Effect of Eimeria falciformis infection on the development of toxoplasmosis in mice

White mice previously infected with 10(2), 10(3) or 10(4) Eimeria falciformis oocysts on days 0, 5, 10 or 30 were inoculated per os with 10(1), 10(2), 10(3) or 10(4) Toxoplasma oocysts. While the results obtained for mice with higher Toxoplasma inocula were consistent, animals with 10(1) and 10(2) oocysts previous inoculation with Eimeria showed important differences related with those infected only with Toxoplasma. For example, survival time was higher in animals infected with both parasites, especially if inoculated with Eimeria 30 days before Toxoplasma infection. Furthermore the number of T. gondii cysts found in the animals previously infected with Eimeria was lower compared with mice inoculated with Toxoplasma only. Body weight of mice infected with Toxoplasma previous infection with Eimeria was almost normal in relation to those infected only with Toxoplasma, indicating a probable pathological effect due to the parasite, more evident in "non immunized" mice.     

Effect of corticosteroids on the congenital transmission of experimental toxoplasmosis]

Female white mice with chronic toxoplasmosis were treated with cortisone acetate (3mg for each 25 g of body weight) 12, 8, 4 and 0 days before mating. Cortisone induces congenital transmission of T. gondii.     

First record of a potential neonate tiger shark (Galeocerdo cuvier) at a remote oceanic island in the Eastern Tropical Pacific

Tiger sharks (Galeocerdo cuvier) play an important ecological role as top predators, yet knowledge of their reproductive ecology is scarce. Here, the authors report the first observation of a potential neonate G. cuvier at Cocos Island, a predator-dominated oceanic island in the Eastern Tropical Pacific (ETP). The individual was detected using baited remote underwater video stations (BRUVS). The cameras also detected female individuals potentially pregnant, suggesting that parturition may take place at or near the island. Nonetheless, it is still unclear if the presence of a single neonate is an isolated event or evidence that the species is using the island for reproduction.     

Effect of Trypanosoma lewisi (Kinetoplastida: Trypanosomatidae) on the infection of white rats with Toxoplasma gondii (Eucoccidia: Sarcocystidae) oocysts

White rats were inoculated with 10(6) trypomastigotes of Trypanosoma lewisi, simultaneously or two days before and after inoculation with 10(5) oocysts of T. gondii. A greater number of cysts was found in the brain of the animals having concomitant inoculations, as compared with rats inoculated with either one of the two parasites. An apparent immunosuppressive effect is likely. Since both organisms can be found in rats, it is possible that infections with T. lewisi, could make this rodent another intermediate host for Toxoplasma infections.     

Intestinal parasites in howler monkeys Alouatta palliata (Primates: Cebidae) of Costa Rica

Fecal samples of 102 howler monkeys (Alouatta palliata) from several sites of Costa Rica were studied for intestinal parasites. The zones studied were: Central Valley (San Ramón, Alajuela), Central Pacific (Chomes and Manuel Antonio National Park. Puntarenas), North Pacific (Palo Verde Park and Playa Potrero, Guanacaste). Chira Island in the Nicoya Gulf and Caribean area (Cahuita. Limón). Animals were anesthetized with dards containing Telazol in order to collect the fecal material; some monkeys defecated spontaneously and others by direct stimulation. Samples were studied in saline solution (0.85%) and a Iodine solution, or stained with Haematoxylin. The material was also cultured in Dobell culture medium to determine the presence of amoeba and flagellates. Strongvloides. Controrchis. Trypanoxyuris genera were found in 3.4% of the samples. In addition 16.7% to 80% of the animals showed protozoa infection with Endolimax, Entamoeba, Trichomonas and Giardia. It is discussed the relationships of parasite infection with environmental conditions, animal population and human presence, specially in the monkey conservation programs point of view.     

