Complete life cycle of Myxobolus rotundus (Myxosporea: Myxobolidae), a gill myxozoan of common bream Abramis brama

Abstract

The life cycle of Myxobolus rotundus Nemeczek, 1911, a myxosporean parasite of the gills of common bream Abramis brama L., was studied under laboratory conditions. Mature Myxobolus spp. spores from plasmodia in the gills of wild bream were used to infect naïve oligochaete worms in a flow-through system of aquaria. Triactinomyxon-type actinospores were released from the oligochaetes 1 yr later and allowed to continually flow into a tank containing uninfected bream fry. The gills of the fry were checked for development of plasmodia in squash preparations 3 d postexposure, and then at weekly intervals for 8 wk. Tissue samples were fixed at each time point. Developing plasmodia were first observed 17 d post-exposure (Day 17). Mature spores were collected from plasmodia on Day 56 and were added to plastic dishes containing parasite-free Tubifex tubifex oligochaetes. Second-generation actinospores were released from these worms 8 mo post-exposure, and were morphologically identical to first-generation spores. Myxospores obtained from the bream fry were morphologically identical to those identified in wild bream as M. rotundus. Small subunit ribosomal RNA gene sequences obtained from first-and second-generation actinospores and the bream fry myxospores were 100% similar to M. rotundus spores from the original wild fish.

Some additional data to the occurrence, morphology and validity of Myxobolus turpisrotundus Zhang, 2009 (Myxozoa: Myxosporea)

“…In addition, the plasmodium size of M. turpisrotundus is 600-6,200 μm in diameter and that of M. rotundus is 60-180 μm in diameter. Plasmodia of M. turpisrotundus were found in skin, jaws, gills, and fins of allogynogenetic gibel carp, while Molnár et al (2009) andSzékely et al (2009a) pointed out that M. rotundus was a specific gill parasite of the common bream. Moreover, M. turpisrotundus was previously described from allogynogenetic gibel carp, which is taxonomically distant from common bream.…”

Myxobolus supamattayai n. sp. (Myxosporea: Myxobolidae) from Thailand parasitizing the scale pellicle of wild mullet (Valamugil seheli)

“…Although host and tissue specificity are of great help in differentiating morphologically similar spores, there are some myxosporea, such as Myxobolus rotundus, that are classified from 27 cyprinid fish species and from different sites in the fish body (Eiras et al 2005;Molnár et al 2009;Zhang et al 2010). However, recent reports have described a specific parasite of common bream using molecular data and the actinosporean stage development in oligochaete, Tubifex tubifex Székely et al 2009). The wide host range and multiple infection sites are still yet to be explored.…”

Three actinosporean types (Myxozoa) from the oligochaete Branchiura sowerbyi in China

“…The revolutionary discovery by Wolf and Markiw (1984) that the life cycle of Myxobolus cerebralis (Höffer, 1903) involves an alternation between myxospore and actinospore stages in vertebrate and invertebrate hosts, respectively, greatly improved scientific research on actinosporeans and the understanding of myxozoan biology in the last two decades (Kent et al 2001;Yokoyama 2003;Székely et al 2009). Many studies have widely reported the actinospore fauna from fish farms and natural water, and the life cycle of many myxozoan species in Europe El-Mansy et al 1998a, b;Xiao and Desser 1998a, b, c;Hallett et al 1999Hallett et al , 2002Székely et al 2000Székely et al , 2002aSzékely et al , b, 2003Székely et al , 2004Székely et al , 2005Negredo and Mulcahy 2001;Özer et al 2002;Oumouna et al 2003;Marcucci et al 2009) and eastern Asia (Yokoyam et al 1993;1995).…”