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The evolutionary origin of the pinnipeds (seals, sea lions, and walruses)
is still uncertain. Most authors support a hypothesis of a monophyletic
origin of the pinnipeds from a caniform carnivore. A minority view suggests
a diphyletic origin with true seals being related to the mustelids (otters
and ferrets). The phylogenetic relationships of the walrus to other
pinniped and carnivore families are also still particularly problematic.
Here we examined the relative support for mono- and diphyletic hypotheses
using DNA sequence data from the mitochondrial small subunit (12S) rRNA and
cytochrome b genes. We first analyzed a small group of taxa representing
the three pinniped families (Phocidae, Otariidae, and Odobenidae) and
caniform carnivore families thought to be related to them. We inferred
phylogenetic reconstructions from DNA sequence data using standard
parsimony and neighbor-joining algorithms for phylogenetic inference as
well as a new method called spectral analysis (Hendy and Penny) in which
phylogenetic information is displayed independently of any selected tree.
We identified and compensated for potential sources of error known to lead
to selection of incorrect phylogenetic trees. These include sampling error,
unequal evolutionary rates on lineages, unequal nucleotide composition
among lineages, unequal rates of change at different sites, and
inappropriate tree selection criteria. To correct for these errors, we
performed additional transformations of the observed substitution patterns
in the sequence data, applied more stringent structural constraints to the
analyses, and included several additional taxa to help resolve long,
unbranched lineages in the tree. We find that there is strong support for a
monophyletic origin of the pinnipeds from within the caniform carnivores,
close to the bear/raccoon/panda radiation. Evidence for a diphyletic origin
was very weak and can be partially attributed to unequal nucleotide
compositions among the taxa analyzed. Subsequently, there is slightly more
evidence for grouping the walrus with the eared seals versus the true
seals. A more conservative interpretation, however, is that the walrus is
an early, but not the first, independent divergence from the common
pinniped ancestor.
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Stuart A Suttie Alan GK Li Martha Quinn Kenneth GM Park 《World journal of surgical oncology》2007,5(1):1-9
Background
Caveolin-1 is thought to have an important impact on both signal transduction and mediation of intracellular processes. Furthermore, it has been suggested that Caveolin-1 may contribute to certain steps of carcinogenesis in various types of cancer. We examined the potential clinical relevance of Caveolin-1 in normal, benign and malignant breast tissue specimens.Methods
Using tissue microarray (TMA) technology cases of invasive breast cancer, DCIS, benign breast disease (i.e. fibroadenoma, sclerosing adenosis, ductal hyperplasia and radial scar) and normal breast tissue were evaluated for Caveolin-1 expression. Immunohistochemical staining with an anti-Caveolin-1-antibody was performed. Staining intensity was quantified semiquantitatively. In invasive lesions staining results were correlated with clinical and pathological data.Results
No Caveolin-1 expression was observed in epithelial cells of normal breast tissue (n = 5), benign breast disease (n = 295) and DCIS (n = 108). However, Caveolin-1 expression was found in 32 of 109 cases of invasive breast carcinomas (29.4%). Caveolin-1 expression in invasive breast cancer could neither be correlated with survival parameters such as overall or disease-free survival nor with established clinical and pathological markers.Conclusion
In this study we demonstrated expression of Caveolin-1 in one third of invasive breast cancers. A significant increase in Caveolin-1 expression was observed comparing invasive breast cancer to both benign breast tissue and non-invasive breast cancer. Since inhibitors of Caveolin-1 signalling are available, targeting Caveolin-1 in breast cancer may represent a potential option for future breast cancer treatment. 相似文献6.
