Page 1. "Imbued with courage, suffused with humanity, and written with grace." MATT RI... more Page 1. "Imbued with courage, suffused with humanity, and written with grace." MATT RIDLEY, author of Genome CHALLENGING NATURE ~> LEE The Jlash of ence and Spirituality at the New Frontiers of Life . SILVER Author of Remaking Eden Page 2. ...
Renowned biologist Ernest Everett Just (1883-1941) was an outspoken advocate for the classical em... more Renowned biologist Ernest Everett Just (1883-1941) was an outspoken advocate for the classical embryologist's view of the cell; he believed that all the parts of the cell, but especially the cytoplasm, have important roles to play in the process of development, whereby a one-celled zygote becomes a many-celled animal. In opposition to geneticist Thomas Hunt Morgan, Just formulated a hypothesis for how the cell works in development, one that gave a more dominant role to cytoplasmic (instead of nuclear) factors. This paper argues that, in creating his hypothesis, Just applied insights from the African American intellectual community in which he was immersed, much as Charles Darwin applied insights from British political economist Thomas R. Malthus in formulating his theory of evolution by natural selection. This in no way diminishes the scientific validity of Just's (or Darwin's) hypothesis. Rather, it highlights Just's creativity and, as such, points to the importance of having diversity in science.
The recent conversion of adult cells into so-called induced pluripotent stem (iPS) cells through ... more The recent conversion of adult cells into so-called induced pluripotent stem (iPS) cells through direct reprogramming opens a new chapter in the study of disease and the development of regenerative medicine. It also provides a historic opportunity to turn away from the ethically problematic use of embryonic stem cells isolated through the destruction of human embryos. Moreover, because iPS cells are patient specific, they render therapeutic cloning unnecessary. To maximize therapeutic benefit, adult stem cell research will need to be pursued in parallel with studies using iPS cells. Among the four alternative methods presented by the President's Council on Bioethics, direct reprogramming is the most ethically acceptable. Nonetheless, iPS cells are tainted by their association with the human embryonic stem cell lines, derived in the past, which will be required for their validation. This concern is one that can be resolved. Human iPS cells will serve to stem the tide of human embryonic stem cell research, changing it and diverting stem cell research in a more ethical direction.
Although I oppose the federal funding of human embryonic stem cell research, I supported Barack O... more Although I oppose the federal funding of human embryonic stem cell research, I supported Barack Obama for president. I voted for him in November despite knowing that he fully intended to lift the restrictions on embryonic stem cell research that President Bush had put in place. Indeed, I would vote for him again. Why? It is because, like many others, I am not a single-issue voter. Although I disagree with Obama on traditional respect-for-life issues such as abortion and stem cell research, I wholeheartedly agree with him on a host of other important issues-the war in Iraq, universal health care, the importance of diplomacy and dialogue, energy policy, concern for the environment, and global climate change, to name a few.
Ernest Everett Just (1883-1941) was a pioneering African-American embryologist who is best known ... more Ernest Everett Just (1883-1941) was a pioneering African-American embryologist who is best known for his discovery of the fast block to polyspermy, his elucidation of the slow block, and his discovery that the adhesive properties of the cells of the cleavage embryo depend on the particular developmental stage that they are in. Born in Charleston in 1883, Just left South Carolina as a teenager to attend Kimball Union Academy, a boarding school in Meriden, New Hampshire, and then Dartmouth College in nearby Hanover, where he received a bachelor's degree in 1907. That same year, he accepted a faculty position at Howard University. His appointment was at first in English, but in 1910, at the request of President Thirkfield, he moved to the Biology Department.
BoorRsYEws ofU.S. policy on embryos and concludes that making it more coherent will be a challeng... more BoorRsYEws ofU.S. policy on embryos and concludes that making it more coherent will be a challenge. I strong$ recommend tris book for scholarship and for teaching. It contains information that few moral theologians have at their fingertips and renders what can sometimes be expressed as vague concerns about justice in concrete terms. It also firrthers what may bethemain contribution ofthe Catholic common-good tradition: envisioning the possibility ofreal social change. Catholic social ethics has never endorsed a separatist, countercultural agenda, nor abandoned hope of social reform. Papal social-encyclical tradition (see, for example, Leo)OIL Rerum nwarum,lSgl [imptcitly], and John Paul II, Sollicitudo rei socialis,1987, nn' 46,48) as well as e,piscopal statements, such as the U.S. bishops' important 1993 statement on healthcare reforn, "A Framework for Comprehensive Health Care Reform: Protecting Human Life, Promoting Hunan Dipity, Pursuing the Common Good," envision bioethics as a st>. cially engaged endeavor, aiming at the transformation of social practices. Genetics and Ethics moves this agenda fonvard.
