The 12^th East Coast Protozoology conference, hosted by Dr. Francine Marciano-Cabral and her lab, took place on June 3-5, 2005 at Virginia Commonwealth University School of Medicine in Richmond, Virginia. Thirty nine scientists participated in this year’s conference, sharing their latest research by means of a number of excellent oral and poster presentations.

Session moderators: Dr.’s Wade Bell and Francine Marciano-Cabral

The first talk of the conference was given by Dr. Ronald Fayer, who

Ronald Fayer

gave a great introductory talk about the parasitic protist Cryptosporidium. This genus consists of 15 species that infect the gastrointestinal tract of over 150 vertebrate host organisms. The predominant species of humans are C. hominis and C. parvum. The recent sequencing of both C. hominis and C. parvum genomes could provide information that leads to the development of pharmaceuticals and immunity-based prevention strategies to help combat this parasite.

Joao Alves

The second talk given by Dr. Joao Alves was devoted to dissecting the recently sequenced genome of C. hominis. The approximate 9.2 Mb genome consists of almost 4,000 protein-coding genes, 45 tRNAs and at least 4 rRNAs. C. hominis appears to be capable of both aerobic and anaerobic metabolism and relies heavily on the import of amino acids, nucleotides and other materials for biosynthesis. A series of hypothetical signal transduction systems have been identified.

Jan Keithly

Dr. Janet Keithly spoke about electron tomographic and ultrastructural analysis of the Cryptosporidium parvum relict mitochondrion. The relict mitochondrion in C. parvum is a small membranous organelle located between the nucleus and crystalloid body of the cell. Interestingly enough, these mitochondria apparently lack a mitochondrial genome and cristae junctions, which are essential in other protistan mitochondria. The proposed function of this unusual mitochondrial morphology is to protect the cytosolic compartment from toxic ferrous iron and sulfide, essential for iron-sulfur cluster (ISC) biosynthesis.

Jan Mead

Dr. Jan Mead gave an interesting talk concerning the susceptibility of humans to C. parvum infection. Immunocompetent humans usually develop an immune response that protect from symptomatic disease. In contrast, immunocompromised individuals typically develop chronic cryptosporidiosis and usually exhibit a decrease in CD4+ cells when infected with C. parvum. In addition, IFN-G and IL-12 have been implicated in susceptibility to C. Parvum infections. Interestingly enough, treatment of IL-12 knockout mice with recombinant IL-12 and IL-18 or irradiated parasites were protected from re-infection with C. parvum.

Richard Guerrant

Dr. Richard Guerrant gave an excellent talk regarding the impact of Cryptosporidium infections. Cryptosporidium infection is the leading cause of diarrheal death in children. Dr. Guerrant presented fascinating data that correlated the number of childhood diarrheal episodes with increased growth shortfalls, decreased stamina, decreased IQ and poor school performance. In addition, the APOE4 gene that codes for the lipoprotein cholesterol transporter implicated in Alzheimer’s disease appears to protect against these adverse diarrheal effects in regions with increased prevalence of Cryptosporidium infections. Much like the Sickle cell gene, this means good news for kids but bad news for adults. Dr. Guerrant also introduced us to the diarrheal euphemism "overt squirts".

The poster session was held following the first afternoon talks. Sixteen posters on a variety of topics were presented. The majority of the posters involved studies on a variety of parasitic protists, including Cryptosporidium, Entamoeba, Leishmania, Crepidoodinium, Amoebophyra, Naegleria and Quahog Parasite Unknown (QPX). The remaining posters included the ecology and morphology of several species of dinoflagellates, the loss of preservation in certain ciliate samples using a well known fixation method, exocytic processes in Tetrahymena, microbial succession and bathyal bifouling in Antarctic near shore waters and a memorial poster devoted to Dr. Hans Ris. The diversity of topics presented within a relatively small number of posters demonstrates the value of this conference in exposing researchers, particularly students, to a wide variety of topics in a benign and intimate setting.

Session moderators: Dr.’s Burt Goldberg, John Kloetzel and Glen McGugan

Chitchai Chantangsi

Chitchai Chantangsi proposed using the cytochrome c oxidase subunit 1 (CO1) from the mitochondrial genome to discriminate between the approximately 41 species of Tetrahymena. Mitochondrial genes are faster evolving and more variable than nuclear genes, making them better candidates for use in species discrimination studies. The CO1 nucleotide sequences of 9 Tetrahymena species were tested and found to have an average sequence similarity of 88.6%. Furthermore, phylogenetic tree analysis based on these results separated these 9 species into two groups, which was similar to nuclear based results.

