The intraflagellar transport protein, IFT88, is essential for vertebrate photoreceptor assembly and maintenance

Approximately 10% of the photoreceptor outer segment (OS) is turned over each day, requiring large amounts of lipid and protein to be moved from the inner segment to the OS. Defects in intraphotoreceptor transport can lead to retinal degeneration and blindness. The transport mechanisms are unknown, but because the OS is a modified cilium, intraflagellar transport (IFT) is a candidate mechanism. IFT involves movement of large protein complexes along ciliary microtubules and is required for assembly and maintenance of cilia. We show that IFT particle proteins are localized to photoreceptor connecting cilia. We further find that mice with a mutation in the IFT particle protein gene, Tg737/IFT88, have abnormal OS development and retinal degeneration. Thus, IFT is important for assembly and maintenance of the vertebrate OS.

Analysis ofChlamydomonasSF-assemblin by GFP tagging and expression of antisense constructs

Striated fiber assemblin (SF-assemblin or SFA) is the major component of the striated microtubule-associated fibers (SMAFs) in the flagellar basal apparatus of green flagellates. We generated nuclear transformants of Chlamydomonas expressing green fluorescent protein (GFP) fused to the C-terminus of SFA. SFA-GFP assembled into striated fibers that exceeded those of wild-type cells in size by several fold. At elevated temperatures(≥32°C) SFA-GFP was mostly soluble and heat shock depolymerized the SMAFs. C-terminal deletions of 18 or only six residues disturbed the ability of SFA-GFP to polymerize, indicating an important role of the C-terminal domain for fiber formation. The exchange of the penultimate Ser275 with alanine made SFA-GFP highly insoluble, causing aberrant fiber formation and conferring heat stability to the fibers. By contrast, a replacement with glutamic acid increased the solubilty of the molecule, indicating that phosphorylation on Ser275 might control solubility of SFA. In vivo observation of GFP fluorescence showed that SFA-GFP fibers were disassembled during mitosis. In cells overexpressing full-length or truncated SFA-GFP, the amount of wild-type protein was reduced. Elevated temperatures dissolved SFA-GFP fibers and induced the synthesis of SFA, suggesting that cells control both the amount of soluble and polymeric SFA. By expressing constructs consisting of cDNA and genomic DNA for parts of SFA in antiparallel configuration, the amount of SFA was severely reduced. In these strains we observed defects in flagellar assembly, indicating an important role for noncontractile striated roots in the flagella apparatus.

Relation between hepatitis B carrier status and antibody against synthetic Plasmodium falciparum erythrocyte surface (pf155 - RESA) antigen

A survey on Plasmodium infection was carried out in gold mine camps located in the Brazilian Amazon. Antibody against P. falciparum ring-infected erythrocyte surface antigen (RESA) was quantified by an enzyme-immunoassay in order to assess P. falciparum exposure. Hepatitis B, a common infection in this area, was also investigated by serologic markers. Among 520 sampled subjects, 517 (99.4%) admitted previous symptomatic malaria, 106 (20.4%) had positive thick smears for malaria, 82.9% had HBV markers, and 7.1% were HBsAg positive. Anti-RESA titers was significantly lower in HBV carriers than in people with resolved HBV infection suggesting that the anti-RESA immune response could be supressed by HBV carrier status. Moreover, immunedeficient responses to both infections may take place in some subjects causing concomitant lower anti-RESA response and incapacity to clear HBV.

High malaria transmission intensity in a village close to Yaounde, the capital city of Cameroon

A 2-yr longitudinal malaria study was undertaken in a suburb of Yaounde, the capital city of Cameroon, in the village of Simbock, approximately 2 km from the city limits. This study allowed assessment of malaria transmission intensity and dynamics in this region before implementation of pyrethroid impregnated bed nets through the national vector control program. Anophelines were captured on human volunteers by pyrethrum spray collections and in resting sites outdoors. Malaria vectors were Anopheles funestus Giles, Anopheles gambiae s.s. Giles (M and S forms), Anopheles moucheti Evans, and Anopheles nili Theobald. An. moucheti was the most abundant mosquito captured during the study, accounting for >54% of total anophelines caught. The annual Plasmodium falciparum Welch entomological inoculation rates measured by enzyme-linked immunosorbent assay were 277 infected bites per human for the first year and 368 for the second year. An. gambiae s.s., An. funestus, An. moucheti, and An. nili were responsible for 23.8%, 26.8%, 39.2%, and 10.2% of malaria transmission, respectively. Malaria transmission is perennial throughout the year. All these vectors were highly anthropophagous because only two out of 566 mosquitoes blood-meal tested were not taken on humans.

