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PubMed2006

Toward a global phylogeny of the Brassicaceae.

The Brassicaceae is a large plant family (338 genera and 3,700 species) of major scientific and economic importance. The taxonomy of this group has been plagued by convergent evolution in nearly every morphological feature used to define tribes and genera. Phylogenetic analysis of 746 nrDNA internal transcribed spacer (ITS) sequences, representing 24 of the 25 currently recognized tribes, 146 genera, and 461 species of Brassicaceae, produced the most comprehensive, single-locus-based phylogenetic analysis of the family published to date. Novel approaches to nrDNA ITS analysis and extensive taxonomic sampling offered a test of monophyly for a large complement of the currently recognized tribes and genera of Brassicaceae. In the most comprehensive analysis, tribes Alysseae, Anchonieae plus Hesperideae, Boechereae, Cardamineae, Eutremeae, Halimolobeae, Iberideae, Noccaeeae, Physarieae, Schizopetaleae, Smelowskieae, and Thlaspideae were all monophyletic. Several broadly defined genera (e.g., Draba and Smelowskia) were supported as monophyletic, whereas others (e.g., Sisymbrium and Alyssum) were clearly polyphyletic. Analyses of ITS data identified several problematic sequences attributable to errors in sample identification or database submission. Results from parsimony ratchet and Bayesian analyses recovered little support for the backbone of the phylogeny, suggesting that many lineages of Brassicaceae have undergone rapid radiations that may ultimately be difficult to resolve with any single locus. However, the development of a preliminary supermatrix including the combination of 10 loci for 65 species provides an initial estimate of intertribal relations and suggests that broad application of such a method will provide greater understanding of relationships in the family.

Animals↗
PubMed1988

A dynamic model for water flow in a single tree: evidence that models must account for hydraulic architecture.

A model is presented for the dynamics of water flow in a single eastern white cedar tree (Thuja occidentalis L.). The model takes into account the spatial and temporal dependence of the evaporative flux from leaves in the crown. It also accounts for the quantitative hydraulic architecture of the tree, i.e., the model characterizes the tree as a branched catena of > 4000 stem segments in which account is taken of the segment length, diameter, hydraulic resistance, and the total area of leaves attached to the segment. Input values needed to run the model are measurements of evaporative flux, hydraulic conductance of stems versus stem diameter, and leaf and stem water storage capacitances. Output parameters are the spatial and temporal characterization of stem and leaf water potentials, stem and leaf water deficits, sap flow rate, and relative sap velocity. The input and output values of the branched catena model are compared and contrasted to that of an unbranched catena model. It is shown that the branched catena model fits independently measured field parameters better than an unbranched catena model. Close correspondence is found between model predictions and field measurements of shoot water potential, pressure gradients in stems, hysteresis in sap velocity between the lower and upper parts of the tree, and diurnal changes in stem and leaf water deficits. This model is discussed in terms of both the hydraulic architecture of trees and the potential application of the model to questions of tree morphology, ecology, physiology and evolution.

Journal Article↗
PubMed2006

Symmetrical crypsis and asymmetrical signalling in the cuttlefish Sepia officinalis.

The salience of bilateral symmetry to humans has led to the suggestion that camouflage may be enhanced in asymmetrical patterns. However, the importance of bilateral symmetry in visual signals (and overall morphology) may constrain the evolution of asymmetrical camouflage, resulting in the bilaterally symmetrical cryptic patterns that we see throughout the animal kingdom. This study investigates the cuttlefish (Sepia officinalis), which can control the degree of symmetry in its coloration. Ten juvenile S. officinalis were filmed in two behavioural contexts (cryptic and threatened) to test the prediction that cryptic patterns will be expressed more asymmetrically than an anti-predator signal known as the 'deimatic display'. Cryptic body patterns, particularly those with a disruptive function, were found to exhibit a high degree of bilateral symmetry. By contrast, the components of the deimatic display were often expressed asymmetrically. These results are contrary to the predicted use of symmetry in defensive coloration, indicating that the role of symmetry in both crypsis and visual signalling is not as straightforward as previously suggested.

Adaptation, Physiological↗
PubMed1989

Isolation, structure, and expression of labial, a homeotic gene of the Antennapedia Complex involved in Drosophila head development.

