Antisporozoite Antibodies with Protective and Nonprotective Activities: In Vitro and In Vivo Correlations Using Plasmodium gallinaceum, an Avian Model

ABSTRACT. A correlation was observed between in vivo and in vitro activity of six monoclonal antibodies (mAb) against the major circumsporozoite protein of the avian malaria Plasmodium gallinaceum as follows. (1) Two mAb were protective, totally abrogating sporozoite infectivity to chicks, its natural host, in vivo; they caused 100% inhibition of sporozoite invasion (ISI) in vitro to SL-29 chicken fibroblasts and intense ISI to cultured chicken macrophages, as well as inhibited the exoerythrocytic development of sporozoites taken up by macrophages, the initial cell host of P. gallinaceum sporozoites. (2) Two mAb were partially protective in that they reduced sporozoite infectivity to chicks, caused partial ISI to SL-29 and macrophage cells and partial inhibition to the exoerythrocytic development of sporozoites in macrophages in vitro. (3) Two mAb were totally inactive in vivo although they both bound to the sporozoite antigens as detected by indirect immunofluorescence, western blot, and ELISA; they both failed to induce ISI or inhibit the exoerythrocytic development in macrophages. The possible participation of macrophages as the initial cell type involved in sporozoite destruction in the presence of anti-circumsporozoite antibodies is discussed.     

Common Epitopes In the Circumsporozoite Proteins of Plasmodium Berghei and Plasmodium Gallinaceum Identified By Monoclonal Antibodies to the P. Gallinaceum Circumsporozoite Protein

ABSTRACT. Monoclonal antibodies that react with the circumsporozoite protein of the avian malaria Plasmodium gallinaceum sporozoites also reacted with circumsporozoite protein of the rodent malaria Plasmodium berghei. Two types of reactivity were identified: 1) two monoclonal antibodies reacted with P. berghei sporozoite protein by enzyme-linked immunosorbent assay, Western blot and indirect immunofluorescence antibody, 2) six other monoclonal antibodies reacted with P. berghei sporozoites by ELISA and Western blot only. We studied whether these differences could be explained by reactivity in enzyme-linked immunosorbent assay with different P. berghei circumsporozoite peptides. Although all P. gallinaceum monoclonal antibodies reacted with the P. berghei repeats, the first group reacted with a conserved peptide sequence, N1, whereas the second group did not. These results suggest that circumsporozoite proteins from P. gallinaceum and P. berghei share common epitopes. the biological significance of our finding is not yet clear. Indeed, the cross-reactive monoclonal antibodies giving a positive indirect immunofluorescence antibody with the P. berghei sporozoites only caused a borderline effect on the living P. berghei parasites in vitro as measured by inhibition of sporozoite infectivity.     

Karyotype analysis in South American species of Myrtaceae

In Myrtaceae (Myrteae), the diploid chromosome number 2 n  = 2 x  = 22 is the most common, although variations of ploidy level occur, with some triploid (2 n  = 3 x  = 33) and tetraploid (2 n  = 4 x  = 44) records. Karyotype details in this group are scarce because the chromosomes are small (< 2 μm). In this work, we carried out a karyotypic analysis of 15 species of Myrtaceae grouped in different subtribes and genera. Measurements of chromosome length (long arm, L ; short arm, S ) were taken and several karyotypic parameters were calculated for each species. The karyotypes in fleshy-fruited taxa (Myrteae) were more varied than in the other previously analysed dry-fruited group ( Eucalyptus , Eucalypteae), in which the chromosomes were exclusively metacentric.  © 2007 The Linnean Society of London, Botanical Journal of the Linnean Society, 2007, 155 , 571–580.     

Chromosome numbers in Brazilian species of Crotalaria (Leguminosae, Papilionoideae) and their taxonomic significance

Chromosome numbers were counted for 23 species of Crotalaria native to Brazil. Among these data there were new counts for 15 taxa, and some confirmed previous reports or represented numbers that were different from those cited previously. The chromosome numbers most frequently found were 2 n  = 16 and 2 n  = 32. Only C. incana L. had 2 n  = 14 and C. tweediana Benth. had 2 n  = 54. The counts 2 n  = 32 and 54 were found in species of section Calycinae and 2 n  = 16 and 14 in species of section Chrysocalycinae . The data revealed the importance of chromosomal parameters in the characterization of sections Calycinae and Chrysocalycinae in Brazil. We discuss the systematic significance and evolutionary aspects for the genus, comparing the results with the two sections that are native in Brazil.  © 2006 The Linnean Society of London, Botanical Journal of the Linnean Society , 2006, 151 , 271–277.     

