High-density genetic mapping for coffee leaf rust resistance

Coffee leaf rust caused by the fungus Hemileia vastatrix causes considerable economic losses for coffee producers. Although agrochemical products can provide sufficient disease control, the use of resistant cultivars is a safer alternative. This resistance may be constrained by one or a few genetic factors, mainly those found in material originating from interspecific hybrids. In this study, the genetic analysis of an F ₂ population consisting of 224 plants derived from a crossing of Híbrido de Timor UFV 427-15 (resistant) with Catuaí Amarelo IAC 30 (susceptible) showed that a dominant gene confers the resistance of coffee to race II of H. vastatrix. From a genetic map saturated with 25 amplified fragment length polymorphism (AFLP) markers linked to the resistance gene, we developed a high-density genetic map with six sequence-characterized amplified region (SCAR) markers delimiting a chromosomal region of 9.45 cM and flanking the dominant gene at 0.7 and 0.9 cM. This is the first saturated and high-density genetic map obtained from this region containing the resistance gene. The results of this study are of great importance for the introduction of molecular markers for marker-assisted selection; they will also facilitate studies related to the cloning, structure, and function of race-specific genes involved in the resistance of coffee trees to H. vastatrix.     

The Potential Impact of White-Nose Syndrome on the Conservation Status of North American Bats

White-Nose syndrome (WNS) is an emergent infectious disease that has already killed around six million bats in North America and has spread over two thousand kilometers from its epicenter. However, only a few studies on the possible impacts of the fungus on bat hosts were conducted, particularly concerning its implications for bat conservation. We predicted the consequences of WNS spread by generating a map with potential areas for its occurrence based on environmental conditions in sites where the disease already occurs, and overlaid it with the geographic distribution of all hibernating bats in North America. We assumed that all intersection localities would negatively affect local bat populations and reassessed their conservation status based on their potential population decline. Our results suggest that WNS will not spread widely throughout North America, being mostly restricted to the east and southeast regions. In contrast, our most pessimistic scenario of population decline indicated that the disease would threaten 32% of the bat species. Our results could help further conservation plans to preserve bat diversity in North America.     

Identification of Bioactive Compounds against Aedes aegypti (Diptera: Culicidae) by Bioassays and in Silico Assays

Most of the hematophagous insects act as disease vectors, including Aedes aegypti, responsible for transmitting some of the most critical arboviruses globally, such as Dengue. The use of repellents based on natural products is a promising alternative for personal protection compared to industrial chemical repellents. In this study, the repellent effect of essential oils extracted from Lippia thymoides, Lippia alba, Cymbopogon winterianus, and Eucalyptus globulus leaves was evaluated. Essential oils used showed repellent activity against Ae. aegypti in laboratory bioassays, obtaining protection rates above 70 % from 3.75 mg/mL and higher concentration for all analyzed oils. GC/MS identified 57 constituents, which were used in the ligand-based pharmacophore model to expose compounds with requirements for repellents that modulate mosquitoes behavior through odorant-binding protein 1 Ae. aegypti. Ligand-based pharmacophore model approach results suggested that repellent activity from C. winterianus, L. alba, and L. thymoides essential oils’ metabolites is related to Citronelal (QFIT=26.77), Citronelol (QFIT=11.29), Citronelol acetate (QFIT=52.22) and Geranil acetate (QFIT=10.28) with synergistic or individual activity. E. globulus essential oil's repellent activity is associated with Ledol (0.94 %; QFIT=41.95). Molecular docking was applied to understand the binding mode and affinity of the essential oils’ data set at the protein binding site. According to molecular docking, Citronelol (ChemPLP=60.98) and geranyl acetate (ChemPLP=60.55) were the best-classified compounds compared to the others and they can be explored to develop new repellents.     

Unpacking of a Crumpled Wire from Two-Dimensional Cavities

The physics of tightly packed structures of a wire and other threadlike materials confined in cavities has been explored in recent years in connection with crumpled systems and a number of topics ranging from applications to DNA packing in viral capsids and surgical interventions with catheter to analogies with the electron gas at finite temperature and with theories of two-dimensional quantum gravity. When a long piece of wire is injected into two-dimensional cavities, it bends and originates in the jammed limit a series of closed structures that we call loops. In this work we study the extraction of a crumpled tightly packed wire from a circular cavity aiming to remove loops individually. The size of each removed loop, the maximum value of the force needed to unpack each loop, and the total length of the extracted wire were measured and related to an exponential growth and a mean field model consistent with the literature of crumpled wires. Scaling laws for this process are reported and the relationship between the processes of packing and unpacking of wire is commented upon.     

