The K+/H+ antiporter LeNHX2 increases salt tolerance by improving K+ homeostasis in transgenic tomato

The endosomal LeNHX2 ion transporter exchanges H⁺ with K⁺ and, to lesser extent, Na⁺. Here, we investigated the response to NaCl supply and K⁺ deprivation in transgenic tomato (Solanum lycopersicum L.) overexpressing LeNHX2 and show that transformed tomato plants grew better in saline conditions than untransformed controls, whereas in the absence of K⁺ the opposite was found. Analysis of mineral composition showed a higher K⁺ content in roots, shoots and xylem sap of transgenic plants and no differences in Na⁺ content between transgenic and untransformed plants grown either in the presence or the absence of 120 mm NaCl. Transgenic plants showed higher Na⁺/H⁺ and, above all, K⁺/H⁺ transport activity in root intracellular membrane vesicles. Under K⁺ limiting conditions, transgenic plants enhanced root expression of the high‐affinity K⁺ uptake system HAK5 compared to untransformed controls. Furthermore, tomato overexpressing LeNHX2 showed twofold higher K⁺ depletion rates and half cytosolic K⁺ activity than untransformed controls. Under NaCl stress, transgenic plants showed higher uptake velocity for K⁺ and lower cytosolic K⁺ activity than untransformed plants. These results indicate the fundamental role of K⁺ homeostasis in the better performance of LeNHX2 overexpressing tomato under NaCl stress.     

MotifAnalyzer‐PDZ: A computational program to investigate the evolution of PDZ‐binding target specificity

Recognition of short linear motifs (SLiMs) or peptides by proteins is an important component of many cellular processes. However, due to limited and degenerate binding motifs, prediction of cellular targets is challenging. In addition, many of these interactions are transient and of relatively low affinity. Here, we focus on one of the largest families of SLiM‐binding domains in the human proteome, the PDZ domain. These domains bind the extreme C‐terminus of target proteins, and are involved in many signaling and trafficking pathways. To predict endogenous targets of PDZ domains, we developed MotifAnalyzer‐PDZ, a program that filters and compares all motif‐satisfying sequences in any publicly available proteome. This approach enables us to determine possible PDZ binding targets in humans and other organisms. Using this program, we predicted and biochemically tested novel human PDZ targets by looking for strong sequence conservation in evolution. We also identified three C‐terminal sequences in choanoflagellates that bind a choanoflagellate PDZ domain, the Monsiga brevicollis SHANK1 PDZ domain (mbSHANK1), with endogenously‐relevant affinities, despite a lack of conservation with the targets of a homologous human PDZ domain, SHANK1. All three are predicted to be signaling proteins, with strong sequence homology to cytosolic and receptor tyrosine kinases. Finally, we analyzed and compared the positional amino acid enrichments in PDZ motif‐satisfying sequences from over a dozen organisms. Overall, MotifAnalyzer‐PDZ is a versatile program to investigate potential PDZ interactions. This proof‐of‐concept work is poised to enable similar types of analyses for other SLiM‐binding domains (e.g., MotifAnalyzer‐Kinase). MotifAnalyzer‐PDZ is available at http://motifAnalyzerPDZ.cs.wwu.edu .     

Animal Board Invited Review: Meta-analysis of genetic parameters for resilience and efficiency traits in goats and sheep

