Sustained fixation induced changes in phoria and convergence peak velocity

Purpose

This study sought to investigate the influence of phoria adaptation on convergence peak velocity from responses located at different initial vergence positions.

Methods

Symmetrical 4° convergence step responses and near dissociated phoria (measured at 40 cm from the subject''s midline) were recorded from six subjects with normal binocular vision using an infrared limbus tracking system with a haploscope. Two different sustained fixations (1° and 16° convergent rotation along the subject''s midline) were used to study whether phoria had an influence on the peak velocity of convergence responses located at two initial vergence positions (1° or ‘far’ steps and 12° or ‘near’ steps).

Results

Phoria was significantly adapted after a sustained fixation task at near (16°) and far (1°) (p<0.002). A repeated measures ANOVA showed that convergence far steps were significantly faster than the near steps (p<0.03). When comparing convergence steps with the same initial vergence position, steps measured after near phoria adaptation were faster than responses after far adaptation (p<0.02). A regression analysis demonstrated that the change in phoria and the change in convergence peak velocity were significantly correlated for the far convergence steps (r = 0.97, p = 0.001). A weaker correlation was observed for the near convergence steps (r = 0.59, p = 0.20).

Conclusion

As a result of sustained fixation, phoria was adapted and the peak velocity of the near and far convergence steps was modified. This study has clinical considerations since prisms, which evoke phoria adaptation, can be prescribed to help alleviate visual discomfort. Future investigations should include a systematic study of how prisms may influence convergence and divergence eye movements for those prescribed with prisms within their spectacles.     

Role of plant autophagy in stress response

Autophagy is a conserved pathway for the bulk degradation of cytoplasmic components in all eukaryotes. This process plays a critical role in the adaptation of plants to drastic changing environmental stresses such as starvation, oxidative stress, drought, salt, and pathogen invasion. This paper summarizes the current knowledge about the mechanism and roles of plant autophagy in various plant stress responses.     

大豆异黄酮对大鼠乳腺癌细胞内cAMP/PKA信号途径的影响

本实验研究了大豆异黄酮对SHZ-88大鼠乳腺癌细胞内cAMP／PKA信号途径的影响。实验设3组：空白对照组、50μg／ml大豆黄酮及15μg／ml染料木素组。采用放射免疫测定法（RIA）检测了胞内cAMP的浓度、腺苷酸环化酶（adenylate cyclase,AC）和磷酸二酯酶（phosphodiesterase,PDE）的活性,用（γ-^32P）ATP掺入法测定cAMP依赖性PKA的活性,半定量RT-PCR法分析cAMP反应元件结合蛋白（cAMP response element binding protein,CREB）mRNA表达的变化。结果表明：在处理后5min,大豆黄酮组和染料木素组细胞的cAMP浓度分别比对照组升高了9．5％和11．0％（P〈0．05）：10min时,分别比对照组升高31．0％和40.3％（P〈0．01）。3组细胞的AC活性在处理时间内没有明显变化。但在处理后5min,大豆黄酮组和染料木素组细胞的PDE活性分别降至对照组的71．8％和71．6％（P〈0．05）。处理后20min,大豆黄酮组和染料木素组细胞PKA活性分别上升到对照组的125．8％和122．3％（P〈0．05）;到40min时仍维持在高水平。大豆黄酮组和染料木素组细胞CREB mRNA的表达量在处理后3h分别比对照组增加31．6％和51．1％（P〈0．05）;6h后开始下降。这些结果提示,大豆异黄酮能够激活大鼠乳腺癌细胞内cAMP／PKA信号途径;而且是通过抑制磷酸二酯酶的活性,导致胞内cAMP浓度升高而实现的。     

模拟酸雨对小黑麦种子萌发及幼苗生理特性的影响

以小黑麦品种中饲237为材料。在不同pH值的模拟酸雨条件下对种子萌发及幼苗生理特性进行了研究。分别测定了发芽率、发芽势、发芽指数、活力指数和种子脱氢酶含量、幼苗鲜重、幼苗叶片叶绿素含量、叶片电导率等指标。结果表明,种子的各项发芽指标及种子脱氢酶含量、幼苗鲜重、叶绿素含量等随酸雨pH值减小整体呈降低趋势,叶片电导率则随酸雨pH值减小而有增加趋势。     

