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排序方式: 共有197条查询结果,搜索用时 15 毫秒
71.
Ricardo Piazza Meireles Costanza Faranda Elsa Gliozzi Adriano Pimentel Vittorio Zanon Sérgio P. Ávila 《Revue de Micropaléontologie》2012,55(4):133-148
The nine oceanic islands that comprise the Azores archipelago are located in the middle of the northern Atlantic Ocean. In this isolated archipelago, there is a rich fossil record in one of the islands, Santa Maria. In this island, samples were collected in the Upper Miocene composite section of Malbusca outcrop, located in the southern shore of the island, and the fossil marine Ostracoda were studied. This work represents the first report of fossil ostracods from the Azores archipelago. Thirteen species were found, representing seven families and 12 genera (Xestoleberis, Loxoconcha, Callistocythere, Leptocythere, Dameriacella, Aurila, Heliocythere, Pachycaudites, Neonesidea, Cyamocytheridea, ?Quadracythere and Paracypris). Among the identified species, one new species, Leptocythere azorica n. sp., is described. Loxoconcha (two species) was the most diversified genus. The collected species are mainly ornamented and typical of warm waters and epi-neritic habitats (~ 10–50 m of depth). 相似文献
72.
There are many reports of cryptosporidial infection in ostriches, but none with molecular characterization of the isolates. A study was undertaken for the characterization of a Brazilian Cryptosporidium sp. ostrich isolate by using molecular phylogenetic analysis of fragments of the 18S ribosomal DNA, heat-shock protein (hsp) 70 coding gene, and actin coding gene. Biological studies were accomplished by the experimental inoculation of chickens via oral or intratracheal routes with fresh ostrich Cryptosporidium sp. oocysts. Molecular analysis of nucleotide sequences of the 3 genes by using neighbor-joining and parsimony methods grouped the ostrich isolate as a sister taxon of Cryptosporidium baileyi and showed that the ostrich isolate is genetically distinct from all other known Cryptosporidium species or genotypes. None of the inoculated chickens developed infection as determined by mucosal smears, histology, and fecal screening for oocysts. Although biological and molecular studies indicate that the ostrich Cryptosporidium is a new species, further studies regarding morphological, biological, and molecular characteristics of other ostrich isolates are required to confirm the species status of the ostrich Cryptosporidium. 相似文献
73.
KATALIN É. SZABÓ JUDIT MAKK KEVE TIHAMÉR KISS ALEXANDER EILER ÉVA ÁCS BENCE TÓTH ÁRON KEVE KISS STEFAN BERTILSSON 《Freshwater Biology》2008,53(7):1359-1371
1. An artificial glass substratum was incubated in the River Danube for a period of 28 days in order to detect the sequential colonization of microorganisms.
2. Light and fluorescent microscopy showed that microalgae and the picoalgal fraction on the slides increased rapidly over the first 2 weeks of colonization. Diatoms were numerically the most abundant component of the periphyton and their species richness and diversity increased rapidly in the early phase of colonization whereas diversity subsequently increased moderately.
3. Evenness of the diatom community was initially high, lower in the intermediate phase and again higher later on. Succession involving early, intermediate and late colonizer species was observed. Community composition during the first 5 days of colonization was very different from later stages whereas there were only minor changes subsequently.
4. Molecular community analysis by means of terminal restriction fragment length polymorphism analysis of PCR amplified 16S rRNA and 18S rRNA genes pointed to even larger differences between the composition of samples obtained early and late in the period.
5. The number of 18S rRNA and 16S rRNA terminal restriction fragments (T-RF-s) was variable over the colonization period and the fragment patterns of both the bacterial and eukaryotic portion of the microbial community were variable, with most T-RF-s unique to a single sample, suggesting a wide diversity and dynamic properties of periphytic organisms. 相似文献
2. Light and fluorescent microscopy showed that microalgae and the picoalgal fraction on the slides increased rapidly over the first 2 weeks of colonization. Diatoms were numerically the most abundant component of the periphyton and their species richness and diversity increased rapidly in the early phase of colonization whereas diversity subsequently increased moderately.
3. Evenness of the diatom community was initially high, lower in the intermediate phase and again higher later on. Succession involving early, intermediate and late colonizer species was observed. Community composition during the first 5 days of colonization was very different from later stages whereas there were only minor changes subsequently.
4. Molecular community analysis by means of terminal restriction fragment length polymorphism analysis of PCR amplified 16S rRNA and 18S rRNA genes pointed to even larger differences between the composition of samples obtained early and late in the period.