The labial (lab) gene of Drosophila melanogaster is necessary for the proper development of the embryonic (larval) and adult head. We have identified the lab transcription unit within the proximal portion of the Antennapedia Complex (ANT-C) by mapping the molecular lesions associated with chromosomally rearranged lab alleles. We present its molecular structure, nucleotide sequence, and temporal pattern of expression. In addition, using antibodies generated against a fusion protein, we show that in the embryo the lab protein is distributed in neural and epidermal cells of the procephalic lobe; in a discrete loop of the midgut; and in specific progenitor sensory cells of the clypeolabrum, thoracic segments, and tail region. The regions of lab expression in the developing cephalon represent nonsegmented domains that are anterior to and largely nonoverlapping with the domains of expression of the Deformed (Dfd) and proboscipedia (pb) genes, two other homeotic loci of the ANT-C that also function to direct the development of head structures. Furthermore, lab head expression is associated with the complex cellular movements of head involution, a process that not only is defective in lab embryos, but the failure of which appears to be largely responsible for the defects observed in mutant embryos. Finally, we suggest that lab head expression provides a molecular marker for an intercalary segment, an ancestral segment that has become morphologically indistinct during the evolution of the insect head.

Amino Acid Sequence↗
PubMed2001

Amorphous thin film growth: effects of density inhomogeneities.

A nonlinear stochastic growth equation for the spatiotemporal evolution of the surface morphology of amorphous thin films in the presence of potential density variations is derived from the relevant physical symmetries and compared to recent experimental results. Numerical simulations of the growth equation exhibit a saturation of the surface morphology for large film thickness originating from the inclusion of the density inhomogeneities. Furthermore, we argue why moundlike surface structures observed on vapor deposited amorphous films are not the result of the Grinfeld instability.

Journal Article↗
PubMed2000

A segmental gene duplication generated differentially expressed myb-homologous genes in maize.

The myb-homologous p1 gene regulates the synthesis of flavonoid pigments in maize kernel pericarp and cob; these floral organs are greatly modified in size and shape compared with their counterparts in teosinte, the progenitor of maize. To elucidate the molecular evolution of the p1 gene in relation to its expression and possible functions in maize and teosinte, we have isolated a second maize gene (p2) that is highly homologous with the p1 gene, and a related gene (p2-t) from Zea mays subsp parviglumis. We present evidence that the maize p1 and p2 genes were generated by duplication of an ancestral p gene (p(pre)) and its downstream sequences; the duplicated 3' flanking sequences were inserted upstream of the p(pre) gene, thereby changing its transcription pattern. This model accounts for the structural organization and the observed differential expression of the p1 and p2 genes: p1 transcripts accumulate in kernel pericarp, cob, tassel glumes, and silk, whereas p2 transcripts are found in developing anther and silk. The duplication is estimated to have occurred 2.75 million years ago; subsequently, multiple retroelements have been inserted between the p1 and p2 genes. Our results demonstrate the evolution of a single gene into a compound locus containing two component genes with different tissue specificities. Expression of the p1 gene in the kernel pericarp may have provided a selective advantage during the evolution of maize kernel morphology.

Amino Acid Sequence↗
PubMed2001

Perspective: From mutants to mechanisms? Assessing the candidate gene paradigm in evolutionary biology.

The generation of mutants in model organisms by geneticists and developmental biologists over the last century has occasionally produced phenotypes that are startlingly reminiscent of those seen in other species. Such extreme mutations have generally been dismissed by evolutionary geneticists since the "modern synthesis" as irrelevant to adaptation and speciation. But only in recent years has information on the molecular bases of mutant phenotypes become widely available, and thus work on testing the relevance of such extreme mutations to the generation of phylogenetic diversity has just begun. Here we evaluate whether evolutionary mimics are, in fact, useful for pinpointing the genetic differences that distinguish morphological variants generated during evolution. Examples come from both plants and animals, and range from intraspecific to interordinal taxonomic ranges. The use of mutationally defined candidate genes to predict evolutionary mechanisms has so far been most fruitful in explaining intraspecific variants, where it has been effective in both plants and animals. In several cases these efforts were facilitated or supported by parallel results from quantitative trait loci studies, in which natural alleles controlling continuous variation in developmental model organisms were mapped to mutationally defined genes. However, despite these successes the approach's utility seems to rapidly decay as a function of phylogenetic distance. This suggests that the divergence of developmental genetic systems is great even in closely related organisms and may become intractable at larger distances. We discuss this result in the context of what it teaches us about development, the future prospects of the candidate gene approach, and the historical debate over process in micro- and macroevolution.