红树林区微生物资源

随着工业的迅猛发展,工业废料源源不断地向海洋输出,污染日趋严重。人们在大力开发海洋微生物自净能力的同时,也对海岸线的绿色卫士——红树林给予了密切关注,积极展开红树林区微生物资源的开发利用。本文从红树林区微生物库的资源多样性、微生物在物质循环和能量流动中的作用、生理活性物质、代谢产物和污染治理等几个方面进行综述。     

Transformation from Organo-Cr (III) to Trivalent Chromium Mineral (Guyanaite/Grimaldiite) and its Environmental Implication

Remediation of heavy-metal contamination by biomineralization has become an environmentally very important issue in the last two decades. Here we describe the transformation of amorphous organo-Cr(III) to chromium hydroxide oxide (guyanaite/grimaldiite) by hydrothermal treatment (HTT). First, glycine-Cr(III) was synthesized to serve as a simple model for exploring the conditions favoring HTT. Cell-bound Cr(III) was obtained by the reduction of hexavalent chromium [Cr(VI)] to trivalent chromium [Cr(III)] by Bacillus cereus. Then the reduced Cr(III) was chelated by ligands at the cell surface, forming cell-bound Cr(III). Subsequently, HTT was applied to treat cell-bound Cr(III) at different temperatures and for different lengths of time. The results showed that, by this treatment at 200°C for 7 days or at 250°C for 1 day, glycine-Cr(III) was converted to trivalent chromium mineral (guyanaite/grimaldiite), having the form of nanosheets with a length of 10～20 nm and a width of 3～5 nm under the described conditions. Cell-bound Cr(III) could also be converted to guyanaite/grimaldiite at 250°C for 9 days if it was bound by an organic compound more complex than glycine. Our finding showed that organo-Cr(III) could be transformed into minerals by an appropriate hydrothermal process, which is applicable to bioremediation of heavy-metal pollution. Our findings also suggest that organo-Cr(III) may play an important role in the biogeochemistry of chromium.     

AsHSP17, a creeping bentgrass small heat shock protein modulates plant photosynthesis and ABA‐dependent and independent signalling to attenuate plant response to abiotic stress

Heat shock proteins (HSPs) are molecular chaperones that accumulate in response to heat and other abiotic stressors. Small HSPs (sHSPs) belong to the most ubiquitous HSP subgroup with molecular weights ranging from 12 to 42 kDa. We have cloned a new sHSP gene, AsHSP17 from creeping bentgrass (Agrostis stolonifera) and studied its role in plant response to environmental stress. AsHSP17 encodes a protein of 17 kDa. Its expression was strongly induced by heat in both leaf and root tissues, and by salt and abscisic acid (ABA) in roots. Transgenic Arabidopsis plants constitutively expressing AsHSP17 exhibited enhanced sensitivity to heat and salt stress accompanied by reduced leaf chlorophyll content and decreased photosynthesis under both normal and stressed conditions compared to wild type. Overexpression of AsHSP17 also led to hypersensitivity to exogenous ABA and salinity during germination and post‐germinative growth. Gene expression analysis indicated that AsHSP17 modulates expression of photosynthesis‐related genes and regulates ABA biosynthesis, metabolism and ABA signalling as well as ABA‐independent stress signalling. Our results suggest that AsHSP17 may function as a protein chaperone to negatively regulate plant responses to adverse environmental stresses through modulating photosynthesis and ABA‐dependent and independent signalling pathways.     

Combined mutagenesis of <Emphasis Type="Italic">Rhodosporidium toruloides</Emphasis> for improved production of carotenoids and lipids

Objectives

To improve production of lipids and carotenoids by the oleaginous yeast Rhodosporidium toruloides by screening mutant strains.

Results

Upon physical mutagenesis of the haploid strain R. toruloides np11 with an atmospheric and room temperature plasma method followed by chemical mutagenesis with nitrosoguanidine, a mutant strain, R. toruloides XR-2, formed dark-red colonies on a screening plate. When cultivated in nitrogen-limited media, XR-2 cells grew slower but accumulated 0.23 g lipids/g cell dry wt and 0.75 mg carotenoids/g CDW. To improve its production capacity, different amino acids and vitamins were supplemented. p-Aminobenzoic acid and tryptophan had beneficial effects on cell growth. When cultivated in nitrogen-limited media in the presence of selected vitamins, XR-2 accumulated 0.41 g lipids/g CDW and 0.69 mg carotenoids/g CDW.

