Saturday, July 03, 2021

Dinoflagellate Genome Structure Unlike Any Other Known

Amazing stuff! Wonders of life!

"... Rather than the flexible, X-shaped chromosomes familiar to humans, dinoflagellates organize their genetic material in orderly blocks along rigid, rod-shaped chromosomes. Genes within blocks are consistently transcribed in one direction and rarely interact with others outside their immediate vicinity. This odd arrangement, the authors found, influences the three-dimensional structure of the entire chromosome. ...
Dinoflagellates are best known for their relationship to corals. In exchange for a safe home, the single-cell microalgae provide the coral with photosynthetic nutrients. When corals bleach, it’s because they’re expelling their symbionts in response to stress. ...
Their genomes, for one, are massive. S. microadriaticum’s genome is relatively small among dinoflaggelates, but it’s still one-third the size of the human genome. And rather than regulate gene expression only through transcription, dinoflagellates also engage in rampant gene and chromosome duplication, making genome assembly a nightmarish effort for geneticists—putting the puzzle together is more difficult when many of the pieces look identical. 

Until very recently, it was also thought that dinoflagellates lacked the histones that condense and package DNA and are present in all other eukaryotes. While recent studies have found that they do in fact have histones, they likely don’t serve the same purpose. Ordinarily, histones work like spools, allowing DNA to wind and unwind to become more or less accessible to transcriptional machinery as needed. In contrast, dinoflagellate chromosomes seem to be perpetually condensed into a crystalline structure, leaving unanswered questions about how their DNA is organized and how it can be accessed for transcription. ..."

Dinoflagellate Genome Structure Unlike Any Other Known | The Scientist Magazine® The transcription of DNA drives the remarkably tidy organization of chromosomes in the dinoflagellate Symbiodinium microadriaticum, a species involved in a life-supporting symbiosis with corals.

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