Visualizing Fusome Morphology via Tubulin Immunofluorescence in Drosophila Ovarian Germ Cells.

In many species, oocytes are initially formed by the mitotic divisions of germline stem cells and their differentiating daughters. These progenitor cells are frequently interconnected in structures called cysts, which may function to safeguard oocyte quality. In Drosophila, an essential germline-specific organelle called the fusome helps maintain and coordinate the mitotic divisions of both germline stem cells and cyst cells.

Utilizing the FLP-Out System for Clonal RNAi Analysis in the Adult Drosophila Ovary.

The ability to conduct spatially controlled RNA interference (RNAi) for gene knockdown using the UAS/Gal4 system is among the most appealing techniques available for analysis of gene function in the Drosophila ovary. While gene knockdown experiments in somatic cells in the developing organism (i.e.

β-importin Tnpo-SR promotes germline stem cell maintenance and oocyte differentiation in female Drosophila.

Germ cell development requires interplay between factors that balance cell fate and division. Early in their development, germ cells in many organisms divide mitotically with incomplete cytokinesis. Key regulatory events then lead to the specification of mature gametes, marked by the switch to a meiotic cell cycle program.

Novel roles for RNA binding proteins squid, hephaesteus, and Hrb27C in Drosophila oogenesis.

Background: Reproductive capacity in many organisms is maintained by germline stem cells (GSCs). A complex regulatory network influences stem cell fate, including intrinsic factors, local signals, and hormonal and nutritional cues. Posttranscriptional regulatory mechanisms ensure proper cell fate transitions, promoting germ cell differentiation to oocytes.

Nuclear receptors linking physiology and germline stem cells in Drosophila.

Maternal nutrition and physiology are intimately associated with reproductive success in diverse organisms. Despite decades of study, the molecular mechanisms linking maternal diet to the production and quality of oocytes remain poorly defined. Nuclear receptors (NRs) link nutritional signals to cellular responses and are essential for oocyte development.

Orphan nuclear receptor ftz-f1 (NR5A3) promotes egg chamber survival in the Drosophila ovary.

Gamete production in mammals and insects is controlled by cell signaling pathways that facilitate communication between germ cells and somatic cells. Nuclear receptor signaling is a key mediator of many aspects of reproduction, including gametogenesis. For example, the NR5A subfamily of nuclear receptors is essential for gonad development and sex steroid production in mammals.

Coordinating Proliferation, Polarity, and Cell Fate in the Female Germline.

Gametes are highly specialized cell types produced by a complex differentiation process. Production of viable oocytes requires a series of precise and coordinated molecular events. Early in their development, germ cells are an interconnected group of mitotically dividing cells.

Novel cis-regulatory regions in ecdysone responsive genes are sufficient to promote gene expression in Drosophila ovarian cells.

The insect steroid hormone ecdysone is a key regulator of oogenesis in Drosophila melanogaster and many other species. Despite the diversity of cellular functions of ecdysone in oogenesis, the molecular regulation of most ecdysone-responsive genes in ovarian cells remains largely unexplored. We performed a functional screen using the UAS/Gal4 system to identify non-coding cis-regulatory elements within well-characterized ecdysone-response genes capable of driving transcription of an indelible reporter in ovarian cells.

Spargel/dPGC-1 is essential for oogenesis and nutrient-mediated ovarian growth in Drosophila.

Dietary proteins are crucial for oogenesis. The Target of Rapamycin (TOR) is a major nutrient sensor controlling organismal growth and fertility, but the downstream effectors of TOR signaling remain largely uncharacterized. We previously identified Drosophila Spargel/dPGC-1 as a terminal effector of the TOR-TSC pathway, and now report that Spargel connects nutrition to oogenesis.

Quantitative analysis and comparison of 3D morphology between viable and apoptotic MCF-7 breast cancer cells and characterization of nuclear fragmentation.

