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31.
Rossetti V Bagheri HC 《Proceedings. Biological sciences / The Royal Society》2012,279(1742):3457-3466
A fundamental advancement in the evolution of complexity is division of labour. This implies a partition of tasks among cells, either spatially through cellular differentiation, or temporally via a circadian rhythm. Cyanobacteria often employ either spatial differentiation or a circadian rhythm in order to separate the chemically incompatible processes of nitrogen fixation and photosynthesis. We present a theoretical framework to assess the advantages in terms of biomass production and population size for three species types: terminally differentiated (heterocystous), circadian, and an idealized species in which nitrogen and carbon fixation occur without biochemical constraints. On the basis of real solar irradiance data at different latitudes, we simulate population dynamics in isolation and in competition for light over a period of 40 years. Our results show that in isolation and regardless of latitude, the biomass of heterocystous cyanobacteria that optimally invest resources is comparable to that of the idealized unconstrained species. Hence, spatial division of labour overcomes biochemical constraints and enhances biomass production. In the circadian case, the strict temporal task separation modelled here hinders high biomass production in comparison with the heterocystous species. However, circadian species are found to be successful in competition for light whenever their resource investment prevents a waste of fixed nitrogen more effectively than do heterocystous species. In addition, we show the existence of a trade-off between population size and biomass accumulation, whereby each species can optimally invest resources to be proficient in biomass production or population growth, but not necessarily both. Finally, the model produces chaotic dynamics for population size, which is relevant to the study of cyanobacterial blooms. 相似文献
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33.
Bagheri J van den Berg-Emons RJ Pel JJ Horemans HL Stam HJ 《Journal of strength and conditioning research / National Strength & Conditioning Association》2012,26(3):691-696
The goal of this study was to compare the acute effects of whole-body vibration (WBV) delivered by 3 devices with different mechanical behavior on jump force (JF) and jump rate of force development (JRFD). Twelve healthy persons (4 women and 8 men; age 30.5 ± 8.8 years; height 178.6 ± 7.3 cm; body mass 74.8 ± 9.7 kg) were exposed to WBV for 15 and 40 seconds using 2 professional devices (power plate [PP; vertical vibration] and Galileo 2000 [GA; oscillatory motion around the horizontal axis in addition to vertical vibration]) and a home-use device [Power Maxx, PM; horizontal vibration]). The JF and JRFD were evaluated before, immediately after, and 5 minutes after WBV. The JF measured immediately after 40 seconds of vibration by the GA device was reduced (3%, p = 0.05), and JRFD measured after 5 minutes of rest after 40 seconds of vibration by the PM device was reduced (12%, p < 0.05) compared with the baseline value. The acute effects of WBV (15 or 40 seconds) on JF and JRFD were not significantly different among the 3 devices. In conclusion, our hypothesis that WBV devices with different mechanical behaviors would result in different acute effects on muscle performance was not confirmed. 相似文献
34.
Using first principle calculations, we investigated cation-π interactions between alkali cations (Li(+), Na(+), and K(+)) and pristine C(24) or doped fullerenes of BC(23), and NC(23). The most suitable adsorption site is found to be atop the center of a six-membered ring of the exterior surface of C(24) molecule. Interaction energies of these cations decreased in the order: Li(+)?>?Na(+)?>?K(+), with values of -31.82, -22.36, and -15.68 kcal mol(-1), respectively. It was shown that the interaction energies are increased and decreased by impurity doping of B and N atoms in adjacent wall of adsorption site, depending on electron donating or receptivity of the doping atoms. 相似文献
35.
While long-term fixation and storage of specimens is common and useful for many research projects, it is particularly important for space flight investigations where samples may not be returned to Earth for several months (International Space Station) or years (manned mission to Mars). We examined two critical challenges of space flight experimentation: the effect of long-term fixation on the quality of mouse bone preservation and the preservation of antigens and enzymes for both histochemical and immunohistochemical analyses, and how the animal/sample processing affects the preservation. We show that long-term fixation minimally affects standard histological staining, but that enzyme histochemistry and immunolabeling are greatly compromised. Further, we demonstrate that whole animal preservation is not as suitable as whole leg or stripped leg preservation for long-term fixation and all histological analyses. Overall, we recommend whole leg processing for long-term storage of bone specimens in fixative prior to embedding in plastic for histological examination. 相似文献
36.
Duringan August, 1999 field campaign, measurements were made to establish hydrologicoptical properties of the Hudson/Raritan Estuary (New York-New Jersey): 1)concurrent above-and below-surface spectral irradiance; 2) sampling forlaboratory determination of inherent optical properties; and 3) concentrationsof optically-important water quality parameters. We used a bio optical modelbased on to predict thesubsurface irradiance reflectance from optically important water constituents.This model was then validated with the measured reflectance spectra from thefield spectroradiometers. Modeling of reflectance is a prerequisite forprocessing remote sensing data to desired thematic maps. These are key input tothe geographic information system (GIS) used to manage the water qualitycondition of the estuary. 相似文献
37.
