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91.
Garcia-Mira MM Sadqi M Fischer N Sanchez-Ruiz JM Muñoz V 《Science (New York, N.Y.)》2002,298(5601):2191-2195
Theory predicts the existence of barrierless protein folding. Without barriers, folding should be noncooperative and the degree of native structure should be coupled to overall protein stability. We investigated the thermal unfolding of the peripheral subunit binding domain from Escherichia coli's 2-oxoglutarate dehydrogenase multienzyme complex (termed BBL) with a combination of spectroscopic techniques and calorimetry. Each technique probed a different feature of protein structure. BBL has a defined three-dimensional structure at low temperatures. However, each technique showed a distinct unfolding transition. Global analysis with a statistical mechanical model identified BBL as a downhill-folding protein. Because of BBL's biological function, we propose that downhill folders may be molecular rheostats, in which effects could be modulated by altering the distribution of an ensemble of structures. 相似文献
92.
We directly observed the hydration dynamics of an excess electron in the finite-sized water clusters of (H2O)n- with n = 15, 20, 25, 30, and 35. We initiated the solvent motion by exciting the hydrated electron in the cluster. By resolving the binding energy of the excess electron in real time with femtosecond resolution, we captured the ultrafast dynamics of the electron in the presolvated ("wet") and hydrated states and obtained, as a function of cluster size, the subsequent relaxation times. The solvation time (300 femtoseconds) after the internal conversion [140 femtoseconds for (H2O)35-] was similar to that of bulk water, indicating the dominant role of the local water structure in the dynamics of hydration. In contrast, the relaxation in other nuclear coordinates was on a much longer time scale (2 to 10 picoseconds) and depended critically on cluster size. 相似文献
93.
Edery P Marcaillou C Sahbatou M Labalme A Chastang J Touraine R Tubacher E Senni F Bober MB Nampoothiri S Jouk PS Steichen E Berland S Toutain A Wise CA Sanlaville D Rousseau F Clerget-Darpoux F Leutenegger AL 《Science (New York, N.Y.)》2011,332(6026):240-243
The spliceosome, a ribonucleoprotein complex that includes proteins and small nuclear RNAs (snRNAs), catalyzes RNA splicing through intron excision and exon ligation to produce mature messenger RNAs, which, in turn serve as templates for protein translation. We identified four point mutations in the U4atac snRNA component of the minor spliceosome in patients with brain and bone malformations and unexplained postnatal death [microcephalic osteodysplastic primordial dwarfism type 1 (MOPD 1) or Taybi-Linder syndrome (TALS); Mendelian Inheritance in Man ID no. 210710]. Expression of a subgroup of genes, possibly linked to the disease phenotype, and minor intron splicing were affected in cell lines derived from TALS patients. Our findings demonstrate a crucial role of the minor spliceosome component U4atac snRNA in early human development and postnatal survival. 相似文献
94.
Bao-Li Qiu Fang Dang Shao-Jian Li Muhammad Z. Ahmed Feng-Liang Jin Shun-Xiang Ren Andrew G. S. Cuthbertson 《Journal of pest science》2011,84(4):419-427
The sweetpotato whitefly, Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) is a widely distributed and destructive agricultural pest on various host plants. The
biology of two biotypes of B. tabaci: the invasive B and a new defined Cv biotype, on a range of host plants (hibiscus, laurel, poinsettia, collard, cucumber
and tomato) were studied in the laboratory. Results revealed that the developmental periods of the B biotype immatures were
not significantly different on the tested host plants except those between laurel and collard. The Cv biotype immatures developed
significantly slower on cucumber and tomato than on the other plants. B. tabaci B biotype had the highest survivorship on collard (68.55%), and the lowest on laurel (33.24%), while the Cv biotype had the
highest and lowest survivorships on laurel (61.63%) and tomato (36.74%). Host plants did not significantly affect the pre-ovipostion
period regardless of biotype. The longest averaged longevity and highest fecundity of B biotype were both recorded on collard:
25.15 days and 143.0 eggs. The highest fecundity of Cv biotype was 196.49 eggs on laurel and its longest longevity was on
hibiscus (19.62 days). The intrinsic rate of natural increase (r
m) of B biotype on the three vegetables were all higher than those on the three ornamentals whereas the r
m of Cv biotype on the three ornamentals were all higher that those on the three vegetables. Our research indicates that B. tabaci B and Cv biotypes have different host plant suitabilities. The three tested vegetables were more suitable for B biotype while
the three tested ornamental plants were more suitable for Cv biotype. The potential mechanism for the different suitability
of B and Cv biotypes on various host plants is also discussed. 相似文献
95.
