Titel Deelnemers "Korte inhoud" "Expansion, in vivo-ex vivo cycling, and genetic manipulation of primary human hepatocytes" "Eleftherios Michailidis, Koen Vercauteren, Liliana Mancio-Silva, Linda Andrus, Cyprien Jahan, Inna Ricardo-Lax, Chenhui Zou, Mohammad Kabbani, Paul Park, Corrine Quirk, Christina Pyrgaki, Brandon Razooky, Lieven Verhoye, Irene Zoluthkin, Wei-Yu Lu, Stuart J Forbes, Luis Chiriboga, Neil D Theise, Roland W. Herzog, Hiroshi Suemizu, William M Schneider, Amir Shlomai, Philip Meuleman, Sangeeta N Bhatia, Charles M. Rice, Ype P de Jong" "Primary human hepatocytes (PHHs) are an essential tool for modeling drug metabolism and liver disease. However, variable plating efficiencies, short lifespan in culture, and resistance to genetic manipulation have limited their use. Here, we show that the pyrrolizidine alkaloid retrorsine improves PHH repopulation of chimeric mice on average 10-fold and rescues the ability of even poorly plateable donor hepatocytes to provide cells for subsequent ex vivo cultures. These mouse-passaged (mp) PHH cultures overcome the marked donor-to-donor variability of cryopreserved PHH and remain functional for months as demonstrated by metabolic assays and infection with hepatitis B virus and Plasmodium falciparum mpPHH can be efficiently genetically modified in culture, mobilized, and then recultured as spheroids or retransplanted to create highly humanized mice that carry a genetically altered hepatocyte graft. Together, these advances provide flexible tools for the study of human liver disease and evaluation of hepatocyte-targeted gene therapy approaches." "Genetic and pharmacological manipulation of glial glutamate transporters does not alter infection-induced seizure activity" "Jaycie L Loewen, Giulia Albertini, E Jill Dahle, Hideyo Sato, Ilse Smolders, Ann Massie, Karen S Wilcox" "The contribution of glial transporters to glutamate movement across the membrane has been identified as a potential target for anti-seizure therapies. Two such glutamate transporters, GLT-1 and system xc-, are expressed on glial cells, and modulation of their expression and function have been identified as a means by which seizures, neuronal injury, and gliosis can be reduced in models of brain injury. While GLT-1 is responsible for the majority of glutamate uptake in the brain, system xc- releases glutamate in the extracellular cleft in exchange for cystine and represents as such the major source of hippocampal extracellular glutamate. Using the Theiler's Murine Encephalomyelitis Virus (TMEV) model of viral-induced epilepsy, we have taken two well-studied approaches, one pharmacological, one genetic, to investigate the potential role(s) of GLT-1 and system xc- in TMEV-induced pathology. Our findings suggest that the methods we utilized to modulate these glial transporters, while effective in other models, are not sufficient to reduce the number or severity of behavioral seizures in TMEV-infected mice. However, genetic knockout of xCT, the specific subunit of system xc-, may have cellular effects, as we observed a slight decrease in neuronal injury caused by TMEV and an increase in astrogliosis in the CA1 region of the hippocampus. Furthermore, xCT knockout caused an increase in GLT-1 expression selectively in the cortex. These findings have significant implications for both the characterization of the TMEV model as well as for future efforts to discover novel and effective anti-seizure drugs." "Development of strategies for genetic manipulation and fine-tuning of a chloroplast retrograde signal 3′-phosphoadenosine 5′-phosphate" "Su Yin Phua, Wannarat Pornsiriwong, Kai Xun Chan, Gonzalo M. Estavillo, Barry J. Pogson" "Development and validation of flexible system for selective genetic manipulation of astrocytes in wild-type mouse" "Filip de Vin, Matthew Holt" "Transformable bending-active structures: manipulating elastic deformation in kinetic and rapidly assembled structures" "Ant colony optimisation-based radiation pattern manipulation algorithm for electronically steerable array radiator antennas" "Jan Aelterman, Roald Goossens, Frederick Declercq, Hendrik Rogier" "A new algorithm for manipulating the radiation pattern of Electronically Steerable Array Radiator Antennas is proposed. A continuous implementation of the Ant Colony Optimisation (ACO) technique calculates the optimal impedance values of reactances loading different parasitic radiators placed in a circle around a centre antenna. By proposing a method to obtain a suitable sampling frequency of the radiation pattern for use in the optimisation algorithm and by transforming the reactance search space into the search space of associated phases, special care was taken to create a fast and reliable implementation, resulting in an approach that is suitable for real-time implementation. The authors compare their approach to analytical techniques and optimisation algorithms for calculating these reactances. Results show that the method is able to calculate near-optimal solutions for gain optimisation and side lobe reduction." "Thermal manipulation during incubation of broilers: Implications for heat resilience, performance and behaviour" "Sara Verlinden" "The poultry production sector is being challenged and a lot