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PubMed2006

Molybdenum trioxide nanostructures: the evolution from helical nanosheets to crosslike nanoflowers to nanobelts.

MoO(3) nanostructures with different morphologies, such as helical nanosheets, crosslike nanoflowers, and nanobelts, have been synthesized on a large scale by an environmentally friendly chemical route. The evolution process from helical nanosheets to crosslike nanoflowers to nanobelts is observed for the first time. The influences of reaction time and the molar ratio of molybdenum and H(2)O(2) on the morphologies of MoO(3) nanostructures have been investigated. The synthetic process is environmentally friendly and may be extended to synthesize nanostructures of other metal (W, Ti, and Cr) oxides.

Journal Article↗
PubMedDate not supplied

[Clinical study of white atrophy: the viewpoint of the phlebologist].

After giving a clinical description of Millian's white atrophy, its preferred locations and the area in which it develops (post-phlebitic or non-post-phlebitic chronic venous deficiency), the author distinguishes: a benign, non-evolutive form; forms of pseudo white atrophy, of identical morphology, of different development in which a tableau of acute inflamed hypodermititis develops towards hyperalgic ulceration; intermediate forms of more chronic development; non-evolutive forms, such as certain ulcer scars. If it is impossible to predict the developmental capacity of a plaque of white atrophy, it is nevertheless crucial to prescribe in all cases a well adapted elastic support, as this is the only way to avoid the majority of complications and, sometimes, to obtain a certain degree of reversibility.

Atrophy↗
PubMed1993

[Apophysitis of the iliac crest. A little known cause of low back pain and pelvic pain in children].

The authors describe an iliac osteochondrosis in 98 teenagers aged of 12 to 17 years, responsible for anterior, medial or posterior pains of pelvis and the lumbar zone, squaring with the period of ossification of the iliac crest. The spontaneous pain was revived by pressing a precise zone of the iliac crest. These pains have the usual characteristics of the pains of ossification of apophysis. The identification of the characteristics allows to avoid any further investigation which will have to be realised in case of doubt or modification of the evoluting symtomatology. It is to recognize this cause of pain so as not to attribute it to a regional morphological anomaly that may lead to excessive surgical indications. The evolution was constantly favourable after a few weeks delay. Only a momentary and adapted restriction of sporting activities is justified.

Adolescent↗
PubMedDate not supplied

Animal phylogeny and the ancestry of bilaterians: inferences from morphology and 18S rDNA gene sequences.

Insight into the origin and early evolution of the animal phyla requires an understanding of how animal groups are related to one another. Thus, we set out to explore animal phylogeny by analyzing with maximum parsimony 138 morphological characters from 40 metazoan groups, and 304 18S rDNA sequences, both separately and together. Both types of data agree that arthropods are not closely related to annelids: the former group with nematodes and other molting animals (Ecdysozoa), and the latter group with molluscs and other taxa with spiral cleavage. Furthermore, neither brachiopods nor chaetognaths group with deuterostomes; brachiopods are allied with the molluscs and annelids (Lophotrochozoa), whereas chaetognaths are allied with the ecdysozoans. The major discordance between the two types of data concerns the rooting of the bilaterians, and the bilaterian sister-taxon. Morphology suggests that the root is between deuterostomes and protostomes, with ctenophores the bilaterian sister-group, whereas 18S rDNA suggests that the root is within the Lophotrochozoa with acoel flatworms and gnathostomulids as basal bilaterians, and with cnidarians the bilaterian sister-group. We suggest that this basal position of acoels and gnathostomulids is artifactal because for 1,000 replicate phylogenetic analyses with one random sequence as outgroup, the majority root with an acoel flatworm or gnathostomulid as the basal ingroup lineage. When these problematic taxa are eliminated from the matrix, the combined analysis suggests that the root lies between the deuterostomes and protostomes, and Ctenophora is the bilaterian sister-group. We suggest that because chaetognaths and lophophorates, taxa traditionally allied with deuterostomes, occupy basal positions within their respective protostomian clades, deuterostomy most likely represents a suite of characters plesiomorphic for bilaterians.

