首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 31 毫秒
1.
Benthic annelid communities were studied during a one-year period (August/95 to July/96) in two sectors of the beaches Engenho d'Agua and S?o Francisco, S?o Sebasti?o Channel (S?o Paulo, Brazil), where the substrate is composed by a mixture of sand and rock fragments. Abiotic parameters such as salinity of interstitial water and sediment properties were used to characterize the environment. The polychaetes were well represented in the two sectors and their distribution was related with sediment type. The density of individuals and the number of taxa was higher at S?o Francisco, while the diversity and the evenness were higher at Engenho d'Agua. This difference can be a consequence of organic enrichment caused by domestic input, and of the lower and more variable salinity at S?o Francisco. Due to these factors, the high density of opportunistic species, like Capitella capitata ssp., Scolelepis squamata, Laeonereis acuta and several oligochaetes, represented 75.5% of total abundance at this sector.  相似文献   

2.
At present the majority of the endemic bird species occurring on São Tomé and Príncipe remain common, the rarer species being those largely confined to primary rainforest. In 1990 the dwarf olive ibis (Bostrychia bocagei), São Tomé fiscal shrike (Lanius newtoni), São Tomé short-tail (Amaurocichla bocagii) were rediscovered and in 1991 the São Tomé grosbeak (Neospiza concolor) was seen for the first time since 1888. Lowland primary forest is the only habitat on São Tomé in which all the endemic species are found. Primary forest on Príncipe remains largely unsurveyed since the beginning of the century. Due to the decline in the cocoa industry and poor infra-structure post-independence the extent of secondary forest is probably at its greatest since the late 1800s. This habitat is an important buffer zone against development for the remaining primary forest and also contains important populations of many of the endemic species, in particular the São Tomé scops owl (Otus hartlaubi), São Tomé oriole (Oriolus crassirostris) and giant weaver (Ploceus grandis). On both islands the remaining areas of primary forest need immediate protection and suitable boundaries have been designated under the Zona Ecológica plan. Fortunately, except for an important area around Lagôa Amélia, primary forest is not under immediate threat, although a variety of pressures are likely to increase. In conjunction with the protection of primary forest, a plant for managing the remaining timber resource on the islands will be a vital requirement, particularly if areas of shade forest, an important habitat for endemic bird species and a potentially valuable economic resource, are to be conserved and sustainably managed.  相似文献   

3.
Yeasts of the Cryptococcus genus are distributed in nature associated to animal and vegetal organic residues. Occasionally, species other than C. neoformans may be responsible for infectious diseases in human and animals. This study aims to determine the occurrence of Cryptococcus species in the atmosphere and bird droppings in the city of Ribeir?o Preto, S?o Paulo, Brazil, and to evaluate three virulence factors: capsule formation, growth at 37 degrees C and melanin production. We analyzed 86 environmental samples (54 droppings and 32 air). Of the 41 strains isolated, 15 were C. neoformans var. neoformans (12 droppings and 3 air), 15 C. albidus (12 droppings and 3 air), 9 C. laurentii (7 droppings and 2 air) and 2 C. uniguttulatus (from droppings). Capsules were produced by 93.3% of C. neoformans var. neoformans, 66.7% of C. albidus, 88.9% of C. laurentii and 50% (1/2) of C. uniguttulatus. All strains of C. neoformans, 20% of C. albidus and 44.4% of C. laurentii were able to grow at 37 degrees C. The melanin production on DOPA agar was verified in C. neoformans (93.3%), C. albidus (26.7%) and C. laurentii (66.7%). We concluded that different Cryptococcus species coexist in the same ecological niche and they are able to produce virulence factors.  相似文献   