Evaluation of a dipstick malaria sporozoite panel assay for detection of naturally infected mosquitoes

The determination of the presence or absence of malaria sporozoites in wild-caught Anopheles mosquitoes remains an integral component to the understanding of the transmission dynamics in endemic areas. To improve that capability, there has been on-going development of a new device using dipstick immunochromatographic technology for simplifying the testing procedure and reducing the time required to obtain results. As part of a larger multi-center effort, we evaluated the sensitivity and specificity of a prototype malaria sporozoite antigen panel assay (Medical Analysis Systems, Camarillo, CA) against three human Plasmodium species/polymorphs. The wicking (dipstick) assay was compared against a standard parasite antigen capture enzyme-linked immunosorbent assay (ELISA) for the detection of human circumsporozoite protein (CSP) in wild-caught mosquitoes. Over 6,800 Anopheles mosquitoes, representing 20 species collected from malaria endemic areas of Indonesia were tested either individually or in pools of up to 10 mosquitoes each. From 1,442 pooled test strip assays and ELISA formats, nine mosquito pools were found reactive for P.falciparum, P. vivax 210, or P. vivax 247 CSP. There was complete concordance between test strip results and ELISA results. Sensitivity was 100% and given some minor problems with false positives or negatives, specificity (n = 488) was 97%. Most strips judged as false positive produced very weak signals compared with negative control blank strips and paired ELISA-negative samples. The dipstick test proved technically simpler to perform and interpret than the ELISA and results were obtained within 15 min of exposure to mosquito suspension. This qualitative assay appears an attractive alternative to the CSP ELISA for detection of sporozoites in fresh or dried mosquitoes.

An outbreak of cutaneous leishmaniasis among soldiers in Belém, Pará State, Brazil, caused by Leishmania (Viannia) lindenbergi n. sp. A new leishmanial parasite of man in the Amazon region

Eight cases of cutaneous leishmaniasis are recorded among soldiers of the Brazilian Forest Infantry stationed in Belém, State of Pará, north of Brazil. The infections, all acquired during manoeuvres in nearby degraded primary forest, are attributed to a new member of the subgenus Viannia, Leishmania (V.) lindenbergi n. sp. A further infection by this parasite was encountered in a woman, who lived very close to the same piece of forest. The new parasite has been characterised and differentiated from other known species of the subgenus Viannia following the combined use of enzyme electrophoresis and monoclonal antibodies techniques. The eco-epidemiology of L. (V.) lindenbergi is discussed: by far the most abundant anthropophilic sandfly in the type locality was identified as Lutzomyia (Nyssomyia) antunesi (Coutinho), and this remains high on the list of possible vectors.

Evaluation of anopheline mosquitoes (Diptera: Culicidae) from the republic of Korea for Plasmodium vivax circumsporozoite protein

As part of an on-going malaria surveillance effort conducted by the U.S. Forces Korea, Republic of Korea (ROK), a total of 28,286 anopheline mosquitoes was tested for the presence of Plasmodium vivax circumsporozoite (CS) protein. Mosquitoes were collected (using a variety of light and baited traps) from 29 locations throughout the ROK (the majority were collected near the de-militarized zone), identified to species, and tested by enzyme-linked immunosorbent assay for the presence of P. vivax 210 and P. vivax 247 CS protein. Recent evidence suggests that characters used to separate Anopheles sinensis Wiedemann from An. lesteri Baisas & Hu are unreliable; therefore, the data have been analyzed by grouping these two species. A total of 25,365 Anopheles sinensis/lesteri, 2,890 An. yatsushiroensis Miyazaki, and 31 An. sineroides Yamada was tested. Of these, one pool of 10 An. sinensis/lesteri collected on 9 September 1999 at Camp Howze and one pool of nine An. sinensis/ lesteri collected on 13 September 1999 at Camp Bonifas were positive for P. vivax 247.

