Cell Division In Drosophila Research Articles

Light, flies and cell division. Workshop: regulation of cell division in Drosophila.

A meeting on the regulation of cell division in Drosophila took place in Cortona. Italy, June 10–15, 2000. This is the second of a series that started in 1995 in Loch Ranoch. Scotland, UK. This meeting was organized by Maurizio Gatti (Rome, Italy) as an EMBO workshop and had additional financial support form the University of Rome ‘La Sapienza’ and the ‘Centro di Genetica Evoluzionistica del CNR’. ![][1] During the past 10 years, Drosophila has revealed itself as a powerful system for studying the cell cycle, a field traditionally dominated by yeast and Xenopus . There are a number of reasons for this, including the fact that Drosophila is a well‐established model system amenable to sophisticated genetic analysis and molecular biology techniques. In fact, it is actually the only genetically amenable, higher eukaryote that is being used extensively as a model system for cell‐cycle research. Furthermore, as a higher eukaryote, Drosophila uses much of the same cell cycle machinery that is also used in vertebrates. The similarities go beyond ultrastructural detail, as shown by the recently published analysis of the Drosophila genome sequence, which revealed that half of the fly protein sequences identified by the Drosophila genome project show significant similarity to mammalian proteins and that the fly has orthologues of 61% of human disease genes and 68% of the cancer genes that were surveyed (Rubin et al ., 2000). The same applies to cell division; analysis of the Drosophila genome confirms previous suggestions of strong parallelism between flies and human cell cycle regulators. Last, but not least, Drosophila is much more amenable than other classical cell‐cycle models to analysis with the new cell imaging techniques. ### Live imaging One of the most significant highlights of the meeting was the extensive use of live imaging, which is becoming commonplace in the study of the cell … [1]: /embed/graphic-1.gif

Analysis of partner of inscuteable, a Novel Player of Drosophila Asymmetric Divisions, Reveals Two Distinct Steps in Inscuteable Apical Localization

Asymmetric localization is a prerequisite for inscuteable ( insc) to function in coordinating and mediating asymmetric cell divisions in Drosophila. We show here that Partner of Inscuteable (Pins), a new component of asymmetric divisions, is required for Inscuteable to asymmetrically localize. In the absence of pins, Inscuteable becomes cytoplasmic and asymmetric divisions of neuroblasts and mitotic domain 9 cells show defects reminiscent of insc mutants. Pins colocalizes with Insc and interacts with the region necessary and sufficient for directing its asymmetric localization. Analyses of pins function in neuroblasts reveal two distinct steps for Insc apical cortical localization: A pins-independent, bazooka-dependent initiation step during delamination (interphase) and a later maintenance step during which Baz, Pins, and Insc localization are interdependent.

Frizzled signalling controls orientation of asymmetric sense organ precursor cell divisions in Drosophila.

During metazoan development, cell-fate diversity is brought about, in part, by asymmetric cell divisions. In Drosophila, bristle mechanosensory organs are composed of four different cells that originate from a single precursor cell, pI, after two rounds of asymmetric division. At each division, distinct fates are conferred on sister cells by the asymmetric segregation of Numb, a negative regulator of Notch signalling. Here we show that the orientation of the mitotic spindles and the localization of the Numb crescent follow a stereotyped pattern. Mitosis of pI is orientated parallel to the anteroposterior axis of the fly. We show that signalling mediated by the Frizzled receptor polarizes pI along this axis, thereby specifying the orientation of the mitotic spindle and positioning the Numb crescent. The mitoses of the two cells produced by mitosis of pI are orientated parallel and orthogonal, respectively, to the division axis of pI. This difference in cell-division orientation is largely independent of the identity of the secondary precursor cells, and is regulated by Frizzled-independent mechanisms.

On the roles of inscuteable in asymmetric cell divisions in Drosophila.

Three processes requiring insc, protein localization, RNA localization, and mitotic spindle orientation, appear to be tightly correlated but nevertheless independent. The apical cortical localization of Insc protein occurs prior to mitosis and precedes the basal localization of Pros, Numb, and pros RNA. In insc null mutants, neuroblasts divide in more random orientations and fail to correctly localize Pros, Numb, and pros RNA to their correct position during mitosis. Our results suggest that asymmetric localization of Insc during interphase functions to establish positional information for spindle orientation and the basal localization of Numb, Pros, and pros RNA during mitosis. Insc probably interacts with a number of interacting partners in order to effect its various functions. One of its partners, Stau, is involved exclusively in the process of RNA localization.

Role of inscuteable in orienting asymmetric cell divisions in Drosophila.

Drosophila neuroblasts and epithelial cells in the procephalic neurogenic region divide perpendicular to the surface, and segregate the proteins Numb and Prospero into the basal daughter cell. We demonstrate here that orientation of the mitotic spindle and correct localization of Numb and Prospero in these cells require the inscuteable gene. Moreover, ectopic expression of inscuteable in other epithelial cells leads to spindle reorientation. The Inscuteable protein localizes to the apical cell cortex before mitosis, suggesting that Inscuteable functions in establishing polarity for asymmetric cell division.

7 Genetic Analysis of Cell Division in Drosophila

Publisher Summary This chapter discusses the genetics of cell division in Drosophila and the effect of different alterations in cell division on Drosophila development. Drosophila developmental genetics accommodate many old-fashioned techniques that should be routinely used to complement the knowledge of mitotic genes and their function. For many reasons, Drosophila has occupied a privileged position as a model system for genetics in the reduced historical time scale. It also occupies a privileged position in the evolutionary time scale. Many of the future relevant findings on the genetic control of cell division will come from the laboratories working with fruit flies, and these findings will be extrapolated with ease to other eukaryotes, including humans. The chapter elaborates on the effect of mitotic mutations on embryonic development, mitosis during postembryonic development, and tubulin and kinesin gene families.

Chapter 21 Mutations Affecting Cell Division in Drosophila

This chapter discusses the mutations affecting cell division in Drosophila . It is suggested that a combined genetic and molecular analysis of cell division can easily be carried out in Drosophila melanogaster . As relatively high-resolution cytological observations can be made on a variety of mitotically and meiotically active Drosophila tissues, this approach has the potential to yield considerable novel information. The richest source of cell-division mutants are those isolated through cytological analysis of collections of strains dying at the larval/pupal boundary. The chapter reviews available strategies for the isolation and characterization of Drosophila mitotic mutants. It describes the phenotypes of the mitotic mutants thus far isolated, showing that lesions in many different aspects of cell division can be detected. It also outlines a rapid and efficient protocol for the isolation of mitotic mutants that facilitate subsequent molecular cloning of the genes of interest.