Characterizing the Arabidopsis frd3 mutant through an activation tagging screen [abstract]

Abstract only availableIron is an essential element present in many common proteins, and is crucial in many metabolic pathways. This role is evident in the disorders due to iron deficiency. Anemia, caused by iron deficiency, is the most common nutritional disorder affecting the world's population. As most people depend primarily on plants for their nutritional needs, one way of reducing this problem will be to enhance the bioavailable iron content of plants. A better understanding of how plants acquire, transport and store iron is needed before this goal can be achieved. The Arabidopsis frd3 mutant constitutively activates its iron uptake mechanisms, resulting in an over accumulation of iron and other metals. However iron is mislocalized and never enters leaf cells where it is ultimately required. Recent work has suggested that the FRD3 protein transports citrate into the root vasculature which is necessary for the correct localization of iron throughout the plant. One way to learn more about the FRD3 protein, and about iron homeostasis in plants, is through an activation tagging screen looking for suppressors of the frd3 phenotype. Briefly, the activation tagging construct has been transformed into frd3 plants using the established agrobacterium floral dip method. Suppressor mutants have been selected using ferric chelate reductase assay. Putative mutants have been transferred to soil, and three generations have been screened. After confirmation, TAIL-PCR will be used to identify activated genes. Additional mutant characterization will be carried out at this stage. At least three classes of genes could be identified through this screen: (1) other citrate effluxers that will perform the same function as FRD3, (2) repressors of FRO2, the root ferric chelate reductase or (3) transporters that would facilitate movement of iron into leaf cells. Discovery and further characterization of these genes would greatly facilitate our understanding of iron nutrition in plants.MU Monsanto Undergraduate Research Fellowshi

Silencing of three members of the cytochrome p450 family of genes to uncover their role in iron regulation in A. thaliana

Abstract only availableIron absorption and distribution by an organism needs to be tightly regulated because iron is essential but in excess it can be dangerous and may even result in death. Through microarray analyses of iron-starved Arabidopsis plants (WT and a mutant) we discovered that three members of the Cytochrome p450 family of genes are up-regulated under iron deficiency. The genes are At4g31940, At4g31950 and At4g31970 and they are highly homologous to each other. Individual Arabidopsis knockouts do not show a phenotype suggesting that their function may be redundant. Since obtaining a triple mutant plant via crossings of individual KO lines is not achievable due to the three genes being tightly linked, here we employ a RNAi strategy to silence them. This approach will enable us to gain further insight into their role in iron homeostasis.Plant Genomics Internships @ M

A case study of a plant-animal relationship: Cola lizae and lowland gorillas in the Lope Reserve, Gabon

The fruits of Cola lizae, an endemic tree with a limited geographical distribution, have been a major food source for lowland gorillas in the Lope Reserve during part of each year over a six-year period. Faecal analysis indicated that 11,000- 18,000 Cola seeds km-2 were deposited by gorillas during the 4- month season in 1989. Gorillas are the only important dispersers of this species: other primates consume the succulent mesocarp, but do not swallow the large seed; elephants do not eat Cola fruits. Observations of Cola seeds in gorilla faeces showed a very high germination rate and, despite initial high mortality, 18% of seedlings still survived six months after deposition. Survival of seedlings was significantly better in faeces left at nest-sites than in other areas of the forest: 40% of seedlings were viable at nest- sites six months after deposition. This suggests that the open areas of forest, preferred by gorillas as nest-sites, are advantageous to the propagation of this species

Characterization of a putative mutant for iron homeostasis

Abstract only availableLittle is known about the genetics of iron homeostasis in plants. A novel genetic screen was used to identify mutants with alterations in iron homeostasis. Because Ferritin (Fer1) mRNA expression is upregulated by intracellular iron concentration in leaves, this gene can be used to predict intercellular iron concentrations in leaves. To identify mutants that over- or under-accumulate leaf iron, Arabidopsis was transformed with the reporter gene Green Fluorescent Protein (GFP) driven by the Fer1 promoter. Seed from this transgenic plant were mutagenized with EMS. The resulting M2 seed were screened for high or low GFP fluorescence relative to transgenic controls grown on iron-sufficient medium. A putative Over-Accumulator of Fe, pOAF40, was identified that expressed high levels of GFP fluorescence. Our objective was to characterize this mutant for alterations in iron homeostasis. Seed of pOAF40 and the non-mutagenized transgenic control were germinated and plants grown on iron-sufficient medium for 14 days before transferring to iron-sufficient or -deficient media for four days. Fer1 mRNA levels, chlorophyll content, and ferric-chelate reductase activity (an enzyme whose activity increases during iron deficiency) were determined at the point of transfer and again four days after transfer. Fer1 mRNA expression was the same at the time of transfer, but greater relative to transgenic controls regardless of iron concentration 4 days later. The average concentration of chlorophyll in pOAF40 was less than the control regardless of sampling time or iron concentration. pOAF40 exhibited lower reductase activity than control on the day of transfer, however this difference in activity was not detected four days after transfer within iron-sufficient or -deficient treatments. Furthermore, ferric-chelatate reductase activity was greater in iron-deficient than -sufficient media for both mutant and control suggesting normal response to iron-deficiency by pOAF40. Further characterization of this mutant is being performed to determine whether the mutation deregulates ferritin expression or leads to over-accumulation of iron in leaves.MU Monsanto Undergraduate Research Fellowshi

