The tubby family proteins

The tubby mouse shows a tripartite syndrome characterized by maturity-onset obesity, blindness and deafness. The causative gene Tub is the founding member of a family of related proteins present throughout the animal and plant kingdoms, each characterized by a signature carboxy-terminal tubby domain. This domain consists of a β barrel enclosing a central α helix and binds selectively to specific membrane phosphoinositides. The vertebrate family of tubby-like proteins (TULPs) includes the founding member TUB and the related TULPs, TULP1 to TULP4. Tulp1 is expressed in the retina and mutations in TULP1 cause retinitis pigmentosa in humans; Tulp3 is expressed ubiquitously in the mouse embryo and is important in sonic hedgehog (Shh)-mediated dorso-ventral patterning of the spinal cord. The amino terminus of these proteins is diverse and directs distinct functions. In the best-characterized example, the TULP3 amino terminus binds to the IFT-A complex, a complex important in intraflagellar transport in the primary cilia, through a short conserved domain. Thus, the tubby family proteins seem to serve as bipartite bridges through their phosphoinositide-binding tubby and unique amino-terminal functional domains, coordinating multiple signaling pathways, including ciliary G-protein-coupled receptor trafficking and Shh signaling. Molecular studies on this functionally diverse protein family are beginning to provide us with remarkable insights into the tubby-mouse syndrome and other related diseases

Wagging the Dogma Tissue-Specific Cell Cycle Control in the Mouse Embryo

AbstractThe family of cyclin-dependent kinases (Cdks) lies at the core of the machinery that drives the cell division cycle. Studies in cultured mammalian cells have provided insight into the cellular functions of many Cdks. Recent Cdk and cyclin knockouts in the mouse show that the functions of G1 cell cycle regulatory genes are often essential only in specific cell types, pointing to our limited understanding of tissue-specific expression, redundancy, and compensating mechanisms in the Cdk network

The COOH terminus of the c-Abl tyrosine kinase contains distinct F- and G-actin binding domains with bundling activity

The myristoylated form of c-Abl protein, as well as the P210bcr/abl protein, have been shown by indirect immunofluorescence to associate with F-actin stress fibers in fibroblasts. Analysis of deletion mutants of c-Abl stably expressed in fibroblasts maps the domain responsible for this interaction to the extreme COOH-terminus of Abl. This domain mediates the association of a heterologous protein with F-actin filaments after microinjection into NIH 3T3 cells, and directly binds to F-actin in a cosedimentation assay. Microinjection and cosedimentation assays localize the actin-binding domain to a 58 amino acid region, including a charged motif at the extreme COOH-terminus that is important for efficient binding. F-actin binding by Abl is calcium independent, and Abl competes with gelsolin for binding to F- actin. In addition to the F-actin binding domain, the COOH-terminus of Abl contains a proline-rich region that mediates binding and sequestration of G-actin, and the Abl F- and G-actin binding domains cooperate to bundle F-actin filaments in vitro. The COOH terminus of Abl thus confers several novel localizing functions upon the protein, including actin binding, nuclear localization, and DNA binding. Abl may modify and receive signals from the F-actin cytoskeleton in vivo, and is an ideal candidate to mediate signal transduction from the cell surface and cytoskeleton to the nucleus

A Timelapse Camera Dataset and Markov Model of Dust Devil Activity at Eldorado Playa, Nevada, USA

We report a May-June 2015 survey of dust devil activity on a Nevada desert playa using an inexpensive digital timelapse camera. We discuss techniques for exploiting the large volume of data (∼32,700 images, made publicly-available) generated in these observations, similar to imaging from Mars landers and rovers, noting the diurnal image filesize variations as a useful quick-look metric of weather conditions. We present results from a semi-automated image classification: this classification is available to other workers, for example for benchmarking automated procedures. The acquisition of images at 1/min for some 36 days permits study of the diurnal variation of dust devil activity (e.g. 85% of the dust devil images [i.e. those images manually classified as showing dust devils] occur between 12:00 and 17:00; during the period of peak activity 13:00–15:00 about 7% of images contain well-defined dust devils of several meters diameter or larger). The data also permit the dependence of dust devil characteristics on ambient conditions. We construct a simple two-state Markov model for the occurrence and persistence of dust devils (a few per cent chance that new dust devil activity appears in the next image; and a ∼45% chance that activity stops) which may help inform strategies for acquiring and interpreting field observations

Xenopus Cdc14α/β are localized to the nucleolus and centrosome and are required for embryonic cell division

BACKGROUND: The dual specificity phosphatase Cdc14 has been shown to be a critical regulator of late mitotic events in several eukaryotes, including S. cerevisiae, S. pombe. C. elegans and H. sapiens. However, Cdc14 homologs have clearly evolved to regulate distinct cellular processes and to respond to regulatory signals important for these processes. The human paralogs hCdc14A and B are the only vertebrate Cdc14 homologues studied to date, but their functions are not well understood. Therefore, it is of great interest to examine the function Cdc14 homologs in other vertebrate species. RESULTS: We identified two open reading frames from Xenopus laevis closely related to human Cdc14A, called XCdc14α and XCdc14β, although no obvious paralog of the hCdc14B was found. To begin a functional characterization of Xcdc14α and XCdc14β, we raised polyclonal antibodies against a conserved region. These antibodies stained both the nucleolus and centrosome in interphase Xenopus tissue culture cells, and the mitotic centrosomes. GFP-tagged version of XCdc14α localized to the nucleulus and GFP-XCdc14β localized to the centrosome, although not exclusively. XCdc14α was also both meiotically and mitotically phosphorylated. Injection of antibodies raised against a conserved region of XCdc14/β into Xenopus embryos at the two-cell stage blocked division of the injected blastomeres, suggesting that activities of XCdc14α/β are required for normal cell division. CONCLUSION: These results provide evidence that XCdc14α/β are required for normal cellular division and are regulated by at least two mechanisms, subcellular localization and possibly phosphorylation. Due to the high sequence conservation between Xcdc14α and hCdc14A, it seems likely that both mechanisms will contribute to regulation of Cdc14 homologs in vertebrates

The effects of poverty reduction strategies on artisanal fishing in Ghana: The case of Keta municipality

This paper assesses the level of poverty in Ghana after three decades of successive implementation of numerous poverty reduction strategies including Structural Adjustment Program (SAP) by various governments of Ghana. The Keta municipality in the Volta region, where artisanal fishing thrives, was chosen as a representative sample of the whole country. The authors identified eleven artisanal fishing communities in the selected area using systematic sampling. Data were collected on household consumption patterns. This process was used to determine the profile of poverty using the latest upper poverty line of Ghana and the Greer and Thorbecke (1984) poverty formula. Research findings show that the various poverty alleviation methods implemented over three decades by the Government of Ghana, the World Bank, and the International Monetary Fund (IMF) significantly failed as they have not produced any meaningful effect on poverty reduction in the sample area. Finally, this paper offers further suggestions regarding how this poverty gap may be bridged using alternative methods