Resumo Em regiões tropicais, savanas e florestas estacionais, biomas altamente diversos, ocorrem lado a lado, sob o mesmo clima. Sendo assim, esse mosaico não pode ser explicado somente por variáveis climáticas, devendo ser considerada a frequência e intensidade de incêndios, disponibilidade de água e status do solo. A disponibilidade de nutrientes no solo, especialmente nitrogênio e fósforo, tem sido postulada para explicar as transições abruptas entre savanas e florestas estacionais nos trópicos. Espécies vegetais desses dois biomas podem apresentar estratégias nutricionais diferentes para lidar com a limitação tanto de nitrogênio como de fósforo. Utilizamos dois pares de árvores congenéricas — cada par com uma espécie típica de savana e outra de floresta estacional vizinha — para testar se as espécies da savana e da floresta apresentaram estratégias nutricionais diferentes durante seu desenvolvimento inicial. Cultivamos 56 indivíduos de cada uma dessas espécies em um sistema hidropônico com quatro tratamentos: (1) solução Hoagland completa, (2) solução Hoagland sem nitrogênio, (3) solução Hoagland sem fósforo e (4) solução Hoagland sem nitrogênio e fósforo. Após 45 dias, colhemos as plantas e medimos a biomassa total, a relação raiz / parte aérea, altura, área foliar e área foliar específica. No geral, as espécies savânicas foram mais leves, menores em altura, área foliar e área foliar específica e apresentaram maiores razões entre biomassa radicular por biomassa aérea quando comparadas às espécies florestais. A oferta de nitrogênio aumentou o desempenho das espécies de ambos biomas. O fósforo melhorou o desempenho das espécies florestais e causou sintomas de toxicidade nas espécies savânicas. Concluímos que, já como mudas, espécies congenéricas de savana e floresta apresentaram demandas distintas e foram parcialmente diferentes em relação a suas estratégias nutricionais.

Abstract In the tropical region, savannas and seasonal forests, both highly diverse biomes, occur side by side, under the same climate. If so, that mosaic cannot be explained solely by climatic variables, but also by fire, water availability and soil status. Nutrient availability in the soil, especially nitrogen and phosphorus, has been postulated to explain the abrupt transitions between savannas and seasonal forests in tropical regions. Plants from these two biomes may present different nutritional strategies to cope with nitrogen and phosphorus limitation. We used two congeneric pairs of trees — each pair with a species from the savanna and another from the neighboring seasonal forest — to test whether savanna and forest species presented different nutritional strategies during their early development. We cultivated 56 individuals from each of these species in a hydroponics system with four treatments: (1) complete Hoagland solution, (2) Hoagland solution without nitrogen, (3) Hoagland solution without phosphorus, and (4) Hoagland solution without nitrogen and phosphorus. After 45 days, we harvested the plants and measured total biomass, root to shoot ratio, height, leaf area, and specific leaf area. Overall, savanna species were lighter, shorter, with smaller leaves, higher specific leaf areas, and higher root to shoot ratios when compared to the forest species. Nitrogen increased the performance of species from both biomes. Phosphorus improved the performance of the forest species and caused toxicity symptoms in the savanna species. Hence, savanna and forest species presented different demands and were partially distinct already as seedlings concerning their nutritional strategies.

Abstract In this work, a new method employs Bioinspired Computational (BIC) optimization from the genetic algorithm, bat algorithm, and flower pollination algorithm. Robust and accurate modeling of the input parameters adjusts the propagation models Stanford University Interim, Electronic Communication Committee, and Floating Interception that consider environments with characteristics specifically of urban regions in the Amazon. The lack of research related to the development of propagation models for Amazonian environments motivated this work. Thus, this application proves the effectiveness of using BIC techniques for modeling the communication channel. Measurement campaigns were carried out in the city of Belem, Brazil, for large-scale channel modeling on the frequencies of 1.8 and 2.6 GHz, belonging to the long-term evolution or fourth-generation mobile communications system (4G). After being adjusted by the optimum values calculated by the BIC techniques used, the models showed better results compared to modeling without optimization. Additionally, it was verified an error reduction of about 80% concerning the metrics root-mean-square error and standard deviation.

