Evolution of digestive enzyme activities and structures in Alvinocarididae shrimps
Ravallec, R.; Van Wormhoudt, A. (1997). Evolution of digestive enzyme activities and structures in Alvinocarididae shrimps, in: Biologie des sources hydrothermales profondes = Biology of deep-sea hydrothermal vents: Journées d'échanges du Programme DORSALES = DORSALES Workshop Roscoff 6-8 octobre 1997. Cahiers de Biologie Marine, 38(2): pp. 136-137
In: (1997). Biologie des sources hydrothermales profondes = Biology of deep-sea hydrothermal vents: Journées d'échanges du Programme DORSALES = DORSALES Workshop Roscoff 6-8 octobre 1997. Cahiers de Biologie Marine, 38(2)[s.n.][s.l.]. 111-149 pp., meer
In: Cahiers de Biologie Marine. Station Biologique de Roscoff: Paris. ISSN 0007-9723; e-ISSN 2262-3094, meer
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| Auteurs | | Top |
- Ravallec, R.
- Van Wormhoudt, A.
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| Abstract |
Chorocaris chacei and Rimicaris exocula are two different Caridea from the family Alvinocarididae, living near deep-sea hydrothermal vent sites in mid-Atlantic ridge. They are characterized by an evolution of their digestive function toward the exclusive use of epibiotic bacteria in Rimicaris while Chorocaris is still necrophagous. The aim of our study was to characterize the properties of some digestive enzymes and to have some access to their structure using PCR. While their hepatopancreas seemed normal in cell structure, the level of digestive enzymes measured in these species was very low (at least 10 times lower than in other crustaceans for amylase). The highest activities were found for cathepsins and lysozymes while some amylase and chymotrypsin activities (only in Rimicaris) were measured. The activity measured on branchial extracts was not significantly different from that measured on hepatopancreas extracts but the origin of the enzymes was not determined. These activities confirm a necrophagous and a bacteriophagous alimentary comportment. pH and temperature effects did not present any particularity while the apparent Km measured for the enzymes were very low. The amount of extracted RNA or DNA was also very low compared to other shrimps. Trying different RT-PCR and PCR with different probes deduced from the structure of shrimp amylases or cathepsins, we were able to characterize only a short fragment of 160 bp for amylase in the two species. The same fragment was recovered in some Caridea and all were cloned and sequenced. One to 26 nucleotide changes were observed in the different species. However Penaeus vannamei cDNA corresponding fragments, used as an outgroup reference, presented the same level of variation inside the different isoforms, precluding the use of this fragment for phylogenetic studies. In future it should be interesting to work on fresh material in order to amplify larger PCR fragments suitable for molecular phylogeny. The construction of a cDNA library will also be very useful. |
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