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Sample records for interrogans serovar lai

  1. EFFECTS OF TEMPERATURE ON GENE EXPRESSION PATTERNS IN LEPTOSPIRA INTERROGANS SEROVAR LAI AS ASSESSED BY WHOLE-GENOME MICROARRAYS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The availability of genome sequences for two serovars of Leptospira interrogans, Lai and Copenhageni, has opened up opportunities to examine global transcription profiles using microarray technology. Temperature is a key environmental factor, which is known to affect leptospiral protein expression....

  2. Immunological characteristics of the glycolipid antigen of Leptospira interrogans serovar lai.

    PubMed Central

    Masuzawa, T; Nakamura, R; Shimizu, T; Iwamoto, Y; Morita, T; Yanagihara, Y

    1989-01-01

    The protective antigen (PAg), a glycolipid substance, was extracted from Leptospira interrogans serovar lai strain 017 with a chloroform-methanol-water (1:2:0.8 [vol/vol/vol]) solution and partially purified by silica gel column chromatography. The PAg was not detected by Coomassie brilliant blue staining in sodium dodecyl sulfate-polyacrylamide gel electrophoresis but was observed as a smearlike band, which corresponded to a 24- to 30-kilodalton standard protein, by silver staining. The outer envelope (OE) fraction showed the same band, suggesting that the PAg was one of the chemical components of the OE. The immunogenicity and protective activity of the PAg were compared with those of the OE. The PAg as well as the OE and whole cells was able to induce agglutinating antibody against L. interrogans. Furthermore, the immune sera exhibited opsonic activity against L. interrogans, as observed by measurement of chemical luminescence derived from reactive oxygen. The PAg exhibited protective activity in hamsters challenged with lethal doses of L. interrogans. Therefore, the antigen may be useful as a component vaccine against leptospiral infection. Images PMID:2744857

  3. Protection of guinea pigs against Leptospira interrogans serovar Lai by LipL21 DNA vaccine.

    PubMed

    He, Han Jiang; Wang, Wen Yu; Wu, Zhong Dao; Lv, Zhi Yue; Li, Jun; Tan, Li Zhi

    2008-10-01

    In this study, the full lipL21 gene fragment encoding outer membrane protein LipL21 was cloned from L. interrogans serovar Lai and inserted into eukaryotic expression vector pcDNA3.1(+). The guinea pigs were immunized with pcDNA3.1(+)-lipL21, pcDNA3.1(+) or PBS. Six weeks after the second immunization, the splenocytes were isolated to detect their proliferative ability by lymphocyte transformation experiments. In addition, microscopic agglutination test was used for quantitative detection of specific antibodies. The rest guinea pigs were challenged intraperitoneally with L. interogans sorevar Lai. Then, protective effect was evaluated on the basis of survival and histopathological lesions in the kidneys, lungs, and liver. The lipL21 gene was successfully expressed in COS-7 cells through recombinant pcDNA3.1(+)-lipL21. The titer of specific antibodies substantially increased, and the stimulation index of splenocytes increased significantly. Hence, the pcDNA3.1(+)-lipL21 could protect the immunized guinea pigs from homotypic Leptospira infection. Furthermore, no obvious pathologic changes were observed in the pcDNA3.1(+)-lipL21 immunized guinea pigs. The results showed that the protective effect with pathogenic strains of Leptospira was shared by LipL21 mediated through a plasmid vector. Consequently, these results indicated that the lipL21 DNA vaccine was a promising candidate for the prevention of leptospirosis. PMID:18954563

  4. [Immunogenecity of expressed protein p68 from recombinant plasmid rpDJt in L. interrogans serovar lai].

    PubMed

    Jiang, N; Dai, B; Li, S; Zhao, H; Fang, Z; Wu, W; Ye, D; Liu, J; Song, S; Yang, Y; Zhang, Y; Liu, F; Tu, Y; Yang, H; Huang, Z; Liang, L; Hu, L; Zhao, M

    1997-06-01

    There are two types of infection caused by pathogenic microorganisms, intracellular infection and intercellular infection. Infection of pathogenic leptospira is an intercellular infection. The immunological reaction of host to intercellular infection is unique. The potential immunogen of an expressed protein should meet three criteria: it can be degraded (by antigen-present cells in the host); it should have antigenic epitope which can be recognized by specific antibodies and have at least one epitope that can be recognized by an MHC II protein and T cell receptor. In this study we report the cloning of an L. interrogans protein in plasmid rpDJt and the immunogencity of the expressed protein derivative. A genomic library of L. interrogans serovar lai strain 017 was constructed with the plasmid vector pUC18. Recombinant plasmids, designated pDJH2 and pDJ8 were screened from the bank. EcoRI-inserted fragment of 1. 9 kb recombinant DNA of pDJH2 was ligated into T7 RNA polymerase/promoter vectors (pT7-7). Then they were transformed into E. coli JM109 (De3), one of subclones, designated rpDJt was achieved. SDS-PAGE showed that the molecular weights of expression proteins were 68 kd and 23 kd respectively, designated p68 and p23. Purifying and isolating p68 and p23, we separated them from SDS-Polyacrylamide gels by using Side-Strip method. After fragmenting and electroeluting, p68 and p23 were injected into guinea pigs and rabbits. An extremely strong immune response to p68 was obtained since an anti-p68 antibody response could be detected to a dilution 1:524,288 (guinea pigs) and 1:262,144 (rabbits) by ELISA while anti-P23 antibody being 1:1024 (the same to guinea pigs and rabbits). The results of improved MTT and conA 3HTdR transformation methods showed the activities and proliferation of Th-cells were increased in guinea pigs after p68 immunization (IL-6, 83.25 IU/ml, IL-2, 28.75 IU/ml; RPI, 2.04, SI, 65.62%) Thlymphocyte existed in two subclasses, the Th1- and Th2

  5. Comparative genomic analysis of eight Leptospira strains from Japan and the Philippines revealing the existence of four putative novel genomic islands/islets in L. interrogans serovar Lai strain 56601.

    PubMed

    Youn, Jung-Ho; Hayashida, Kyoko; Koizumi, Nobuo; Ohnishi, Makoto; Sugimoto, Chihiro

    2014-12-01

    Leptospirosis is one of the most widespread zoonotic diseases worldwide and can be considered an emerging health problem to both human and animal. Despite the importance of the disease, complete genome sequences are currently available for only three Leptospira interrogans strains: 56601, Fiocruz L1-130, and IPAV. Therefore, intra- and inter-species comparative genomic analyses of Leptospira are limited. Here, to advance current knowledge of the genomic differences within Leptospira species, next-generation sequencing technology was used to examine the genomes of eight L. interrogans strains belonging to six different serogroups isolated from humans and dogs in Japan and the Philippines. The genomic sequences were mapped to that of the reference strain, L. interrogans serovar Lai strain 56601. The results revealed the presence of four novel genomic islands/islets (GIs) in strain 56601. This study provides a deeper insight into the molecular basis and evolutionary perspective of the virulence of leptospires. PMID:25449997

  6. Complete genome sequence of Leptospira interrogans serovar Bratislava, strain PigK151

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The genus Leptospira contains pathogens serologically classified into over 250 serovars, intermediate pathogens and saprophytes with genetic classification into 21 different species. Worldwide, leptospirosis is one of the most widespread zoonoses. L. interrogans serovar Bratislava has been isolated ...

  7. Draft Genome Sequence of Leptospira interrogans Serovar Bataviae Strain LepIMR 22 Isolated from a Rodent in Johor, Malaysia.

    PubMed

    Amran, Fairuz; Mohd Khalid, Mohd Khairul Nizam; Mohamad, Saharuddin; Mat Ripen, Adiratna; Ahmad, Norazah; Goris, Marga G A; Muhammad, Ayu Haslin; Noor Halim, Nurul Atiqah

    2016-01-01

    Leptospira interrogans serovar Bataviae was recently identified as one of the persistent Leptospira serovars in Malaysia. Here, we report the draft genome sequence of the L. interrogans serovar Bataviae strain LepIMR 22 isolated from kidney of a rodent in Johor, Malaysia. PMID:27609924

  8. Whole Genome Sequencing Allows Better Understanding of the Evolutionary History of Leptospira interrogans Serovar Hardjo

    PubMed Central

    Llanes, Alejandro; Restrepo, Carlos Mario; Rajeev, Sreekumari

    2016-01-01

    The genome of a laboratory-adapted strain of Leptospira interrogans serovar Hardjo was sequenced and analyzed. Comparison of the sequenced genome with that recently published for a field isolate of the same serovar revealed relatively high sequence conservation at the nucleotide level, despite the different biological background of both samples. Conversely, comparison of both serovar Hardjo genomes with those of L. borgpetersenii serovar Hardjo showed extensive differences between the corresponding chromosomes, except for the region occupied by their rfb loci. Additionally, comparison of the serovar Hardjo genomes with those of different L. interrogans serovars allowed us to detect several genomic features that may confer an adaptive advantage to L. interrogans serovar Hardjo, including a possible integrated plasmid and an additional copy of a cluster encoding a membrane transport system known to be involved in drug resistance. A phylogenomic strategy was used to better understand the evolutionary position of the Hardjo serovar among L. interrogans serovars and other Leptospira species. The proposed phylogeny supports the hypothesis that the presence of similar rfb loci in two different species may be the result of a lateral gene transfer event. PMID:27442015

  9. Heat stability of protective antigen of Leptospira interrogans serovar lai.

    PubMed Central

    Masuzawa, T; Nakamura, R; Shimizu, T; Yanagihara, Y

    1990-01-01

    Protective antigen (PAg; glycolipid antigen; molecular size, 23 to 30 kilodaltons), the serogroup-specific antigen partially purified from leptospiral cells, is one of the most important protective antigens. The heat stability of PAg was compared with that of whole-cell (WC) antigen by using sodium dodecyl sulfate-polyacrylamide gel electrophoresis, immunoblotting, protective activity, opsonin-inducing activity, agglutinating antibody-inducing activity, and an inhibition test in an enzyme-linked immunosorbent assay. A band of 23 to 30 kilodaltons of PAg, which was seen in untreated PAg and WC, shifted to a position with a molecular size of ca. 20 kilodaltons after heat treatment of PAg at 80 degrees C for 30 min and WC at 100 degrees C for 30 min. In the enzyme-linked immunosorbent assay inhibition test with monoclonal antibody LW2 and a sonicated antigen of WC, the inhibition rate of PAg and WC to sonicated WC was reduced by heat treatment at 80 degrees C for 30 min and at 100 degrees C for 30 min, respectively. Agglutinating antibody-inducing activities and opsonin-inducing activities of PAg and WC in mice were reduced by heat treatment under the same conditions; these activities were assayed by a microscopic agglutination test and by chemical luminescence response in serum from immunized mice, respectively. Protective activity of heated PAg and heated WC in cyclophosphamide-pretreated mice agreed with the results of immunogenicity in mice. These results indicate that the Leptospira PAg is one of the important protective antigens and is altered by heat treatment at 80 degrees C. Furthermore, the immunogenicity and antigenicity of the PAg present in WC are more stable than that of the extracted PAg, and the coexistence of other cellular components with PAg might protect and stabilize PAg from the heat treatment. Images PMID:2332463

  10. Complete Genome Sequence of Leptospira interrogans Serovar Bratislava, Strain PigK151.

    PubMed

    Alt, David P; Wilson-Welder, Jennifer H; Bayles, Darrell O; Cameron, Caroline; Adler, Ben; Bulach, Dieter M; Seemann, Torsten; Lehane, Michael J; Haines, Lee R; Darby, Alistair C; Hall, Neil; Radford, Alan D; Zuerner, Richard L

    2015-01-01

    Leptospira interrogans serovar Bratislava infection occurs in multiple domestic and wildlife species and is associated with poor reproductive performance in swine and horses. We present the complete genome assembly of strain PigK151 comprising two chromosomes, CI (4.457 Mbp) and CII (358 kbp). PMID:26112787

  11. First Genome Sequence of Leptospira interrogans Serovar Pomona, Isolated from a Bovine Abortion.

    PubMed

    Varni, Vanina; Koval, Ariel; Nagel, Ariel; Ruybal, Paula; Caimi, Karina; Amadio, Ariel F

    2016-01-01

    Leptospirosis is a widespread zoonosis and a re-emergent disease of global distribution with major relevance in veterinary production. Here, we report the whole-genome sequence of Leptospira interrogans serovar Pomona strain AKRFB, isolated from a bovine abortion during a leptospirosis outbreak in Argentina. PMID:27198013

  12. Complete Genome Sequence of Leptospira interrogans Serovar Bratislava, Strain PigK151

    PubMed Central

    Alt, David P.; Bayles, Darrell O.; Cameron, Caroline; Adler, Ben; Bulach, Dieter M.; Seemann, Torsten; Lehane, Michael J.; Haines, Lee R.; Darby, Alistair C.; Hall, Neil; Radford, Alan D.; Zuerner, Richard L.

    2015-01-01

    Leptospira interrogans serovar Bratislava infection occurs in multiple domestic and wildlife species and is associated with poor reproductive performance in swine and horses. We present the complete genome assembly of strain PigK151 comprising two chromosomes, CI (4.457 Mbp) and CII (358 kbp). PMID:26112787

  13. Characterization of an antigenic oligosaccharide from Leptospira interrogans serovar pomona and its role in immunity.

    PubMed Central

    Midwinter, A; Vinh, T; Faine, S; Adler, B

    1994-01-01

    An antigenic oligosaccharide fraction derived from the lipopolysaccharide of Leptospira interrogans serovar pomona was isolated by endo-glycosidase H digestion and column chromatography. The oligosaccharide contained rhamnose, ribose, glucose, and glucosamine and inhibited the binding of opsonic, protective monoclonal antibodies directed against the lipopolysaccharide. When conjugated to diphtheria toxoid, the oligosaccharide elicited the production of agglutinating, opsonic antibodies. Images PMID:7960129

  14. First Genome Sequence of Leptospira interrogans Serovar Pomona, Isolated from a Bovine Abortion

    PubMed Central

    Varni, Vanina; Koval, Ariel; Nagel, Ariel; Ruybal, Paula

    2016-01-01

    Leptospirosis is a widespread zoonosis and a re-emergent disease of global distribution with major relevance in veterinary production. Here, we report the whole-genome sequence of Leptospira interrogans serovar Pomona strain AKRFB, isolated from a bovine abortion during a leptospirosis outbreak in Argentina. PMID:27198013

  15. Molecular characterization, serotyping, and antibiotic susceptibility profile of Leptospira interrogans serovar Copenhageni isolates from Brazil.

    PubMed

    Miraglia, Fabiana; Matsuo, Minekazo; Morais, Zenaide Maria; Dellagostin, Odir Antonio; Seixas, Fabiana Kömmling; Freitas, Julio César; Hartskeerl, Rudy; Moreno, Luisa Zanolli; Costa, Bárbara Letícia; Souza, Gisele Oliveira; Vasconcellos, Silvio Arruda; Moreno, Andrea Micke

    2013-11-01

    Leptospira interrogans serogroup Icterohaemorrhagiae is the major serogroup infecting humans worldwide, and rodents and dogs are the most significant transmission sources in urban environments. Knowledge of the prevalent serovars and their maintenance hosts is essential to understand the epidemiology of leptospirosis. In this study, 20 Leptospira isolates were evaluated by pulsed-field gel electrophoresis (PFGE), variable number tandem-repeat analysis (VNTR), serotyping, and determination of antimicrobial resistance profile. Isolates, originated from bovine, canine, human, and rodent sources, were characterized by microscopic agglutination test with polyclonal and monoclonal antibodies and were identified as L. interrogans serogroup Icterohaemorrhagiae serovar Copenhageni. MICs of antimicrobials often used in veterinary medicine were determined by broth microdilution test. Most of tested antibiotics were effective against isolates, including penicillin, ampicillin, and ceftiofur. Higher MIC variability was observed for fluoroquinolones and neomycin; all isolates were resistant to trimethoprim/sulfamethoxazole and sulphadimethoxine. Isolates were genotyped by PFGE and VNTR; both techniques were unable to discriminate between serovars Copenhageni and Icterohaemorrhagiae, as expected. PFGE clustered all isolates in 1 pulsotype, indicating that these serovars can be transmitted between species and that bovine, rodent, and dogs can maintain them in the environment endangering the human population. PMID:24054736

  16. Geographical dissemination of Leptospira interrogans serovar Pomona during seasonal migration of California sea lions.

    PubMed

    Zuerner, Richard L; Cameron, Caroline E; Raverty, Stephen; Robinson, John; Colegrove, Kathleen M; Norman, Stephanie A; Lambourn, Dyanna; Jeffries, Steven; Alt, David P; Gulland, Frances

    2009-05-28

    Leptospirosis is one of the most widespread bacterial zoonoses in the world and affects most mammalian species. Although leptospirosis is well documented and characterized in terrestrial species, less information is available regarding the distribution and impact of leptospirosis in marine mammals. Additionally, the role of animal migrations on the geographical spread of leptospirosis has not been reported. Periodic epizootic outbreaks of acute leptospirosis among California sea lions (Zalophus californianus) have been reported since 1971. In this study, we collected samples from California sea lions stranded along the Pacific coast of North America during the most recent epidemic in 2004, and maintained leptospirosis surveillance of the California sea lion population along the California coast through 2007. Several isolates of Leptospira interrogans serovar Pomona were obtained from kidney and urine samples collected during this study, a finding consistent with serological evidence that California sea lions are persistently exposed to this leptospiral serovar. Combined, these data support a model whereby California sea lions are maintenance hosts for L. interrogans serovar Pomona, yet periodically undergo outbreaks of acute infection. During the 2004 outbreak, the incidence of new leptospirosis cases among California sea lions coincided with the seasonal movement of male sea lions from rookeries along the coast of central and southern California north as far as British Columbia. These data show that seasonal animal movement contributes to the distribution of leptospirosis across a large geographical region. PMID:19186009

  17. [The serovars of Leptospira interrogans isolated from cases of human leptospirosis in São Paulo, Brazil].

    PubMed

    Sakata, E E; Yasuda, P H; Romero, E C; Silva, M V; Lomar, A V

    1992-01-01

    Eighteen strains of L. interrogans isolated from human cases were serotyped by the agglutinin-absorption test at Instituto Adolfo Lutz in São Paulo, Brazil. Fourteen were identified as serovar copenhageni (icterohaemorrhagiae serogroup), 2 as canicola (canicola serogroup), 1 as castellonis (Ballum serogroup) and 1 as pomona serogroup (serovar not yet defined). The frequency of serovar copenhageni in 100% of the isolates in icterohaemorrhagiae serogroup is emphasized and more studies to verify the real serovars prevalence as subsidy to the epidemiology of this infection are suggested by the authors. PMID:1342073

  18. Isolation of Leptospira interrogans serovar grippotyphosa from the skin of a dog.

    PubMed

    Anderson, J F; Miller, D A; Post, J E; Johnson, R C; Magnarelli, L A; Andreadis, T G

    1993-12-01

    Leptospira interrogans serovar grippotyphosa was isolated from the skin of a 14-year-old male dog with deteriorating health. Necropsy revealed numerous lesions characteristic of aged dogs, but no evidence of acute hepatitis or nephritis, which are common features of pathogenic Leptospira infections. Antibody to Leptospira was not detected in the dog's serum by microagglutination. Leptospires grew slowly in Barbour-Stoenner-Kelly medium, a medium commonly used to isolate Borrelia, but then grew abundantly in Tween 80-bovine albumin leptospire medium. The isolate was pathogenic to a hamster and was identified by microagglutination and restriction endonuclease analysis. PMID:8288477

  19. Leptospira interrogans serovar hardjo Infection in Cattle in the South Okanagan District of British Columbia

    PubMed Central

    Kingscote, Barbara F.

    1985-01-01

    An outbreak of leptospirosis due to Leptospira interrogans serovar hardjo in the South Okanagan District of British Columbia was investigated. The infection was associated primarily with bulls, but serovar hardjo was isolated from both bulls and cows at slaughter. Kidney and cerebrospinal fluid were found to contain leptospires, independently of the presence and level of serum agglutinins. Treatment of a bull twice in six months with dihydrostreptomycin failed to diminish an agglutinin titer (1/200) which persisted for two years without reexposure of the bull. A serological survey of cull cows sold through a central auction mart revealed the presence of hardjo agglutinins in 15.4% of 1300 sera representing 163 herds in 20 locations. Thirty percent of these herds contained reactor cattle. The number of premises from which reactor cattle came in a given locality varied from 4% to 67.7%. Measures to control leptospirosis in the study are suggested. PMID:17422584

  20. Variable Nucleotide Tandem-Repeat Analysis Revealing a Unique Group of Leptospira interrogans Serovar Pomona Isolates Associated with California Sea Lions

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Leptospira interrogans serovar Pomona is commonly isolated from a variety of wildlife and domesticated livestock. It is difficult to assess whether disease outbreaks with serovar Pomona in given animal populations are due to endemic infections or accidental exposure. Unlike many leptospiral serovars...

  1. Evaluation of pathogenic serovars of Leptospira interrogans in dairy cattle herds of Shahrekord by PCR

    PubMed Central

    Jafari Dehkordi, A; Shahbazkia, HR; Ronagh, N

    2011-01-01

    Background and objectives Leptospirosis is an important zoonotic disease caused by Leptospira interrogans. Leptospirosis leads to economical losses in dairy farm industry. The objective of this study was to evaluate the pathogenic serovars of Leptospira interrogans in dairy cattle herds of Shahrekord by PCR. Materials and Methods Two hundred samples (100 urine and 100 blood) were collected from 100 cows randomly and delivered to the laboratory. Samples were stored at -20 °C. DNA was extracted and purified from the plasma and urine samples and concentrated on diatoms in the presence of guanidine thiocyanate (GuSCN). PCR products were detected and identified as Leptospira by ilumination of the expected size of DNA bands after staining of the agarose gel with ethidium bromide gels. PCR products were purified and sequenced. Results The results showed that 28% of urine samples and 23% of plasma samples were contaminated. The major serotypes were Icterohaemorrhagiae (50%) and Pomona (37.5%). The urine samples of 17 cows were positive for Leptospira without positive plasma samples. This indicated that these cows are reservoirs in dairy herds of Shahrekord and dangerous for human health. The plasma samples of twelve cows were positive for Leptospira without positive urine samples. Conclusions Leptospira serotypes can be maintained in relatively dry regions and must be considered when dealing with leptospirosis in dairy farms of Shahrekord and human health. PMID:22347596

  2. Iron metabolism in hamsters experimentally infected with Leptospira interrogans serovar Pomona: influence on disease pathogenesis.

    PubMed

    Sobroza, Ânderson O; Tonin, Alexandre A; Da Silva, Alekandro S; Dornelles, Guilherme L; Wolkmer, Patrícia; Duarte, Marta M M F; Hausen, Bruna S; Sangoi, Manuela B; Moresco, Rafael N; Stefani, Lenita M; Mazzantti, Cinthia M; Lopes, Sonia T A; Leal, Marta L R

    2014-12-01

    The aim of this study was to analyze the classic iron markers associated to the storage process in hamsters experimentally infected by Leptospira interrogans serovar Pomona. Four groups with six hamsters each were used; two were negative controls (C7 and C14) and two were composed by infected animals (T7 and T14). Blood samples were collected on the seventh (C7 and T7) and fourteenth days (C14 and T14) post-inoculation. Iron availability was determined in sera samples through the assessment of iron, ferritin, transferrin, and iron binding capacity, whereas the bone marrow was also evaluated for the presence of iron by Pearl's reaction. Additionally, the total antioxidant capacity (TAC) and total oxidant status (TOS) were assessed, along with hepcidin and IL-6 levels. Based on the results, it was possible to observe the onset of an anemic profile, predominantly hemolytic and regenerative. Also, The other parameters showed an increase in seric iron (P<0.01) and ferritin (P<0.01), and a positive Pearl's reaction in T7 and T14, when compared with the control groups. Transferrin levels decreased (P<0.05) in animals of T14 with saturation index. TAC was increased in both periods (P<0.01), while TOS was increased only on T14 (P<0.05). Hepcidin and IL-6 were increased on T7 and T14 (P<0.01). Therefore, it was observed that the serum profile from infected animals showed a strong hemolytic pattern, with some demonstration of ferric tissue sequestration when the infection tended to become chronic. The results show that iron metabolism is activated in hamsters infected by L. interrogans serovar Pomona. PMID:25449998

  3. Leptospira interrogans serovars Bratislava and Muenchen animal infections: Implications for epidemiology and control.

    PubMed

    Arent, Z; Frizzell, C; Gilmore, C; Allen, A; Ellis, W A

    2016-07-15

    Strains of Leptospira interrogans belonging to two very closely related serovars - Bratislava and Muenchen - have been associated with disease in domestic animals, in particular pigs, but also in horses and dogs. Similar strains have also been recovered from various wildlife species. Their epidemiology is poorly understood. Two hundred and forty seven such isolates, from UK domestic animal and wildlife species, were examined by restriction endonuclease analysis in an attempt to elucidate their epidemiology. A representative sub-sample of 65 of these isolates was further examined by multiple-locus variable-number tandem repeat analysis and 22 by secY sequencing. Ten restriction pattern types were identified. The majority of isolates fell into one of three restriction endonuclease analysis pattern types designated B2a, B2b and M2a. B2a was ubiquitous and was isolated from 10 species and represented the majority of the horse and all dog isolates. B2b was very different, being isolated only from pigs, indicating that this type was maintained by pigs. The pattern M2a was reported for the majority of isolates from pigs but also was common in small rodents isolates. Five restriction pattern types were found only in wildlife suggesting that they are unlikely to pose a disease threat to domestic animals. Multiple-locus variable-number tandem repeat analysis identified six clusters. The REA types B2a and B2b were all found in one MLVA cluster while the majority of the M2a strains examined occurred in another cluster. The secY sequencing detected only one sequence type, clustered with other serovars of Leptospira interrogans. PMID:27283852

  4. Isoleucine biosynthesis in Leptospira interrogans serotype lai strain 56601 proceeds via a threonine-independent pathway.

    PubMed

    Xu, Hai; Zhang, Yuzhen; Guo, Xiaokui; Ren, Shuangxi; Staempfli, Andreas A; Chiao, Juishen; Jiang, Weihong; Zhao, Guoping

    2004-08-01

    Three leuA-like protein-coding sequences were identified in Leptospira interrogans. One of these, the cimA gene, was shown to encode citramalate synthase (EC 4.1.3.-). The other two encoded alpha-isopropylmalate synthase (EC 4.1.3.12). Expressed in Escherichia coli, the citramalate synthase was purified and characterized. Although its activity was relatively low, it was strictly specific for pyruvate as the keto acid substrate. Unlike the citramalate synthase of the thermophile Methanococcus jannaschii, the L. interrogans enzyme is temperature sensitive but exhibits a much lower K(m) (0.04 mM) for pyruvate. The reaction product was characterized as (R)-citramalate, and the proposed beta-methyl-d-malate pathway was further confirmed by demonstrating that citraconate was the substrate for the following reaction. This alternative pathway for isoleucine biosynthesis from pyruvate was analyzed both in vitro by assays of leptospiral isopropylmalate isomerase (EC 4.2.1.33) and beta-isopropylmalate dehydrogenase (EC 1.1.1.85) in E. coli extracts bearing the corresponding clones and in vivo by complementation of E. coli ilvA, leuC/D, and leuB mutants. Thus, the existence of a leucine-like pathway for isoleucine biosynthesis in L. interrogans under physiological conditions was unequivocally proven. Significant variations in either the enzymatic activities or mRNA levels of the cimA and leuA genes were detected in L. interrogans grown on minimal medium supplemented with different levels of the corresponding amino acids or in cells grown on serum-containing rich medium. The similarity of this metabolic pathway in leptospires and archaea is consistent with the evolutionarily primitive status of the eubacterial spirochetes. PMID:15292141

  5. Molecular and serological characterization of Leptospira interrogans serovar Canicola isolated from dogs, swine, and bovine in Brazil.

    PubMed

    Miraglia, Fabiana; de Morais, Zenaide M; Dellagostin, Odir A; Seixas, Fabiana K; Freitas, Julio C; Zacarias, Francielle G S; Delbem, Adina C; Ferreira, Thaís S P; Souza, Gisele O; Hartskeerl, Rudy A; Vasconcellos, Silvio A; Moreno, Andrea M

    2013-01-01

    The identification of Leptospira clinical isolates through genotyping and serotyping, besides the recognition of its reservoirs, are important tools for understanding the epidemiology of leptospirosis, and they are also keys for identifying new species and serovars. Fourteen clinical isolates from animals were characterized by means of single enzyme amplified length polymorphism, variable number of tandem repeat analysis, pulsed field gel electrophoresis, and serotyping. All isolates were identified as Leptospira interrogans, serovar Canicola. Infections by this serovar occur in urban regions, where dogs represent the main maintenance hosts, whereas bovine and swine may act as reservoirs of serovar Canicola in rural areas. Both urban and rural aspects of leptospirosis, and the role of domestic animals as maintenance hosts, cannot be neglected in developing and developed countries. PMID:22610538

  6. Asymptomatic and chronic carriage of Leptospira interrogans serovar Pomona in California sea lions (Zalophus californianus).