For a study of diversity and genetic structuring in Melipona quadrifasciata, 61 colonies were collected in eight locations in the state of Minas Gerais, Brazil. By means of PCR analysis, 119 ISSR bands were obtained, 80 (68%) being polymorphic. He and H B were 0.20 and 0.16, respectively. Two large groups were obtained by the UPGMA method, one formed by individuals from Januária, Urucuia, Rio Vermelho and Caeté and the other by individuals from São João Del Rei, Barbacena, Ressaquinha and Cristiano Otoni. The Φst and θB values were 0.65 and 0.58, respectively, thereby indicating high population structuring. UPGMA grouping did not reveal genetic structuring of M. quadrifasciata in function of the tergite stripe pattern. The significant correlation between dissimilarity values and geographic distances (r = 0.3998; p < 0.05) implies possible geographic isolation. The genetic differentiation in population grouping was probably the result of an interruption in gene flow, brought about by geographic barriers between mutually close geographical locations. Our results also demonstrate the potential of ISSR markers in the study of Melipona quadrifasciata population structuring, possibly applicable to the studies of other bee species.

Melipona quadrifasciata Lepeletier, 1836, regionally known as "mandaçaia", has been traditionally divided in two distinct subspecies: M. quadrifasciata anthidioides and M. quadrifasciata quadrifasciata. The main difference between the subspecies refers to the yellow metasomal stripes which are continuous in M. q. quadrifasciata and discontinuous in M. q. anthidioides. This study investigated the geographic differentiation in the metasomal stripes and characterized the restriction sites in the mtDNA of both chromatic types. Specimens from 198 localities were examined, and the variation observed in the pattern of stripes was grouped into distinct classes. The distribution pattern found in the present work agrees with the previously reported pattern: M. q. quadrifasciata inhabits the southern portion of the distribution, from Misiones, Argentina, southeastern Paraguay and Rio Grande do Sul to southern São Paulo, and M. q. anthidioides ranges from northeastern São Paulo to the northern Diamantina Plateau, Bahia, and westwards to the central portion of the Goiás state. It is documented for the first time the occurrence of two populations with continuous stripes inhabiting disjunct areas in relation to M. q. quadrifasciata - one in northern Minas Gerais and another in northeastern Bahia and Sergipe. The data of RFLP showed two restriction patterns, one present in M. q. quadrifasciata, and another in M. q. anthidioides and in populations with continuous metasomal stripes from northern Minas Gerais and northeastern Bahia and Sergipe. The observed patterns of geographic differentiation of M. quadrifasciata suggests the occurrence of repeated events of geographical isolation, followed by range expansion, that occurred probably during the cycles of climatic changes in the Pleistocene.

Propolis is a natural resinous substance collected by bees from vegetal sources and its therapeutic properties have been investigated. In this work, we evaluated the inhibitory activity of ethanolic extracts of propolis (EEP) from the Southeast and South of Brazil on coagulase-negative Staphylococcus (CNS) growth as well as the EEP in vitro synergism with antimicrobial drugs by using the diffusion method (E-test). The EEP chemical characteristics (dry weight, pH, flavonoid and phenolic compounds) were determined. Seven drugs were tested, and synergism was observed between three drugs and Southeast EEP, six drugs and South EEP, and one drug and ethanol control. Ethanolic extracts of propolis from the South of Brazil presented the greatest flavonoid content and synergism rate, while EEP from the Southeast presented the greatest anti-CNS activity and phenolic compound content. Results showed the correlation among anti-CNS activity, synergism rate and chemical characteristics of propolis.

