Killing two enemies with one stone? Genomics of resistance to two sympatric pathogens in Norway spruce.

Trees must cope with the attack of multiple pathogens, often simultaneously during their long lifespan. Ironically, the genetic and molecular mechanisms controlling this process are poorly understood. The objective of this study was to compare the genetic component of resistance in Norway spruce to Heterobasidion annosum s.s. and its sympatric congener Heterobasidion parviporum. Heterobasidion root- and stem-rot is a major disease of Norway spruce caused by members of the Heterobasidion annosum species complex. Resistance to both pathogens was measured using artificial inoculations in half-sib families of Norway spruce trees originating from central to northern Europe. The genetic component of resistance was analysed using 63,760 genome-wide exome-capture sequenced SNPs and multitrait genome-wide associations. No correlation was found for resistance to the two pathogens; however, associations were found between genomic variants and resistance traits with synergic or antagonist pleiotropic effects to both pathogens. Additionally, a latitudinal cline in resistance in the bark to H. annosum s.s. was found; trees from southern latitudes, with a later bud-set and thicker stem diameter, allowed longer lesions, but this was not the case for H. parviporum. In summary, this study detects genomic variants with pleiotropic effects which explain multiple disease resistance from a genic level and could be useful for selection of resistant trees to both pathogens. Furthermore, it highlights the need for additional research to understand the evolution of resistance traits to multiple pathogens in trees.

Association genetics identifies a specifically regulated Norway spruce laccase gene, PaLAC5, linked to Heterobasidion parviporum resistance.

It is important to improve the understanding of the interactions between the trees and pathogens and integrate this knowledge about disease resistance into tree breeding programs. The conifer Norway spruce (Picea abies) is an important species for the forest industry in Europe. Its major pathogen is Heterobasidion parviporum, causing stem and root rot. In this study, we identified 11 Norway spruce QTLs (Quantitative trait loci) that correlate with variation in resistance to H. parviporum in a population of 466 trees by association genetics. Individual QTLs explained between 2.1 and 5.2% of the phenotypic variance. The expression of candidate genes associated with the QTLs was analysed in silico and in response to H. parviporum hypothesizing that (a) candidate genes linked to control of fungal sapwood growth are more commonly expressed in sapwood, and; (b) candidate genes associated with induced defences are respond to H. parviporum inoculation. The Norway spruce laccase PaLAC5 associated with control of lesion length development is likely to be involved in the induced defences. Expression analyses showed that PaLAC5 responds specifically and strongly in close proximity to the H. parviporum inoculation. Thus, PaLAC5 may be associated with the lignosuberized boundary zone formation in bark adjacent to the inoculation site.

300 mm Wafer-level, ultra-dense arrays of Au-capped nanopillars with sub-10 nm gaps as reliable SERS substrates.

The 193 nm deep UV immersion lithography is leveraged to fabricate highly dense and uniform arrays of Au-capped Si nanopillars on a 300 mm wafer level, and the substrates are applied in surface enhanced Raman spectroscopy for reliable molecule detection. Due to the sub-10 nm gap sizes and ultra-high array density with the lattice constant less than 100 nm, our nanopillar based substrates outperform the current commercial products in terms of the signal intensity, reproducibility and fabrication scale.

Effect of vascular endothelial growth factor and its receptor KDR on the transendothelial migration and local trafficking of human T cells in vitro and in vivo.

In these studies, we find that the vascular endothelial growth factor (VEGF) receptor KDR is expressed on subsets of mitogen-activated CD4(+) and CD8(+) T cells in vitro. We also found that KDR colocalizes with CD3 on mitogen-activated T cells in vitro and on infiltrates within rejecting human allografts in vivo. To evaluate whether VEGF and KDR mediate lymphocyte migration across endothelial cells (ECs), we used an in vitro live-time transmigration model and observed that both anti-VEGF and anti-KDR antibodies inhibit the transmigration of both CD4(+) and CD8(+) T cells across tumor necrosis factor α (TNFα)-activated, but not unactivated ECs. In addition, we found that interactions among CD4(+) or CD8(+) T cells and TNFα-activated ECs result in the induction of KDR on each T cell subset, and that KDR-expressing lymphocytes preferentially transmigrate across TNFα-activated ECs. Finally, using a humanized severe combined immunodeficient mouse model of lymphocyte trafficking, we found that KDR-expressing lymphocytes migrate into human skin in vivo, and that migration is reduced in mice treated with a blocking anti-VEGF antibody. These observations demonstrate that induced expression of KDR on subsets of T cells, and locally expressed VEGF, facilitate EC-dependent lymphocyte chemotaxis, and thus, the localization of T cells at sites of inflammation.

