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Characteristic Morphological Features (characteristic + morphological_feature)
Selected AbstractsMorphological irregularities and features of resistance to apoptosis in the dcp-1/pita double mutated egg chambers during Drosophila oogenesisCYTOSKELETON, Issue 1 2005Ioannis P. Nezis Abstract In the present study, we demonstrate the most novel characteristic morphological features of Drosophila egg chambers lacking both dcp-1 and pita functions in the germline cells. Dcp-1 is an effector caspase and it has been previously shown to play an important role during Drosophila oogenesis [McCall and Steller, 1998 : Science 279 : 230,234; Laundrie et al., 2003 : Genetics 165 : 1881,1888; Peterson et al., 2003 : Dev Biol 260 : 113,123]. The completion of sequencing and annotation of the Drosophila genome has revealed that the dcp-1 gene is nested within an intron of another distinct gene, called pita, a member of the C2H2 zinc finger protein family that regulates transcriptional initiation. The dcp-1,/,/pita,/, nurse cells exhibit euchromatic nuclei (delay of apoptosis) during the late stages of oogenesis, as revealed by conventional light and electron microscopy. The phalloidin-FITC staining discloses significant defects in actin cytoskeleton arrangement. The actin bundles fail to organize properly and the distribution of actin filaments in the ring canals is changed compared to the wild type. The oocyte and the chorion structures have been also modified. The oocyte nucleus is out of position and the chorion appears to contain irregular foldings, while the respiratory filaments obtain an altered morphology. The dcp-1,/,/pita,/, egg chambers do not exhibit the rare events of spontaneously induced apoptosis, observed for the wild type flies, during mid-oogenesis. Interestingly, the mutated egg chambers are protected by staurosporine-induced apoptosis in a percentage of 40%, strongly suggesting the essential role of dcp-1 and/or pita during mid-oogenesis. Cell Motil. Cytoskeleton 60:14,23, 2005. © 2004 Wiley-Liss, Inc. [source] A study of candidate marine target impact craters in Arabia Terra, MarsMETEORITICS & PLANETARY SCIENCE, Issue 6 2010Germari de VILLIERS Arabia Terra is a region on Mars that straddles the crustal dichotomy, and several proposed shorelines are located in the area. Shallow marine impact craters on Mars likely would exhibit features like those on Earth, including characteristic morphological features that are distinctly different from that of craters formed on land. Common attributes of terrestrial marine impact craters include features of wet mass movement such as gravity slumps and debris flows; radial gullies leading into the crater depression; resurge deposits and blocks of dislocated materials; crater rim collapse or breaching of the crater wall; a central peak terrace or peak ring terrace; and subdued topography (an indicator of both age and possible flood inundation immediately following impact). In this article, these features have been used to evaluate craters on Mars as to a possible marine origin. This study used a simple quantification system to approximately judge and rank shallow marine impact crater candidates based on features observed in terrestrial analogs. Based on the quantification system, 77 potential shallow marine impact craters were found within an area bounded by 20°N and 40°N as well as 20°W and 20°E. Nine exemplary candidates were ranked with total scores of 70% or more. In a second, smaller study area, impact craters of approximately similar size and age were evaluated as a comparison and average total scores are 35%, indicating that there is some morphological difference between craters inside and outside the proposed shorelines. Results of this type of study are useful in helping to develop a general means of classification and characterization of potential marine craters. [source] Geissleria gereckei sp. nov. (Bacillariophyta) from leaf-litter covered stones of very shaded carbonate mountain springs with extremely low dischargePHYCOLOGICAL RESEARCH, Issue 3 2009Marco Cantonati SUMMARY A new benthic freshwater diatom, Geissleria gereckei sp. nov., was identified from light and scanning electron micrographs. The most characteristic morphological features are the valve outline (elliptical, but with lateral margins that can range from slightly convex to slightly concave and also straight, and protracted, almost capitate ends), the size and length/width ratio, and the pattern of the striae around the central area. The new species was found to be epilithic, and characteristic of leaf-litter covered stones of very shaded carbonate mountain springs of the Italian Alps with extremely-low discharge (likely to be affected by seasonal desiccation). Very-low-discharge springs host a highly specialized diatom microflora, and are likely to increase in number in the near future due to the reduction of water, which is predicted to be caused by climate change in many regions. [source] Morphology of Canine Cumulus,Oocyte Complexes in Pre-pubertal BitchesANATOMIA, HISTOLOGIA, EMBRYOLOGIA, Issue 6 2003A. Haenisch-Woehl Summary The morphology of canine cumulus,oocyte complexes (COCs) before puberty is still unknown. Therefore, the aim of our study was to elucidate the morphological characteristics of pre-pubertal oocytes and cumulus cells by light microscopy, scanning electron microscopy and transmission electron microscopy. The pre-pubertal oocyte was characterized by accumulation of lipid yolk droplets in the cytoplasm as well as high energy metabolism, low protein synthesis and high transcriptional activity of the cumulus cells. The cumulus cells, which revealed a prominent nucleus and few cytoplasm, communicated with each other by few short processes and exhibited merely a small amount of processes reaching the oocyte. Our studies imply that both the oocyte and the cumulus cells of canine COCs before puberty reveal characteristic morphological features which are correlated with changes in oocyte metabolism and cumulus cell communication. [source] T cells and eosinophils in bronchial smooth muscle cell death in asthmaCLINICAL & EXPERIMENTAL ALLERGY, Issue 6 2009K. Solarewicz-Madejek Summary Background Bronchial smooth muscle cells (SMC) proliferate, express adhesion molecules, secrete cytokines and thus efficiently contribute to the pathogenesis of asthma. Objective The aim of the study was to investigate whether, and by which mechanism, T cells and eosinophils can cause death of airway SMC. Methods The T cell- and eosinophil-induced cell death was analysed in primary human bronchial SMC cultures as well as in bronchial biopsy specimens from non-asthmatic and asthmatic individuals. Results Bronchial SMC death showed characteristic morphological features of apoptosis in 3,6 days cultures with inflammatory cytokines (IFN-,, TNF-,), soluble death ligands [sFasL, TNF-related apoptosis-inducing ligand (TRAIL)] and activated T-helper type 1 (Th1) and Th2 cell supernatants. The recombinant eosinophil cationic protein induced SMC necrosis within 1 h. Resting SMC expressed the death receptors TNFR1, TNFR2, Fas, TRAILR1, TRAILR2 and membrane FasL as a death-inducing ligand. IFN-, and TNF-, up-regulated TNFR1, TNFR2, Fas and membrane FasL on SMC. TNF-, up-regulated TRAILR1 and TRAILR2; sFasL up-regulated TNFR2. The intracellular caspase-3 activation in SMC was significantly increased by IFN-,, sFasL, TRAIL, Th1 and Th2 cell supernatants. Increased expression of TRAIL in asthmatics, but not in non-asthmatic individuals was demonstrated in situ. The apoptosis receptors TRAILR1 and TRAILR2 were expressed in SMC and epithelial cells both in healthy and asthmatic biopsies. Prominent apoptosis of SMC was observed in fatal asthma, but not intermittent asthma biopses. Conclusion The demonstration of bronchial SMC death both by apoptosis and necrosis indicates the essential role of T cells and eosinophils in the bronchial tissue injury particularly in the severe asthma. [source] | ||||||||||