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Middle Region (middle + region)
Selected AbstractsThe bone histology of osteoderms in temnospondyl amphibians and in the chroniosuchian BystrowiellaACTA ZOOLOGICA, Issue 1 2010Florian Witzmann Abstract Witzmann, F. and Soler-Gijón, R. 2010. The bone histology of osteoderms in temnospondyl amphibians and in the chroniosuchian Bystrowiella. ,Acta Zoologica (Stockholm) 91: 96,114 Bone histology of osteoderms in the armoured temnospondyl Peltobatrachus, plagiosaurids (Gerrothorax, Plagiosuchus) and dissorophids (Aspidosaurus, Cacops, Platyhystrix), as well as in the chroniosuchian Bystrowiella, is studied. The massive osteoderms of Peltobatrachus and Gerrothorax consist of homogeneous parallel-fibred bone, whereas in dissorophids, a lightly built, trabecular middle region is mantled by a thin cortex that is composed of a plywood-type structure. In Bystrowiella and Plagiosuchus, the osteoderms consist to a large degree of interwoven primary fibres and have cell lacunae that bear stumpy canaliculi. The differences in the histological structure of dissorophids and plagiosaurids suggest an iterative evolution of osteoderms. Furthermore, histology in Plagiosuchus indicates a metaplastic development of the osteoderms, whereas the osteoderms of Gerrothorax represent periosteal ossifications as in dissorophids. This suggests a convergent origin of osteoderms also within plagiosaurids. The extensive armour in Gerrothorax probably constituted a calcium reservoir, indicated by cyclical resorption events preserved in the external cortex and interpreted as a physiological response to periodic changes in salinity of the aquatic environment. In contrast, the unique osteoderm structure of dissorophids provides maximum stability and minimum bone mass, and is coherent with the interpretation that the osteoderms served to strengthen the vertebral column during terrestrial locomotion. [source] The specificity of alcohol dehydrogenase with cis -retinoidsFEBS JOURNAL, Issue 9 2004Activity with 11- cis -retinol, localization in retina Studies in knockout mice support the involvement of alcohol dehydrogenases ADH1 and ADH4 in retinoid metabolism, although kinetics with retinoids are not known for the mouse enzymes. Moreover, a role of alcohol dehydrogenase (ADH) in the eye retinoid interconversions cannot be ascertained due to the lack of information on the kinetics with 11- cis -retinoids. We report here the kinetics of human ADH1B1, ADH1B2, ADH4, and mouse ADH1 and ADH4 with all- trans -, 7- cis -, 9- cis -, 11- cis - and 13- cis -isomers of retinol and retinal. These retinoids are substrates for all enzymes tested, except the 13- cis isomers which are not used by ADH1. In general, human and mouse ADH4 exhibit similar activity, higher than that of ADH1, while mouse ADH1 is more efficient than the homologous human enzymes. All tested ADHs use 11- cis -retinoids efficiently. ADH4 shows much higher kcat/Km values for 11- cis -retinol oxidation than for 11- cis -retinal reduction, a unique property among mammalian ADHs for any alcohol/aldehyde substrate pair. Docking simulations and the kinetic properties of the human ADH4 M141L mutant demonstrated that residue 141, in the middle region of the active site, is essential for such ADH4 specificity. The distinct kinetics of ADH4 with 11- cis -retinol, its wide specificity with retinol isomers and its immunolocalization in several retinal cell layers, including pigment epithelium, support a role of this enzyme in the various retinol oxidations that occur in the retina. Cytosolic ADH4 activity may complement the isomer-specific microsomal enzymes involved in photopigment regeneration and retinoic acid synthesis. [source] Two-phase flow behavior in microtube reactors during biodiesel production from waste cooking oilAICHE JOURNAL, Issue 5 2010Guoqing Guan Abstract Flow patterns in the course of transesterification of waste cooking oil (WCO), sunflower oil (SFO) with water and/or oleic acid as a model of WCO, and pure SFO in the presence of a KOH catalyst in microtubes were investigated. FAME yield for the transesterification of WCO reached more than 89% in the microtube reactors with a residence time of 252 s at 333 K. The flow patterns when using WCO were changed from a liquid,liquid slug flow at the inlet region to a parallel flow at the middle region, and then to a homogeneous liquid flow at the outlet region as the reaction proceeded at 333 K. Fine droplets containing glycerol and methanol generally formed in oil slugs when using pure SFO, but were almost unobservable when using WCO. The soap produced from free fatty acids was considered to be the main factor affecting the flow patterns of WCO and SFO. © 2009 American Institute of Chemical Engineers AIChE J, 2010 [source] Reproductive morphology of Brittanichthys axelrodi (Teleostei: Characidae), a miniature inseminating fish from South AmericaJOURNAL OF MORPHOLOGY, Issue 1 2007Robert Javonillo Abstract Light and electron microscopy were used to investigate the morphology of reproductive characters in a characid fish, Brittanichthys axelrodi. Spermatozoa were found in ovaries of females, thereby confirming insemination in this