As espécies vegetais apresentam flores com características morfológicas e funcionais diversificadas, que podem ser associadas a sistemas de polinização, incluindo espécies polinizadas pelo vento, besouros, mariposas, abelhas, insetos pequenos, aves ou morcegos. Calculamos as freqüências dos sistemas de polinização entre as espécies lenhosas em cinco fragmentos de cerrado no Brasil central e testamos se os sistemas de polinização estavam de fato relacionados às características florais. Amostramos 2.280 indivíduos, pertencentes a 121 espécies, das quais 99 foram descritas em relação a todas as características florais. A maioria dessas espécies possuía antese diurna, cores claras e flores abertas. Os grupos mais freqüentes foram os das plantas polinizadas por abelhas, insetos pequenos e mariposas. Uma análise de ordenação das espécies e dos caracteres florais mostrou que houve agrupamentos entre as espécies com alguns sistemas de polinização, tais como as polinizadas principalmente por besouros, mariposas, aves e morcegos, para os quais inferências baseadas em características florais são recomendadas. No caso das espécies polinizadas por abelhas e insetos pequenos, inferências a partir dos caracteres florais não são recomendadas devido à grande dispersão dos escores das espécies e à sobreposição entre esses dois grupos, que ocorreram, provavelmente, devido à ausência de especificidade nas relações planta-polinizador.

Plant species present flowers with varied morphological and functional features, which may be associated to pollination systems, including species pollinated by wind, beetles, moths, bees, small insects, birds, or bats. We calculated the frequencies of the pollination systems among woody species in five cerrado fragments in central-western Brazil and tested whether the pollination systems were indeed related to floral traits. We sampled 2,280 individuals, belonging to 121 species, ninety-nine of which were described in relation to all floral traits. Most species had diurnal anthesis, pale colors, and open flowers. The most frequent groups were those composed by the species pollinated by bees, small insects, and moths. A Principal Component Analysis of the species and floral traits showed that there was a grouping among species with some pollination systems, such as those pollinated mainly by beetles, moths, birds, and bats, for which inferences based on the floral traits are recommended in cerrado sites. For the species pollinated mainly by bees or small insects, inferences based on the floral traits are not recommended, due to the large dispersion of the species scores and overlapping between these two groups, which probably occurred due to the specificity absence in plant-pollinator relationships.

As savanas podem ser divididas de acordo com a sua estacionalidade em savanas semi-estacionais, savanas estacionais, savanas hiperestacionais ou esteros. Savanas hiperestacionais são caracterizadas pela alternância de dois estresses contrastantes durante cada ciclo anual, um induzido pela seca e fogo e outro, pelo alagamento. A maior região de savana na América do Sul é o cerrado brasileiro, que apresenta poucas áreas hiperestacionais, que se tornam alagadas durante a estação chuvosa. Os solos de cerrado são geralmente bem drenados, mas há, no Brasil central, uma pequena área de cerrado em que o solo é pobremente drenado e que se torna alagada no meio da estação úmida, possibilitando o aparecimento de um cerrado hiperestacional. Como o solo é importante para a ecologia da vegetação do cerrado, nós nos perguntamos se o alagamento no cerrado hiperestacional implicava diferenças nas características edáficas em relação ao cerrado estacional, que não alaga durante a estação chuvosa, e ao campo úmido, que permanece alagado durante o ano todo. Em cada ambiente, nós sorteamos dez pontos, em que coletamos amostras de solo, no meio da estação chuvosa, para análises químicas e granulométricas. Para todas as variáveis, encontramos diferenças significativas entre os três ambientes, ao menos em uma profundidade. Não obstante, quando analisamos todas as variáveis edáficas conjuntamente, observamos que os solos sob os cerrados hiperestacional e estacional foram semelhantes e ambos foram diferentes do solo sob o campo úmido. O solo sob campo úmido relacionou-se a maiores quantidades de argila, silte, matéria orgânica, fósforo, alumínio, saturação por alumínio, capacidade de troca catiônica e soma de bases, enquanto que os solos sob cerrados hiperestacional e estacional relacionaram-se a maiores valores de pH, areia, saturação por bases, cálcio e magnésio. Uma vez que os solos sob os dois tipos de cerrado foram similares química e fisicamente, a duração do alagamento no cerrado hiperestacional não é suficiente para alterar as suas características edáficas. Limitações para as plantas crescendo no cerrado hiperestacional devem ser conseqüência dos efeitos diretos do alagamento. Como as espécies vegetais de cerrado são espécies de áreas secas, a hipoxia causada pelo alagamento pode limitar o número de espécies de cerrado que são capazes de suportar essa condição.

