1 2985 140 GENETIC DIVERSITY FOR NITROGEN USE EFFICIENCY IN ARABIDOPSIS THALIANA. THE PLASTICITY OF PLANT GROWTH RESPONSE TO DIFFERING NITRATE AVAILABILITY RENDERS THE IDENTIFICATION OF BIOMARKERS DIFFICULT, BUT ALLOWS ACCESS TO GENETIC FACTORS AS TOOLS TO MODULATE ROOT SYSTEMS TO A WIDE RANGE OF SOIL CONDITIONS. NITROGEN AVAILABILITY IS A MAJOR DETERMINANT OF CROP YIELD. WHILE THE APPLICATION OF FERTILISER SUBSTANTIALLY INCREASES THE YIELD ON POOR SOILS, IT ALSO CAUSES NITRATE POLLUTION OF WATER RESOURCES AND HIGH COSTS FOR FARMERS. INCREASING NITROGEN USE EFFICIENCY IN CROP PLANTS IS A NECESSARY STEP TO IMPLEMENT LOW-INPUT AGRICULTURAL SYSTEMS. WE EXPLOITED THE GENETIC DIVERSITY PRESENT IN THE WORLDWIDE ARABIDOPSIS THALIANA POPULATION TO STUDY ADAPTIVE GROWTH PATTERNS AND CHANGES IN GENE EXPRESSION ASSOCIATED WITH CHRONIC LOW NITRATE STRESS, TO IDENTIFY BIOMARKERS ASSOCIATED WITH GOOD PLANT PERFORMANCE UNDER LOW NITRATE AVAILABILITY. ARABIDOPSIS ACCESSIONS WERE GROWN ON AGAR PLATES WITH LIMITED AND SUFFICIENT SUPPLY OF NITRATE TO MEASURE ROOT SYSTEM ARCHITECTURE AS WELL AS SHOOT AND ROOT FRESH WEIGHT. DIFFERENTIAL GENE EXPRESSION WAS DETERMINED USING AFFYMETRIX ATH1 ARRAYS. WE SHOW THAT THE RESPONSE TO DIFFERING NITRATE AVAILABILITY IS HIGHLY VARIABLE IN ARABIDOPSIS ACCESSIONS. ANALYSES OF VEGETATIVE SHOOT GROWTH AND ROOT SYSTEM ARCHITECTURE IDENTIFIED ACCESSION-SPECIFIC REACTION MODES TO COPE WITH LIMITED NITRATE AVAILABILITY. TRANSCRIPTION AND EPIGENETIC FACTORS WERE IDENTIFIED AS IMPORTANT PLAYERS IN THE ADAPTION TO LIMITED NITROGEN IN A GLOBAL GENE EXPRESSION ANALYSIS. FIVE NITRATE-RESPONSIVE GENES EMERGED AS POSSIBLE BIOMARKERS FOR NUE IN ARABIDOPSIS. THE PLASTICITY OF PLANT GROWTH IN RESPONSE TO DIFFERING NITRATE AVAILABILITY IN THE SUBSTRATE RENDERS THE IDENTIFICATION OF MORPHOLOGICAL AND MOLECULAR FEATURES AS BIOMARKERS DIFFICULT, BUT AT THE SAME TIME ALLOWS ACCESS TO A MULTITUDE OF GENETIC FACTORS WHICH CAN BE USED AS TOOLS TO MODULATE AND ADJUST ROOT SYSTEMS TO A WIDE RANGE OF SOIL CONDITIONS. 2019 2 3487 36 IDENTIFICATION OF DIFFERENTIALLY METHYLATED SITES WITH WEAK METHYLATION EFFECTS. DEOXYRIBONUCLEIC ACID (DNA) METHYLATION IS AN EPIGENETIC ALTERATION CRUCIAL FOR REGULATING STRESS RESPONSES. IDENTIFYING LARGE-SCALE DNA METHYLATION AT SINGLE NUCLEOTIDE RESOLUTION IS MADE POSSIBLE BY WHOLE GENOME BISULFITE SEQUENCING. AN ESSENTIAL TASK FOLLOWING THE GENERATION OF BISULFITE SEQUENCING DATA IS TO DETECT DIFFERENTIALLY METHYLATED CYTOSINES (DMCS) AMONG TREATMENTS. MOST STATISTICAL METHODS FOR DMC DETECTION DO NOT CONSIDER THE DEPENDENCY OF METHYLATION PATTERNS ACROSS THE GENOME, THUS POSSIBLY INFLATING TYPE I ERROR. FURTHERMORE, SMALL SAMPLE SIZES AND WEAK METHYLATION EFFECTS AMONG DIFFERENT PHENOTYPE CATEGORIES MAKE IT DIFFICULT FOR THESE STATISTICAL METHODS TO ACCURATELY DETECT DMCS. TO ADDRESS THESE ISSUES, THE WAVELET-BASED FUNCTIONAL MIXED MODEL (WFMM) WAS INTRODUCED TO DETECT DMCS. TO FURTHER EXAMINE THE PERFORMANCE OF WFMM IN DETECTING WEAK DIFFERENTIAL METHYLATION