Detection of Shiga toxigenic (STEC) and enteropathogenic (EPEC) Escherichia coli in dairy buffalo

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Comparative analysis of two techniques for detection and segmentation of moving bodies

This paper makes a comparative analysis of results produced by the application of two techniques for the detection and segmentation of bodies in motion captured in images sequence, namely: 1) technique based on the temporal average of the values of each pixel recorded in N consecutive image frames and, 2) technique based on historical values associated with pixels recorded in different frames of an image sequence.

Sequential sampling of soybean and beans seeds for Sclerotinia sclerotiorum detection (Lib.) DeBary

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Detection of chromosomal bla(CTX-M-2) in diverse Escherichia coli isolates from healthy broiler chickens

The rise of extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli in food-producing animals is a growing concern for public health. We investigated ESBL producers isolated from broiler chickens in Brazil and characterized 19 CTX-M-2-producing E.coli. The ISCR1 was detected upstream of the chromosome-located gene bla(CTX-M-2), associated with sul-1 type integron structure. CTX-M-2-producing E.coli exhibited different PFGE-types and phylogenetic groups, showing a non-clonal dissemination. The sequence types found (ST93, ST155 and ST2309) have been associated with humans and animals worldwide. Herein, we report the chromosomal location of bla(CTX-M-2) on E.coli, highlighting the risks of multidrug-resistant bacteria in food-producing animals.

Molecular detection and phylogenetic analysis of bovine astrovirus in Brazil

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Detection of bla(CTX-M)-type genes in complex class 1 integrons carried by Enterobacteriaceae isolated from retail chicken meat in Brazil

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Change detection as support for monitoring the dynamic of land around reservoir

The change detection technique was used in this study to provide preliminary information on the dynamics of land cover in the region over the western basin of the Tiete River. This area is characterized by sequence of reservoirs and intense agricultural activity, triggering series negative effects. One of the impacts is contamination and proliferation of aquatic organisms in these aquatics environments, increased by release of nutrients from human activities. This work was possible to observe a large switching classes and secondary vegetation bare land, probably related to agricultural activity.

Venomics of the Australian eastern brown snake (Pseudonaja textilis): detection of new venom proteins and splicing variants

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Development of an Electrochemical Insulin Sensor Based on a High Affinity DNA Sequence Found in the Insulin-linked Polymorphic Region

The detection of pertinent biomarkers has the potential provide an early indication of disease progression before considerable damage has been incurred. A decrease in an individual’s sensitivity to insulin, which may be quantified as the ratio of insulin to glucose in the blood after a glucose pulse, has recently been reported as an early predictor of insulin-dependent diabetes mellitus. Routine measurement of insulin levels is therefore desirable in the care of diabetes-prone individuals. A rapid, simple, and reagentless method for insulin detection would allow for wide-spread screenings that provide earlier signs of diabetes onset. The aim of this thesis is to develop a folding-base electrochemical sensor for the detection of insulin. The sensor described herein consists of a DNA probe immobilized on a gold disc electrode via an alkanethiol linker and embedded in an alkanethiol self-assembled monolayer. The probe is labeled with a redox reporter, which readily transfers electrons to the gold electrode in the absence of insulin. In the presence of insulin, electron transfer is inhibited, presumably due to a binding-induced conformational or dynamic change in the DNA probe that significantly alters the electron-tunneling pathway. A 28-base segment of the insulin-linked polymorphic region that has been reported to bind insulin with high affinity serves as the capture element of the DNA probe. Three probe constructs that vary in their secondary structure and position of the redox label are evaluated for their utility as insulin-sensing elements on the electrochemical platform. The effects of probe modification on secondary structure are also evaluated using circular dichroism spectroscopy.

