Browsing by Issue Date, starting with "2009-02"
Now showing 1 - 6 of 6
Results Per Page
Sort Options
- A Gene-Based Linkage Map for Bicyclus anynana Butterflies Allows for a Comprehensive Analysis of Synteny with the Lepidopteran Reference GenomePublication . Beldade, P.; Saenko, SV.; Pul, N.; Long, AD.Lepidopterans (butterflies and moths) are a rich and diverse order of insects, which, despite their economic impact and unusual biological properties, are relatively underrepresented in terms of genomic resources.We focus on Bicyclus anynana butterflies, a laboratory system for studying the diversification of novelties and serially repeated traits. With a panel of 12 small families and a biphasic mapping approach, we first assigned 508 expressed genes to segregation groups and then ordered 297 of them within individual linkage groups. We also coarsely mapped seven color pattern loci.
- Experimental evolution reveals natural selection on standing genetic variationPublication . Teotónio, H; Chelo, IM; Bradic, M; Rose, MR; Long, ADEvolution depends on genetic variation generated by mutation or recombination from standing genetic variation. In sexual organisms, little is known about the molecular population genetics of adaptation and reverse evolution(1-11). We carry out 50 generations of experimental reverse evolution in populations of Drosophila melanogaster, previously differentiated by forward evolution, and follow changes in the frequency of SNPs in both arms of the third chromosome. We characterize the effects of sampling finite population sizes and natural selection at the genotype level. We demonstrate that selection has occurred at several loci and further that there is no general loss or gain of allele diversity. We also observe that despite the complete convergence to ancestral levels of adaptation, allele frequencies only show partial return.
- Neural representation of behavioral outcomes in the orbitofrontal cortexPublication . Mainen, ZF; Kepecs, AThe orbitofrontal cortex (OFC) is important in processing rewards and other behavioral outcomes. Here, we review from a computational perspective recent progress in understanding this complex function. OFC neurons appear to represent abstract outcome values, which may facilitate the comparison of options, as well as concrete outcome attributes, such as flavor or location, which may enable predictive cues to access current outcome values in the face of dynamic modulation by internal state, context and learning. OFC can use reinforcement learning to generate outcome predictions; it can also generate outcome predictions using other mechanisms, including the evaluation of decision confidence or uncertainty. OFC neurons encode not only the mean expected outcome but also the variance, consistent with the idea that OFC uses a probabilistic population code to represent outcomes. We suggest that further attention to the nature of its representations and algorithms will be critical to further elucidating OFC function.
- Microsatellite markers associated with genes expressed in developing wings of Bicyclus anynana butterfliesPublication . Beldade, P.; Van´T Hof, Arje`n E.; Jerónimo, MA.; Long, AD.Deriving useful microsatellite markers in lepidopterans has been challenging when relying on scans of genomic DNA libraries, presumably due to repetitiveness in their genomes. We assayed 96 of 320 microsatellites identified in silico from a collection of Bicyclus anynana ESTs, in 11 independent individuals from a laboratory population.From the 68 successful assays, we identified 40 polymorphic markers including 22 with BLAST-based annotation. Nine of 12 selected polymorphic markers tested in a panel of 24 wild-caught individuals converted to successful assays and were all polymorphic. We discuss how microsatellite discovery in ESTs is an efficient strategy with important attendant advantages.
- Development and evolution of insect pigmentation: Genetic mechanisms and the potential consequences of pleiotropyPublication . Wittkopp, PJ.; Beldade, P.Insect pigmentation is a premier model system in evolutionary and developmental biology. It has been at the heart of classical studies as well as recent breakthroughs. In insects, pigments are produced by epidermal cells through a developmental process that includes pigment patterning and synthesis. Many aspects of this process also impact other phenotypes, including behavior and immunity.
- Epigenetic reprogramming and small RNA silencing of transposable elements in pollenPublication . Slotkin, R.K.; Vaughn, M.; Borges, F.; Tanurdzic, M.; Becker, J.D.; Feijó, J.A.; Martienssen, R.The mutagenic activity of transposable elements (TEs) is suppressed by epigenetic silencing and small interfering RNAs (siRNAs), especially in gametes that could transmit transposed elements to the next generation. In pollen from the model plant Arabidopsis, we show that TEs are unexpectedly reactivated and transpose, but only in the pollen vegetative nucleus, which accompanies the sperm cells but does not provide DNA to the fertilized zygote. TE expression coincides with downregulation of the heterochromatin remodeler decrease in DNA methylation 1 and of many TE siRNAs. However, 21 nucleotide siRNAs from Athila retrotransposons are generated and accumulate in pollen and sperm, suggesting that siRNA from TEs activated in the vegetative nucleus can target silencing in gametes. We propose a conserved role for reprogramming in germline companion cells, such as nurse cells in insects and vegetative nuclei in plants, to reveal intact TEs in the genome and regulate their activity in gametes