Comparative mapping of loci controlling winter survival and related traits in oilseed Brassica rapa and B. napus

Winter survival is an important characteristic of oilseedBrassica that is seeded in the fall in northern climates,and it may be affected by genetic variation for other cold-regulated traits,such as freezing tolerance and vernalization responsive flowering time. Weanalyzed immortalized populations of oilseed Brassica rapa(recombinant inbred lines) and B. napus (double haploidlines) derived from crosses of annual and biennial types in order to comparethe map positions and effects of quantitative trait loci controlling wintersurvival, nonacclimated and acclimated freezing tolerances, and flowering time.The B. napus population was evaluated in multiple winters,and six of the 16 total significant QTL for winter survival were detected inmore than one winter. Correspondence in the map positions of QTL controllingdifferent traits within species provided evidence that some alleles causinggreater acclimated freezing tolerance and later flowering time also contributedto increased winter survival. Correspondence in the map positions of QTLbetween species provided evidence for allelic variation at homologous loci inB. rapa and B. napus. The potentialrole of some candidate genes in regulating these traits is discussed.     

Accumulation of fumonisins B1 and B2 in freshly harvested Brazilian commercial maize at three locations during two nonconsecutive seasons

Fifty-six Brazilian commercial maize cultivars were examined for FB1 and FB2 accumulation after two non-consecutive growing seasons. During the 94/95 growing season 35 cultivars were planted at three locations in the state of S?o Paulo, Brazil. All samples (total of 105) were contaminated (0.10 micro/g-6.58 microg/g FB1 and 0.04 microg/g-2.15 microg/g FB2). During the 97/98 growing season, 8 of the cultivars used during 94/95 and 21 others were replanted at the same locations. All 87 samples were contaminated (1.15 microg/g-43.80 microg/g FB1 and 0.08 microg/g-11.65 microg/g FB2). One cultivar accumulated significantly less fumonisins in all locations during both growing seasons, indicating that some degree of selection may be possible even in climates that favor F. moniliforme (verticillioides) infection of maize. The presence of water surplus in soil from kernel maturity to harvest correlated with concentrations of FB1 in the grain for the 8 cultivars planted during both seasons at three locations. Observed trends indicated that water excesses and deficits from silking to harvest increased fumonisin levels. The difference in the incidence of FB1, FB2, and FB1 + FB2 was significant between growing seasons, planting locations and between cultivars. Neither the level of hybridization, nor the type of endosperm, nor the length of the vegetative cycle showed any effect on the FB1 contamination.     

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.     

In Vitro Evaluation of the Effect of Stimulation with Magnetic Fields on Chondrocytes

Magnetic fields (MFs) have been used as an external stimulus to increase cell proliferation in chondrocytes and extracellular matrix (ECM) synthesis of articular cartilage. However, previously published studies have not shown that MFs are homogeneous through cell culture systems. In addition, variables such as stimulation times and MF intensities have not been standardized to obtain the best cellular proliferative rate or an increase in molecular synthesis of ECM. In this work, a stimulation device, which produces homogeneous MFs to stimulate cell culture surfaces was designed and manufactured using a computational model. Furthermore, an in vitro culture of primary rat chondrocytes was established and stimulated with two MF schemes to measure both proliferation and ECM synthesis. The best proliferation rate was obtained with an MF of 2 mT applied for 3 h, every 6 h for 8 days. In addition, the increase in the synthesis of glycosaminoglycans was statistically significant when cells were stimulated with an MF of 2 mT applied for 5 h, every 6 h for 8 days. These findings suggest that a stimulation with MFs is a promising tool that could be used to improve in vitro treatments such as autologous chondrocyte implantation, either to increase cell proliferation or stimulate molecular synthesis. Bioelectromagnetics. 2020;41:41–51 © 2019 Bioelectromagnetics Society     

A Comparison of the Whole Genome Approach of MeDIP-Seq to the Targeted Approach of the Infinium HumanMethylation450 BeadChip? for Methylome Profiling

DNA methylation is one of the most studied epigenetic marks in the human genome, with the result that the desire to map the human methylome has driven the development of several methods to map DNA methylation on a genomic scale. Our study presents the first comparison of two of these techniques - the targeted approach of the Infinium HumanMethylation450 BeadChip® with the immunoprecipitation and sequencing-based method, MeDIP-seq. Both methods were initially validated with respect to bisulfite sequencing as the gold standard and then assessed in terms of coverage, resolution and accuracy. The regions of the methylome that can be assayed by both methods and those that can only be assayed by one method were determined and the discovery of differentially methylated regions (DMRs) by both techniques was examined. Our results show that the Infinium HumanMethylation450 BeadChip® and MeDIP-seq show a good positive correlation (Spearman correlation of 0.68) on a genome-wide scale and can both be used successfully to determine differentially methylated loci in RefSeq genes, CpG islands, shores and shelves. MeDIP-seq however, allows a wider interrogation of methylated regions of the human genome, including thousands of non-RefSeq genes and repetitive elements, all of which may be of importance in disease. In our study MeDIP-seq allowed the detection of 15,709 differentially methylated regions, nearly twice as many as the array-based method (8070), which may result in a more comprehensive study of the methylome.     

