Advanced Life Forms Research Articles

Evolutionary origins and innovations sculpting the mammalian PRPS enzyme complex.

The phosphoribosyl pyrophosphate synthetase (PRPS) enzyme conducts a chokepoint reaction connecting central carbon metabolism and nucleotide production pathways, making it essential for life1,2. Here, we show that the presence of multiple PRPS-encoding genes is a hallmark trait of eukaryotes, and we trace the evolutionary origins and define the individual functions of each of the five mammalian PRPS homologs - three isozymes (one testis-restricted)3,4 and two non-enzymatic associated proteins (APs)5,6 - which we demonstrate operate together as a large molecular weight complex capable of attaining a heterogeneous array of functional multimeric configurations. Employing a repertoire of isogenic fibroblast clones in all viable individual or combinatorial assembly states, we define preferential interactions between subunits, and we show that cells lacking PRPS2, PRPSAP1, and PRPSAP2 render PRPS1 into aberrant homo-oligomeric assemblies with diminished metabolic flux and impaired proliferative capacity. We demonstrate how numerous evolutionary innovations in the duplicated genes have created specialized roles for individual complex members and identify translational control mechanisms that enable fine-tuned regulation of PRPS assembly and activity, which provide clues into the positive and negative selective pressures that facilitate metabolic flexibility and tissue specialization in advanced lifeforms. Collectively, our study demonstrates how evolution has transformed a single PRPS gene into a multimeric complex endowed with functional and regulatory features that govern cellular biochemistry.

Archean Biogeochemical Cognizance from Dharwar Craton, India – A Review

Abstract The Banded iron formations (BIFs) and manganese formations of Chitradurga, Shimoga and Sandur greenstone belts of Dharwar craton, associated with the stromatolitic carbonates, carbonaceous phyllites and shales along with gold mineralization, are best geological entities to evaluate the Archean biogeochemical processes and transformation of a habitable Earth. The geochemical anomalies along with C, O and S isotopic signatures of stromatolitic carbonates, carbonaceous phyllites and sulphidic BIFs reflect on biogenic signatures, fluctuating Archean ocean temperatures from 25-75°C and anoxic to euxinic redox conditions. The U-Pb detrital zircon ages of these stromatolitic carbonates indicate 3.5 to 2.6 Ga whereas the carbonaceous shales indicate 3.2 – 2.2 Ga reflecting the transportation of organic matter to the ocean basin during the growth of stromatolitic carbonates. The gold content of carbonaceous phyllites and sulphidic BIFs indicates hydrothermal source. The O2 produced due to stromatolitic activity has deposited Mn and Fe of the Archean oceans as BIFs and Mn formations. The biogenic matter of the stromatolites along with other siliciclastic material, gold and sulphides derived from the volcanic activity mixed and formed as carbonaceous shales in the ocean basin under euxinic conditions. The comprehensive geological, geochemical including isotopic studies on these rock types collectively indicate the interaction of lithosphere-hydrosphere-atmosphere-biosphere in the Archean oceans which paved the way for the advanced forms of life.

Authigenic kaolinite and sudoite in sandstones from the Paleoproterozoic Franceville sub-basin (Gabon)

The mineral paragenetic sequence of the 2.1-billion-year-old (Ga) Francevillian basin is important for understanding the diagenetic fluid history that allowed the preservation of the oldest ecosystem, including bacterial and more advanced forms of life in the FB 2 Member. However, a full characterization of the clay mineralogy of the FB 2 microbial mat-related structures (MRS) and associated host sediments (sandstones and black shales) is yet to be determined. Petrographic, microscopic, and mineralogical analyses reveal the concurrent presence of authigenic vermiform kaolinite and sudoite in the MRS and host sediments. Kaolinite formed along cleavages of altered muscovite and as pore-filling during early diagenesis, while sudoite likely precipitated at the expense of kaolinite that undergone secondary dissolution later in the diagenetic sequence. The formation of sudoite was promoted by fault-controlled acidic and oxidized brines that might have migrated during the Francevillian basin inversion. These results imply that the porosity and permeability of sedimentary rocks dominantly control the mineralogical assemblage of the FB 2 Member.

