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161.
Natacha E. Piloni Juan C. Perazzo Virginia Fernandez Luis A. Videla Susana Puntarulo 《Biometals》2016,29(1):119-130
This work was aimed to test the hypothesis that sub-chronic administration of iron-dextran (Fe-dextran) (six doses of 50 mg Fe-dextran/kg) to rats triggers a transient oxidative stress in brain and mechanisms of cellular antioxidant defence. After 2 h of administration of the 6th dose, a significant increase of total Fe, the labile Fe pool (LIP), the lipid radical (LR?)/α-tocopherol (α-T) content ratio were observed, as compared to values in control brain homogenates. The ascorbyl radical (A?)/ascorbate (AH?) content ratio and the oxidation rate of 2′,7′-dichlorodihidrofluorescein (DCFH-DA) were significantly higher in Fe-dextran treated rats, as compared to values in brain from control rats after 4 h treatment. An increase in both catalase (CAT) and superoxide dismutase (SOD) activity was observed at 8 and 1–2 h, respectively. No significant changes were detected in the nuclear factor-κB (NF-κB) levels in nuclear extracts from rat brains after 1–8 h of Fe-dextran administration. After 2 h of Fe administration Fe concentration in cortex, striatum and hippocampus was significantly increased as compared to the same areas from control animals. Both, CAT and SOD activities were significantly increased in cortex after Fe administration over control values, without changes in striatum and hippocampus. Taken as a whole, sub-chronic Fe administration enhances the steady state concentration of Fe in the brain LIP that favors the settlement of an initial oxidative stress condition, both at hydrophilic and lipophilic compartments, resulting in cellular protection evidenced by antioxidant enzyme upregulation. 相似文献
162.
163.
Milan Lana Teunissen van Manen Boris Jansen Francisco Cuesta Susana Len‐Ynez William Daniel Gosling 《Ecology and evolution》2019,9(16):9120-9128
It remains poorly understood how the composition of leaf wax n‐alkanes reflects the local environment. This knowledge gap inhibits the interpretation of plant responses to the environment at the community level and, by extension, inhibits the applicability of n‐alkane patterns as a proxy for past environments. Here, we studied the n‐alkane patterns of five Miconia species and one Guarea species, in the Ecuadorian Andes (653–3,507 m a.s.l.). We tested for species‐specific responses in the average chain length (ACL), the C31/(C31 + C29) ratio (ratio), and individual odd n‐alkane chain lengths across an altitudinally driven environmental gradient (mean annual temperature, mean annual relative air humidity, and mean annual precipitation). We found significant correlations between the environmental gradients and species‐specific ACL and ratio, but with varying magnitude and direction. We found that the n‐alkane patterns are species‐specific at the individual chain length level, which could explain the high variance in metrics like ACL and ratio. Although we find species‐specific sensitivity and responses in leaf n‐alkanes, we also find a general decrease in “shorter” (<C29) and an increase in “longer” (>C31) chain lengths with the environmental gradients, most strongly with temperature, suggesting n‐alkanes are useful for reconstructing past environments. 相似文献
164.
165.
Frago S Goñi G Herguedas B Peregrina JR Serrano A Perez-Dorado I Molina R Gómez-Moreno C Hermoso JA Martínez-Júlvez M Mayhew SG Medina M 《Archives of biochemistry and biophysics》2007,467(2):206-217
Contribution of three regions (phosphate-binding, 50’s and 90’s loops) of Anabaena apoflavodoxin to FMN binding and reduction potential was studied. Thr12 and Glu16 did not influence FMN redox properties, but Thr12 played a role in FMN binding. Replacement of Trp57 with Glu, Lys or Arg moderately shifted Eox/sq and Esq/hq and altered the energetic of the FMN redox states binding profile. Our data indicate that the side chain of position 57 does not modulate Eox/sq by aromatic stacking or solvent exclusion, but rather by influencing the relative strength of the H-bond between the N(5) of the flavin and the Asn58-Ile59 bond. A correlation was observed between the isoalloxazine increase in solvent accessibility and less negative Esq/hq. Moreover, Esq/hq became less negative as positively charged residues were added near to the isoalloxazine. Ile59 and Ile92 were simultaneously mutated to Ala or Glu. These mutations impaired FMN binding, while shifting Esq/hq to less negative values and Eox/sq to more negative. These effects are discussed on the bases of the X-ray structures of some of the Fld mutants, suggesting that in Anabaena Fld the structural control of both electron transfer steps is much more subtle than in other Flds. 相似文献
166.
Mario Pagano J. Dedrick Jordan Susana R. Neves Tracy Nguyen Ravi Iyengar 《Cellular signalling》2008,20(6):1190-1197
The Gs and Gi pathways interact to control the levels of intracellular cAMP. Although coincident signaling through Gs and Gi-coupled receptors can attenuate Gs-stimulated cAMP levels, it is not known if prior activation of the Gi pathway can affect signaling by Gs-coupled receptors. We have found that activated Gαo/i interact with RGS20, a GTPase activating protein for members of the Gαο/i family. Interaction between Gαo/i and RGS20 results in decreased cellular levels of RGS20. This decrease was induced by activated Gαo and Gαi2 but not by Gαq, Gαi1 or Gαi3. The Gαo/i-induced decrease in RGS20 can be blocked by proteasomal inhibitors lactacystin or MG132. Activated Gαo stimulates the ubiquitination of RGS20. The serotonin-1A receptor that couples to Go/i reduces the levels of RGS20 and this effect is blocked by lactacystin, suggesting that Go/i promotes the degradation of RGS20. Expression of RGS20 attenuates the inhibition of β-adrenergic receptor-induced cAMP levels mediated by the serotonin-1A receptor. Prior activation of the serotonin-1A receptor results in loss of the RGS20-mediated attenuation, and the loss of attenuation is blocked when lactacystin is included during the prior treatment. These observations suggest that Go/i-coupled receptors, by stimulating the degradation of RGS20, can regulate how subsequent activation of the Gs and Gi pathways controls cellular cAMP levels, thus allowing for signal integration. 相似文献
167.
