Virus-Derived Small Interfering RNAs Affect the Accumulations of Viral and Host Transcripts in Maize

RNA silencing is a conserved surveillance mechanism against invading viruses in plants, which involves the production of virus-derived small interfering RNAs (vsiRNAs) that play essential roles in the silencing of viral RNAs and/or specific host transcripts. However, how vsiRNAs function to target viral and/or host transcripts is poorly studied, especially in maize (Zea mays L.). In this study, a degradome library constructed from Sugarcane mosaic virus (SCMV)-inoculated maize plants was analyzed to identify the cleavage sites in viral and host transcripts mainly produced by vsiRNAs. The results showed that 42 maize transcripts were possibly cleaved by vsiRNAs, among which several were involved in chloroplast functions and in biotic and abiotic stresses. In addition, more than 3000 cleavage sites possibly produced by vsiRNAs were identified in positive-strand RNAs of SCMV, while there were only four cleavage sites in the negative-strand RNAs. To determine the roles of vsiRNAs in targeting viral RNAs, six vsiRNAs were expressed in maize protoplast based on artificial microRNAs (amiRNAs), of which four could efficiently inhibit the accumulations of SCMV RNAs. These results provide new insights into the genetic manipulation of maize with resistance against virus infection by using amiRNA as a more predictable and useful approach.

An epidemiologic study of pelvic organ prolapse in postmenopausal women: a population-based sample in China

OBJECTIVE

This study aimed to assess the prevalence and factors associated with symptomatic pelvic organ prolapse (POP) in a representative sample of postmenopausal Chinese women.

METHODS

A total of 20,008 postmenopausal Chinese women were recruited to this cross-sectional study between February 2014 and March 2016. The prevalence of symptomatic POP, defined as any stage II or higher POP resulting in symptoms, was assessed using questionnaires and physical examinations. Multivariable logistic regression was used to assess factors associated with symptomatic POP.

RESULTS

Among all women with natural menopause included in the study (mean age =61.98 ± 10.62 years), 2962 of 20,008 women (14.80%, 95% confidence interval [CI] 14.3-15.3%) had symptomatic POP. In the multivariate analysis, women were more likely to have symptomatic POP if aged 50-59 years (adjusted odds ratio [AOR] 1.322, 95% CI 1.123-1.560), 60-69 years (AOR 1.603, 95% CI 1.352-1.907), or above 70 years (AOR 1.824, 95% CI 1.158-2.197), compared with women aged 40-49 years. Having delivered two times (AOR 1.145, 95% CI 1.105-1.292) or three or more times (AOR 1.384, 95% CI 1.214-1.578) was significantly associated with symptomatic POP. Compared with normal weight women, overweight women (AOR 1.365, 95% CI 1.247-1.494) and obese women (AOR 1.548, 95% CI 1.344-1.780) were more likely to have POP. Living in an urban area, smoking, alcohol consumption, cough, constipation, mental labor, physical disease, and gynecological diseases were also associated with symptomatic POP.

CONCLUSIONS

Symptomatic POP affects nearly 15% of postmenopausal women in China. The prevalence of symptomatic POP increases significantly with age, body mass index, and parity.

Characterization of maize translational responses to sugarcane mosaic virus infection

Sugarcane mosaic virus (SCMV) frequently causes dramatic losses in maize production as the main pathogen of maize dwarf mosaic disease. It is important to understand the translational responses in maize to SCMV infection since viruses have to recruit host translation apparatus to express their proteins. However, due to technical limitations, research on virus translation lags far behind that on transcription. Here, we studied the relationship between systemic symptom expression and virus accumulation and found that both SCMV RNA and proteins accumulated rapidly during the systemic infection process in which varying degrees of chlorosis to mosaic symptoms developed on non-inoculated leaves. In addition, we applied ribosome profiling, which couples polysomal mRNA isolation with high-throughput sequencing, on the symptomatic leaves infected with SCMV to unravel the translational responses of maize to viral infection on a genome-wide scale. The results showed that only the genomic positive-stranded RNA of SCMV was involved in translation, and SCMV only occupied a small amount of translational resources of host plant at the early stage of infection. Further analyses on a global gene expression and gene ontology (GO) enrichment revealed that photosynthesis and metabolism were dramatically repressed at both transcriptional and translational levels. Altogether, our results laid a foundation for dissecting the molecular mechanism of plant translational responses to viral infection.

