MidExDB: A database of Drosophila CNS midline cell gene expression

Background  

The Drosophila CNS midline cells are an excellent model system to study neuronal and glial development because of their diversity of cell types and the relative ease in identifying and studying the function of midline-expressed genes. In situ hybridization experiments generated a large dataset of midline gene expression patterns. To help synthesize these data and make them available to the scientific community, we developed a web-accessible database.     

Mutations in Smooth Muscle Alpha-Actin (ACTA2) Cause Coronary Artery Disease, Stroke, and Moyamoya Disease, Along with Thoracic Aortic Disease

The vascular smooth muscle cell (SMC)-specific isoform of α-actin (ACTA2) is a major component of the contractile apparatus in SMCs located throughout the arterial system. Heterozygous ACTA2 mutations cause familial thoracic aortic aneurysms and dissections (TAAD), but only half of mutation carriers have aortic disease. Linkage analysis and association studies of individuals in 20 families with ACTA2 mutations indicate that mutation carriers can have a diversity of vascular diseases, including premature onset of coronary artery disease (CAD) and premature ischemic strokes (including Moyamoya disease [MMD]), as well as previously defined TAAD. Sequencing of DNA from patients with nonfamilial TAAD and from premature-onset CAD patients independently identified ACTA2 mutations in these patients and premature onset strokes in family members with ACTA2 mutations. Vascular pathology and analysis of explanted SMCs and myofibroblasts from patients harboring ACTA2 suggested that increased proliferation of SMCs contributed to occlusive diseases. These results indicate that heterozygous ACTA2 mutations predispose patients to a variety of diffuse and diverse vascular diseases, including TAAD, premature CAD, ischemic strokes, and MMD. These data demonstrate that diffuse vascular diseases resulting from either occluded or enlarged arteries can be caused by mutations in a single gene and have direct implications for clinical management and research on familial vascular diseases.     

Database resources of the National Center for Biotechnology Information

In addition to maintaining the GenBank nucleic acid sequence database, the National Center for Biotechnology Information (NCBI) provides data analysis and retrieval resources that operate on the data in GenBank and a variety of other biological data made available through NCBI's Web site. NCBI data retrieval resources include Entrez, PubMed, LocusLink and the Taxonomy Browser. Data analysis resources include BLAST, Electronic PCR, OrfFinder, RefSeq, UniGene, HomoloGene, Database of Single Nucleotide Polymorphisms (dbSNP), Human Genome Sequencing, Human MapViewer, GeneMap'99, Human-Mouse Homology Map, Cancer Chromosome Aberration Project (CCAP), Entrez Genomes, Clusters of Orthologous Groups (COGs) database, Retroviral Genotyping Tools, Cancer Genome Anatomy Project (CGAP), SAGEmap, Gene Expression Omnibus (GEO), Online Mendelian Inheri-tance in Man (OMIM), the Molecular Modeling Database (MMDB) and the Conserved Domain Database (CDD). Augmenting many of the Web applications are custom implementations of the BLAST program optimized to search specialized data sets. All of the resources can be accessed through the NCBI home page at: http://www.ncbi.nlm.nih. gov.     

POLYGONAL ASPECTS OF CELL FACES. I. PENTAGONS AND HEXAGONS AS PREVAILING TYPES

Wheeler , George E. (Brooklyn Coll., Brooklyn, N. Y.) Polygonal aspects of cell faces. I. Pentagons and hexagons as prevailing types. Amer. Jour. Bot. 49(3): 246–252. Illus. 1962.—Different types of cell faces, classified as to polygon type (i.e., number of sides per face), may predominate in different samples of internal cells and of internal tissues; no single face type is exclusively predominant in all tissues. Pentagons usually are the most numerous type in the cell samples reported in the literature, but hexagons exceed them in some samples. Generally, these 2 “compete” for numerical supremacy. Perpetuation of an already-established, face-type dominance was studied, using data from the literature and from original diagrams. Cell-division orientation, i.e., the location and the relative positioning of new cell-division walls, was found to be the prime factor in maintaining the preponderant type. The polygon nature of the new wall is an additional, but less important, factor. Typical division events tend to favor pentagonal faces; but with an increase in cell division “regularity,” hexagons begin to rise in numbers. During the early stages in tissue differentiation, while mitosis is still occurring, one face type may replace another as the predominating type. Such a shift may be associated with the developmental characteristics of that tissue.     

