Assessment of schistosomiasis, through school surveys, in the Forest Zone of Pernambuco, Brazil

This work had the objective of assessing the present epidemiological situation regarding schistosomiasis through performing Kato-Katz coproscopic tests on representative samples of schoolchildren from each of the 43 municipality of endemic area of the state of Pernambuco, Brazil. The methodology is recommended by the World Health Organization to conduct sampled surveys among children at elementary school levels, ideal target group for baseline surveys: (i) schools are accessible; (ii) the greatest prevalence of schistosomiasis is found within this group; (iii) the data gathered from this age group can be used for intervention within the community as a whole. The following infection indicators were utilized: positivity (percentage of individuals examined with eggs of Schistosoma mansoni in the feces) and severity (geometric mean number of eggs per gram of feces, epg). These indicators allowed the area in general and the municipalities in particular to be categorized into prevalence and severity classes for S. mansoni. The prevalence classes were: low (<10%), medium (> 10 and < 50%), and high (> 50%); the severity classes were: low (1-99 epg), moderate (100-399 epg), and severe (> 400 epg). For the geohelminthic diseases, the following indicators were used: positivity for each geohelminth (percentage of individuals examined with eggs of geohelminths), and cumulative positivity (percentage of individuals examined with eggs of at least one geohelminth). The municipalities were categorized by means of their cumulative positivity into the following geohelminth prevalence classes (WHO 2002): low (< 50%), medium (> 50 and < 70%), and high (> 70%). The study covered 271 schools in 179 different localities, thus giving a total of 11,234 examinations performed. The overall positivity for S. mansoni was 14.4% and the egg count for this parasite in the feces gave a geometric mean of 67.9 epg which suggests a low general state of infection. These results allow this mesoregion to be categorized as presenting medium prevalence and low severity of schistosomiasis. The overall positivity rates for the geohelminths, Ascaris lumbricoides, Ancylostomidae, and Trichuris trichiura were, respectively, 30.4, 10.1, and 27.8%; the cumulative positivity was 45.4%. These results allow this mesoregion to be categorized as presenting low prevalence of geohelminthic diseases. The data show some municipalities in Pernambuco with prevalence greater than 20%, while others presented parasite loads greater than 100 epg. These indicators attest to the significant morbidity due to schistosomiasis regarding to the severity of infections established in young populations.     

Effect of acetonitrile on Cynara cardunculus L. cardosin A stability

The kinetics of the structural changes affecting cardosin A, a plant aspartic proteinase (AP) from Cynara cardunculus L., in the presence of a mixture of acetonitrile (AN) in water (W) was studied. Incubation of cardosin A with 10% (v/v) AN resulted in a gradual increase in protein helicity, accompanied by changes in the tertiary structure, seen by changes in the intrinsic fluorescence of tryptophan. Differential scanning calorimetry (DSC) revealed that the temperature of denaturation of cardosin A decreased upon the addition of AN. With longer incubation times, the small chain of cardosin A denatured completely, consequent exposure of the single tryptophan residue accounting well for the observed spectral shift intrinsic fluorescence of the protein. Enzymatic activity assays demonstrated that the kinetically determined unfolding of the small chain of cardosin A does not result in loss of the activity of this enzyme.     

Domestic pigs have low susceptibility to H5N1 highly pathogenic avian influenza viruses

Genetic reassortment of H5N1 highly pathogenic avian influenza viruses (HPAI) with currently circulating human influenza A strains is one possibility that could lead to efficient human-to-human transmissibility. Domestic pigs which are susceptible to infection with both human and avian influenza A viruses are one of the natural hosts where such reassortment events could occur. Virological, histological and serological features of H5N1 virus infection in pigs were characterized in this study. Two- to three-week-old domestic piglets were intranasally inoculated with 10(6) EID(50) of A/Vietnam/1203/04 (VN/04), A/chicken/Indonesia/7/03 (Ck/Indo/03), A/Whooper swan/Mongolia/244/05 (WS/Mong/05), and A/Muscovy duck/Vietnam/ 209/05 (MDk/VN/05) viruses. Swine H3N2 and H1N1 viruses were studied as a positive control for swine influenza virus infection. The pathogenicity of the H5N1 HPAI viruses was also characterized in mouse and ferret animal models. Intranasal inoculation of pigs with H5N1 viruses or consumption of infected chicken meat did not result in severe disease. Mild weight loss was seen in pigs inoculated with WS/Mong/05, Ck/Indo/03 H5N1 and H1N1 swine influenza viruses. WS/Mong/05, Ck/Indo/03 and VN/04 viruses were detected in nasal swabs of inoculated pigs mainly on days 1 and 3. Titers of H5N1 viruses in nasal swabs were remarkably lower compared with those of swine influenza viruses. Replication of all four H5N1 viruses in pigs was restricted to the respiratory tract, mainly to the lungs. Titers of H5N1 viruses in the lungs were lower than those of swine viruses. WS/Mong/05 virus was isolated from trachea and tonsils, and MDk/VN/05 virus was isolated from nasal turbinate of infected pigs. Histological examination revealed mild to moderate bronchiolitis and multifocal alveolitis in the lungs of pigs infected with H5N1 viruses, while infection with swine influenza viruses resulted in severe tracheobronchitis and bronchointerstitial pneumonia. Pigs had low susceptibility to infection with H5N1 HPAI viruses. Inoculation of pigs with H5N1 viruses resulted in asymptomatic to mild symptomatic infection restricted to the respiratory tract and tonsils in contrast to mouse and ferrets animal models, where some of the viruses studied were highly pathogenic and replicated systemically.     