Animals↗
PubMed2003

Evo-Devo: the long and winding road.

Evolutionary developmental biology (Evo-Devo) aims to unveil how developmental processes and mechanisms become modified during evolution and how from these changes the past and present biodiversity arose. The first wave of Evo-Devo identified a conserved set of toolkits common to most metazoans. The present second wave has changed gear and aims to identify how genes and modules were used differently through evolution to build the past and present morphological diversity. The burgeoning third wave is introducing experimental testing of predictions drawn from the first and second waves. Here we review some of the hottest topics, contributions and insights of present Evo-Devo related to basic concepts and paradigms of evolutionary research. Future directions of Evo-Devo are also highlighted; in other words, Quo Vadis, Evo-Devo?

Animals↗
PubMed1975

[Morphological and functional variations of the muscles of invertebrates].

The problem of muscle evolution among Invertebrates has been considered, mainly in obliquely strated fibers of Annelida and in trasversally striated fibers of Insecta. In both groups the morphological variations run parallel to the functional requirements; similar modulations, in fact, have been observed in fast and slow acting muscle fibers independently from the basic pattern of Insecta and Annelida fibers. Fast acting muscles are characterized by a lesser diameter of myosin filaments and a low thin-to-thick filament ratio. On the contrary, the slow acting muscles show a greater diameter of the myosin filaments and a higher thin-to-thick filament ratio. These observations agree with the hypothesis of a common origin of almost all muscular systems.

Animals↗
PubMed2005

Comparative analysis of morphological diversity: does disparity accumulate at the same rate in two lineages of centrarchid fishes?

Evolutionary lineages differ with regard to the variety of forms they exhibit. We investigated whether comparisons of morphological diversity can be used to identify differences in ecological diversity in two sister clades of centrarchid fishes. Species in the Lepomis clade (sunfishes) feed on a wider range of prey items than species in the Micropterus clade (black basses). We quantified disparity in morphology of the feeding apparatus as within-clade variance on principal components and found that Lepomis exhibits 4.4 and 7.4 times more variance than Micropterus on the first two principal components. However, lineages are expected to diversify morphologically and ecologically given enough time, and this pattern could have arisen due to differences in the amount of time each clade has had to accumulate variance. Despite being sister groups, the age of the most recent common ancestor of Lepomis is approximately 14.6 million years ago and its lineages have a total length of 86.4 million years while the age of the most recent common ancestor of Micropterus is only about 8.4 million years ago, and it has a total branch length of 42.9 million years. We used the Brownian motion model of character evolution to test the hypothesis that time of independent evolution of each clade's lineages accounts for differences in morphological disparity and determined that the rates of evolution of the first two principal components are 4.4 and 7.7 times greater in Lepomis. Thus, time and phylogeny do not account for the differences in morphological disparity observed in Lepomis and Micropterus, and other diversity-promoting mechanisms should be investigated.

Adaptation, Biological↗
PubMed2005

A nuclear DNA phylogenetic perspective on the evolution of echolocation and historical biogeography of extant bats (chiroptera).

Bats (Order Chiroptera), the only mammals capable of powered flight and sophisticated laryngeal echolocation, represent one of the most species-rich and ubiquitous orders of mammals. However, phylogenetic relationships within this group are poorly resolved. A robust evolutionary tree of Chiroptera is essential for evaluating the phylogeny of echolocation within Chiroptera, as well as for understanding their biogeographical history. We generated 4 kb of sequence data from portions of four novel nuclear intron markers for multiple representatives of 17 of the 18 recognized extant bat families, as well as the putative bat family Miniopteridae. Three echolocation-call characters were examined by mapping them onto the combined topology: (1) high-duty cycle versus low-duty cycle, (2) high-intensity versus low-intensity call emission, and (3) oral versus nasal emission. Echolocation seems to be highly convergent, and the mapping of echolocation-call design onto our phylogeny does not appear to resolve the question of whether echolocation had a single or two origins. Fossil taxa may also provide insight into the evolution of bats; we therefore evaluate 195 morphological characters in light of our nuclear DNA phylogeny. All but 24 of the morphological characters were found to be homoplasious when mapped onto the supermatrix topology, while the remaining characters provided insufficient information to reconstruct the placement of the fossil bat taxa with respect to extant families. However, a morphological synapomorphy characterizing the Rhinolophoidea was identified and is suggestive of a separate origin of echolocation in this clade. Dispersal-Vicariance analysis together with a relaxed Bayesian clock were used to evaluate possible biogeographic scenarios that could account for the current distribution pattern of extant bat families. Africa was reconstructed as the center of origin of modern-day bat families.

