Flavonol derivatives of the genus Clibadium (compositae)

The flavonoids of eleven species of Clibadium are all based on the flavonols kaempferol, quercetin and quercetagetin. Glucose and galactose sugar substitutions occur in all taxa, while rhamnosides, arabinosides, xylosides, rutinosides and diglucosides are less widely distributed. O-Methylated compounds provide the most meaningful taxonomic information and serve to divide the species into two groups. Infraspecific variation of flavonoids is commonplace. This is the first report of flavonoids in Clibadium.     

The poultry red mite (Dermanyssus gallinae): a potential vector of pathogenic agents

The poultry red mite, D. gallinae has been involved in the transmission of many pathogenic agents, responsible for serious diseases both in animals and humans. Nowadays, few effective methods are available to control the ectoparasite in poultry farms. Consequently, this is an emerging problem which must be taken into account to maintain good health in commercial egg production. This paper addresses the vector capacity of the ectoparasite with special emphasis on salmonellae, pathogenic agents responsible for many of the most important outbreaks of food-borne diseases worlwide. It has been experimentally shown that D. gallinae could act as a biological vector of S. enteritidis and natural carriage of these bacteria by the mite on poultry premises has also been reported. It was also found that D. gallinae carried other pathogens such as E. coli, Shigella sp., and Staphylococcus, thus increasing the list of pathogenic agents potentially transmitted by the mite.     

Concerted Interconversion between Ionic Lock Substates of the β2 Adrenergic Receptor Revealed by Microsecond Timescale Molecular Dynamics

The recently solved crystallographic structures for the A_2A adenosine receptor and the β₁ and β₂ adrenergic receptors have shown important differences between members of the class-A G-protein-coupled receptors and their archetypal model, rhodopsin, such as the apparent breaking of the ionic lock that stabilizes the inactive structure. Here, we characterize a 1.02 μs all-atom simulation of an apo-β₂ adrenergic receptor that is missing the third intracellular loop to better understand the inactive structure. Although we find that the structure is remarkably rigid, there is a rapid influx of water into the core of the protein, as well as a slight expansion of the molecule relative to the crystal structure. In contrast to the x-ray crystal structures, the ionic lock rapidly reforms, although we see an activation-precursor-like event wherein the ionic lock opens for ∼200 ns, accompanied by movements in the transmembrane helices associated with activation. When the lock reforms, we see the structure return to its inactive conformation. We also find that the ionic lock exists in three states: closed (or locked), semi-open with a bridging water molecule, and open. The interconversion of these states involves the concerted motion of the entire protein. We characterize these states and the concerted motion underlying their interconversion. These findings may help elucidate the connection between key local events and the associated global structural changes during activation.     

Phylogenetic implications of corolla morphology in subfamily Barnadesioideae (Asteraceae)

The previously insignificant and small South American subtribe Barnadesiinae of tribe Mutisieae has been shown recently to be ancient within Asteraceae. Due to absence of a 22 kb diagnostic chloroplast inversion, plus other features, this subtribe has been elevated to subfamilial status as Barnadesioideae, now containing 90 species in nine genera. Recent cladistic analyses at the generic and specific levels based on morphology and DNA sequences (ITS and trnL intron) have revealed different relationships among taxa of the subfamily. To better understand these conflicts, we analyze specific morphological features of corollas (shape and vascularization) to develop trends (trees) in these features based on minimal structural change (i.e., morphological parsimony), and to compare these with relationships among genera derived from the two recent cladistic analyses. We define six principal types of corollas in Barnadesioideae (tubular, split, double split, ligulate, subbilabiate and bilabiate) and six principal types of corolla vascularization patterns (combinations of presence or absence of central bundles, fusion of adjacent bundles and fusion of bundles at the apex of corolla lobes). In all features we assume character states in Calyceraceae to be ancestral. In corolla shape, from tubular ancestry, we hypothesize two general evolutionary trends within the subfamily: (1) splitting of the tube, and (2) flattening of the tube. In vascularization of corollas, from an ancestral condition of one central and one lateral bundle in each corolla lobe and all traces fused at the apex, we hypothesize four basic trends: (1) gain or (2) loss of lateral vascular traces in each lobe, (3) loss of the central vein, and (4) loss of fusion of traces in lobe apices. These morphological trends allow tests of the two previous phylogenetic hypotheses by (1) counting step changes (following steps in the morphological network) in the two characters on the two competing phylogenetic trees and (2) constructing an index of morphological advancement for each genus (based on morphological trees of the two characters) and correlating these with cladistic distances within the two phylogenies. Results of both tests reveal the molecular phylogeny to be more compatible with evolutionary inferences from the two morphological features. With Fulcaldea excluded, a highly significant correlation is seen between morphological advancement and cladistic distance in the molecular phylogeny.     

