Temporal regulation of neuronal maturation in Caenorhabditis elegans. Katherine Olson Carter

ISBN: 9780549651888

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NOOKstudy eTextbook

157 pages


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Temporal regulation of neuronal maturation in Caenorhabditis elegans.  by  Katherine Olson Carter

Temporal regulation of neuronal maturation in Caenorhabditis elegans. by Katherine Olson Carter
| NOOKstudy eTextbook | PDF, EPUB, FB2, DjVu, audiobook, mp3, RTF | 157 pages | ISBN: 9780549651888 | 9.20 Mb

During postmitotic development, neurons perform migrations, extend axons, and initiate production of neurotransmitters, and mounting evidence suggests that these maturation events are temporally regulated. In C. elegans , a number of temporalMoreDuring postmitotic development, neurons perform migrations, extend axons, and initiate production of neurotransmitters, and mounting evidence suggests that these maturation events are temporally regulated. In C. elegans , a number of temporal patterning genes have been identified and ordered into the heterochronic pathway, which directs the timing of stage-specific cell divisions in the hypodermal V lineage.

The primary hypothesis of this dissertation research was that these heterochronic genes also controlled the timing of postmitotic neuronal maturation.-To test this prediction, candidate heterochronic mutants were crossed into a reporter strain that permitted visualization of C. elegans hermaphrodite specific neurons (HSNs). In wild-type animals, HSNs extend a single axon that grows ventrally and anteriorly during the L4 larval stage. Loss-of-function (1f) mutants for three heterochronic genes, the microRNA lin-4 and its targets lin-14 and lin-28, displayed striking temporal phenotypes in the HSNs.

In lin-4 (lf) animals, HSN axons were not detected in the majority of adults, while intrinsic over-expression of lin-4 orlf mutations in lin-14 or lin-28 resulted in precocious axon outgrowth during the L3 stage. Analysis of GFP reporter strains confirmed that all three genes were expressed and temporally regulated in the HSNs, and down-regulation of LIN-14 and LIN-28 required wild-type lin-4.

These genes could also temporally regulate HSN maturation more broadly, since lf mutations in all three genes exhibited changes in the timing of expression of tph-1, the serotonin-synthesis enzyme.-It is likely that heterochronic genes control distinct timed events through different mechanisms.

The heterochronic genes hbl-1 and lin-29 were identified as temporal regulators of axon outgrowth in the VC neurons, and hbl-1 could be targeted by lin-4 in these cells. In the HSNs, by contrast, hbl-1 was found to play an important role in spatial patterning, including cell migration.-My dissertation research presents a new role for microRNAs in regulating axon growth and timing of postmitotic maturation in the C. elegans nervous system. In addition to revealing the complexity of temporal patterning, it has also shown the surprising extent to which the same genes function in different contexts to control timed developmental events.



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