耳聋是最常见的严重影响言语交流的残疾之一,每年至少有一半的新生聋儿是由于遗传缺陷引起的。引起耳聋的致病基因和突变种类众多,其中,基因拷贝数变异(Copy Number Variations,CNVs)被确认为是广泛存在于人类基因组DNA的重要变异形式,...耳聋是最常见的严重影响言语交流的残疾之一,每年至少有一半的新生聋儿是由于遗传缺陷引起的。引起耳聋的致病基因和突变种类众多,其中,基因拷贝数变异(Copy Number Variations,CNVs)被确认为是广泛存在于人类基因组DNA的重要变异形式,并且可以通过干扰基因表达来调控表型,是影响人类某些疾病的重要因素,其在遗传性耳聋致病机制中也起到重要作用。随着基因组测序技术的飞速发展,越来越多的致病性CNVs被发现、鉴定及定位。本文就目前CNVs与遗传性耳聋的关系研究作一综述,详细阐述CNVs在遗传性耳聋分子诊断中的重要作用。展开更多
Mercury(Hg) is a toxic heavy metal with its biogeochemical cycling in the ocean depending on the type and behavior of the oceanic microalgae.The present work aimed to evaluate bioaccumulation and transformation of Hg ...Mercury(Hg) is a toxic heavy metal with its biogeochemical cycling in the ocean depending on the type and behavior of the oceanic microalgae.The present work aimed to evaluate bioaccumulation and transformation of Hg by Phaeodactylum tricornutum,a typical unicellular diatom,when exposed to the extremely high level of Hg in order to understand the possible mechanisms of acute stress response.P.tricornutum can accumulate Hg(its bioaccumulation factor is at 104 level),and the 96 h EC 50 was estimated to be 145μg L-1.The amounts of surface-bound Hg being about 1.2 to 4.8 times higher than those of intracellular Hg under exposure to HgCl 2(from 20 to 120μg L-1 concentrations) suggested that the cell wall of P.tricornutum is an important "fence" towards Hg.After entering the P.tricornutum cell,Hg underwent transformation in its chemical form via interactions with high molecular weight sulfur-containing proteins(accounting for 68% of the intracellular Hg),and glutathione as well as the induced phytochelatins(PCs)(24% Hg) which alleviated the toxicity of HgCl2.In addition,the existence of organic ligands greatly influenced the uptake and transformation behavior of P.tricornutum towards HgCl2,especially in the case of cysteine(Cys),which increased the uptake of Hg,but alleviated the toxicity of Hg towards P.tricornutum due to the fact that Cys is an important precursor for the synthesis of PCs inside the cell.The uptake process of Hg by P.tricornutum was in agreement with the Freundlich isotherm,suggesting a typical heterogeneous sorption process.More importantly,we observed the conversion of HgCl2 into methylmercury inside the P.tricornutum cells and its release into the culture solution using HPLC/CVG-AFS and GC-MS,although the mechanism needs to be further investigated.展开更多
Brassica chinensis L. was chosen and exposed to different concentrations of Cd exposure to evaluate its Cd-accumulating capacity and its potential cellular defensive mechanisms. Cd accumulation in the shoots and roots...Brassica chinensis L. was chosen and exposed to different concentrations of Cd exposure to evaluate its Cd-accumulating capacity and its potential cellular defensive mechanisms. Cd accumulation in the shoots and roots of B. chinensis was up to 1348.3±461.8 and 3761.0±795.0 mg per killogram of dry weight, respectively, under 200 μmol/L of Cd exposure. Increasing Cd accumulation in the plant was accompanied by rapid accumulation of phytochelatins (PCs), and the sequestration of Cd by PCs provided a primary cellular mechanism for Cd detoxification and tolerance of B. chinensis. Furthermore, malondialdehyde formation, hydrogen peroxide content and antioxidative enzyme activities such as superoxide dismutase, catalase, guaiacol peroxidase and ascorbate peroxidase were observed in the shoots of Cd-stressed B. chinensis. Increasing enzyme activities in response to concentrations of 5 to 50 μmol/L Cd showed an efficient defense against oxidative stress, suggesting that the antioxidative system was a secondary defensive mechanism. These resulted in reduced free Cd damage and enhanced Cd accumulation and tolerance. Glutathione plays a pivotal role in these two detoxification pathways. In general, these results suggested that PCs and the antioxidative system are synergistic in combatting Cd-induced oxidative stress and that they play important roles in Cd detoxification of B. chinensis, and also give a deep understanding of the natural defensive mechanisms in plants under heavy metal stress.展开更多
The effects of lanthanum at different concen-trations on the related photosynthetic activities of Hill reac-tion, Mg2+-ATPase and Ca2+-ATPase in spinach chloroplast were studied. Experimental results showed that lanth...The effects of lanthanum at different concen-trations on the related photosynthetic activities of Hill reac-tion, Mg2+-ATPase and Ca2+-ATPase in spinach chloroplast were studied. Experimental results showed that lanthanum can increase all the activities at suitable concentration (15-30 mg·L-1), however, it behaves toxically on them when over used (60 mg·L-1). To get an improved understanding of the mechanism of lanthanum effects on the photosynthesis of spinach, the different subcomponents in the chloroplast of the cultured spinach were isolated, and the content of lan-thanum