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81.
Fourteen polymorphic microsatellite loci were developed for the raccoon tick (Ixodes texanus). Three multiplexed panels comprising the loci were developed and 50 ticks collected from two infected raccoons (Procyon lotor) were genotyped. The number of alleles per locus ranged from five to 22, and single locus heterozygosities ranged from 0.46 to 0.94. Future research will further our understanding of I. texanus biology and help in elucidating the effects of life-history variation on parasite population genetic structure, using I. texanus as a model organism. 相似文献
82.
Yasuharu Kushida Masak Takaine Kentaro Nakano Toshiro Sugai Krishna Kumar Vasudevan Mayukh Guha Yu‐Yang Jiang Jacek Gaertig Osamu Numata 《The Journal of eukaryotic microbiology》2017,64(3):293-307
Ciliates such as Tetrahymena thermophila have two distinct nuclei within one cell: the micronucleus that undergoes mitosis and meiosis and the macronucleus that undergoes amitosis, a type of nuclear division that does not involve a bipolar spindle, but still relies on intranuclear microtubules. Ciliates provide an opportunity for the discovery of factors that specifically contribute to chromosome segregation based on a bipolar spindle, by identification of factors that affect the micronuclear but not the macronuclear division. Kinesin‐14 is a conserved minus‐end directed microtubule motor that cross‐links microtubules and contributes to the bipolar spindle sizing and organization. Here, we use homologous DNA recombination to knock out genes that encode kinesin‐14 orthologues (KIN141, KIN142) in Tetrahymena. A loss of KIN141 led to severe defects in the chromosome segregation during both mitosis and meiosis but did not affect amitosis. A loss of KIN141 altered the shape of the meiotic spindle in a way consistent with the KIN141's contribution to the organization of the spindle poles. EGFP‐tagged KIN141 preferentially accumulated at the spindle poles during the meiotic prophase and metaphase I. Thus, in ciliates, kinesin‐14 is important for nuclear divisions that involve a bipolar spindle. 相似文献
83.
The photosynthetic response of trees to rising CO2 concentrations largely depends on source-sink relations, in addition to differences in responsiveness by species, genotype, and functional group. Previous studies on elevated CO2 responses in trees have either doubled the gas concentration (>700 μmol mol−1) or used single large addition of CO2 (500-600 μmol mol−1). In this study, Gmelina arborea, a fast growing tropical deciduous tree species, was selected to determine the photosynthetic efficiency, growth response and overall source-sink relations under near elevated atmospheric CO2 concentration (460 μmol mol−1). Net photosynthetic rate of Gmelina was ∼30% higher in plants grown in elevated CO2 compared with ambient CO2-grown plants. The elevated CO2 concentration also had significant effect on photochemical and biochemical capacities evidenced by changes in FV/FM, ABS/CSm, ET0/CSm and RuBPcase activity. The study also revealed that elevated CO2 conditions significantly increased absolute growth rate, above ground biomass and carbon sequestration potential in Gmelina which sequestered ∼2100 g tree−1 carbon after 120 days of treatment when compared to ambient CO2-grown plants. Our data indicate that young Gmelina could accumulate significant biomass and escape acclimatory down-regulation of photosynthesis due to high source-sink capacity even with an increase of 100 μmol mol−1 CO2. 相似文献
84.
85.