Detection Methods for the Genus Lysobacter and the Species Lysobacter enzymogenes

Strains of Lysobacter enzymogenes, a bacterial species with biocontrol activity, have been detected via 16S rDNA sequences in soil in different parts of the world. In most instances, however, their occurrence could not be confirmed by isolation, presumably because the species occurred in low numbers relative to faster-growing species of Bacillus or Pseudomonas. In this study, we developed DNA-based detection and enrichment culturing methods for Lysobacter spp. and L. enzymogenes specifically. In the DNA-based method, a region of 16S rDNA conserved among Lysobacter spp. (L4: GAG CCG ACG TCG GAT TAG CTA GTT), was used as the forward primer in PCR amplification. When L4 and universal bacterial primer 1525R were used to amplify DNA from various bacterial species, an 1100-bp product was found in Lysobacter spp. exclusively. The enrichment culturing method involved culturing soils for 3 days in a chitin-containing broth amended with antibiotics. Bacterial strains in the enrichment culture were isolated on yeast-cell agar and then identified by 16S rDNA sequence analysis. A strain of L. enzymogenes added to soils was detected at populations as low as 102 and 104 CFU/g soil by PCR amplification and enrichment culturing, respectively. In a survey of 58 soil samples, Lysobacter was detected in 41 samples by PCR and enrichment culture, out of which 6 yielded strains of Lysobacter spp. by enrichment culture. Among isolated strains, all were identified to be L. enzymogenes, with the exception of a strain of L. antibioticus. Although neither method alone is completely effective at detecting L. enzymogenes, they are complementary when used together and may provide new information on the spatial distribution of the species in soil.

Detection of dengue virus in sera of Brazilian blood donors

BACKGROUND: Dengue is the most important arboviral disease in the world. Dengue viruses (DENVs) have produced huge outbreaks in Brazil in the past 25 years with more than 5 million reported cases. During these epidemics, asymptomatic individuals infected with DENV could donate blood and serve as a source of virus dissemination in the community. Here, we studied the circulation of DENV in healthy individuals during an epidemic outbreak. STUDY DESIGN AND METHODS: The study included 500 serum samples from healthy blood donors collected at the Hemotherapy Center of Ribeirao Preto, Brazil, during a dengue outbreak. The presence of DENV RNA in the serum samples was screened by real-time reverse transcriptionpolymerase chain reaction (PCR). The virus serotype was determined by a heminested PCR procedure. A partial fragment of the NS5 gene sequence was used for phylogenetic analysis. RESULTS: DENV RNA was detected in the serum sample of 2 of 500 (0.4%) individuals. Both of them were infected with DENV-3 Genotype III, a virus that has been circulating in Brazil in the past decade. CONCLUSION: Individuals with asymptomatic DENV infection can be blood donors and serve as a source of virus dissemination in the community. Further studies are needed to determine the risk of recipient infection by DENV as a result of transfusion in Brazil, especially during epidemic periods.

Multi-planet extrasolar systems - detection and dynamics

20 years after the discovery of the first planets outside our solar system, the current exoplanetary population includes more than 700 confirmed planets around main sequence stars. Approximately 50% belong to multiple-planet systems in very diverse dynamical configurations, from two-planet hierarchical systems to multiple resonances that could only have been attained as the consequence of a smooth large-scale orbital migration. The first part of this paper reviews the main detection techniques employed for the detection and orbital characterization of multiple-planet systems, from the (now) classical radial velocity (RV) method to the use of transit time variations (TTV) for the identification of additional planetary bodies orbiting the same star. In the second part we discuss the dynamical evolution of multi-planet systems due to their mutual gravitational interactions. We analyze possible modes of motion for hierarchical, secular or resonant configurations, and what stability criteria can be defined in each case. In some cases, the dynamics can be well approximated by simple analytical expressions for the Hamiltonian function, while other configurations can only be studied with semi-analytical or numerical tools. In particular, we show how mean-motion resonances can generate complex structures in the phase space where different libration islands and circulation domains are separated by chaotic layers. In all cases we use real exoplanetary systems as working examples.

