Publications by authors named "H G de Couet"

41 Publications

The cephalopod arm crown: appendage formation and differentiation in the Hawaiian bobtail squid .

Front Zool 2016 29;13:44. Epub 2016 Sep 29.

Department of Biology, University of Hawaii at Manoa, 2538 McCarthy Mall, Edmondson Hall 413, Honolulu, HI 96822 USA.

Background: Cephalopods are a highly derived class of molluscs that adapted their body plan to a more active and predatory lifestyle. One intriguing adaptation is the modification of the ventral foot to form a bilaterally symmetric arm crown, which constitutes a true morphological novelty in evolution. In addition, this structure shows many diversifications within the class of cephalopods and therefore offers an interesting opportunity to study the molecular underpinnings of the emergence of phenotypic novelties and their diversification. Here we use the sepiolid as a model to study the formation and differentiation of the decabrachian arm crown, which consists of four pairs of sessile arms and one pair of retractile tentacles. We provide a detailed description of arm crown formation in order to understand the basic morphology and the developmental dynamics of this structure.

Results: We show that the morphological formation of the cephalopod appendages occurs during distinct phases, including outgrowth, elongation, and tissue differentiation. Early outgrowth is characterized by uniform cell proliferation, while the elongation of the appendages initiates tissue differentiation. The latter progresses in a gradient from proximal to distal, whereas cell proliferation becomes restricted to the distal-most end of the arm. Differences in the formation of arms and tentacles exist, with the tentacles showing an expedite growth rate and higher complexity at younger stages.

Conclusion: The early outgrowth and differentiation of the arm crown shows similarities to the related, yet derived cephalopod . Parallels in the growth and differentiation of appendages seem to exist throughout the animal kingdom, raising the question of whether these similarities reflect a recruitment of similar molecular patterning pathways.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1186/s12983-016-0175-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5041568PMC
September 2016

Culture of Hawaiian bobtail squid (Euprymna scolopes) embryos and observation of normal development.

Cold Spring Harb Protoc 2009 Nov;2009(11):pdb.prot5323

Department of Zoology, University of Hawaii at Manoa, Honolulu, HI 96822, USA.

The ability to rear Hawaiian bobtail squid (Euprymna scolopes) embryos under controlled environmental conditions is a basic and necessary tool for developmental studies. It negates the need to know when fertilization occurred, allows correlation of the phase of development with the time of development (thereby facilitating collection of embryos at specific stages), and allows comparisons between cephalopod species. Embryonic development in E. scolopes is robust over a range of temperatures, is relatively rapid (approximately 21 d), and proceeds normally under laboratory conditions at ambient temperature (27 degrees C-29 degrees C). Here we present methods for maintaining E. scolopes embryos in culture from cleavage through hatching, as well as observing and recording live or freshly fixed embryos under a dissecting microscope.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1101/pdb.prot5323DOI Listing
November 2009

Whole-mount in situ hybridization of Hawaiian bobtail squid (Euprymna scolopes) embryos with DIG-labeled riboprobes: II. Embryo preparation, hybridization, washes, and immunohistochemistry.

Cold Spring Harb Protoc 2009 Nov;2009(11):pdb.prot5322

Department of Zoology, University of Hawaii at Manoa, Honolulu, HI 96822, USA.

Whole-mount in situ hybridization is a technique used to localize and visualize specific gene transcripts in whole embryos by hybridizing labeled RNA probes complementary to the sequence of interest. A digoxigenin (DIG)-labeled riboprobe synthesized during in vitro transcription through the incorporation of DIG-labeled UTP is hybridized to the target sequence under stringent conditions, and excess unhybridized probe is removed during a series of washes. The location of the labeled riboprobe, and thus the mRNA sequence of interest, is then visualized by immunohistochemistry. This protocol outlines the steps involved in preparing Hawaiian bobtail squid (Euprymna scolopes) embryos, hybridizing a DIG-labeled riboprobe in whole-mount embryos, and visualizing the labeled RNA colorimetrically using an alkaline-phosphatase-conjugated anti-DIG antibody.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1101/pdb.prot5322DOI Listing
November 2009

Whole-mount in situ hybridization of Hawaiian bobtail squid (Euprymna scolopes) embryos with DIG-labeled riboprobes: I. DNA template preparation and in vitro transcription of riboprobes.

Cold Spring Harb Protoc 2009 Nov;2009(11):pdb.prot5321

Department of Zoology, University of Hawaii at Manoa, Honolulu, HI 96822, USA.

Whole-mount in situ hybridization is a technique used to localize and visualize specific gene transcripts in whole embryos by hybridizing labeled RNA probes complementary to the sequence of interest. A digoxigenin (DIG)-labeled riboprobe synthesized during in vitro transcription through the incorporation of a DIG-labeled UTP is hybridized to the target sequence under stringent conditions, and excess, unhybridized probe is removed during a series of washes. The location of the labeled riboprobe, and thus the mRNA sequence of interest, is then visualized by immunohistochemistry. This protocol outlines the techniques for preparing RNA probes for whole-mount in situ hybridization in Hawaiian bobtail squid (Euprymna scolopes) embryos from linearized plasmid DNA or polymerase chain reaction (PCR) products.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1101/pdb.prot5321DOI Listing
November 2009

Confocal immunocytochemistry of embryonic and juvenile Hawaiian bobtail squid (Euprymna scolopes) tissues.

Cold Spring Harb Protoc 2009 Nov;2009(11):pdb.prot5320

Department of Zoology, University of Hawaii at Manoa, Honolulu, HI 96822, USA.

The Hawaiian bobtail squid Euprymna scolopes is a cephalopod whose small size, short lifespan, rapid growth, and year-round availability make it suitable as a model organism. This protocol describes the preparation of whole juvenile squids by whole-mount immunocytochemistry for visualization by confocal microscopy.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1101/pdb.prot5320DOI Listing
November 2009
-->