Identification of a line of sheep carrying a putative autosomal gene increasing ovulation rate in sheep that does not appear to interact with mutations in the transforming growth factor beta superfamily

Sheep lines with mutations in single genes that have major effects on ovulation rate have been very useful in gaining a better understanding of pathways important in controlling follicular development and ovulation rate. To date however, all known mutations are in the transforming growth factor beta (TGFB) superfamily. Ovulation rates were measured in 720 progeny of 20 rams that were descendants of a single prolific ewe. Evaluation of ovulation rates of daughters of closely related sires suggests the presence of a segregating major gene Fecundity Davisdale (FECD) that increases ovulation rate between 0.4 and 0.8 in heterozygous daughters. Key features of mutations in genes of the TGFB superfamily pathway, such as synergistic interactions with other family members, infertility in homozygous carriers, and increased responsiveness to exogenous gonadotropins, were not observed in this line; thus, the mutation does not appear to be acting in the TGFB pathway. Hence, there is likely a novel mutation being carried in this line of sheep that alters ovulation rate. Future identification of the causative mutation may provide new insights into regulation of follicular development and ovulation rate.     

The rapid activation of N-Ras by α-thrombin in fibroblasts is mediated by the specific G-protein Gαi2–Gβ1–Gγ5 and occurs in lipid rafts

α-thrombin is a potent mitogen for fibroblasts and initiates a rapid signal transduction pathway leading to the activation of Ras and the stimulation of cell cycle progression. While the signaling events downstream of Ras have been studied in significant detail and appear well conserved across many species and cell types, the precise molecular events beginning with thrombin receptor activation and leading to the activation of Ras are not as well understood. In this study, we examined the immediate events in the rapid response to α-thrombin, in a single cell type, and found that an unexpected degree of specificity exists in the pathway linking α-thrombin to Ras activation. Specifically, although IIC9 cells express all three Ras isoforms, only N-Ras is rapidly activated by α-thrombin. Further, although several Gα subunits associate with PAR1 and are released following stimulation, only Gα_i2 couples to the rapid activation of Ras. Similarly, although IIC9 cells express many Gβ and Gγ subunits, only a subset associates with Gα_i2, and of those, only a single Gβγ dimer, Gβ₁γ₅, participates in the rapid activation of N-Ras. We then hypothesized that co-localization into membrane microdomains called lipid rafts, or caveolae, is at least partially responsible for this degree of specificity. Accordingly, we found that all components localize to lipid rafts and that disruption of caveolae abolishes the rapid activation of N-Ras by α-thrombin. We thus report the molecular elucidation of an extremely specific and rapid signal transduction pathway linking α-thrombin stimulation to the activation of Ras.     

HPV16 Down-Regulates the Insulin-Like Growth Factor Binding Protein 2 to Promote Epithelial Invasion in Organotypic Cultures

Cervical cancer is a multi-stage disease caused by human papillomaviruses (HPV) infection of cervical epithelial cells, but the mechanisms regulating disease progression are not clearly defined. Using 3-dimensional organotypic cultures, we demonstrate that HPV16 E6 and E7 proteins alter the secretome of primary human keratinocytes resulting in local epithelial invasion. Mechanistically, absence of the IGF-binding protein 2 (IGFBP2) caused increases in IGFI/II signalling and through crosstalk with KGF/FGFR2b/AKT, cell invasion. Repression of IGFBP2 is mediated by histone deacetylation at the IGFBP2 promoter and was reversed by treatment with histone deacetylase (HDAC) inhibitors. Our in vitro findings were confirmed in 50 invasive cancers and 79 cervical intra-epithelial neoplastic lesions caused by HPV16 infection, where IGFBP2 levels were reduced with increasing disease severity. In summary, the loss of IGFBP2 is associated with progression of premalignant disease, and sensitises cells to pro-invasive IGF signalling, and together with stromal derived factors promotes epithelial invasion.     