Wade Bell

Dr. Wade Bell presented some interesting data on the ryanodine receptors in Paramecium. Ryanodine receptors are intracellular calcium-release channels that were found to localize to the mitochondria in Paramecium when the cells were labeled with fluorescent-tagged ryanodine. A probe to mitochondrial Ca²⁺ revealed that mitochondrial Ca²⁺ stores were reduced following a depolarization event in the cell. Dr. Bell’s group has identified at least three different ryanodine receptor sequences from the Paramecium genome project and has amplified one of them from genomic DNA.

Rebecca MacLean

Rebecca MacLean proposed using PCR methods to quickly discriminate between different species of amebae that are responsible for human disease. In a clinical situation, quick identification of the infectious protist is imperative because treatment is species dependent. Rebecca presented data that demonstrated the ability to discriminate between different species of free living amebae. In addition, PCR was used to identify Acanthamoeba spp in paraffin-embedded brain tissue, which was confirmed upon histological examination.

Charles Guerra

Charles Guerra presented work that demonstrated the existence of signaling pathways within the cilia of Tetrahymena thermophila. Considering the lack of overt sensory organelles in ciliates, the use of cilia as sensory organelles in these organisms should not come as a surprise. Previous work in the lab had demonstrated the presence of ciliary membrane protein with proposed receptor tyrosine kinase function. By mining the Tetrahymena genome database, Charles was able to identify other key proteins which could complete a ciliary signaling pathway in Tetrahymena. Further work in this rapidly developing area of ciliary biology should uncover signaling pathways critical for Tetrahymena cell survival.

Aaron Bell

Following the break, Aaron Bell presented his work on GEF1, a guanine nucleotide exchange factor found in Tetrahymena thermophila. Guanine nucleotide exchange factors are responsible for exchanging GDP for GTP on small G proteins, thereby activating the protein. GEF1 was subsequently cloned from T. thermophila cDNA and was found to encode a protein 2053 amino acids in length. The ciliary localization of this protein suggests that GEF1 could either function to regulate import/export of ciliary proteins or be involved in a ciliary signal transduction pathway.

John Kloetzel

A new species of testate ameba found in Crater Lake, Oregon was the topic of Dr. John Kloetzel’s talk. Crater Lake is the world’s largest caldera lake and was formed less than 7700 years ago, following the eruption of Mt. Mazama. Interestingly, this new species seems to prefer living at a depth of 160-200 meters where the water temperature remains a constant 4° C throughout the year. One of the more interesting evolutionary questions posed by Dr. Kloetzel was whether or not the biochemical adaptations required for living at this depth and temperature were acquired within the relatively short time period since the crater’s formation.

Carly Jordan

Carly Jordan presented her work on the small protist parasite Encephalitozoon cuniculi. This parasite is of particular importance in human health due to the impact it has on young and immunocompromised individuals, particularly AIDS patients. Carly’s research focuses on treatment of E. cuniculi infection with the recently approved drug Nitazoxanide (NTZ), which is being used to treat AIDS patients with C. parvum and Giardia lamblia infections. Preliminary results indicate that 5 ng/ml of NTZ inhibits the development of E. cuniculi and therefore could be used to treat AIDS patients infected with this parasite.

Sheila Mitchell

The topic of Sheila Mitchell’s talk was canine coccidiosis, which is caused by Cystoisospora canis and C. ohioensis infections. Sheila is interested in developing an experimental model of canine intestinal coccidiosis. Oocysts of C. canis obtained from pitbull puppies proved to be infectious for young beagles and inoculated beagles developed clinical coccidiosis. One of the aims of Sheila’s research is to develop a PCR test for early detection of Cystoisospora infections. More important to the audience of this talk was that no beagles were harmed during the course of these experiments.

Burt Goldberg

Dr. Goldberg’s talk highlighted the growing crisis of inadequate education in U.S. high schools. The crux of the problem appears to be that many high school science and math teachers have inadequate training. According to one study, 56% of high school students taking physical science courses are being taught by teachers that are teaching outside of their fields. In high poverty schools, the situation is even more serious. The only way to reverse the current trend is to focus on the education of the teachers that are teaching our children.