in each subcomponent was determined by ICP-MS. The results obtained indicated that among these different subcomponents, about 90% out of the total chloroplast lan-thanum was located in photosystem II (PS II) while there was little lanthanum in photosystem I (PS I). Moreover, size ex-clusion high performance liquid chromatography (SE-HPLC) coupled with online UV and ICP-MS detections was novelly used for locating lanthanum binding sites in PS II proteins for the first time. It was found that lanthanum has two bind-ing sites in PS II: La associates with chlorophyll together with magnesium in PS II by partly replacing magnesium and also shares the common binding sites of PS II proteins to-gether with the inorganic cofactors of calcium and manga-nese, influencing the process of photosynthesis.展开更多
In this paper,we report the bioaccumulation and transformation of cadmium (Cd) by Phaeodactylum tricornutum in the presence of ethylenediamine tetra acetic acid (EDTA) and cysteine (Cys). Both EDTA and Cys can allevia...In this paper,we report the bioaccumulation and transformation of cadmium (Cd) by Phaeodactylum tricornutum in the presence of ethylenediamine tetra acetic acid (EDTA) and cysteine (Cys). Both EDTA and Cys can alleviate the toxicity of Cd to P. tricornutum. Short term intracellular uptake and extracellular adsorption experiments using ICP-MS indicated that the amounts of Cd accumulated on the cell surface of P. tricornutum and inside the cell decreased along with the increase of EDTA concentration,which conformed to the prediction of the Free Ion Activity Model (FIAM). However,extracellular adsorption of Cd increased at first and then decreased along with the increase in the concentration of Cys,while intracellular uptake increased under Cys concentrations from the blank value to 4.45 μmol/L,and then tended to remain at the same level when the Cys concentration was greater than 4.45 μmol/L,and this deviated remarkably from the FIAM. The interactions of Cd with _Si_OH,_C_OH and NH2(CO) _OH on the cell wall were confirmed using FT-IR and XPS studies. The results obtained using HPLC of the phytochelatins (PCs) produced by P. tricornutum under CdCl2,Cd_EDTA and Cd_Cys stress suggested that the main reason for the different effects of EDTA and Cys on the bioaccumulation and transformation of Cd by P. tricornutum was that Cys is not only a complexing ligand to Cd,as is EDTA,but also it is a precursor of the intracellular synthesizing PCs participating in the cellular defense mechanism against Cd. Furthermore,the discovery of in vivo PCs and oxidized_PCs as well as Cd-PC2 in P. tricornutum using ESI-IT-MS provided the evidence for deactivation of Cd by the PCs,reducing Cd-toxicity to P. tricornutum.展开更多
文摘耳聋是最常见的严重影响言语交流的残疾之一,每年至少有一半的新生聋儿是由于遗传缺陷引起的。引起耳聋的致病基因和突变种类众多,其中,基因拷贝数变异(Copy Number Variations,CNVs)被确认为是广泛存在于人类基因组DNA的重要变异形式,并且可以通过干扰基因表达来调控表型,是影响人类某些疾病的重要因素,其在遗传性耳聋致病机制中也起到重要作用。随着基因组测序技术的飞速发展,越来越多的致病性CNVs被发现、鉴定及定位。本文就目前CNVs与遗传性耳聋的关系研究作一综述,详细阐述CNVs在遗传性耳聋分子诊断中的重要作用。
基金supported by the National Basic Research Program of China (2009CB421605)the National Natural Science Foundation of China (21035006)
文摘Mercury(Hg) is a toxic heavy metal with its biogeochemical cycling in the ocean depending on the type and behavior of the oceanic microalgae.The present work aimed to evaluate bioaccumulation and transformation of Hg by Phaeodactylum tricornutum,a typical unicellular diatom,when exposed to the extremely high level of Hg in order to understand the possible mechanisms of acute stress response.P.tricornutum can accumulate Hg(its bioaccumulation factor is at 104 level),and the 96 h EC 50 was estimated to be 145μg L-1.The amounts of surface-bound Hg being about 1.2 to 4.8 times higher than those of intracellular Hg under exposure to HgCl 2(from 20 to 120μg L-1 concentrations) suggested that the cell wall of P.tricornutum is an important "fence" towards Hg.After entering the P.tricornutum cell,Hg underwent transformation in its chemical form via interactions with high molecular weight sulfur-containing proteins(accounting for 68% of the intracellular Hg),and glutathione as well as the induced phytochelatins(PCs)(24% Hg) which alleviated the toxicity of HgCl2.In addition,the existence of organic ligands greatly influenced the uptake and transformation behavior of P.tricornutum towards HgCl2,especially in the case of cysteine(Cys),which increased the uptake of Hg,but alleviated the toxicity of Hg towards P.tricornutum due to the fact that Cys is an important precursor for the synthesis of PCs inside the cell.The uptake process of Hg by P.tricornutum was in agreement with the Freundlich isotherm,suggesting a typical heterogeneous sorption process.More importantly,we observed the conversion of HgCl2 into methylmercury inside the P.tricornutum cells and its release into the culture solution using HPLC/CVG-AFS and GC-MS,although the mechanism needs to be further investigated.