    PubMed

    Prager, K C; Greig, Denise J; Alt, David P; Galloway, Renee L; Hornsby, Richard L; Palmer, Lauren J; Soper, Jennifer; Wu, Qingzhong; Zuerner, Richard L; Gulland, Frances M D; Lloyd-Smith, James O

    2013-05-31

    Since 1970, periodic outbreaks of leptospirosis, caused by pathogenic spirochetes in the genus Leptospira, have caused morbidity and mortality of California sea lions (Zalophus californianus) along the Pacific coast of North America. Yearly seasonal epizootics of varying magnitude occur between the months of July and December, with major epizootics occurring every 3-5 years. Genetic and serological data suggest that Leptospira interrogans serovar Pomona is the infecting serovar and is enzootic in the California sea lion population, although the mechanism of persistence is unknown. We report asymptomatic carriage of Leptospira in 39% (33/85) of wild, free-ranging sea lions sampled during the epizootic season, and asymptomatic seroconversion with chronic asymptomatic carriage in a rehabilitated sea lion. This is the first report of asymptomatic carriage in wild, free-ranging California sea lions and the first example of seroconversion and asymptomatic chronic carriage in a sea lion. Detection of asymptomatic chronic carriage of Leptospira in California sea lions, a species known to suffer significant disease and mortality from the same Leptospira strain, goes against widely-held notions regarding leptospirosis in accidental versus maintenance host species. Further, chronic carriage could provide a mechanism for persistent circulation of Leptospira in the California sea lion population, particularly if these animals shed infectious leptospires for months to years. PMID:23419822

  7. Molecular studies on European equine isolates of Leptospira interrogans serovars Bratislava and Muenchen.

    PubMed

    Arent, Zbigniew; Gilmore, Colm; Brem, Siegfried; Ellis, William A

    2015-08-01

    Strains of Leptospira interrogans belonging to two very closely related serovars – Bratislava and Muenchen – are known to cause widespread infection of the horse population in many parts of the world. Conventional serological typing of isolates has been unable to differentiate between wildlife, pig, dog and possibly horse maintained isolates and therefore has been unable to provide further insight into their diversity and the relationship between them. Twenty-one such European isolates of serovar Bratislava and Muenchen were examined by restriction endonuclease analysis and multiple-locus variable-number tandem repeat analysis in an attempt to elucidate their epidemiology. The restriction pattern types were identified and fell into one of four REA designed pattern types, B1, B2a, M1, M2a. Nine strains from Northern Ireland and two from Germany belonged to B2a, which is a ubiquitous strain being originally isolated from a large number of wild and domestic animal species in the UK. Five strains were identified as B1 and they came from Portugal, The Netherlands, Germany and Northern Ireland; three strains isolated in Germany belong to M1; two strains belonged to M2a. Genotypes B1 and M1 have, with the exception of one hedgehog isolate, been recovered only from horses and it may indicate their adaptation to this species. PMID:26165505

  8. Whole-Genome Sequence of Leptospira interrogans Serovar Hardjo Subtype Hardjoprajitno Strain Norma, Isolated from Cattle in a Leptospirosis Outbreak in Brazil.

    PubMed

    Cosate, M R V; Soares, S C; Mendes, T A; Raittz, R T; Moreira, E C; Leite, R; Fernandes, G R; Haddad, J P A; Ortega, J Miguel

    2015-01-01

    Leptospirosis is caused by pathogenic bacteria of the genus Leptospira spp. This neglected re-emergent disease has global distribution and relevance in veterinary production. Here, we report the whole-genome sequence and annotation of Leptospira interrogans serovar Hardjo subtype Hardjoprajitno strain Norma, isolated from cattle in a livestock leptospirosis outbreak in Brazil. PMID:26543126

  9. Whole-Genome Sequence of Leptospira interrogans Serovar Hardjo Subtype Hardjoprajitno Strain Norma, Isolated from Cattle in a Leptospirosis Outbreak in Brazil

    PubMed Central

    Soares, S. C.; Mendes, T. A.; Raittz, R. T.; Moreira, E. C.; Leite, R.; Fernandes, G. R.; Haddad, J. P. A.; Ortega, J. Miguel

    2015-01-01

    Leptospirosis is caused by pathogenic bacteria of the genus Leptospira spp. This neglected re-emergent disease has global distribution and relevance in veterinary production. Here, we report the whole-genome sequence and annotation of Leptospira interrogans serovar Hardjo subtype Hardjoprajitno strain Norma, isolated from cattle in a livestock leptospirosis outbreak in Brazil. PMID:26543126

  10. Management practices as risk factors for the presence of bulk milk antibodies to Salmonella, Neospora caninum and Leptospira interrogans serovar hardjo in Irish dairy herds.

    PubMed

    O' Doherty, E; Berry, D P; O' Grady, L; Sayers, R

    2014-06-01

    A survey of management practices in 309 Irish dairy herds was used to identify risk factors for the presence of antibodies to Salmonella, Neospora caninum and Leptospira interrogans serovar hardjo in extensively managed unvaccinated dairy herds. A previous study documented a herd-level seroprevalence in bulk milk of 49%, 19% and 86% for Salmonella, Neospora caninum and leptospira interrogans serovar hardjo, respectively in the unvaccinated proportion of these 309 herds in 2009. Association analyses in the present study were carried out using multiple logistic regression models. Herds where cattle were purchased or introduced had a greater likelihood of being positive to leptospira interrogans serovar hardjo (P<0.01) and Salmonella (P<0.01). Larger herds had a greater likelihood of recording a positive bulk milk antibody result to leptospira interrogans serovar hardjo (P<0.05). Herds that practiced year round calving were more likely to be positive to Neospora caninum (P<0.05) compared to herds with a spring-calving season, with no difference in risk between herds that practiced split calving compared to herds that practiced spring calving. No association was found between presence of dogs on farms and prevalence of Neospora caninum possibly due to limited access of dogs to infected materials including afterbirths. The information from this study will assist in the design of suitable control programmes for the diseases under investigation in pasture-based livestock systems. PMID:24661904

  11. Prevalence of antibodies to Leptospira interrogans serovar hardjo in bulk tank milk from unvaccinated irish dairy herds

    PubMed Central

    2004-01-01

    Bulk tank milk samples, collected from 347 herds throughout the Republic of Ireland using a sampling frame based on seven milk-recording organisations, were tested by ELISA for antibodies to Leptospira interrogans serovar hardjo. These herds, which had not been vaccinated against leptospirosis within the previous five years, were categorised according to their province, milk-recording organisation and size. Two-hundred-and-seventy-three herds (79%) had a positive ELISA titre. Both the probability of a herd being seropositive and the antibody level in the herd milk sample were affected by the province (P < 0.05 and P < 0.01, respectively) and the herd size category (P < 0.05 and P < 0.01, respectively). Larger herds were significantly more likely to have positive reactions and higher mean concentrations of antibody. It was concluded that a high proportion of unvaccinated Irish dairy herds have been exposed to infection with Leptospira hardjo. PMID:21851657

  12. Characterization of Leptospira interrogans Serovars by Polymorphism Variable Number Tandem Repeat Analysis

    PubMed Central

    Rezasoltani, Sama; Dabiri, Hossein; Khaki, Pejvak; Rostami Nejad, Mohammad; Karimnasab, Nasim; Modirrousta, Shiva

    2015-01-01

    Background: Leptospirosis is recognized as a re-emerging infectious disease; therefore, understanding the epidemiology of the disease is vital for designing intervention programs and diminishing its transmission. Recently, Multilocus variable number tandem repeat analysis (MLVA) is used for segregating and identifying Leptospira serovars. The method has potential application in investigating the molecular epidemiology of Leptospira. Objectives: The propose of this study was genomic identification of pathogenic Leptospires in Iran by MLVA. Materials and Methods: Leptospira serovars were obtained from National Reference Laboratory of Leptospira at Razi Vaccine and Serum Research Institute, Karaj, Iran. Serovars were cultured into the liquid EMJH medium and incubated at 28˚C for 7 days. DNA of serovars was extracted using the phenol-chloroform method. PCR was performed with 5 selected variable number tandem repeat analysis (VNTR) loci. The amplified products were analyzed by agarose gel electrophoresis. The size of the amplified products was estimated by 100 bp ladder and sequencing analysis. Results: The saprophytic serovar showed no amplified fragments. PCR products in all pathogenic serovars were observed. The 12 reference serovars used for the development of technique displayed distinct patterns. Conclusions: Results showed that MLVA technique with its range of polymorphism is a good marker for identification of pathogenic serovars. Some VNTR loci are more powerful than the other ones with regard to differentiation. Serovars from the same geographical area have more genetic similarity than same serovars from different places. MLVA is a suitable technique for epidemiological survey. PMID:26568805

  13. DNA probe for detection of the Leptospira interrogans serovar hardjo genotype hardjo-bovis.

    PubMed Central

    LeFebvre, R B

    1987-01-01

    A DNA probe is described for the diagnostic and taxonomic identification of the North American cattle pathogen Leptospira interrogans genotype hardjo-bovis. The probe is specific for this genotype and does not hybridize to genomic DNA of any other leptospire pathogen commonly found in North America. Images PMID:2826538

  14. SEROPREVALENCE OF NINE LEPTOSPIRA INTERROGANS SEROVARS IN WILD CARNIVORES, UNGULATES, AND PRIMATES FROM A ZOO POPULATION IN A METROPOLITAN REGION OF CHILE.

    PubMed

    Moreno-Beas, Eduardo; Abalos, Pedro; Hidalgo-Hermoso, Ezequiel

    2015-12-01

    Serum samples from 130 individuals representing 42 species of carnivores, ungulates, and primates from a population of captive mammals in Metropolitan Region in Chile were tested for antibodies against nine serovars of Leptospira interrogans using the microscopic agglutination test. Ten percent of the animals were seropositive to one or more serovars. Seroprevalence was significantly higher in ungulates (20.4%) compared to carnivores (3.8%) and primates (3.4%). There were no significant differences in seroprevalence among sex and age ranges. The most frequent serovar detected was Autumnalis, present in 53.4% of antibody-positive animals. Most positive animals had titers of ≤1 : 200, except for a maned wolf ( Chrysocyon brachyurus ) with titers of 1 : 400 against serovar Hardjo. To the authors' knowledge, this is the first report of Leptospira exposure detected in native endangered pudu ( Pudu puda ) and the first confirmation of exposure to L. interrogans in captive wild mammals in Chile. Leptospirosis should be considered as a differential diagnosis in future disease presentation for hepatitis or abortions in captive mammals in Chile. PMID:26667533

  15. Identification of a 35-kilodalton serovar-cross-reactive flagellar protein, FlaB, from Leptospira interrogans by N-terminal sequencing, gene cloning, and sequence analysis.

    PubMed Central

    Lin, M; Surujballi, O; Nielsen, K; Nadin-Davis, S; Randall, G

    1997-01-01

    During the screening of antibodies to pathogenic leptospires, a murine monoclonal antibody (designated M138) was found to react with various serovars. An antigen of approximately 35 kDa from Leptospira interrogans serovar pomona, which reacted strongly with M138, was characterized by N-terminal amino acid sequencing and identified as a flagellin, a class B polypeptide subunit (FlaB) of the periplasmic flagella. The gene encoding the FlaB protein, flaB, was amplified from the genomic DNA of several pathogenic serovars by PCR with a single pair of oligonucleotide primers, suggesting that FlaB is highly conserved among these serovars. Cloning and sequence analysis of flaB from serovar pomona revealed that it contains an 849-bp open reading frame with a G + C content of 46.88% which encodes a 283-amino-acid protein with a calculated molecular mass of 31.297 kDa and a predicted pI of 9.065. A sequence comparison of flagellin proteins revealed that the amino acid sequence is most variable in the central portion of the serovar pomona FlaB, which is believed to contain specific sequence information and which may thus be useful in the design of DNA or synthetic peptide probes suitable for the detection of infection with pathogenic leptospires. PMID:9317049

  16. Profiling of Leptospira interrogans, L. santarosai, L. meyeri and L. borgpetersenii by SE-AFLP, PFGE and susceptibility testing—a continuous attempt at species and serovar differentiation

    PubMed Central

    Moreno, Luisa Z; Miraglia, Fabiana; Lilenbaum, Walter; Neto, José SF; Freitas, Julio C; Morais, Zenaide M; Hartskeerl, Rudy A; da Costa, Barbara LP; Vasconcellos, Silvio A; Moreno, Andrea M

    2016-01-01

    Leptospirosis is a widespread systemic zoonosis, considered as reemerging in certain developing countries. Although the cross agglutinin absorption test is still considered the standard method for Leptospira identification, it presents several disadvantages. The aim of this study was to characterize Leptospira spp. isolated from various hosts by genotyping and broth microdilution susceptibility testing in an attempt to differentiate Leptospira species, serogroups and serovars. Forty-seven isolates were studied. They were previously serotyped, and species confirmation was performed by 16S rRNA sequencing. Single-enzyme amplified fragment length polymorphism (SE-AFLP) and pulsed-field gel electrophoresis (PFGE) analysis enabled the distinction of L. interrogans from L. santarosai, L. meyeri and L. borgpetersenii in two main clusters. Among L. interrogans, it was possible to differentiate into two new clusters the serogroup Icterohaemorrhagiae from the serogroups Canicola and Pomona. L. santarosai isolates presented higher genetic variation than the other species in both techniques. Interestingly, the minimum inhibitory concentration (MIC) cluster analysis also provided Leptospira serogroup differentiation. Further studies are necessary regarding serovar Bananal isolates, as they presented the highest MIC values for most of the antimicrobials tested. All studied techniques successfully distinguished Leptospira species and serogroups. Despite being library-dependent methods, these approaches are less labor intensive and more economically viable, particularly SE-AFLP, and can be implemented in most reference laboratories worldwide to enable faster Leptospira typing. PMID:26956446

  17. Profiling of Leptospira interrogans, L. santarosai, L. meyeri and L. borgpetersenii by SE-AFLP, PFGE and susceptibility testing--a continuous attempt at species and serovar differentiation.

    PubMed

    Moreno, Luisa Z; Miraglia, Fabiana; Lilenbaum, Walter; Neto, José S F; Freitas, Julio C; Morais, Zenaide M; Hartskeerl, Rudy A; da Costa, Barbara L P; Vasconcellos, Silvio A; Moreno, Andrea M

    2016-01-01

    Leptospirosis is a widespread systemic zoonosis, considered as reemerging in certain developing countries. Although the cross agglutinin absorption test is still considered the standard method for Leptospira identification, it presents several disadvantages. The aim of this study was to characterize Leptospira spp. isolated from various hosts by genotyping and broth microdilution susceptibility testing in an attempt to differentiate Leptospira species, serogroups and serovars. Forty-seven isolates were studied. They were previously serotyped, and species confirmation was performed by 16S rRNA sequencing. Single-enzyme amplified fragment length polymorphism (SE-AFLP) and pulsed-field gel electrophoresis (PFGE) analysis enabled the distinction of L. interrogans from L. santarosai, L. meyeri and L. borgpetersenii in two main clusters. Among L. interrogans, it was possible to differentiate into two new clusters the serogroup Icterohaemorrhagiae from the serogroups Canicola and Pomona. L. santarosai isolates presented higher genetic variation than the other species in both techniques. Interestingly, the minimum inhibitory concentration (MIC) cluster analysis also provided Leptospira serogroup differentiation. Further studies are necessary regarding serovar Bananal isolates, as they presented the highest MIC values for most of the antimicrobials tested. All studied techniques successfully distinguished Leptospira species and serogroups. Despite being library-dependent methods, these approaches are less labor intensive and more economically viable, particularly SE-AFLP, and can be implemented in most reference laboratories worldwide to enable faster Leptospira typing. PMID:26956446

  18. Multiple-locus variable-number tandem repeat analysis (MLVA) of Leptospira interrogans serovar Pomona from Argentina reveals four new genotypes.

    PubMed

    Pavan, María Elisa; Cairó, Fabián; Brihuega, Bibiana; Samartino, Luis

    2008-01-01

    Outbreaks of leptospirosis occur regularly in Argentina, but little is known about their epidemiological relationships. We have analyzed the genetic diversity of a collection of 16 strains of Leptospira interrogans serovar Pomona isolated from animals and humans in Argentina during the past 45 years. Genotyping was performed by multiple-locus variable-number tandem repeat analysis (MLVA) using the loci VNTR4, VNTR7, VNTR9, VNTR10, VNTR19, VNTR23 and VNTR31, as described by Majed et al. [Identification of variable-number tandem-repeat loci in Leptospira interrogans sensu stricto. J Clin Microbiol 2005;43:539-45]. Clustering analysis revealed four new distinct MLVA genotypes, with a dominant one. Strains with this genotype were consistently isolated since 1960 to the present, mainly from cows and pigs, but also from humans, representing 75% of the total strains studied. These strains coexisted temporally and geographically with isolates presenting the other new genotypes. VNTR4 locus, with four different alleles, presented the highest diversity between the VNTR loci analyzed. MLVA patterns obtained will be useful for future diagnostic and epidemiological tracing analysis. PMID:17531318

  19. Effect of exposure to Neospora caninum, Salmonella, and Leptospira interrogans serovar Hardjo on the economic performance of Irish dairy herds.

    PubMed

    O' Doherty, E; Sayers, R; O' Grady, L; Shalloo, L

    2015-04-01

    The objective of the current study was to quantify the effects of exposure to Salmonella, Neospora caninum, and Leptospira interrogans serovar Hardjo (L. hardjo) on dairy farm profitability and to simulate the effect of vaccination for Salmonella and L. hardjo on dairy farm profitability. The production effects associated with exposure to each of these pathogens in study herds were defined under 3 categories: (1) milk production effects, (2) reproduction effects (including culling), and (3) mortality effects. The production effects associated with exposure to Salmonella, N. caninum, and L. hardjo were incorporated into the Moorepark Dairy Systems Model. In the analysis, herds negative for exposure to Salmonella, N. caninum, and L. hardjo were assumed baseline herds, with all results presented relative to this base. In simulations examining the effect of vaccination for Salmonella and L. hardjo on farm profitability, vaccinated herds (vaccination costs included) were considered as baseline herds and results were presented relative to this base. Total annual profits in unvaccinated herds were reduced by €77.31, €94.71, and €112.11 per cow at milk prices of €0.24, €0.29, and €0.34/L, respectively, as a result of exposure to Salmonella. In the current study, herds positive for exposure to Salmonella recorded a 316-kg reduction in milk yield, whereas no association was detected between exposure to N. caninum or L. hardjo and milk production. Exposure to both N. caninum and L. hardjo was associated with compromised reproductive performance. Herds positive for exposure to N. caninum and Salmonella had greater rates of adult cow mortality and calf mortality, respectively. Vaccination for both Salmonella and L. hardjo was associated with improved performance in study herds. Exposure to N. caninum resulted in a reduction in annual farm profits of €11.55, €12, and €12.44 per cow at each milk price, whereas exposure to L. hardjo resulted in a reduction in

  20. In Vivo-Expressed Proteins of Virulent Leptospira interrogans Serovar Autumnalis N2 Elicit Strong IgM Responses of Value in Conclusive Diagnosis

    PubMed Central

    Raja, Veerapandian; Shanmughapriya, Santhanam; Kanagavel, Murugesan; Artiushin, Sergey C.; Velineni, Sridhar; Timoney, John F.

    2015-01-01

    Leptospirosis is a serious zoonosis that is underdiagnosed because of limited access to laboratory facilities in Southeast Asia, Central and South America, and Oceania. Timely diagnosis of locally distributed serovars of high virulence is crucial for successful care and outbreak management. Using pooled patient sera, an expression gene library of a virulent Leptospira interrogans serovar Autumnalis strain N2 isolated in South India was screened. The identified genes were characterized, and the purified recombinant proteins were used as antigens in IgM enzyme-linked immunosorbent assay (ELISA) either singly or in combination. Sera (n = 118) from cases of acute leptospirosis along with sera (n = 58) from healthy subjects were tested for reactivity with the identified proteins in an ELISA designed to detect specific IgM responses. We have identified nine immunoreactive proteins, ArgC, RecA, GlpF, FliD, TrmD, RplS, RnhB, Lp28.6, and Lrr44.9, which were found to be highly conserved among pathogenic leptospires. Apparently, the proteins ArgC, RecA, GlpF, FliD, TrmD, and Lrr44.9 are expressed during natural infection of the host and undetectable in in vitro cultures. Among all the recombinant proteins used as antigens in IgM ELISA, ArgC had the highest sensitivity and specificity, 89.8% and 95.5%, respectively, for the conclusive diagnosis of leptospirosis. The use of ArgC and RecA in combination for IgM ELISA increased the sensitivity and specificity to 95.7% and 94.9%, respectively. ArgC and RecA thus elicited specific IgM responses and were therefore effective in laboratory confirmation of Leptospira infection. PMID:26607308

  1. In Vivo-Expressed Proteins of Virulent Leptospira interrogans Serovar Autumnalis N2 Elicit Strong IgM Responses of Value in Conclusive Diagnosis.

    PubMed

    Raja, Veerapandian; Shanmughapriya, Santhanam; Kanagavel, Murugesan; Artiushin, Sergey C; Velineni, Sridhar; Timoney, John F; Natarajaseenivasan, Kalimuthusamy

    2016-01-01

    Leptospirosis is a serious zoonosis that is underdiagnosed because of limited access to laboratory facilities in Southeast Asia, Central and South America, and Oceania. Timely diagnosis of locally distributed serovars of high virulence is crucial for successful care and outbreak management. Using pooled patient sera, an expression gene library of a virulent Leptospira interrogans serovar Autumnalis strain N2 isolated in South India was screened. The identified genes were characterized, and the purified recombinant proteins were used as antigens in IgM enzyme-linked immunosorbent assay (ELISA) either singly or in combination. Sera (n = 118) from cases of acute leptospirosis along with sera (n = 58) from healthy subjects were tested for reactivity with the identified proteins in an ELISA designed to detect specific IgM responses. We have identified nine immunoreactive proteins, ArgC, RecA, GlpF, FliD, TrmD, RplS, RnhB, Lp28.6, and Lrr44.9, which were found to be highly conserved among pathogenic leptospires. Apparently, the proteins ArgC, RecA, GlpF, FliD, TrmD, and Lrr44.9 are expressed during natural infection of the host and undetectable in in vitro cultures. Among all the recombinant proteins used as antigens in IgM ELISA, ArgC had the highest sensitivity and specificity, 89.8% and 95.5%, respectively, for the conclusive diagnosis of leptospirosis. The use of ArgC and RecA in combination for IgM ELISA increased the sensitivity and specificity to 95.7% and 94.9%, respectively. ArgC and RecA thus elicited specific IgM responses and were therefore effective in laboratory confirmation of Leptospira infection. PMID:26607308

  2. Detection of leptospiral antigen (L. interrogans serovar copenhageni serogroup Icterohaemorrhagiae) by immunoelectron microscopy in the liver and kidney of experimentally infected guinea-pigs.

    PubMed Central

    De Brito, T.; Prado, M. J.; Negreiros, V. A.; Nicastri, A. L.; Sakata, E. E.; Yasuda, P. H.; Santos, R. T.; Alves, V. A.

    1992-01-01

    Guinea-pigs were experimentally infected with L. interrogans serovar copenhageni serogroup Icterohaemorrhagiae and their liver and kidney were studied by immunoelectron microscopy using the post embedding indirect immunogold labelling technique. Primary antibody was a purified rabbit anti-serum produced against the same leptospiral strain used in the inoculum. Gold-labelled leptospiral antigen (LAg) was found close to cell membranes of hepatocytes, kidney tubular cells and endothelial cells of the interstitial capillaries of the kidney. Afterwards it was internalized by hepatic and tubular cells, and eventually found in lysosomes. Phagolysosomes of Kupffer cells were also found to contain remnants of degraded leptospires and gold-labelled LAg. Gold-labelled intact leptospires were detected at the enlarged intercellular spaces between hepatocytes at the areas of hepatic cell plate disarray, showing the potential for leptospiral migration during the septicaemic phase of the disease potentially contributing to the pathogenesis of the lesions. The affinity of leptospiral antigenic material for cell membranes suggests an initial interaction with cell surface proteins followed by its internalization and cell damage. The nature of antigenic material detected, however, remains undefined; it may be a toxin, an enzyme or any other factor/s involved in leptospiral virulence. Images Fig. 1 Fig. 2 Fig. 3 Fig. 4 Fig. 5 Fig. 6 Fig. 7 Fig. 8 PMID:1419779

  3. Identification of Seroreactive Proteins of Leptospira interrogans Serovar Copenhageni Using a High-Density Protein Microarray Approach

    PubMed Central

    Lessa-Aquino, Carolina; Borges Rodrigues, Camila; Pablo, Jozelyn; Sasaki, Rie; Jasinskas, Algis; Liang, Li; Wunder, Elsio A.; Ribeiro, Guilherme S.; Vigil, Adam; Galler, Ricardo; Molina, Douglas; Liang, Xiaowu; Reis, Mitermayer G.; Ko, Albert I.; Medeiros, Marco Alberto; Felgner, Philip L.

    2013-01-01

    Background Leptospirosis is a widespread zoonotic disease worldwide. The lack of an adequate laboratory test is a major barrier for diagnosis, especially during the early stages of illness, when antibiotic therapy is most effective. Therefore, there is a critical need for an efficient diagnostic test for this life threatening disease. Methodology In order to identify new targets that could be used as diagnostic makers for leptopirosis, we constructed a protein microarray chip comprising 61% of Leptospira interrogans proteome and investigated the IgG response from 274 individuals, including 80 acute-phase, 80 convalescent-phase patients and 114 healthy control subjects from regions with endemic, high endemic, and no endemic transmission of leptospirosis. A nitrocellulose line blot assay was performed to validate the accuracy of the protein microarray results. Principal findings We found 16 antigens that can discriminate between acute cases and healthy individuals from a region with high endemic transmission of leptospirosis, and 18 antigens that distinguish convalescent cases. Some of the antigens identified in this study, such as LipL32, the non-identical domains of the Lig proteins, GroEL, and Loa22 are already known to be recognized by sera from human patients, thus serving as proof-of-concept for the serodiagnostic antigen discovery approach. Several novel antigens were identified, including the hypothetical protein LIC10215 which showed good sensitivity and specificity rates for both acute- and convalescent-phase patients. Conclusions Our study is the first large-scale evaluation of immunodominant antigens associated with naturally acquired leptospiral infection, and novel as well as known serodiagnostic leptospiral antigens that are recognized by antibodies in the sera of leptospirosis cases were identified. The novel antigens identified here may have potential use in both the development of new tests and the improvement of currently available assays for

  4. Complete Genome Sequences of Low-Passage Virulent and High-Passage Avirulent Variants of Pathogenic Leptospira interrogans Serovar Manilae Strain UP-MMC-NIID, Originally Isolated from a Patient with Severe Leptospirosis, Determined Using PacBio Single-Molecule Real-Time Technology.

    PubMed

    Satou, Kazuhito; Shimoji, Makiko; Tamotsu, Hinako; Juan, Ayaka; Ashimine, Noriko; Shinzato, Misuzu; Toma, Claudia; Nohara, Toshitsugu; Shiroma, Akino; Nakano, Kazuma; Teruya, Kuniko; Terabayashi, Yasunobu; Ohki, Shun; Koizumi, Nobuo; Okano, Shou; Suzuki, Toshihiko; Hirano, Takashi

    2015-01-01

    Here, we report the complete genome sequences of low-passage virulent and high-passage avirulent variants of pathogenic Leptospira interrogans serovar Manilae strain UP-MMC-NIID, a major causative agent of leptospirosis. While there were no major differences between the genome sequences, the levels of base modifications were higher in the avirulent variant. PMID:26272567

  5. Complete Genome Sequences of Low-Passage Virulent and High-Passage Avirulent Variants of Pathogenic Leptospira interrogans Serovar Manilae Strain UP-MMC-NIID, Originally Isolated from a Patient with Severe Leptospirosis, Determined Using PacBio Single-Molecule Real-Time Technology

    PubMed Central

    Shimoji, Makiko; Tamotsu, Hinako; Juan, Ayaka; Ashimine, Noriko; Shinzato, Misuzu; Toma, Claudia; Nohara, Toshitsugu; Shiroma, Akino; Nakano, Kazuma; Teruya, Kuniko; Terabayashi, Yasunobu; Ohki, Shun; Koizumi, Nobuo; Okano, Shou; Suzuki, Toshihiko; Hirano, Takashi

    2015-01-01

    Here, we report the complete genome sequences of low-passage virulent and high-passage avirulent variants of pathogenic Leptospira interrogans serovar Manilae strain UP-MMC-NIID, a major causative agent of leptospirosis. While there were no major differences between the genome sequences, the levels of base modifications were higher in the avirulent variant. PMID:26272567

  6. Safety and efficacy of a new octavalent combined Erysipelas, Parvo and Leptospira vaccine in gilts against Leptospira interrogans serovar Pomona associated disease and foetal death.

