Development of a cyanobacterial biolarvicide

Results of studies on a larvicidal cyanobacterium that expresses a Bti cryIVD gene fusion are reported. Genetically altered Agmenellum quadruplicatum PR-6 is shown to be toxic to larvae of three major genera of disease-bearing mosquitos. Factors affecting expression of Bti genes in cyanobacteria are discussed.

Cyanobacterial occurrence and detection of microcystin by planar chromatography in surface water of Billings and Guarapiranga Reservoirs, SP, Brazil

Billings and Guarapiranga Reservoirs were deeply affected by environmental disturbances, which more evident consequence are the cyanobacterial blooms. Microcystins are the most common cyanotoxin in freshwaters and more than 70 types are known. Different methods for microcystins analysis in water can be used, among which ELISA and HPLC are the most frequently employed. However, less sophisticated and more economic methods can also be used. This is the case of planar chromatography (thin-layer chromatography) method previously used in cyanotoxins purification but gradually replaced by others. Posterior optimization of the microcystin chromatography conditions and because of its simplicity, rapidity, efficiency and low cost, this method is again considered an option for the analysis of microcystins and nodularins. Considering the importance of Billings and Guarapiranga Reservoirs for drinking water supplies and the few scientific data about cyanobacteria and cyanotoxins in these water bodies, the aims of this work are to analyze the biodiversity of cyanobacteria in the Billings and Guarapiranga Reservoirs and the detection of dissolved microcystins in the water. It was possible to identify 17 species of cyanobacteria, 9 of them being potentially toxic. In Billings Reservoir Microcystis aeruginosa (Kützing) Kützing and Cylindrospermopsis raciborskii (Woloszynska) Seenayya & Subba Raju are the most common species, while in Guarapiranga Reservoir only M. aeruginosa was considered as a common species. Microcystins were detected in all Billings Reservoir samples and in only one sample from Guarapiranga Reservoir.

Cyanobacterial toxins in Portugal: effects on aquatic animals and risk for human health

Toxic cyanobacteria are common in Portuguese freshwaters and the most common toxins are microcystins. The occurrence of microcystin-LR (MCYST-LR) has been reported since 1990 and a significant number of water reservoirs that are used for drinking water attain high levels of this toxin. Aquatic animals that live in eutrophic freshwater ecosystems may be killed by microcystins but in many cases the toxicity is sublethal and so the animals can survive long enough to accumulate the toxins and transfer them along the food chain. Among these, edible mollusks, fish and crayfish are especially important because they are harvested and sold for human consumption. Mussels that live in estuarine waters and rivers where toxic blooms occur may accumulate toxins without many significant acute toxic effects. In this study data are presented in order to understand the dynamics of the accumulation and depuration of MCYST-LR in mussels. The toxin is readily accumulated and persists in the shellfish for several days after contact. In the crayfish the toxin is accumulated mainly in the gut but is also cleared very slowly. In carps, although the levels of the toxins found in naturally caught specimens were not very high, some toxin was found in the muscle and not only in the viscera. This raises the problem of the toxin accumulation by fish and possible transfer through the food chain. The data gathered from these experiments and from naturally caught specimens are analyzed in terms of risk for human consumption. The occurrence of microcystins in tap water and the incidence of toxic cyanobacteria in fresh water beaches in Portugal are reported. The Portuguese National Monitoring Program of cyanobacteria is mentioned and its implications are discussed.

Toxicity of a cyanobacterial extract containing microcystins to mouse lungs

Toxic cyanobacteria in drinking water supplies can cause serious public health problems. In the present study we analyzed the time course of changes in lung histology in young and adult male Swiss mice injected intraperitoneally (ip) with a cyanobacterial extract containing the hepatotoxic microcystins. Microcystins are cyclical heptapeptides quantified by ELISA method. Ninety mice were divided into two groups. Group C received an injection of saline (300 µl, ip) and group Ci received a sublethal dose of microcystins (48.2 µg/kg, ip). Mice of the Ci group were further divided into young (4 weeks old) and adult (12 weeks old) animals. At 2 and 8 h and at 1, 2, 3, and 4 days after the injection of the toxic cyanobacterial extract, the mice were anesthetized and the trachea was occluded at end-expiration. The lungs were removed en bloc, fixed, sectioned, and stained with hematoxylin-eosin. The percentage of the area of alveolar collapse and the number of polymorphonuclear (PMN) and mononuclear cell infiltrations were determined by point counting. Alveolar collapse increased from C to all Ci groups (123 to 262%) independently of time, reaching a maximum value earlier in young than in adult animals. The amount of PMN cells increased with time of the lesion (52 to 161%). The inflammatory response also reached the highest level earlier in young than in adult mice. After 2 days, PMN levels remained unchanged in adult mice, while in young mice the maximum number was observed at day 1 and was similar at days 2, 3, and 4. We conclude that the toxins and/or other cyanobacterial compounds probably exert these effects by reaching the lung through the blood stream after ip injection.

Contribuição ao conhecimento dos Odonatos da Estação Ecológica de Maracá - Roraima.