Savannas may be divided according to their seasonality into semi-seasonal, seasonal, hyperseasonal, or marshy savannas. Hyperseasonal savannas are characterized by the alternation of two contrasting stresses during each annual cycle, one induced by drought and fire and the other, by waterlogging. In South America, the largest savanna region is the Brazilian cerrado, in which there are few hyperseasonal areas that become waterlogged in the rainy season. The cerrado soils are generally well drained, but in central Brazil there is a small cerrado area in which the soil is poorly drained and which becomes waterlogged in the middle of the rainy season, allowing the appearance of a hyperseasonal cerrado. As long as soil is important in the ecology of the cerrado vegetation, we asked whether the waterlogging in this hyperseasonal cerrado implied that there were differences in soil characteristics in relation to a seasonal cerrado, which is not waterlogged in the rainy season, and to a floodplain grassland, which remains waterlogged throughout the year. In each environment, we randomly selected ten points, in which we collected soil samples in the mid-rainy season for chemical and granulometric analyses. For all variables, we found significant differences among the three environments, at least at one of the depths. Nevertheless, when we took into account all the variables together, we observed that the soils under the hyperseasonal and seasonal cerrados were similar and both were different to the soil under the floodplain grassland. The soil under the floodplain grassland was related to larger amounts of clay, silt, organic matter, phosphorus, aluminium, aluminium saturation, cation exchange capacity, and sum of bases, whereas soils under hyperseasonal and seasonal cerrados were related to higher pH values, base saturation, calcium, magnesium, and sand. As long as the soil under both cerrados was chemically and physically similar, the duration of waterlogging in the hyperseasonal cerrado is not long enough to alter its soil characteristics. Limitations to the plants growing on the hyperseasonal cerrado soil must be a consequence of the direct effects of flooding. Since cerrado plant species are dryland ones, the hypoxia caused by waterlogging may limit the number of cerrado species able to withstand these conditions.

The presence of Staphylococcus aureus in the nasal cavities and pericatheter skin of peritoneal dialysis patients put them at high risk of developing peritonitis. However, it is not clear whether the presence of coagulase-negative staphylococci (CNS) in the nasal passages and skin of patients is related to subsequent occurrence of peritoneal infection. The aim of the present study was to verify the relationship between endogenous sources of S. aureus and CNS and occurrence of peritonitis in patients undergoing peritoneal dialysis. Thirty-two patients on peritoneal hemodialysis were observed for 18 months. Staphylococcus species present in their nasal passage, pericatheter skin and peritoneal effluent were identified and compared based on drug susceptibility tests and dendrograms, which were drawn to better visualize the similarity among strains from extraperitoneal sites as well as their involvement in the causes of infection. Out of 288 Staphylococcus strains isolated, 155 (53.8%) were detected in the nasal cavity, 122 (42.4%) on the skin, and 11 (3.8%) in the peritoneal effluent of patients who developed peritonitis during the study. The most frequent Staphylococcus species were CNS (78.1%), compared with S. aureus (21.9%). Among CNS, S. epidermidis was predominant (64.4%), followed by S. warneri (15.1%), S. haemolyticus (10.7%), and other species (9.8%). Seven (64%) out of 11 cases of peritonitis analyzed presented similar strains. The same strain was isolated from different sites in two (66%) out of three S. aureus infection cases. In the six cases of S. epidermidis peritonitis, the species that caused infection was also found in the normal flora. From these, two cases (33%) presented highly similar strains and in three cases (50%), it was difficult to group strains as to similarity. Patients colonized with multidrug-resistant S. epidermidis strains were more predisposed to infection. Results demonstrated that an endogenous source of S. epidermidis could cause peritonitis in peritoneal dialysis patients, similarly to what has been observed with S. aureus.