4.
Neto  Ana Isabel 《Hydrobiologia》2000,432(1-3):135-147
The intertidal benthic algal communities of two sites located on opposite coasts of São Miguel Island (Azores), were studied over a 2-year period (September 1993–September 1995). At both sites (São Roque on the south coast and São Vicente on the north), the littoral region was surveyed from the upper intertidal down to the sublittoral fringe. The survey revealed five distinct zones, with a variable degree of overlapping. The two upper zones were characterized by animals (littorinids and barnacles, respectively). Lower down, algal communities formed three distinct zones: an upper Fucus spiralis/Gelidium microdon association, a more extensive turf zone, and a belt featuring erect or frondose algae. Upper in the eulittoral, the turf was mainly monospecific, and dominated by Caulacanthus ustulatus. The lower eulittoral turf was dominated by articulated coralline algae, the associated species differing between the two sites studied. Mainly erect algae (Pterocladiella, Asparagopsis, etc.) occurred furthest down the shore and extended into the nearby shallow sublittoral. Two intertidal communities were studied at each locality: the upper eulittoral (Caulacanthus turf in São Roque and the Fucus spiralis/Gelidium microdon association at São Vicente), and the lower eulittoral (the coralline turf). The lower littoral communities had a higher algal diversity. A general pattern was observed in the seasonal variation of biomass: the lower levels exhibited the higher values in late summer/early autumn, the period in which the upper levels had the lowest standing crops. Physical factors are proposed to account for this. No significant inter-annual variations could be detected, indicating relatively stable communities, at least on a short-term basis.  相似文献   

5.
Faunal inventories are extremely important, especially when focused on neglected groups, such as echinoderms, and concentrated on areas under intense anthropic activity such as the SAo Sebastilo Channel in Brazil (23 degrees 41' - 23 degrees 54' S and 45 degrees 19' - 45 degrees 30' W). Intertidal and upper sublittoral zone collections were performed at five sites of the Channel's continental margin from May to August 2001. The rocky substrate down to 19 m deep was surveyed by snorkeling and SCUBA diving from August 2002 to May 2004, on both margins of the Channel: continental (14 sites) and insular (10 sites). We report a total of 38 species of echinoderms (one Crinoidea, nine Asteroidea, 13 Ophiuroidea, nine Echinoidea and six Holothuroidea). Seven of those species have been recorded here for the first time for the Channel (four Asteroidea, two Ophiuroidea and one Echinoidea).  相似文献   

6.
S. Sendacz 《Hydrobiologia》1984,113(1):121-127
The composition of the zooplankton of the Billings Reservoir and its variation in an eutrophic environment, subject to frequent blooms of algae (chiefly Cyanophyceae) was studied during one year (from October, 1977 to September, 1978) in two stations in the littoral and in the limnetic zone.The zooplankton community in the limnetic zone was dominated by cyclopoid copepods (Thermocyclops crassus and Metacyclops mendocinus) and by rotifers (Brachionus, Polyarthra and others) which represented, respectively 38.5 and 35.5% of the total zooplankton. At the littoral zone, cyclopoids were the most abundant (42.3%).The cladocerans were the least significant group at both stations, and calanoid copepods were found only at the littoral zone.A higher production of small filtrators, such as rotifers, cyclopoid nauplii and Bosmina sp was observed.  相似文献   

7.
8.
9.
Micropaleontological studies of Tertiary shales and carbonates of the continental shelf of northeast Brazil have shown the existence of several levels rich in scolecodnts, even in areas in which other taxa are absent. A systematic analysis of the vertical distribution of these worm remains in relation to the Eocene/Oligocene stratigraphical subdivision based on pollen and spores, dinoflagellates, nannoplankton and foraminifera leads to the possibility of establishing a scolecodont zonation that can be traced into areas in which other microfossils are rarely preserved. This possibility, which may be a new stratigraphical tool in the exploration for petroleum in Brazil, is applied to the off-shore Maranhão basin.  相似文献   

10.
This study investigated rickettsial infection in animals, humans, ticks, and fleas collected in five areas of the state of S?o Paulo. Eight flea species (Adoratopsylla antiquorum antiquorum, Ctenocephalides felis felis, Polygenis atopus, Polygenis rimatus, Polygenis roberti roberti, Polygenis tripus, Rhopalopsyllus lugubris, and Rhopalopsyllus lutzi lutzi), and five tick species (Amblyomma aureolatum, Amblyomma cajennense, Amblyomma dubitatum, Ixodes loricatus, and Rhipicephalus sanguineus) were collected from dogs, cats, and opossums. Rickettsia felis was the only rickettsia found infecting fleas, whereas Rickettsia bellii was the only agent infecting ticks, but no animal or human blood was shown to contain rickettsial DNA. Testing animal and human sera by indirect immunofluorescence assay against four rickettsia antigens (R. rickettsii, R. parkeri, R. felis, and R. bellii), some opossum, dog, horse, and human sera reacted to R. rickettsii with titers at least four-fold higher than to the other three rickettsial antigens. These sera were considered to have a predominant antibody response to R. rickettsii. Using the same criteria, opossum, dog, and horse sera showed predominant antibody response to R. parkeri or a very closely related genotype. Our serological results suggest that both R. rickettsii and R. parkeri infected animals and/or humans in the studied areas.  相似文献   

