Several groups within tribe Phyllantheae (Phyllanthaceae) formed, independently, an (obligate) pollination mutualism with Epicephala moths, which originally had been parasitic. In this pollination... Show moreSeveral groups within tribe Phyllantheae (Phyllanthaceae) formed, independently, an (obligate) pollination mutualism with Epicephala moths, which originally had been parasitic. In this pollination system, female moths actively collect pollen from staminate flowers and deposit it on the stigma of pistillate flowers, after which they place at least one egg in or against the ovary. The high pollination rate makes the system beneficial for the plants, whereas the larvae are provided with food (part of the developing seeds) and some protection against predation. Qualitative comparisons are made between non-moth-pollinated lineages, used as outgroups and various, independently moth-pollinated Phyllantheae clades, used as ingroups, thereby looking for parallel developments. The flowers of both sexes of various groups display similar, convergent morphological adaptations to the pollination system, likely to secure the obligate relationship and to improve efficiency. Sepals in both sexes, free or partly to highly connate, are commonly upright and form a narrow tube. The staminate flowers often have united, vertical stamens with the anthers along the androphore or on top of the androphore. Pistillate flowers generally reduce the stigmatic surface, either by making the stigmas shorter or by uniting them into a cone with a small opening at the top for pollen deposition. Less obvious is the reduction of the stigmatic papillae; these are often present in non-moth-pollinated taxa, but absent in the moth-pollinated species. The most diverging, parallel adaptations to moth pollination are currently found in the Palaeotropics, whereas in the Neotropics, some groups continue to also be pollinated by other insect groups and are morphologically less changed. Show less
Stel, W. van der; Yang, H.; Le Dévédec, S.E.; Water, B. van de; Beltman, J.B.; Danen, E.H.J. 2022
Cells can adjust their mitochondrial morphology by altering the balance between mitochondrial fission and fusion to adapt to stressful conditions. The connection between a chemical perturbation,... Show moreCells can adjust their mitochondrial morphology by altering the balance between mitochondrial fission and fusion to adapt to stressful conditions. The connection between a chemical perturbation, changes in mitochondrial function, and altered mitochondrial morphology is not well understood. Here, we made use of high-throughput high-content confocal microscopy to assess the effects of distinct classes of oxidative phosphorylation (OXPHOS) complex inhibitors on mitochondrial parameters in a concentration and time resolved manner. Mitochondrial morphology phenotypes were clustered based on machine learning algorithms and mitochondrial integrity patterns were mapped. In parallel, changes in mitochondrial membrane potential (MMP), mitochondrial and cellular ATP levels, and viability were microscopically assessed. We found that inhibition of MMP, mitochondrial ATP production, and oxygen consumption rate (OCR) using sublethal concentrations of complex I and III inhibitors did not trigger mitochondrial fragmentation. Instead, complex V inhibitors that suppressed ATP and OCR but increased MMP provoked a more fragmented mitochondrial morphology. In agreement, complex V but not complex I or III inhibitors triggered proteolytic cleavage of the mitochondrial fusion protein, OPA1. The relation between increased MMP and fragmentation did not extend beyond OXPHOS complex inhibitors: increasing MMP by blocking the mPTP pore did not lead to OPA1 cleavage or mitochondrial fragmentation and the OXPHOS uncoupler FCCP was associated with OPA1 cleavage and MMP reduction. Altogether, our findings connect vital mitochondrial functions and phenotypes in a high-throughput high-content confocal microscopy approach that help understanding of chemical-induced toxicity caused by OXPHOS complex perturbing chemicals. Show less
Tin electrodeposition applications have rapidly evolved in the past 25 years. Usage of tin coatings has advanced from being mainly used for corrosion protection and decorative purposes, to being... Show moreTin electrodeposition applications have rapidly evolved in the past 25 years. Usage of tin coatings has advanced from being mainly used for corrosion protection and decorative purposes, to being used in modern technology such in electronic devices, photovoltaic cells and Li-ion batteries. The new tin coating applications have also come with challenges that require the production of nanostructured deposits, multilayers coatings and composites. Furthermore, the need to reduce energy and source consumptions, and the implementation of more environment-friendly processes, require detailed and fundamental knowledge of the electrodeposition process.The emphasis throughout this thesis is therefore to obtain detailed mechanistic information of tin electrodeposition process.The experimental and theoretical work presented in this thesis attempts to understand the mechanism of tin electrodeposition, and the effect of electrolyte anions and naphthalene-based additives, during the early and subsequent stages of the process. Show less
