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  • 1
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    Bacterial rheotaxis [Environmental Sciences] (2012)
    National Academy of Sciences
    Details
    Publication Date: 2012-03-28
    Description: The motility of organisms is often directed in response to environmental stimuli. Rheotaxis is the directed movement resulting from fluid velocity gradients, long studied in fish, aquatic invertebrates, and spermatozoa. Using carefully controlled microfluidic flows, we show that rheotaxis also occurs in bacteria. Excellent quantitative agreement between experiments with Bacillus subtilis and a mathematical model reveals that bacterial rheotaxis is a purely physical phenomenon, in contrast to fish rheotaxis but in the same way as sperm rheotaxis. This previously unrecognized bacterial taxis results from a subtle interplay between velocity gradients and the helical shape of flagella, which together generate a torque that alters a bacterium's swimming direction. Because this torque is independent of the presence of a nearby surface, bacterial rheotaxis is not limited to the immediate neighborhood of liquid–solid interfaces, but also takes place in the bulk fluid. We predict that rheotaxis occurs in a wide range of bacterial habitats, from the natural environment to the human body, and can interfere with chemotaxis, suggesting that the fitness benefit conferred by bacterial motility may be sharply reduced in some hydrodynamic conditions.
    Print ISSN: 0027-8424
    Electronic ISSN: 1091-6490
    Topics: Biology , Medicine , Natural Sciences in General
    Published by National Academy of Sciences
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  • 2
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    Chemoattraction to dimethylsulfoniopropionate throughout the marine microbial food web (2010)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 2010-07-22
    Description: Phytoplankton-produced dimethylsulfoniopropionate (DMSP) provides underwater and atmospheric foraging cues for several species of marine invertebrates, fish, birds, and mammals. However, its role in the chemical ecology of marine planktonic microbes is largely unknown, and there is evidence for contradictory functions. By using microfluidics and image analysis of swimming behavior, we observed attraction toward microscale pulses of DMSP and related compounds among several motile strains of phytoplankton, heterotrophic bacteria, and bacterivore and herbivore microzooplankton. Because microbial DMSP cycling is the main natural source of cloud-forming sulfur aerosols, our results highlight how adaptations to microscale chemical seascapes shape planktonic food webs, while potentially influencing climate at the global scale.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Seymour, Justin R -- Simo, Rafel -- Ahmed, Tanvir -- Stocker, Roman -- New York, N.Y. -- Science. 2010 Jul 16;329(5989):342-5. doi: 10.1126/science.1188418.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Ralph M. Parsons Laboratory, Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA. Justin.Seymour@uts.edu.au〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/20647471" target="_blank"〉PubMed〈/a〉
    Keywords: Alphaproteobacteria/physiology ; Animals ; *Bacterial Physiological Phenomena ; Betaine ; Chemotactic Factors/metabolism ; *Chemotaxis ; Chlorophyta/physiology ; Cues ; Dinoflagellida/physiology ; Ecosystem ; *Food Chain ; Kinetoplastida/physiology ; Microfluidic Analytical Techniques ; Movement ; Phytoplankton/metabolism/*physiology ; Pseudoalteromonas/physiology ; *Seawater/microbiology ; *Sulfonium Compounds/metabolism ; Synechococcus/physiology ; Zooplankton/*physiology
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
    Published by American Association for the Advancement of Science (AAAS)
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  • 3
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    Trade-offs of chemotactic foraging in turbulent water (2012)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 2012-11-03
    Description: Bacteria play an indispensable role in marine biogeochemistry by recycling dissolved organic matter. Motile species can exploit small, ephemeral solute patches through chemotaxis and thereby gain a fitness advantage over nonmotile competitors. This competition occurs in a turbulent environment, yet turbulence is generally considered inconsequential for bacterial uptake. In contrast, we show that turbulence affects uptake by stirring nutrient patches into networks of thin filaments that motile bacteria can readily exploit. We find that chemotactic motility is subject to a trade-off between the uptake benefit due to chemotaxis and the cost of locomotion, resulting in an optimal swimming speed. A second trade-off results from the competing effects of stirring and mixing and leads to the prediction that chemotaxis is optimally favored at intermediate turbulence intensities.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Taylor, John R -- Stocker, Roman -- New York, N.Y. -- Science. 2012 Nov 2;338(6107):675-9. doi: 10.1126/science.1219417.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Applied Mathematics and Theoretical Physics, University of Cambridge, Wilberforce Road, Cambridge CB3 0WA, UK.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/23118190" target="_blank"〉PubMed〈/a〉
