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بروس لي : أسطورة الشرق الخالدة /
أسطورة الشرق الخالدة، التنين الصيني، علامة الووشو، مؤسس الجيت كون دو، معلم الفنون القتالية الأشهر في التاريخ، كلها ألقاب حظي بها الرجل الأشهر في الفنون القتالية في تاريخنا المعاصر \"لي تشن فان\" وهو الاسم الأصلي للتنين الصيني \"بروس لي\". يرتبط اسم بروس لي بالأساطير القتالية التي لا تزال يتناقلها الصغار والشباب المهتمون بفنون القتال، ذلك المصارع ذو الأصول الصينية المولود بالولايات المتحدة. تلك الأساطير التي ارتبطت بمولده ونشأته، وتعلمه فنون رياضتي الووشو والكونغ فو، تأسيسه لرياضة الجيت كون دو \"القبضة المعارضة\". حياته الشخصية، أساليبه القتالية الفريدة، أدواره السينمائية التي حققت أعلى الإيرادات في السينما الأمريكية في ذلك الوقت، مقولاته الشهيرة التي ألهمت الكثيرين، أسرار وفاته الغامضة، كل ذلك من أسرار يكشفها لنا المؤلف الصيني لهذا الكتاب تشنغ جيه الباحث المخضرم في كل ما يتعلق بيروس لي والذي أجرى تحليلا شاملا لكم ضخم من المعلومات الرسمية والموثوقة عن بروس لي، وبدأ منذ عام 2013 في كتابة قصة حياة بروس لي التي نعرض لها في هذا الكتاب والتي تضم الكثير من الوثائق المعلومات التي تنشر للمرة الأولى، ويرى مؤلف هذا الكتاب أن قصة حياة بروس لي التي يعرضها هذا الكتاب ليست محتوى أدبيا أو فكريا : ولكنها أقرب ما تكون إلى الحقيقة. كل هذا وأكثر، حول أسطورة الشرق الخالدة بروس لي. بين دفتي هذا الكتاب.
Book
Heavy metal ATPase 3 (HMA3) confers cadmium hypertolerance on the cadmium/zinc hyperaccumulator Sedum plumbizincicola
Cadmium (Cd) is highly toxic to most organisms, but some rare plant species can hyperaccumulate Cd in aboveground tissues without suffering from toxicity. The mechanism underlying Cd detoxification by hyperaccumulators is interesting but unclear.
Here, the heavy metal ATPase 3 (SpHMA3) gene responsible for Cd detoxification was isolated from the Cd/zinc (Zn) hyperaccumulator Sedum plumbizincicola. RNA interference (RNAi)-mediated silencing and overexpression of SpHMA3 were induced to investigate its physiological functions in S. plumbizincicola and a nonhyperaccumulating ecotype of Sedum alfredii.
Heterologous expression of SpHMA3 in Saccharomyces cerevisiae showed Cd-specific transport activity. SpHMA3 was highly expressed in the shoots and the protein was localized to the tonoplast. The SpHMA3-RNAi lines were hypersensitive to Cd but not to Zn, with the growth of shoots and young leaves being severely inhibited by Cd. Overexpressing SpHMA3 in the nonhyperaccumulating ecotype of S. alfredii greatly increased its tolerance to and accumulation of Cd, but not Zn.
These results indicate that elevated expression of the tonoplast-localized SpHMA3 in the shoots plays an essential role in Cd detoxification, which contributes to the maintenance of the normal growth of young leaves of S. plumbizincicola in Cd-contaminated soils.
Journal Article
Arsenic and cadmium accumulation in rice and mitigation strategies
Background
Arsenic (As) and cadmium (Cd) are two toxic elements that have a relatively high risk of transfer from paddy soil to rice grain. Rice is a major dietary source of these two elements for populations consuming rice as a staple food. Reducing their accumulation in rice grain is important for food safety and human health.
