The generic placement of a morphologically enigmatic species in Asteraceae: evidence from ITS sequences

 Bidens cordylocarpa is a high polyploid species restricted in distribution to stream sides in the mountains of Jalisco, Mexico. The morphologically enigmatic species was originally described as a member of the genus Coreopsis, but later transferred to Bidens, largely because the involucral bracts appear most similar to Bidens. Characters of the cypselae, often useful in generic placement, are of no value for this species because the fruits have features not detected in either Bidens or Coreopsis. Sequences from the internal transcribed spacer region of nuclear ribosomal DNA (ITS) were used to assess the relationships of Bidens cordylocarpa. The molecular phylogeny places B. cordylocarpa in a strongly supported clade of Mexican and South American Bidens, and provides more definitive evidence of relationships than morphology, chromosome number, or secondary chemistry. Molecular, morphological, and chromosomal data suggest that B. cordylocarpa is an ancient polyploid, perhaps the remnant of a polyploid complex. Received August 28, 2000 Accepted February 11, 2001     

The Biopolymer Markup Language.

SUMMARY: An XML derived from a data model designed to be a hierarchical representation of an organism has been specified and a browser to use this language has been developed. AVAILABILITY: The language definition is available in HTML form at http://www.proteometrics.com/BIOML/. The BioML browser is available on request from the author.     

Kinetics of acetylation-deacetylation of angiotensin II. Intramolecular interactions of the tyrosine and histidine side-chains

The possible existence of intramolecular interactions involving the tyrosine and histidine residues in angiotensin II has been investigated by measuring the reactivities of the functional groups in the molecule. Angiotensin II catalyzed the hydrolysis of p-nitrophenylacetate in the pH range 6.6-8.2 at higher rates than were consistent with the reactivities of the free constituent functional groups, and had 2-4% of the activity of chymotrypsin between pH 6.6 and 7.5. Treatment of angiotensin II with acetic anhydride demonstrated that the tyrosine hydroxyl and the imidazole side-chain in angiotensin II acetylated and deacetylated at markedly higher rates than for the free amino acids, indicating increased nucleophilicities and the presence of intrinsic deacetylation mechanisms for these residues in angiotensin II. These findings are consistent with the presence of tyrosine hydroxyl-histidine-carboxylate charge relay system in ANG II in aqueous environments, and suggest that ANG II may act at membrane receptors by a mechanism which is analogous to that operating in serine proteases.     

Cloning of aroG, the gene coding for phospho-2-keto-3-deoxy-heptonate aldolase(phe), in Escherichia coli K-12, and subcloning of the aroG promoter and operator in a promoter-detecting plasmid

Defective transducing phages carrying aroG, the structural gene for phenylalanine (phe)-inhibitable phospho-2-keto-heptonate aldolase (EC 4.1.2.15; previously known as 3-deoxy-D-arabinoheptulosonate-7-phosphate synthetase[phe]), have been isolated, and DNA from two of these phages has been used to construct a restriction map of the region from att lambda to aroG. A 7.6-kb PstI-HindIII fragment from one of these phages was cloned into pBR322 and shown to contain aroG. The location of aroG within the 7.6 kb was established by subcloning and Tn3 transpositional mutagenesis. A fragment carrying the aroG promoter and operator has been cloned into a high copy number promoter-cloning vector (pMC489), and the resulting aroGpo-LacZ' (alpha) fusion subcloned in a low copy number vector. Strains with this fusion on the low copy number vector exhibit negative regulation of beta-galactosidase expression by both phenylalanine and tryptophan and positive regulation by tyrosine in a tyrR+ background.     

