513 research outputs found
A dual function of Drosophila capping protein on DE-cadherin maintains epithelial integrity and prevents JNK-mediated apoptosis
E-cadherin plays a pivotal role in epithelial cell polarity, cell signalling and tumour suppression. However, how E-cadherin dysfunction promotes tumour progression is poorly understood. Here we show that the actin-capping protein heterodimer, which regulates actin filament polymerization, has a dual function on DE-cadherin in restricted Drosophila epithelia. Knocking down capping protein in the distal wing disc epithelium disrupts DE-cadherin and Armadillo localization at adherens junctions and upregulates DE-cadherin transcription. In turn, DE-cadherin provides an active signal, which prevents Wingless signalling and promotes JNK-mediated apoptosis. However, when cells are kept alive with the Caspase inhibitor P35, the activity of the JNK pathway and of the Yorkie oncogene trigger massive proliferation of cells that fail to stably retain associations with their neighbours. Moreover, loss of capping protein cooperates with the Ras oncogene to induce massive tissue overgrowth. Taken together, our findings argue that in some epithelia, the dual effect of capping protein loss on DE-cadherin triggers the elimination of mutant cells, preventing them from proliferating. However, the appearance of a second mutation that blocks cell death may allow for the development of some epithelial tumour
Characterization of Coffee ringspot virus-Lavras: A model for an emerging threat to coffee production and quality
AbstractThe emergence of viruses in Coffee (Coffea arabica and Coffea canephora), the most widely traded agricultural commodity in the world, is of critical concern. The RNA1 (6552nt) of Coffee ringspot virus is organized into five open reading frames (ORFs) capable of encoding the viral nucleocapsid (ORF1p), phosphoprotein (ORF2p), putative cell-to-cell movement protein (ORF3p), matrix protein (ORF4p) and glycoprotein (ORF5p). Each ORF is separated by a conserved intergenic junction. RNA2 (5945nt), which completes the bipartite genome, encodes a single protein (ORF6p) with homology to RNA-dependent RNA polymerases. Phylogenetic analysis of L protein sequences firmly establishes CoRSV as a member of the recently proposed Dichorhavirus genus. Predictive algorithms, in planta protein expression, and a yeast-based nuclear import assay were used to determine the nucleophillic character of five CoRSV proteins. Finally, the temperature-dependent ability of CoRSV to establish systemic infections in an initially local lesion host was quantified
Reproduction of the blue jack mackerel, Trachurus picturatus, in western Portugal: microscopic gonad analysis reveals indeterminate fecundity and skipped spawning patterns
Blue jack mackerel, Trachurus picturatus, is the fifth most landed fish species in mainland Portugal, but
information on its reproductive biology is scarce. From September 2018 to August 2019, 626 specimens
were collected from commercial vessels to clarify the reproductive strategy of the T. picturatus population
off the west coast of Portugal. The proportion and length range of males and females were similar. Only
three of the specimens collected were categorized as immature, indicating that the fish caught in the
fishery are primarily mature. The spawning season lasted from late January until the end of March, with
gonadosomatic indices being similar for males and females. Fecundity was indeterminate, and estimated
batch fecundity ranged between 6,798 (at 25.4 cm TL) and 302,358 oocytes (at 33.8 cm TL). The low
number of females showing direct evidence of imminent or recent spawning suggests a low number
of spawning events. In addition, 12.7% of females were considered non-reproductive due to ovary
abnormalities including parasitic infection by Kudoa species, atretic structures and skipped spawning
events. This study highlights the importance of accounting for skipped spawning events and ovary
abnormalities in the management of species fisheries.info:eu-repo/semantics/publishedVersio
Spectrum of genetic diversity and networks of clonal organisms
Clonal organisms present a particular challenge in population genetics
because, in addition to the possible existence of replicates of the same
genotype in a given sample, some of the hypotheses and concepts underlying
classical population genetics models are irreconcilable with clonality. The
genetic structure and diversity of clonal populations was examined using a
combination of new tools to analyze microsatellite data in the marine
angiosperm Posidonia oceanica. These tools were based on examination of the
frequency distribution of the genetic distance among ramets, termed the
spectrum of genetic diversity (GDS), and of networks built on the basis of
pairwise genetic distances among genets. The properties and topology of
networks based on genetic distances showed a "small-world" topology,
characterized by a high degree of connectivity among nodes, and a substantial
amount of substructure, revealing organization in sub-families of closely
related individuals.
Keywords: genetic networks; small-world networks; genetic diversity; clonal
organismsComment: Replaced with revised versio
Modeling Rett Syndrome With Human Patient-Specific Forebrain Organoids
Engineering brain organoids from human induced pluripotent stem cells (hiPSCs) is a
powerful tool for modeling brain development and neurological disorders. Rett syndrome
(RTT), a rare neurodevelopmental disorder, can greatly benefit from this technology,
since it affects multiple neuronal subtypes in forebrain sub-regions. We have established
dorsal and ventral forebrain organoids from control and RTT patient-specific hiPSCs
recapitulating 3D organization and functional network complexity. Our data revealed
a premature development of the deep-cortical layer, associated to the formation of
TBR1 and CTIP2 neurons, and a lower expression of neural progenitor/proliferative
cells in female RTT dorsal organoids. Moreover, calcium imaging and electrophysiology
analysis demonstrated functional defects of RTT neurons. Additionally, assembly of
RTT dorsal and ventral organoids revealed impairments of interneuron’s migration.
Overall, our models provide a better understanding of RTT during early stages of
neural development, demonstrating a great potential for personalized diagnosis and
drug screening
- …