Genome-wide association identifies several QTLs controlling cysteine and methionine content in soybean seed including some promising candidate genes.

Soybean is an important source of protein, oil and carbohydrates, as well as other beneficial nutrients. A major function of proteins in nutrition is to supply adequate amounts of amino acids. Although they are essential for human nutrition, the sulfur-containing amino acids cysteine (Cys) and methionine (Met) are often limited and the genetic control of their content in soybean seeds is poorly characterized. This study aimed to characterize the phenotypic variation and identify quantitative trait loci (QTL) associated with Cys and Met content in a core set of 137 soybean lines, representative of the genetic diversity among Canadian short-season soybean, spanning maturity groups 000-II (MG000-II). Significant phenotypic differences were found among these lines for Cys, Met and Cys + Met content. Using both a mixed linear model and six multi-locus methods with a catalogue of 2.18 M SNPs, we report a total of nine QTLs and seventeen QTNs of which seven comprise promising candidate genes. This work allowed us to reproducibly detect multiple novel loci associated with sulfur-containing amino acid content. The markers and genes identified in this study may be useful for soybean genetic improvement aiming to increase Cys and Met content.

Embolization of the Middle meningeal artery in chronic subdural hematoma - A systematic review.

Chronic subdural hematomas (cSDH) are one of the most frequent reasons for consultation in neurosurgery. Multiple authors have proposed middle meningeal artery embolization (MMAE) as an option in cSDH patients to manage recurrence or avoid surgery altogether. Although many articles have been published on the matter, the current body of evidence still has to be evaluated before MMAE is integrated into clinical practice. The goal of this study was to review the evidence on MMAE in cSDH to assess its safety, feasibility, indications and efficacy. We performed a systematic review of the literature according to PRISMA guidelines using multiple electronic databases. Our search yielded a total of 18 original articles from which data were extracted. A total of 190 patients underwent MMAE from which 81.3% were symptomatic cSDH. Over half (52.3%) of the described population were undergoing antithrombotic therapy. Most (83%) procedures used polyvinyl alcohol (PVA) particles and no complications were reported regarding the embolization procedures. Although the definition of resolution varied among authors, cSDH resolution was reported in 96.8% of cases. MMAE is a feasible technique for cSDH, but the current body of evidence does not yet support its use as a standard treatment. Further studies with a higher level of evidence are necessary before MMAE can be formally recommended.

Identification and characterization of silicon efflux transporters in horsetail (Equisetum arvense).

Silicon (Si) is a beneficial element to plants, and its absorption via transporters leads to protective effects against biotic and abiotic stresses. In higher plants, two groups of root transporters for Si have been identified: influx transporters (Lsi1) and efflux transporters (Lsi2). Lsi1 transporters belong to the NIPIII aquaporins, and functional Lsi1s have been found in many plants species. Much less is known about Lsi2s that have been characterized in only a few species. Horsetail (Equisetum arvense), known among the highest Si accumulators in the plant kingdom, is a valuable model to study Si absorption and deposition. In this study, we first analyzed discrete Si deposition patterns in horsetail shoots, where ubiquitous silicification differs markedly from that of higher plants. Then, using the sequenced horsetail root transcriptome, two putative Si efflux transporter genes, EaLsi2-1 and EaLsi2-2, were identified. These genes share low sequence similarity with their homologues in higher plants. Further characterisation of EaLsi2-1 in transient expression assay using Nicotiana benthamiana epidermal cells confirmed transmembrane localization. In order to determine their functionality, the EaLsi2-1 was expressed in Xenopus oocytes, confirming that the translated protein was efficient for Si efflux. Both genes were equally expressed in roots and shoots, but interestingly, showed a much higher expression in the shoots than in the roots in contrast to Lsi2s found in other plants, a result consistent with the specific anatomy of horsetail and its rank as one of the highest Si accumulators among plant species.

The wire anchor loop traction (WALT) maneuver.

Crossing the neck of large complex intracranial aneurysms for the purposes of stent deployment can be challenging using standard over the wire techniques. We describe a novel yet simple technique for straightening out the loop formed within a large intracranial aneurysm, which is often required in order to cross the aneurysm neck into the distal branch. Both the microcatheter and microwire are initially introduced into the distal vasculature, followed by withdrawal of the microwire to a point parallel to the distal exiting branch. The microcatheter and microwire are then gently withdrawn and a series of maneuvers to gradually reduce the loop is performed, obviating the need for distal purchase in the form of a stent, balloon, or coil, which have previously been described to maintain distal purchase.