    PubMed

    Jacobs, A A C; Harks, F; Hoeijmakers, M; Collell, M; Segers, R P A M

    2015-07-31

    The safety and protective efficacy of a new octavalent combination vaccine containing inactivated Erysipelothrix rhusiopathiae, Parvovirus, and Leptospira interrogans (sensu lato) serogroups Canicola, Icterohaemorrhagiae, Australis (Bratislava), Grippotyphosa, Pomona and Tarassovi - Porcilis(®) Ery+Parvo+Lepto - was evaluated in laboratory studies and under field conditions. The safety (2× overdose and repeated dose) was tested in 26 gilts. In this study, neither vaccine related temperature increase nor other systemic reactions were observed after intramuscular vaccination. No local reactions were observed except for one animal that had a small local reaction (2cm diameter) that lasted for 5 days after the third vaccination. Efficacy was tested in 40 gilts. A group of 20 gilts was vaccinated at 20 and 24 weeks of age with Porcilis(®) Ery+Parvo+Lepto and a group of 20 age- and source-matched animals served as the control group. The gilts were inseminated at 41 weeks or 66 weeks of age and were challenged with serovar Pomona 10 weeks after insemination, corresponding to 6 months (n=2×10) and 12 months (n=2×10) after the last vaccination. After both the 6- and 12-month challenges the control animals developed clinical signs (fever, lethargy and anorexia) and leptospiraemia as determined by positive blood culture. In addition, both the 6- and 12-month challenges resulted in death of 21% and 27% of the total number of foetuses in the control groups, respectively. Clinical signs and leptospiraemia were statistically significantly lower in vaccinated gilts after both the 6- and 12-month challenges. In addition, foetal death was statistically significantly lower (3% and 2%, respectively) in vaccinated gilts after both the 6- and 12 month challenges. The vaccine was tested further under field conditions on a Portuguese farm with a history of an increasing abortion rate associated with a Leptospira serovar Pomona infection (confirmed by PCR and serology). This study was

  7. Detection of human leptospirosis as a cause of acute fever by capture ELISA using a Leptospira interrogans serovar Copenhageni (M20) derived antigen

    PubMed Central

    2013-01-01

    Background Leptospirosis is a potentially lethal zoonosis mainly affecting low-resource tropical countries, including Peru and its neighbouring countries. Timely diagnosis of leptospirosis is critical but may be challenging in the regions where it is most prevalent. The serodiagnostic gold standard microagglutination test (MAT) may be technically prohibitive. Our objective in this study was to assess the sensitivity, specificity, and predictive value of an IgM antibody capture enzyme-linked immunoassay (MAC-ELISA) derived from the M20 strain of Leptospira interrogans serovar Copenhageni (M20) by comparison to MAT, which was used as the gold standard method of diagnosis. Methods Acute and convalescent sera from participants participating in a passive febrile surveillance study in multiple regions of Peru were tested by both IgM MAC-ELISA and MAT. The sensitivity, specificity, positive and negative predictive value (PPV, NPV) of the MAC-ELISA assay for acute, convalescent and paired sera by comparison to MAT were calculated. Results The sensitivity, specificity, PPV and NPV of the MAC-ELISA assay for acute sera were 92.3%, 56.0%, 35.3% and 96.6% respectively. For convalescent sera, the sensitivity, specificity, PPV and NPV of the MAC-ELISA assay were 93.3%, 51.5%, 63.6% and 89.5% respectively. For paired sera, the sensitivity, specificity, PPV and NPV of the MAC-ELISA assay were 93.6%, 37.5%, 59.2%, 85.7% respectively. Conclusions The M20 MAC-ELISA assay performed with a high sensitivity and low specificity in the acute phase of illness. Sensitivity was similar as compared with MAT in the convalescent phase and specificity remained low. Paired sera were the most sensitive but least specific by comparison to MAT serodiagnosis. NPV for acute, convalescent and paired sera was high. The limited specificity and high sensitivity of the MAC-ELISA IgM suggests that it would be most valuable to exclude leptospirosis in low-resource regions that lack immediate access to

  8. Physical and genetic maps of the Leptospira interrogans serovar icterohaemorrhagiae strain Ictero no.1 chromosome and sequencing of a 19-kb region of the genome containing the 5S rRNA gene.

    PubMed

    Takahashi, Y; Akase, K; Hirano, H; Fukunaga, M

    1998-07-17

    We report the construction of physical and genetic maps of the chromosome of Leptospira interrogans serovar icterohaemorrhagiae strain Ictero No.1 using pulsed-field gel electrophoresis of DNA fragments generated by digestion with enzymes SrfI, AscI, FseI, and NotI and using reciprocal hybridization. We also sequenced the 19-kilobase (kb) DNA segment including the one gene for 5S rRNA (rrf) of pathogenic Leptospira. The size of the chromosome of the strain Ictero No.1 was estimated to be 4673kb and was found to be similar to those of the chromosomes of the leptospira strains Verdun (serovar icterohaemorrhagiae) and RZ11 (serovar pomona). The strains Verdun and RZ11 carry a small 350-kb replicon (minichromosome), and the strain Ictero No.1 also contained the same kind of molecule together with the chromosome. The physical maps of the strains Ictero No.1 and Verdun were almost identical, as were the locations of the selected genes, except for the location of one of the 16S rRNA genes. Overall, the genetic organization appeared to be conserved within the serovar icterohaemorrhagiae strains. In the sequenced region, we identified 10 putative ORFs and one rrf sequence, and the transcription orientations were all the same. A homology search for the products deduced from the sequenced data revealed that the orf H exhibited high similarity to malic acid enzyme of Haemophilus influenzae and fumarate hydratase of Escherichia coli (orf J). The rest of the putative products encoded by ORFs in the sequenced region showed little similarity with the proteins contained in the databases and were considered to be unknown proteins. PMID:9666070

  9. Global Proteome Analysis of Leptospira interrogans

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Comparative global proteome analyses were performed on Leptospira interrogans serovar Copenhageni grown under conventional in vitro conditions and those mimicking in vivo conditions (iron limitation and serum presence). Proteomic analyses were conducted using iTRAQ and LC-ESI-tandem mass spectrometr...

  10. A Model System for Studying the Transcriptomic and Physiological Changes Associated with Mammalian Host-Adaptation by Leptospira interrogans Serovar Copenhageni

    PubMed Central

    Caimano, Melissa J.; Sivasankaran, Sathesh K.; Allard, Anna; Hurley, Daniel; Hokamp, Karsten; Grassmann, André A.; Hinton, Jay C. D.; Nally, Jarlath E.

    2014-01-01

    Leptospirosis, an emerging zoonotic disease with worldwide distribution, is caused by spirochetes belonging to the genus Leptospira. More than 500,000 cases of severe leptospirosis are reported annually, with >10% of these being fatal. Leptospires can survive for weeks in suitably moist conditions before encountering a new host. Reservoir hosts, typically rodents, exhibit little to no signs of disease but shed large numbers of organisms in their urine. Transmission occurs when mucosal surfaces or abraded skin come into contact with infected urine or urine-contaminated water or soil. In humans, leptospires can cause a variety of clinical manifestations, ranging from asymptomatic or mild fever to severe icteric (Weil's) disease and pulmonary haemorrhage. Currently, little is known about how Leptospira persist within a reservoir host. Prior in vitro studies have suggested that leptospires alter their transcriptomic and proteomic profiles in response to environmental signals encountered during mammalian infection. However, no study has examined gene expression by leptospires within a mammalian host-adapted state. To obtain a more faithful representation of how leptospires respond to host-derived signals, we used RNA-Seq to compare the transcriptome of L. interrogans cultivated within dialysis membrane chambers (DMCs) implanted into the peritoneal cavities of rats with that of organisms grown in vitro. In addition to determining the relative expression levels of “core” housekeeping genes under both growth conditions, we identified 166 genes that are differentially-expressed by L. interrogans in vivo. Our analyses highlight physiological aspects of host adaptation by leptospires relating to heme uptake and utilization. We also identified 11 novel non-coding transcripts that are candidate small regulatory RNAs. The DMC model provides a facile system for studying the transcriptional and antigenic changes associated with mammalian host-adaption, selection of targets for

  11. Pathogenomic Inference of Virulence-Associated Genes in Leptospira interrogans

    PubMed Central

    Lehmann, Jason S.; Fouts, Derrick E.; Haft, Daniel H.; Cannella, Anthony P.; Ricaldi, Jessica N.; Brinkac, Lauren; Harkins, Derek; Durkin, Scott; Sanka, Ravi; Sutton, Granger; Moreno, Angelo; Vinetz, Joseph M.; Matthias, Michael A.

    2013-01-01

    Leptospirosis is a globally important, neglected zoonotic infection caused by spirochetes of the genus Leptospira. Since genetic transformation remains technically limited for pathogenic Leptospira, a systems biology pathogenomic approach was used to infer leptospiral virulence genes by whole genome comparison of culture-attenuated Leptospira interrogans serovar Lai with its virulent, isogenic parent. Among the 11 pathogen-specific protein-coding genes in which non-synonymous mutations were found, a putative soluble adenylate cyclase with host cell cAMP-elevating activity, and two members of a previously unstudied ∼15 member paralogous gene family of unknown function were identified. This gene family was also uniquely found in the alpha-proteobacteria Bartonella bacilliformis and Bartonella australis that are geographically restricted to the Andes and Australia, respectively. How the pathogenic Leptospira and these two Bartonella species came to share this expanded gene family remains an evolutionary mystery. In vivo expression analyses demonstrated up-regulation of 10/11 Leptospira genes identified in the attenuation screen, and profound in vivo, tissue-specific up-regulation by members of the paralogous gene family, suggesting a direct role in virulence and host-pathogen interactions. The pathogenomic experimental design here is generalizable as a functional systems biology approach to studying bacterial pathogenesis and virulence and should encourage similar experimental studies of other pathogens. PMID:24098822

  12. Antibodies against Leptospira interrogans in California sea lion pups from Gulf of California.

    PubMed

    Godínez, C R; Zelaya de Romillo, B; Aurioles-Gamboa, D; Verdugo-Rodríguez, A; Rodríguez-Reyes, E A; De la Peña-Moctezuma, A

    1999-01-01

    One hundred and twenty-five serum samples from California sea lion (Zalophus californianus californianus) pups, and one from an adult female from eight reproductive rookeries located in seven islands in the Gulf of California (Mexico), were collected during the 1994-96 reproductive seasons. These were tested for antibodies to 19 serovars of Leptospira interrogans using a Microscopic Agglutination Test (MAT). Forty-one samples (32%) had antibody levels from 1:20 to 1:320 to one or more serovars. The most frequently detected serotypes were Leptospira interrogans hardjo (n = 13), cynopteri (8), ballum (6), and szwajizak (5). Serovars with the highest prevalence were Leptospira interrogans hardjo and serjoe (1:320), ballum (1:160), and cynopteri, girppotyphosa, and tarassovi (1:80). Based on these results, exposure of sea lions to L. interrogans serovar hardjo seems to be relatively common among colonies located in the islands of the Gulf of California in contrast with those located on the Pacific coast, where the most frequently detected serovar is L. interrogans serovar pomona. PMID:10073358

  13. High-Resolution Typing of Leptospira interrogans Strains by Multispacer Sequence Typing

    PubMed Central

    Zilber, Anne-Laure; Picardeau, Mathieu; Ayral, Florence; Artois, Marc; Demont, Pierre; Kodjo, Angeli

    2014-01-01

    Leptospirosis is a worldwide zoonosis which is responsible for the typical form of Weil's disease. The epidemiological surveillance of the Leptospira species agent is important for host prevalence control. Although the genotyping methods have progressed, the identification of some serovars remains ambiguous. We investigated the multispacer sequence typing (MST) method for genotyping strains belonging to the species Leptospira interrogans, which is the main agent of leptospirosis worldwide. A total of 33 DNA samples isolated from the reference strains of L. interrogans serogroups Icterohaemorrhagiae, Australis, Canicola, and Grippotyphosa, which are the most prevalent serogroups in France, were analyzed by both the variable-number tandem-repeat (VNTR) and MST methods. An MST database has been constructed from the DNA of these reference strains to define the MST profiles. The MST profiles corroborated with the VNTR results. Moreover, the MST analysis allowed the identification at the serovar level or potentially to the isolate level for strains belonging to L. interrogans serovar Icterohaemorrhagiae, which then results in a higher resolution than VNTR (Hunter-Gaston index of 0.94 versus 0.68). Regarding L. interrogans serogroups Australis, Canicola, and Grippotyphosa, the MST and VNTR methods similarly identified the genotype. The MST method enabled the acquisition of simple and robust results that were based on the nucleotide sequences. The MST identified clinical isolates in correlation with the reference serovar profiles, thus permitting an epidemiological surveillance of circulating L. interrogans strains, especially for the Icterohaemorrhagiae serogroup, which includes the most prevalent strains of public health interest. PMID:24478489

  14. Role of sph2 Gene Regulation in Hemolytic and Sphingomyelinase Activities Produced by Leptospira interrogans

    PubMed Central

    Narayanavari, Suneel A.; Lourdault, Kristel; Sritharan, Manjula; Haake, David A.; Matsunaga, James

    2015-01-01

    Pathogenic members of the genus Leptospira are the causative agents of leptospirosis, a neglected disease of public and veterinary health concern. Leptospirosis is a systemic disease that in its severest forms leads to renal insufficiency, hepatic dysfunction, and pulmonary failure. Many strains of Leptospira produce hemolytic and sphingomyelinase activities, and a number of candidate leptospiral hemolysins have been identified based on sequence similarity to well-characterized bacterial hemolysins. Five of the putative hemolysins are sphingomyelinase paralogs. Although recombinant forms of the sphingomyelinase Sph2 and other hemolysins lyse erythrocytes, none have been demonstrated to contribute to the hemolytic activity secreted by leptospiral cells. In this study, we examined the regulation of sph2 and its relationship to hemolytic and sphingomyelinase activities produced by several L. interrogans strains cultivated under the osmotic conditions found in the mammalian host. The sph2 gene was poorly expressed when the Fiocruz L1-130 (serovar Copenhageni), 56601 (sv. Lai), and L495 (sv. Manilae) strains were cultivated in the standard culture medium EMJH. Raising EMJH osmolarity to physiological levels with sodium chloride enhanced Sph2 production in all three strains. In addition, the Pomona subtype kennewicki strain LC82-25 produced substantially greater amounts of Sph2 during standard EMJH growth than the other strains, and sph2 expression increased further by addition of salt. When 10% rat serum was present in EMJH along with the sodium chloride supplement, Sph2 production increased further in all strains. Osmotic regulation and differences in basal Sph2 production in the Manilae L495 and Pomona strains correlated with the levels of secreted hemolysin and sphingomyelinase activities. Finally, a transposon insertion in sph2 dramatically reduced hemolytic and sphingomyelinase activities during incubation of L. interrogans at physiologic osmolarity

  15. Isolation and Molecular Characterization of Leptospira interrogans and Leptospira borgpetersenii Isolates from the Urban Rat Populations of Kuala Lumpur, Malaysia

    PubMed Central

    Benacer, Douadi; Zain, Siti Nursheena Mohd; Amran, Fairuz; Galloway, Renee L.; Thong, Kwai Lin

    2013-01-01

    Rats are considered the principal maintenance hosts of Leptospira. The objectives of this study were isolation and identification of Leptospira serovars circulating among urban rat populations in Kuala Lumpur. Three hundred urban rats (73% Rattus rattus and 27% R. norvegicus) from three different sites were trapped. Twenty cultures were positive for Leptospira using dark-field microscopy. R. rattus was the dominant carrier (70%). Polymerase chain reaction (PCR) confirmed that all isolates were pathogenic Leptospira species. Two Leptospira serogroups, Javanica and Bataviae, were identified using microscopic agglutination test (MAT). Pulsed-field gel electrophoresis (PFGE) identified two serovars in the urban rat populations: L. borgpetersenii serovar Javanica (85%) and L. interrogans serovar Bataviae (15%). We conclude that these two serovars are the major serovars circulating among the urban rat populations in Kuala Lumpur. Despite the low infection rate reported, the high pathogenicity of these serovars raises concern of public health risks caused by rodent transmission of leptospirosis. PMID:23358635

  16. A comparative analysis of the attachment of Leptospira interrogans and L. borgpetersenii to mammalian cells.

    PubMed

    Andrade, Gabrielle I; Brown, Paul D

    2012-06-01

    Leptospirosis, the world's most ubiquitous zoonosis, is caused by pathogenic Leptospira. As microbe-host interactions are specific in pathogenesis, it is likely that there are several molecules mediating the attachment of the Leptospira to mammalian cells. In this study, we analysed the attachment of Leptospira interrogans serovar Portlandvere and Leptospira borgpetersenii serovar Jules to untreated HEp-2 cells or HEp-2 cells treated with the various enzymes, lectins or sugars and to integrins αVβ3 and α5β1, relative to control wells. We found that both serovars bound equally well to HEp-2 cells; however, serovar Jules showed a higher level of attachment to integrins. Both serovars showed an increase in attachment to HEp-2 cells coated with lectins peanut agglutinin, Ulex europaeus agglutinin, soybean agglutinin and Erythrina cristagalli agglutinin (p < 0.05); in the case of Concanavalin A, Jules showed an increase, while Portlandvere showed a significant decrease in attachment. Trypsinizing monolayers resulted in a decrease in attachment for both serovars, while when chondroitinase, neuraminidase and heparinase were used an increase in attachment was recorded. Leptospires coated with sugars showed a decrease in attachment. These results show that serovar Jules' general greater affinity for the mediators examined may suggest a greater potential for virulence over serovar Portlandvere. PMID:22409511

  17. Seroprevalence and risk factors associated with within-flock transmission of Leptospira interrogans in transhumant farming systems in Mexico.

    PubMed

    Arteaga-Troncoso, G; Jiménez-Estrada, J M; Montes De Oca-Jimenez, R; López-Hurtado, M; Luna-Alvarez, M; Hernandez-Andrade, L; Moreno-Alfaro, A; Galan-Herrera, J F; Guerra-Infante, F M

    2015-10-01

    A number of recent reports emphasize the risk of zoonotic diseases and the high degree of prevalence of asymptomatic animals infected with Leptospira interrogans. This report sought to assess the prevalence of antibodies to certain serovars of L. interrogans, and to describe the association between seropositivity and risk factors associated with within-flock transmission in a mountainous region of Mexico. Overall seroprevalence to L. interrogans was 54·5% (95% confidence interval 48·3-60·7); the most frequent serovar was Icterohaemorrhagiae. The accumulation of placentas and fetuses at a site close to lambing paddocks can play a significant role as a risk factor for within-flock transmission of L. interrogans in transhumant farming systems in the municipality of Xalatlaco. The high prevalence of L. interrogans antibodies supports the hypothesis that natural foci of this zoonosis are present in sheep flocks in this area. These findings emphasize the need for planning and implementation of control programmes for ovine leptospirosis in Mexico and elsewhere. PMID:25600318

  18. Evidence of Leptospira interrogans infection in California sea lion pups from the Gulf of California.

    PubMed

    Acevedo-Whitehouse, Karina; de la Cueva, Horacio; Gulland, Frances M D; Aurioles-Gamboa, David; Arellano-Carbajal, Fausto; Suarez-Güemes, Francisco

    2003-01-01

    Forty-two urine and 96 blood and serum samples were obtained from California sea lion (Zalophus californianus) pups from the Gulf of California during the 2000 reproductive season. Antibody prevalence to 13 serovars of Leptospira interrogans was determined by microagglutination tests (MAT); presence of pathogenic leptospires was detected by polymerase chain reaction (PCR). Samples with antibody titers > or = 1:25 or 115 bp fragments on ethidium bromidestained 1.5% agarose gels were considered positive. Antibody prevalence was 54% overall with highest prevalence against serovar cynopteri (50% of all positive reactions). Highest antibody titers (1:50) were detected against serovars cynopteri and pomona. Polymerase chain reaction products were observed in two of 42 urine samples, six of 96 blood samples, and one of 96 serum samples. Presence of PCR products in blood and serum was demonstrated in pups that were seronegative. Kruskall-Wallis tests and corresponding post hoc Tukey tests (alpha = 0.05) showed that prevalence of leptospirosis was significantly different among all rookeries. The high seroprevalence (54%), low antibody titers (maximum 1:50), absence of pups showing clinical signs indicative of the disease, and lack of recent reports of increased mortality of sea lions in the Gulf of California are suggestive of the presence of enzootic host-adapted serovars. Crowding in rookeries as well as the presence of bats and rodents on some of the islands may explain infection by L. interrogans (sensu lato) and some of the differences in seroprevalence among reproductive rookeries. PMID:12685078

  19. Prevalence of Leptospira interrogans antibodies in free-ranging Tayassu pecari of the Southern Pantanal, Brazil, an ecosystem where wildlife and cattle interact.

    PubMed

    de Freitas, Tatiana P Tavares; Keuroghlian, Alexine; Eaton, Donald P; de Freitas, Emanuel Barbosa; Figueiredo, Aline; Nakazato, Luciano; de Oliveira, Jacqueline M; Miranda, Flávia; Paes, Rita Cassia S; Monteiro, Leticia A R Carneiro; Lima, José Vergílio B; da C Neto, Aparecida A; Dutra, Valéria; de Freitas, Julio Cesar

    2010-12-01

    We surveyed a wild population of white-lipped peccaries (Tayassu pecari) in the Brazilian Pantanal for evidence of Leptospira interrogans. Serum samples from 71 free-ranging T. pecari were obtained between 2003 and 2005 in the southern Pantanal of Mato Grosso do Sul state. We used microscopic microagglutination to test for antibodies against 14 L. interrogans serovars (antibody titers ≥ 1:100 were considered seropositive). Seventy percent of captured animals tested positive for leptospirosis antibodies. Antibodies against icterohaemorrhagiae and autumnalis serovars were the most prevalent. We used log-linear analyses to test for associations among seropositivity, age class, and sex of captured animals. Seropositivity was strongly associated with animal age class, but independent of sex. Forty-six percent of animals less than 2 years old, 63% of adults during peak reproductive years, and 100% of the oldest age class were seropositive. A nonparametric multivariate procedure (MRPP) showed that the composition of serovar antibody types changed with age, and ANOVA models demonstrated that antibody titers increased with age, suggesting long-term exposure to a greater number and variety (i.e., serovar types) of L. interrogans infections. This study presents the first quantitative survey of antibodies against L. interrogans serovars in a T. pecari population of the Pantanal. The high prevalence of leptospirosis antibodies in free-ranging white-lipped peccaries and the potential impacts on reproduction and population dynamics emphasize the need for further studies investigating the roles of Pantanal wildlife and livestock in the transmission and maintenance of L. interrogans in the environment. PMID:20596776

  20. Temperature-Regulated Protein Synthesis by Leptospira interrogans

    PubMed Central

    Nally, Jarlath E.; Timoney, John F.; Stevenson, Brian

    2001-01-01

    Leptospira interrogans is an important mammalian pathogen. Transmission from an environmental source requires adaptations to a range of new environmental conditions in the organs and tissues of the infected host. Since many pathogenic bacteria utilize temperature to discern their environment and regulate the synthesis of appropriate proteins, we investigated the effects of temperature on protein synthesis in L. interrogans. Bacteria were grown for several days after culture temperatures were shifted from 30 to 37°C. Triton X-114 cellular fractionation identified several proteins of the cytoplasm, periplasm, and outer membrane for which synthesis was dependent on the culture temperature. Synthesis of a cytoplasmic protein of 20 kDa was switched off at 37°C, whereas synthesis of a 66-kDa periplasmic protein was increased at the higher temperature. Increased synthesis of a 25-kDa outer membrane protein was observed when the organisms were shifted from 30 to 37°C. A 36-kDa protein synthesized at 30 but not at 37°C was identified as LipL36, an outer membrane lipoprotein. In contrast, expression of another lipoprotein, LipL41, was the same at either temperature. Immunoblotting with convalescent equine sera revealed that some proteins exhibiting thermoregulation of synthesis elicited antibody responses during infection. Our results show that sera from horses which aborted as a result of naturally acquired infection with L. interrogans serovar pomona type kennewicki recognize periplasmic and outer membrane proteins which are differentially synthesized in response to temperature and which therefore may be important in the host-pathogen interaction during infection. PMID:11119530

  1. First isolation of Leptospira interrogans from Lycalopex griseus (South American gray fox) in Argentina shows new MLVA genotype.

    PubMed

    Scialfa, Exequiel; Brihuega, Bibiana; Venzano, Agustín; Morris, Winston Eduardo; Bolpe, Jorge; Schettino, Mateo

    2013-01-01

    To identify carriers of Leptospira spp. in Argentina, wild animals were trapped in Buenos Aires Province during three nights, capturing 12 Didelphis albiventris (white-eared opossum), six Chaetophractus villosus (big hairy armadillo), five Lycalopex griseus (South American gray fox), and two Conepatus chinga (Molina's hog-nosed skunk). All were tested by microscopic agglutination test, and five (two gray foxes, two armadillos, and one skunk) were positive for Leptospira interrogans serovars Canicola and Icterohaemorrhagiae, L. borgpetersenii serovar Castellonis, and L. kirschneri serovar Grippotyphosa, at titers of 1:50 and 1:100. Kidney tissue from all animals was cultured, and one isolate of L. interrogans from a gray fox was obtained. Hamsters inoculated with the isolate died after 6 days with no macroscopic lesions at necropsy. However, histologic examination revealed glomerulonephritis, interstitial nephritis, and pneumonia. The Leptospira strain from the South American gray fox was analyzed serologically and its pathogenicity was established. Genotyping through multiple-locus variable-number tandem repeat analysis showed that the strain was a new genotype related to the L. interrogans serogroup Icterohaemorrhagiae. PMID:23307384

  2. Mouse model for sublethal Leptospira interrogans infection.

    PubMed

    Richer, Luciana; Potula, Hari-Hara; Melo, Rita; Vieira, Ana; Gomes-Solecki, Maria

    2015-12-01

    Although Leptospira can infect a wide range of mammalian species, most studies have been conducted in golden Syrian hamsters, a species particularly sensitive to acute disease. Chronic disease has been well characterized in the rat, one of the natural reservoir hosts. Studies in another asymptomatic reservoir host, the mouse, have occasionally been done and have limited infection to mice younger than 6 weeks of age. We analyzed the outcome of sublethal infection of C3H/HeJ mice older than age 10 weeks with Leptospira interrogans serovar Copenhageni. Infection led to bloodstream dissemination of Leptospira, which was followed by urinary shedding, body weight loss, hypothermia, and colonization of the kidney by live spirochetes 2 weeks after infection. In addition, Leptospira dissemination triggered inflammation in the kidney but not in the liver or lung, as determined by increased levels of mRNA transcripts for the keratinocyte-derived chemokine, RANTES, macrophage inflammatory protein 2, tumor necrosis factor alpha, interleukin-1β, inducible nitric oxide synthase, interleukin-6, and gamma interferon in kidney tissue. The acquired humoral response to Leptospira infection led to the production of IgG mainly of the IgG1 subtype. Flow cytometric analysis of splenocytes from infected mice revealed that cellular expansion was primarily due to an increase in the levels of CD4(+) and double-negative T cells (not CD8(+) cells) and that CD4(+) T cells acquired a CD44(high) CD62L(low) effector phenotype not accompanied by increases in memory T cells. A mouse model for sublethal Leptospira infection allows understanding of the bacterial and host factors that lead to immune evasion, which can result in acute or chronic disease or resistance to infection (protection). PMID:26416909

  3. Mouse Model for Sublethal Leptospira interrogans Infection

    PubMed Central

    Richer, Luciana; Potula, Hari-Hara; Melo, Rita; Vieira, Ana

    2015-01-01

    Although Leptospira can infect a wide range of mammalian species, most studies have been conducted in golden Syrian hamsters, a species particularly sensitive to acute disease. Chronic disease has been well characterized in the rat, one of the natural reservoir hosts. Studies in another asymptomatic reservoir host, the mouse, have occasionally been done and have limited infection to mice younger than 6 weeks of age. We analyzed the outcome of sublethal infection of C3H/HeJ mice older than age 10 weeks with Leptospira interrogans serovar Copenhageni. Infection led to bloodstream dissemination of Leptospira, which was followed by urinary shedding, body weight loss, hypothermia, and colonization of the kidney by live spirochetes 2 weeks after infection. In addition, Leptospira dissemination triggered inflammation in the kidney but not in the liver or lung, as determined by increased levels of mRNA transcripts for the keratinocyte-derived chemokine, RANTES, macrophage inflammatory protein 2, tumor necrosis factor alpha, interleukin-1β, inducible nitric oxide synthase, interleukin-6, and gamma interferon in kidney tissue. The acquired humoral response to Leptospira infection led to the production of IgG mainly of the IgG1 subtype. Flow cytometric analysis of splenocytes from infected mice revealed that cellular expansion was primarily due to an increase in the levels of CD4+ and double-negative T cells (not CD8+ cells) and that CD4+ T cells acquired a CD44high CD62Llow effector phenotype not accompanied by increases in memory T cells. A mouse model for sublethal Leptospira infection allows understanding of the bacterial and host factors that lead to immune evasion, which can result in acute or chronic disease or resistance to infection (protection). PMID:26416909

  4. Phenotypic and Molecular Characterization of Leptospira interrogans Isolated from Canis familiaris in Southern Brazil.