Linking frugivore activity to early recruitment of a bird dispersed tree,Eugenia umbelliflora (Myrtaceae) in the Atlantic rainforest

Seed dispersal by animals is a complex process involving several distinct stages: fruit removal by frugivores, seed delivery in different microhabitats, seed germination, seedling establishment, and adult recruitment. Nevertheless, studies conducted until now have provided scarce information concerning the sequence of stages in a plant's life cycle in its entirety. The main objective of this study was to evaluate the immediate consequences of frugivore activity for Eugenia umbelliflora (Myrtaceae) early recruitment by measuring the relative importance of each fruit‐eating bird species on the establishment of new seedlings in scrub and low restinga vegetation in the Atlantic rainforest, Brazil. We conducted focal tree observations on E. umbelliflora trees recording birds' feeding behaviour and post‐feeding movements. We also recorded the fate of dispersed seeds in scrub and low restinga vegetation. We recorded 17 bird species interacting with fruits in 55 h of observation. Only 30% of the handled fruits were successfully removed. From 108 post flight movements of exit from the fruiting trees, 30.6% were to scrub and 69.4% to low restinga forest. Proportion of seed germination was higher in low restinga than in the scrub vegetation. Incorporating the probabilities of seeds' removal, deposition, and germination in both sites, we found that the relative importance of each frugivorous bird as seed dispersers varies largely among species. Turdus amaurochalinus and Turdus rufiventris were the best dispersers, together representing almost 12% probability of seed germination following removal. Our results show the importance of assessing the overall consequence of seed dispersal within the framework of disperser effectiveness, providing a more comprehensive and realistic evaluation of the relative importance of different seed dispersers on plant population dynamics.     

Exoerythrocytic Development of Plasmodium Gallinaceum Sporozoites In A Chicken Fibroblast Cell Line and Inhibition of the Cell Invasion By Specific Anti-Sporozoite Monoclonal Antibodies

ABSTRACT. Cultivation of the Plasmodium gallinaceum exoerythrocytic forms from sporozoites was attempted in three diferent cell lines: HEPG2-A16 (from a human hepatoma), VERO (monkey kidney epithelial cells) and SL-29 (chicken embryo fibroblast cells). the sporozoites in vaded all three cell types but their development into exoerythrocytic forms ocurred only in the SL-29 cells. In the presence of specific monoclonal antibodies against the major circumsporozoite protein, there were varying degrees of inhibition of parasite invasion of the SL-29 cells. of seven monoclonal antibodies tested, two completely inhibited cell invasion at high concentrations and caused intense inhibition at concentrations as low as 2.5 μg/ml, four caused intense inhibition at these various concentrations, and one had no effect on sporozoite invasion.     

Cytotaxonomy of Lychnophoriopsis Sch.Bip. and Paralychnophora MacLeish species (Asteraceae: Vernonieae: Lychnophorinae)

The genera Lychnophoriopsis and Paralychnophora are endemic to Brazilian 'campo rupestre' in the States of Minas Gerais and Bahia. To analyse the status of the cytotaxonomy of these genera, we carried out chromosome counts on several species. Two chromosome numbers were obtained for four species of Paralychnophora : 2 n  = 36 and 2 n  = 38. For three species of Lychnophoriopsis , only 2 n  = 36 was observed. The chromosome size (1.0–2.58 µm) and morphology (mainly metacentric, with some submetacentric) were analysed in four species of Paralychnophora and showed relative constancy .   © 2007 The Linnean Society of London. Botanical Journal of the Linnean Society , 2007, 154 , 109–114.     

Observation of some key stages of the embryonic development of Biomphalaria straminea (Dunker, 1848) (Molluska,Planorbidae)

Summary

Biomphalaria straminea is a freshwater snail and one of the intermediate hosts of the trematode parasite which causes schistosomiasis in Brazil. The main stages of embryonic development were analyzed with confocal laser scanning microscopy (CLSM), using the fluorescent probe DiOC and Nile Red as a vital stain in in vivo preparations. In fixed preparations nuclei were stained by the Feulgen reaction or the fluorescent DNA probe, Höechst 33342. Results obtained from the analysis of embryos at the stages of early cleavage, morula, blastula, gastrula, early trocophore and veliger showed that these stages are similar to those described for Biomphalaria glabrata and Biomphalaria tenagophila. CLSM optical sections of early trochophore showed important morphological structures such as the blastopore, stomodeum and shell gland; and in early veliger, internal organs such as the esophagus, stomach and male and female ducts were also clearly identified.     

Cytotaxonomy of species of Vernonia, section Lepidaploa, group Axilliflorae (Asteraceae, Vernonieae)

Mitotic chromosomes of eight populations of six species of Vernonia sensu Baker (Asteraceae, Vernonieae, section Lepidaploa , group Axilliflorae ) were studied to assess the validity of maintaining the genus as proposed currently ( sensu Baker) or of splitting it into several smaller genera ( sensu Robinson). The species were collected in areas of 'cerrado' and 'campo rupestre' in southern and central-western Brazil. The chromosome numbers were 2 n  = 20–40 and karyotypic analysis showed a predominance of metacentric chromosomes, with some submetacentrics. B chromosomes were seen in one population of V. geminata . The chromosomes varied in length from 0.9 to 4.6 µm, with a total chromatin length of 29.7–45.0 µm and a symmetry index of 41.2–46.9%. The intrachromosomal asymmetry index varied from 0.13 to 0.29, and the interchromosomal asymmetry index varied from 0.15 to 0.21. The dispersion diagram showed that population 1 of V. geminata had the most asymmetrical karyotype. These results do not provide sufficient evidence for a conclusive cytotaxonomic discussion of Vernonia , mainly because of the impossibility of associating any infrageneric group with specific karyotypic characters, and also because of the small number of species analysed so far.  © 2007 The Linnean Society of London. Botanical Journal of the Linnean Society , 2007, 154 , 99–108.