Scope
We review recent progress in understanding the biogeochemical processes controlling As and Cd bioavailability in paddy soil, the mechanisms of their uptake, translocation and detoxification in rice plants, and strategies to reduce their accumulation in rice grain. Similarities and differences between the two elements are emphasized. Some knowledge gaps are also identified.
Conclusions
The concentrations of As and Cd in rice grain vary by three orders of magnitude, depending on the bioavailability of the two elements in soil, rice genotype and growing conditions. The redox potential in paddy soil has a profound but opposite effect on As and Cd bioavailability, whereas soil pH affects Cd bioavailability more than As bioavailability. A number of key genes involved in As and Cd uptake, translocation, sequestration, and detoxification in rice have been characterized. Allelic variations of several genes underlying the variations in Cd accumulation have been identified, but more remains to be elucidated, especially for As. Two types of strategies can be used to reduce As and Cd accumulation, reducing their bioavailability in soil or their uptake and translocation in rice. Reducing the accumulation of both As and Cd in rice simultaneously remains a great challenge.
Journal Article
OsHAC4 is critical for arsenate tolerance and regulates arsenic accumulation in rice
Soil contamination with arsenic (As) can cause phytotoxicity and elevated As accumulation in rice grain. Here, we used a forward genetics approach to investigate the mechanism of arsenate (As(V)) tolerance and accumulation in rice.
A rice mutant hypersensitive to As(V), but not to As(III), was isolated. Genomic resequencing and complementation tests were used to identify the causal gene. The function of the gene, its expression pattern and subcellular localization were characterized.
OsHAC4 is the causal gene for the As(V)-hypersensitive phenotype. The gene encodes a rhodanase-like protein that shows As(V) reductase activity when expressed in Escherichia coli. OsHAC4 was highly expressed in roots and was induced by As(V). In OsHAC4pro-GUS transgenic plants, the gene was expressed exclusively in the root epidermis and exodermis. OsHAC4-eGFP was localized in the cytoplasm and the nucleus. Mutation in OsHAC4 resulted in decreased As(V) reduction in roots, decreased As(III) efflux to the external medium and markedly increased As accumulation in rice shoots. Overexpression of OsHAC4 increased As (V) tolerance and decreased As accumulation in rice plants.
OsHAC4 is an As(V) reductase that is critical for As(V) detoxification and for the control of As accumulation in rice. As(V) reduction, followed by As(III) efflux, is an important mechanism of As(V) detoxification.
Journal Article
Decreasing arsenic accumulation in rice by overexpressing OsNIP1;1 and OsNIP3;3 through disrupting arsenite radial transport in roots
Rice is a major dietary source of the toxic metalloid arsenic. Reducing arsenic accumulation in rice grain is important for food safety.
We generated transgenic rice overexpressing two aquaporin genes, OsNIP1;1 and OsNIP3;3, under the control of a maize ubiquitin promoter or the rice OsLsi1 promoter, and tested the effect on arsenite uptake and translocation.
OsNIP1;1 and OsNIP3;3 were highly permeable to arsenite in Xenopus oocyte assays. Both transporters were localized at the plasma membrane. Knockout of either gene had little effect on arsenite uptake or translocation. Overexpression of OsNIP1;1 or OsNIP3;3 in rice did not affect arsenite uptake but decreased root-to-shoot translocation of arsenite and shoot arsenic concentration markedly. The overexpressed OsNIP1;1 and OsNIP3;3 proteins were localized in all root cells without polarity. Expression of OsNIP1;1 driven by the OsLsi1 promoter produced similar effects. When grown in two arsenic-contaminated paddy soils, overexpressing lines contained significantly lower arsenic concentration in rice grain than the wild-type without compromising plant growth or the accumulation of essential nutrients.
Overexpression of OsNIP1;1 or OsNIP3;3 provides a route for arsenite to leak out of the stele, thus restricting arsenite loading into the xylem. This strategy is effective in reducing arsenic accumulation in rice grain.
Journal Article
Mutation in OsCADT1 enhances cadmium tolerance and enriches selenium in rice grain
• How cadmium (Cd) tolerance in rice is regulated remains poorly understood. We used a forward genetic approach to investigate Cd tolerance in rice.
