Effect of light and darkness on the growth and development of downy mildew pathogen Hyaloperonospora arabidopsidis

Disease development in plants requires a susceptible host, a virulent pathogen, and a favourable environment. Oomycete pathogens cause many important diseases and have evolved sophisticated molecular mechanisms to manipulate their hosts. Day length has been shown to impact plant‐oomycete interactions but a need exists for a tractable reference system to understand the mechanistic interplay between light regulation, oomycete pathogen virulence, and plant host immunity. Here we present data demonstrating that light is a critical factor in the interaction between Arabidopsis thaliana and its naturally occurring downy mildew pathogen Hyaloperonospora arabidopsidis (Hpa). We investigated the role of light on spore germination, mycelium development, sporulation and oospore formation of Hpa, along with defence responses in the host. We observed abundant Hpa sporulation on compatible Arabidopsis under day lengths ranging from 10 to 14 hours. Contrastingly, exposure to constant light or constant dark suppressed sporulation. Exposure to constant dark suppressed spore germination, mycelial development and oospore formation. Interestingly, exposure to constant light stimulated spore germination, mycelial development and oospore formation. A biomarker of plant immune system activation was induced under both constant light and constant dark. Altogether, these findings demonstrate that Hpa has the molecular mechanisms to perceive and respond to light and that both the host and pathogen responses are influenced by the light regime. Therefore, this pathosystem can be used for investigations to understand the molecular mechanisms through which oomycete pathogens like Hpa perceive and integrate light signals, and how light influences pathogen virulence and host immunity during their interactions

Assessment of the left atrial volume index and plasma NT-proANP level in patients with acute ST-elevation myocardial infarction

OBJECTIVES: Acute ST-elevation myocardial infarction is associated with ventricular dysfunction due to ischemia-induced progressive myocardial damage. The decrease in ventricular compliance causes left atrial dilatation and stretching of the atrial myocardium, which are the main stimuli for the secretion of atrial natriuretic peptide. The aim of this study was to evaluate left atrial dimensions and atrial natriuretic peptide levels in patients early after their first acute ST-elevation myocardial infarction and assess the probable interaction between coronary lesions and these measurements. METHODS: A total of 110 patients with acute myocardial infarction and 50 controls were studied. Plasma atrial natriuretic peptide was measured at admission. Left ventricular function, diameter, and volume index were evaluated using transthoracic echocardiography. Gensini and vessel scores of the patients who underwent coronary angiography were calculated. RESULTS: Plasma atrial natriuretic peptide in the patients with myocardial infarction was increased compared with that in controls (3.90±3.75 vs. 1.35±0.72 nmol/L,

Small RNA Inhibits Infection by Downy Mildew Pathogen Hyaloperonospora Arabidopsidis

Gene silencing exists in eukaryotic organisms as a conserved regulation of the gene expression mechanism. In general, small RNAs (sRNAs) are produced within the eukaryotic cells and incorporated into an RNA‐induced silencing complex (RISC) within cells. However, exogenous sRNAs, once delivered into cells, can also silence target genes via the same RISC. Here, we explored this concept by targeting the Cellulose synthase A3 (CesA3) gene of Hyaloperonospora arabidopsidis (Hpa), the downy mildew pathogen of Arabidopsis thaliana. Hpa spore suspensions were mixed with sense or antisense sRNAs and inoculated onto susceptible Arabidopsis seedlings. While sense sRNAs had no obvious effect on Hpa pathogenicity, antisense sRNAs inhibited spore germination and hence infection. Such inhibition of infection was not race‐specific, but dependent on the length and capping of sRNAs. Inhibition of infection by double stranded sRNA was more efficient than that observed with antisense sRNA. Thus, exogenous sRNA targeting conserved CesA3 could suppress Hpa infection in Arabidopsis, indicating the potential of this simple and efficient sRNA‐based approach for deciphering gene functions in obligate biotrophic pathogens as well as for R‐gene independent control of diseases in plants

Synchronization of Circadian Clock Gene Expression in Arabidopsis and Hyaloperonospora arabidopsidis and its Impact on Host-Pathogen Interactions

Organisms across all kingdoms have an internal circadian clock running in 24h cycles. This clock affects a variety of processes, including innate immunity in plants. However, the role of pathogen circadian clocks had not been extensively explored. We previously showed that light can influence infection of the oomycete Hyaloperonospora arabidopsidis (Hpa, downy mildew disease) on its natural host Arabidopsis thaliana. Here, we identified Hpa orthologs of known circadian clock genes (CCGs) Drosophila TIMELESS (TIM) and Arabidopsis Sensitive to Red Light Reduced 1 (AtSRR1) genes. Expression of both HpaTIM and HpaSRR1 showed a circadian rhythm when Hpa was exposed to constant light. Contrastingly, these two genes were negatively regulated by constant dark exposure. Furthermore, the expression patterns of HpaTIM and HpaSRR1 correlate with those of AtCCA1 and AtLHY, indicating a synchronisation of biological clock genes between the host and the pathogen. In addition, screening mutants of Arabidopsis Clock Regulated Genes (AtCRGs) with three virulent Hpa isolates revealed that mutations in AtCRGs influenced HpaTIM and HpaSRR1 expression and Hpa development, indicating a functional link between the plant biological clock and virulence. Moreover, sporulation of Hpa was reduced by targeting HpaTIM and HpaSRR1 with short synthesized small interfering RNAs, indicating that the pathogen clock is also relevant to virulence. We propose that plant and pathogen clocks are synchronized during infection and that proper regulation of both clocks are genetically necessary for pathogen virulence