Amino Acid Sequence↗
PubMedDate not supplied

Functional consequences of chronic implantation of electrodes for electromyographic studies in the gastrointestinal tract of chickens.

The aims of this work were: A) to define the morphological and functional changes induced by chronic implantation of electrodes for electromyographic studies and B) to study the evolution of the gastrointestinal myoelectrical activity after electrode implantation. Four lots of animals were established: birds implanted with 7 and 5 triplets of electrodes in the gastroduodenal area (lots I5 and I7 respectively); sham operated birds (lot SH) and control (lot C). Body weight was not modified by surgery. Food intake, which was transiently decreased, returned to normal within the first week post-implantation. Gastrointestinal transit time (TT) was significantly increased in lots I7 and SH during the first week. In SH birds TT returned to normal in the second week after surgery, whereas in I7 birds this parameter was not normalized until the third week. Apparent hypertrophy of the duodenum was found in lot I7 but not in lots SH and C (P < 0.05). Qualitative electromyographical changes were found in lot I7 but not in lot I5, with no morphological changes. The evolution of the electrical signal (frequency and amplitude of spiking) was analyzed in lot I5. Frequency stabilized shortly after surgery (0.8-2 days). In contrast, amplitude increased progressively to reach a steady value 9-18 days after surgery. Our results indicate that the number of electrodes implanted for electromyographical studies may induce significant morphological as well as motor changes in the gastrointestinal tract. Thus there should be as few electrodes as possible in order to avoid the changes mentioned above.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed2004

Acute coronary syndromes in smokers: clinical and angiographic characteristics.

UNLABELLED: Smoking is a major and reversible risk factor for coronary artery disease. The present work aims to define the risk factors, angiographic and clinical characteristics and evolution of acute coronary syndromes in smokers. METHODS: We studied 521 consecutive patients with acute coronary syndrome admitted to the intensive care unit who underwent catheterization. We assessed the population in terms of risk factors, pathology (unstable angina or acute myocardial infarction), coronary morphology, left ventricular function, the need for intervention, evolution and complications over a one-year period. The characteristics of smokers were then compared with those of non-smokers. RESULTS: Of the 521 patients with acute coronary syndrome (391 men), 182 (35 %) were smokers. The smokers were younger than the non-smokers (56.3+/-9.5 versus 66.4 +/- 7.8; p < 0.001), were more frequently male (91 versus 66%; p < 0.001), and presented more risk factors (43% with 3 or more risk factors versus 17% in non-smokers; p < 0.001), more obesity (11 versus 5%; p < 0.01), and less diabetes (19 versus 37%; p < 0.001). Smokers presented greater prevalence of acute myocardial infarction (57 versus 40%; p < 0.001) and less unstable angina. Coronary morphology was not significantly different in smokers compared to non- smokers and left ventricular function after the aculte coronary syndrome was similar in both groups. Smokers less frequently underwent surgery during hospitalization (22% versus 35%; p < 0.01) but needed angioplasty as often as non-smokers (48% versus 16%; NS). Smokers presented more frequent complications (angina, heart failure, re-infarction or CABG) than non-smokers (26% versus 17%; p < 0.01), during the first year of follow-up. One-year mortality was similar in both groups. The results were not significantly different when adjusted for gender. CONCLUSIONS: On average, acute coronary syndrome occurred 10 years earlier in smokers than in non-smokers. The former generally presented more risk factors, lower prevalence of diabetes and higher of obesity, more myocardial infarctions and less unstable angina. After the acute coronary syndrome, at one year, smokers presented more complications than non-smokers but had similar mortality.

