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991.
    
The Drosophila inner photoreceptors R7 and R8 are responsible for color vision and their differentiation starts at the third instar larval stage. Only a handful of genes with R7 or R8-cell-specific expression are known. We performed an enhancer-trap screen using a novel piggyBac transposable element, pBGay, carrying a Gal4 sequence under the control of the P promoter to identify novel genes expressed specifically in R7 or R8 cells. From this screen, three lines were analyzed in detail: piggyBacAC109 and piggyBacAC783 are expressed in R8 cells and piggyBacAC887 is expressed in R7 cells at the third instar larval stage and pupal stages. Molecular analysis showed that the piggyBac elements were inserted into the first intron of CG14160 and CG7985 genes and the second intron of unzipped. We show the expression pattern in the developing eye imaginal disc, pupal retina as well as the adult retina. The photoreceptor-specific expression of these genes is reported for the first time and we propose that these lines are useful tools for studying the development of the visual system.  相似文献   
992.
    
Biomechanics and Modeling in Mechanobiology - The microstructure for mature vessels has been investigated in detail, while there is limited information about the embryonic stages, in spite of their...  相似文献   
993.
    
The continuously increasing usage of cell phones has raised concerns about the adverse effects of microwave radiation (MWR) emitted by cell phones on health. Several in vitro and in vivo studies have claimed that MWR may cause various kinds of damage in tissues. The aim of this study is to examine the possible effects of exposure to low‐intensity MWR on DNA and oxidative damage in the livers of rats. Eighteen Sprague–Dawley male rats were divided into three equal groups randomly (n = 6). Group 1 (Sham‐control): rats were kept under conditions the same as those of other groups, except for MWR exposure. Group 2: rats exposed to 1800 MHz (SAR: 0.62 W/kg) at 0.127 ± 0.04 mW/cm2 power density, and Group 3: rats exposed to 2,100 MHz (SAR: 0.2 W/kg) at 0.038 ± 0.03 mW/cm2 power density. Microwave application groups were exposed to MWR 2 h/day for 7 months. At the end of the exposure period, the rats were sacrificed and DNA damage, malondialdehyde (MDA), 8‐hydroxydeoxyguanosine (8‐OHdG), and total oxidant‐antioxidant parameter analyses were conducted in their liver tissue samples. It was found that 1800 and 2100 MHz low‐intensity MWR caused a significant increase in MDA, 8‐OHdG, total oxidant status, oxidative stress index, and comet assay tail intensity (P < 0.05), while total antioxidant status levels (P < 0.05) decreased. The results of our study showed that whole‐body exposure to 1800 and 2100 MHz low‐intensity MWR emitted by cell phones can induce oxidative stress by altering oxidant‐antioxidant parameters and lead to DNA strand breaks and oxidative DNA damage in the liver of rats. Bioelectromagnetics. 2021;42:76–85. © 2020 Bioelectromagnetics Society  相似文献   
994.
995.
Protein conformational changes that result in misfolding, aggregation and amyloid fibril formation are a common feature of many neurodegenerative disorders. Studies with beta-amyloid (Abeta), alpha-synuclein and other amyloid-forming proteins indicate that the assembly of misfolded protein conformers into fibrils is a complex process that may involve the population of metastable spherical and/or annular oligomeric assemblies. Here, we show by atomic force microscopy that a mutant huntingtin fragment with an expanded polyglutamine repeat forms spherical and annular oligomeric structures reminiscent of those formed by Abeta and alpha-synuclein. Notably, the molecular chaperones Hsp70 and Hsp40, which are protective in animal models of neurodegeneration, modulate polyglutamine aggregation reactions by partitioning monomeric conformations and disfavoring the accretion of spherical and annular oligomers.  相似文献   
996.
  总被引:1,自引:0,他引:1  
The effects of streptomycin sulfate, gentamicin sulfate, thiamphenicol, penicillin G, teicoplanin, ampicillin, cefotaxime, and cefodizime on the enzyme activity of glutathione reductase (GR) were studied using human and rat erythrocyte GR enzymes in in vitro and in vivo studies, respectively. The enzyme was purified 5,342-fold from human erythrocytes in a yield of 29% with 50.75 U/mg. The purification procedure involved the preparation of hemolysate, ammonium sulfate precipitation, 2',5'-ADP Sepharose 4B affinity chromatography and Sephadex G-200 gel filtration chromatography. Purified enzyme was used in the in vitro studies, and rat erythrocyte hemolysate was used in the in vivo studies. In the in vitro studies, I50 and K(i) values were 12.179 mM and 6.5123 +/- 4.1139 mM for cefotaxime, and 1.682 mM and 0.7446 +/- 0.2216 mM for cefodizime, respectively, showing the inhibition effects on the purified enzyme. Inhibition types were noncompetitive for cefotaxime and competitive for cefodizime. In the in vivo studies, 300 mg/kg cefotaxime and 1000 mg/kg cefodizime when administered to rats inhibited enzyme activity during the first 2h (p < 0.01). Cefotaxime led to increased enzyme activity at 4h (p < 0.05), but neither cefotaxime nor cefodizime had any significant inhibition or activation effects over 6 h (p > 0.05).  相似文献   
997.
    