Conclusions

A mutant R. toruloides strain with improved production profiles for lipids and carotenoids was obtained, indicating its potential to use combined mutagenesis for a more productive phenotype.

     

The Role of Physical Activity in Harm Reduction among Betel Quid Chewers from a Prospective Cohort of 419,378 Individuals

ObjectiveTo assess the benefits of regular exercise in reducing harms associated with betel quid (BQ) chewing.MethodsThe study cohort, 419,378 individuals, participated in a medical screening program between 1994 and 2008, with 38,324 male and 1,495 female chewers, who consumed 5–15 quids of BQ a day. Physical activity of each individual, based on “MET-hour/week”, was classified as “inactive” or “active”, where activity started from a daily 15 minutes/day or more of brisk walking (≥3.75 MET-hour/week). Hazard ratios for mortality and remaining years in life expectancy were calculated.ResultsNearly one fifth (18.7%) of men, but only 0.7% of women were chewers. Chewers had a 10-fold increase in oral cancer risk; and a 2-3-fold increase in mortality from lung, esophagus and liver cancer, cardiovascular disease, and diabetes, with doubling of all-cause mortality. More than half of chewers were physically inactive (59%). Physical activity was beneficial for chewers, with a reduction of all-cause mortality by 19%. Inactive chewers had their lifespan shortened by 6.3 years, compared to non-chewers, but being active, chewers improved their health by gaining 2.5 years. The improvement, however, fell short of offsetting the harms from chewing.ConclusionsChewers had serious health consequences, but being physically active, chewers could mitigate some of these adverse effects, and extend life expectancy by 2.5 years and reduce mortality by one fifth. Encouraging exercise, in addition to quitting chewing, remains the best advice for 1.5 million chewers in Taiwan.     

The Thioredoxin GbNRX1 Plays a Crucial Role in Homeostasis of Apoplastic Reactive Oxygen Species in Response to Verticillium dahliae Infection in Cotton