Integrating community assembly and biodiversity to better understand ecosystem function: the Community Assembly and the Functioning of Ecosystems (CAFE) approach

The research of a generation of ecologists was catalysed by the recognition that the number and identity of species in communities influences the functioning of ecosystems. The relationship between biodiversity and ecosystem functioning (BEF) is most often examined by controlling species richness and randomising community composition. In natural systems, biodiversity changes are often part of a bigger community assembly dynamic. Therefore, focusing on community assembly and the functioning of ecosystems (CAFE), by integrating both species richness and composition through species gains, losses and changes in abundance, will better reveal how community changes affect ecosystem function. We synthesise the BEF and CAFE perspectives using an ecological application of the Price equation, which partitions the contributions of richness and composition to function. Using empirical examples, we show how the CAFE approach reveals important contributions of composition to function. These examples show how changes in species richness and composition driven by environmental perturbations can work in concert or antagonistically to influence ecosystem function. Considering how communities change in an integrative fashion, rather than focusing on one axis of community structure at a time, will improve our ability to anticipate and predict changes in ecosystem function.     

Regeneration of Cucumis sativus var. sativus and C. sativus var. hardwickii,C. melo,and C. metuliferus from explants through somatic embryogenesis and organogenesis

Regeneration in six inbred lines or F₁ hybrids of Cucumis sativus was achieved on Murashige & Skoog's medium containing various concentrations of 2,4-D/BA, NAA/BA, NAA/Z or NAA/K. The range of regeneration frequency for cotyledon, leaf and petiole explants was 0–38, 0–75 and 14–96%, respectively, after 6–8 weeks in culture. Only one subculture of calli to growth regulator-free medium was required for regeneration. Preincubation of explants in the dark for 2–3 weeks was essential to achieve optimal regeneration. Highest frequency of plantlet formation occurred with petiole explants incubated on NAA/BA (5.0/2.5 M), NAA/Z (5.0/5.0 M) or 2,4-D/BA (5.0/5.0 M). Approximately 80% of these plantlets survived after transplanting to greenhouse soil, and they flowered and set fruit. The F₁ hybrid, Endeavor, gave the highest regeneration frequency of 91% on 2,4-D/BA at 5.0/5.0 M. Formation of somatic embryos was observed on 2,4-D/BA, while organogenesis and embryogenesis both were evident on NAA/BA and NAA/Z. Cotyledonary explants yielded the lowest frequency (ca. 7%) of plantlet formation in this study. Plantlets of C. sativus var. hardwickii and an F₁ hybrid of C. sativus x C. s. var hardwickii were regenerated on NAA/Z and NAA/K at frequencies of 15–65%, predominantly by the formation of somatic embryos. Shoots were obtained from cotyledon and leaf explants of C. metuliferus on IAA/BA (7.5/5.0 M) and from leaf and petiole explants of C. melo on NAA/BA (5.0/2.5 M), but plantlets were recovered only in C. melo.Abbreviations BA benzyladenine - 2,4-D 2,4-dichlorophenoxy-acetic acid - IAA indoleacetic acid - K kinetin - MS Murashige & Skoog's medium - NAA naphthaleneacetic acid - Z zeatindihydroside     

Purification and characterization of a new peptide antibiotic produced by a thermotolerant Bacillus licheniformis strain

A Bacillus licheniformis strain, 189, isolated from a hot spring environment in the Azores, Portugal, strongly inhibited growth of Gram-positive bacteria. It produced a peptide antibiotic at 50 degrees C. The antibiotic was purified and biochemically characterized. It was highly resistant to several proteolytic enzymes. Additionally, it retained its antimicrobial activity after incubation at pH values between 3.5 and 8; it was thermostable, retaining about 85% and 20% of its activity after 6 h at 50 degrees C and 100 degrees C, respectively. Its molecular mass determined by mass spectrometry was 3249.7 Da.     