Longitudinal patterns in carbon and nitrogen fluxes and stream metabolism along an urban watershed continuum 总被引:1,自引:0,他引:1
Sujay S. Kaushal Katie Delaney-Newcomb Stuart E. G. Findlay Tamara A. Newcomer Shuiwang Duan Michael J. Pennino Gwendolyn M. Sivirichi Ashley M. Sides-Raley Mark R. Walbridge Kenneth T. Belt 《Biogeochemistry》2014,121(1):23-44
An urban watershed continuum framework hypothesizes that there are coupled changes in (1) carbon and nitrogen cycling, (2) groundwater-surface water interactions, and (3) ecosystem metabolism along broader hydrologic flowpaths. It expands our understanding of urban streams beyond a reach scale. We evaluated this framework by analyzing longitudinal patterns in: C and N concentrations and mass balances, groundwater-surface interactions, and stream metabolism and carbon quality from headwaters to larger order streams. 52 monitoring sites were sampled seasonally and monthly along the Gwynns Falls watershed, which drains 170 km2 of the Baltimore Long-Term Ecological Research site. Regarding our first hypothesis of coupled C and N cycles, there were significant inverse linear relationships between nitrate and dissolved organic carbon (DOC) and nitrogen longitudinally (P < 0.05). Regarding our second hypothesis of coupled groundwater-surface water interactions, groundwater seepage and leaky piped infrastructure contributed significant inputs of water and N to stream reaches based on mass balance and chloride/fluoride tracer data. Regarding our third hypothesis of coupled ecosystem metabolism and carbon quality, stream metabolism increased downstream and showed potential to enhance DOC lability (e.g., ~4 times higher mean monthly primary production in urban streams than forest streams). DOC lability also increased with distance downstream and watershed urbanization based on protein and humic-like fractions, with major implications for ecosystem metabolism, biological oxygen demand, and CO2 production and alkalinity. Overall, our results showed significant in-stream retention and release (0–100 %) of watershed C and N loads over the scale of kilometers, seldom considered when evaluating monitoring, management, and restoration effectiveness. Given dynamic transport and retention across evolving spatial scales, there is a strong need to longitudinally and synoptically expand studies of hydrologic and biogeochemical processes beyond a stream reach scale along the urban watershed continuum. 相似文献
86.
The present study was undertaken to characterize leaf gas exchange physiology and photoacclimation characteristics in drought-stressed mulberry cultivar V1 (Morus indica L.) grown under the hot semi-arid steppe agroclimate of Southern India. The experiment was conducted in year 2009 during peak summer months (April–June). Mulberry plants, grown in short rotation coppice system, were subjected to two irrigation regimes: the control plot received a regulated full-rate irrigation (weekly 2–3 times) and the drought-stressed plot received a regulated deficit irrigation (irrigated only once in a fortnight). Net photosynthesis, transpiration, stomatal conductance, leaf water potential (ΨL) and photosytem-II (PS II) efficiency were examined. In spite of significant down-regulation in leaf gas exchange, the drought-stressed stands still exhibited a considerable rate of photosynthesis along with significant concomitant decrease in ΨL, more conspicuously during midday (12.00–13.00 h) depicting rather low stomatal control on ΨL, a behavior characterized as ‘anisohydric’. The PS II structural and functional integrity was well-maintained, even in the drought-stressed plants. However, apparent photoacclimatory changes were recorded in drought-exposed stands including decrease in electron transport and enhanced thermal dissipation from PS II. Overall, our data demonstrate some of the important driving leaf-level mechanisms adopted by mulberry cultivar V1 to tolerate drought stress and sustain photosynthesis. 相似文献
87.
Eric S Wisenbaugh Paul E Andrews Robert G Ferrigni Steven E Schild Sameer R Keole William W Wong Sujay A Vora 《Reviews in urology》2014,16(2):67-75
Proton beam therapy for prostate cancer has become a source of controversy in the urologic community, and the rapid dissemination and marketing of this technology has led to many patients inquiring about this therapy. Yet the complexity of the technology, the cost, and the conflicting messages in the literature have left many urologists ill equipped to counsel their patients regarding this option. This article reviews the basic science of the proton beam, examines the reasons for both the hype and the controversy surrounding this therapy, and, most importantly, examines the literature so that every urologist is able to comfortably discuss this option with inquiring patients.Key words: Prostate cancer, Proton beam therapy, External beam radiation therapy, Intensity modulated radiation therapyProton beam therapy (PBT) has become a source of controversy in the urologic community. It is not uncommon to hear mixed messages regarding the issue, from zealous advocates to cost-conscious skeptics, leaving many urologists unsure what to tell their patients with prostate cancer. What is clear, however, is that the technology is disseminating across the nation, and as our patients turn to the internet to learn more about their diagnosis, they are going to encounter increasingly more information about PBT, both scientific and promotional in nature. Hence, it is necessary for every urologist to understand the basics of PBT to help guide our patients through treatment options. This article reviews and compares the basic science of conventional external beam radiation therapy (EBRT) with PBT, examines the reasons for both the hype and the controversy surrounding this therapy, and, most importantly, examines the literature so that all urologists are adequately equipped to counsel their patients on this subject. 相似文献
88.