Estudou-se a fauna odonatológica da Estação Ecológica de Maracá, no Estado de Roraima, com base em material coletado nas matas e campos de sua parte oriental. Foram coletadas 61 espécies das quais 3 são novas para a ciência (Epipleoneura, Leptobasisa. Lestes) e serão descritas em outro trabalho e 8 constituem novos registros para a fauna brasileira (Aeolagrion demerarum, Argia pulla, Hetaerina mortua, Hetaerina westfalli, Meta leptobasis manicaria., Neoneura denticulata, Neoneura gaida, Protoneura amatoria). Verificou-se que as espécies de grande distribuição geográfica, geralmente mais comuns, pre-dominam nas áreas de savana, enquanto nas matas predominam as de distribuição geográfica mats restrita. Os resultados ressaltam a grande semelhança que existe entre a fauna de Maracá e a da Venezuela.

Molecular mechanisms and biological importance of Plasmodium falciparum erythrocyte rosetting

Rosetting, i.e. the spontaneous binding of uninfected to malaria infected erythrocytes and endothelial cytoadherence may hinder the blood flow and lead to serve Plasmodium falciparum malaria. Falciparum isolates obtained from unconscious patients all form rosettes and/or express a significantly higher man rosetting rate than isolates from patients with uncomplicated malaria. Furthermore, sera of patients with cerebral malaria are devoid of anti-rosetting activity while sera from patients with mild disease carry high levels of anti-rosetting antibodies. The presence of anti-rosetting antibodies also seems important for the efficient interaction of rosetting infected rbc and leucocytes. Two parasite derived rosetting ligands of Mr 22k and Mr28K named "rosettins, have been found on the surface of rosetting infected erythrocytes. CD36 has in at least some strains of parasites been found to function as a rosetting receptor on the uninfectederythrocyte. Heparin disrupts rosettes of P. falciparum in vitro and inhibits the sequestration of rosetting cells ex vivo. In conclusion, rosetting seems a crucial factor in the development of cerebral malaria and treatment of patients with anti-rosetting substances might become an effectivew adjunct in the treatment of severe malaria.

Prozone effects in microscopic agglutination tests for leptospirosis in the sera of mice infected with the pathogenic Leptospira interrogans serovar Canicola

Mice experimentally infected with a pathogenic strain of Leptospira interrogans serovar Canicola produced false negative results (prozone effect) in a microscopic agglutination test (MAT). This prozone effect occurred in several serum samples collected at different post-infection times, but it was more prominent in samples collected from seven-42 days post-infection and for 1:50 and 1:100 sample dilutions. This phenomenon was correlated with increased antibody titres in the early post-infection phase. While prozone effects are often observed in serological agglutination assays for the diagnosis of animal brucellosis and human syphilis, they are not widely reported in leptospirosis MATs.

A new species of Stilobezzia Kieffer from the neotropical region (Diptera, Ceratopogonidae)

A new species from the Neotropical Region, Stilobezzia (Stilobezzia) pseudopunctulata Cazorla & Ronderos, is described and illustrated based on male and female adults and pupal exuviae. Adults were collected in the Argentinian provinces of Chaco, Formosa, Corrientes and Buenos Aires, and in Santa Cruz, Bolivia. The pupa was collected from mats of floating aquatic macrophytes in a lagoon in Ilha da Marchantería, in the vicinities of Manaus, Brazil. This new species is compared with its similar congener Stilobezzia punctulata Lane, from which it can be mainly distinguished by the wing with only two dark spots, the parameres longer and hook-shaped, the pupal respiratory organ with 11-12 pores and the very short apicolateral processes of the anal segment.

Bermuda grass sod production as related to nitrogen rates

Of all nutrients, N has the strongest effect on grass growth and an adequate N fertilization can reduce the time required for the formation of high-quality mats. This study aimed to evaluate the influence of N fertilization on Bermuda grass sod production and quality. The experiment was conducted in an area of commercial sod production, in Capela do Alto, state of São Paulo. Cynodon dactylon (Pers) L., known as Bermuda grass, was evaluated in a randomized complete block design with five treatments and four replications. Treatments consisted of five N rates: 0, 150, 300, 450 and 600 kg ha-1. Increasing N applications to Bermuda grass increased the soil cover rate, reducing the time required for mat formation. The accumulation of rhizome + root + stolon dry matter was highest at a rate of 354 kg ha-1 N and the mat resistance to breakage at a rate of 365 kg ha-1 N. Nitrogen rates between 354 and 365 kg ha-1 increased mat resistance and consequently the suitability for postharvest handling, tending to improve the efficiency in the area.

