Dcode.org anthology of comparative genomic tools

Comparative genomics provides the means to demarcate functional regions in anonymous DNA sequences. The successful application of this method to identifying novel genes is currently shifting to deciphering the non-coding encryption of gene regulation across genomes. To facilitate the practical application of comparative sequence analysis to genetics and genomics, we have developed several analytical and visualization tools for the analysis of arbitrary sequences and whole genomes. These tools include two alignment tools, zPicture and Mulan; a phylogenetic shadowing tool, eShadow for identifying lineage- and species-specific functional elements; two evolutionary conserved transcription factor analysis tools, rVista and multiTF; a tool for extracting cis-regulatory modules governing the expression of co-regulated genes, Creme 2.0; and a dynamic portal to multiple vertebrate and invertebrate genome alignments, the ECR Browser. Here, we briefly describe each one of these tools and provide specific examples on their practical applications. All the tools are publicly available at the website

A view of evolution by a Christian biologist

This paper, which originated as an address to a gathering of Dutch Reformed Ministers in Potchefstroom, deals with the response of a Christian to concepts of evolution. The paper looks at the concept of “the beginning”, the origin of life , genetics, mutation and natural selection, the origin of diversity or speciation, man as a biological species, the missing link (in which attention is given to various theories), and finally theories of human evolution. These include the neoteny theory, the savannah theory and the aquatic theory. Following a discussion of the various aspects of these theories, the authors go on to a discussion of the evolution of intelligence and culture, and reach the conclusion that “for a Christian, evolution may help him to understand more about God and his love and his work, and also then to have more security in the belief in God”

Effect of age and cytoskeletal elements on the indentation-dependent mechanical properties of chondrocytes.

Articular cartilage chondrocytes are responsible for the synthesis, maintenance, and turnover of the extracellular matrix, metabolic processes that contribute to the mechanical properties of these cells. Here, we systematically evaluated the effect of age and cytoskeletal disruptors on the mechanical properties of chondrocytes as a function of deformation. We quantified the indentation-dependent mechanical properties of chondrocytes isolated from neonatal (1-day), adult (5-year) and geriatric (12-year) bovine knees using atomic force microscopy (AFM). We also measured the contribution of the actin and intermediate filaments to the indentation-dependent mechanical properties of chondrocytes. By integrating AFM with confocal fluorescent microscopy, we monitored cytoskeletal and biomechanical deformation in transgenic cells (GFP-vimentin and mCherry-actin) under compression. We found that the elastic modulus of chondrocytes in all age groups decreased with increased indentation (15-2000 nm). The elastic modulus of adult chondrocytes was significantly greater than neonatal cells at indentations greater than 500 nm. Viscoelastic moduli (instantaneous and equilibrium) were comparable in all age groups examined; however, the intrinsic viscosity was lower in geriatric chondrocytes than neonatal. Disrupting the actin or the intermediate filament structures altered the mechanical properties of chondrocytes by decreasing the elastic modulus and viscoelastic properties, resulting in a dramatic loss of indentation-dependent response with treatment. Actin and vimentin cytoskeletal structures were monitored using confocal fluorescent microscopy in transgenic cells treated with disruptors, and both treatments had a profound disruptive effect on the actin filaments. Here we show that disrupting the structure of intermediate filaments indirectly altered the configuration of the actin cytoskeleton. These findings underscore the importance of the cytoskeletal elements in the overall mechanical response of chondrocytes, indicating that intermediate filament integrity is key to the non-linear elastic properties of chondrocytes. This study improves our understanding of the mechanical properties of articular cartilage at the single cell level

Optimization of a genomic editing system using CRISPR/Cas9-induced site-specific gene integration

The CRISPR-Cas system is an adaptive immune system found in bacteria which helps protect against the invasion of other microorganisms. This system induces double stranded breaks at precise genomic loci (1) in which repairs are initiated and insertions of a target are completed in the process. This mechanism can be used in eukaryotic cells in combination with sgRNAs (1) as a tool for genome editing. By using this CRISPR-Cas system, in addition to the “safe harbor locus,” ROSAβ26, the incorporation of a target gene into a site that is not susceptible to gene silencing effects can be achieved through few simple steps. PCR amplification of the target genes , ROSA26 and mKate2, with a sgRNA scaffold and T7 promoter followed by in vitro transcription aim to produce an RNA product. This sgRNA product can be run through a digestion with Cas9 to validate cleavage of the genomic ROSA DNA template or mKate plasmid. Osteoblast mouse cells are transfected and labeled through partial uptake by the CRISPR mechanism, by cutting in the ROSA loci and repairing with pieces of the fluorescent mKate2 plasmid. These cells were measured via flow cytometry to give a percentage of red cells. This data shows the scaffolding construct created is targeted by the Cas9 endonuclease and through homologous repair the cells will incorporate the mKate2 target gene in vitro in MC3T3 mouse cells

Global Gene Expression Analysis Identifies Age-Related Differences in Knee Joint Transcriptome during the Development of Post-Traumatic Osteoarthritis in Mice.