Hanieh Bagheri Tudashki Youssef Haddad Iness Charfi Rejean Couture Graciela Pineyro 《Journal of cellular and molecular medicine》2020,24(10):5718-5730
δ-opioid receptor (DOPr) agonists have analgesic efficacy in chronic pain models but development of tolerance limits their use for long-term pain management. Although agonist potential for inducing acute analgesic tolerance has been associated with distinct patterns of DOPr internalization, the association between trafficking and chronic tolerance remains ill-defined. In a rat model of streptozotocin (STZ)-induced diabetic neuropathy, deltorphin II and TIPP produced sustained analgesia following daily (intrathecal) i.t. injections over six days, whereas similar treatment with SNC-80 or SB235863 led to progressive tolerance and loss of the analgesic response. Trafficking assays in murine neuron cultures showed no association between the magnitude of ligand-induced sequestration and development of chronic tolerance. Instead, ligands that supported DOPr recycling were also the ones producing sustained analgesia over 6-day treatment. Moreover, endosomal endothelin-converting enzyme 2 (ECE2) blocker 663444 prevented DOPr recycling by deltorphin II and TIPP and precipitated tolerance by these ligands. In conclusion, agonists, which support DOPr recycling, avoid development of analgesic tolerance over repeated administration. 相似文献
38.
Background
Female only unisexual vertebrates that reproduce by hybridogenesis show an unusual genetic composition. They are of hybrid origin but show no recombination between the genomes of their parental species. Instead, the paternal genome is discarded from the germline prior to meiosis, and gametes (eggs only) contain solely unrecombined maternal genomes. Hence hybridogens only transmit maternally inherited mutations. Hybridity is restored each generation by backcrossing with males of the sexual parental species whose genome was eliminated. In contrast, recombining sexual species propagate an intermixed pool of mutations derived from the maternal and paternal parts of the genome. If mutation rates are lower in female gametes than males, it raises the possibility for lower mutation accumulation in a hybridogenetic population, and consequently, higher population fitness than its sexual counterpart. 相似文献39.
Ensieh Sajadi Sara Dadras Mohammad Bayat Shabnam Abdi Hamid Nazarian Sanaz Ziaeipour Fatemeh Mazini Mahsa Kazemi Mohammad Bagheri Aida Valizadeh Mohammad-Amin Abdollahifar 《Journal of cellular biochemistry》2019,120(10):17312-17325
The current study was conducted to assess the relationship between testicular cells in spermatogenesis, through which the production of healthy and mature sperm is essential. However, it seems necessary to obtain more information about the three-dimensional pattern of the testis cells arrangement, which is directly related to the function of the testis after induction of diabetes. Twelve adult mice (28-30 g) were assigned into two experimental groups: (1) control and (2) diabetic (40 mg/kg STZ). The epididymal sperm collected from the tail of the epididymis and testes samples were taken for stereology, immunocytochemistry and RNA extraction. Our data showed that diabetes could notably decrease the number of testicular cells, together with a reduction of total sperm count. In addition, the results from the second-order stereology indicated the significant changes in the spatial arrangement of Sertoli cells and spermatogonial cells in the diabetic groups, in comparison with the control (P < .05). Moreover, the immunohistochemistry results showed a significant reduction in Sex-determining Region Y (SRY) box 9 gene (SOX9), vimentin, occludin, and connexin-43 positive cells in the diabetic groups compared with the control (P < .05). Furthermore, our data showed that the expression of steroidogenic acute regulatory protein steroidogenic acute regulatory protein (StAR) and peripheral benzodiazepine receptor peripheral benzodiazepine receptor (PBR) was significantly reduced in the diabetic groups, in comparison with the control (P < .05). These findings suggest that structural and functional changes of testis cells after induction of diabetes cause the alterations in the spatial arrangement of Sertoli and spermatogonial cells, ultimately influencing the normal spermatogenesis in mice. 相似文献
40.
Amirhossein Bagheri Sarvestani Ebrahim Goshtasbi Rad Kamyar Iravani 《Computer methods in biomechanics and biomedical engineering》2018,21(8):532-540
In this study, laryngeal flow fields are investigated and compared in normal larynx and models of larynx with unilateral vocal fold paralysis (UVFP). In paralytic models, three fixed initial glottal gaps are considered to understand the positive or probable negative impacts of surgical operation on unilaterally paralytic larynx, by which the paralyzed vocal fold is brought closer to the mid-plane. Various features of the flow fields have been discussed in detail including glottal gap width, glottal flow rate, glottal exit pressure pattern and glottal jet evolution. The numerical solution of fluid-structure interaction is carried out using ANSYS, and the results confirm some of the favorable effects of surgery on the patient’s larynx. It is also shown that by tightening the glottal gap, some of the problems caused by the presence of a motionless vocal fold, such as leakage through glottal gap in the closure phase resulting in breathy voice can be moderated, although some of the symptoms of this disorder remain relatively unchanged. 相似文献