Morphological changes in apoptotic cells provide essential markers for defining and detection of apoptosis as a fundamental mechanism of cell death. Among these changes, the nuclear fragmentation and condensation have been regarded as the important markers but quantitative characterization of these changes is yet to be achieved. We have acquired confocal image stacks of 206 viable and apoptotic MCF-7 cells stained by three fluorescent dyes.

Temporal remodeling of the cell cycle accompanies differentiation in the Drosophila germline.

Development of multicellular organisms relies upon the coordinated regulation of cellular differentiation and proliferation. Growing evidence suggests that some molecular regulatory pathways associated with the cell cycle machinery also dictate cell fate; however, it remains largely unclear how the cell cycle is remodeled in concert with cell differentiation. During Drosophila oogenesis, mature oocytes are created through a series of precisely controlled division and differentiation steps, originating from a single tissue-specific stem cell.

RNAi-Based Techniques for the Analysis of Gene Function in Drosophila Germline Stem Cells.

Elucidating the full repertoire of molecular mechanisms that promote stem cell maintenance requires sophisticated techniques for identifying and characterizing gene function in stem cells in their native environment. Ovarian germline stem cells in the fruit fly, Drosophila melanogaster, are an ideal model to study the complex molecular mechanisms driving stem cell function in vivo. A variety of new genetic tools make RNAi a useful complement to traditional genetic mutants for the investigation of the molecular mechanisms guiding ovarian germline stem cell function.

Steroid Hormones and the Physiological Regulation of Tissue-Resident Stem Cells: Lessons from the Ovary.

Purpose Of Review: Stem cells respond to local paracrine signals; more recently, however, systemic hormones have also emerged as key regulators of stem cells. This review explores the role of steroid hormones in stem cells, using the germline stem cell as a centerpiece for discussion.

Recent Findings: Stem cells sense and respond directly and indirectly to steroid hormones, which regulate diverse sets of target genes via interactions with nuclear hormone receptors.

Making the cut: Innovative methods for optimizing perfusion-based migration assays.

Application of fluid shear stress to adherent cells dramatically influences their cytoskeletal makeup and differentially regulates their migratory phenotype. Because cytoskeletal rearrangements are necessary for cell motility and migration, preserving these adaptations under in vitro conditions and in the presence of fluid flow are physiologically essential. With this in mind, parallel plate flow chambers and microchannels are often used to conduct in vitro perfusion experiments.

A Genetic Mosaic Screen Reveals Ecdysone-Responsive Genes Regulating Drosophila Oogenesis.

Multiple aspects of Drosophila oogenesis, including germline stem cell activity, germ cell differentiation, and follicle survival, are regulated by the steroid hormone ecdysone. While the transcriptional targets of ecdysone signaling during development have been studied extensively, targets in the ovary remain largely unknown. Early studies of salivary gland polytene chromosomes led to a model in which ecdysone stimulates a hierarchical transcriptional cascade, wherein a core group of ecdysone-sensitive transcription factors induce tissue-specific responses by activating secondary branches of transcriptional targets.

Mcm10 is required for oogenesis and early embryogenesis in Drosophila.

Efficient replication of the genome and the establishment of endogenous chromatin states are processes that are essential to eukaryotic life. It is well documented that Mcm10 is intimately linked to both of these important biological processes; therefore, it is not surprising that Mcm10 is commonly misregulated in many human cancers. Most of the research regarding the biological roles of Mcm10 has been performed in single-cell or cell-free in-vitro systems.

Ecdysone response gene E78 controls ovarian germline stem cell niche formation and follicle survival in Drosophila.

Nuclear hormone receptors have emerged as important regulators of mammalian and Drosophila adult physiology, affecting such seemingly diverse processes as adipogenesis, carbohydrate metabolism, circadian rhythm, stem cell function, and gamete production. Although nuclear hormone receptors Ecdysone Receptor (EcR) and Ultraspiracle (Usp) have multiple known roles in Drosophila development and regulate key processes during oogenesis, the adult function of the majority of nuclear hormone receptors remains largely undescribed. Ecdysone-induced protein 78C (E78), a nuclear hormone receptor closely related to Drosophila E75 and to mammalian Rev-Erb and Peroxisome Proliferator Activated Receptors, was originally identified as an early ecdysone target; however, it has remained unclear whether E78 significantly contributes to adult physiology or reproductive function.

