Eugregarines reduce susceptibility of the hide beetle, Dermestes maculatus, to apicomplexan pathogens and retard larval development.

Eugregarines are abundant in a great diversity of invertebrates, and yet their relationships with their hosts are subject to controversy and confusion. We tested the effect of the eugregarine, Pyxinia crystalligera, on growth, development, and susceptibility to two Apicomplexa pathogens of the hide beetle, D. maculatus.

Individual and population effects of eugregarine, Gregarina niphandrodes (Eugregarinida: Gregarinidae), on Tenebrio molitor (Coleoptera: Tenebrionidae).

Gregarines are single-celled parasites in the phylum Apicomplexa that infect invertebrates. They are highly abundant on three levels: among a large diversity of invertebrates, in the proportion of population of organisms they infect, and within individually infected organisms. Because of their remarkable prevalence, we hypothesize that they play an important role in support of their hosts.

Ultrastructure of the Gregarina niphandrodes nucleus through stages from unassociated trophozoites to gamonts in syzygy and the syzygy junction.

In Gregarina niphandrodes, an apicomplexan parasite, the sexual stage of its life cycle begins with the association of 2 gamonts. Here, we describe the ultrastructure of the syzygy junction and the nucleus during the transition from unassociated trophozoites to paired gamonts to gamonts in syzygy. Throughout this process, the folds within the syzygy junction undergo changes that correspond to changes of the epicytic folds.

Fluid dynamic models of flagellar and ciliary beating.

We have developed a fluid-mechanical model of a eucaryotic axoneme that couples the internal force generation of dynein molecular motors, the passive elastic mechanics of microtubules, and forces due to nexin links with a surrounding incompressible fluid. This model has been used to examine both ciliary beating and flagellar motility. In this article, we show preliminary simulation results for sperm motility in both viscous and viscoelastic fluids, as well as multiciliary interaction with a mucus layer.

Gregarina niphandrodes may lack both a plastid genome and organelle.

Gregarines are early diverging apicomplexans that appear to be closely related to Cryptosporidium. Most apicomplexans, including Plasmodium, Toxoplasma, and Eimeria, possess both plastids and corresponding plastid genomes. Cryptosporidium lacks both the organelle and the genome.

Dynamic organization of microtubules and microtubule-organizing centers during the sexual phase of a parasitic protozoan, Lecudina tuzetae (Gregarine, Apicomplexa).

Lecudina tuzetae is a parasitic protozoan (Gregarine, Apicomplexa) living in the intestine of a marine polychaete annelid, Nereis diversicolor. Using electron and fluorescence microscopy, we have characterized the dynamic changes in microtubule organization during the sexual phase of the life cycle. The gametocyst excreted from the host worm into seawater consists of two (one male and one female) gamonts in which cortical microtubule arrays are discernible.

Expressed sequence tag (EST) analysis of Gregarine gametocyst development.

Gregarines are protozoan parasites of invertebrates in the phylum Apicomplexa. We employed an expressed sequence tag strategy in order to dissect the molecular processes of sexual or gametocyst development of gregarines. Expressed sequence tags provide a rapid way to identify genes, particularly in organisms for which we have very little molecular information.