Action of pilocarpine on the normal frog heart and in pathology

Experiments on frogs were performed to examine the effect of the M-cholinomimetic pilocarpine on the heart. It was discovered that at concentrations of 10(-15)--10(-5) g/ml pilocarpine exerted only an adverse chronotropic effect on the perfused heart. When applied at a concentration of 10(-4) g/ml the drug produced a negative as well as a positive chronotropic effect. The latter occurred spasmodically (without progressive rise in the heart rate) in association with a slow heart rate. In some experiments such effects were preceded by a certain deceleration of the heart. In experiments with positive chronotropic effects, arrhythmias and sinoatrial dissociation were observed sometimes. Experiments with recording of the electrograms of the sinuses and lower parts showed that such effects were caused not by pacemaker acceleration but by the removal of the blockade of conduction, between the pacemaker and the atria. As far as the pacemaker is concerned, pilocarpine exerted only a negative chronotropic effect.     

Purification and characterization of carbon monoxide dehydrogenase, a nickel, zinc, iron-sulfur protein, from Rhodospirillum rubrum

Carbon monoxide dehydrogenase (CO dehydrogenase) from Rhodospirillum rubrum was shown to be an oxygen-sensitive, nickel, iron-sulfur, and zinc-containing protein that was induced by carbon monoxide (CO). The enzyme was purified 212-fold by heat treatment, ion-exchange, and hydroxylapatite chromatography and preparative gel electrophoresis. The purified protein, active as a monomer of Mr = 61,800, existed in two forms that were comprised of identical polypeptides and differed in metal content. Form 1 comprised 90% of the final activity, had a specific activity of 1,079 mumol CO oxidized per min-1 mg-1, and contained 7 iron, 6 sulfur, 0.6 nickel, and 0.4 zinc/monomer. Form 2 had a lower specific activity (694 mumol CO min-1 mg-1) and contained 9 iron, 8 sulfur, 1.4 nickel, and 0.8 zinc/monomer. Reduction of either form by CO or dithionite resulted in identical, rhombic ESR spectra with g-values of 2.042, 1.939, and 1.888. Form 2 exhibited a 2-fold higher integrated spin concentration, supporting the conclusion that it contained an additional reducible metal center(s). Cells grown in the presence of 63NiCl2 incorporated 63Ni into CO dehydrogenase. Although nickel was clearly present in the protein, it was not ESR-active under any conditions tested. R. rubrum CO dehydrogenase was antigenically distinct from the CO dehydrogenases from Methanosarcina barkeri and Clostridium thermoaceticum.     

Antibodies against calcium-regulating hormones in infectious-allergic forms of bronchial asthma

Antibodies to calcitonin, parathyroid hormone and cortisol are detected in acute stage of infection-caused bronchial asthma. The appearance of antibodies is paralleled by marked hypercalcaemia. The antibodies may bind excessive hormones in the blood, preventing further hormonal imbalance. Ten-day treatment with glucocorticoids decreased the amount of antibodies possibly due to normalization of hormonal secretion and restoration of their balance. As a result, calcium blood levels returned to normal.     

State of aggregation of the (Ca2+ + Mg2+)-ATPase studied using saturation-transfer electron spin resonance

The state of aggregation of the (Ca2+ + Mg2+)-ATPase in the membrane of sarcoplasmic reticulum and in reconstituted membrane systems has been studied using saturation-transfer electron spin resonance (ST-ESR). Saturation-transfer ESR spectra show that in the sarcoplasmic reticulum, the ATPase is relatively free to rotate, with an effective rotational correlation time of approx. 33 microseconds at 4 degrees C, consistent with a monomeric or dimeric structure. The rate of rotation is observed to decrease with decreasing molar ratio of lipid to protein. In reconstituted systems, rotational motion of the ATPase on the millisecond time scale ceases when the lipids are in the gel phase. Addition of decavanadate, which causes the formation of crystalline arrays in negatively stained electron micrographs, results in only a small reduction in rotation rate for the ATPase in the membrane. The experiments are interpreted in terms of a short-lived (on the millisecond time scale) protein-protein interaction, with the formation of crystalline clusters of ATPase molecules which form and melt rapidly.