Early changes in pro-inflammatory cytokine levels in neonates with encephalopathy are associated with remote epilepsy.

BackgroundNeonatal seizures are associated with adverse neurologic sequelae including epilepsy in childhood. Here we aim to determine whether levels of cytokines in neonates with brain injury are associated with acute symptomatic seizures or remote epilepsy.MethodsThis is a cohort study of term newborns with encephalopathy at UCSF between 10/1993 and 1/2000 who had dried blood spots. Maternal, perinatal/postnatal, neuroimaging, and epilepsy variables were abstracted by chart review. Logistic regression was used to compare levels of cytokines with acute seizures and the development of epilepsy.ResultsIn a cohort of 26 newborns with neonatal encephalopathy at risk for hypoxic ischemic encephalopathy with blood spots for analysis, diffuse alterations in both pro- and anti-inflammatory cytokine levels were observed between those with (11/28, 39%) and without acute symptomatic seizures. Seventeen of the 26 (63%) patients had >2 years of follow-up and 4/17 (24%) developed epilepsy. Higher levels of pro-inflammatory cytokines IL-6 and TNF-α within the IL-1β pathway were significantly associated with epilepsy.ConclusionsElevations in pro-inflammatory cytokines in the IL-1β pathway were associated with later onset of epilepsy. Larger cohort studies are needed to confirm the predictive value of these circulating biomarkers

Seasonal feeding on bark by gorillas: an unexpected keystone food?

First paragraph: There are a number of reports in the literature of primates feeding on the bark of trees, but bark has only occasionally been considered as a major food to be studied in its own right (e.g., Waser, 1977; Beeson, 1987; Norris, 1988). All the great apes feed on bark at certain times, and clearly have preferences as to which species they choose (e.g., Schaller, 1963; Jones & Sabater Pi. 1971; Casimir, 1975: Nishida, 1976; Goodall, 1977; Rodman, 1977; Sabater Pi, 1977, 1979). Evidence has been presented that bark feeding by chimpanzees (Pan troglodytes) and orangutans (Pongo pygmaeus) is a seasonal phenomenon related to scarcity of preferred fruits (Nishida, 1976; Rodman, 1977), and similar conclusions have been drawn from studies of blue monkeys (Cercopithecus mitis) living near plantations of exotic pines (Beeson, 1987; Maganga & Wright, 1992). Bark feeding is also well known in other mammals where, again, it often occurs seasonally (e.g., elephants, Wing & Buss, 1970; grey squirrels, Kenward & Parish, 1986)

Effects of the dry season on gorilla diet in Gabon

It has been shown by various workers that lowland gorillas, Gorilla g. gorillas, in Gabon eat large quantities of succulent fruits (TUTIN and FERNANDEZ, 1985, WILLIAMSON, 1988,WILLIAMSON et al., 1988). This is now being extended to include analysis of the nutrient content of fruit foods, and to study annual variations in fruit consumption caused by, for example, the major dry season from June to September

Early changes in brain structure correlate with language outcomes in children with neonatal encephalopathy.

Global patterns of brain injury correlate with motor, cognitive, and language outcomes in survivors of neonatal encephalopathy (NE). However, it is still unclear whether local changes in brain structure predict specific deficits. We therefore examined whether differences in brain structure at 6 months of age are associated with neurodevelopmental outcomes in this population. We enrolled 32 children with NE, performed structural brain MR imaging at 6 months, and assessed neurodevelopmental outcomes at 30 months. All subjects underwent T1-weighted imaging at 3 T using a 3D IR-SPGR sequence. Images were normalized in intensity and nonlinearly registered to a template constructed specifically for this population, creating a deformation field map. We then used deformation based morphometry (DBM) to correlate variation in the local volume of gray and white matter with composite scores on the Bayley Scales of Infant and Toddler Development (Bayley-III) at 30 months. Our general linear model included gestational age, sex, birth weight, and treatment with hypothermia as covariates. Regional brain volume was significantly associated with language scores, particularly in perisylvian cortical regions including the left supramarginal gyrus, posterior superior and middle temporal gyri, and right insula, as well as inferior frontoparietal subcortical white matter. We did not find significant correlations between regional brain volume and motor or cognitive scale scores. We conclude that, in children with a history of NE, local changes in the volume of perisylvian gray and white matter at 6 months are correlated with language outcome at 30 months. Quantitative measures of brain volume on early MRI may help identify infants at risk for poor language outcomes

