Comparative study of two thioredoxin peroxidases from disk abalone (Haliotis discus discus): cloning, recombinant protein purification, characterization of antioxidant activities and expression analysis

Thioredoxin peroxidase (TPx), also named peroxiredoxin (Prx), is an important peroxidase, which can protect organisms against various oxidative stresses. Two TPxs were isolated from a disk abalone (Haliotis discus discus) cDNA library, named as AbTPx1 and AbTPx2, respectively. AbTPx1 and AbTPx2 consist of 1315 and 1045 bp full-length cDNA with 753 and 597 bp open reading frames encoding 251 and 199 amino acids, respectively. The TPx signature motif 1 (FYPLDFTFVCPTEI) and motif 2 (GEVCPA) were conserved in both AbTPx1 and AbTPx2 amino acid sequences. Purified recombinant abalone TPx fusion proteins catalyzed the reduction of H2O2 and butyl hydroperoxide in peroxidase assays. Furthermore, both AbTPx fusion proteins were shown to protect super-coiled DNA from damage by metal-catalyzed oxidation (MCO) in vitro. Escherichia coli cells transformed with AbTPx1 and AbTPx2 coding sequences in pMAL-c2x showed resistance to H2O2 at 0.8 mM concentration by in vivo H2O2 tolerance assay. AbTPx1 and AbTPx2 mRNA were constitutively expressed in gill, mantle, abductor muscle and digestive tract in a tissue specific manner. Additionally, both TPxs mRNA were up-regulated in gill and digestive tract tissues against H2O2 at 3h post injection. The results indicate that AbTPx1 and AbTPx2 gene expressions are induced by oxidative stress and their respective proteins function in the detoxification of different ROS molecules to maintain efficient antioxidant defense in disk abalone.     

Systematics and cladistics of Megalostomis Chevrolat,and the biogeography of Clytrini (Coleoptera: Cryptocephalinae)

We present a cladistic analysis of the subtribe Megalostomina, a Neotropical group of ‘case‐bearer’ leaf beetles. A comparative study of the external and internal adult morphology of Clytrini was undertaken. New characters are described for the subtribe Megalostomina, from the internal sac of aedeagus, which provide a useful phylogenetic signal. More than 180 photographs illustrating the most important characters (74 characters and their respective states) used in the cladistic analysis are provided. The cladistic analysis of 57 terminal taxa and 95 characters was undertaken, under equal weights, and also using implied weights as a means to down‐weight homoplasious characters. We test the monophyly and explore intergeneric relationships of the subtribe Megalostomina, and reconstruct the relationships among the species of Megalostomis Chevrolat. The 42 species recognized can be assigned either to a group mostly containing species of North and Central America, or to a larger one of mostly South American species. Support is low, and the formal naming of groups is deferred pending a revision of all Megalostomina. We confirm the subgenera of Megalostomis of previous classifications are unnatural, and the following changes in the generic classification of the subtribe Megalostomina are proposed: Coleorozena Moldenke syn.n. of Coscinoptera Lacordaire; Coleothorpa Moldenke syn.n. of Coscinoptera Lacordaire; and Euryscopa (Coleoguerina) Moldenke syn.n. of Coscinoptera Lacordaire. Furthermore, six formerly recognized subgenera of Megalostomis are considered junior synonyms of Megalostomis Chevrolat: Megalostomis (Minturnia) Lacordaire syn.n. ; Megalostomis (Heterostomis) Lacordaire syn.n. ; Megalostomis (Scaphigenia) Lacordaire syn.n. ; Megalostomis (Snellingia) Moldenke syn.n. ; Megalostomis (Coleobyersa) Moldenke syn.n. ; and Megalostomis (Pygidiocarina) Moldenke syn.n. Thus, no subgenera are recognized within Megalostomis. Previous hypotheses on Clytrini biogeography were revisited in the light of new biogeographic and phylogenetic knowledge. We hypothesize an origin of Clytrini in tropical/subtropical Gondwana, when South America, Africa, Madagascar and India were connected. Changes in the configuration of the tectonic plates in the Cenozoic allowed the dispersal of Clytrina to the Palaearctic and Nearctic regions, and dispersion of Babiina and Megalostomina through the Nearctic region.     