species. Bony hooks can be found on the fourth unbranched ray and branched rays 1,4 of the anal fin and the unique sigmoidally-curved ray of the caudal fin in mature males. Testes have three distinct regions: an anterior spermatogenic region, an aspermatogenic middle region lined with a simple squamous epithelium and used for storage of mature spermatozoa, and a posterior region of coiled chambers lined with a high simple cuboidal epithelium. The most posterior region appears to be instrumental in the formation and storage of spermatozeugmata, unencapsulated sperm packets. Thus far, this tripartite testis morphology is unique among characids. The mature spermatozoon has an elongate nucleus (,5 ,m in length). A striated rootlet originates at the anterior end of the distal centriole and continues to the anterior tip of the cell. The striated rootlet wraps around the entire ventral area of the anterior part of the nucleus and appears to continue around the anterior tip of the nucleus and down the dorsal side as electron-dense material. Several large, spherical mitochondria (,0.6 ,m in diameter) with lamellar cristae overlap the posterior end of the nucleus and continue beyond together with the cytoplasmic collar that contains the flagellum which lacks axonemal fins. Each spermatozeugma is lanceolate in shape when sectioned mid-sagitally, with the core staining positively for mucopolysaccharides. In both sexes, the gonopore opens posterior to the anus, with the urinary pore having a separate opening posterior to the gonopore. Bands of skeletal muscle were found in the area of the male gonopore. These morphological features are likely linked to the reproductive mode of insemination, a trait that is so far as known, relatively rare among teleost fishes, but is proving increasingly frequent among certain groups of characid fishes. J. Morphol, 2006. © 2006 Wiley-Liss, Inc. [source] Molecular dynamic simulations of nanomechanic chaperone peptide and effects of in silico His mutations on nanostructured functionJOURNAL OF PEPTIDE SCIENCE, Issue 11 2008Abolfazl Barzegar Abstract The nanoscale peptide YSGVCHTDLHAWHGDWPLPVK exhibits molecular chaperone activity and prevents protein aggregation under chemical and/or thermal stress. Here, His mutations of this peptide and their impact on chaperone activity were evaluated using theoretical techniques. Molecular dynamic (MD) simulations with simulated annealing (SA) of different mutant nanopeptides were employed to determine the contribution of the scaffolding His residues (H45, H49, H52), when mutated to Pro, on chaperone action in vitro. The in silico mutations of His residues to Pro (H45P, H49P, H52P) revealed loss of secondary ordered strand structure. However, a small part of the strand conformation was formed in the middle region of the native chaperone peptide. The His-to-Pro mutations resulted in decreased gyration radius (Rg) values and surface accessibility of the mutant peptides under the simulation times. The invariant dihedral angle (,) values and the disrupting effects of the Pro residues indicated the coil conformation of mutant peptides. The failure of the chaperone-like action in the Pro mutant peptides was consistent with their decreased effective accessible surfaces. The high variation of , value for His residues in native chaperone peptide leads to high flexibility, such as a minichaperone acting as a nanomachine at the molecular level. Our findings demonstrate that the peptide strand conformation motif with high flexibility at nanoscale is critical for chaperone activity. Copyright © 2008 European Peptide Society and John Wiley & Sons, Ltd. [source] The mechanical binding strengths of Helicobacter pylori BabA and SabA adhesins using an adhesion binding assay,ELISA, and its clinical relevance in JapanMICROBIOLOGY AND IMMUNOLOGY, Issue 8 2010Mitsuaki Nishioka ABSTRACT To elucidate a potential role for H. pylori BabA and SabA adhesins in the pathogenesis of gastric mucosal lesions, the MBS of BabA and SabA was examined using an in-house ABA-ELISA. Ninety isolates from Japanese patients with gastric cancer (n= 43) and non-cancerous (n= 47) lesions were subjected to an ABA-ELISA which had been developed in-house, and sequential analysis of the babA2 middle region. The BabA-MBS was significantly higher in the cancer than the non-cancer group (P= 0.019), but there was no significant difference for SabA-MBS. A weak correlation between BabA-MBS and SabA-MBS (r= 0.418) was observed, the positive correlation being higher in the cancer than the non-cancer group (r= 0.598 and 0.288, respectively). The isolates were classified into two groups: a BabA-high-binding and a BabA-low-binding group (in comparison to the average for BabA-MBS). The average SabA-MBS in the BabA-high-binding group was significantly higher than in the BabA-low-binding group (P < 0.0001). Analysis of babA2 middle region diversity (AD1,5) revealed that AD2-type was predominant in isolates irrespective of BabA-MBS. H. pylori BabA-MBS might have an effect on SabA-MBS and relate to the severity of gastric disorders, including gastric cancer. Evaluation of MBS of the combined two adhesins would be helpful for predicting damage in the H. pylori infected