Ultrastructure of developmental stages of Hemolivia stellata (Apicomplexa: Haemogregarinidae) in the cane toad Bufo marinus and in its vector tick Amblyomma rotondatum

Abstract

The fine structure of the hemogregarine Hemolivia stellata Petit, Landau, Baccam and Lainson, 1990 developmental stages in the cane toad Bufo marinus L. and the vector tick Amblyomma rotondatum Koch, 1844 are described. In the liver of the toad, merozoites bound by a pellicle were located free and in the cytoplasm, and young and encased mature polynucleated meronts were located in a parasitophorous vacuole (PV). Premature gametocytes in the erythrocytes were bound by a bilayered membranous wall and the mature gametocytes were encased in a bivalved capsule, suture sites occurring at both gametocyte extremities. In the tick gut cells, oocysts located within a PV formed oblong, pellicle-bound sporokinetes, with a small apical complex, a few short rhoptries, and a fragmented crystalloid body. Liberated sporokinetes re-entered gut cells to proceed with their differentiation into sporocysts within a PV with elaborate rims which suggested engagement in active metabolite cross-transport. With maturity, the sporocyst wall gradually transformed into a hard capsule. Differences in fine structural development between species of Hemolivia and the insect-transmitted Hepatozoon are conspicuous. The fine structure and course of development of H. stellata are very similar to those of the previously described Hemolivia mariae; their sporokinetes differ, however, in having conspicuous rhoptries rather than spherical-granular anlagen bodies, and fragmented rather than continuous crystalline bodies.

Hemolivia mauritanica(Haemogregarinidae: Apicomplexa) infection in the tortoiseTestudo graecain the Near East with data on sporogonous development in the tick vectorHyalomna aegyptium

“…Male ticks that remain attached to tortoises until the end of the summer are also heavy infected with sporocysts and are likely to be the vehicle for perpetuating infection into the next year. The sporogenesis process follows the pattern observed in the other two species of Hemolivia (Smallridge & Paperna, 2000b;Boulard et al, 2001), although there is some evident variation in fine-structural details: H. mauritanicum early sporocysts lack the crystalline bodies and the sphere-filled vacuoles prominent in H. stellata. The numerous micronemes and the apical projections seen in H. mauritanicum are absent in the latter two species.…”

“…The most conspicuous common characters were the oogonous-sporogonous development in the gut epithelium of ixodiid ticks, the stellate or triangular oocysts and a motile stage, progeny of oocysts -the sporokinete, which precedes differentiation of the encysted sporocyst. These features were confirmed by ultrastructural studies of H. mariae (Smallridge & Paperna, 2000a,b) and H. stellata (Boulard et al, 2001). Our study of apicomplexan parasites of reptiles in the Near East included terrapins (Paperna, 1989) and tortoises.…”

Ultrastructure of developmental stages of Hemolivia mariae (Apicomplexa: Haemogregarinidae), natural parasite of the Australian sleepy lizard, in experimentally infected deviant hosts

“…They are present in mature gametocytes of haemosporidians (Aikawa et al 1969, Paperna andBoulard 2000); in Hemolivia mariae gametocytes they disappear with the onset of maturity. Osmiophilic bodies were seen also in the recently studied Hemolivia stellata (Boulard et al 2001). Desser (1990, 1992) reported micronemes and dense organelles with peduncles extending to the plasmalemma in sporozoites of Haemogregarina balli and H. myxocephali.…”

“…The vesicles, which are apparently interconnected by ducts, are too vaguely outlined for any interpretation of their identity. Association between apparently forming amylopectin bodies and ER ducts has been observed also in tissue stages of H. stellata (Boulard et al 2001) Encasement in the gametocytes is associated with the long-lived nature of this stage in the circulatory blood, which increases the probability of successful vectormediated transmission. By the same strategy, meront encasement may also facilitate longer persistence as source for gametocyte relapses.…”

Ultrastructural Comparison of Hepatozoon ixoxo and Hepatozoon theileri (Adeleorina: Hepatozoidae), Parasitising South African Anurans

“…) and sutures (Boulard et al. ; Paperna and Smallridge ; Telford ) in H. ixoxo is alike to those seen characterising the gamonts of species of Hemolivia . However, in the case of Hemolivia this capsule wall appears impermeable to Giemsa stain and fixation (Boulard et al.…”