Validation of Genotyping-By-Sequencing Analysis in Populations of Tetraploid Alfalfa by 454 Sequencing.

Genotyping-by-sequencing (GBS) is a relatively low-cost high throughput genotyping technology based on next generation sequencing and is applicable to orphan species with no reference genome. A combination of genome complexity reduction and multiplexing with DNA barcoding provides a simple and affordable way to resolve allelic variation between plant samples or populations. GBS was performed on ApeKI libraries using DNA from 48 genotypes each of two heterogeneous populations of tetraploid alfalfa (Medicago sativa spp. sativa): the synthetic cultivar Apica (ATF0) and a derived population (ATF5) obtained after five cycles of recurrent selection for superior tolerance to freezing (TF). Nearly 400 million reads were obtained from two lanes of an Illumina HiSeq 2000 sequencer and analyzed with the Universal Network-Enabled Analysis Kit (UNEAK) pipeline designed for species with no reference genome. Following the application of whole dataset-level filters, 11,694 single nucleotide polymorphism (SNP) loci were obtained. About 60% had a significant match on the Medicago truncatula syntenic genome. The accuracy of allelic ratios and genotype calls based on GBS data was directly assessed using 454 sequencing on a subset of SNP loci scored in eight plant samples. Sequencing depth in this study was not sufficient for accurate tetraploid allelic dosage, but reliable genotype calls based on diploid allelic dosage were obtained when using additional quality filtering. Principal Component Analysis of SNP loci in plant samples revealed that a small proportion (<5%) of the genetic variability assessed by GBS is able to differentiate ATF0 and ATF5. Our results confirm that analysis of GBS data using UNEAK is a reliable approach for genome-wide discovery of SNP loci in outcrossed polyploids.

A new method for studying population genetics of cyst nematodes based on Pool-Seq and genomewide allele frequency analysis.

Cyst nematodes are important agricultural pests responsible for billions of dollars of losses each year. Plant resistance is the most effective management tool, but it requires a close monitoring of population genetics. Current technologies for pathotyping and genotyping cyst nematodes are time-consuming, expensive and imprecise. In this study, we capitalized on the reproduction mode of cyst nematodes to develop a simple population genetic analysis pipeline based on genotyping-by-sequencing and Pool-Seq. This method yielded thousands of SNPs and allowed us to study the relationships between populations of different origins or pathotypes. Validation of the method on well-characterized populations also demonstrated that it was a powerful and accurate tool for population genetics. The genomewide allele frequencies of 23 populations of golden nematode, from nine countries and representing the five known pathotypes, were compared. A clear separation of the pathotypes and fine genetic relationships between and among global populations were obtained using this method. In addition to being powerful, this tool has proven to be very time- and cost-efficient and could be applied to other cyst nematode species.

Intra-arterial carboplatin as a salvage strategy in the treatment of recurrent glioblastoma multiforme.

The first-line treatment of glioblastoma typically consists of a maximal surgical resection, followed by a combination of radio-chemotherapy with temozolomide. There is however no consensus regarding optimal therapeutic approaches at relapse. The following phase II study explored the therapeutic gain obtained when exposing these patients to a combination of intra-arterially administered carboplatin and melphalan at first or second relapse as a salvage treatment in recurrent glioblastoma. Fifty-one consecutive patients diagnosed with glioblastoma were accrued and offered this treatment at first or second relapse. A Karnofsky score of ≥ 60 was required, and when appropriate, patients were first reoperated prior to accrual. Patients enrolled were treated every 4 weeks (1 cycle) for up to 12 cycles. Progression was evaluated by Macdonald criteria. Primary end point surrogates were overall survival from diagnosis and study entry. Median survival from diagnosis and study entry was 23 and 11 months, respectively. The median time to progression was 5.2 months. All patients enrolled were treated for a minimum of 2 cycles. Hematologic toxicity was manageable, with an 8 % of grade II neutropenia, 12 % of grade II thrombocytopenia and 7 % of grade III thrombocytopenia. This therapeutic strategy represents an adequate option in the second-line treatment of recurrent glioblastoma. The adjunction of an osmotic permeabilization could be considered to further expand delivery, and hopefully improve survival in these patients.

Cloning, functional characterization and heterologous expression of TaLsi1, a wheat silicon transporter gene.