stomach. [source] Morphology and ultrastructure of the female accessory sex glands in various crickets (Orthoptera, Saltatoria, Gryllidae)MITTEILUNGEN AUS DEM MUSEUM FUER NATURKUNDE IN BERLIN-DEUTSCHE ENTOMOLOGISCHE ZEITSCHRIFT, Issue 2 2002Robert Sturm Abstract In the present study, the morphology and ultrastructure of the accessory sex glands in females of the three cricket species Teleogryllus commodus, Gryllus bimaculatus, and Gryllus assimilis were subject to a detailed comparison. Within the observed crickets, the pairy glands are uniformly located in the 6th and 7th abdominal segment, joining the genital chamber lateral to the terminal papilla. Each gland is composed of an apical region (R3), consisting of the end tubules which produce the main amount of secretion, a middle region (R2) storing and leading the secretion to the orifice, and a basal region (R1) defining the orifice and most basal part of the gland. Concerning the size, number of ramifications, and length/width ratio, the investigated organs are marked by great variations among the species, ranging from anisometric glands (length/width < or > 1) with low number of ramifications in Teleogryllus commodus and Gryllus assimilis to nearly isometric glands with very numerous (up to 30) ramifications in Gryllus bimaculatus. The morphology of the respective glands is uniformly expressed by an epithelium composed of a basal lamina, one layer of gland cells, and a luminal, duct-less cuticular intima forming specific spines and hair-like processes. The ultrastructure of single gland cells is marked by a basal region with a large elliptic nucleus and intracellular cisternae formed by deep invaginations of the basal cell membrane. The apical part contains numerous lipid- and protein-forming compartments, mitochondria of cristae type, vesicles, and lipid drops. The apical cell surface is enlarged by forming a dense layer of microvilli. The lipophilic secretion produced by the glands is thought to be used as a lubricant in the ovipositor during egg-laying. [source] Etch-pits and threading dislocations in thick LEO GaN films on sapphire grown by MOCVDPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 10 2004Lu Min Abstract High quality Lateral Epitaxial Overgrowth (LEO) GaN films on (0001) sapphire substrates were grown by a commercial MOCVD system (Thomas Swan Corp.). We have studied the etch-pits and threading dislocations in GaN films by wet etching of pits, HCl vapor etching of pits and Scanning Electron Microscope (SEM). SEM images of GaN films etched in HCl vapor and molten KOH gave us notably different etching pits densities in the different region of LEO GaN films, which confirmed HCl vapor etching could show three kinds of Threading Dislocations (TDs), while molten KOH wet etching only could show pure screw TDs. In region above window TDs density is high (about 3 × 108/cm2) and edge TDs are in the majority, while it is almost free of TDs in region above mask, and only in middle region above mask there are some TDs (including all three kinds) and also edge TDs are in the majority. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Degradation of the auxin response factor ARF1THE PLANT JOURNAL, Issue 1 2008Jemma Salmon Summary Auxin-mediated gene expression is largely controlled through a family of DNA-binding proteins known as auxin response factors (ARF). Previous studies on the role of proteolytic regulation in auxin signaling have focused on degradation of their interacting partner, the Aux/IAA proteins. Aux/IAA family members with domain II sequences are rapidly degraded, show auxin-enhanced degradation rates, and interact with the related F-box proteins TIR1 and AFB1-3, which indicates that they are ubiquitylated by a CUL1-dependent E3 ligase. To date, limited data have been generated regarding degradation of ARFs. Here, we focus on the degradation rate of one ARF family member, Arabidopsis thaliana ARF1, and find that the half-lives of N-terminally HA-tagged ARF1 and C-terminally luciferase-tagged ARF1 are both approximately 3,4 h. This half-life appears to be conferred by a component of the middle region (MR), and degradation of the luciferase fusion with the MR is more rapid when the fusion includes an additional nuclear localization signal. ARF1 degradation is proteasome-dependent and rates are not altered in a CUL1 mutant background, suggesting that this ARF is targeted for proteasomal degradation via an alternative set of machinery to that used for Aux/IAA degradation. Consistent with this, exogenous indole acetic acid does not affect the degradation of ARF1. Given increasing evidence that the relative ratio of Aux/IAAs to ARFs rather than the absolute quantity within the cell appears to be the mode through which auxin signaling is modulated, this half-life is likely to be biologically relevant. [source] Phylogenetic analysis and species identification of popular shrimp species in southeast China using the first internally transcribed spacer of ribosomal DNAAQUACULTURE RESEARCH, Issue 11 2009Zhigang Wu Abstract The ribosomal DNA internally transcribed spacer 1 (ITS1) was investigated in the search for an appropriate genetic marker that was suitable for phylogenetic study and