Acute Disease↗
PubMed1990

Quantitative analysis of prostatic intraepithelial neoplasia on tissue sections.

The changes in nuclear morphology (karyometry) and DNA content in prostatic intraepithelial neoplasia (PIN) were analyzed on tissue sections. The cases of PIN were subdivided into PIN 1 and PIN 2 based on the degree of proliferation and the anaplasia of the secretory cells lining the ducts and acini. Cases of nodular hyperplasia (NH) and adenocarcinoma were also studied for comparative purposes. Karyometric analysis showed a progression of most values from NH to PIN to carcinoma. The DNA analysis showed a decrease in the frequency of nuclei in the diploid range and an increase in the percentage of nuclei in the other ploidy regions (especially between 2c and 4c and in the tetraploid range) from NH to PIN to carcinoma. Forward stepwise discriminant analysis showed similarities between NH and PIN 1 and between PIN 2 and carcinoma. These findings suggest that the evolution towards adenocarcinoma is characterized by progressive morphologic derangements of the nuclei and by the transformation of the diploid DNA content into a nondiploid one, with the changes taking place at the level of PIN 2.

Adenocarcinoma↗
PubMed1992

The maintenance of single-locus polymorphism. IV. Models with mutation from existing alleles.

The ability of viability selection to maintain allelic polymorphism is investigated using a constructionist approach. In extensions to the models we have previously proposed, a population is bombarded with a series of mutations whose fitnesses in conjunction with other alleles are functions of the corresponding fitnesses with a particular allele, the parent allele, already in the population. Allele frequencies are iterated simultaneously, thus allowing alleles to be driven to extinction by selection. Such models allow very high levels of polymorphism to evolve: up to 38 alleles in one case. Alleles that are lethal as homozygotes can evolve to surprisingly high frequencies. The joint evolution of allele frequencies and viabilities highlights the necessity to consider more than the current morphology of a population. Comparisons are made with the neutral theory of evolution and it is suggested that failure to reject neutrality using the Ewens-Watterson test cannot be regarded as evidence for the neutral theory.

Mathematics↗
PubMed1984

Development of the lymph nodes in the very young, and their evolution in the mature, nude rat.

We recently revised the concepts on the morphology of the lymph nodes of the young adult athymic nude rat. The present work studied the postnatal development of its nodal structures and their evolution with aging. The structural development of the deep cortex "units" was found to progress as usual. However, while the concentration of lymphocytes appeared to develop normally in the periphery of a unit, the center of the unit remained lymphocyte-depleted. Further, the peripheral cortex failed to develop over the middle part of a unit center. With aging, the peripheral cortex over the remainder of a unit center could atrophy and disappear completely. The present findings did not yield information as to whether thymic elements are necessary to trigger the development of a unit, but they revealed that its further development is determined by stimuli. It was concluded that, in the absence of T-cells, stimuli for cellular immune responses provoke the proliferation of the reticular or interdigitating cells of a unit center. On the other hand, an increase of these stimuli was concluded to cause the peripheral cortex to fail to develop over part of a unit center and, later, to atrophy over the remainder of the unit center. The mechanisms of the phenomena are discussed.

Aging↗
PubMed2000

Molecular phylogenetic analysis of the Pneumoroidea (Orthoptera, Caelifera): molecular data resolve morphological character conflicts in the basal acridomorpha.