Animals↗
PubMed1987

Restoration of active haemopoiesis in a patient with myelofibrosis and subsequent termination in acute myeloblastic leukaemia: case report and review of the literature.

A patient with polycythaemia vera developed typical myelofibrosis after 15 yr. After a further 8 months, during which time she was pancytopenic and transfusion-dependent, a slow spontaneous recovery in haemopoiesis occurred and the full blood count became normal. 6 months later pancytopenia recurred and soon afterwards the patient developed acute myeloblastic leukaemia from which she died. The evolution of bone marrow morphology and isotopic studies. Only 2 previous reports of this kind of transformation exist in the literature, although restoration of normal or polycythaemic haemopoiesis has been reported in 8 patients with myelofibrosis. It is likely that these transformations occur because of alterations in stem cell behaviour rather than as a result of therapy.

Acute Disease↗
PubMed1990

Spatial variation of ozone depletion rates in the springtime Antarctic polar vortex.

An area-mapping technique, designed to filter out synoptic perturbations of the Antarctic polar vortex such as distortion or displacement away from the pole, was applied to the Nimbus-7 TOMS (Total Ozone Mapping Spectrometer) data. This procedure reveals the detailed morphology of the temporal evolution of column O3. The results for the austral spring of 1987 suggest the existence of a relatively stable collar region enclosing an interior that is undergoing large variations. There is tentative evidence for quasi-periodic (15 to 20 days) O3 fluctuations in the collar and for upwelling of tropospheric air in late spring. A simplified photochemical model of O3 loss and the temporal evolution of the area-mapped polar O3 are used to constrain the chlorine monoxide (ClO) concentrations in the springtime Antarctic vortex. The concentrations required to account for the observed loss of O3 are higher than those previously reported by Anderson et al. but are comparable to their recently revised values. However, the O3 loss rates could be larger than deduced here because of underestimates of total O3 by TOMS near the terminator. This uncertainty, together with the uncertainties associated with measurements acquired during the Airborne Antarctic Ozone Experiment, suggests that in early spring, closer to the vortex center, there may be even larger ClO concentrations than have yet been detected.

Antarctic Regions↗
PubMed1981

The anatomy and phylogenetic significance of the carotid arteries and nerves in strepsirhine primates.

The internal carotid artery in lorisiform primates was identified on the basis of its close association with the internal carotid nerve (postsynaptic sympathetic trunk). An atrophic vessel in the lorisine Arctocebus resembles the internal carotid artery of Lemur in that it enters the tympanic bulla and promontory tube closely associated with the internal carotid nerve. According to this criterion of homology, the enigmatic lorisiform extrabullar carotid artery is not homologous with the internal carotid (promontory) artery of lemuriform primates or the medial internal carotid artery of the dog. Hypotheses about strepsirhine evolution must take these morphological facts into account.

Animals↗
PubMed1988

Evolution of NMRI mice ovaries and corpora lutea during pregnancy: morphologic and morphometric study.

During pregnancy in mice, three groups of corpora lutea (CL) originating from 4 successive ovulatory cycles could be distinguished taking into account their size, cellular structure and stain affinity. Type I CL originated at the onset of pregnancy, type II CL originated during the 2 previous estrous cycles and type III CL were produced during a cycle preceding the two others. CL volume of type I increased 10-fold between day 0 and day 18.5, a 2.5-fold increase in volume occurred in type II CL between day 0 and day 3, although they derived from cycles preceding pregnancy. The volume of type III remained unchanged. This fact suggested that types I and II CL probably play a functional role in the ongoing pregnancy. After day 10 of pregnancy a high correlation coefficient (r = 0.933) is observed between type I CL and the number of embryos in the corresponding uterine horn.

Animals↗
PubMed2001

Developmentally distinct MYB genes encode functionally equivalent proteins in Arabidopsis.

