The slug-like larva of Phoronis ovalis swims for about 4 days, creeps on the sea-bed for 3 to 4 days, then bores into a carbonate floor.[27][28] Nothing is known about three species. The remaining species develop free-swimming actinotroch larvae, which feed on plankton. The actinotroch is an upright cylinder with the anus at the bottom and fringed with cilia. At the top is a lobe[1] or hood, under which are: a ganglion, connected to a patch of cilia outside the apex of the hood;[7] a pair of protonephridia(smaller and simpler than the metanephridia in the adult);[1] the mouth; and feeding tentacles that encircle the mouth.[7] After swimming for about 20 days, the actinotroch settles on the seabed and undergoes a catastrophic metamorphosis (radical change) in 30 minutes: the hood and larval tentacles are absorbed and the adult lophophore is created round the mouth, and both now points upward; the gut develops a U-bend so that the anus is just under and outside the lophophore.[1] Finally the adult phoronid builds a tube.[7]

Lophotrochozoa

Try saying that ten times fast.  

What I don’t get is that the internet says that Lophotrochozoa are protostomes, but the phylogeny my professor gave us has them including Ectoprocta and Brachiopoda, both of which are deuterostomes, so….?

New in Pubmed: Identification of Conserved and Novel MicroRNAs in the Pacific Oyster Crassostrea gigas by Deep Sequencing.

Identification of Conserved and Novel MicroRNAs in the Pacific Oyster Crassostrea gigas by Deep Sequencing.

PLoS One. 2014;9(8):e104371

Authors: Xu F, Wang X, Feng Y, Huang W, Wang W, Li L, Fang X, Que H, Zhang G

Abstract
MicroRNAs (miRNAs) play important roles in regulatory processes in various organisms. To date many studies have been performed in the investigation of miRNAs of numerous bilaterians, but limited numbers of miRNAs have been identified in the few species belonging to the clade Lophotrochozoa. In the current study, deep sequencing was conducted to identify the miRNAs of Crassostrea gigas (Lophotrochozoa) at a genomic scale, using 21 libraries that included different developmental stages and adult organs. A total of 100 hairpin precursor loci were predicted to encode miRNAs. Of these, 19 precursors (pre-miRNA) were novel in the oyster. As many as 53 (53%) miRNAs were distributed in clusters and 49 (49%) precursors were intragenic, which suggests two important biogenetic sources of miRNAs. Different developmental stages were characterized with specific miRNA expression patterns that highlighted regulatory variation along a temporal axis. Conserved miRNAs were expressed universally throughout different stages and organs, whereas novel miRNAs tended to be more specific and may be related to the determination of the novel body plan. Furthermore, we developed an index named the miRNA profile age index (miRPAI) to integrate the evolutionary age and expression levels of miRNAs during a particular developmental stage. We found that the swimming stages were characterized by the youngest miRPAIs. Indeed, the large-scale expression of novel miRNAs indicated the importance of these stages during development, particularly from organogenetic and evolutionary perspectives. Some potentially important miRNAs were identified for further study through significant changes between expression patterns in different developmental events, such as metamorphosis. This study broadened the knowledge of miRNAs in animals and indicated the presence of sophisticated miRNA regulatory networks related to the biological processes in lophotrochozoans.

PMID: 25137038 [PubMed - as supplied by publisher]



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