Initial Metabolic Profiles Are Associated with 7-Day Survival among Infants Born at 22-25 Weeks of Gestation.

OBJECTIVE:To evaluate the association between early metabolic profiles combined with infant characteristics and survival past 7 days of age in infants born at 22-25 weeks of gestation. STUDY DESIGN:This nested case-control consisted of 465 singleton live births in California from 2005 to 2011 at 22-25 weeks of gestation. All infants had newborn metabolic screening data available. Data included linked birth certificate and mother and infant hospital discharge records. Mortality was derived from linked death certificates and death discharge information. Each death within 7 days was matched to 4 surviving controls by gestational age and birth weight z score category, leaving 93 cases and 372 controls. The association between explanatory variables and 7-day survival was modeled via stepwise logistic regression. Infant characteristics, 42 metabolites, and 12 metabolite ratios were considered for model inclusion. Model performance was assessed via area under the curve. RESULTS:The final model included 1 characteristic and 11 metabolites. The model demonstrated a strong association between metabolic patterns and infant survival (area under the curve [AUC] 0.885, 95% CI 0.851-0.920). Furthermore, a model with just the selected metabolites performed better (AUC 0.879, 95% CI 0.841-0.916) than a model with multiple clinical characteristics (AUC 0.685, 95% CI 0.627-0.742). CONCLUSIONS:Use of metabolomics significantly strengthens the association with 7-day survival in infants born extremely premature. Physicians may be able to use metabolic profiles at birth to refine mortality risks and inform postnatal counseling for infants born at <26 weeks of gestation

Race/Ethnicity and Geographic Access to Urban Trauma Care

Importance Little is known about the distribution of life-saving trauma resources by racial/ethnic composition in US cities, and if racial/ethnic minority populations disproportionately live in US urban trauma deserts. Objective To examine racial/ethnic differences in geographic access to trauma care in the 3 largest US cities, considering the role of residential segregation and neighborhood poverty. Design, Setting, and Participants A cross-sectional, multiple-methods study evaluated census tract data from the 2015 American Community Survey in Chicago, Illinois; Los Angeles (LA), California; and New York City (NYC), New York (N = 3932). These data were paired to geographic coordinates of all adult level I and II trauma centers within an 8.0-km buffer of each city. Between February and September 2018, small-area analyses were conducted to assess trauma desert status as a function of neighborhood racial/ethnic composition, and geospatial analyses were conducted to examine statistically significant trauma desert hot spots. Main Outcomes and Measures In small-area analyses, a trauma desert was defined as travel distance greater than 8.0 km to the nearest adult level I or level II trauma center. In geospatial analyses, relative trauma deserts were identified using travel distance as a continuous measure. Census tracts were classified into (1) racial/ethnic composition categories, based on patterns of residential segregation, including white majority, black majority, Hispanic/Latino majority, and other or integrated; and (2) poverty categories, including nonpoor and poor. Results Chicago, LA, and NYC contained 798, 1006, and 2128 census tracts, respectively. A large proportion comprised a black majority population in Chicago (35.1%) and NYC (21.4%), compared with LA (2.7%). In primary analyses, black majority census tracts were more likely than white majority census tracts to be located in a trauma desert in Chicago (odds ratio [OR], 8.48; 95% CI, 5.71-12.59) and LA (OR, 5.11; 95% CI, 1.50-17.39). In NYC, racial/ethnic disparities were not significant in unadjusted models, but were significant in models adjusting for poverty and race-poverty interaction effects (adjusted OR, 1.87; 95% CI, 1.27-2.74). In comparison, Hispanic/Latino majority census tracts were less likely to be located in a trauma desert in NYC (OR, 0.03; 95% CI, 0.01-0.11) and LA (OR, 0.30; 95% CI, 0.22-0.40), but slightly more likely in Chicago (OR, 2.38; 95% CI, 1.56-3.64). Conclusions and Relevance In this study, black majority census tracts were the only racial/ethnic group that appeared to be associated with disparities in geographic access to trauma centers