Selection and characterization of mexican strains ofBacillus thuringiensis active against four major lepidopteran maize pests

In order to isolate novel delta-endotoxins fromBacillus thuringiensis Berliner, a total of 426 native isolates (in varying numbers for each pest) were screened against four major maize pests: corn earworm,Helicoverpa zea; fall armyworm,Spodoptera frugiperda; southwestern corn borer,Diatraea graridiosella, and sugarcane borer,Diatraea saccharalis. Spore-crystal complexes from the isolates were integrated into semi-artificial diets of each pest and mortality was assessed 7 days after treatment. A total of 25 isolates were selected on the basis of highest larval mortality against at least one insect species. There was no correspondence of the most toxic isolates when tested against the four different insect species. Most of the 25 selected isolates caused higher toxicities against all four pests than the standard strain HD-1, regardless of not achieving 100% mortality in any bioassay.H. zea demonstrated the highest level of mortality (96%) and was susceptible to the largest number of isolates (98). None of the other insect species were found susceptible at levels greater than 60%. All the selected active strains were isolated from stored grain dusts (except for LBIT-167), and had bipyramidal crystals with Cry I-like proteins. Most isolates also formed an associated square (cubic) inclusion, with Cry Il-like proteins according to SDS-PAGE analysis of their parasporal bodies. The most active isolates will be subjected to further studies, in order to identify putative novel genes to be expressed in transgenic maize     

A New Species of <Emphasis Type="Italic">Pararrhopalites</Emphasis> Bonet &amp; Tellez (Collembola,Symphypleona, Sminthuridae) from Iron Caves in Brazil

A second species of the genus Pararrhopalites is described from caves inserted in iron ore lithology. Both species present a particular sensory organ in the interantennal region. The new species, Pararrhopalites ubiquum n.sp., has a wider distribution and it is not restricted to a single cave, as it is the case of Pararrhopalites sideroicus Zeppelini & Brito, in Fla Entomol 97(4):1733–1744, 2014, being found even in the Mesovoid Shallow Substratum. An update to the previously published identification key is presented.     

Effect of landscape features on genetic structure of the goitered gazelle (<Emphasis Type="Italic">Gazella subgutturosa</Emphasis>) in Central Iran

The populations of goitered gazelle suffered significant decline due to natural and anthropogenic factors over the last century. Investigating the effects of barriers on gene flow among the remaining populations is vital for conservation planning. Here we adopted a landscape genetics approach to evaluate the genetic structure of the goitered gazelle in Central Iran and the effects of landscape features on gene flow using 15 polymorphic microsatellite loci. Spatial autocorrelation, isolation by distance (IBD) and isolation by resistance (IBR) models were used to elucidate the effects of landscape features on the genetic structure. Ecological modeling was used to construct landscape permeability and resistance map using 12 ecogeographical variables. Bayesian algorithms revealed three genetically homogeneous groups and restricted dispersal pattern in the six populations. The IBD and spatial autocorrelation revealed a pattern of decreasing relatedness with increasing distance. The distribution of potential habitats was strongly correlated with bioclimatic factors, vegetation type, and elevation. Resistance distances and graph theory were significantly related with variation in genetic structure, suggesting that gazelles are affected by landscape composition. The IBD showed greater impact on genetic structure than IBR. The Mantel and partial Mantel tests indicated low but non-significant effects of anthropogenic barriers on observed genetic structure. We concluded that a combination of geographic distance, landscape resistance, and anthropogenic factors are affecting the genetic structure and gene flow of populations. Future road construction might impede connectivity and gene exchange of populations. Conservation measures on this vulnerable species should consider some isolated population as separate management units.     

Mice with endogenous TDP‐43 mutations exhibit gain of splicing function and characteristics of amyotrophic lateral sclerosis

TDP‐43 (encoded by the gene TARDBP) is an RNA binding protein central to the pathogenesis of amyotrophic lateral sclerosis (ALS). However, how TARDBP mutations trigger pathogenesis remains unknown. Here, we use novel mouse mutants carrying point mutations in endogenous Tardbp to dissect TDP‐43 function at physiological levels both in vitro and in vivo. Interestingly, we find that mutations within the C‐terminal domain of TDP‐43 lead to a gain of splicing function. Using two different strains, we are able to separate TDP‐43 loss‐ and gain‐of‐function effects. TDP‐43 gain‐of‐function effects in these mice reveal a novel category of splicing events controlled by TDP‐43, referred to as “skiptic” exons, in which skipping of constitutive exons causes changes in gene expression. In vivo, this gain‐of‐function mutation in endogenous Tardbp causes an adult‐onset neuromuscular phenotype accompanied by motor neuron loss and neurodegenerative changes. Furthermore, we have validated the splicing gain‐of‐function and skiptic exons in ALS patient‐derived cells. Our findings provide a novel pathogenic mechanism and highlight how TDP‐43 gain of function and loss of function affect RNA processing differently, suggesting they may act at different disease stages.