A key transition in the evolution of the insect suborder Caelifera (Orthoptera; Insecta) was from predominantly non-angiosperm-feeding basal lineages to the modern acridomorph fauna (grasshoppers and related insects). However, because of conflicts in the distribution of several complex morphological characters, the relationships of the presumed intermediates, and in particular of the superfamily Pneumoroidea, are presently unclear. We undertook a phylogenetic study of representatives of all of the transitional acridomorph families using mitochondrial and nuclear DNA sequences. No support for pneumoroid monophyly was obtained from nonparametric bootstrap analysis. Furthermore, adopting a maximum-likelihood approach, specific hypotheses of relationships within the Pneumoroidea were firmly rejected using parametric bootstrapping and Kishino-Hasegawa tests. The results indicate that the Pneumoroidea are at best a grade. This distinction implies that the evolution of the proposed pneumoroid synapomorphies, femoro-abdominal stridulation and simple male genital structure, might previously have been misinterpreted as cases of single character gains or losses within lineages. Reconstructions of character states for the femoro-abdominal stridulation indicate that, in fact, multiple losses or gains are equally likely. An important implication of our findings is that, in grasshoppers, auditory tympana may have evolved before stridulation, supporting the argument that the original function of tympana may have been related not to conspecific communication but to predator detection. Overall, the results of this study emphasize the high information content of these minor groups (in this case, the four intermediate families under consideration contain only 0.2% of extant orthopteran species diversity). Our analyses also demonstrate the advantages of model-based methods in analyzing systematic problems and, in particular, of the importance of testing specific phylogenetic hypotheses when a priori support for groupings (e.g., from nonparametric bootstrapping) is marginal.

Animals↗
PubMed1992

The evolution of eutherian spermatozoa and underlying selective forces: female selection and sperm competition.

We have examined sperm morphology and dimensions in Eutherian mammals. In most Eutherians, sperm heads are round or oval and spermatozoa have short tails (average sperm length about 65 microns; range = 33-121 microns). Rodents, however, clearly depart from the typical Eutherian pattern in that they show a broad array of head morphs and an extreme range of sperm dimensions (35-250 microns). In order to trace the evolutionary changes that rodent sperm have undergone, we have used phylogenetic relationships based on biogeographical, morphological, chromosomal and genic data, and we have superimposed onto them the information available on sperm traits. Analyses were carried out for five rodent groups on which enough information was available. The evolutionary trends which emerged from these studies have two main points in common: throughout evolution spermatozoa have become enlarged and morphologically more complex, and this process seems to have taken place independently in different lineages. A general model was developed which outlines the different evolutionary pathways that rodent sperm have undergone. The adaptive significance of the increase in head complexity and the elongation of the sperm tail remains obscure. We have integrated information from evolutionary, physiological and behavioural studies to address this issue. We argue that two main selective forces may have favoured these changes: female selection within the reproductive tract and sperm competition. The female tract represents a formidable barrier for spermatozoa and its provides an environment where numerous interactions take place. The extent of these barriers and the complexity of these poorly understood interactions suggest that females may be exercising a strong selection, which may enable them to favour particular types of spermatozoa or ejaculates from particular males. Throughout their evolution males must have evolved adaptations to overcome these barriers, and the conflicting interests of choosy females. Sperm competition is a potent evolutionary force among mammals, which has influenced not only the evolution of sperm numbers but also changes in sperm dimensions. Thus, sperm competition has favoured the elongation of the sperm tail, which has led to the attainment of faster swimming speed, an important factor when sperm from rival males compete to reach the ova first.

Animals↗
PubMed2003

Diversification of brain and sense organ morphology in Antarctic dragonfishes (Perciformes: Notothenioidei: Bathydraconidae).