    Keywords: *Bacterial Physiological Phenomena ; *Chemotaxis ; Computer Simulation ; Ecosystem ; *Microbial Interactions ; Movement ; Seawater/*microbiology ; *Water Movements
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
    Published by American Association for the Advancement of Science (AAAS)
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  • 4
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    Marine microbes see a sea of gradients (2012)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 2012-11-03
    Description: Marine bacteria influence Earth's environmental dynamics in fundamental ways by controlling the biogeochemistry and productivity of the oceans. These large-scale consequences result from the combined effect of countless interactions occurring at the level of the individual cells. At these small scales, the ocean is surprisingly heterogeneous, and microbes experience an environment of pervasive and dynamic chemical and physical gradients. Many species actively exploit this heterogeneity, while others rely on gradient-independent adaptations. This is an exciting time to explore this frontier of oceanography, but understanding microbial behavior and competition in the context of the water column's microarchitecture calls for new ecological frameworks, such as a microbial optimal foraging theory, to determine the relevant trade-offs and global consequences of microbial life in a sea of gradients.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Stocker, Roman -- 1R01GM100473/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 2012 Nov 2;338(6107):628-33. doi: 10.1126/science.1208929.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Ralph M. Parsons Laboratory, Department of Civil and Environmental Engineering, 49-213, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA. romans@mit.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/23118182" target="_blank"〉PubMed〈/a〉
    Keywords: Adaptation, Physiological ; Aquatic Organisms/*physiology ; Bacteria/genetics/growth & development ; *Bacterial Physiological Phenomena ; Biodiversity ; Biological Evolution ; *Chemotaxis ; *Ecosystem ; Environment ; Oceans and Seas ; Seawater/*chemistry/*microbiology ; Water Microbiology
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
    Published by American Association for the Advancement of Science (AAAS)
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  • 5
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    Tryptophan catabolism is unaffected in chronic granulomatous disease (2014)
    Nature Publishing Group (NPG)
    Details
    Publication Date: 2014-10-25
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Maghzal, Ghassan J -- Winter, Susann -- Wurzer, Bettina -- Chong, Beng H -- Holmdahl, Rikard -- Stocker, Roland -- England -- Nature. 2014 Oct 23;514(7523):E16-7. doi: 10.1038/nature13844.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉1] Vascular Biology Division, Victor Chang Cardiac Research Institute, Darlinghurst, New South Wales 2010, Australia [2] School of Medicine, University of New South Wales, New South Wales 2052, Australia [3] School of Medical Sciences and Bosch Institute, The University of Sydney, Camperdown, New South Wales 2050, Australia. ; Department of Medical Biochemistry and Biophysics, Karolinska Institutet, 171 77 Stockholm, Sweden. ; School of Medical Sciences and Bosch Institute, The University of Sydney, Camperdown, New South Wales 2050, Australia. ; Centre for Vascular Research, University of New South Wales, New South Wales 2052, Australia.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/25341792" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Granulomatous Disease, Chronic/*metabolism/*pathology ; Inflammation/*metabolism ; Kynurenine/*metabolism ; Tryptophan/*metabolism
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Published by Nature Publishing Group (NPG)
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  • 6
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    How cats lap: water uptake by Felis catus (2010)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 2010-11-13