Close stellar encounters kicking planets out of habitable zone in various stellar environments

Continuous habitability of a planet is a critical condition for advanced forms of life to appear, but it can be endangered by astronomical events such as stellar encounters. The purpose of this study is to analyze close stellar encounters able to change planetary orbits initially in circumstellar habitable zones and to investigate the expected encounter rates in a variety of stellar environments. Using gravitational simulations for three-body systems, this study analyzed the dependencies of encounter impact-parameters with kinematic, geometric, and habitability parameters of the system. We also used kinematic properties of various stellar regions and estimated encounter rates of the events. The expected number of threatening stellar encounters in the Solar neighborhood is [Formula: see text] in 4 billion years, while for the Galactic bulge environment, we expect approximately 5.5 times the value. The encounter rates for other stellar environments are calculated and spheroidal dwarf galaxies and globular clusters encounter rates are estimated. The results show that in contrast with the solar neighborhood, close stellar encounters can play a significant role in the expected number of planets with continuous habitability in dense stellar environments. Another notable result shows that threatening stellar encounter rate follows the number density of stars, and is not strongly dependent of the region’s velocity dispersion. Further investigations are needed to study long-term multiple planetary systems and how they can change the overall expected value of continuously habitable planets.

Targeting Mitochondrial Singlet Oxygen Dynamics Offers New Perspectives for Effective Metabolic Therapies of Cancer.

The occurrence of mitochondrial respiration has allowed evolution toward more complex and advanced life forms. However, its dysfunction is now also seen as the most probable cause of one of the biggest scourges in human health, cancer. Conventional cancer treatments such as chemotherapy, which mainly focus on disrupting the cell division process, have shown being effective in the attenuation of various cancers but also showing significant limits as well as serious sides effects. Indeed, the idea that cancer is a metabolic disease with mitochondria as the central site of the pathology is now emerging, and we provide here a review supporting this “novel” hypothesis re-actualizing past century Otto Warburg's thoughts. Our conclusion, while integrating literature, is that mitochondrial activity and, in particular, the activity of cytochrome c oxidase, complex IV of the ETC, plays a fundamental role in the effectiveness or non-effectiveness of chemotherapy, immunotherapy and probably radiotherapy treatments. We therefore propose that cancer cells mitochondrial singlet oxygen (1O2) dynamics may be an efficient target for metabolic therapy development.

Intergovernmental Coordination without the Big Polluters

Human beings have existed as modern homo sapiens for some 100,000 years, recent DNA research informs. And this race has grown to a staggering 8 billion almost, dominant over all other living species and subjugating the other human races. The 21st century may end the fantastic story about Cro-Magnons as planet Earth no longer may support advanced forms of life, i.e. low temperature, supply of food, access to drinking water as well as absence of war between or within nations and even civilisations. Only intergovernmental coordination can slow the process of climate change, but the nature of international relations prohibits it.

A Relational Ontology for Psychology: Life as an Asymmetric Subjet-Object Choosing Relation : Review of A New Logical Foundation for Psychology, J. Mammen, Springer, 2017.

This review of Mammen's new book (2017), provides a brief summary of the first part, stressing the main points of the author's constructive critique of the unfortunate issues psychology inherited from the atomistic mechanism of classical physics. Driving the discussion on the ontological level, Mammen briefly shows how nowadays natural sciences provide the main components psychology needs to overcome the everlasting crisis of psychology sinceits constitution as a science: discontinuity, contextuality, etc. Making of the relation between subject and object the foundation of any science, Mammen contributes to a new ontology specific to human study with elements of last century mathematics, notably the axiom of choice, bridging the rift between natural and human sciences with a continuum from inert matter to more or less advanced life forms. Mammen's constructive proposal opens the building site of a new foundation for life sciences, avoiding both simplistic mechanism and nihilist post-modernism.

