Our understanding of cellular mechanisms by which animals regulate their response to starvation is limited despite the close relevance of the problem to major human health issues. L1 diapause of Caenorhabditis elegans, where newly hatched first stage larval arrested in response to food-less environment, is an excellent system to study the problem. We found through genetic manipulation and lipid analysis that ceramide biosynthesis, particularly those with longer fatty acid side chains, critically impacts animal survival during L1 diapause. Genetic and expression analyses indicate that ceramide likely regulate this response by affecting gene expression and activity in multiple regulatory pathways known to regulate starvation-induced stress, including the insulin-IGF-1 signaling (IIS) pathway, Rb and other pathways that mediate pathogen/toxin/oxidative stress responses. These findings provide an important insight into the roles of sphingolipid metabolism in not only starvation response but also aging and food-response related human health problems.
Starvation-Induced Stress Response Is Critically Impacted by Ceramide Levels in Caenorhabditis elegans.
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View SamplesThe first embryonic cell divisions rely on maternally stored mRNA and proteins. The zygotic genome is initially transcriptionally silenced and activated later in a process called zygotic genome activation (ZGA). ZGA in any species is still a poorly understood process; the timing of transcription onset is controversial and the identity of the first transcribed genes unclear. Zebrafish, Danio rerio, is a rapidly developing vertebrate model, which is accessible to experimentation and global studies before, during and after ZGA. Overall design: To accurately determine the onset of ZGA and to identify the first transcripts in zebrafish, we developed a metabolic labeling method, utilizing the ribonucleotide analog 4-thio-UTP, which allows efficient and specific affinity purification of newly transcribed RNA. Using deep sequencing, we characterized the onset of transcription in zebrafish embryos at 128-, 256-, and 512-cell stages. We identified 592 nuclear-encoded zygotically transcribed genes, comprising 670 transcript isoforms. Mitochondrial genomes were highly transcribed at all time points. Further, bioinformatic analysis revealed an enrichment of transcription factors and miRNAs among the newly transcribed genes, suggesting mechanistic roles for the early genes that are required to activate subsequent gene expression programs in development. Interestingly, analysis of gene-architecture revealed that zygotically transcribed genes are often intronless and short, reducing transcription and processing time of the transcript. The newly generated dataset enabled us to compare zygotically transcribed genes over a broad phylogenetic distance with fly and mouse early zygotic genes. This analysis revealed that short gene length is a common characteristic for early zygotically expressed genes. However, we detected a poor level of overlap for shared orthologs.
The earliest transcribed zygotic genes are short, newly evolved, and different across species.
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View SamplesDendritic cells (DCs) and macrophages (MPs) are important for immunological homeostasis in the colon. We found that F4/80hi CX3CR1hi (CD11b+CD103-) cells account for 80% of mouse colonic lamina propria (cLP) MHC-IIhi cells. Both CD11c+ and CD11c- cells within this population were identified as MPs based on multiple criteria, including a MP transcriptome revealed by microarray analysis. These MPs constitutively released high levels of IL-10 at least partially in response to the microbiota via an MyD88-independent mechanism. In contrast, cells expressing low to intermediate levels of F4/80 and CX3CR1 were identified as DCs, based on phenotypic and functional analysis and comprise three separate CD11chi cell populations: CD103+CX3CR1-CD11b- DCs, CD103+CX3CR1-CD11b+ DCs and CD103-CX3CR1intCD11b+ DCs. In non-inflammatory conditions, Ly6Chi monocytes differentiated primarily into CD11c+, but not CD11c- MPs. In contrast, during colitis, Ly6Chi monocytes massively invaded the colon and differentiated into pro-inflammatory CD103-CX3CR1intCD11b+ DCs, which produced high levels of IL-12, IL-23, iNOS and TNF. These findings demonstrate the dual capacity of Ly6Chi blood monocytes to differentiate into either regulatory MPs or inflammatory DCs in the colon, and that the balance of these immunologically antagonistic cell types is dictated by microenvironmental conditions.