The duplication and divergence of developmental control genes is thought to have driven morphological diversification during the evolution of multicellular organisms. To examine the molecular basis of this process, we analyzed the functional relationship between two paralogous MYB transcription factor genes, WEREWOLF (WER) and GLABROUS1 (GL1), in Arabidopsis. The WER and GL1 genes specify distinct cell types and exhibit non-overlapping expression patterns during Arabidopsis development. Nevertheless, reciprocal complementation experiments with a series of gene fusions showed that WER and GL1 encode functionally equivalent proteins, and their unique roles in plant development are entirely due to differences in their cis-regulatory sequences. Similar experiments with a distantly related MYB gene (MYB2) showed that its product cannot functionally substitute for WER or GL1. Furthermore, an analysis of the WER and GL1 proteins shows that conserved sequences correspond to specific functional domains. These results provide new insights into the evolution of the MYB gene family in Arabidopsis, and, more generally, they demonstrate that novel developmental gene function may arise solely by the modification of cis-regulatory sequences.

Amino Acid Sequence↗
PubMed2006

Gliosarcoma with features of osteoblastic osteosarcoma: a review.

CONTEXT: Gliosarcoma is a rare tumor of the central nervous system characterized by a biphasic histologic pattern, consisting of a gliomatous and a sarcomatous component, respectively. In most instances the sarcomatous component is represented by a fibrosarcoma, but other stromal malignancies have also been described. Osteosarcomatous differentiation in gliosarcoma has been rarely reported. OBJECTIVE: To review characteristic radiologic and histopathologic features of this rare neoplasm, to debate about possible differential diagnoses that should be taken into consideration, and to provide an overview of the potential histopathogenesis of gliosarcomas. DATA SOURCES: Relevant articles indexed in PubMed (National Library of Medicine) and reference medical texts. CONCLUSIONS: Recent molecular studies suggest that sarcomatous and gliomatous components of gliosarcoma might be derived from a single precursor cell clone, progressing in 2 subclones with distinct morphologic features during tumor evolution. Nonetheless, events determining splitting of the original clone into 2 histologic populations remain to be investigated.

Central Nervous System Neoplasms↗
PubMed1999

[Remodelling of the radial artery graft 5 years after aortocoronary bypass intervention].

BACKGROUND: The radial artery (RA) is being employed as coronary artery bypass graft with good results, but when it is proximally anastomosed to the ascending aorta, undergoes substantial hemodynamic changes which could lead to significant graft intimal hyperplasia. The aim of this study was to investigate the evolution of RA graft morphology over time. METHODS: We studied 20 patients with a perfectly patent RA graft at both 1 and 5 year angiography after coronary artery bypass graft. RESULTS: Both RA graft and grafted coronary artery diameters, assessed by quantitative coronary angiography, significantly increased at 5 years, in comparison to 1 year angiography (2.08 +/- 0.45 vs 2.54 +/- 0.53 mm, +22%, p < 0.001 and 1.92 +/- 0.47 vs 2.18 +/- 0.41 mm, +13.3%, p < 0.001, respectively). CONCLUSIONS: Hemodynamic changes following RA employment for coronary artery bypass graft stimulate a remodeling of RA graft itself and of the grafted coronary arteries. The progressive increase of diameters observed in RA grafts strongly argues against the development of flow-limiting graft intimal hyperplasia when RA is proximally anastomosed to the ascending aorta. Moreover, grafted coronary artery dilation suggests that hemorrheologic changes following coronary artery bypass graft could play a major role in the development of RA remodeling over time.

Analysis of Variance↗
PubMed2000

Nailfold videocapillaroscopy assessment of microvascular damage in systemic sclerosis.