Evolution and Creationism: Views of Students in a Colombian University—Findings from 7 Years of Data Using a Three-Question Survey

The theory of evolution is the backbone of the biological sciences. Arguably, this is the reason why evolution education is an extensively investigated issue in several countries around the world. Little is known, however, about the views of university students in Colombia. Here, we report on 7 years of data generated by a three-question anonymous survey to identify Colombian university students’ views about evolution and creationism. We hypothesized that university students’ views may be related to their major and/or age. In total, 1132 students (ages 16–23 years) from different majors at a private university in Bogota were surveyed. Our findings showed that (1) 66% of the university students held the view that human beings have developed over millions of years from less advanced forms of life and that God had no part in this process, (2) 85% of university students believed that humans have developed from other species, (3) 84% of university students held the view that life on Earth has evolved over time through natural selection, and (4) the chi-square analyses of the responses to the three-question survey revealed that university students’ views about evolution and creationism were not related to their major and/or age. Our findings reinforce the key role of students’ views, which should be valued and integrated into evolution education practice.

Updating Darwin: Information and entropy drive the evolution of life

The evolution of species, according to Darwin, is driven by struggle – by competition between variant autonomous individuals for survival of the fittest and reproductive advantage; the outcome of this struggle for survival is natural selection. The Neo-Darwinians reframed natural selection in terms of DNA: inherited genotypes directly encode expressed phenotypes; a fit phenotype means a fit genotype – thus the evolution of species is the evolution of selfish, reproducing individual genotypes. Four general characteristics of advanced forms of life are not easily explained by this Neo-Darwinian paradigm: 1) Dependence on cooperation rather than on struggle, manifested by the microbiome, ecosystems and altruism; 2) The pursuit of diversity rather than optimal fitness, manifested by sexual reproduction; 3) Life’s investment in programmed death, rather then in open-ended survival; and 4) The acceleration of complexity, despite its intrinsic fragility. Here I discuss two mechanisms that can resolve these paradoxical features; both mechanisms arise from viewing life as the evolution of information. Information has two inevitable outcomes; it increases by autocatalyis and it is destroyed by entropy. On the one hand, the autocalalysis of information inexorably drives the evolution of complexity, irrespective of its fragility. On the other hand, only those strategic arrangements that accommodate the destructive forces of entropy survive – cooperation, diversification, and programmed death result from the entropic selection of evolving species. Physical principles of information and entropy thus fashion the evolution of life.

Updating Darwin: Information and entropy drive the evolution of life.

The evolution of species, according to Darwin, is driven by struggle - by competition between variant autonomous individuals for survival of the fittest and reproductive advantage; the outcome of this struggle for survival is natural selection. The Neo-Darwinians reframed natural selection in terms of DNA: inherited genotypes directly encode expressed phenotypes; a fit phenotype means a fit genotype - thus the evolution of species is the evolution of selfish, reproducing individual genotypes. Four general characteristics of advanced forms of life are not easily explained by this Neo-Darwinian paradigm: 1) Dependence on cooperation rather than on struggle, manifested by the microbiome, ecosystems and altruism; 2) The pursuit of diversity rather than optimal fitness, manifested by sexual reproduction; 3) Life's investment in programmed death, rather then in open-ended survival; and 4) The acceleration of complexity, despite its intrinsic fragility. Here I discuss two mechanisms that can resolve these paradoxical features; both mechanisms arise from viewing life as the evolution of information. Information has two inevitable outcomes; it increases by autocatalyis and it is destroyed by entropy. On the one hand, the autocalalysis of information inexorably drives the evolution of complexity, irrespective of its fragility. On the other hand, only those strategic arrangements that accommodate the destructive forces of entropy survive - cooperation, diversification, and programmed death result from the entropic selection of evolving species. Physical principles of information and entropy thus fashion the evolution of life.

ABOUT EXOBIOLOGY: THE CASE FOR DWARF K STARS

ABSTRACT One of the most fundamental topics of exobiology concerns the identification of stars with environments consistent with life. Although it is believed that most types of main-sequence stars might be able to support life, particularly extremophiles, special requirements appear to be necessary for the development and sustainability of advanced life forms. From our study, orange main-sequence stars, ranging from spectral type late-G to mid-K (with a maximum at early K), are most promising. Our analysis considers a variety of aspects, including (1) the frequency of the various types of stars, (2) the speed of stellar evolution in their lifetimes, (3) the size of the stellar climatological habitable zones (CLI-HZs), (4) the strengths and persistence of their magnetic-dynamo-generated X-ray–UV emissions, and (5) the frequency and severity of flares, including superflares; both (4) and (5) greatly reduce the suitability of red dwarfs to host life-bearing planets. The various phenomena show pronounced dependencies on the stellar key parameters such as effective temperature and mass, permitting the assessment of the astrobiological significance of various types of stars. Thus, we developed a “Habitable-Planetary-Real-Estate Parameter” (HabPREP) that provides a measure for stars that are most suitable for planets with life. Early K stars are found to have the highest HabPREP values, indicating that they may be “Goldilocks” stars for life-hosting planets. Red dwarfs are numerous, with long lifetimes, but their narrow CLI-HZs and hazards from magnetic activity make them less suitable for hosting exolife. Moreover, we provide X-ray–far-UV irradiances for G0 V–M5 V stars over a wide range of ages.

