The end-of-day far-red irradiation increases gibberellin A1 content in cowpea (Vigna sinensis) epicotyls by reducing its inactivation

It has been shown previously that gibberellins (GAs) mediate the phytochrome (Phy) control of cowpea ( Vigna sinensis L.) epicotyl elongation induced by end-of-day (EOD)-far-red light (FR). In the present work, the EOD-FR effect on GA metabolism and GA levels in cowpea has been investigated. GA₁, GA₈, GA₁₉ and GA₂₀ were identified in epicotyls, and GA₁, GA₁₉, GA₂₀ and GA₂₉-catabolite in leaves of 6-day-old cowpea seedlings. The content of GA₁ in the epicotyl paralleled the decrease of its growth rate, supporting the hypothesis that this is the GA bioactive in controlling cowpea epicotyl elongation. FR enhanced both the amount of [3H]GA₁ in the epicotyl produced from applied [3H]GA₂₀, and that of applied [3H]GA₁ that remained unmetabolized in epicotyl explants, suggesting that Phy may regulate the inactivation of GA₁. In agreement with this effect of light on GA₁ metabolism, the contents of GA₁ in the epicotyl remained higher in FR-treated than in R-treated explants. Moreover, in intact seedlings EOD-FR treatment increased both epicotyl elongation and GA₁ content in the responsive epicotyl, whereas it was not altered in the leaves. These results show, for the first time, that photostable Phys modulate the stem elongation in light-grown plants by locally controlling the GA₁ levels through regulation of its inactivation.     

Chemiluminescence of the Fenton reaction and a dihydroxybenzene-driven Fenton reaction

A dihydroxybenzenes(DHB)-driven Fenton reaction was found to be more efficient than a simple Fenton reaction based on OH radical and activated species production. The reason for this enhanced reactivity by [Fe DHB] complexes is not well understood, but results suggest that it may be explained by the formation of oxidation species different from those formed during the classic Fenton reactions. In previous work, greater concentrations, and more sustained production of OH over time were observed in DHB driven Fenton reactions versus neat Fenton and Fenton-like reactions. In this work, chemiluminescence (CL) was monitored, and compared to OH production kinetics. The CL of the DHB-driven Fenton reaction was shorter than that for sustained production of OH. CL appears to have been caused by excited Fe(IV) species stabilized by the DHB ligands initially formed in the reaction. Formation of this species would have to have occurred by the reaction between OH and Fe(III) in a DHB complex.     

Spider assemblages in the overstory, understory, and ground layers of managed stands in the western boreal mixedwood forest of Canada

Logging is the main human disturbance in the boreal forest; thus, understanding the effects of harvesting practices on biodiversity is essential for a more sustainable forestry. To assess changes in spider composition because of harvesting, samples were collected from three forest layers (overstory, understory, and ground) of deciduous and conifer dominated stands in the northwestern Canadian boreal mixedwood forest. Spider assemblages and feeding guild composition were compared between uncut controls and stands harvested to 20% retention. In total, 143 spider species were collected, 74 from the ground, 60 from the understory, and 71 from the overstory, and species composition of these three pools differed considerably among layers. Distinctive spider assemblages were collected from the canopy of each forest cover type but these were only slightly affected by harvesting. However, logging had a greater impact on the species composition in the understory and ground layers when compared with unharvested controls. Guild structure differed among layers, with wandering and sheet-weaving spiders dominant on the ground while orb-weaving and ambush spiders were better represented in the understory and overstory, respectively. Given the ecological importance of spiders and the expectation of faunal changes with increased harvesting, further efforts toward the understanding of species composition in higher strata of the boreal forest are needed.     

New Application of the Comet Assay: Chromosome�CComet Assay

The comet assay is a well-established, simple, versatile, visual, rapid, and sensitive tool used extensively to assess DNA damage and DNA repair quantitatively and qualitatively in single cells. The comet assay is most frequently used to analyze white blood cells or lymphocytes in human biomonitoring studies, although other cell types have been examined, including buccal, nasal, epithelial, and placental cells and even spermatozoa. This study was conducted to design a protocol that can be used to generate comets in subnuclear units, such as chromosomes. The new technique is based on the chromosome isolation protocols currently used for whole chromosome mounting in electron microscopy, coupled to the alkaline variant of the comet assay, to detect DNA damage. The results show that migrant DNA fragments can be visualized in whole nuclei and isolated chromosomes and that they exhibit patterns of DNA migration that depend on the level of DNA damage produced. This protocol has great potential for the highly reproducible study of DNA damage and repair in specific chromosomal domains.     

The transmembrane domain of podoplanin is required for its association with lipid rafts and the induction of epithelial-mesenchymal transition

Podoplanin is a transmembrane glycoprotein that is upregulated in cancer and was reported to induce an epithelial-mesenchymal transition (EMT) in MDCK cells. The promotion of EMT was dependent on podoplanin binding to ERM (ezrin, radixin, moesin) proteins through its cytoplasmic (CT) domain, which led to RhoA-associated kinase (ROCK)-dependent ERM phosphorylation. Using detergent-resistant membrane (DRM) assays, as well as transmembrane (TM) interactions and ganglioside GM1 binding, we present evidence supporting the localization of podoplanin in raft platforms important for cell signalling. Podoplanin mutant constructs harbouring a heterologous TM region or lacking the CT tail were unable to associate with DRMs, stimulate ERM phosphorylation and promote EMT or cell migration. Similar effects were observed upon disruption of a GXXXG motif within the TM domain, which is involved in podoplanin self-assembly. In contrast, deletion of the extracellular (EC) domain did not affect podoplanin DRM association. Together, these data suggest that both the CT and TM domains are required for podoplanin localization in raft platforms, and that this association appears to be necessary for podoplanin-mediated EMT and cell migration.     

Ontogenetic variation in the plumage colour of female European Pied Flycatchers Ficedula hypoleuca

Although variation in the dorsal plumage colour of male European Pied Flycatchers Ficedula hypoleuca has received a great deal of attention, females of the species have been usually considered to be nearly uniformly monochromatic brown. Using reflectance spectrophotometry, we explore the age‐dependent variation of plumage colour in females. We disentangle the within‐ and between‐individual effects of this pattern and show a within‐individual darkening of the mantle colour with age, whereas differences between individuals in structural colour expression may underlie the trend for a more reflective white in the females' breast plumage with advancing age. The darkening of the dorsal plumage as females age reflects the most common pattern of age‐related variation in males in most European populations of the species.     

The Effects of Chilling on the Fecundity and Life Span of Mass-reared Parasitoids (Hymenoptera: Braconidae) of the Mediterranean Fruit Fly, Ceratitis capitata (Wiedemann) (Diptera: Tephritidae)

Suppression of Mediterranean fruit fly (medfly), Ceratitis capitata (Wiedemann), populations may be achieved through the mass-rearing and augmentative aerial release of opiine braconid parasitoids. Typically, aerial release techniques require up to one hour of chilling of adult parasitoids at temperatures as low as 3.5°C prior to their dissemination. Such chilling potentially could affect the subsequent performance of the insects. Among three species of the genus Diachasmimorpha longicaudata (Ashmead), tryoni (Cameron), and krausii (Fullaway) there was little or no affect of chilling in the laboratory on female longevity, production of daughters, or offspring sex ratio. This is consistent with previous experiments that found chilling to have no discernable effect on the short-term mortality of D. tryoni or on its ability to take flight immediately after aerial release. While there was little effect of chilling on longevity and fecundity in a species from another opiine genus, Fopius arisanus (Sonan), exposure to low temperatures did result in a significantly more male-biased offspring sex ratio.