Genetic selection focused purely on production traits has proven very successful in improving the productive performance of livestock. However, heightened environmental and infectious disease challenges have raised the need to also improve the resilience of animals to such external stressors, as well as their efficiency in utilising available resources. A better understanding of the relationship between efficiency and production and health traits is needed to properly account for it in breeding programmes and to produce animals that can maintain high production performance in a range of environmental conditions with minimal environmental footprint. The aim of this study was to perform a meta-analysis of genetic parameters for production, efficiency and health traits in sheep and goats. The dataset comprised 963 estimates of heritability and 572 genetic correlations collated from 162 published studies. A threelevel meta-analysis model was fitted. Pooled heritability estimates for milk production traits ranged between 0.27 ± 0.03 and 0.48 ± 0.13 in dairy goats and between 0.21 ± 0.06 and 0.33 ± 0.07 in dairy sheep. In meat sheep, the heritability of efficiency traits ranged from 0.09 ± 0.02 (prolificacy) up to 0.32 ± 0.14 (residual feed intake). For health traits, pooled heritability was 0.07 ± 0.01 (faecal egg count) and 0.21 ± 0.01 (somatic cell score) in dairy goats and 0.14 ± 0.04 (faecal egg count) and 0.13 ± 0.02 (somatic cell score) in dairy sheep. In meat sheep, the heritability of disease resistance and survival traits ranged between 0.07 ± 0.02 (mastitis) and 0.50 ± 0.10 (breech strike). Pooled estimates of genetic correlations between resilience and efficiency traits in dairy goats were not significantly different from zero with the exception of somatic cell score and fat content (?0.19 ± 0.01). In dairy sheep, only the unfavourable genetic correlation between somatic cell score and protein content (0.12 ± 0.03) was statistically significant. In meat sheep only, the correlations between growth and faecal egg count (?0.28 ± 0.11) as well as between growth and dagginess (?0.33 ± 0.13) were statistically significant and favourable. Results of this meta-analysis provide evidence of genetic antagonism between production and health in dairy sheep and goats. This was not observed in meat sheep where most of the pooled estimates had high standard errors and were non-significant. Based on the obtained results, it seems feasible to simultaneously improve efficiency and health in addition to production by including the different types of traits in the breeding goal. However, a better understanding of potential trade-offs between these traits would be beneficial. Particularly, more studies focused on reproduction and resilience traits linked to the animal’s multi-trait response to challenges are required.     

Relation of B-type natriuretic peptide to left ventricular wall stress as assessed by cardiac magnetic resonance imaging in patients with dilated cardiomyopathy

Ventricular loading conditions are crucial determinants of cardiac function and prognosis in heart failure. B-type natriuretic peptide (BNP) is mainly stored in the ventricular myocardium and is released in response to an increased ventricular filling pressure. We examined, therefore, the hypothesis that BNP serum concentrations are related to ventricular wall stress. Cardiac magnetic resonance imaging (MRI) was used to assess left ventricular (LV) mass and cardiac function of 29 patients with dilated cardiomyopathy and 5 controls. Left ventricular wall stress was calculated by using a thick-walled sphere model, and BNP was assessed by immunoassay. LV mass (r = 0.73, p < 0.001) and both LV end-diastolic (r = 0.54, p = 0.001) and end-systolic wall stress (r = 0.66, p < 0.001) were positively correlated with end-diastolic volume. LV end-systolic wall stress was negatively related to LV ejection fraction (EF), whereas end-diastolic wall stress was not related to LVEF. BNP concentration correlated positively with LV end-diastolic wall stress (r = 0.50, p = 0.002). Analysis of variance revealed LV end-diastolic wall stress as the only independent hemodynamic parameter influencing BNP (p < 0.001). The present approach using a thick-walled sphere model permits determination of mechanical wall stress in a clinical routine setting using standard cardiac MRI protocols. A correlation of BNP concentration with calculated LV stress was observed in vivo. Measurement of BNP seems to be sufficient to assess cardiac loading conditions. Other relations of BNP with various hemodynamic parameters (e.g., EF) appear to be secondary. Since an increased wall stress is associated with cardiac dilatation, early diagnosis and treatment could potentially prevent worsening of the outcome.     