Genes of ancient microtubule-stabilizing proteins traveled through pre-Cambrian Echinoidea to advanced life forms of dry land and ended up in the human genome as the fusion oncogenes-oncoproteins eml1/EML1-abl/ABL, and eml4/EML4-alk/ALK

The genes eml1/4 of the Echinodermata microtubule-stabilizing gene product-like 1/4 proteinsEML1/4 of the sea cucumbers (Holothuroidea) traveled through the evolutionary scale up to the human genome. Human cells malignantly transformed by oncogenes abl or alk enlist the protein products EML1/4 for the activation and protection of the gene product oncoproteins ABL or ALK against destruction by ubiquitination, and for gaining virulence and chemotherapy resistance. Neither the abl nor the alk genes act as oncogenes without fusion with another particular gene, such as eml1/4 in this case. A large number of ancient but conserved gene product proteins chaperon, protect and enhance oncoproteins. These mechanisms indicate that ancient cell survival pathways exist conserved in the genomes of advanced multicellular diplo- and triploblastic hosts (including Homo). These genomic pathways are on special occasions constitutively reactivated in extant cells undergoing transformations for survival under adverse circumstances. Extant cells under threat react by re-living scenarios that characterized life forms in the primordial physico-chemical universe. In the clinical practice these cells are recognized as chemoradiotherapy-resistant cancer cells undergoing a process of retrograde immortalization.

Cosmic Explosions, Life in the Universe, and the Cosmological Constant.

Gamma-ray bursts (GRBs) are copious sources of gamma rays whose interaction with a planetary atmosphere can pose a threat to complex life. Using recent determinations of their rate and probability of causing massive extinction, we explore what types of universes are most likely to harbor advanced forms of life. We use cosmological N-body simulations to determine at what time and for what value of the cosmological constant (Λ) the chances of life being unaffected by cosmic explosions are maximized. Life survival to GRBs favors Lambda-dominated universes. Within a cold dark matter model with a cosmological constant, the likelihood of life survival to GRBs is governed by the value of Λ and the age of the Universe. We find that we seem to live in a favorable point in this parameter space that minimizes the exposure to cosmic explosions, yet maximizes the number of main sequence (hydrogen-burning) stars around which advanced life forms can exist.

Evolution of the PWWP-domain encoding genes in the plant and animal lineages

BackgroundConserved domains are recognized as the building blocks of eukaryotic proteins. Domains showing a tendency to occur in diverse combinations (‘promiscuous’ domains) are involved in versatile architectures in proteins with different functions. Current models, based on global-level analyses of domain combinations in multiple genomes, have suggested that the propensity of some domains to associate with other domains in high-level architectures increases with organismal complexity. Alternative models using domain-based phylogenetic trees propose that domains have become promiscuous independently in different lineages through convergent evolution and are, thus, random with no functional or structural preferences. Here we test whether complex protein architectures have occurred by accretion from simpler systems and whether the appearance of multidomain combinations parallels organismal complexity. As a model, we analyze the modular evolution of the PWWP domain and ask whether its appearance in combinations with other domains into multidomain architectures is linked with the occurrence of more complex life-forms. Whether high-level combinations of domains are conserved and transmitted as stable units (cassettes) through evolution is examined in the genomes of plant or metazoan species selected for their established position in the evolution of the respective lineages.ResultsUsing the domain-tree approach, we analyze the evolutionary origins and distribution patterns of the promiscuous PWWP domain to understand the principles of its modular evolution and its existence in combination with other domains in higher-level protein architectures. We found that as a single module the PWWP domain occurs only in proteins with a limited, mainly, species-specific distribution. Earlier, it was suggested that domain promiscuity is a fast-changing (volatile) feature shaped by natural selection and that only a few domains retain their promiscuity status throughout evolution. In contrast, our data show that most of the multidomain PWWP combinations in extant multicellular organisms (humans or land plants) are present in their unicellular ancestral relatives suggesting they have been transmitted through evolution as conserved linear arrangements (‘cassettes’). Among the most interesting biologically relevant results is the finding that the genes of the two plant Trithorax family subgroups (ATX1/2 and ATX3/4/5) have different phylogenetic origins. The two subgroups occur together in the earliest land plants Physcomitrella patens and Selaginella moellendorffii.ConclusionGain/loss of a single PWWP domain is observed throughout evolution reflecting dynamic lineage- or species-specific events. In contrast, higher-level protein architectures involving the PWWP domain have survived as stable arrangements driven by evolutionary descent. The association of PWWP domains with the DNA methyltransferases in O. tauri and in the metazoan lineage seems to have occurred independently consistent with convergent evolution. Our results do not support models wherein more complex protein architectures involving the PWWP domain occur with the appearance of more evolutionarily advanced life forms.

