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91.
Conformational nonequivalence of chains 1 and 2 of dipalmitoyl phosphatidylcholine as observed by Raman spectroscopy. 总被引:2,自引:1,他引:1 下载免费PDF全文
Raman spectroscopic data indicate that the conformations of the two hydrocarbon chains of dipalmitoyl phosphatidylcholine in aqueous dispersions of the lipid differ signficantly. The compounds 1-palmitoyl, 2-palmitoyl-d31-3-sn-phosphatidylcholine and 1-palmitoyl-d31, 2-palmitoyl-3-sn-phosphatidylcholine were synthesized. Aqueous dispersions of these phospholipids display very similar phase behavior, with both premelting and melting transitions at nearly identical temperatures, midway between the comparable transition temperatures of undeuterated and completely deuterated dipalmitoyl phosphatidylcholine. We have monitored the state of chains 1 and 2 of these molecules simultaneously and independently by Raman spectroscopy. Raman difference spectra taken between samples of the two compounds under identical conditions show significant features. We attribute these spectral differences to nonequivalent conformations of the fatty acyl chains attached at positions 1 and 2 on the glycerol backbone. Below the pretransition the conformation of chain 2 is, on average, slightly less all-trans than is the chain at position 1. There is some evidence that the conformations of the terminal methyl group of the two chains are significantly different at low temperatures. 相似文献
92.
Internuclear Genetic Transfer in Vegetative Dikaryons of SCHIZOPHYLLUM COMMUNE: I. Di-Mon Mating Analysis 总被引:1,自引:1,他引:0 下载免费PDF全文
A series of hemi-compatible dikaryon x monokaryon (di-mon) matings was designed to determine whether there was any genetic interaction between the dikaryotic nuclei. One of the nuclei in each dikaryon was known to carry a recessive gene (mnd) that promoted the development of an abnormal growth form, mound. Dikaryons containing both mnd + and mnd nuclei produced mosaic colonies that consisted of three distinct kinds of hyphae: mound, fruiting body, and vegetative (devoid of any multihyphal structure). When dikaryotic hyphae from each of these morphological regions were used in di-mon matings, the genetic and developmental characteristics of the selected nuclear types were examined in the resulting derived dikaryons. The results showed that fruiting-body and vegetative cells contained the expected mnd and mnd+ nuclei. Dikaryotic mound hyphae, however, contained only mnd nuclei. In a manner as yet unresolved, but clearly dependent on the presence of the mnd allele, the mnd + allele of a wild nucleus was altered to, or acquired, the mnd allele. A number of hypotheses were considered to explain the genetic event(s) that generates [mnd + mnd*] dikaryotic cells from [mnd+ + mnd] cells, but none was found to be entirely satisfactory. 相似文献
93.
Gaber E. El-Desoky Samir A. Bashandy Ibrahim M. Alhazza Zeid A. Al-Othman Mourad A. M. Aboul-Soud Kareem Yusuf 《PloS one》2013,8(3)
The present study was undertaken to investigate the protective effect of the filamentous cyanobacterium Spirulina platensis (S. platensis) on mercury (II) chloride (HgCl2)-induced oxidative damages and histopathological alterations in the testis of Wistar albino rats. The animals were divided into four equal groups, i
) control, ii
) HgCl2, iii
) S. platensis and iv
) combination of HgCl2+S. platensis. Oxidative stress, induced by a single dose of HgCl2 (5 mg/kg, bw; subcutaneously, s.c.), substantially decreased (P<0.01) the activity level of testicular key enzymatic antioxidant biomarkers (superoxide dismutase, SOD; catalase, CAT and glutathione peroxidase, GPx), oxidative stress makers (blood hydroperoxide; testicular reduced glutathione, GSH and malondialdehyde, MDA), and testicular mercury levels. Moreover, HgCl2 administration resulted in a significant (P<0.01) increase in the number of sperms with abnormal morphology and decrease in epididymal sperm count, motility, plasma testosterone level and testicular cholesterol. Furthermore, HgCl2 exposure induced histopathological changes to the testis including morphological alterations of the seminiferous tubules, and degeneration and dissociation of spermatogenic cells. Notably, oral pretreatment of animals with Spirulina (300 mg/kg, bw) lowered the extent of the observed HgCl2-mediated toxicity, whereby significantly reducing the resulting lipid peroxidation products, mercury accumulation in the testis, histopathological changes of the testes and spermatozoal abnormalities. In parallel, the pretreatment with Spirulina also completely reverted the observed Hg-Cl2-induced inhibition in enzymatic activities of antioxidant biomarkers (SOD, CAT and GPx) back to control levels. The pretreatment of rats with S. platensis significantly recovered the observed HgCl2-mediated decrease in the weight of accessory sex organs. Taken together, our findings clearly highlight the role of S. platensis as a protective modulator of HgCl2-induced testicular injuries and suggest some therapeutic potential in mammals. Further investigation of therapeutic strategies employing Spirulina against heavy metals toxicity in humans is therefore warranted. 相似文献
94.
Protoplasma - Overexpressing OsPIP2;4 in the two rice cultivars Giza178 and IR64 resulted in contrasting cultivar-dependent physiological attributes under control and drought conditions in the... 相似文献
95.
96.