• Using a root elongation assay, we isolated a rice mutant with enhanced Cd tolerance, cadt1, from an ethyl methanesulphonate (EMS)-mutagenized population of a widely grown Indica cultivar. The mutant accumulated more Cd in roots but not in shoots and grains. Using genomic resequencing and complementation, we identified OsCADT1 as the causal gene for the mutant phenotype, which encodes a putative serine hydroxymethyltransferase.
• OsCADT1 protein was localized to the nucleus and the OsCADT1 gene was expressed in both roots and shoots. OsCADT1 mutation resulted in higher sulphur and selenium accumulation in the shoots and grains. Selenate influx in cadt1 was 2.4 times that of the wild-type. The mutant showed higher expression of the sulphate/selenate transporter gene OsSULTR1;1 and the sulphur-deficiency-inducible gene OsSDI1. Thiol compounds including cysteine, glutathione and phytochelatins were significantly increased in the mutant, underlying its increased Cd tolerance. Growth and grain biomass were little affected.
• The results suggest that OsCADT1 acts as a negative regulator of sulphate/selenate uptake and assimilation. OsCADT1 mutation increases Cd tolerance and enriches selenium in rice grains, providing a novel solution for selenium biofortification.
Journal Article
A molecular switch in sulfur metabolism to reduce arsenic and enrich selenium in rice grain
Rice grains typically contain high levels of toxic arsenic but low levels of the essential micronutrient selenium. Anthropogenic arsenic contamination of paddy soils exacerbates arsenic toxicity in rice crops resulting in substantial yield losses. Here, we report the identification of the gain-of-function
arsenite tolerant 1
(
astol1
) mutant of rice that benefits from enhanced sulfur and selenium assimilation, arsenic tolerance, and decreased arsenic accumulation in grains. The
astol1
mutation promotes the physical interaction of the chloroplast-localized
O
-acetylserine (thiol) lyase protein with its interaction partner serine-acetyltransferase in the cysteine synthase complex. Activation of the serine-acetyltransferase in this complex promotes the uptake of sulfate and selenium and enhances the production of cysteine, glutathione, and phytochelatins, resulting in increased tolerance and decreased translocation of arsenic to grains. Our findings uncover the pivotal sensing-function of the cysteine synthase complex in plastids for optimizing stress resilience and grain quality by regulating a fundamental macronutrient assimilation pathway.
Contamination of paddy soils can lead to toxic arsenic accumulation in rice grains and low levels of the micronutrient selenium. Here the authors show that a gain of function mutant affecting an
O
-acetylserine (thiol) lyase enhances sulfur and selenium assimilation while reducing arsenic accumulation in grains.
Journal Article
The acceptance, readiness, affordances, and challenges of mobile-assisted language learning: A systematic literature review
Although mobile technologies are commonly used to support language learning, there is a lack of research to comprehensively determine the acceptance, readiness, affordances, and challenges in this area. To address this gap, this systematic literature review selected 49 articles indexed in the Scopus database between 2013 and 2022. This study found that TAM and UTAUT are the two most used models to examine the acceptance and readiness of MALL users. Besides, respondents generally have a positive acceptance and readiness for MALL, and they have sufficient knowledge and experience with MALL. This research classified three categories of the affordances of MALL, namely technology-based affordances which are related to the variety and application of mobile apps and the enhancing features of multimedia, the functional affordances of MALL which are related to the dynamic and flexible learning environments and the accessibility of mobile devices, and various aspects of language learning-based affordances. Regarding the challenges of MALL, this study has found that infrastructural and technological challenges, e.g. the insufficient ownership and accessibility of mobile devices, the limitations of mobile devices, the shortcomings of user interface and the instructional design of mobile apps, user-related issues, e.g., lack of technical and language skills, and application concerns, e.g. pedagogical concerns, health, privacy, and security concerns, and other real-world application concern could affect respondents’ acceptance and readiness of MALL. Both practical and theoretical implications are highlighted in this research.
Journal Article