    PubMed

    Jorge, Sérgio; Monte, Leonardo G; De Oliveira, Natasha R; Collares, Thais F; Roloff, Bárbara C; Gomes, Charles K; Hartwig, Daiane D; Dellagostin, Odir A; Hartleben, Cláudia P

    2015-10-01

    Leptospirosis is a zoonotic disease caused by pathogenic spirochetes from the genus Leptospira, which includes 20 species and more than 300 serovars. Canines are important hosts of pathogenic leptospires and can transmit the pathogen to humans via infected urine. Here, we report the phenotypic and molecular characterization of Leptospira interrogans isolated from Canis familiaris in Southern Brazil. The isolated strain was characterized by variable-number tandem-repeats analysis as L. interrogans, serogroup Icterohaemorrhagiae. In addition, the isolate was recognized by antibodies from human and canine serum samples previously tested by microscopic agglutination test. Ultimately, the expression of membrane-associated antigens (LipL32 and leptospiral immunoglobulin-like proteins) from pathogenic leptospires using monoclonal antibodies was detected by indirect immunofluorescence assay. In conclusion, identification of new strains of Leptospira can help in the diagnosis and control of leptospirosis. PMID:26100241

  5. Seasonal prevalence of antibodies to Leptospira interrogans in Antillean manatees from a landlocked lake in Tabasco, Mexico.

    PubMed

    Aragón-Martínez, Arianna; Olivera-Gómez, León D; Jiménez-Domínguez, Darwin

    2014-07-01

    Factors that alter the dynamics of ecologic systems can influence transmission of infectious diseases and may lead to decreases in natural populations. Leptospirosis is a cosmopolitan disease of zoonotic importance that affects most mammals. At the southern Gulf of Mexico, Antillean manatees (Trichechus manatus manatus) inhabit highly variable environments, with extended floods during the rainy season and drought conditions during the dry season that affect food availability and the thermal environment for manatees. We tested for changes in prevalence and titers of antibodies to 12 serovars of Leptospira interrogans in manatees between dry and rainy seasons. We determined titers for L. interrogans through microscopic agglutination tests (MAT) from 10 manatees, six during the dry season (DS), and six during the rainy season (RS) in Laguna de las Ilusiones, a landlocked lake hosting a population of about 20 manatees. All individuals were antibody positive (titers ≥ 100) to at least one serovar. The serovars bataviae, bratislava, canicola, and icterohaemorrhagiae had overall prevalences ≥ 50%; bataviae, bratislava, and canicola had prevalences ≥ 50% during both seasons. Serovars icterohaemorrhagiae and pyrogenes had prevalences ≥ 50% during DS and pomona, tarassovi, wolfii, and autumnalis during RS. Significant differences in prevalence between seasons were found for pomona, tarassovi, and autumnalis. Titers of tarassovi, wolfii, autumnalis, and bataviae were significantly higher during RS. There was a high prevalence of L. interrogans during the RS independent of high availability of plant foods, coinciding with the epizootiology of the bacteria that are endemic to tropical regions. Another factor possibly influencing prevalence is high anthropogenic pressure at the lake, causing an increase in potential sources of infection. Because of possible cross-reaction in MAT, further research is needed on the molecular discrimination of serovars in animals in the

  6. A Methylated Phosphate Group and Four Amide-linked Acyl Chains in Leptospira interrogans Lipid A. The Membrane Anchor of an Unusual Lipopolysaccharide that Activates TLR2*

    PubMed Central

    Que-Gewirth, Nanette L. S.; Ribeiro, Anthony A.; Kalb, Suzanne R.; Cotter, Robert J.; Bulach, Dieter M.; Adler, Ben; Girons, Isabelle Saint; Werts, Catherine; Raetz, Christian R. H.

    2008-01-01

    Leptospira interrogans differs from other spirochetes in that it contains homologs of all the Escherichia coli lpx genes required for the biosynthesis of the lipid A anchor of lipopolysaccharide (LPS). LPS from L. interrogans cells is unusual in that it activates TLR2 rather than TLR4. The structure of L. interrogans lipid A has now been determined by a combination of matrix-assisted laser desorption ionization time-of-flight mass spectrometry, NMR spectroscopy, and biochemical studies. Lipid A was released from LPS of L. interrogans serovar Pomona by 100 °C hydrolysis at pH 4.5 in the presence of SDS. Following purification by anion exchange and thin layer chromatography, the major component was shown to have a molecular weight of 1727. Mild hydrolysis with dilute NaOH reduced this to 1338, consistent with the presence of four N-linked and two O-linked acyl chains. The lipid A molecules of both the virulent and nonvirulent forms of L. interrogans serovar Icterohaemorrhagiae (strain Verdun) were identical to those of L. interrogans Pomona by the above criteria. Given the selectivity of L. interrogans LpxA for 3-hydroxylaurate, we propose that L. interrogans lipid A is acylated with R-3-hydroxylaurate at positions 3 and 3′ and with R-3-hydroxypalmitate at positions 2 and 2′. The hydroxyacyl chain composition was validated by gas chromatography and mass spectrometry of fatty acid methyl esters. Intact hexa-acylated lipid A of L. interrogans Pomona was also analyzed by NMR, confirming the presence a β-1′,6-linked disaccharide of 2,3-diamino-2,3-dideoxy-D-glucopyranose units. Two secondary unsaturated acyl chains are attached to the distal residue. The 1-position of the disaccharide is derivatized with an axial phosphate moiety, but the 4′-OH is unsubstituted. 1H and 31P NMR analyses revealed that the 1-phosphate group is methylated. Purified L. interrogans lipid A is inactive against human THP-1 cells but does stimulate tumor necrosis factor production by

  7. Serovar Diversity of Pathogenic Leptospira Circulating in the French West Indies

    PubMed Central

    Bourhy, Pascale; Herrmann Storck, Cécile; Theodose, Rafaelle; Olive, Claude; Nicolas, Muriel; Hochedez, Patrick; Lamaury, Isabelle; Zinini, Farida; Brémont, Sylvie; Landier, Annie; Cassadou, Sylvie; Rosine, Jacques; Picardeau, Mathieu

    2013-01-01

    Background Leptospirosis is one of the most important neglected tropical bacterial diseases in Latin America and the Caribbean. However, very little is known about the circulating etiological agents of leptospirosis in this region. In this study, we describe the serological and molecular features of leptospires isolated from 104 leptospirosis patients in Guadeloupe (n = 85) and Martinique (n = 19) and six rats captured in Guadeloupe, between 2004 and 2012. Methods and Findings Strains were studied by serogrouping, PFGE, MLVA, and sequencing 16SrRNA and secY. DNA extracts from blood samples collected from 36 patients in Martinique were also used for molecular typing of leptospires via PCR. Phylogenetic analyses revealed thirteen different genotypes clustered into five main clades that corresponded to the species: L. interrogans, L. kirschneri, L. borgpetersenii, L. noguchi, and L. santarosai. We also identified L. kmetyi in at least two patients with acute leptospirosis. This is the first time, to our knowledge, that this species has been identified in humans. The most prevalent genotypes were associated with L. interrogans serovars Icterohaemorrhagiae and Copenhageni, L. kirschneri serovar Bogvere, and L. borgpetersenii serovar Arborea. We were unable to identify nine strains at the serovar level and comparison of genotyping results to the MLST database revealed new secY alleles. Conclusions The overall serovar distribution in the French West Indies was unique compared to the neighboring islands. Typing of leptospiral isolates also suggested the existence of previously undescribed serovars. PMID:23516654

  8. Risk factors associated with prevalence of antibodies to Leptospira interrogans in a metapopulation of black-tailed prairie dogs in Mexico.

    PubMed

    Montiel-Arteaga, Ana; Atilano, Daniel; Ayanegui, Alejandra; Ceballos, Gerardo; Suzán, Gerardo

    2015-01-01

    Interest in the study of infectious diseases of wildlife has grown in recent decades and now focuses on understanding host-parasite dynamics and factors involved in disease occurrence. The black-tailed prairie dog (Cynomys ludovicianus) is a useful species for this type of investigation because it lives in heterogeneous landscapes where human activities take place, and its populations are structured as a metapopulation. Our goal was to determine if colony area, density, and proximity to human settlements are associated with prevalence of antibodies to Leptospira interrogans in black-tailed prairie dogs of northwestern Chihuahua State, Mexico. We captured 266 prairie dogs in 11 colonies in 2009 and analyzed 248 serum samples with the microscopic agglutination test (MAT) for antibody to any of the 12 pathogenic serovars of L. interrogans. Serologically positive test results for only serovars Bratislava, Canicola, Celledoni, and Tarassovi were considered for statistical analysis. Almost 80% of sera were positive for at least one pathogenic serovar (MAT titer ≥1∶80). The highest recorded antibody prevalences were to serovars Bratislava and Canicola. Correlation analysis showed a negative relationship between L. interrogans antibody prevalence and colony area (r = -0.125, P<0.005), suggesting that animals living in larger colonies were at a lower risk than those in smaller colonies. The correlation between the serovar Canicola and distance was negative (r = -0.171, P<0.007), and this relationship may be explained by the presence of domestic dogs associated with human dwellings. This is the first study of Leptospira spp. antibody prevalence in prairie dogs, and it provides valuable insights into the dynamics of leptospirosis in threatened wildlife species. Further studies are needed to evaluate the impact of Leptospira serovars in metapopulations of prairie dogs and other domestic and wild mammals in grassland communities. PMID:25380365

  9. Immunological and molecular characterization of Leptospira interrogans isolated from a bovine foetus.

    PubMed

    Monte, Leonardo Garcia; Ridieri, Karine Forster; Jorge, Sérgio; Oliveira, Natasha Rodrigues; Hartwig, Daiane Drawanz; Amaral, Marta Gonçalves; Hartleben, Cláudia Pinho; Dellagostin, Odir Antonio

    2015-06-01

    Cattle are commonly infected with pathogenic leptospires, and similarly to rodents, they excrete the bacteria in their urine and can transmit the pathogen from animal to animal or animal to human. Thus, surveillance and monitoring systems for detection of new Leptospira serovars are important for the control of leptospirosis. Here, we report the isolation of a spirochete from a stillborn bovine foetus and its characterization by immunological and molecular techniques. A variable number tandem repeat profile using seven discriminatory primers identified the spirochete as belonging to species Leptospira interrogans serogroup Australis serovar Muenchen. A phenotypic analysis using monoclonal antibodies (mAbs) against leptospiral membrane-associated proteins confirmed the expression of important virulence and pathogenicity factors (LipL32 and LigBrep). Out of 120 reference sera tested, 22 positive (36.66%) and 9 negative (15%) also reacted with the new isolate. Furthermore, the serovar Muenchen isolate was virulent in hamster model. The animal inoculated developed acute lethal infection characterized by hepatic, pulmonary and renal lesions. Local isolates exhibited unique characteristics that differed from those of reference strains; therefore, isolation of leptospires is useful in the surveillance of local pathogenic serovars. In conclusion, the data obtained from this study can contribute to the epidemiological understanding and control of leptospirosis in southern Brazil. PMID:25976319

  10. Comparative seroprevalence of Leptospira interrogans in Colombian mammals along a climatic gradient.

    PubMed

    Astudillo, Viviana González; Hernández, Dave Wehdeking; Stadlin, Juliana Peña; Bernal, Leonardo Arias; Rodríguez, Dora Adriana Lombo; Hernández, Miryam Astudillo

    2012-12-01

    Leptospirosis is a widespread zoonotic disease with well-established impacts on human health in tropical and subtropical regions. Although Leptospira spp. are known to readily infect many wildlife species, the understanding of interspecies and climatic variability in patterns of infection in Neotropical mammals is limited. To improve the understanding of this interplay, 85 mammals representing 17 species were sampled from four Colombian zoos along a climatic gradient. Prevalence of the 21 primary serovars against Leptospira interrogans was determined using the microagglutination test. Individuals were considered positive for a given serovar if antibodies were observable at a 1:100 dilution or greater. Overall prevalence was 9.52%, with positive titers to serovar hurstbridge in Carnivora (Canidae); serovar sarmin in Primata (Atelidae); and serovars australis, mini, autumnalis, pomona, icterohaemorrhagiae, and seramanga in Primata (Cebidae). Prevalence was positively correlated with humidity and temperature, with significantly higher prevalence at the site characterized by high humidity, severe flooding because of rainfall, and warm weather throughout the year. All positive animals were classified as clinically asymptomatic, meaning that antibodies from a current or past infection were detected but no overt symptoms were apparent. The diversity of serovars observed and the taxon-specific nature of these associations suggest that the epidemiology of Leptospira transmission is likely to be complex and multidimensional. The strong association observed between prevalence and climate suggests that the important role of climate as an indicator of Leptospira infection risk in humans may also be applicable to wildlife. Future studies in both wild and captive populations of Neotropical wildlife will further elucidate this disease interplay. PMID:23272343

  11. Dual nuclease activity of a Cas2 protein in CRISPR-Cas subtype I-B of Leptospira interrogans.

    PubMed

    Dixit, Bhuvan; Ghosh, Karukriti Kaushik; Fernandes, Gary; Kumar, Pankaj; Gogoi, Prerana; Kumar, Manish

    2016-04-01

    Leptospira interrogans serovar Copenhageni strain Fiocruz L1-130 carries a set of cas genes associated with CRISPR-Cas subtype I-B. Herein, we report for the first time active transcription of a set of cas genes (cas1 to cas8) of L. interrogans where cas4, cas1, cas2 and cas6, cas3, cas8, cas7, cas5 are clustered together in two independent operons. As an initial step toward comprehensive understanding of CRISPR-Cas system in spirochete, the biochemical study of one of the core Leptospira Cas2 proteins (Lep_Cas2) showed nuclease activity on both DNA and RNA in a nonspecific manner. Additionally, unlike other known Cas2 proteins, Lep_Cas2 showed metal-independent RNase activity and preferential activity on RNA over DNA. These results provide insight for understanding Cas2 diversity existing in the prokaryotic adaptive immune system. PMID:26950513

  12. In vivo cell aggregations of a recent swine biofilm-forming isolate of Leptospira interrogans strain from Argentina.

    PubMed

    Brihuega, Bibiana; Samartino, Luis; Auteri, Carmelo; Venzano, Agustín; Caimi, Karina

    2012-01-01

    Leptospirosis is a zoonosis of ubiquitous distribution caused by spirochetes. Leptospires exist either as saprophytic water-associated organisms or as animal pathogens that can survive in water. Previous works have demonstrated that both saprophytic and pathogenic leptospires are able to produce functional biofilms, which consist of a community of bacteria embedded in an extracellular matrix attached to a surface. This structure is believed to provide protection from environmental aggressiveness. In the present study, we analyzed the capacity of biofilm formation both of a a recent field isolate of Leptospira interrogans serovar Pomona obtained from an aborted swine fetus and of the saprophytic Leptospira biflexa serovar Patoc. We used light microscopy, immunofluorescence, and scanning electron microscopic examinations on glass and polystyrene plate models to evaluate the process in vitro. The ability to form bacterial aggregations in vivo was tested using pregnant guinea pigs infected with both strains. We obtained biofilms both on glass and plastic surfaces. Scanning electron microscopic analysis showed differences in the biofilm structure formed by both strains. L. interrogans serovar Pomona cell aggregations were observed in placental tissues by light microscopy. Biofilms and cell aggregations are consistent with the life of saprophytic strains in water and could help pathogenic strains to colonize the host and lead to abortion in pregnant animals. PMID:23102459

  13. Carriage of Leptospira interrogans among domestic rats from an urban setting highly endemic for leptospirosis in Brazil.

    PubMed

    de Faria, Marcos Tucunduva; Calderwood, Michael S; Athanazio, Daniel A; McBride, Alan J A; Hartskeerl, Rudy A; Pereira, Martha Maria; Ko, Albert I; Reis, Mitermayer G

    2008-10-01

    A survey was conducted to identify reservoirs for urban leptospirosis in the city of Salvador, Brazil. Sampling protocols were performed in the vicinity of households of severe leptospirosis cases identified during active hospital-based surveillance. Among a total of 142 captured Rattus norvegicus (Norwegian brown rat), 80.3% had a positive culture isolate from urine or kidney specimens and 68.1% had a positive serum sample by microscopic agglutination test (MAT) titre of > or = 1:100. Monoclonal antibody-based typing of isolates identified that the agent carried by rats was Leptospira interrogans serovar Copenhageni, which was the same serovar isolated from patients during hospital-based surveillance. Leptospira spp. were not isolated from 8 captured Didelphis marsupialis (Opossum), while 5/7 had a positive MAT titre against a saprophytic serogroup. R. rattus were not captured during the survey. The study findings indicate that the brown rat is a major rodent reservoir for leptospirosis in this urban setting. Furthermore, the high carriage rates of L. interrogans serovar Copenhageni in captured rats suggest that there is a significant degree of environmental contamination with this agent in the household environment of high risk areas, which in turn is a cause of transmission during urban epidemics. PMID:18721789

  14. Adhesins of Leptospira interrogans Mediate the Interaction to Fibrinogen and Inhibit Fibrin Clot Formation In Vitro

    PubMed Central

    Oliveira, Rosane; Domingos, Renan F.; Siqueira, Gabriela H.; Fernandes, Luis G.; Souza, Natalie M.; Vieira, Monica L.; de Morais, Zenaide M.; Vasconcellos, Silvio A.; Nascimento, Ana L. T. O.

    2013-01-01

    We report in this work that Leptospira strains, virulent L. interrogans serovar Copenhageni, attenuated L. interrogans serovar Copenhageni and saprophytic L. biflexa serovar Patoc are capable of binding fibrinogen (Fg). The interaction of leptospires with Fg inhibits thrombin- induced fibrin clot formation that may affect the haemostatic equilibrium. Additionally, we show that plasminogen (PLG)/plasmin (PLA) generation on the surface of Leptospira causes degradation of human Fg. The data suggest that PLA-coated leptospires were capable to employ their proteolytic activity to decrease one substrate of the coagulation cascade. We also present six leptospiral adhesins and PLG- interacting proteins, rLIC12238, Lsa33, Lsa30, OmpL1, rLIC11360 and rLIC11975, as novel Fg-binding proteins. The recombinant proteins interact with Fg in a dose-dependent and saturable fashion when increasing protein concentration was set to react to a fix human Fg concentration. The calculated dissociation equilibrium constants (KD) of these reactions ranged from 733.3±276.8 to 128±89.9 nM for rLIC12238 and Lsa33, respectively. The interaction of recombinant proteins with human Fg resulted in inhibition of fibrin clot by thrombin-catalyzed reaction, suggesting that these versatile proteins could mediate Fg interaction in Leptospira. Our data reveal for the first time the inhibition of fibrin clot by Leptospira spp. and presents adhesins that could mediate these interactions. Decreasing fibrin clot would cause an imbalance of the coagulation cascade that may facilitate bleeding and help bacteria dissemination PMID:24009788

  15. A Spatio-Temporal Enhancement Method for medium resolution LAI (STEM-LAI)

    NASA Astrophysics Data System (ADS)

    Houborg, Rasmus; McCabe, Matthew F.; Gao, Feng

    2016-05-01

    Satellite remote sensing has been used successfully to map leaf area index (LAI) across landscapes, but advances are still needed to exploit multi-scale data streams for producing LAI at both high spatial and temporal resolution. A multi-scale Spatio-Temporal Enhancement Method for medium resolution LAI (STEM-LAI) has been developed to generate 4-day time-series of Landsat-scale LAI from existing medium resolution LAI products. STEM-LAI has been designed to meet the demands of applications requiring frequent and spatially explicit information, such as effectively resolving rapidly evolving vegetation dynamics at sub-field (30 m) scales. In this study, STEM-LAI is applied to Moderate Resolution Imaging Spectroradiometer (MODIS) based LAI data and utilizes a reference-based regression tree approach for producing MODIS-consistent, but Landsat-based, LAI. The Spatial and Temporal Adaptive Reflectance Fusion Model (STARFM) is used to interpolate the downscaled LAI between Landsat acquisition dates, providing a high spatial and temporal resolution improvement over existing LAI products. STARFM predicts high resolution LAI by blending MODIS and Landsat based information from a common acquisition date, with MODIS data from a prediction date. To demonstrate its capacity to reproduce fine-scale spatial features observed in actual Landsat LAI, the STEM-LAI approach is tested over an agricultural region in Nebraska. The implementation of a 250 m resolution LAI product, derived from MODIS 1 km data and using a scale consistent approach based on the Normalized Difference Vegetation Index (NDVI), is found to significantly improve accuracies of spatial pattern prediction, with the coefficient of efficiency (E) ranging from 0.77-0.94 compared to 0.01-0.85 when using 1 km LAI inputs alone. Comparisons against an 11-year record of in-situ measured LAI over maize and soybean highlight the utility of STEM-LAI in reproducing observed LAI dynamics (both characterized by r2 = 0.86) over a

  16. Relationships between prevalence of Leptospira interrogans in cattle, and regional, climatic, and seasonal factors.

    PubMed

    Miller, D A; Wilson, M A; Beran, G W

    1991-11-01

    On the basis of serologic test results and isolation of leptospires from mature cattle, distribution and prevalence of Leptospira interrogans serovars and genotypes were compared by state and region of the United States. Relationships between isolation rate and month of sample collection, mean regional temperature, and mean regional precipitation were examined. Isolation rate and seroprevalence were significantly (P less than 0.001) higher for southeastern, south central, and Pacific coastal regions than for other regions of the United States. Isolates of genotypes hardjo-bovis A and kennewicki A and B, and of serovar grippotyphosa appeared to be randomly distributed. Genotype hardjo-bovis B isolates came from a southern area of the country that extends from Georgia to New Mexico. To the authors' knowledge, this is the first recorded isolation of serovar hardjo from Hawaii. Although significant relationship was not documented between isolation rate and month or season of the year, seroprevalence for summer, fall, and winter was significantly (P less than 0.001) higher than that for spring. Regional isolation rate was related more to mean temperature (r = 0.83; P less than 0.05) than to mean precipitation amount (r = 0.34; P greater than 0.50). PMID:1785720

  17. Isolation of Salmonella enterica and serologic reactivity to Leptospira interrogans in opossums (Didelphis virginiana) from Yucatán, México.

    PubMed

    Ruiz-Pina, Hugo Antonio; Puc-Franco, Miguel Angel; Flores-Abuxapqui, Javier; Vado-Solis, Ignacio; Cardenas-Marrufo, María Fidelia

    2002-01-01

    The presence of Salmonella enterica and serologic evidence of infection by Leptospira interrogans, were detected in the opossum Didelphis virginiana in a semi-urban locality of the Yucatán State, México. Ninety-one opossums were captured during the period April 1996 and May 1998. From a total of 17 feces samples, four Salmonella enterica subsp. enterica serotypes (Sandiego, Newport, Anatum, and Minnesota), and one Salmonella enterica subsp. arizonae serovar O44:Z4,Z23:- were isolated. Some opossums presented mixed infections. From 81 sera samples, four (4.9%) were positive to antibodies to Leptospira serovars pomona and wolfii. Both animals infected with Salmonella enterica and those serologically positive to Leptospira interrogans were captured in peridomestic habitat. Opossums infected with Salmonella enterica, were captured in dry season, and those seropositive to Leptospira interrogans during the rainy season. The implications of infection and reactivity of these zoonotic pathogens in D. virginiana in the Yucatan state are briefly discussed. PMID:12219118

  18. A combined approach of VNTR and MLST analysis: improving molecular typing of Argentinean isolates of Leptospira interrogans.

    PubMed

    Caimi, Karina; Varni, Vanina; Melendez, Yamil; Koval, Ariel; Brihuega, Bibiana; Ruybal, Paula

    2012-08-01

    Leptospirosis is an emerging infectious disease that has been identified as both a human and animal health problem worldwide. Regular outbreaks associated with specific risk factors have been reported in Argentina. However, there are no available data concerning the genetic population level for this pathogen. Therefore, the aim of this work was to describe the genetic diversity of Leptospira interrogans through the application of two molecular typing strategies: variable number of tandem repeats (VNTR) and multilocus sequence typing (MLST). For this purpose, seven reference strains and 18 non-epidemiologically related isolates from diverse hosts and Argentinean regions were analysed. Among them, nine genotypes and seven sequence types (STs), including three unreported STs, were described using VNTR and MLST, respectively. eBURST analysis demonstrated that ST37 was the most frequent and founder genotype of a clonal complex (CCs) containing STN1 and STN3, suggesting the importance of studying the serovars belonging to this CC in Argentina. The data from maximum parsimony analysis, which combined both techniques, achieved intra-serovar discrimination, surmounted microscopic agglutination test discrepancies and increased the discriminatory power of each technique applied separately. This study is the first to combine both strategies for L. interrogans typing to generate a more comprehensive molecular genotyping of isolates from Argentina in a global context. PMID:22850955

  19. A comprehensive survey on isoleucine biosynthesis pathways in seven epidemic Leptospira interrogans reference strains of China.

    PubMed

    Zou, Ying; Guo, Xiaokui; Picardeau, Mathieu; Xu, Hai; Zhao, Guoping

    2007-04-01

    Previous studies have indicated that different species of Leptospira synthesize isoleucine via either pyruvate and/or threonine pathways. Seven epidemic Leptospira interrogans reference strains from China belonging to different serovars, together with three saprophytic strains of Leptospira biflexa and Leptospira meyeri, were analysed. The isoleucine biosynthesis properties were studied firstly by measuring the key enzymes of the two pathways, citramalate synthase (CimA, CE4.1.3.-) and threonine deaminase (IlvA, CE4.2.1.16), from cell extracts of the bacteria. Meanwhile, alpha-isopropylmalate synthase (LeuA, CE4.2.1.12), the key enzyme of leucine biosynthesis, was also measured as a control. It was found that all L. interrogans strains synthesized isoleucine via the pyruvate pathway exclusively, but L. biflexa and L. meyeri used both pathways. Dot-Blot and PCR amplification of both cimA and ilvA genes in the corresponding strains provided additional evidence consistent with the data of enzymatic assays. Although it is evident that leptospires' isoleucine biosynthesis may preferentially adapt either to the pyruvate pathway exclusively for pathogens or to the combination of both pyruvate and threonine pathways for saprophytes, broader sampling with careful genomospecies identification is needed for a solid conclusion. PMID:17227461

  20. Kinetics of Leptospira interrogans Infection in Hamsters after Intradermal and Subcutaneous Challenge

    PubMed Central

    Coutinho, Mariana L.; Matsunaga, James; Wang, Long-Chieh; de la Peña Moctezuma, Alejandro; Lewis, Michael S.; Babbitt, Jane T.; Aleixo, Jose Antonio G.; Haake, David A.

