Project description:Mesial temporal lobe epilepsy (MTLE) is the most common medically refractory epilepsy syndrome; kainic acid (KA) induced seizures have been studied as a MTLE model as limbic seizures produced by systemic injections of KA result in a distinctive pattern of neurodegeneration in the hippocampus that resembles human hippocampal sclerosis. In our "2-hit" seizure model, animals subjected to seizures during week 2 of life become more susceptible to seizures later in life and sustain extensive hippocampal neuronal injury after second KA seizures in adulthood. Using high-density oligonucleotide gene arrays, we began to elucidate the molecular basis of this priming effect of early-life seizures and of the age-specific neuroprotection against seizure-induced neuronal injury. We seek to identify target genes for epileptogenesis and cell death by selecting transcripts that are differentially regulated at various times in the P15 and P30 hippocampus. To screen for and identify candidate genes responsible for epileptogenesis and seizure-induced cell death. We hypothesize that active process of cell death signaling and long-term synaptic changes leading to chronic epilepsy is mediated by distinct transcriptional responses in mature brain that are different from those in immature brain. We will select for transcripts that are highly regulated at 1, 6, 24, 72 and 240 hours (h) after KA-induced seizures at P30 compared to P15. These differentially regulated genes will serve as potential target genes for therapeutic intervention. Highly regulated genes identified in our array analysis will then be confirmed by real-time quantitative reverse transcriptase-polymerase chain reaction (RT-PCR). Causative roles of select genes will be directly tested by gene silencing using RNA interference technology or by gene delivery using viral vectors.
Project description:Primary cortical neurons were isolated from E15 mice and after 5 days in vitro were untreated or treated for 24 h with mesenchymal stem cell conditioned medium and then untreated or treated for a further 24 h with NMDA. Neuron gene expression was profiled and compared between the four different conditions (neurons, neurons+MSC cm, neurons+NMDA, neurons+MSC cm+NMDA) to investigate the molecular mechanisms of MSC neuroprotection. Mesenchymal stem cells (MSC) promote functional recovery in experimental models of central nervous system (CNS) pathology and are currently being tested in clinical trials for stroke, multiple sclerosis and CNS injury. Their beneficial effects are attributed to activation of endogenous CNS repair processes and immune regulation but their mechanisms of action are poorly understood. Here we investigated the neuroprotective effects of MSC in simplified MSC-neuron co-culture systems and in mice using models of glutamate excitotoxicity. MSC protected primary cortical neurons against glutamate (NMDA) receptor-induced death and conditioned medium from MSC (MSC cm), but not control NIH3T3 cells, was sufficient for this effect. MSC cm neuroprotection in mouse cortical neurons was reduced by neutralizing antibodies to bFGF and associated with altered gene expression in neurons towards an immature phenotype as well as reduced neuronal Grin1, Grin2a and Grin2b mRNA levels in response to NMDA stimulation. Further, MSC cm neuroprotection in rat retinal ganglion cells was associated with absence of glutamate-induced calcium influx. Adoptive transfer of EGFP+MSC in a mouse kainic acid seizure model reduced CA3 neuron damage and hippocampal astrocytosis and resulted in the increased expression of neuronal genes that are upregulated by MSC cm, Bmi1, Ddx4, Ezh1, in the hippocampus. These results show that MSC mediate direct neuroprotection against glutamate excitotoxicity by secreting bFGF, reducing glutamate receptor expression and function and altering neuron gene expression towards an immature pattern, and provide evidence for a link between the therapeutic effects of MSC and the activation of endogenous repair processes following CNS injury. In vitro cultures primary cortical neurons from mice were protected from glutamate excitotoxicity when pre-treated with MSC cm. Global gene expression changes induced in neurons before and after treatment with MSC cm and/or NMDA were investigated using a cDNA spotted macroarray filter. Four samples were analysed in duplicate: neurons alone (untreated), neurons+MSC cm, neurons+NMDA, neurons+MSC cm+NMDA.