11.
Visceral larva migrans syndrome by Toxocara affects mainly children between 2 and 5 years of age, it is generally asymptomatic, and the seroprevalence varies from 3 to 86% in different countries. A total of 399 schoolchildren from 14 public schools of the Butant? region, S?o Paulo city, Brazil, were evaluated by Toxocara serology (enzyme-linked immunosorbent assay). Epidemiological data to the Toxocara infection obtained from a protocol were submitted to multiple logistic regression analysis for a risk profile definition. Blood was collected on filter paper by finger puncture, with all samples tested in duplicate. Considering titers > or = 1/160 as positive, the seroprevalence obtained was 38.8%. Among infected children, the mean age was 9.4 years, with a similar distribution between genders. A significant association was observed with the presence of onychophagia, residence with a dirty backyard, living in a slum, previous wheezing episodes, school attended, and family income (p < 0.05). All data, except "living in a slum", were considered to be determinant of a risk profile for the acquisition of Toxocara infection. A monthly income > or = 5 minimum salaries represented a protective factor, although of low relevance. Toxocara eggs were found in at least one of the soil samples obtained from five schools, with high prevalence of Toxocara infections, indicating the frequent soil contamination by this agent.  相似文献   

12.
Tradescantia pallida cv. purpurea, a popular garden plant in Brazil, was used for the Tradescantia micronucleus (Trad-MCN) assay. In situ monitoring of the genotoxicity of air pollutants was carried out by sentinel approach, using the plant grown in the field or using the plants in pots which were carried to the monitoring sites. Two highly polluted sites, in S?o Paulo city (Cerqueira Cesar and Congonhas) and two rural sites (the cities of Pirassununga, 200 km and Caucaia do Alto, 50 km from S?o Paulo, respectively) were chosen for this study, in order to determine the gradient difference of the air pollution levels. Sentinel plants in Congonhas site presented the highest frequency of micronuclei (4.4%), in comparison with 2.2 and 2.3% found in plants from Pirassununga and Cerqueira Cesar sites, respectively (Kruskal-Wallis; P<0.020). Significant increases (F test; P<0.0001) in the frequency of micronuclei were observed in plants exposed in the polluted urban sites (Cerqueira Cesar: 5.7%; Congonhas: 7.1% and Caucaia do Alto: 2.3%). The increase in the frequency of micronuclei observed indicates the potential risk of mutagenicity in presence of high concentrations of pollutants.  相似文献   

13.
This study investigates the ecology of monogenean gill parasites of Aslyanax altiparanae Garutti & Britski, 2000 and Rhamdia quelen (Quoy & Gaimard, 1824) in a stretch of the Sao Francisco Verdadeiro River, Parana, Brazil. Statistical and ecological indices were used to examine observed levels of parasitism in relation to host and environmental characteristics. A. altiparance and R. quelen had infestation intensities of 2.8 and 23.1 parasites per fish, respectively. The only significant environmental influence was observed at the upstream station for R. quelen. For both host species, parasitized and non-parasitized individuals presented similar weight-ength relationships. Parasitized individuals had dispersed K,, values indicating abnormal conditions. The low levels of parasitism observed in this study suggest that the environment is relatively undisturbed. Additional studies should compare these two species and their respective parasites following completion of the hydroelectric headquarters planned for construction in this stretch of the Sao Francisco Verdoadeiro River.  相似文献   

14.
Infections by Cryptococcus strains other than C. neoformans have been detected in immunocompromised patients. Of these strains, three are considered human pathogens: C. albidus, C. laurenttii, and C. uniguttulatus. This study deals with the in vitro susceptibility of Cryptococcus to drugs such as amphotericin B, itraconazole, fluconazole, and 5-fluorocytosine. Environmental Cryptococcus isolates (50) distributed as follows: C. neoformans var. neoformans (16), C. albidus (17), C. laurentii (14), and C. uniguttulatus (3) were evaluated by the micro and macrodilution techniques, according to EUCAST and NCCLS recommendations, respectively. Considering both methodologies the respective minimal inhibitory concentrations (MIC) were 0.125 and 2 microg/ml for amphotericin B, 0.06 and 8 microg/ml for itraconazole, and 0.5 and more than 64 microg/ml for fluconazole and 5-fluorocytosine. Agreement percentages for the two methodologies were 100% for amphotericin B and fluconazole for all the strains tested. For itraconazole, the agreement percentage was 81.3% in the C. neoformans strain and 100% for all the others. All species had a agreement percentage of 94.1 to 100% when susceptibility to 5-fluorocytosine was tested. It is concluded that environmental isolates of C. neoformans var. neoformans, C. albidus, C. laurentii, and C. uniguttulatus may show high MICs against certain drugs, suggesting in vitro primary resistance to the antifungals tested.  相似文献   

