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PubMed1979

Earth history at the century mark of the U.S. Geological Survey.

Earth history involves all aspects of geological and biological evolution, especially paleontology and stratigraphy. Early paleontological exploration of the western United States by and before the U.S. Geological Survey featured the dramatic discoveries and rivalries of the great vertebrate paleontologists Leidy, Cope, Marsh, and Osborn. Invertebrate paleontology and paleobotany in the U.S. Geological Survey blossomed with emphasis on practical missions. The most illuminating and useful earth history, nevertheless, emerges where there is a high degree of interaction with academic scholars. Despite a good knowledge of its broad features, the drama of earth history remains obscure in detail. Whereas it speaks conclusively for the reality of organic evolution, it is less conclusive about mechanisms and many important transitions. Current investigations, however, especially in pre-Phanerozoic, mammalian, and human paleontology, promise improved insights. New techniques in collecting, sample preparation, and research are revealing previously unknown kinds of fossils and exquisite details of preservation. Plate tectonic theory provides a new framework for historical geography and biogeography. Emerging techniques in geochronology-matching paleopolarity sequences, for example-promise to resolve old problems of the synchroneity or heterochroneity of different biotal provinces. As it splits into subfields, the teaching and practice of paleontology expand to cover all of them. The fossils themselves, however, remain the basic objective evidence. All hypotheses about them must answer to this court of appeal. But nature rarely responds in an either-or way. The most probable hypotheses are those that have repeatedly confronted objective reality and survived all opportunity for disproof.

Journal Article↗
PubMed1984

Sequence homology between two membrane transport ATPases, the Kdp-ATPase of Escherichia coli and the Ca2+-ATPase of sarcoplasmic reticulum.

We have determined the DNA sequences of the genes encoding the three structural proteins of the Kdp-ATPase, an ATP-driven potassium transport system of Escherichia coli. Regions of the predicted amino acid sequence of KdpB, the phosphorylated protein of the system, are homologous to regions of the Ca2+-ATPase of rabbit sarcoplasmic reticulum. The phosphorylated aspartate residue of the latter is within a region of homology.

Adenosine Triphosphatases↗
PubMed1985

Binding of pea cytochrome f to the inner membrane of Escherichia coli requires the bacterial secA gene product.

Various sequences from the 5' end of the pea chloroplast gene for cytochrome f have been fused in the correct reading frame with lacZ, and the cellular location of the hybrid polypeptides in Escherichia coli has been examined. Hybrid polypeptides containing N-terminal parts of cytochrome f are located in the cytoplasmic membrane of E. coli. Membrane localization is most efficient when the intact signal sequence of cytochrome f is present at the N-terminal end of the fusion proteins. Fusion within the signal sequence, so that the processing site is absent, reduces the efficiency of membrane binding. Membrane insertion of fusion proteins containing signal sequences is prevented in a temperature-sensitive secA strain at the nonpermissive temperature and the hybrid proteins accumulate in the cytoplasm. This indicates that specific recognition of the chloroplast signal sequence occurs in the bacterial secretory pathway.

Bacterial Proteins↗
PubMed1985

Gene gating: a hypothesis.

It is assumed that the genome of a higher eukaryotic organism is organized into a number of distinct three-dimensional (3-D) structures, each characteristic for a given differentiated state. These discrete 3-D structures are envisioned to develop in a hierarchical and largely irreversible manner from an omnipotent 3-D structure of the zygotic genome. The information for these processes is assumed to reside in the genome. The nuclear pore complexes, the peripheral nuclear lamina, and components of the nuclear core are proposed to be among the topologically most proximal organelles that interpret this information and thereby serve in the maintenance and the alteration of the 3-D structure of the genome during development, differentiation, and the cell cycle. The nuclear pore complexes are envisioned to serve as gene-gating organelles capable on interacting specifically with expanded (transcribable) portions of the genome. Their nonrandom distribution on the nuclear surface would reflect the underlying periodic organization of the genome into expanded and compacted domains, alternating with each other. All transcripts of a given gated gene would leave the nucleus by way of that pore complex to which the gene is gated. Implications for cell asymmetry and polarity are discussed and evolutionary considerations are presented.

Animals↗
PubMed1992

Extreme clonal diversity and divergence in populations of a selfing hermaphroditic fish.