基金the National Natural Science Foundation of China (Grant Nos. 20535020, 20475046 and 20775062)the National "863" Hi-Tech Project of China (Grant No. 2006AA06Z404)the National Basic Research Program of China (Grant No. 2003CD415001)
文摘Brassica chinensis L. was chosen and exposed to different concentrations of Cd exposure to evaluate its Cd-accumulating capacity and its potential cellular defensive mechanisms. Cd accumulation in the shoots and roots of B. chinensis was up to 1348.3±461.8 and 3761.0±795.0 mg per killogram of dry weight, respectively, under 200 μmol/L of Cd exposure. Increasing Cd accumulation in the plant was accompanied by rapid accumulation of phytochelatins (PCs), and the sequestration of Cd by PCs provided a primary cellular mechanism for Cd detoxification and tolerance of B. chinensis. Furthermore, malondialdehyde formation, hydrogen peroxide content and antioxidative enzyme activities such as superoxide dismutase, catalase, guaiacol peroxidase and ascorbate peroxidase were observed in the shoots of Cd-stressed B. chinensis. Increasing enzyme activities in response to concentrations of 5 to 50 μmol/L Cd showed an efficient defense against oxidative stress, suggesting that the antioxidative system was a secondary defensive mechanism. These resulted in reduced free Cd damage and enhanced Cd accumulation and tolerance. Glutathione plays a pivotal role in these two detoxification pathways. In general, these results suggested that PCs and the antioxidative system are synergistic in combatting Cd-induced oxidative stress and that they play important roles in Cd detoxification of B. chinensis, and also give a deep understanding of the natural defensive mechanisms in plants under heavy metal stress.
文摘The effects of lanthanum at different concen-trations on the related photosynthetic activities of Hill reac-tion, Mg2+-ATPase and Ca2+-ATPase in spinach chloroplast were studied. Experimental results showed that lanthanum can increase all the activities at suitable concentration (15-30 mg·L-1), however, it behaves toxically on them when over used (60 mg·L-1). To get an improved understanding of the mechanism of lanthanum effects on the photosynthesis of spinach, the different subcomponents in the chloroplast of the cultured spinach were isolated, and the content of lan-thanum in each subcomponent was determined by ICP-MS. The results obtained indicated that among these different subcomponents, about 90% out of the total chloroplast lan-thanum was located in photosystem II (PS II) while there was little lanthanum in photosystem I (PS I). Moreover, size ex-clusion high performance liquid chromatography (SE-HPLC) coupled with online UV and ICP-MS detections was novelly used for locating lanthanum binding sites in PS II proteins for the first time. It was found that lanthanum has two bind-ing sites in PS II: La associates with chlorophyll together with magnesium in PS II by partly replacing magnesium and also shares the common binding sites of PS II proteins to-gether with the inorganic cofactors of calcium and manga-nese, influencing the process of photosynthesis.
文摘In this paper,we report the bioaccumulation and transformation of cadmium (Cd) by Phaeodactylum tricornutum in the presence of ethylenediamine tetra acetic acid (EDTA) and cysteine (Cys). Both EDTA and Cys can alleviate the toxicity of Cd to P. tricornutum. Short term intracellular uptake and extracellular adsorption experiments using ICP-MS indicated that the amounts of Cd accumulated on the cell surface of P. tricornutum and inside the cell decreased along with the increase of EDTA concentration,which conformed to the prediction of the Free Ion Activity Model (FIAM). However,extracellular adsorption of Cd increased at first and then decreased along with the increase in the concentration of Cys,while intracellular uptake increased under Cys concentrations from the blank value to 4.45 μmol/L,and then tended to remain at the same level when the Cys concentration was greater than 4.45 μmol/L,and this deviated remarkably from the FIAM. The interactions of Cd with _Si_OH,_C_OH and NH2(CO) _OH on the cell wall were confirmed using FT-IR and XPS studies. The results obtained using HPLC of the phytochelatins (PCs) produced by P. tricornutum under CdCl2,Cd_EDTA and Cd_Cys stress suggested that the main reason for the different effects of EDTA and Cys on the bioaccumulation and transformation of Cd by P. tricornutum was that Cys is not only a complexing ligand to Cd,as is EDTA,but also it is a precursor of the intracellular synthesizing PCs participating in the cellular defense mechanism against Cd. Furthermore,the discovery of in vivo PCs and oxidized_PCs as well as Cd-PC2 in P. tricornutum using ESI-IT-MS provided the evidence for deactivation of Cd by the PCs,reducing Cd-toxicity to P. tricornutum.
