Chromosomal Distribution of Genes Conferring Tolerance to Abiotic Stresses Versus That of Genes Controlling Resistance to Biotic Stresses in Plants

Tolerance to abiotic stresses caused by environmental conditions can prevent yield loss in crops for sustaining agricultural productivity [1]. Resistance to biotic stresses caused by diseases and insects can prevent or reduce yield loss in crops [2]. For each crop or plant species, there are many abiotic threats, such as changes in temperature, soil salinity/alkalinity, water shortage, and soil contaminants, as well as biotic challenges from pathogens (bacteria, viruses, and fungi), insects, and nematodes. Plants need to possess genes conferring tolerance to these abiotic stresses to adapt to the changing environment, due to global climate changes, in which they are growing. Due to the coevolution of plants and stress-causing organisms [3], plants need to possess multiple resistance genes to deal with the rise of new virulence in stress-causing organisms. Plant breeders are constantly looking for new resistance genes to combat evolving organisms that pose a threat to susceptible crops. As a result, plant geneticists have identified many resistance genes in various crops, and molecular geneticists have developed molecular markers for most of those genes. Similarly, researchers are investigating plant mechanisms and underlying genetic systems involved in plant tolerance to abiotic stresses, hoping to breed crops resilient to adverse environmental conditions. With the advent of whole-genome sequencing in many important crops, it is time to map the detailed chromosomal locations of known genes that are involved in tolerance to various abiotic stresses as well as in the resistance to biotic stresses in important plant species. In the Special Issue, Mapping Abiotic Stress-Tolerance Genes in Plants of International Journal of Molecular Sciences, 21 papers, including two reviews and 19 research articles, were published [4–24]. Eleven research articles [3,25–34] were published in the Special Issue “Mapping Plant Genes that Confer Resistance to Biotic Stress.” In this editorial, I firstly express my appreciation to all authors for their contribution to the two Special Issues. Secondly, I will compare the chromosomal distribution patterns of genes for the two types of stresses that plants faced (Tables 1 and 2). The evidence obtained supports my long-held hypothesis that genes conferring resistance to biotic stresses are more likely to be located in the distal portion of chromosomes than the proximal portion in order to adapt to the host-pest coevolution. On the other hand, abiotic-stress tolerance genes should have a lower ratio of distal to proximal distribution than that for biotic stresses to maintain the stability of genes regulating plant growth and development. Knowing the relationship between gene functions and their chromosomal distribution patterns, plant breeders can select the most appropriate and efficient method to improve crops for withstanding stresses and ensuring productivity and food security

Using practice effects for targeted trials or sub-group analysis in Alzheimer\u27s disease: How practice effects predict change over time

OBJECTIVE: To describe the presence of practice effects in persons with Alzheimer disease (AD) or mild cognitive impairment (MCI) and to evaluate how practice effects affect cognitive progression and the outcome of clinical trials. METHODS: Using data from a meta-database consisting of 18 studies including participants from the Alzheimer disease Cooperative Study (ADCS) and the Alzheimer Disease Neuroimaging Initiative (ADNI) with ADAS-Cog11 as the primary outcome, we defined practice effects based on the improvement in the first two ADAS-Cog11 scores and then estimated the presence of practice effects and compared the cognitive progression between participants with and without practice effects. The robustness of practice effects was investigated using CDR SB, an outcome independent the definition itself. Furthermore, we evaluated how practice effects can affect sample size estimation. RESULTS: The overall percent of practice effects for AD participants was 39.0% and 53.3% for MCI participants. For AD studies, the mean change from baseline to 2 years was 12.8 points for the non-practice effects group vs 7.4 for the practice effects group; whereas for MCI studies, it was 4.1 for non-practice effects group vs 0.2 for the practice effects group. AD participants without practice effects progressed 0.9 points faster than those with practice effects over a period of 2 years in CDR-SB; whereas for MCI participants, the difference is 0.7 points. The sample sizes can be different by over 35% when estimated based on participants with/without practice effects. CONCLUSION: Practice effects were prevalent and robust in persons with AD or MCI and affected the cognitive progression and sample size estimation. Planning of future AD or MCI clinical trials should account for practice effects to avoid underpower or considers target trials or stratification analysis based on practice effects

