Search

Search Results

• 1. [Article] Mechanisms of Animal Diapause: Recent Developments from Nematodes, Crustaceans, Insects, and Fish

  Life cycle delays are beneficial for opportunistic species encountering suboptimal environments. Many animals display a programmed arrest of development (diapause) at some stage(s) of their development, ...

  Citation × Citation Citation Abstract Copy Title: Mechanisms of Animal Diapause: Recent Developments from Nematodes, Crustaceans, Insects, and Fish Author: Hand, Steven C., Denlinger, David L., Podrabsky, Jason E., Roy, Richard Year: 2016 Life cycle delays are beneficial for opportunistic species encountering suboptimal environments. Many animals display a programmed arrest of development (diapause) at some stage(s) of their development, and the diapause state may or may not be associated with some degree of metabolic depression. In this review, we will evaluate current advancements in our understanding of the mechanisms responsible for the remarkable phenotype, as well as environmental cues that signal entry and termination of the state. The developmental stage at which diapause occurs dictates and constrains the mechanisms governing diapause. Considerable progress has been made in clarifying proximal mechanisms of metabolic arrest and the signaling pathways like insulin/Foxo that control gene expression patterns. Overlapping themes are also seen in mechanisms that control cell cycle arrest. Evidence is emerging for epigenetic contributions to diapause regulation via small RNAs in nematodes, crustaceans, insects, and fish. Knockdown of circadian clock genes in selected insect species supports the importance of clock genes in the photoperiodic response that cues diapause. A large suite of chaperone-like proteins, expressed during diapause, protects biological structures during long periods of energy-limited stasis. More information is needed to paint a complete picture of how environmental cues are coupled to the signal transduction that initiates the complex diapause phenotype, as well as molecular explanations for how the state is terminated. Excellent examples of molecular memory in post-dauer animals have been documented in Caenorhabditis elegans It is clear that a single suite of mechanisms does not regulate diapause across all species and developmental stages. Title: Mechanisms of Animal Diapause: Recent Developments from Nematodes, Crustaceans, Insects, and Fish Author: Hand, Steven C., Denlinger, David L., Podrabsky, Jason E., Roy, Richard Year: 2016 Life cycle delays are beneficial for opportunistic species encountering suboptimal environments. Many animals display a programmed arrest of development (diapause) at some stage(s) of their development, and the diapause state may or may not be associated with some degree of metabolic depression. In this review, we will evaluate current advancements in our understanding of the mechanisms responsible for the remarkable phenotype, as well as environmental cues that signal entry and termination of the state. The developmental stage at which diapause occurs dictates and constrains the mechanisms governing diapause. Considerable progress has been made in clarifying proximal mechanisms of metabolic arrest and the signaling pathways like insulin/Foxo that control gene expression patterns. Overlapping themes are also seen in mechanisms that control cell cycle arrest. Evidence is emerging for epigenetic contributions to diapause regulation via small RNAs in nematodes, crustaceans, insects, and fish. Knockdown of circadian clock genes in selected insect species supports the importance of clock genes in the photoperiodic response that cues diapause. A large suite of chaperone-like proteins, expressed during diapause, protects biological structures during long periods of energy-limited stasis. More information is needed to paint a complete picture of how environmental cues are coupled to the signal transduction that initiates the complex diapause phenotype, as well as molecular explanations for how the state is terminated. Excellent examples of molecular memory in post-dauer animals have been documented in Caenorhabditis elegans It is clear that a single suite of mechanisms does not regulate diapause across all species and developmental stages. Close

• 2. [Article] Transcriptomic Analysis of Maternally Provisioned Cues for Phenotypic Plasticity in the Annual Killifish, <i>Austrofundulus limnaeus</i>

  Background: Genotype and environment can interact during development to produce novel adaptive traits that support life in extreme conditions. The development of the annual killifsh Austrofundulus limnaeus ...

