Evaluation of the Local Analgesic Effects of a Commercial Aqueous Extract of Sarracenia purpurea and Ammonium Sulfate in the Equine Abaxial Sesamoid Block Model

Sarracenia purpurea is a carnivorous plant whose aqueous extracts have been proposed to exert analgesic effects by neurolytical action on peripheral nerves. The aim of this study was to determine the local analgesic effects of a commercially available aqueous extract solution of S. purpurea (P-Bloc, St. Joseph, Missouri) and a 1% ammonium sulfate solution, using the horse abaxial sesamoid block model. Twenty horses were randomly assigned to two groups. The first group (n = 10) was used to evaluate the effect of P-Bloc. The horses received a bilateral (medial and lateral) abaxial sesamoid block with 5 mL of P-Bloc in one random forelimb, while in the contralateral forelimb, they received either 5 mL of 2% lidocaine as a positive control (n = 5) or 5 mL of 0.9% NaCl as a negative control (n = 5). The second group (n = 10) was treated as the first but received 5 mL of 1% ammonium sulfate in NaCl (0.9% NaCl) solution instead of P-Bloc. The period of hoof withdrawal reflex latency (HWRL, in seconds) was measured using a custom-made heat projector lamp as a source of a noxious skin heating stimulus applied to the pastern. Lidocaine (2%) prolonged (P ≤ .05) the HWRL period, returning to the negative control basal values after 240 minutes. Neither the treatment with P-Bloc nor 1% ammonium sulfate modified the HWRL period. The lack of effect of these compounds in this model reinforces the results reported elsewhere and suggests a nonlocal anesthetic mechanism of action for the aqueous extract of S. purpurea in the horse.     

A set of novel RNAs transcribed from the chloroplast genome accumulates in date palm leaflets affected by brittle leaf disease

Brittle leaf disease or maladie des feuilles cassantes (MFC) is a lethal disorder of date palms that has assumed epidemic proportions in the oases of southern Tunisia. After a prolonged period during which palms are declining, the disease ends with the death of the palms. Whereas no pathogen could ever be associated with the disease, leaflets of affected palms have been previously shown to be deficient in manganese. Analysis of RNA preparations from leaflets of MFC-affected palms revealed the presence of a set of novel RNAs (MFC-RNAs) of sense and antisense polarities, which are homologous to various regions of the date palm chloroplast genome, such as the regions containing genes rrn5S-trnR(ACG) and trnM(CAU)-atpE. In the RNA preparations obtained from leaflets of affected palms, some of these RNAs are present as double-stranded species (MFC-dsRNAs), as witnessed by results from cellulose chromatography, end labeling, RNase digestion, and northern hybridization with strand specific probes. These MFC-RNAs represent a novel type of host-derived RNAs, and their presence in MFC-affected date palms is of diagnostic value.     

Identification and multi-environment validation of resistance to Botrytis fabae in Vicia faba

The aim of this work was to find new sources of resistance to chocolate spot disease, and to validate their stability across different environments. In order to do so, a collection of 307 accessions of Vicia faba was screened for resistance to Botrytis fabae under field conditions; stability of resistance of the 40 most-resistant accessions was tested in a multi-location experiment in Austria, Chile, Egypt, France and Spain over two field seasons. Although complete resistance was not found, nine accessions showed interesting levels of incomplete resistance (ranging from 10 to 20% of average severity across environments, maximum average severity being 47.9%). Genotype × environment interaction accounted for 22% of the sum of squares of the multi-environment evaluation, revealing instability of the phenotypic expression across environments. This usually hampers the efficiency of selection and reduces the adaptability of the plant material. Three accessions stand out for their consistent resistance, both in terms of reduced disease severity and high stability, which make them good candidates for breeding programs. As for environments, those with the highest total severity mean were the most discriminant between accessions. In contrast, those with lower severity means were the most representative of the whole range of environments. It can be concluded that validation of resistance to chocolate spot in different environments is an essential step when screening for material of interest and should be taken into account for further works.     

Effects of Mexican dwarf mistletoe (Arceuthobium vaginatum subsp. vaginatum) on the growth of Pinus cooperi in Durango,Mexico—A case study

Mexican dwarf mistletoe (Arceuthobium vaginatum subsp. vaginatum, Viscaceae) is the most widespread and damaging parasitic plant in Mexico. It parasitizes 10 species of pines (Pinus spp., Pinaceae) as principal hosts, including Pinus cooperi, one of the economically most important pines in the state of Durango. As a case study, we used stem analysis to estimate the effects of Mexican dwarf mistletoe on volume and height growth of dwarf mistletoe‐infected P. cooperi in western Durango (Ejido El Brillante, Municipality Pueblo Nuevo). This case study sampled a total of 48 trees, 12 in each of four infection classes estimated using the 6‐class dwarf mistletoe rating system (DMR): uninfected (DMR 0), lightly infected (DMR 1–2), moderately infected (DMR 3–4) and severely infected (DMR 5–6). Significant reductions in both volume and height growth were found for moderately and severely infected trees when compared to uninfected trees. On average, reductions in volume growth and height growth were as high as 50% and 17%, respectively. The largest growth reductions were for moderately infected trees, but large growth reductions also occurred for severely infected trees. Because of the reduced growth associated with moderate to severe infection, Mexican dwarf mistletoe‐infested pine forests in Durango, where timber production is a high priority, should be managed using harvesting practices that reduce dwarf mistletoe infection, and thereby, increase forest productivity.     