Except for residue 161, the amino acids within the loop are similar between B. stearothermophilus... more Except for residue 161, the amino acids within the loop are similar between B. stearothermophilus PFK (BsPFK) and the PFK from Escherichia coli (EcPFK). In the former enzyme, residue 161 is a glutamate, while in the latter it is a glutamine. We have used site-directed mutagenesis to investigate the importance of residue 161 for the allosteric regulation of the two enzymes by phosphoenolpyruvate (PEP), an inhibitor, and GDP, an activator. In BsPFK, glutamate 161 has been changed to a glutamine and an alanine, while in EcPFK, glutamine 161 has been changed to a glutamate, an arginine, and an alanine. The kinetic parameters of the mutant enzymes were similar to those of the respective wild types, indicating that residue 161 is not directly involved in substrate binding and catalysis. One of the EcPFK mutants, Q161A, though activated normally by GDP, was completely insensitive to PEP. This indicates that the hydrogen-bonding ability of residue 161 is critical for PEP inhibition of EcPFK and suggests that GDP activation and PEP inhibition follow different structural pathways in EcPFK. The BsPFK mutant enzymes were less sensitive to PEP inhibition and more sensitive to GDP activation, suggesting that inhibition and activation are opposed and follow a common structural pathway in agreement with a concerted allosteric mechanism. Phosphofructokinase (PFK,' EC 2.7.1.11) catalyzes the first committed step of glycolysis, the transfer of the y-phosphate of ATP to fructose 6-phosphate (Fru-6P) to produce ADP and fructose 1,6-bisphosphate. A divalent Mg2+ ion, as well as a monovalent N&+ or K+ ion, is required for catalysis. In bacteria, PFK is allosterically inhibited by phosphoenolpyruvate (PEP) and activated by ADP (or GDP). Bacterial PFK is a tetramer of identical subunits each 36 000 Da in size, and exists as a dimer of rigid dimers. There are four active sites and four effector sites into which both PEP and ADP (or GDP) bind.
The chloramphenicol producer Streptomyces venezuelae contains an enzyme, SvTrpEG, that has a high... more The chloramphenicol producer Streptomyces venezuelae contains an enzyme, SvTrpEG, that has a high degree of amino acid sequence similarity to the phenazine biosynthetic enzyme PhzE of certain species of Pseudomonas. PhzE has the sequence signature of an anthranilate synthase, but recent evidence indicates that it catalyzes the production of 2-amino-4-deoxyisochorismate (ADIC), an intermediate in the two-step anthranilate synthase reaction, not anthranilate. In order to determine if SvTrpEG is likewise an ADIC synthase, we have cloned the gene for SvTrpEG, expressed the recombinant enzyme in Escherichia coli, and purified the enzyme. Analysis of the SvTrpEG-catalyzed reaction mixture using UV-visible spectrophotometry, fluorescence spectrometry, and high-performance liquid chromatography shows that the product of the reaction is anthranilate, not ADIC. Our results therefore reveal that, despite its sequence similarity to PhzE, SvTrpEG is an anthranilate synthase, not an ADIC synthase.
The National Catholic Bioethics Quarterly, Feb 1, 2005
, meeting of the U. S. President's Council on Bioethics. Council member William Hurlbut, a physic... more , meeting of the U. S. President's Council on Bioethics. Council member William Hurlbut, a physician and Consulting Professor in the Program in Human Biology at Stanford University, formally unveiled a proposal that he claimed would solve the ethical problems surrounding the extraction of stem cells from human embryos. 1 The proposal would involve the creation of genetically defective embryos that "never rise to the level of integrated organismal existence essential to be designated human life with potential," 2 and therefore could be used as morally acceptable sources of stem cells for research and therapy. Only a few of the council members (Paul McHugh, Gilbert Meilaender and, to some extent, Michael Gazzaniga) expressed concern about Hurlbut's proposal, and Leon Kass, council chairman, endorsed the proposal "at The views expressed in this essay are solely the author's. They do not necessarily reflect the views of Howard University.
