The model angiosperm Arabidopsis thaliana produces viable seed through coordinated growth of three constituents; seed coat, embryo and endosperm. During development the embryo grows to fill the space defined by the seed coat. The growing embryo is surrounded by endosperm, an ephemeral, nutritive structure. The process of programmed cell death (PCD) is essential for endosperm consumption by the embryo however very little is known about developmental PCD in the endosperm. ZOU is a transcription factor expressed specifically in endosperm adjacent to the growing embryo in the Embryo Surrounding Region (ESR) (Yang et al., 2008). zou seed likely have reduced PCD resulting in abnormally persistent endosperm and a small embryo at seed maturity which results in seed shriveling. A second zou phenotype is an impairment of cuticle development in the embryonic leaves (cotyledons), suggesting that ZOU may mediate a signal from endosperm to embryo. The ESR expressed gene ALE1 is down-regulated in zou. When ALE1 is artificially expressed in zou ESR by the construct pSUC5::ALE1 the zou epidermal phenotype is rescued but not the seed shriveling phenotype of zou (Xing et al., 2013). Fixed and resin-embedded sections of zou and pSUC5::ALE1 lines herein confirm that zou-like endosperm is exhibited in pSUC5::ALE1 lines. This confirms that the two phenotypes of zou are genetically separable. The involvement of ZOU in epidermal processes is further confirmed through genetic studies showing that ZOU acts in the same pathway to impart embryonic cuticle as the embryo-expressed Receptor Like Kinases GSO1 and GSO2. In order to quantify PCD in the endosperm of wild-type and zou seed, PCD expression marker and TUNEL analysis were conducted. One PCD marker, pCEP:H2A-YFP is shown to be expressed in wild-type ESR, it is not clear if expression is lost in zou. To identify candidate genes under the control of ZOU active in endosperm PCD the results from several transcriptional profiling experiments were analysed and validated; this detailed gene expression in wild-type, ale1 and zou siliques which allowed for the identification of targets of ZOU but not of ALE1, targets predicted to be PCD effectors. In silico expression and ontology analysis confirmed likely roles for some candidates in endosperm PCD processes (particularly cell wall modification). Selected targets were cloned under pSUC5 and expressed in the ESR of zou seed as part of a molecular screen for the rescue of the zou endosperm phenotype. The ZOU target FRINGE-Like, a Glycosyl Transferase which shows strong endosperm expression is shown to partially rescue the zou phenotype but does not rescue the epidermal phenotype, suggesting that it may mediate PCD processes under ZOU control. The initial discovery that a Glycosyl Transferase may be active in a developmental PCD process in plants is exciting and novel and benefits understanding of developmental PCD and endosperm breakdown, two poorly characterized processes in plants.

Programmed cell death and cell corpse clearance are an essential part of an organism’s overall health and development. Cell corpses are often engulfed by professional phagocytes such as macrophages. However, in certain tissues, neighboring non-professional cells can also carry out phagocytic functions. Here, we use the Drosophila melanogaster ovary to investigate novel genes required for engulfment by non-professional phagocytes. In the Drosophila ovary, neighboring epithelial cells facilitate the clearance of dying germline cells. We performed an unbiased kinase screen to identify novel proteins and pathways involved in cell clearance in the nurse cell. Several genes identified in this screen were members of the phosphoinositide 3-kinase (PI3K) family. The class II and III PI3Ks are required for nurse cell clearance and acidification during late-stage oogenesis. Class I PI3K is required for progression during engulfment in mid-stage oogenesis. This kinase screen has revealed novel genes for further exploration and investigation. / 2019-02-28T00:00:00Z

<p>Föreliggande studies syfte är att vara en första byggsten i skapandet av ett praktiskt användbart tillvägagångssätt för interaktionsdesign som bygger på programmerad inlärning och tillämpad beteendeanalys. Litteraturstudier och logiska resonemang resulterade i en iterativ metod. Denna tillämpades sedan på fallet Dice Arena för att generera kunskap inför framtida utveckling av denna eller liknande metoder. Slutsatsen var att designmetoden är ofullständig men till viss del användbar. Designmetodens huvudsakliga bidrag var en sekvensdesign, en delmetod som strukturerade och tydliggjorde designuppgiften.</p>

Föreliggande studies syfte är att vara en första byggsten i skapandet av ett praktiskt användbart tillvägagångssätt för interaktionsdesign som bygger på programmerad inlärning och tillämpad beteendeanalys. Litteraturstudier och logiska resonemang resulterade i en iterativ metod. Denna tillämpades sedan på fallet Dice Arena för att generera kunskap inför framtida utveckling av denna eller liknande metoder. Slutsatsen var att designmetoden är ofullständig men till viss del användbar. Designmetodens huvudsakliga bidrag var en sekvensdesign, en delmetod som strukturerade och tydliggjorde designuppgiften.

There is no abstract available for this thesis.