Characterization of TgROP9 (p36), a novel rhoptry protein of Toxoplasma gondii tachyzoites identified by T cell clone

T cell clone 3Tx19 detects a Toxoplasma gondii tachyzoite protein which, in high resolution 2D gel electrophoresis, runs at 36 kDa apparent MW with two spots of pI 5.9 and 6.5, thus exhibiting a migration pattern distinct from those of other known Toxoplasma antigens. The sequences of peptide fragments from tryptic digestion of the more prominent protein spot allowed the design of oligonucleotide primers to obtain the coding cDNA sequence. Sequence analysis of cDNA from strain BK revealed a 363 amino acid open reading frame, defined by all nine peptide sequences determined. The deduced protein sequence contains two hydrophobic segments, one near the N-terminus including a predicted signal peptide and a shorter second at the carboxy terminus, but homology to any other known protein is lacking. With synthetic peptides covering the complete primary structure, the epitope for clone 3Tx19 was mapped within the deduced partial sequence, which had remained unconfirmed by tryptic peptides. Antibodies raised against another, putative B cell epitope peptide detected the same two protein spots in 2D gel, indicating that they are antigenically related isoforms. The protein p36 is expressed by T. gondii isolates of all three intraspecies subgroups, but not in the bradyzoite stage. In intracellular tachyzoites, p36 colocalizes with rhoptry proteins and has a distribution pattern disparate from that of dense granule and microneme proteins. Subcellular fractionation indicated that p36 is a soluble constituent of tachyzoites. We suggest that this T cell-stimulatory novel rhoptry protein of T. gondii be named ROP9. It represents a marker of the tachyzoite stage.

Evidence for a compartmentalized B cell response as characterized by IgG epitope specificity in human ocular toxoplasmosis

Infectious agents in the eye induce both a local and a systemic humoral immune response. Previously, differences in Ag recognition were observed between systemic and ocular derived IgG of patients with ocular toxoplasmosis. This finding implied a nonrandom distribution of IgG-producing B cells in the inflamed eye. In the present study, we compared the intraocular and systemic B cell responses of patients with ocular toxoplasmosis to a single Toxoplasma gondii Ag. Two series of C-terminally deleted recombinant T. gondii GRA-2 proteins were constructed to delineate IgG B cell epitopes of paired ocular and serum samples. Differences in epitope region recognition between the ocular and systemic compartment were detected in 9 of 13 patients. The difference in distribution of GRA-2 epitopes between paired samples is indicative of a local GRA-2 specific B cell population functionally different from the systemic GRA-2-specific B cell population. Our results suggest a selective activation of a subset of B cells locally in nonlymphoid tissue.

Plasmodium vivax malaria vaccine development

Plasmodium vivax represents the most widespread malaria parasite worldwide. Although it does not result in as high a mortality rate as P. falciparum, it inflicts debilitating morbidity and consequent economic impact in endemic communities. In addition, the relapsing behavior of this malaria parasite and the recent resistance to anti-malarials contribute to making its control more difficult. Although the biology of P. vivax is different from that of P. falciparum and the human immune response to this parasite species has been rather poorly studied, significant progress is being made to develop a P. vivax-specific vaccine based on the information and experience gained in the search for a P. falciparum vaccine. We have devoted great effort to antigenically characterize the P. vivax CS protein and to test its immunogenicity using the Aotus monkey model. Together with other groups we are also assessing the immunogenicity and protective efficacy of the asexual blood stage vaccine candidates MSP-1 and DBP in the monkey model, as well as the immunogenicity of Pvs25 and Pvs28 ookinete surface proteins. The transmission-blocking efficacy of the responses induced by these latter antigens is being assessed using Anopheles albimanus mosquitoes. The current status of these vaccine candidates and other antigens currently being studied is described.

