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Albertha J M Walhout
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April 20, 2018: Science
Frank Weber, Laurence C Walhout, Johanna C Escher
BACKGROUND: Propofol is often used for procedural sedation in children undergoing gastrointestinal endoscopy. Reliable assessment of the depth of hypnosis during the endoscopic procedure is challenging. Processed electroencephalography using the Narcotrend Index can help titrating propofol to a predefined sedation level. AIMS: The aim of this trial was to investigate the impact of Narcotrend Index-guided titration of propofol delivery on the speed of recovery. METHODS: Children, aged 12-17 years, undergoing gastrointestinal endoscopy under procedural sedation, had propofol delivered via target controlled infusion either based on Narcotrend Index guidance (group NI) or standard clinical parameters (group C)...
March 25, 2018: Paediatric Anaesthesia
Huimin Na, Olga Ponomarova, Gabrielle E Giese, Albertha J M Walhout
Vitamin B12 functions as a cofactor for methionine synthase to produce the anabolic methyl donor S-adenosylmethionine (SAM) and for methylmalonyl-CoA mutase to catabolize the short-chain fatty acid propionate. In the nematode Caenorhabditis elegans, maternally supplied vitamin B12 is required for the development of offspring. However, the mechanism for exporting vitamin B12 from the mother to the offspring is not yet known. Here, we use RNAi of more than 200 transporters with a vitamin B12-sensor transgene to identify the ABC transporter MRP-5 as a candidate vitamin B12 exporter...
March 20, 2018: Cell Reports
John S Reece-Hoyes, Albertha J M Walhout
The Gateway recombinatorial cloning system was developed for cloning multiple DNA fragments in parallel (e.g., in 96-well formats) in a standardized manner using the same enzymes. Gateway cloning is based on the highly specific integration and excision reactions of bacteriophage λ into and out of the Escherichia coli genome. Because the sites of recombination (" att " sites) are much longer (25-242 bp) than restriction sites, they are extremely unlikely to occur by chance in DNA fragments. Therefore, the same recombination enzyme can be used to robustly clone many different fragments of variable size in parallel reactions...
January 2, 2018: Cold Spring Harbor Protocols
John S Reece-Hoyes, Albertha J M Walhout
This protocol describes using the Gateway recombinatorial cloning system to simultaneously transfer a promoter and an open reading frame (ORF) from two different Entry clones into the same Destination vector using LR enzymes. A multisite cloning reaction transfers the inserts from multiple Entry clones into a single Destination vector. This type of recombination is much less efficient than transferring a single DNA fragment; however, the variety of Destination clones that can be generated in this manner is vast...
January 2, 2018: Cold Spring Harbor Protocols
John S Reece-Hoyes, Albertha J M Walhout
This protocol describes using the Gateway recombinatorial cloning system to create an Entry clone carrying an open reading frame (ORF) and then to transfer the ORF into a Destination vector. In this example, BP recombination is used to clone an ORF from a cDNA source into the Donor vector pDONR 221. The ORF from the resulting Entry clone is then transferred into the Destination vector pDEST-15; the product (the Destination clone) will express the ORF as an amino-terminal GST-fusion. The technique can be used as a guide for cloning any other DNA fragment of interest-a promoter sequence or 3' untranslated region (UTR), for example-with substitutions of different genetic material such as genomic DNA, att sites, and vectors as required...
January 2, 2018: Cold Spring Harbor Protocols
John S Reece-Hoyes, Albertha J M Walhout
Generating stocks of Entry and Destination vectors for use in the Gateway recombinatorial cloning system requires transforming them into Escherichia coli strain DB3.1, where they can replicate because this strain is immune to the effects of the ccdB gene carried in the Gateway cassette. However, mutations in the ccdB gene can arise at low frequency, and these mutant plasmids will consequently allow growth of standard cloning strains of E. coli (e.g., DH5α). Therefore, after making new stocks of Gateway plasmids, their ability to grow in cloning strains of E...