Girish R. Bankar Gopalan Kutty Nampurath Pawan G. Nayak Shoumyo Bhattacharya 《Chemico-biological interactions》2010,183(2):327-331
We have previously demonstrated the vasorelaxant activity of 1,3,4-oxadiazole derivative (NOX-1) through L-type Ca2+ channel blockage. In the present study, we investigated whether the correction of endothelial dysfunction is dependent on the normalization of high blood pressure levels by 1,3,4-oxadiazole derivative (NOX-1) in deoxycorticosterone acetate (DOCA-salt) and NG-nitro-l-arginine (L-NNA) hypertensive rats. In DOCA-salt and L-NNA hypertensive rats, the mean systolic blood pressure (MSBB) was 185.3 ± 4.7 and 170.2 ± 4.1 mmHg, whereas after administration of NOX-1 to hypertensive rats, MSBB was 127.8 ± 4.5 and 120.2 ± 5.1 mmHg, respectively. To study the endothelial dysfunction, concentration–response curves of norepinephrine (NE) and acetylcholine (Ach) were constructed in rat aortic rings isolated from normotensive, hypertensive (DOCA and L-NNA) and NOX-1 treated rats. NE-induced contractions and Ach-induced relaxations were significantly (p < 0.05) decreased and increased, respectively in the aorta of NOX-1 treated rats. Vasorelaxant activity of NOX-1 was not abolished by pretreatment of aortic rings with L-NNA, 1H-[1,2,4] oxadiazolo [4,3-A] quinoxalin-1-one (ODQ), indomethacin or glibenclamide. The results suggest that the endothelial dysfunction can be corrected by the L-type Ca2+ channel blocker with endothelium-independent action and that is dependent on the normalization of high blood pressure levels. The antihypertensive and vasorelaxant effects of NOX-1 are mainly endothelial-independent and it can be used to treat hypertension, a state associated with endothelial dysfunction. 相似文献
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Assessment of hypolipidaemic activity of three thiazolidin-4-ones in mice given high-fat diet and fructose 总被引:1,自引:0,他引:1
Nampurath GK Mathew SP Khanna V Zachariah RT Kanji S Chamallamudi MR 《Chemico-biological interactions》2008,171(3):363-368
Three 4-thiazolidinones, two with nicotinamide (NAT1 and NAT2) and one with 4-chlorophenoxyacetamide (PAT1) side chains were evaluated for their hypolipidaemic, hypoglycaemic activity in Swiss albino mice fed a high-fat diet along with fructose administered in drinking water. NAT1 and PAT caused reduction of elevated triglycerides, cholesterol and glucose; NAT2 was effective only against triglycerides. Nicotinamide side chain might have contributed to the lipid lowering effect of both NAT1 and NAT2, but the bulky group of the latter could have affected proper binding to the receptor sites, making it ineffective against elevated cholesterol. On the other hand, the 4-chlorophenoxyacetamide side chain of PAT might have exerted powerful hypolipidaemic activity, despite the bulky substitution at C2. As antioxidants, NAT2 and PAT1 showed superior activity, compared to NAT1. The thiazolidinone ring might be responsible for the lipid lowering effect, which is however, modified by the type of substitutions at C2 and N of the ring. Detailed study is warranted to explain the mechanism of action of these compounds as also to make more potent ones. 相似文献
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NaCl-preferring NZB/B1NJ mice and NaCl-avoiding CBA/J mice have similar amiloride inhibition of chorda tympani responses to NaCl 总被引:1,自引:1,他引:0
Integrated chorda tympani nerve responses to NaCl were studied in two mouse
strains, an NaCl-preferring NZB/B1NJ and an NaCl-avoiding CBA/J. The NaCl
responses of both strains had similar magnitude and were suppressed by
amiloride to a similar extent. This suggests that peripheral gustatory
responsiveness to NaCl is not the only mechanism underlying mouse strain
variation in NaCl acceptance.
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The secondary intracellular target of human neutrophil peptide-1 has been examined in M. tuberculosis H37Ra. Binding studies with radioiodinated HNP-1 revealed biphasic equilibrium binding kinetics with respect to time. The major
site of HNP-1 binding was found to be plasma membrane/cell wall whereas the cytosol appears to be a secondary site. Among
the different macromolecules examined, maximum inhibition (75%) was observed in DNA biosynthesis during treatment with HNP-1.
The interaction of HNP-1 with mycobacterial genomic DNA on the basis of gel retardation assay revealed HNP-1 binding to DNA.
These results indicate that HNP-1 has DNA as the secondary intracellular target for antibacterial action against mycobacteria.
Received: 25 October 2000/Accepted: 10 January 2001 相似文献
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To evaluate breastfed infants' responses to scented objects, we videotaped
the facial and bodily reactions of sixty-three infants as they explored, in
succession, three toys that were identical in appearance but different in
their characteristic odor. Two of the toys were scented with odorants
previously shown to be transmitted to human milk, one with ethanol and the
other with vanilla, whereas the third toy was unscented. Each videotape was
subjected to frame-by-frame analysis to measure a variety of behaviors that
are considered either to be exploratory in nature in that they lead to
perceptual information about the object or to reflect the infants' hedonic
reaction. Analyses of these behaviors revealed that the infants looked more
and vocalized less in the presence of the vanilla-scented toy and spent
less time manipulating the ethanol-scented toy when compared with the
unscented toy. Moreover, differential exposure to the odors of ethanol and
vanilla, as indicated by differential consumption of alcohol by a parent or
use of vanilla-scented product by the mother, was related to differential
responses to these odors. These findings suggest that human infants are
able to detect and retain information about the chemical features of their
environment.
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