LAP3, a novel plant protein required for pollen development, is essential for proper exine formation

We isolated lap3-1 and lap3-2 mutants in ascreen for pollen that displays abnormal stigma binding.Unlike wild-type pollen, lap3-1 and lap3-2 pollen exine isthinner, weaker, and is missing some connections betweentheir roof-like tectum structures. We describe the mappingand identification of LAP3 as a novel gene that contains arepetitive motif found in b-propeller enzymes. Insertionmutations in LAP3 lead to male sterility. To investigatepossible roles for LAP3 in pollen development, we assayedthe metabolite profile of anther tissues containing developingpollen grains and found that the lap3-2 defect leadsto a broad range of metabolic changes. The largest changeswere seen in levels of a straight-chain hydrocarbon nonacosaneand in naringenin chalcone, an obligate compoundin the flavonoid biosynthesis pathway

Novi lizozim s antifungalnim svojstvima, izoliran iz sjemenki biljke Pithecellobium dulce

A protein of an apparent molecular mass of 14.4 kDa with antifungal activity was isolated from the seeds of Pithecellobium dulce using extraction with 100 mM Tris-HCl buffer (pH=8.0), precipitation with 80 % ammonium sulfate, and bioassay purification via Resource Q anion exchange chromatography and Superdex 200 gel filtration chromatography. The purified protein was putatively identified by tandem mass spectrometry with Mascot database searching, with the partial amino acid sequences showing a high degree of similarity to chicken egg white lysozyme. This putative plant lysozyme expressed antifungal activity with a rather high thermal stability of up to 80 °C for 15 min (at pH=8.0). It exerted an antifungal action towards Macrophomina phaseolina but displayed no antifungal activity against two other isolates, Phymatotrichopsis omnivora and Fusarium avenaceum.Iz sjemenki biljke Pithecellobium dulce ekstrakcijom sa 100 mM Tris puferom (pH=8), zatim taloženjem pomoću 80 %-tnog amonijeva sulfata i pročišćavanjem anionsko-izmjenjivačkom Resource Q i gel-filtracijskom Superdex 200 kromatografijom izoliran je protein relativne molekularne mase od 14,4 kDa, koji ima antifungalna svojstva. Pročišćeni je protein identificiran pomoću tandemske spektrometrije masa, pri čemu je upotrijebljena baza podataka Mascot. Utvrđeno je da djelomična sekvencija aminokiselina ispitivanoga proteina izrazito nalikuje sekvenciji lizozima bjelanjka kokošjeg jajeta. Lizozim iz biljke imao je antifungalna svojstva i bio je stabilan pri pH=8 tijekom 15 minuta na temperaturama čak do 80 °C. Spriječio je rast plijesni Macrophomina phaseolina, ali ne i vrsta Phymtotrichopsis omnivora i Fusarium avenaceum

Biomarker metabolites capturing the metabolite variance present in a rice plant developmental period

BACKGROUND: This study analyzes metabolomic data from a rice tillering (branching) developmental profile to define a set of biomarker metabolites that reliably captures the metabolite variance of this plant developmental event, and which has potential as a basis for rapid comparative screening of metabolite profiles in relation to change in development, environment, or genotype. Changes in metabolism, and in metabolite profile, occur as a part of, and in response to, developmental events. These changes are influenced by the developmental program, as well as external factors impinging on it. Many samples are needed, however, to characterize quantitative aspects of developmental variation. A biomarker metabolite set could benefit screening of quantitative plant developmental variation by providing some of the advantages of both comprehensive metabolomic studies and focused studies of particular metabolites or pathways. RESULTS: An appropriate set of biomarker metabolites to represent the plant developmental period including the initiation and early growth of rice tillering (branching) was obtained by: (1) determining principal components of the comprehensive metabolomic profile, then (2) identifying clusters of metabolites representing variation in loading on the first three principal components, and finally (3) selecting individual metabolites from these clusters that were known to be common among diverse organisms. The resultant set of 21 biomarker metabolites was reliable (P = 0.001) in capturing 83% of the metabolite variation in development. Furthermore, a subset of the biomarker metabolites was successful (P = 0.05) in correctly predicting metabolite change in response to environment as determined in another rice metabolomics study. CONCLUSION: The ability to define a set of biomarker metabolites that reliably captures the metabolite variance of a plant developmental event was established. The biomarker metabolites are all commonly present in diverse organisms, so studies of their quantitative relationships can provide comparative information concerning metabolite profiles in relation to change in plant development, environment, or genotype

Plant neighbor identity influences plant biochemistry and physiology related to defense