    Description: Animals have developed a range of drinking strategies depending on physiological and environmental constraints. Vertebrates with incomplete cheeks use their tongue to drink; the most common example is the lapping of cats and dogs. We show that the domestic cat (Felis catus) laps by a subtle mechanism based on water adhesion to the dorsal side of the tongue. A combined experimental and theoretical analysis reveals that Felis catus exploits fluid inertia to defeat gravity and pull liquid into the mouth. This competition between inertia and gravity sets the lapping frequency and yields a prediction for the dependence of frequency on animal mass. Measurements of lapping frequency across the family Felidae support this prediction, which suggests that the lapping mechanism is conserved among felines.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Reis, Pedro M -- Jung, Sunghwan -- Aristoff, Jeffrey M -- Stocker, Roman -- New York, N.Y. -- Science. 2010 Nov 26;330(6008):1231-4. doi: 10.1126/science.1195421. Epub 2010 Nov 11.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Civil and Environmental Engineering, Massachusetts Institute of Technology (MIT), Cambridge, MA 02139, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/21071630" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Biomechanical Phenomena ; Cats/*physiology ; Drinking/*physiology ; Felidae/physiology ; Gravitation ; Models, Biological ; Movement ; Physical Processes ; Tongue/*physiology
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
    Published by American Association for the Advancement of Science (AAAS)
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  • 7
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    Single-cell genomics reveals hundreds of coexisting subpopulations in wild Prochlorococcus (2014)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 2014-04-26
    Description: Extensive genomic diversity within coexisting members of a microbial species has been revealed through selected cultured isolates and metagenomic assemblies. Yet, the cell-by-cell genomic composition of wild uncultured populations of co-occurring cells is largely unknown. In this work, we applied large-scale single-cell genomics to study populations of the globally abundant marine cyanobacterium Prochlorococcus. We show that they are composed of hundreds of subpopulations with distinct "genomic backbones," each backbone consisting of a different set of core gene alleles linked to a small distinctive set of flexible genes. These subpopulations are estimated to have diverged at least a few million years ago, suggesting ancient, stable niche partitioning. Such a large set of coexisting subpopulations may be a general feature of free-living bacterial species with huge populations in highly mixed habitats.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Kashtan, Nadav -- Roggensack, Sara E -- Rodrigue, Sebastien -- Thompson, Jessie W -- Biller, Steven J -- Coe, Allison -- Ding, Huiming -- Marttinen, Pekka -- Malmstrom, Rex R -- Stocker, Roman -- Follows, Michael J -- Stepanauskas, Ramunas -- Chisholm, Sallie W -- New York, N.Y. -- Science. 2014 Apr 25;344(6182):416-20. doi: 10.1126/science.1248575.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Civil and Environmental Engineering, Massachusetts Institute of Technology (MIT), 77 Massachusetts Avenue, Cambridge, MA 02139, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/24763590" target="_blank"〉PubMed〈/a〉
    Keywords: Atlantic Ocean ; Biological Evolution ; Ecosystem ; Genes, Bacterial ; *Genetic Variation ; *Genome, Bacterial ; Metagenomics ; Molecular Sequence Data ; Mutation ; Phylogeny ; Polymorphism, Single Nucleotide ; Prochlorococcus/classification/*genetics/*physiology ; Seasons ; Seawater/*microbiology ; Sequence Analysis, DNA ; Single-Cell Analysis
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
    Published by American Association for the Advancement of Science (AAAS)
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  • 8
    Electronic Resource
    Electronic Resource
    Ultrastructural studies on neuromuscular contacts and the formation of junctions in the flight muscle of Antheraea polyphemus (Lep.) (1975)
    Springer
    Cell & tissue research 159 (1975), S. 245-266 
    Details
    ISSN: 1432-0878
