Michael Wisniewski

Bio: Michael Wisniewski is an academic researcher from Virginia Tech. The author has contributed to research in topics: Postharvest & Penicillium expansum. The author has an hindex of 64, co-authored 264 publications receiving 13201 citations. Previous affiliations of Michael Wisniewski include United States Department of Agriculture & Stockholm University.

Rapid Evaluation of Plant Extracts and Essential Oils for Antifungal Activity Against Botrytis cinerea

Abstract: A rapid assay to determine antifungal activity in plant extracts and essential oils is described. Wells in microtiter plates were loaded with Botrytis cinerea spores and plant extracts or essential oils. Subsequent changes in optical density following spore germination in the wells was measured after 24 h using an automatic microtiter plate reader driven by a software program developed for this purpose. Extracts from 345 plants and 49 essential oils were evaluated for their antifungal activity against B. cinerea. Among 345 plant extracts analyzed, 13 showed high levels of antifungal activity, with species of Allium and Capsicum predominating. Among the 49 essential oils tested, palmarosa (Cymbopogon martini), red thyme (Thymus zygis), cinnamon leaf (Cinnamomum zeylanicum), and clove buds (Eugenia caryophyllata) demonstrated the most antifungal activity against B. cinerea. The most frequently occurring constituents in essential oils showing high antifungal activity were: D-limonene, cineole; β-myrcene; α-pinene, β-pinene; and camphor.

SPAdes, a new genome assembly algorithm and its applications to single-cell sequencing ( 7th Annual SFAF Meeting, 2012)

Abstract: The lion's share of bacteria in various environments cannot be cloned in the laboratory and thus cannot be sequenced using existing technologies. A major goal of single-cell genomics is to complement gene-centric metagenomic data with whole-genome assemblies of uncultivated organisms. Assembly of single-cell data is challenging because of highly non-uniform read coverage as well as elevated levels of sequencing errors and chimeric reads. We describe SPAdes, a new assembler for both single-cell and standard (multicell) assembly, and demonstrate that it improves on the recently released E+V-SC assembler (specialized for single-cell data) and on popular assemblers Velvet and SoapDeNovo (for multicell data). SPAdes generates single-cell assemblies, providing information about genomes of uncultivatable bacteria that vastly exceeds what may be obtained via traditional metagenomics studies. SPAdes is available online ( http://bioinf.spbau.ru/spades ). It is distributed as open source software.

Reactive Oxygen Species, Oxidative Damage, and Antioxidative Defense Mechanism in Plants under Stressful Conditions

Abstract: Reactive oxygen species (ROS) are produced as a normal product of plant cellular metabolism. Various environmental stresses lead to excessive production of ROS causing progressive oxidative damage and ultimately cell death. Despite their destructive activity, they are well-described second messengers in a variety of cellular processes, including conferment of tolerance to various environmental stresses. Whether ROS would serve as signaling molecules or could cause oxidative damage to the tissues depends on the delicate equilibrium between ROS production, and their scavenging. Efficient scavenging of ROS produced during various environmental stresses requires the action of several nonenzymatic as well as enzymatic antioxidants present in the tissues. In this paper, we describe the generation, sites of production and role of ROS as messenger molecules as well as inducers of oxidative damage. Further, the antioxidative defense mechanisms operating in the cells for scavenging of ROS overproduced under various stressful conditions of the environment have been discussed in detail.

Significance of Inducible Defense-related Proteins in Infected Plants

Abstract: Inducible defense-related proteins have been described in many plant species upon infection with oomycetes, fungi, bacteria, or viruses, or insect attack. Several types of proteins are common and have been classified into 17 families of pathogenesis-related proteins (PRs). Others have so far been found to occur more specifically in some plant species. Most PRs and related proteins are induced through the action of the signaling compounds salicylic acid, jasmonic acid, or ethylene, and possess antimicrobial activities in vitro through hydrolytic activities on cell walls, contact toxicity, and perhaps an involvement in defense signaling. However, when expressed in transgenic plants, they reduce only a limited number of diseases, depending on the nature of the protein, plant species, and pathogen involved. As exemplified by the PR-1 proteins in Arabidopsis and rice, many homologous proteins belonging to the same family are regulated developmentally and may serve different functions in specific organs or tissues. Several defense-related proteins are induced during senescence, wounding or cold stress, and some possess antifreeze activity. Many defense-related proteins are present constitutively in floral tissues and a substantial number of PR-like proteins in pollen, fruits, and vegetables can provoke allergy in humans. The evolutionary conservation of similar defense-related proteins in monocots and dicots, but also their divergent occurrence in other conditions, suggest that these proteins serve essential functions in plant life, whether in defense or not.