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César Díaz-Celis, Viviana I Risca, Felipe Hurtado, Jessica K Polka, Scott D Hansen, Daniel Maturana, Rosalba Lagos, R Dyche Mullins, Octavio Monasterio
Bacteria of the genus Prosthecobacter express homologs of eukaryotic α- and β-tubulin, called BtubA and BtubB, that have been observed to assemble into filaments in presence of GTP. BtubA/B polymers are proposed to be composed in vitro by two to six protofilaments, in contrast to in vivo where they have been reported to form 5-protofilaments tubes named bacterial microtubules (bMTs). The btubAB genes likely entered the Prosthecobacter lineage via horizontal gene transfer and may derive from an early ancestor of the modern eukaryotic microtubule (MT)...
July 17, 2017: Journal of Bacteriology
Gillian H Gile, Erick R James, Vera Tai, James T Harper, Trevor L Merrell, Vittorio Boscaro, Filip Husník, Rudolf H Scheffrahn, Patrick J Keeling
Spirotrichonymphea is a class of hypermastigote parabasalids defined by their spiral rows of many flagella. They are obligate hindgut symbionts of lower termites. Despite more than 100 years of morphological and ultrastructural study, the group remains poorly characterised by molecular data and the phylogenetic positions and taxonomic validity of most genera remain in question. The genus Spirotrichonympha has been reported to inhabit several termite genera, including Reticulitermes, Coptotermes, and Hodotermopsis...
July 15, 2017: Journal of Eukaryotic Microbiology
Emily E Riley, Eric Lauga
Many cells exploit the bending or rotation of flagellar filaments in order to self-propel in viscous fluids. While appropriate theoretical modeling is available to capture flagella locomotion in simple, Newtonian fluids, formidable computations are required to address theoretically their locomotion in complex, nonlinear fluids, e.g., mucus. Based on experimental measurements for the motion of rigid rods in non-Newtonian fluids and on the classical Carreau fluid model, we propose empirical extensions of the classical Newtonian resistive-force theory to model the waving of slender filaments in non-Newtonian fluids...
June 2017: Physical Review. E
William Ko, Sookkyung Lim, Wanho Lee, Yongsam Kim, Howard C Berg, Charles S Peskin
The helical flagella that are attached to the cell body of bacteria such as Escherichia coli and Salmonella typhimurium allow the cell to swim in a fluid environment. These flagella are capable of polymorphic transformation in that they take on various helical shapes that differ in helical pitch, radius, and chirality. We present a mathematical model of a single flagellum described by Kirchhoff rod theory that is immersed in a fluid governed by Stokes equations. We perform numerical simulations to demonstrate two mechanisms by which polymorphic transformation can occur, as observed in experiments...
June 2017: Physical Review. E
Patrick Siyambulela Mafunda, Liana Maree, Antoinette Kotze, Gerhard van der Horst
This study evaluated the semen of two penguin species from separate genera with reference to unique features in sperm structure using light microscopy and transmission electron microscopy. Ejaculates from African penguin (n = 51) and Rockhopper penguin (n = 9) contained on average more than 60% motile spermatozoa and a sperm concentration of 3274 × 10(6)/ml and 1423 × 10(6)/ml, respectively. The percentage progressive motility was similar for the two species as well as all the kinematics parameters...
May 7, 2017: Theriogenology
Caroline Spitz Dos Santos, Vera Lúcia Teixeira de Jesus, Douglas McIntosh, Caroline Cunha Carreiro, Lilian Cristina Oliveira Batista, Bruno do Bomfim Lopes, Daniel Marchesi Neves, Carlos Wilson Gomes Lopes
Non-human primates are our closest relatives and represent an interesting model for comparative parasitological studies. However, research on this topic particularly in relation to intestinal parasites has been fragmentary and limited mainly to animals held in captivity. Thus, our knowledge of host-parasite relationships in this species-rich group of mammals could be considered rudimentary. The current study combined morphological, ultrastructural, and molecular analyses to characterize isolates of intestinal tetratrichomonads recovered from the feces of three species of South American, non-human primates...
July 13, 2017: Parasitology Research
Changyong Cheng, Zhimei Dong, Xiao Han, Hang Wang, Li Jiang, Jing Sun, Yongchun Yang, Tiantian Ma, Chunyan Shao, Xiaodu Wang, Zhongwei Chen, Weihuan Fang, Nancy E Freitag, Huarong Huang, Houhui Song
Microbes employ the thioredoxin system to defend against oxidative stress and ensure correct disulfide bonding to maintain protein function. Listeria monocytogenes has been shown to encode a putative thioredoxin, TrxA, but its biological roles and underlying mechanisms remain unknown. Here, we showed that expression of L. monocytogenes TrxA is significantly induced in bacteria treated with the thiol-specific oxidizing agent, diamide. Deletion of trxA markedly compromised tolerance of the pathogen to diamide, and mainly impaired early stages of infection in human intestinal epithelial Caco-2 cells...
