The toxicity and bioaccumulation of selenite in four microalgae, Spirulina platensis, Dunaliella salina, Dunaliella bardawill and Phaeodactylum tricornutum cultured in the presence of selenite were investigated. Lower...The toxicity and bioaccumulation of selenite in four microalgae, Spirulina platensis, Dunaliella salina, Dunaliella bardawill and Phaeodactylum tricornutum cultured in the presence of selenite were investigated. Lower concentrations of selenite were generally nontoxic and frequently stimulated algal growth, while higher concentrations of selenite inhibited algal growth. Selenite was more toxic to D. salina and D. bardawill than to S. platensis and P. tricornutum . All algae cultured in selenite were able to incorporate Se to different degrees, which depended on algal species. The distributions of selenite among intracellular macromolecular compounds were different among algal species: most of the selenite was associated with proteins in S. platensis, D. salina and D. bardawill , while most of the selenite was associated with lipids in P. tricornutum , which reflected the physiological differences among the algae. These observations suggest that algae are able to accumulate selenite and bind it with intracellular macromolecular compounds when exposed to high concentration of selenite. This may represent a form of storage or detoxification of selenite by the algae.展开更多
Human endogenous retroviruses(HERVs) are retroviruses that infected human genome millions of years ago and have persisted throughout human evolution. About 8% of our genome is composed of HERVs, most of which are nonf...Human endogenous retroviruses(HERVs) are retroviruses that infected human genome millions of years ago and have persisted throughout human evolution. About 8% of our genome is composed of HERVs, most of which are nonfunctional because of epigenetic control or deactivating mutations. However, a correlation between HERVs and human cancer has been described and many tumors, such as melanoma, breast cancer, germ cell tumors, renal cancer or ovarian cancer, express HERV proteins, mainly HERV-K(HML6) and HERV-K(HML2). Although the causative role of HERVs in cancer is controversial, data from animal models demonstrated that endogenous retroviruses are potentially oncogenic. HERV protein expression in human cells generates an immune response by activating innate and adaptive immunities. Some HERV-derived peptides have antigenic properties. For example, HERV-K(HML-6) encodes the HER-K MEL peptide recognized by CD8+ lymphocytes. In addition, HERVs are twoedged immunomodulators. HERVs show immunosuppressive activity. The presence of genomic retroviral elements in host-cell cytosol may activate an interferon type I response. Therefore, targeting HERVs through cellular vaccines or immunomodulatory drugs combined with checkpoint inhibitors is attracting interest because they could be active in human tumors.展开更多
A substantial part of the human genome is derived from transposable elements;remnants of ancient retroviral infections.Conservative estimates set the percentage of human endogenous retroviruses(HERVs) in the genome at...A substantial part of the human genome is derived from transposable elements;remnants of ancient retroviral infections.Conservative estimates set the percentage of human endogenous retroviruses(HERVs) in the genome at 8%.For the most part,the interplay between mutations,epigenetic mechanisms and posttranscriptional regulations silence HERVs in somatic cells.We first highlight mechanisms by which activation of members of several HERV families may be associated with tumor development before discussing the arising chances for both diagnosis and therapy.It has been shown that at least in some cases,tumor cells expressing HERV open reading frames(ORFs) thus gain tumor-promoting functions.However,since these proteins are not expressed in healthy tissues,they become prime target structures.Of potential pharmacological interest are the prevention of HERV transposition,the inhibition of HERV-encoded protein expression and the interference with these proteins' activities.Evidence from recent studies unequivocally proves that HERV ORFs represent a very interesting source of novel tumor-specific antigens with even the potential to surpass entity boundaries.The development of new tumor(immune-) therapies is a very active field and true tumor-specific targets are of outstanding interest since they minimize the risk of autoimmunity and could reduce side effects.Finally,we postulate on main future research streams in order to stimulate discussion on this hot topic.展开更多
The relatively low susceptibility ofHelicoverpa armigera to CrylAc, its history of resistance to chemical insecticides and the seasonal decline in expression of CrylAc in transgenic cotton necessitated the development...The relatively low susceptibility ofHelicoverpa armigera to CrylAc, its history of resistance to chemical insecticides and the seasonal decline in expression of CrylAc in transgenic cotton necessitated the development of cotton expressing two insecticidal proteins to provide sustainable control of this multinational pest. To manage the resistance issue, it was essential that the second insecticidal protein have a significantly different mode of action to CrylAc. A common feature of resistance to CrylA proteins in several species as well as H. armigera has been a change in the binding site. A study of binding sites for some Cry proteins in the brush border membrane vesicles （BBMV） ofH. armigera and Helicoverpa punctigera was undertaken. The binding affinity for CrylAc was higher than for CrylAb, matching their relative toxicities, and CrylAc and CrylAb were found to share at least one binding site in both I-1. armigera and I-1. punctigera. However Cry2Aa did not compete with CrylAc for binding and so could be used in transgenic cotton in combination with CrylAc to control H. armigera and manage resistance. Variation in the susceptibilities of three different H. armigera strains to CrylAc correlated with the parameter Bmax/Kcom.展开更多
This paper demonstrates a new framework of vocabulary learning processes（VLPs） with fill/ justification of involved learning steps, in response to inefficient self-directed vocabulary learning（SDVL） of college stu...This paper demonstrates a new framework of vocabulary learning processes（VLPs） with fill/ justification of involved learning steps, in response to inefficient self-directed vocabulary learning（SDVL） of college students in China's Mainland. Based on the review of established frameworks for second language acquisition and vocabulary learning, a more systematic and comprehensive framework of VLPs is constructed with six new VLPs explored and specified sequentially in a cycle. It aims to help initiate learners＇ mental efforts in a rational way and thereby achieve learners＇ long-term word retention and good word transfer. Besides, the newly-designed VLPs are embodied in authentic learning material for learners＇ self-study of vocabulary in particular domains. The efficacy of the material is also tested in an empirical study for the purpose of validating the effectiveness of these VLPs.展开更多
文摘The toxicity and bioaccumulation of selenite in four microalgae, Spirulina platensis, Dunaliella salina, Dunaliella bardawill and Phaeodactylum tricornutum cultured in the presence of selenite were investigated. Lower concentrations of selenite were generally nontoxic and frequently stimulated algal growth, while higher concentrations of selenite inhibited algal growth. Selenite was more toxic to D. salina and D. bardawill than to S. platensis and P. tricornutum . All algae cultured in selenite were able to incorporate Se to different degrees, which depended on algal species. The distributions of selenite among intracellular macromolecular compounds were different among algal species: most of the selenite was associated with proteins in S. platensis, D. salina and D. bardawill , while most of the selenite was associated with lipids in P. tricornutum , which reflected the physiological differences among the algae. These observations suggest that algae are able to accumulate selenite and bind it with intracellular macromolecular compounds when exposed to high concentration of selenite. This may represent a form of storage or detoxification of selenite by the algae.