Streptomyces are multicellular, Gram-positive bacteria in the phylum of actinobacteria which produce a high amount of bioactive natural products of which the expression is tightly coordinated with... Show moreStreptomyces are multicellular, Gram-positive bacteria in the phylum of actinobacteria which produce a high amount of bioactive natural products of which the expression is tightly coordinated with the life cycle. This thesis shows the identification of S. roseifaciens, a novel species with an uncommon, verticillate spore morphology and a unique household of SsgA-like proteins. Analyses of the peptidoglycan composition show that S. coelicolor show a pattern of 3-3 cross-linking befitting a tip-growing organism and change in composition between vegetative mycelium and spores. Kitasatosporae carry meso-DAP in the peptidoglycan of vegetative mycelium and LL-DAP in the peptidoglycan of spores. In line with this difference, the peptidoglycan architecture of these two growth stages undergoes such radical changes that they would seem to be from different species. S. coelicolor is naturally vancomycin resistant, but the addition of D-alanine and disruption in a single gene increases vancomycin sensitivity by a thousandfold. A knockout mutant of the alanine racemase, alr, requires exogenous addition of D-alanine. The Alr crystal structure of S. coelicolor and the D-cycloserine producer S. lavendulae were compared as to look for possible mechanisms for D-cycloserine resistance. Show less
Streptomyces are Gram-positive, soil dwelling bacteria that raised interest in the last 50 years for their high potential in antibiotic and protein production. Thanks to their saprophytic nature,... Show moreStreptomyces are Gram-positive, soil dwelling bacteria that raised interest in the last 50 years for their high potential in antibiotic and protein production. Thanks to their saprophytic nature, streptomycetes secrete a massive amount of industrial enzymes. They have a relatively low level of endogenous extracellular proteolytic activity when compared to other expression hosts (e.g. Bacillus), they are generally more suited to produce proteins encoded by high G+C actinomycete genes in their native form, coupled to efficient secretion so as to avoid that the proteins end up in inclusion bodies (often a problem when using e.g. E. coli) and making downstream processes easier. Despite their attractive potential, Streptomyces present several constraints which so far limit their application in industry. The first constraint is morphology: by growing as a network of hyphae, they produce dense pellets in liquid cultures that hold Streptomyces back from being one of the first choice cell factories in large scale fermentations. In addition, the limited availability of efficient expression systems for high-level transcription/translation and subsequent secretion is a further bottleneck. This thesis presents the work done to address these issues for the optimization of Streptomyces lividans for future industrial applications and enzyme production. Show less
Merels in de stad blijken te verschillen van soortgenoten in naburige bossen ten aanzien van lichaamsbouw, zang, en genetica. Nederlandse stadsmerels zijn zwaarder dan hun soortgenoten in het bos.... Show moreMerels in de stad blijken te verschillen van soortgenoten in naburige bossen ten aanzien van lichaamsbouw, zang, en genetica. Nederlandse stadsmerels zijn zwaarder dan hun soortgenoten in het bos. Daarnaast zingen stadsmerels met een hogere frequentie dan bosmerels wat de hoorbaarheid bij laagtonig verkeerslawaai ten goede komt. Merelmannen merken zelf daadwerkelijk de verschillen op tussen de zang van stads- en bosmerels, zo blijkt uit experimenten waarbij de zang werd afgespeeld in merelterritoria in stad en bos. Stadsmerels reageren namelijk sterker op hogere zang en bosmerels juist meer op lagere. Variatie in zang en reactie op zang kan mogelijk de onderlinge uitwisseling tussen stad- en bospopulaties be_nvloeden. Dit wordt ondersteund door de bevinding dat populaties uit steden en naburige bossen inderdaad genetisch anders zijn. De gevonden verschillen zijn opmerkelijk omdat de studiepopulaties in stad en bos slechts 5 _ 10 km uit elkaar liggen. Het onderzoek toont dus aan dat een stedelijke omgeving invloed kan hebben op belangrijke soortskenmerken waarbij het echter nog maar de vraag is of deze evolutie ooit zal leiden tot het ontstaan van twee gescheiden merelsoorten. Show less