In the subzero shelf waters of Antarctica, fishes of the perciform suborder Notothenioidei dominate the fish fauna and constitute an adaptive radiation and a species flock. The 16 species of dragonfishes of the family Bathydraconidae live from surface waters to nearly 3,000 m and have the greatest overall depth range among notothenioid families. We examined the anatomy and histology of the brain, retina, and cephalic lateral line system of nine bathydraconid species representing 8 of the 11 known genera. We evaluate these data against a cladogram identifying three clades in the family. We provide a detailed drawing of the brain and cranial nerves of Gymnodraco acuticeps and Akarotaxis nudiceps. Bathydraconid brain morphology falls into two categories. Brains of most species are similar to those of generalized perciforms and some basal notothenioids (Class I). However, brains of deep-living bathydraconids (members of the tribe Bathydraconini minus Prionodraco) have a reduced telencephalon and tectum that renders the neural axis visible - the stalked brain morphology (Class II). All bathydraconids have duplex (rod and cone) retinae but there is considerable interspecific variation in the ratio of cones:rods and in the number of cells in the internal nuclear layer. Retinal histology reflects habitat depth but is not tightly coupled to phylogeny. Although the deep-living species of Bathydraconini have rod-dominated retinae, the retinae of some sister species are photopic. An expanded cephalic lateral line system is also characteristic of all members of the Bathydraconini as exemplified by Akarotaxis. This morphology includes large lateral line pores, wide membranous canals, hypertrophied canal neuromasts, and large anterodorsal lateral line nerves, eminentia granulares, and crista cerebellares. The saccular otoliths are also enlarged in members of this tribe. Neural diversification among bathydraconids on the Antarctic shelf has not involved the evolution of sensory specialists. Brain and sense organ morphologies do not approach the specialized condition seen in primary deep-sea fishes or even that of some secondary deep-sea fishes including sympatric non-notothenioids such as liparids (snailfishes) and muraenolepidids (eel cods). The brains and sense organs of bathydraconids, including the deep-living species, reflect their heritage as perciform shorefishes.

Anatomy, Comparative↗
PubMed2004

The genetics of floral divergence and postzygotic barriers between outcrossing and selfing populations of Arenaria uniflora (Caryophyllaceae).

The genetic architecture of floral traits involved in the evolution of self-pollination provides a window into past processes of mating system divergence. In this study, we use two generations of crosses between highly selfing and predominantly outcrossing populations of Arenaria uniflora (Caryophyllaceae) to determine the minimum number, average dominance relationships, and pleiotropic effects of genetic factors involved in floral divergence. Comparison of the F1 and F2 phenotypic means with the expectations of a completely additive model of gene action revealed a primarily additive genetic basis for floral characters associated with mating system variation. The exception was flower life span, which showed partial dominance of the outcrosser phenology. In contrast to similarly divergent species, the substantial differences in flower size between these A. uniflora populations appear to involve relatively few genes of large effect (minimum number of effective factors = 2.2 +/- 2.8 SE). In addition, correlations among traits in the F2 generation indicate that pleiotropy may be an important feature of the genetic architecture of floral evolution in A. uniflora. The evolution of selfing via major modifiers of floral morphology is consistent with other evidence for ecological selection for preemptive self-pollination in A. uniflora. Analyses of the genetic basis of autonomous selfing were complicated by hybrid breakdown in both F1 and F2 generations. Only F1 hybrids showed reductions in female fertility, but about 30% of F1 and F2 hybrids exhibited partial or complete male sterility. Male sterile flowers were characterized by short stamens, reduced petals, and a lack of protandry, as well as indehiscent anthers. This morphological breakdown mimics environmental disruptions of floral development and may result from novel genic interactions in hybrids.

Analysis of Variance↗
PubMed1983

Size and diet in the evolution of African ape craniodental form.

Interspecific differences in craniodental morphology among Pan paniscus, Pan troglodytes, and Gorilla gorilla are analyzed. These apes differ in both diet and body size, and thus present an excellent example in which to apply an allometric criterion of subtraction in order to determine morphological differences which might be related to divergent dietary specialization. The use of ontogenetic allometry in particular as a criterion of subtraction is discussed. Bivariate and multivariate results indicate that most of the variation in skull form among the species relates to the extension of a common growth trend to different sizes. Comparative analysis of growth trajectories reveals a number of differences, but none that appear to relate to a reorganization of skull proportions which might correspond to a dietary shift towards increased folivory. The dentition clearly exhibits non-allometric shape changes corresponding to the dietary differences, however. The meaning of these differences between cranial and dental patterns is discussed.

Africa↗