of pressure is placed on its producers. Together with the increasing demand for animal welfare, there are many and necessary restrictions and environmental standards. Since most of the poultry production takes place in warm climate areas such as China, Brazil, Latin America and the Asia-Pacific regions, both outdoor as indoor bred animals are threatened by rising temperatures. Meat-type chickens, called broilers, are more sensitive to heat stress than egg-type chickens, called layers, due to their higher body weight and faster growth. Thermal discomfort from the heat poses a serious challenge for sustainable broiler production. Even in more moderate climate regions such as North America and Europe, heat stress occurs more often due to the increase in the number and intensity of heat waves. Several heat stress alleviating techniques are available ranging from management to genetic strategies. One of the more promising strategies is a process called thermal manipulation in which broiler eggs are exposed to high temperatures during their incubation. Epigenetic adaptations will prepare these animals for later life when challenged by heat and this by lowering their body temperature and basal metabolism. Despite the plethora of research conducted, it appears that thermal manipulation affects not only the thermoregulatory system but also performance parameters such as chick quality, hatchability and growth. Contradicting effects are found for similar or even identical treatments indicating the lack of knowledge about the functioning of thermal manipulations and the thermoregulatory system. Additionally, it has been shown that thermal manipulation influences fear and social behaviour in reptiles and the first indications in layers are found. Therefore, it is important to assess these effects as well. In this work, the potential of thermal manipulation is further explored by looking into the mechanisms behind it, investigated from a molecular level as well as evaluating its effects on fear and social behaviour. All of this while monitoring performance parameters. In the first part of this work, the mRNA expression levels of 22 potentially thermosensitive ion channels are measured in the brains of developing broiler embryos. Several of these channels were TRP (transient receptor potential) ion channels as these are known to be thermosensitive and responsible for peripheral and brain temperature sensing in mammals. However, very limited research is conducted in poultry. To study these channels in broilers, eggs were incubated in different temperature profiles (T1 and T2) during which brain samples were collected from incubation day 15 until hatch. We found 8 of the ion channels to be affected by treatment or by the interaction of treatment and day. In general, the expression of potentially heat sensitive ion channels was increased in both T1 and T2. However, the more intense T2 treatment managed to change the expression of more channels than T1. It seems that both treatments had an acclimatisation effect, probably as a result of epigenetic mechanisms, to adapt the animal to a life in which heat stress can occur. As validation, a heat challenge test in later life showed a numerical lowering for the number of mortalities for both T1 and T2, although the difference was not statistically significant. To evaluate the effects of T1 and T2 on fear and social behaviour, seven behaviour tests were conducted throughout the rearing period of 42 days. Both T1 and T2 increased social stress during isolation with T1's effects visible from week 4 onwards, whereas T2 increased the stress levels only in week 6. Interestingly, the social motivation to be with conspecifics of T2 males was increased from week 1 onwards. Prosocial behaviours are crucial for good animal welfare, especially as a high sociality can aid in coping with other stressors. The behaviour effects of two cold incubation profiles were also researched with one referred to as IT treatment, designed to increase performance variables, and the other one referred to as NT, designed to represent a nature like incubation. IT was found to increase the fear of a novel environment whereas NT males showed increased levels of social stress when in isolation. For all treatments, a variety of effects were found on performance parameters. The same as in literature studies. It is likely that the background of the broiler breeder farm and age of the breeders, the exact storage conditions and uncontrolled elements in the incubators such as humidity, O2 and CO2 interfered with the results. Even though some treatments had a negative effect on hatch performance such as lowering hatchability or chick quality, none of the treatments affected their growth during the full rearing period. All in all, treatment T2 seems like a potentially commercially applicable treatment due to its promising heat resilience improving effects, improvements in social motivation and no decrease in performance. Still, many questions are remaining especially concerning the more fundamental research on thermal manipulation, thermosensitivity, integration of signals etc. Epigenetic research is just starting to elucidate further mechanisms behind thermoregulation in general and the way thermal