Thyroid hormone-induced cardiac mechano growth factor expression depends on beating activity.

The mechano growth factor (MGF), a splice variant of the IGF-I gene, was first discovered in mechanically overloaded skeletal muscle and was shown to play an important role in proliferation of muscle stem cells. Since then, the presence and effects of MGF have been demonstrated in other tissues. MGF has been shown to act neuroprotectively during brain ischemia, and pretreatment with MGF before myocardial infarction improves cardiac function. Because MGF plays a permissive role in exercise-induced skeletal muscle hypertrophy, we hypothesize that MGF is commonly involved in cardiac hypertrophy. To investigate the regulation of MGF expression in heart, mice were treated with thyroid hormone (T(3)) for 12 d to induce physiological cardiac hypertrophy. MGF mRNA expression was specifically increased in midregions of the septum and left ventricular wall. Interestingly, MGF expression strongly correlated with the increased or decreased beating frequency of hyperthyroid and hypothyroid hearts. To further investigate the mechanically dependent induction of MGF, neonatal rat cardiomyocytes were isolated and exposed to T(3). Upon T(3) treatment, cardiomyocytes increased both contractile activity measured as beats per minute and MGF as well as IGF-IEa mRNA expression. Importantly, when cardiomyocytes were contractile arrested by KCl, simultaneous exposure to T(3) prevented the up-regulation of MGF, whereas IGF-IEa was still induced. These studies demonstrated that MGF but not IGF-IEa expression is dependent on beating activity. These findings suggest that MGF is specifically stimulated by mechanical loading of the heart to mediate the hypertrophic response to thyroid hormone.

The role of nitric oxide in renal transplantation.

This review discusses the concept that nitric oxide synthase (NOS) may orchestrate both the inflammatory response to the renal allograft and anti-inflammatory defense in the graft itself. NO is produced by endothelial, epithelial, as well as inflammatory cells. In the setting of transplantation, the endothelium is the first lining to be subjected to the early response to injury. In turn, activated endothelial cells facilitate leukocyte recruitment, immune-mediated injury, and angiogenesis. On activation by inflammatory stimuli, endothelial cells up-regulate multiple vasoactive substances, oxygen radicals, cytokines, chemokines, and growth factors. Therefore, endothelial integrity, especially the expression of protecting vasoactive agents, such as NO, may be a key factor in resistance or sensitivity to transplantation-mediated injury. Thus, evaluating the mechanisms by which NO is involved in either protecting or injuring the transplanted allogeneic kidney is important for our understanding of renal allograft rejection. This review focuses on the role of NO in the inflammatory endothelial-leukocyte interactions, which are implicated in acute and chronic rejection of the transplanted kidney.

Anti-inflammatory effects of tetrahydrobiopterin on early rejection in renal allografts: modulation of inducible nitric oxide synthase.

Oxidative stress contributes to the development of early transplant failure. As nitric oxide synthases (NOS) can act as sources of superoxide, we investigated the effect of the NOS cofactor tetrahydrobiopterin (BH4) on oxyradical production and early rejection in a rat kidney transplantation model. Allograft transplantation (Brown Norway to Lewis) showed more renal superoxide production and monocyte infiltration when compared with isografts (Lewis to Lewis). Administration of the stable BH4 precursor sepiapterin had no effect on superoxide production in the isografts (51+/-10 vs. 69+/-17 cps/10 mg protein), but led to a marked decrease in superoxide production in the allografts (116+/-11 vs. 60+/-6 cps/10 mg protein; P<0.05) and was accompanied by a reduction in periarterial macrophage infiltration (3.3+/-0.7 vs. 1.3+/-0.3 cells/vessel; P<0.05) and an increase in NO production (78+/-22 vs. 173+/-12 AU/g kidney) (P<0.01). In vitro experiments confirm that iNOS can produce superoxide mainly from the heme domain, whereas BH4 administration can reverse this superoxide production in the presence of adequate anti-oxidant defense. Our findings support the hypothesis that BH4 can be used to modulate the function of the inflammatory iNOS isoform and suggest a potential therapeutic role for sepiapterin in early allograft rejection.