    Keywords: Neuromuscular junctions ; Rete synapticum ; Development ; Antheraea ; (Lepidoptera) ; Trophic action ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The ultrastructure of neuromuscular connections on developing dorsolongitudinal flight muscles was studied in the moth Antheraea polyphemus, Undifferentiated membrane contacts between axon terminals and muscle-fiber anlagen are present in the diapause pupa. They persist during the period of nerve outgrowth, which probably provides a pathway of contact guidance. By the 4th day of adult development some of these contact areas have differentiated into structures similar to neuromuscular junctions although differentiation of muscle structure does not start earlier than the eighth day. Dense-cored vesicles are abundant in many axon terminals at the beginning of development. They later decrease in number quite rapidly. The significance of the above-mentioned early junctions, their possible mode of action and the role of the dense-cored vesicles are discussed. It is proposed that they exercise a stimulating (trophic) influence on the growth of the undifferentiated muscular tissue. The imaginai neuromuscular junctions are formed during the second half of adult development. Clusters of vesicles and electron-dense depositions along the inner face of the axolemma seem to initiate junction formation. Glial processes then grow between axoand sarcolemma and divide the large contact area into several small segments. Mutual invaginations and protrusions of the sarcolemma and the glial cell membrane subsequently form an extensive “rete synapticum.” Six days before eclosion the glial and sarcoplasmic parts of the rete synapticum are similar in size. Up to eclosion, all glial processes shrink and increase in electron density. Most of the observations are discussed also in relation to findings in vertebrates.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00219160
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  • 9
    Electronic Resource
    Electronic Resource
    Ultrastructural studies on neuromuscular contacts and the formation of junctions in the flight muscle of Antheraea polyphemus (Lep.) (1975)
    Springer
    Cell & tissue research 164 (1975), S. 331-355 
    Details
    ISSN: 1432-0878
    Keywords: Flight muscle ; Denervation ; Peripheral Wallerian degeneration ; Metamorphic axon degeneration ; Antheraea (Lepidoptera) ; Trophic action ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary In the moth Antheraea polyphemus the innervation of the anlage of the dorsolongitudinal flight muscle (dlm) was transected at the onset of adult development. The subsequent breakdown of the isolated motor stumps during early adult development was studied at the ultrastructural level. First reactions are seen on the second day of development when axonal mitochondria shrink. Later, elongated vesicles similar in structure to channels of smooth ER, appear in large numbers in the axoplasm. Their nature as well as the functional aspects of early axonal changes are discussed. From the 7th day onward two types of axonal breakdown become prominent. The first is characterized by swelling axon profiles, distorted vesicles and strongly shrunken mitochondria, while shrinking axon profiles containing tightly packed mitochondria and unaltered vesicles are typical of the second. Both types presumably take place independently of each other in different axon terminals. Axons and the contents of at least the first type are finally removed by transformation into lamellar bodies. Glial processes obviously behave independently of degenerating terminals; they loose any contact with them and never act as phagocytes for axon remnants. During the whole period of breakdown undifferentiated contacts between nerve fibers and muscle anlagen are present but synaptic structures as in normal developing dlm have never been observed. This fact, in comparison with earlier studies, suggests a lack of trophic nervous activity on the muscle anlagen tissue. A short time after removal of the isolated stumps new nerve tracts appear between dlm-fibers (which are, of course, strongly retarded in development). They are presumably sensory wing nerves which lack a guide structure to the central target, due to axotomy. Neuromuscular contacts or even junctions formed by axons of these nerves have occasionally been detected on the dlm. Their nature is discussed. Wallerian axon degeneration is compared to the normal, metamorphic breakdown of the innervation of the larval dlm-precursor. In contrast to the former, glial processes here remain in contact with the terminals. Glia and axons first swell. Then most glial processes are transformed into lamellar bodies whereas neuntes shrink and become electron-dense. Axonal organelles remain intact for a long period.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00223013
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  • 10
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    Low-Reynolds-number swimming at pycnoclines (2012)
    National Academy of Sciences
    Details
    Publication Date: 2012-02-21
    Print ISSN: 0027-8424
    Electronic ISSN: 1091-6490
    Topics: Biology , Medicine , Natural Sciences in General
    Published by National Academy of Sciences
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