A Highly Conserved Poc1 Protein Characterized in Embryos of the Hydrozoan Clytia hemisphaerica: Localization and Functional Studies

Poc1 (Protein of Centriole 1) proteins are highly conserved WD40 domain-containing centriole components, well characterized in the alga Chlamydomonas, the ciliated protazoan Tetrahymena, the insect Drosophila and in vertebrate cells including Xenopus and zebrafish embryos. Functions and localizations related to the centriole and ciliary axoneme have been demonstrated for Poc1 in a range of species. The vertebrate Poc1 protein has also been reported to show an additional association with mitochondria, including enrichment in the specialized “germ plasm” region of Xenopus oocytes. We have identified and characterized a highly conserved Poc1 protein in the cnidarian Clytia hemisphaerica. Clytia Poc1 mRNA was found to be strongly expressed in eggs and early embryos, showing a punctate perinuclear localization in young oocytes. Fluorescence-tagged Poc1 proteins expressed in developing embryos showed strong localization to centrioles, including basal bodies. Anti-human Poc1 antibodies decorated mitochondria in Clytia, as reported in human cells, but failed to recognise endogenous or fluorescent-tagged Clytia Poc1. Injection of specific morpholino oligonucleotides into Clytia eggs prior to fertilization to repress Poc1 mRNA translation interfered with cell division from the blastula stage, likely corresponding to when neosynthesis normally takes over from maternally supplied protein. Cell cycle lengthening and arrest were observed, phenotypes consistent with an impaired centriolar biogenesis or function. The specificity of the defects could be demonstrated by injection of synthetic Poc1 mRNA, which restored normal development. We conclude that in Clytia embryos, Poc1 has an essentially centriolar localization and function

Deskilling, agrodiversity, and the seed trade: a view from contemporary British allotments

Over the last half-century, quality control standards have had the perverse effect of restricting the circulation of non-commercially bred vegetable cultivars in Britain. Recent European and British legislation attempts to compensate for this loss of agrodiversity by relaxing genetic purity standards and the cost of seed marketing for designated ‘‘Amateur’’ and ‘‘Conservation’’ varieties. Drawing on fieldwork conducted at a British allotment site, this article cautions against bringing genetically heterogeneous cultivars into the commercial sphere. Such a move may intensify the horticultural ‘‘deskilling’’ of British allotment gardeners, who have come to rely on commercial seed catalogs as sources of germplasm and knowledge. Horticultural deskilling also entails the delegation of seed selection activities to professional breeders and the potential loss of agrodiversity. The activities of dedicated seed savers who save and circulate the seed of genetically heterogeneous ‘‘heritage’’ varieties, in a manner similar to the management of landraces in the global South, may provide a better model for attempts to safeguard vegetable diversity in the global North