Planktic Cyanobacteria from São Paulo State, Brazil: Chroococcales

The biodiversity studies of planktic cyanobacteria started in 1997 with intensive collecting in different water bodies of São Paulo State. Due to the problems brougth by eutrophication and cyanobacterial blooms, the samplings were concentrated in reservoirs of Alto Tietê region that supply drinking water to millions of people. The samples were collected with 20 µm plankton net or Van Dorn's bottle. Part of each one was preserved in formaldehyde or lugol solution and part was isolated. The culture strains were kept in BG11 and/or AMS1 media. Based on natural and culture material, 26 species were identified belonging to the families Chroococcaceae (2 taxa), Merismopediaceae (12), Microcystaceae (7) and Synechococcaceae (5). Among these species, six are potentialy toxic: Aphanocapsa incerta (Lemmerm.) Cronberg & Komárek, Microcystis aeruginosa (Kütz.) Kütz., M. botrys Teiling, M. panniformis Komárek et al., M. wesenbergii (Komárek) Komárek, and Radiocystis fernandoi Komárek & Komár.-Legn. Bacularia and Coelosphaeriopsis are genera reported for the first time in Brazil.

Planktic Cyanobacteria from upper Tietê basin reservoirs, SP, Brazil

Considering the great ecological and sanitary importance of the cyanobacteria and the need of detailed information about these organisms in Brazilian water bodies, the present study aims at contributing towards the knowledge of the cyanobacterial flora of five reservoirs belonging to the upper Tietê Basin, São Paulo: Billings, Guarapiranga, Jundiaí, Pirapora, Ponte Nova and Taiaçupeba. In the past several years, these reservoirs have been submitted to severe environmental deterioration and have repeatedly presented cyanobacterial blooms, including those of toxic species. The samples were collected between 1997 and 2003 either with plankton net (20 µm mesh) or van Dorn's bottle, and preserved with lugol solution or formaldehyde. Some species were isolated and maintained in culture. Forty-eight species of cyanobacteria were identified, with predominance of the order Chroococcales (58%), followed by the orders Oscillatoriales (21%) and Nostocales (21%). Among the 48 studied species, 17 (35%) were considered potentially toxic. The occurrence and biodiversity of the cyanobacteria in each reservoir depend on the environmental conditions. Among the five water bodies, Billings Reservoir presented the most adequate situation for the development of a greater number of species (34), probably due to its high pH values (around 8). Pirapora Reservoir on the other hand, with highest conductivity (445.0 µS cm-1) and lowest Secchi depth values (0.2 m), presented the lowest cyanobacterial biodiversity (14 species).

Tropical inselbergs: habitat types, adaptive strategies and diversity patterns

Inselbergs are isolated rock outcrops that rise abruptly above the surrounding plains. Granitic and gneissic inselbergs are geologically and geomorphologically old and occur throughout a broad spectrum of climatic zones. They form microclimatically and edaphically dry growth sites that support a highly specialized vegetation. Based on physiognomic criteria a number of habitat types can be distinguished that are widespread on inselbergs (e.g. ephemeral flush vegetation, monocotyledonous mats, rock pools). Three hot spots of global inselberg plant diversity can be identified which are both rich in species and endemics: a) southeastern Brazil, b) Madagascar and c) southwestern Australia.

Subgeneric diversity of Brasilonema (Cyanobacteria, Scytonemataceae)

The recently described scytonematoid cyanobacterial genus Brasilonema is known mainly from tropical and subtropical rain forests (Mata Atlântica) of southeastern Brazil, where it occurs in aerophytic wooden, stony and iron substrates. This genus was defined according to both molecular and morphological criteria. The type species B. bromeliae was described from the specialized habitat: it grows in phytothelmes, epiphytic on both living and died leaves within the rosettes of large bromeliad plants slightly above or in the zone of the water level. The genus Brasilonema is evidently widely distributed in coastal forests of São Paulo State, where it occurs also in remarkable diversity. According to our results, this genus currently comprises seven taxa, which are distinct by different morphology and ecological characteristics.

Ecological distribution of stream macroalgae in different spatial scales using taxonomic and morphological groups

We examined the ecological distribution of macroalgal communities in streams using species groups (taxonomic units = algal phyla, and morphological = morphological types) with similar structures and functions instead of the species themselves. The study was conducted from June to July/2007 in two drainage basins located in mid-southern region of Paraná State , Brazil. Evaluations of macroalgal communities took into consideration the following spatial scales: the drainage basin (the Pedras river and Marrecas river basins), shading regime (open and shaded stream segments), mesohabitats (riffles and pools), and microhabitats (sampling units of 0.05m2). A total of 29 taxa (23 subgeneric, one generic, and five vegetative groups) were identified. On these, 12 taxa belong to Chlorophyta, 11 to Cyanobacteria, four to Heterokontophyta, and two to Rhodophyta. The proportions of morphological types were: 24% free filaments, 17.25% mats, tufts, gelatinous colonies, and gelatinous filaments, 7% crusts. In terms of spatial scales, we observed a predominance of Chlorophyta in open stream segments and Cyanobacteria in shaded stream segments, reflecting the loss of competitive advantage of green algae in sites with low energy availability. In the mesohabitats, the morphological types recorded in pools were predominantly poorly adapted to fast currents (free filaments), while those found in riffles (mats, tufts and gelatinous filaments) were highly resistant to fast water flows. As such, the use of species groupings based on algal taxonomy associated with morphological characteristics proved to be useful to understanding the distributions of these organisms in lotic environments.