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PubMed1999

The Tangled Web: Gene Genealogies and the Origin of Eukaryotes.

Accessing data from the genomes of organisms (individual genes) and analyzing these data using sophisticated alignment and phylogenetic methods led to the expectation that we would be able to paint a clear picture of the evolution of eukaryotes. Previous analyses based on morphology and ultrastructure failed to pinpoint both the sister taxon to eukaryotes and the branching order of eukaryotic lineages. However, the expectation that molecular data would provide resolution has not been met since a growing number of gene genealogies present conflicting hypotheses for the origin and diversification of eukaryotes. Instead of reconstructing a simple bifurcating tree of life, these gene genealogies have generated a complex picture of eukaryotic genomes whereby ancient lateral transfers (of individual genes or perhaps even entire genomes) has tangled the evolutionary history of eukaryotes. Resolution of these conflicting genealogies comes in recognizing that eukaryotes are chimeric, containing genetic information from multiple ancestral lineages.

Journal Article↗
PubMed2003

The mitochondrial genome of Phoronis architecta--comparisons demonstrate that phoronids are lophotrochozoan protostomes.

The proper reconstruction of the relationships among the animal phyla is central to interpreting patterns of animal evolution from the genomic level to the morphological level. This is true not only of the more speciose phyla but also of smaller groups. We report here the nearly complete DNA sequence of the mitochondrial genome of the phoronid Phoronis architecta, which has a gene arrangement remarkably similar to that of a protostome animal, the chiton Katharina tunicata. Evolutionary analysis of both gene arrangements and inferred amino acid sequences of these taxa, along with those of three brachiopods and other diverse animals, strongly supports the hypothesis that lophophorates are part of the large group that includes mollusks and annelids-i.e., the Lophotrochozoa-and solidly refutes the alternative of their being deuterostomes.

Animals↗
PubMedDate not supplied

Genetic and morphological divergence among sympatric canids.

Numerous studies have suggested that the extent of character divergence observed between two sympatric species reflects the intensity of competition for resources or space. However, the influence of time on divergence is often overlooked. We examined the relationship between time and character divergence in two groups of congeneric, sympatric canids on two continents: South American foxes and African jackals. Character divergence was assessed from measurements of body mass and dental and cranial shape. Divergence time was estimated from data on mitochondrial DNA restriction site polymorphisms. Our findings indicate that African jackals are morphologically similar despite having diverged more than 2 million years ago. By contrast, South American foxes differ substantially in both size and morphology after only 250,000 years of evolution. Thus, the lack of character divergence among the African jackals cannot be explained as a result of very recent common ancestry.

Animals↗
PubMed2000

Multigene phylogeny of land plants with special reference to bryophytes and the earliest land plants.

A widely held view of land plant relationships places liverworts as the first branch of the land plant tree, whereas some molecular analyses and a cladistic study of morphological characters indicate that hornworts are the earliest land plants. To help resolve this conflict, we used parsimony and likelihood methods to analyze a 6, 095-character data set composed of four genes (chloroplast rbcL and small-subunit rDNA from all three plant genomes) from all major land plant lineages. In all analyses, significant support was obtained for the monophyly of vascular plants, lycophytes, ferns (including PSILOTUM: and EQUISETUM:), seed plants, and angiosperms. Relationships among the three bryophyte lineages were unresolved in parsimony analyses in which all positions were included and weighted equally. However, in parsimony and likelihood analyses in which rbcL third-codon-position transitions were either excluded or downweighted (due to apparent saturation), hornworts were placed as sister to all other land plants, with mosses and liverworts jointly forming the second deepest lineage. Decay analyses and Kishino-Hasegawa tests of the third-position-excluded data set showed significant support for the hornwort-basal topology over several alternative topologies, including the commonly cited liverwort-basal topology. Among the four genes used, mitochondrial small-subunit rDNA showed the lowest homoplasy and alone recovered essentially the same topology as the multigene tree. This molecular phylogeny presents new opportunities to assess paleontological evidence and morphological innovations that occurred during the early evolution of terrestrial plants.

DNA, Mitochondrial↗
PubMed1988

Do woody plants operate near the point of catastrophic xylem dysfunction caused by dynamic water stress? : answers from a model.