Comparative proteome analysis of Leishmania donovani at different stages of transformation from promastigotes to amastigotes

To pass through its life cycle, protozoan parasites of the genus Leishmania have to differentiate from promastigotes to amastigotes. The molecular basis underiving this major transformation is poorly understood. One way to study this phenomenon is to isolate and characterize proteins that are specifically expressed in one of the two stages of the life cycle or during the stage differentiation. Using two-dimensional gel electrophoresis, we mapped the Leishmania donovani proteome during stage differentiation to identify stage-specific proteins and regulons. A protocol for extracting proteins of both promastigote and amastigote L. donovani cells was developed, which is compatible with isoelectric focusing. Up to 400 L. donovani protein spots were visualized on a silver-stained gel. Metabolic labeling of the cells was used to compare directly the protein synthesis pattern with the protein level pattern. The silver-stained images of L. donovani cells harvested on different days of stage differentiation were compared to the corresponding autoradiographs. A marked decrease in protein synthesis during stage differentiation from promastigotes to amastigotes was observed. The stained protein pattern as well as the protein pattern on the autoradiograph changed dramatically, especially after day 3 (about 24 h after pH shift) of transformation.

Biochemical and biological characterization of the protective Leishmania pifanoi amastigote antigen P-8

The Leishmania pifanoi amastigote antigen P-8 has been previously shown to induce protective immunity in a murine model of cutaneous leishmaniasis (L. Soong, S. M. Duboise, P. Kima, and D. McMahon-Pratt, Infect. Immun. 63:3559-3566, 1995). As this antigen is of interest for further vaccine studies, the biochemical characterization of P-8 was undertaken. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis, Western-blot analysis, and gel filtration chromatography revealed that P-8 antigen consisted of two proteoglycolipid complexes. The P-8 epitope is associated with the L. pifanoi amastigote-specific glycolipid components found in the two complexes. The P-8 complex 1 (P-8c1) consists of a 56-kDa serine metalloproteinase, apolipoprotein E (derived from fetal bovine serum), and amastigote-specific glycolipids. The P-8 complex 2 (P-8c2) consists of a 31-kDa cysteine proteinase associated with amastigote glycolipids. Biochemical analyses suggest that the P-8 antigenic glycolipids may be distinct from previously described Leishmania glycolipids (glycosylinositol-phospholipids and sphingoglycolipids). Protective immunity studies revealed that P-8c1 (serine metalloproteinase-glycolipid complex) confers comparable protection against infection as immunopurified P-8. The isolated P-8c2 (cysteine proteinase-glycolipid complex) does not provide significant protection, nor does stimulation with P-8c2 result in significant T-cell activation in P-8- or P-8c2-vaccinated mice. Consequently, the P-8c1 complex appears to be the immunodominant component of P-8.

Entamoeba histolytica: transferrin binding proteins

Entamoeba histolytica trophozoites depend on iron for their growth; thus, they must use some host iron-containing molecules to fulfill this requirement. In this work we report that amoebas are able to utilize human holo-Tf as iron source and to recognize it through transferrin binding proteins. By use of an anti-human transferrin antiserum in an immunoblotting assay, two main polypeptides with apparent molecular masses of 70 and 140 kDa were found in total extract of trophozoites cultured in vitro. However, when a monoclonal anti-human transferrin receptor antibody was used, only one band with molecular mass of 140 kDa was observed. Both the human transferrin and the monoclonal antibody recognized a protein on the amoebic surface, demonstrated by confocal microscopy. Furthermore, the complex transferrin-transferrin binding protein was internalized by an endocytic process and probably dissociated inside the cell. This mechanism could be one manner in which E. histolytica acquires iron from the human host transferrin.

