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At least 973 records · Page 54Linked to original sources
PubMed1999

Anisophylly and Dorsiventral Shoot Symmetry.

Anisophylly is a special case of shoot dorsiventral symmetry in which leaf size and form differ between dorsal and ventral sides of the shoot. Anisophylly is normally coupled with leaf and stem asymmetry, modified phyllotaxis, and anisoclady. Anisophylly may be expressed throughout the shoot system (habitual anisophylly) or restricted to lateral shoots (lateral anisophylly). The combination of anisophylly, shoot dorsiventrality, and plagiotropy has arisen numerous times during evolution of the land plants, most notably in the primarily tropical families of Acanthaceae, Gesneriaceae, Melastomataceae, and Urticaceae. It is thought to represent an adaptation that maximizes light capture in dimly lit understories. In species for which anisophylly is an intrinsic expression of overall shoot symmetry, anisophylly and associated features of shoot dorsiventrality are expressed early in development. In contrast, when expression of anisophylly depends on growth conditions, anisophylly is secondarily imposed on early isophyllous leaf development. Despite more than a century of experimentation, very little is understood about the physiological control of anisophylly and dorsiventrality. Development of these features requires regulated suppression of some parts of the shoot and stimulation of others. Shifts in the temporal and spatial patterns of growth suppression and enhancement occur during both the ontogeny of an individual and during evolutionary change. Elucidating these processes for anisophyllous shoot development also should have broader significance for understanding the evolution of other morphological innovations.

Journal Article↗
PubMed1990

Richter's syndrome presenting as primary central nervous system lymphoma. Transformation of an identical clone.

The development of a central nervous system (CNS) large cell lymphoma in a patient simultaneously diagnosed with chronic lymphocytic leukemia (CLL) is reported. Although differences in phenotypic expression were demonstrated in study of the peripheral blood and CNS disease, identical immunoglobulin gene rearrangements were identified, providing evidence for evolution of two morphologically distinct neoplasms from the same clone. Beyond histologic transformation, acquisition of an aneuploid cell population in the CNS tumor was demonstrated by analysis of DNA content. Isolated parenchymal involvement of the CNS by large cell transformation of CLL has not been previously described; its relationship to CNS lymphoma and Richter's syndrome are reviewed.

Aged↗
PubMed2006

Bird pollination in an angraecoid orchid on Reunion Island (Mascarene Archipelago, Indian Ocean).

BACKGROUND AND AIMS: Although numerous angraecoid orchids in Madagascar display typical sphingophilous syndrome (i.e. white, nectariferous, long-spurred flowers, producing a strong scent at the crepuscule that is attractive to moths), three species of Angraecum in Reunion, belonging to the endemic section Hadrangis, have atypical unscented and short-spurred flowers. The aim of the study was to investigate the implication of plant-pollinator interaction on the evolution of floral morphology of these peculiar island floral forms. METHODS: The flower morphology of A. striatum (one of the three section Hadrangis species) was investigated by performing a set of floral measures, and the reproductive biology was investigated by a set of hand pollination experiments. Natural pollinators were observed by means of a digital video camera. Pollinator efficiency (pollen removal and deposition) and reproductive success (fruit set) were quantified once a week in natural field conditions during the 2005 flowering season (i.e. from January to March). KEY RESULTS: The orchid is self-compatible but requires a pollinator to achieve fruit set. Only one pollinator was observed, the endemic white-eye Zosterops borbonicus (Zosteropidae). These birds perched on inflorescences, and probed most fresh-looking flowers on each plant for nectar. Nectar was both abundant (averaging 7.7 microL) and dilute (averaging 9.7 % sugar in sucrose equivalents). Birds were mostly active between 0830 and 0930 h. Visits to plants were extremely short, lasting from 9 to 27 s. At the study site, 60.9 % of flowers had pollen removed, and 46.4 % had pollinia deposited on stigmas. The proportion of flowers that initiated a fruit averaged 20.6 % in natural conditions. CONCLUSIONS: For the first time, a bird-pollinated orchid is described from a sub-tribe that is mainly specialized for moth pollination. This study documents a morphological shift in flowers in response to pollinator adaptations in the insular context of the Mascarene Archipelago.

Animals↗
PubMed2026

Biocontrol potential and molecular basis of predation in a marine raptorial ciliate.