Green alga Zygnema was exposed to three concentrations of selenium and two levels of UV-B radiation. The combined effects of both treatments
on energy availability; photochemical quantum yield and respiratory potential were studied. Our findings show that traces
of selenium enhance metabolic process connected with photochemical quantum yield and mitochondrial respiration. Surprisingly,
selenium does not diminish the effects of UV-B radiation; on the contrary, the combined action of UV-B radiation and traces
of selenium leads to pronounced negative effects on photochemical quantum yield and the respiratory potential. Selenium is
involved in the activation of energy resources in green alga Zygnema. The importance of selenium for activity of the mitochondria is possibly an evolutionary recollection from an endosymbiotic
bacterium. 相似文献
97.
Sonja Gaber Eva Elisa Fischerauer Eleonore Fröhlich Gregor Janezic Florian Amerstorfer Annelie-Martina Weinberg 《Cell and tissue research》2009,335(3):539-549
Post-traumatic overgrowth of growing long bones is a common clinical phenomenon in paediatric traumatology and is the result
of an enhanced stimulation of the nearby growth plate after fracture. To date, the exact post-fractural reactions of the growth
plate are poorly understood. The aim of this study has been to determine the impact of fracture on the frequency of chondrocyte
apoptosis of the growth plate. Rats sustained a mid-diaphyseal closed fracture of the left tibia or were left untreated. All
animals were killed 3, 10, 14 or 29 days after trauma. The left and right tibiae were harvested and apoptotic chondrocytes
of the proximal tibial growth plate were detected by TUNEL staining. The apoptosis percentage of physeal chondrocytes was
statistically compared among fractured bones, intact contra-lateral bones and control bones. The physeal apoptosis rate of
the fractured bone was significantly higher than that of the contra-lateral intact bone (valid for all evaluated days) and
the control bone (valid from day 10 onwards). Contra-lateral intact tibiae never showed significantly higher apoptosis rates
compared with control tibiae. Thus, mid-diaphyseal fracture influences the nearby growth plate by stimulating chondrocyte
programmed cell death, which is associated with cartilage resorption and bone replacement. The lack of a significant difference
between the intact contra-lateral and the intact control bone suggests that fracture only has a local effect that contributes
to the greater apoptosis rate of the adjacent physis. 相似文献
98.
Wu B Ottow K Poulsen P Gaber RF Albers E Kielland-Brandt MC 《The Journal of cell biology》2006,173(3):327-331
Recent studies of Saccharomyces cerevisiae revealed sensors that detect extracellular amino acids (Ssy1p) or glucose (Snf3p and Rgt2p) and are evolutionarily related to the transporters of these nutrients. An intriguing question is whether the evolutionary transformation of transporters into nontransporting sensors reflects a homeostatic capability of transporter-like sensors that could not be easily attained by other types of sensors. We previously found SSY1 mutants with an increased basal level of signaling and increased apparent affinity to sensed extracellular amino acids. On this basis, we propose and test a general model for transporter- like sensors in which occupation of a single, central ligand binding site increases the activation energy needed for the conformational shift between an outward-facing, signaling conformation and an inward-facing, nonsignaling conformation. As predicted, intracellular leucine accumulation competitively inhibits sensing of extracellular amino acids. Thus, a single sensor allows the cell to respond to changes in nutrient availability through detection of the relative concentrations of intra- and extracellular ligand. 相似文献
99.
Antioxidative defense under salt stress 总被引:1,自引:0,他引:1
Gaber M Abogadallah 《Plant signaling & behavior》2010,5(4):369-374
Salt tolerance is a complex trait involving the coordinated action of many gene families that perform a variety of functions such as control of water loss through stomata, ion sequestration, metabolic adjustment, osmotic adjustment and antioxidative defense. In spite of the large number of publications on the role of antioxidative defense under salt stress, the relative importance of this process to overall plant salt tolerance is still a matter of controversy. In this article, the generation and scavenging of reactive oxygen species (ROS) under normal and salt stress conditions in relation to the type of photosynthesis is discussed. The CO2 concentrating mechanism in C4 and CAM plants is expected to contribute to decreasing ROS generation. However, the available data supports this hypothesis in CAM but not in C4 plants. We discuss the specific roles of enzymatic and non enzymatic antioxidants in relation to the oxidative load in the context of whole plant salt tolerance. The possible preventive antioxidative mechanisms are also discussed.Key words: salt stress, generation of ROS, type of photosynthesis, scavenging of ROS, preventive antioxidative defense 相似文献
100.
Forensic science uses scientific methods to help the scientists who study evidence to assist in the solving of crimes. Coleoptera is the most diverse and speciose group of insects that have an important role in many scientific fields especially forensic entomology. In addition, it is difficult to morphologically identify and discriminate between them. In the present study, the molecular analysis using mitochondrial DNA information was conducted to swiftly and accurately identify the recovered Coleoptera species. A molecular identification method involving a 221‐bp segment of the 16 s ribosomal RNA (16 s rRNA) gene from three beetle species, collected from a rabbit carcass, was evaluated. The analysis with maximum likelihood method recovered a generally well supported phylogeny, with most currently accepted taxa and species groups as monophyletic. These results will be instrumental for the implementation of the Saudian database of forensically relevant beetles. 相似文献