Leaf-cutting ants as road engineers: the width of trails at branching points in <Emphasis Type="Italic">Atta cephalotes</Emphasis>

We used a simple engineering principle, which suggests that the width of a road needed for a smooth traffic flow is proportional to the peak traffic volume (“engineering hypothesis”), to analyze the adaptive significance of trail width at branching points in the leaf-cutting ant Atta cephalotes. Since the flow of outgoing ants splits at trail bifurcations and merges when ants return to the nest through the same paths, the sum of branch widths should equal the width of the trail section upstream of the bifurcation. We measured the width of branches and their preceding trail section and also performed field measurements and manipulations to analyze ant flow, number of collisions, and ant speed in different trail sectors. Contrary to the prediction of the “engineering hypothesis”, the sum of branch widths was larger than the width of the trail immediately before the bifurcation. Our data contradict the “trail addition hypothesis” and support the “border effect hypothesis” to explain this pattern. First, the width of the widest branch was smaller than the width of the trail upstream of the bifurcation, an unexpected result if one branch is merely the continuation of the basal trail. Second, ants collided with obstacles more often in the margin than in the central portion of the trail, relocated ants from central to margin trail sectors reduced their speed, and ant flow was higher in the central sections of the trail. Since the delaying effect of trail margins increases as the trail width decreases, ants may build branches wider than expected to reduce the border effect. The delaying effect of trail margins should be included in the analysis of costs and benefits to fully understand the adaptive value of the design of ant trail networks.     

Bacterial polysaccharides suppress induced innate immunity by calcium chelation

Bacterial pathogens and symbionts must suppress or negate host innate immunity. However, pathogens release conserved oligomeric and polymeric molecules or MAMPs (Microbial Associated Molecular Patterns), which elicit host defenses [1], [2] and [3]. Extracellular polysaccharides (EPSs) are key virulence factors in plant and animal pathogenesis, but their precise function in establishing basic compatibility remains unclear [4], [5], [6] and [7]. Here, we show that EPSs suppress MAMP-induced signaling in plants through their polyanionic nature [4] and consequent ability to chelate divalent calcium ions [8]. In plants, Ca2+ ion influx to the cytosol from the apoplast (where bacteria multiply [4], [5] and [9]) is a prerequisite for activation of myriad defenses by MAMPs [10]. We show that EPSs from diverse plant and animal pathogens and symbionts bind calcium. EPS-defective mutants or pure MAMPs, such as the flagellin peptide flg22, elicit calcium influx, expression of host defense genes, and downstream resistance. Furthermore, EPSs, produced by wild-type strains or purified, suppress induced responses but do not block flg22-receptor binding in Arabidopsis cells. EPS production was confirmed in planta, and the amounts in bacterial biofilms greatly exceed those required for binding of apoplastic calcium. These data reveal a novel, fundamental role for bacterial EPS in disease establishment, encouraging novel control strategies.     

Control of the pattern‐recognition receptor EFR by an ER protein complex in plant immunity

In plant innate immunity, the surface‐exposed leucine‐rich repeat receptor kinases EFR and FLS2 mediate recognition of the bacterial pathogen‐associated molecular patterns EF‐Tu and flagellin, respectively. We identified the Arabidopsis stromal‐derived factor‐2 (SDF2) as being required for EFR function, and to a lesser extent FLS2 function. SDF2 resides in an endoplasmic reticulum (ER) protein complex with the Hsp40 ERdj3B and the Hsp70 BiP, which are components of the ER‐quality control (ER‐QC). Loss of SDF2 results in ER retention and degradation of EFR. The differential requirement for ER‐QC components by EFR and FLS2 could be linked to N‐glycosylation mediated by STT3a, a catalytic subunit of the oligosaccharyltransferase complex involved in co‐translational N‐glycosylation. Our results show that the plasma membrane EFR requires the ER complex SDF2–ERdj3B–BiP for its proper accumulation, and provide a demonstration of a physiological requirement for ER‐QC in transmembrane receptor function in plants. They also provide an unexpected differential requirement for ER‐QC and N‐glycosylation components by two closely related receptors.