Inferring responses to climate warming from latitudinal pattern of clonal hybridization

Climate warming may affect reproductive isolation between sympatric sister species by modifying reproductive phenology or mate choice. This is expected to result in a latitudinal progression of hybridization in response to the shifting of environmental conditions. The fish species northern redbelly dace (Chrosomus eos) and finescale dace (C. neogaeus) display a wide sympatric distribution in North America. The asexual reproduction of their hybrids allows determining where and when hybridization occurred. The aim of this study was twofold: first, to assess whether temperature affected reproductive isolation, and second, whether the effects of climate warming resulted in a latitudinal progression of hybridization. We performed a 500 km latitudinal survey (51 sites) in southeastern Quebec (Canada) and determined the distribution of clonal hybrid lineages. Results revealed a total of 78 hybrid lineages, including 70 which originated locally. We detected a significant difference between the southern and northern range of the survey in terms of the proportion of sites harboring local hybrids (20/23 vs. 8/28 sites, respectively) and hybrid diversity (57 vs. 13 lineages, respectively). This confirmed that there was more frequent interspecific mating in the warmest sites. In the southern range, diversity of lineages and simulations suggest that hybridization first took place (>7,000 years) in sites characterized by a longer growing season, followed by northerly adjacent sites (ca. 3,500–5,000 years). Moreover, evidence of hybridization occurring in present‐day time was detected. This suggests that the current warming episode is going beyond the limits of the previous warmest period of the Holocene.     

Xanthidae MacLeay, 1838 (Decapoda: Brachyura: Xanthoidea) systematics: A multi-gene approach with support from adult and zoeal morphology

Currently, 13 subfamilies are recognised in the brachyuran family Xanthidae: Actaeinae, Antrocarcininae, Chlorodiellinae, Cymoinae, Etisinae, Euxanthinae, Kraussiinae, Liomerinae, Polydectinae, Speocarcininae, Xanthinae, Zalasiinae and Zosiminae. This classification has been based on shared adult features like a transversely ovate carapace, well defined dorsal carapace regions, usually with lateral dentition, stout chelipeds and relatively short ambulatory legs. Such characters are now considered to be convergent. Consequently a number of higher xanthid taxa may be artifical and not monophyletic. A broad sample of 147 xanthid species representing 75 out of 124 genera from all 13 xanthid subfamilies were sampled in a multi-gene analysis. Four markers (three mitochondrial and one nuclear) were used and yielded a tree with ca. 30 xanthid clades. Monophyletic support was demonstrated for the Antrocarcininae (although substantially redefined), Cymoinae, and Polydectinae. Almost every other subfamily was para- or polyphyletic. Furthermore, the two other families of the Xanthoidea, Pseudorhombilidae and Panopeidae, were found nested within the Xanthidae. The molecular results were consistent with phylogenetic relationships implied by a suite of novel and/or neglected “ventral” adult characters including sternal characters, position of genital openings and morphology of the first zoea, instead of “dorsal” characters traditionally used to infer xanthid relationships.     

Early septic shock induces loss of oxidative phosphorylation yield plasticity in liver mitochondria

We aimed to study the change in mitochondrial oxidative phosphorylation efficiency occurring at the early stage of septic shock in an experimental model. Thirty-six male Wistar rats were divided into two groups. In the first group, a cecal ligation and puncture (CLP) was carried out to induce septic shock for 5 h. The second group includes sham-operated rats and constitutes the control group. Blood gas analysis, alanine amino transferase, and lactic acid dosages were assayed 5 h after surgery. Liver mitochondria were isolated for in vitro functional characterization, including mitochondrial respiratory parameters, oxidative phosphorylation efficiency, oxi-radical production, membrane potential, and cytochrome c oxidase activity and content. Liver interleukin 1β (IL-1β) and tumor necrosis α mRNA levels were determined. Septic shock induced a severe hypotension occurring 180 min after CLP in association with a metabolic acidosis, an increase in plasma alanine amino transferase, liver IL-1β gene expression, and mitochondrial reactive oxygen species production. The rates of mitochondrial oxygen consumption and the activity and content of cytochrome c oxidase were significantly decreased while no alterations in the oxidative phosphorylation efficiency and inner membrane integrity were found. These results show that contrary to what was expected, liver mitochondria felt to adjust their oxidative phosphorylation efficiency in response to the decrease in the mitochondrial oxidative activity induced by CLP. This loss of mitochondrial bioenergetics plasticity might be related to mitochondrial oxidative stress and liver cytokines production.     

Role of connexins and pannexins during ontogeny,regeneration, and pathologies of bone

Electron micrographs revealed the presence of gap junctions in osteoblastic cells over 40 years ago. These intercellular channels formed from connexins are present in bone forming osteoblasts, bone resorbing osteoclasts, and osteocytes (mature osteoblasts embedded in the mineralized bone matrix). More recently, genetic and pharmacologic studies revealed the role of connexins, and in particular Cx43, in the differentiation and function of all bone types. Furthermore, mutations in the gene encoding Cx43 were found to be causally linked to oculodentodigital dysplasia, a condition that results in an abnormal skeleton. Pannexins, molecules with similar structure and single-membrane channel forming potential as connexins when organized as hemichannels, are also expressed in osteoblastic cells. The function of pannexins in bone and cartilage is beginning to be uncovered, but more research is needed to determine the role of pannexins in bone development, adult bone mass and skeletal homeostasis. We describe here the current knowledge on the role of connexins and pannexins on skeletal health and disease.