Predator-prey interactions are widespread across organisms and are key drivers of morphological and behavioral evolution. Despite this, predation remains poorly understood among microbial eukaryotes, mostly due to the absence of a tractable experimental system that allows quantitative, reproducible investigation. This study establishes the marine raptorial ciliate Chaenea vorax as a highly efficient predator, with Rosenzweig-MacArthur model simulations based on predation data showing that only a few dozen individuals can eliminate the vast majority of the facultatively pathogenic ciliate Uronema marinum within 1-2 days, providing a quantitative basis for developing predator-based biocontrol strategies in aquaculture. Genomic analysis shows that C. vorax possesses a highly fragmented macronuclear genome enriched with predation-related pathways, including calcium-mediated contractility, cellular proteolysis, toxin expulsion systems, among others. Transcriptomic profiling during predation events further demonstrates significant upregulation of genes involved in cytoskeletal remodeling, proteolytic activity, and cellular detoxification. Evolutionary analyses suggest that C. vorax has an extremely long evolutionary history, exceptionally high nucleotide diversity even among ciliates, and gene family expansions linked to predatory adaptation. Although the prey possesses certain defensive mechanisms (e.g. trichocysts), these are largely ineffective against short-term predation in closed aquatic environments. These findings provide fundamental insights into the molecular basis of predation in ciliates and suggest the potential utility of C. vorax in biocontrol applications targeting pathogenic ciliates.

Ciliophora↗
PubMed1992

Polysomnography in newborns and young infants: sleep architecture.

Sleep architecture derived from long-term polysomnographic recordings during the first year of life is characterized by clear developmental trends against a backdrop of variability. Variability is due to differences in state definitions and data collection and analysis strategies but probably also to an intrinsic characteristic of the maturing central nervous system (functional plasticity). Changes in sleep and wakefulness probably constitute nonspecific responses to a variety of stimuli. The variability has frustrated efforts to use specific features of sleep architecture for diagnostic or prognostic purposes. At present, polysomnographic studies of sleep architecture independent from EEG and cardiorespiratory studies are not indicated for diagnosing specific medical conditions or prognoses of good/adverse outcomes. For accurate interpretation for cardio-respiratory data, however, studies of sleep and wakefulness are indispensable. Furthermore, the study of neonatal seizures, in particular the coherence of state-defining variables or the evolution of sleep morphology, may benefit from attention to sleep architecture. Initial findings from some laboratories suggest that the very feature of excessive instability, which can be measured by repetitive long-term polysomnographic monitoring, signals a poor prognosis. In addition, fragmented sleep and the evolving interrelationship between ultradian and circadian rhythms may contain useful information that has yet to be mined. The advent of computer technologies can make the clinical laboratory into a setting where both research and clinical studies contribute to an elucidation of risk for sudden infant death syndrome and sequelae of neonatal seizures.

Circadian Rhythm↗
PubMed2003

Low-malignant-potential tumor of the ovary: sonographic features with clinicopathologic correlation in 41 patients.

The biologic, behavioral, and pathologic features of low-malignant-potential (LMP) tumor of the ovary are distinct from their invasive counterpart. LMP tumors affect patients at a younger age and have a much better 5- and 20-year survival rate compared with invasive ovarian malignancy. The authors retrospectively reviewed the records and sonograms of 41 patients (51 masses) with LMP tumor of the ovary. They demonstrated a wide variety of morphologies on the presentation sonograms with six masses favored to be benign, four indeterminate, 18 likely malignant, and 23 clearly malignant. Eighteen of 51 masses (35.3%) had a unique appearance-a cyst within the ovary of small to medium size with vascular mural nodularity and preserved surrounding ovarian parenchyma. Low-level echoes within the cystic components of the mass, reminiscent of typical endometrioma, were present in 19 of 51 masses (37.2%). Peritoneal dissemination was present in six patients at presentation, all! whom were alive at follow-up between 45 and 120 months. The authors think that many LMP tumors may be recognized and treated while they are still small. Ovary-sparing surgery may preserve patient fertility. LMP tumors may present initially with a benign morphology, although temporal evolution tends to show more suspicious features. Because these tumors may also appear frankly malignant or show peritoneal dissemination, the possibility of LMP tumor must be considered in light of their much better prognosis compared with invasive ovarian malignancy.

Adult↗
PubMed2005

Amiodarone keratopathy: an in vivo confocal microscopy study.