Self-incompatibility and floral parameters in Hypochaeris sect. Hypochaeris (Asteraceae)

We studied the relationships between self-incompatibility mechanisms and floral parameters in the genus Hypochaeris L. sect. Hypochaeris (consisting of H. glabra, H. radicata, H. arachnoidea, and H. salzmanniana). We assessed at intra- and interspecific levels (1) the self-incompatibility (SI) mechanism and its distribution among populations, (2) the relationship between SI and floral parameters, and (3) the relationship of SI to reproductive success. Hypochaeris salzmanniana is semi-incompatible, H. glabra is self-compatible, and H. arachnoidea and H. radicata are self-incompatible. Floral parameters differed among populations of H. salzmanniana: plants in self-compatible populations had fewer flowers per head, a smaller head diameter on the flower, and a shorter period of anthesis than self-incompatible populations. We also detected this pattern within a semi-compatible population of H. salzmanniana, and these differences were also found between species with different breeding mechanisms. Fruit to flower ratio in natural populations was generally high (>60%) in all species, regardless of breeding system. It is hypothesized that self-compatibility may have arisen through loss of allelic diversity at the S locus due to bottleneck events and genetic drift.     

Phytoplankton composition of the Kandalaksha Gulf, Russian White Sea: Dinophysis and lipophilic toxins in the blue mussel (Mytilus edulis)

Dinophysis acuminata and D. norvegica were observed in plankton net samples during the summer of 2002 from the Kandalaksha Gulf in the White Sea (North European Russia). Prorocentrum lima was found as an epiphyte on subtidal macroalgae in August, but not observed in plankton net samples. Protein phosphatase 2A (PP2A) inhibition measured 127.8 ng OA-equivalent/g of mussel (Mytilus edulis) hepatopancreas from samples collected a few days after when Dinophysis was recorded at a density of 1550 cells L⁻¹. Liquid chromatography–mass spectrometry confirmed presence of several classes of lipophilic shellfish toxins associated with Dinophysis spp. in the mussels including okadaic acid, dinophysistoxin-1, pectenotoxins and yessotoxins. No azaspiracid was detected. This represents the first identification of phycotoxicity in the White Sea.     

The promiscuous and the chaste: frequent allopolyploid speciation and its genomic consequences in American daisies (Melampodium sect. Melampodium; Asteraceae)

Polyploidy, an important factor in eukaryotic evolution, is especially abundant in angiosperms, where it often acts in concert with hybridization to produce allopolyploids. The application of molecular phylogenetic techniques has identified the origins of numerous allopolyploids, but little is known on genomic and chromosomal consequences of allopolyploidization, despite their important role in conferring divergence of allopolyploids from their parental species. Here, using several plastid and nuclear sequence markers, we clarify the origin of tetra- and hexaploids in a group of American daisies, allowing characterization of genome dynamics in polyploids compared to their diploid ancestors. All polyploid species are allopolyploids. Among the four diploid gene pools, the propensity for allopolyploidization is unevenly distributed phylogenetically with a few species apparently more prone to participate, but the underlying causes remain unclear. Polyploid genomes are characterized by differential loss of ribosomal DNA loci (5S and 35S rDNA), known hotspots of chromosomal evolution, but show genome size additivity, suggesting limited changes beyond those affecting rDNA loci or the presence of processes counterbalancing genome reduction. Patterns of rDNA sequence conversion and provenance of the lost loci are highly idiosyncratic and differ even between allopolyploids of identical parentage, indicating that allopolyploids deriving from the same lower-ploid parental species can follow different evolutionary trajectories.