15.
The present study reports a collection of Amblyomma spp. ticks in birds from several areas of the state of São Paulo, Brazil. A total of 568 tick specimens (404 larvae, 164 nymphs) were collected from 261 bird specimens. From these ticks, 204 (36%) specimens (94 larvae, 110 nymphs) were reared to the adult stage, being identified as Amblyomma longirostre (94 larvae, 90 nymphs), Amblyomma calcaratum (13 nymphs), Amblyomma nodosum (2 nymphs), and Amblyomma cajennense (5 nymphs). Additionally, 39 larvae reared to the nymphal stage and 8 nymphs that died before reaching the adult stage were identified as A. longirostre according to peculiar characters inherent to the nymphal stage of this species: scutum elongate, and hypostome pointed. The remaining 271 larvae and 46 nymphs were identified as Amblyomma sp. Ticks were collected from 51 species of birds distributed in 22 bird families and 6 orders. The order Passeriformes constituted the vast majority of the records, comprising 253 (97%) out of the 261 infested birds. Subadults of A. longirostre were identified from 35 species of Passeriformes, comprising 11 families (Cardinalidae, Dendrocolaptidae, Fringillidae, Furnariidae, Parulidae, Pipridae, Thamnophilidae, Thraupidae, Turdidae, Tyrannidae, and Vireonidae), and from 1 species of a non-passerine bird, a puffbird (Bucconidae). Subadults of A. calcaratum were identified from 5 species of Passeriformes, comprising 5 families (Cardinalinae, Conopophagidae, Pipridae, Thamnophilidae and Turdidae). Subadults of A. nodosum were identified from 2 species of Passeriformes, comprising two bird families (Thamnophilidae and Pipridae). Subadults of A. cajennense were identified from 2 species of non-passerine birds, belonging to 2 different orders (Ciconiiformes: Threskiornithidae, and Gruiformes: Cariamidae). Birds were usually infested by few ticks (mean infestation of 2.2 ticks per bird; range: 1–16). Currently, 82 bird species are known to be infested by immature stages of A. longirostre, with the vast majority [74 (90%)] being Passeriformes. Our results showed that Passeriformes seems to be primary hosts for subadult stages of A. longirostre, A. calcaratum, and A. nodosum. However, arboreal passerine birds seem to be the most important hosts for A. longirostre whereas ground-feeding passerine birds seem to be the most important for both A. calcaratum and A. nodosum. In contrast, the parasitism of birds by subadults of A. cajennense has been restricted to non-passerine birds.  相似文献   

16.
Stryphnodendron polyphythum Mart., popularly known as Barbatimão, is a native Brazilian tree widely used in folk medicine as a wound healing agent. Cotyledonary node segments were placed on Murashige and Skoog (MS) medium supplemented with different types and concentrations of cytokinins. The medium that gave best shoot proliferation contained 13.3 M 6-benzyladenine (BA). However, MS supplemented with 0.04 M BA and 0.005 M indole-3-acetic-acid enhanced shoot length. Root formation was best on shoots inserted into medium with half-strength macronutrients supplemented with 5.37 M naphthaleneacetic acid and 80 mg 1–1 phloroglucinol.  相似文献   

