What does it take to be a plant pathogen: genomic insights from <Emphasis Type="Italic">Streptomyces</Emphasis> species

Plant pathogenicity is rare in the genus Streptomyces, with only a dozen or so species possessing this trait out of the more than 900 species described. Nevertheless, such species have had a significant impact on agricultural economies throughout the world due to their ability to cause important crop diseases such as potato common scab, which is characterized by lesions that form on the potato tuber surface. All pathogenic species that cause common scab produce a family of phytotoxins called the thaxtomins, which function as cellulose synthesis inhibitors. In addition, the nec1 and tomA genes are conserved in several pathogenic streptomycetes, the former of which is predicted to function in the suppression of plant defense responses. Streptomyces scabies is the oldest plant pathogen described and has a world-wide distribution, whereas species such as S. turgidiscabies and S. acidiscabies are believed to be newly emergent pathogens found in more limited geographical locations. The genome sequence of S. scabies 87-22 was recently completed, and comparative genomic analyses with other sequenced microbial pathogens have revealed the presence of additional genes that may play a role in plant pathogenicity, an idea that is supported by functional analysis of one such putative virulence locus. In addition, the availability of multiple genome sequences for both pathogenic and nonpathogenic streptomycetes has provided an opportunity for comparative genomic analyses to identify the Streptomyces pathogenome. Such genomic analyses will contribute to the fundamental understanding of the mechanisms and evolution of plant pathogenicity and plant-microbe biology within this genus.     

The effects of cosolutes on protein dynamics: the reversal of denaturant-induced protein fluctuations by trimethylamine N-oxide

The protein stabilizing effects of the small molecule osmolyte, trimethylamine N-oxide, against chemical denaturant was investigated by NMR spin-relaxation measurements and model-free analysis. In the presence of 0.7 M guanidine hydrochloride increased picosecond-nanosecond dynamics are observed in the protein ribonuclease A. These increased fluctuations occur throughout the protein, but the most significant increases in flexibility occur at positions believed to be the first to unfold. Addition of 0.35 M trimethylamine N-oxide to this destabilized form of ribonuclease results in significant rigidification of the protein backbone as assessed by (1)H-(15)N order parameters. Statistically, these order parameters are the same as those measured in native ribonuclease indicating that TMAO reduces the amplitude of backbone fluctuations in a destabilized protein. These data suggest that TMAO restricts the bond vector motions on the protein energy landscape to resemble those motions that occur in the native protein and points to a relation between stability and dynamics in this enzyme.     

Analysis of acute explosive training modalities to improve lower-body power in baseball players

Complex training is the simultaneous combination of heavy resistance training and plyometrics. The objective of this study was to test the effects of complex training vs. heavy resistance or plyometric interventions alone on various power-specific performance measures. Forty-five male division II junior college baseball players participated in 3 separate 4-week resistance training interventions. Subjects were randomly assigned to one of three groups. In a counterbalanced rotation design, each group participated in complex, heavy resistance, and plyometric training interventions. Each individual was tested in 20-yd (SP20), 40-yd (SP40), 60-yd (SP60), vertical jump, standing broad jump, and T-agility measures pre- and post-4-week training interventions. There was no statistical significant difference (p = 0.11) between groups across all performance measures. Review of each distinct training intervention revealed greater percent improvements in SP20 (0.55; -0.49; -0.12), SP40 (0.26; -0.72; -1.33), SP60 (0.27; 0.15; -0.27), standing broad jump (1.80; 0.67; 1.1), and T-agility (2.33; 1.23; -0.04) with complex training interventions than with the heavy resistance or plyometric training interventions, respectively. Plyometric-only training showed greater percent changes in vertical jump (1.90) than with complex (0.97) or heavy resistance training (0.36). The present results indicate that complex training can provide strength and conditioning professionals equal, if not slightly greater, improvements in muscular power than traditional heavy resistance- and plyometric-only interventions in moderately trained athletes. Complex training can be another valuable method for short-term power and speed improvements in athletes in isolation or in conjunction with other power development methods.     

Ligneous membranitis in Scottish Terriers is associated with a single nucleotide polymorphism in the plasminogen (PLG) gene

Ligneous membranitis (LM) is a rare chronic inflammatory condition of the mucous membranes associated with plasminogen (encoded by PLG) deficiency in affected humans and dogs. In human, the condition is genetic in nature with numerous mutations and polymorphisms in PLG identified in affected individuals and related family members. The condition is uncommonly reported in dogs and, to date, no genetic studies have been performed. We identified related Scottish Terriers (littermates) with severe LM and unaffected relatives (sire, dam and a sibling from a previous litter). Plasma plasminogen activity was below normal in one affected dog but within normal reference intervals for the other. Sequencing of PLG from the affected dogs revealed a homozygous A>T single nucleotide polymorphism in an intron donor site (c.1256+2T>A). The related, unaffected dogs displayed heterozygous alleles at this position (c.1256+2T/A), whereas no mutation was detected in unaffected, non‐related control dogs. This is the first report to identify gene polymorphisms associated with LM in dogs.     

Affordable uniform isotope labeling with <Superscript>2</Superscript>H, <Superscript>13</Superscript>C and <Superscript>15</Superscript>N in insect cells

For a wide range of proteins of high interest, the major obstacle for NMR studies is the lack of an affordable eukaryotic expression system for isotope labeling. Here, a simple and affordable protocol is presented to produce uniform labeled proteins in the most prevalent eukaryotic expression system for structural biology, namely Spodoptera frugiperda insect cells. Incorporation levels of 80 % can be achieved for ¹⁵N and ¹³C with yields comparable to expression in full media. For ²H,¹⁵N and ²H,¹³C,¹⁵N labeling, incorporation is only slightly lower with 75 and 73 %, respectively, and yields are typically twofold reduced. The media were optimized for isotope incorporation, reproducibility, simplicity and cost. High isotope incorporation levels for all labeling patterns are achieved by using labeled algal amino acid extracts and exploiting well-known biochemical pathways. The final formulation consists of just five commercially available components, at costs 12-fold lower than labeling media from vendors. The approach was applied to several cytosolic and secreted target proteins.     

Control of resistance training intensity by the OMNI perceived exertion scale

The purpose of this study was to determine the applicability of the rating of perceived exertion (RPE) scale as a means of controlling resistance training intensity and establishing the relationship between the RPE value, load, and mechanical power (MP) produced during the bench press. Eleven men (22.1 ± 1.0 years) were evaluated on 8 separate days with 48 hours of rest between sessions. After determining the 1 repetition maximum (1RM) value, each subject underwent 7 tests until achieving muscular failure with the following percentage ranges: 30-40, >40-50, >50-60, >60-70, >70-80, >80-90, and >90%. A rotary encoder and the OMNI-RES (0-10) scale were used to estimate the power and to determine the perception of effort (RPE) expressed after each repetition of each set. The RPE produced from the start to the end of each set was related to the percentage of the load and the variability of the MP measured. Additionally, except for the >90% range, significant differences (p < 0.05) between the initial RPE (RPE I) and the average RPE of the first 3 repetitions (RPE 1_3 rep) with respect to the RPE produced with a 10% reduction in MP were identified for all the ranges. These relationships demonstrate the utility of RPE for controlling resistance training intensity.