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PubMed2005

Angiogenesis and schistosomal granuloma formation.

An increasing amount of evidences points to angiogenesis as playing a paramount role in fibrosis development. However granulomas in general, and periovular schistosomal granulomas in particular, are considered avascular structures, although they usually result in dense areas of focal fibrosis. In order to clarify this apparent paradox, the presence of blood vessels was systematically searched in hepatic schistosomal granulomas of mice, during different stages of the infection, and at different stages of granuloma evolution, by means of vascular injections of colored masses, demonstration of laminin in vascular basement membranes and by ultra structural analysis. Vascular proliferation appeared evident at the early stages of granuloma formation, gradually decreasing thereafter, older granulomas becoming almost avascular structures, sometimes delimited at the periphery by a rich vascular network.

Animals↗

PubMed1999

Polyphyly and convergent morphological evolution in Commelinales and Commelinidae: evidence from rbcL sequence data.

Phylogenetic relationships of the five families of the order Commelinales remain an area of deep uncertainty in higher-level monocot systematics, despite intensive morphological and anatomical study. To test the monophyly of the Commelinales and the subclass Commelinidae, evaluate their relationships, and analyze evolutionary trends in their morphology, ecology, and biogeography, we conducted parsimony analyses on 95 rbcL sequences representing 17 taxa of Commelinales, 16 taxa of other Commelinidae, and 63 taxa from Arecidae, Liliidae, and Zingiberidae. Commelinales is polyphyletic and Commelinidae paraphyletic, with Eriocaulaceae and Xyridaceae sister to Poaceae and its relatives, Rapateaceae sister to Bromeliaceae and Mayacaceae, and Commelinaceae sister to Philydrales and allies. Thurnia is sister to Prionium at the base of Cyperaceae-Juncaceae; only 1 of Cronquist's multifamily commelinoid orders is diagnosed as monophyletic. We propose a revised Commelinidae, incorporating 4 revised superorders (Bromelianae, Commelinanae, Dasypogonanae, Arecanae) and 10 orders ((Poales, Eriocaulales, Cyperales, Typhales, Bromeliales), (Commelinales, Philydrales, Zingiberales), (Dasypogonales), (Arecales)). Morphological and anatomical characters used to define the original Commelinales and Commelinidae appear to be plesiomorphic or to reflect convergence or recurrent mutation; several characters supporting our revised classification are anatomical traits that seem relatively insulated from environmental selection pressures. The Commelinidae distal to the Arecales arose in South America, with amphiatlantic Bromeliaceae-Mayacaceae-Rapateaceae originating in the Guayana Shield. Ecological diversification involved the repeated invasion of shady, infertile, or arid microsites. The numbers of species in families of the revised Commelinidae are related partly to the extent of adaptive radiation in those families, but seem more strongly related to nonadaptive features promoting speciation, such as restricted seed dispersal (especially in forest interior groups with fleshy fruits), polyploidy, aneuploidy, and apomixis. Species diversity is unrelated to the rate/amount of rbcL sequence evolution.

DNA, Plant↗

PubMed2005

Pyramidal neurons of granular prefrontal cortex of the galago: complexity in evolution of the psychic cell in primates.

Typically, cognitive abilities of humans have been attributed to their greatly expanded cortical mantle, granular prefrontal cortex (gPFC) in particular. Recently we have demonstrated systematic differences in microstructure of gPFC in different species. Specifically, pyramidal cells in adult human gPFC are considerably more spinous than those in the gPFC of the macaque monkey, which are more spinous than those in the gPFC of marmoset and owl monkeys. As most cortical dendritic spines receive at least one excitatory input, pyramidal cells in these different species putatively receive different numbers of inputs. These differences in the gPFC pyramidal cell phenotype may be of fundamental importance in determining the functional characteristics of prefrontal circuitry and hence the cognitive styles of the different species. However, it remains unknown as to why the gPFC pyramidal cell phenotype differs between species. Differences could be attributed to, among other things, brain size, relative size of gPFC, or the lineage to which the species belong. Here we investigated pyramidal cells in the dorsolateral gPFC of the prosimian galago to extend the basis for comparison. We found these cells to be less spinous than those in human, macaque, and marmoset.