EVENTS, WE USED BOTH SIMULATED AND EMPIRICAL DATA AND COMPARE WFMM PERFORMANCE TO A POPULAR DMC DETECTION TOOL METHYLKIT. ANALYSES OF SIMULATED DATA THAT REPLICATED THE EFFECTS OF THE HERBICIDE GLYPHOSATE ON DNA METHYLATION IN ARABIDOPSIS THALIANA SHOW THAT WFMM RESULTS IN HIGHER SENSITIVITY AND SPECIFICITY IN DETECTING DMCS COMPARED TO METHYLKIT, ESPECIALLY WHEN THE METHYLATION DIFFERENCES AMONG PHENOTYPE GROUPS ARE SMALL. MOREOVER, THE PERFORMANCE OF WFMM IS ROBUST WITH RESPECT TO SMALL SAMPLE SIZES, MAKING IT PARTICULARLY ATTRACTIVE CONSIDERING THE CURRENT HIGH COSTS OF BISULFITE SEQUENCING. ANALYSIS OF EMPIRICAL ARABIDOPSIS THALIANA DATA UNDER VARYING GLYPHOSATE DOSAGES, AND THE ANALYSIS OF MONOZYGOTIC (MZ) TWINS WHO HAVE DIFFERENT PAIN SENSITIVITIES-BOTH DATASETS HAVE WEAK METHYLATION EFFECTS OF <1%-SHOW THAT WFMM CAN IDENTIFY MORE RELEVANT DMCS RELATED TO THE PHENOTYPE OF INTEREST THAN METHYLKIT. DIFFERENTIALLY METHYLATED REGIONS (DMRS) ARE GENOMIC REGIONS WITH DIFFERENT DNA METHYLATION STATUS ACROSS BIOLOGICAL SAMPLES. DMRS AND DMCS ARE ESSENTIALLY THE SAME CONCEPTS, WITH THE ONLY DIFFERENCE BEING HOW METHYLATION INFORMATION ACROSS THE GENOME IS SUMMARIZED. IF METHYLATION LEVELS ARE DETERMINED BY GROUPING NEIGHBORING CYTOSINE SITES, THEN THEY ARE DMRS; IF METHYLATION LEVELS ARE CALCULATED BASED ON SINGLE CYTOSINES, THEY ARE DMCS. 2018 3 840 31 CHEMOENZYMATIC LABELING OF DNA METHYLATION PATTERNS FOR SINGLE-MOLECULE EPIGENETIC MAPPING. DNA METHYLATION, SPECIFICALLY, METHYLATION OF CYTOSINE (C) NUCLEOTIDES AT THE 5-CARBON POSITION (5-MC), IS THE MOST STUDIED AND SIGNIFICANT EPIGENETIC MODIFICATION. HERE WE DEVELOPED A CHEMOENZYMATIC PROCEDURE TO FLUORESCENTLY LABEL NON-METHYLATED CYTOSINES IN CPG CONTEXT, ALLOWING EPIGENETIC PROFILING OF SINGLE DNA MOLECULES SPANNING HUNDREDS OF THOUSANDS OF BASE PAIRS. WE USED A CPG METHYLTRANSFERASE WITH A SYNTHETIC S-ADENOSYL-L-METHIONINE COFACTOR ANALOG TO TRANSFER AN AZIDE TO CYTOSINES INSTEAD OF THE NATURAL METHYL GROUP. A FLUOROPHORE WAS THEN CLICKED ONTO THE DNA, REPORTING ON THE AMOUNT AND POSITION OF NON-METHYLATED CPGS. WE FOUND THAT LABELING EFFICIENCY WAS INCREASED UP TO 2-FOLD BY THE ADDITION OF A NUCLEOSIDASE, PRESUMABLY BY DEGRADING THE INACTIVE BY-PRODUCT OF THE COFACTOR AFTER LABELING, PREVENTING ITS INHIBITORY EFFECT. WE USED THE METHOD TO DETERMINE THE DECLINE IN GLOBAL DNA METHYLATION IN A CHRONIC LYMPHOCYTIC LEUKEMIA PATIENT AND THEN PERFORMED WHOLE-GENOME METHYLATION MAPPING OF THE MODEL PLANT ARABIDOPSIS THALIANA. OUR GENOME MAPS SHOW HIGH CONCORDANCE WITH PUBLISHED BISULFITE SEQUENCING METHYLATION MAPS. ALTHOUGH MAPPING RESOLUTION IS LIMITED BY OPTICAL DETECTION TO 500-1000 BP, THE LABELED DNA MOLECULES PRODUCED BY THIS APPROACH ARE HUNDREDS OF THOUSANDS OF BASE PAIRS LONG, ALLOWING ACCESS TO LONG REPETITIVE AND STRUCTURALLY VARIABLE GENOMIC REGIONS. 