Identification of Postharvest Senescence Regulators Through Map-Based Cloning Using Detached Arabidopsis Inflorescences as a Model Tissue.

Postharvest deterioration of fruits and vegetables can be accelerated by biological, environmental, and physiological stresses. Fully understanding tissue response to harvest will provide new opportunities for limiting postharvest losses during handling and storage. The model plant Arabidopsis thaliana (Arabidopsis) has many attributes that make it excellent for studying the underlying control of postharvest responses. It is also one of the best resourced plants with numerous web-based bioinformatic programs and large numbers of mutant collections. Here we introduce a novel assay system called AIDA (the Arabidopsis Inflorescence Degreening Assay) that we developed for understanding postharvest response of immature tissues. We also demonstrate how the high-throughput screening capability of AIDA can be used with mapping technologies (high-resolution melting [HRM] and needle in the k-stack [NIKS]) to identify regulators of postharvest senescence in ethyl methanesulfonate (EMS) mutagenized plant populations. Whether it is best to use HRM or NIKS or both technologies will depend on your laboratory facilities and computing capabilities.

Staying green postharvest: how three mutations in the Arabidopsis chlorophyll b reductase gene NYC1 delay degreening by distinct mechanisms.

Stresses such as energy deprivation, wounding and water-supply disruption often contribute to rapid deterioration of harvested tissues. To uncover the genetic regulation behind such stresses, a simple assessment system was used to detect senescence mutants in conjunction with two rapid mapping techniques to identify the causal mutations. To demonstrate the power of this approach, immature inflorescences of Arabidopsis plants that contained ethyl methanesulfonate-induced lesions were detached and screened for altered timing of dark-induced senescence. Numerous mutant lines displaying accelerated or delayed timing of senescence relative to wild type were discovered. The underlying mutations in three of these were identified using High Resolution Melting analysis to map to a chromosomal arm followed by a whole-genome sequencing-based mapping method, termed 'Needle in the K-Stack', to identify the causal lesions. All three mutations were single base pair changes and occurred in the same gene, NON-YELLOW COLORING1 (NYC1), a chlorophyll b reductase of the short-chain dehydrogenase/reductase (SDR) superfamily. This was consistent with the mutants preferentially retaining chlorophyll b, although substantial amounts of chlorophyll b were still lost. The single base pair mutations disrupted NYC1 function by three distinct mechanisms, one by producing a termination codon, the second by interfering with correct intron splicing and the third by replacing a highly conserved proline with a non-equivalent serine residue. This non-synonymous amino acid change, which occurred in the NADPH binding domain of NYC1, is the first example of such a mutation in an SDR protein inhibiting a physiological response in plants.

Genomes of 'Candidatus Liberibacter solanacearum' Haplotype A from New Zealand and the United States Suggest Significant Genome Plasticity in the Species.

'Candidatus Liberibacter solanacearum' contains two solanaceous crop-infecting haplotypes, A and B. Two haplotype A draft genomes were assembled and compared with ZC1 (haplotype B), revealing inversion and relocation genomic rearrangements, numerous single-nucleotide polymorphisms, and differences in phage-related regions. Differences in prophage location and sequence were seen both within and between haplotype comparisons. OrthoMCL and BLAST analyses identified 46 putative coding sequences present in haplotype A that were not present in haplotype B. Thirty-eight of these loci were not found in sequences from other Liberibacter spp. Quantitative polymerase chain reaction (qPCR) assays designed to amplify sequences from 15 of these loci were screened against a panel of 'Ca. L. solanacearum'-positive samples to investigate genetic diversity. Seven of the assays demonstrated within-haplotype diversity; five failed to amplify loci in at least one haplotype A sample while three assays produced amplicons from some haplotype B samples. Eight of the loci assays showed consistent A-B differentiation. Differences in genome arrangements, prophage, and qPCR results suggesting locus diversity within the haplotypes provide more evidence for genetic complexity in this emerging bacterial species.

Exercise-associated hyponatremia with exertional rhabdomyolysis: importance of proper treatment.