January 2, 2018: Cold Spring Harbor Protocols
Gea A Holtman, Yvonne Lisman-van Leeuwen, Boudewijn J Kollen, Obbe F Norbruis, Johanna C Escher, Laurence C Walhout, Angelika Kindermann, Yolanda B de Rijke, Patrick F van Rheenen, Marjolein Y Berger
BACKGROUND: In children with symptoms suggestive of inflammatory bowel disease (IBD) who present in primary care, the optimal test strategy for identifying those who require specialist care is unclear. We evaluated the following three test strategies to determine which was optimal for referring children with suspected IBD to specialist care: 1) alarm symptoms alone, 2) alarm symptoms plus c-reactive protein, and 3) alarm symptoms plus fecal calprotectin. METHODS: A prospective cohort study was conducted, including children with chronic gastrointestinal symptoms referred to pediatric gastroenterology...
2017: PloS One
Renée Walhout, Esther Verstraete, Martijn P van den Heuvel, Jan H Veldink, Leonard H van den Berg
OBJECTIVE: To investigate whether symptom development in motor neuron disease (MND) is a random or organized process. METHODS: Six hundred patients with amyotrophic lateral sclerosis (ALS), upper motor neuron (UMN) or lower motor neuron (LMN) phenotypes were invited for a questionnaire concerning symptom development. A binomial test was used to examine distribution of symptoms from site of onset. Development of symptoms over time was evaluated by Kaplan-Meier analysis...
February 2018: Amyotrophic Lateral Sclerosis and Frontotemporal Degeneration
Akihiro Mori, Amy D Holdorf, Albertha J M Walhout
Reverse genetic screens by RNA interference (RNAi) in model organisms such as the nematode Caenorhabditis elegans have provided numerous insights into gene function, thereby connecting genotype to phenotype. However, genes that contribute only subtly are often missed because relatively large numbers of measurements and reliable quantification are required to overcome experimental and biological noise that may mask subtle phenotypic effects. Here, we address this challenge by focusing on two phenotypes in C...
September 2017: Genes to Cells: Devoted to Molecular & Cellular Mechanisms
Alex M Tamburino, Ebru Kaymak, Shaleen Shrestha, Amy D Holdorf, Sean P Ryder, Albertha J M Walhout
Interactions between RNA binding proteins (RBPs) and mRNAs are critical to post-transcriptional gene regulation. Eukaryotic genomes encode thousands of mRNAs and hundreds of RBPs. However, in contrast to interactions between transcription factors (TFs) and DNA, the interactome between RBPs and RNA has been explored for only a small number of proteins and RNAs. This is largely because the focus has been on using 'protein-centered' (RBP-to-RNA) interaction mapping methods that identify the RNAs with which an individual RBP interacts...
2017: Translation
Queenie Hu, Dayana R D'Amora, Lesley T MacNeil, Albertha J M Walhout, Terrance J Kubiseski
Cellular damage caused by reactive oxygen species is believed to be a major contributor to age-associated diseases. Previously, we characterized the Caenorhabditis elegans Brap2 ortholog (BRAP-2) and found that it is required to prevent larval arrest in response to elevated levels of oxidative stress. Here, we report that C. elegans brap-2 mutants display increased expression of SKN-1-dependent, phase II detoxification enzymes that is dependent on PMK-1 (a p38 MAPK C. elegans ortholog). An RNA-interference screen was conducted using a transcription factor library to identify genes required for increased expression of the SKN-1 target gst-4 in brap-2 mutants...
August 2017: Genetics
Aurian P García-González, Ashlyn D Ritter, Shaleen Shrestha, Erik C Andersen, L Safak Yilmaz, Albertha J M Walhout
The human microbiota greatly affects physiology and disease; however, the contribution of bacteria to the response to chemotherapeutic drugs remains poorly understood. Caenorhabditis elegans and its bacterial diet provide a powerful system to study host-bacteria interactions. Here, we use this system to study how bacteria affect the C. elegans response to chemotherapeutics. We find that different bacterial species can increase the response to one drug yet decrease the effect of another. We perform genetic screens in two bacterial species using three chemotherapeutic drugs: 5-fluorouracil (5-FU), 5-fluoro-2'-deoxyuridine (FUDR), and camptothecin (CPT)...