We discuss the relationship between the dynamically changing tension gradients required to move water rapidly through the xylem conduits of plants and the proportion of conduits lost through embolism as a result of water tension. We consider the implications of this relationship to the water relations of trees. We have compiled quantitative data on the water relations, hydraulic architecture and vulnerability of embolism of four widely different species: Rhizophora mangle, Cassipourea elliptica, Acer saccharum, and Thuja occidentalis. Using these data, we modeled the dynamics of water flow and xylem blockage for these species. The model is specifically focused on the conditions required to generate ;runaway embolism,' whereby the blockage of xylem conduits through embolism leads to reduced hydraulic conductance causing increased tension in the remaining vessels and generating more tension in a vicious circle. The model predicted that all species operate near the point of catastrophic xylem failure due to dynamic water stress. The model supports Zimmermann's plant segmentation hypothesis. Zimmermann suggested that plants are designed hydraulically to sacrifice highly vulnerable minor branches and thus improve the water balance of remaining parts. The model results are discussed in terms of the morphology, hydraulic architecture, eco-physiology, and evolution of woody plants.

Journal Article↗
PubMed2003

Neuronal classes in the isocortex of a monotreme, the Australian echidna (Tachyglossus aculeatus).

We have used Valverde-Golgi and Golgi-Colonnier techniques to analyze cortical neuronal morphology in four regions (frontal cortex, primary motor cortex, primary somatosensory cortex, primary visual cortex) of the isocortex of the echidna (Tachyglossus aculeatus). Eight classes of neurons could be identified--pyramidal, spinous bipolar, aspinous bipolar, spinous bitufted, aspinous bitufted, spinous multipolar, aspinous multipolar and neurogliaform. All except the pyramidal neurons were morphologically similar to neuronal classes seen in eutherian and metatherian isocortex. Pyramidal neurons made up a small proportion of all cortical neurons encountered in our preparations of echidna cortex (34% in visual cortex, 35% in somatosensory cortex, 41% in frontal cortex and 49% in motor cortex) compared to both reported values in eutherian cortex and values we found in rat cortex impregnations prepared in an identical fashion to the echidna material (75% in rat motor and 78% in rat somatosensory cortex). Many pyramidal neurons in the echidna isocortex were atypical (30-42% depending on region) with inverted somata, short or branching apical dendrites and/or few basal dendrites, very different from the usual pyramidal neuron morphology in eutherian cortex. Dendritic spine density on apical and basal dendrites of echidna pyramidal neurons in somatosensory cortex and apical dendrites of motor cortex pyramidal neurons was also lower than that found in the rat. The present findings are consistent with both pyramidal neurons and the many diverse types of non-pyramidal neurons having already emerged as discrete morphological entities very early in mammalian cortical evolution, at the time of divergence of the therian and prototherian lineage.

Animals↗
PubMed2005

Was Darwin a creationist?

Throughout the Origin of Species, Darwin contrasts his theory of natural selection with the theory that God independently created each species. This makes it seem as though the Origin offers a scientific alternative to a theological worldview. A few months after the Origin appeared, however, the eminent anatomist Richard Owen published a review that pointed out the theological assumptions of Darwin's theory. Owen worked in the tradition of rational morphology, within which one might suggest that evolution occurs by processes that are continuous with those by which life arises from matter; in contrast, Darwin rested his account of life's origins on the notion that God created one or a few life forms upon which natural selection could act. Owen argued that Darwin's reliance on God to explain the origins of life makes his version of evolution no less supernatural than the special creationist that Darwin criticizes: although Darwin limits God to one or a few acts of creation, he still relies upon God to explain life's existence.

Biological Evolution↗
PubMed2001

Delayed costs of an induced defense in tadpoles? Morphology, hopping, and development rate at metamorphosis.