PURPOSE: To evaluate the characteristics and evolution of corneal morphologic changes induced by systemic amiodarone treatment by using in vivo slit scanning confocal microscopy in an attempt to understand the pathogenesis of corneal and other systemic side effects of this drug. METHODS: Forty-nine eyes of 25 consecutive subjects receiving amiodarone therapy (group A) and 26 eyes of 13 age- and sex-matched healthy control subjects (group B) were enrolled in the study. RESULTS: In group A, the mean dosage of amiodarone was 224.0 +/- 71.3 mg, and the mean duration of treatment was 21.3 +/- 20.9 months. In eight (8 of 49,16.3) eyes of four patients, no deposition was observed, neither by slitlamp nor by confocal microscopy. The deposition could be detected as early as 2 months after the onset of treatment in 41 (41 of 49, 83.7%) eyes, by slitlamp and confocal microscopy. Deposition was significantly correlated with the duration of treatment and, therefore, the cumulative dose of the drug ingested. Deposits were observed as bright, hyper-reflective spots that were localized intracellularly and were present at the level of basal lamina of all 41 (100%) corneas in which deposition could be observed at confocal microscopy. Deposits were also observed in the superficial epithelium, anterior stroma, mid stroma, and subepithelial nerves in eyes with grade 2 to 4 keratopathy. Additionally, morphologic abnormalities were observed in anterior stromal keratocytes, subepithelial and stromal nerves, and endothelium. The mean anterior and posterior keratocyte densities were statistically significantly higher than those in group B. CONCLUSIONS: In addition to showing drug deposition does not seem to occur before 2 months of treatment and does not seem to be correlated with tear function. Although the clinical significance of morphologic changes induced by the drug is known and although deposition could not be detected before it was evident with slitlamp biomicroscopy, with some improvement in instrumentation, the authors believe that confocal microscopy will also prove to be useful in early diagnosis and in understanding the pathophysiology of amiodarone keratopathy. This may help grow insight to the mechanism of other, sometimes lethal, systemic side effects of this drug.

Adult↗
PubMed2000

Developmental trade-offs and life histories: strategic allocation of resources in caddis flies.

Resource allocation trade-offs during development are potentially very important in the evolution of organism morphology and life-history strategy However, they have rarely been demonstrated empirically. To what extent the division of limited resources between growing organs is a consequence of particular developmental pathways or varies strategically in line with life-history predictions is unknown. It has been demonstrated in a number of holometabolous insects that altering the resources available at pupation changes the pattern of allocation to adult tissues, but this has not been examined in a life-history context. Using caddis flies (Trichoptera), we show here that the effect of depleted larval resources on the pattern of somatic and reproductive investment is not fixed but varies between species with different life-history patterns. In particular, we demonstrate that, in a long-lived species, thorax size is preserved, which contrasts with the pattern previously observed in a short-lived species. That the adult body can be differentially altered by the same resource depletion in the larvae demonstrates that the allocation of resources amongst body parts is not a consequence of fixed pathways during development. Rather, the allocation of resources during development can occur in a manner consistent with the minimization of the effects on adult fitness.

Animals↗
PubMed2005

Seafloor topography and tectonic elements of the Western Indian Ocean.

The break-up of Gondwanaland and dispersal of several of its component continental fragments, which eventually formed the margins of the Indian Ocean, have produced an ocean basin of enormous variety, both in relief and in origin of seafloor features. The western half of the Indian Ocean alone contains every type of tectonic plate boundary, both active and fossil, and, along with some of the deepest fracture zones, the most complex mid-ocean ridge configurations and some of the thickest sedimentary sequences in the world's ocean basins. This ocean is one of the most diverse on the face of the globe. We explore the evolution of the morphology of the Indian Ocean floor, and discuss the effect of its variations, maxima and minima, on the interconnectivity of the ocean's water masses.

Journal Article↗
PubMed2003

Early pathogenesis of Autographa californica multiple nucleopolyhedrovirus and Helicoverpa zea single nucleopolyhedrovirus in Heliothis virescens: a comparison of the 'M' and 'S' strategies for establishing fatal infection.

