Fluorogenic and bioorthogonal modification of rna using photoclick chemistry

A bromoaryltetrazole-modified uridine was synthesized as a new RNA building block for bioorthogonal, light-activated and postsynthetic modification with commercially available fluorescent dyes. It allows “photoclick”-type modifications by irradiation with light (300 nm LED) at internal and terminal positions of presynthesized RNA with maleimide-conjugated fluorophores in good yields. The reaction was evidenced for three different dyes. During irradiation, the emission increases due to the formation of an intrinsically fluorescent pyrazoline moiety as photoclick product. The fluorogenecity of the photoclick reaction was significantly enhanced by energy transfer between the pyrazoline as the reaction product (poor emitter) and the photoclicked dye as the strong emitter. The RNA-dye conjugates show remarkable fluorescent properties, in particular an up to 9.4 fold increase of fluorescence, which are important for chemical biology and fluorescent imaging of RNA in cells

Bean Leaf Beetle Biology and Management

In the past few years, Iowa bean leaf beetle densities have reached record levels. Bean leaf beetles are present in Iowa soybean fields every year, but recently many producers have had to apply insecticides to manage this pest

Beetles transmit a new soybean virus

In 1999, soybean producers from around the state reported problems with soybean green stem and mottled or discolored soybean seed. Many of these reports of poor soybean quality are suspected to be caused by the spread of a new soybean disease in Iowa, bean pod mottle virus. Bean pod mottle virus was identified in Iowa as early as 1968, but it hasn\u27t been widespread or implicated in causing significant yield losses. Last year bean pod mottle virus was confirmed in soybeans in several central and western Iowa counties (Dallas, Ida, Marshall, Polk, Story, and Woodbury)

Early-season bean leaf beetles rarely equal economic damage

Don\u27t be surprised to see more bean leaf beetles this season than in typical years. Last year, a large bean leaf beetle population was present in most of Iowa. The mild winter apparently allowed at least 50 percent winter survival of overwintering beetles. This is in contrast to the 25 percent survival recorded last year. The bean leaf beetle completes two generations each year in Iowa. Adults overwinter and emerge in late April or May depending on the temperature. Adults have been reported in 1998 since the third week of April

Effect of Bean Leaf Beetle Management on Soybean Yield and on Incidence of Bean Pod Mottle Virus in Eastern Iowa

The bean leaf beetle (BLB) is a long-time pest of soybeans and other beans; but until 2000, it seldom reached levels that warranted treatment on a large scale. Recently however, the BLB also has been identified as the transmission source of a disease called bean pod mottle virus (BPMV), which can cause yield reduction of benas as well as discoloring of soybeans that results in dockage at market. During the winter of 2000–2001, high overwintering BLB populations due to an extensive insulating snow cover suggested that BLB populations would be quite high during the 2001 growing season. While research by Dr. Larry Pedigo, professor of entomology, and others has been done to establish developmental stage thresholds for BLB management in soybeans, the addition of BPMV to the overall equation indicated the need for additional research to determine timing, effectiveness, and economics of spraying to prevent the introduction of BPMV into the plants

New Thresholds and Strategies for Management of Bean Leaf Beetles in Iowa Soybean

The bean leaf beetle is an annual pest of soybean in midwestern states. Adult beetles feed on any aboveground plant part and are especially fond of soybean pods late in the growing season. Larvae, which are similar in appearance to com rootworm larvae, feed below the soil surface on soybean nodules, but their impact on yield or plant health is not known. In addition to the physical injury that bean leaf beetle adults cause to soybean plants, this insect also transmits bean pod mottle virus-a potentially yield-robbing plant disease that makes proper management of this insect even more critical. This report focuses on a new concept for managing second-generation bean leaf beetle adults, the performance of insecticides in controlling this pest, and the problems related to bean pod mottle virus and transmission by adult beetles

Fast and Efficient Postsynthetic DNA Labeling in Cells by Means of Strain-Promoted Sydnone-Alkyne Cycloadditions

Fast and efficient: DNA strands, modified with the novel bioorthogonal reporters sydnones, undergo fast and efficient labeling with cyclooctynes and have the potential to become essential tools for imaging DNA and possibly RNA in cells. Sydnones are highly stable mesoionic 1,3-dipoles that react with cyclooctynes through strain-promoted sydnone-alkyne cycloaddition (SPSAC). Although sydnones have been shown to be valuable bioorthogonal chemical reporters for the labeling of proteins and complex glycans, nucleic acids have not yet been tagged by SPSAC. Evaluation of SPSAC kinetics with model substrates showed fast reactions with cyclooctyne probes (up to k=0.59 M$^{-1}$ s$^{-1}$), and two different sydnones were effectively incorporated into both 2’-deoxyuridines at position 5, and 7-deaza-2’-deoxyadenosines at position 7. These modified nucleosides were synthetically incorporated into single-stranded DNAs, which were successfully postsynthetically labeled with cyclooctyne probes both in vitro and in cells. These results show that sydnones are versatile bioorthogonal tags and have the premise to become essential tools for tracking DNA and potentially RNA in living cells

Pion-nucleus optical potential valid up to the DELTA-resonance region

We present in this article an optical potential for the $\pi$-nucleus interaction that can be used in various studies involving $\pi$-nucleus channels. Based on earlier treatments of the low energy $\pi$-nucleus optical potential, we have derived a potential expression applicable from threshold up to the $\Delta$-resonance region. We extracted the impulse approximation form for this potential from the $\pi-N$ scattering amplitude and then added to it kinematical and physical corrections. The kinematic corrections arise from transforming the impulse approximation expression from the $\pi-N$ center of mass frame to the $\pi$-nucleus center of mass frame, while the physical corrections arise mostly from the many-body nature of the $\pi$-nucleus interaction. By taking advantage of the experimental progress in our knowledge of the $\pi-N$ process, we have updated earlier treatments with parameters calculated from state-of-the-art experimental measurements.Comment: 23 pages, 12 figures. Accepted for publication in Physical Review

Management of Bean Leaf Beetles and Bean Pod Mottle Virus: A Summary of Current and Future Research

In 2002, the bean leaf beetle, Cerotoma trifurcata (Forster), population reached the highest level recorded in 14 years (Fig. 1). The bean leaf beetle is now considered the most frequent insect pest of Iowa soybean, and concern over this pest is greater because it transmits a soybean virus, Bean pod mottle virus (BPMV). Bean leaf beetle management recently has become more complicated because of this insect\u27s association with BPMV, therefore, it is important to understand the life cycle of the beetle and its relation to BPMV before management decisions are made