Extension rates across the northern Shanxi Grabens, China, from Quaternary geology, seismicity and geodesy

Discrepancies between geological, seismic and geodetic rates of strain can indicate that rates of crustal deformation, and hence seismic hazard, are varying through time. Previous studies in the northern Shanxi Grabens, at the northeastern corner of the Ordos Plateau in northern China, have found extension rates of anywhere between 0 and 6 mm a−1 at an azimuth of between 95° and 180°. In this paper we determine extension rates across the northern Shanxi Grabens from offset geomorphological features and a variety of Quaternary dating techniques (including new IRSL and Ar-Ar ages), a Kostrov summation using a 700 yr catalogue of historical earthquakes, and recent campaign GPS measurements. We observe good agreement between Quaternary, seismic and geodetic rates of strain, and we find that the northern Shanxi Grabens are extending at around 1–2 mm a−1 at an azimuth of ≈151°. The azimuth of extension is particularly well constrained and can be reliably inferred from catalogues of small earthquakes. We do not find evidence for any substantial variations in extension rate through time, though there is a notable seismic moment rate deficit since 1750. This deficit could indicate complex fault interactions across large regions, aseismic accommodation of deformation, or that we are quite late in the earthquake cycle with the potential for larger earthquakes in the relatively near future

Fermions, Gauge Theories, and the Sinc Function Representation for Feynman Diagrams

We extend our new approach for numeric evaluation of Feynman diagrams to integrals that include fermionic and vector propagators. In this initial discussion we begin by deriving the Sinc function representation for the propagators of spin-1/2 and spin-1 fields and exploring their properties. We show that the attributes of the spin-0 propagator which allowed us to derive the Sinc function representation for scalar field Feynman integrals are shared by fields with non-zero spin. We then investigate the application of the Sinc function representation to simple QED diagrams, including first order corrections to the propagators and the vertex.Comment: 10 pages, Latex, 9 figure

Ultraviolet Broad Absorption Features and the Spectral Energy Distribution of the QSO PG 1351+64

We present a moderate-resolution (~20 km/s) spectrum of the mini broad-absorption-line QSO PG1351+64 between 915-1180 A, obtained with the Far Ultraviolet Spectroscopic Explorer (FUSE). Additional spectra at longer wavelengths were also obtained with the HST and ground-based telescopes. Broad absorption is present on the blue wings of CIII 977, Ly-beta, OVI 1032,1038, Ly-alpha, NV 1238,1242, SiIV 1393,1402, and CIV 1548,1450. The absorption profile can be fitted with five components at velocities of ~ -780, -1049, -1629, -1833, and -3054 km/s with respect to the emission-line redshift of z = 0.088. All the absorption components cover a large fraction of the continuum source as well as the broad-line region. The OVI emission feature is very weak, and the OVI/Lyalpha flux ratio is 0.08, one of the lowest among low-redshift active galaxies and QSOs. The UV continuum shows a significant change in slope near 1050 A in the restframe. The steeper continuum shortward of the Lyman limit extrapolates well to the observed weak X-ray flux level. The absorbers' properties are similar to those of high-redshift broad absorption-line QSOs. The derived total column density of the UV absorbers is on the order of 10^21 cm^-2, unlikely to produce significant opacity above 1 keV in the X-ray. Unless there is a separate, high-ionization X-ray absorber, the QSO's weak X-ray flux may be intrinsic. The ionization level of the absorbing components is comparable to that anticipated in the broad-line region, therefore the absorbers may be related to broad-line clouds along the line of sight.Comment: 23 pages, Latex, 5 figure