm provided efficient discrimination of dust in this study. The derived dust information, in conjunction with the MODIS land cover product (1 km spatial resolution) and high-resolution Landsat data (30 m spatial resolution; Landsat 8, Operational Land Imager sensor) were used to identify the locations and specific sources of dust. Dust emissions appear to be sporadic in time and space, controlled by both environmental factors and human activity, although past studies have indicated that many dust emissions are from consistently active hot spots. Analysis of MODIS data indicated that three subregions of the eastern China and Mongolia source region are the dominant sources of dust: Horqin Sandy Land, Otintag Sandy Land, and the southeastern Mongolian Gobi; each of these subregions contains dust emission hot spots. We identified the locations of consistent hot spots and verified that some individual dust emissions originated from those hot spots. Our data also indicated that hot spots in southeastern Mongolia have migrated northward since 2006. Our study showed that hot spots such as dry lakes, river beds, mines, and croplands contribute to dust emissions in the eastern China and Mongolia source region. Dust hot spots coincide with regions of expanding industry in Otintag Sandy Land and in some areas of the Mongolian Gobi and with agricultural areas in Horqin Sandy Land and in some parts of the Mongolian Gobi. In Horqin and Otintag sandy lands, dust sources are associated with ephemeral water bodies. Water conservation can be an important countermeasure for initial dust emissions in the Horqin Sandy Land. In the Otintag Sandy Land, attention should be paid to human activities, for example, minimizing the effects of mining disturbances, improving dust suppression in industrial areas, and controlling water use by industry. In Mongolia, protective farming techniques and water conservation in dust emitting basins, and dust suppression and water resource protection in mining zones, must be considered to combat dust emission. MODIS level 1B data can be used to locate dust hot spots and to identify future sources of dust entrainment. Dust hot spots identified from MODIS level 1B data provide small-scale information about dust emission that can be used to locate pollution hot spots, increase understanding of the global dust cycle, and improve dust modeling.

Regional hot spots of exceptional longevity in Germany

In investigating processes of demographic change such as the longevity revolution, vanguard populations are of specific interest, as studying them is likely to improve our understanding of the underlying mechanisms driving the change. This paper explores the spatial variation in the occurrence of exceptional longevity in Germany using a large individual-level dataset covering all persons who reached ages of 105 and above in Germany in the period 1991 to 2002 (N: 1,339). The first part of our analysis reveals that many of these individuals died very close to their birth place. This finding of a localised lifetime net migration pattern supports the view that an analysis of regional variation in exceptional longevity can produce meaningful results, as a large share of the individuals were living in the same spatial context, at least early and late in life. In our analysis of regional variation in exceptional longevity, we could detect consistent hot spots in Berlin and north-western Germany. These findings are all the more notable as the areas of highest life expectancy at birth are currently located in the south of Germany.

Global trends in sediment-related research in earth science during 1992–2011: a bibliometric analysis

An effective bibliometric analysis based on the Science Citation Index-Expanded database was conducted to evaluate earth science sediment-related research from different perspectives from 1992 to 2011. The geographical influences of the authors were subsequently visualized. Sediment-related research experienced notable growth in the past two decades. Multidisciplinary geosciences and environmental sciences were the two major categories, and Environmental Science and Technology was the most active journal. Damste JSS and Schouten S were the two most prolific authors with the most high-quality articles and the greatest geographic influences. The major spatial clusters of authors overlapped quite well with regions with high economic growth in the USA, Western Europe, and Eastern Asia. The USA was the largest contributor in global sediment research with the most independent and collaborative papers, and the dominance of the USA was also confirmed in the national collaboration network. National academic output was positively associated with its economic capability. The Chinese Academy of Sciences, the US Geological Survey and the Russian Academy of Sciences were the three major contributing institutions. A keywords analysis determined that "evolution", "water", "soil(s)", and "model" were consistent hotspots in sediment research. Several keywords such as "organic-matter", "Holocene", "dynamics", "erosion", "sediment transport", "climate", and "heavy-metal" received dramatically increased attention during the study period. Through co-word analysis, significant differences were observed between environmental and multidisciplinary geosciences in terms of the most frequently used keywords, and the prevalent research topic patterns were ascertained.