BACKGROUND: Proper acute management of exercise-associated hyponatremia (EAH) has been known for decades, yet this information has not been uniformly implemented. Since treatment of EAH with isotonic fluids can result in delayed recovery and death, it is important that proper acute management in the field and hospital be utilized. CASE REPORT: We describe a participant of the 161-km Western States Endurance Run (WSER) who presented with seizure after dropping out at 145 km. He had gained 2.2% of his initial weight by 126 km from using sodium supplements and drinking copious volumes of fluids. He was treated promptly in the field for presumed EAH with two intravenous boluses of 100 mL of 3% hypertonic saline and showed rapid improvement in neurologic status. His recovery was then delayed with the use of high volumes of intravenous isotonic fluids, apparently for concern over his mild exertional rhabdomyolysis. CONCLUSIONS: Symptomatic EAH should be acutely managed with hypertonic saline, whereas treatment with high volumes of isotonic fluids may delay recovery and has even resulted in deaths from cerebral edema. Concern over central pontine myelinolysis from rapid correction of hyponatremia in EAH is unsupported. Furthermore, the exertional rhabdomyolysis often associated with EAH, and the concern over progression to acute kidney failure, should not dictate initial treatment.

Carbon deprivation-driven transcriptome reprogramming in detached developmentally arresting Arabidopsis inflorescences.

Senescence is genetically controlled and activated in mature tissues during aging. However, immature plant tissues also display senescence-like symptoms when continuously exposed to adverse energy-depleting conditions. We used detached dark-held immature inflorescences of Arabidopsis (Arabidopsis thaliana) to understand the metabolic reprogramming occurring in immature tissues transitioning from rapid growth to precocious senescence. Macroscopic growth of the detached inflorescences rapidly ceased upon placement in water in the dark at 21°C. Inflorescences were completely degreened by 120 h of dark incubation and by 24 h had already lost 24% of their chlorophyll and 34% of their protein content. Comparative transcriptome profiling at 24 h revealed that inflorescence response at 24 h had a large carbon-deprivation component. Genes that positively regulate developmental senescence (ARABIDOPSIS NAC DOMAIN CONTAINING PROTEIN92) and shade-avoidance syndrome (PHYTOCHROME INTERACTING FACTOR4 [PIF4] and PIF5) were up-regulated within 24 h. Mutations in these genes delayed degreening of the inflorescences. Their up-regulation was suppressed in dark-held inflorescences by glucose treatment, which promoted macroscopic growth and development and inhibited degreening of the inflorescences. Detached inflorescences held in the dark for 4 d were still able to reinitiate development to produce siliques upon being brought out to the light, indicating that the transcriptional reprogramming at 24 h was adaptive and reversible. Our results suggest that the response of detached immature tissues to dark storage involves interactions between carbohydrate status sensing and light deprivation signaling and that the dark-adaptive response of the tissues appears to utilize some of the same key regulators as developmental senescence.

Nutraceutical-mediated restoration of wild-type levels of IKBKAP-encoded IKAP protein in familial dysautonomia-derived cells.

SCOPE: The reported ability to modulate the production of the wild-type transcript in cells bearing the splice-altering familial dysautonomia (FD)-causing mutation in the IKBKAP gene prompted an evaluation of the impact of commonly consumed nutraceuticals on the splicing of this transcript. METHODS AND RESULTS: Screening efforts revealed the ability of the isoflavones, genistein, and daidzein, to impact splicing and increase the production of the wild-type, exon-20-containing, transcript, and the full-length IKBKAP-encoded IΚB kinase complex associated protein(IKAP) in FD-derived cells. Genistein was also found to impact splicing in neuronal cells, a cell type profoundly impacted by FD. The simultaneous exposure of FD-derived cells to genistein and epigallocatechin gallate (EGCG) resulted in the almost exclusive production of the exon-20-containing transcript and the production of wild-type amounts of IKAP protein. CONCLUSION: This study represents the first demonstration that the isoflavones, genistein and daidzein, possess splice-altering capabilities and that simultaneous treatment with genistein and EGCG reverses the splice-altering impact of the FD-causing mutation. These findings support the clinical evaluation of the therapeutic impact of the combined administration of these two commonly consumed nutraceuticals on this patient population and suggest a broader evaluation of the impact of these nutraceuticals on the in vivo RNA splicing process.

