The structure of latherin, a surfactant allergen protein from horse sweat and saliva

Latherin is a highly surface-active allergen protein found in the sweat and saliva of horses and other equids. Its surfactant activity is intrinsic to the protein in its native form, and is manifest without associated lipids or glycosylation. Latherin probably functions as a wetting agent in evaporative cooling in horses, but it may also assist in mastication of fibrous food as well as inhibition of microbial biofilms. It is a member of the PLUNC family of proteins abundant in the oral cavity and saliva of mammals, one of which has also been shown to be a surfactant and capable of disrupting microbial biofilms. How these proteins work as surfactants while remaining soluble and cell membrane-compatible is not known. Nor have their structures previously been reported. We have used protein nuclear magnetic resonance spectroscopy to determine the conformation and dynamics of latherin in aqueous solution. The protein is a monomer in solution with a slightly curved cylindrical structure exhibiting a ‘super-roll’ motif comprising a four-stranded anti-parallel β-sheet and two opposing α-helices which twist along the long axis of the cylinder. One end of the molecule has prominent, flexible loops that contain a number of apolar amino acid side chains. This, together with previous biophysical observations, leads us to a plausible mechanism for surfactant activity in which the molecule is first localized to the non-polar interface via these loops, and then unfolds and flattens to expose its hydrophobic interior to the air or non-polar surface. Intrinsically surface-active proteins are relatively rare in nature, and this is the first structure of such a protein from mammals to be reported. Both its conformation and proposed method of action are different from other, non-mammalian surfactant proteins investigated so far

Ocular manifestations of Hansen's disease

A detailed ophthalmic evaluation including slitlamp biomicroscopy, measurement of corneal sensitivity using Cochet and Bonnet aesthesiometer, Schirmer's test and Goldmann applanation tonometry was carried out in 89 patients of Hansen's disease attending the leprosy clinic with or without ocular symptoms and willing to undergo eye evaluation. Thirty-one patients had lepromatous leprosy (8 with erythema nodosum leprosum), 56 patients had borderline disease (13 with reversal reactions) and 2 had tuberculoid disease. In addition to the well documented changes of lagophthalmos (6.7%), uveitis (7.3%) and cataracts (19%), we noted prominent corneal nerves in 133 eyes (74.7%), beaded corneal nerves in 19 eyes (10.7%), corneal scarring in 10 eyes (5.6%), corneal hypoaesthesia in 51 eyes (28%) and dry eye in 18 eyes (13%). Beaded corneal nerves and/or stomal infiltrates occurred mainly in the lepromatous group (75%). Ocular hypotony (IOP less than 12 mm Hg) was not seen more frequently in Hansen's as compared to age and sex matched controls with refractive errors or cataracts (33.7%, vs. 37.8%,p=0.33). Our study highlights the primary corneal involvement with corneal neuropathy as the predominant feature of Hansen's disease

Anti-Hyperon Enhancement through Baryon Junction Loops

The baryon junction exchange mechanism recently proposed to explain valence baryon number transport in nuclear collisions is extended to study midrapidity anti-hyperon production. Baryon junction-anti-junction (J anti-J) loops are shown to enhance anti-Lambda, anti-Xi, anti-Omega yields as well as lead to long range rapidity correlations. Results are compared to recent WA97 Pb + Pb -> Y + anti-Y + X data.Comment: 10 pages, 4 figure

Molecular Electroporation and the Transduction of Oligoarginines

Certain short polycations, such as TAT and polyarginine, rapidly pass through the plasma membranes of mammalian cells by an unknown mechanism called transduction as well as by endocytosis and macropinocytosis. These cell-penetrating peptides (CPPs) promise to be medically useful when fused to biologically active peptides. I offer a simple model in which one or more CPPs and the phosphatidylserines of the inner leaflet form a kind of capacitor with a voltage in excess of 180 mV, high enough to create a molecular electropore. The model is consistent with an empirical upper limit on the cargo peptide of 40--60 amino acids and with experimental data on how the transduction of a polyarginine-fluorophore into mouse C2C12 myoblasts depends on the number of arginines in the CPP and on the CPP concentration. The model makes three testable predictions.Comment: 15 pages, 5 figure

Nitrogen Rate and Landscape Impacts on Life Cycle Energy Use and Emissions from Switchgrass-derived Ethanol

Switchgrass-derived ethanol has been proposed as an alternative to fossil fuels to improve sustainability of the US energy sector. In this study, life cycle analysis (LCA) was used to estimate the environmental benefits of this fuel. To better define the LCA environmental impacts associated with fertilization rates and farm-landscape topography, results from a controlled experiment were analyzed. Data from switchgrass plots planted in 2008, consistently managed with three nitrogen rates (0, 56, and 112 kg N ha−1), two landscape positions (shoulder and footslope), and harvested annually (starting in 2009, the year after planting) through 2014 were used as input into the Greenhouse gases, Regulated Emissions and Energy use in transportation (GREET) model. Simulations determined nitrogen (N) rate and landscape impacts on the life cycle energy and emissions from switchgrass ethanol used in a passenger car as ethanol–gasoline blends (10% ethanol:E10, 85% ethanol:E85s). Results indicated that E85s may lead to lower fossil fuels use (58 to 77%), greenhouse gas (GHG) emissions (33 to 82%), and particulate matter (PM2.5) emissions (15 to 54%) in comparison with gasoline. However, volatile organic compounds (VOCs) and other criteria pollutants such as nitrogen oxides (NOx), particulate matter (PM10), and sulfur dioxides (SOx) were higher for E85s than those from gasoline. Nitrogen rate above 56 kg N ha−1 yielded no increased biomass production benefits; but did increase (up to twofold) GHG, VOCs, and criteria pollutants. Lower blend (E10) results were closely similar to those from gasoline. The landscape topography also influenced life cycle impacts. Biomass grown at the footslope of fertilized plots led to higher switchgrass biomass yield, lower GHG, VOCs, and criteria pollutants in comparison with those at the shoulder position. Results also showed that replacing switchgrass before maximum stand life (10–20 years.) can further reduce the energy and emissions reduction benefits

Sod Suppression Techniques for Legume Interseeding

Sod suppression is necessary for successful establishment of legumes interseeded into existing pasture; however such techniques vary in their effectiveness, cost, and management. Sod suppression experiments for legume interseeding into cool-season pasture were conducted at South Dakota State University’s Cow-Calf Unit located near Brookings, SD in 2003 to 2005. We evaluated (i) spring burn, (ii) field cultivator or disk, (iii) herbicide, (iv) heavy fall and spring graze, and (v) a control with no sod suppression. Legume species were alfalfa, birdsfoot trefoil, and kura clover. Sod suppression techniques enhanced the success of legume interseeding. In this study, the grazing equaled or was better than herbicide as a sod suppression technique. Field cultivating, disking or spring burning did not enhance the success of legume establishment. Alfalfa had a greater establishment in the drier year of 2003. Birdsfoot trefoil had greater establishment in the wetter year of 2004. Kura clover was not successful in establishment. Costs of sod suppression techniques varied from $0 per acre (grazing) to$13.30 per acre (herbicide). Management of sod suppression techniques is important to provide a long enough window for legumes to establish with minimal competition from existing grass. Managers can choose the sod suppression technique and legume that fits their resources, skills, and comfort level to achieve successful legume interseeding

Stability ordering of cycle expansions

We propose that cycle expansions be ordered with respect to stability rather than orbit length for many chaotic systems, particularly those exhibiting crises. This is illustrated with the strong field Lorentz gas, where we obtain significant improvements over traditional approaches.Comment: Revtex, 5 incorporated figures, total size 200