Silicon (Si) is known to be beneficial to plants, namely in alleviating biotic and abiotic stresses. The magnitude of such positive effects is associated with a plant's natural ability to absorb Si. Many grasses can accumulate as much as 10% on a dry weight basis while most dicots, including Arabidopsis, will accumulate less than 0.1%. In this report, we describe the cloning and functional characterization of TaLsi1, a wheat Si transporter gene. In addition, we developed a heterologous system for the study of Si uptake in plants by introducing TaLsi1 and OsLsi1, its ortholog in rice, into Arabidopsis, a species with a very low innate Si uptake capacity. When expressed constitutively under the control of the CaMV 35S promoter, both TaLsi1 and OsLsi1 were expressed in cells of roots and shoots. Such constitutive expression of TaLsi1 or OsLsi1 resulted in a fourfold to fivefold increase in Si accumulation in transformed plants compared to WT. However, this Si absorption caused deleterious symptoms. When the wheat transporter was expressed under the control of a root-specific promoter (a boron transporter gene (AtNIP5;1) promoter), a similar increase in Si absorption was noted but the plants did not exhibit symptoms and grew normally. These results demonstrate that TaLsi1 is indeed a functional Si transporter as its expression in Arabidopsis leads to increased Si uptake, but that this expression must be confined to root cells for healthy plant development. The availability of this heterologous expression system will facilitate further studies into the mechanisms and benefits of Si uptake.

Microsatellite instability in Arabidopsis increases with plant development.

Plant development consists of the initial phase of intensive cell division followed by continuous genome endoreduplication, cell growth, and elongation. The maintenance of genome stability under these conditions is the main task performed by DNA repair and genome surveillance mechanisms. Our previous work showed that the rate of homologous recombination repair in older plants decreases. We hypothesized that this age-dependent decrease in the recombination rate is paralleled with other changes in DNA repair capacity. Here, we analyzed microsatellite stability using transgenic Arabidopsis (Arabidopsis thaliana) plants that carry the nonfunctional ß-glucuronidase gene disrupted by microsatellite repeats. We found that microsatellite instability increased dramatically with plant age. We analyzed the contribution of various mechanisms to microsatellite instability, including replication errors and mistakes of DNA repair mechanisms such as mismatch repair, excision repair, and strand break repair. Analysis of total DNA polymerase activity using partially purified protein extracts showed an age-dependent decrease in activity and an increase in fidelity. Analysis of the steady-state RNA level of DNA replicative polymerases α, δ, Pol I-like A, and Pol I-like B and the expression of mutS homolog 2 (Msh2) and Msh6 showed an age-dependent decrease. An in vitro repair assay showed lower efficiency of nonhomologous end joining in older plants, paralleled by an increase in Ku70 gene expression. Thus, we assume that the more frequent involvement of nonhomologous end joining in strand break repair and the less efficient end-joining repair together with lower levels of mismatch repair activities may be the main contributors to the observed age-dependent increase in microsatellite instability.

The allotetraploid Arabidopsis thaliana-Arabidopsis lyrata subsp. petraea as an alternative model system for the study of polyploidy in plants.

Polyploidy is known to be common in plants and recent work has focused on the rapid changes in genome structure and expression that occur upon polyploidization. In Arabidopsis, much of this work has been done on a synthetic allotetraploid obtained by crossing a tetraploid Arabidopsis thaliana (2n = 4x = 20) with A. arenosa (2n = 4x = 32). To explore an alternative route to polyploidy in this model species, we have developed a synthetic allopolyploid by crossing two diploid species: A. thaliana (2n = 2x = 10) and Arabidopsis lyrata subsp. petraea (2n = 2x = 16). F(1) hybrids were easy to obtain and phenotypically more similar to A. lyrata. Spontaneous chromosome doubling events occurred in about 25% of the F(1)s, thus restoring fertility. The resulting allotetraploids (2n = 26) exhibited many genomic changes typically reported upon polyploidization. Nucleolar dominance was observed as only the A. lyrata rDNA loci were expressed in the F(1) and allotetraploids. Changes in the degree of methylation were observed at almost 25% of the loci examined by MSAP analysis. Finally, structural genomic alterations did occur as a large deletion covering a significant portion of the upper arm of chromosome II was detected but no evidence of increased mobility of transposons was obtained. Such allotetraploids derived from two parents with sequenced (or soon to be sequenced) genomes offer much promise in elucidating the various changes that occur in newly synthesized polyploids.