Identification and characterization of an excretory-secretory product from Giardia lamblia

A 58 kDa excretory-secretory product (ESP) of Giardia lamblia has been characterized. The ESP was purified over 508-fold by a combination of ammonium sulphate precipitation and sequential chromatography on affinity matrix and a gel filtration column. The homogeneity of the purified protein was established by sodium dodecyl sulphate polyacrylamide gel electrophoresis (Mr, 58 kDa) and analytical isoelectrophoresis (pI 4.75). The purified protein was recognized by the pooled sera of G. lamblia-positive patients as well as an antiserum raised against crude Giardia extract, thus indicating it to be an immunodominant parasite product. The ESP was found to agglutinate rabbit erythrocytes. The haemagglutinating activity of this protein was inhibited strongly by thyroglobulin, fetuin, asialofetuin and monosialoganglioside but not by simple sugars. The purified protein was characterized immunochemically and was found to be heat stable as well as protease sensitive. Lectin-binding studies of the purified ESP and its sensitivity to periodic-acid silver staining as well as to metaperiodate treatment clearly indicated its glycoprotein nature. The major localization site of the ESP was found to be on the surface of the parasite as revealed by flow cytometric analysis. Further, this glycoprotein induced fluid accumulation in ligated rabbit ileal loops and revealed a positive skin permeability reaction in the rabbit.

Vesicle-mediated trafficking of parasite proteins to the host cell cytosol and erythrocyte surface membrane in Plasmodium falciparum infected erythrocytes

During the development of the asexual stage of the malaria parasite, Plasmodium falciparum, the composition, structure and function of the host cell membrane is dramatically altered, including the ability to adhere to vascular endothelium. Crucial to these changes is the transport of parasite proteins, which become associated with or inserted into the erythrocyte membrane. Protein and membrane targeting beyond the parasite plasma membrane must require unique pathways, given the parasites intracellular location within a parasitophorous vacuolar membrane and the lack of organelles and biosynthetic machinery in the host cell necessary to support a secretory system. It is not clear how these proteins cross the parasitophorous vacuolar membrane or how they traverse the erythrocyte cytosol to reach their final destinations. The identification of: (1) a P. falciparum homologue of the protein Sar1p, which is an essential component of the COPII-based secretory system in mammalian cells and yeast and (2) electron-dense, possibly coated, secretory vesicles bearing P. falciparum erythrocyte membrane protein 1 and P. falciparum erythrocyte membrane protein 3 in the host cell cytosol of P. falciparum infected erythrocytes recently provided the first direct evidence of a vesicle-mediated pathway for the trafficking of some parasite proteins to the erythrocyte membrane. The major advance in uncovering the parasite-induced secretory pathway was made by incubating infected erythrocytes with aluminium tetrafluoride, an activator of guanidine triphosphate-binding proteins, which resulted in the accumulation of the vesicles into multiple vesicle strings. These vesicle complexes were often associated with and closely abutted the erythrocyte membrane, but were apparently prevented from fusing by the aluminium fluoride treatment, making their capture by electron microscopy possible. It appears that malaria parasites export proteins into the host cell cytosol to support a vesicle-mediated protein trafficking pathway.

[Relevance of Entamoeba dispar in amebiasis]

Entamoeba histolytica was redefined to recognize the existence of two morphologically indistinguishable species but genetically distinct: E. histolytica and E. dispar. The former is a pathogen responsible for amebiasis while the latter is a commensal. This redefinition has dramatically changed the understanding of amebiasis and its clinical management.

Quantitative analysis of two-dimensional gel electrophoresis protein patterns: a method for studying genetic relationships among Globodera pallida populations

A method based in two-dimensional protein gel electrophoresis has been developed in order to improve the analysis of genetic relationships among populations of Globodera. It has been used to estimate genetic divergence among nine Globodera pallida nematode populations. Sixty-one anonymous polypeptide spots were resolved using silver-stained high-resolution 2D gels and they were quantified in each population to establish genetic variation among G. pallida populations. The results of this analysis were compared with those obtained after a study of allelic frequency variation, which was carried out using seven previously described loci. Genetic distances among populations were calculated by means of both studies, the quantitative analysis and the allelic frequency variation, and phylogenetic trees were constructed for each type of analysis. A correlation analysis between the two distance matrices was carried out and a bootstrap analysis was performed to determine the strength of the clusters obtained with each method. The results obtained support the idea that quantitative protein analysis can be successfully applied to phylogenetic analysis of G. pallida populations.