Surveillance using serological and molecular methods for the detection of infectious agents in captive Brazilian neotropic and exotic felids

The aim of the current study was to investigate the exposure of captive wild felids to various infectious pathogens using serological and molecular methods. One hundred and fifty-nine neotropic felids and 51 exotic felids from 28 captive settings in Brazil were tested. While antibodies against Feline parvovirus and Feline coronavirus (FCoV), Feline calicivirus and Bartonella spp. were frequently detected by serologic tests, antibodies against Felid herpesvirus 1 or infection with hemotropic mycoplasmas were less prevalent. Serologic evidence of exposure to Ehrlichia spp., Feline immunodeficiency virus, and Feline leukemia virus (FeLV) was detected rarely, and infections with FeLV, Ehrlichia spp., and Cytauxzoon spp. were found infrequently. The detected Bartonella sequence was molecularly similar to B. koehlerae and B. henselae; for Cytauxzoon, the sequence resembled those from domestic cats. No Anaplasma phagocytophilum and Theileria spp. infections were detected. The positive test results varied significantly among different facilities and species. Additionally, FCoV seropositivity was more prevalent in captivity than in free-ranging populations. Results suggest that testing is appropriate prior to relocation of felids.

Detection of DENV-4 genotype I from mosquitoes collected in the city of Manaus, Brazil

Background Dengue epidemics have been reported in Brazil since 1981. In Manaus, a large city in the Amazon region, dengue is endemic with all four-virus serotypes (DENV-1, -2, -3, and -4) simultaneously causing human disease. In 2008, during a surveillance of dengue virus in mosquitoes in the district of Tancredo Neves in Manaus, 260 mosquitoes of Aedes genus were captured, identified and grouped into pools of 10 mosquitoes. Findings RNA extracts of mosquito pools were tested by a RT-Hemi-Nested-PCR for detection of flaviviruses. One amplicon of 222 bp, compatible with dengue virus serotype 4, was obtained from a pool of Aedes aegypti. The nucleotide sequence of the amplicon indicated that the mosquitoes were infected with DENV-4 of genotype I. This virus of Asian origin has been described in Manaus in 2008 infecting acute febrile illness patients. Conclusion This is the first report of dengue virus serotype 4 genotype I infecting Aedes aegypti in the Americas.

Detection of Hepatitis B virus subgenotype A1 in a Quilombo community from Maranhão, Brazil

Abstract Background The Brazilian population is mainly descendant from European colonizers, Africans and Native Americans. Some Afro-descendants lived in small isolated communities since the slavery period. The epidemiological status of HBV infection in Quilombos communities from northeast of Brazil remains unknown. The aim of this study was to characterize the HBV genotypes circulating inside a Quilombo isolated community from Maranhão State, Brazil. Methods Seventy-two samples from Frechal Quilombo community at Maranhão were collected. All serum samples were screened by enzyme-linked immunosorbent assays for the presence of hepatitis B surface antigen (HBsAg). HBsAg positive samples were submitted to DNA extraction and a fragment of 1306 bp partially comprising HBsAg and polymerase coding regions (S/POL) was amplified by nested PCR and its nucleotide sequence was determined. Viral isolates were genotyped by phylogenetic analysis using reference sequences from each genotype obtained from GenBank (n = 320). Sequences were aligned using Muscle software and edited in the SE-AL software. Bayesian phylogenetic analyses were conducted using Markov Chain Monte Carlo (MCMC) method to obtain the MCC tree using BEAST v.1.5.3. Results Of the 72 individuals, 9 (12.5%) were HBsAg-positive and 4 of them were successfully sequenced for the 1306 bp fragment. All these samples were genotype A1 and grouped together with other sequences reported from Brazil. Conclusions The present study represents the first report on the HBV genotypes characterization of this community in the Maranhão state in Brazil where a high HBsAg frequency was found. In this study, we reported a high frequency of HBV infection and the exclusive presence of subgenotype A1 in an Afro-descendent community in the Maranhão State, Brazil.