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31.
Plant and Soil - Southern South American Proteaceae can occupy soils that are rich in total phosphorus (P) but poor in available P (for example volcanic soils) thanks to their cluster roots (CR),... 相似文献
32.
James A. Simmons Andrea Megela Simmons 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》2011,197(5):585-594
Widely divergent vertebrates share a common central temporal mechanism for representing periodicities of acoustic waveform events. In the auditory nerve, periodicities corresponding to frequencies or rates from about 10 Hz to over 1,000 Hz are extracted from pure tones, from low-frequency complex sounds (e.g., 1st harmonic in bullfrog calls), from mid-frequency sounds with low-frequency modulations (e.g., amplitude modulation rates in cat vocalizations), and from time intervals between high-frequency transients (e.g., pulse-echo delay in bat sonar). Time locking of neuronal responses to periodicities from about 50 ms down to 4 ms or less (about 20–300 Hz) is preserved in the auditory midbrain, where responses are dispersed across many neurons with different onset latencies from 4–5 to 20–50 ms. Midbrain latency distributions are wide enough to encompass two or more repetitions of successive acoustic events, so that responses to multiple, successive periods are ongoing simultaneously in different midbrain neurons. These latencies have a previously unnoticed periodic temporal pattern that determines the specific times for the dispersed on-responses. 相似文献
33.
Corica F Corsonello A Apolone G Lucchetti M Melchionda N Marchesini G;QUOVADIS Study Group 《Obesity (Silver Spring, Md.)》2006,14(8):1429-1437
Objective: To investigate the construct validity of the Short Form‐36 (SF‐36) Health Survey questionnaire in obese patients. Research Methods and Procedures: Our series consisted of 1735 obese patients (age, 44.7 ± 11.0 years; 1346 women) consecutively enrolled in the QUOVADIS study, an observational multicenter study of obese treatment‐seeking outpatients. The construct validity of the SF‐36 was assessed by main component analysis. Age‐, gender‐, and education‐adjusted general linear models were used to investigate the relationship between BMI and SF‐36 domains or factors identified by main component analysis. Results: BMI was significantly associated with poor health‐related quality of life in all eight SF‐36 domains, and the strongest association was observed with physical activity. Main components analysis generated a six‐factor solution explaining 59% of the observed variance. BMI was strongly associated with factors based on the loading of items regarding the physical activity domain and factors based on role‐physical and role‐emotional items or general health and bodily pain items. In contrast, mental health‐, vitality‐, and social functioning‐based factors were not related to BMI. Discussion: In obese treatment‐seeking outpatients, the clustering of SF‐36 items in main components is not significantly different from the domain‐based approach generally used, thus confirming the robustness of such a generic questionnaire in this specific condition. However, the peculiar clustering of some SF‐36 items and their relationship with BMI suggest that the health‐related quality of life profile of subjects belonging to that population may be better described with alternative aggregations of the SF‐36 items or with disease‐tailored questionnaires. 相似文献
34.
Ryan Wilcox Bryan E Welm Jeffrey T Chang Evan Johnson Avrum Spira Stefanie S Jeffrey Andrea H Bild 《Molecular systems biology》2011,7(1)
Identifying the best drug for each cancer patient requires an efficient individualized strategy. We present MATCH (M erging genomic and pharmacologic A nalyses for T herapy CH oice), an approach using public genomic resources and drug testing of fresh tumor samples to link drugs to patients. Valproic acid (VPA) is highlighted as a proof‐of‐principle. In order to predict specific tumor types with high probability of drug sensitivity, we create drug response signatures using publically available gene expression data and assess sensitivity in a data set of >40 cancer types. Next, we evaluate drug sensitivity in matched tumor and normal tissue and exclude cancer types that are no more sensitive than normal tissue. From these analyses, breast tumors are predicted to be sensitive to VPA. A meta‐analysis across breast cancer data sets shows that aggressive subtypes are most likely to be sensitive to VPA, but all subtypes have sensitive tumors. MATCH predictions correlate significantly with growth inhibition in cancer cell lines and three‐dimensional cultures of fresh tumor samples. MATCH accurately predicts reduction in tumor growth rate following VPA treatment in patient tumor xenografts. MATCH uses genomic analysis with in vitro testing of patient tumors to select optimal drug regimens before clinical trial initiation. 相似文献
35.