The amnioserosa (AS) is an epithelium that plays major roles in two crucial morphogenetic processes during Drosophila embryogenesis: Germ Band Retraction (GBR) and Dorsal Closure (DC). The AS is extraembryonic and as such, it does not contribute to the mature embryo but is eliminated during development by programmed cell death. In this thesis, a comprehensive investigation of the timing and characteristics of the AS death and degeneration is performed. It is demonstrated that AS elimination occurs in two phases: “cell extrusion” during DC, embryonic stages 12 to 14, and “tissue dissociation” following DC, embryonic stages 15 to 16. Ten percent of AS cells are eliminated during phase one while the remaining ninety percent are removed during phase two. It is found that both cell extrusion and tissue dissociation are absent in apoptotic defective backgrounds, as well as in genetic backgrounds associated with increased class I phosphoinositide 3-kinase (PI3K) activity, a key regulator of autophagy. It is also found that extrusion is enhanced two-fold in embryos expressing the pro-apoptotic reaper gene product, and that tissue dissociation also accelerates in this background. Interestingly, our observations suggest that the activation of caspase cascade is not complete until AS cells have lost apical contacts with neighboring cells. Shortly after the loss of apical contact, an apoptotic morphology including membrane blebbing, cell fragmentation, and macrophage engulfment is readily observed. Measurements of the rate of DC demonstrate that this process is protracted in backgrounds lacking extrusion, leading to the conclusion that extrusion contributes towards generating adequate AS tension required for normal DC rates. Overall, our data suggest that phase one extrusion and phase two dissociation are manifestations of the same cellular event and that both are caspase dependent. It is also demonstrated that autophagy is a key component of AS death that acts upstream of apoptosis. Strikingly, our results lead to the suggestion that autophagy may function to trigger apoptosis during the programmed elimination of this extra-embryonic tissue.

There is no abstract available for this dissertation.

The amnioserosa (AS) is an epithelium that plays major roles in two crucial morphogenetic processes during Drosophila embryogenesis: Germ Band Retraction (GBR) and Dorsal Closure (DC). The AS is extraembryonic and as such, it does not contribute to the mature embryo but is eliminated during development by programmed cell death. In this thesis, a comprehensive investigation of the timing and characteristics of the AS death and degeneration is performed. It is demonstrated that AS elimination occurs in two phases: “cell extrusion” during DC, embryonic stages 12 to 14, and “tissue dissociation” following DC, embryonic stages 15 to 16. Ten percent of AS cells are eliminated during phase one while the remaining ninety percent are removed during phase two. It is found that both cell extrusion and tissue dissociation are absent in apoptotic defective backgrounds, as well as in genetic backgrounds associated with increased class I phosphoinositide 3-kinase (PI3K) activity, a key regulator of autophagy. It is also found that extrusion is enhanced two-fold in embryos expressing the pro-apoptotic reaper gene product, and that tissue dissociation also accelerates in this background. Interestingly, our observations suggest that the activation of caspase cascade is not complete until AS cells have lost apical contacts with neighboring cells. Shortly after the loss of apical contact, an apoptotic morphology including membrane blebbing, cell fragmentation, and macrophage engulfment is readily observed. Measurements of the rate of DC demonstrate that this process is protracted in backgrounds lacking extrusion, leading to the conclusion that extrusion contributes towards generating adequate AS tension required for normal DC rates. Overall, our data suggest that phase one extrusion and phase two dissociation are manifestations of the same cellular event and that both are caspase dependent. It is also demonstrated that autophagy is a key component of AS death that acts upstream of apoptosis. Strikingly, our results lead to the suggestion that autophagy may function to trigger apoptosis during the programmed elimination of this extra-embryonic tissue.

none

The carbonaceous material possesses many kinds of structures and extensive applicability. For example, they are used for lithium battery and fuel cell electrode, printer¡¦s carbon powder, and for the reinforcement of tire. The carbon nanotube and carbon nanocapsule are the novel carbonaceous materials. Their unique property and applicability have attracted a lot of investigation. In this research, we attempt to understand the relationship between the structures and chemical properties of the carbonaceous material. Graphite is an ideal model for this study, and the temperature-programmed desorption method is applied in this investigation. XRD and TEM are also used to support the results of TPD method. Four kinds of exploration molecules are chosen. They are benzene-like molecules, cyclohexane-like molecules, long chain molecules and alcohol-like molecules, respectively. We attempt to find out the differences of the interaction between graphite and various kinds of molecules. The benzene-like molecules with alkyl branch are strongly adsorbed on graphite. The adsorption of long chain molecules on graphite is the next. There are more than one kind of adsorption site on graphite available for 1,3-hexadiene and alcohol-like molecules adsorption. The adsorption behavior of 1,3-hexadiene and alcohol molecules are more complicated. Although the desorption activation energy for different molecules on graphite with different coverages are different. The difference in the desorption activation energy are negligible. The tendency of change is similar for the same kind of molecules. The adsorbed molecules can also diffuse into graphite¡¦s interlayer structure. The interlayer distance of graphite can be changed by the diffusion process of the adsorbed molecules. The desorption activation energies may change when graphite¡¦s pore size changes or functional groups exist on graphite surface. The changes of the activation energy caused by the change of graphite¡¦s pore size or by the surface functional groups are more prominent than the changes induced by the coverage difference of adsorbed molecules on graphite.