Determination of antigenic domain in GST fused major surface protein (Nc-p43) of Neospora caninum

The antigenic domain of the major surface protein (Nc-p43) of Neospora caninum was examined by polymerase chain reaction of its gene fragments and recombinant expression as GST fusion proteins. The fragments of Nc-p43 were as follow: a total open reading frame (OFR), T; OFR without signal sequence and C-terminal hydrophobic sequence, S; N-terminal 2/3 parts of S, A; C-terminal 2/3 parts, P; N-terminal 1/3 part, X; middle 1/3 part, Y; and C-terminal 1/3 part, Z, respectively. The DNA fragments were cloned into pGEX-4T vector. Recombinant plasmids transformed into Escherichia coli of BL21 pLysS (DE3) strain were induced to express GST or GST fused fragments of Nc-p43 such as 69 kDa protein for T, 66 kDa for S, 52 kDa for A, 53 kDa for P, and 40 kDa proteins for X, Y, and Z, respectively in SDS-PAGE. The Nc-p43 fragments of T, S, and P reacted with a bovine serum of neosporosis while those of A, X, Y, and Z together with GST did not in the western blot. These findings suggest that the antigenic domain of Nc-p43 of N. caninum may be localized in the C-terminal 2/3 parts. Together with A19 clone in SAG1 of Toxoplasma gondii (Nam et al., 1996), the P fragment of Nc-p43 could be used as efficient antigens to diagnose and differentiate those infections with both species.

Recombinant proteins produced by vaccinia virus vectors can be incorporated within the virion (IMV form) into different compartments

Vaccinia virus (VV) is one of the largest and most complex of animal viruses, with a virion that contains about 100 different polypeptides. Assembly of the viral proteins occurs in discrete cytoplasmic sites leading to formation of two infectious forms, an abundant (>90%) intracellular mature virus (IMV) with an envelope, and a minor extracellular enveloped virus (EEV) with an extra membrane acquired from the trans-Golgi network. It has been shown that while EEV contains in the outer membrane cellular proteins probably acquired during virus release from cells, however, IMV exclude host proteins during assembly. Since VV recombinants (VVr) expressing genes of interest are candidates as potential vaccines against pathogens and cancer, it becomes important to know if VVr can acquire foreign proteins during morphogenesis. In this investigation we show that purified virions (IMVs) from VVr can incorporate foreign proteins into different sites in the virus particle. By sequential fractionation of virion compartments with detergents, we found foreign proteins in the lipid envelope (cytokine IL-12 and CS antigen of Plasmodium yoelii), as part of a protein matrix-like membrane (HIV-1 gp41 of env), or more closely associated with the core containing the DNA complexes (HIV-1 gp160; a multiepitopic protein with the V3 loop of HIV-1 Env from different isolates, and beta-galactosidase). Similar findings were observed with purified virions derived from the WR strain as well as from the highly attenuated modified vaccinia virus Ankara (MVA) strain. These observations should be taken into consideration when VVr are used in clinical trials or in other vaccination approaches.

Towards the Toxoplasma gondii proteome: position of 13 parasite excretory antigens on a standardized map of two-dimensionally separated tachyzoite proteins

High resolution two-dimensional separation of Toxoplasma gondii tachyzoite lysate revealed up to 224 distinct protein spots in Coomassie-stained gel. Computional matching of 14 digitized gels yielded a standard two-dimensional proteome map. The excretory T. gondii dense granule proteins GRA1-GRA8, S16/acid phosphatase, nucleoside triphosphate hydrolase, and H4 were identified by Western blotting of both total gel and isolated protein spots. In addition, two excretory antigens defined by parasite-specific monoclonal T cells, p36 and p40, were mapped by a novel T-cell blotting technique based on electroeluting single protein spots and testing the eluates for antigenic activity against the T-cell clones. In summary, these results represent a first step in Toxoplasma proteome analysis.