One hundred fifty years without Darwin are enough!

Charles Darwin (1809–1882) was born two centuries ago. The Origin of Species was published in 1859, 150 yr ago. The theory of biological evolution by natural selection, as first proposed by Darwin, is the central organizing principle of biology. Indeed, as the great evolutionist Theodosius Dobzhansky asserted in 1973 in an address to the American Association of Biology Teachers, ‘‘Nothing in biology makes sense except in the light of evolution’’ (Dobzhansky 1973). Yet, in the United States, evolution is not generally accepted by the public. According to a Gallup poll of 1016 U.S. adults, taken in November 2004, 45% of those surveyed favored the statement that ‘‘God created human beings in their present form within the last 10,000 years,’’ 38% favored that ‘‘Man developed over millions of years, but God guided the process,’’ and 13% that ‘‘Man developed over millions of years from less advanced life forms.’’ Teaching creationism rather than evolution in the schools is favored by a large number of American citizens. In a CNN/USA Today Gallup poll of 1001 adults conducted in March 2005, 76% would not ‘‘be upset if public schools in [their] community taught creationism,’’ but only 63% would not ‘‘be upset if the schools taught evolution.’’ Only 22% would be upset if creationism would be taught, while 34% would be upset if evolution would be taught. Other polls yield similar statistics. In 1959, at a symposium celebrating the 100th anniversary of the publication of the Origin of Species, the eminent geneticist and Nobel Laureate H.J. Muller proclaimed ‘‘One Hundred Years without Darwin Are Enough!’’ (Muller 1959). Fifty years later, Darwin’s theory of evolution is far from universally accepted by the American public and activists throughout the country are advancing creationist or ‘‘intelligent design’’ alternatives to explain the origin, diversity, and adaptation of organisms, seeking that these ‘‘theories’’ be taught in the schools. Our educational system and society as a whole are best served when we teach science,not religious faithmasqueradingas science, in theclassrooms. It is pathetic that at this point in history we need to proclaim that 150 years without Darwin’s Origin of Species are enough.

