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  • 1
    ISSN: 1615-6102
    Keywords: Flagellar apparatus ; Green algae ; Rhizoplast ; Rootlets
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The ultrastructure of the flagellar apparatus of the marine quadriflagellate green algaTetraselmis subcordiformis is described in detail. Special consideration is given to the functional significance of the contractile rhizoplast and also to a complex structure which anchors the flagellar apparatus to the cell membrane and theca. The flagellar apparatus lies at the base of a deep apical depression. Four basal bodies lie in a zigzag row with their long axes nearly parallel. Outer adjacent pairs of basal bodies are structurally linked by a Z-shaped, ribbon-like structure. A striated fiber (transfiber) connects each outer basal body with the inner basal body of the opposite, mirror image pair. A complex system of four laminated oval discs (rhizanchora), microtubule rootlets and fibrous material anchor the flagellar apparatus and rhizoplasts to the plasma membrane and theca. A 4-2-4-2 arrangement of microtubule rootlets is present. Rhizoplasts, which are contractile organelles, branch into five distinct arms and associate with the near outer basal body and each of the four rhizanchora. Rhizoplast contraction is thought to be linked to flagellar activity and may act to alter the direction of motion of the cell.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1615-6102
    Keywords: Flagellar apparatus ; Green algae ; Phylogeny ; Striated fiber ; Symmetry ; Ulothrix
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The anterior end of the zoospore ofUlothrix belkae has been examined in detail and is compared toStigeoclonium and other filamentous green algae. The nature of the symmetry of green algal motile cells is discussed and the term, 180° rotational symmetry, is proposed to describe the type of arrangement of anterior end components seen inU. belkae, including the four basal bodies, rootlets and striated fibers. The four microtubular rootlets are cruciately arranged. A striated microtubule-associated component (SMAC) has a periodicity of 6.4 nm and extends with each 2-membered rootlet posteriorly into the cell. One 5-membered rootlet passes very near the eyespot. Phylogeny in green algal motile cells is discussed.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-2218
    Keywords: Ultrasound ; Localization ; Adhesions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Laparoscopic candidates with abdominal scars may have adhesions that result in visceral injury during trocar insertion. The purpose of this study was to evaluate the use of preoperative ultrasound mapping of abdominal wall adhesions, to provide safe initial laparoscopic access, and to guide the placement of subsequent trocars, facilitating adhesolysis when necessary. Thirty consecutive patients with previous abdominal surgery who were scheduled for laparoscopy underwent a preoperative ultrasonic examination of the abdominal wall using a 7-MHz linear ultrasound probe. Spontaneous viscera slide was measured during longitudinal scanning (normal=2–5 cm) and induced viscera slide was evaluated during longitudinal and transverse scanning (normal=1 cm or more) over the existing abdominal scar, the peri-umbilical region, and the remaining abdominal quadrants. Sixteen (53%) of 30 patients had adhesions under their scar and only four patients (25%) had umbilical adhesions. The 12 patients without umbilical adhesions all had successful closed cannulation while open cannulation at alternate sites was successful in the four individuals with umbilical adhesions. Blind umbilical needle cannulation was successfully done in all of the remaining 14 patients (47%) without visceral injury, including three patients (21%) with upper abdominal scars who were adhesion-free elsewhere. No adhesions were encountered that had not been preoperatively predicted by ultrasound. We conclude that examination of the abdominal wall with spontaneous and induced viscera slide, using ultrasound scanning, can reliably detect intraabdominal adhesions. The examination is best done on a highly selective basis by the operating surgeon to guide the location for initial trocar insertion and determine the type of abdominal wall cannulation in those individuals with previous abdominal scars.
    Type of Medium: Electronic Resource
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  • 4
    Publication Date: 2018-05-04
    Description: Severe malaria is caused by the apicomplexan parasite Plasmodium falciparum. Despite decades of research, the distinct biology of these parasites has made it challenging to establish high-throughput genetic approaches to identify and prioritize therapeutic targets. Using transposon mutagenesis of P. falciparum in an approach that exploited its AT-rich genome, we generated more than 38,000 mutants, saturating the genome and defining mutability and fitness costs for over 87% of genes. Of 5399 genes, our study defined 2680 genes as essential for optimal growth of asexual blood stages in vitro. These essential genes are associated with drug resistance, represent leading vaccine candidates, and include approximately 1000 Plasmodium -conserved genes of unknown function. We validated this approach by testing proteasome pathways for individual mutants associated with artemisinin sensitivity.
    Keywords: Microbiology, Online Only
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Geosciences , Computer Science , Medicine , Natural Sciences in General , Physics
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