Recombination is unknown in natural populations of Rivulus marmoratus, a selfing hermaphrodite, and genetic variation is likely due to mutation alone. DNA fingerprinting with an array of microsatellite [e.g., (CT)9] and minisatellite (e.g., the 33.15 core sequence) probes reveals very high clonal diversity within samples of seven Floridian populations, of which five contain about as many clones as there are individuals. There are 42 clones among 58 individuals surveyed (mean, 1.4 individuals per clone), a level of genetic diversity unprecedented among clonal animals. Moreover, all of the probes recognize the same clones even though, at high hybridization stringencies, there is little overlap in the fingerprint patterns they generate. This suggests that most sympatric clones differ by multiple and independent mutational steps. In one population studied in detail, the average number of mutational steps separating two clones is estimated at 9 or 10 and may be substantially higher. The mutational discontinuities among sympatric clones make it unlikely that they evolved by accumulation of neutral mutations in populations that are otherwise genetically uniform. The data argue that the mixing of unrelated individuals from different local populations occurs to an extent previously unappreciated and/or that divergence of clones is mediated by natural selection. If confirmed, the latter would be a serious challenge to current ideas on the predominant role of recombination in promoting the evolution of biological novelty.

Animals↗
PubMed1995

Complexity, contingency, and criticality.

Complexity originates from the tendency of large dynamical systems to organize themselves into a critical state, with avalanches or "punctuations" of all sizes. In the critical state, events which would otherwise be uncoupled become correlated. The apparent, historical contingency in many sciences, including geology, biology, and economics, finds a natural interpretation as a self-organized critical phenomenon. These ideas are discussed in the context of simple mathematical models of sandpiles and biological evolution. Insights are gained not only from numerical simulations but also from rigorous mathematical analysis.

Journal Article↗
PubMed1999

Evidence of hominid-like precision grip capability in the hand of the Miocene ape Oreopithecus.

Functional and allometric analyses of the hand of the late Miocene ape Oreopithecus bambolii (Tuscany, Italy) reveal a series of features that reflect an improved grasping capability including firm pad-to-pad precision gripping that apes are unable to perform. Related features such as hand length, relative thumb length, a deep and large insertion area for the tendon of the long thumb flexor, and the form of the metacarpal 2/capitate articulation are not present in extant or fossil apes. In these features, the Oreopithecus hand closely matches the pattern of early hominids, presumably as a response to similar functional demands.

Animals↗
PubMed1999

Atmospheric oxygen over Phanerozoic time.

It is quite possible that the level of atmospheric oxygen has varied (roughly between 15 and 30% O2) over the past 550 million years. This variation is suggested by modeling of the carbon and sulfur cycles, by the excessive sediment burial of organic matter that accompanied the advent of large vascular land plants, and by recent physiological studies that relate to biological evolution.

Journal Article↗
PubMed1995

The high activity of rat glutathione transferase 8-8 with alkene substrates is dependent on a glycine residue in the active site.

Rat glutathione transferase (GST) 8-8 displays high catalytic activity with alpha, beta-unsaturated carbonyl compounds, including lipid peroxidation products such as 4-hydroxyalkenals. The catalytic efficiency of the related class Alpha GST 1-1 is substantially lower with the same substrates. Chimeric enzymes were prepared by replacing N-terminal subunit 8 segments of different lengths (6, 25, or 100 residues) with corresponding sequences from subunit 1 using recombinant DNA techniques. The chimeric subunit r1(25)r8, containing 25 amino acid residues from subunit 1, had the same low activity with alkenal substrates as that displayed by subunit 1. Mutation of Ala-12 into Gly in r1(25)r8 gave rise to the high alkenal activity characteristic of subunit 8, showing the importance of amino acid residue 12 for the activity. However, other structural determinants are also essential, as demonstrated by the corresponding Ala-12-->Gly mutation in subunit 1, which did not afford high alkenal activity. The results show that a single point mutation in a GST subunit may give rise to a 100-fold increase in catalytic efficiency with certain substrates. Introduction of such mutations may have contributed to the biological evolution of GST isoenzymes with altered substrate specificities and may also find use in the engineering of GSTs for novel functions.

Alkenes↗
PubMed2002

Characterization of effector proteins translocated via the SPI1 type III secretion system of Salmonella typhimurium.

Salmonella spp. employ a conserved type III secretion system encoded within the pathogenicity island 1 (SPI1; centisome 63) to translocate effector proteins into the host cytosol. The translocated effector proteins trigger diverse responses including bacterial internalization. In a mutation analysis we have defined the set of effector proteins mediating tissue culture cell invasion. This set includes sopE2 (centisome 40-42), sopB (SPI5, centisome 20) and in the case of S. typhimurium SL1344 also the phage-encoded effector sopE (SopEphi, centisome 59-60). A triple mutant SL1344 derivative deficient of SopE, SopE2 and SopB was more than 100-fold attenuated in tissue culture cell invasion. Phylogenetic analyses indicate that the last common ancestor of all contemporary Salmonella lineages already harbored all genes necessary for host cell invasion, namely the SPI1 type III secretion system, sopE2 and sopB. SopE, which is 70% identical to sopE2 is only present in some Salmonella strains and emerged later well after the divergence of the contemporary Salmonella lineages. Interestingly, S. typhimurium strains that harbor sopE are associated with epidemics, arguing that sopE is one of the factors determining the "fitness" of a strain. We found that SopE can specifically activate a different set of host cellular RhoGTPases than SopE2. This allows the bacteria to fine tune host cellular responses very precisely and may offer an explanation for the improved epidemic fitness of sopE-positive S. typhimurium strains.

