Dissecting the Mechanisms and the Nutritional Requirements of the Expansion of Normal and Tumorigenic Intestinal Stem Cell Lineages in Drosophila melanogaster

Organisms are constantly challenged by injury and senescence. To replenish lost cells, adult tissue must contain a cellular reserve to maintain homeostasis. For example, adult stem cells exhibit two unique properties, self-renewal and potency, that make them well suited for this role. Tight regulatory control of stem cell properties is critical to maintain homeostatic balance; misregulation often leads to tumors or diseases. Recently, homeostasis of the intestinal epithelium has been shown to depend on a population of molecular defined intestinal stem cells: ISCs) in both Drosophila and mammals. However, the regulatory mechanisms controlling ISC behaviors remain poorly defined. We took advantage of the molecular genetic approaches available in Drosophila melanogaster to investigate how ISC properties are regulated by both intrinsic and extrinsic factors. In the course of the thesis, we identified two conserved signaling pathways that regulate ISC properties intrinsically. First, we demonstrated that WNT/APC signaling is an important regulator of ISC proliferation and relatively dispensable for potency. Parallel studies in mammals also show that loss of APC: APClof) in the ISC lineage leads to hyperplasia, supporting a model whereAPClofISCs can function as a cell-of-origin for intestinal tumors. In follow-up studies, we have taken a genetic approach to identify modifiers that control the expansion of tumorigenicAPCloflineages. We have now identified Insulin signaling as a modifier that is necessary and sufficient for the expansion of tumorigenicAPCloflineages. Future studies will define the precise cellular and molecular mechanisms underlying this phenomenon. A second key finding of our studies is that JAK/STAT signaling pathway coordinates ISC proliferation and regulates the competency for daughter cell differentiation. In summary, ISC properties are regulated by conserved WNT/APC and JAK/STAT signaling similar to what has been shown in other stem cell lineages. The intestinal tract is a primary site of nutrient absorption. We hypothesized that dietary nutrients can extrinsically regulate ISC properties. However, the precise requirement of individual macronutrients or micronutrients could not be investigated because a chemically defined food: CDF) consisting entirely of purified compounds was not available. We developed a new CDF media that permits CDFs with different nutrient compositions at iso-caloric density to be generated. Using this CDF recipe, we defined the individual macronutrient requirements for development, reproduction and longevity of Drosophila. Ongoing experiments are focused on determining the role of macronutrients in regulating ISC properties. We also seek to determine if nutrients are differentially required for normal and tumorigenic ISC lineages. Findings from this nutritional study may identify new therapeutic targets for regenerative medicine or cancer therapy

Development and characterization of a chemically defined food for Drosophila

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. In addition, CDF facilitates the direct comparison of data obtained independently from different laboratories. Here, we report the development and characterization of a CDF for Drosophila. We show that CDF can support the long-term culture of laboratory strains and demonstrate that this formulation has utility in isolating macronutrient from caloric density requirements in studies of development, longevity and reproduction

The Impact of Peak Hydrogeneration for Reserving Environmental Flow in Dachia River, Taiwan

Source: ICHE Conference Archive - https://mdi-de.baw.de/icheArchiv

Tailoring excitonic states of van der Waals bilayers through stacking configuration, band alignment and valley-spin

Excitons in monolayer semiconductors have large optical transition dipole for strong coupling with light field. Interlayer excitons in heterobilayers, with layer separation of electron and hole components, feature large electric dipole that enables strong coupling with electric field and exciton-exciton interaction, at the cost that the optical dipole is substantially quenched (by several orders of magnitude). In this letter, we demonstrate the ability to create a new class of excitons in transition metal dichalcogenide (TMD) hetero- and homo-bilayers that combines the advantages of monolayer- and interlayer-excitons, i.e. featuring both large optical dipole and large electric dipole. These excitons consist of an electron that is well confined in an individual layer, and a hole that is well extended in both layers, realized here through the carrier-species specific layer-hybridization controlled through the interplay of rotational, translational, band offset, and valley-spin degrees of freedom. We observe different species of such layer-hybridized valley excitons in different heterobilayer and homobilayer systems, which can be utilized for realizing strongly interacting excitonic/polaritonic gases, as well as optical quantum coherent controls of bidirectional interlayer carrier transfer either with upper conversion or down conversion in energy

The influence of the technical dimension, functional dimension, and tenant satisfaction on tenant loyalty: an analysis based on the theory of planned behavior

This study primarily explored the influence of the technical dimension, functional dimension, and tenant satisfaction on tenant loyalty. The theory of planned behavior served as the basis of this study, and the three aforementioned factors (the technical dimension, the functional dimension, and tenant satisfaction) were incorporated into a conceptual framework for tenant loyalty. Structural equation modeling (SEM) was employed for parameter estimation. The participants consisted of tenants residing in eight administrative districts in Kaohsiung City. 315 questionnaires were administered, all of which were returned. After removing 15 invalid responses, there were 300 valid responses, which indicated an effective recovery rate of 95.2%. The results showed that the technical dimension, the functional dimension, and attitude significantly and positively influenced tenant satisfaction. Tenant satisfaction, perceived behavioral control, and social norms significantly and positively influenced tenant loyalty. Tenant satisfaction mediated the influence of the technical dimension and the functional dimension on tenant loyalty; the mediating effect of the functional dimension on tenant loyalty was greater than that of the technical dimension. The findings of this study highlight the measures rental companies should adopt in order to enhance the technical dimension, functional dimension, and tenant satisfaction, as this is crucial to maintaining sustainable operations

The Incentive Mechanism with RFID Technology for Suppliers to Design Environmentally-Friendly Electrical and Electronic Equipment

AbstractTaiwan EPA has promulgated Resource Recycling Act in 2002, which is formulated to conserve natural resources, reduce waste, promote recycling and reuse of materials, mitigate environmental loading, and build a society in which resources are used in a sustainable manner. [1] Since 1998, the recycling of waste large household appliances such as televisions, washing machines, refrigerators, and air conditioners, etc. has been implemented; waste electric fans and waste computer keyboards were also included in 2007. Although recycling in Taiwan initiated early, whether waste electrical and electronic equipment recycling is just the process of decomposition, recycling, incineration, and landfill, rather than extending the product lifespan, need further studies to confirm that.The Recycling Fund Management Board takes charge of the operation of recycling mechanism in Taiwan. The funds mostly paid by the businesses as the recycling, clearance and disposal fees. Such fees now are unified under the same products specifications. The existed system can’t provide products under the same specifications but with longer lifespan more preferential fees, which means that there is no incentive for the suppliers to improve the design of products.With Radio Frequency Identification (RFID) inserted in, the household appliances will not only have the basic information about the product, but also can keep track of the purchase and maintenance record, as well as the disposal date and location, during the use stage of that product. Such record provides information on the service life of the product, and the recycling fees paid by businesses could be returned relative to the lifetime to the consumers accordingly. The new mechanism incentives the suppliers to consider the product durability in design and manufacture stages that helps achieve the goal to make products decomposable, recyclable, and lifetime extended