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Blackburn DG, Barnes MS, Reimers CD, Appiah FA, Lestz LL, Bonneau LJ, Hanson M, Smith-Paredes D, Bhullar BA. How do Crocodylian embryos process yolk? Morphological evidence from the American alligator, Alligator mississippiensis. J Morphol 2020; 282:953-958. [PMID: 32840899 DOI: 10.1002/jmor.21252] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2020] [Revised: 07/17/2020] [Accepted: 07/26/2020] [Indexed: 12/17/2022]
Abstract
Recent studies have demonstrated a mechanism of embryonic yolk processing in lizards, snakes and turtles that differs markedly from that of birds. In the avian pattern, cells that line the inside of the yolk sac take up products of yolk digestion and deliver nutrients into the vitelline circulation. In contrast, in squamates and turtles, proliferating endodermal cells invade and fill the yolk sac cavity, forming elongated strands of yolk-filled cells that surround small blood vessels. This arrangement provides a means by which yolk material becomes cellularized, digested, and transported for embryonic use. Ultrastructural observations on late-stage Alligator mississippiensis eggs reveal elongated, vascular strands of endodermal cells within the yolk sac cavity. The strands of cells are intermixed with free yolk spheres and clumps of yolk-filled endodermal cells, features that reflect early phases in the yolk-processing pattern. These observations indicate that yolk processing in Alligator is more like the pattern of other reptiles than that of birds.
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Affiliation(s)
- Daniel G Blackburn
- Department of Biology, and Electron Microscopy Center, Trinity College, Hartford, Connecticut, USA
| | - Madeline S Barnes
- Department of Biology, and Electron Microscopy Center, Trinity College, Hartford, Connecticut, USA
| | - Charles D Reimers
- Department of Biology, and Electron Microscopy Center, Trinity College, Hartford, Connecticut, USA
| | - Farahana A Appiah
- Department of Biology, and Electron Microscopy Center, Trinity College, Hartford, Connecticut, USA
| | - Luisa L Lestz
- Department of Biology, and Electron Microscopy Center, Trinity College, Hartford, Connecticut, USA
| | - Laurie J Bonneau
- Department of Biology, and Electron Microscopy Center, Trinity College, Hartford, Connecticut, USA
| | - Michael Hanson
- Department of Geology and Geophysics, Yale University, New Haven, Connecticut, USA
| | - Daniel Smith-Paredes
- Department of Geology and Geophysics, Yale University, New Haven, Connecticut, USA
| | - Bhart-Anjan Bhullar
- Department of Geology and Geophysics, Yale University, New Haven, Connecticut, USA
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Elinson RP, Stewart JR, Bonneau LJ, Blackburn DG. Amniote yolk sacs: diversity in reptiles and a hypothesis on their origin. Int J Dev Biol 2014; 58:889-94. [DOI: 10.1387/ijdb.140239db] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Abstract
Although medical advances occur daily, ophthalmic nurses face vision decrease or loss in their patients. Orientation and mobility training are offered by state agencies, helping the person find ways to adjust to living with sight loss. Whereas a white cane is the preferred mobility method of choice for some persons, more persons are discovering the advantages of a guide dog. This article will help ophthalmic nurses understand how a guide dog is produced and the uses of a guide dog. This knowledge is an option to increase mobility in newly blind patients.
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Affiliation(s)
- L J Bonneau
- Fidelco Guide Dog Foundation, Inc, PO Box 142, Bloomfield, CT 06002, USA
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Abstract
Extensive analysis of cDNAs from the para locus in D. melanogaster reveals posttranscriptional modifications indicative of adenosine-to-inosine RNA editing. Most of these edits occur in highly conserved regions of the Na+ channel, and they occur in distant relatives of D. melanogaster as well. Sequence comparison between species has identified putative cis-acting elements important for each RNA editing site. Double-stranded RNA secondary structures with striking similarity to known RNA editing sites were generated based on these data. In addition, the RNA editing sites appear to be developmentally regulated. We have cloned a potential RNA editase, DRED, with a high degree of homology to the mammalian RED1,2 genes. The DRED locus itself is highly regulated by transcription from alternative promoters and alternative splicings.
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Affiliation(s)
- C J Hanrahan
- Department of Pharmacology, University of Connecticut Health Center, Farmington 06030-6125, USA
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