2022 4 2647 33 EPIGENOMIC PLASTICITY OF ARABIDOPSIS MSH1 MUTANTS UNDER PROLONGED COLD STRESS. DYNAMIC TRANSCRIPTIONAL AND EPIGENETIC CHANGES ENABLE RAPID ADAPTIVE BENEFIT TO ENVIRONMENTAL FLUCTUATIONS. HOWEVER, THE UNDERLYING MECHANISMS AND THE EXTENT TO WHICH THIS OCCURS ARE NOT WELL KNOWN. MUTS HOMOLOG 1 (MSH1) MUTANTS CAUSE HERITABLE DEVELOPMENTAL PHENOTYPES ACCOMPANIED BY MODULATION OF DEFENSE, PHYTOHORMONE, STRESS-RESPONSE, AND CIRCADIAN RHYTHM GENES, AS WELL AS HERITABLE CHANGES IN DNA METHYLATION PATTERNS. CONSISTENT WITH GENE EXPRESSION CHANGES, MSH1 MUTANTS DISPLAY ENHANCED TOLERANCE FOR ABIOTIC STRESS INCLUDING DROUGHT AND SALT STRESS, WHILE SHOWING INCREASED SUSCEPTIBILITY TO FREEZING TEMPERATURES. DESPITE CHANGES IN DEFENSE AND BIOTIC STRESS-RESPONSE GENES, MSH1 MUTANTS SHOWED INCREASING SUSCEPTIBILITY TO THE BACTERIAL PATHOGEN PSEUDOMONAS SYRINGAE. OUR RESULTS SUGGEST THAT CHRONIC COLD AND LOW LIGHT STRESS (10 DEGREES C, 150 MUMOL M(-2) S(-1)) INFLUENCES NON-CG METHYLATION TO A GREATER DEGREE IN MSH1 MUTANTS COMPARED TO WILD-TYPE COL-0. FURTHERMORE, CHG CHANGES ARE MORE CLOSELY PERICENTROMERIC, WHEREAS CHH CHANGES ARE GENERALLY MORE DISPERSED. THIS INCREASED VARIATION IN NON-CG METHYLATION PATTERN DOES NOT SIGNIFICANTLY AFFECT THE MSH1-DERIVED ENHANCED GROWTH BEHAVIOR AFTER MUTANTS ARE CROSSED WITH ISOGENIC WILD TYPE, REITERATING THE IMPORTANCE OF CG METHYLATION CHANGES IN MSH1-DERIVED ENHANCED VIGOR. THESE RESULTS INDICATE THAT MSH1METHYLOME IS HYPER-RESPONSIVE TO ENVIRONMENTAL STRESS IN A MANNER DISTINCT FROM THE WILD-TYPE RESPONSE, BUT CG METHYLATION CHANGES ARE POTENTIALLY RESPONSIBLE FOR GROWTH VIGOR CHANGES IN THE CROSSED PROGENY. 2018 5 5330 33 PUTATIVE EPIGENETIC BIOMARKERS OF STRESS IN RED BLOOD CELLS OF CHICKENS REARED ACROSS DIFFERENT BIOMES. PRODUCTION ANIMALS ARE CONSTANTLY SUBJECTED TO EARLY ADVERSE ENVIRONMENTAL CONDITIONS THAT INFLUENCE THE ADULT PHENOTYPE AND PRODUCE EPIGENETIC EFFECTS. CPG DINUCLEOTIDE METHYLATION IN RED BLOOD CELLS (RBC) COULD BE A USEFUL EPIGENETIC BIOMARKER TO IDENTIFY ANIMALS SUBJECTED TO CHRONIC STRESS IN THE PRODUCTION ENVIRONMENT. HERE WE COMPARED A REDUCED FRACTION OF THE RBC METHYLOME OF CHICKENS EXPOSED TO SOCIAL ISOLATION TO NON-EXPOSED. THESE EXPERIMENTS WERE PERFORMED IN TWO DIFFERENT LOCATIONS: BRAZIL AND SWEDEN. THE AIM WAS TO IDENTIFY STRESS-ASSOCIATED DNA METHYLATION PROFILES IN RBC ACROSS THESE POPULATIONS, IN SPITE OF THE VARIABLE CONDITIONS TO WHICH BIRDS ARE EXPOSED IN EACH FACILITY AND THEIR DIFFERENT LINEAGES. BIRDS WERE INCREASINGLY EXPOSED TO A SOCIAL ISOLATION TREATMENT, COMBINED WITH FOOD AND WATER DEPRIVATION, AT RANDOM PERIODS OF THE DAY FROM WEEKS 1-4 AFTER HATCHING. WE THEN COLLECTED THE RBC DNA FROM INDIVIDUALS AND COMPARED A REDUCED FRACTION OF THEIR METHYLOME BETWEEN THE EXPERIMENTAL GROUPS USING TWO BIOINFORMATIC APPROACHES TO IDENTIFY DIFFERENTIALLY METHYLATED REGIONS (DMRS): ONE USING FIXED-SIZE WINDOWS AND ANOTHER THAT PRESELECTED DIFFERENTIAL PEAKS WITH MACS2. THREE LEVELS OF SIGNIFICANCE WERE USED (P 50%) OF SPECIFIC TRANSCRIPTION FACTOR BINDING SITES. THREE OVERLAPPING DMRS WERE FOUND BETWEEN THE BR AND SW POPULATION USING THE MOST RELAXED P-VALUE (P