Om Cellbyggnad Och Tjufbin Hos Trachusa Serratulae

De egendomliga celler, som forfardigas af denna biart, ha forst efter 1890 borjat bli mera allmant kanda. Namnda ar beskrefvos de sasom forut obekanta dels af Perez, dels af J. Sahlberg

The Effects of Elasticity and Geometry on Cell Migration and Polarization

Cell migration is a crucial process in the development and maintenance of the human body. Migration is also involved in a number of pathologies. In atherosclerosis, for example, immune cells migrate to the site of inflammation and contribute to the progression of the disease. In cancer, cells migrate out of the primary tumor through the body to metastasize at distant sites creating deadly secondary tumors. In all of these examples, cells confront and must adapt to a broad range of extracellular environments. Two important properties that cells encounter in the body are the elasticity of the environment and confinement. A better understanding of how a cell responds to these parameters would offer insights into the progression of diseases like cancer and atherosclerosis. Much cell migration research, however, has focused on cells moving on flat stiff substrates, like a glass culture dish. Therefore, in this dissertation, we investigated the effects of substrate elasticity and confinement on cell polarization and migration. First, macrophage behavior was studied on substrates of different stiffness. We found that macrophages are mechanosensitive and respond with changes in area, proliferation, and migration. To further investigate cell migration in response to stiffness we focused on polarization, the first step in directed cell migration, and found that the position of the centrosome, an organelle indicating polarity, was dependent on substrate elasticity. Micropatterned one-dimensional lines and a microfluidic device were used to study the effect of confinement on cell polarization and migration. We discovered that the centrosome position for cells migrating on lines is different than in two-dimensional migration and we also show the importance of microtubule polymerization forces in maintaining centrosome position. We used a microfluidic device to mimic the three-dimensional confinement cells encounter in the body. Under increased confinement, the centrosome position is more similar to migration on lines than on flat surfaces and is maintained even when cells change directions. These results demonstrate how the elasticity and confinement of a cell’s microenvironment affect cell polarization and migration. These results are important to further understand the role of these parameters in the progression of diseases like atherosclerosis and cancer

Visual ecology of aphids – a critical review on the role of colours in host finding

We review the rich literature on behavioural responses of aphids (Hemiptera: Aphididae) to stimuli of different colours. Only in one species there are adequate physiological data on spectral sensitivity to explain behaviour crisply in mechanistic terms. Because of the great interest in aphid responses to coloured targets from an evolutionary, ecological and applied perspective, there is a substantial need to expand these studies to more species of aphids, and to quantify spectral properties of stimuli rigorously. We show that aphid responses to colours, at least for some species, are likely based on a specific colour opponency mechanism, with positive input from the green domain of the spectrum and negative input from the blue and/or UV region. We further demonstrate that the usual yellow preference of aphids encountered in field experiments is not a true colour preference but involves additional brightness effects. We discuss the implications for agriculture and sensory ecology, with special respect to the recent debate on autumn leaf colouration. We illustrate that recent evolutionary theories concerning aphid–tree interactions imply far-reaching assumptions on aphid responses to colours that are not likely to hold. Finally we also discuss the implications for developing and optimising strategies of aphid control and monitoring

Rescue of Photoreceptor Degeneration by Curcumin in Transgenic Rats with P23H Rhodopsin Mutation

The P23H mutation in the rhodopsin gene causes rhodopsin misfolding, altered trafficking and formation of insoluble aggregates leading to photoreceptor degeneration and autosomal dominant retinitis pigmentosa (RP). There are no effective therapies to treat this condition. Compounds that enhance dissociation of protein aggregates may be of value in developing new treatments for such diseases. Anti-protein aggregating activity of curcumin has been reported earlier. In this study we present that treatment of COS-7 cells expressing mutant rhodopsin with curcumin results in dissociation of mutant protein aggregates and decreases endoplasmic reticulum stress. Furthermore we demonstrate that administration of curcumin to P23H-rhodopsin transgenic rats improves retinal morphology, physiology, gene expression and localization of rhodopsin. Our findings indicate that supplementation of curcumin improves retinal structure and function in P23H-rhodopsin transgenic rats. This data also suggest that curcumin may serve as a potential therapeutic agent in treating RP due to the P23H rhodopsin mutation and perhaps other degenerative diseases caused by protein trafficking defects