5. The number of 18S rRNA and 16S rRNA terminal restriction fragments (T-RF-s) was variable over the colonization period and the fragment patterns of both the bacterial and eukaryotic portion of the microbial community were variable, with most T-RF-s unique to a single sample, suggesting a wide diversity and dynamic properties of periphytic organisms. 相似文献
74.
Ferreira JM Drumond BP Guedes MI Pascoal-Xavier MA Almeida-Leite CM Arantes RM Mota BE Abrahão JS Alves PA Oliveira FM Ferreira PC Bonjardim CA Lobato ZI Kroon EG 《PloS one》2008,3(8):e3043
Brazilian Vaccinia virus had been isolated from sentinel mice, rodents and recently from humans, cows and calves during outbreaks on dairy farms in several rural areas in Brazil, leading to high economic and social impact. Some phylogenetic studies have demonstrated the existence of two different populations of Brazilian Vaccinia virus strains circulating in nature, but little is known about their biological characteristics. Therefore, our goal was to study the virulence pattern of seven Brazilian Vaccinia virus strains. Infected BALB/c mice were monitored for morbidity, mortality and viral replication in organs as trachea, lungs, heart, kidneys, liver, brain and spleen. Based on the virulence potential, the Brazilian Vaccinia virus strains were grouped into two groups. One group contained GP1V, VBH, SAV and BAV which caused disease and death in infected mice and the second one included ARAV, GP2V and PSTV which did not cause any clinical signals or death in infected BALB/c mice. The subdivision of Brazilian Vaccinia virus strains into two groups is in agreement with previous genetic studies. Those data reinforce the existence of different populations circulating in Brazil regarding the genetic and virulence characteristics. 相似文献
75.
Mônica A. Cupertino-Eisenlohr Ronaldo Vinícius-Silva Leonardo D. Meireles Pedro V. Eisenlohr João A. A. Meira-Neto Ana Paula Santos-Gonçalves 《Biodiversity and Conservation》2017,26(8):1845-1861
Bamboos play an important role in forest dynamics, but management strategies are needed to avoid monodominance. Understanding how climate change would influence the geographic distribution of bamboos could provide management tools for habitat conservation, as well as prevent the expansion of this group. We investigated the distribution patterns of Merostachys species that are endemic to the Brazilian Atlantic Forest, under current and future climate scenarios. We obtained occurrence records based on field collection, herbaria data and online databases. We used the Maxent algorithm to model potential distribution. Future scenarios considered the IPCC forecasted climate for 2070. Our models showed that a reduction in suitable areas for Merostachys species will likely occur, but the existence of suitable areas under climate changes in the Brazilian Atlantic Forest indicates climatic stability in some areas of occurrence of these species in their richness center. Since the fact that in places with local dominance of woody bamboos there is a decrease in the diversity of other plant species, the occurrence of Merostachys throughout the suitable areas may represent risks to biodiversity conservation. Investigations of the synergistic effects of climate change and the local dominance of woody bamboos are required. Therefore, management measures may be very important to control the occurrence of woody bamboos in the Brazilian Atlantic Forest, mainly in climatically stable areas. 相似文献
76.
Distribution of Leguminosae tree species in different altitudinal levels along the Atlantic Rain Forest in the Brazilian coast 下载免费PDF全文
The Atlantic Forest is one of the most threatened tropical forests in the world. Leguminosae, by its great richness and dominance among arboreal stratum elements, is of major importance in the floristic composition and structure of this forest. We investigated the distribution of legume species on an altitudinal gradient to find out the altitudinal zones with higher richness of species; the altitudinal zones with greater floristic similarity; the possible presence of species that may be exclusive to certain vegetation types and the altitudinal amplitudes of those species, as well as the occurrence of species substitution along the altitudinal gradient. Therefore, thirty one studies conducted in different altitudinal levels between 5° S and 29° S were analyzed. A matrix with 142 tree species distributed in altitudinal zones (every 100 m) from sea level to 2100 m was built. The greatest species richness was observed in the Submontane Forest (50–500 m) with 92 species. The cluster analysis revealed a strong dissimilarity of the 1400–2100 m (Upper Montane) and 0–10 m zones (Restinga Forest). The Submontane and the Montane Forest share the highest number of species (38 ssp.). Forty species are unique to Submontane. Substitution of species was verified. Some species have their preferred habitat located at a specific altitudinal amplitude, as is the case of Inga laurina and I. subnuda (0–10 m), I. lanceifolia and Machaerium scleroxylon (800–1200 m). The Leguminosae, although well adapted to the first colonization and establishment of diverse environment, was poorly represented above 1500 m altitude. 相似文献
77.