Inducible nitric oxide synthase in renal transplantation.

The importance of the endothelial isoform of nitric oxide synthase (eNOS) has been well established. Endothelium-derived nitric oxide has been shown to be essential for vascular homeostasis and modulation of eNOS has thus become a target in prevention of cardiovascular disease. The role of the inducible form of nitric oxide synthase (iNOS) in vascular biology, however, is less clear. Classically, iNOS has been regarded as an enzyme that produces nmolar amounts of the nitric oxide radical, thereby leading to cellular damage. More recent data, however, have shown that the iNOS can be a superoxide, peroxynitrite as well as a nitric oxide-producing enzyme, while the biological effects of iNOS probably depend upon the sort of radical species released by the enzyme as well as the anti-oxidant capacity of the cellular microenvironment of the enzyme. This brief review discusses these aspects in relation to renal transplantation.

L-arginine supplementation improves function and reduces inflammation in renal allografts.

Recovery from ischemia/reperfusion and immune-mediated injury in the renal transplant is associated with reduced renal hemodynamics and increased leukocyte infiltration. In diverse models of renal failure, L-arginine supplementation improved hemodynamics and reduced inflammation. However in a proinflammatory environment, L-arginine can worsen renal injury. This study investigated the therapeutic potential of L-arginine supplementation in allogeneic renal transplantation: Brown Norway rat kidneys were transplanted into Lewis rat recipients, with one native kidney remaining. Recipients received low-dose cyclosporin A (2.5 mg/kg per d subcutaneously) to obtain moderate vascular and interstitial rejection, with or without 1% L-arginine in drinking water for 7 d posttransplantation. Transplantation increased renal vasoconstriction (from 16.9 +/- 1.33 to 35.1 +/- 8.6 units; P: < 0.01), thereby reducing GFR (from 0.96 +/- 0.09 to 0.48 +/- 0.10 ml/min; P: < 0.05). Treatment with L-arginine restored renal graft function to levels found in normal donors (renal vascular resistance, 15.7 +/- 1.69 units; GFR, 0.80 +/- 0.06 ml/min). L-arginine significantly reduced vascular occlusion because of less inflammation, endothelial disruption, and thrombosis. L-arginine also decreased tubulitis, interstitial injury, and macrophage infiltration. These protective effects suggest that L-arginine might be useful as additive therapy to conventional immune suppression.

Dysfunctional renal nitric oxide synthase as a determinant of salt-sensitive hypertension: mechanisms of renal artery endothelial dysfunction and role of endothelin for vascular hypertrophy and Glomerulosclerosis.

This study investigated the role of renal nitric oxide synthase (NOS), endothelin, and possible mechanisms of renovascular dysfunction in salt-sensitive hypertension. Salt-sensitive (DS) and salt-resistant (DR) Dahl rats were treated for 8 wk with high salt diet (4% NaCl) alone or in combination with the ET(A) receptor antagonist LU135252 (60 mg/kg per d). Salt loading markedly increased NOS activity (pmol citrulline/mg protein per min) in renal cortex and medulla in DR but not in DS rats by 270 and 246%, respectively. Hypertension in DS rats was associated with renal artery hypertrophy, increased vascular and renal endothelin-1 (ET-1) protein content, and glomerulosclerosis. In the renal artery but not in the aorta of hypertensive DS rats, endothelium-dependent relaxation to acetylcholine was unchanged; however, endothelial dysfunction due to enhanced prostanoid-mediated, endothelium-dependent contractions and attenuation of basal nitric oxide release was present. Treatment with LU135252 reduced hypertension in part, but completely prevented activation of tissue ET-1 without affecting ET-3 levels. This was associated with a slight increase of renal NOS activity, normalization of endothelial dysfunction and renal artery hypertrophy, and marked attenuation of glomerulosclerosis. Thus, DS rats fail to increase NOS activity in response to salt loading. This abnormality may predispose to activation of the tissue ET-1 system, abnormal renal vasoconstriction, and renal injury. Chronic ET(A) receptor blockade normalized salt-induced changes in the renal artery and reduced glomerular injury, suggesting therapeutic potential for ET antagonists in salt-sensitive forms of hypertension.