Multiple ecosystem services from field margin vegetation for ecological sustainability in agriculture: scientific evidence and knowledge gaps

Background: Field margin and non-crop vegetation in agricultural systems are potential ecosystem services providers because they offer semi-natural habitats for both below and above ground animal groups such as soil organisms, small mammals, birds and arthropods that are service supplying units. They are considered as a target area for enhancing farm biodiversity. Methodology: To explore the multiple potential benefits of these semi-natural habitats and to identify research trends and knowledge gaps globally, a review was carried out following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. A total of 235 publications from the year 2000 to 2016 in the Scopus and Web of Science databases were reviewed. Results: The literature showed an increasing trend in the number of published articles over time with European studies leading in the proportion of studies conducted, followed by North America, Asia, South America, Africa and Australia. Several functional groups of organisms were studied from field margin and non-crop vegetation around agricultural lands including natural enemies (37%), insect pests (22%), birds (17%), pollinators (16%), soil macro fauna (4%) and small mammals (4%). Ecosystem services derived from the field margin included natural pest regulation, pollination, nutrient cycling and reduced offsite erosion. Some field margin plants were reported to host detrimental crop pests, a major ecosystem dis-service, potentially leading to increased pest infestation in the field. Conclusion: The majority of studies revealed the importance of field margin and non-crop vegetation around arable fields in enhancing ecosystem biodiversity. Promotion of field margin plants that selectively enhance the population of beneficial organisms would support sustainable food security rather than simply boosting plant diversity. Our analyses also highlight that agro-ecological studies remain largely overlooked in some regions

Processing of the amyloid precursor protein and its paralogues amyloid precursor-like proteins 1 and 2

Alzheimer’s disease (AD) is a neurodegenerative disorder which is histopathologically characterised by amyloid plaques and neurofibrillary tangles. Amyloid plaques consist of the amyloid β-peptide (Aβ) that can form aggregates in the brain. Aβ is generated from the amyloid precursor protein (APP) through proteolytic cleavage. APP belongs to a conserved protein family that also includes the two paralogues, APP-like proteins 1 and 2 (APLP1 and APLP2). Despite the immense amount of research on APP, motivated by its implication in AD, the function of this protein family has not yet been determined. In this thesis, we have studied the expression and proteolytic processing of the APP protein family. Our results are consistent with previous findings that suggest a role for APP during neuronal development. Treatment of cells with retinoic acid (RA) resulted in increased synthesis. In addition, we observed that RA treatment shifted the processing of APP from the amyloidogenic to the non-amyloidogenic pathway. The proteins in the APP family have been hard to distinguish both with respect to function and proteolytic processing. However, for development of new drugs with APP processing enzymes as targets this is of great importance. Our studies suggest similarities, but also differences in the mechanism regulating the processing of the different paralogues. We found that brain-derived neurotrophic factor (BDNF) had different impact on the members of the APP family. Most interestingly, we also found that the mechanism behind the increased processing in response to IGF-1 was not identical between the homologous proteins. In summary, our results indicate that in terms of regulation APLP1 and APLP2 differ more from each other than from APP. Our studies open up the possibility of finding means to selectively block Aβ production without interfering with the processing and function of the paralogous proteins

Sortase A coupling of the recombinant partial silk proteins 4Rep-Srt and G-/G5-CT to understand the structure of silk fiber