In vitro maturation and fertilization of prepubertal and pubertal black Bengal goat oocytes 总被引:1,自引:0,他引:1
Momena Khatun Mohammad Musharraf Uddin Bhuiyan Jalal Uddin Ahmed Aminul Haque Mohammad Bozlur Rahman Mohammed Shamsuddin 《Journal of veterinary science (Suw?n-si, Korea)》2011,12(1):75-82
Oocytes retrieval, in vitro maturation (IVM) and fertilization (IVF) efficiency are inevitable steps towards in vitro production of embryos. In the present study, these parameters were investigated in the ovaries of prepubertal (n = 31) and pubertal (n = 61) black Bengal goats obtained from a slaughterhouse. Nuclear maturation was evaluated upon aspiration and following IVM in TCM-199 (Earle''s salt with L-glutamine and sodium bicarbonate) for 27 h at 39℃ under 5% CO2 in humidified air. The oocytes retrieval and efficiency (mean ± SD) per prepubertal and pubertal goats were 5.2 ± 0.6 and 6.8 ± 0.6, and 77.3 ± 0.1% and 80.5 ± 0.6%, respectively. Anaphase I - telophase I stages differed significantly (7.3 ± 0.8 vs. 2.6 ± 0.2, p < 0.05) between the two groups of goats. After IVM, the percentages of metaphase II were significantly higher (66.3 vs. 60.3, p < 0.05) in pubertal goats than in their prepubertal counterparts. The percentages of normal in vitro fertilization (IVF) in Fert-Tyrode''s albumin lactate pyruvate of pubertal goat oocytes did not differ between Percoll and swim-up sperm separation methods (36.7 ± 0.9% vs. 32.7 ± 1.3%, p > 0.05). Furthermore, sperm capacitation by heparin alone or in combination with ionomycin did not lead to a significant increase in the normal fertilization rate (34.8 ± 1.7 vs. 32.2 ± 1.5%, respectively) in the oocytes of pubertal goats. In conclusion, the ovaries of pubertal black Bengal goats obtained from the slaughterhouse could be used for in vitro embryo production. However, further optimization of the IVM and IVF techniques are necessary for satisfactory in vitro embryo production. 相似文献
96.
Smita JainRafat S. Ahmed Vinod Kumar AroraBasu Dev Banerjee 《Pesticide biochemistry and physiology》2011,100(2):182-186
Triazophos, O,O-diethyl-1-H-1,2,4-triazol-3-yl phosphorothioate, (TZ) is an organophosphorus pesticide which is extensively used in agriculture for controlling insect pests. Except a FAO/WHO report no study has investigated its short-term toxicity with respect to its potential to cause biochemical and histopathological alterations. The present study was designed to identify the effect of TZ at different doses (1.64, 3.2 and 8.2 mg/kg) on the oxidative stress parameters in blood as well as organs involved in xenobiotic metabolism (liver and brain) following chronic exposure for 90 days. Moreover, the study also delineates the effect of TZ on the histo-architecture of these organs. The results indicated a dose dependent induction (p < 0.001) of oxidative stress, as evident by increased malondialdehyde (MDA) level and compromised antioxidant defense including glutathione S transferase (GST) activity, glutathione (GSH) content and ferric reducing ability of plasma (FRAP) in blood, and increased MDA level with concomitantly decreased GSH content in tissues, following chronic exposure to TZ. The ratio of MDA: FRAP in blood was found to be increased following chronic exposure to TZ and may serve as a suitable indicator of severity of oxidative damage. Onset of such biochemical alterations is one of the early adaptive responses to TZ exposure which leads to histopathological alterations in terms of diffuse fatty changes expanding from mid-zonal area to whole lobule in liver. However, increased oxidative stress did not bring any morphological alteration in brain. The present study concludes that induction of oxidative stress, leading to subsequent histopathological alterations in liver, is an important mechanism underlying the TZ induced chronic toxicity. 相似文献
97.
A separation system has been developed to permit the simultaneous analysis of major anthocyanins and stilbenes from berries of Vitis species in <1 h. The system makes use of separation by HPLC and detection by UV-visible absorption and fluorescence, for anthocyanins and stilbenes, respectively, with the two detection systems linked in series. Monitoring the absorption at 520 nm permits ready identification and quantification of major anthocyanins. Chromatograms derived from fluorescence (330 nm excitation/374 nm emission) produce less clear data for the piceids and resveratrols, which are present in much lower amounts; peaks for these compounds can be verified by means of external or internal standards. 相似文献
98.