2017: Frontiers in Cellular and Infection Microbiology
Yuqing Hou, George B Witman
Cilia are assembled via intraflagellar transport (IFT). The IFT machinery is composed of motors and multi-subunit particles, termed IFT-A and IFT-B, that carry cargo into the cilium. Knowledge of how the IFT subunits interact with their cargo is of critical importance for understanding how the unique ciliary domain is established. We previously reported a Chlamydomonas mutant, ift46-1, that fails to express the IFT-B protein IFT46, has greatly reduced levels of other IFT-B proteins, and assembles only very short flagella...
July 12, 2017: Molecular Biology of the Cell
Sudarshan Gadadhar, Hala Dadi, Satish Bodakuntla, Anne Schnitzler, Ivan Bièche, Filippo Rusconi, Carsten Janke
As essential components of the eukaryotic cytoskeleton, microtubules fulfill a variety of functions that can be temporally and spatially controlled by tubulin posttranslational modifications. Tubulin glycylation has so far been mostly found on motile cilia and flagella, where it is involved in the stabilization of the axoneme. In contrast, barely anything is known about the role of glycylation in primary cilia because of limitations in detecting this modification in these organelles. We thus developed novel glycylation-specific antibodies with which we detected glycylation in many primary cilia...
July 7, 2017: Journal of Cell Biology
Renate Radek, Katja Meuser, Jürgen F H Strassert, Oguzhan Arslan, Anika Teßmer, Jan Šobotník, David Sillam-Dussès, Ricardo A Nink, Andreas Brune
The guts of lower termites are inhabited by host-specific consortia of cellulose-digesting flagellate protists. In this first investigation of the symbionts of the family Serritermitidae, we found that Glossotermes oculatus and Serritermes serrifer each harbor similar parabasalid morphotypes: large Pseudotrichonympha-like cells, medium-sized Leptospironympha-like cells with spiraled bands of flagella, and small Hexamastix-like cells; oxymonadid flagellates were absent. Despite their morphological resemblance to Pseudotrichonympha and Leptospironympha, a SSU rRNA-based phylogenetic analysis identified the two larger, trichonymphid flagellates as deep-branching sister groups of Teranymphidae, with Leptospironympha sp...
July 6, 2017: Journal of Eukaryotic Microbiology
Sweta Parab, Veena Dalvi, Sushma Mylavaram, Abhipriya K, Susan Idicula-Thomas, Shobha Sonawane, Priyanka Parte
Motility in sperm is driven by the flagella, the principal component of which is the axoneme. The microtubules which make up the 9 + 2 axoneme are composed of heterodimers of alpha and beta tubulins and undergo several post-translational modifications. We have earlier reported that HDAC6 functions as tubulin deacetylase in sperm and has a role in sperm movement. While exploring the specific tubulin acetyltransferase (TAT) in sperm we observed the presence of Chromodomain Y-Like (CDYL), on the principal piece of rat spermatozoa which compelled us to explore its function in sperm...
July 6, 2017: Cytoskeleton
William R Hardin, Renyu Li, Jason Xu, Andrew M Shelton, Germain C M Alas, Vladimir N Minin, Alexander R Paredez
Devoid of all known canonical actin-binding proteins, the prevalent parasite Giardia lamblia uses an alternative mechanism for cytokinesis. Unique aspects of this mechanism can potentially be leveraged for therapeutic development. Here, live-cell imaging methods were developed for Giardia to establish division kinetics and the core division machinery. Surprisingly, Giardia cytokinesis occurred with a median time that is ∼60 times faster than mammalian cells. In contrast to cells that use a contractile ring, actin was not concentrated in the furrow and was not directly required for furrow progression...
July 5, 2017: Proceedings of the National Academy of Sciences of the United States of America
Tianlong Li, Jinxing Li, Konstantin Morozov, Zhiguang Wu, Tailin Xu, Isaac Rozen, Alexander M Leshansky, Longqiu Li, Joseph Wang
The unique swimming strategies of natural microorganisms have inspired recent development of magnetic micro/nanorobots powered by artificial helical or flexible flagella. However, as artificial nanoswimmers with unique geometries are being developed, it is critical to explore new potential modes for kinetic optimization. For example, the freestyle stroke is the most efficient of the competitive swimming strokes for humans. Here we report a new type of magnetic nanorobot, a symmetric multi-linked two-arm nanoswimmer, capable of efficient "freestyle" swimming at low Reynolds numbers...
July 5, 2017: Nano Letters
Yunjeong Choe, Junmo Park, Jong Earn Yu, Jeong-Il Oh, Suhkmann Kim, Ho Young Kang
Edwardsiella piscicida is a Gram-negative pathogen that generally causes lethal septicemia in marine and freshwater fish. We generated a E. piscicida CK216 Δcrp mutant to investigate various biological roles related to this organism, including pathogenesis. Lack of Crp in CK216 was demonstrated by immunoblotting using a Crp-specific antibody. Compared to the parental strain, the mutant exhibited changes in three biochemical phenotypes, including ornithine decarboxylation, citrate utilization, and H2S production...