17.
In the present study, attempts to isolate Rickettsia in cell culture were performed individually in seven specimens of Haemaphysalis juxtakochi ticks collected in the state of S?o Paulo (southeastern Brazil). Rickettsia was successfully isolated by the shell vial technique and established in Vero cell culture from six ticks (six isolates). DNA extracted from infected cells of these isolates was tested by PCR and DNA sequencing, using genus-specific Rickettsia primers targeting the genes gltA, htrA, ompA, and ompB. After the generated sequences were compared with available sequences in GenBank, five out of the six isolates were identified as Rickettsia bellii (isolates HJ#1, HJ#2, HJ#3, HJ#4, and HJ#7). The sixth isolate (HJ#5) was closest to Rickettsia sp. strain R300, previously detected in H. juxtakochi in northern Brazil, and to Rickettsia rhipicephali, isolated from ticks in the United States. Following recent gene sequence-based criteria proposed for the identification of Rickettsia isolates, both isolate HJ#5 and strain R300 were identified as South American strains of R. rhipicephali, which was confirmed in this continent for the first time. Isolation of R. bellii from H. juxtakochi ticks, added to eight other tick species that have been reported to be infected with this bacterium in Brazil, indicates that R. bellii is indeed the most frequent Rickettsia species infecting ticks in Brazil. Currently, the role of both R. rhipicephali and R. bellii as human pathogens is regarded as unknown.  相似文献   

18.
The benthic algal communities of two subtidal sites, located on opposite coasts of S?o Miguel Island (S?o Roque in the south and S?o Vicente on the north coast), were studied over a 2 year period (September 1993–September 1995). At both sites the sublittoral region was surveyed from low-tide level down to a depth of 15 m. Qualitative and quantitative changes are described. A depth-related gradient in species diversity and biomass was found at both localities. In general, red algae such as corallines and Pterocladiella capillacea predominated in the shallow sublittoral (5 m) while brown algae such as Zonaria and Stypocaulon were more abundant at 15 m. Multivariate analyses emphasized the existence at each study site of two communities (5 and 15 m depth), separated by a large transition zone. The 15 m community on the south coast site showed the largest number of species (52), whereas the lowest diversity (30 species) also occurred at this site in the 5 m community. A clear seasonal pattern of biomass change could be discerned only at S?o Vicente where the highest biomass was recorded in spring/summer. No major inter-annual variations could be detected, indicating relatively stable communities at least on a short-term basis. Received in revised form: 28 March 2001 Electronic Publication  相似文献   

19.
We studied the spatial and temporal variation in O2 and dissolved inorganic carbon (DIC) forms concentrations in ten subtropical watersheds located in the state of São Paulo, Brazil, with different degrees of impact by urbanization and land-use changes. Additionally, we used stable carbon isotopic composition of DIC to explain observed patterns. We found that land-cover changes and watershed geology are the main drivers of DIC distribution. Land-cover/use changes influence the riverine DIC in two ways: by replacing the original Cerrado 3 (C3)-type forest vegetation by C4-type vegetation composed of grasses (pasture), and by sugarcane. Most domestic sewage is dumped untreated into rivers in the state of São Paulo. Consequently, in the most densely populated watersheds, sewage is an important source of labile carbon and consequently of DIC to rivers. In terms of geology, although silicate weathering that produces kaolinite is the main type of weathering in the watersheds, the weathering of carbonate cements present in the geological formations of the western portion of the state of São Paulo are also an important source of DIC to rivers.  相似文献   

20.
The geographic origins of African slave settlers and the Portuguese genetic contribution to the population of S?o Tomé (Gulf of Guinea) were assessed through the analysis of beta-globin haplotypes in 44 chromosomes bearing the betaS allele and through the study of the genetic variation in eight autosomal markers (APOA1, AT3, FY, LPL, OCA2, RB1, Sb19.3, and GC) informative for admixture in a sample of 224 individuals. The observed betaS haplotype distribution (36.4% Bantu, 52.3% Benin, 4.5% Cameroon, 4.5% Senegal, and 2.3% atypical) is in accordance with the historical information on the major geographic sources of slave settlers of S?o Tomé, although it captures a more important contribution of Central-West Africa regions than previously anticipated. European admixture, estimated to be 10.7 +/- 0.9%, has created a considerable level of genetic structure, as indicated by the finding of significant linkage disequilibrium between 33% of unlinked marker loci pairs. Recent admixture was found to have an important contribution to these values, since removal of individuals with Portuguese or Cape Verdian parents or grandparents from the sample dropped the miscegenation level to 6.5 +/- 0.8% and reduced significant linkage disequilibrium to 11% of unlinked marker pairs. Taken together, these results indicate that the peopling of S?o Tomé might have provided one of the first examples of the combination of diverse African contributions and European admixture that emerged from the overseas population relocations promoted by the Atlantic slave trade.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号