Publications by authors named "Micchelli C"

Morphological modifications and shifts in organelle relationships are hallmarks of dormancy in eukaryotic cells. Communications between altered mitochondria and nuclei are associated with metabolic quiescence of cancer cells that can survive chemotherapy. In plants, changes in the pathways between nuclei, mitochondria, and chloroplasts are associated with cold stress and bud dormancy.

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Morphological modifications and shifts in organelle relationships are hallmarks of dormancy in eukaryotic cells. Communications between altered mitochondria and nuclei are associated with metabolic quiescence of cancer cells that can survive chemotherapy. In plants, changes in the pathways between nuclei, mitochondria, and chloroplasts are associated with cold stress and bud dormancy.

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Microbial pathogens use proteases for their infections, such as digestion of proteins for nutrients and activation of their virulence factors. As an obligate intracellular parasite, must invade host cells to establish its intracellular propagation. To facilitate invasion, the parasites secrete invasion effectors from microneme and rhoptry, two unique organelles in apicomplexans.

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Microbial recognition is a key step in regulating the immune signaling pathways of multicellular organisms. Peptidoglycan, a component of the bacterial cell wall, exhibits immune stimulating activity in both plants and animals. Lysin motif domain (LysMD) family proteins are ancient peptidoglycan receptors that function in bacteriophage and plants.

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Unlabelled: Microbial pathogens use proteases for their infections, such as digestion of proteins for nutrients and activation of their virulence factors. As an obligate intracellular parasite, must invade host cells to establish its intracellular propagation. To facilitate invasion, the parasites secrete invasion effectors from microneme and rhoptry, two unique organelles in apicomplexans.

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Toxoplasma gondii is a protozoan pathogen that widely affects the human population. The current antibiotics used for treating clinical toxoplasmosis are limited. In addition, they exhibit adverse side effects in certain groups of people.

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We describe a new methodology for genetically labeling single cell lineages in Drosophila called DMARCM. The system offers ultra-low frequency labeling, linear induction, consistent labeling among individuals and virtually no background signal. We compare this technique to an existing approach, which has been widely adopted.

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Germline-encoded receptors recognizing common pathogen-associated molecular patterns are a central element of the innate immune system and play an important role in shaping the host response to infection. Many of the innate immune molecules central to these signaling pathways are evolutionarily conserved. LysMD3 is a novel molecule containing a putative peptidoglycan-binding domain that has orthologs in humans, mice, zebrafish, flies, and worms.

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The endocrine system employs peptide hormone signals to translate environmental changes into physiological responses. The diffuse endocrine system embedded in the gastrointestinal barrier epithelium is one of the largest and most diverse endocrine tissues. Furthermore, it is the only endocrine tissue in direct physical contact with the microbial environment of the gut lumen.

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The endocrine system mediates long-range peptide hormone signaling to broadcast changes in metabolic status to distant target tissues via the circulatory system. In many animals, the diffuse endocrine system of the gut is the largest endocrine tissue, with the full spectrum of endocrine cell subtypes not yet fully characterized. Here, we combine molecular mapping, lineage tracing and genetic analysis in the adult fruit fly to gain new insight into the cellular and molecular mechanisms governing enteroendocrine cell diversity.

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The gastrointestinal (GI) tract harbors an essential barrier epithelium that separates an organism from its changing external environment. As such, the gut epithelium is a fascinating nexus of stem cell biology, immunology and physiology. Investigators have sought to mine this rich interface for new biological and mechanistic insights.

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Adult stem cells vary widely in their rates of proliferation. Some stem cells are constitutively active, while others divide only in response to injury. The mechanism controlling this differential proliferative set point is not well understood.

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Diet can affect a spectrum of biological processes ranging from behavior to cellular metabolism. Yet, the precise role of an individual dietary constituent can be a difficult variable to isolate experimentally. A chemically defined food (CDF) permits the systematic evaluation of individual macro- and micronutrients.