Models for the evolution of plasticity predict that individuals having phenotypes induced by exposure to enemies should experience relatively low fitness when enemies are absent. However, costs of induced phenotypes have been difficult to find in both plants and animals, perhaps because costs are expressed at later stages in the life cycle. We searched for delayed costs of an induced defense in larvae of the water frog Rana ridibunda, which exhibits strong phenotypic responses to predators. Tadpoles grew to metamorphosis in outdoor artificial ponds, in either the presence or absence of Aeshna dragonfly larvae confined within cages. We collected metamorphs at forelimb emergence, estimated their development rate until tail resorption was complete, and measured their body and leg shape and hopping performance. Development rate through metamorphosis reflects the duration of a transitional period during which metamorphs are especially vulnerable to predators, and hopping performance may reflect ability to escape predators. Froglets from the dragonfly treatment lost mass through metamorphosis significantly faster than those from predator-free ponds, but they resorbed their tails at about the same rate, despite the fact that their tails were relatively large to begin with. Froglets developing from predator-induced tadpoles had shorter, more muscular legs, and hopped 5% longer distances (difference not significant). Therefore, producing an induced defense against insect predators during the tadpole stage did not exact a cost during or immediately after metamorphosis; if anything, tadpoles with the predator-induced phenotype gave rise to more vigorous froglets. These results focus attention on other costs of the induced phenotype, as well as alternative explanations for plasticity that do not rely on direct fitness trade-offs.

Animals↗
PubMed2003

Intra- and interspecific genetic complexities of two Eothenomys species in Honshu, Japan.

Differences in the nuclear ribosomal DNA (rDNA), mitochondrial DNA (mtDNA), cytochrome b (Cytb), and Y chromosomal Sry genes were used to assess intra- and interspecific relationships in two Japanese red-backed voles, Eothenomys andersoni and E. smithii, focusing on areas where the two species might come into contact. In the Kii Peninsula, southwestern Honshu, which contains an allopatric population of E. andersoni isolated from its main range, the rDNA-RFLP data provide robust evidence of past mutual interspecific gene introgression, while the Cytb and Sry sequences were specific to this population. In central Honshu, where E. andersoni and E. smithii inhabit higher and lower altitudes, respectively, with a narrow sympatric zone, the rDNA-RFLP and Sry variation was specific for each species, while introgression of the mtDNA from E. smithii to E. andersoni was seen. These complex patterns in the gene markers are consistent with our previous notions derived from sex chromosome variation. Our previous and present data strongly suggest that the evolution of these vole species, which are morphologically and cytogenetically distinct, involves complex genetic interactions and the resultant combinations of genes are sometimes peculiar, mainly due to the Cytb haplotypes. However, phylogenetic analysis using a combination of maternal, paternal, and biparental markers has proven useful for understanding the evolutionary history given the complex phylogenetic background.

Animals↗
PubMedDate not supplied

[Temporomandibular joint involvement in juvenile idiopathic arthritis: treatment with an orthodontic appliance].

OBJECTIVE: About 65% of children suffering from juvenile idiopathic arthritis (JIA) shows a more or less marked involvement of temporo-mandibular joint (TMJ) with altered mandibular growth, resorption of the condyles, occlusary instability, reduced chewing ability and facial dysmorphia. The purpose of our study is to prevent and to treat the progressive evolution of JIA on craniofacial growth and morphology with a functional appliance; surgery should be considered only in so far as the adequacy of TMJ movement is concerned. METHODS: From 1992 until now 72 children with proved JIA and TMJ involvement have been treated (50 females, 22 males, aged 6 to 16 years old). TMJ involvement was bilateral in 61% and unilateral in 39% of patients. A diagnostic workup was carried out involving tomograms of TMJ and cephalometric radiograph and analysis. The authors used a bimaxillary activator in the attempt to modify the unfavourable growth pattern and provide a gradual ante-rotation of the jaw. RESULTS: Almost all JIA patients showed satisfactory long term results, easing of pain, reduced skeletal discrepancy, increased function and good facial profile. CONCLUSIONS: The long term results of this study indicate that orthopaedic therapy might control the vicious circle of the malocclusion in children with JIA, preventing exacerbation of mandibular clockwise rotation. Surgical intervention for the improvement of TMJ function should be considered only if a severe restricted state is imminent.

Adolescent↗
PubMed1999

[Diagnosis and endovascular treatment of thoracic aortic diseases].

