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Diseases of Aquatic Organisms

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DAO 116:213-225 (2015)  -  DOI:

Histophagous ciliate Pseudocollinia brintoni and bacterial assemblage interaction with krill Nyctiphanes simplex. I. Transmission process

Jaime Gómez-Gutiérrez1,*, Alejandro López-Cortés2, Mario J. Aguilar-Méndez2,4, Jorge A. Del Angel-Rodríguez2,5, Nelly Tremblay1,6, Tania Zenteno-Savín2, Carlos J. Robinson

1Instituto Politécnico Nacional, Centro Interdisciplinario de Ciencias Marinas, Departamento de Plancton y Ecología Marina, Av. Instituto Politécnico Nacional s/n, La Paz, BCS 23096, Mexico
2Centro de Investigaciones Biológicas del Noroeste (CIBNOR), La Paz, BCS 23096, Mexico
3Instituto de Ciencias del Mar y Limnología, Universidad Nacional Autónoma de México (UNAM), Mexico City, DF 04510, Mexico
4Present address: Instituto Politécnico Nacional, Unidad Profesional Interdisciplinaria de Ingeniería Campus Guanajuato, Silao de la Victoria, Guanajuato 36275, Mexico
5Present address: Departments of Biology and Ocean Sciences, Memorial University of Newfoundland, St. John’s, NL A1C 5S7, Canada
6Present address: Instituto Politécnico Nacional, Centro de Investigación y de Estudios Avanzados (CINVESTAV)— Unidad Mérida, Departamento de Recursos del Mar, Mérida, Yucatán 97310, Mexico
*Corresponding author:

ABSTRACT: Histophagous ciliates of the genus Pseudocollinia cause epizootic events that kill adult female krill (Euphausiacea), but their mode of transmission is unknown. We compared 16S rRNA sequences of bacterial strains isolated from stomachs of healthy krill Nyctiphanes simplex specimens with sequences of bacterial isolates and sequences of natural bacterial communities from the hemocoel of N. simplex specimens infected with P. brintoni to determine possible transmission pathways. All P. brintoni endoparasitic life stages and the transmission tomite stage (outside the host) were associated with bacterial assemblages. 16S rRNA sequences from isolated bacterial strains showed that Photobacterium spp. and Pseudoalteromonas spp. were dominant members of the bacterial assemblages during all life phases of P. brintoni and potential pathobionts. They were apparently unaffected by the krill’s immune system or the histophagous activity of P. brintoni. However, other bacterial strains were found only in certain P. brintoni life phases, indicating that as the infection progressed, microhabitat conditions and microbial interactions may have become unfavorable for some strains of bacteria. Trophic infection is the most parsimonious explanation for how P. brintoni infects krill. We estimated N. simplex vulnerability to P. brintoni infection during more than three-fourths of their life span, infecting mostly adult females. The ciliates have relatively high prevalence levels (albeit at <10% of sampled stations) and a short life cycle (estimated <7 d). Histophagous ciliate-krill interactions may occur in other krill species, particularly those that form dense swarms and attain high population densities that potentially enhance trophic transmission and allow completion of the Pseudocollinia spp. life cycle.

KEY WORDS: Collinia · Histophagous · Apostome ciliates · Euphausiacea · Parasite-host association · Gulf of California

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Cite this article as: Gómez-Gutiérrez J, López-Cortés A, Aguilar-Méndez MJ, Del Angel-Rodríguez JA, Tremblay N, Zenteno-Savín T, Robinson CJ (2015) Histophagous ciliate Pseudocollinia brintoni and bacterial assemblage interaction with krill Nyctiphanes simplex. I. Transmission process. Dis Aquat Org 116:213-225.

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