T-Rex in Wonderland: Kentucky’s 27-million-dollar Creation Museum Turns One

One year ago, when I covered the opening of the Answers in Genesis Creation Museum in Petersburg, Kentucky (Slack 2007), I asked preacher Ken Ham, Answers in Genesis’ rugged-faced CEO and president, why the age of the Earth matters so much to his followers. “If any word of the Bible is false,” he said, “then all of it can be called into question.” From Ham’s point of view, the authority of the entire Bible rides on every word in it. If Genesis is wrong, then the Ten Commandments might as well be, too. And it is the Ten Commandments and other moral pronouncements in the Bible that are important to Ham, not really, in themselves, the age of the Earth or the method by which it was populated. The real concern and target of creationism is not evolution, it is moral relativism. The Creation Museum is no little roadside attraction. It’s a polished, 27-million-dollar, 60,000-square-foot “natural history” museum just about 20 miles southwest of Cincinnati and within easy driving distance of millions of people. In the 12 months since its opening, according to the museum’s website, more than 360,000 people have visited its halls. Answers in Genesis (AiG), the nonprofit ministry devoted to what it calls Biblical apologetics, or “the reasoned defense of the Bible,” is projecting at least as many in the year to come. It is remarkable that AiG was able to raise nearly 30 million dollars to build the museum and fill it with exhibits, but more astounding still is the fact that so many Americans will come here and say, “Finally, a decent science museum for me!” In fact, I heard that sentiment repeated time and again from museum visitors. A 2007 Newsweek poll found that 48% of Americans hold that “God created humans pretty much in the present form at one time within the last 10,000 years or so.” (Newsweek Poll 2007). That means about half of Americans would feel perfectly at home at the Creation Museum. That’s a higher percentage than accept the view of the world portrayed in mainstream science museums. In the same poll, only 43% answered affirmatively to the assertion that “Humans developed over millions of years from less advanced forms of life.” Ham is explicit about the museum’s purpose. He hoped, he said, that it would undo “the damage done 82 years ago when Clarence Darrow put William Jennings Bryan on the stand” in the famous Scopes trial in Dayton, Tennessee. “Bryan was asked questions about the Book of Genesis that he couldn’t answer,” said Ham. “It was the first time the Bible was ridiculed by the media in America, and that was a downward turning point for Christendom.” In the decades that followed, Ham said, the Bible’s values were replaced by a tolerance for homosexuality, divorce, sexual promiscuity, porn, and the banning of God from schools and courts. “We are going to undo all of that here at the Creation Museum,” said Ham. “We are going to answer the questions Bryan wasn’t prepared to, and show that belief in every word of the Bible can be defended by modern science.” I am an evolutionist, not religious, and not an advocate of creationism in any of its forms. But wherever you stand on the evolution–creation debate, this museum has a lot to Evo Edu Outreach (2008) 1:342–345 DOI 10.1007/s12052-008-0063-6

Creationism in the Biology Classroom: What Do Teachers Teach & How Do They Teach It?

Despite decades of science education reform, a long string of legal defeats for creationists, the incorporation of evolution-based standards into states' science education requirements, and the repeated emphasis of evolution by scientific professional societies (National Association of Biology Teachers, 2002; Moore, 2002a-c, 2004, a-b), creationism remains overwhelmingly popular with the public (i.e., with our former students). For example, 45% of participants in a 1982 Gallup poll agreed with the statement that created human beings pretty much in their present form at one time within the last 10,000 years or so; 40% agreed with Human beings have developed over millions of years from less advanced forms of life, but God guided this process; and 9% agreed with Human beings have developed over millions of years from less advanced forms of life, but god had no part in this process (Scott, 1999). In an identical Gallup poll conducted in 2004, the responses were similar (Newport, 2004), and a study published in 2006 found that the acceptance of evolution is lower in the United States than virtually anywhere else in the world (Miller, Scott & Okamoto, 2006). As biology teacher John Scopes noted in 1966, don't think the world changes very rapidly (Anonymous, 1966). Creationism also remains surprisingly popular among high school biology teachers throughout the United States (Eve & Harrold, 1991; Moore, 2004a-b; Riddle, 1941). For example, a variety of studies have shown that 15-30% of biology teachers in public schools teach creationism (Eve & Harrold, 1991; Trani, 2004; Zimmerman, 1987, and references therein). Although the teaching of creationism (including intelligent design) in public school biology classes is clearly unlawful (Edwards v. Aguillard; Moore 2002a, 2004a, 2007), these teachers' actions are consistent with the public's desire to include creationism in science classrooms (Bergman, 1999). Confrontations of some of these teachers have produced lawsuits, all of which have been lost by creationists (Moore, 2002a, 2004a, 2007). Although the various studies of the teaching of creationism in biology classrooms have been informative, they have often involved political problems, small sample sizes, and limited responses (e.g., participants' responses were restricted to only the Christian stories of creation; Aguillard, 1999; Bergman, 1999; McKeachie, Lin & Strayer, 2002). Moreover, they have not addressed several important questions that I have tried to answer with this study. For example, * What version(s) of creationism do teachers teach? There are many different stories and, even within Christianity, many different types of creationism (Leeming & Leeming, 1994; Scott, 2004). Do biology teachers who include creationism in their courses teach several generic stories or a variety of specific stories? Or only one story? If teachers teach only one story, which story do they teach? * How do teachers present creationism? For example, do teachers present creationism as a religious idea? Or as a philosophical idea? Or as a scientific alternative to evolution (i.e., creation science)? What I Did This study was conducted from fall, 2001 through fall, 2005 in a large, introductory non-majors biology course at the Twin Cities campus of the University of Minnesota. Students in the study came from throughout the United States, and particularly from Minnesota, and had an average ACT score of 22, an average age of 19, and an average high school graduation percentile of 54%. There were approximately equal percentages of male and female students having the following ethnic diversity: 51% Caucasian, 20% African American, 2% American Indian, 20% Asian American, 4% Chicano/Latina, and 3% undecided. To avoid the low return rates and other problems associated with direct surveys of teachers (e.g., a 29% return rate in Ohio; Zimmerman, 1987), I surveyed 1,465 freshmen who had taken high school biology in public schools. …