Aging and injury are two major risk factors for osteoarthritis (OA). Yet, very little is known about how aging and injury interact and contribute to OA pathogenesis. In the present study, we examined age- and injury-related molecular changes in mouse knee joints that could contribute to OA. Using RNA-seq, first we profiled the knee joint transcriptome of 10-week-old, 62-week-old, and 95-week-old mice and found that the expression of several inflammatory-response related genes increased as a result of aging, whereas the expression of several genes involved in cartilage metabolism decreased with age. To determine how aging impacts post-traumatic arthritis (PTOA) development, the right knee joints of 10-week-old and 62-week-old mice were injured using a non-invasive tibial compression injury model and injury-induced structural and molecular changes were assessed. At six-week post-injury, 62-week-old mice displayed significantly more cartilage degeneration and osteophyte formation compared with young mice. Although both age groups elicited similar transcriptional responses to injury, 62-week-old mice had higher activation of inflammatory cytokines than 10-week-old mice, whereas cartilage/bone metabolism genes had higher expression in 10-week-old mice, suggesting that the differential expression of these genes might contribute to the differences in PTOA severity observed between these age groups

Genome-wide de Novo Prediction of Proximal and Distal Tissue-Specific Enhancers

Determining how transcriptional regulatory networks are encoded in the human genome is essential for understanding how cellular processes are directed. Here, we present a novel approach for systematically predicting tissue specific regulatory elements (REs) that blends genome-wide expression profiling, vertebrate genome comparisons, and pattern analysis of transcription factor binding sites. This analysis yields 4,670 candidate REs in the human genome with distinct tissue specificities, the majority of which reside far away from transcription start sites. We identify key transcription factors (TFs) for 34 distinct tissues and demonstrate that tissue-specific gene expression relies on multiple regulatory pathways employing similar, but different cohorts of interacting TFs. The methods and results we describe provide a global view of tissue specific gene regulation in humans, and propose a strategy for deciphering the transcriptional regulatory code in eukaryotes

Methionine Adenosyltransferase 1a (MAT1A) Enhances Cell Survival During Chemotherapy Treatment and is Associated with Drug Resistance in Bladder Cancer PDX Mice.

Bladder cancer is among the top ten most common cancers, with about ~380,000 new cases and ~150,000 deaths per year worldwide. Tumor relapse following chemotherapy treatment has long been a significant challenge towards completely curing cancer. We have utilized a patient-derived bladder cancer xenograft (PDX) platform to characterize molecular mechanisms that contribute to relapse following drug treatment in advanced bladder cancer. Transcriptomic profiling of bladder cancer xenograft tumors by RNA-sequencing analysis, before and after relapse, following a 21-day cisplatin/gemcitabine drug treatment regimen identified methionine adenosyltransferase 1a (MAT1A) as one of the significantly upregulated genes following drug treatment. Survey of patient tumor sections confirmed elevated levels of MAT1A in individuals who received chemotherapy. Overexpression of MAT1A in 5637 bladder cancer cells increased tolerance to gemcitabine and stalled cell proliferation rates, suggesting MAT1A upregulation as a potential mechanism by which bladder cancer cells persist in a quiescent state to evade chemotherapy

SOST Inhibits Prostate Cancer Invasion.

Inhibitors of Wnt signaling have been shown to be involved in prostate cancer (PC) metastasis; however the role of Sclerostin (Sost) has not yet been explored. Here we show that elevated Wnt signaling derived from Sost deficient osteoblasts promotes PC invasion, while rhSOST has an inhibitory effect. In contrast, rhDKK1 promotes PC elongation and filopodia formation, morphological changes characteristic of an invasive phenotype. Furthermore, rhDKK1 was found to activate canonical Wnt signaling in PC3 cells, suggesting that SOST and DKK1 have opposing roles on Wnt signaling in this context. Gene expression analysis of PC3 cells co-cultured with OBs exhibiting varying amounts of Wnt signaling identified CRIM1 as one of the transcripts upregulated under highly invasive conditions. We found CRIM1 overexpression to also promote cell-invasion. These findings suggest that bone-derived Wnt signaling may enhance PC tropism by promoting CRIM1 expression and facilitating cancer cell invasion and adhesion to bone. We concluded that SOST and DKK1 have opposing effects on PC3 cell invasion and that bone-derived Wnt signaling positively contributes to the invasive phenotypes of PC3 cells by activating CRIM1 expression and facilitating PC-OB physical interaction. As such, we investigated the effects of high concentrations of SOST in vivo. We found that PC3-cells overexpressing SOST injected via the tail vein in NSG mice did not readily metastasize, and those injected intrafemorally had significantly reduced osteolysis, suggesting that targeting the molecular bone environment may influence bone metastatic prognosis in clinical settings

Resisting disposability: Survivalist entrepreneurs in South Africa’s informal recycling sector

Waste is an increasing global environmental issue. South Africa’s informal sector plays a crucial role in diverting recyclables from landfills. Despite their indispensable contributions, informal recyclers form part of a societal group that is marginalised, negatively labelled and deemed ‘disposable’ under neoliberal capitalist structures. This article draws on data from interviews held with 21 participants who work in the informal recycling sector in Gqeberha (formerly Port Elizabeth) in South Africa. It investigates the participants’ own perceptions of their societal role, of which four became prominent, namely: (1) cleaners of the environment, (2) providers for dependents, (3) informal environmental educators and (4) community uplifters. We argue that the participants’ positive self-views can be seen as a powerful counter-narrative that challenges harmful prevailing stereotypes, which allows for a more nuanced perception of their lives and labour. Their positive self-perceptions and resourcefulness should not be interpreted as an endorsement of neoliberal capitalism that compels them to actively combat stigmatisation. Instead, their determination to resist negative stereotypes simultaneously underscores the necessity of confronting stigmatisation in society. Transdisciplinary contribution: The parallel themes of agency and autonomy in both informal recycling and entrepreneurship prompt a reconsideration of the conventional entrepreneurial discourse and its applicability to marginalised communities. We recommend that informal recyclers’ accumulated knowledge, skill set and well-being be acknowledged to ensure their dignity and that their labour is valued