manipulation influences it. Many opportunities remain open in this field of research. The combination of epigenetic studies with computer supported data analysis such as Precision livestock farming techniques analysing biological data in real-time could be valuable for future monitoring and control of the incubation process concerning its temperature profile." "Optogenetic manipulation of neural activity in C. elegans: From synapse to circuits and behaviour" "Steven Husson" "The emerging field of optogenetics allows for optical activation or inhibition of excitable cells. In 2005, optogenetic proteins were expressed in the nematode Caenorhabditis elegans for the first time. Since then, C. elegans has served as a powerful platform upon which to conduct optogenetic investigations of synaptic function, circuit dynamics and the neuronal basis of behaviour. The C. elegans nervous system, consisting of 302 neurons, whose connectivity and morphology has been mapped completely, drives a rich repertoire of behaviours that are quantifiable by video microscopy. This model organism's compact nervous system, quantifiable behaviour, genetic tractability and optical accessibility make it especially amenable to optogenetic interrogation. Channelrhodopsin-2 (ChR2), halorhodopsin (NpHR/Halo) and other common optogenetic proteins have all been expressed in C. elegans. Moreover, recent advances leveraging molecular genetics and patterned light illumination have now made it possible to target photoactivation and inhibition to single cells and to do so in worms as they behave freely. Here, we describe techniques and methods for optogenetic manipulation in C. elegans. We review recent work using optogenetics and C. elegans for neuroscience investigations at the level of synapses, circuits and behaviour." "Chemogenetic manipulation of astrocyte activity at the synapse- a gateway to manage brain disease" "Lut Arckens" "Astrocytes are the major glial cell type in the central nervous system (CNS). Initially regarded as supportive cells, it is now recognized that this highly heterogeneous cell population is an indispensable modulator of brain development and function. Astrocytes secrete neuroactive molecules that regulate synapse formation and maturation. They also express hundreds of G protein-coupled receptors (GPCRs) that, once activated by neurotransmitters, trigger intracellular signalling pathways that can trigger the release of gliotransmitters which, in turn, modulate synaptic transmission and neuroplasticity. Considering this, it is not surprising that astrocytic dysfunction, leading to synaptic impairment, is consistently described as a factor in brain diseases, whether they emerge early or late in life due to genetic or environmental factors. Here, we provide an overview of the literature showing that activation of genetically engineered GPCRs, known as Designer Receptors Exclusively Activated by Designer Drugs (DREADDs), to specifically modulate astrocyte activity partially mimics endogenous signalling pathways in astrocytes and improves neuronal function and behavior in normal animals and disease models. Therefore, we propose that expressing these genetically engineered GPCRs in astrocytes could be a promising strategy to explore (new) signalling pathways which can be used to manage brain disorders. The precise molecular, functional and behavioral effects of this type of manipulation, however, differ depending on the DREADD receptor used, targeted brain region and timing of the intervention, between healthy and disease conditions. This is likely a reflection of regional and disease/disease progression-associated astrocyte heterogeneity. Therefore, a thorough investigation of the effects of such astrocyte manipulation(s) must be conducted considering the specific cellular and molecular environment characteristic of each disease and disease stage before this has therapeutic applicability." "Manipulation of Arthropod Sex Determination by Endosymbionts: Diversity and Molecular Mechanisms" "Wen-Juan Ma, F. Vavre" "Arthropods exhibit a large variety of sex determination systems both at the chromosomal and molecular level. Male heterogamety, female heterogamety, and haplodiploidy occur frequently, but partially different genes are involved. Endosymbionts, such as Wolbachia, Cardinium,Rickettsia, and Spiroplasma, can manipulate host reproduction and sex determination. Four major reproductive manipulation types are distinguished: cytoplasmic incompatibility, thelytokous parthenogenesis, male killing, and feminization. In this review, the effects of these manipulation types and how they interfere with arthropod sex determination in terms of host developmental timing, alteration of sex determination, and modification of sexual differentiation pathways are summarized. Transitions between different manipulation types occur frequently which suggests that they are based on similar molecular processes. It is also discussed how mechanisms of reproductive manipulation and host sex determination can be informative on each other, with a special focus on haplodiploidy. Future directions on how the study of endosymbiotic manipulation of host reproduction can be key to further studies of arthropod sex determination are shown."