Animals↗

PubMed1997

Plant transposons: contributors to evolution?

A spectrum of different hypotheses has been presented by various authors, from plant transposable elements as major agents in evolution to the very opposite, transposons as mainly selfish DNA constituting a genetic burden for the organisms. The following review will focus on: (1) a short survey of the two main different assessments of transposable elements (TEs) concerning the origin of species (selfish vs useful DNA); (2) the significance of the hierarchy of gene functions and redundancies for TE activities (selfish in non-redundant parts of the genome, but as a source of variability in the rest); (3) the relevance of the results of TE research in Zea mays and Antirrhinum majus for species formation in the wild (contrast between artificial and natural selection); (4) three areas of research where a synthesis between the two different evaluations of TEs seems possible: regressive evolution, the origin of ecotypes and the origin of cultivated plants; and (5) some possible prospects regarding TE-induced species formation in the angiosperms in general, i.e., the basic difference between systematic and genetic species concepts and the conceivable origin of a large part of angiosperm morphospecies owing to loss of function and further mutations by TE activities.

DNA↗

PubMed1998

The correlation of protein structure and evolution of a protein-coding gene: phylogenetic inference using cytochrome oxidase III.

Discriminating phylogenetic signal from noise in DNA sequence data is a difficult problem in phylogenetic inference at higher systematic levels. For protein-coding genes, noise at synonymous (silent) positions can be filtered by deleting entire codon positions or types of change at a codon position. This method is not appropriate for replacement sites, because changes at each site within a codon may not be independent. This research presents a method using information from protein structure to evaluate variation in replacement sites. Analysis of the correlation of amino acid variation with protein structure identified rapidly evolving codons in the COIII gene. In a series of phylogenetic analyses attempting to recover a known set of vertebrate relationships, downweighting these labile codons produced the most accurate results. Structural correlates of variable and invariant residues identified in this study can be used to increase the accuracy of models used for phylogenetic inference. Viewing amino acid variation within a phylogenetic framework provided insight into residue changes important in the secondary and tertiary structures of the molecule, changes that were correlated between pairs of neighboring residues or between residues in neighboring helices.

Amino Acid Substitution↗

PubMed1998

Classification of vascular malformations of the central nervous system.

The ability to systematically and meaningfully classify a disease is in many ways a reflection of our overall understanding of it. Over time, nosologic schemes applied to any disease typically undergo a characteristic evolution from purely descriptive, to pathoanatomic and/or embryologic, to finally biological definitions. With the recent developments in further elucidating the pathophysiology, histopathology, natural history, and cellular biology of various vascular malformations occurring within the central nervous system, it is time to derive a more comprehensive and "universal" classification system that integrates classic pathoanatomic schemes with a biologically defined scheme previously developed for systematic vascular malformations. Such a system is proposed and discussed, including detailed review of important subtypes.

Arteriovenous Malformations↗

PubMed2005

The systematic component of phylogenetic error as a function of taxonomic sampling under parsimony.

The effect of taxonomic sampling on phylogenetic accuracy under parsimony is examined by simulating nucleotide sequence evolution. Random error is minimized by using very large numbers of simulated characters. This allows estimation of the consistency behavior of parsimony, even for trees with up to 100 taxa. Data were simulated on 8 distinct 100-taxon model trees and analyzed as stratified subsets containing either 25 or 50 taxa, in addition to the full 100-taxon data set. Overall accuracy decreased in a majority of cases when taxa were added. However, the magnitude of change in the cases in which accuracy increased was larger than the magnitude of change in the cases in which accuracy decreased, so, on average, overall accuracy increased as more taxa were included. A stratified sampling scheme was used to assess accuracy for an initial subsample of 25 taxa. The 25-taxon analyses were compared to 50- and 100-taxon analyses that were pruned to include only the original 25 taxa. On average, accuracy for the 25 taxa was improved by taxon addition, but there was considerable variation in the degree of improvement among the model trees and across different rates of substitution.

