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Central Cavity (central + cavity)
Selected AbstractsUltrastructural aspects of the follicular cells of the pars tuberalis in bats related to the seasonal cycleTHE ANATOMICAL RECORD : ADVANCES IN INTEGRATIVE ANATOMY AND EVOLUTIONARY BIOLOGY, Issue 2 2003Giacomo Azzali Abstract The topography and structure of the follicular cells and the follicular cavity of the hypophyseal pars tuberalis (PT) were studied in adult hibernating bats (Pipistrellus pipistrellus and Rhinolophus ferrumequinum) of both sexes, during the annual seasonal cycle and the reproductive cycle. The follicular cells were found to be organized around a central cavity. They showed a polyhedral shape and apical microvilli protruding into central cavities. During hibernation, the follicular cells showed active cytoplasmic organelles, clusters of glycogen particles, and lipid droplets. In the supranuclear cytoplasm, 9+2 type cilia, some dense bodies, microvesicular vacuoles, and thin actin-like filaments (rather scarce during autumn) were detected. The contents of the follicular cavity showed well-defined ultrastructural seasonal characteristics, with a colloid-like aspect during awakening and a strongly granular aspect during autumn oestrus and mating. Positive staining for PAS and paraldehyde fuchsin, and a marked reaction to lectins PHA-L4, MAM, and RCA 60 suggested the presence of sialo-glycoproteins in the follicular cavities. Both follicular and endocrine PT-specific cells appeared to mark the boundary of follicular cavities. This finding suggests that the follicular cavity contents are comprised of both types of cells, rather than by cell fragmentation or degeneration products. Anat Rec Part A 273A:763,771, 2003. © 2003 Wiley-Liss, Inc. [source] Mammalian Mcm2/4/6/7 complex forms a toroidal structureGENES TO CELLS, Issue 5 2003Norikazu Yabuta Background: The Mcm proteins are a family of six homologous proteins (Mcm2,7) that play an important role in DNA replication. They form Mcm4/6/7 and Mcm2/4/6/7 complexes, but their structures are not known. Results: We found that the human Mcm2/4/6/7 tetramer forms a toroidal structure, with a central cavity about 3,4 nm in diameter. Observations were made using electron microscopy, employing the image analysis of single particles. The most predominant averaged image displayed a toroid harbouring four bulges forming corners, one of which was larger than the others. This structure was very similar to the mouse Mcm2/4/6/7 tetramer that was independently prepared and analysed by electron microscopy. These toroidal structures are distinct from that of the Mcm4/6/7 hexamer, which was also examined by electron microscopy. GST(glutathione S-transferase)-pull down and two hybrid experiments suggest that a putative Mcm6-Mcm6 hinge contributes to the formation of the Mcm7/4/6/6/4/7 heterohexamer. Conclusions: The Mcm2/4/6/7 tetramer forms a toroidal structure that is distinct from that of the Mcm4/6/7 hexamer in size and shape. [source] Cutaneous sarcoid-like granulomas with alveolar hemorrhage and c-ANCA PR-3INTERNATIONAL JOURNAL OF DERMATOLOGY, Issue 9 2004Natividade Rocha MD A 28-year-old woman, employed as a leather factory worker, noted asymptomatic, well-delimited plaques on both knees, 6 years ago. The plaques were violaceous with a smooth surface. One appeared over a post-traumatic scar from childhood (Fig. 1). Two years later, she began to complain of symptoms suggestive of polyarthritis, first of the small joints of the hands (proximal interphalanges) and then of the larger joints (wrists, elbows, and knees). She was diagnosed with rheumatoid arthritis and began treatment with nonsteroidal anti-inflammatory drugs for 1 month without any change. Deflazacort, 12 mg/day, and hydroxychloroquine, 400 mg/day, were administered for 3 months, with improvement of her articular complaints, but not her skin lesions. Figure 1. Well-delimited, violaceous plaques with a smooth surface on the knees, one over an old post-traumatic scar One year later, she complained of dysphonia, which remitted spontaneously after some weeks. After one additional year, she noted papules, with similar characteristics to the plaques, on the elbows, and two well-delimited orange-to-brown plaques on the forehead (Fig. 2). Figure 2. Orange,brown plaques symmetrically placed on the forehead During the fifth year of the disease, she was referred for the first time to a dermatologist, who biopsied one of the knee lesions. The histologic result was compatible with "sarcoid granuloma." At that time, she presented with skin lesions as her only complaint. Sarcoidosis was suspected based on a chest X-ray, which revealed hilar lymphadenopathy and diffuse accentuation of the interstitium. In November 2000, she suddenly developed fever (40 °C), cough with hemoptysis, dysphonia, and subcutaneous nodules on the palmar surface of the fingers of both hands that were painless, well-delimited, 5 mm in diameter, and firm (Fig. 3). She reported a weight loss of 12 kg in the previous 3 months. Pulmonary condensation was found on auscultation, and she had