Nucleopolyhedroviruses (NPVs) (Baculoviridae) produce fatal infections in larval lepidopteran insects. NPVs are designated SNPVs or MNPVs based on whether the occlusion-derived virus (ODV) that initiates primary midgut infections contains single (S) or multiple (M) nucleocapsids. The principal consequence of this ODV packaging is that primary target cells infected with the M phenotype receive multiple nucleocapsids, whereas those infected by the S phenotype receive only one. To determine the biological significance of this difference in the initial infection strategy, a comparison of the primary and secondary infection patterns of the recombinants Helicoverpa zea SNPV (HzSNPV-hsp70/lacZ) and Autographa californica MNPV (AcMNPV-hsp70/lacZ) in orally inoculated larvae of Heliothis virescens was carried out. At dosages yielding similar final mortalities ( approximately 85 %), primary midgut infections by HzSNPV-hsp70/lacZ (indicated by lacZ expression) were observed 6 h earlier and in greater numbers than those generated by AcMNPV-hsp70/lacZ. Infection of secondary target cells in the tracheal epidermis, however, occurred at the same time and at the same rate for both NPVs. A 2 h delay was observed between the onset of primary and secondary AcMNPV-hsp70/lacZ infection, supporting the hypothesis that early tracheal infections were initiated by ODV nucleocapsids repackaged as budded virus. In contrast, an 8 h delay was observed with HzSNPV-hsp70/lacZ, suggesting that systemic infections were established only after virus replication in primary targets. Significant numbers of both MNPV- and SNPV-infected primary target cells were sloughed from the midgut beginning as early as 16 h post-infection. Midgut cell sloughing may be an important host-mediated selection pressure influencing the evolution of NPV morphology and gene regulation, shaping, in part, baculovirus infection strategies.

Animals↗
PubMed2004

Modified cellular automaton model for the prediction of dendritic growth with melt convection.

A modified cellular automaton (MCA) coupled with a momentum and species transport model has been developed in order to predict the evolution of dendritic morphology during solidification of alloys in the presence of melt convection. In the present model, the cellular automaton algorithm for dendritic growth is incorporated with the transport model, for calculating fluid flow and mass transfer by both convention and diffusion. The MCA model takes into account the effects of the constitutional undercooling and the curvature undercooling on the equilibrium interface temperature. It also considers the preferred growth orientation of crystals and solute redistribution during solidification. In the transport model, which is coupled with cellular automaton approach, the SIMPLE scheme is employed to solve the governing equations of momentum and species transfers. The present model was applied to model solutal dendritic growth of an Al-3mass%Cu alloy in a forced flow. The simulations reproduced the typical asymmetric growth features of convective dendrites with various preferred orientations. The effects of inlet flow velocity on the solute redistribution and the growth velocity of a dendritic tip were quantitatively investigated.

Journal Article↗
PubMed2005

Roughening rates of strained-layer instabilities.

We study the evolution of the morphology of Si0.75Ge0.25 strained layers using a wide range of deposition times, 60<tau<2400 s, at 600 degrees C on laser textured substrates with miscuts theta<15 degrees off Si(001). Ripple-shaped morphologies form spontaneously on miscuts along the 110 directions. At the shortest deposition times, roughening is suppressed as predicted by a linear stability analysis that uses previously measured values for the mass transport rate on the surface. The measured time constant of the roughening is approximately 80 s, a factor of 4 larger than predicted by theory.

Journal Article↗
PubMed2000

Homologs of small nucleolar RNAs in Archaea.

In eukaryotes, dozens of posttranscriptional modifications are directed to specific nucleotides in ribosomal RNAs (rRNAs) by small nucleolar RNAs (snoRNAs). We identified homologs of snoRNA genes in both branches of the Archaea. Eighteen small sno-like RNAs (sRNAs) were cloned from the archaeon Sulfolobus acidocaldarius by coimmunoprecipitation with archaeal fibrillarin and NOP56, the homologs of eukaryotic snoRNA-associated proteins. We trained a probabilistic model on these sRNAs to search for more sRNAs in archaeal genomic sequences. Over 200 additional sRNAs were identified in seven archaeal genomes representing both the Crenarchaeota and the Euryarchaeota. snoRNA-based rRNA processing was therefore probably present in the last common ancestor of Archaea and Eukarya, predating the evolution of a morphologically distinct nucleolus.

Archaea↗
PubMed2000

Accessory pulsatile organs: evolutionary innovations in insects.

In addition to the dorsal vessel ("heart"), insects have accessory pulsatile organs ("auxiliary hearts") that supply body appendages with hemolymph. They are indispensable in the open circulatory system for hemolymph exchange in antennae, long mouthparts, legs, wings, and abdominal appendages. This review deals with the great diversity in the functional morphology and the evolution of these accessory pulsatile organs. In primitive insects, hemolymph is supplied to antennae and cerci by arteries connected to the dorsal vessel. In higher insects, however, these arteries were decoupled and associated with autonomous pumps that entered their body plan as evolutionary innovations. To ensure hemolymph supply to legs, wings, and some other appendages, completely new accessory pulsatile organs evolved. The muscular components of these pulsatile organs and their elastic antagonists were recruited from various organ systems and assembled to new functional units. In general, it seems that the evolution of accessory pulsatile organs has been determined by developmental and spatial constraints imposed by other organ systems rather than by changes in circulatory demands.

