Genomic characterization of a repetitive motif strongly associated with developmental genes in Drosophila

BACKGROUND: Non-coding DNA represents a high proportion of all metazoan genomes. Although an undetermined fraction of this DNA may be considered devoid of any function, it also contains important information residing in specific cis-regulatory sequences. RESULTS: We report a 27 bp motif that is overrepresented within the fly genome. This motif does not show any significant similarity with transposon sequences and is strongly associated with genes involved in development and/or signal transduction. The 27 bp motif is preferentially located within introns, and has a tendency to be present in multiple copies around genes. Furthermore, it is often found embedded in known non-coding regulatory regions. The regulatory network defined by this motif is partially shared in D. pseudoobscura. CONCLUSION: We have identified a 27 bp cis-regulatory sequence widely distributed within the Drosophila genome in association with developmental genes. This motif may be very useful towards the annotation of functional regulatory regions within the Drosophila genome and the construction of regulatory networks of Drosophila development

Biological activities for 'Ficus carica' latex for potential therapeutics in Human Papillomavirus (HPV) related cervical cancers

Abstract Infection caused by high-risk human papillomaviruses (HPVs) are implicated in the aetiology of cervical cancer. Although current methods of treatment for cervical cancer can ablate lesions, preventing metastatic disseminations and excessive tissue injuries still remains a major concern. Hence, development of a safer and more efficient treatment modality is of vital importance. Natural products from plants are one of the principal sources of precursors to lead compounds with direct pharmaceutical application across all disease classes. One of these plants is Ficus carica, whose fruit latex, when applied on HPV-induced skin warts, has shown potential as a possible cure for this virus related lesions. This study explores the in vitro biological activities of fig latex and elucidates its possible mechanisms of action on cervical cancer cell lines CaSki and HeLa positive for HPV type 16 and 18, respectively. Our data shows that fig latex inhibits properties that are associated with HPV-positive cervical cancer transformed cells such as rapid growth and invasion and substantially downregulated the expression of p16 and HPV onco-proteins E6, E7. These findings suggest Ficus carica latex has the potential to be used in the development of therapeutic modalities for the possible treatment, cure and prevention of HPV related cervical cancer

Development of the Bi-Partite Gal4-UAS System in the African Malaria Mosquito, Anopheles gambiae

Functional genetic analysis in Anopheles gambiae would be greatly improved by the development of a binary expression system, which would allow the more rapid and flexible characterisation of genes influencing disease transmission, including those involved in insecticide resistance, parasite interaction, host and mate seeking behaviour. The Gal4-UAS system, widely used in Drosophila melanogaster functional genetics, has been significantly modified to achieve robust application in several different species. Towards this end, previous work generated a series of modified Gal4 constructs that were up to 20 fold more active than the native gene in An. gambiae cells. To examine the Gal4-UAS system in vivo, transgenic An. gambiae driver lines carrying a modified Gal4 gene under the control of the carboxypeptidase promoter, and responder lines carrying UAS regulated luciferase and eYFP reporter genes have been created. Crossing of the Gal4 and UAS lines resulted in progeny that expressed both reporters in the expected midgut specific pattern. Although there was minor variation in reporter gene activity between the different crosses examined, the tissue specific expression pattern was consistent regardless of the genomic location of the transgene cassettes. The results show that the modified Gal4-UAS system can be used to successfully activate expression of transgenes in a robust and tissue specific manner in Anopheles gambiae. The midgut driver and dual reporter responder constructs are the first to be developed and tested successfully in transgenic An. gambiae and provide the basis for further advancement of the system in this and other insect species

Gene expression patterns associated with blood-feeding in the malaria mosquito Anopheles gambiae

BACKGROUND: Blood feeding, or hematophagy, is a behavior exhibited by female mosquitoes required both for reproduction and for transmission of pathogens. We determined the expression patterns of 3,068 ESTs, representing ~2,000 unique gene transcripts using cDNA microarrays in adult female Anopheles gambiae at selected times during the first two days following blood ingestion, at 5 and 30 min during a 40 minute blood meal and at 0, 1, 3, 5, 12, 16, 24 and 48 hours after completion of the blood meal and compared their expression to transcript levels in mosquitoes with access only to a sugar solution. RESULTS: In blood-fed mosquitoes, 413 unique transcripts, approximately 25% of the total, were expressed at least two-fold above or below their levels in the sugar-fed mosquitoes, at one or more time points. These differentially expressed gene products were clustered using k-means clustering into Early Genes, Middle Genes, and Late Genes, containing 144, 130, and 139 unique transcripts, respectively. Several genes from each group were analyzed by quantitative real-time PCR in order to validate the microarray results. CONCLUSION: The expression patterns and annotation of the genes in these three groups (Early, Middle, and Late genes) are discussed in the context of female mosquitoes' physiological responses to blood feeding, including blood digestion, peritrophic matrix formation, egg development, and immunity

A Machine Learning Approach for Identifying Novel Cell Type–Specific Transcriptional Regulators of Myogenesis

Transcriptional enhancers integrate the contributions of multiple classes of transcription factors (TFs) to orchestrate the myriad spatio-temporal gene expression programs that occur during development. A molecular understanding of enhancers with similar activities requires the identification of both their unique and their shared sequence features. To address this problem, we combined phylogenetic profiling with a DNA–based enhancer sequence classifier that analyzes the TF binding sites (TFBSs) governing the transcription of a co-expressed gene set. We first assembled a small number of enhancers that are active in Drosophila melanogaster muscle founder cells (FCs) and other mesodermal cell types. Using phylogenetic profiling, we increased the number of enhancers by incorporating orthologous but divergent sequences from other Drosophila species. Functional assays revealed that the diverged enhancer orthologs were active in largely similar patterns as their D. melanogaster counterparts, although there was extensive evolutionary shuffling of known TFBSs. We then built and trained a classifier using this enhancer set and identified additional related enhancers based on the presence or absence of known and putative TFBSs. Predicted FC enhancers were over-represented in proximity to known FC genes; and many of the TFBSs learned by the classifier were found to be critical for enhancer activity, including POU homeodomain, Myb, Ets, Forkhead, and T-box motifs. Empirical testing also revealed that the T-box TF encoded by org-1 is a previously uncharacterized regulator of muscle cell identity. Finally, we found extensive diversity in the composition of TFBSs within known FC enhancers, suggesting that motif combinatorics plays an essential role in the cellular specificity exhibited by such enhancers. In summary, machine learning combined with evolutionary sequence analysis is useful for recognizing novel TFBSs and for facilitating the identification of cognate TFs that coordinate cell type–specific developmental gene expression patterns

Sequence-specific targeting of MSL complex regulates transcription of the roX RNA genes

In Drosophila, dosage compensation is controlled by the male-specific lethal (MSL) complex consisting of at least five proteins and two noncoding RNAs, roX1 and roX2. The roX RNAs function in targeting MSL complex to the X chromosome, and roX transgenes can nucleate spreading of the MSL complex into flanking chromatin when inserted on an autosome. An MSL-binding site (DHS, DNaseI hypersensitive site) has been identified in each roX gene. Here, we investigate the functions of the DHS using transgenic deletion analyses and reporter assays. We find that MSL interaction with the DHS counteracts constitutive repression at roX1, resulting in male-specific expression of roX1 RNA. Surprisingly, the DHS is not required for initiation of cis spreading of MSL complex, instead local transcription of roX RNAs correlates with extensive spreading