Neural basis of stereotype-induced shifts in women's mental rotation performance.

Recent negative focus on women's academic abilities has fueled disputes over gender disparities in the sciences. The controversy derives, in part, from women's relatively poorer performance in aptitude tests, many of which require skills of spatial reasoning. We used functional magnetic imaging to examine the neural structure underlying shifts in women's performance of a spatial reasoning task induced by positive and negative stereotypes. Three groups of participants performed a task involving imagined rotations of the self. Prior to scanning, the positive stereotype group was exposed to a false but plausible stereotype of women's superior perspective-taking abilities; the negative stereotype group was exposed to the pervasive stereotype that men outperform women on spatial tasks; and the control group received neutral information. The significantly poorer performance we found in the negative stereotype group corresponded to increased activation in brain regions associated with increased emotional load. In contrast, the significantly improved performance we found in the positive stereotype group was associated with increased activation in visual processing areas and, to a lesser degree, complex working memory processes. These findings suggest that stereotype messages affect the brain selectively, with positive messages producing relatively more efficient neural strategies than negative messages.

Working in partnership in the antenatal period: what do child and family health nurses do?

BACKGROUND: There is strong evidence that comprehensive sustained home visiting programs, commencing antenatally can improve child and maternal outcomes for vulnerable families. Community child and family health nurses, who traditionally engage with families post-birth, are well placed to provide interventions in the antenatal period. There is, however, little information on what home visiting nurses do, particularly in the antenatal period. An Australian trial of sustained nurse home visiting provides the opportunity to explore what child and family health nurses actually do in this new area of antenatal intervention. METHOD: Nurses completed a checklist following each home visit detailing the interventions undertaken. Descriptive analysis was undertaken to describe the frequency of each of interventions. Factor analysis was undertaken to group the interventions into clusters. Further analysis was undertaken to determine if the clusters of interventions were associated with the frequency of home visits or characteristics of the mothers/families. RESULT: Four clusters of interventions were identified: comprehensive range of physical and psychosocial care for most families; ongoing management of lower risk needs for mothers who were young, unsupported or had a history of mental health problems; preventive care for first-time mothers; and management of high risk needs (drugs and alcohol and domestic violence) in conjunction with other professionals. DISCUSSION AND CONCLUSION: The interventions undertaken reflect the conceptual framework of the program. Nurses are delivering a comprehensive range of physical and psychosocial care to most women and families in the antenatal period, with some groups of women receiving additional support related to differing areas of needs.

Anticipated socio-environmental impacts of the proposed Little Darby National Wildlife Refuge in Ohio.

Data were collected during the summer of 2000 from 146 residents living in a rural area located in central Ohio that had been identified as a possible site for a national wildlife refuge. The purpose of the study was to assess anticipated socio-economic and environmental impacts of the proposed refuge on local people and natural ecosystems. A 'vested interests' theoretical model was developed to guide the investigation. The theoretical model posits that attitudes of local people toward externally induced projects are a function of costs and benefits individuals expect to receive as a result of the development action. The theory posits that individuals who expect to receive greater benefits from the refuge will exhibit more favorable attitudes toward the proposed project. Anticipated impacts of the proposed refuge were assessed with a Likert-type attitude scale that was shown to be highly reliable. Variables measuring specific costs and benefits associated with the proposed project were used as predictive variables. Descriptive statistics demonstrated that respondents believed the proposed wildlife refuge would generate more costs than benefits for local residents. Multiple linear regression findings demonstrated that six variables were significant in explaining 65.1% of the variance in the attitudes toward the proposed project. The significant variables were as follows: perceived costs and benefits associated with the proposed project, perceived water quality within the Little Darby Creek at the time of the data collection, age of primary income earner, expected future water quality within the Little Darby Creek, expected impact of farmland transition on the household, and attitude toward private property rights. Study findings consistently support research hypotheses.