Anne Chevrel Agnes Mesneau Dyana Sanchez Louisa Celma Sophie Quevillon-Cheruel Andrea Cavagnino Sylvie Nessler Ines Li de la Sierra-Gallay Herman van Tilbeurgh Philippe Minard Marie Valerio-Lepiniec Agathe Urvoas 《Journal of structural biology》2018,201(2):88-99
We have previously described a highly diverse library of artificial repeat proteins based on thermostable HEAT-like repeats, named αRep. αReps binding specifically to proteins difficult to crystallize have been selected and in several examples, they made possible the crystallization of these proteins. To further simplify the production and crystallization experiments we have explored the production of chimeric proteins corresponding to covalent association between the targets and their specific binders strengthened by a linker. Although chimeric proteins with expression partners are classically used to enhance expression, these fusions cannot usually be used for crystallization. With specific expression partners like a cognate αRep this is no longer true, and chimeric proteins can be expressed purified and crystallized. αRep selection by phage display suppose that at least a small amount of the target protein should be produced to be used as a bait for selection and this might, in some cases, be difficult. We have therefore transferred the αRep library in a new construction adapted to selection by protein complementation assay (PCA). This new procedure allows to select specific binders by direct interaction with the target in the cytoplasm of the bacteria and consequently does not require preliminary purification of target protein. αRep binders selected by PCA or by phage display can be used to enhance expression, stability, solubility and crystallogenesis of proteins that are otherwise difficult to express, purify and/or crystallize. 相似文献
36.
Susan M. Rankin Sarah K. Storm Dana L. Pieto Andrea L. Risser 《Journal of Insect Behavior》1996,9(1):85-103
The expression and maintenance of maternal behavior in the earwig,Euborellia annulipes, was examined through manipulation of clutch size, age, and species and through observations of interactions between brooding females. Females underwent discrete gonadotrophic cycles culminating in oviposition of first clutches that were highly variable in size. Neither the head capsule width nor the age of the mother was correlated with clutch size. Maternal care extended through embryogenesis and for the week following hatching. Clutch removal significantly shortened the interclutch interval, indicating that the presence of brood inhibited the onset of the second gonadotrophic cycle. Brooding females readily accepted replacement clutches of the same age. Thus, mothers did not appear to distinguish their own eggs from those of other females. Experimental doubling of clutch size did not significantly reduce the proportion hatching or fledging. In contrast, reducing clutch size diminished the percentage successfully fledging. Manipulation of clutch age resulted in reduced hatching/fledging success. Placing two females, each with newly laid clutches, in the same cage usually resulted in egg transfer from the nest of one female to that of the other within 12 h. Nests of females with larger forceps were significantly more likely to contain both clutches. When mothers with first clutches were paired with mothers with third clutches, eggs were more likely to be transferred to the nest of the older female.E. annulipes females with newly laid clutches appeared to accept as replacement clutches eggs of the earwigDoru taeniatum. Alien clutches were maintained for the typical duration of embryogenesis; however, noD. taeniatum hatchlings were observed. 相似文献
37.
Rosalie J. Harris Callum Bryant Melinda A. Coleman Andrea Leigh Verónica F. Briceño Pieter A. Arnold Adrienne B. Nicotra 《Journal of phycology》2023,59(1):179-192
Foundation seaweed species are experiencing widespread declines and localized extinctions due to increased instability of sea surface temperature. Characterizing temperature thresholds are useful for predicting patterns of change and identifying species most vulnerable to extremes. Existing methods for characterizing seaweed thermal tolerance produce diverse metrics and are often time-consuming, making comparisons between species and techniques difficult, hindering insight into global patterns of change. Using three kelp species, we adapted a high-throughput method – previously used in terrestrial plant thermal biology – for use on kelps. This method employs temperature-dependent fluorescence (T–F0) curves under heating or cooling regimes to determine the critical temperature (Tcrit) of photosystem II (PSII), i.e., the breakpoint between slow and fast rise fluorescence response to changing temperature, enabling rapid assays of photosynthetic thermal tolerance using a standardized metric. This method enables characterization of Tcrit for up to 48 samples per two-hour assay, demonstrating the capacity of T–F0 curves for high-throughput assays of thermal tolerance. Temperature-dependent fluorescence curves and their derived metric, Tcrit, may offer a timely and powerful new method for the field of phycology, enabling characterization and comparison of photosynthetic thermal tolerance of seaweeds across many populations, species, and biomes. 相似文献
38.
