Independent specialisation of myosin II paralogues in muscle vs. non-muscle functions during early animal evolution: a ctenophore perspective

ABSTRACT: BACKGROUND: Myosin II (or Myosin Heavy Chain II, MHCII) is a family of molecular motors involved in the contractile activity of animal muscle cells but also in various other cellular processes in non-muscle cells. Previous phylogenetic analyses of bilaterian MHCII genes identified two main clades associated respectively with smooth/non-muscle cells (MHCIIa) and striated muscle cells (MHCIIb). Muscle cells are generally thought to have originated only once in ancient animal history, and decisive insights about their early evolution are expected to come from expression studies of Myosin II genes in the two non-bilaterian phyla that possess muscles, the Cnidaria and Ctenophora. RESULTS: We have uncovered three MHCII paralogues in the ctenophore species Pleurobrachia pileus. Phylogenetic analyses indicate that the MHCIIa / MHCIIb duplication is more ancient than the divergence between extant metazoan lineages. The ctenophore MHCIIa gene (PpiMHCIIa) has an expression pattern akin to that of "stem cell markers" (Piwi, Vasa...) and is expressed in proliferating cells. We identified two MHCIIb genes that originated from a ctenophore-specific duplication. PpiMHCIIb1 represents the exclusively muscular form of myosin II in ctenophore, while PpiMHCIIb2 is expressed in non-muscle cells of various types. In parallel, our phalloidin staining and TEM observations highlight the structural complexity of ctenophore musculature and emphasize the experimental interest of the ctenophore tentacle root, in which myogenesis is spatially ordered and strikingly similar to striated muscle formation in vertebrates. CONCLUSION: MHCIIa expression in putative stem cells/proliferating cells probably represents an ancestral trait, while specific involvement of some MHCIIa genes in smooth muscle fibres is a uniquely derived feature of the vertebrates. That one ctenophore MHCIIb paralogue (PpiMHCIIb2) has retained MHCIIa-like expression features furthermore suggests that muscular expression of the other paralogue, PpiMHCIIb1, was the result of neofunctionalisation within the ctenophore lineage, making independent origin of ctenophore muscle cells a likely option.     

Mimosa pudica,Dionaea muscipula and anesthetics

Some studies showed that anesthetics reduce the response of physical stimuli in Mimosa pudica and in Venus Flytrap (Dionaea muscipula), peculiar plants that have the ability to respond to touch stimuli. In this research we tested the effects of ketamine, lidocaine, diethyl ether, and amlodipine on the movements of Mimosa pudica and Venus Flytrap. With a literature review, we tried to bring elements to theorize about the interaction of these substances with these plants. The angular displacement in Mimosa´s petiole and in Dionaea leaves is what was measured to compare the drugs group with control groups.     

Enantioselective analysis of unbound tramadol, O-desmethyltramadol and N-desmethyltramadol in plasma by ultrafiltration and LC-MS/MS: application to clinical pharmacokinetics

This study describes the enantioselective analysis of unbound and total concentrations of tramadol and its main metabolites O-desmethyltramadol (M1) and N-desmethyltramadol (M2) in human plasma. Sample preparation was preceded by an ultrafiltration step to separate the unbound drug. Both the ultrafiltrate and plasma samples were submitted to liquid/liquid extraction with methyl t-butyl ether. Separation was performed on a Chiralpak(?) AD column and tandem mass spectrometry consisting of an electrospray ionization source, positive ion mode and multiple reaction monitoring was used as the detection system. Linearity was observed in the following ranges: 0.2-600 and 0.5-250 ng/mL for analysis of total and unbound concentrations of the tramadol enantiomers, respectively, and 0.1-300 and 0.25-125 ng/mL for total and unbound concentrations of the M1 and M2 enantiomers, respectively. The lower limits of quantitation were 0.2 and 0.5 ng/mL for analysis of total and unbound concentration of each tramadol enantiomer, respectively, and 0.1 and 0.25 ng/mL for total and unbound concentrations of M1 and M2 enantiomers, respectively. Intra- and interassay reproducibility and inaccuracy did not exceed 15%. Clinical application of the method to patients with neuropathic pain showed plasma accumulation of (+)-tramadol and (+)-M2 after a single oral dose of racemic tramadol. Fractions unbound of tramadol, M1 or M2 were not enantioselective in the patients investigated.     

BCL3 gene role in facial morphology

BACKGROUND: Cleft lip (CL) with or without palate (CLP) and isolated cleft palate (CP) are etiologically complex diseases with interactions among various environmental and genetic factors. The aim of the current study was to identify association with genetic markers and phenotypic craniofacial data in patients with CL/CLP/CP parents. METHODS: Posteroanterior and lateral digital radiographs of the cranium were obtained from 74 parents of patients with CL/CLP/CP. One hundred seventy‐three patients with CL/CLP/CP and 190 controls were enrolled in the study for the association test. Five genetic markers of the IRF6 gene and 14 markers of the 19q13 locus were genotyped. Linear regression analysis was performed for the relationship of cephalometric measurements with genotype data adjusted for age, gender, and cleft type. Chi‐square and transmission disequilibrium tests were performed to evaluate differences in alleles of the BCL3 gene. Positive findings were replicated in an independent sample (n = 95) of patients with CL/CLP/CP parents. RESULTS: Genetic markers of the BCL3 gene at 19q13, rs7257231, and rs1979377 in the familial association test and rs10401176 in the case‐control association test, were associated with craniofacial phenotype. Carriers of BCL3 allele rs7257231T had longer posterior cranial bases than noncarriers (p_adjusted = 0.0028), and in the familial‐based association test showed the statistically strongest relationship (p_adjusted = 0.05) to phenotype. Relation of rs7257231 to facial formation was confirmed in the replication group (p = 0.0024). CONCLUSIONS: The results indicate that BCL3, which has functions related to cell adhesion and whose downregulation can cause disruption of ectodermal development, is likely to be important in facial formation. Birth Defects Research (Part A), 2012. © 2012 Wiley Periodicals, Inc.     

