Predictable and stable epimutations induced during clonal plant propagation with embryonic transcription factor.

Clonal propagation is frequently used in commercial plant breeding and biotechnology programs because it minimizes genetic variation, yet it is not uncommon to observe clonal plants with stable phenotypic changes, a phenomenon known as somaclonal variation. Several studies have linked epigenetic modifications induced during regeneration with this newly acquired phenotypic variation. However, the factors that determine the extent of somaclonal variation and the molecular changes underpinning this process remain poorly understood. To address this gap in our knowledge, we compared clonally propagated Arabidopsis thaliana plants derived from somatic embryogenesis using two different embryonic transcription factors- RWP-RK DOMAIN-CONTAINING 4 (RKD4) or LEAFY COTYLEDON2 (LEC2) and from two epigenetically distinct founder tissues. We found that both the epi(genetic) status of the explant and the regeneration protocol employed play critical roles in shaping the molecular and phenotypic landscape of clonal plants. Phenotypic variation in regenerated plants can be largely explained by the inheritance of tissue-specific DNA methylation imprints, which are associated with specific transcriptional and metabolic changes in sexual progeny of clonal plants. For instance, regenerants were particularly affected by the inheritance of root-specific epigenetic imprints, which were associated with an increased accumulation of salicylic acid in leaves and accelerated plant senescence. Collectively, our data reveal specific pathways underpinning the phenotypic and molecular variation that arise and accumulate in clonal plant populations.

A transposon surveillance mechanism that safeguards plant male fertility during stress.

Although plants are able to withstand a range of environmental conditions, spikes in ambient temperature can impact plant fertility causing reductions in seed yield and notable economic losses1,2. Therefore, understanding the precise molecular mechanisms that underpin plant fertility under environmental constraints is critical to safeguarding future food production3. Here, we identified two Argonaute-like proteins whose activities are required to sustain male fertility in maize plants under high temperatures. We found that MALE-ASSOCIATED ARGONAUTE-1 and -2 associate with temperature-induced phased secondary small RNAs in pre-meiotic anthers and are essential to controlling the activity of retrotransposons in male meiocyte initials. Biochemical and structural analyses revealed how male-associated Argonaute activity and its interaction with retrotransposon RNA targets is modulated through the dynamic phosphorylation of a set of highly conserved, surface-located serine residues. Our results demonstrate that an Argonaute-dependent, RNA-guided surveillance mechanism is critical in plants to sustain male fertility under environmentally constrained conditions, by controlling the mutagenic activity of transposons in male germ cells.

A new role for histone demethylases in the maintenance of plant genome integrity.

Histone modifications deposited by the Polycomb repressive complex 2 (PRC2) play a critical role in the control of growth, development, and adaptation to environmental fluctuations of most multicellular eukaryotes. The catalytic activity of PRC2 is counteracted by Jumonji-type (JMJ) histone demethylases, which shapes the genomic distribution of H3K27me3. Here, we show that two JMJ histone demethylases in Arabidopsis, EARLY FLOWERING 6 (ELF6) and RELATIVE OF EARLY FLOWERING 6 (REF6), play distinct roles in H3K27me3 and H3K27me1 homeostasis. We show that failure to reset these chromatin marks during sexual reproduction results in the transgenerational inheritance of histone marks, which cause a loss of DNA methylation at heterochromatic loci and transposon activation. Thus, Jumonji-type histone demethylases play a dual role in plants by helping to maintain transcriptional states through development and safeguard genome integrity during sexual reproduction.

137Cs Dosimeter Irradiation Facilities: Calibration Frequency, Precision, and Accuracy.