Diagnostic guidelines for the histological particle algorithm in the periprosthetic neo-synovial tissue

BACKGROUND

The identification of implant wear particles and non-implant related particles and the characterization of the inflammatory responses in the periprosthetic neo-synovial membrane, bone, and the synovial-like interface membrane (SLIM) play an important role for the evaluation of clinical outcome, correlation with radiological and implant retrieval studies, and understanding of the biological pathways contributing to implant failures in joint arthroplasty. The purpose of this study is to present a comprehensive histological particle algorithm (HPA) as a practical guide to particle identification at routine light microscopy examination.

METHODS

The cases used for particle analysis were selected retrospectively from the archives of two institutions and were representative of the implant wear and non-implant related particle spectrum. All particle categories were described according to their size, shape, colour and properties observed at light microscopy, under polarized light, and after histochemical stains when necessary. A unified range of particle size, defined as a measure of length only, is proposed for the wear particles with five classes for polyethylene (PE) particles and four classes for conventional and corrosion metallic particles and ceramic particles.

RESULTS

All implant wear and non-implant related particles were described and illustrated in detail by category. A particle scoring system for the periprosthetic tissue/SLIM is proposed as follows: 1) Wear particle identification at light microscopy with a two-step analysis at low (× 25, × 40, and × 100) and high magnification (× 200 and × 400); 2) Identification of the predominant wear particle type with size determination; 3) The presence of non-implant related endogenous and/or foreign particles. A guide for a comprehensive pathology report is also provided with sections for macroscopic and microscopic description, and diagnosis.

CONCLUSIONS

The HPA should be considered a standard for the histological analysis of periprosthetic neo-synovial membrane, bone, and SLIM. It provides a basic, standardized tool for the identification of implant wear and non-implant related particles at routine light microscopy examination and aims at reducing intra-observer and inter-observer variability to provide a common platform for multicentric implant retrieval/radiological/histological studies and valuable data for the risk assessment of implant performance for regional and national implant registries and government agencies.

Mild Hypothermia Protects Renal Function in Ischemia-reperfusion Kidney: An Experimental Study in Mice

Mild hypothermia reduces the damage caused by hypoxia and oxidative stress, but how this happens is not very clear. Mice were anesthetized and their core body temperature was maintained at 38 ± 0.5°C and 32 ± 0.5°C. The renal artery and renal veins were blocked for 35 minutes and reperfusion was performed. Twenty-four hours later, serum was obtained to detect the concentrations of creatinine. The expression of CIRP, TRX, Bcl-2, and Bax were detected in tissue samples using Western blot. Apoptosis was measured using terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling and the apoptosis rates were calculated. SOD and MDA were detected to determine the extent of oxidative damage in different groups. The concentration of creatinine in the NC group was 2.11 ± 0.39 mg/dL. Compared to the IR group, the concentration of creatinine decreased in MH+IR group and showed a significant statistical difference (8.74 ± 1.38 mg/dL vs 15.36 ± 2.13 mg/dL, P < .01); the apoptosis rate also decreased with statistical significance (15.02 ± 1.45% vs 37.02 ± 5.70%, P < .01). Compared to the IR group, the expression of CIRP, TRX, and the Bcl-2/Bax ratio significantly increased in the MH+IR group. The SOD activity in the MH+IR group increased (26.90 ± 4.41 U/mgprot vs 16.85 ± 2.41 U/mgprot, P < .05) and the MDA level decreased (0.76 ± 0.18 nmol/mgprot vs 1.37 ± 0.32 nmol/mgprot, P < .05) compared to those of the IR group. Mild hypothermia protects mice kidneys from ischemia-reperfusion damage by reducing oxidative stress injury and apoptosis.

Myocardial ischaemia reperfusion injury: the challenge of translating ischaemic and anaesthetic protection from animal models to humans

Myocardial ischaemia reperfusion injury is the leading cause of death in patients with cardiovascular disease. Interventions such as ischaemic pre and postconditioning protect against myocardial ischaemia reperfusion injury. Certain anaesthesia drugs and opioids can produce the same effects, which led to an initial flurry of excitement given the extensive use of these drugs in surgery. The underlying mechanisms have since been extensively studied in experimental animal models but attempts to translate these findings to clinical settings have resulted in contradictory results. There are a number of reasons for this such as dose response, the intensity of the ischaemic stimulus applied, the duration of ischaemia and lost or diminished cardioprotection in common co-morbidities such as diabetes and senescence. This review focuses on current knowledge regarding myocardial ischaemia reperfusion injury and cardioprotective interventions both in experimental animal studies and in clinical trials.