Classification↗

PubMed1990

[Systematic preoperative evaluation].

The number of preoperative studies is soaring due to the increase in paraclinical investigational means. Some of these assessments are regarded as superfluous. Since the future evolution of technology will inevitably further increase this item of Health costs, we should consider our possibilities for action within the limits of professional liability case law.

Clinical Laboratory Techniques↗

PubMed2006

Selected-control hydrothermal synthesis and formation mechanism of monazite- and zircon-type LaVO(4) nanocrystals.

Selective-controlled structure and shape of LaVO(4) nanocrystals were successfully synthesized by a simple hydrothermal method without the presence of catalysts or templates. It was found that tuning the pH of the growth solution was a crucial step for the control of the structure transformation, that is, from monoclinic (m-) to tetragonal (t-) phase, and morphology evolution of LaVO(4) nanocrystals. Further studies demonstrated that the morphology of the product had a strong dependence on the initial lanthanum sources. In the La(NO(3))(3) or LaCl(3) reaction system, pure t-LaVO(4) nanorods with uniform diameters about 10 nm could be obtained. But when using La(2)(SO(4))(3) as the lanthanum source, we can get t-LaVO(4) nanowiskers with broomlike morphology. The detailed systematic study had shown that a special dissolution-recrystallization transformation mechanism as well as an Ostwald ripening process was responsible for the phase control and anisotropic morphology evolution of the LaVO(4) nanocrystals. As a result, the controlled synthesis of m- and t-LaVO(4) not only has great theoretical significance in studying the polymorph control and selective synthesis of inorganic materials but also benefits the potential applications based on LaVO(4) nanocrystals owing to the unusual luminescent properties induced by structural transformation.

Journal Article↗

PubMed1983

Technology, specialization, and the allied health professions.

Medical specialization has been made possible through the evolution and dominance of the anatomic theory of disease and the growth of technology. Through the view offered by anatomy, the idea of dividing and studying portions of the body seemed natural and desirable. Through technology, diagnostic and therapeutic actions on these parts became possible. Specialization has affected all aspects of medicine, particularly the allied health professions. The narrow perspective on illness that specialization can produce in allied health professionals may be forestalled through systematic educational efforts to broaden their understanding of illness by delineating the ethical dimensions of their relationship to patients, creating a view of their place in the historical evolution of medicine, and examining how technology influences medicine and its role in shaping allied health careers.

Allied Health Personnel↗

PubMed2003

Multiple hybrid formation in natural populations: concerted evolution of the internal transcribed spacer of nuclear ribosomal DNA (ITS) in North American Arabis divaricarpa (Brassicaceae).

DNA sequence variation of the internal transcribed spacer (ITS) region of nuclear ribosomal DNA from Arabis holboellii, A. drummondii, and its putative hybrid A. divaricarpa was analyzed to study hybrid speciation in a species system geographically covering nearly the entire North American continent. Based on molecular systematics the investigated species are better combined under the genus Boechera. Multiple intraindividual ITS copies were detected in numerous accessions of A. divaricarpa, and, to a minor extent, in the parental taxa. Comparative phylogenetic analysis demonstrates that reticulate evolution is common. Consequently, concerted evolution of ITS regions resulted in different types of ITS fragments not only in hybrid populations but also in one of the parental taxa, A. holboellii. Hybrid formation often occurred independently at different sites and at different times, which is reflected by ITS copies resampling the original parental sequence variation in different ways. Some biogeographic structuring of genetic diversity is apparent and mirrors postglacial migration routes. Hybridization, reticulation, and apomixis are assumed to be the major forces driving speciation processes in this species complex. Analysis of conserved regions and secondary structures of the ITS region provided no evidence that, in this system, hybrid ITS evolution is predominantly driven in a particular direction. However, two regions in the ITS1 and ITS2, respectively, show higher mutation rates than expected from outgroup comparisons. Strong evidence for the occurrence of apomixis in A. holboellii and A. divaricarpa has come from pollen size measurements and estimations of pollen quality, which favor the hypothesis that A. drummondii served as paternal hybridization partner more frequently than A. holboellii.