A alpha-glycerophosphate dehydrogenase is present in Trypanosoma cruzi glycosomes

alpha-glycerophosphate dehydrogenase (alpha-GPDH-EC.1.1.1.8) has been considered absent in Trypanosoma cruzi in contradiction with all other studied trypanosomatids. After observing that the sole malate dehydrogenase can not maintain the intraglycosomal redox balance, GPDH activity was looked for and found, although in very variable levels, in epimastigotes extracts. GPDH was shown to be exclusively located in the glycosome of T. cruzi by digitonin treatment and isopycnic centrifugation. Antibody against T. brucei GPDH showed that this enzyme seemed to be present in an essentially inactive form at the beginning of the epimastigotes growth. GPDH is apparently linked to a salicylhydroxmic-sensitive glycerophosphate reoxidizing system and plays an essential role in the glycosome redox balance.

Intramitochondrial localization of universal minicircle sequence-binding protein, a trypanosomatid protein that binds kinetoplast minicircle replication origins

Kinetoplast DNA (kDNA), the mitochondrial DNA of the trypanosomatid Crithidia fasciculata, is a unique structure containing 5,000 DNA minicircles topologically linked into a massive network. In vivo, the network is condensed into a disk-shaped structure. Replication of minicircles initiates at unique origins that are bound by universal minicircle sequence (UMS)-binding protein (UMSBP), a sequence-specific DNA-binding protein. This protein, encoded by a nuclear gene, localizes within the cell's single mitochondrion. Using immunofluorescence, we found that UMSBP localizes exclusively to two neighboring sites adjacent to the face of the kDNA disk nearest the cell's flagellum. This site is distinct from the two antipodal positions at the perimeter of the disk that is occupied by DNA polymerase beta, topoisomerase II, and a structure-specific endonuclease. Although we found constant steady-state levels of UMSBP mRNA and protein and a constant rate of UMSBP synthesis throughout the cell cycle, immunofluorescence indicated that UMSBP localization within the kinetoplast is not static. The intramitochondrial localization of UMSBP and other kDNA replication enzymes significantly clarifies our understanding of the process of kDNA replication.

Morphological and genetic differentiation of Rodentolepis straminea (Goeze, 1752) and Rodentolepis microstoma (Dujardin, 1845) (Hymenolepididae)

The two related species, Rodentolepis straminea (Goeze, 1782) and Rodentolepis microstoma (Dujardin, 1845) (Cestoda, Hymenolepididae), both parasites of rodents, were compared morphologically and electrophoretically. Adult worms were isolated from three wild rodent species of the family Muridae (Apodemus flavicollis, Apodemus sylvaticus, and Mus musculus) from three different sites in Spain and France. Although these two species were strikingly similar in morphological appearance, some of the morphological and metrical features analysed (scolex, mature segments and eggs) can be used for differentiation. Fixed allelic differences were found. Of the ten enzymes detected by starch-gel electrophoresis, six (AAT, AK, GPI, MDH, NP, PGM) showed characteristic isoenzyme profiles in each species. Only in MPI, PEPC, PEPD, and ME enzyme loci were no differences found. The study revealed that the two taxa can be clearly differentiated.

Dipsticks for rapid detection of plasmodium in vectoring anopheles mosquitoes

Malaria remains the most serious vector-borne disease, affecting some 300-500 million people annually, transmitted by many species of Anopheles mosquitoes (Diptera: Culicidae). Monoclonal antibodies developed against specific circumsporozoite (CS) proteins of the main malaria parasites Plasmodium falciparum and P. vivax have been used previously for enzyme-linked immunosorbent assays (ELISA), widely employed for detection of malaria sporozoites in vector Anopheles for local risk assessment, epidemiological studies and targeting vector control. However, ELISA procedures are relatively slow and impractical for field use. To circumvent this, we developed rapid wicking assays that identify the presence or absence of specific peptide epitopes of CS protein of the most important P. falciparum and two strains (variants 210 and 247) of the more widespread P. vivax. The resulting assay is a rapid, one-step procedure using a 'dipstick' wicking test strip. In laboratory assessment, dipsticks identified 1 ng/ mL of any of these three CS protein antigens, with sensitivity nearly equal to the CS standard ELISA. We have developed and are evaluating a combined panel assay that will be both qualitative and quantitative. This quick and easy dipstick test (VecTest Malaria) offers practical advantages for field workers needing to make rapid surveys of malaria vectors.