  Citation × Citation Citation Abstract Copy Title: Transcriptomic Analysis of Maternally Provisioned Cues for Phenotypic Plasticity in the Annual Killifish, <i>Austrofundulus limnaeus</i> Author: Romney, Amie L., Podrabsky, Jason E. Year: 2017 Background: Genotype and environment can interact during development to produce novel adaptive traits that support life in extreme conditions. The development of the annual killifsh Austrofundulus limnaeus is unique among vertebrates because the embryos have distinct cell movements that separate epiboly from axis formation during early development, can enter into a state of metabolic dormancy known as diapause and can survive extreme environmental conditions. The ability to enter into diapause can be maternally programmed, with young females producing embryos that do not enter into diapause. Alternately, embryos can be programmed to “escape” from diapause and develop directly by both maternal factors and embryonic incubation conditions. Thus, maternally packaged gene products are hypothesized to regulate developmental trajectory and perhaps the other unique developmental characters in this species. Results: Using high-throughput RNA sequencing, we generated transcriptomic profles of mRNAs, long non-coding RNAs and small non-coding RNAs (sncRNAs) in 1–2 cell stage embryos of A. limnaeus. Transcriptomic analyses suggest maternal programming of embryos through alternatively spliced mRNAs and antisense sncRNAs. Comparison of these results to those of comparable studies on zebrafsh and other fshes reveals a surprisingly high abundance of transcripts involved in the cellular response to stress and a relatively lower expression of genes required for rapid transition through the cell cycle. Conclusions: Maternal programming of developmental trajectory is unlikely accomplished by diferential expression of diapause-specifc genes. Rather, evidence suggests a role for trajectory-specifc splice variants of genes expressed in both phenotypes. In addition, based on comparative studies with zebrafsh, the A. limnaeus 1–2 cell stage transcriptome is unique in ways that are consistent with their unique life history. These results not only impact our understanding of the genetic mechanisms that regulate entrance into diapause, but also provide insight into the epigenetic regulation of gene expression during development Title: Transcriptomic Analysis of Maternally Provisioned Cues for Phenotypic Plasticity in the Annual Killifish, <i>Austrofundulus limnaeus</i> Author: Romney, Amie L., Podrabsky, Jason E. Year: 2017 Background: Genotype and environment can interact during development to produce novel adaptive traits that support life in extreme conditions. The development of the annual killifsh Austrofundulus limnaeus is unique among vertebrates because the embryos have distinct cell movements that separate epiboly from axis formation during early development, can enter into a state of metabolic dormancy known as diapause and can survive extreme environmental conditions. The ability to enter into diapause can be maternally programmed, with young females producing embryos that do not enter into diapause. Alternately, embryos can be programmed to “escape” from diapause and develop directly by both maternal factors and embryonic incubation conditions. Thus, maternally packaged gene products are hypothesized to regulate developmental trajectory and perhaps the other unique developmental characters in this species. Results: Using high-throughput RNA sequencing, we generated transcriptomic profles of mRNAs, long non-coding RNAs and small non-coding RNAs (sncRNAs) in 1–2 cell stage embryos of A. limnaeus. Transcriptomic analyses suggest maternal programming of embryos through alternatively spliced mRNAs and antisense sncRNAs. Comparison of these results to those of comparable studies on zebrafsh and other fshes reveals a surprisingly high abundance of transcripts involved in the cellular response to stress and a relatively lower expression of genes required for rapid transition through the cell cycle. Conclusions: Maternal programming of developmental trajectory is unlikely accomplished by diferential expression of diapause-specifc genes. Rather, evidence suggests a role for trajectory-specifc splice variants of genes expressed in both phenotypes. In addition, based on comparative studies with zebrafsh, the A. limnaeus 1–2 cell stage transcriptome is unique in ways that are consistent with their unique life history. These results not only impact our understanding of the genetic mechanisms that regulate entrance into diapause, but also provide insight into the epigenetic regulation of gene expression during development Close