Usamos o sistema de Raunkiaer para classificar, em formas de vida, as plantas vasculares presentes em 12 parcelas aleatórias de 25 m² de cerrado. A área de estudo é coberta por cerrado sensu stricto e se localiza no fragmento do Valério, aproximadamente a 22º13'S e 47º51'W, a 760 m de altitude, na Estação Ecológica e Experimental de Itirapina, Estado de São Paulo. O espectro florístico considera a forma de vida de cada espécie; no espectro de freqüência, cada espécie é ponderada por sua freqüência e o espectro vegetacional não considera as espécies, mas sim os indivíduos em cada classe. No espectro florístico, as forma de vida mais bem representadas foram as dos fanerófitos e dos hemicriptófitos, como em outros cerrados. Esse espectro diferiu significativamente do espectro normal de Raunkiaer devido, principalmente, à sub-representação dos terófitos e à super-representação dos fanerófitos. Os espectros florísticos e de freqüência foram similares, mas ambos diferiram do espectro vegetacional. Recomendamos o espectro florístico para os trabalhos em escalas maiores e para descrição do fitoclima e o espectro vegetacional para os trabalhos em escalas menores e para descrição quantitativa da fisionomia. O espectro de freqüência não é recomendado em nenhuma situação.

We used Raunkiaer's system to classify in life-forms the vascular plants present in 12 random 25 m² quadrats of a cerrado site. The study area is covered by cerrado sensu stricto and is located in the Valério fragment, at about 22º13'S and 47º51'W, 760 m above sea level, in the Itirapina Ecological and Experimental Station, São Paulo State, southeastern Brazil. The floristic spectrum considers the life-form of each species, while in the frequency spectrum, each species is weighted by its frequency. The vegetation spectrum does not consider the species at all, but only the individuals in each life-form class. In the floristic spectrum, the most represented life-forms were the phanerophytes and the hemicryptophytes, as in other cerrado sites. This spectrum differed significantly from Raunkiaer's normal spectrum, mainly due to under-representation of therophytes and over-representation of phanerophytes. The floristic and frequency spectra were similar, but both differed from the vegetation spectrum. We recommend the floristic spectrum when working at larger scales and a description of the phytoclimate is wanted. The vegetation spectrum is preferable when working at smaller scales and wanting a quantitative description of the physiognomy. The frequency spectrum is not recommended at all.

Estudamos três fisionomias do cerrado (campo cerrado, cerrado sensu stricto e cerradão) em uma reserva com 1.225 ha, situada no munícipio de Santa Rita do Passa-Quatro (21°36-38'S e 47°36-39'W), Estado de São Paulo, com o objetivo de comparar a estrutura da vegetação, tanto do componente arbustivo-arbóreo quanto do herbáceo-subarbustivo. Como descritores da estrutura da comunidade, utilizamos a riqueza, a densidade, a área basal, o volume cilíndrico e a diversidade. Em cada uma das três fisionomias, lançamos aleatoriamente 10 parcelas de 40 m², em que amostramos as plantas lenhosas com diâmetro do caule no nível do solo maior ou igual a 1 cm (componente arbustivo-arbóreo), com subparcelas de 2,5 m², em que amostramos as plantas lenhosas com diâmetro do caule no nível do solo menor do que 1 cm e todas as não-lenhosas (componente herbáceo-subarbustivo). No componente arbustivo-arbóreo, encontramos diferenças significativas entre as fisionomias para a riqueza, a densidade e o volume cilíndrico. O volume cilíndrico aumentou do campo cerrado ao cerradão, enquanto a riqueza e a densidade foram maiores no cerrado sensu stricto. Para o componente herbáceo-subarbustivo, detectamos diferenças em todas as variáveis, que foram maiores nas fisionomias savânicas, campo cerrado e cerrado sensu stricto, do que nas fisionomias florestal e cerradão. O volume cilíndrico foi a melhor variável para distinguir diferenças entre as fisionomias. A similaridade florística seguiu o gradiente campo cerrado-cerrado sensu stricto-cerradão, e a diversidade beta foi maior para o componente herbáceo-subarbustivo.