Arabis↗

PubMed2003

Evolution of the AMP-forming acetyl-CoA synthetase gene in the Drosophilidae family.

Analysis of the AMP-forming ACS gene was performed in 12 species of the Drosophilidae family. Systematically four introns, aligned at the same positions, were detected, but none of them showed a position similar to those known for species outside the Drosophilidae family. The average length of introns varied from 63 to 75 bp but in two species Drosophila takahashii and D. kikkawai the length of the second intron was 343 and 210 bp, respectively. In coding regions, about 80% of the third codon positions were substituted while first and second positions showed, respectively, 14% and 6% substitutions. Interestingly, the divergence observed at the protein level between species was very low. The phylogenetic tree based on the DNA sequences of the exons was mainly in agreement with taxonomic classification and previous molecular phylogenies except for D. ananassae, which appeared more closely related to D. subobscura and D. funebris than to the species of the melanogaster group.

Acetate-CoA Ligase↗

PubMed2026

Building phenotypic character matrices for phylogenetic inference: exploration of 35 years of practice.

Recent methodological development in phylogenetic inference has focused predominantly on molecular data. However, renewed interest in other data types, particularly morphological data, has followed from the increased recognition of the power of total evidence and tip-dating approaches, including fossil data, for inference of time-scaled trees and rates of evolution. However, attention has largely focused on the improvement of models of morphological evolution and other analytical tools with much less discussion about data acquisition itself. Here we review past and current practice for describing and collecting morphological data for phylogenetic inference. We present a systematic review of 164 phylogenetic analyses conducted over the last 35 years and focused on a diverse group of extinct arthropods: trilobites. Trends in increasing matrix size, data type, and coding strategy are evident. Where present, polymorphic characters have been predominantly derived from discretized continuous characters, although increasingly practitioners are utilizing alternative approaches for the treatment of quantitative characters. Not surprisingly, traditional indices that describe character consistency are highly correlated with matrix size but show surprising variation at different taxonomic scales. More recent attempts to describe data quality using information theory imply that characters can have high information content even if data are missing for many tips, providing support against the exclusion of characters because of missing data. In consideration of this, as well as advances in the study of developmental biology and variational complexity, we identify several avenues for increasing the quality and quantity of morphological data going forward.

Phylogeny↗

PubMed2000

Promiscuity and the primate immune system.

The behavioral and ecological factors involved in immune system evolution remain poorly explored. We present a phylogenetic analysis of white blood cell counts in primates to test three hypotheses related to disease risk: increases in risk are expected with group size or population density, exposure to soil-borne pathogens, and mating promiscuity. White blood cell counts were significantly greater in species where females have more mating partners, indicating that the risk of sexually transmitted disease is likely to be a major factor leading to systematic differences in the primate immune system.

Animals↗

PubMed2004

The evolution of semantic systems.

Semantic or cultural systems are sets of concepts connected by meaningful relationships, and they exhibit properties similar to those of populations of biological organisms. Drawing upon ideas from evolutionary biology and methods from information technology, this article explores the potential for research and engineering on the evolution of semantic systems. Such work in cultural genetics requires two things: (1) a rigorous but evolving taxonomic system to categorize cultural artifacts, elements, and clusters, and (2) a set of hypotheses about the processes that cause evolutionary change. This article illustrates systematic approaches to cultural taxonomy with data on the popular ideology of the space program, science fiction motion pictures, nanotechnology books, and nanotechnology research grants. It offers hypotheses derived from evolutionary and population biology that might be useful in explaining cultural evolution.