Molecular mapping of soybean rust (Phakopsora pachyrhizi) resistance genes: discovery of a novel locus and alleles

Soybean production in South and North America has recently been threatened by the widespread dissemination of soybean rust (SBR) caused by the fungus Phakopsora pachyrhizi. Currently, chemical spray containing fungicides is the only effective method to control the disease. This strategy increases production costs and exposes the environment to higher levels of fungicides. As a first step towards the development of SBR resistant cultivars, we studied the genetic basis of SBR resistance in five F(2) populations derived from crossing the Brazilian-adapted susceptible cultivar CD 208 to each of five different plant introductions (PI 200487, PI 200526, PI 230970, PI 459025, PI 471904) carrying SBR-resistant genes (Rpp). Molecular mapping of SBR-resistance genes was performed in three of these PIs (PI 459025, PI 200526, PI 471904), and also in two other PIs (PI 200456 and 224270). The strategy mapped two genes present in PI 230970 and PI 459025, the original sources of Rpp2 and Rpp4, to linkage groups (LG) J and G, respectively. A new SBR resistance locus, rpp5 was mapped in the LG-N. Together, the genetic and molecular analysis suggested multiple alleles or closely linked genes that govern SBR resistance in soybean.     

Minimal chemical modification of reductive end of dextran to produce an amphiphilic polysaccharide able to incorporate onto lipid nanocapsules

In order to graft an amphiphilic polysaccharide to lipid nanocapsules, we present here a new method of dextran lipidation. The lipidation strategy is based on the formation of an oxime linkage between the amphiphilic hydroxylamine C16E20ONH2 and the reductive end of a 40 kDa dextran. This chemoselective reaction allows us to control the lipidation site and the number of lipid introduced on the dextran molecule. This new amphiphilic dextran was used to coat the surface of lipid nanocapsules. The coating efficiency was followed by dynamic light scattering and the presence of the polysaccharide was confirmed by (1)H NMR and observed by electronic microscopy.     

Genetic covariation between effectiveness and cost of defence in aphids

Ecological immunology distinguishes between the long-term evolutionary costs of possessing defences against parasites and the short-term costs of using them. Evolutionary biologists have typically focused on the former in the search for constraints on the evolution of resistance. Here, we show in the peach-potato aphid, Myzus persicae, that short-term costs may be of equal evolutionary importance. Survivors of more resistant aphid clones suffered a higher reduction of fecundity upon parasitoid attack than survivors of more susceptible clones. This genetically based trade-off between benefits and costs of defence may limit the evolution of increased resistance and explain the maintenance of genetic variation for resistance under environmental variation in parasitism risk.     

In vivo reshaping the catalytic site of nucleoside 2'-deoxyribosyltransferase for dideoxy- and didehydronucleosides via a single amino acid substitution

Nucleoside 2'-deoxyribosyltransferases catalyze the transfer of 2-deoxyribose between bases and have been widely used as biocatalysts to synthesize a variety of nucleoside analogs. The genes encoding nucleoside 2'-deoxyribosyltransferase (ndt) from Lactobacillus leichmannii and Lactobacillus fermentum underwent random mutagenesis to select variants specialized for the synthesis of 2',3'-dideoxynucleosides. An Escherichia coli strain, auxotrophic for uracil and unable to use 2',3'-dideoxyuridine, cytosine, and 2',3'-dideoxycytidine as a source of uracil was constructed. Randomly mutated lactobacilli ndt libraries from two species, L. leichmannii and L. fermentum, were screened for the production of uracil with 2',3'-dideoxyuridine as a source of uracil. Several mutants suitable for the synthesis of 2',3'-dideoxynucleosides were isolated. The nucleotide sequence of the corresponding genes revealed a single mutation (G --> A transition) leading to the substitution of a small aliphatic amino acid by a nucleophilic one, A15T (L. fermentum) or G9S (L. leichmannii), respectively. We concluded that the "adaptation" of the nucleoside 2'-deoxyribosyltransferase activity to 2,3-dideoxyribosyl transfer requires an additional hydroxyl group on a key amino acid side chain of the protein to overcome the absence of such a group in the corresponding substrate. The evolved proteins also display significantly improved nucleoside 2',3'-didehydro-2',3'-dideoxyribosyltransferase activity.     

Pleiotropy in the melanocortin system, coloration and behavioural syndromes

In vertebrates, melanin-based coloration is often associated with variation in physiological and behavioural traits. We propose that this association stems from pleiotropic effects of the genes regulating the synthesis of brown to black eumelanin. The most important regulators are the melanocortin 1 receptor and its ligands, the melanocortin agonists and the agouti-signalling protein antagonist. On the basis of the physiological and behavioural functions of the melanocortins, we predict five categories of traits correlated with melanin-based coloration. A review of the literature indeed reveals that, as predicted, darker wild vertebrates are more aggressive, sexually active and resistant to stress than lighter individuals. Pleiotropic effects of the melanocortins might thus account for the widespread covariance between melanin-based coloration and other phenotypic traits in vertebrates.