A phylogenetic analysis of species in the Bufo crucifer group (Anura: Bufonidae), based on indolealkylamines and proteins from skin secretions

This research tested the utility of two classes of skin secretion compounds to the phylogeny of the Bufo crucifer group. Skin secretions from specimens of nine populations of B. crucifer group were obtained and submitted to qualitative analysis. We observed a clear difference in the composition of the skin secretion molecules obtained from the species of Bufo studied. Fifty-nine molecules, 16 indolealkylamines and 43 proteins, were used as characters, and 39 of these were parsimonious informative. The tree topology of the skin secretion combined data showed areas of congruence and conflict when compared to an mtDNA phylogeny of the B. crucifer group. We used the Templeton test to evaluate the heterogeneity between the skin secretion and mtDNA data. Although not recommended, we performed a combined analysis with the two partitions. The skin secretion characters from the species of Bufo studied have phylogenetic signal. These data are indicative, at least as a preliminary study, of the phylogenetic relationships among the B. crucifer group taxa.     

Effect of microwave treatment on the shear bond strength of different types of commercial teeth to acrylic resin

doi:10.1111/j.1741‐2358.2009.00333.x
Effect of microwave treatment on the shear bond strength of different types of commercial teeth to acrylic resin Objective: The purpose of this study was to verify the effect of microwave treatment on the shear bond strength of commercial types of teeth to acrylic resin, when the glossy ridge laps were unmodified (groups 1 and 5), bur abraded (groups 2 and 6), bur grooved (groups 3 and 7) or etched by monomer (groups 4 and 8). Background: Controversial findings have shown that mechanical or chemical changes in ridge‐lap surface of the tooth increase or decrease the bond strength between tooth and acrylic resin, and the microwave disinfection may cause different changes on this bond strength. Materials and methods: Eighty specimens (n = 10) were made with the acrylic resin bonded to tooth glossy ridge lap, polymerised in water at 74°C for 9 h, and deflasked after flask cooling. Specimens of the groups 5, 6, 7 and 8 were individually immersed in 150 ml of water and submitted to microwave treatment in an oven at 650 W for 3 min. Control specimens (groups 1, 2, 3 and 4) were not microwave treated. Shear bond strength test was performed in an Instron machine with a cross‐speed of 1 mm/min. Collected data were submitted to anova and Tukey’s test (α = 0.05). Results: Microwave treatment decreased the shear bond strength values of the tooth/resin bond. In the microwaved and non‐microwaved procedures, mechanical retention improved the shear bond strength when compared with the control and monomer treatments. Conclusion: Shear bond strength of the tooth/resin bond was influenced by the microwave treatment and different commercial teeth association, and was lower for the Biotone tooth.     

Intestinal synthesis of 24-keto-1,25-dihydroxyvitamin D3. A metabolite formed in vivo with high affinity for the vitamin D cytosolic receptor

24-Keto-1,25-dihydroxyvitamin D3 has been identified as an intestinal metabolite of 1,25-dihydroxyvitamin D3 by ultraviolet absorbance, mass spectroscopy, and chemical reactivity. The metabolite was produced from 1,25-dihydroxyvitamin D3 and 1,24R,25-trihydroxyvitamin D3 in rat intestinal mucosa homogenates. 24-Keto-1,25-dihydroxyvitamin D3 is present in vivo in the plasma and small intestinal mucosa of rats fed a stock diet, receiving no exogenous 1,25-dihydroxyvitamin D3, and in the plasma and small intestinal mucosa of rats dosed chronically with 1,25-dihydroxyvitamin D3. 24-Keto-1,25-dihydroxyvitamin D3 has affinity equivalent to 1,24R,25-trihydroxyvitamin D3 for the 3.7 S cytosolic receptor specific for 1,25-dihydroxyvitamin D3 in the intestine and thymus. In cytosolic preparations contaminated with the 5 S vitamin D-binding protein, both metabolites are about 7-fold less potent than 1,25-dihydroxyvitamin D3. In contrast, in cytosolic preparations largely free of the 5 S binding protein, both metabolites are equipotent with the parent compound. No evidence was obtained supporting a substantial presence of 23-keto-1,25-dihydroxyvitamin D3 in vivo; nor was the latter compound generated in detectable amounts from 1,25-dihydroxyvitamin D3 by intestinal homogenates. Thus, C-24 oxidation is a significant pathway of intestinal 1,25-dihydroxyvitamin D3 metabolism that produces metabolites with high affinity for the cytosolic receptor which mediates vitamin D action.     