Melissa Lasaro Zhi Liu Rima Bishar Kathryn Kelly Sujay Chattopadhyay Sandip Paul Evgeni Sokurenko Jun Zhu Mark Goulian 《Journal of bacteriology》2014,196(9):1723-1732
The biology of Escherichia coli in its primary niche, the animal intestinal tract, is remarkably unexplored. Studies with the streptomycin-treated mouse model have produced important insights into the metabolic requirements for Escherichia coli to colonize mice. However, we still know relatively little about the physiology of this bacterium growing in the complex environment of an intestine that is permissive for the growth of competing flora. We have developed a system for studying colonization using an E. coli strain, MP1, isolated from a mouse. MP1 is genetically tractable and does not require continuous antibiotic treatment for stable colonization. As an application of this system, we separately knocked out each two-component system response regulator in MP1 and performed competitions against the wild-type strain. We found that only three response regulators, ArcA, CpxR, and RcsB, produce strong colonization defects, suggesting that in addition to anaerobiosis, adaptation to cell envelope stress is a critical requirement for E. coli colonization of the mouse intestine. We also show that the response regulator OmpR, which had previously been hypothesized to be important for adaptation between in vivo and ex vivo environments, is not required for MP1 colonization due to the presence of a third major porin. 相似文献
89.
Hadley KC Borrelli MJ Lepock JR McLaurin J Croul SE Guha A Chakrabartty A 《Cell stress & chaperones》2011,16(5):549-561
The inability of cells to maintain protein folding homeostasis is implicated in the development of neurodegenerative diseases,
malignant transformation, and aging. We find that multiphoton fluorescence imaging of 1-anilinonaphthalene-8-sulfonate (ANS)
can be used to assess cellular responses to protein misfolding stresses. ANS is relatively nontoxic and enters live cells
and cells or tissues fixed in formalin. In an animal model of Alzheimer’s disease, ANS fluorescence imaging of brain tissue
sections reveals the binding of ANS to fibrillar deposits of amyloid peptide (Aβ) in amyloid plaques and in cerebrovascular
amyloid. ANS imaging also highlights non-amyloid deposits of glial fibrillary acidic protein in brain tumors. Cultured cells
under normal growth conditions possess a number of ANS-binding structures. High levels of ANS fluorescence are associated
with the endoplasmic reticulum (ER), Golgi, and lysosomes—regions of protein folding and degradation. Nuclei are virtually
devoid of ANS binding sites. Additional ANS binding is triggered by hyperthermia, thermal lesioning, proteasome inhibition,
and induction of ER stress. We also use multiphoton imaging of ANS binding to follow the in vivo recovery of cells from protein-damaging
insults over time. We find that ANS fluorescence tracks with the binding of the molecular chaperone Hsp70 in compartments
where Hsp70 is present. ANS highlights the sensitivity of specific cellular targets, including the nucleus and particularly
the nucleolus, to thermal stress and proteasome inhibition. Multiphoton imaging of ANS binding should be a useful probe for
monitoring protein misfolding stress in cells. 相似文献
90.
Cells undergo dynamic remodeling of the cytoskeleton during adhesion and migration on various extracellular matrix (ECM) substrates in response to physiological and pathological cues. The major mediators of such cellular responses are the heterodimeric adhesion receptors, the integrins. Extracellular or intracellular signals emanating from different signaling cascades cause inside-out signaling of integrins via talin, a cystokeletal protein that links integrins to the actin cytoskeleton. Various integrin subfamilies communicate with each other and growth factor receptors under diverse cellular contexts to facilitate or inhibit various integrin-mediated functions. Since talin is an essential mediator of integrin activation, much of the integrin crosstalk would therefore be influenced by talin. However, despite the existence of an extensive body of knowledge on the role of talin in integrin activation and as a stabilizer of ECM-actin linkage, information on its role in regulating inter-integrin communication is limited. This review will focus on the structure of talin, its regulation of integrin activation and discuss its potential role in integrin crosstalk. This article is part of a Special Issue entitled: Reciprocal influences between cell cytoskeleton and membrane channels, receptors and transporters. Guest Editor: Jean Claude Hervé. 相似文献