June 28, 2017: Fish & Shellfish Immunology
Yoann G Santin, Eric Cascales
Most gene clusters encoding multiprotein complexes of the bacterial cell envelope, such as conjugation and secretion systems, Type IV pili, and flagella, bear a gene encoding an enzyme with peptidoglycan hydrolase activity. These enzymes are usually glycoside hydrolases that cleave the glycan chains of the peptidoglycan. Their activities are spatially controlled to avoid cell lysis and to create localized rearrangement of the cell wall. This is assured by interaction with the structural subunits of the apparatus...
2017: Methods in Molecular Biology
Hee Jung Kim, Woongjae Yoo, Kyeong Sik Jin, Sangryeol Ryu, Hyung Ho Lee
Flagellar biogenesis is controlled by a negative feedback loop. When FliD was secreted at the late step of flagellar assembly, the FliD-FliT complex disassembled and free FliT bound to the FlhDC complex, a master regulator of flagellar biogenesis, subsequently inhibiting the overall expression of flagellar proteins. In this study, we analyzed the role of the FliD C-terminal domain in pentamer formation and interaction with FliT. Our study showed that the FliD L443R mutant exists as a monomer in solution, indicating that the Leu443 residue of FliD, which contributes to its interaction with FliT, plays a crucial role in the pentameric oligomerization of FliD...
June 30, 2017: Scientific Reports
Yan Li, Mingyang Zhou, Fengqing Wang, En Tao Wang, Zongjun Du, Chaoya Wu, Zhenpeng Zhang, Wei Liu, Zhihong Xie
A protease-producing bacterial strain, 13-12T, was isolated from the ocean sediment of Laizhou Bay, PR China and systematically studied. The bacterium was Gram-stain negative, non spore-forming rods, which were motile with two flagella. It was positive for oxidase, the hydrolysis of starch, agar and gelatin, and for nitrate reduction. It was negative for catalase, esterase and the degradation of CM-cellulose. Optimum growth was observed at 28 °C, pH 6.5-7.0 and in the presence of 2-3 % (w/v) NaCl. Phylogenetic analysis of the 16S rRNA gene, and whole genome data, affiliated it to the genus Photobacterium...
June 2017: International Journal of Systematic and Evolutionary Microbiology
Katarzyna A Radomska, Marc M S M Wösten, Soledad R Ordoñez, Jaap A Wagenaar, Jos P M van Putten
Flagella-driven motility enables bacteria to reach their favorable niche within the host. The human foodborne pathogen Campylobacter jejuni produces two heavily glycosylated structural flagellins (FlaA and FlaB) that form the flagellar filament. It also encodes the non-structural FlaC flagellin which is secreted through the flagellum and has been implicated in host cell invasion. The mechanisms that regulate C. jejuni flagellin biogenesis and guide the proteins to the export apparatus are different from those in most other enteropathogens and are not fully understood...
2017: Frontiers in Microbiology
Grace I Borlee, Brooke A Plumley, Kevin H Martin, Nawarat Somprasong, Mihnea R Mangalea, M Nurul Islam, Mary N Burtnick, Paul J Brett, Ivo Steinmetz, David P AuCoin, John T Belisle, Dean C Crick, Herbert P Schweizer, Bradley R Borlee
Burkholderia pseudomallei, the causative agent of melioidosis, is an important public health threat due to limited therapeutic options for treatment. Efforts to improve therapeutics for B. pseudomallei infections are dependent on the need to understand the role of B. pseudomallei biofilm formation and its contribution to antibiotic tolerance and persistence as these are bacterial traits that prevent effective therapy. In order to reveal the genes that regulate and/or contribute to B. pseudomallei 1026b biofilm formation, we screened a sequence defined two-allele transposon library and identified 118 transposon insertion mutants that were deficient in biofilm formation...
June 2017: PLoS Neglected Tropical Diseases
Jesús Espinal-Enríquez, Daniel Alejandro Priego-Espinosa, Alberto Darszon, Carmen Beltrán, Gustavo Martínez-Mekler
Spermatozoa sea urchin swimming behaviour is regulated by small peptides from the egg outer envelope. Speract, such a peptide, after binding to its receptor in Strongylocentrotus purpuratus sperm flagella, triggers a signaling pathway that culminates with a train of intracellular calcium oscillations, correlated with changes in sperm swimming pattern. This pathway has been widely studied but not fully characterized. Recent work on Arbacia punctulata sea urchin spermatozoa has documented the presence of the Ca(2+) CatSper channel in their flagella and its involvement in chemotaxis...
June 26, 2017: Scientific Reports
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