April 20, 2017: Cell
Jingyan Zhang, Amy D Holdorf, Albertha Jm Walhout
Resident microbes of the human body, particularly the gut microbiota, provide essential functions for the host, and, therefore, have important roles in human health as well as mitigating disease. It is difficult to study the mechanisms by which the microbiota affect human health, especially at a systems-level, due to heterogeneity of human genomes, the complexity and heterogeneity of the gut microbiota, the challenge of growing these bacteria in the laboratory, and the lack of bacterial genetics in most microbiotal species...
August 2017: Current Opinion in Biotechnology
L Safak Yilmaz, Albertha Jm Walhout
Flux balance analysis (FBA) with genome-scale metabolic network models (GSMNM) allows systems level predictions of metabolism in a variety of organisms. Different types of predictions with different accuracy levels can be made depending on the applied experimental constraints ranging from measurement of exchange fluxes to the integration of gene expression data. Metabolic network modeling with model organisms has pioneered method development in this field. In addition, model organism GSMNMs are useful for basic understanding of metabolism, and in the case of animal models, for the study of metabolic human diseases...
February 2017: Current Opinion in Chemical Biology
Juan I Fuxman Bass, John S Reece-Hoyes, Albertha J M Walhout
An important question when studying gene regulation is which transcription factors (TFs) interact with which cis-regulatory elements, such as promoters and enhancers. Addressing this issue in complex multicellular organisms is challenging as several hundreds of TFs and thousands of regulatory elements must be considered in the context of different tissues and physiological conditions. Yeast one-hybrid (Y1H) assays provide a powerful "gene-centered" method to identify the TFs that can bind a DNA sequence of interest...
December 1, 2016: Cold Spring Harbor Protocols
Juan I Fuxman Bass, John S Reece-Hoyes, Albertha J M Walhout
Here, we present a protocol for amplifying DNA fragments from the genome of, or plasmids transformed into, yeast strains that require the use of the lytic enzyme zymolyase to break open the yeast cells by digesting the cell wall. Yeast strains requiring such treatment include YM4271 and Y1HaS2, whereas other yeast strains (e.g., MaV103) might not require treatment with Zymolyase.
December 1, 2016: Cold Spring Harbor Protocols
Juan I Fuxman Bass, John S Reece-Hoyes, Albertha J M Walhout
In this protocol, we present a qualitative assay for monitoring the level of expression of β-galactosidase, an enzyme encoded by the LacZ gene, in yeast. This is useful both for determining autoactivity of LacZ expression in yeast DNA "bait" strains and for assessing LacZ reporter gene activation mediated by a transcription factor "prey" interaction with a DNA bait of interest in yeast one-hybrid (Y1H) assays. In this colorimetric assay, yeast are lysed in liquid nitrogen and then assayed for β-galactosidase expression using the colorless compound X-gal, which turns blue in the presence of this enzyme...
December 1, 2016: Cold Spring Harbor Protocols
Juan I Fuxman Bass, John S Reece-Hoyes, Albertha J M Walhout
Yeast one-hybrid (Y1H) assays are used to identify which transcription factor (TF) "prey" molecules can bind a DNA fragment of interest that is used as "bait". Y1H assays involve introducing plasmids that encode TFs into a yeast "bait strain" in which the DNA fragment of interest is integrated upstream of one or more reporters, and activation of these reporters indicates that a TF-DNA interaction has occurred. These plasmids express each TF as a hybrid protein (hence the "one-hybrid" name) fused to the activation domain (AD) of the yeast TF Gal4...
December 1, 2016: Cold Spring Harbor Protocols
Juan I Fuxman Bass, John S Reece-Hoyes, Albertha J M Walhout
Yeast one-hybrid (Y1H) assays are used to identify which transcription factor (TF) "preys" can bind a DNA fragment of interest that is used as the "bait." Undertaking Y1H assays requires the generation of a yeast "bait strain" for each DNA fragment of interest that features the DNA bait coupled to a reporter(s). Plasmids encoding TFs fused to the Gal4 activation domain (AD) are then introduced into the bait strain, and activation of the reporter(s) indicates that a TF-DNA interaction has occurred. Here, we present a protocol for the first part of the strategy-the generation of a bait strain for Y1H assays...
December 1, 2016: Cold Spring Harbor Protocols
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