<p>Abstract</p> <p>Background</p> <p>Chemical and biological processes dictate an individual organism's ability to recognize and respond to other organisms. A small but growing body of evidence suggests that plants may be capable of recognizing and responding to neighboring plants in a species specific fashion. Here we tested whether or not individuals of the invasive exotic weed, <it>Centaurea maculosa</it>, would modulate their defensive strategy in response to different plant neighbors.</p> <p>Results</p> <p>In the greenhouse, <it>C. maculosa </it>individuals were paired with either conspecific (<it>C. maculosa</it>) or heterospecific (<it>Festuca idahoensis</it>) plant neighbors and elicited with the plant defense signaling molecule methyl jasmonate to mimic insect herbivory. We found that elicited <it>C. maculosa </it>plants grown with conspecific neighbors exhibited increased levels of total phenolics, whereas those grown with heterospecific neighbors allocated more resources towards growth. To further investigate these results in the field, we conducted a metabolomics analysis to explore chemical differences between individuals of <it>C. maculosa </it>growing in naturally occurring conspecific and heterospecific field stands. Similar to the greenhouse results, <it>C. maculosa </it>individuals accumulated higher levels of defense-related secondary metabolites and lower levels of primary metabolites when growing in conspecific versus heterospecific field stands. Leaf herbivory was similar in both stand types; however, a separate field study positively correlated specialist herbivore load with higher densities of <it>C. maculosa </it>conspecifics.</p> <p>Conclusions</p> <p>Our results suggest that an individual <it>C. maculosa </it>plant can change its defensive strategy based on the identity of its plant neighbors. This is likely to have important consequences for individual and community success.</p

Rapid Identification of Hospitalized Patients at High Risk for MRSA Carriage

Patients who are asymptomatic carriers of methicillin-resistant Staphylococcus aureus (MRSA) are major reservoirs for transmission of MRSA to other patients. Medical personnel are usually not aware when these high-risk patients are hospitalized. We developed and tested an enterprise-wide electronic surveillance system to identify patients at high risk for MRSA carriage at hospital admission and during hospitalization. During a two-month study, nasal swabs from 153 high-risk patients were tested for MRSA carriage using polymerase chain reaction (PCR) of which 31 (20.3%) were positive compared to 12 of 293 (4.1%, p < 0.001) low-risk patients. The mean interval from admission to availability of PCR test results was 19.2 hours. Computer alerts for patients at high-risk of MRSA carriage were found to be reliable, timely and offer the potential to replace testing all patients. Previous MRSA colonization was the best predictor but other risk factors were needed to increase the sensitivity of the algorith

Integrated metabolomics identifies CYP72A67 and CYP72A68 oxidases in the biosynthesis of Medicago truncatula oleanate sapogenins

Introduction: Triterpene saponins are important bioactive plant natural products found in many plant families including the Leguminosae. Objectives: We characterize two Medicago truncatula cytochrome P450 enzymes, MtCYP72A67 and MtCYP72A68, involved in saponin biosynthesis including both in vitro and in planta evidence. Methods: UHPLC-(-)ESI-QToF-MS was used to profile saponin accumulation across a collection of 106 M. truncatula ecotypes. The profiling results identified numerous ecotypes with high and low saponin accumulation in root and aerial tissues. Four ecotypes with significant differential saponin content in the root and/or aerial tissues were selected, and correlated gene expression profiling was performed. Results: Correlation analyses between gene expression and saponin accumulation revealed high correlations between saponin content with gene expression of -amyrin synthase, MtCYP716A12, and two cytochromes P450 genes, MtCYP72A67 and MtCYP72A68. In vivo and in vitro biochemical assays using yeast microsomes containing MtCYP72A67 revealed hydroxylase activity for carbon 2 of oleanolic acid and hederagenin. This finding was supported by functional characterization of MtCYP72A67 using RNAi-mediated gene silencing in M. truncatula hairy roots, which revealed a significant reduction of 2-hydroxylated sapogenins. In vivo and in vitro assays with MtCYP72A68 produced in yeast showed multifunctional oxidase activity for carbon 23 of oleanolic acid and hederagenin. These findings were supported by overexpression of MtCYP72A68 in M. truncatula hairy roots, which revealed significant increases of oleanolic acid, 2-hydroxyoleanolic acid, hederagenin and total saponin levels. Conclusions: The cumulative data support that MtCYP72A68 is a multisubstrate, multifunctional oxidase and MtCYP72A67 is a 2-hydroxylase, both of which function during the early steps of triterpene-oleanate sapogenin biosynthesis

Patterns of Metabolite Changes Identified from Large-Scale Gene Perturbations in Arabidopsis Using a Genome-Scale Metabolic Network

Metabolomics enables quantitative evaluation of metabolic changes caused by genetic or environmental perturbations. However, little is known about how perturbing a single gene changes the metabolic system as a whole and which network and functional properties are involved in this response. To answer this question, we investigated the metabolite profiles from 136 mutants with single gene perturbations of functionally diverse Arabidopsis (Arabidopsis thaliana) genes. Fewer than 10 metabolites were changed significantly relative to the wild type in most of the mutants, indicating that the metabolic network was robust to perturbations of single metabolic genes. These changed metabolites were closer to each other in a genome-scale metabolic network than expected by chance, supporting the notion that the genetic perturbations changed the network more locally than globally. Surprisingly, the changed metabolites were close to the perturbed reactions in only 30% of the mutants of the well-characterized genes. To determine the factors that contributed to the distance between the observed metabolic changes and the perturbation site in the network, we examined nine network and functional properties of the perturbed genes. Only the isozyme number affected the distance between the perturbed reactions and changed metabolites. This study revealed patterns of metabolic changes from large-scale gene perturbations and relationships between characteristics of the perturbed genes and metabolic changes

Ultraviolet Difference Spectral Studies on Concanavalin A

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/65204/1/j.1432-1033.1970.tb01116.x.pd