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71.
Vivian de Buffrénil Aurore Canoville Ruggero D’Anastasio Daryl P. Domning 《Journal of Mammalian Evolution》2010,17(2):101-120
Osteosclerosis, or inner bone compaction, and pachyostosis, or outer hyperplasy of bone cortices (swollen bones), are typical
features of tetrapods secondarily adapted to life in water. These peculiarities are spectacularly exemplified by the ribs
of extant and extinct Sirenia. Sea cows are thus the best model for studying this kind of bone structural specializations.
In order to document how these features differentiated during sirenian evolution, the ribs of 15 species, from the most basal
form (Pezosiren portelli) up to extant taxa, were studied, and compared to those of other mammalian species from both morphometric and histological
points of view. Pachyostosis was the first of these two specializations to occur, by the middle of the Eocene, and is a basal
feature of the Sirenia. However, it subsequently regressed in some taxa that do not exhibit hyperplasic rib cortices. Osteosclerosis
was only incipient in P. portelli. Its full development occurred later, by the end of the Eocene. These two structural specializations of bone are variably
pronounced in extinct and extant sirenians, and relatively independent from each other, although frequently associated. They
are possibly due to similar heterochronic mechanisms bearing on the timing of osteoblast activity. These results are discussed
with respect to the functional constraints of locomotion in water. 相似文献
72.
Lázaro Molina Ruggero La Rosa Juan Nogales Fernando Rojo 《Environmental microbiology》2019,21(7):2375-2390
Pseudomonas putida is a soil bacterium with a versatile and robust metabolism. When confronted with mixtures of carbon sources, it prioritizes the utilization of the preferred compounds, optimizing metabolism and growth. This response is particularly strong when growing in a complex medium such as LB. This work examines the changes occurring in P. putida KT2440 metabolic fluxes, while it grows exponentially in LB medium and sequentially consumes the compounds available. Integrating the uptake rates for each compound at three different moments during the exponential growth with the changes observed in the proteome, and with the metabolic fluxes predicted by the iJN1411 metabolic model for this strain, allowed the metabolic rearrangements that occurred to be determined. The results indicate that the bacterium changes significantly the configuration of its metabolism during the early, mid and late exponential phases of growth. Sugars served as an energy source during the early phase and later as energy and carbon source. The configuration of the tricarboxylic acids cycle varied during growth, providing no energy in the early phase, and turning to a reductive mode in the mid phase and to an oxidative mode later on. This work highlights the dynamism and flexibility of P. putida metabolism. 相似文献
73.
74.
75.
F. Papi L. Pardi 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1959,41(6):583-596
Zusammenfassung Mittels einer neuen Versuchseinrichtung wird die Fähigkeit der Amphipoden Talitrus saltator (Montagu) sich mit dem Mond meereseinwärts zu orientieren untersucht. Es wurden zwei Populationen verschieden orientierter Küsten benutzt, die eine mit Fluchtrichtung ungefähr nach Westen, die zweite mit Fluchtrichtung etwa nach Südsüdwest. Eine richtige Orientierung der Tiere, die unmittelbar vor dem Versuch gesammelt wurden, wird bei verschiedenen Mondphasen und-ständen bestätigt. Aber auch Tiere, welche am vorigen Sonnenuntergang oder sogar am vorigen Neumond erbeutet und dann ständig im Dunkel gehalten wurden, sind meistens richtig orientiert. Es wird behauptet, daß zwei verschiedene physiologische Rhythmen die Sonnenund die Mondorientierung von Talitrus bedingen. 相似文献
76.
Ophiobolin B (OPH B), a sesterpene metabolite of Helminthosporium oryzae, inhibits proton extrusion from maize coleoptiles. Moreover OPH B counteracts the biological activity of fusicoccin (FC), another terpenoid toxin produced by Fusicoccum amygdali having a similar basic chemical structure: OPH B inhibits FC-promoted proton extrusion, potassium uptake and cell enlargement.The findings suggest that the effect of OPH B in stimulating electrolites, glucose and aminoacid leakage, reported in a previous paper, can be explained by the capacity of the toxin to inhibit proton extrusion.Abbreviations FC
fusicoccin
- OPH B
ophiobolin B 相似文献
77.
doi: 10.1111/j.1741‐2358.2011.00536.x Effect of ill‐fitting dentures on the swallowing duration in patients using polygraphy Background: Surface electromyography (SEMG) has been widely used in the recent years to study swallowing physiology, offering a valid and reliable tool for identifying normal swallowing. The goal of our study was to assess the contribution of denture fitness in the age‐related increase of swallowing duration. Methods: Twenty denture wearers and 20 dentate individuals were analysed using SEMG and a computerised kinesiography of mandibular movement. Three spontaneous saliva swallowings were recorded for each patient with both their old and new prostheses. Three spontaneous saliva swallowings were recorded for each dentate person in two different recording sessions. Results: Old prosthesis mean swallowing time was 1.84 (SD ± 0.85) seconds while the new well‐fitting prostheses needed a 1.28 (SD ± 0.55) (p = 0.0009) swallowing time. The difference in swallowing time was significant (p = 0.01) between dentate subjects and individuals wearing an old prosthesis. No significant difference was found between dentate subjects and the same prosthesis wearers when a new well‐fitting prosthesis was worn. Conclusion: Data presented in this work suggest that part of the increased duration of swallowing showed by elderly and healthy people is because of incorrect an dental prosthesis. Prolongation of swallowing duration in the elderly population could be reconsidered in the light of the quality of dental device worn by the aged population. 相似文献
78.