The importance of location and visual cues during foraging in the German wasp (Vespula germanica F.) (Hymenoptera: Vespidae)

Abstract

The way in which foraging wasps use cues for prey location and choice appears to depend on both the context and on the type of prey. Vespula germanica is an opportunistic, generalist prey forager, and individual wasp foragers often return to hunt at sites of previous hunting success. In this paper, we studied which cues are used by this wasp when relocating a food source. Particularly we analysed the response to a displaced visual cue versus a foraging location at which either honey or cat food had been previously presented. We conclude that location is used over a displaced visual cue for directing wasp hovering, although the landing response is directed differently according to bait type. When wasps are exploiting cat food, location also elicits landing, but if they are exploiting honey, a displaced visual cue elicits landing more frequently than location.     

Host Cell Poly(ADP-Ribose) Glycohydrolase Is Crucial for Trypanosoma cruzi Infection Cycle

Trypanosoma cruzi, etiological agent of Chagas’ disease, has a complex life cycle which involves the invasion of mammalian host cells, differentiation and intracellular replication. Here we report the first insights into the biological role of a poly(ADP-ribose) glycohydrolase in a trypanosomatid (TcPARG). In silico analysis of the TcPARG gene pointed out the conservation of key residues involved in the catalytic process and, by Western blot, we demonstrated that it is expressed in a life stage-dependant manner. Indirect immunofluorescence assays and electron microscopy using an anti-TcPARG antibody showed that this enzyme is localized in the nucleus independently of the presence of DNA damage or cell cycle stage. The addition of poly(ADP-ribose) glycohydrolase inhibitors ADP-HPD (adenosine diphosphate (hydroxymethyl) pyrrolidinediol) or DEA (6,9-diamino-2-ethoxyacridine lactate monohydrate) to the culture media, both at a 1 µM concentration, reduced in vitro epimastigote growth by 35% and 37% respectively, when compared to control cultures. We also showed that ADP-HPD 1 µM can lead to an alteration in the progression of the cell cycle in hydroxyurea synchronized cultures of T. cruzi epimastigotes. Outstandingly, here we demonstrate that the lack of poly(ADP-ribose) glycohydrolase activity in Vero and A549 host cells, achieved by chemical inhibition or iRNA, produces the reduction of the percentage of infected cells as well as the number of amastigotes per cell and trypomastigotes released, leading to a nearly complete abrogation of the infection process. We conclude that both, T. cruzi and the host, poly(ADP-ribose) glycohydrolase activities are important players in the life cycle of Trypanosoma cruzi, emerging as a promising therapeutic target for the treatment of Chagas’ disease.     

PHYLOGENY AND SYSTEMATICS OF THE MARINE ALGAL FAMILY GRACILARIACEAE (GRACILARIALES,RHODOPHYTA) BASED ON SMALL SUBUNIT rDNA AND ITS SEQUENCES OF ATLANTIC AND PACIFIC SPECIES1

We sequenced the small subunit rDNA and internal transcribed spacer region of Gracilariaceae from the tropical Atlantic and Pacific, with emphasis on flattened or compressed species. Sequence comparisons confirmed three main lineages of Gracilariaceae: Curdiea/Melanthalia, Gracilariopsis/Gracilariophila, and Gracilaria. The Curdiea/Melanthalia diverged early in the family. Gracilariopsis was paraphyletic, because at least one Gracilariophila species evolved from it. The Atlantic Gracilariopsis were monophyletic and separated from the Pacific lineages. The Gracilaria included all species referable to its own species and to Hydropuntia, which was paraphyletic, formed by distantly related lineages. The new combination Gracilaria pauciramosa (N. Rodríguez Ríos) Bellorin, M. C. Oliveira et E. C. Oliveira is proposed for Polycavernosa pauciramosa N. Rodríguez Ríos. Recognition of subgenera within Gracilaria, based on spermatangial arrangement, was not supported. Instead, infrageneric groups were delineated by geographic origins and combinations of reproductive characters. Most Pacific species with either “textorii” or “verrucosa” type spermatangia were deeply separated from Atlantic species. Within the Atlantic Gracilaria, a lineage encompassing mostly tropical cylindrical species with “henriquesiana” type spermatangia and distinctive cystocarp anatomy was recognized. A lineage was also retrieved for cold water stringy species with verrucosa type spermatangia. Several species from the western Atlantic are closely related to Gracilaria tikvahiae McLachlan with nearly identical morphology. On the other hand, most flattened species from the tropical Atlantic were closely related despite their diverse morphologies. The interpretation of our data in addition to the literature indicates that more populations from the Indo‐Pacific must be studied before a general picture of Gracilariaceae evolution can be framed.     

