Resolving species boundaries in a recent radiation with the Angiosperms353 probe set: the Lomatium packardiae/L. anomalum clade of the L. triternatum (Apiaceae) complex

PREMISE

Speciation not associated with morphological shifts is challenging to detect unless molecular data are employed. Using Sanger-sequencing approaches, the Lomatium packardiae/L. anomalum subcomplex within the larger Lomatium triternatum complex could not be resolved. Therefore, we attempt to resolve these boundaries here.

METHODS

The Angiosperms353 probe set was employed to resolve the ambiguity within Lomatium triternatum species complex using 48 accessions assigned to L. packardiae, L. anomalum, or L. triternatum. In addition to exon data, 54 nuclear introns were extracted and were complete for all samples. Three approaches were used to estimate evolutionary relationships and define species boundaries: STACEY, a Bayesian coalescent-based species tree analysis that takes incomplete lineage sorting into account; ASTRAL-III, another coalescent-based species tree analysis; and a concatenated approach using MrBayes. Climatic factors, morphological characters, and soil variables were measured and analyzed to provide additional support for recovered groups.

RESULTS

The STACEY analysis recovered three major clades and seven subclades, all of which are geographically structured, and some correspond to previously named taxa. No other analysis had full agreement between recovered clades and other parameters. Climatic niche and leaflet width and length provide some predictive ability for the major clades.

CONCLUSIONS

The results suggest that these groups are in the process of incipient speciation and incomplete lineage sorting has been a major barrier to resolving boundaries within this lineage previously. These results are hypothesized through sequencing of multiple loci and analyzing data using coalescent-based processes.

Polyphenols from the sagebrush Artemisia tridentata ssp. tridentata affect the redox state of cultured hepatocytes by direct and indirect mechanisms

Basin big sagebrush (Artemisia tridentata Nutt. ssp. tridentata (Asteraceae)), is a widespread North American shrub which produces a variety of polyphenolic compounds. Although sagebrush has been used as a traditional remedy by natives and settlers to the region, the polyphenols in Artemisia tridentata ssp. tridentata have not been highly investigated for their bioactive properties. To determine whether these polyphenols affect the intracellular redox state, we measured their ability to neutralize radicals in vitro and in a human liver carcinoma cell line (HepG2), and their effects on intracellular glutathione levels. Extracts from Artemisia tridentata ssp. tridentata decreased the oxidation of 2'7'-dichlorofluorescin in vitro and in cultured cells. Cells treated with polyphenolic extracts showed increased levels of glutathione in a time and dose-dependent manner. Approximately 48 polyphenolic compounds were distinguishable in extracts, by HPLC/UV absorbance detection. Mass spectroscopy was used to identify thirteen compounds as aesculin, aesculetin, apigenin, apigenin-7-O-glucoside, axillarin, casticin, chlorogenic acid, isoscopoletin, kaempferol, luteolin, methyl-axillarin, quercetin, and scopoletin. These results indicate that polyphenols produced in Artemisia tridentata ssp. tridentata affect the redox state of living cells by multiple mechanisms.

Partial purification and some properties of a cholinesterase from bush bean (Phaseolus vulgaris L.) roots

A cholinesterase was partially purified from bush bean (Phaseolus vulgaris L.) roots by using acridinium-based ligand affinity chromatography. The procedure gave a 78-fold increase in specific activity, although at least three inactive contaminants remained. The enzyme activity was maximal against acetyl esters of choline and was inhibited by neostigmine. Di-isopropyl phosphorofluoridate completely inhibited activity at concentrations greater than 0.1 mM. The catalytic centre activity was 2 X 10(-4) times that of electric eel acetylcholinesterase. Cholinesterase activity appeared as a peak (s = 4.2 +/- 0.1 S) after isokinetic sedimentation. The Stokes radius was 4.00 nm and the apparent molecular weight was 72700 +/- 1900. The smallest active and native form of the enzyme appeared to be a monomer. This contrasts with animal acetylcholinesterases, in which the smallest active and native forms are multimeric.