Page 1. "Imbued with courage, suffused with humanity, and written with grace." MATT RI... more Page 1. "Imbued with courage, suffused with humanity, and written with grace." MATT RIDLEY, author of Genome CHALLENGING NATURE ~> LEE The Jlash of ence and Spirituality at the New Frontiers of Life . SILVER Author of Remaking Eden Page 2. ...
Renowned biologist Ernest Everett Just (1883-1941) was an outspoken advocate for the classical em... more Renowned biologist Ernest Everett Just (1883-1941) was an outspoken advocate for the classical embryologist's view of the cell; he believed that all the parts of the cell, but especially the cytoplasm, have important roles to play in the process of development, whereby a one-celled zygote becomes a many-celled animal. In opposition to geneticist Thomas Hunt Morgan, Just formulated a hypothesis for how the cell works in development, one that gave a more dominant role to cytoplasmic (instead of nuclear) factors. This paper argues that, in creating his hypothesis, Just applied insights from the African American intellectual community in which he was immersed, much as Charles Darwin applied insights from British political economist Thomas R. Malthus in formulating his theory of evolution by natural selection. This in no way diminishes the scientific validity of Just's (or Darwin's) hypothesis. Rather, it highlights Just's creativity and, as such, points to the importance of having diversity in science.
The recent conversion of adult cells into so-called induced pluripotent stem (iPS) cells through ... more The recent conversion of adult cells into so-called induced pluripotent stem (iPS) cells through direct reprogramming opens a new chapter in the study of disease and the development of regenerative medicine. It also provides a historic opportunity to turn away from the ethically problematic use of embryonic stem cells isolated through the destruction of human embryos. Moreover, because iPS cells are patient specific, they render therapeutic cloning unnecessary. To maximize therapeutic benefit, adult stem cell research will need to be pursued in parallel with studies using iPS cells. Among the four alternative methods presented by the President's Council on Bioethics, direct reprogramming is the most ethically acceptable. Nonetheless, iPS cells are tainted by their association with the human embryonic stem cell lines, derived in the past, which will be required for their validation. This concern is one that can be resolved. Human iPS cells will serve to stem the tide of human embryonic stem cell research, changing it and diverting stem cell research in a more ethical direction.
Although I oppose the federal funding of human embryonic stem cell research, I supported Barack O... more Although I oppose the federal funding of human embryonic stem cell research, I supported Barack Obama for president. I voted for him in November despite knowing that he fully intended to lift the restrictions on embryonic stem cell research that President Bush had put in place. Indeed, I would vote for him again. Why? It is because, like many others, I am not a single-issue voter. Although I disagree with Obama on traditional respect-for-life issues such as abortion and stem cell research, I wholeheartedly agree with him on a host of other important issues-the war in Iraq, universal health care, the importance of diplomacy and dialogue, energy policy, concern for the environment, and global climate change, to name a few.
Ernest Everett Just (1883-1941) was a pioneering African-American embryologist who is best known ... more Ernest Everett Just (1883-1941) was a pioneering African-American embryologist who is best known for his discovery of the fast block to polyspermy, his elucidation of the slow block, and his discovery that the adhesive properties of the cells of the cleavage embryo depend on the particular developmental stage that they are in. Born in Charleston in 1883, Just left South Carolina as a teenager to attend Kimball Union Academy, a boarding school in Meriden, New Hampshire, and then Dartmouth College in nearby Hanover, where he received a bachelor's degree in 1907. That same year, he accepted a faculty position at Howard University. His appointment was at first in English, but in 1910, at the request of President Thirkfield, he moved to the Biology Department.
BoorRsYEws ofU.S. policy on embryos and concludes that making it more coherent will be a challeng... more BoorRsYEws ofU.S. policy on embryos and concludes that making it more coherent will be a challenge. I strong$ recommend tris book for scholarship and for teaching. It contains information that few moral theologians have at their fingertips and renders what can sometimes be expressed as vague concerns about justice in concrete terms. It also firrthers what may bethemain contribution ofthe Catholic common-good tradition: envisioning the possibility ofreal social change. Catholic social ethics has never endorsed a separatist, countercultural agenda, nor abandoned hope of social reform. Papal social-encyclical tradition (see, for example, Leo)OIL Rerum nwarum,lSgl [imptcitly], and John Paul II, Sollicitudo rei socialis,1987, nn' 46,48) as well as e,piscopal statements, such as the U.S. bishops' important 1993 statement on healthcare reforn, "A Framework for Comprehensive Health Care Reform: Protecting Human Life, Promoting Hunan Dipity, Pursuing the Common Good," envision bioethics as a st>. cially engaged endeavor, aiming at the transformation of social practices. Genetics and Ethics moves this agenda fonvard.
