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Vertical Growth (vertical + growth)
Selected AbstractsAnalysis of Meox - 2 mutant mice reveals a novel postfusion-based cleft palateDEVELOPMENTAL DYNAMICS, Issue 2 2006Jiu-Zhen Jin Abstract Cleft palate represents a common human congential disease involving defects in the development of the secondary palate. Major steps in mammalian palatogenesis include vertical growth, elevation, and fusion of the palate shelves. Our current study with the homeobox gene Meox - 2 during mouse secondary palate development reveals a novel postfusion-based mechanism for cleft palate. Meox - 1 and Meox - 2 are two functionally related homeobox genes playing important roles in somitogenesis and limb muscle differentiation. We found that the expression of Meox - 2, not Meox - 1, marks the specification of early mouse palatal mesenchymal cells in the maxillary processes at embryonic day 11.5 (E11.5). From E12.5 to E15.5, the expression of Meox - 2 occupies only the posterior part of the palate, providing an early molecular marker for the anterior,posterior polarity in mouse secondary palate formation. A total of 35.3% of Meox - 2,/, (n = 17) and 25.5% of Meox - 2+/, (n = 55) mouse embryos display a cleft palate phenotype at E15.5, indicating that the reduction of Meox - 2 function is associated with susceptibility to cleft palate. Unlike previously reported clefts, none of the clefts found in Meox - 2 mutants contain any epithelial sheets in the medial edge areas, and detailed examination revealed that the clefts resulted from the breakdown of newly fused palates. This article is the first report of a gene required to maintain adherence of the palatal shelves after fusion. Developmental Dynamics 235:539,546, 2006. © 2005 Wiley-Liss, Inc. [source] Tertiary relict trees in a Mediterranean climate: abiotic constraints on the persistence of Prunus lusitanica at the eroding edge of its rangeJOURNAL OF BIOGEOGRAPHY, Issue 8 2008Fernando Pulido Abstract Aim, To investigate the ecophysiological traits allowing persistence of a subtropical relict tree (Prunus lusitanica L.) under a dry Mediterranean climate at the eroding edge of its range. Location, A glasshouse for the study under controlled conditions and two marginal populations located in riparian forests of central Spain and exposed to summer drought, in contrast to subtropical populations that grow in mountain cloud forests. Methods, Two experiments were conducted to assess tolerance to the abiotic conditions found in riparian habitats. In a glasshouse experiment, gas-exchange and light-use parameters were measured to evaluate seedling responses to a factorial combination of irradiance (60%, 10%, 2% and 0.5% full sun) and moisture (well watered control and drought stress). In a parallel field experiment, irradiance and soil moisture were measured as predictors of seedling survival at two sites in which half the seedlings were subjected to a threefold increase in summer precipitation by adding water every 10 days. Results Soil moisture strongly determined survival both in the glasshouse and in the two field sites. In the field, periodic addition of water failed to increase survival. Water-use efficiency (WUE) increased with drought. Seedlings did not tolerate deep shade (2,0.5%) and their performance and survival were better when exposed to moderate (10%) or high (60%) irradiance. The effect of water stress on seedling performance was stronger at moderate irradiance, moderate at high irradiance and negligible at very low light. Seedling size (height and number of leaves) attained after 1 month of experimental treatments had a positive effect on survival at the end of the summer, hence greater survival was not achieved at the expense of vertical growth. Main conclusions, While studies in Macaronesia have shown that P. lusitanica occupies a wide range of moisture conditions along mountain slopes, it behaves as an obligate riparian species in dry peripheral populations. Intolerance to deep shade and tolerance to moderate and high irradiance allow the species to grow in small and moist gaps, or in treeless river sections. Despite the species' low range filling in marginal, drought-prone regions, long-term persistence might have been achieved through shifts to riparian habitats serving as local refuges. [source] Establishing a missing link: warm summers and winter snow cover promote shrub expansion into alpine tundra in ScandinaviaNEW PHYTOLOGIST, Issue 4 2010Martin Hallinger Summary ,Shrub expansion in alpine and arctic areas is a process with possibly profound implications for ecosystem functioning. The recent shrub expansion has been mainly documented by remote sensing techniques, but the drivers for this process largely remain hypotheses. ,Here, we outline a dendrochronological method, adapted to shrubs, to address these hypotheses and then present a mechanism for the current shrub expansion by linking recent climate change to shrub growth performance in northern Sweden. ,A pronounced increase in radial and vertical growth during recent decades along an elevational gradient from treeline to shrubline indicates an ongoing shrub expansion. Age distribution of the shrub population indicates the new colonization of shrubs at high elevations. ,Shrub growth is correlated with warm summers and winter snow cover and suggests the potential for large-scale ecosystem changes if climate change continues as projected. [source] Differential compaction due to the irregular topology of a diagenetic reaction boundary: a new mechanism for the formation of polygonal faultsBASIN RESEARCH, Issue 3 2009R. J. Davies ABSTRACT We propose a new mechanism for the formation of some polygonal fault arrays. Seismically imaged opal-A (biogenic silica) to