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11.
12.
Emily HM Wong David K Smith Raul Rabadan Malik Peiris Leo LM Poon 《BMC evolutionary biology》2010,10(1):253
Background
The influenza A virus is an important infectious cause of morbidity and mortality in humans and was responsible for 3 pandemics in the 20th century. As the replication of the influenza virus is based on its host's machinery, codon usage of its viral genes might be subject to host selection pressures, especially after interspecies transmission. A better understanding of viral evolution and host adaptive responses might help control this disease. 相似文献13.
Rebecca C Mueller Fabiana S Paula Babur S Mirza Jorge LM Rodrigues Klaus Nüsslein Brendan JM Bohannan 《The ISME journal》2014,8(7):1548-1550
Understanding the interactions among microbial communities, plant communities and soil properties following deforestation could provide insights into the long-term effects of land-use change on ecosystem functions, and may help identify approaches that promote the recovery of degraded sites. We combined high-throughput sequencing of fungal rDNA and molecular barcoding of plant roots to estimate fungal and plant community composition in soil sampled across a chronosequence of deforestation. We found significant effects of land-use change on fungal community composition, which was more closely correlated to plant community composition than to changes in soil properties or geographic distance, providing evidence for strong links between above- and below-ground communities in tropical forests. 相似文献
14.
Carmen García Luis M. Montuenga J. F. Medina Jesús Prieto 《Cell and tissue research》1998,291(3):481-488
Na+-independent anion exchangers, a family of membrane proteins that mediate electroneutral exchanges of chloride and bicarbonate ions across the cell membrane, are considered to be involved in intracellular pH regulation as well as in transepithelial acid/base transport. Previous immunohistochemical data have shown that anion-exchanger-2 (AE2) protein is expressed in the liver parenchyma, localizing at both the canaliculi and the luminal surfaces of intrahepatic bile ducts, where it may have a role in the biliary secretion of bicarbonate. In the present study, we have carried out in situ hybridization experiments on biopsies of human liver using three overlapping antisense anion-exchanger-2 riboprobes. Anion-exchanger-2 mRNA signals were localized mainly in the cytoplasm of terminal and interlobular bile-duct cells, whereas weaker signals were observed in bile-duct cells of larger intrahepatic ducts. Furthermore, some hepatocytes, mostly periportal, contained detectable anion-exchanger-2 mRNA signals in their cytoplasm. No hybridization signals were observed in controls with sense riboprobes, with omission of the antisense probe, or with treatment of the sections with RNase before hybridizations. Finally, intense anion-exchanger-2 hybridization signals were observed in lymphomononuclear cells in sinusoids and in portal infiltrates. Immunocytochemical data from reverse-phase sections suggest that these cells correspond to some of the CD45R+ (UCHL1+) T lymphocytes resident in the liver. 相似文献
15.
Simultaneous immunostaining method for localization of bromodeoxyuridine and calcitonin gene-related peptide. 总被引:1,自引:0,他引:1
L M Montuenga D R Springall J Gaer J T McBride J M Polak 《The journal of histochemistry and cytochemistry》1992,40(8):1121-1128
A new simultaneous double immunostaining method has been optimized to localize the DNA synthesis marker bromodeoxyuridine (BrdU) and calcitonin gene-related peptide (CGRP) in endocrine cells of Bouin's-fixed, paraffin-embedded rat lung. Nuclease pre-treatment before immunostaining is compatible with optimal tissue morphology and CGRP antigenicity preservation. Nickel-enhanced development of avidin-biotin-peroxidase staining is used to show CGRP immunoreactivity in black and alkaline phosphatase-anti-alkaline phosphatase is applied to demonstrate incorporated BrdU in red. The present methodology could be useful for studies requiring detection of incorporated BrdU in cells producing regulatory peptides or other labile antigens. 相似文献
16.
Three satellite DNA families were identified in three species of burying
beetles, Nicrophorus orbicollis, N. marginatus, and N. americanus. Southern
hybridization and nucleotide sequence analysis of individual randomly
cloned repeats shows that these satellite DNA families are highly abundant
in the genome, are composed of unique repeats, and are species-specific.
The repeats do not have identifiable core elements or substructures that
are similar in all three families, and most interspecific sequence
similarity is confined to homopolymeric runs of A and T. Satellite DNA from
N. marginatus and N. americanus show single-base-pair indels among repeats,
but single-nucleotide substitutions characterize most of the repeat
variability. Although the repeat units are of similar lengths (342, 350,
and 354 bp) and A + T composition (65%, 71%, and 71%, respectively), the
average nucleotide divergence among sequenced repeats is very low (0.18%,
1.22%, and 0.71%, respectively). Transition/transversion ratios from the
consensus sequence are 0.20, 0.69, and 0.70, respectively.