Spindelsilke är ett intressant material på grund av dess biokompatibilitet och därav användning som biomaterial. Det är jämförbart med konstgjorda material när det gäller styrka och elasticitet, och i kombination med biokompatibiliteten, är spindelsilke eftertraktat inom det medicinska området. Sju olika spindeltrådar produceras av hjulspindeln och en kan användas som säkerhetslina vid flykt, och är därav mycket stark och töjbar. Säkerhetslinan består av två proteiner, så kallade stora ampullkörtel spidroiner 1 och 2 (MaSp1 & 2) eftersom de produceras i den stora ampullkörteln i spindeln. Dessa två proteiner är i sin tur sammansatta av tre delar, en repetitiv region i mitten och två icke-repetitiva regioner vid proteinets terminaler, N- och C-terminal domänerna. Att använda spindlar som huvudsakliga producenter av spindeltråd inom forskning är problematiskt och har fått forskare att vända sig till rekombinant produktion för uttryck av proteiner, mestadels i E. coli. Proteinstorleken är en begränsning vid produktion i E. coli, så forskare har uppfunnit ett mindre protein än MaSp som endast består av en mindre del av den repetitiva regionen och C-terminal domänen, så kallad 4RepCT. 4RepCT kan fortfarande bilda spindeltråd under fysiologiskt tillstånd och är biokompatibel. 4RepCT kan funktionaliseras med biomolekyler som kan ändra dess funktion, till exempel genom ett celladhesions motiv från fibronektin, som gör att 4RepCT kan binda till celler. I detta projekt siktar vi på att producera 4Rep-Srt och G-/G5-CT separat innan de kopplas med enzymet Sortase A. Sortase A känner igen en Sortase-tagg (LPXTG) på C-terminalen av ett protein (4Rep-Srt i detta projekt) och kopplar det till annat protein som har 1-5 glyciner på N-terminalen (G-/G5-CT i detta projekt). När proteinerna produceras separat kan G-/G5-CT uttryckas med 13C och 15N före kopplingen, och ge information om vilken del av 4Rep-G-/G5-CT-proteinet som är G-/G5-CT. Genom att känna till proteinets struktur, kan även dess egenskaper och funktioner förstås för att bättre bistå konstruktionen av proteiner för att erhålla biomolekyler med önskade funktioner.Spider silk is a material of interest due its biocompatibility and therefore usage as a biomaterial. Its comparability to man-made materials in terms of strength and elasticity, along its biocompatibility, makes it desirable in the medical field. Dragline silk is one of seven types of silk made by orb-web-weaving spiders which is used as a lifeline in case of predators to escape and is therefore very strong and extensible. The dragline silk is composed of two proteins, called major ampullate spidroin silk protein 1 and 2 (MaSp1 & 2) since it is made in the major ampullate gland in the spider. These two proteins are in turn composed of three parts, a repetitive region in the middle, and two nonrepetitive regions at the terminals, N- and C-terminal domain. Having spiders as main producers of silk when conducting research come with difficulties and have made researchers turn to recombinant production for expression, mostly in E. coli. However, the protein size is a limitation when expressing in E. coli so researchers has come up with a smaller protein than MaSp made up of only the repetitive region and the C-terminal domain, called 4RepCT. 4RepCT is still able to self-assemble into fibers under physiological-like conditions and is biocompatible. 4RepCT can be functionalized with other biomolecules that can alter its function, e.g., a cell-adhesion motif from fibronectin, allowing 4RepCT to bind to cells. In this project we aim to produce 4Rep-Srt and G-/G5-CT separately before coupling them with enzyme Sortase A. Sortase A recognizes a Sortase tag (LPXTG) on the C-terminus of one protein (4Rep-Srt in this project) and connects it to another protein that has 1-5 glycine’s on the N-terminus (G-/G5-CT in this project). When producing the proteins separately, we can express G-/G5-CT with 13C and 15N before coupling and then know which part of the 4Rep-G-/G5-CT protein is G-/G5-CT. By knowing the structure of the protein, protein features and functions can be discovered to better aid the engineering of proteins to get biomolecules with wanted functions

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