Colonization and extinction of land planarians (Platyhelminthes,Tricladida) in a Brazilian Atlantic Forest regrowth remnant

Long-term assessments of species assemblages are valuable tools for detecting species ecological preferences and their dispersal tracks, as well as for assessing the possible effects of alien species on native communities. Here we report a 50-year-long study on population dynamics of the four species of land flatworms (Platyhelminthes, Tricladida, Terricola) that have colonized or become extinct in a 70-year-old Atlantic Forest regrowth remnant through the period 1955–2006. On the one hand, the two initially most abundant species, which are native to the study site, Notogynaphallia ernesti and Geoplana multicolor have declined over decades and at present do not exist in the forest remnant. The extinction of these species is most likely related with their preference for open vegetation areas, which presently do not exist in the forest remnant. On the other hand, the neotropical Geoplaninae 1 and the exotic Endeavouria septemlineata were detected in the forest only very recently. The long-term study allowed us to conclude that Geoplaninae 1 was introduced into the study area, although it is only known from the study site. Endeavouria septemlineata, an active predator of the exotic giant African snail, is originally known from Hawaii. This land flatworm species was observed repeatedly in Brazilian anthropogenic areas, and this is the first report of the species in relatively well preserved native forest, which may be evidence of an ongoing adaptive process. Monitoring of its geographic spread and its ecological role would be a good practice for preventing potential damaging effects, since it also feeds on native mollusk fauna, as we observed in lab conditions. Júlio Pedroni: Granted by CNPQ–Brazil.     

Ultrastruttura della cellula apicale di Halopteris scoparia (L.) Sauvageau (Phaeophyceae,Sphacelariales)

Abstract

Ultrastructure of the apical cell of Halopteris scoparia (L.) Sauvageau (Phaeophyceae, Sphacelariales). - The ultrastructure of resting apical cells of Halopteris scoparia (L.) Sauvageau from material collected in December is described. The cytoplasm is higly vacuolated with lipids, poliphenolic substances and polisaccharides occurring inside the vacuoles (the classic « physodes »).

Two cell organelles are prominently active at this stage: conspicuosly hypertrophic dictyosomes and the budding endoplasmic reticulum. Both light and electron microscope observations show that the cell wall has an outer stratification and inner discontinuous thickenings, the constituent material of which is uniformerly dispersed.

The above observations point out that the apical cell of Halopteris scoparia at this stage of its life cycle is engaged in an elaboration of vacuolar and parietal substances which will be therefore readly available at the outset of the growing season.     

Liver Accumulation of Plasmodium chabaudi-Infected Red Blood Cells and Modulation of Regulatory T Cell and Dendritic Cell Responses

It is postulated that accumulation of malaria-infected Red Blood Cells (iRBCs) in the liver could be a parasitic escape mechanism against full destruction by the host immune system. Therefore, we evaluated the in vivo mechanism of this accumulation and its potential immunological consequences. A massive liver accumulation of P. c. chabaudi AS-iRBCs (Pc-iRBCs) was observed by intravital microscopy along with an over expression of ICAM-1 on day 7 of the infection, as measured by qRT-PCR. Phenotypic changes were also observed in regulatory T cells (Tregs) and dendritic cells (DCs) that were isolated from infected livers, which indicate a functional role for Tregs in the regulation of the liver inflammatory immune response. In fact, the suppressive function of liver-Tregs was in vitro tested, which demonstrated the capacity of these cells to suppress naive T cell activation to the same extent as that observed for spleen-Tregs. On the other hand, it is already known that CD4+ T cells isolated from spleens of protozoan parasite-infected mice are refractory to proliferate in vivo. In our experiments, we observed a similar lack of in vitro proliferative capacity in liver CD4+ T cells that were isolated on day 7 of infection. It is also known that nitric oxide and IL-10 are partially involved in acute phase immunosuppression; we found high expression levels of IL-10 and iNOS mRNA in day 7-infected livers, which indicates a possible role for these molecules in the observed immune suppression. Taken together, these results indicate that malaria parasite accumulation within the liver could be an escape mechanism to avoid sterile immunity sponsored by a tolerogenic environment.     

