Capitalizing on multi-element interactions through bal-anced nutrition——A pathway to improve nitrogen use efficiency in China,India and North America

A viable option for increasing nitrogen (N) use efficiency and mitigation of negative impacts of N on the environment is to capitalize on multi-element interactions through implementation of nutrient management programs that provide balanced nutrition. Numerous studies have demonstrated the immediate efficacy of this approach in the developing regions like China and India as well as developed countries in North America. Based on 241 site-years of experiments in these countries, the first-year N recovery efficiency (RE) for the conventional or check treatments averaged 21% while the balanced treatments averaged 54% RE, for an average increase of 33% in RE due to balanced nutrition. Effective policies to promote adoption are most likely those that enable site-specific approaches to nutrient management decisions rather than sweeping, nation-wide incentives supporting one nutrient over another. Local farmers, advisers and officials need to be empowered with tools and information to help them define necessary changes in practices to create more balanced nutrient management.     

The air-borne distribution of zoonotic agents from livestock waste spreading and microbiological risk to fresh produce from contaminated irrigation sources

Aims:  To assess the risks of zoonotic agents in dissemination of livestock wastes into the environment by airborne distribution. To subsequently assess the survival time of zoonotic agents, introduced in irrigation water, on the phylloplane of produce.
Methods and Results:  An Escherichia coli marker was introduced into pig slurry which was spread using a rain gun sprayer. Air sampling was undertaken to determine the distance reached by the marker. No recoveries were observed at a distance of 250 m. Borehole water, contaminated with zoonotic agents, was used to irrigate field plots sown with lettuce and spinach. Decline in bacterial numbers on the phylloplane was observed with time. After initial rapid decreases, we were unable to detect any pathogen from the phylloplane, 1 month after contamination.
Conclusions:  These preliminary results suggest that the risks to public health from the aerosolized spread of bacteria during slurry spreading by rain gun are low. Although, zoonotic agents on crop phylloplanes perish quickly, the risks of overhead irrigation of fresh produce 3 weeks before harvest should still be considered.
Significance and Impact of the Study:  These preliminary results improve our understanding on the fate of zoonotic agents in the environment. Spreading liquid livestock wastes by an airborne mechanism may not pose a significant public health risk. Detection of zoonotic agents 3 weeks after contamination of lettuce and spinach means that consideration should be given by the farmers until the time of harvest, when irrigating fresh produce with water that may have been directly or indirectly contaminated by livestock wastes.     

Peripartum Cardiomyopathy Presenting With Ventricular Tachycardia: A Rare Presentation

A 25-year-old previously asymptomatic pregnant woman at 36 weeks'' gestation was noticed to have repetitive monomorphic ventricular tachycardia. A dilated left ventricle with moderately reduced systolic function was found on echocardiographic examination. This is a very rare presentation of peripartum cardiomyopathy (PPCMP) presenting with repetitive monomorphic ventricular tachycardia.     

Heart and Skeletal Muscle Inflammation of Farmed Salmon Is Associated with Infection with a Novel Reovirus

Atlantic salmon (Salmo salar L.) mariculture has been associated with epidemics of infectious diseases that threaten not only local production, but also wild fish coming into close proximity to marine pens and fish escaping from them. Heart and skeletal muscle inflammation (HSMI) is a frequently fatal disease of farmed Atlantic salmon. First recognized in one farm in Norway in 1999[1], HSMI was subsequently implicated in outbreaks in other farms in Norway and the United Kingdom[2]. Although pathology and disease transmission studies indicated an infectious basis, efforts to identify an agent were unsuccessful. Here we provide evidence that HSMI is associated with infection with piscine reovirus (PRV). PRV is a novel reovirus identified by unbiased high throughput DNA sequencing and a bioinformatics program focused on nucleotide frequency as well as sequence alignment and motif analyses. Formal implication of PRV in HSMI will require isolation in cell culture and fulfillment of Koch''s postulates, or prevention or modification of disease through use of specific drugs or vaccines. Nonetheless, as our data indicate that a causal relationship is plausible, measures must be taken to control PRV not only because it threatens domestic salmon production but also due to the potential for transmission to wild salmon populations.     

Stereoselective synthesis of a conformationally defined cyclohexyl carnitine analogue that binds CPT-1 with high affinity.