palpable hepatomegaly. Peripheral lymphadenopathy was not present. Figure 3. Painless, well-delimited, firm subcutaneous nodules on the palmar surface of the fingers Laboratory investigations revealed normochromic, normocytic anemia (hemoglobin, 7.7 g/dL), iron deficit, a white blood cell count of 16,000/µL with neutrophilia, an erythrocyte sedimentation rate of 130 mm/h, elevation of liver enzymes, a slight increase in angiotensin-converting enzyme (ACE) level (72 U/L), hypergammaglobulinemia (IgG, 3350 mg/dL), antinuclear antibody (ANA) of 1 : 320, and a slight increase in CD4 and decrease in CD8 lymphocytes with normal cellular morphology in blood. Renal function, urine sediment, urine and serum calcium, complement (C4), dsDNA, antimitochondrial antibody, direct and indirect Coombs test, antineutrophil cytoplasmic antibody (ANCA), tuberculin skin tests, viral markers of hepatitis B, C, and human immunodeficiency virus (HIV), electrocardiogram (ECG), ophthalmic examinations, and culture for infectious agents in blood and sputum were all normal or negative. Computed tomography (CT) scan showed an infiltrate in the upper right pulmonary lobule with a central cavity and bilateral hilar lymphadenopathy (Fig. 4). Homogeneous hepatosplenomegaly was present. The bronchoalveolar lavage (BAL) showed a slight lymphocytic increase predominantly of CD8 cells and hemosiderosis. Stains for infectious agents, including acid-fast bacillus, fungi, Mycoplasma, and Legionella, were negative. Three biopsies from the forehead, elbows, and knees showed well-formed noncaseating epithelioid cell granulomas with giant cells of the Langhans type in the dermis, suggestive of sarcoidosis (Figs 5 and 6). A fourth biopsy from a finger nodule demonstrated inflammatory infiltration of the dermis and necrosis with cellular debris. Vasculitis was not seen (Fig. 7). Figure 4. Computed tomography scan showing an infiltrate in the upper right pulmonary lobule with a central cavity Figure 5. Beneath a flattened epidermis, several sarcoid granulomas composed of epithelioid histiocytes and several multinucleated giant cells of Langhans type can be seen (hematoxylin and eosin, ×10) Figure 6. Less well-formed sarcoid granulomas in a hyperkeratotic area, surrounded by a sparse rim of lymphocytes (hematoxylin and eosin, ×20) Figure 7. Foci of necrosis and fibrinoid degeneration with some neutrophil infiltration and nuclear dusting (hematoxylin and eosin, ×40) The patient was treated with a broad-spectrum empirical antimicrobial (levofloxacin, 500 mg daily intravenously) over 12 days, with prompt improvement in her symptoms and remission of the forehead and finger lesions. Nevertheless, on the first evaluation after hospitalization, the CT scan showed persistence of the pulmonary cavity (Fig. 8). A repeat ANCA determination was positive (cytoplasmic pattern, c-ANCA) at 1 : 640 by indirect immunofluorescence (IIF). Antiproteinase-3 antibody was demonstrated at 78 by enzyme-linked immunosorbent assay (ELISA). Figure 8. Computed tomography scan showing persistence of the pulmonary cavity She underwent an open lung biopsy which revealed intra-alveolar hemorrhage and scanty noncaseating epithelioid cell granulomas of the sarcoidosis type in the peripheral blood vessels without vasculitis. A diagnosis of Wegener's granulomatosis was made and she began prednisolone (1 mg/kg/day) and oral cyclophosphamide (2 mg/kg/day). One year later, she is asymptomatic, the skin lesions have completely remitted, c-ANCA is negative, and the CT scan shows partial regression of the pulmonary cavity. [source] A New Farnesyl Diphosphate Synthase Gene from Taxus media Rehder: Cloning, Characterization and Functional ComplementationJOURNAL OF INTEGRATIVE PLANT BIOLOGY, Issue 6 2006Zhi-Hua Liao Abstract Farnesyl diphosphate synthase (FPS; EC 2.5.1.10) catalyzes the production of 15-carbon farnesyl diphosphate which is a branch-point intermediate for many terpenoids. This reaction is considered to be a rate-limiting step in terpenoid biosynthesis. Here we report for the first time the cloning of a new full-length cDNA encoding farnesyl diphosphate synthase from a gymnosperm plant species, Taxus media Rehder, designated as TmFPS1. The full-length cDNA of TmFPS1 (GenBank accession number: AY461811) was 1 464 bp with a 1 056-bp open reading frame encoding a 351-amino acid polypeptide with a calculated molecular weight of 40.3 kDa and a theoretical pI of 5.07. Bioinformatic analysis revealed that TmFPS1 contained all five conserved domains of prenyltransferases, and showed homology to other FPSs of plant origin. Phylogenetic analysis showed that farnesyl diphosphate synthases can be divided into two groups: one of prokaryotic origin and the other of eukaryotic origin. TmFPS1 was grouped with FPSs of plant origin. Homology-based structural modeling showed that TmFPS1 had the typical spatial structure of FPS, whose most prominent structural feature is the arrangement of 13 core helices around a large central cavity in which the catalytic reaction takes place. Our bioinformatic analysis strongly suggests that TmFPS1 is a functional gene. Southern