OBJECTIVE: To correlate microvascular abnormalities, evaluated by nailfold videocapillaroscopy (NVC), with the duration of both Raynaud's phenomenon (RP) and systemic sclerosis (SSc) from the date of diagnosis, in a large number of patients with SSc. METHODS: Ninety-seven consecutive patients were recruited and distributed into 3 groups on the basis of the morphological NVC patterns observed: "early" (E), "active" (A), and "late" (L). In each group the age of patients, age at onset, and the duration of RP as well as of overt SSc were investigated and correlated with the different NVC pattern variables. RESULTS: The early appearance of giant capillaries and hemorrhages (E pattern) is of great relevance for the early diagnosis of SSc. Therefore, these alterations are more evident in the active phase of the disease (A pattern). Conversely, the NVC observation of loss of capillaries and vascular architectural disorganization and the presence of ramified/bushy capillaries (L pattern) represents the clearest aspect of advanced SSc microvascular damage. These morphological alterations were found to correlate significantly with the duration of both RP and SSc, as well as with age of patients (p = 0.0001). No significant differences were observed when the variables were analyzed in the patients classified as having limited cutaneous SSc or diffuse cutaneous SSc. CONCLUSION: Classification of defined major nailfold patterns may be useful in assessing the appearance and progression of sclerodermic microangiopathy. As well, nailfold changes might represent a morphological reproduction of the evolution of SSc.

Female↗
PubMed2001

Transgressive character expression in a hybrid sunflower species.

Diploid hybrid lineages often are ecologically distinct from their parental species. However, it is unclear whether this niche divergence is typically achieved via hybrid intermediacy, a mixture of parental traits, and/or the evolution of extreme (transgressive) morphological and ecophysiological features. Here we compare an extensively studied hybrid sunflower species, Helianthus anomalus, with its putative parents, H. annuus and H. petiolaris, for 41 morphological and 12 ecophysiological traits. Helianthus anomalus was morphologically intermediate for one trait (2.4%), parental-like for 23 traits (56.1%), and transgressive for 17 traits (41.5%). For ecophysiological traits, H. anomalus was not significantly different from one or both parents for nine traits (75%), and was transgressive for the remaining three (25%). Thus, H. anomalus appears to be a mosaic of parental-like and transgressive phenotypes. Although the fitness effects of the transgressive characters are not yet known, many of these characters are consistent with adaptations reported for other sand dune plants. Genetic studies are currently underway to ascertain whether these extreme characters arose as a direct byproduct of hybridization or whether they evolved via mutational divergence.

Journal Article↗
PubMedDate not supplied

[Diagnostic perspectives in the rheumatologic vasculitis: the role of video-capillaroscopy].

Microvascular involvements represent one of the first step in many autoimmune diseases such as scleroderma (SSc) or antiphospholipid syndrome. Early in the disease, the peripheral microangiopathy may be well recognised and studied by nailfold videocapillaroscopy (NVC), a noninvasive and safe technique, that is reported to have both diagnostic and prognostic value, especially in the presence of Raynaud's phenomenon (RP). The classification of defined major NVC patterns in SSc might be useful in assessing the appearance and progression of the sclerodermic microangiopathy. In addition, the NVC changes might represent a morphological reproduction of the evolution of the SSc. The early appearance of giant capillaries and haemorrhages (Early pattern) is of great relevance for the early diagnosis of the SSc. Therefore, these alterations are more evident in the active phase of the disease (Active pattern). Conversely, the NVC observation of loss of capillaries, vascular architectural disorganisation and the presence of ramified/bushy capillaries (Late pattern) represents the clearest aspect of advanced SSc microvascular damages. Interesting, correlations between the NVC and clinical aspects of SSc, as well as the effects of therapeutical interventions have been observed.

Capillaries↗
PubMed2003

Four decades of teaching developmental biology in Germany.

I have taught developmental biology in Essen for 30 years. Since my department is named Zoophysiologie (Zoophysiology), besides Developmental Biology, I also have to teach General Animal Physiology. This explains why the time for teaching developmental biology is restricted to a lecture course, a laboratory course and several seminar courses. However, I also try to demonstrate in the lecture courses on General Physiology the close relationship between developmental biology, physiology, morphology, anatomy, teratology, carcinogenesis, evolution and ecology (importance of environmental factors on embryogenesis). Students are informed that developmental biology is a core discipline of biology. In the last decade, knowledge about molecular mechanisms in different organisms has exponentially increased. The students are trained to understand the close relationship between conserved gene structure, gene function and signaling pathways, in addition to or as an extension of, classical concepts. Public reports about the human genome project and stem cell research (especially therapeutic and reproductive cloning) have shown that developmental biology, both in traditional view and at the molecular level, is essential for the understanding of these complex topics and for serious and non-emotional debate.

Curriculum↗