Carnitine (1, 3-hydroxy-4-trimethylammoniobutyrate) is important in mammalian tissue as a carrier of acyl groups. In order to explore the binding requirements of the carnitine acyltransferases for carnitine, we designed conformationally defined cyclohexyl carnitine analogues. These diastereomers contain the required gauche conformation between the trimethylammonium and hydroxy groups but vary the conformation between the hydroxy and carboxylic acid groups. Here we describe the synthesis and biological activity of the all-trans diastereomer (2), which was prepared by the ring opening of trans-methyl 2,3-epoxycylohexanecarboxylate with NaN3. Racemic 2 was a competitive inhibitor of neonatal rat cardiac myocyte CPT-1 (K(i) 0.5 mM for racemic 2; K(m) 0.2 mM for L-carnitine) and a noncompetitive inhibitor of neonatal rat cardiac myocyte CPT-2 (K(i) 0.67 mM). These results suggest that 2 represents the bound conformation of carnitine for CPT-1.     

Cofilin-linked changes in actin filament flexibility promote severing

The actin regulatory protein, cofilin, increases the bending and twisting elasticity of actin filaments and severs them. It has been proposed that filaments partially decorated with cofilin accumulate stress from thermally driven shape fluctuations at bare (stiff) and decorated (compliant) boundaries, thereby promoting severing. This mechanics-based severing model predicts that changes in actin filament compliance due to cofilin binding affect severing activity. Here, we test this prediction by evaluating how the severing activities of vertebrate and yeast cofilactin scale with the flexural rigidities determined from analysis of shape fluctuations. Yeast actin filaments are more compliant in bending than vertebrate actin filaments. Severing activities of cofilactin isoforms correlate with changes in filament flexibility. Vertebrate cofilin binds but does not increase the yeast actin filament flexibility, and does not sever them. Imaging of filament thermal fluctuations reveals that severing events are associated with local bending and fragmentation when deformations attain a critical angle. The critical severing angle at boundaries between bare and cofilin-decorated segments is smaller than in bare or fully decorated filaments. These measurements support a cofilin-severing mechanism in which mechanical asymmetry promotes local stress accumulation and fragmentation at boundaries of bare and cofilin-decorated segments, analogous to failure of some nonprotein materials.     

Embryonic and adult isoforms of XLAP2 form microdomains associated with chromatin and the nuclear envelope

Laminin-associated polypeptide 2 (LAP2) proteins are alternatively spliced products of a single gene; they belong to the LEM domain family and, in mammals, locate to the nuclear envelope (NE) and nuclear lamina. Isoforms lacking the transmembrane domain also locate to the nucleoplasm. We used new specific antibodies against the N-terminal domain of Xenopus LAP2 to perform immunoprecipitation, identification and localization studies during Xenopus development. By immunoprecipitation and mass spectrometry (LC/MS/MS), we identified the embryonic isoform XLAP2??, which was downregulated during development similarly to XLAP2??. Embryonic isoforms XLAP2?? and XLAP2?? were located in close association with chromatin up to the blastula stage. Later in development, both embryonic isoforms and the adult isoform XLAP2?? were localized in a similar way at the NE. All isoforms colocalized with lamin B2/B3 during development, whereas XLAP2?? was colocalized with lamin B2 and apparently with the F/G repeat nucleoporins throughout the cell cycle in adult tissues and culture cells. XLAP2?? was localized in clusters on chromatin, both at the NE and inside the nucleus. Embryonic isoforms were also localized in clusters at the NE of oocytes. Our results suggest that XLAP2 isoforms participate in the maintenance and anchoring of chromatin domains to the NE and in the formation of lamin B microdomains.     

High-resolution electron microscope and computed images of human tooth enamel crystals

The structure of human enamel crystallites has been studied at a near atomic level by high-resolution electron microscopy. Electron micrographs have been obtained from crystallites present in human enamel with a structure resolution of 0.2 nm in the [0001], [1210], [1213], [1100] and [4510] zone axes directions. In most cases it was possible to match the experimental images with images calculated using the atomic positions of mineral hydroxyapatite. However, in some cases a discrepancy between calculated and experimental image detail was observed in the c direction of the [1210] and the [1100] images. This shows: (i) a structural heterogeneity of the crystals, and (ii) a loss of hexagonal symmetry of the structure. The resolution required to distinguish individual atomic sites in the different zones has been determined, and this will provide a useful basis for future work. As the determination of the "real structure" of biological crystals is of prime importance for the study of calcification mechanisms (crystal growth), biological properties and destructive phenomena of calcified tissues (i.e., dental caries and bone resorption).