Natural killer cells promote early CD8 T cell responses against cytomegalovirus

Understanding the mechanisms that help promote protective immune responses to pathogens is a major challenge in biomedical research and an important goal for the design of innovative therapeutic or vaccination strategies. While natural killer (NK) cells can directly contribute to the control of viral replication, whether, and how, they may help orchestrate global antiviral defense is largely unknown. To address this question, we took advantage of the well-defined molecular interactions involved in the recognition of mouse cytomegalovirus (MCMV) by NK cells. By using congenic or mutant mice and wild-type versus genetically engineered viruses, we examined the consequences on antiviral CD8 T cell responses of specific defects in the ability of the NK cells to control MCMV. This system allowed us to demonstrate, to our knowledge for the first time, that NK cells accelerate CD8 T cell responses against a viral infection in vivo. Moreover, we identify the underlying mechanism as the ability of NK cells to limit IFN-alpha/beta production to levels not immunosuppressive to the host. This is achieved through the early control of cytomegalovirus, which dramatically reduces the activation of plasmacytoid dendritic cells (pDCs) for cytokine production, preserves the conventional dendritic cell (cDC) compartment, and accelerates antiviral CD8 T cell responses. Conversely, exogenous IFN-alpha administration in resistant animals ablates cDCs and delays CD8 T cell activation in the face of NK cell control of viral replication. Collectively, our data demonstrate that the ability of NK cells to respond very early to cytomegalovirus infection critically contributes to balance the intensity of other innate immune responses, which dampens early immunopathology and promotes optimal initiation of antiviral CD8 T cell responses. Thus, the extent to which NK cell responses benefit the host goes beyond their direct antiviral effects and extends to the prevention of innate cytokine shock and to the promotion of adaptive immunity.     

Reactions of the UVRABC excision nuclease with DNA damaged by diamminedichloroplatinum(II).

Mutants of Escherichia coli, which are blocked in excision repair (uvrA6, uvrB5, or uvrC34) are exceptionally sensitive to the antitumor drug cis-Pt(II)(NH3)2Cl2 (cis-DDP) but not the trans isomer. Plasmid DNA, damaged by either the cis or trans compound and treated with the UVRABC excision nuclease was cut as shown by conversion of supercoiled DNA to relaxed forms. All three protein products of the uvrA, uvrB, and uvrC genes were required for incision. End-labeled fragments damaged with cis-DDP and reacted with the UVRABC nuclease were cut at the 8th phosphodiester bond 5' and at the 4th phosphodiester bond 3' to adjacent GG's. DNA treated with trans-DDP was not cut appreciably at adjacent GG's by the repair enzyme as subsequent analysis of reaction products after enzyme digestion gave a pattern similar to those obtained with control untreated fragments. The results indicate that the UVRABC nuclease may promote cell survival by the removal of adjacent GG's which are crosslinked by cis-Pt(II)(NH3)2Cl2.     

USE OF SENSORY EVALUATION FOR MEASURING DEODORIZING EFFECTS OF AN AIR CONDITIONER

The application of sensory methodology for measuring deodorizing effect of an air conditioner equipped with electric plasma was introduced. Deodorizing effect was measured using chemical and sensory methods at different time (0, 30 and 60 min) and mode (control, blowing and cooling) of an air conditioner. Smoke from a roll of cigarette in a closed room was used as a source of odor and the concentrations of acetic acid and ammonia were measured as odorous chemical components. As one of the sensory methods triangle test was used and as a first step to obtain deodorizing effects by triangle test, the threshold of each panelist was obtained as the log dilution ratio of odor concentration at which the difference from odorless air was detected. The odor concentration at each time and mode was calculated using the threshold of the panel and the deodorizing effect was obtained on the basis of the odor concentration. In addition to a triangle test, scaling methods such as category scaling or magnitude estimation were used to measure deodorizing effect of an air conditioner. Deodorizing effects by scaling methods were calculated based on odor intensity with time at each mode. The regression analysis was done between the efficacy of deodorizing effect by sensory test and those by acetic acid and ammonia, the R² values of the regression equations for triangle test, category scale, and magnitude estimation were 0.84, 0.72 and 0.69, respectively. Deodorizing effect by triangle test explained the decrease of acetic acid and ammonia better than those by category scaling or magnitude estimation while high cost and time consuming labor involved in triangle tests reduced the merit. The results of this study demonstrated that various sensory methods could be used to measure deodorizing effect of air conditioners and further researches on fast and reliable methods are needed to establish the official procedures.