Localization of Endo-Oligopeptidase (EC 3.4.22.19) in the Rat Nervous Tissue

The subcellular and regional distribution of endo-oligopeptidase (EC 3.4.22.19), an enzyme capable of generating enkephalin by single cleavage from enkephalin-containing peptides, was determined by an enzymatic assay using metorphamide and by immunochemical techniques in the CNS of the rat. The rat CNS contains a membrane-associated form of endo-oligopeptidase, an enzyme predominantly associated with the soluble fraction of brain homogenates. Subcellular fractionation showed that approximately 17% of the total activity of the enzyme is associated with membrane fractions including synaptosomes. Synaptosomal membranes were prepared from neocortex, striatum, hypothalamus, medulla, spinal cord, and cerebellum. The amount of EC 3.4.22.19 activity solubilized by 3-[( 3-cholamidopropyl]dimethylammonio)-1-propanesulfonate from synaptosomal membranes was similar in neocortex, striatum, and hypothalamus, being three- to 10-fold greater than in spinal cord, cerebellum, and medulla. A polyclonal antibody exhibiting high affinity for endo-oligopeptidase was raised in rabbits against the purified rat brain enzyme and used to localize endo-oligopeptidase by Western blotting and by immunoperoxidase techniques. A strong band corresponding to the Mr of EC 3.4.22.19 was found in solubilized proteins obtained from synaptosomal membranes prepared from hypothalamus, neocortex, and striatum when subjected to Western blotting. The immunohistochemical localization of endo-oligopeptidase indicated that the immunoreactivity was confined to gray matter in regions known to be rich in peptide-containing neurons such as the striatum. In the cerebellum, a region poor in peptides, no staining could be detected. The nonuniform distribution of endo-oligopeptidase in rat brain suggests a role in neurotransmitter processing in the CNS.     

Multiple Bacteriocin Production by Leuconostoc mesenteroidesTA33a and Other Leuconostoc/Weissella Strains

Leuconostoc (Lc.) mesenteroides TA33a produced three bacteriocins with different inhibitory activity spectra. Bacteriocins were purified by adsorption/desorption from producer cells and reverse phase high-performance liquid chromatography. Leucocin C-TA33a, a novel bacteriocin with a predicted molecular mass of 4598 Da, inhibited Listeria and other lactic acid bacteria (LAB). Leucocin B-TA33a has a predicted molecular mass of 3466 Da, with activity against Leuconostoc/Weissella (W.) strains, and appears similar to mesenterocin 52B and dextranicin 24, while leucocin A-TA33a, which also inhibited Listeria and other LAB strains, is identical to leucocin A-UAL 187. A survey of other known bacteriocin-producing Leuconostoc/Weissella strains for the presence of the three different bacteriocins revealed that production of leucocin A-, B- and C-type bacteriocins was widespread. Lc. carnosum LA54a, W. paramesenteroides LA7a, and Lc. gelidum UAL 187-22 produced all three bacteriocins, whereas W. paramesenteroides OX and Lc. carnosum TA11a produced only leucocin A- and B-type bacteriocins. Received: 11 April 1997 / Accepted: 10 June 1997     

Guaraná (Paullinia cupana) as a commercial crop in Brazilian Amazonia

Guaraná (Paullinia cupana) is a woody vine or sprawling shrub native to the central Amazon Basin. The seeds are commercially produced on some 6,000 ha in the state of Amazonas near Manaus. The principal article of commerce is an amber-colored, carbonated soft drink. It is also widely used as a high caffeine stimulant and in local medicines. The plant is monoecious and is damaged by a number of diseases, the most severe being anthracnose. Prospects are excellent for greatly expanded international markets.     

Study of Poaceae phenology in a Mediterranean climate. Which species contribute most to airborne pollen counts?

The present study sought to determine which of the common Poaceae species in the study area contribute most to the Poaceae pollen season curve, and to determine the phenological behaviour of the species studied. The different floral phenophases in thirty-three Poaceae species common in and around the city of Córdoba (SW Iberian Peninsula) were checked periodically over the period 2004–2006. Results showed that longer phenological ranges were recorded in the coolest and wettest year, and shorter ranges in the warmest and driest year. Moreover, ranges varied as a function of altitude: populations in lower-lying areas flowered earlier than those at higher altitudes. The results, taken in conjunction with the findings of preliminary research into potential pollen production, showed that probably only four of the Poaceae species studied—Dactylis glomerata, Lolium rigidum, Trisetaria panicea and Vulpia geniculata—were major contributors to the Poaceae airborne pollen curve.     

Vacuolation induced by VacA toxin of Helicobacter pylori requires the intracellular accumulation of membrane permeant bases, Cl(-) and water.

The protein vacuolating toxin A (VacA) of Helicobacter pylori converts late endosomes into large vacuoles in the presence of permeant bases. Here it is shown that this phenomenon corresponds to an accumulation of permeant bases and Cl(-) in HeLa cells and requires the presence of extracellular Cl(-). The net influx of Cl(-) is due to electroneutral, Na(+), K(+), 2Cl(-) cotransporter-mediated transport. Cell vacuolation leads to cell volume increase, consistent with water flux into the cell, while hyper-osmotic media decreased vacuole formation. These data represent the first evidence that VacA-treated cells undergo an osmotic unbalance, reinforcing the hypothesis that the VacA chloride channel is responsible for cell vacuolation.