Remarkable progress has occurred in many branches of biology and health sciences during the last few decades. Trace element (TE) research has definitely shared in this explosion of scientific knowledge. Due to the imp...Remarkable progress has occurred in many branches of biology and health sciences during the last few decades. Trace element (TE) research has definitely shared in this explosion of scientific knowledge. Due to the improvements in analytical technology, the discovery of TEs in organism was realized. The developments of TE research have been promoted by the demand of public health (e.g. deficiency or toxicity). The profound knowledge of nutritional importance of TEs has been achieved with application of advanced methods in biological, medical and chemical fields, etc. In this paper, a new definition of essentiality of TEs is introduced. According to this definition, onIy ten TEs (Fe, Zn, F, Cu, I, Se, Mn, Mo, Cr, Co) are considered to be essential to humans. The others need more evidence to prove their essentiality in humans. The recent progress on the biochemical and immunological functions of TEs and on the roles of TEs in brain development are briefly described. The TEs, mainly Se, I, Zn, Fe, are more closely related to public health. Also, emphases are laid on balancing all nutrients when new knowledge of essential TEs is applied in public health展开更多
Selenium has been recognized as an essential nutrient in animals since the 1950s. Demonstration of the role of dietary selenium in protection from oxidative stress foIlowed in the early 1970s, and was largely attribut...Selenium has been recognized as an essential nutrient in animals since the 1950s. Demonstration of the role of dietary selenium in protection from oxidative stress foIlowed in the early 1970s, and was largely attributed to its presence as an integral part of cellular glutathione peroxidase. However, the functions of this enzyme did not explain many of the other effects of selenium deficiency. The identification of other mammalian selenoproteins during the last few years has provided new insights into the functions of this trace nutrient. The discovery that type 1 deiodinase (D1) is a selenoenzyme, in addition to unveiling an essential role for selenium in thyroid hormone action, has had more far-reaching implications. Studies of this protein opened the door for investigation of the requirements for eukaryotic selenoprotein synthesis,and the features that distinguish this pathway from the corresponding prokaryotic pathway.Selenium is present in a number of prokaryotic and eukaryotic proteins in the form of the unusual amino acid, selenocysteine. Incorporation of selenocysteine into these proteins requires a novel translation step in which UGA specifies selenocysteine insertion. Since UGA codons are typically recognized as translation stop signals, an intriguing question is raised: How does a cell recognize and distinguish a UGA selenocysteine codon from a UGA stop codon? In this review, we will focus on what is known about selenocysteine incorporation in eukaryotes, briefly summarizing initial studies and discussing a few recent advances in our understanding of this unique 'recoding' process展开更多
文摘Remarkable progress has occurred in many branches of biology and health sciences during the last few decades. Trace element (TE) research has definitely shared in this explosion of scientific knowledge. Due to the improvements in analytical technology, the discovery of TEs in organism was realized. The developments of TE research have been promoted by the demand of public health (e.g. deficiency or toxicity). The profound knowledge of nutritional importance of TEs has been achieved with application of advanced methods in biological, medical and chemical fields, etc. In this paper, a new definition of essentiality of TEs is introduced. According to this definition, onIy ten TEs (Fe, Zn, F, Cu, I, Se, Mn, Mo, Cr, Co) are considered to be essential to humans. The others need more evidence to prove their essentiality in humans. The recent progress on the biochemical and immunological functions of TEs and on the roles of TEs in brain development are briefly described. The TEs, mainly Se, I, Zn, Fe, are more closely related to public health. Also, emphases are laid on balancing all nutrients when new knowledge of essential TEs is applied in public health
文摘Selenium has been recognized as an essential nutrient in animals since the 1950s. Demonstration of the role of dietary selenium in protection from oxidative stress foIlowed in the early 1970s, and was largely attributed to its presence as an integral part of cellular glutathione peroxidase. However, the functions of this enzyme did not explain many of the other effects of selenium deficiency. The identification of other mammalian selenoproteins during the last few years has provided new insights into the functions of this trace nutrient. The discovery that type 1 deiodinase (D1) is a selenoenzyme, in addition to unveiling an essential role for selenium in thyroid hormone action, has had more far-reaching implications. Studies of this protein opened the door for investigation of the requirements for eukaryotic selenoprotein synthesis,and the features that distinguish this pathway from the corresponding prokaryotic pathway.Selenium is present in a number of prokaryotic and eukaryotic proteins in the form of the unusual amino acid, selenocysteine. Incorporation of selenocysteine into these proteins requires a novel translation step in which UGA specifies selenocysteine insertion. Since UGA codons are typically recognized as translation stop signals, an intriguing question is raised: How does a cell recognize and distinguish a UGA selenocysteine codon from a UGA stop codon? In this review, we will focus on what is known about selenocysteine incorporation in eukaryotes, briefly summarizing initial studies and discussing a few recent advances in our understanding of this unique 'recoding' process