Thermoregulation in polar seals: Profiling surface heat in Weddell seals

Our understanding of thermoregulation in marine mammals is ambiguous at best, due to the conflicting needs of homeostasis in air and water. Infrared imaging (IRT) has become increasingly applied to wildlife research given the non‐invasive nature of the technology, which is particularly desirable for work with species that are at risk and/or difficult to handle. Our prior work identified species‐specific patterns of heat loss by season and body condition under controlled conditions. As part of a larger study, we are assessing the use of IRT under extreme Antarctic field conditions to determine baseline and variation in thermal profiles in animals of known condition and physiological state. Weddell seals show consistent hot spots around the poorly insulated head and well‐insulated but active axilla. The trunk and neck are typically cool, whereas flippers are variable. Best fit LME showed ambient temperature, relative humidity and blubber depth to be the primary predictors of IRT signatures. Animal, body site and wind speed were not significant. Profiles were similar between wet and dry seals, however, dry animals can have surface temperatures that are only marginally above ambient, greatly minimizing heat loss. Funded by NSF.

The incidence of road-killed possums in the Ku-ring-gai area of Sydney

The spatial and temporal incidence of possum mortality on roads was monitored in Sydney’s northern suburbs over a two-year period. In total, 217 road surveys were completed, equating to over 17 000 km travelled. Almost 600 possums were observed as road-kill, with common ringtail possums (Pseudocheirus peregrinus) encountered in 87% of surveys and almost three times as often as common brushtail possums (Trichosurus vulpecula) (encountered in 52% of surveys). Roads were classified into three categories based on adjacent landscape attributes, with the road-side environment ranging from suburban housing to continuous sclerophyll forest. Clusters, or ‘hot spots’, for possum road-kill were identified using GIS. Most possum fatalities, and five out of six hot spots, occurred along roads at the bush–urban interface, suggesting high possum movement rates and/or abundance at these sites. Continuous canopy across the road was available along only 4% of the roads surveyed, forcing these arboreal marsupials to cross roads via electricity wires or at ground level, making them vulnerable to collision with vehicles. In an attempt to mitigate the possum road toll, two rope tunnel bridges were erected at canopy level above the most consistent hot spot. Subsequent monitoring of the roads was undertaken for 10 months after erection of the canopy bridge and road-kill numbers declined significantly at the site of the bridges, but also at adjacent sites throughout the study area.

Upper mantle structure from long-period differential traveltimes and free oscillation data

SUMMARY We have performed an inversion to model upper mantle structure using SS-S differential traveltime residuals in conjunction with previously reported structure coefficient estimates obtained from free oscillation frequency and attenuation measurements. The model we obtain is consistent with both the differential traveltime and structure coefficient data sets and provides nearly the same level of fit as independent inversions of these data sets. We find that a relatively simple model parametrization appears to be adequate for the data used. Upper mantle velocity perturbations and lateral variations in the radii of boundaries at 400 and 670 km depth are parametrized with spherical harmonic expansions up to degree and order 8. The expansions are fixed at specific depth knots (separated by roughly 200 km) spanning the range 20-670 km. Radial variations in velocity are obtained by linear interpolation between these depth knots. Smoothness constraints were applied as part of the inversion procedure, as well as corrections for the thickness and velocity variations of the crust. The smoothness constraints were adjusted to require a smoother structure in the bottom portion (400 to 670 km depth) of the model, where the structure coefficients have the greatest sensitivity. The upper part of the model is primarily constrained by the differential traveltime data. The resulting misfit of the final model shows that, on average, the individual structure coefficients and SS-S measurements are fit to within approximately 1.5 standard deviations. We suggest that some of the misfit is due to lower mantle structure which is not included in the modelling. The power as a function of harmonic degree for the top portion of the model (20 to 220 km depth) does not fall off significantly at the higher harmonic degrees, suggesting that the differential traveltime data may require models which include structure for degrees greater than 8. Boundary perturbations at depths of 400 and 670 km trade off strongly with the velocity variations. Allowing variations of the order of f10 km in the radii of the discontinuities at 400 and 670 km provides a slight improvement to the data fit. Comparisons of several depths of our upper mantle velocity model to the geoid show the strongest correlation at degree 2 for structure near 670 km depth. The distribution of slab structures is highly correlated to the degree 2 components of the model for depths of 200 to 670 km. Examination of the model in the vicinity of hotspots shows no consistent hotspot related signal.