Retinoic acid synthesis by cytosol from the alcohol dehydrogenase negative deermouse

Cytosolic alcohol dehydrogenase in the deermouse is coded by a single genetic locus and a strain of the deermouse which is alcohol dehydrogenase negative exists. These two strains of the deermouse were used to extend insight into the role of cytosolic alcohol dehydrogenases in the conversion of retinol into retinoic acid. Retinoic acid synthesis from physiological concentrations of retinol (7.5 microM) with cytosol from the alcohol dehydrogenase negative deermouse was 13% (liver), 14% (kidney), 60% (testes), 78% (lung), and 100% (small intestinal mucosa) of that observed with cytosol from the positive deermouse. The rates in the negative strain ranged from 0.3 to 0.7 nmol/h/mg protein: sufficient to fulfill cellular needs for retinoic acid. Ten millimolar 4-methylpyrazole inhibited retinoic acid synthesis 92, 94, 26, and 30% in kidney, liver, lung, and testes of the positive deermouse, respectively, but only 50, 30, 0, and 0% in the same tissues from the negative deermouse. Ethanol (300 mM) did not inhibit retinoic acid synthesis in kidney cytosol from the negative strain. Therefore multiple cytosolic dehydrogenases, including alcohol dehydrogenases, contribute to retinol metabolism in vitro. The only enzyme(s) likely to be physiologically significant to retinoic acid synthesis in vivo, however, is the class of dehydrogenase, distinct from ethanol dehydrogenase, that is common to both the positive and the negative deermouse. This conclusion is supported by the data described above, the kinetics of retinoic acid synthesis and retinal reduction in kidney cytosol from the negative deermouse, and the very existence of the alcohol dehydrogenase negative deermouse. This work also shows that microsomes inhibit the cytosolic conversion of retinol into retinoic acid and that the synthesis of retinal, a retinoid that has no known function outside of the eye, does not reflect the ability or capacity of a sample to synthesize retinoic acid.     

(23S)-1,23,25-Trihydroxycholecalciferol, an intestinal metabolite of 1,25-dihydroxycholecalciferol.

(23S)-23,25-Dihydroxycholecalciferol was converted into a polar metabolite in a calciferol-deficient chick kidney homogenate. The metabolite was identified as (23S)-1,23,25-trihydroxycholecalciferol by absorbance spectroscopy and mass spectrometry, and by formation of derivatives. (23S)-1,23,25-Trihydroxycholecalciferol was also observed as a 1,25-dihydroxycholecalciferol metabolite in intestinal cells isolated from 1,25-dihydroxycholecalciferol-treated rat. The trihydroxy metabolite was 50-fold less potent than 1,25-dihydroxycholecalciferol in the chick intestinal 1,25-dihydroxycholecalciferol receptor assay.     

The action of α-amanitin in vivo on the synthesis and maturation of mouse liver ribonucleic acids

α-Amanitin acts in vitro and in vivo as a selective inhibitor of nucleoplasmic RNA polymerases. Treatment of mice with low doses of α-amanitin causes the following changes in the synthesis, maturation and nucleocytoplasmic transfer of liver RNA species. 1. The synthesis of the nuclear precursor of mRNA is strongly inhibited and all electrophoretic components are randomly affected. The labelling of cytoplasmic mRNA is blocked. These effects may be correlated with the rapid and lasting inhibition of nucleoplasmic RNA polymerase. 2. The synthesis and maturation of the nuclear precursor of rRNA is inhibited within 30min. (a) The initial effect is a strong (about 80%) inhibition of the early steps of 45S precursor rRNA maturation. (b) The synthesis of 45S precursor rRNA is also inhibited and the effect increases from about 30% at 30min to more than 70% at 150min. (c) The labelling of nuclear and cytoplasmic 28S and 18S rRNA is almost completely blocked. The labelling of nuclear 5S rRNA is inhibited by about 50%, but that of cytoplasmic 5S rRNA is blocked. (d) The action of α-amanitin on the synthesis of precursor rRNA cannot be correlated with the slight gradual decrease of nucleolar RNA polymerase activity (only 10–20% inhibition at 150min). (e) The inhibition of precursor rRNA maturation and synthesis precedes the ultrastructural lesions of the nucleolus detected by standard electron microscopy. 3. The synthesis of nuclear 4.6S precursor of tRNA is not affected by α-amanitin. However, the labelling of nuclear and cytoplasmic tRNA is decreased by about 50%, which indicates an inhibition of precursor tRNA maturation. The results of this study suggest that the synthesis and maturation of the precursor of rRNA and the maturation of the precursor of tRNA are under the control of nucleoplasmic gene products. The regulator molecules may be either RNA or proteins with exceedingly fast turnover.