Toxicity of sewage-contaminated sediment cores to Macrocystis pyrifera (Laminariales,Phaeophyta) gametophytes determined by digital image analysis

Macrocystis pyrifera gametophytes were exposed in batch culture to varying mass concentrations of buried, sewage-contaminated, historically discharged sediment that had been sampled from two sites off Palos Verdes Peninsula, California. Significant gametophytic vegetative growth inhibition was detected in six days, using digital image analysis at sediment loadings ranging from 0.15 to 14.5 g in 500 mL nutrient-enriched seawater. Inhibition declined at low sediment loadings and increased at high loadings as cultures aged. Sediments corresponding to the historic emissions peak taken 2 km from the Joint Water Pollution Control Plant outfall inhibited vegetative growth more than did sediments sampled 13 km distant. Analysis showed elevated aqueous Cd(II), Cr(II) and p,p-DDE concentrations in high sediment-loading culture medium. Inhibition by Zn(II) alone was observed at similar concentrations in other experiments, but synergism or antagonism by other toxicants remains possible.     

EVIDENCE OF AN ORGANIC MATRIX FROM DIATOM BIOSILICA1

Most biominerals appear to be composites of organic material and mineral. Whether biosilica is such a composite is unresolved because of a lack of evidence for such organic components. We present evidence that organic material exists within diatom biosilica and can be extracted using HF/NH₄F solutions from frustules isolated from Cyclotella meneghiniana Kütz and diatomaceous earth. To eliminate organic casing on the silicified frustules as a source of organic materials, the casing was removed by oxidation of frustules with NaOCl before extraction. The removal of the casing was confirmed in that oxidized frustules no longer displayed the ability to be stained with ruthenium red and fluorescamine. Frustules examined with EDXA showed an emission peak from sulfur before treatment but no peak following treatment, indicating that oxidation removed organic sulfur. The organic material obtained from extracts of fresh frustules contained both soluble and insoluble components. Only soluble material was evident in extracts from diatomaceous earth. The soluble material appears to contain glycoproteins with relatively high levels of serine and glycine. The soluble proteins from fresh frustules also appear to be phosphorylated. Indirect evidence is presented that suggests the soluble proteins may contain regions of primary structure enriched in anionic amino acids. The soluble extracts differ from general cell contents when the two fractions are compared, suggesting that frustules contain specialized organic material. The identification of silica-specific organic material suggests that mineralization in diatoms may be in part matrix-mediated.     

The use of deslorelin implants for the synchronization of estrous in diestrous bitches

A novel approach to estrous induction in diestrous bitches is described. Twelve spontaneously cycling anestrous bitches served as controls. Thirteen anestrous and 15 diestrous bitches were induced to come into synchronous estrous using prostaglandin (diestrous bitches only) and deslorelin implants (Ovuplant). Implants contained either 2.1 or 1.05 mg deslorelin and were administered beneath the vestibular submucosa. All treated bitches came into estrous, regardless of implant size. Whereas all anestrous bitches ovulated, one of six diestrous bitches treated with the larger implant and three of nine treated with the smaller implant failed to ovulate. Induced bitches generally produced fewer corpora lutea than controls. Sixty-seven percent of control bitches became pregnant, with 0.63 fetuses per corpus luteum, whereas the pregnancy rate and fetuses per corpus luteum were 67 and 70% and 0.42 and 0.55 in the anestrous bitches induced with 1.05 and 2.1 mg deslorelin implants, respectively (not different from controls). Only 2 of 15 induced diestrous bitches conceived a detectable pregnancy, one of which was resorbed. In conclusion, although ovulatory estrous can be induced in bitches that had their most recent ovulation 40-100 days ago, these bitches are very unlikely to become pregnant during the induced estrous. The reason for the poor fertility in these diestrous bitches requires further study.