Phylogeny of Greya (Lepidoptera: Prodoxidae), based on nucleotide sequence variation in mitochondrial cytochrome oxidase I and II: congruence with morphological data

The phylogeny of Greya Busck (Lepidoptera: Prodoxidae) was inferred from nucleotide sequence variation across a 765-bp region in the cytochrome oxidase I and II genes of the mitochondrial genome. Most parsimonious relationships of 25 haplotypes from 16 Greya species and two outgroup genera (Tetragma and Prodoxus) showed substantial congruence with the species relationships indicated by morphological variation. Differences between mitochondrial and morphological trees were found primarily in the positions of two species, G. variabilis and G. pectinifera, and in the branching order of the three major species groups in the genus. Conflicts between the data sets were examined by comparing levels of homoplasy in characters supporting alternative hypotheses. The phylogeny of Greya species suggests that host-plant association at the family level and larval feeding mode are conservative characters. Transition/transversion ratios estimated by reconstruction of nucleotide substitutions on the phylogeny had a range of 2.0-9.3, when different subsets of the phylogeny were used. The decline of this ratio with the increase in maximum sequence divergence among taxa indicates that transitions are masked by transversions along deeper internodes or long branches of the phylogeny. Among transitions, substitutions of A-->G and T-->C outnumbered their reciprocal substitutions by 2-6 times, presumably because of the approximately 4:1 (77%) A+T-bias in nucleotide base composition. Of all transversions, 73%-80% were A<-->T substitutions, 85% of which occurred at third positions of codons; these estimates did not decrease with an increase in maximum sequence divergence of taxa included in the analysis. The high frequency of A<-->T substitutions is either a reflection or an explanation of the 92% A+T bias at third codon positions.      

An investigation of the co-evolutionary relationships between onchobothriid tapeworms and their elasmobranch hosts

There is general consensus that the living elasmobranchs comprise a monophyletic taxon. There is evidence that, among tetraphyllidean tapeworms, the approximately 201 hooked species (Onchobothriidae) may also comprise a monophyletic group. Determinations of host specificity are contingent upon correct specific identifications. Since 1960, over 200 new elasmobranch species and over 100 new onchobothriid species have been described. Some confidence can be placed in host and parasite identifications of recent studies, but specific identifications provided in older literature in many cases are suspect. There is some consensus among published works on the phylogenetic relationships among elasmobranchs. Phylogenetic relationships among onchobothriids remain largely unresolved. Elasmobranchs have been poorly sampled for onchobothriids; records exist for approximately 20% of the 911 species and approximately 44% of the 170 elasmobranch genera. Onchobothriids are remarkably host specific, exhibiting essentially oioxenous specificity for their definitive hosts. Multiple onchobothriid species commonly parasitise the same host species; in some cases these are congeners, in other cases these are members of two different onchobothriid genera. There is substantial incongruence between available host and parasite phylogenies. For example, Acanthobothrium is by far the most ubiquitous onchobothriid genus, parasitising almost all orders of elasmobranchs known to host onchobothriids, yet, there is no evidence of major clades of Acanthobothrium corresponding to postulated major subgroupings of elasmobranchs (e.g. Galea and Squalea or sharks and rays). Potamotrygonocestus appears to be among the most basal onchobothriid groups, yet it parasitises one of the most derived elasmobranch groups (the freshwater stingray genus Potamotrygon). It appears that congeners parasitising the same host species are not necessarily each other's closest relatives. At this point the preliminary and limited available data suggest that, at least in this system, strict host specificity is not necessarily indicative of strict co-evolution. This study was extremely limited by the lack of available robust phylogenies for onchobothriids and elasmobranchs.     

Evolution of the major lineages of tapeworms (Platyhelminthes: Cestoidea) inferred from 18S ribosomal DNA and elongation factor-1alpha

The interrelationships of the tapeworms (Platyhelminthes: Cestoidea) were inferred by analysis of complete gene sequences (approximately 2,200 bp) of 18S small subunit ribosomal DNA (18S) and partial gene sequences (approximately 900 bp) of elongation factor-1alpha (Ef-1alpha). New collections were made of 23 species representing each of the 14 currently recognized orders of tapeworms, including the Amphilinidea, Gyrocotylidea, and the 12 orders of the Eucestoda. Sequences were determined directly from polymerase chain reaction (PCR) products by either manual or automated methods. Nucleotide sequences of platyhelminth species outside of the Cestoidea were obtained for rooting the resulting trees. The 18S sequences were aligned with reference to the secondary structural features of the gene and the Ef-1alpha sequences were aligned with reference to their corresponding amino acid residues. Significant length variation among taxa was observed in the V2, V4, and V7 variable regions of the 18S gene. Such positions where sequences could not be aligned confidently were excluded from the analyses. Third codon positions of the Ef-1alpha gene were inferred to be saturated at an ordinal level of comparison. In addition, a short (approximately 35 bp) intron region of the Ef-1alpha gene was found to be shared only among the eucestode taxa, with the exception of Spathebothrium simplex (Spathebothriidea), which lacked the intron. Complete alignments showing structural features of the genes and sites excluded from analysis are provided as appendices. The sequence data were partitioned into 7 data sets in order to examine the effects of analyses on different subsets of the data. Analyses were conducted on the 2 genes independently, different codon positions of Ef-1alpha, amino acid sequences of Ef-1alpha, and combinations thereof. All subsets of the data were analyzed under the criterion of maximum parsimony as well as minimum evolution using both maximum-likelihood estimated, and LogDet-transformed distances. Results varied among the different data partitions and methods of analysis. Nodes with strong character support, however, were consistently recovered, and a general pattern of evolution was observed. Monophyly of the Cestoidea (Amphilinidea + Gyrocotylidea + Eucestoda) and Eucestoda and the traditionally accepted positions of the Amphilinidea and Gyrocotylidea as sister lineages to the Eucestoda were supported. Within the Eucestoda, the Spathebothriidea was found to be the sister of all other eucestodes. The remaining orders generally formed a diphyletic pattern of evolution consisting of separate difossate and tetrafossate lineages. This pattern was not universally observed among the analyses, primarily because the trypanorhynch and diphyllidean taxa showed instability in their phylogenetic position. Additional relationships that showed high levels of nodal support included a sister relationship between the Pseudophyllidea and Haplobothriidea and a clade uniting the Cyclophyllidea, Nippotaeniidea, and Tetrabothriidea. The Tetraphyllidea, as currently defined, was found to be paraphyletic without the inclusion of the orders Proteocephalidea and, possibly, Lecanicephalidea. Ordinal status of a monophyletic Litobothriidea, currently classified within the Tetraphyllidea, was found to be supported from a phylogenetic perspective.     