Use of lysophosphatidylethanolamine, a natural lipid, to retard tomato leaf and fruit senescence

We studied the influence of lysophosphatidylethanolamine (LPE) on the pattern and rate of ethylene production and respiration of tomato ( Lycopersicon esculentum cv. H7155) leaflets and fruit. Leaflets that had been senescing on the plant showed a climacteric-like rise in ethylene production but not in respiration rate which decreased continuously with leaf age. Detached leaflets had a climacteric-like pattern in respiration whether they were incubated in complete darkness or in light. Detached leaflets incubated in the dark had higher rates of ethylene production and CO₂ evolution than did light-incubated leaves. There was no change in the pattern of ethylene production or CO₂ evolution as a result of LPE treatment. However, LPE-treated attached and detached leaflets had consistently lower rates of CO₂ evolution. The reduction in CO₂ evolution by LPE was most pronounced at the climacteric-like peak of the detached leaves. LPE-treated leaflets had a higher chlorophyll content and fresh weight and lower electrolyte leakage than the control. LPE-treated fruits had lower rates of ethylene and CO₂ production than did the control. LPE-treated fruits also had higher pericarp firmness and lower electrolyte leakage than the control. The results of the present study provide evidence that LPE is able to retard senescence of attached leaves and detached leaves and tomato fruits. Several recent studies suggest that lysolipids can act in a specific manner as metabolic regulators. Our results suggest a specific role of lysolipid LPE in aging and senescence     

Plasma Membrane ATPase Activity following Reversible and Irreversible Freezing Injury

Plasma membrane ATPase has been proposed as a site of functional alteration during early stages of freezing injury. To test this, plasma membrane was purified from Solanum leaflets by a single step partitioning of microsomes in a dextran-polyethylene glycol two phase system. Addition of lysolecithin in the ATPase assay produced up to 10-fold increase in ATPase activity. ATPase activity was specific for ATP with a K_m around 0.4 millimolar. Presence of the ATPase enzyme was identified by immunoblotting with oat ATPase antibodies. Using the phase partitioning method, plasma membrane was isolated from Solanum commersonii leaflets which had four different degrees of freezing damage, namely, slight (reversible), partial (partially reversible), substantial and total (irreversible). With slight (reversible) damage the plasma membrane ATPase specific activity increased 1.5- to 2-fold and its K_m was decreased by about 3-fold, whereas the specific activity of cytochrome c reductase and cytochrome c oxidase in the microsomes were not different from the control. However, with substantial (lethal, irreversible) damage, there was a loss of membrane protein, decrease in plasma membrane ATPase specific activity and decrease in K_m, while cytochrome c oxidase and cytochrome c reductase were unaffected. These results support the hypothesis that plasma membrane ATPase is altered by slight freeze-thaw stress.     

A new look at computation of the complexity index in mangroves: do disturbed forests have clues to analyze canopy height patchiness?

This paper proposes some guidelines to compute complexity index in those mangroves where either seasonal or strong disturbances have occurred. We surveyed 31 mangrove localities in Buenaventura Bay, Central Pacific Coast of Colombia, where structural parameters were measured within a 0.1 ha plot. Also, most likely disturbances were noted for each plot. Complexity index was calculated in its classical form using the arithmetic mean of the three tallest trees(maximal mean) and alternatively using: a) the total mean: the height average of all trees recorded in each plot; and b) the mode: the most frequent tree height class (10 cm intervals) within each plot. Afterwards, we compared the three computations and discussed there liability of each one according to the current state by plot. In addition, all structural parameters were sorted in two diameter at breast height (dbh) cohorts (2.5–10 cm and ≥ 10 cm) to figure out which contributes more to the forest structure. We conclude the following: (a) The mean of the three tallest trees is not a good estimator of forest development when seasonal or strong disturbances occur since complexity index based in it always overestimates forest structure. (b) Seasonal disturbances and recruitment produce mosaic forests. The best estimator of this condition is the mean height which encompasses both central tendency and variability. (c) The modal height is also helpful to establish the dominant cohort when forests show two or more storied-canopies, or intermediate cohorts are missing. It also applies when a new stock of recruits is entering in a mature forest (the modal or maximal heights can be used interchangeably in this case). (d) Maximal height is the best estimator for uniformly developed forests with closed canopies and/or a single dominant tall-cohort. (e) If one is not confident about which height type to include to compute the complexity index, we recommend to sort out structure data by dbh-cohorts and calculate indices for both of them. This will show which cohort is contributing most to forest complexity. Finally, we suggest to exclude non-mangrove species from the complexity index computation since they mostly do not contribute significantly to forest basal area. This revised version was published online in July 2006 with corrections to the Cover Date.     

Genetic variability of Spodoptera frugiperda Smith (Lepidoptera: Noctuidae) populations from Latin America is associated with variations in susceptibility to Bacillus thuringiensis cry toxins

Bacillus thuringiensis strains isolated from Latin American soil samples that showed toxicity against three Spodoptera frugiperda populations from different geographical areas (Mexico, Colombia, and Brazil) were characterized on the basis of their insecticidal activity, crystal morphology, sodium dodecyl sulfate-polyacrylamide gel electrophoresis of parasporal crystals, plasmid profiles, and cry gene content. We found that the different S. frugiperda populations display different susceptibilities to the selected B. thuringiensis strains and also to pure preparations of Cry1B, Cry1C, and Cry1D toxins. Binding assays performed with pure toxin demonstrated that the differences in the toxin binding capacities of these insect populations correlated with the observed differences in susceptibility to the three Cry toxins analyzed. Finally, the genetic variability of the three insect populations was analyzed by random amplification of polymorphic DNA-PCR, which showed significant genetic diversity among the three S. frugiperda populations analyzed. The data presented here show that the genetic variability of S. frugiperda populations should be carefully considered in the development of insect pest control strategies, including the deployment of genetically modified maize in different geographical regions.