    2014-01-01

    Background Leptospirosis is a zoonosis caused by highly motile, helically shaped bacteria that penetrate the skin and mucous membranes through lesions or abrasions, and rapidly disseminate throughout the body. Although the intraperitoneal route of infection is widely used to experimentally inoculate hamsters, this challenge route does not represent a natural route of infection. Methodology/Principal Findings Here we describe the kinetics of disease and infection in hamster model of leptospirosis after subcutaneous and intradermal inoculation of Leptospira interrogans serovar Copenhageni, strain Fiocruz L1-130. Histopathologic changes in and around the kidney, including glomerular and tubular damage and interstitial inflammatory changes, began on day 5, and preceded deterioration in renal function as measured by serum creatinine. Weight loss, hemoconcentration, increased absolute neutrophil counts (ANC) in the blood and hepatic dysfunction were first noted on day 6. Vascular endothelial growth factor, a serum marker of sepsis severity, became elevated during the later stages of infection. The burden of infection, as measured by quantitative PCR, was highest in the kidney and peaked on day 5 after intradermal challenge and on day 6 after subcutaneous challenge. Compared to subcutaneous challenge, intradermal challenge resulted in a lower burden of infection in both the kidney and liver on day 6, lower ANC and less weight loss on day 7. Conclusions/Significance The intradermal and subcutaneous challenge routes result in significant differences in the kinetics of dissemination and disease after challenge with L. interrogans serovar Copenhageni strain Fiocruz L1-130 at an experimental dose of 2×106 leptospires. These results provide new information regarding infection kinetics in the hamster model of leptospirosis. PMID:25411782

  1. Multiple-locus variable-number tandem repeat analysis of Leptospira interrogans and Leptospira borgpetersenii isolated from small feral and wild mammals in East Asia.

    PubMed

    Koizumi, Nobuo; Izumiya, Hidemasa; Mu, Jung-Jung; Arent, Zbigniew; Okano, Shou; Nakajima, Chie; Suzuki, Yasuhiko; Mizutani Muto, Maki; Tanikawa, Tsutomu; Taylor, Kyle R; Komatsu, Noriyuki; Yoshimatsu, Kumiko; Thi Thu Ha, Hoang; Ohnishi, Makoto

    2015-12-01

    Leptospira spp. are the causative agents of a worldwide zoonosis, leptospirosis, maintained by various mammals. Each Leptospira serovar is frequently associated with a particular maintenance host, and recently, Leptospira genotype-host association has also been suggested to limit serovars to restricted areas. We investigated the molecular characteristics of L. interrogans and L. borgpetersenii which were isolated from small feral and wild animals in four East Asian states using multiple-locus variable-number tandem repeat analysis (MLVA). MLVA using 11 loci was performed on 110 L. interrogans serogroups from Japan (79 strains of 5 serogroups from 3 animal species), Philippines (21; 3; 2), Taiwan (7; 2; 3), and Vietnam (3; 1; 1). A MLVA method using 4 loci for L. borgpetersenii was established and performed on 52 isolates from Japan (26; 3; 7), Philippines (13; 1; 2), and Taiwan (13; 1; 3). In L. interrogans, serogroups Autumnalis and Hebdomadis appeared more genetically diverse than serogroups Bataviae, Grippotyphosa, Icterohaemorrhagiae, Pomona, or Pyrogenes. The former serogroup strains with the exception of one Hebdomadis strain were isolated from Apodemus speciosus while all the latter serogroup strains with the exception of Grippotyphosa were isolated from Rattus norvegicus. L. borgpetersenii was isolated from at least 11 animal species while L. interrogans was isolated from five species, which might suggest a wider host range for L. borgpetersenii. Broad host preference in a single genotype was also observed, which colonized not only different species of the same genera but also multiple animal genera. This study demonstrates that there may be variability in the range of genetic diversity among different Leptospira serogroups, which may be attributed to maintenance host animals and environmental factors. PMID:26296603

  2. Comparison of Bacterial Burden and Cytokine Gene Expression in Golden Hamsters in Early Phase of Infection with Two Different Strains of Leptospira interrogans

    PubMed Central

    Fujita, Rie; Koizumi, Nobuo; Sugiyama, Hiromu; Tomizawa, Rina; Sato, Ryoichi; Ohnishi, Makoto

    2015-01-01

    Leptospirosis, a zoonotic infection with worldwide prevalence, is caused by pathogenic spirochaetes of Leptospira spp., and exhibits an extremely broad clinical spectrum in human patients. Although previous studies indicated that specific serovars or genotypes of Leptospira spp. were associated with severe leptospirosis or its outbreak, the mechanism underlying the difference in virulence of the various Leptospira serotypes or genotypes remains unclear. The present study addresses this question by measuring and comparing bacterial burden and cytokine gene expression in hamsters infected with strains of two L. interrogans serovars Manilae (highly virulent) and Hebdomadis (less virulent). The histopathology of kidney, liver, and lung tissues was also investigated in infected hamsters. A significantly higher bacterial burden was observed in liver tissues of hamsters infected with serovar Manilae than those infected with serovar Hebdomadis (p < 0.01). The average copy number of the leptospiral genome was 1,302 and 20,559 in blood and liver, respectively, of hamsters infected with serovar Manilae and 1,340 and 4,896, respectively, in hamsters infected with serovar Hebdomadis. The expression levels of mip1alpha in blood; tgfbeta, il1beta, mip1alpha, il10, tnfalpha and cox2 in liver; and tgfbeta, il6, tnfalpha and cox2 in lung tissue were significantly higher in hamsters infected with serovar Manilae than those infected with serovar Hebdomadis (p < 0.05). In addition, infection with serovar Manilae resulted in a significantly larger number of hamsters with tnfalpha upregulation (p = 0.04). Severe distortion of tubular cell arrangement and disruption of renal tubules in kidney tissues and hemorrhage in lung tissues were observed in Manilae-infected hamsters. These results demonstrate that serovar Manilae multiplied more efficiently in liver tissues and induced significantly higher expression of genes encoding pro- and anti-inflammatory cytokines than serovar Hebdomadis

  3. Isolation and characterization of Leptospira interrogans from pigs slaughtered in São Paulo State, Brazil

    PubMed Central

    Miraglia, Fabiana; Moreno, Andréa Mike; Gomes, Cleise Ribeiro; Paixão, Renata; Liuson, Esequiel; Morais, Zenaide Maria; Maiorka, Paulo; Seixas, Fabiana Kömmling; Dellagostin, Odir Antonio; Vasconcellos, Silvio Arruda

    2008-01-01

    With the aim of isolating Leptospira spp., blood serum, kidney, liver and genital tract of 137 female swine (40 sows and 97 gilts) and also urine samples from 22 sows were collected in a slaughterhouse in the State of São Paulo, from April 2003 to August 2004. Four isolates were obtained from animals that presented microagglutination test (MAT) titers ≥ 100 for the serovar Pomona and one was obtained from an animal negative by MAT in which Leptospira was isolated from the liver and reproductive tract. The presence of leptospiral DNA was investigated by PCR, and positive results were found in kidneys of 11 females, liver of two, genital tract of two and urine of one of them. Nephrosis, interstitial multifocal nephritis, moderate to severe changing, hyalines cylinders and hemorrhagic focuses, hepatic and uterine horns congestion were histological lesions observed in higher frequency in animals positive for leptospira. The silver impregnation (Warthin Starry) confirmed the presence of spirochetes in renal tubules of four females with positive leptospira cultures from kidneys. The serogroup of the five isolates was identified as Pomona by cross agglutination with reference polyclonal antibodies. Molecular characterization of the isolates was carried out by variable-number tandem-repeats analysis. All the isolates revealed a pattern distinct from the L. interrogans Pomona type strain, but identical to a previously identified pattern from strains isolated in Argentina belonging to serovar Pomona. PMID:24031254

  4. The passive diffusion of Leptospira interrogans

    NASA Astrophysics Data System (ADS)

    Koens, Lyndon; Lauga, Eric

    2014-12-01

    Motivated by recent experimental measurements, the passive diffusion of the bacterium Leptospira interrogans is investigated theoretically. By approximating the cell shape as a straight helix and using the slender-body-theory approximation of Stokesian hydrodynamics, the resistance matrix of Leptospira is first determined numerically. The passive diffusion of the helical cell is then obtained computationally using a Langevin formulation which is sampled in time in a manner consistent with the experimental procedure. Our results are in excellent quantitative agreement with the experimental results with no adjustable parameters.

  5. Collection 5 MODIS LAI/FPAR Products

    NASA Astrophysics Data System (ADS)

    Samanta, A.; Ganguly, S.; Schull, M. A.; Shabanov, N. V.; Knyazikhin, Y.; Myneni, R. B.

    2008-12-01

    MODIS LAI algorithm was substantially refined for the Collection 5 reprocessing to optimally use suite of MODIS observations from Terra and Aqua sensors. Refinements are based on advancements in RT theory, analysis of former versions of global time series of LAI product and product validation with field measurements. The Look-up-tables were regenerated for all vegetation types based on a new Stochastic RT model. The Collection 5 suite of LAI/FPAR products possesses higher quality retrievals than previous versions. The following 1-km products are operationally generated at NASA Science Computing Facilities (SCF): 8-day Terra and Aqua products, 8-days Combined Terra and Aqua product, and 4-day Combined Terra and Aqua product. In addition, monthly Collection 5 Terra products are processed and archived at the Boston University (BU) SCF. In this study, we analyzed Collection 5 LAI/FPAR products over a range of spatial scales: Global, North American continent (single composite during the growing season), at scale of MODIS tile (annual time series for three MODIS tiles), and at the scale of validation sites (annual time series for three sites). For analysis we used Collection 5 BU monthly Terra products. The LAI retrieval algorithm consists of two parts: main (Radiative Transfer based) and back-up (empirical). The BU monthly compositing scheme consists of 3 main steps: 1) selection of data from 8-day MOD15A2 product; 2) assembling tile data into global map based on a global land cover; and 3) degrading from 1km resolution to 4km resolution. We focused on the following: 1) Enhancement in the number of high quality retrievals in Collection 5; 2) Utility of the product to improve retrievals under atmospheric contamination of surface reflectance (clouds, aerosols) and for dense vegetation under saturation of surface reflectance; 3) Utility of the product to improve temporal resolution of retrievals.

  6. Stray dogs as reservoirs of the zoonotic agents Leptospira interrogans, Trypanosoma cruzi, and Aspergillus spp. in an urban area of Chiapas in southern Mexico.

    PubMed

    Jimenez-Coello, Matilde; Ortega-Pacheco, Antonio; Guzman-Marin, Eugenia; Guiris-Andrade, Dario M; Martinez-Figueroa, Laura; Acosta-Viana, Karla Y

    2010-03-01

    This investigation determined the presence and prevalence of the zoonotic agents Leptospira interrogans, Trypanosoma cruzi, and Aspergillus spp. in the stray dog population (a total of 224 stray dogs) in an urban area of Southern Mexico. Blood serum samples were taken from all dogs, and root hair samples were taken from dogs with skin lesions and partial alopecia. IgG antibodies for L. interrogans from 10 serovars were detected using the microscopic agglutination test. Immunofluorescence antibody test and Western blot assay were used for serologic diagnosis of T. cruzi. The Sabouraud medium was used to isolate Aspergillus spp. Prevalence of L. interrogans was 4.9%, which was determined by identifying only serovars Pyrogenes, which accounted for 3.6%, and Tarassovi, which constituted 1.3%, with titers from 1:100 to 1:800. Additionally, T. cruzi antibodies were detected in 4.5% of the dogs. Skin lesions were found in 43% of the dogs (98/224), and 35 cultures were positive for Aspergillus spp. (35.7%, p < 0.05, 95% confidence interval 2.45-3.67), identified as A. niger (82.8%), A. flavus (14.3%), and A. terreus (2.9%). This study demonstrates the presence of certain zoonotic agents (bacteria, protozoa, and fungi) in stray dogs living within the studied area. Dogs play an important role in the transmission of diseases that are potentially harmful to humans. Although the prevalence of canine leptospirosis and trypanosomiasis is not high in Southern Mexico compared with other tropical regions of Mexico, the presence of these zoonotic agents in the stray dog population demonstrates that the stray dog population in this region is a significant reservoir and potential source of infection in humans. Special care should be taken when handling stray dogs that exhibit skin lesions with partial alopecia, since a pathological Aspergillus sp. fungus may be present. PMID:19514808

  7. Isolation and molecular characterization of Leptospira borgpetersenii serovar Hardjo strain Hardjobovis in the urine of naturally infected cattle in Brazil.

    PubMed

    Chideroli, R T; Pereira, U P; Gonçalves, D D; Nakamura, A Y; Alfieri, A A; Alfieri, A F; Freitas, J C

    2016-01-01

    Most epidemiologic studies on bovine leptospirosis are based on serological tests that use antibodies against several serotypes, including the serovar Hardjo, which is widespread and considered to be the most adapted to bovine hosts. However, using only serological studies is not sufficient to identify and distinguish species of leptospires. The aim of this study was report the first isolation in Brazil of two strains serovar Hardjo obtained in urine samples from naturally infected cows in a small Brazilian dairy herd and find the genetic species and consequently the type strain Hardjobovis by molecular characterization. Fifteen dairy cows with a history of reproductive failure, such as abortion and infertility, were selected. Urine samples obtained from each animal were immediately seeded in tubes containing Ellinghausen-McCullough-Johnson-Harris culture medium. The identification of the isolates was performed by Multilocus variable-number tandem-repeat analysis (MLVA) technique and phylogenetic analysis of partial sequence of gene sec Y. From the 15 urine samples evaluated, two Leptospira were found and identified as the Londrina 49 and Londrina 54 strains. The MLVA profiles and sequencing of gene sec Y characterized the isolates as L. borgpetersenii serovar Hardjo strain Hadjobovis because it has different genetic pattern of Leptospira interrogans serovar Hardjo strain Hardjoprajitno. Therefore, more studies are needed including isolation and molecular characterization from regional strains to obtain a better knowledge about epidemiology of serovar Hardjo in bovine which may assist in future strategies of prevention and control of bovine leptospirosis. PMID:26909976

  8. Passive immunization with Leptospira LPS-specific agglutinating but not non-agglutinating monoclonal antibodies protect guinea pigs from fatal pulmonary hemorrhages induced by serovar Copenhageni challenge.

    PubMed

    Challa, Sreerupa; Nally, Jarlath E; Jones, Carroll; Sheoran, Abhineet S

    2011-06-15

    Leptospira interrogans serovar Copenhageni causes pulmonary hemorrhages with respiratory failure, a major cause of death in leptospirosis patients. Protective immunity to Leptospira is known to correlate with the production of leptospiral lipopolysaccharide (L-LPS)-specific agglutinating antibodies. We generated L-LPS-specific mouse monoclonal antibodies (MAbs) and investigated if these MAbs can protect guinea pigs against fatal pulmonary hemorrhages caused by serovar Copenhageni. The MAbs L8H4 and L9B11 against 22kDa L-LPS agglutinated leptospires and completely protected guinea pigs from the development of fatal pulmonary hemorrhages by serovar Copenhageni, whereas the MAb L4C1 against 8kDa L-LPS neither agglutinated the bacteria nor protected the animals against the fatal pulmonary hemorrhages. PMID:21549788

  9. Leptospira interrogans stably infects zebrafish embryos, altering phagocyte behavior and homing to specific tissues.

    PubMed

    Davis, J Muse; Haake, David A; Ramakrishnan, Lalita

    2009-01-01

    Leptospirosis is an extremely widespread zoonotic infection with outcomes ranging from subclinical infection to fatal Weil's syndrome. Despite the global impact of the disease, key aspects of its pathogenesis remain unclear. To examine in detail the earliest steps in the host response to leptospires, we used fluorescently labelled Leptospira interrogans serovar Copenhageni to infect 30 hour post fertilization zebrafish embryos by either the caudal vein or hindbrain ventricle. These embryos have functional innate immunity but have not yet developed an adaptive immune system. Furthermore, they are optically transparent, allowing direct visualization of host-pathogen interactions from the moment of infection. We observed rapid uptake of leptospires by phagocytes, followed by persistent, intracellular infection over the first 48 hours. Phagocytosis of leptospires occasionally resulted in formation of large cellular vesicles consistent with apoptotic bodies. By 24 hours, clusters of infected phagocytes were accumulating lateral to the dorsal artery, presumably in early hematopoietic tissue. Our observations suggest that phagocytosis may be a key defense mechanism in the early stages of leptospirosis, and that phagocytic cells play roles in immunopathogenesis and likely in the dissemination of leptospires to specific target tissues. PMID:19547748

  10. Severe Leptospira interrogans serovar Icterohaemorrhagiae infection with hepato-renal-pulmonary involvement treated with corticosteroids

    PubMed Central

    Schulze, Marco H; Raschel, Heribert; Langen, Heinz-Jakob; Stich, August; Tappe, Dennis

    2014-01-01

    Key Clinical Message The traditional concept of immediate antibiotic treatment in suspected leptospirosis seems to be especially important for patients up to day 4 of clinical illness. As immune mechanisms probably play a crucial role in advanced leptospirosis with presumed pulmonary hemorrhages, patients might benefit from corticosteroids or other immunosuppressive agents beside antibiotics. PMID:25614810

  11. Asymptomatic and chronic carriage of Leptospira interrogans serovar Pomona in California sea lions (Zalophus californianus)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Since 1970, periodic outbreaks of leptospirosis, caused by pathogenic spirochetes in the genus Leptospira, have caused morbidity and mortality of California sea lions (Zalophus californianus) along the Pacific coast of North America. Yearly seasonal epizootics of varying magnitude occur between the ...

  12. Geographical Dissemination of Leptospira interrogans serovar Pomona During Seasonal Migration of California Sea Lions

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Leptospirosis is one of the most widespread bacterial zoonoses in the world, and affects both terrestrial and marine mammals. Little information is available describing the geographical spread of leptospirosis, but it is logical to assume that animal migrations contribute to this process. There ha...

  13. Seasonal LAI in slash pine estimated with LANDSAT TM

    NASA Technical Reports Server (NTRS)

    Curran, Paul J.; Dungan, Jennifer L.; Gholz, Henry L.

    1990-01-01

    The leaf area index (LAI, total area of leaves per unit area of ground) of most forest canopies varies throughout the year, yet for logistical reasons it is difficult to estimate anything more detailed than a seasonal maximum LAI. To determine if remotely sensed data can be used to estimate LAI seasonally, field measurements of LAI were compared to normalized difference vegetation index (NDVI) values derived using LANDSAT Thematic Mapper (TM) data, for 16 fertilized and control slash pine plots on 3 dates. Linear relationships existed between NDVI and LAI with R(sup 2) values of 0.35, 0.75, and 0.86 for February 1988, September 1988, and March, 1989, respectively. This is the first reported study in which NDVI is related to forest LAI recorded during the month of sensor overpass. Predictive relationships based on data from eight of the plots were used to estimate the LAI of the other eight plots with a root-mean-square error of 0.74 LAI, which is 15.6 percent of the mean LAI. This demonstrates the potential use of LANDSAT TM data for studying seasonal dynamics in forest canopies.

  14. Seasonal LAI in slash pine estimated with Landsat TM

    NASA Technical Reports Server (NTRS)

    Curran, Paul J.; Dungan, Jennifer L.; Gholz, Henry L.

    1992-01-01

    The leaf area index (LAI, total area of leaves per unit area of ground) of most forest canopies varies throughout the year, yet for logistical reasons it is difficult to estimate anything more detailed than a seasonal maximum LAI. To determine if remotely sensed data can be used to estimate LAI seasonally, field measurements of LAI were compared to normalized difference vegetation index (NDVI) values derived using Lnandsat Thematic Mapper (TM) data, for 16 fertilized and control slash pine plots on 3 dates. Linear relationships existed between NDVI and LAI with R (sup 2) values of 0.35, 0.75, and 0.86 for February 1988, September 1988, and March, 1989, respectively. This is the first reported study in which NDVI is related to forest LAI recorded during the month of sensor overpass. Predictive relationships based on data from eight of the plots were used to estimate the LAI of the other eight plots with a root-mean-square error of 0.74 LAI, which is 15.6 percent of the mean LAI. This demonstrates the potential use of Landsat TM data for studying seasonal dynamics in forest canopies.

  15. Two Draft Genome Sequences of a New Serovar of Salmonella enterica, Serovar Lubbock

    PubMed Central

    den Bakker, Henk C.; Nightingale, Kendra K.; Brichta-Harhay, Dayna M.; Edrington, Thomas S.; Loneragan, Guy H.

    2015-01-01

    Salmonella enterica is principally a foodborne pathogen that shows considerable serovar diversity. In this report, we present two draft genome sequences of Salmonella enterica subsp. enterica serovar Lubbock, a novel serovar. PMID:25883279

  16. Two draft genome sequences of a new serovar of Salmonella enterica, serovar Lubbock

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Salmonella enterica is principally a foodborne pathogen that shows considerable serovar diversity. In this report, we present two draft genome sequences of Salmonella enterica subsp. enterica serovar Lubbock, a novel serovar....

  17. Three Different Methods of Estimating LAI in a Small Watershed

    NASA Astrophysics Data System (ADS)

    Speckman, H. N.; Ewers, B. E.; Beverly, D.

    2015-12-01

    Leaf area index (LAI) is a critical input of models that improve predictive understanding of ecology, hydrology, and climate change. Multiple techniques exist to quantify LAI, most of which are labor intensive, and all often fail to converge on similar estimates. . Recent large-scale bark beetle induced mortality greatly altered LAI, which is now dominated by younger and more metabolically active trees compared to the pre-beetle forest. Tree mortality increases error in optical LAI estimates due to the lack of differentiation between live and dead branches in dense canopy. Our study aims to quantify LAI using three different LAI methods, and then to compare the techniques to each other and topographic drivers to develop an effective predictive model of LAI. This study focuses on quantifying LAI within a small (~120 ha) beetle infested watershed in Wyoming's Snowy Range Mountains. The first technique estimated LAI using in-situ hemispherical canopy photographs that were then analyzed with Hemisfer software. The second LAI estimation technique was use of the Kaufmann 1982 allometrerics from forest inventories conducted throughout the watershed, accounting for stand basal area, species composition, and the extent of bark beetle driven mortality. The final technique used airborne light detection and ranging (LIDAR) first DMS returns, which were used to estimating canopy heights and crown area. LIDAR final returns provided topographical information and were then ground-truthed during forest inventories. Once data was collected, a fractural analysis was conducted comparing the three methods. Species composition was driven by slope position and elevation Ultimately the three different techniques provided very different estimations of LAI, but each had their advantage: estimates from hemisphere photos were well correlated with SWE and snow depth measurements, forest inventories provided insight into stand health and composition, and LIDAR were able to quickly and

  18. Post-translational Modification of LipL32 during Leptospira interrogans Infection

    PubMed Central

    Witchell, Timothy D.; Eshghi, Azad; Nally, Jarlath E.; Hof, Rebecca; Boulanger, Martin J.; Wunder, Elsio A.; Ko, Albert I.; Haake, David A.; Cameron, Caroline E.

    2014-01-01

    Background Leptospirosis, a re-emerging disease of global importance caused by pathogenic Leptospira spp., is considered the world's most widespread zoonotic disease. Rats serve as asymptomatic carriers of pathogenic Leptospira and are critical for disease spread. In such reservoir hosts, leptospires colonize the kidney, are shed in the urine, persist in fresh water and gain access to a new mammalian host through breaches in the skin. Methodology/Principal Findings Previous studies have provided evidence for post-translational modification (PTM) of leptospiral proteins. In the current study, we used proteomic analyses to determine the presence of PTMs on the highly abundant leptospiral protein, LipL32, from rat urine-isolated L. interrogans serovar Copenhageni compared to in vitro-grown organisms. We observed either acetylation or tri-methylation of lysine residues within multiple LipL32 peptides, including peptides corresponding to regions of LipL32 previously identified as epitopes. Intriguingly, the PTMs were unique to the LipL32 peptides originating from in vivo relative to in vitro grown leptospires. The identity of each modified lysine residue was confirmed by fragmentation pattern analysis of the peptide mass spectra. A synthetic peptide containing an identified tri-methylated lysine, which corresponds to a previously identified LipL32 epitope, demonstrated significantly reduced immunoreactivity with serum collected from leptospirosis patients compared to the peptide version lacking the tri-methylation. Further, a subset of the identified PTMs are in close proximity to the established calcium-binding and putative collagen-binding sites that have been identified within LipL32. Conclusions/Significance The exclusive detection of PTMs on lysine residues within LipL32 from in vivo-isolated L. interrogans implies that infection-generated modification of leptospiral proteins may have a biologically relevant function during the course of infection. Although

  19. Brown and green LAI mapping through spectral indices

    NASA Astrophysics Data System (ADS)

    Delegido, Jesús; Verrelst, Jochem; Rivera, Juan P.; Ruiz-Verdú, Antonio; Moreno, José

    2015-03-01

    When crops senescence, leaves remain until they fall off or are harvested. Hence, leaf area index (LAI) stays high even when chlorophyll content degrades to zero. Current LAI approaches from remote sensing techniques are not optimized for estimating LAI of senescent vegetation. In this paper a two-step approach has been proposed to realize simultaneous LAI mapping over green and senescent croplands. The first step separates green from brown LAI by means of a newly proposed index, 'Green Brown Vegetation Index (GBVI)'. This index exploits two shortwave infrared (SWIR) spectral bands centred at 2100 and 2000 nm, which fall right in the dry matter absorption regions, thereby providing positive values for senescent vegetation and negative for green vegetation. The second step involves applying linear regression functions based on optimized vegetation indices to estimate green and brown LAI estimation respectively. While the green LAI index uses a band in the red and a band in the red-edge, the brown LAI index uses bands located in the same spectral region as GBVI, i.e. an absorption band located in the region of maximum absorption of cellulose and lignin at 2154 nm, and a reference band at 1635 nm where the absorption of both water and dry matter is low. The two-step approach was applied to a HyMap image acquired over an agroecosystem at the agricultural site Barrax, Spain.

  20. Uncertainty Analysis in the Creation of a Fine-Resolution Leaf Area Index (LAI) Reference Map for Validation of Moderate Resolution LAI Products

    EPA Science Inventory

    The validation process for a moderate resolution leaf area index (LAI) product (i.e., MODIS) involves the creation of a high spatial resolution LAI reference map (Lai-RM), which when scaled to the moderate LAI resolution (i.e., >1 km) allows for comparison and analysis with this ...