Eric Schott

The amazing ability of Perkinsus marinus to survive phagocytosis by its host, Crassostrea virginica (the eastern oyster), was the topic of Dr. Eric Schott’s talk. The parasite’s ability to remove reactive oxygen species appears to be the means by which they escape digestion by their host. This ability seems to stem from the presence of APX (ascorbate dependent peroxidase) genes in the genome of P. marinus that might contribute to hydrogen peroxide removal. Two putative APX genes (PmAPX1 and PmAPX2) were isolated from P. marinus cDNA and antibodies against these peptides localized these two gene products to different subcellular locations, as seen by immunofluorescence.

Marilee Ramesh

Dr. Marilee Ramesh is interested in the origin and evolution of meiosis and is looking for meiotic genes in protists. Dr. Ramesh presented her work on meiotic genes in Giardia. Giardia is a vertebrate parasite that is asexual, lack mitochondria and has a relatively small genome (12 mb). Interestingly enough, Dr. Ramesh’s research indicates that Giardia appears to have genes for meiosis. These findings raise several questions, such as: Does Giardia have meiosis after all? Did it lose meiosis? Do these meiotic genes serve non-meiotic functions?

Sam Bowser

Dr. Sam Bowser presented his work on determining an identifying characteristic for Gromia spp. Gromiids can be difficult to distinguish from other rhizarians, which can be a problem when conducting biodiversity studies. Both SEM and TEM studies have confirmed that this group of protists possesses iron containing scales, previously described as a "honeycomb membrane", within the test wall that can be used as an identifying characteristic. By using this identifying characteristic, Dr. Bowser has identified several giant (>1 mm) Antarctic species of gromiid.

Olga Tavares-Sanchez

Granulomatous Amebic Encephalitis and cutaneous acanthamoebiasis in immune compromised individuals are caused by Acanthamoeba spp. Olga Tavares-Sanchez presented her work on using a mouse model to study Acanthamoeba infections. Mice were first immune suppressed using THC, the psychoactive component of marijuana. The animals were then exposed to Acanthamoeba and sacrificed at various time points to determine what organs were infected using PCR methods. THC-treated mice had infected brain and liver tissues, demonstrating that immune suppression allows dissemination of the amoebae to other organs.

Bruno da Rocha Azevedo

Tritrichomonas foetus is a parasitic protist that infects the urogenital tracts of calves and bulls, which can result in a reduction in milk production, spontaneous abortions, low birth weight and delayed calving. Bruno found that five different subpopulations of T. foetus destroyed epithelial monolayers with varying efficiency, which was independent of the amount of cytoadhesion and whole-cell protease activity exhibited by the subpopulations. In addition, Bruno found a correlation between contact-independent cytotoxicity and extracellular protease activity, implicating this enzyme in T. foetus mediated cytotoxicity.

Andrea Habura

The classification of foraminiferan protists has traditionally been by composition and shape of their elaborate tests. Foraminiferans like the allogromiids, however, are more difficult to identify because their tests are generally single-chambered and soft walled. Dr. Andrea Habura had previously used environmental DNA techniques to determine that 75% of the foraminiferans had escaped detection by traditional techniques and that most of those were allogromiids. In this talk, Dr. Habura used this same technique to sample 3 different sites along the eastern seaboard and found that allogromiids were prevalent at each site. These results could indicate a previously underappreciated role of these foraminiferans in nutrient cycling in benthic environments.

Jeff Cole

Heliochonid ciliates are highly specialized ectosymbionts on the gills of their crustacean hosts. The taxonomic data for identification of this group of ciliates, primarily kinetome mapping, is sparse or non-existent. In order to try and clarify the ambiguity in the taxonomic record, Jeffrey Cole examined live and Protargol stained specimens of a Heliochona spp removed from Gammarus amphipods. Jeff found that the kinetome of the tomite (migratory daughter cell) is derived directly from the parent cell and the trophont (sessile form) kinetome is produced directly from the kinetome of the tomite during metamorphosis. Jeff also discovered that this species preferentially colonizes the anterior most gill pairs of the host.

Wolfgang Petz

Dr. Wolfgang Petz delivered an excellent talk on the biodiversity of ciliates and testate amebae in the benthos of high Arctic freshwater lakes. Dr. Petz found over 220 ciliate species and 50 testate amoebae taxa present in the benthos of 24 lakes and streams as well as two wet terrestrial moss sites. The diversity and species composition of ciliates and testate amebae in the Arctic freshwater communities was found to be significantly richer than that of Antarctic regions of similar latitudes. In addition, approximately 80% of the biomass was dominated by flagellates. Dr. Petz concluded that the relatively large biomass of the ciliates and testate amebae in this environment indicates that they play a crucial ecologic role in high Arctic limnobenthos.

 Part Two of this report