Identifying Cis-Regulatory Sequences by Word Profile Similarity

Recognizing regulatory sequences in genomes is a continuing challenge, despite a wealth of available genomic data and a growing number of experimentally validated examples.We discuss here a simple approach to search for regulatory sequences based on the compositional similarity of genomic regions and known cis-regulatory sequences. This method, which is not limited to searching for predefined motifs, recovers sequences known to be under similar regulatory control. The words shared by the recovered sequences often correspond to known binding sites. Furthermore, we show that although local word profile clustering is predictive for the regulatory sequences involved in blastoderm segmentation, local dissimilarity is a more universal feature of known regulatory sequences in Drosophila.Our method leverages sequence motifs within a known regulatory sequence to identify co-regulated sequences without explicitly defining binding sites. We also show that regulatory sequences can be distinguished from surrounding sequences by local sequence dissimilarity, a novel feature in identifying regulatory sequences across a genome. Source code for WPH-finder is available for download at http://rana.lbl.gov/downloads/wph.tar.gz

Drive counts as a method of estimating ungulate density in forests: mission impossible?

Although drive counts are frequently used to estimate the size of deer populations in forests, little is known about how counting methods or the density and social organization of the deer species concerned influence the accuracy of the estimates obtained, and hence their suitability for informing management decisions. As these issues cannot readily be examined for real populations, we conducted a series of ‘virtual experiments’ in a computer simulation model to evaluate the effects of block size, proportion of forest counted, deer density, social aggregation and spatial auto-correlation on the accuracy of drive counts. Simulated populations of red and roe deer were generated on the basis of drive count data obtained from Polish commercial forests. For both deer species, count accuracy increased with increasing density, and decreased as the degree of aggregation, either demographic or spatial, within the population increased. However, the effect of density on accuracy was substantially greater than the effect of aggregation. Although improvements in accuracy could be made by reducing the size of counting blocks for low-density, aggregated populations, these were limited. Increasing the proportion of the forest counted led to greater improvements in accuracy, but the gains were limited compared with the increase in effort required. If it is necessary to estimate the deer population with a high degree of accuracy (e.g. within 10% of the true value), drive counts are likely to be inadequate whatever the deer density. However, if a lower level of accuracy (within 20% or more) is acceptable, our study suggests that at higher deer densities (more than ca. five to seven deer/100 ha) drive counts can provide reliable information on population size

Capacity of the forest hunting grounds on the example of the Kluczbork Forest District

The aim of the study was to determine the abundance of winter food of cervids and the capacity of the Game Breeding Centre 'Krystyna' administered by the Kluczbork Forest District (southern Poland). Research was based on the estimation of shoots available for cervids in winter time. Evaluation of annual increment of biomass was calculated on 160 circular plots, on which occurrence of trees and shrubs species was estimated (tab. 1). We assumed that the cervids cause 20% loss of growth of shoots for forest species and 90% for other species. Among the 4296 examined trees or shrubs we identified 15 deciduous and 4 coniferous species (tab. 2). The estimation of the potential food for cervids showed a significant variation depending on the species. Among the conifers, the largest total weight of shoots was observed for spruce and pine, while among the deciduous species, the largest reserves of shoots were noted for hornbeam, birch, beech and mountain ash (fig. 2). The so called secure resources amounts to approximately 8 t/1000 ha, which accounted for 35% of the total stock of shoots up to 2 m above the ground. The most food was offered by spruce and pine (over 2.5 t/1000 ha), and hornbeam, mountain ash, black cherry, birch, beech and alder buckthorn (fig. 4). Based on the calculated mass of the shoots possible to eat by deer without threat of the economic damage, we calculated capacity of the forest hunting grounds using two variants of the winter (short and long), and three variants of share the shoots in the diet. The obtained capacity amounted to on average from 120 to 144 deer/1000 ha during short winter or from 103 to 123 deer during the long winter. These results point to the urgent need to objectify the existing rules for determining allowable density of deer at the local level

Mitogenomics reveals low variation within a trigeneric complex of black corals from the North Pacific Ocean

