Evidence of hybridity in invasive watermilfoil (Myriophyllum) populations. (1/29)

Invasions of nonindigenous species have caused ecological devastation to natural communities worldwide, yet the biological bases for invasiveness remain poorly understood. Our studies of invasive watermilfoil (Myriophyllum) populations revealed widespread polymorphisms in biparentally inherited nuclear ribosomal DNA sequences, which were not detected in populations of native North American species. Subclones of the polymorphic regions revealed the occurrence of distinct sequences matching those acquired from both nonindigenous and native North American species. Molecular data demonstrate clearly that invasive watermilfoil populations in North America have resulted from hybridization between nonindigenous and native species. These observations suggest that invasiveness in these aggressive aquatic weeds may be linked to heterosis maintained by vegetative propagation.  (+info)

Anti-inflammatory effects of aqueous extract from Dichroa febrifuga root in rat liver. (2/29)

AIM: To study the anti-inflammatory effects of aqueous extract from Dichroa febrifuga root (AEDF) for suppression in the process of lipopolysaccharide (LPS)-induced sepsis in the rat liver. METHODS: The inhibitory effect of AEDF on the alteration of inflammatory proteins was investigated by Western blot and immunohistochemical analysis. RESULTS: Western blot analysis showed that the level of nuclear factor (NF)-kappaBp65 was markedly up-regulated and (I)-kappaBalpha was down-regulated by LPS (8 mg/kg) challenge. However, AEDF 100 mg/kg inhibited induction of NF-kappaBp65 and degradation of I-kappaBalpha in the liver of LPS-challenged rats. Immunohistochemical analysis showed that while the expression of the NF-kappaBp65, tumor necrosis factor (TNF)-alpha and inducible nitric oxide synthase (iNOS) tended to increase, that of I-kappaBalpha was decreased in the hepatocytes of rats challenged with LPS. A slight decline of NF-kappaBp65, TNF-alpha and iNOS, but an increase of I-kappaBalpha were observed in the hepatocytes of the rats pretreated with AEDF. CONCLUSION: AEDF may act as a therapeutic agent for inflammatory disease through a regulation of inflammation-related proteins.  (+info)

Astilbic acid induced COLO 205 cell apoptosis by regulating Bcl-2 and Bax expression and activating caspase-3. (3/29)

AIM: To investigate the effect of astilbic acid (3beta, 6beta-dihydroxyolean-12-en-27-oic acid, AA) on human colorectal carcinoma COLO 205 cell proliferation and apoptosis. METHODS: Proliferation of COLO 205 cells was measured by MTT assay. Content of DNA in COLO 205 cell was measured by modified diphenylamine assay. AA-induced morphological changes was observed with fluorescence microscope and transmission electron microscope. DNA fragmentation was visualized by agarose gel electrophoresis. Apoptosis rate and cell cycle distribution were determined by flow cytometric analysis. Expressions of Bcl-2 and Bax proteins were visioned by immunohistochemical analysis. The change of relative mitochondrial transmembrane potential (MTP) in COLO 205 cell was analyzed with FCM after rhodamine 123 staining. RESULTS: The IC50 (96 h) of AA for inhibiting COLO 205 cell proliferation was 61.56+/-0.34 micromol/L. AA induced a marked concentration- and time-dependent inhibition of COLO 205 cell proliferation and reduced the DNA content in COLO 205 cell. Cells treated with AA 64 micromol/L showed typical morphological changes of apoptosis and DNA ladder pattern. The cell cycle was arrested in G0/G1 phase, and the apoptosis rate was 28.25 % for COLO 205 cells treated with AA 64 micromol/L for 48 h. Meanwhile the expression of Bcl-2 protein was decreased while that of Bax was increased and relative MTP was decreased as well. DEVD-CHO 1 micromol/L could increase the viability of COLO 205 cells treated with AA for 48 h. CONCLUSION: AA showed potent inhibitory activity on COLO 205 cells proliferation, and could induce COLO 205 cells apoptosis through disturbing DNA replication, down-regulating Bcl-2 expression, and up-regulating Bax expression, lowering relative MTP, and activating caspase-3 pathway.  (+info)

Effect of Astilbe koreana on ultraviolet B (UVB)-induced inflammatory response in human keratinocytes. (4/29)

The EtOH extract from the rhizomes of Astilbe koreana (Saxifragaceae) exhibited potent antioxidant activity in our recent study. Since the oxidative stress is known to be involved in the inflammatory response after ultraviolet B (UVB) exposure, the ability of the A. koreana extract to inhibit UVB-induced prostaglandin E2 (PGE2) and nitric oxide (NO) production was examined. UVB irradiation (35 mJ/cm2) increased PGE2 and NO production, which were significantly decreased by pre-administration of the A. koreana extract in a dose-dependent manner. The A. koreana extract also preserved cellular antioxidant capacity after UVB irradiation, which was determined by glutathione (GSH) content. UVB irradiation enhanced the formation of ROS in the keratinocytes, which was determined using a 2,7'-dichlorofluorescein diacetate (DCFH-DA), a redox sensitive dye. The levels of intracellular reactive oxygen species (ROS) were also significantly reduced by pre-treatment of the A. koreana extract in a dose-dependent manner measured 9 h after UVB irradiation. The results suggest that the A. koreana extract may have a protective effect on the UVB-injured keratinocytes by inhibiting PGE2 and NO production, possibly through the inhibition of intracellular ROS accumulation.  (+info)