Preparation and physicochemical characterization of 5 niclosamide solvates and 1 hemisolvate

The purpose of the study was to characterize the physicochemical, structural, and spectral properties of the 1∶1 niclosamide and methanol, diethyl ether, dimethyl sulfoxide, N,N' dimethylformamide, and tetrahydrofuran solvates and the 2∶1 niclosamide and tetraethylene glycol hemisolvate prepared by recrystallization from these organic solvents. Structural, spectral, and thermal analysis results confirmed the presence of the solvents and differences in the structural properties of these solvates. In addition, differences in the activation energy of desolvation, batch solution calorimetry, and the aqueous solubility at 25°C, 24 hours, showed the stability of the solvates to be in the order: anhydrate > diethyl ether solvate > tetraethylene glycol hemisolvate > methanol solvate > dimethyl sulfoxide solvate > N,N' dimethylformamide solvate. The intrinsic and powder dissolution rates of the solvates were in the order: anhydrate > diethyl ether solvate > tetraethylene glycol hemisolvate > N,N' dimethylformamide solvate > methanol solvate > dimethyl sulfoxide solvate. Although these nonaqueous solvates had higher solubility and dissolution rates than the monohydrous forms, they were unstable in aqueous media and rapidly transformed to one of the monohydrous forms.     

Analysis of plastid DNA-like sequences within the nuclear genomes of higher plants

A wide-ranging examination of plastid (pt)DNA sequence homologies within higher plant nuclear genomes (promiscuous DNA) was undertaken. Digestion with methylation-sensitive restriction enzymes and Southern analysis was used to distinguish plastid and nuclear DNA in order to assess the extent of variability of promiscuous sequences within and between plant species. Some species, such as Gossypium hirsutum (cotton), Nicotiana tabacum (tobacco), and Chenopodium quinoa, showed homogenity of these sequences, while intraspecific sequence variation was observed among different cultivars of Pisum sativum (pea), Hordeum vulgare (barley), and Triticum aestivum (wheat). Hypervariability of plastid sequence homologies was identified in the nuclear genomes of Spinacea oleracea (spinach) and Beta vulgaris (beet), in which individual plants were shown to possess a unique spectrum of nuclear sequences with ptDNA homology. This hypervariability apparently extended to somatic variation in B. vulgaris. No sequences with ptDNA homology were identified by this method in the nuclear genome of Arabidopsis thaliana.      

Cestode systematics and phylogeny move forward

This paper represents a meeting report for the Fifth International Workshop on Cestode Systematics and Phylogeny held at the Institute of Parasitology, Academy of Sciences of the Czech Republic, České Budějovice, 18–22 July 2005. The major topics discussed included (i) the progress in cestode systematics during 2002–2005, (ii) the use of the life-cycle data in phylogenetic studies, (iii) the utilisation of new morphological and molecular characters in cestode systematics and phylogeny, and (iv) the ongoing work on the completion of the Global Cestode Database.     

Endoglin (CD105) expression is regulated by the liver X receptor alpha (NR1H3) in human trophoblast cell line JAR

Human implantation involves invasion of the uterine wall and remodeling of uterine arteries by extravillous cytotrophoblasts. Defects in these early steps of placental development lead to poor placentation and are often associated with preeclampsia, a frequent complication of human pregnancy. One of the complex mechanisms controlling trophoblast invasion involves the activation of the liver X receptor beta (or NR1H2, more commonly known as LXRbeta) by oxysterols known as potent LXR activators. This activation of LXRbeta leads to a decrease of trophoblast invasion. The identification of new target genes of LXR in the placenta could aid in the understanding of their physiological roles in trophoblast invasion. In the present study, we show that the endoglin (ENG) gene is a direct target of the liver X receptor alpha (NR1H3, also known as LXRalpha). ENG, whose gene is highly expressed in syncytiotrophoblasts, is part of the transforming growth factor (TGF) receptor complex that binds several members of the TGFbeta superfamily. In the human placenta, ENG has been shown to be involved in the inhibition of trophoblast invasion. Treatment of human choriocarcinoma JAR cells with T0901317, a synthetic LXR-selective agonist, leads to a significant increase in ENG mRNA and protein levels. Using transfection and electrophoretic mobility shift assays, we demonstrate that LXR (as a heterodimer with the retinoid X receptor) is able to bind the ENG promoter on an LXR response element and mediates the activation of ENG gene expression by LXRalpha in JAR cells. This study suggests a novel mechanism by which LXR may regulate trophoblast invasion in pathological pregnancy such as preeclampsia.