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991.
To prevent predation on their eggs, prey often avoid patches occupied by predators. As a result, they need to delay oviposition
until they reach predator-free patches. Because many species allocate energy to egg production in a continuous fashion, it
is not clear what kind of mechanism prey use to delay oviposition. We used females of the phytoseiid mite Neoseiulus cucumeris to study these mechanisms. Females were placed in patches with pollen, a food source they use for egg production, and they
were exposed to another phytoseiid mite, Iphiseius degenerans, which is an intraguild predator of N. cucumeris juveniles. We found that the oviposition of N. cucumeris females on patches with the predator was lower than on patches without the predator. Cues left by the intraguild predator
were not sufficient to elicit such behaviour. Females of N. cucumeris reduced oviposition when exposed to the predator by retaining the egg inside their body, resulting in a lower developmental
rate once these eggs were laid. Hence, females are capable of retaining eggs, but the development of these eggs continues
inside the mother’s body. In this way, females gain some time to search for less risky oviposition sites. 相似文献
992.
Filippo Conti Maria Cristina Valerio Joseph P. Zbilut Alessandro Giuliani 《Systems and synthetic biology》2007,1(4):161-165
A biological system, like any complex system, blends stochastic and deterministic features, displaying properties of both.
In a certain sense, this blend is exactly what we perceive as the “essence of complexity” given we tend to consider as non-complex
both an ideal gas (fully stochastic and understandable at the statistical level in the thermodynamic limit of a huge number
of particles) and a frictionless pendulum (fully deterministic relative to its motion). In this commentary we make the statement
that systems biology will have a relevant impact on nowadays biology if (and only if) will be able to capture the essential
character of this blend that in our opinion is the generation of globally ordered collective modes supported by locally stochastic
atomisms. 相似文献
993.
We studied 3H-glycine and 3H-strychnine specific binding to glycine receptor (GlyR) in intact isolated frog retinas. To avoid glycine binding to glycine uptake sites, experiments were performed at low ligand concentrations in a sodium-free medium. The binding of both radiolabeled ligands was saturated. Scatchard analysis of bound glycine and strychnine revealed a KD of 2.5 and 2.0 M, respectively. Specific binding of glycine was displaced by -alanine, sarcosine, and strychnine. Strychnine binding was displaced 50% by glycine, and sarcosine. Properties of the strychnine-binding site in the GlyR were modified by sarcosine. Binding of both radioligands was considerably reduced by compounds that inhibit or activate adenylate cyclase and increased cAMP levels. A phorbol ester activator of PKC remarkably decreased glycine and strychnine binding. These results suggest modulation of GlyR in response to endogenous activation of protein kinases A and C, as well as protein phosphorylation modulating GlyR function in retina. 相似文献
994.
New record of Scomberesox scombroides (Richardson, 1843) (Beloniformes: Scomberesocidae) in southwestern waters of Patagonia and an update on its geographic distribution on the Argentine continental shelf 下载免费PDF全文
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998.
Cristina M. Al Matarneh Ionel I. Mangalagiu Sergiu Shova 《Journal of enzyme inhibition and medicinal chemistry》2016,31(3):470-480
A study concerning design, synthesis, structure and in vitro antimycobacterial and anticancer evaluation of new fused derivatives with pyrrolo[2,1-c][4,7]phenanthroline skeleton is described. The strategy adopted for synthesis involves a [3?+?2] dipolar cycloaddition of several in situ generated 4,7-phenanthrolin-4-ium ylides to different substituted alkynes and alkenes. Stereo- and regiochemistry of cycloaddition reactions were discussed. The structure of the new compounds was proven unambiguously, single-crystal X-ray diffraction studies including. The antimycobacterial and anticancer activity of a selection of new synthesized compounds was evaluated against Mycobacterium tuberculosis H37Rv under aerobic conditions and 60 human tumour cell line panel, respectively. Five of the tested compounds possess a moderate antimycobacterial activity, while two of the compounds have a significant antitumor activity against renal cancer and breast cancer. 相似文献
999.
Salinity remarkably inhibits NO3 - uptake but the mechanisms are not well understood. This study was addressed to elucidate the role of ionic and osmotic components of salinity on NO3 - influx and efflux employing classic kinetics involving a low affinity transport system (LATS) and a high affinity transport system (HATS). In the presence of KCl, NaCl, and Na2SO4 at 100 mM concentrations, in both LATS and HATS, Michaelis constant (Km) was similar for the three salts and maximum rate (Vmax) decreased as follows: KCl > NaCl > Na2SO4, compared to control indicating a non-competitive interaction with NO3 -. Unexpectedly, iso-osmotic solutions (osmotic potential Ψπ = -0.450) of polyethylene glycol (PEG, 17.84 %, v/v) and mannitol (100 mM) remarkably increased Km in both the LATS and the HATS, but Vmax did not change indicating a competitive inhibition. Under the PEG and mannitol treatments, Km and Vmax were higher than under the salt treatments. The salts increased slightly NO3 - efflux in the following order KCl > NaCl > Na2SO4. In contrast, mannitol strongly stimulated and the PEG inhibited NO3 - efflux. The obtained data reveal that salinity effects were not dependent on the anion type (Cl- versus SO4 2-) indicating a non-competitive inhibition mechanism between Cl- and NO3 -. In contrast, the cation types (K+ versus Na+) had a pronounced effect. The osmotic component is important to net NO3 - uptake affecting remarkably the influx in both LATS and HATS components of cowpea roots. 相似文献
1000.
Mañes S Llorente M Lacalle RA Gómez-Moutón C Kremer L Mira E Martínez-A C 《The Journal of biological chemistry》1999,274(11):6935-6945
The androgen-independent human prostate adenocarcinoma cell line DU-145 proliferates in serum-free medium and produces insulin-like growth factors (IGF)-I, IGF-II, and the IGF type-1 receptor (IGF-1R). They also secrete three IGF-binding proteins (IGFBP), IGFBP-2, -3, and -4. Of these, immunoblot analysis revealed selective proteolysis of IGFBP-3, yielding fragments of 31 and 19 kDa. By using an anti-IGF-I-specific monoclonal antibody (mAb), we detect surface receptor-bound IGF-I on serum-starved DU-145 cells, which activates IGF-1R and triggers a mitogenic signal. Incubation of DU-145 cells with blocking anti-IGF-I, anti-IGF-II, or anti-IGF-I plus anti-IGF-II mAb does not, however, inhibit serum-free growth of DU-145. Conversely, anti-IGF-1R mAb and IGFBP-3 inhibit DNA synthesis. IGFBP-3 also modifies the DU-145 cell cycle, decreases p34(cdc2) levels, and IGF-1R autophosphorylation. The antiproliferative IGFBP-3 activity is not IGF-independent, since des-(1-3)IGF-I, which does not bind to IGFBP-3, reverses its inhibitory effect. DU-145 also secretes the matrix metalloproteinase (MMP)-9, which can be detected in both a soluble and a membrane-bound form. Matrix metalloproteinase inhibitors, but not serpins, abrogate DNA synthesis in DU-145 associated with the blocking of IGFBP-3 proteolysis. Overexpression of an antisense cDNA for MMP-9 inhibits 80% of DU-145 cell proliferation that can be reversed by IGF-I in a dose-dependent manner. Inhibition of MMP-9 expression is also associated with a decrease in IGFBP-3 proteolysis and with reduced signaling through the IGF-1R. Our data indicate an IGF autocrine loop operating in DU-145 cells, specifically modulated by IGFBP-3, whose activity may in turn be regulated by IGFBP-3 proteases such as MMP-9. 相似文献