Alicia M. Bray Leah S. Bauer Therese M. Poland Robert A. Haack Anthony I. Cognato James J. Smith 《Biological invasions》2011,13(12):2869-2887
Emerald ash borer (EAB), Agrilus planipennis Fairmaire (Coleoptera: Buprestidae), is an invasive pest of North American ash (Fraxinus spp.) trees first discovered outside of its native range of northeastern Asia in 2002. EAB spread from its initial zone of
discovery in the Detroit, Michigan and Windsor, Ontario metropolitan areas, in large part, from inadvertent human-assisted
movement of infested ash materials. EAB infestations are now known in 15 US states and two Canadian provinces. The primary
goal of this study was to use molecular markers to characterize the population genetic structure of EAB in its native and
introduced range. This information may provide valuable insights on the geographic origin, potential host range, invasion
potential, and additional biological control agents for ongoing management efforts of this destructive wood-boring beetle.
EAB were collected from 17 localities in its native Asian range and from 7 localities in North America, and population structure
analyzed using mtDNA gene sequences, AFLP fingerprints, and alleles at 2 microsatellite loci. Analysis of mtDNA cytochrome
oxidase subunit I gene (COI; 439 bp) sequences revealed all North American individuals carry a common mtDNA haplotype also
found in China and South Korea. Additional mtDNA haplotypes observed in China and South Korea differed from the common haplotype
by 1–2 nucleotide substitutions and a single individual from Japan differed by 21 nucleotide changes (4.8%). Analysis using
AFLP fingerprints (108 loci) indicated Asian populations were more highly variable, yet had less overall population structure,
than the North American populations. North American populations appear most closely related to populations in our sample from
the Chinese provinces of Hebei and Tianjin City. Further, population assignment tests assigned 88% of the individual beetles
from North America to either Hebei or Tianjin City. 相似文献
168.
169.
RAPD-PCR analysis of Staphylococcus aureus strains isolated from bovine and human hosts 总被引:3,自引:0,他引:3
Reinoso E Bettera S Frigerio C DiRenzo M Calzolari A Bogni C 《Microbiological research》2004,159(3):245-255
Staphylococcus aureus is one of the most important pathogens in humans and animals. In this study eighty strains were analyzed by RAPD-PCR to assess the genetic relationship between S. aureus isolates from bovine and human hosts. Results were compared with those obtained by biotyping. Fifty-two percent of the S. aureus isolates belonged to a host specific biotype (human, bovine and poultry). Bovine and human ecovars were the most prevalent. Dendrogram obtained by RAPD results showed that all the isolates clustered into eleven groups (A-K) at a relative genetic similarity of less than 30% when analyzed with the three primers. Group A clustered 95% of the human host isolates and the remaining groups (B-K) clustered the bovine host isolates. Principal coordinate analysis also showed that the isolates could be arbitrarily divided into two groups, bovine and human, by the second coordinate. Only 9 isolates (11%) were not clustered into these groups. The genetic diversity among the S. aureus isolates from bovine hosts is relatively low compared to that of isolates from human hosts. There were no statistically significant differences among isolated from bovine and human hosts. This study shows that RAPD-PCR assayed with three primers can be successfully applied to assess the genetic relationship of S. aureus isolates from different hosts. 相似文献
170.
Susana Freitas Anna Vavakou Marine Arakelyan Sergei V. Drovetski Jelka Crnobrnja-isailović Artem A. Kidov 《分类学与生物多样性》2013,11(2):184-197
Darevskia praticola differs from the other species of the genus in having a large but disjunct distribution, covering the Balkan and the Caucasus regions. Furthermore, most Darevskia species occupy saxicolous habitats, whereas D. praticola inhabits meadows and forest environments. Here we determine the phylogeographic and phylogenetic relationships of Darevskia praticola sensu lato and evaluate the current, morphology-based taxonomy. We sequenced two mtDNA genes (Cyt-b and ND4) and two nuclear loci (MC1R and RELN) for samples collected across the species range. Because our sequences amplified with the Cyt-b primers appear to represent a nuclear pseudogene we excluded this marker from the final analysis. Our results support monophyly of D. praticola and show its division into three clades. The first divergence, dated to the Late Pliocene, is between the Balkans and the Caucasus. The Caucasus lineage is further subdivided in a western Greater Caucasus and a Transcaucasia clade, likely due to subsequent differentiation during the Pleistocene. Our findings do not support the current taxonomic arrangement within D. praticola. The main geographic divergence likely happened due to a vicariance event associated with Plio-Pleistocene climatic and vegetation oscillations. 相似文献