Many dosimeter and instrument calibration sources, especially Cs irradiators permanently installed in facilities, are infrequently calibrated since their geometry is not subject to large variation, their mechanisms are simple, and their operation can be visibly error-free for decades. Only decay corrections are needed to know delivered doses at fixed locations once a thorough characterization of such facilities is completed. For one such Cs source, however, collected current values in a span of a few days were found to drop significantly. Malfunction of the internal positioning mechanisms through wear were found to be the cause. This paper suggests periodic source calibrations for the timely identification of source failures that could cause gross errors in dose delivery. In addition, a rigorous analysis of the magnitude of uncertainties and errors in dose delivery using a calibration source is included, which is based upon newly collected experimental data. This provides a technical basis for calibration procedures to ensure a given accuracy and precision of dose delivery.

Design of Interrogation Protocols for Radiation Dose Measurements Using Optically-Stimulated Luminescent Dosimeters.

Optically-stimulated luminescent dosimeters are capable of being interrogated multiple times post-irradiation. Each interrogation removes a fraction of the signal stored within the optically-stimulated luminescent dosimeter. This signal loss must be corrected to avoid systematic errors in estimating the average signal of a series of optically-stimulated luminescent dosimeter interrogations and requires a minimum number of consecutive readings to determine an average signal that is within a desired accuracy of the true signal with a desired statistical confidence. This paper establishes a technical basis for determining the required number of readings for a particular application of these dosimeters when using certain OSL dosimetry systems.

Impact of long-term medical conditions on the outcomes of psychological therapy for depression and anxiety.

BACKGROUND: Long-term conditions often coexist with depression and anxiety. AIMS: To assess the effectiveness of stepped-care psychological therapies for patients with long-term conditions. METHOD: Data from 28 498 patients were analysed using regression to model depression (Patient Health Questionnaire (PHQ-9)) and anxiety (Generalised Anxiety Disorder scale (GAD-7)) outcomes. Post-treatment symptoms and effect sizes (d) were estimated for individuals with and without long-term conditions, controlling for covariates. The likelihood of access and response to intensive psychological interventions was also examined. RESULTS: Higher post-treatment symptoms were predicted for patients with musculoskeletal problems (d = 0.22-0.27), chronic obstructive pulmonary disease (d = 0.26-0.33), diabetes (d = 0.05-0.13) and psychotic disorders (d = 0.50-0.58). Most long-term conditions were associated with greater odds of accessing high-intensity therapies, yet individuals who accessed these continued to have higher average post-treatment symptoms. CONCLUSIONS: Some long-term conditions are associated with greater intensity of care and poorer outcomes after therapy.

Quantification of Shear Wave Scattering From Far-Surface Defects via Ultrasonic Wavefield Measurements.

Nondestructive evaluation methods rely on prior knowledge of the expected interaction of ultrasonic waves with defects to inform detection and characterization decisions. Wavefield imaging, which refers to the measurement of signals originating from a spatially fixed source on a 2-D rectilinear grid, can be applied to visualize the effect of a subsurface scatterer on surface-measured wave motion. Here, obliquely incident shear waves are directed at the far surface of a plate containing a through-hole using the well-known angle-beam ultrasonic inspection method. A laser vibrometer and laboratory scanner are used to record the resulting out-of-plane motion on the plate surface in the vicinity of the through-hole both before and after a far-surface corner notch is introduced and subsequently enlarged. Waves scattered from the notch are isolated from the incident and hole-scattered waves via baseline subtraction of wavefields. The scattered wavefields are then filtered in the frequency-wavenumber domain to separate Rayleigh, shear, and longitudinal contributions to the scattered wavefield. The filtered wavefields are interpolated in space to obtain 2-D radial wavefield slices originating at the base of the notch. Each radial slice is analyzed to quantify scattering as a function of observation direction, resulting in Rayleigh, shear, and longitudinal scattering profiles for each notch size. The results are compared for four different notch sizes and two transducer orientations.

Nutrient supplements boost yeast transformation efficiency.