A 2013 study revealed that three morphologically distinct antipatharian genera (Dendrobathypathes, Lillipathes, Parantipathes) from the eastern North Pacific (ENP) are genetically indistinguishable using three mitochondrial and four nuclear markers (7,203 bp). To investigate whether this lack of molecular variability extends beyond three mitochondrial genes, we sequenced the complete mitogenome of a single representative within each genus. Dendrobathypathes was the only specimen from the 2013 study containing high molecular weight (HMW) DNA. In terms of geographic proximity to the ENP, the closest Lillipathes and Parantipathes yielding HMW DNA were from the central North Pacific near Hawai'i. Based on cox3-IGR-cox1, Lillipathes and Parantipathes each contained two variable sites and thus were not equivalent substitutes for specimens from the ENP. Nonetheless, variation was extremely low when comparing the mitogenomes, with 32 variable positions across 17,687 bp. Pairwise comparisons revealed 18 (Dendrobathypathes and Parantipathes) and 23 (Lillipathes and Parantipathes;Lillipathes and Dendrobathypathes) variable sites. An ML-based phylogenetic reconstruction using 13 protein-coding genes and two rRNAs revealed that the three North Pacific genera grouped in a clade with Atlantic Dendrobathypathes, while Atlantic Parantipathes spp. formed a sister clade. Previous research hypothesized that hybridization with subsequent introgression was responsible for the lack of variability among genera. Due to uniparental inheritance and lack of recombination, mtDNA cannot identify hybrids; however, finding Pacific Parantipathes grouping with Dendrobathypathes and Lillipathes rather than Atlantic Parantipathes suggests that the trigeneric complex has a unique evolutionary history. If high-resolution nuclear markers support hybridization, it will be important to elucidate the molecular mechanism that maintains three distinct morphological forms occurring in sympatry

Inference of Transcription Factor Regulation Patterns Using Gene Expression Covariation in Natural Populations of Drosophila melanogaster

Gene regulatory networks control the complex programs that drive development. Deciphering the connections between transcription factors (TFs) and target genes is challenging, in part because TFs bind to thousands of places in the genome but control expression through a subset of these binding events. We hypothesize that we can combine natural variation of expression levels and predictions of TF binding sites to identify TF targets. We gather RNA-seq data from 71 genetically distinct F1 Drosophila melanogaster embryos and calculate the correlations between TF and potential target genes' expression levels, which we call "regulatory strength." To separate direct and indirect TF targets, we hypothesize that direct TF targets will have a preponderance of binding sites in their upstream regions. Using 14 TFs active during embryogenesis, we find that 12 TFs showed a significant correlation between their binding strength and regulatory strength on downstream targets, and 10 TFs showed a significant correlation between the number of binding sites and the regulatory effect on target genes. The general roles, e.g. bicoid's role as an activator, and the particular interactions we observed between our TFs, e.g. twist's role as a repressor of sloppy paired and odd paired, generally coincide with the literature

Global Gene Expression Analysis Identifies PDEF Transcriptional Networks Regulating Cell Migration during Cancer Progression

Prostate derived ETS factor (PDEF) is an ETS (epithelial-specific E26 transforming sequence) family member that has been identified as a potential tumor suppressor. In multiple invasive breast cancer cells, PDEF expression inhibits cell migration by preventing the acquisition of directional morphological polarity conferred by changes in cytoskeleton organization. In this study, microarray analysis was used to identify >200 human genes that displayed a common differential expression pattern in three invasive breast cancer cell lines after expression of exogenous PDEF protein. Gene ontology associations and data mining analysis identified focal adhesion, adherens junctions, cell adhesion, and actin cytoskeleton regulation as cell migration-associated interaction pathways significantly impacted by PDEF expression. Validation experiments confirmed the differential expression of four cytoskeleton-associated genes with known functional associations with these pathways: uPA, uPAR, LASP1, and VASP. Significantly, chromatin immunoprecipitation studies identified PDEF as a direct negative regulator of the metastasis-associated gene uPA and phenotypic rescue experiments demonstrate that exogenous urokinase plasminogen activator (uPA) expression can restore the migratory ability of invasive breast cancer cells expressing PDEF. Furthermore, immunofluorescence studies identify the subcellular relocalization of urokinase plasminogen activator receptor (uPAR), LIM and SH3 protein (LASP1), and vasodilator-stimulated protein (VASP) as a possible mechanism accounting for the loss of morphological polarity observed upon PDEF expression