  1. NEW WILDLIFE HOSTS OF Leptospira interrogans IN CAMPECHE, MEXICO

    PubMed Central

    ESPINOSA-MARTÍNEZ, Deborah V.; SÁNCHEZ-MONTES, Daniel Sokani; LEÓN-PANIAGUA, Livia; RÍOS-MUÑOZ, César A.; BERZUNZA-CRUZ, Miriam; BECKER, Ingeborg

    2015-01-01

    Leptospira interrogans has been identified to cause leptospirosis, a widespread zoonotic disease that has been identified in domestic and wild animals. This work analyzed kidneys from two species of wild rodents from the state of Campeche, Mexico. Analyses were made by PCR using specific primers for detection of Leptospira interrogans DNA. The rodent species that tested positive were Heteromys gaumeri and Ototylomys phyllotis, both of which are new hosts for the bacteria in Southeastern Mexico. These records provide new insights into the disease’s transmission that should be studied carefully in order to identify other potential host species, including humans, which are at risk of becoming infected if they are in contact with infected wildlife. PMID:25923901

  2. New wildlife hosts of Leptospira interrogans in Campeche, Mexico.

    PubMed

    Espinosa-Martínez, Deborah V; Sánchez-Montes, Daniel Sokani; León-Paniagua, Livia; Ríos-Muñoz, César A; Berzunza-Cruz, Miriam; Becker, Ingeborg

    2015-01-01

    Leptospira interrogans has been identified to cause leptospirosis, a widespread zoonotic disease that has been identified in domestic and wild animals. This work analyzed kidneys from two species of wild rodents from the state of Campeche, Mexico. Analyses were made by PCR using specific primers for detection of Leptospira interrogans DNA. The rodent species that tested positive were Heteromys gaumeri and Ototylomys phyllotis, both of which are new hosts for the bacteria in Southeastern Mexico. These records provide new insights into the disease's transmission that should be studied carefully in order to identify other potential host species, including humans, which are at risk of becoming infected if they are in contact with infected wildlife. PMID:25923901

  3. Identification of Cell-Binding Adhesins of Leptospira interrogans

    PubMed Central

    Evangelista, Karen V.; Hahn, Beth; Wunder, Elsio A.; Ko, Albert I.; Haake, David A.; Coburn, Jenifer

    2014-01-01

    Leptospirosis is a globally distributed bacterial infectious disease caused by pathogenic members of the genus Leptospira. Infection can lead to illness ranging from mild and non-specific to severe, with jaundice, kidney and liver dysfunction, and widespread endothelial damage. The adhesion of pathogenic Leptospira species (spp.), the causative agent of leptospirosis, to host tissue components is necessary for infection and pathogenesis. While it is well-established that extracellular matrix (ECM) components play a role in the interaction of the pathogen with host molecules, we have shown that pathogenic Leptospira interrogans binds to host cells more efficiently than to ECM components. Using in vitro phage display to select for phage clones that bind to EA.hy926 endothelial cells, we identified the putative lipoproteins LIC10508 and LIC13411, and the conserved hypothetical proteins LIC12341 and LIC11574, as candidate L. interrogans sv. Copenhageni st. Fiocruz L1–130 adhesins. Recombinant LIC11574, but not its L. biflexa homologue LBF1629, exhibited dose-dependent binding to both endothelial and epithelial cells. In addition, LIC11574 and LIC13411 bind to VE-cadherin, an endothelial cell receptor for L. interrogans. Extraction of bacteria with the non-ionic detergent Triton X-114 resulted in partitioning of the candidate adhesins to the detergent fraction, a likely indication that these proteins are outer membrane localized. All candidate adhesins were recognized by sera obtained from leptospirosis patients but not by sera from healthy individuals as assessed by western blot. This work has identified bacterial adhesins that are potentially involved in L. interrogans infection of the mammalian host, and through cadherin binding, may contribute to dissemination and vascular damage. Our findings may be of value in leptospirosis control and prevention, with the bacterial adhesins potentially serving as targets for development of diagnostics, therapeutics, and

  4. Distribution of Leptospira interrogans by Multispacer Sequence Typing in Urban Norway Rats (Rattus norvegicus): A Survey in France in 2011-2013

    PubMed Central

    Bicout, Dominique J.; Kodjo, Angeli; Artois, Marc; Djelouadji, Zoheira

    2015-01-01

    Background Urban leptospirosis has increasingly been reported in both developing and developed countries. The control of the disease is limited because our understanding of basic aspects of the epidemiology, including the transmission routes of leptospires among rat populations, remains incomplete. Through the ability to distinguish among Leptospira strains in rats, multispacer sequence typing (MST) could provide a modern understanding of Leptospira epidemiology; however, to our knowledge, the distribution of Leptospira strains among urban rat colonies has not been investigated using MST. Aims and Methodology The objective of this study was to identify the Leptospira strains present in rats (Rattus norvegicus) in Lyon (France) using MST and to characterize their spatial distribution. Kidneys and urine were collected from rats trapped live in seven locations in the city and in one suburban location. Each location was considered to represent a rat colony. Bacterial cultures and quantitative polymerase chain reaction (qPCR) assays were performed, and the L. interrogans DNA identified was then genotyped using MST. The distributions of Leptospira strains were spatially described. Key Results Among 84 wild rats, MST profiles were obtained in 35 of 37 rats that had a positive result for L. interrogans by bacterial culture and/or qPCR analyses. All of the MST profiles were related to reference strains previously isolated from human patients that belong to the serogroup Icterohaemorrhagiae and the serovars [strain(s)] Copenhageni [Wijinberg or M20] (n = 26), Icterohaemorrhagiae [CHU Réunion] (n = 7), Icterohaemorrhagiae [R1] (n = 1) and Copenhageni [Shibaura 9] (n = 1). Each colony was infected with leptospires having the same MST profile. Major Conclusions This study demonstrated that MST could be used for the purpose of field studies, either on culture isolates or on DNA extracted from kidneys and urine, to distinguish among L. interrogans isolates in rats. MST could

  5. BOREAS RSS-7 LAI, Gap Fraction, and FPAR Data

    NASA Technical Reports Server (NTRS)

    Hall, Forrest G. (Editor); Nickeson, Jaime (Editor); Chen, Jing

    2000-01-01

    The BOREAS RSS-7 team collected various data sets to develop and validate an algorithm to allow the retrieval of the spatial distribution of Leaf Area Index (LAI) from remotely sensed images. Ground measurements of LAI and Fraction of Photosynthetically Active Radiation (FPAR) absorbed by the plant canopy were made using the LAI-2000 and TRAC optical instruments during focused periods from 09-Aug-1993 to 19-Sep-1994. The measurements were intensive at the NSA and SSA tower sites, but were made just once or twice at auxiliary sites. The final processed LAI and FPAR data set is contained in tabular ASCII files. The data files are available on a CD-ROM (see document number 20010000884).

  6. Development of Transcriptional Fusions to Assess Leptospira interrogans Promoter Activity

    PubMed Central

    Cerqueira, Gustavo M.; Souza, Natalie M.; Araújo, Eduardo R.; Barros, Aline T.; Morais, Zenaide M.; Vasconcellos, Sílvio A.; Nascimento, Ana L. T. O.

    2011-01-01

    Background Leptospirosis is a zoonotic infectious disease that affects both humans and animals. The existing genetic tools for Leptospira spp. have improved our understanding of the biology of this spirochete as well as the interaction of pathogenic leptospires with the mammalian host. However, new tools are necessary to provide novel and useful information to the field. Methodology and Principal Findings A series of promoter-probe vectors carrying a reporter gene encoding green fluorescent protein (GFP) were constructed for use in L. biflexa. They were tested by constructing transcriptional fusions between the lipL41, Leptospiral Immunoglobulin-like A (ligA) and Sphingomielynase 2 (sph2) promoters from L. interrogans and the reporter gene. ligA and sph2 promoters were the most active, in comparison to the lipL41 promoter and the non-induced controls. The results obtained are in agreement with LigA expression from the L. interrogans Fiocruz L1-130 strain. Conclusions The novel vectors facilitated the in vitro evaluation of L. interrogans promoter activity under defined growth conditions which simulate the mammalian host environment. The fluorescence and rt-PCR data obtained closely reflected transcriptional regulation of the promoters, thus demonstrating the suitability of these vectors for assessing promoter activity in L. biflexa. PMID:21445252

  7. Occurrence of antibodies anti -Toxoplasma gondii, Neospora caninum and Leptospira interrogans in a captive deer herd in Southern Brazil.

    PubMed

    Zimpel, Cristina Kraemer; Grazziotin, Ana Laura; de Barros Filho, Ivan Roque; Guimaraes, Ana Marcia de Sa; dos Santos, Leonilda Correia; de Moraes, Wanderlei; Cubas, Zalmir Silvino; de Oliveira, Marcos Jose; Pituco, Edviges Maristela; Lara, Maria do Carmo Custódio de Souza Hunold; Villalobos, Eliana Monteforte Cassaro; Silva, Lília Marcia Paulin; Cunha, Elenice Maria Sequetin; Castro, Vanessa; Biondo, Alexander Welker

    2015-01-01

    A large number of Brazilian zoos keep many endangered species of deer, however, very few disease surveillance studies have been conducted among captive cervids. Blood samples from 32 Brazilian deer (Blastocerus dichotomus, Mazama nana and Mazama americana) kept in captivity at Bela Vista Biological Sanctuary (Foz do Iguaçu, Brazil) were investigated for 10 ruminant pathogens, with the aims of monitoring deer health status and evaluating any potential zoonotic risk. Deer serum samples were tested for Brucella abortus, Leptospira (23 serovars), Toxoplasma gondii, Neospora caninum, bovine viral diarrhea virus, infectious bovine rhinotracheitis virus, foot-and-mouth disease virus, western equine encephalitis virus, eastern equine encephalitis virus and Venezuelan equine encephalitis virus. Antibodies against T. gondii (15.6%), N. caninum (6.2%) and L. interrogans serogroup Serjoe (3.1%) were detected. The serological results for all other infectious agents were negative. The deer were considered to be clinically healthy and asymptomatic regarding any disease. Compared with studies on free-ranging deer, the prevalences of the same agents tested among the captive deer kept at the Sanctuary were lower, thus indicating good sanitary conditions and high-quality management practices at the zoo. PMID:26689185

  8. Leptospiral Antibodies in Cattle in Alberta and Evidence of an Emerging Serovar

    PubMed Central

    Kingscote, Barbara

    1988-01-01

    Antibodies to Leptospira interrogans serovars hardjo and pomona were present in 8.3% and 0.5% of sera respectively, from adult female cattle in Alberta surveyed in 1984-85. Criterion for a positive serum sample was 50% agglutination at 1/100 dilution in the microscopic agglutination test. A positive herd contained one or more cows with positive serum. Prevalences were calculated on sample sizes that would give 80-95% reliability. Hardjo antibody prevalences and hardjo-positive herd prevalences were 0-53.9% and 0-83.3%, respectively, among 65 municipalities surveyed. Pomona prevalences by comparison were 0-3.4% and 0-11.7% respectively. Hardjo had increased significantly since 1980-82, and antibodies were found throughout the province. Pomona occurred mainly in southeastern Alberta, where it was isolated from cattle, swine and skunks. Hardjo was isolated only from cattle and it was found in many areas. Antibodies to icterohaemorrhagiae were present in 0.4% of sera from parts of Alberta surveyed in 1980; evidence of the presence of leptospires related to this serovar in bovine and porcine urinary tracts was obtained by immunofluorescence. ImagesFigure 3. PMID:17423101

  9. Framework for automated spatio-temporal enhancement of coarse resolution leaf area index (FASE-LAI) – Application to MODIS LAI

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A multi-scale satellite-based Framework for Automated Spatio-temporal Enhancement of coarse-resolution leaf area index (LAI) products (FASE-LAI) has ben established to generate 4-day time-series of Landsat-scale LAI, thereby meeting the critical demands of applications needing frequent and high spat...

  10. Pathogenic Leptospira interrogans exoproteins are primarily involved in heterotrophic processes.

    PubMed

    Eshghi, Azad; Pappalardo, Elisa; Hester, Svenja; Thomas, Benjamin; Pretre, Gabriela; Picardeau, Mathieu

    2015-08-01

    Leptospirosis is a life-threatening and emerging zoonotic disease with a worldwide annual occurrence of more than 1 million cases. Leptospirosis is caused by spirochetes belonging to the genus Leptospira. The mechanisms of disease manifestation in the host remain elusive, and the roles of leptospiral exoproteins in these processes have yet to be determined. Our aim in this study was to assess the composition and quantity of exoproteins of pathogenic Leptospira interrogans and to construe how these proteins contribute to disease pathogenesis. Label-free quantitative mass spectrometry of proteins obtained from Leptospira spirochetes cultured in vitro under conditions mimicking infection identified 325 exoproteins. The majority of these proteins are conserved in the nonpathogenic species Leptospira biflexa, and proteins involved in metabolism and energy-generating functions were overrepresented and displayed the highest relative abundance in culture supernatants. Conversely, proteins of unknown function, which represent the majority of pathogen-specific proteins (presumably involved in virulence mechanisms), were underrepresented. Characterization of various L. interrogans exoprotein mutants in the animal infection model revealed host mortality rates similar to those of hosts infected with wild-type L. interrogans. Collectively, these results indicate that pathogenic Leptospira exoproteins primarily function in heterotrophic processes (the processes by which organisms utilize organic substances as nutrient sources) to maintain the saprophytic lifestyle rather than the virulence of the bacteria. The underrepresentation of proteins homologous to known virulence factors, such as toxins and effectors in the exoproteome, also suggests that disease manifesting from Leptospira infection is likely caused by a combination of the primary and potentially moonlight functioning of exoproteins. PMID:25987703

  11. Pathogenic Leptospira interrogans Exoproteins Are Primarily Involved in Heterotrophic Processes

    PubMed Central

    Eshghi, Azad; Pappalardo, Elisa; Hester, Svenja; Thomas, Benjamin; Pretre, Gabriela

    2015-01-01

    Leptospirosis is a life-threatening and emerging zoonotic disease with a worldwide annual occurrence of more than 1 million cases. Leptospirosis is caused by spirochetes belonging to the genus Leptospira. The mechanisms of disease manifestation in the host remain elusive, and the roles of leptospiral exoproteins in these processes have yet to be determined. Our aim in this study was to assess the composition and quantity of exoproteins of pathogenic Leptospira interrogans and to construe how these proteins contribute to disease pathogenesis. Label-free quantitative mass spectrometry of proteins obtained from Leptospira spirochetes cultured in vitro under conditions mimicking infection identified 325 exoproteins. The majority of these proteins are conserved in the nonpathogenic species Leptospira biflexa, and proteins involved in metabolism and energy-generating functions were overrepresented and displayed the highest relative abundance in culture supernatants. Conversely, proteins of unknown function, which represent the majority of pathogen-specific proteins (presumably involved in virulence mechanisms), were underrepresented. Characterization of various L. interrogans exoprotein mutants in the animal infection model revealed host mortality rates similar to those of hosts infected with wild-type L. interrogans. Collectively, these results indicate that pathogenic Leptospira exoproteins primarily function in heterotrophic processes (the processes by which organisms utilize organic substances as nutrient sources) to maintain the saprophytic lifestyle rather than the virulence of the bacteria. The underrepresentation of proteins homologous to known virulence factors, such as toxins and effectors in the exoproteome, also suggests that disease manifesting from Leptospira infection is likely caused by a combination of the primary and potentially moonlight functioning of exoproteins. PMID:25987703

  12. Leptospira species and serovars identified by MALDI-TOF mass spectrometry after database implementation

    PubMed Central

    2014-01-01

    Background Leptospirosis, a spirochaetal zoonotic disease of worldwide distribution, endemic in Europe, has been recognized as an important emerging infectious disease, though yet it is mostly a neglected disease which imparts its greatest burden on impoverished populations from developing countries. Leptospirosis is caused by the infection with any of the more than 230 serovars of pathogenic Leptospira sp. In this study we aimed to implement the MALDI-TOF mass spectrometry (MS) database currently available in our laboratory with Leptospira reference pathogenic (L. interrogans, L. borgpetersenii, L. kirschneri, L. noguchii), intermediate (L. fainei) and saprophytic (L. biflexa) strains of our collection in order to evaluate its possible application to the diagnosis of leptospirosis and to the typing of strains. This was done with the goal of understanding whether this methodology could be used as a tool for the identification of Leptospira strains, not only at species level for diagnostic purposes, but also at serovar level for epidemiological purposes, overcoming the limits of serological and molecular conventional methods. Twenty Leptospira reference strains were analysed by MALDI-TOF MS. Statistical analysis of the protein spectra was performed by ClinProTools software. Results The spectra obtained by the analysis of the reference strains tested were grouped into 6 main classes corresponding to the species analysed, highlighting species-specific protein profiles. Moreover, the statistical analysis of the spectra identified discriminatory peaks to recognize Leptospira strains also at serovar level extending previously published data. Conclusions In conclusion, we confirmed that MALDI-TOF MS could be a powerful tool for research and diagnostic in the field of leptospirosis with broad applications ranging from the detection and identification of pathogenic leptospires for diagnostic purposes to the typing of pathogenic and non-pathogenic leptospires for

  13. Assimilation of LAI time-series in crop production models

    NASA Astrophysics Data System (ADS)

    Kooistra, Lammert; Rijk, Bert; Nannes, Louis

    2014-05-01

    Agriculture is worldwide a large consumer of freshwater, nutrients and land. Spatial explicit agricultural management activities (e.g., fertilization, irrigation) could significantly improve efficiency in resource use. In previous studies and operational applications, remote sensing has shown to be a powerful method for spatio-temporal monitoring of actual crop status. As a next step, yield forecasting by assimilating remote sensing based plant variables in crop production models would improve agricultural decision support both at the farm and field level. In this study we investigated the potential of remote sensing based Leaf Area Index (LAI) time-series assimilated in the crop production model LINTUL to improve yield forecasting at field level. The effect of assimilation method and amount of assimilated observations was evaluated. The LINTUL-3 crop production model was calibrated and validated for a potato crop on two experimental fields in the south of the Netherlands. A range of data sources (e.g., in-situ soil moisture and weather sensors, destructive crop measurements) was used for calibration of the model for the experimental field in 2010. LAI from cropscan field radiometer measurements and actual LAI measured with the LAI-2000 instrument were used as input for the LAI time-series. The LAI time-series were assimilated in the LINTUL model and validated for a second experimental field on which potatoes were grown in 2011. Yield in 2011 was simulated with an R2 of 0.82 when compared with field measured yield. Furthermore, we analysed the potential of assimilation of LAI into the LINTUL-3 model through the 'updating' assimilation technique. The deviation between measured and simulated yield decreased from 9371 kg/ha to 8729 kg/ha when assimilating weekly LAI measurements in the LINTUL model over the season of 2011. LINTUL-3 furthermore shows the main growth reducing factors, which are useful for farm decision support. The combination of crop models and sensor

  14. Crystallization and preliminary X-ray diffraction studies of ferredoxin reductase from Leptospira interrogans

    SciTech Connect

    Nascimento, Alessandro S.; Ferrarezi, Thiago; Catalano-Dupuy, Daniela L.; Ceccarelli, Eduardo A.; Polikarpov, Igor

    2006-07-01

    Crystals adequate for X-ray diffraction analysis have been prepared from L. interrogans ferredoxin-NADP{sup +} reductase. Ferredoxin-NADP{sup +} reductase (FNR) is an FAD-containing enzyme that catalyzes electron transfer between NADP(H) and ferredoxin. Here, results are reported of the recombinant expression, purification and crystallization of FNR from Leptospira interrogans, a parasitic bacterium of animals and humans. The L. interrogans FNR crystals belong to a primitive monoclinic space group and diffract to 2.4 Å resolution at a synchrotron source.

  15. Characterization of Leptospira isolates from serovar hardjo by ribotyping, arbitrarily primed PCR, and mapped restriction site polymorphisms.

    PubMed Central

    Perolat, P; Merien, F; Ellis, W A; Baranton, G

    1994-01-01

    Leptospira serovar hardjo isolates of the hardjoprajitno and hardjobovis genotypes were characterized by ribotyping, arbitrarily primed PCR (AP-PCR) fingerprinting, and the study of mapped restriction site polymorphisms (MRSPs) in rrs and rrl genes. After restriction of chromosomal DNA with BglII, EcoRI, or HindIII, each genotype was individualized with a distinct ribotype. The fingerprints produced by AP-PCR with seven primers clearly separated the two groups; primers KF and RSP produced species-specific products which assigned hardjoprajitno and hardjobovis isolates to the species L. interrogans sensu stricto and L. borgpetersenii, respectively. Furthermore, AP-PCR fingerprints gave evidence of a considerable genomic heterogeneity at the strain level among the hardjobovis group. Conversely, the hardjoprajitno group was homogeneous. MRSP profiles in ribosomal genes indicated that hardjoprajitno and hardjobovis isolates belonged to L. interrogans MRSP group B and L. borgpetersenii group C, respectively. AP-PCR and determination of MRSPs in ribosomal genes proved to be quick and reliable methods for typing Leptospira strains and for studying intraspecific population structures. Images PMID:7989548

  16. LAI reactivity in rats immunized with tumor cells.

    PubMed

    Pham Manh Hung; Kalafut, F; Novotná, L; Koníková, E

    1980-01-01

    Leukocytes of peripheral blood of F1 hybrid inbred strain of rats LW X AVN and rats of inbred Lewis strain, immunized for three consecutive weeks with increasing doses of live or dead MC-1 or B 77 tumor cells, incubated for 20 hours with specific tumor extract, showed a lower adhering ability (LAI 32.8 +/- 16.6, 44.4 +/- 14.0, 43.1 +/- 7.4%) than that of the same cell population cultured without a specific antigen. The nonspecific tumor extract did not produce any LAI reactivity (4.4 +/- 5.9, 5.8 +/- 8.2, 6.7 +/- 5.9%). The values of LAI leukocytes of the controls tested by both the antigens were concordant with those found in samples of the same cell population tested without any antigens. The discussion bears on a possibility of applying the 20-hour modification of the LAI test in studies of cell immunity in immunized patients. PMID:7005699

  17. Comparison of MODIS LAI data products in Mclean county, Illinois

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In 2000, shortly after NASA Terra was launched, Dr. Doraiswamy started experiments to determine the usefulness of the Moderate Resolution Imaging Spectroradiometer (MODIS) for crop modeling, particularly the Leaf Area Index (LAI) data product (MOD15A). The field experiments were conducted in Mclean...

  18. Identification of Leptospira interrogans Phospholipase C as a Novel Virulence Factor Responsible for Intracellular Free Calcium Ion Elevation during Macrophage Death

    PubMed Central

    Ojcius, David M.; Zhao, Xin; Sun, Dexter; Ge, Yu-Mei; Zheng, Lin-Li; Lin, Xu’ai; Li, Lan-Juan; Yan, Jie

    2013-01-01

    Background Leptospira-induced macrophage death has been confirmed to play a crucial role in pathogenesis of leptospirosis, a worldwide zoonotic infectious disease. Intracellular free Ca2+ concentration ([Ca2+]i) elevation induced by infection can cause cell death, but [Ca2+]i changes and high [Ca2+]i-induced death of macrophages due to infection of Leptospira have not been previously reported. Methodology/Principal Findings We first used a Ca2+-specific fluorescence probe to confirm that the infection of L. interrogans strain Lai triggered a significant increase of [Ca2+]i in mouse J774A.1 or human THP-1 macrophages. Laser confocal microscopic examination showed that the [Ca2+]i elevation was caused by both extracellular Ca2+ influx through the purinergic receptor, P2X7, and Ca2+ release from the endoplasmic reticulum, as seen by suppression of [Ca2+]i elevation when receptor-gated calcium channels were blocked or P2X7 was depleted. The LB361 gene product of the spirochete exhibited phosphatidylinositol phospholipase C (L-PI-PLC) activity to hydrolyze phosphatidylinositol-4,5-bisphosphate (PIP2) into inositol-1,4,5-trisphosphate (IP3), which in turn induces intracellular Ca2+ release from endoplasmic reticulum, with the Km of 199 µM and Kcat of 8.566E-5 S-1. Secretion of L-PI-PLC from the spirochete into supernatants of leptospire-macrophage co-cultures and cytosol of infected macrophages was also observed by Western Blot assay. Lower [Ca2+]i elevation was induced by infection with a LB361-deficient leptospiral mutant, whereas transfection of the LB361 gene caused a mild increase in [Ca2+]i. Moreover, PI-PLCs (PI-PLC-β3 and PI-PLC-γ1) of the two macrophages were activated by phosphorylation during infection. Flow cytometric detection demonstrated that high [Ca2+]i increases induced apoptosis and necrosis of macrophages, while mild [Ca2+]i elevation only caused apoptosis. Conclusions/Significance This study demonstrated that L. interrogans infection induced [Ca2

  19. Leptospira interrogans induces uterine inflammatory responses and abnormal expression of extracellular matrix proteins in dogs.

    PubMed

    Wang, Wei; Gao, Xuejiao; Guo, Mengyao; Zhang, Wenlong; Song, Xiaojing; Wang, Tiancheng; Zhang, Zecai; Jiang, Haichao; Cao, Yongguo; Zhang, Naisheng

    2014-10-01

    Leptospira interrogans (L. interrogans), a worldwide zoonosis, infect humans and animals. In dogs, four syndromes caused by leptospirosis have been identified: icteric, hemorrhagic, uremic (Stuttgart disease) and reproductive (abortion and premature or weak pups), and also it caused inflammation. Extracellular matrix (ECM) is a complex mixture of matrix molecules that is crucial to the reproduction. Both inflammatory response and ECM are closed relative to reproductive. The aim of this study was to clarify how L. interrogans affected the uterus of dogs, by focusing on the inflammatory responses, and ECM expression in dogs uterine tissue infected by L. interrogans. In the present study, 27 dogs were divided into 3 groups, intrauterine infusion with L. interrogans, to make uterine infection, sterile EMJH, and normal saline as a control, respectively. The uteruses were removed by surgical operation in 10, 20, and 30 days, respectively. The methods of histopathological analysis, ELISA, Western blot and qPCR were used. The results showed that L. interrogans induced significantly inflammatory responses, which were characterized by inflammatory cellular infiltration and high expression levels of tumor necrosis factor α (TNF-α), interleukin-1β (IL-1β) and interleukin-6 (IL-6) in uterine tissue of these dogs. Furthermore, L. interrogans strongly down-regulated the expression of ECM (collagens (CL) IV, fibronectins (FN) and laminins (LN)) in mRNA and protein levels. These data indicated that strongly inflammatory responses, and abnormal regulation of ECM might contribute to the proliferation of dogs infected by L. interrogans. PMID:25153777

  20. Salmonella serovars differentially stimulate bovine leukocyte responses in vitro

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The majority of Salmonella serovars cause no clinical signs in cattle, while some serovars, such as Salmonella enterica serovar Typhimurium (ST) and Dublin (SD), may cause severe disease. Mechanisms underlying the difference in pathogenesis between different serovars are not clear. The objective of ...

  1. Visual proteomics of the human pathogen Leptospira interrogans

    PubMed Central

    Beck, Martin; Malmström, Johan A.; Lange, Vinzenz; Schmidt, Alexander; Deutsch, Eric W.; Aebersold, Ruedi

    2010-01-01

    Systems biology conceptualizes biological systems as dynamic networks of interacting elements, whereby functionally important properties are thought to emerge from the structure of such networks. Due to the ubiquitous role of complexes of interacting proteins in biological systems, their subunit composition and temporal and spatial arrangement within the cell are of particular interest. ‘Visual proteomics’ attempts to localize individual macromolecular complexes inside of intact cells by template matching reference structures into cryo electron tomograms. Here we have combined quantitative mass spectrometry and cryo electron tomography to detect, count and localize specific protein complexes within the cytoplasm of the human pathogen Leptospira interrogans. We describe a novel scoring function for visual proteomics and assess its performance and accuracy under realistic conditions. We discuss current and general limitations of the approach, as well as expected improvements in the future. PMID:19838170

  2. Crystal structure of homoserine O-acetyltransferase from Leptospira interrogans

    SciTech Connect

    Wang Mingzhu; Liu Lin; Wang Yanli; Wei Zhiyi; Zhang Ping; Li Yikun; Jiang Xiaohua; Xu Hang Gong Weimin

    2007-11-30

    Homoserine O-acetyltransferase (HTA, EC 2.3.1.31) initiates methionine biosynthesis pathway by catalyzing the transfer of acetyl group from acetyl-CoA to homoserine. This study reports the crystal structure of HTA from Leptospira interrogans determined at 2.2 A resolution using selenomethionyl single-wavelength anomalous diffraction method. HTA is modular and consists of two structurally distinct domains-a core {alpha}/{beta} domain containing the catalytic site and a helical bundle called the lid domain. Overall, the structure fold belongs to {alpha}/{beta} hydrolase superfamily with the characteristic 'catalytic triad' residues in the active site. Detailed structure analysis showed that the catalytic histidine and serine are both present in two conformations, which may be involved in the catalytic mechanism for acetyl transfer.

  3. Spatially and temporally continuous LAI datasets based on the mixed pixel decomposition method.

    PubMed

    Zhao, Jianjun; Wang, Yanying; Zhang, Hongyan; Zhang, Zhengxiang; Guo, Xiaoyi; Yu, Shan; Du, Wala

    2016-01-01

    The leaf area index (LAI) is a key biophysical parameter that determines the state of plant growth. A global LAI has been routinely produced by the Moderate Resolution Imaging Spectro-radiometer (MODIS) and Advanced Very High Resolution Radiometer (AVHRR). However, the MODIS and AVHRR LAI products cannot be synchronized with the same spatial and temporal resolution. The LAI features are not discernible when a global LAI product is implemented at the regional scale because it has low resolution and different land cover types. To obtain high spatial and temporal resolution of LAI products, an empirical model based on the pixel scale was developed. The approach to generate a long (multi-decade) time series of a 1-km spatial resolution LAI normally integrates both AVHRR and MODIS datasets for different land cover types. In this paper, a regression-based model for generating a vegetation LAI was developed using the AVHRR Global Inventory Modelling and Mapping Studies Normalized Difference Vegetation Index (NDVI), MODIS LAI and land cover as input data; the model was evaluated by using relevant data from the same period data from 2000 to 2006. The results of this method show a good consistency in LAI values retrieved from the AVHRR NDVI and MODIS LAI. This simple method has no specific-limited data requirements and can provide improved spatial and temporal resolution in a region without ground data. PMID:27186480

  4. Linking in situ LAI and fine resolution remote sensing data to map reference LAI over cropland and grassland using geostatistical regression method

    NASA Astrophysics Data System (ADS)

    He, Yaqian; Bo, Yanchen; Chai, Leilei; Liu, Xiaolong; Li, Aihua

    2016-08-01

    Leaf Area Index (LAI) is an important parameter of vegetation structure. A number of moderate resolution LAI products have been produced in urgent need of large scale vegetation monitoring. High resolution LAI reference maps are necessary to validate these LAI products. This study used a geostatistical regression (GR) method to estimate LAI reference maps by linking in situ LAI and Landsat TM/ETM+ and SPOT-HRV data over two cropland and two grassland sites. To explore the discrepancies of employing different vegetation indices (VIs) on estimating LAI reference maps, this study established the GR models for different VIs, including difference vegetation index (DVI), normalized difference vegetation index (NDVI), and ratio vegetation index (RVI). To further assess the performance of the GR model, the results from the GR and Reduced Major Axis (RMA) models were compared. The results show that the performance of the GR model varies between the cropland and grassland sites. At the cropland sites, the GR model based on DVI provides the best estimation, while at the grassland sites, the GR model based on DVI performs poorly. Compared to the RMA model, the GR model improves the accuracy of reference LAI maps in terms of root mean square errors (RMSE) and bias.

