Since the discovery of blood circulation and transfusion, there has been an insatiable demand for voluntary blood donations throughout the world. However, gathering blood donors has never been easy because eligible do...Since the discovery of blood circulation and transfusion, there has been an insatiable demand for voluntary blood donations throughout the world. However, gathering blood donors has never been easy because eligible donors constitute only a fraction of the general population and are often reluctant to donate. This is especially challenging in underprivileged countries of sub-Saharan Africa such as Malawi whose nationally run blood transfusion service struggles to maintain hospital blood banks. As a result, hospitals turn to their local communities for directed donations. A retrospective analysis from January 2014 to June 2016 of directed blood donor data from two hospitals in the Kasungu District of Malawi was conducted. The analysis of 2134 donations was carried out with respect to sex, age, hemoglobin concentration, blood group, and presence of transfusion-transmissible infections. On average, donors were 30 years of age and predominately male. Blood group O+ constituted more than half of all directed blood donations. Ultimately, about one third of donations were unable to be utilized for transfusion.展开更多
Plants possess both types of endosymbiotic organelles, chloroplasts and mitochondria. Transit peptides and presequences function as signal sequences for specific import into chloroplasts and mitochondria, respectively...Plants possess both types of endosymbiotic organelles, chloroplasts and mitochondria. Transit peptides and presequences function as signal sequences for specific import into chloroplasts and mitochondria, respectively. However, how these highly similar signal sequences confer the protein import specificity remains elusive. Here, we show that mitochondrial- or chloroplast-specific import involves two distinct steps, specificity determination and translocation across envelopes, which are mediated by the N-terminal regions and functionally interchangeable C-terminal regions, respectively, of transit peptides and presequences. A domain harboring multiple-arginine and hydrophobic sequence motifs in the N-terminal regions of presequences was identified as the mitochondrial specificity factor. The presence of this domain and the absence of arginine residues in the N-terminal regions of otherwise common targeting signals confers specificity of protein import into mitochondria and chloroplasts, respectively. AtToc159, a chloroplast import receptor, also contributes to determining chloroplast import specificity. We propose that common ancestral sequences were functionalized into mitochondrial- and chloroplast-specific signal sequences by the presence and absence, respectively, of multiple-arginine and hydrophobic sequence motifs in the N-terminal region.展开更多
文摘Since the discovery of blood circulation and transfusion, there has been an insatiable demand for voluntary blood donations throughout the world. However, gathering blood donors has never been easy because eligible donors constitute only a fraction of the general population and are often reluctant to donate. This is especially challenging in underprivileged countries of sub-Saharan Africa such as Malawi whose nationally run blood transfusion service struggles to maintain hospital blood banks. As a result, hospitals turn to their local communities for directed donations. A retrospective analysis from January 2014 to June 2016 of directed blood donor data from two hospitals in the Kasungu District of Malawi was conducted. The analysis of 2134 donations was carried out with respect to sex, age, hemoglobin concentration, blood group, and presence of transfusion-transmissible infections. On average, donors were 30 years of age and predominately male. Blood group O+ constituted more than half of all directed blood donations. Ultimately, about one third of donations were unable to be utilized for transfusion.
文摘Plants possess both types of endosymbiotic organelles, chloroplasts and mitochondria. Transit peptides and presequences function as signal sequences for specific import into chloroplasts and mitochondria, respectively. However, how these highly similar signal sequences confer the protein import specificity remains elusive. Here, we show that mitochondrial- or chloroplast-specific import involves two distinct steps, specificity determination and translocation across envelopes, which are mediated by the N-terminal regions and functionally interchangeable C-terminal regions, respectively, of transit peptides and presequences. A domain harboring multiple-arginine and hydrophobic sequence motifs in the N-terminal regions of presequences was identified as the mitochondrial specificity factor. The presence of this domain and the absence of arginine residues in the N-terminal regions of otherwise common targeting signals confers specificity of protein import into mitochondria and chloroplasts, respectively. AtToc159, a chloroplast import receptor, also contributes to determining chloroplast import specificity. We propose that common ancestral sequences were functionalized into mitochondrial- and chloroplast-specific signal sequences by the presence and absence, respectively, of multiple-arginine and hydrophobic sequence motifs in the N-terminal region.