Project description:Few studies have assessed the patterns of parasite populations of rodents over a longitudinal gradient in Chile. In this work, the gastrointestinal helminthic fauna of invasive rodents in Chile was examined to assess the association between their presence/absence and abundance with latitude, host sex, and host body condition, and to assess the coexistence and correlation of the abundance between parasite species. Rodents were obtained from 20 localities between 33 and 43°S. Helminths were extracted from the gastrointestinal tract and identified morphologically. Overall, 13 helminth taxa were obtained. The most frequently identified parasite species was Heterakis spumosa, and the most abundant was Syphacia muris, while Physaloptera sp. was the most widely distributed. No locality presented with a coexistence that was different from that expected by chance, while the abundance of five helminthic species correlated with the abundance of another in at least one locality, most likely due to co-infection rather than interaction. Host sex was associated with parasite presence or abundance, and female sex-biased parasitism was notably observed in all cases. Body condition and latitude presented either a positive or negative association with the presence or abundance of parasites depending on the species. It is notable that the likely native Physaloptera sp. is widely distributed among invasive rodents. Further, gravid females were found, suggesting spillback of this species to the native fauna. The low frequency and abundance of highly zoonotic hymenolepid species suggest that rodents are of low concern regarding gastrointestinal zoonotic helminths.
Project description:Primary cortical neurons were isolated from E15 mice and after 6 days in vitro were untreated or treated for 24 h with mesenchymal stem cell conditioned medium. Neuron gene expression was profiled and compared between the two different conditions (neurons and neurons+MSC cm) to investigate the molecular mechanisms of MSC neuroprotection. Mesenchymal stem cells (MSC) promote functional recovery in experimental models of central nervous system (CNS) pathology and are currently being tested in clinical trials for stroke, multiple sclerosis and CNS injury. Their beneficial effects are attributed to the activation of endogenous CNS protection and repair processes as well as immune regulation but their mechanisms of action are poorly understood. Here we investigated the neuroprotective effects of mouse MSC in rodent MSC-neuron co-cultures and mice using models of glutamate excitotoxicity. A 24 hr pre-culture of mouse primary cortical neurons with MSC protected them against glutamate (NMDA) receptor-induced death and conditioned medium from MSC (MSC CM) was sufficient for this effect. Protection by MSC CM was associated with reduced mRNA levels of genes encoding NMDA receptor subunits, and increased levels for genes associated with non-neuronal and stem cell types, as shown by RT-PCR and cDNA microarray analyses. Changes in gene expression were not associated with alterations in cell lineage representation within the cultures. Further, MSC CM-mediated neuroprotection in rat retinal ganglion cells was associated with reduced glutamate-induced calcium influx. The adoptive transfer of EGFP+MSC in a mouse kainic acid epilepsy model also provided neuroprotection against glutamate excitotoxicity in vivo, as shown by reduced neuron damage and glial cell activation in the hippocampus. These results show that MSC mediate direct neuroprotection by reducing neuronal sensitivity to glutamate receptor ligands and altering gene expression, and suggest a link between the therapeutic effects of MSC and the activation of cell plasticity in the damaged CNS.
Project description:The Norway rat has important impacts on our life. They are amongst the most used research subjects, resulting in ground-breaking advances. At the same time, wild rats live in close association with us, leading to various adverse interactions. In face of this relevance, it is surprising how little is known about their natural behaviour. While recent laboratory studies revealed their complex social skills, little is known about their social behaviour in the wild. An integration of these different scientific approaches is crucial to understand their social life, which will enable us to design more valid research paradigms, develop more effective management strategies, and to provide better welfare standards. Hence, I first summarise the literature on their natural social behaviour. Second, I provide an overview of recent developments concerning their social cognition. Third, I illustrate why an integration of these areas would be beneficial to optimise our interactions with them.
Project description:BackgroundMurine kobuviruses (MuKV) are newly recognized picornaviruses first detected in murine rodents in the USA in 2011. Little information on MuKV epidemiology in murine rodents is available. Therefore, we conducted a survey of the prevalence and genomic characteristics of rat kobuvirus in Guangdong, China.ResultsFecal samples from 223 rats (Rattus norvegicus) were collected from Guangdong and kobuviruses were detected in 12.6% (28) of samples. Phylogenetic analysis based on partial 3D and complete VP1 sequence regions showed that rat kobuvirus obtained in this study were genetically closely related to those of rat/mouse kobuvirus reported in other geographical areas. Two near full-length rat kobuvirus genomes (MM33, GZ85) were acquired and phylogenetic analysis of these revealed that they shared very high nucleotide/amino acids identity with one another (95.4%/99.4%) and a sewage-derived sequence (86.9%/93.5% and 87.5%/93.7%, respectively). Comparison with original Aichivirus A strains, such human kobuvirus, revealed amino acid identity values of approximately 80%.ConclusionOur findings indicate that rat kobuvirus have distinctive genetic characteristics from other Aichivirus A viruses. Additionally, rat kobuvirus may spread via sewage.