相似文献
17.
Membrane resistance change of the frog taste cells in response to water and Nacl 总被引:2,自引:0,他引:2
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The electrical properties of the frog taste cells during gustatory stimulations with distilled water and varying concentrations of NaCl were studied with intracellular microelectrodes. Under the Ringer adaptation of the tongue, two types of taste cells were distinguished by the gustatory stimuli. One type, termed NaCl-sensitive (NS) cells, responded to water with hyperpolarizations and responded to concentrated NaCl with depolarizations. In contrast, the other type of cells, termed water-sensitive (WS) cells, responded to water depolarizations and responded to concentrated NaCl with hyperpolarizations. The membrane resistance of both taste cell types increased during the hyperpolarizing receptor potentials and decreased during the depolarizing receptor potentials, Reversal potentials for the depolarizing and hyperpolarizing responses in each cell type were a few millivolts positive above the zero membrane potential. When the tongue was adapted with Na-free Ringer solution for 30 min, the amplitude of the depolarizing responses in the NS cells reduced to 50% of the control value under normal Ringer adaptation. On the basis of the present results, it is concluded (a) that the depolarizing responses of the NS and WS cells under the Ringer adaptation are produced by the permeability increase in some ions, mainly Na+ ions across the taste cell membranes, and (b) that the hyperpolarizing responses of both types of taste cells are produced by a decrease in the cell membrane permeability to some ions, probably Na+ ions, which is slightly enhanced during the Ringer adaptation. 相似文献
18.
Molecular evidence for the rapid propagation of mouse t haplotypes from a single, recent, ancestral chromosome 总被引:11,自引:0,他引:11
Silver LM; Hammer M; Fox H; Garrels J; Bucan M; Herrmann B; Frischauf AM; Lehrach H; Winking H; Figueroa F 《Molecular biology and evolution》1987,4(5):473-482
Mouse t haplotypes are variant forms of chromosome 17 that exist at high
frequencies in worldwide populations of two species of commensal mice. To
determine both the relationship of t haplotypes to each other and the
species within which they exist, 35 representative t haplotypes were
analyzed by means of 10 independent molecular probes, including five DNA
clones and five polypeptide spots identified by means of two- dimensional
gel electrophoresis. All of the tested haplotypes were found to share
restriction fragments and polypeptide spots that are absent in mice
carrying wild-type forms of chromosome 17. This observation provides the
first direct evidence that all of the known t haplotypes are descendents of
a single ancestral chromosome. The absence of variation among t haplotypes
could mean that this ancestral chromosome existed relatively recently, in
which case it would be necessary to postulate introgressions of t
haplotypes across species lines to explain their presence in both Mus
domesticus and M. musculus. Alternatively, it is possible that the
ancestral chromosome existed prior to the split between M. domesticus and
M. musculus and that, by chance, our probes fail to detect polymorphisms
that exist among the t haplotypes. A further result of our analysis is the
characterization of a partial t haplotype in a wild population of Israeli
mice.
相似文献
19.
20.
Abasolo I Wang Z Montuenga LM Calvo A 《Biochemical and biophysical research communications》2004,322(3):878-886
Adrenomedullin (AM) is a multifunctional peptide expressed in the normal and malignant prostate, and in prostate cancer cells. To elucidate the potential role of AM in prostate cancer, we have transfected the human AM gene into PC-3, DU 145, and LNCaP prostate cancer cells. Northern blot, Western blot, and radioimmunoassay techniques confirmed an increase in the synthesis and secretion of the 6kDa mature peptide, in the AM-transfected clones. Proliferation and cell cycle assays demonstrated that AM overexpression inhibited cell proliferation in PC-3 and LNCaP cells through a G0/G1 cell cycle arrest, but not in DU 145 cells. In vivo growth assays also confirmed that, at least in PC-3, AM produced a very significant reduction of tumor volume. In addition, the three cell lines expressed the CL/RCP/RAMP-2 receptor complex by RT-PCR, which suggests that AM peptide acts through an autocrine loop in prostate cancer cells. Although cAMP elevation is the most common pathway involved in AM signalling, stimulation of PC-3, DU 145, and LNCaP with synthetic AM did not increase intracellular cAMP. However, short-term stimulation of PC-3 cells with synthetic AM increased ERK1/2 activation. On the contrary, long-term stimulation, or AM overexpression, caused a reduction in the basal activation of ERK1/2. In summary, our results demonstrate that AM (either overexpressed or exogenously added) causes an inhibition of prostate cancer cell growth. This inhibition does not depend on changes in intracellular cAMP levels, but may be related to ERK1/2 activation. 相似文献