Over the last 70 yr, more than 12,000 maize accessions have been screened for their level of resistance to western corn rootworm, Diabrotica virgifera virgifera (LeConte; Coleoptera: Chrysomelidae), ...larval feeding. Less than 1% of this germplasm was selected for initiating recurrent selection or other breeding programs. Selected genotypes were mostly characterized by large root systems and superior root regrowth after root damage caused by western corn rootworm larvae. However, no hybrids claiming native (i.e., host plant) resistance to western corn rootworm larval feeding are currently commercially available. We investigated the genetic basis of western corn rootworm resistance in maize materials with improved levels of resistance using linkage disequilibrium mapping approaches. Two populations of topcrossed doubled haploid maize lines (DHLs) derived from crosses between resistant and susceptible maize lines were evaluated for their level of resistance in three to four different environments. For each DHL topcross an average root damage score was estimated and used for quantitative trait loci (QTL) analysis. We found genomic regions contributing to western corn rootworm resistance on all maize chromosomes, except for chromosome 4. Models fitting all QTL simultaneously explained about 30 to 50% of the genotypic variance for root damage scores in both mapping populations. Our findings confirm the complex genetic structure of host plant resistance against western corn rootworm larval feeding in maize. Interestingly, three of these QTL regions also carry genes involved in ascorbate biosynthesis, a key compound we hypothesize is involved in the expression of western corn rootworm resistance.
Encephalitozoon cuniculi is an important microsporidian pathogen that is considered an emergent, zoonotic, and opportunistic. It infects both domestic and laboratory rabbits, generating severe ...chronic interstitial and granulomatous nephritis with fibrosis and granulomatous encephalitis. Encephalitozoonosis is diagnosed in paraffin-embedded sections by examining the spores in the host tissues. The spores are difficult to observe when the samples are stained with hematoxylin and eosin (H&E), particularly when there is an inflammatory reaction and tissue damage. The spores are easily mistaken for other microorganisms, such as fungi (yeasts), protozoa, and bacteria. In our study, we used kidney samples from E. cuniculi–positive rabbits and employed 14 recommended histologic stains for detecting microsporidia spores: alcian blue, calcofluor white, Giemsa, Gram, Grocott, H&E, Luna, Luxol fast blue, Masson trichrome, modified trichrome stain (MTS), periodic acid–Schiff reaction (PAS), Van Gieson, Warthin–Starry (WS), and Ziehl–Neelsen (ZN).We concluded that MTS and Gram stain, detected by light microscopy, and calcofluor white stain, detected by ultraviolet light microscopy, are the best stains for detecting spores of E. cuniculi in paraffin-embedded tissues from infected rabbits. These stains were superior to WS, ZN, Giemsa, and PAS for identifying spores without background “noise” or monochromatic interference. Also, they allow individual spores to be discerned in paraffin-embedded tissues. MTS allows observation of the polar tube, polaroplast, and posterior vacuole, the most distinctive parts of the spore.
The initial colonization of the Americas remains a highly debated topic
, and the exact timing of the first arrivals is unknown. The earliest archaeological record of Mexico-which holds a key ...geographical position in the Americas-is poorly known and understudied. Historically, the region has remained on the periphery of research focused on the first American populations
. However, recent investigations provide reliable evidence of a human presence in the northwest region of Mexico
, the Chiapas Highlands
, Central Mexico
and the Caribbean coast
during the Late Pleistocene and Early Holocene epochs. Here we present results of recent excavations at Chiquihuite Cave-a high-altitude site in central-northern Mexico-that corroborate previous findings in the Americas
of cultural evidence that dates to the Last Glacial Maximum (26,500-19,000 years ago)
, and which push back dates for human dispersal to the region possibly as early as 33,000-31,000 years ago. The site yielded about 1,900 stone artefacts within a 3-m-deep stratified sequence, revealing a previously unknown lithic industry that underwent only minor changes over millennia. More than 50 radiocarbon and luminescence dates provide chronological control, and genetic, palaeoenvironmental and chemical data document the changing environments in which the occupants lived. Our results provide new evidence for the antiquity of humans in the Americas, illustrate the cultural diversity of the earliest dispersal groups (which predate those of the Clovis culture) and open new directions of research.