Biological Evolution↗

PubMed2002

Segmental paralogy in the human genome: a large-scale triplication on 1p, 6p, and 21q.

Few cases of large-scale segmental paralogy have been reported in the human genome. We have identified a large (approximately 500 kb) segment on human chromosome (HC) 21 (21q22) that is triplicated on HC 1 (1p35) and HC 6 (6p12-21). We also identified a new member of CLIC (Chloride Intracellular Channel) family on 21q, namely CLIC6. All three segments appear to include three functional members of three different gene families: DSCR1-like (Down Syndrome Candidate Region 1-like), CLIC, and AML/Runt (Acute Myeloid Leukemia/Runt). Molecular evolution analysis shows a common evolutionary origin for the triplicated regions. This finding of a further large-scale genomic triplication that went undetected at previously systematic automated searches provides a new model for gene divergence study and underlines the need for new tools to effectively detect inter-chromosomal similarity. An algorithm to overcome current limitations is proposed.

Amino Acid Sequence↗

PubMed2004

Evolution of metazoan cell junction proteins: the scaffold protein MAGI and the transmembrane receptor tetraspanin in the demosponge Suberites domuncula.

Until recently the positioning of the sponges (phylum Porifera) within the metazoan systematics was hampered by the lack of molecular evidence for the existence of junctional structures in the surface cell layers. In this study two genes related to the tight junctions are characterized from the demosponge Suberites domuncula: tetraspanin (SDTM4SF), a cell surface receptor, and MAGI (SDMAGI), a MAGUK (membrane-associated guanylate kinase homologue) protein. Especially the MAGI protein is known in other metazoan animal phyla to exist exclusively in tight junctions. The characteristic domains of MAGI proteins (six PDZ domains, two WW domains, and a truncated guanylate kinase motif) are conserved in the sponge protein. The functional analysis of SDMAGI done by in situ hybridization shows its expression in the surface epithelial layers (exopinacoderm and endopinacoderm). Northern blot studies reveal that expression of SDMAGI and SDTM4SF increases after formation of the pinacoderm layer in the animals as well as in primmorphs. These results support earlier notions that sponges contain junctional structures. We conclude that sponges contain epithelia whose cells are organized by cell junctions.

Amino Acid Sequence↗

PubMed1996

Kinetic and cross-linking studies on the interactions of negative patch mutant plastocyanin from Silene pratensis with photosystem I complexes from cyanobacteria, green algae, and plants.

The site-directed mutants of negative patches on silene plastocyanin (PC) were used to investigate the change of interactions between photosystem I (PSI) and PC during the course of evolution from cyanobacteria to plants. The net charges of two highly conserved negative patches (#42-45 and #59-61) on silene PC were systematically modified from -4 to +1. PSI complexes from cucumber and Chlamydomonas reinhardtii were efficient electron acceptors for silene PC. The increase of net charge on the negative patch (#42-45) of silene PC decreased the reduction rates of PSI from cucumber and Chlamydomonas, while the modification of the other negative patch (#59-61) had no effect. Though the addition of MgCl2 decreased the reduction rate of cucumber PSI, the decrease was severely diminished in the case of Chlamydomonas PSI, and the reduction rate increased with increasing concentration of MgCl2 when the net charge of the negative patch (#42-45) was modified to +1. The PSI complexes from Anabaena variabilis and Synechosystis sp. PCC 6803 were inefficient electron acceptors for silene PC and their rates were almost independent of the net charge of the negative patches, as well as the ionic strength of the reaction mixtures. Silene PC specifically cross-linked to the PsaF subunit of PSI complexes from cucumber, Chlamydomonas, Anabaena, and Synechosystis sp. PCC 6803. Modification of the negative patch (#42-45) inhibited the formation of cross-linked adducts in all the cases examined, whereas modification of the other negative patch (#59-61) had essentially no effect. Based on these results, the changes of electrostatic interactions between PC and PSI during the course of evolution from cyanobacteria to plants are discussed.

Amino Acid Sequence↗