Biology subjects

Rieger, I.

Publications and source records attributed to Rieger, I..

3 recordsLinked to original sources

bioRxiv2024

Perception of Temperature Even in the Absence of Actual Change is Sufficient to Drive Transgenerational Epigenetic Inheritance

Can processes occurring in one individuals nervous system influence the physiology of the descendants? Here, we explored the hypothesis that parents sensation or perception of environmental cues can influence their offspring, extending across many subsequent generations. We show that in Caenorhabditis elegans, temperature perception by the AFD thermosensory neurons initiates a signaling cascade that, directly or indirectly, induces transgenerational changes in RNAi factors, small RNAs, and their target genes. Moreover, we identify secreted factors that enable this neuron-to-germline communication and trace the path of the epigenetic signal. We further model the process mathematically, and the model yields new predictions that we validate experimentally: blocking sensory input dampens RNAi inheritance initiated by exogenous double-stranded RNA (dsRNA). Together, our results demonstrate that sensory perception is sufficient to influence small RNA-mediated heritable gene expression memory.

genetics↗

bioRxiv2024

A Tunable and Druggable Mechanism to Delay Forgetting of Olfactory Memories in C. elegans

The poet W.B Yeats wrote that "All that is personal soon rots, it must be packed in ice or salt". Here we show that in Caenorhabditis elegans nematodes, simple animals with just 302 neurons, memories are preserved on ice and in lithium salt. C. elegans nematodes can form associative memories, which are typically forgotten quickly. We discovered that when placed on ice, worms delay forgetting of specific olfactory memories by at least 8-fold. Delayed forgetting was canceled completely when the worms were gradually adapted to low temperatures, owing to a genetically-encoded program that turns acclimated worms cold-tolerant. RNA-seq, mutant analyses, and pharmacological assays revealed that regulation of membrane properties switches cold-induced delayed forgetting ON and OFF, and, remarkably, that lithium delays forgetting only in cold-sensitive but not cold-tolerant worms. We found that downregulation of the diacylglycerol pathway in the AWC sensory neurons is essential for lithium-mediated delayed forgetting, and using neuronal activity recordings located the memory trace to the downstream AIY interneurons. We suggest that the awesome genetic tractability of C. elegans might be harnessed to study the effects of lithium and cold temperatures on the brain, why it influences psychiatric disorders, and even more fundamentally how memory is stored and lost.

neuroscience↗

bioRxiv2023

Nucleus-Independent Transgenerational Small RNA Inheritance in C. elegans

Studies using C. elegans nematodes demonstrated that, against the dogma, animals can transmit epigenetic information transgenerationally. While it is now clear that in these worms ancestral RNA interference (RNAi) responses continue to regulate gene expression for many generations, it is still debated whether the primary agent that perpetuates heritable silencing is RNA or chromatin, and whether the information is communicated to the next generation inside or outside of the nucleus. Here we take advantage of the tractability of gene-specific double stranded RNA-induced heritable silencing to answer these questions. We demonstrate that RNAi can be inherited independently of any changes to the chromatin or any other nuclear factors via mothers that are genetically engineered to transmit only their ooplasm but not the oocytes nuclei to the next generation. Nucleus-independent RNA inheritance depends on ZNFX-1, an RNA-binding germ granule resident protein. We find that upon manipulation of normal germ granules functions (in pptr-1 mutants) nucleus-independent RNA inheritance becomes stronger, and can occur even in znfx-1 mutants. Utilizing RNA sequencing, chimeric worms, and sequence polymorphism between different C. elegans isolates, we identify endogenous small RNAs which, similarly to exogenous siRNAs, are inherited in a nucleus-independent manner. From an historical perspective, nucleus-independent inheritance of small RNAs might be regarded as partial vindication of discredited cytoplasmic inheritance theories from the 19th century, such as Darwins "pangenesis" theory.

genetics↗