Steam reforming chemical looping (CL-SMR) using mixed iron oxides has the potential as an alternative to the current partial oxidation (POX) and steam reforming (SMR) processes. In this study, the ...use of FeMoO
4
, Fe
2
ZnO
4
and Fe
2
MnO
4
as oxygen carriers (OC) under the CL-SMR reaction scheme was proposed to overcome the current disadvantages of methane POX and SMR processes. This research is aimed at finding potential iron-based metal oxides for the production of syngas, which can be regenerated under favorable conditions in steam, while producing H
2
. Thermodynamic evaluation and process simulation of the CL-SMR reaction scheme using mixed iron-oxides was performed. Results indicate that FeMoO
4
, Fe
2
ZnO
4
and Fe
2
MnO
4
generated syngas at 750 °C, 730 °C and 600 °C, respectively. However, FeMoO
4
was not fully regenerated under favorable conditions, whereas Fe
2
ZnO
4
and Fe
2
MnO
4
were completely regenerated at 440 °C and 640 °C, respectively. Fe
2
MnO
4
showed the most favorable operating conditions among the studied OC towards the production of syngas. Preliminary experimental studies involved the synthesis of Fe
2
MnO
4
through a solid-state method using Fe
2
O
3
and MnO as precursors, which was characterized
via
XRD, while its redox performance was evaluated in a TGA CH
4
-H
2
O redox cycle, with reduction using CH
4
followed by the steam oxidation of OC. Results indicate that both reduction with methane and oxidation with water vapor using Fe
2
MnO
4
present reasonable reduction-oxidation rates to be used in the CL-SMR reaction scheme, verifying the feasibility of the theoretical study performed in the present investigation.
Chemical looping steam reforming (CL-SMR) thermodynamic analysis and process simulation using Fe
2
MnO
4
as an oxygen carrier.
•Sensory panelists detected differences in texture among 10 melon genotypes.•Instrumental assessments detected differences in texture among 10 melon genotypes.•Instrumental parameters can predict ...texture sensory attributes in melon genotypes.•Breeding programs targeting texture may be accelerated by instrumental methods.
Melon (Cucumis melo L.) is a commercially important horticultural crop worldwide that exhibits extensive phenotypic and genetic variation. Texture is one of the key attributes defining melon fruit quality and overall consumer preference. The aim of this research was two-fold: first, to characterize and compare differences in fruit sensory and instrumental textural properties among a diverse panel of melon fruit genotypes (to determine if each methodology is capable of discriminating among genotypes independently); and secondly, to assess the correlations between texture-related sensory attributes and instrumental parameters. During two production seasons, fruit from 10 melon genotypes with diverse textural characteristics were harvested at optimal commercial maturity and stored for six days at 5 °C plus one day at room temperature, then analyzed for textural instrumental and sensory properties. Both methodologies detected significant and reproducible differences in texture among the assayed melon genotypes. Furthermore, texture-related sensory attributes of firmness, crunchiness, and juiciness significantly correlated with several parameters obtained through the instrumental assessment of texture by using different probes of the texture analyzer instrument, independently. Our results indicate that texture-related attributes and overall fruit quality improvement could be accelerated significantly by the application of instrumental measurements to select for phenotypes that highly associate with consumer perception, decreasing costs and time investments.
•Maturity at harvest and after storage plus genotype impact melon fruit flavor.•Volatiles increased in storage for all melon genotypes with esters being dominant.•Short shelf-life melons associated ...with esters, sulphur compounds and a terpenoid.•Long shelf-life melons related with green/grassy aroma/flavor, firmness, aldehydes.
Flavor is a key attribute defining melon fruit quality and driving consumer preferences. We characterized and compared fruit ripening patterns (ethylene, respiration), physicochemical properties (rind/flesh color, firmness, soluble solids, acidity), aroma volatiles, and flavor-related sensory attributes in seven melon genotypes differing in shelf life capacity. Fruits were evaluated at optimal maturity and after storage for six days at 5 °C plus one day at room temperature. Total volatile content increased after storage in all genotypes, with esters being dominant. Shorter shelf-life genotypes, displaying a sharper climacteric phase, correlated with fruity/floral/sweet flavor-related descriptors, and with esters, sulfur-containing compounds and a terpenoid. Longer shelf-life types were associated with firmness, green and grassy aroma/flavor and aldehydes. Multivariate regression identified key volatiles that predict flavor sensory perception, which could accelerate breeding of longer shelf-life melons with improved flavor characteristics.
Geometry teaching in elementary schools in Colombia is a challenging task. Students’ problems with this topic have led to below-average performances in the Program of International Student ...Assessment. To face this challenge, this paper presents Akasha, a personalized software application to reinforce geometry teaching to elementary school children between 5 and 7 years old. Akasha provides ludic activities to identify and characterize polyhedra, polygons, and shape attributes. To further improve the experience, Akasha uses information about users to adjust the difficulty level, and to customize the look and feel of the application. To validate the approach, this study assessed student performance before and after using Akasha in three different schools (public and private) of Bogotá (Colombia). The results suggest that the use of Akasha may have a positive impact on students’ learning, regardless of their social, economic, or technological background.