species identification of eight major exported shrimp species in southeast China. Using the selected primers, the amplified ITS1 sequences exhibited a high degree of length polymorphisms, ranging from 448 bp in Metapenaeopsis dalei to 1491 bp in Macrobrachium nipponense. Many microsatellite loci were found at the 5, end and in the middle region of ITS1, which seemed to be associated with intragenomic sequence variation among samples of the same species. This variation might obscure the phylogenetic relationship between some shrimp populations, but the separation of five Penaeus species was well supported. In combination with polymerase chain reaction-restriction fragment length polymerism methods analysis, ITS1 sequences from shrimp species belonging to different families and genera could also be easily discernable. The results suggested that ITS1 was highly variable among different shrimp groups and could be an appropriate marker for species identification and molecular systematic studies. [source] End-to-end and end-to-middle interhelical interactions: new classes of interacting helix pairs in protein structuresACTA CRYSTALLOGRAPHICA SECTION D, Issue 10 2009Tarini Shankar Ghosh Helix,helix interactions are important for the structure, stability and function of ,-helical proteins. Helices that either cross in the middle or show extensive contacts between each other, such as coiled coils, have been investigated in previous studies. Interactions between two helices can also occur only at the terminal regions or between the terminal region of one helix and the middle region of another helix. Examples of such helix pairs are found in aquaporin, H+/Cl, transporter and Bcl-2 proteins. The frequency of the occurrence of such `end-to-end' (EE) and `end-to-middle' (EM) helix pairs in protein structures is not known. Questions regarding the residue preferences in the interface and the mode of interhelical interactions in such helix pairs also remain unanswered. In this study, high-resolution structures of all-, proteins from the PDB have been systematically analyzed and the helix pairs that interact only in EE or EM fashion have been extracted. EE and EM helix pairs have been categorized into five classes (N,N, N,C, C,C, N,MID and C,MID) depending on the region of interaction. Nearly 13% of 5725 helix pairs belonged to one of the five classes. Analysis of single-residue propensities indicated that hydrophobic and polar residues prefer to occur in the C-terminal and N-terminal regions, respectively. Hydrophobic C-terminal interacting residues and polar N-terminal interacting residues are also highly conserved. A strong correlation exists between some of the residue properties (surface area/volume and length of side chains) and their preferences for occurring in the interface of EE and EM helix pairs. In contrast to interacting non-EE/EM helix pairs, helices in EE and EM pairs are farther apart. In these helix pairs, residues with large surface area/volume and longer side chains are preferred in the interfacial region. [source] New Bradoriid Arthropods from the Early Cambrian Balang Formation of Eastern Guizhou, South ChinaACTA GEOLOGICA SINICA (ENGLISH EDITION), Issue 1 2010Jin PENG Abstract: The Early Cambrian Balang Formation is comprised of mudrock and shale, which was deposited in a shelf environment in the eastern part of Guizhou, south China. The Balang Fauna, which consists of seven phyla, occurs in the middle and upper parts of the Balang Formation. Arthropods are important constituents of the Balang Fauna and include a great number of trilobites, large bivalved arthropods, and newly-discovered well-preserved bradoriid fossils. The bradoriids present include three genera and four species: Comptaluta inflate (Cheng, 1974) emend Hou et al., 2002; Comptaluta kailiensis sp. nov, and Alutella elongeta sp. nov, Aluta sp. This faunal assemblage in the Balang Formation is distinguished from the Tsunyiella Chang, 1964, Songlinella Yin, 1978 and Kunmingella Hou, 1956 assemblage which occurs in the Niutitang and Mingxinsi formations of the Yangtze Platform in middle region of Guizhou and which is earlier than the Balang Formation in age. However, this assemblage resembles the ComptalutaÖpik, 1968 assemblage from the Early Cambrian Heilinpu Formation in Wuding County, Yuanan Province and from the Ordian Stage of the Cambrian of Australia. The great abundance of ComptalutaÖpik, 1968 and overall taxonomic diversity of the ComptalutaÖpik, 1968 assemblage set it distinctly apart from the Alutella Kobayashi et Kato, 1951 and Aluta Hou, 1956 assemblages of the Balang Formation. Alutella Kobayashi et Kato, 1951 and Aluta Hou, 1956 also occur in the Early Cambrian Niutitang Formation of the Yangtze Platform of Guizhou. Individual Bradoriids from the Balang Formation are characterized by large size (>3 mm). The discovery of new Bradoriid assemblages not only expands the group's geographical range and assemblage affinities, but also indicates that Bradoriids migrated eastward from shallow-water to deeper-water environments during the Early Cambrian, indicating that they were capable of life in deeper-water, and adaptation to a new ecological setting. [source] | ||||||||||||||||