らい菌によるマクロファージの機能変化

As an obligate intracellular pathogen, the principal host cells for Mycobacterium leprae are mononuclear phagocytes or macrophages. The macrophage is a primitive cell type being found in both early and advanced life forms, and possesses a variety of functions, such as phagocytosis of invaded bacteria, production of cytokines, antigen presentation and tumor killing. Hansen's disease is a chronic infectious disease characterized by specific host immune responses against M. leprae. In this article the macrophage is focused to dissect its functions in the disease.

The Driving Force for Life's Emergence: Kinetic and Thermodynamic Considerations

The principles that govern the emergence of life from non-life remain a subject of intense debate. The evolutionary paradigm built up over the last 50 years, that argues that the evolutionary driving force is the Second Law of Thermodynamics, continues to be promoted by some, while severely criticized by others. If the thermodynamic drive toward ever-increasing entropy is not what drives the evolutionary process, then what does? In this paper, we analyse this long-standing question by building on Eigen's “replication first” model for life's emergence, and propose an alternative theoretical framework for understanding life's evolutionary driving force. Its essence is that life is a kinetic phenomenon that derives from the kinetic consequences of autocatalysis operating on specific biopolymeric systems, and this is demonstrably true at all stages of life's evolution — from primal to advanced life forms. Life's unique characteristics — its complexity, energy-gathering metabolic systems, teleonomic character, as well as its abundance and diversity, derive directly from the proposition that from a chemical perspective the replication reaction is an extreme expression of kinetic control, one in which thermodynamic requirements have evolved to play a supporting, rather than a directing, role. The analysis leads us to propose a new sub-division within chemistry — replicative chemistry. A striking consequence of this kinetic approach is that Darwin's principle of natural selection: that living things replicate, and therefore evolve, may be phrased more generally: that certain replicating things can evolve, and may therefore become living. This more general formulation appears to provide a simple conceptual link between animate and inanimate matter.

Landmark discoveries in the trail from chemistry to cellular biochemistry, with particular reference to mileposts in research on bioenergetics

AbstractMolecular oxygen was discovered in 1775 by Joseph Priestley. He also made the important observations that oxygen is produced by plants and that gases (O2 and CO2) mediate the interdependence of plant and animal life. The biological experiments of Priestley dealt with aerobes, the most advanced forms of life. It was the research of Louis Pasteur, however, on fermentation of sugar by anaerobic microbes that provided a system that was the first to reveal significant clues to the biochemistry of bioenergetics. Analysis of the detailed mechanism of anaerobic sugar fermentation by yeast during the first third of the 20th century and the later study of energy‐yielding aerobic respiration and energy conversion in photosynthesis required development of many new techniques. These became the tools that were exploited to yield the basic outlines of cell biochemistry. Included were chromatography, metabolic gas manometry, spectrophotometry, the use of stable and radioactive isotopes as tracers of intermediary metabolism, and procedures for purification of proteins and other macromolecules. Noteworthy advances included discovery and characterization of the (Krebs) tricarboxylic acid cycle, “activated” intermediates such as acetyl coenzyme A, electron carriers and coenzymes necessary for energy conversion and reductive biosynthesis, ATP (the universal energy “currency”) and a multitude of enzymes involved in catabolic and biosynthetic metabolism.