A potential strategy for counteracting age-related sarcopenia: preliminary evidence of combined exercise training and leucine supplementation

Previous research has demonstrated the positive effects of concurrent/combined aerobic and resistance exercise or leucine supplementation on skeletal muscle protein synthesis (MPS) and hypertrophy in aging organisms. However, the effects of a multimodal intervention which combines both aerobic and resistance exercise and leucine supplementation has not been fully elucidated. Eighteen month old and 2 month old C57BL/6 mice were assigned to aging control (AC, n = 8), aging and multimodal intervention (AMI, n = 8) and young control (YC, n = 8). Mice in the YC and AC groups were fed an alanine-rich diet (3.4%), and mice in the AMI group received an isonitrogenous leucine-supplemented (5%) diet in combination with combined aerobic (30 minutes swimming) and resistance exercise training (incremental jumping submersed in water with overload corresponding to 40%-50% body weight) for a total of 4 weeks. The gastrocnemius muscles were dissected for western blotting detection (signaling proteins involved in MPS) and the ex vivo determination of protein synthesis and protein content. The muscle strength of the hind limbs was measured pre-experiment and repeated once per week on Sunday for 4 weeks. Mice in the AC and AMI groups showed lower ex vivo protein synthesis, protein content, expression of signaling proteins involved in MPS, maximal grip strength but higher plasma cortisol compared with the YC group post intervention. When compared to AC mice, the multimodal treatment led to lower activity of Sestrin2, higher expression of PI3K III and the phosphorylation of mTOR, p70S6K and 4E-BP1, as well as higher plasma leucine, wet gastrocnemius muscle weight and muscle weight to body weight ratio. Furthermore, the multimodal intervention induced more pronounced anabolic response such as higher ex vivo protein synthesis rate, total protein content, and myofibrillar fractions in gastrocnemius muscle, and greater maximum grip strength. The present research shows that a multimodal intervention including combined both aerobic and resistance exercise training and 5% leucine supplementation has the potential to maintain skeletal muscle protein synthesis and attenuate losses in muscular strength during the aging process.

Identification of miRNAs and their targets in maize in response to Sugarcane mosaic virus infection

MicroRNAs (miRNAs) are endogenous non-coding small RNAs that play essential regulatory roles in plant development and environmental stress responses. Maize (Zea mays L.) is a global economically important food and forage crop. To date, a number of maize miRNAs have been identified as being involved in plant development and stress responses. However, the miRNA-mediated gene regulatory networks responsive to virus infections in maize remain largely unknown. In this study, the profiles of small RNAs in buffer- and Sugarcane mosaic virus (SCMV)-inoculated maize plants were obtained by high-throughput sequencing, respectively. A total of 154 known miRNAs and 213 novel miRNAs were profiled and most of the miRNAs identified were differentially expressed after SCMV infection. In addition, 70 targets of 13 known miRNAs and 3 targets of a novel miRNA were identified by degradome analysis. The results of Northern blotting and quantitative real-time PCR showed that the expression levels of the selected miRNAs and their targets were mostly influenced by SCMV infection at 12 days post inoculation, including up-regulation of miR168 and miR528, and down-regulation of miR159, miR397 and miR827. These results provide new insights into the regulatory networks of miRNAs and their targets in maize plants responsive to SCMV infection.

Transcriptome analysis of watermelon (Citrullus lanatus) fruits in response to Cucumber green mottle mosaic virus (CGMMV) infection

Cucumber green mottle mosaic virus (CGMMV) belongs to the Tobamovirus genus and is a major global plant virus on cucurbit plants. It causes severe disease symptoms on infected watermelon plants (Citrullus lanatus), particularly inducing fruit decay. However, little is known about the molecular mechanism of CGMMV-induced watermelon fruit decay. For this study, comparative analysis of transcriptome profiles of CGMMV-inoculated and mock-inoculated watermelon fruits were conducted via RNA-Seq. A total of 1,621 differently expressed genes (DEGs) were identified in CGMMV-inoculated watermelon, among which 1,052 were up-regulated and 569 were down-regulated. Functional annotation analysis showed that several DEGs were involved in carbohydrate metabolism, hormone biosynthesis and signaling transduction, secondary metabolites biosynthesis, and plant-pathogen interactions. We furthermore found that some DEGs were related to cell wall components and photosynthesis, which may directly be involve in the development of the symptoms associated with diseased watermelons. To confirm the RNA-Seq data, 15 DEGs were selected for gene expression analysis by qRT-PCR. The results showed a strong correlation between these two sets of data. Our study identified many candidate genes for further functional studies during CGMMV-watermelon interactions, and will furthermore help to clarify the understanding of pathogenic mechanism underlying CGMMV infection in cucurbit plants.