Inflammation switches the differentiation program of Ly6Chi monocytes from antiinflammatory macrophages to inflammatory dendritic cells in the colon.
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View SamplesIn development, timing is of the utmost importance, and the timing of various developmental processes are often changed during evolution. During human evolution sexual maturation has been delayed relative to other primates and this may have played a critical role for both the increase of human brain size and the rise of human-specific cognitive traits .
Transcriptional neoteny in the human brain.
Sex, Age, Specimen part
View SamplesIn development, timing is of the utmost importance, and the timing of various developmental processes are often changed during evolution. During human evolution sexual maturation has been delayed relative to other primates and this may have played a critical role for both the increase of human brain size and the rise of human-specific cognitive traits .
Transcriptional neoteny in the human brain.
Sex, Age, Specimen part
View SamplesIn development, timing is of the utmost importance, and the timing of various developmental processes are often changed during evolution.
Transcriptional neoteny in the human brain.
Sex, Age, Specimen part
View SamplesBipolar Disorder (BD) is a complex neuropsychiatric disorder that is characterized by intermittent episodes of mania and depression and, without treatment, 15% of patients commit suicide1. Hence, among all diseases, BD has been ranked by the WHO as a top disorder of morbidity and lost productivity2. Previous neuropathological studies have revealed a series of alterations in the brains of BD patients or animal models3, such as reduced glial cell number in the patient prefrontal cortex4, up-regulated activities of the PKA/PKC pathways5-7, and changes in dopamine/5-HT/glutamate neurotransmission systems8-11. However, the roles and causation of these changes in BD are too complex to exactly determine the pathology of the disease; none of the current BD animal models can recapitulate both the manic and depressive phenotypes or spontaneous cycling of BD simultaneously12,13. Furthermore, while some patients show remarkable improvement with lithium treatment, for yet unknown reasons, other patients are refractory to lithium treatment. Therefore, developing an accurate and powerful biological model has been a challenge for research into BD. The development of induced pluripotent stem cell (iPSC) technology has provided such a new approach. Here, we developed a human BD iPSC model and investigated the cellular phenotypes of hippocampal dentate gyrus neurons derived from the patient iPSCs. Using patch clamp recording, somatic Ca2+ imaging and RNA-seq techniques, we found that the neurons derived from BD patients exhibited hyperactive action potential (AP) firing, up-regulated expression of PKA/PKC/AP and mitochondria-related genes. Moreover, lithium selectively reversed these alterations in the neurons of patients who responded to lithium treatment. Therefore, hyper-excitability is one endophenotype of BD that is probably achieved through enhancement in the PKA/PKC and Na+ channel signaling systems, and our BD iPSC model can be used to develop new therapies and drugs aimed at clinical treatment of this disease. Overall design: total RNAseq from neurons generated from BD patient-specific iPS cells
Differential responses to lithium in hyperexcitable neurons from patients with bipolar disorder.
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View SamplesThis SuperSeries is composed of the SubSeries listed below.
Integrative DNA methylation and gene expression analyses identify DNA packaging and epigenetic regulatory genes associated with low motility sperm.
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View SamplesThis SuperSeries is composed of the SubSeries listed below.
Transcriptional profiles underlying parent-of-origin effects in seeds of Arabidopsis thaliana.
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View SamplesCrossing plants of the same species but different ploidies can have dramatic effects on seed growth, but little is known about the alterations to transcriptional programmes responsible for this. Parental genomic imbalance particularly affects proliferation of the endosperm, with an increased ratio of paternally to maternally contributed genomes (paternal excess) associated with overproliferation, while maternal excess inhibits endosperm growth. One interpretation is that interploidy crosses disrupt the balance in the seed of active copies of parentally imprinted genes. This is supported by the observation that mutations in imprinted FIS-class genes of Arabidopsis thaliana share many features of the paternal excess phenotype. Here we investigated gene expression underlying parent-of-origin effects in Arabidopsis through transcriptional profiling of siliques generated by interploidy crosses and FIS-class mutants.
Transcriptional profiles underlying parent-of-origin effects in seeds of Arabidopsis thaliana.
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