  5. Molecular characterization of the pL40 protein in Leptospira interrogans.

    PubMed

    Zhao, Wei; Chen, Chun-Yan; Zhang, Xiang-Yan; Lai, Wei-Qiang; Hu, Bao-Yu; Zhao, Guo-Ping; Qin, Jin-Hong; Guo, Xiao-Kui

    2009-06-01

    Leptospirosis is a widespread zoonotic disease caused by pathogenic leptospires. The identification of outer membrane proteins (OMPs) conserved among pathogenic leptospires, which are exposed on the leptospiral surface and expressed during mammalian infection, has become a major focus of leptospirosis research. pL40, a 40 kDa protein coded by the LA3744 gene in Leptospira interrogans, was found to be unique to Leptospira. Triton X-114 fractionation and flow cytometry analyses indicate that pL40 is a component of the leptospiral outer membrane. The conservation of pL40 among Leptospira strains prevalent in China was confirmed by both Western blotting and PCR screening. Furthermore, the pL40 antigen could be recognized by sera from guinea pigs and mice infected with low-passage L. interrogans. These findings indicate that pL40 may serve as a useful serodiagnostic antigen and vaccine candidate for L. interrogans. PMID:19767845

  6. Heterogenic colonization patterns by Leptospira interrogans in Rattus norvegicus from urban slums

    PubMed Central

    Santos, Ana Amélia Nunes; Figueira, Cláudio Pereira; dos Reis, Mitermayer Galvão; Costa, Federico; Ristow, Paula

    2015-01-01

    Abstract We evaluated the renal colonization by Leptospira interrogans in Rattus norvegicus (rats), as it is the major natural reservoir of urban leptospirosis. We caught 72 R. norvegicus, out of which 32 were found to be positive for L. interrogans by immunofluorescence assay. From these rats, we selected 17 and divided them into six groups based on the mass-age/sex. We performed the immunohistochemistry test against L. interrogans in the kidney sections of the rats and systematically counted the colonized tubules (CTs) in 20 fields. The proportion of positive fields varied from 5% to 95%. The number of CTs in 20 fields varied from 0.5 to 85.5. These differences were not related to age or sex of the animals. The characterization of leptospiral colonization patterns in the natural reservoirs is important to better understand the host-pathogen interactions in leptospirosis. PMID:26691476

  7. Heterogenic colonization patterns by Leptospira interrogans in Rattus norvegicus from urban slums.

    PubMed

    Santos, Ana Amélia Nunes; Figueira, Cláudio Pereira; dos Reis, Mitermayer Galvão; Costa, Federico; Ristow, Paula

    2015-01-01

    We evaluated the renal colonization by Leptospira interrogans in Rattus norvegicus (rats), as it is the major natural reservoir of urban leptospirosis. We caught 72 R. norvegicus, out of which 32 were found to be positive for L. interrogans by immunofluorescence assay. From these rats, we selected 17 and divided them into six groups based on the mass-age/sex. We performed the immunohistochemistry test against L. interrogans in the kidney sections of the rats and systematically counted the colonized tubules (CTs) in 20 fields. The proportion of positive fields varied from 5% to 95%. The number of CTs in 20 fields varied from 0.5 to 85.5. These differences were not related to age or sex of the animals. The characterization of leptospiral colonization patterns in the natural reservoirs is important to better understand the host-pathogen interactions in leptospirosis. PMID:26691476

  8. [Modified EMJH medium for cultivation of Leptospira interrogans serogroup ballum].

    PubMed

    González, A; Borrero, R; Ruiz, J; Batista, N; Fernández, Y; Valdés, Y; González, M

    2006-01-01

    Strains within the Ballum serogroup of spirochete Leptospira show fastidious growth with more exigent nutritional requirements than those of other Leptospira pathogenic strains. The influence of 37 nutritional compounds on the growth of Leptospira interrogans serogroup Ballum was investigated employing the synthetic EMJH medium as the base for the study. Microbial growth was estimated spectrophotometrically and direct counts were performed with a Petroff-Hausser counting chamber. Virulence stability was evaluated by calculating the mean lethal dose in hamsters. Antigenicity stability was evaluated by Western blotting using a specific antiserum. Cell yields commonly obtained in EMJH were triplicated without virulence or antigenicity depletions after culturing in a modified EMJH medium with an increased concentration of Tween 80, and the incorporation of sodium acetate and beef extract. Neither the increased concentration of at least 6 components of EMJH nor the incorporation of a variety of new nutrients stimulated cell yields or the growth rate of the microorganism. The results allow us to make use of an enriched culture medium that promotes high cell yields of this fastidious serogroup most prevalent in humans in Cuba. PMID:17037250

  9. Leptospira interrogans survey by PCR in wild rodents coming from different urban areas of Palermo, Italy.

    PubMed

    Vitale, Maria; Di Bella, Carobelo; Agnello, Stefano; Curro, Victoria; Vicari, Domenico; Vitale, Fabrizio

    2007-01-01

    DNA extracted from the kidneys of rodents captured in different urban areas of Palermo, Italy, had been analysed for the presence of pathogenic L. interrogans sensu latu DNA. PCR analysis had shown that in rodents captured close to green areas and small river up to 40 % animals give positive PCR results. Not many cases of human leptospirosis are reported in Sicilian island in which hot season is usually dry. But considering climate change toward subtropical aspect in Sicily, with hot humid summer and sudden thunderstorm, screening for L. interrogans sensu latu prevalence can be useful for leptospirosis risk analysis on human population. PMID:23427420

  10. Aboveground biomass and leaf area index (LAI) mapping for Niassa Reserve, northern Mozambique

    NASA Astrophysics Data System (ADS)

    Ribeiro, Natasha S.; Saatchi, Sassan S.; Shugart, Herman H.; Washington-Allen, Robert A.

    2008-09-01

    Estimations of biomass are critical in miombo woodlands because they represent the primary source of goods and services for over 80% of the population in southern Africa. This study was carried out in Niassa Reserve, northern Mozambique. The main objectives were first to estimate woody biomass and Leaf Area Index (LAI) using remotely sensed data [RADARSAT (C-band, λ = 5.7-cm)] and Landsat ETM+ derived Normalized Difference Vegetation Index (NDVI) and Simple Ratio (SR) calibrated by field measurements and, second to determine, at both landscape and plot scales, the environmental controls (precipitation, woody cover density, fire and elephants) of biomass and LAI. A land-cover map (72% overall accuracy) was derived from the June 2004 ETM+ mosaic. Field biomass and LAI were correlated with RADARSAT backscatter (rbiomass = 0.65, rLAI = 0.57, p < 0.0001) from July 2004, NDVI (rbiomass = 0.30, rLAI = 0.35; p < 0.0001) and SR (rbiomass = 0.36, rLAI = 0.40, p < 0.0001). A jackknife stepwise regression technique was used to develop the best predictive models for biomass (biomass = -5.19 + 0.074 * radarsat + 1.56 * SR, r2 = 0.55) and LAI (LAI = -0.66 + 0.01 * radarsat + 0.22 * SR, r2 = 0.45). Biomass and LAI maps were produced with an estimated peak of 18 kg m-2 and 2.80 m2 m-2, respectively. On the landscape-scale, both biomass and LAI were strongly determined by mean annual precipitation (F = 13.91, p = 0.0002). On the plot spatial scale, woody biomass was significantly determined by fire frequency, and LAI by vegetation type.

  11. Isotopic Anomalies in a Uranium Cluster Formed by Lais

    NASA Astrophysics Data System (ADS)

    van de Walle, J.; Tarento, R. J.; Joyes, P.

    A study of a Au-U liquid alloy ion source (LAIS) where uranium is enriched in its lighter element (20% 235U, 80% 238U) has been performed by high resolution mass spectrometry. Monoatomic species Au+, Au2+, U2+, U3+ and polyatomic species Au+n, Up+n, AunU+ are observed. The monoatomic results are well explained by the Kingham postionization process. Au+n and AunU+ species present an interesting odd-even effect characteristic of monovalent elements. The main result of this preliminary letter is a heteroisotope anomaly which appears in U+2, U+3 and U4+3 emission where only homoisotopes are detected. A similar phenomenon was reported for Cu+2 and Ge+2 in a previous work and was attributed to a higher state of excitation of emitted heteroisotope aggregates which explode as they fly to the collector.1,2

  12. Transcriptional response of Leptospira interrogans to iron limitation and characterization of a PerR homolog

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Leptospira interrogans is the causative agent of leptospirosis, a zoonosis of global significance. Iron is essential for growth of most bacterial species. Since availability of iron is low in the host, pathogens have evolved complex iron acquisition mechanisms to survive and establish infection. In ...

  13. Relationship between LAI and Landsat TM spectral vegetation indices in the Texas Panhandle

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Mapping and monitoring leaf area index (LAI) is important for spatially distributed modeling of surface energy balance, evapotranspiration and vegetation productivity. Remote sensing can facilitate the rapid collection of LAI information on individual fields over large areas in a time and cost-effec...

  14. Application and Evaluation of MODIS LAI, fPAR, and Albedo Products in the WRFCMAQ System

    EPA Science Inventory

    Leaf area index (LAI), vegetation fraction (VF), and surface albedo are important parameters in the land surface model (LSM) for meteorology and air quality modeling systems such as WRF/CMAQ. LAI and VF control not only leaf to canopy level evapotranspiration flux scaling but al...

  15. Comparing LAI estimates of corn and soybean from vegetation indices of multi-resolution satellite images

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Leaf area index (LAI) is important in explaining the ability of the crop to intercept solar energy for biomass production and in understanding the impact of crop management practices. This paper describes a procedure for estimating LAI as a function of image-derived vegetation indices from temporal ...

  16. Jointly assimilating MODIS LAI and ET products into SWAP model for winter wheat yield estimation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Leaf Area Index (LAI) and Evapotranspiration (ET) are two key biophysical variables related to crop growth and grain yield. This study presents a framework to assimilate MODIS LAI products (MCD15A3) and MODIS ET products (MOD16A2) into the soil water atmosphere plant (SWAP) model to improve estimate...

  17. Sensitivity analysis for leaf area index (LAI) estimation from CHRIS/PROBA data

    NASA Astrophysics Data System (ADS)

    Cao, Jianjun; Gu, Zhujun; Xu, Jianhua; Duan, Yushan; Liu, Yongmei; Liu, Yongjuan; Li, Dongliang

    2014-09-01

    Sensitivity analyses were conducted for the retrieval of vegetation leaf area index (LAI) from multiangular imageries in this study. Five spectral vegetation indices (VIs) were derived from Compact High Resolution Imaging Spectrometer onboard the Project for On Board Autonomy (CHRIS/PROBA) images, and were related to LAI, acquired from in situ measurement in Jiangxi Province, China, for five vegetation communities. The sensitivity of LAI retrieval to the variation of VIs from different observation angles was evaluated using the ratio of the slope of the best-fit linear VI-LAI model to its root mean squared error. Results show that both the sensitivity and reliability of VI-LAI models are influenced by the heterogeneity of vegetation communities, and that performance of vegetation indices in LAI estimation varies along observation angles. The VI-LAI models are more reliable for tall trees than for low growing shrub-grasses and also for forests with broad leaf trees than for coniferous forest. The greater the tree height and leaf size, the higher the sensitivity. Forests with broad-leaf trees have higher sensitivities, especially at oblique angles, while relatively simple-structured coniferous forests, shrubs, and grasses show similar sensitivities at all angles. The multi-angular soil and/or atmospheric parameter adjustments will hopefully improve the performance of VIs in LAI estimation, which will require further investigation.

  18. Assessment of MODIS LAI retrievals over soybean crop in Southern Brazil

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This paper examines the magnitude of the Collection 4 MODIS leaf area index (LAI) product for the soybean crop for two crop seasons, 2001/2002 to 2004/2005, in Southern Brazil. The data indicated that there were a large proportion of digical counts were at a maximum level suggesting that the LAI was...

  19. Towards an Improved LAI Collection Protocol via Simulated and Field-Based PAR Sensing

    PubMed Central

    Yao, Wei; Kelbe, David; van Leeuwen, Martin; Romanczyk, Paul; van Aardt, Jan

    2016-01-01

    In support of NASA’s next-generation spectrometer—the Hyperspectral Infrared Imager (HyspIRI)—we are working towards assessing sub-pixel vegetation structure from imaging spectroscopy data. Of particular interest is Leaf Area Index (LAI), which is an informative, yet notoriously challenging parameter to efficiently measure in situ. While photosynthetically-active radiation (PAR) sensors have been validated for measuring crop LAI, there is limited literature on the efficacy of PAR-based LAI measurement in the forest environment. This study (i) validates PAR-based LAI measurement in forest environments, and (ii) proposes a suitable collection protocol, which balances efficiency with measurement variation, e.g., due to sun flecks and various-sized canopy gaps. A synthetic PAR sensor model was developed in the Digital Imaging and Remote Sensing Image Generation (DIRSIG) model and used to validate LAI measurement based on first-principles and explicitly-known leaf geometry. Simulated collection parameters were adjusted to empirically identify optimal collection protocols. These collection protocols were then validated in the field by correlating PAR-based LAI measurement to the normalized difference vegetation index (NDVI) extracted from the “classic” Airborne Visible Infrared Imaging Spectrometer (AVIRIS-C) data (R2 was 0.61). The results indicate that our proposed collecting protocol is suitable for measuring the LAI of sparse forest (LAI < 3–5 (m2/m2)). PMID:27428969

  20. Estimating leaf area index from Landsat using MODIS LAI products and field measurements as reference

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Leaf area index (LAI) is a key biophysical parameter used in most land surface models. Operationally, LAI products currently used typically come from coarse resolution sensors such as the Moderate Resolution Imaging Spectroradiometer (MODIS). While coarse resolution data at the kilometer scale are o...

  1. A simple method for retrieving leaf area index from landsat using MODIS LAI products as reference

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Leaf Area Index (LAI) is a key parameter in most land surface models. Models that operate at multiple spatial scales may require consistent LAI inputs at different spatial resolutions or from different sensors. For example, the Atmosphere-Land Exchange Inverse (ALEXI) model and associated disaggrega...

  2. Towards an improved LAI collection protocol via simulated field-based PAR sensing

    DOE PAGESBeta

    Yao, Wei; Van Leeuwen, Martin; Romanczyk, Paul; van Aardt, Jan; Kelbe, David

    2016-07-14

    In support of NASA’s next-generation spectrometer—the Hyperspectral Infrared Imager (HyspIRI)—we are working towards assessing sub-pixel vegetation structure from imaging spectroscopy data. Of particular interest is Leaf Area Index (LAI), which is an informative, yet notoriously challenging parameter to efficiently measure in situ. While photosynthetically-active radiation (PAR) sensors have been validated for measuring crop LAI, there is limited literature on the efficacy of PAR-based LAI measurement in the forest environment. This study (i) validates PAR-based LAI measurement in forest environments, and (ii) proposes a suitable collection protocol, which balances efficiency with measurement variation, e.g., due to sun flecks and various-sized canopymore » gaps. A synthetic PAR sensor model was developed in the Digital Imaging and Remote Sensing Image Generation (DIRSIG) model and used to validate LAI measurement based on first-principles and explicitly-known leaf geometry. Simulated collection parameters were adjusted to empirically identify optimal collection protocols. Furthermore, these collection protocols were then validated in the field by correlating PAR-based LAI measurement to the normalized difference vegetation index (NDVI) extracted from the “classic” Airborne Visible Infrared Imaging Spectrometer (AVIRIS-C) data (R2 was 0.61). The results indicate that our proposed collecting protocol is suitable for measuring the LAI of sparse forest (LAI < 3–5 ( m2/m2)).« less

  3. Retrieving leaf area index from landsat using MODIS LAI products and field measurements

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A simple reference-based approach has been developed for retrieving leaf area index (LAI) from Landsat imagery. The approach uses homogeneous and high quality LAI retrievals from the moderate resolution imaging spectroradiometer (MODIS) as reference to develop a regression tree relating these MODIS ...

  4. Retrieving LAI from Remotely Sensed Images: Spectral Indices vs. Spatial Texture

    NASA Astrophysics Data System (ADS)

    Song, C.; Gray, J. M.; Zhang, S.

    2008-12-01

    Leaves are the interface where energy and gas exchanges between the atmosphere and forest ecosystems occur. Accurate knowledge of the amount leaves is essential to successfully modeling the fluxes of water and carbon through the earth's forests. Leaf area index (LAI) is a parameter used to quantify the abundance of leaves in a given stand. Remote sensing offers the only feasible way to quantify LAI over large areas. Tremendous efforts have been devoted to this task by remote sensing scientists, but there is still a lack of concensus on how LAI can be best retrieved. Though global LAI products are available, their accuracy has remained unsatisfactory for regional applications. Previous work has primarily focused on using the spectral information in remotely sensed imagery. In this study, we compared the potential of LAI retrieval from various spectral indices derived from Landsat TM images with retrieval using the spatial information, image texture, derived from the Ikonos images. LAI on the ground was derived from allometry, LAI-2000 and the TRAC device in the Duke Forest area in central North Carolina. Our results show that the commonly used spectral indices, normalized difference vegetation index (NDVI) and simple ratio vegetation index (SRVI) were not the best choice for LAI retrieval. We found that Landsat TM derived Structural Index (SI=TM4/TM5) and normalized difference water index (NDWI), as well as Ikonos image texture are much better alternatives.

  5. Towards an Improved LAI Collection Protocol via Simulated and Field-Based PAR Sensing.

    PubMed

    Yao, Wei; Kelbe, David; Leeuwen, Martin van; Romanczyk, Paul; Aardt, Jan van

    2016-01-01

    In support of NASA's next-generation spectrometer-the Hyperspectral Infrared Imager (HyspIRI)-we are working towards assessing sub-pixel vegetation structure from imaging spectroscopy data. Of particular interest is Leaf Area Index (LAI), which is an informative, yet notoriously challenging parameter to efficiently measure in situ. While photosynthetically-active radiation (PAR) sensors have been validated for measuring crop LAI, there is limited literature on the efficacy of PAR-based LAI measurement in the forest environment. This study (i) validates PAR-based LAI measurement in forest environments, and (ii) proposes a suitable collection protocol, which balances efficiency with measurement variation, e.g., due to sun flecks and various-sized canopy gaps. A synthetic PAR sensor model was developed in the Digital Imaging and Remote Sensing Image Generation (DIRSIG) model and used to validate LAI measurement based on first-principles and explicitly-known leaf geometry. Simulated collection parameters were adjusted to empirically identify optimal collection protocols. These collection protocols were then validated in the field by correlating PAR-based LAI measurement to the normalized difference vegetation index (NDVI) extracted from the "classic" Airborne Visible Infrared Imaging Spectrometer (AVIRIS-C) data ( R 2 was 0.61). The results indicate that our proposed collecting protocol is suitable for measuring the LAI of sparse forest (LAI < 3-5 ( m 2 / m 2 )). PMID:27428969

  6. The effect of land cover heterogeneity of MODIS pixel on canopy LAI estimation

    NASA Astrophysics Data System (ADS)

    Manninen, T.; Puttonen, N.

    2012-04-01

    The boreal zone land cover has a very significant influence on the northern hemisphere albedo and is an important component of the northern hemisphere carbon budget. Both albedo and the leaf area index (LAI) are one of the most important biophysical vegetation parameters and belong to the Essential Climate Variables (ECV) . In addition, in winter time the boreal forest albedo is a complicated combination of snow and canopy radiative properties, so that the albedo is a function of the canopy LAI. One possibility to estimate LAI using optical satellite data is by determination of spectral vegetation indices (SVIs), such as the reduced simple ratio (RSR). It uses the visible near infrared and short wave infrared channels. In large areas moderate resolution instruments, like MODIS, are suitable for LAI mapping. Yet, the heterogeneity of land cover in many boreal areas, for example in Finland, causes a challenge for LAI estimation. This effect was studied using several Landsat and MODIS images and the high resolution CORINE land cover map covering the same area in various parts of Finland. The atmospheric correction of the Landsat images was adjusted so that each MODIS pixel reflectance matched the average of the Landsat pixel reflectances within the MODIS pixel. The LAI values for Landsat and MODIS images were then determined using the RSR index. The LAI average of forested Landsat pixels was compared to the corresponding MODIS pixel LAI as a function of open water area fraction in the MODIS pixel. A regression function was determined to derive a method to correct the MODIS based LAI values with the open water area fraction. It turned out that the existence of open water in the MODIS pixels reduces the determined canopy LAI value on the average 30%. Also other land cover classes affect the LAI value, but the effect of water is largest, because the reflectance of water deviates so much from that of the canopy. The canopy LAI map of whole Finland was then calculated

  7. Evaluation of MODIS-LAI products in the tropical dry secondary forest of Mata Seca, Minas Gerais, Brazil

    NASA Astrophysics Data System (ADS)

    Yamarte Loreto, Payri Alejandra

    Leaf Area Index (LAI) advances scientific knowledge of the role of secondary forests in forest area conservation. MODIS-LAI products provide an alternative, efficient and cost-effective method for measuring LAI in Tropical Dry Forests (TDFs). The performance of MODIS-LAI satellite products in a TDF was studied as a function of successional stages by (1) estimating seasonal LAI variations compared to in situ LAI values (2) using dry season MODIS-LAI products to estimate Woody Area Index (WAI) (3) estimating phenology changes through comparisons to in situ data. The study demonstrates (1) MODIS-LAI product showed agreement with in situ values with increasing successional stage. (2) MODIS-LAI product showed best agreement to in situ WAI values in the intermediate successional stage. (3) TIMESAT analysis indicated that MODIS-LAI products detected start-of-season 1-2 weeks before in situ values and end-of-season 20-30 days after in situ values, indicating that MODIS-LAI product captures canopy leafing, but is not suitable for detecting senescence. Keywords: Leaf Area Index, Validation, MODIS, Woody Area Index, Phenology, Tropical Secondary Forest Succession, Hemispherical Photography, LAI-2000,.

  8. Deriving Leaf Area Index (LAI) from multiple lidar remote sensing systems

    NASA Astrophysics Data System (ADS)

    Tang, H.; Dubayah, R.; Zhao, F.

    2012-12-01

    LAI is an important biophysical variable linking biogeochemical cycles of earth systems. Observations with passive optical remote sensing are plagued by saturation and results from different passive and active sensors are often inconsistent. Recently lidar remote sensing has been applied to derive vertical canopy structure including LAI and its vertical profile. In this research we compare LAI retrievals from three different types of lidar sensors. The study areas include the La Selva Biological Station in Costa Rica and Sierra Nevada Forest in California. We first obtain independent LAI estimates from different lidar systems including airborne lidar (LVIS), spaceborne lidar (GLAS) and ground lidar (Echidna). LAI retrievals are then evaluated between sensors as a function of scale, land cover type and sensor characteristics. We also assess the accuracy of these LAI products against ground measurements. By providing a link between ground observations, ground lidar, aircraft and space-based lidar we hope to demonstrate a path for deriving more accurate estimates of LAI on a global basis, and to provide a more robust means of validating passive optical estimates of this important variable.

  9. [LAI-based regional winter wheat yield estimation by remote sensing].

    PubMed

    Ren, Jian-qiang; Chen, Zhong-xin; Zhou, Qing-bo; Tang, Hua-jun

    2010-11-01

    By using retrieved LAI from remotely-sensed imagery, this paper studied the regional winter wheat yield estimation in Huanghuaihai Plain of North China. In order to improve the quality of remotely sensed data for winter wheat yield estimation, a Savitzky-Golay filter was used to smooth the MODIS-NDVI time series data to reduce the cloud contamination and remove the abnormal data. Then, a Gaussian model was used to simulate the daily crop LAI which was corrected by interpolating the measured LAI to get the average LAI values for each phenological stage. Using these LAI data, the relationships between LAI and crop yield at the main phenological stages of winter wheat was established. After optimizing the yield estimation model, the optimal time period and the best model parameters for winter wheat yield estimation in the study area were selected out. Finally, the established model was applied to estimate winter wheat yield based on the retrieved LAI from MODIS-NDVI, and the model accuracy was tested. Through the comparison of the predicted yield with the measured yield in the field, the mean relative error was 1.21%, and the RMSE was 257.33 kg x hm(-2). The model and the method proposed in this study were promising, and could help to get the accurate estimated yield of winter wheat in about 20-30 days ahead of the harvest. PMID:21361014

  10. LAI Calculated from High-Resolution Imagery: Accounting for Water Tracks

    NASA Astrophysics Data System (ADS)

    Trochim, E.; Mumm, J. P.; Prakash, A.; Kane, D. L.

    2012-12-01

    Leaf Area Index (LAI) is fundamental for calculations of primary productivity, energy balance, evapotranspiration and biogeochemical cycling. Remote estimations in the Arctic are critical to cover large areas efficiently to understand current processes and predict the effects of climate change. LAI is defined as the total one-sided area of leaves per unit ground area. In the Arctic, previous efforts have concentrated on correlating direct methods of calculating LAI with indices that can be derived through remotely sensed imagery, including the Normalized Difference Vegetation Index (NDVI) and Enhanced Vegetation Index (EVI). In this study we use LAI measurements to explore the significant relationship between soil moisture and LAI values in and around water tracks. Water tracks are saturated linear-curvilinear features which make up the majority of the drainage network in the Imnavait, Toolik and Upper Kuparuk basins. In early July 2010 ground based transects consisting of 2 m2 plots in and around water tracks documented vegetation percent cover, soil morphology, and visible and near IR imagery. A threshold was applied to each plot to calculate fractional cover and converted to LAI based on Beer-Lambert's law. This was compared to multispectral WorldView 2 data with a 2.3 m spatial resolution collected on July 2, 4 and 10 in 2010. The imagery was converted to reflectance using ATCOR, and NDVI and EVI were calculated. LAI was computed using known relationships developed in the area between these indices. Fractional cover based on NDVI, EVI and the red edge band (705 to 745 nm) were also used to estimate LAI. The variation between these values was compared against the ground based imagery and analyzed using a two-way repeated measures statistical test. This technique illustrated the significant difference in LAI values between water track and non-water track areas which has not been explicitly documented before. It also was able to shed light on the confounding

  11. Development of regional wheat VI-LAI models using Resourcesat-1 AWiFS data

    NASA Astrophysics Data System (ADS)

    Chaurasia, Sasmita; Nigam, R.; Bhattacharya, B. K.; Sridhar, V. N.; Mallick, K.; Vyas, S. P.; Patel, N. K.; Mukherjee, J.; Shekhar, Chander; Kumar, Dhiraj; Singh, K. R. P.; Bairagi, G. D.; Purohit, N. L.; Parihar, J. S.

    2011-12-01

    The time of forcing of spatial LAI to crop models at single or multiple stages is important to simulate crop biomass and yield in varying agro-climatic conditions and scales. The high temporal resolution (5-day) by Advanced Wide Field Sensor (AWiFS) on-board Resourcesat-1 Satellite IRS-P6 with 56 m spatial resolution and large swath (740 km) has substantially increased the availability of regional clear sky optical remote sensing data. The present study aimed at developing empirical vegetation index VI-LAI models for wheat using AWiFS optical data in four bands and in-situ measurements sampled over five different agro-climatic regions (ACRs) during 2005-2006 followed by validation during 2006-2007. While nonlinear relations exist for all the three normalized indices such as normalized difference vegetation index (NDVI), normalized difference water index (NDWI) and Green NDVI, linear relation was the best fit for ratio vegetation index (RVI). Both NDVI and RVI models generally showed better correlation ranges (0.65-0.84 for NDVI and 0.37-0.76 for RVI) than other indices. The common NDVI-LAI model was found to produce lower root mean square errors (RMSE) between 0.5 and 1.1 from pooled model than those between 0.5 and 1.32 from regional models. The rate of substantial increase in errors from NDVI-LAI model (RMSE of modeled LAI: 0.85 to 1.28) as compared to RVI-LAI model (RMSE of modeled LAI: 1.12 to 1.17) at LAI greater than 3, than below 3 revealed the early saturation of NDVI than RVI. It is therefore recommended that LAI estimates can be used to force crop simulation model upto early vegetative stage based on NDVI and maximum vegetative to reproductive stages based on RVI.