A Violaxanthin Deepoxidase Interacts with a Viral Suppressor of RNA Silencing to Inhibit Virus Amplification

RNA silencing plays a critical role against viral infection. To counteract this antiviral silencing, viruses have evolved various RNA silencing suppressors. Meanwhile, plants have evolved counter-counter defense strategies against RNA silencing suppression (RSS). In this study, the violaxanthin deepoxidase protein of maize (Zea mays), ZmVDE, was shown to interact specifically with the helper component-proteinase (HC-Pro; a viral RNA silencing suppressor) of Sugarcane mosaic virus (SCMV) via its mature protein region by yeast two-hybrid assay, which was confirmed by coimmunoprecipitation in Nicotiana benthamiana cells. It was demonstrated that amino acids 101 to 460 in HC-Pro and the amino acid glutamine-292 in ZmVDE mature protein were essential for this interaction. The mRNA levels of ZmVDE were down-regulated 75% to 65% at an early stage of SCMV infection. Interestingly, ZmVDE, which normally localized in the chloroplasts and cytoplasm, could relocalize to HC-Pro-containing aggregate bodies in the presence of HC-Pro alone or SCMV infection. In addition, ZmVDE could attenuate the RSS activity of HC-Pro in a specific protein interaction-dependent manner. Subsequently, transient silencing of the ZmVDE gene facilitated SCMV RNA and coat protein accumulation. Taken together, our results suggest that ZmVDE interacts with SCMV HC-Pro and attenuates its RSS activity, contributing to decreased SCMV accumulation. This study demonstrates that a host factor can be involved in secondary defense responses against viral infection in monocot plants.

Identification of differentially regulated maize proteins conditioning Sugarcane mosaic virus systemic infection

Sugarcane mosaic virus (SCMV) is the most important cause of maize dwarf mosaic disease. To identify maize genes responsive to SCMV infection and that may be involved in pathogenesis, a comparative proteomic analysis was performed using the first and second systemically infected leaves (termed 1 SL and 2 SL, respectively). Seventy-one differentially expressed proteins were identified in 1 SL and 2 SL upon SCMV infection. Among them, eight proteins showed the same changing patterns in both 1 SL and 2 SL. Functional annotations of regulated proteins and measurement of photosynthetic activity revealed that photosynthesis was more inhibited and defensive gene expression more pronounced in 1 SL than in 2 SL. Knockdown of regulated proteins in both 1 SL and 2 SL by a brome mosaic virus-based gene silencing vector in maize indicated that protein disulfide isomerase-like and phosphoglycerate kinase were required for optimal SCMV replication. By contrast, knockdown of polyamine oxidase (ZmPAO) significantly increased SCMV accumulation, implying that ZmPAO activity might contribute to resistance or tolerance. The results suggest that combining comparative proteomic analyses of different tissues and virus-induced gene silencing is an efficient way to identify host proteins supporting virus replication or enhancing resistance to virus infection.

One-step reverse transcription loop-mediated isothermal amplification for the detection of Maize chlorotic mottle virus in maize

Maize chlorotic mottle virus (MCMV) is spreading in many regions worldwide, causing maize lethal necrosis when co-infected with a potyvirid. In this study, one-step reverse transcription loop-mediated isothermal amplification (RT-LAMP) assay was developed to detect MCMV in maize. A set of four specific primers was designed based on the conserved coat protein gene sequences of MCMV. The RT-LAMP could be completed within 60min under isothermal condition at 63°C. The sensitivity test showed that the RT-LAMP was about 10-fold more sensitive than RT-PCR and no cross-reactivity was detected with other viral pathogens infecting maize in China. Moreover, the results of RT-LAMP could be visually inspected by SYBR Green I staining in a closed-tube, facilitating high-throughput application of MCMV detection. This method was further verified by testing field-collected samples. These results suggested that the developed MCMV RT-LAMP technique is a rapid, efficient and sensitive method which could be used as a routine screen for MCMV infection.

Characterization of small interfering RNAs derived from Rice black streaked dwarf virus in infected maize plants by deep sequencing