We studied three cerrado physiognomies (campo cerrado, a savanna woodland; cerrado sensu stricto, a woodland; and cerradão, a tall woodland) in a reserve with 1,225 ha, in Santa Rita do Passa-Quatro (21°36-38'S and 47°36-39'W), São Paulo State, South-eastern Brazil, to compare plant communities structure. As descriptors of the vegetation structure, we used richness, density, basal area, cylindrical volume, and diversity. Ten 40 m² quadrats were placed randomly in each physiognomy, in which we sampled the woody plants with stem diameter equal or larger than 1 cm (woody component), and ten 2.5 m² quadrats, in which we sampled the woody plants with stem diameter smaller than 1 cm and all the non-woody individuals (herbaceous component). In the woody component, we found significant differences among the physiognomies for richness, density and cylindrical volume. Cylindrical volume increased from campo cerrado to cerradão, but richness and density were higher in cerrado sensu stricto. In the herbaceous component, we detected differences for all variables, which were higher in the savanna physiognomies, campo cerrado and cerrado sensu stricto, than in the forest physiognomy, cerradão. Cylindrical volume was the best variable to distinguish the physiognomies. Floristic similarity followed the campo cerrado-cerrado sensu stricto-cerradão gradient, and beta diversity was higher in the herbaceous component.

Foi estudada uma área de vegetação natural, de 1269 ha, composta principalmente por cerrado, situada no munícipio de Santa Rita do Passa Quatro, estado de São Paulo (21°36-39'S, 47°36-38'W). Entre setembro de 1995 e fevereiro de 1997, realizou-se um levantamento florístico, em que foram amostradas as espécies vasculares de plantas em fase fértil. A partir dos dados desse levantamento, estudaram-se os padrões de floração e frutificação da comunidade, comparando as espécies herbáceo-subarbustivas com as arbustivo-arbóreas. No componente herbáceo-subarbustivo, foram encontradas 239 espécies e, no componente arbustivo-arbóreo, 108 espécies. As espécies arbustivo-arbóreas floresceram principalmente no início da estação chuvosa, enquanto as herbáceo-subarbustivas produziram flores, de modo geral, apenas no final da estação úmida. A proporção de espécies anemo e autocóricas foi maior no componente herbáceo-subarbustivo, ao contrário das zoocóricas, mais freqüentes no componente arbustivo-arbóreo. Na estação seca, quando sua dispersão é mais eficiente, a proporção de espécies anemo e autocóricas em frutificação foi maior. Já durante a estação chuvosa, as espécies zoocóricas frutificaram com maior intensidade, uma vez que seus frutos carnosos podem se manter atraentes por mais tempo.

A natural vegetation area, with 1269 ha, composed mainly by cerrado, located at Santa Rita do Passa Quatro Municipality, São Paulo State, southeastern Brazil (21°36-39'S, 47°36-38'W), was studied. From September 1995 to February 1997, a floristic survey was carried out, when all vascular plant species at reproductive stage were collected. The flowering and fruiting patterns of the community were studied, comparing the herbaceous and the woody species. In the herbaceous component, 239 species were found and, in the woody one, 108 species. The woody species flowered mainly at the beginning of the rainy season, while the herbaceous ones produced flowers generally at the end of that season. The proportion of anemo and autochorous species was greater in the herbaceous component. The zoochorous ones, on the contrary, were more frequent in the woody component. At the dry season, when their dispersion is more efficient, the proportion of anemo and autochorous species producing fruits was higher. During the rainy season, when their fruits become attractive for longer time, the zoochorous species fruited more intensely.