Recent years have seen the emergence of non-invasive imaging techniques for the morphological assessment of the thoracic aorta. This evolution results in an important reduction of the role of diagnostic angiography. Simultaneously, thanks to a tremendous technologic development, endovascular treatment techniques concern nowadays some pathologic conditions of the descending aorta. A number of reports using a variety of devices have been published in the literature concerning the treatment of dissection and aortic aneurysm. Based on mid-term results, endoluminal repair with use of stent-grafts is a feasible and safe alternative to surgery with a low rate of morbidity and mortality. In type B dissections with end-organ involvement, interventional radiology can be used either to fenestrate the flap or to stent the flap in branch arteries. Proper selection of patients by non-invasive imaging is fundamental for successful endoluminal treatment. However, there is still major concern with respect to long term results of these new treatments.

Adult↗
PubMed2000

Genome-wide search for loss of heterozygosity using laser capture microdissected tissue of breast carcinoma: an implication for mutator phenotype and breast cancer pathogenesis.

Breast cancer is considered to display a high degree of intratumor heterogeneity, without any obvious morphological and pathological steps to define sequential evolution, and its progression may vary among individual tumors. In an attempt to elucidate these etiological and phenotypic complexities, the present study, based on the fundamental concept that genomic instability is the engine of both tumor progression and tumor heterogeneity, was conducted to test the hypothesis that breast cancer pathogenesis is driven by double-strand break (DSB)-initiated chromosome instability (CIN). The rationale underlying this hypothesis is derived from the clues provided by family breast cancer syndromes, in which susceptibility genes, including p53, ATM, BRCA1 and BRCA2, are involved within the common functional pathway of DSB-related checkpoint/ repair. Because genomic deletion caused by DSB is reflected in the genetic mechanism of loss of heterozygosity (LOH), this genome-wide LOH study was conducted, using 100 tumors and 400 microsatellite markers. To minimize the effect of heterogeneity within tumors, the experimental technique of laser capture microdissection was used to ensure that genetic and phenotypic examinations were based on the same tumor cells. Support for our hypothesis comes from the observations that: (a) the extent of DSB-initiated CIN in tumors significantly increased as tumors progressed to poorer grades or later stages; (b) in the sequential steps toward CIN, the loci of p53 and ATM, the key checkpoint genes against DSB, were lost at the earliest stage; and (c) many loci identified to be important in breast tumorigenesis were the genomic sites possibly harboring the genes involved in DSB-related checkpoint/repair (including RAD51, RAD52, and BRCA1) or CIN (including FA-A, FA-D, and WRN), and a higher number of these loci showing LOH was significantly associated with increased level of DSB-initiated CIN (P < 0.0001). Breast cancers are thus considered to be sequentially progressive with CIN. However, CIN might also cause genetic heterogeneity, which was revealed by the findings that LOH at some markers was observed only in the component of ductal carcinoma in situ but not in the invasive component of the same tumors. In addition, some markers were found to preferentially lose at specific tumor grades, implying their contribution to genetic heterogeneity during tumor development. Therefore, this study suggests that breast cancer progression is clonal with regard to CIN, but different breast cancers would present distinct molecular profiles resulting from genetic heterogeneity caused by CIN.

Adult↗
PubMed1992

[Diagnostic evaluation of cervical adenopathies in childhood].

Between 1985 and 1990, 45 children were studied in an inpatient basis hospital because of cervical lymphadenopathy. This was the most important clinical sign in these patients. Forty-three had true adenitis. In the others, one was submaxillitis and one a sarcoma. The age range was from 2.1 to 13.3 years. Seven children (16%) had neoplastic adenitis (2 papillary carcinoma of the thyroid, 4 Hodgkin's lymphoma and one non-Hodgkin's lymphoma). Thirty-six patients had benign disorders (18 mononucleosis infections, 7 nonspecific adenitis, 5 infections of mycobacteria, 2 of toxoplasma and 2 of rickettsia, one cervical Whipple and one desmopathic adenitis). We did no find any differences related to age or morphological characteristics of the lymph nodes. The evolution time in patients with malignant tumors was 16.4 weeks and 9.6 weeks in the benign group. All of the cases with supraclavicular location had a lymphoma. The mean LDH in patients with malignant tumors was 214 U/L and 614 U/L in those with non-malignant tumors (p < 0.01).