文摘Human endogenous retroviruses(HERVs) are retroviruses that infected human genome millions of years ago and have persisted throughout human evolution. About 8% of our genome is composed of HERVs, most of which are nonfunctional because of epigenetic control or deactivating mutations. However, a correlation between HERVs and human cancer has been described and many tumors, such as melanoma, breast cancer, germ cell tumors, renal cancer or ovarian cancer, express HERV proteins, mainly HERV-K(HML6) and HERV-K(HML2). Although the causative role of HERVs in cancer is controversial, data from animal models demonstrated that endogenous retroviruses are potentially oncogenic. HERV protein expression in human cells generates an immune response by activating innate and adaptive immunities. Some HERV-derived peptides have antigenic properties. For example, HERV-K(HML-6) encodes the HER-K MEL peptide recognized by CD8+ lymphocytes. In addition, HERVs are twoedged immunomodulators. HERVs show immunosuppressive activity. The presence of genomic retroviral elements in host-cell cytosol may activate an interferon type I response. Therefore, targeting HERVs through cellular vaccines or immunomodulatory drugs combined with checkpoint inhibitors is attracting interest because they could be active in human tumors.
基金Supported by Grants from the State Mecklenburg-Vorpommern and from Deutsche Krebshilfe,No.108446
文摘A substantial part of the human genome is derived from transposable elements;remnants of ancient retroviral infections.Conservative estimates set the percentage of human endogenous retroviruses(HERVs) in the genome at 8%.For the most part,the interplay between mutations,epigenetic mechanisms and posttranscriptional regulations silence HERVs in somatic cells.We first highlight mechanisms by which activation of members of several HERV families may be associated with tumor development before discussing the arising chances for both diagnosis and therapy.It has been shown that at least in some cases,tumor cells expressing HERV open reading frames(ORFs) thus gain tumor-promoting functions.However,since these proteins are not expressed in healthy tissues,they become prime target structures.Of potential pharmacological interest are the prevention of HERV transposition,the inhibition of HERV-encoded protein expression and the interference with these proteins' activities.Evidence from recent studies unequivocally proves that HERV ORFs represent a very interesting source of novel tumor-specific antigens with even the potential to surpass entity boundaries.The development of new tumor(immune-) therapies is a very active field and true tumor-specific targets are of outstanding interest since they minimize the risk of autoimmunity and could reduce side effects.Finally,we postulate on main future research streams in order to stimulate discussion on this hot topic.
文摘The relatively low susceptibility ofHelicoverpa armigera to CrylAc, its history of resistance to chemical insecticides and the seasonal decline in expression of CrylAc in transgenic cotton necessitated the development of cotton expressing two insecticidal proteins to provide sustainable control of this multinational pest. To manage the resistance issue, it was essential that the second insecticidal protein have a significantly different mode of action to CrylAc. A common feature of resistance to CrylA proteins in several species as well as H. armigera has been a change in the binding site. A study of binding sites for some Cry proteins in the brush border membrane vesicles （BBMV） ofH. armigera and Helicoverpa punctigera was undertaken. The binding affinity for CrylAc was higher than for CrylAb, matching their relative toxicities, and CrylAc and CrylAb were found to share at least one binding site in both I-1. armigera and I-1. punctigera. However Cry2Aa did not compete with CrylAc for binding and so could be used in transgenic cotton in combination with CrylAc to control H. armigera and manage resistance. Variation in the susceptibilities of three different H. armigera strains to CrylAc correlated with the parameter Bmax/Kcom.
文摘This paper demonstrates a new framework of vocabulary learning processes（VLPs） with fill/ justification of involved learning steps, in response to inefficient self-directed vocabulary learning（SDVL） of college students in China's Mainland. Based on the review of established frameworks for second language acquisition and vocabulary learning, a more systematic and comprehensive framework of VLPs is constructed with six new VLPs explored and specified sequentially in a cycle. It aims to help initiate learners＇ mental efforts in a rational way and thereby achieve learners＇ long-term word retention and good word transfer. Besides, the newly-designed VLPs are embodied in authentic learning material for learners＇ self-study of vocabulary in particular domains. The efficacy of the material is also tested in an empirical study for the purpose of validating the effectiveness of these VLPs.