Animals↗
PubMed2002

The prototype of sex chromosomes found in Korean populations of Rana rugosa.

The seventh largest chromosome in Japanese populations of the frog Rana rugosa morphologically evolved as a sex chromosome. The sex chromosome is XX/XY type in one geographic form and ZZ/ZW type in another. In contrast, the seventh chromosomes are still homomorphic between the sexes in the other two geographic forms: they are more subtelocentric in the Kanto form and subtelocentric in the western Japanese form. To identify a prototype of the sex chromosomes, we extended our investigation in this study to the Korean form, which is supposed to be close to the phylogenetic origin of this species. The karyotype, a sex-linked gene sequence, and mechanisms of sex determination and gonadal differentiation were all examined. In addition, phylogenetic analyses were performed based on mitochondrial gene sequences and the results of crossings between the Korean and Japanese forms. As a consequence, the more subtelocentric seventh chromosome, shared by the Korean and Japanese Kanto forms, was concluded to be the prototype of the sex chromosomes. Starting at the prototype, a whole process of morphological sex chromosome evolution was reconstructed.

Animals↗
PubMed2001

BCR rearrangement-negative chronic myelogenous leukemia revisited.

PURPOSE: To document the characteristics of patients with major breakpoint cluster region (M-bcr) rearrangement-negative chronic myelogenous leukemia (CML). PATIENTS AND METHODS: The hematopathologist, who was blinded to patients' molecular status, reviewed the referral bone marrows and peripheral-blood smears from 26 patients with Philadelphia (Ph) translocation-negative CML who lacked Bcr rearrangement (and other evidence of a Bcr-Abl anomaly) and 14 patients (controls) with chronic-phase Ph-positive CML. Clinical data was ascertained by chart review. RESULTS: Among the 26 M-bcr rearrangement-negative CML patients, three pathologic subtypes emerged: (1) patients indistinguishable from classic CML (n = 9), (2) patients with atypical CML (n = 8), and (3) patients with chronic neutrophilic leukemia (n = 9). Among the 14 patients with Ph-positive CML who were included in the blinded review, 13 were classified as classic CML, and one was classified as atypical CML. The only statistically significant difference between M-bcr rearrangement-negative subgroups was in the proportion of patients having karyotypic abnormalities, an observation common only in patients with atypical CML (P = 0.008). However, the small number of patients in each subgroup limited our ability to differentiate between them. Interferon alfa induced complete hematologic remission in five of 14 patients; four of these remissions lasted more than 5 years. Only one of 26 patients developed blast crisis. The median survival of the 26 patients was 37 months. CONCLUSION: Patients with M-bcr rearrangement-negative CML fall into three morphologic subgroups. Disease evolution does not generally involve blastic transformation. Instead, patients show progressive organomegaly, leukocytosis, anemia, and thrombocytosis. Some patients in each subgroup can respond to interferon alfa.

Adult↗
PubMed2004

Paleo-oncology: the role of ancient remains in the study of cancer.

Paleo-oncology is the study of carcinomas and sarcomas in ancient human populations and their hominid precursors. These populations are informative concerning the possible influences on cancer of morphologic and functional evolution, diet, lifestyle, and other environmental factors. The prevalence of cancer in ancient populations might have differed from that in modern humans, because of substantial differences in tobacco and alcohol use, diet, life expectancy, and the availability of treatment. The available physical data concerning cancer in antiquity includes evidence of its existence in animal fossils and ancient humans and their precursors. The difficulties of paleo-oncologic research include a limited soft tissue record. In evaluating cancer in ancient remains, one must also deal with the problem of pseudopathology: whether an observed tissue change is all antemortem pathologic lesion or a postmortem artifact. Future archeological discoveries and the application of improved diagnostic techniques may enable paleo-oncology to make further contributions to our understanding of cancer.

Animals↗
PubMedDate not supplied

[Black grain mycetoma caused by Madurella grisea].

The authors reported one case of eumycotic mycetoma due to Madurella grisea (black grains) occurred on the right foot of the patient studied. The structure, microscopic morphology and therapeutic evolution are also studied and reported.

Adult↗