Evolutionary analysis of Citrus tristeza virus outbreaks in Calabria,Italy: two rapidly spreading and independent introductions of mild and severe isolates

The evolution of citrus tristeza virus (CTV) from outbreaks occurred in Calabria, Italy, was compared with that of CTV outbreaks reported previously in another two proximal Italian regions, Sicily and Apulia. Examination of four genomic regions (genes p20, p25 and p23, and one fragment of open reading frame 1) showed two recombination events, and phylogenetic analysis disclosed two divergent CTV groups in Calabria: one formed by severe and the other by mild isolates. This analysis, together with others involving population genetic parameters, revealed a low migration rate of CTV between the three Italian regions, as well as significant differences in selective pressures, epidemiology and demography, all affecting the genetic structure of CTV populations.     

Changes in the enantiomeric distribution of selected volatile constituents of Mentha pulegium L. powders caused by hot water treatment

The variation, in general, of the composition of the aromatic fraction and, in particular, of the enantiomeric composition of certain chiral volatile compounds of commercial Mentha pulegium L. powders caused by boiling water was evaluated. A comparison between the volatile profile of the studied herbs demonstrated that most M. pulegium L. samples contained high proportions of Mentha piperita L., even when this information was not specified on the label. Likewise, substantial changes in the volatile fraction of the infusions with respect to the composition of the original plant used in their preparation were found. The enantiomeric composition of some chiral compounds of the dried plant material, particularly limonene, was modified by adding hot water, whereas others were kept invariable. The results shown in this work reflect the need for the control of the composition of commercial powders and brews of M. pulegium L. to ensure their correct application.     

Two Dobzhansky-Muller genes interact to cause hybrid lethality in Drosophila

The Dobzhansky-Muller model proposes that hybrid incompatibilities are caused by the interaction between genes that have functionally diverged in the respective hybridizing species. Here, we show that Lethal hybrid rescue (Lhr) has functionally diverged in Drosophila simulans and interacts with Hybrid male rescue (Hmr), which has functionally diverged in D. melanogaster, to cause lethality in F1 hybrid males. LHR localizes to heterochromatic regions of the genome and has diverged extensively in sequence between these species in a manner consistent with positive selection. Rapidly evolving heterochromatic DNA sequences may be driving the evolution of this incompatibility gene.     

Frequency and intensity of pyrethroid resistance through the CDC bottle bioassay and their association with the frequency of kdr mutations in Aedes aegypti (Diptera: Culicidae) from Mexico

BACKGROUND

The control of Aedes aegypti (L.), the main urban vector that causes arboviral diseases such as dengue, Chikungunya and Zika, has proved to be a challenge because of a rapid increase in insecticide resistance. Therefore, adequate monitoring of insecticide resistance is an essential element in the control of Ae. aegypti and the diseases it transmits. We estimated the frequency and intensity (Resistance Frequency Rapid Diagnostic Test [F‐RDT] and Resistance Intensity Rapid Diagnostic Test [I‐RDT]) of pyrethroid resistance in populations of Ae. aegypti from Mexico using the bottle bioassay and results were related to the frequencies of knockdown resistance (kdr) mutations V1016I and F1534C.

RESULTS

All populations under study were resistant to the pyrethroids: bifenthrin (99%), d‐(cis–trans)‐phenothrin (6.3% cis, 91.7% trans) and permethrin (99.5%) according to F‐RDT, and showed moderate to high‐intensity resistance at 10× the diagnostic dose (DD) in I‐RDT. Frequencies of the kdr mutation V1016I in Ae. aegypti populations were correlated with moderate permethrin resistance at 10× DD, whereas F1534C mutation frequencies were correlated with high bifenthrin resistance at 5× DD. Both I1016 and C1535 were highly correlated with high‐intensity phenothrin resistance at 1× to 10× DD.

CONCLUSIONS

This study showed that high frequencies of kdr mutations V1016I and F1534C are reflected in the results of F‐RDT and I‐RDT tests. Bioassays in conjunction with the characterization of genetic resistance mechanisms are indispensable in the strategic and rational management of resistance in mosquitoes. © 2018 Society of Chemical Industry