Anti-Inflammatory Agents↗
PubMed1976

[Fetal and neo-natal development of brown adipose tissue in guinea pigs and rats. Feto-maternal or milk transfer of essential fatty acids : lipogenesis and morphology (author's transl)].

Brown adipose tissue (BAT) lipogenesis (fatty acid, glycerol and CO2 synthesis) and its morphology determined by optical microscopy, were studied in guinea pigs and rats during intra-uterine life and during the suckling period. Following the receptor induction and after the commencement of the hormone sensitive adenylate-cyclase/lipase system (i.e. on the 60th day in guinea pigs, on the 20th day in rats), the fetal BAT releases fatty acids (NEFA) and is capable of allowing the non-shivering thermogenesis. When the maternal diet and, consequently, the fetal or neonatal BAT are supplied with considerable linoleic acid, NEFA contain a large proportion of essential fatty acids. In vitro, the greater the linoleic acid concentration in these NEFA, the less inhibited is the lipogenesis from (2-14C) pyruvate. Thus, in periods just preceding or succeeding birth, fatty acid and glycerol synthesis are higher when the feto-maternal and/or the milk supply are enriched in linoleic acid than when they contain a large proportion of endogenous fatty acids. Morphological studies indicate that the adipose cell evolution could be nonidentical in BAT more or less enriched in essential fatty acids. Linoleic enriched BAT (of animals born to females kept on a sunflower oil diet) seemed to be in a healthy physiological state at birth, perhaps due to rapid lipid renewal and synthesis in their membranes. The control BAT (of animals born to females kept on a lard diet) appeared loaded with fats and in a worse conservation state at the same age.

Adipose Tissue, Brown↗
PubMedDate not supplied

[Epithelial attachment and subperiosteal implants].

The case presented is a subperiosteal implantation in a human being, in chrome cobalt mollybdenum, with two years and a half of evolution. It has been studied from the morphological point of view on being extracted for the patient's request, because of a prosthetic maladjustment; the existence of a epitheliarl adhesion and the subjacen tissue reaction have been documented.

Dental Implantation, Subperiosteal↗
PubMed1991

Connective tissue changes in rheumatic heart disease.

The connective matrix of 17 surgically excised mitral complexes from patients with clinical diagnosis of rheumatic carditis was evaluated by semi-quantitative histopathological, immunohistochemical and ultrastructural parameters. Different and concomitant patterns of loose and dense fibrosis were observed with variable constitution and organization of collagen I, III, IV, procollagen III, laminin, fibronectin and elastin. Loose fibrosis exhibited codistribution of all matrix components, Initial phase of fibrosis was characterized by deposition of all matrix components organized in a network pattern. In dense fibrosis a parallel disposition of type I collagen bundles predominated. In the denser (hyalin) fibrosis, the collagen exhibited abnormalities in fiber diameters and in fiber conformation (hyperfibers) and there was reduction or disappearance of other matrix components. The presence of these different kinds of connective matrix and the ultrastructural alterations in collagen fibers are associated to different stages of fibrosis organization and probably reflect changes in collagen susceptibility to degradation. These morphologic patterns may be related to the evolution (stability or reversibility) of rheumatic sequelae.

Adolescent↗
PubMed1989

[Congenital contractural arachnodactyly. Report of 2 clinical cases].

Two unrelated male children, aged 15 and 2 months, with congenital contractural arachnodactyly (CCA) are described. CCA is an autosomal dominant disorder of benign evolution, affects the connective tissue and its morphologic phenotype is similar to Marfan syndrome. Differential diagnosis and management are discussed.

Bone Diseases, Developmental↗
PubMed1977

[Valvular insufficiency after venous thrombosis. Experimental study].

Venous thrombosis can produce lesions of valvular cusps which are generally ascribe to the phase of thrombus organization. Valvular lesions hold a very important role in the genesis of the post phlebitic chronic venous insufficiency. Experimental thrombosis had been induced in dogs with electrical stimulation of femoral veins to study morphological aspects of valvular cusps in various evolutive phases of thrombosis. Results emphasize too early onset and quick evolution of valvular damage. It can contribute to explain frequent failures of attempted therapy about prevention of post phlebitic syndromes.

Animals↗