Study Design.
Global cross-sectional survey.
Objective.
To determine the classification accuracy, interobserver reliability, and intraobserver reproducibility of the AO Spine Upper Cervical Injury ...Classification System based on an international group of AO Spine members.
Summary of Background Data.
Previous upper cervical spine injury classifications have primarily been descriptive without incorporating a hierarchical injury progression within the classification system. Further, upper cervical spine injury classifications have focused on distinct anatomical segments within the upper cervical spine. The AO Spine Upper Cervical Injury Classification System incorporates all injuries of the upper cervical spine into a single classification system focused on a hierarchical progression from isolated bony injuries (type A) to fracture dislocations (type C).
Methods.
A total of 275 AO Spine members participated in a validation aimed at classifying 25 upper cervical spine injuries through computed tomography scans according to the AO Spine Upper Cervical Classification System. The validation occurred on two separate occasions, three weeks apart. Descriptive statistics for percent agreement with the gold-standard were calculated and the Pearson χ
2
test evaluated significance between validation groups. Kappa coefficients (κ) determined the interobserver reliability and intraobserver reproducibility.
Results.
The accuracy of AO Spine members to appropriately classify upper cervical spine injuries was 79.7% on assessment 1 (AS1) and 78.7% on assessment 2 (AS2). The overall intraobserver reproducibility was substantial (κ=0.70), while the overall interobserver reliability for AS1 and AS2 was substantial (κ=0.63 and κ=0.61, respectively). Injury location had higher interobserver reliability (AS1: κ = 0.85 and AS2: κ=0.83) than the injury type (AS1: κ=0.59 and AS2: 0.57) on both assessments.
Conclusion.
The global validation of the AO Spine Upper Cervical Injury Classification System demonstrated substantial interobserver agreement and intraobserver reproducibility. These results support the universal applicability of the AO Spine Upper Cervical Injury Classification System.
Level of Evidence
4
Active faults of El Salvador Martínez-Díaz, José J.; Álvarez-Gómez, José A.; Staller, Alejandra ...
Journal of South American earth sciences,
January 2021, 2021-01-00, Letnik:
105
Journal Article
Recenzirano
In this work we present a review of the current state of knowledge of the active faults in El Salvador and its seismo-tectonic implications. An updated map of active fault traces is combined with the ...spatial analysis of shallow seismicity, focal mechanisms, recent geodetic GPS velocities, local strain estimations and morpho-tectonic features to provide a synoptic view of the active tectonics of the El Salvador. The major faults selected as potential seismic sources bound tectonic blocks or regions that include GPS sites with consistent relative velocity vectors. We propose several active tectonic domains along El Salvador controlled by three current deformation regimes: a crustal block in the forearc sliver dominated by rigid westward translation with the faster and more homogeneous GPS velocities; three zones dominated by E-W distributed extensional coaxial deformation; and two bands with a deformation compatible with transtensional regime. In the Western sector of the ESFZ, GPS velocities and local structure suggest that E-W extension concentrates along the NNW-SSE oriented Santa Ana volcanic axis and it could connect to the north with the extensional region of the Ipala Graben. This is consistent with to the eastward shift of the North America-Cocos-Caribbean triple junction and “the closing of the zipper” proposed in recent models that progressively slows down the strike-slip movement along the northern limit of the forearc sliver. In the central sector large GPS velocity gradient parallel to the volcanic arc may be associated to complex and discontinuous structure of the ESFZ driving slowdown of the westward movement of local tectonic blocks. The southeaster sector of the ESFZ is an incipient large pull-apart structure affecting a pre-existing extensional N-S oriented fabric that induces two tectonic subdomains, the eastern one undergo E-W coaxial extension and the western one characterized by transtensional strain regime. We propose a new structural segmentation of the ESFZ considering that this fault zone includes all those structures that accommodate the relative velocity between the forearc sliver and the Chortís block. The 38 active faults with surface traces that are mapped for more than 5 km long proposed in this work, with maximum potential magnitude Mw ranging from 5.98 to 7.94, will contribute to improve regional and local seismic sources databases and seismic hazard assessment.
•Review of the current state of knowledge of the active faults in El Salvador.•Updated active faults map consistent with GPS velocities distribution.•Three current deformation regimes along the El Salvador fault zone.
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