Nonuniform concerted evolution and chloroplast capture: heterogeneity of observed introgression patterns in three molecular data partition phylogenies of Asian Mitella (saxifragaceae). (5/29)

Interspecific hybridization is one of the major factors leading to phylogenetic incongruence among loci, but the knowledge is still limited about the potential of each locus to introgress between species. By directly sequencing three DNA regions: chloroplast DNAs (matK gene and trnL-F noncoding region), the nuclear ribosomal external transcribed spacer (ETS) region, and internal transcribed spacer (ITS) regions, we construct three phylogenetic trees of Asian species of Mitella (Saxifragaceae), a genus of perennials in which natural hybrids are commonly observed. Within this genus, there is a significant topological conflict between chloroplast and nuclear phylogenies and also between the ETS and the ITS, which can be attributed to frequent hybridization within the lineage. Chloroplast DNAs show the most extensive introgression pattern, ITS regions show a moderate pattern, and the ETS region shows no evidence of introgression. Nonuniform concerted evolution best explains the difference in the introgression patterns between the ETS region and ITS regions, as the sequence heterogeneity of the ITS region within an individual genome is estimated to be twice that of an ETS in this lineage. Significant gene conversion patterns between two hybridizing taxa were observed in contiguous arrays of cloned ETS-ITS sequences, further confirming that only ITS regions have introgressed bidirectionally. The relatively slow concerted evolution in the ITS regions probably allows the coexistence of multiple alleles within a genome, whereas the strong concerted evolution in the ETS region rapidly eliminates heterogeneous alleles derived from other species, resulting in species delimitations highly concordant with those based on morphology. This finding indicates that the use of multiple molecular tools has the potential to reveal detailed organismal evolution processes involving interspecific hybridization, as an individual locus varies greatly in its potential to introgress between species.  (+info)

Molecular characterization and functional expression of flavonol 6-hydroxylase. (6/29)

BACKGROUND: Flavonoids, one of the major groups of secondary metabolites, play important roles in the physiology, ecology and defence of plants. Their wide range of activities is the result of their structural diversity that encompasses a variety of functional group substitutions including hydroxylations. The aromatic hydroxylation at position 6 of flavonols is of particular interest, since it is catalyzed by a 2-oxoglutarate-dependent dioxygenase (ODD), rather than a cytochrome P450-dependent monooxygenase. ODDs catalyze a variety of enzymatic reactions implicated in secondary metabolite biosynthesis. RESULTS: A cDNA fragment encoding an ODD involved in the 6-hydroxylation of partially methylated flavonols, flavonol 6-hydroxylase (F6H), was isolated and characterized from Chrysosplenium americanum using internal peptide sequence information obtained from the native plant protein. This novel clone was functionally expressed in both prokaryotic and eukaryotic expression systems and exhibited ODD activity. The cofactor and cosubstrate requirements of the recombinant proteins are typical for ODDs, and the recombinant enzymes utilize 3,7,4'-trimethylquercetin as the preferred substrate. The genomic region encoding this enzyme possesses two introns at conserved locations for this class of enzymes and is present as a single copy in the C. americanum genome. CONCLUSIONS: Recombinant F6H has been functionally expressed and characterized at the molecular level. The results demonstrate that its cofactor dependence, physicochemical characteristics and substrate preference compare well with the native enzyme. The N-terminal region of this protein is believed to play a significant role in catalysis and may explain the difference in the position specificity of the 6-hydroxylation reaction.  (+info)

Two new neolignans from the aerial parts of Rodgersia podophylla. (7/29)

Two new neolignans (1, 2) were isolated from the aerial parts of Rodgersia podophylla, along with four known neolignans, and their structures were elucidated using spectral experiments and comparison with literature data.  (+info)

Chloroplast DNA phylogeography of the arctic-montane species Saxifraga hirculus (Saxifragaceae). (8/29)

The genetic structure of populations of an arctic-montane herb, Saxifraga hirculus (Saxifragaceae), was analysed by means of chloroplast restriction fragment-length polymorphism. Sampled populations were distributed across Europe and North America (Alaska and Colorado). There was no evidence for geographically structured genetically divergent lineages, and although no haplotypes were shared between North America and Europe, the haplotypes from different continents were intermixed on a minimum spanning tree. European populations were much more highly differentiated and had much lower levels of haplotype diversity than their Alaskan counterparts. Centres of haplotype diversity were concentrated in those Alaskan populations located outside the limits of the last (Wisconsin) glaciation, suggesting that they may have acted as refugia during the Pleistocene. It was not possible to identify putative migration routes or corresponding refugia in the European genepool. One British population, from the Pentland Hills, was genetically very distant from all the others, for reasons that are as yet unknown.  (+info)