     

Hydrophylic surfactant–imidazole derivative association studied by RPLC using a hydroorganic solution

A high-performance liquid chromatographic (HPLC) method for an association study of imidazole derivatives in surfactant micellars using a hydrophilic detergent, i.e. Montanox DF 80 was presented. The thermodynamic results obtained showed that imidazole association in the surfactant micelles was effective over a concentration of surfactant equal to approximatively 4·10⁻⁴ mol/l. In addition, an enthalpy–entropy compensation study revealed that the type of interaction between the solute and the RP18 stationary phase was independent of the molecular structure. The thermodynamic variations observed were considered to be the result of equilibrium displacement between the solute and free ethanol (respectively free surfactant) and its clusters (respectively to micelles) created in the mobile phase.     

Phylogeny of eriphioid crabs (Brachyura,Eriphioidea) inferred from molecular and morphological studies

The evolutionary relationships of the brachyuran crab superfamily Eriphioidea, commonly known as stone or rubble crabs, are examined. Analysis of three mitochondrial (12S, 16S and COI) and two nuclear loci (18S and Histone 3) was carried out for 51 taxa representing the Carpilioidea, Dairoidea, Eriphioidea, Goneplacoidea, Parthenopoidea, Pilumnoidea, Portunoidea, Pseudozioidea and Xanthoidea. Phylogenetic analyses of molecular data used three methods of inference that recovered similar topologies with minor differences. Maximum parsimony analysis of 20 morphological characters taken from first zoeas of 11 species yielded two equally parsimonious trees and generally supported the molecular analyses. None of the analyses recovered Eriphioidea as monophyletic, and each of the eriphioid families represented by two or more taxa was shown to be polyphyletic in both molecular and larval analyses. This study indicates that the present classification based on adult morphology is incongruent with phylogenetic relationships and that the diagnostic characters the result of convergence (particularly in feeding morphology) rather than shared ancestry.     

Size and protein content of accessory glands in adult male Caloptilia fraxinella in different physiological states

Reproductive diapause is a strategy employed by some insects to coordinate reproduction with the appropriate environmental conditions for mate location and offspring development. Male Caloptilia fraxinella Ely (Lepidoptera: Gracillariidae) eclose in July in reproductive diapause, and remain unmated until May of the next year, when they emerge from overwintering sites in a reproductively active state. The present study assesses characteristics of male sex accessory glands (SAG) throughout the adult life stage when males are reproductively active and in early and late reproductive diapause. Male SAG are longer and positively correlate with moth body size when males are reproductively active in the spring compared with males in reproductive diapause in the summer and autumn. Male SAG also contain significantly more protein during the period of reproductive activity than during reproductive diapause. Access to a carbohydrate nutrition source does not impact male SAG length or protein concentration when males are reproductively active in the spring. Treatment with a Juvenile Hormone analogue in the autumn, but not the summer, tends to increase the total protein concentration compared with that of untreated control moths.     

The evolution of digit form in Gonatodes (Gekkota: Sphaerodactylidae) and its bearing on the transition from frictional to adhesive contact in gekkotans

Although the phenomenon of adhesion in geckos has been intensively studied for over 200 years, our understanding of how the morphological apparatus associated with this arose is less clear. Indeed, whether or not all of the intricate morphological hierarchy that is implicated in the attachment and removal of the adhesive setae originated at the same time is unknown. To explore whether setae may have arisen prior to the other parts of this structural hierarchy, we undertook morphological observations of Gonatodes, an ancestrally padless, sphaerodatyline genus known to exhibit the expression of incipient subdigital pads in some species. Focusing on this geographically and morphologically well‐circumscribed genus, for which intraspecific relationships are adequately known and ecology is quite well documented, allowed us to deduce trends in digit proportions, shape, scalation, and skeletal structure, and associate these with the micro‐ornamentation of the subdigital surfaces. Our findings indicate that in Gonatodes, setae capable of inducing adhesion are present without the modifications of the digital musculotendinous, circulatory and skeletal systems that are generally considered to be necessary for the operation of a functional adhesive apparatus. The acquisition of these latter characteristics (independently in many lineages of gekkotans, and incipiently so in Anolis) may have been preceded by a suite of modifications of the digits that enhanced static clinging in relation to sit‐and‐wait predation and the ability to take refuge on surfaces unavailable to other taxa. These possibilities await further testing. J. Morphol. 276:1311–1332, 2015. © 2015 Wiley Periodicals, Inc.     

GTPase ROP2 binds and promotes activation of target of rapamycin,TOR, in response to auxin

Target of rapamycin (TOR) promotes reinitiation at upstream ORFs (uORFs) in genes that play important roles in stem cell regulation and organogenesis in plants. Here, we report that the small GTPase ROP2, if activated by the phytohormone auxin, promotes activation of TOR, and thus translation reinitiation of uORF-containing mRNAs. Plants with high levels of active ROP2, including those expressing constitutively active ROP2 (CA-ROP2), contain high levels of active TOR. ROP2 physically interacts with and, when GTP-bound, activates TOR in vitro. TOR activation in response to auxin is abolished in ROP-deficient rop2 rop6 ROP4 RNAi plants. GFP-TOR can associate with endosome-like structures in ROP2-overexpressing plants, indicating that endosomes mediate ROP2 effects on TOR activation. CA-ROP2 is efficient in loading uORF-containing mRNAs onto polysomes and stimulates translation in protoplasts, and both processes are sensitive to TOR inhibitor AZD-8055. TOR inactivation abolishes ROP2 regulation of translation reinitiation, but not its effects on cytoskeleton or intracellular trafficking. These findings imply a mode of translation control whereby, as an upstream effector of TOR, ROP2 coordinates TOR function in translation reinitiation pathways in response to auxin.