Drosophila oocytes as a model for understanding meiosis: an educational primer to accompany "corolla is a novel protein that contributes to the architecture of the synaptonemal complex of Drosophila".

Achieving a thorough understanding of the events and ramifications of meiosis is a common learning objective for undergraduate introductory biology, genetics, and cell biology courses. Meiosis is also one of the most challenging cellular processes for students to conceptualize. Connecting textbook descriptions of meiosis to current research in the field of genetics in a problem-based learning format may aid students' understanding of this important biological concept.

Control of adult stem cells in vivo by a dynamic physiological environment: diet-dependent systemic factors in Drosophila and beyond.

Adult stem cells are inextricably linked to whole-body physiology and nutrient availability through complex systemic signaling networks. A full understanding of how stem cells sense and respond to dietary fluctuations will require identifying key systemic mediators, as well as elucidating how they are regulated and integrated with local and intrinsic factors across multiple tissues. Studies focused on the Drosophila germline have generated valuable insights into how stem cells are controlled by diet-dependent pathways, and increasing evidence suggests that diverse adult stem cell populations respond to nutrients through similar mechanisms.

Cyclin E controls Drosophila female germline stem cell maintenance independently of its role in proliferation by modulating responsiveness to niche signals.

Stem cells must proliferate while maintaining 'stemness'; however, much remains to be learned about how factors that control the division of stem cells influence their identity. Multiple stem cell types display cell cycles with short G1 phases, thought to minimize susceptibility to differentiation factors. Drosophila female germline stem cells (GSCs) have short G1 and long G2 phases, and diet-dependent systemic factors often modulate G2.

Food for thought: neural stem cells on a diet.

Growing evidence shows that stem cells are modulated by systemic factors that are integrated with local signals in response to physiological status. Two recent Cell (Chell and Brand, 2010) and Nature (Sousa-Nunes et al., 2011) papers reveal that Drosophila neural stem cell proliferation is controlled by a diet-dependent insulin/TOR signaling relay between tissues.

The steroid hormone ecdysone functions with intrinsic chromatin remodeling factors to control female germline stem cells in Drosophila.

Steroid hormones are known systemic regulators of multiple normal and cancerous tissues; however, whether or how they impact the fate and function of adult stem cells is unclear. In the Drosophila ovary, insulin signals modulate the proliferation and self-renewal of germline stem cells (GSCs), yet despite evidence that additional systemic factors control GSC activity, these have remained largely unknown. Here, we report that ecdysone, a steroid hormone structurally related to mammalian sex steroids, directly regulates adult GSC proliferation and self-renewal independently of insulin signaling.

Multiple, temporal-specific roles for HNF6 in pancreatic endocrine and ductal differentiation.

Within the developing pancreas Hepatic Nuclear Factor 6 (HNF6) directly activates the pro-endocrine transcription factor, Ngn3. HNF6 and Ngn3 are each essential for endocrine differentiation and HNF6 is also required for embryonic duct development. Most HNF6(-/-) animals die as neonates, making it difficult to study later aspects of HNF6 function.

pdx-1 function is specifically required in embryonic beta cells to generate appropriate numbers of endocrine cell types and maintain glucose homeostasis.

The pdx1 gene is essential for pancreatic organogenesis in humans and mice; pdx1 mutations have been identified in human diabetic patients. Specific inactivation of pdx1 in adult beta cells revealed that this gene is required for maintenance of mature beta cell function. In the following study, a Cre-lox strategy was used to remove pdx1 function specifically from embryonic beta cells beginning at late-gestation, prior to islet formation.