Efficiency of yeast transformation is determined by the rate of yeast endocytosis. The aim of this study was to investigate the effect of introducing amino acids and other nutrients (inositol, adenine, or p-aminobenzoic acid) in the transformation medium to develop a highly efficient yeast transformation protocol. The target of rapamycin complex 1 (TORC1) kinase signalling complex influences the rate of yeast endocytosis. TORC signaling is induced by amino acids in the media. Here, we found that increasing the concentration of amino acids and other nutrients in the growth media lead to an increase yeast transformation efficiency up to 107 CFU per µg plasmid DNA and per 108 cells with a 13.8 kb plasmid DNA. This is over 130 times that of current published methods. This improvement may facilitate more efficient experimentation in which transformation efficiency is critical, such as yeast two-hybrid screening.

Health status of New Zealand European, Maori, and Pacific patients with diabetes at 242 New Zealand general practices.

OBJECTIVE: To compare the care and health status of different ethnic groups attending general practices with diabetes. METHOD: We analysed information about 13,281 patients with any type of diabetes, collected by 242 general practices in the first visit of the Southlink Independent Practitioner Association's Get Checked program. These patients constituted about 60% of patients with diabetes in the South Island of New Zealand. RESULTS: 13,196 (99.4%) patients had Type 1 or Type 2 diabetes. Of these, 11,911 (90.3%) were Europeans, and 759 (5.8%) were Maori or Pacific Islanders (mostly of Samoan, Tongan, Niuean, or Cook Islands origin). There was no difference between ethnic groups in total cholesterol, proportions on oral therapy or statins, or having a foot check. Maori and Pacific Islanders had poorer glycaemic control (HbA1c > 8.0 for 41.5% of Maori or Pacific Islanders versus 23.8% of New Zealand Europeans; 95% confidence interval for the difference [CI]: 14.0, 21.1), and were less likely to have retinopathy screening (71.9% versus 77.9%; CI: -9.2, -2.6). In patients with Type 2 diabetes (and compared with Europeans) Maori and Pacific Islanders were younger, had higher mean body mass indices (males 33.9 versus 29.5; CI: 3.9, 5.0 and females - 34.6 versus 30.7; CI: 3.2, 4.6) and diastolic blood pressures 82.4 mmHg versus 78.7 mmHg (CI: 2.9, 4.5), and were more likely to smoke (27.5% versus 10.9%; CI: 13.3, 19.9). Overall, Maori and Pacific Islanders were more likely to be at high risk for microvascular complications (9.0% versus 4.4%; CI: 2.5, 6.6). CONCLUSIONS: In this study, Maori and Pacific Island patients had a demographic profile suggesting greater health vulnerability (especially for those with Type 2 diabetes) yet similar routine diabetes care (especially for those with Type 1 diabetes). Ethnic inequalities were noted in seven of nine health status measures. IMPLICATIONS: The Get Checked program aims to increase the health of all patients with diabetes but whether it accentuates or diminishes ethnic disparities is not yet known.

Hospital admissions in diabetic and non-diabetic patients: a case-control study.

AIM: To examine differences in morbidity and rates of hospital admission between diabetes patients and patients without diabetes in New Zealand. METHODS: A 1,123 and 11,325 patients with Types 1 and 2 diabetes in the Southlink Health diabetes register were identified. Types 1 and 2 diabetes patients were matched with non-diabetic patients drawn from primary care patient registers. Hospital admission rates for diabetic complications and general medical conditions, length of stay in hospital, patients readmitted, deaths in hospital and hospital procedures were analyzed for the 3-year period from 2000 to 2002. RESULTS: Diabetes patients were more likely to be admitted to hospital for any reason than patients without diabetes (odds ratio (OR) 2.55, 95% confidence interval (CI) 2.13-3.04, p<0.001 for Type 1 patients; OR 1.40, CI 1.33-1.48, p<0.001 for Type 2 patients). A 46% (770) of all admissions for Type 1 patients were due to complications arising from diabetes and 33% (4685) for Type 2 patients. Major complications included ischaemic heart disease, heart failure, cataracts and conditions specific to diabetes. CONCLUSIONS: Increasing prevalence of diabetes will increase demand for hospital services overall, and particularly for inpatient care related to macroangiopathy, ophthalmic and renal problems and peripheral circulatory disorders.