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The adult Drosophila copper cell region or "stomach" is a highly acidic compartment of the midgut with pH < 3. In this region, a specialized group of acid-secreting cells similar to mammalian gastric parietal cells has been identified by a unique ultrastructure and by copper-metallothionein fluorescence. However, the homeostatic mechanism maintaining the acid-secreting "copper cells" of the adult midgut has not been examined.

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Renewing tissues in the adult organism such as the gastrointestinal (GI) epithelium depend on stem cells for epithelial maintenance and repair. Yet, little is known about the developmental origins of adult stem cells and their niches. Studies of Drosophila adult midgut precursors (AMPs), a population of endodermal progenitors, demonstrate that adult intestinal stem cells (ISCs) arise from the AMP lineage and provide insight into the stepwise process by which the adult midgut epithelium is established during development.

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The adult Drosophila midgut is thought to arise from an endodermal rudiment specified during embryogenesis. Previous studies have reported the presence of individual cells termed adult midgut precursors (AMPs) as well as "midgut islands" or "islets" in embryonic and larval midgut tissue. Yet the precise relationship between progenitor cell populations and the cells of the adult midgut has not been characterized.

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Adult stem cells are the most primitive cells of a lineage and are distinguished by the properties of self-renewal and multipotency. Coordinated control of stem cell proliferation and multilineage differentiation is essential to ensure a steady output of differentiated daughter cells necessary to maintain tissue homeostasis. However, little is known about the signals that coordinate stem cell proliferation and daughter cell differentiation.

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Adult stem cells define a cellular reserve with the unique capacity to replenish differentiated cells of a tissue throughout an organism's lifetime. Previous analysis has demonstrated that the adult Drosophila midgut is maintained by a population of multipotent intestinal stem cells (ISCs) that resides in epithelial niches. Adenomatous polyposis coli (Apc), a tumor suppressor gene conserved in both invertebrates and vertebrates, is known to play a role in multiple developmental processes in Drosophila.

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Adult stem cells maintain organ systems throughout the course of life and facilitate repair after injury or disease. A fundamental property of stem and progenitor cell division is the capacity to retain a proliferative state or generate differentiated daughter cells; however, little is currently known about signals that regulate the balance between these processes. Here, we characterize a proliferating cellular compartment in the adult Drosophila midgut.

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In this letter, we provide a study of learning in a Hilbert space of vectorvalued functions. We motivate the need for extending learning theory of scalar-valued functions by practical considerations and establish some basic results for learning vector-valued functions that should prove useful in applications. Specifically, we allow an output space Y to be a Hilbert space, and we consider a reproducing kernel Hilbert space of functions whose values lie in Y.

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Signaling from the Notch (N) receptor is essential for proper cell-fate determinations and tissue patterning in all metazoans. N signaling requires a presenilin (PS)-dependent transmembrane-cleaving activity that is closely related or identical to the gamma-secretase proteolysis of the amyloid-beta precursor protein (APP) involved in Alzheimer's disease pathogenesis. Here, we show that N-[N-(3,5-difluorophenacetyl)-L-alanyl]-(S)-phenylglycine t-butyl ester, a potent gamma-secretase inhibitor reported to reduce amyloid-beta levels in transgenic mice, prevents N processing, translocation, and signaling in cell culture.

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Members of the Hedgehog (Hh) family encode secreted molecules that act as potent organizers during vertebrate and invertebrate development. Post-translational modification regulates both the range and efficacy of Hh protein. One such modification is the acylation of the N-terminal cysteine of Hh.

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The formation of boundaries that prevent the intermixing of cells is an important developmental patterning mechanism. The compartmental lineage restrictions that appear in the developing imaginal discs of Drosophila are striking examples of such boundaries. However, little is known about the cellular mechanism underlying compartmental lineage restrictions.

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We have investigated the role of the Notch and Wingless signaling pathways in the maintenance of wing margin identity through the study of cut, a homeobox-containing transcription factor and a late-arising margin-specific marker. By late third instar, a tripartite domain of gene expression can be identified about the dorsoventral compartment boundary, which marks the presumptive wing margin. A central domain of cut- and wingless-expressing cells are flanked on the dorsal and ventral side by domains of cells expressing elevated levels of the Notch ligands Delta and Serrate.

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