Theoretical model of mitotic spindle microtubule growth for FRAP curve interpretation.

Background: Spindle FRAP curves depend on the kinetic parameters of microtubule polymerization and depolymerization. The empirical FRAP curve proposed earlier permits determination of only one such dynamic parameter, commonly called the "tubulin turnover". The aim of our study was to build a FRAP curve based on an already known kinetic model of microtubule growth.

Accurate measurement of poleward microtubule flux in the spindle of Drosophila S2 cells.

The spindle microtubule (MT) flux is the continuous translocation of MTs toward the spindle poles caused by MT polymerization at plus ends coupled to depolymerization at minus ends. Poleward flux is observed in both mitotic and meiotic spindles; it is evolutionarily conserved and contributes to the regulation of spindle length and anaphase chromosome movement. MT photobleaching is a tool frequently used to measure poleward flux.

Gadd45 expression correlates with age dependent neurodegeneration in Drosophila melanogaster.

The neurodegeneration is one of the features of aging and age-related disorders. Yet, only several antiaging interventions are known to affect the processes of neurodegeneration. Here we show that overexpression of the pro-longevity gene D-GADD45 in Drosophila neurons leads to a postponed manifestation of histological and ultrastructural features of age-dependent neurodegeneration, such as decrease in the packing density of neurons, increasing the degree of neuron cytoplasmic vacuolization, and morphological defects of mitochondrial cristae.

Drosophila splicing factor SF2 knock-down mutant shows altered cell-cycle in vivo.

Pioneering single gene study documents pre-mRNA processing proteins participation in the cell-cycle regulation of multi-cellular animals (Andersen and Tapon, 2008, J Biol Chem 283: 31256-67). Whole-genome RNAi screen in Drosophila tissue-culture cell lines demonstrates that 17 genes involved in RNA-processing are required for G2/M check-point function (Kondo and Perrimon, 2011, Sci Signal 4: rs1). In particular, the silencing of Splicing Factor 2 (SF2) increases the number of G2(M) cells.

The role of Drosophila hyperplastic discs gene in spermatogenesis.

In Drosophila, the ubiquitin ligase Hyd (hyperplastic disc) is required for regulation of cell proliferation during development [Martin et al. (1977) Dev Biol 55, 213-232; Mansfield et al. (1994) Dev Biol 165, 507-526].

Evolutionary origin of the tumor suppressor hyperplastic discs protein.

Previous evolutionary study of the tumor suppressor Merlin revealed that this protein family was produced by very early metazoans with the exception of some or all flatworm lineages [Golovnina et al., 2005]. We ask whether other tumor-suppressor proteins had also been in existence in these times and focus our attention on hyperplastic discs (Hyd) protein, a classic tumor suppressor in Drosophila melanogaster which, when mutated, may cause over-proliferation and malignancy.

Evolution and origin of HRS, a protein interacting with Merlin, the Neurofibromatosis 2 gene product.

Hepatocyte growth factor receptor tyrosine kinase substrate (HRS) is an endosomal protein required for trafficking receptor tyrosine kinases from the early endosome to the lysosome. HRS interacts with Merlin, the Neurofibromatosis 2 (NF2) gene product, and this interaction may be important for Merlin's tumor suppressor activity. Understanding the evolution, origin, and structure of HRS may provide new insight into Merlin function.

Feed-back regulation of successive meiotic cytokinesis.

The paper considers a number of abnormal phenotypes with impaired temporal regulation of cytokinesis during the meiotic division of pollen mother cells. The phenomenon of "non-stop" cytokinesis with blocked arrest of the phragmoplast centrifugal motion and cell plate growth as well as incomplete and premature cytokinesis are described. The obtained data suggested a model for regulation of the processes involved in the arrest of the main cytokinesis processes during its completion in the plant meiosis.

The role of Drosophila Merlin in spermatogenesis.

Background: Drosophila Merlin, the homolog of the human Neurofibromatosis 2 (NF2) gene, is important for the regulation of cell proliferation and receptor endocytosis. Male flies carrying a Mer3 allele, a missense mutation (Met177-->Ile) in the Merlin gene, are viable but sterile; however, the cause of sterility is unknown.

Results: Testis examination reveals that hemizygous Mer3 mutant males have small seminal vesicles that contain only a few immotile sperm.

Model of the reception of hedgehog morphogen concentration gradient: comparison with an extended range of experimental data.

The model for reception of the concentration gradient of the Hedgehog morphogen has been developed. The mechanism of co-operation of the proteins Patched, Smoothened, and Hedgehog is theoretically analyzed in terms of different versions of interactions within this group of proteins. The parametric stability of the modeled system is considered.

Evolution and origin of merlin, the product of the Neurofibromatosis type 2 (NF2) tumor-suppressor gene.

Background: Merlin, the product of the Neurofibromatosis type 2 (NF2) tumor suppressor gene, belongs to the ezrin-radixin-moesin (ERM) subgroup of the protein 4.1 superfamily, which links cell surface glycoproteins to the actin cytoskeleton. While merlin's functional activity has been examined in mammalian and Drosophila models, little is understood about its evolution, diversity, and overall distribution among different taxa.

Role of Jun N-terminal Kinase (JNK) signaling in the wound healing and regeneration of a Drosophila melanogaster wing imaginal disc.

When a fragment of a Drosophila imaginal disc is cultured in growth permissive conditions, it either regenerates the missing structures or duplicates the pattern present in the fragment. This kind of pattern regulation is known to be epimorphic, i.e.

Dynamics of decapentaplegic expression during regeneration of the Drosophila melanogaster wing imaginal disc.

Regeneration of an imaginal disc involves highly ordered proliferation and pattern regulation of the newly formed tissue. Although the general principles of imaginal disc regeneration have been extensively studied, knowledge of the underlying molecular mechanisms is far from complete. Results from other model organisms suggest that regeneration is the result of local recapitulation of the normal patterning genes.