Sperm DNA fragmentation: A new guideline for clinicians

Sperm DNA integrity is crucial for fertilization and development of healthy offspring. The spermatozoon undergoes extensive molecular remodeling of its nucleus during later phases of spermatogenesis, which imparts compaction and protects the genetic content. Testicular (defective maturation and abortive apoptosis) and post-testicular (oxidative stress) mechanisms are implicated in the etiology of sperm DNA fragmentation (SDF), which affects both natural and assisted reproduction. Several clinical and environmental factors are known to negatively impact sperm DNA integrity. An increasing number of reports emphasizes the direct relationship between sperm DNA damage and male infertility. Currently, several assays are available to assess sperm DNA damage, however, routine assessment of SDF in clinical practice is not recommended by professional organizations

A STUDY ON THE EIGENFREQUENCIES OF A VIBRATING TWO PARTED BEAM-MASS SYSTEM

A mathematical model is established to find the eigenfrequencies of a system which consists of two beam segments connected with each other via a distributed mass. The beam segments are simply supported at their other ends. This model enables one to obtain the frequencies of some special cases like stepped beams and shafts, classical simply supported beams and beams carrying concentrated mass. Furthermore, in order to calculate the fundametal frequency of such a system, an approximate method is given. For this purpose, the deflection equations of the system are also derived in non-dimensional form

ENDÜSTRİYEL VE TÜKETİCİ SONRASI ATIKLAR İLE TİCARİLEŞEBİLİR DENİM KUMAŞ ÜRETİMİ

Bu çalışmanın amacı, sıfır atık konseptine uygun olarak kaliteden ödün vermeden %100 geri dönüşüm denim üretimidir. Öncelikli olarak denim kumaş üretim sürecinde hammaddeden mamule atık noktaların tespiti yapılmıştır. Sonraki süreçte endüstriyel atıklar (denim sektöründe geri kazanılan pamuk lifleri) ve tüketici sonrası atıklardan (PET şişe atıklarından geri kazanılan lifler) denim kumaşlar üretilmiştir. Bahsedilen liflere ek olarak olumsuz yönleri elimine edebilmek için klasik pamuk lifleri ve rejenere selülozik Tencel® lifleri de taşıyıcı lifler olarak çalışmada kullanılmıştır. Yapılan tasarıma ve konstrüksiyona bağlı olarak, lif tiplerinin iplik veya kumaş karakteristikleri üzerine etkisi araştırılmıştır. Ayrıca, lifler ve iplik/kumaş sonuçları arasındaki ilişki korelasyon analizi ile istatistiksel olarak değerlendirilmiştir. Araştırmanın sonuçları lif miktarının iplik düzgünsüzlüğü, kalın yer, neps, tüylülük, kumaş hava geçirgenliği ve aşınma direnci üzerinde önemli etkiye sahip olduğunu göstermektedirThe purpose of this study was to produce 100% recycled denim without a tradeoff in quality according to zero waste concepts. Initially, the waste points from raw materials to final product in denim fabric production process were determined. Then, denim fabrics were produced from post-industrial (recycled cotton fibers obtained from denim wastes) and post-consumer wastes (produced from recycled PET bottles). Classic cotton fibers and alternative regenerated cellulose fibers (Tencel®) were used as carrier fiber in addition to mentioned fibers for eliminating recycled fibers disadvantages. The effect of fiber types on yarn or fabric characteristics were investigated in accordance with planning design and construction. Furthermore, the relationships between fibers and yarns/fabric results were statistically evaluated using correlation analysis. The results of this investigation show that the amount of fibers have a significant effect on yarn unevenness, thick places, neps, hairiness, air permeability and abrasion resistance of the sample

NATURAL FREQUENCIES OF A RECTANGULAR PLATE CARRYING A DISTRIBUTED MASS

In this paper, an analytical method is presented to find the eigenfrequencies of a plate carrying an attachment which consist of a uniformly distributed mass. The frequency equation of polynomial type is obtained by applying the standard Galerkin procedure to the equation of motion. The nondimensional parameters which are associated with the location, the area density and the distribution of the mass, are defined in order to make the analysis results generally applicable. Then, the variation of the three lowest frequencies, especially of the fundamental frequency due to its significance, with respect to these nondimensional parameters is investigated. Furthermore, it is shown by a numerical example that the method can be used to study plates with concentrated mass as a special case. Finally, the effects of the location and the mass of such an attachment on the modal surfaces and nodal lines of a plate are investigated