Resin gathering in neotropical resin bugs (Insecta: Hemiptera: Reduviidae): Functional and comparative morphology

Apiomerini (Reduviidae: Harpactorinae) collect plant resins with their forelegs and use these sticky substances for prey capture or maternal care. These behaviors have not been described in detail and morphological structures involved in resin gathering, transfer, and storage remain virtually undocumented. We here describe these behaviors in Apiomerus flaviventris and document the involved structures. To place them in a comparative context, we describe and document leg and abdominal structures in 14 additional species of Apiomerini that represent all but one of the 12 recent genera in the tribe. Based on these morphological data in combination with the behavioral observations on A. flaviventris, we infer behavioral and functional hypotheses for the remaining genera within the tribe Apiomerini. Setal abdominal patches for resin storage are associated with maternal care so far only documented for species of Apiomerus. Based on the occurrence of these patches in several other genera, we propose that maternal care is widespread within the tribe. Ventral abdominal glands are widespread within female Apiomerini. We propose that their products may prevent hardening of stored resins thus providing long‐term supply for egg coating. Judging from the diverse setal types and arrangements on the front legs, we predict six different behavioral patterns of resin gathering within the tribe. J. Morphol., 2011. © 2010 Wiley‐Liss, Inc.     

Biological activity of water-soluble nanostructures of dihydroquercetin with cyclodextrins

The biological properties of dihydroquercetin (DHQ) modified by including it into the ring of β-cyclodextrin (β-CD) to give it more water-soluble properties have been investigated. It was shown that the peroral administration of the DHQ/β-CD complex provides a long increase of DHQ concentration in rat blood (up to 7.5 h), and, unlike pure DHQ, the complex does not accumulate in the liver. As DHQ is released from the complex, it penetrates into liposome membranes, changing their thermodynamic characteristics. DHQ decreases the specific heat absorption, enthalpies, and temperature maximum of lipid melting and increases the transition half-width. This property is used to estimate the stability of the DHQ/β-CD complex. It was shown that complex DHQ/β-CD is not stable, and DHQ molecules slowly leave the complex in water environment. Seven and a half hours after the peroral injection of drugs, DHQ was found in the blood plasma of rats to which water-soluble complex DHQ/βCD was injected and in the liver of rats to which free DHQ was injected. Thus, DHQ/βCD not only is a more water-soluble complex but also it slowly releases DHQ, supporting long a low concentration of the free form of DHQ and providing the penetration of DHQ into the blood stream. After several weeks of feeding old mice with antioxidants, the activity of mitochondrial enzymes was restored to the level observed in young animals.     

A Dated Phylogeny Complements Macroecological Analysis to Explain the Diversity Patterns in Geonoma (Arecaceae)

Integrating phylogenetic data into macroecological studies of biodiversity patterns may complement the information provided by present‐day spatial patterns. In the present study, we used range map data for all Geonoma (Arecaceae) species to assess whether Geonoma species composition forms spatially coherent floristic clusters. We then evaluated the extent to which the spatial variation in species composition reflects present‐day environmental variation vs. nonenvironmental spatial effects, as expected if the pattern reflects historical biogeography. We also examined the degree of geographic structure in the Geonoma phylogeny. Finally, we used a dated phylogeny to assess whether species richness within the floristic clusters was constrained by a specific historical biogeographic driver, namely time‐for‐diversification. A cluster analysis identified six spatially coherent floristic clusters, four of which were used to reveal a significant geographic phylogenetic structure. Variation partitioning analysis showed that 56 percent of the variation in species composition could be explained by spatial variables alone, consistent with historical factors having played a major role in generating the Geonoma diversity pattern. To test for a time‐for‐diversification effect, we correlated four different species richness measures with the diversification time of the earliest large lineage that is characteristic of each cluster. In support of this hypothesis, we found that geographic areas with higher richness contained older radiations. We conclude that current geographic diversity patterns in Geonoma reflect the present‐day climate, but to a larger extent are related to nonenvironmental spatial constraints linked to colonization time, dispersal limitation, and geological history, followed by within‐area evolutionary diversification. Abstract in Spanish is available at http://www.blackwell‐synergy.com/loi/btp .