Endophyte Status in Summer-Dormant Tall Fescue in the Southern Great Plains of USA

Non-toxic fungal endophytes provide persistence-related benefits to summer-active, continental-type tall fescue (Festuca arundinacea Schreb.), as well as reduced animal toxicosis compared to toxic endophytes. However, the benefits of fungal endophytes to summer-dormant, Mediterranean-type tall fescue persistence or production are unclear. Summer-dormant tall fescue has potential to replace traditional, annual small grain graze-out systems in the Southern Great Plains region of the USA. This region is characterized by severe water deficits accompanied by extreme heat in summer, and by relatively mild, rainy winters (Malinowski et al. 2009). Summer-active tall fescues are better suited to high rainfall areas (\u3e 900 mm annual average rainfall (AAR)) east of the 97° longitudinal meridian, while summer-dormant tall fescues are best adapted to lower rainfall areas (600 to 900 mm AAR) between the 97° and 99° longitudinal meridian (Butler et al. 2011). The objective of this field study was to determine the effects of the ‘novel’ endophyte strain AR542 on persistence of summer-dormant tall fescue ‘Flecha’ in the Southern Great Plains of the USA. Two field experiments were conducted to evaluate the effect of the novel endophyte AR542 on the survival of Flecha

Electrochemical and ligand binding studies of a de novo heme protein

Abstract Heme proteins can perform a variety of electrochemical functions. While natural heme proteins carry out particular functions selected by biological evolution, artificial heme proteins, in principle, can be tailored to suit specified technological applications. Here we describe initial characterization of the electrochemical properties of a de novo heme protein, S824C. Protein S824C is a four-helix bundle derived from a library of sequences that was designed by binary patterning of polar and nonpolar amino acids. Protein S824C was immobilized on a gold electrode and the formal potential of heme-protein complex was studied as a function of pH and ionic strength. The binding of exogenous N-donor ligands to heme/S824C was monitored by measuring shifts in the potential that occurred upon addition of various concentrations of imidazole or pyridine derivatives. The response of heme/S824C to these ligands was then compared to the response of isolated heme (without protein) to the same ligands. The observed shifts in potential depended on both the concentration and the structure of the added ligand. Small changes in structure of the ligand (e.g. pyridine versus 2-amino pyridine) produced significant shifts in the potential of the heme-protein. The observed shifts correlate to the differential binding of the N-donor molecules to the oxidized and reduced states of the heme. Further, it was observed that the electrochemical response of the buried heme in heme/S824C differed significantly from that of isolated heme. These studies demonstrate that the structure of the de novo protein modulates the binding of N-donor ligands to heme

Vortices in Saturn's Northern Hemisphere (2008-2015) observed by Cassini ISS

We use observations from the Imaging Science Subsystem on Cassini to create maps of Saturn's Northern Hemisphere (NH) from 2008 to 2015, a time period including a seasonal transition (i.e., spring equinox in 2009) and the 2010 giant storm. The processed maps are used to investigate vortices in the NH during the period of 2008–2015. All recorded vortices have diameters (east‐west) smaller than 6000 km except for the largest vortex that developed from the 2010 giant storm. The largest vortex decreased its diameter from ~11,000 km in 2011 to ~5000 km in 2015, and its average diameter is ~6500 km during the period of 2011–2015. The largest vortex lasts at least 4 years, which is much longer than the lifetimes of most vortices (less than 1 year). The largest vortex drifts to north, which can be explained by the beta drift effect. The number of vortices displays varying behaviors in the meridional direction, in which the 2010 giant storm significantly affects the generation and development of vortices in the middle latitudes (25–45°N). In the higher latitudes (45–90°N), the number of vortices also displays strong temporal variations. The solar flux and the internal heat do not directly contribute to the vortex activities, leaving the temporal variations of vortices in the higher latitudes (45–90°N) unexplained

Vortices in Saturn's Northern Hemisphere (2008-2015) observed by Cassini ISS

We use observations from the Imaging Science Subsystem on Cassini to create maps of Saturn's Northern Hemisphere (NH) from 2008 to 2015, a time period including a seasonal transition (i.e., spring equinox in 2009) and the 2010 giant storm. The processed maps are used to investigate vortices in the NH during the period of 2008–2015. All recorded vortices have diameters (east‐west) smaller than 6000 km except for the largest vortex that developed from the 2010 giant storm. The largest vortex decreased its diameter from ~11,000 km in 2011 to ~5000 km in 2015, and its average diameter is ~6500 km during the period of 2011–2015. The largest vortex lasts at least 4 years, which is much longer than the lifetimes of most vortices (less than 1 year). The largest vortex drifts to north, which can be explained by the beta drift effect. The number of vortices displays varying behaviors in the meridional direction, in which the 2010 giant storm significantly affects the generation and development of vortices in the middle latitudes (25–45°N). In the higher latitudes (45–90°N), the number of vortices also displays strong temporal variations. The solar flux and the internal heat do not directly contribute to the vortex activities, leaving the temporal variations of vortices in the higher latitudes (45–90°N) unexplained