Except for residue 161, the amino acids within the loop are similar between B. stearothermophilus... more Except for residue 161, the amino acids within the loop are similar between B. stearothermophilus PFK (BsPFK) and the PFK from Escherichia coli (EcPFK). In the former enzyme, residue 161 is a glutamate, while in the latter it is a glutamine. We have used site-directed mutagenesis to investigate the importance of residue 161 for the allosteric regulation of the two enzymes by phosphoenolpyruvate (PEP), an inhibitor, and GDP, an activator. In BsPFK, glutamate 161 has been changed to a glutamine and an alanine, while in EcPFK, glutamine 161 has been changed to a glutamate, an arginine, and an alanine. The kinetic parameters of the mutant enzymes were similar to those of the respective wild types, indicating that residue 161 is not directly involved in substrate binding and catalysis. One of the EcPFK mutants, Q161A, though activated normally by GDP, was completely insensitive to PEP. This indicates that the hydrogen-bonding ability of residue 161 is critical for PEP inhibition of EcPFK and suggests that GDP activation and PEP inhibition follow different structural pathways in EcPFK. The BsPFK mutant enzymes were less sensitive to PEP inhibition and more sensitive to GDP activation, suggesting that inhibition and activation are opposed and follow a common structural pathway in agreement with a concerted allosteric mechanism. Phosphofructokinase (PFK,' EC 2.7.1.11) catalyzes the first committed step of glycolysis, the transfer of the y-phosphate of ATP to fructose 6-phosphate (Fru-6P) to produce ADP and fructose 1,6-bisphosphate. A divalent Mg2+ ion, as well as a monovalent N&+ or K+ ion, is required for catalysis. In bacteria, PFK is allosterically inhibited by phosphoenolpyruvate (PEP) and activated by ADP (or GDP). Bacterial PFK is a tetramer of identical subunits each 36 000 Da in size, and exists as a dimer of rigid dimers. There are four active sites and four effector sites into which both PEP and ADP (or GDP) bind.
The chloramphenicol producer Streptomyces venezuelae contains an enzyme, SvTrpEG, that has a high... more The chloramphenicol producer Streptomyces venezuelae contains an enzyme, SvTrpEG, that has a high degree of amino acid sequence similarity to the phenazine biosynthetic enzyme PhzE of certain species of Pseudomonas. PhzE has the sequence signature of an anthranilate synthase, but recent evidence indicates that it catalyzes the production of 2-amino-4-deoxyisochorismate (ADIC), an intermediate in the two-step anthranilate synthase reaction, not anthranilate. In order to determine if SvTrpEG is likewise an ADIC synthase, we have cloned the gene for SvTrpEG, expressed the recombinant enzyme in Escherichia coli, and purified the enzyme. Analysis of the SvTrpEG-catalyzed reaction mixture using UV-visible spectrophotometry, fluorescence spectrometry, and high-performance liquid chromatography shows that the product of the reaction is anthranilate, not ADIC. Our results therefore reveal that, despite its sequence similarity to PhzE, SvTrpEG is an anthranilate synthase, not an ADIC synthase.
The National Catholic Bioethics Quarterly, Feb 1, 2005
, meeting of the U. S. President's Council on Bioethics. Council member William Hurlbut, a physic... more , meeting of the U. S. President's Council on Bioethics. Council member William Hurlbut, a physician and Consulting Professor in the Program in Human Biology at Stanford University, formally unveiled a proposal that he claimed would solve the ethical problems surrounding the extraction of stem cells from human embryos. 1 The proposal would involve the creation of genetically defective embryos that "never rise to the level of integrated organismal existence essential to be designated human life with potential," 2 and therefore could be used as morally acceptable sources of stem cells for research and therapy. Only a few of the council members (Paul McHugh, Gilbert Meilaender and, to some extent, Michael Gazzaniga) expressed concern about Hurlbut's proposal, and Leon Kass, council chairman, endorsed the proposal "at The views expressed in this essay are solely the author's. They do not necessarily reflect the views of Howard University.
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