The firing-rate-based population model for rapidly-adapting (RA) mechanoreceptive fibers by Güçlü and Bolanowski (Güçlü B, Bolanowski SJ. 2002. Modeling population responses of rapidly-adapting mechanoreceptive fibers. Journal of Computational Neuroscience 12:201–218.) is extended by including temporal-response properties of RA fibers. This representation allows for the generation of action-potential (spike) times for each fiber when a sinusoidal, steady-state stimulus is applied onto the skin. Signal detection theory was used to predict human psychophysical thresholds. Specifically, the effects of sensorineural innervation pattern, stimulus-contactor location and selected decision rules on the model predictions were studied. The predicted thresholds were lowest when the decision rule was one spike and highest when many active fibers were required for detection. These predictions were empirically tested by measuring vibrotactile thresholds of the Non-Pacinian I (NP I) channel, which required the special techniques discussed in the preceding article. Although the model predicted thresholds to decrease distally due to the known innervation density which is higher distally, the thresholds of the NP I psychophysical channel were found to be approximately constant (20–25?dB re 1?µm peak amplitude) from the proximal site on the terminal phalanx to the most distal portion. Interestingly, the mechanical impedance of the skin was found not to be constant along the proximo-distal axis. This latter result implies that the space-invariant mechanical attenuation function used in the model may not be valid at every location on the fingertip. Because of this, the discrepancy between the model's predictions and the psychophysical results may be reconciled.  相似文献   
998.
A new series of benzimidazole compounds including hydrazinecarbothioamide, 1,2,4-triazole, 1,3,4-oxadiazole and imine function were synthesized starting from 5,6-dichloro-2-cyclopropyl-1H-benzimidazole. All of the benzimidazole derivatives exhibited good urease inhibitor activity. Compound 6a proved to be the most potent showing an enzyme inhibitory activity with an IC50 = 0.06 µM. Molecular docking studies were also conducted on enzyme extracted from Jack bean urease to identify the binding mode of the newly synthesized compounds.  相似文献   
999.
In order to successfully cryopreserve oocytes using low concentrations of intracellular sugars, it is important to characterize their osmotic response in the presence of these intracellular sugars. In the present study, murine (B6D2F1) oocytes were microinjected with 0.8M glucose, trehalose or stachyose solutions to achieve an intracellular concentration equivalent to 0.1M, and then exposed to hypertonic solutions of increasing strength by supplementing an isotonic solution with 0.2, 0.3, 0.5, and 0.7 M of trehalose. Analysis of volumetric response of microinjected oocytes showed that the oocytes behaved as ideal osmometers in the presence of intracellular sugars and satisfied the Boyle van't Hoff relationship. Extrapolation of the osmotically inactive fraction (V macro b) from the Boyle van't Hoff relationship yielded values of 0.188+/-0.028, 0.212+/-0.042, 0.197+/-0.044, and 0.211+/-0.042 for control, glucose, trehalose and stachyose-injected oocytes, respectively. The present data revealing osmometric behavior of mouse oocytes in the presence of different intracellular sugars are important for the optimization of cryopreservation protocols using sugars.  相似文献   
1000.
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