Examining the proteins that plants secrete into the apoplast in response to pathogen attack provides crucial information for understanding the molecular mechanisms underlying plant innate immunity. In this study, we analyzed the changes in the root apoplast secretome of the Verticillium wilt-resistant island cotton cv Hai 7124 (Gossypium barbadense) upon infection with Verticillium dahliae. Two-dimensional differential gel electrophoresis and matrix-assisted laser desorption/ionization tandem time-of-flight mass spectrometry analysis identified 68 significantly altered spots, corresponding to 49 different proteins. Gene ontology annotation indicated that most of these proteins function in reactive oxygen species (ROS) metabolism and defense response. Of the ROS-related proteins identified, we further characterized a thioredoxin, GbNRX1, which increased in abundance in response to V. dahliae challenge, finding that GbNRX1 functions in apoplastic ROS scavenging after the ROS burst that occurs upon recognition of V. dahliae. Silencing of GbNRX1 resulted in defective dissipation of apoplastic ROS, which led to higher ROS accumulation in protoplasts. As a result, the GbNRX1-silenced plants showed reduced wilt resistance, indicating that the initial defense response in the root apoplast requires the antioxidant activity of GbNRX1. Together, our results demonstrate that apoplastic ROS generation and scavenging occur in tandem in response to pathogen attack; also, the rapid balancing of redox to maintain homeostasis after the ROS burst, which involves GbNRX1, is critical for the apoplastic immune response.Cotton (Gossypium spp.) is one of the most economically important crops worldwide and a number of pathogens affect the growth and development of cotton plants. The soil-borne pathogen Verticillium dahliae (V. dahliae) causes the destructive vascular disease Verticillium wilt, which results in devastating reductions in plant mass, lint yield, and fiber quality (Bolek et al., 2005; Cai et al., 2009). To date, Verticillium wilt has not been effectively controlled in the most common cultivated cotton species, upland cotton (Gossypium hirsutum), and cultivars with stably inherited resistance to this disease are currently unavailable (Aguado et al., 2008; Jiang et al., 2009; Zhang et al., 2012a). Unlike upland cotton, sea-island cotton (Gossypium barbadense), which is only cultivated on a small scale, possesses Verticillium wilt resistance. Exploring the molecular mechanisms involved in the defense responses against V. dahliae invasion in G. barbadense can provide useful information for generating wilt-resistant G. hirsutum species through molecular breeding.During the past decades, progress has been made in studying the defense responses against V. dahliae infection in cotton. Global analyses have demonstrated that several signaling pathways, including those mediated by salicylic acid, ethylene, jasmonic acid, and brassinosteroids, activate distinct processes involved in V. dahliae defense (Bari and Jones, 2009; Grant and Jones, 2009; Gao et al., 2013a). Accumulating evidence indicates that many V. dahliae-responsive genes, such as GbWARKY1, GhSSN, GbERF, GhMLP28, GhNDR1, GhMKK2, and GhBAK1 (Qin et al., 2004; Gao et al., 2011, 2013b; Li et al., 2014a; Sun et al., 2014; Yang et al., 2015), play crucial roles in defense against Verticillium wilt. In addition, the biosynthesis of terpenoids, lignin, and gossypol also makes important contributions to V. dahliae resistance in cotton (Tan et al., 2000; Luo et al., 2001; Xu et al., 2011; Gao et al., 2013a). Together, these studies have greatly improved our understanding of the complex innate defense systems against V. dahliae infection in cotton.The initial interaction between plants and pathogens takes place in the apoplast, the compartment of the plant cell outside the cell membrane, including the cell wall and intercellular space (Dietz, 1997). In response to pathogen colonization, the attacked plant cells undergo significant cellular and molecular changes, such as reinforcement of the cell wall and secretion of antimicrobial molecules into the apoplastic space (Bednarek et al., 2010). Thus, the apoplast serves as the first line of defense against microbe invasion, and apoplast immunity can be considered an important component of the plant immune response to pathogens.Upon recognition of pathogen infection, rapid production of reactive oxygen species [the reactive oxygen species (ROS) burst] occurs in the apoplast (Lamb and Dixon, 1997; Torres et al., 2006; Torres, 2010). This ROS burst is regarded as a core component of the early plant immune response (Daudi et al., 2012; Doehlemann and Hemetsberger, 2013). During defense responses, apoplastic ROS can diffuse into the cytoplasm and serve as signals, interacting with other signaling processes such as phosphorylation cascades, calcium signaling, and hormone-mediated pathways (Kovtun et al., 2000; Mou et al., 2003). Apoplastic ROS can also directly strengthen the host cell walls by oxidative cross linking of glycoproteins (Bradley et al., 1992; Lamb and Dixon, 1997) or the precursors of lignin and suberin polymers (Hückelhoven, 2007). Moreover, apoplastic ROS can directly affect pathogens by degrading nucleic acids and peptides from microbes or causing lipid peroxidation and membrane damage in the microbe (Mehdy, 1994; Lamb and Dixon, 1997; Apel and Hirt, 2004; Montillet et al., 2005).ROS levels in the apoplast increase rapidly in response to a variety of pathogens, but subsequently return to basal levels. The rapid production and dissipation of apoplastic ROS indicate that this process is finely regulated. Two classes of enzymes, NADPH oxidases and class III peroxidases, account for the rapid ROS burst in the apoplast (Bolwell et al., 1995; O’Brien et al., 2012). NADPH oxidases are directly phosphorylated by the receptor-like kinase BIK1 to enhance ROS generation (Li et al., 2014b). Also, due to the toxicity of high levels of ROS, plants have evolved enzymatic and nonenzymatic mechanisms to eliminate ROS, thereby preventing or reducing oxidative damage (Rahal et al., 2014; Torres et al., 2006). However, the molecular system responsible for the regulation of apoplastic ROS homeostasis during the immune response is not well understood.In this study, we performed a comparative analysis of the apoplastic proteomes in control roots compared with V. dahliae-inoculated roots of Gossypium barbadense (wilt-resistant sea-island cotton) using the two-dimensional differential gel electrophoresis (2D-DIGE) technique. Among the differentially expressed apoplastic proteins, ROS-related proteins were found to be major components, including a thioredoxin, GbNRX1, which functions as an ROS scavenger in response to V. dahliae infection. Knock-down of GbNRX1 expression in cotton by virus-induced gene silencing (VIGS) resulted in reduced resistance to V. dahliae. Our results demonstrate that maintaining apoplastic ROS homeostasis is a crucial component of the apoplastic immune response and that GbNRX1 is an important regulator of this process.