opal-CT (cristobalite and tridymite) diagenetic boundaries from two regions offshore of Norway have developed regular wavelength patterns. The pattern consists of cell-shaped elevations that are 200,2600 m wide and up to 200 m high, separated by troughs. The cells represent regions that undergo diagenesis at shallower burial depths, earlier than adjacent areas. The chemical change leads to mechanical compaction and porosity reduction; therefore subsidence occurs above the cells in the overburden. Roughly circular depressions form above the cells, and a network of folds form above inter-cell areas. Networks of normal faults form on the crests and margins of the folds as a result of flexure during the folding. The progressive lateral growth of the cells causes the depressions to widen and intervening folds to narrow resulting in new differential compaction-induced faults to form with variable strike orientations. Lateral and vertical growth of cells leads to cells conjoining and the re-establishment of a uniform planar reaction boundary. This novel but simple mechanism can explain some polygonal fault arrays that form above opal-A to opal-CT reaction boundaries and in these settings the mechanism should be considered in addition to syneresis, density inversion or low coefficients of residual friction which are the most commonly cited drivers for polygonal fault systems. [source] Carbonate seismic stratigraphy of the Gulf of Papua mixed depositional system: Neogene stratigraphic signature and eustatic controlBASIN RESEARCH, Issue 2 2008Evgueni N. Tcherepanov ABSTRACT The Eocene,Miocene carbonate deposition in the Gulf of Papua (GoP) corresponds to the carbonate evolution phase of this continental margin mixed depositional system. Global sea-level (eustatic) fluctuations appear to have been the most important factor influencing the mixed depositional system development during its carbonate phase. Development of the major carbonate system in the Gulf was initiated during the Eocene. Subsequent to an early Oligocene hiatus, the carbonate system expanded its surface area, vertically aggraded, then systematically backstepped, and finally partially drowned during the late Oligocene,early part of the early Miocene. During the late early Miocene,early middle Miocene, the carbonate system continued its vertical growth in most platform areas, where it was able to keep up with sea-level rise. At the early middle/late middle Miocene (Langhian/Serravallian) boundary, carbonate deposition shifted downward during a long-term sea-level regression, exposing most of the early middle Miocene platform tops. Following this downward shift, active carbonate production became restricted during the late middle Miocene to only the northeastern part of the study area, and carbonate accumulation was characterized by four systematically prograding units. At the very beginning of the late Miocene, the platform tops were re-flooded. The carbonate system was partially drowned, systematically backstepped, and locally aggraded during part of the late Miocene, the early Pliocene, and the Quaternary. The overall organization of the carbonate sequence geometries, observed in the GoP, display a clear pattern, often referred to as the Oligocene,Neogene stratigraphic signature. This pattern is identical to contemporaneous sedimentary patterns observed in pure carbonate systems such as in the Maldives and in the Bahamas, and also in some siliciclastic systems. Because this pattern is observed in several globally distributed locations, the recognition of the Oligocene,Neogene stratigraphic signature in the GoP demonstrates that the depositional evolution during the late Oligocene,Miocene and the early Pliocene must have been dominantly controlled by eustatic fluctuations. [source] Tumor cell expression of programmed cell death-1 ligand 1 is a prognostic factor for malignant melanoma,CANCER, Issue 7 2010Ryosuke Hino MD Abstract BACKGROUND: Melanoma tends to be refractory to various immunotherapies because of tumor-induced immunosuppression. To investigate the mechanism underlining the immunosuppression of melanoma patients, the authors focused on programmed cell death-1 (PD-1)/PD-1 ligand 1 (PD-L1) interaction between tumor cells and T cells. METHODS: Melanoma specimens were collected from 59 primary tumors, 16 lymph nodes, and 4 lesions of in-transit metastasis. Specimens stained with anti-PD-L1 monoclonal antibodies were digitalized to jpg files. To evaluate the intensity of PD-L1 expression, histograms were used, and the red density (RD) was measured. PD-1 expression on T cells was analyzed in blood samples from 10 patients who had stage IV melanoma and in 4 samples of in-transit metastases. RESULTS: Twenty-five patients comprised the "low" PD-L1 expression group (RD value, <90), and 34 patients comprised the "high" group (RD value, ,90). Breslow tumor thickness in the high-expression group was significantly higher than in the low-expression group. Univariate and multivariate analyses revealed that the overall survival rate of the high-expression group was significantly lower than that of the low-expression group. In all patients with stage IV disease who were examined, both CD8-positive and CD4-positive T cells had significantly higher PD-1 expression levels in the peripheral blood. Tumor-infiltrating T cells expressed high levels of PD-1, and its expression was elevated further during the clinical course. CONCLUSIONS: The current results indicated that there is a correlation between the degree of PD-L1 expression and the vertical growth of primary tumors in melanoma. Multivariate analysis demonstrated that PD-L1 expression is an independent prognostic factor for melanoma. Cancer 2010. © 2010 American Cancer Society. [source] | ||||||||||