EC02-153-A Revised Jan 2002 Selecting Alfalfa Varieties for Nebraska

Extension Circular 02-153-A: Selecting Alfalfa Varieties for Nebraska. This document provides information about the various types of alfalfa and when to plant them

EC03-153 Selecting Alfalfa Varieties for Nebraska

The most important variety decision on many farms and ranches is the selection of alfalfa. The choice of alfalfa variety affects production for three to ten or more years, whereas varieties of annual crops can be changed annually. Yield potential, pest resistance, and seed price should be considered when selecting alfalfa varieties in Nebraska

EC02-153 Selecting Alfalfa Varieties for Nebraska 2002

Yield potential, pest resistance and seed price should be considered when selecting alfalfa varieties in Nebraska. The most important variety decision on many farms and ranches is the selection of alfalfa. The choice of alfalfa variety affects production for three to 10 or more years, whereas varieties of annual crops can be changed every year. Many alfalfa varieties are available from private and public plant breeders. Over the years, yield trials conducted at widely distributed Nebraska locations have tested most varieties sold in the state

Reactivity of O 2

Enzymatic conversion of polysaccharides into lower-molecular-weight, soluble oligosaccharides is dependent on the action of hydrolytic and oxidative enzymes. Polysaccharide monooxygenases (PMOs) use an oxidative mechanism to break the glycosidic bond of polymeric carbohydrates, thereby disrupting the crystalline packing and creating new chain ends for hydrolases to depolymerize and degrade recalcitrant polysaccharides. PMOs contain a mononuclear Cu(II) center that is directly involved in C-H bond hydroxylation. Molecular oxygen was the accepted cosubstrate utilized by this family of enzymes until a recent report indicated reactivity was dependent on H2O2 Reported here is a detailed analysis of PMO reactivity with H2O2 and O2, in conjunction with high-resolution MS measurements. The cosubstrate utilized by the enzyme is dependent on the assay conditions. PMOs will directly reduce O2 in the coupled hydroxylation of substrate (monooxygenase activity) and will also utilize H2O2 (peroxygenase activity) produced from the uncoupled reduction of O2 Both cosubstrates require Cu reduction to Cu(I), but the reaction with H2O2 leads to nonspecific oxidation of the polysaccharide that is consistent with the generation of a hydroxyl radical-based mechanism in Fenton-like chemistry, while the O2 reaction leads to regioselective substrate oxidation using an enzyme-bound Cu/O2 reactive intermediate. Moreover, H2O2 does not influence the ability of secretome from Neurospora crassa to degrade Avicel, providing evidence that molecular oxygen is a physiologically relevant cosubstrate for PMOs

Characterization of Epichloë coenophiala within the U.S.: are all tall fescue endophytes created equal?

Tall fescue (Lolium arundinaceum) is a valuable and broadly adapted forage grass that occupies approximately 14 million hectares across the United States. A native to Europe, tall fescue was likely introduced into the U.S. around the late 1800’s. Much of the success of tall fescue can be attributed to Epichloë coenophiala (formerly Neotyphodium coenophialum) a seed borne symbiont that aids in host persistence. Epichloë species are capable of producing a range of alkaloids (ergot alkaloids, indole-diterpenes, lolines and peramine) that provide protection to the plant host from herbivory. Unfortunately, most tall fescue within the U.S., commonly referred to as KY31, harbors the endophyte E. coenophiala that causes toxicity to grazing livestock due to the production of ergot alkaloids. Molecular analyses of tall fescue endophytes have identified four independent associations, representing tall fescue with E. coenophiala, Epichloë sp. FaTG-2, Epichloë sp. FaTG-3 or Epichloë sp. FaTG-4. Each of these Epichloë species can be further distinguished based on genetic variation that equates to differences in the alkaloid gene loci. Tall fescue samples were evaluated using markers to SSR and alkaloid biosynthesis genes to determine endophyte strain variation present within continental U.S. Samples represented seed and tillers from the Suiter farm (Menifee County, KY), which is considered the originating site of KY31, as well as plant samples collected from 14 states, breeder’s seed and plant introduction lines (National Plant Germplasm System, NPGS). This study revealed two prominent E. coenophiala genotypes based on presence of alkaloid biosynthesis genes and SSR markers and provides insight into endophyte variation within continental U.S. across historical and current tall fescue samples