Rice black streaked dwarf virus (RBSDV) is the casual agent of maize rough dwarf disease, which frequently causes severe yield loss in China. However, the interaction between RBSDV and maize plants is largely unknown. RNA silencing is a conserved mechanism against viruses in plants. To understand the antiviral RNA interfering response in RBSDV-infected plants, the profile of virus-derived small interfering RNAs (vsiRNAs) from RBSDV in infected maize plants was obtained by deep sequencing in this study. Our data showed that vsiRNAs, accumulated preferentially as 21- and 22-nucleotide (nt) species, were mapped against all 10 genomic RNA segments of RBSDV and derived almost equally overall from both positive and negative strands, while there were significant differences in the accumulation level of vsiRNAs from segments 2, 4, 6, 7 and 10. The vsiRNAs (21 and 22 nt) generated from each segment of RBSDV genome had a 5'-terminal nucleotide bias toward adenine and uracil. The single-nucleotide resolution maps showed that RBSDV-derived siRNAs preferentially distributed in the 5'- or 3'-terminal regions of several genomic segments. In addition, our results showed that the mRNA levels of some components involved in antiviral RNA silencing pathway were differentially modified during RBSDV infection. Among them, the accumulation levels of ZmDCL1, ZmDCL2, ZmDCL3a, ZmAGO1a, ZmAGO1b, ZmAGO2a, ZmAGO18a and ZmRDR6 mRNAs were significantly up-regulated, while those of ZmDCL3b, ZmDCL4 and ZmAGO1c mRNAs showed no obvious changes in RBSDV-infected maize plants.

Mechanical environment change in root, periodontal ligament, and alveolar bone in response to two canine retraction treatment strategies

OBJECTIVE

To investigate the initial mechanical environment (ME) changes in root surface, periodontal ligament (PDL), and alveolar bone due to two treatment strategies, low or high moment-to-force ratio (M/F).

SETTING AND SAMPLE POPULATION

Indiana University-Purdue University Indianapolis. Eighteen patients who underwent maxillary bilateral canine retraction.

MATERIAL AND METHOD

Finite element models of the maxillary canines from the patients were built based on their cone beam computed tomography scans. For each patient, the canine on one side had a specially designed T-loop spring with the M/F higher than the other side. Four stress invariants (1st principal/dilatational/3rd principal/von Mises stress) in the tissues were calculated. The stresses were compared with the bone mineral density (BMD) changes reported previously for linking the ME change to bone modeling/remodeling activities. The correlation was tested by the mixed-model anova.

RESULTS

The alveolar bone in the direction of tooth movement is primarily in tension, while the PDL is in compression; the stresses in the opposite direction have a reversed pattern. The M/F primarily affects the stress in root. Three stress invariants (1st principal/3rd principal/dilatational stress) in the tooth movement direction have moderate correlations with BMD loss.

CONCLUSIONS

The stress invariants may be used to characterize what the osteocytes sense when ME changes. Their distributions in the tissues are significantly different, meaning the cells experience different stimuli. The higher bone activities along the direction of tooth movement may be related to the initial volumetric increase and decrease in the alveolar bone.

Harpagoside ameliorates the amyloid-β-induced cognitive impairment in rats via up-regulating BDNF expression and MAPK/PI3K pathways

So far, no effective disease-modifying therapies for Alzheimer's disease (AD) aiming at protecting or reversing neurodegeneration of the disease have been established yet. The present work aims to elucidate the effect of Harpagoside (abbreviated HAR), an iridoid glycosides purified from the Chinese medicinal herb Scrophularia ningpoensis, on neurodegeneration induced by β-amyloid peptide (Aβ) and the underlying molecular mechanism. Here we show that HAR exerts neuroprotective effects against Aβ neurotoxicity. Rats injected aggregated Aβ₁₋₄₀ into the bilateral hippocampus displayed impaired spatial learning and memory ability in a Y-maze test and novel object recognition test, while HAR treatment ameliorated Aβ₁₋₄₀-induced behavioral deficits. Moreover, administration of HAR increased the expression levels of brain-derived neurotrophic factor (BDNF) and activated the extracellular-regulated protein kinase (ERK) and the phosphatidylinositol 3-kinase (PI3-kinase) pathways both in the cerebral cortex and hippocampus of the Aβ₁₋₄₀-insulted rat model. Furthermore, in cultured primary cortical neurons, Aβ₁₋₄₂ induced significant decrease of choline acetyltransferase (ChAT)-positive neuron number and neurite outgrowth length, both of which were dose dependently increased by HAR. In addition, HAR pretreatment also significantly attenuated the decrease of cell viability in Aβ₁₋₄₂-injured primary cortical neurons. Finally, when K252a, an inhibitor of Trk tyrosine kinases, and a BDNF neutralizing antibody were added to the culture medium 2 h prior to HAR addition, the protective effect of HAR on Aβ₁₋₄₂-induced neurodegeneration in the primary cortical neuron was almost inhibited. Taken together, HAR exerting neuroprotection effect and ameliorating learning and memory deficit appears to be associated, at least in part, with up-regulation of BDNF content as well as activating its downstream signaling pathways, e.g., MAPK/PI3K pathways. It raises the possibility that HAR has potential to be a therapeutic agent against AD.