An Arabidopsis MLH1 mutant exhibits reproductive defects and reveals a dual role for this gene in mitotic recombination.

The eukaryotic DNA mismatch repair (MMR) system contributes to maintaining genome integrity and DNA sequence fidelity in at least two important ways: by correcting errors arising during DNA replication, and also by preventing recombination events between divergent sequences. This study aimed to investigate the role of one key MMR gene in recombination. We obtained a mutant line in which the AtMLH1 gene has been disrupted by the insertion of a T-DNA within the coding region. Transcript analysis indicated that no full-length transcript was produced in mutant plants. The loss of a functional AtMLH1 gene led to a significant reduction in fertility in both homozygotes and heterozygotes, and we observed a strong bias against transmission of the mutant allele. To investigate the role of AtMLH1 in mitotic recombination, the mutant was crossed to a series of recombination reporter lines. A strong decrease (72%) in the frequency of homologous recombination was observed in the mutant. However, the decline in recombination due to homeology was less severe in the Atmlh1 mutant than in a wild-type control. These data demonstrate a dual role for AtMLH1 in recombination: it is both required for recombination and acts to limit recombination between diverged sequences.

The impact of sequence divergence and DNA mismatch repair on homeologous recombination in Arabidopsis.

We examined the effects of substrate divergence and DNA mismatch repair (MMR) on recombination in Arabidopsis thaliana. Relative to the frequency observed in plants with a homologous construct (0% divergence), recombination was decreased 4.1-, 9.6-, 11.7- or 20.3-fold, respectively, in lines with constructs containing 0.5%, 2%, 4% or 9% divergence between the recombination substrates. To evaluate the contribution of the MMR system in this decrease, 12 independent reporter lines (two or three lines per reporter construct) were crossed to an AtMSH2 T-DNA insertional mutant. We examined the recombination frequency in progeny homozygous for a reporter T-DNA and homozygous either for the wild type or the mutant allele of AtMSH2. The loss of MMR activity led to a two- to ninefold increase in homeologous recombination and the size of the increase did not seem to correlate with the amount of divergence. Inversely, complementation of the insertional mutant with a wild-type cDNA of AtMSH2 reduced recombination. Our results demonstrate clearly that sequence divergence can dramatically reduce the recombination frequency in plants and that the MMR system plays a part in this decrease.

Embolization of a massive retropubic hemorrhage following a tension-free vaginal tape (TVT) procedure: case report and literature review.

INTRODUCTION: Since its description by Ulmsten, the TVT procedure has been proven to be safe and well tolerated. Bleeding and hematoma formation, although rare, can occur. Both conservative and surgical managements of this complication have been described. MATERIALS: We report the first case in which a pelvic branch of the obturator artery was embolized using angiography. RESULTS: Our patient was spared surgical exploration and retained the TVT tape. CONCLUSION: Angiography with vessel embolization, when available, should be considered in the treatment of TVT-procedure retropubic hemorrhages.

Involvement of the Arabidopsis thaliana AtPMS1 gene in somatic repeat instability.

Mismatch repair (MMR) genes participate in the maintenance of genome stability in all organisms. Based on its high degree of sequence conservation, it seems likely that the AtPMS1 gene of Arabidopsis thaliana is part of the MMR system in this model plant. To test this hypothesis, we aimed to disrupt AtPMS1 function by over-expressing mutated alleles expected to result in a dominant negative effect. To create one mutant allele we substituted two amino acids in the MutL-box, and for the other mutant allele we deleted 87 amino acids comprising the whole MutL-box. Contrary to published reports in some eukaryotes, transgenic plants expressing these alleles did not exhibit a decrease in fertility nor any other visible phenotype. To examine the impact of these mutations on microsatellite instability, the phenotype most often observed in organisms defective in MMR, reporter lines containing a uidA (GUS) gene inactivated by the insertion of a synthetic microsatellite (G7 or G16) were used. GUS gene function in these lines can be restored following the loss of one base or the gain of two bases in the repetitive tract. This results in the observation of blue sectors on a white background following histochemical staining. In a subset of the transformants, a significant increase (2- to 28-fold) in microsatellite instability was observed relative to wild-type. This report shows that MMR function can be disrupted via a dominant negative approach, and it is the first report to describe the phenotypic consequence of disrupting the function of a MutL homolog in plants.