Ahmed A. M. Awad Atef A. A. Sweed 《Communications in Soil Science and Plant Analysis》2020,51(8):1101-1113
ABSTRACT The objective of this study was to study the influence of three organic manures, farm yard manure (FYM), poultry manure (PLM), and pigeon manure (PGM), on soil physical and chemical properties on tuber yield of Jerusalem artichoke in a newly reclaimed saline calcareous soil. A field experiment was conducted applying the three manures, alone and/or in different combinations. Soils were investigated at surface (0–30 cm) and subsurface (30–60 cm) layers before and after planting, and analyzed for physical and chemical properties. The results indicated that the application of 31.5 kg ha?1 of PLM+10.5 kg of PGM T7 recorded highest available nitrogen, zinc, copper, and moisture content at the surface layer. The same results were obtained for iron and manganese at both layers. While, applying 21.0 kg ha?1 FYM+21.0 kg ha?1 PLM T10 recorded the best treatment for pH, phosphorus, zinc, copper, moisture content, and saturation percentage at the subsurface layer. Applying 21.0 kg ha?1 PGM + 10.5 kg ha?1 FYM+10.5 kg ha?1 PLM T15 recorded the best treatment for organic matter content and bulk density at surface layer and reduced the electrical conductivity and inulin tuber content at both layers. On the other hand, calcium carbonate and sodium adsorption ratio were reduced in both layers by applying 21.0 kg ha?1 PLM+10.5 kg ha?1 FYM+10.5 kg ha?1 PGM T14. The best treatment for tuber nitrogen content and total yield was obtained with applying 42.0 kg ha?1 PLM T2 only and 31.5 kg ha?1 FYM+10.5 kg ha?1 PLM T4, respectively. 相似文献
99.
Yagoub Ael-G Mohamed BE Ahmed AH El Tinay AH 《Journal of agricultural and food chemistry》2004,52(20):6143-6150
Furundu, a meat substitute, is traditionally prepared by cooking the karkade (Hibiscus sabdariffa L.) seed and then fermenting it for 9 days. Physicochemical and functional properties of raw and cooked seed and of furundu ferments were analyzed. Furundu preparation resulted in significant changes in karkade seed major nutrients. Total polyphenols and phytic acid were also reduced. The increase in total acidity and fat acidity coupled with a decrease in pH indicates microbial hydrolysis of the major nutrients; proteins, carbohydrates, and fats. In vitro digestibility of the seed proteins reached the maximum value (82.7%) at the sixth day of fermentation, but thereafter it significantly decreased. The effect of furundu preparation on N solubility profiles and functional properties, such as emulsification and foaming properties and other related parameters, is investigated in water and in 1 M NaCl extracts from defatted flour samples. The results show that cooking followed by fermentation affects proteins solubility in water and 1 M NaCl. The foaming capacity (FC) from the flour of raw seed decreased as a result of cooking. Fermentation for 9 days significantly increased the FC of the cooked seed, restoring the inherent value. Foam from fermented samples collapsed more rapidly during a period of 120 min as compared to the foam from raw and cooked karkade seeds; stability in 1 M NaCl was lower as compared to those in water. In water, the emulsion stability (ES) from the fermented samples was significantly higher than that of the raw seed flour. Addition of 1 M NaCl significantly decreased the ES of the fermented samples. 相似文献
100.
A W Ahmed V N Mallet M J Bertrand 《Journal of the Association of Official Analytical Chemists》1989,72(2):365-367
Methods are described for the determination of acidic herbicides and related compounds in water and soil. Eight acidic herbicides and related compounds were extracted from water using either dichloromethane or an XAD-2 resin column. The acidic moieties were derivatized with 2-cyanoethyldimethyl(diethyl)aminosilane. The derivatized compounds were separated using capillary gas chromatography and quantitated using a nitrogen-phosphorus detector. Extraction from water using dichloromethane or an XAD-2 resin column resulted in recoveries greater than 90% at 0.1 ppb with an average coefficient of variation (CV) of 6%. In soils extracted with aqueous acetonitrile-acetic acid and partitioned into dichloromethane, recoveries at 500 ppb were greater than 75% with an average CV of 3.3%. The methods are rapid and there are few interferences. 相似文献