Ultrafiltration of high-purity grade bovine serum albumin has been carried out under various temperature between 5 and 30 degrees C and at various cross-flow velocities, pressures, and concentrations with the aim of studying protein denaturation and its consequences on the process. Three different pump heads have been tested. Denaturation of proteins in solution has been monitored by laser light scattering and size exclusion chromatography. The rate of protein denaturation increases with temperature, cross-flow, and time. It is observed that membrane fouling is different whether denaturation has occurred or not. Under high-concentration polarization, denaturation can occur in the boundary layer if the wall concentration exceeds 400 g/L. It is shown how the residence time, operating temperature, and pressure play an important part in membrane fouling. This can provide guidelines for process design and control. 相似文献
78.
C. M. Meireles J. Czelusniak I. Sampaio H. Schneider S. F. Ferrari A. F. Coimbra-Filho A. Pissinatti J. A. P. C. Muniz H. S. Ferreira M. P. C. Schneider 《Biochemical genetics》1998,36(7-8):229-244
Five hundred forty-three blood samples from 15populations of the four genera of callitrichin primateswere studied electrophoretically. Polymorphism andgenetic distances were estimated for 20 loci, 13 of which were polymorphic. The lion tamarin(Leontopithecus) studied here exhibited theleast variability for these loci, while the monospecificCebuella showed the most. The genetic distancesobserved between Callithrix andCebuella genera support previous evidenceindicating a close taxonomic relationship between them.Genetic distance values obtained in this study alsosupport the synonimization of the kuhli form with Callithrix jacchuspenicillata. 相似文献
79.
Physiological and biochemical impacts of magnesium-deficiency in two cultivars of coffee 总被引:1,自引:0,他引:1
Dayane Meireles da Silva Isabel Rodrigues Brandão Jose Donizeti Alves Meline Oliveira de Santos Kamila Rezende Dázio de Souza Helbert Rezende Oliveira de Silveira 《Plant and Soil》2014,382(1-2):133-150
Aim
To evaluate biochemical and physiological impacts of magnesium-deficiency on seedlings of two cultivars (Catuaí and Acaiá) of Coffea arabica L..Methods
Six month old seedlings from both cultivars were transferred to plastic receptacles containing solutions with different concentrations of magnesium (Mg). Fully expanded leaves and roots were evaluated at the beginning of treatment and after 10, 20 and 30 days for chlorophyll and carotenoid content, biomass allocation, partitioning of carbohydrates and antioxidant metabolism.Results
Mg-deficiency was characterized by an increase in the shoot/root dry weight ratio, which may be related to accumulation of carbohydrates in leaves. This accumulation is probably responsible for triggering a reduction in the consumption of reducing equivalents, providing favorable conditions for the formation of reactive oxygen species (ROS). The increase in ROS production was accompanied by increases in ascorbate concentration and enzyme activity of the antioxidant metabolism.Conclusions
The Catuaí cultivar is more sensitive to Mg-deficiency than the Acaiá cultivar. When exposed to magnesium deficiency the Catuaí cultivar had reduced growth and its antioxidant metabolism was less efficient at removing ROS. 相似文献80.
André M Siqueira Lucas I Coutinho Rafael L Gurgel Willian CS Su Luiz M Carvalho Silvana G Benzecry Aline CC Alencar Márcia AA Alexandre Maria Gra?as C Alecrim Marcus VG Lacerda 《Memórias do Instituto Oswaldo Cruz》2014,109(5):540-545
Plasmodium vivax is the most widespread parasite causing malaria, being
especially prevalent in the Americas and Southeast Asia. Children are one of the
most affected populations, especially in highly endemic areas. However, there are
few studies evaluating the therapeutic response of infants with vivax malaria.
This study retrospectively evaluated the parasitaemia clearance in children
diagnosed with vivax malaria during the first five days of exclusive treatment
with chloroquine (CQ). Infants aged less than six months old had a significantly
slower parasitaemia clearance time compared to the group of infants and children
between six months and 12 years old (Kaplan-Meier survival analysis; Wilcoxon
test; p = 0.004). The impaired clearance of parasitaemia in younger children with
vivax malaria is shown for the first time in Latin America. It is speculated that
CQ pharmacokinetics in young children with vivax malaria is distinct, but this
specific population may also allow the detection of CQ-resistant parasites during
follow-up, due to the lack of previous immunity. 相似文献