Reciprocal intraguild predation and predator coexistence

Intraguild predation is a mix of competition and predation and occurs when one species feeds on another species that uses similar resources. Theory predicts that intraguild predation hampers coexistence of species involved, but it is common in nature. It has been suggested that increasing habitat complexity and the presence of alternative food may promote coexistence. Reciprocal intraguild predation limits possibilities for coexistence even further. Habitat complexity and the presence of alternative food are believed to promote coexistence. We investigated this using two species of predatory mites, Iphiseiodes zuluagai and Euseius concordis, by assessing co‐occurrence in the field and on arenas differing in spatial structure in the laboratory. The predators co‐occured on the same plants in the field. In the laboratory, adults of the two mites fed on juveniles of the other species, both in the presence and the absence of a shared food source, showing that the two species are involved in reciprocal intraguild predation. Adults of I. zuluagai also attacked adults of E. concordis. This suggests limited possibilities for coexistence of the two species. Indeed, E. concordis invariably went extinct extremely rapidly on arenas without spatial structure with populations consisting of all stages of the two predators and with a shared resource. Coexistence was prolonged on host plant leaves with extra food sources, but E. concordis still went extinct. On small, intact plants, coexistence of the two species was much longer, and ended with the other species, I. zuluagai, often going extinct. These results suggest that spatial structure and the presence of alternative food increase the coexistence period of intraguild predators.     

Circadian Pattern of Cercarial Emergence in Schistosoma Mansoni(Platyhelminthes: Digenea) from Isolated Biomphalaria Glabrata

The present work aimed to compare the acrophases (peak hours) of emergence of Schistosoma mansoni cercariae among isolated individuals of the snail Biomphalaria glabrata. Laboratory stocks of melanic B. glabrata from the same biotope as the S. mansoni strain (Belo Horizonte, Minas Ger-ais) were used. Twenty-two snails individually exposed to five miracidia were tested. Chronobiological trials were performed outdoors after an acclimation period of at least a week. Three groups of snails were tested between November 1989 and April 1991. Cercarial emergence from individual isolated snails was quantified every 3 h for 3 consecutive days. In all trials, most cercariae were found to emerge during daytime (94.9%). Time series and chronograms showed recurrent peaks during the daytime. The periodogram suggested that 24 h was the period that best fitted cercarial emergence data in 90.9% of the snails. The single cosinor analysis confirmed 24-h rhythms in 95.5% of the snails. Acrophases of cercarial emergence among individual snails occurred between 14:15 and 17:02. They did not differ significantly. The population cosinor analysis indicated greater homogeneity in the 24-h rhythms of cercarial emergence than in the snail groups of each chronobiological trial. Acrophases of cercarial emergence occurred between 14:53 and 15:27 and did not differ significantly among all trials. Data from the three trials were pooled and analyzed using the population cosinor. This statistical method indicated a homogeneity in the 24-h rhythms of cercarial emergence from all snails, with acrophase occurring around 15:00. Results showed that the acrophases of cercarial emergence of S. mansoni are similar among isolated B. glubrura specimens. Data support the hypothesis of a “gate” rhythm in the dynamics of cercarial production and emergence. It is suggested that the adaptive importance of the “gate” mechanism is associated with the concentration of cercariae in the water at times when the vertebrate is present, optimizing the contact between the parasite and the host. The emergence of some cercariae at night (5.1% of the total number of emerged cercariae) suggests a flexible “gate” that could be associated with a residual light effect or with experimental procedures in the laboratory.     

Use of odours by Cycloneda sanguinea to assess patch quality

Adult ladybirds are likely to encounter various species of prey when foraging for oviposition sites. Optimal oviposition theory predicts that females should lay eggs in those sites that are the most suitable for offspring development. Therefore, factors that directly affect offspring mortality, such as the presence of predators and food, are expected to play an important role in the assessment of patch profitability by ladybird predators. Using a Y‐tube olfactometer, we tested whether the predatory ladybird Cycloneda sanguinea L. (Coleoptera: Coccinellidae) can use volatile cues to assess patch profitability and avoid predator‐rich patches. We assessed the foraging behaviour of C. sanguinea in response to odours associated with tomato plants infested with a superior prey, Macrosiphum euphorbiae Thomas (Homoptera: Aphididae), and with an inferior prey, Tetranychus evansi Baker and Pritchard (Acari: Tetranychidae), in the presence or absence of the heterospecific predator Eriopis connexa Mulsant (Coleoptera: Coccinellidae). Females of C. sanguinea significantly preferred plants infested by M. euphorbiae to plants infested by T. evansi and avoided odours emanating from plants on which E. connexa females were present. Our results show that C. sanguinea use volatile cues to assess patch profitability and to avoid patches with heterospecific competitors or intraguild predators.