blot analysis revealed that TmFPS1 belongs to a small FPS gene family in T. media. Northern blot analysis indicated that TmFPS1 is expressed in all tested tissues, including the needles, stems and roots of T. media. Subsequently, functional complementation with TmFPS1 in a FPS-deficient mutant yeast demonstrated that TmFPS1 did encode farnesyl diphosphate synthase, which rescued the yeast mutant. This study will be helpful in future investigations aiming at understanding the detailed role of FPS in terpenoid biosynthesis flux control at the molecular genetic level. (Managing editor: Wei Wang) [source] Ultrastructural aspects of the follicular cells of the pars tuberalis in bats related to the seasonal cycleTHE ANATOMICAL RECORD : ADVANCES IN INTEGRATIVE ANATOMY AND EVOLUTIONARY BIOLOGY, Issue 2 2003Giacomo Azzali Abstract The topography and structure of the follicular cells and the follicular cavity of the hypophyseal pars tuberalis (PT) were studied in adult hibernating bats (Pipistrellus pipistrellus and Rhinolophus ferrumequinum) of both sexes, during the annual seasonal cycle and the reproductive cycle. The follicular cells were found to be organized around a central cavity. They showed a polyhedral shape and apical microvilli protruding into central cavities. During hibernation, the follicular cells showed active cytoplasmic organelles, clusters of glycogen particles, and lipid droplets. In the supranuclear cytoplasm, 9+2 type cilia, some dense bodies, microvesicular vacuoles, and thin actin-like filaments (rather scarce during autumn) were detected. The contents of the follicular cavity showed well-defined ultrastructural seasonal characteristics, with a colloid-like aspect during awakening and a strongly granular aspect during autumn oestrus and mating. Positive staining for PAS and paraldehyde fuchsin, and a marked reaction to lectins PHA-L4, MAM, and RCA 60 suggested the presence of sialo-glycoproteins in the follicular cavities. Both follicular and endocrine PT-specific cells appeared to mark the boundary of follicular cavities. This finding suggests that the follicular cavity contents are comprised of both types of cells, rather than by cell fragmentation or degeneration products. Anat Rec Part A 273A:763,771, 2003. © 2003 Wiley-Liss, Inc. [source] Structure,specificity relationships of an intracellular xylanase from Geobacillus stearothermophilusACTA CRYSTALLOGRAPHICA SECTION D, Issue 8 2007V. Solomon Geobacillus stearothermophilus T-6 is a thermophilic Gram-positive bacterium that produces two selective family 10 xylanases which both take part in the complete degradation and utilization of the xylan polymer. The two xylanases exhibit significantly different substrate specificities. While the extracellular xylanase (XT6; MW 43.8,kDa) hydrolyzes the long and branched native xylan polymer, the intracellular xylanase (IXT6; MW 38.6,kDa) preferentially hydrolyzes only short xylo-oligosaccharides. In this study, the detailed three-dimensional structure of IXT6 is reported, as determined by X-ray crystallography. It was initially solved by molecular replacement and then refined at 1.45,Å resolution to a final R factor of 15.0% and an Rfree of 19.0%. As expected, the structure forms the classical (,/,)8 fold, in which the two catalytic residues (Glu134 and Glu241) are located on the inner surface of the central cavity. The structure of IXT6 was compared with the highly homologous extracellular xylanase XT6, revealing a number of structural differences between the active sites of the two enzymes. In particular, structural differences derived from the unique subdomain in the carboxy-terminal region of XT6, which is completely absent in IXT6. These structural modifications may account for the significant differences in the substrate specificities of these otherwise very similar enzymes. [source] Crystallization and preliminary crystallographic studies of bar-headed goose fluoromethaemoglobin with inositol hexaphosphateACTA CRYSTALLOGRAPHICA SECTION D, Issue 9 2000Huan-Chen Wang Bar-headed goose fluoromethaemoglobin (fluoromet-Hb) complexed with inositol hexaphosphate (IHP) has been crystallized using PEG 6000 as precipitant. The crystal belongs to space group P21, with unit-cell parameters a = 59.8, b = 72.0, c = 79.8,Å, , = 102.1°, and diffracts to 2.5,Å resolution. To prove the presence of IHP, the structure was determined by the molecular-replacement method. IHP was observed at the entrance to the central cavity between the N and C termini of two , subunits. [source] Microscopic Evidence of the Metalation of a Free-Base Porphyrin Monolayer with IronCHEMPHYSCHEM, Issue 2 2007Florian Buchner Microscopic evidence of the in situ complexation of Fe-porphyrins is presented. The figure shows the sub-molecular resolved scanning tunneling microscopy images which document the metalation of 2H-TPP (central cavity; TPP: tetraphenylporphyrin) with evaporated iron (protrusions are identified as Fe-TPP). This promising technique enables future surface science investigations of clean iron porphyrin films under ultrahigh vacuum conditions. [source] | |||||||||||||