79.
Chiocchetti R Grandis A Bombardi C Lucchi ML Dal Lago DT Bortolami R Furness JB 《Cell and tissue research》2006,323(2):183-196
To investigate extrinsic origins of calcitonin gene-related peptide immunoreactive (CGRP-IR) nerve fibres in the sheep ileum,
the retrograde fluorescent tracer Fast Blue (FB) was injected into the ileum wall. Sections of thoraco-lumbar dorsal root
ganglia (DRG) and distal (nodose) vagal ganglia showing FB-labelled neurons were processed for CGRP immunohistochemistry.
The distribution of CGRP-IR in fibres and nerve cell bodies in the ileum was also studied. CGRP-IR enteric neurons were morphometrically
analysed in myenteric (MP) and submucosal plexuses (SMP) of lambs (2–4 months). Sensory neurons retrogradely labelled with
FB were scattered in T5-L4 DRG but most were located at the upper lumbar levels (L1-L3); only a minor component of the extrinsic
afferent innervation of the ileum was derived from nodose ganglia. In the DRG, 57% of retrogradely labelled neurons were also
CGRP-IR. In cryostat sections, a dense network of CGRP-IR fibres was observed in the lamina propria beneath the epithelium,
around the lacteals and lymphatic follicles (Peyer's platches), and along and around enteric blood vessels. Rare CGRP-IR fibres
were also present in both muscle layers. Dense pericellular baskets of CGRP-IR fibres were observed around CGRP-negative somata.
The only CGRP-IR nerve cells were well-defined Dogiel type II neurons localised in the MP and in the external and internal
components of the SMP. CGRP-IR neurons in the myenteric ganglia were significantly larger than those in the submucosal ganglia
(mean profile areas: about 1,400 μm2 for myenteric neurons, 750 μm2 for submucosal neurons). About 6% of myenteric neurons and 25% of submucosal neurons were CGRP-IR Dogiel type II neurons.
The percentages of CGRP-IR neurons that were also tachykinin-IR were about 9% (MP) and 42% (SMP), whereas no CGRP-IR neurons
exhibited immunoreactivity for vasoactive intestinal peptide, nitric oxide synthase or tyrosine hydroxylase in either plexus.
Thus, CGRP immunoreactivity occurs in the enteric nervous system of the sheep ileum (as in human small intestine and MP of
pig ileum) in only one morphologically defined type of neuron, Dogiel type II cells. These are probably intrinsic primary
afferent neurons.
This work was supported by grants from the Ricerca Fondamentale Orientata (RFO) and Fondazione Del Monte di Bo e Ra. 相似文献
80.
Morris E Feldman Beth Apsel Aino Uotila Robbie Loewith Zachary A Knight Davide Ruggero Kevan M Shokat 《PLoS biology》2009,7(2)
The mammalian target of rapamycin (mTOR) regulates cell growth and survival by integrating nutrient and hormonal signals. These signaling functions are distributed between at least two distinct mTOR protein complexes: mTORC1 and mTORC2. mTORC1 is sensitive to the selective inhibitor rapamycin and activated by growth factor stimulation via the canonical phosphoinositide 3-kinase (PI3K)→Akt→mTOR pathway. Activated mTORC1 kinase up-regulates protein synthesis by phosphorylating key regulators of mRNA translation. By contrast, mTORC2 is resistant to rapamycin. Genetic studies have suggested that mTORC2 may phosphorylate Akt at S473, one of two phosphorylation sites required for Akt activation; this has been controversial, in part because RNA interference and gene knockouts produce distinct Akt phospho-isoforms. The central role of mTOR in controlling key cellular growth and survival pathways has sparked interest in discovering mTOR inhibitors that bind to the ATP site and therefore target both mTORC2 and mTORC1. We investigated mTOR signaling in cells and animals with two novel and specific mTOR kinase domain inhibitors (TORKinibs). Unlike rapamycin, these TORKinibs (PP242 and PP30) inhibit mTORC2, and we use them to show that pharmacological inhibition of mTOR blocks the phosphorylation of Akt at S473 and prevents its full activation. Furthermore, we show that TORKinibs inhibit proliferation of primary cells more completely than rapamycin. Surprisingly, we find that mTORC2 is not the basis for this enhanced activity, and we show that the TORKinib PP242 is a more effective mTORC1 inhibitor than rapamycin. Importantly, at the molecular level, PP242 inhibits cap-dependent translation under conditions in which rapamycin has no effect. Our findings identify new functional features of mTORC1 that are resistant to rapamycin but are effectively targeted by TORKinibs. These potent new pharmacological agents complement rapamycin in the study of mTOR and its role in normal physiology and human disease. 相似文献