Animals↗
PubMed2005

Integrating nutrition with ecology: balancing the health of humans and biosphere.

OBJECTIVE: To show that current rates of global population growth, production and consumption of food, and use of living and physical resources, are evidently not sustainable. To consider ways in which nutrition and allied sciences can respond to this great challenge of the twenty-first century. METHOD: Past, current and future projected trends in production and consumption patterns are examined. These show that overall present and projected patterns cannot be sustained; and also show increasing unacceptable inequity between and within rich and poor regions and countries. DISCUSSION: Nutrition science classically focuses on nutrients in relation to human physiology, metabolism, growth, health and disease. The social and environmental conditions of the modern, interconnected, market-oriented world, and the consequences for food production and consumption, are extending the research and policy agenda with which nutrition science must now urgently engage. Historically, much attention has been paid to eliminating nutritional deficiency states, and this remains an important task. In modern urban populations 'malnutrition' encompasses new forms of dietary imbalance, especially excesses of certain nutrients. These contribute to various non-communicable diseases and, particularly, to overweight/obesity and its attendant metabolic derangements and disease risks. As a mass phenomenon the current surge in obesity has no historical precedent. The escalating impact of humankind on the natural environment, with its ramifications for present and future food production, is also unprecedented. CONCLUSION: The essential challenge for nutrition science is to develop new understanding and strategies to enable a balance between promoting, equitably, the health of humans while sustaining the long-term health of the biosphere. Extension of nutrition science and food policy to meet those goals will be aided by understanding better how dietary conditions shaped the biological evolution of humankind. The fundamental long-term task is to integrate human health with the health of the biosphere.

Diet↗
PubMed2005

Lifestyle strategies for weight control: experience from the Finnish Diabetes Prevention Study.

Currently, in many European countries more than half the adult population is overweight; it hass become 'abnormal' to be of 'normal weight'. The risk of type 2 diabetes, CVD, hypertension and certain forms of cancer increase with increasing weight. Biological evolution has produced body-fat-regulating mechanisms that are more powerful in protecting against weight loss than against weight gain. The current environment offers constant availability of affordable palatable energy-rich foods, with no need to consume the energy through physical activity. The 'obesogenic' environment is to some extent a political issue, but it has been shown that the healthcare system can also have a role in preventing obesity-related morbidity. The Finnish Diabetes Prevention Study was the first controlled randomised study to show that individualised lifestyle counselling of individuals with high risk of developing type 2 diabetes can influence diet, physical activity and body weight, and that type 2 diabetes can be prevented, or at least postponed. Most importantly, lifestyle changes do not have to be extreme. If the population would adopt a lifestyle in line with the official nutrition recommendations, the obesity and diabetes trend could at least be stabilised.

Body Weight↗
PubMed1991

Evolutionary conservation of a microbody targeting signal that targets proteins to peroxisomes, glyoxysomes, and glycosomes.

Peroxisomes, glyoxysomes, glycosomes, and hydrogenosomes have each been classified as microbodies, i.e., subcellular organelles with an electron-dense matrix that is bound by a single membrane. We investigated whether these organelles might share a common evolutionary origin by asking if targeting signals used for translocation of proteins into these microbodies are related. A peroxisomal targeting signal (PTS) consisting of the COOH-terminal tripeptide serine-lysine-leucine-COOH has been identified in a number of peroxisomal proteins (Gould, S.J., G.-A. Keller, N. Hosken, J. Wilkinson, and S. Subramani. 1989. J. Cell Biol. 108:1657-1664). Antibodies raised to a peptide ending in this sequence (SKL-COOH) recognize a number of peroxisomal proteins. Immunocryoelectron microscopy experiments using this anti-SKL antibody revealed the presence of proteins containing the PTS within glyoxysomes of cells from Pichia pastoris, germinating castor bean seeds, and Neurospora crassa, as well as within the glycosomes of Trypanosoma brucei. Western blot analysis of purified organelle fractions revealed the presence of many proteins containing this PTS in both glyoxysomes and glycosomes. These results indicate that at least one of the signals, and therefore the mechanism, for protein translocation into peroxisomes, glyoxysomes, and glycosomes has been conserved, lending support to a common evolutionary origin for these microbodies. Hydrogenosomes, the fourth type of microbody, did not contain proteins that cross-reacted with the anti-PTS antibody, suggesting that this organelle is unrelated to microbodies.

Amino Acid Sequence↗