Anna Corcione Elisa Ferretti Maria Bertolotto Franco Fais Lizzia Raffaghello Andrea Gregorio Claudya Tenca Luciano Ottonello Claudio Gambini Glaucia Furtado Sergio Lira Vito Pistoia 《PloS one》2009,4(12)
Background
Fractalkine/CX3CL1, a surface chemokine, binds to CX3CR1 expressed by different lymphocyte subsets. Since CX3CL1 has been detected in the germinal centres of secondary lymphoid tissue, in this study we have investigated CX3CR1 expression and function in human naïve, germinal centre and memory B cells isolated from tonsil or peripheral blood.Methodology/Principal Findings
We demonstrate unambiguously that highly purified human B cells from tonsil and peripheral blood expressed CX3CR1 at mRNA and protein levels as assessed by quantitative PCR, flow cytometry and competition binding assays. In particular, naïve, germinal centre and memory B cells expressed CX3CR1 but only germinal centre B cells were attracted by soluble CX3CL1 in a transwell assay. CX3CL1 signalling in germinal centre B cells involved PI3K, Erk1/2, p38, and Src phosphorylation, as assessed by Western blot experiments. CX3CR1+ germinal centre B cells were devoid of centroblasts and enriched for centrocytes that migrated to soluble CX3CL1. ELISA assay showed that soluble CX3CL1 was secreted constitutively by follicular dendritic cells and T follicular helper cells, two cell populations homing in the germinal centre light zone as centrocytes. At variance with that observed in humans, soluble CX3CL1 did not attract spleen B cells from wild type mice. OVA immunized CX3CR1−/− or CX3CL1−/− mice showed significantly decreased specific IgG production compared to wild type mice.Conclusion/Significance
We propose a model whereby human follicular dendritic cells and T follicular helper cells release in the light zone of germinal centre soluble CX3CL1 that attracts centrocytes. The functional implications of these results warrant further investigation. 相似文献39.
Sandra Münder Susanne Tischer Maresa Grundhuber Nathalie Büchels Nadine Bruckmeier Stefanie Eckert Carolin A. Seefeldt Andrea Prexl Tina Käsbauer Angelika Böttger 《Developmental biology》2013
Local self-activation and long ranging inhibition provide a mechanism for setting up organising regions as signalling centres for the development of structures in the surrounding tissue. The adult hydra hypostome functions as head organiser. After hydra head removal it is newly formed and complete heads can be regenerated. The molecular components of this organising region involve Wnt-signalling and β-catenin. However, it is not known how correct patterning of hypostome and tentacles are achieved in the hydra head and whether other signals in addition to HyWnt3 are needed for re-establishing the new organiser after head removal. Here we show that Notch-signalling is required for re-establishing the organiser during regeneration and that this is due to its role in restricting tentacle activation. Blocking Notch-signalling leads to the formation of irregular head structures characterised by excess tentacle tissue and aberrant expression of genes that mark the tentacle boundaries. This indicates a role for Notch-signalling in defining the tentacle pattern in the hydra head. Moreover, lateral inhibition by HvNotch and its target HyHes are required for head regeneration and without this the formation of the β-catenin/Wnt dependent head organiser is impaired. Work on prebilaterian model organisms has shown that the Wnt-pathway is important for setting up signalling centres for axial patterning in early multicellular animals. Our data suggest that the integration of Wnt-signalling with Notch-Delta activity was also involved in the evolution of defined body plans in animals. 相似文献
40.
Kaiser R Bunnell R Hightower A Kim AA Cherutich P Mwangi M Oluoch T Dadabhai S Mureithi P Mugo N Mermin J;KAIS Study Group 《PloS one》2011,6(3):e17842