  12. Estimating forest LAI profiles and structural parameters using a ground-based laser called 'Echidna'.

    PubMed

    Jupp, David L B; Culvenor, D S; Lovell, J L; Newnham, G J; Strahler, A H; Woodcock, C E

    2009-02-01

    There are many techniques for measuring leaf area index (LAI) and forest canopy foliage profiles but their accuracy is questionable. This paper briefly reviews current methods of estimating forest LAI and presents a novel, ground-based laser system, Echidna that can make a wide range of measurements of forest structure, including LAI. Here, use of the system to provide field data and derived gap probabilities in the form of a 'hemispherical photograph with range' is demonstrated. The results show consistency and reproducibility and do not depend on special conditions for the natural light field. PMID:19203942

  13. Constructing seasonal LAI trajectory by data-model fusion for global evergreen needle-leaf forests

    NASA Astrophysics Data System (ADS)

    Wang, R.; Chen, J.; Mo, G.

    2010-12-01

    For decades, advancements in optical remote sensors made it possible to produce maps of a biophysical parameter--the Leaf Area Index (LAI), which is critically necessary in regional and global modeling of exchanges of carbon, water, energy and other substances, across large areas in a fast way. Quite a few global LAI products have been generated since 2000, e.g. GLOBCARBON (Deng et al., 2006), MODIS Collection 5 (Shabanov et al., 2007), CYCLOPES (Baret et al., 2007), etc. Albeit these progresses, the basic physics behind the technology restrains it from accurate estimation of LAI in winter, especially for northern high-latitude evergreen needle-leaf forests. Underestimation of winter LAI in these regions has been reported in literature (Yang et al., 2000; Cohen et al., 2003; Tian et al., 2004; Weiss et al., 2007; Pisek et al., 2007), and the distortion is usually attributed to the variations of canopy reflectance caused by understory change (Weiss et al., 2007) as well as by the presence of ice and snow on leaves and ground (Cohen, 2003; Tian et al., 2004). Seasonal changes in leaf pigments can also be another reason for low LAI retrieved in winter. Low conifer LAI values in winter retrieved from remote sensing make them unusable for surface energy budget calculations. To avoid these drawbacks of remote sensing approaches, we attempt to reconstruct the seasonal LAI trajectory through model-data fusion. A 1-degree LAI map of global evergreen needle-leaf forests at 10-day interval is produced based on the carbon allocation principle in trees. With net primary productivity (NPP) calculated by the Boreal Ecosystems Productivity Simulator (BEPS) (Chen et al., 1999), carbon allocated to needles is quantitatively evaluated and then can be further transformed into LAI using the specific leaf area (SLA). A leaf-fall scheme is developed to mimic the carbon loss caused by falling needles throughout the year. The seasonally maximum LAI from remote sensing data for each pixel

  14. Salmonella enterica: Survival, Colonization, and Virulence Differences among Serovars

    PubMed Central

    Andino, A.; Hanning, I.

    2015-01-01

    Data indicate that prevalence of specific serovars of Salmonella enterica in human foodborne illness is not correlated with their prevalence in feed. Given that feed is a suboptimal environment for S. enterica, it appears that survival in poultry feed may be an independent factor unrelated to virulence of specific serovars of Salmonella. Additionally, S. enterica serovars appear to have different host specificity and the ability to cause disease in those hosts is also serovar dependent. These differences among the serovars may be related to gene presence or absence and expression levels of those genes. With a better understanding of serovar specificity, mitigation methods can be implemented to control Salmonella at preharvest and postharvest levels. PMID:25664339

  15. Collection of LAI and FPAR Data Over The Terra Core Sites

    NASA Technical Reports Server (NTRS)

    Myneni, Ranga B.; Knjazihhin, J.; Tian, Y.; Wang, Y.

    2001-01-01

    The objective of our effort was to collect and archive data on LAI (leaf area index) and FPAR (Fraction of Photosynthetically active Radiation absorbed by vegetation) at the EOS Core validation sites as well as to validate and evaluate global fields of LAI and FPAR derived from atmospherically corrected MODIS (Moderate Resolution Imaging Spectrometer) surface reflectance data by comparing these fields with the EOS Core validation data set. The above has been accomplished by: (a) the participation in selected field campaigns within the EOS Validation Program; (b) the processing of the collected data so that suitable comparison between field measurements and the MODIS LAI/FPAR fields can be made; (c) the comparison of the MODAS LAI/FRAM fields with the EOS Terra Core validation data set.

  16. ASSESSMENT OF MODIS LAI (W4) IN LOBLOLLY PINE (P. TAEDA) FOREST TYPE, APPOMATTOX, VIRGINIA

    EPA Science Inventory

    The United States Environmental Protection Agency initiated MODIS MODI5A2LAI validation research (2002) in the evergreen needle leaf biome, as defined in the MOD12 classification, in a regional study located in the southeastern United States.

  17. A New Global LAI Product and Its Use for Terrestrial Carbon Cycle Estimation

    NASA Astrophysics Data System (ADS)

    Chen, J. M.; Liu, R.; Ju, W.; Liu, Y.

    2014-12-01

    For improving the estimation of the spatio-temporal dynamics of the terrestrial carbon cycle, a new time series of the leaf area index (LAI) is generated for the global land surface at 8 km resolution from 1981 to 2012 by combining AVHRR and MODIS satellite data. This product differs from existing LAI products in the following two aspects: (1) the non-random spatial distribution of leaves with the canopy is considered, and (2) the seasonal variation of the vegetation background is included. The non-randomness of the leaf spatial distribution in the canopy is considered using the second vegetation structural parameter named clumping index (CI), which quantifies the deviation of the leaf spatial distribution from the random case. Using the MODIS Bidirectional Reflectance Distribution Function product, a global map of CI is produced at 500 m resolution. In our LAI algorithm, CI is used to convert the effective LAI obtained from mono-angle remote sensing into the true LAI, otherwise LAI would be considerably underestimated. The vegetation background is soil in crop, grass and shrub but includes soil, grass, moss, and litter in forests. Through processing a large volume of MISR data from 2000 to 2010, monthly red and near-infrared reflectances of the vegetation background is mapped globally at 1 km resolution. This new LAI product has been validated extensively using ground-based LAI measurements distributed globally. In carbon cycle modeling, the use of CI in addition to LAI allows for accurate separation of sunlit and shaded leaves as an important step in terrestrial photosynthesis and respiration modeling. Carbon flux measurements over 100 sites over the globe are used to validate an ecosystem model named Boreal Ecosystem Productivity Simulator (BEPS). The validated model is run globally at 8 km resolution for the period from 1981 to 2012 using the LAI product and other spatial datasets. The modeled results suggest that changes in vegetation structure as quantified

  18. Quantification winter wheat LAI with HJ-1CCD image features over multiple growing seasons

    NASA Astrophysics Data System (ADS)

    Li, Xinchuan; Zhang, Youjing; Luo, Juhua; Jin, Xiuliang; Xu, Ying; Yang, Wenzhi

    2016-02-01

    Remote sensing images are widely used to map leaf area index (LAI) continuously over landscape. The objective of this study is to explore the ideal image features from Chinese HJ-1 A/B CCD images for estimating winter wheat LAI in Beijing. Image features were extracted from such images over four seasons of winter wheat growth, including five vegetation indices (VIs), principal components (PC), tasseled cap transformations (TCT) and texture parameters. The LAI was significantly correlated with the near-infrared reflectance band, five VIs [normalized difference vegetation index, enhanced vegetation index (EVI), modified nonlinear vegetation index (MNLI), optimization of soil-adjusted vegetation index, and ratio vegetation index], the first principal component (PC1) and the second TCT component (TCT2). However, these image features cannot significantly improve the estimation accuracy of winter wheat LAI in conjunction with eight texture measures. To determine the few ideal features with the best estimation accuracy, partial least squares regression (PLSR) and variable importance in projection (VIP) were applied to predict LAI values. Four remote sensing features (TCT2, PC1, MNLI and EVI) were chosen based on VIP values. The result of leave-one-out cross-validation demonstrated that the PLSR model based on these four features produced better result than the ten features' model, throughout the whole growing season. The results of this study suggest that selecting a few ideal image features is sufficient for LAI estimation.

  19. Space-time LAI variability in Northern Puglia (Italy) from SPOT VGT data.

    PubMed

    Balacco, Gabriella; Figorito, Benedetto; Tarantino, Eufemia; Gioia, Andrea; Iacobellis, Vito

    2015-07-01

    The vegetation space-time variability during 1999-2010 in the North of the Apulian region (Southern Italy) was analysed using SPOT VEGETATION (VGT) sensor data. Three bands of VEGETATION (RED, NIR and SWIR) were used to implement the vegetation index named reduced simple ratio (RSR) to derive leaf area index (LAI). The monthly average LAI is an indicator of biomass and canopy cover, while the difference between the annual maximum and minimum LAI is an indicator of annual leaf turnover. The space-time distribution of LAI at the catchment scale was analysed over the examined period to detect the consistency of vegetation dynamics in the study area. A diffuse increase of LAI was observed in the examined years that cannot be directly explained only in terms of increasing water availability. Thus, in order to explain such a general behaviour in terms of climatic factors, the analysis was performed upon stratification of land cover classes, focusing on the most widespread species: forest and wheat. An interesting ascending-descending behaviour was observed in the relationship between inter-annual increments of maximum LAI and rainfall, and in particular, a strong negative correlation was found when the rainfall amount in January and February exceeded a critical threshold of about 100 mm. PMID:26077022

  20. Egg contamination by Salmonella serovar enteritidis following vaccination with Delta-aroA Salmonella serovar typhimurium.

    PubMed

    Parker, C; Asokan, K; Guard-Petter, J

    2001-02-01

    The efficacy of an aroA Salmonella serovar typhimurium modified live vaccine to decrease internal egg contamination after oral challenge of hens with egg-contaminating Salmonella serovar enteritidis was assessed. Challenge was with a mixed phenotype of S. enteritidis that had virulence characteristics previously associated with enhanced oral invasiveness and egg contamination in chickens. Immunized birds had fewer positive ovary/oviduct pools and lower cfu g(-1) cecal contents than did non-immunized birds, but the differences were not significant. The number of positive intestinal (duodenum, jejunum, ileum) and organ (spleen, kidney, liver) pools following challenge from each treatment group were equivalent. Most importantly, immunization did not decrease egg contamination. These results suggest that the ability of modified live vaccines to reduce internal egg contamination by S. serovar enteritidis can be assessed using characterized strains for challenge. PMID:11166998

  1. Retrieval of Vertical LAI Profiles Over Tropical Rain Forests using Waveform Lidar at La Selva, Costa Rica

    NASA Technical Reports Server (NTRS)

    Tang, Hao; Dubayah, Ralph; Swatantra, Anu; Hofton, Michelle; Sheldon, Sage; Clark, David B.; Blair, Bryan

    2012-01-01

    This study explores the potential of waveform lidar in mapping the vertical and spatial distributions of leaf area index (LAI) over the tropical rain forest of La Selva Biological Station in Costa Rica. Vertical profiles of LAI were derived at 0.3 m height intervals from the Laser Vegetation Imaging Sensor (LVIS) data using the Geometric Optical and Radiative Transfer (GORT) model. Cumulative LAI profiles obtained from LVIS were validated with data from 55 ground to canopy vertical transects using a modular field tower to destructively sample all vegetation. Our results showed moderate agreement between lidar and field derived LAI (r2=0.42, RMSE=1.91, bias=-0.32), which further improved when differences between lidar and tower footprint scales (r2=0.50, RMSE=1.79, bias=0.27) and distance of field tower from lidar footprint center (r2=0.63, RMSE=1.36, bias=0.0) were accounted for. Next, we mapped the spatial distribution of total LAI across the landscape and analyzed LAI variations over different land cover types. Mean values of total LAI were 1.74, 5.20, 5.41 and 5.62 over open pasture, secondary forests, regeneration forests after selective-logging and old-growth forests respectively. Lastly, we evaluated the sensitivities of our LAI retrieval model to variations in canopy/ground reflectance ratio and to waveform noise such as induced by topographic slopes. We found for both, that the effects were not significant for moderate LAI values (about 4). However model derivations of LAI might be inaccurate in areas of high-slope and high LAI (about 8) if ground return energies are low. This research suggests that large footprint waveform lidar can provide accurate vertical LAI profile estimates that do not saturate even at the high LAI levels in tropical rain forests and may be a useful tool for understanding the light transmittance within these canopies.

  2. Salmonella Serovars in the Herpetofauna of Indiana County, Pennsylvania

    PubMed Central

    Chambers, David L.; Hulse, Arthur C.

    2006-01-01

    Herpetofaunal Salmonella enterica serovars have not been fully examined in any U.S. region. Thirty-three Salmonella serovars were isolated from 156 samples from 34 species, all within Indiana County, Pennsylvania. Results suggest that herpetofaunas could potentially pose a threat to humans. Further understanding of Salmonella in herpetofaunas may prevent future human cases. PMID:16672533

  3. Genome Sequences of Five Nonvirulent Listeria monocytogenes Serovar 4 Strains

    PubMed Central

    Shen, Yang; Loessner, Martin J.

    2016-01-01

    We present the complete genome sequences of five nonpathogenic Listeria monocytogenes serovar 4 strains: WSLC 1018 (4e), 1019 (4c), 1020 (4a), 1033 (4d), and 1047 (4d). These sequences may help to uncover genes involved in the synthesis of the serovar antigens—phenotypic determinants of virulence deemed clinically relevant. PMID:27034489

  4. Multidrug-Resistant Salmonella enterica Serovar Infantis, Israel

    PubMed Central

    Valinsky, Lea; Weinberger, Miriam; Guy, Sara; Jaffe, Joseph; Schorr, Yosef Ilan; Raisfeld, Abraham; Agmon, Vered; Nissan, Israel

    2010-01-01

    To determine whether rapid emergence of Salmonella enterica serovar Infantis in Israel resulted from an increase in different biotypes or spread of 1 clone, we characterized 87 serovar Infantis isolates on the genotypic and phenotypic levels. The emerging strain comprised 1 genetic clone with a distinct pulsed-field gel electrophoresis profile and a common antimicrobial drug resistance pattern. PMID:21029536

  5. [Change of LAI and spectral response for rice under flood and waterlogging stress].

    PubMed

    Xu, Peng; Gu, Xiao-He; Meng, Lu-Min; Qiu, He; Wang, Hui-Fang

    2013-12-01

    In order to provide the foundational theoretical support for flood loss estimation of rice with RS, the change of leaf area index (LAI) and canopy spectral response during four developmental stages and three waterlogging depths were studied, and the LAI estimation model was established with spectra characteristics parameter using regression analysis method. The results show that LAI value decreases as water depth increases in tillering, jointing and heading stages, and LAI value under complete submergence decreased by 36. 36% than CK in jointing stages. "Double-Peak" presented in the canopy first derivative spectra of 680-760 nm where the red edge parameters existed, and the main peak is located in the 724-737 nm with 701 and 718 nm exhibiting secondary peak. With water depth increasing, "Triple-Peak" emerges especially. The red edge position moves to long-wavelength direction in each developmental stage. Blue shift of red edge amplitude and red edge area was detected in tillering, jointing and filling stages, while red shift appeared in heading stage. The relationship between spectra characteristics parameters and LAI were investigated during 4 growth stages, results were not consistently significant at any wavelengths, and the leaf area indices were significantly correlative to the spectra parameters before heading stage, so the spectra parameters before heading stage can be used to estimate the leaf area indices, and a regression model based on parameter D(lambda737)/D(lambda718) was recommended. Therefore the variation range of LAI for rice could response to the stress intensity directly, and the regression model LAI= 3. 138(D(lambda737)/D(lambda718))-0. 806 can precisely estimate the leaf area index under flooding and waterlogging stress. PMID:24611390

  6. [A Novel Method of Soil Moisture Content Monitoring by Land Surface Temperature and LAI].

    PubMed

    Gao, Zhong-ling; Zheng, Xiao-po; Sun, Yue-jun; Wang, Jian-hua

    2015-11-01

    Land surface temperature (Ts) is influenced by soil background and vegetation growing conditions, and the combination of Ts and vegetation indices (Vis) can indicate the status of surface soil moisture content (SMC). In this study, Advanced Temperature Vegetation Dryness Index (ATVDI) used for monitoring SMC was proposed on the basis of the simulation results with agricultural climate model CUPID. Previous studies have concluded that Normalized Difference Vegetation Index (NDVI) easily reaches the saturation point, andLeaf Area Index (LAI) was then used instead of NDVI to estimate soil moisture content in the paper. With LAI-Ts scatter diagram established by the simulation results of CUPID model; how Ts varied with LAI and SMC was found. In the case of the identical soil background, the logarithmic relations between Ts and LAI were more accurate than the linear relations included in Temperature Vegetation Dryness Index (TVDI), based on which ATVDI was then developed. LAI-Ts scatter diagram with satellite imagery were necessary for determining the expression of the upper and lower logarithmic curves while ATVDI was used for monitoring SMC. Ts derived from satellite imagery were then transformed to the Ts-value which has the same SMC and the minimum LAI in study area with look-up table. The measured SMC from the field sites in Weihe Plain, Shanxi Province, China, and the products of LAI and Ts (MOD15A2 and MOD11A2, respectively) produced by the image derived from Moderate Resolution Imaging Spectrometer (MODIS) were collected to validate the new method proposed in this study. The validation results shown that ATVDI (R² = 0.62) was accurate enough to monitor SMC, and it achieved better result than TVDI. Moreover, ATVDI-derived result were Ts values with some physical meanings, which made it comparative in different periods. Therefore, ATVDI is a promising method for monitoring SMC in different time-spatial scales in agricultural fields. PMID:26978922

  7. Molecular differentiation between Salmonella enterica subsp enterica serovar Pullorum and Salmonella enterica subsp enterica serovar Gallinarum

    PubMed Central

    Ribeiro, Simone Alves Mendes; de Paiva, Jaqueline Boldrin; Zotesso, Fábio; Lemos, Manoel Victor Franco; Berchieri Jánior, Ângelo

    2009-01-01

    S. Pullorum (SP) and S. Gallinarum (SG) are very similar. They are the agents of pullorum disease and fowl typhoid, respectively, and the two diseases are responsible for economic losses in poultry production. Although SP and SG are difficult to be differentiated in routine laboratory procedures, the ability to metabolize ornithine is a biochemical test that may be used to achieve this aim. While SP is able to decarboxylate this amino acid, SG is not. However, the isolation of strains showing atypical biochemical behavior has made this differentiation difficult. One of the genes associated with the metabolization of the amino acid ornithine is called speC, and is found in both serovars. The analysis of 21 SP and 15 SG strains by means of PCR did not enable the differentiation of the two serovars, because fragments produced were identical. However, after enzymatic treatment with restriction enzyme Eco RI, the band pattern of each serovar showed to be different, even in samples of atypical biochemical behavior. This fact enabled the standardization of the technique for a quick and safe differentiation of serovars Pullorum and Gallinarum. PMID:24031341

  8. Validation and Temporal Analysis of Lai and Fapar Products Derived from Medium Resolution Sensor

    NASA Astrophysics Data System (ADS)

    Claverie, M.; Vermote, E. F.; Baret, F.; Weiss, M.; Hagolle, O.; Demarez, V.

    2012-12-01

    Leaf Area Index (LAI) and Fraction of Absorbed Photosynthetically Active Radiation (FAPAR) have been defined as Essential Climate Variables. Many Earth surface monitoring applications are based on global estimation combined with a relatively high frequency. The medium spatial resolution sensors (MRS), such as SPOT-VGT, MODIS or MERIS, have been widely used to provide land surface products (mainly LAI and FAPAR) to the scientific community. These products require quality assessment and consistency. However, due to consistency of the ground measurements spatial sampling, the medium resolution is not appropriate for direct validation with in situ measurements sampling. It is thus more adequate to use high spatial resolution sensors which can integrate the spatial variability. The recent availability of combined high spatial (8 m) and temporal resolutions (daily) Formosat-2 data allows to evaluate the accuracy and the temporal consistency of medium resolution sensors products. In this study, we proposed to validate MRS products over a cropland area and to analyze their spatial and temporal consistency. As a matter of fact, this study belongs to the Stage 2 of the validation, as defined by the Land Product Validation sub-group of the Earth Observation Satellites. Reference maps, derived from the aggregation of Formosat-2 data (acquired during the 2006-2010 period over croplands in southwest of France), were compared with (i) two existing global biophysical variables products (GEOV1/VGT and MODIS-15 coll. 5), and (ii) a new product (MODdaily) derived from the inversion of PROSAIL radiative transfer model (EMMAH, INRA Avignon) applied on MODIS BRDF-corrected daily reflectance. Their uncertainty was calculated with 105 LAI and FAPAR reference maps, which uncertainties (22 % for LAI and 12% for FAPAR) were evaluated with in situ measurements performed over maize, sunflower and soybean. Inter-comparison of coarse resolution (0.05°) products showed that LAI and FAPAR have

  9. Estimation of vegetation LAI from hyperspectral reflectance data: Effects of soil type and plant architecture

    NASA Astrophysics Data System (ADS)

    Darvishzadeh, Roshanak; Skidmore, Andrew; Atzberger, Clement; van Wieren, Sip

    2008-09-01

    The retrieval of canopy biophysical variables is known to be affected by confounding factors such as plant type and background reflectance. The effects of soil type and plant architecture on the retrieval of vegetation leaf area index (LAI) from hyperspectral data were assessed in this study. In situ measurements of LAI were related to reflectances in the red and near-infrared and also to five widely used spectral vegetation indices (VIs). The study confirmed that the spectral contrast between leaves and soil background determines the strength of the LAI-reflectance relationship. It was shown that within a given vegetation species, the optimum spectral regions for LAI estimation were similar across the investigated VIs, indicating that the various VIs are basically summarizing the same spectral information for a given vegetation species. Cross-validated results revealed that, narrow-band PVI was less influenced by soil background effects (0.15 ≤ RMSE cv ≤ 0.56). The results suggest that, when using remote sensing VIs for LAI estimation, not only is the choice of VI of importance but also prior knowledge of plant architecture and soil background. Hence, some kind of landscape stratification is required before using hyperspectral imagery for large-scale mapping of vegetation biophysical variables.

  10. Retrieving Leaf Area Index (LAI) Using Remote Sensing: Theories, Methods and Sensors

    PubMed Central

    Zheng, Guang; Moskal, L. Monika

    2009-01-01

    The ability to accurately and rapidly acquire leaf area index (LAI) is an indispensable component of process-based ecological research facilitating the understanding of gas-vegetation exchange phenomenon at an array of spatial scales from the leaf to the landscape. However, LAI is difficult to directly acquire for large spatial extents due to its time consuming and work intensive nature. Such efforts have been significantly improved by the emergence of optical and active remote sensing techniques. This paper reviews the definitions and theories of LAI measurement with respect to direct and indirect methods. Then, the methodologies for LAI retrieval with regard to the characteristics of a range of remotely sensed datasets are discussed. Remote sensing indirect methods are subdivided into two categories of passive and active remote sensing, which are further categorized as terrestrial, aerial and satellite-born platforms. Due to a wide variety in spatial resolution of remotely sensed data and the requirements of ecological modeling, the scaling issue of LAI is discussed and special consideration is given to extrapolation of measurement to landscape and regional levels. PMID:22574042

  11. Molecular basis of the substrate specificity and the catalytic mechanism of citramalate synthase from Leptospira interrogans.

    PubMed

    Ma, Jun; Zhang, Peng; Zhang, Zilong; Zha, Manwu; Xu, Hai; Zhao, Guoping; Ding, Jianping

    2008-10-01

    Leptospira interrogans is the causative agent for leptospirosis, a zoonotic disease of global importance. In contrast with most other micro-organisms, L. interrogans employs a pyruvate pathway to synthesize isoleucine and LiCMS (L. interrogans citramalate synthase) catalyses the first reaction of the pathway which converts pyruvate and acetyl-CoA into citramalate, thus making it an attractive target for the development of antibacterial agents. We report here the crystal structures of the catalytic domain of LiCMS and its complexes with substrates, and kinetic and mutagenesis studies of LiCMS, which together reveal the molecular basis of the high substrate specificity and the catalytic mechanism of LiCMS. The catalytic domain consists of a TIM barrel flanked by an extended C-terminal region. It forms a homodimer in the crystal structure, and the active site is located at the centre of the TIM barrel near the C-terminal ends of the beta-strands and is composed of conserved residues of the beta-strands of one subunit and the C-terminal region of the other. The substrate specificity of LiCMS towards pyruvate against other alpha-oxo acids is dictated primarily by residues Leu(81), Leu(104) and Tyr(144), which form a hydrophobic pocket to accommodate the C(2)-methyl group of pyruvate. The catalysis follows the typical aldol condensation reaction, in which Glu(146) functions as a catalytic base to activate the methyl group of acetyl-CoA to form an enolated acetyl-CoA intermediate and Arg(16) as a general acid to stabilize the intermediate. PMID:18498255

  12. A landscape view of biomass, LAI, and photosynthetic capacity for FIFE

    NASA Technical Reports Server (NTRS)

    Kittel, T. G. F.; Knapp, A. K.; Seastedt, T.; Schimel, D. S.

    1990-01-01

    Canopy properties in the tallgrass prairie are examined in terms of spatial and temporal variability to determine how the variability constrains the ecosystem-atmosphere exchange of H2O, CO2, and momentum. Canopy structure and photosynthetic capacity are examined by measuring soil properties, canopy biomass, and canopy nitrogen along continuous strips. Special attention is given to sites of maximum and minimum biomass where parameters such as leaf-area index (LAI), photosynthetic rate, chemistry, and structures for both burned and unburned areas. The LAI/biomass data and the canopy attributes show that soil properties are shaped by soil-forming and geomorphic processes. The variables that cause the greatest variation in LAI, canopy stratification, and photosynthetic capacity are found to be management (burning and/or grazing) and landscape position.

  13. Analyzing C-band SAR polarimetric information for LAI and crop yield estimations

    NASA Astrophysics Data System (ADS)

    Molijn, Ramses A.; Iannini, Lorenzo; Mousivand, Ali; Hanssen, Ramon F.

    2014-10-01

    In this study, space remote sensing data and crop specific information from the ESA-led AgriSAR 2009 campaign are used for studying the profiles of C-band SAR backscatter signals and multispectral-based leaf area index (LAI) over the growth period of canola, pea and wheat. In addition, the correlations between radar backscatter parameters and the crop yields were analyzed, based on extracted statistics of temporal profiles. The results show that the HV backscatter and LAI are correlated differently before and after LAI peak. In addition, the coefficient of determination between peakrelated statistics from polarimetric indicator profiles and yield for pea fields can reach up to 0.68, and for canola and wheat up to 0.47 and 0.5, respectively. HV backscatter and coherence between HH and VV are most.

  14. Molecular characterization of virulent Leptospira interrogans serogroup icterohaemorrhagiae isolated from Cavia aperea.

    PubMed

    Monte, Leonardo G; Jorge, Sérgio; Xavier, Marina A; Leal, Fernanda M A; Amaral, Marta G; Seixas, Fabiana K; Dellagostin, Odir A; Hartleben, Cláudia P

    2013-05-01

    Leptospirosis is a worldwide zoonotic infection caused by pathogenic Leptospira. Synanthropic rodents are recognized carriers of leptospires; however, the role of wild rodents in the epidemiology of the disease is still incipient. In this work, we describe Leptospira strain isolated from Cavia aperea (Brazilian guinea pig). The isolated strain was characterized by partial rpoB gene sequencing, variable-number tandem-repeats and histopathological analysis. The strain was identified as Leptospira interrogans, serogroup Icterohaemorrhagiae and caused clinical signs of leptospirosis in the hamster model, attesting to its virulence. In conclusion, these findings could be useful for elucidating the epidemiological role of C. aperea in leptospirosis. PMID:23435256

  15. Purification and characterization of a Na+, K+ ATPase inhibitor found in an endotoxin of Leptospira interrogans.

    PubMed Central

    Burth, P; Younes-Ibrahim, M; Gonçalez, F H; Costa, E R; Faria, M V

    1997-01-01

    We showed previously that the glycolipoprotein fraction prepared from Leptospira interrogans inhibited the Na+,K+ ATPase enzyme purified from brain or kidney and in isolated nephron segments (M. Younes-Ibrahim, P. Burth, M. V. Castro Faria, B. Buffin-Meyer, S. Marsy, C. Barlet-Bas, L. Cheval, and A. Doucet, C. R. Acad. Sci. Paris Ser. III 318:619-625, 1995). In the present communication, we have demonstrated that unsaturated fatty acids such as oleic and palmitoleic acids, which are adsorbed to this fraction, are effective inhibitors of the enzyme. PMID:9119504

  16. [Inversion of LAI by considering the hotspot effect for different geometrical wheat].

    PubMed

    Zhao, Juan; Zhang, Yao-Hong; Huang, Wen-Jiang; Jing, Yuan-Shu; Peng, Dai-Liang; Wang, Li; Song, Xiao-Yu

    2014-01-01

    Aimed to deal with the limitation of canopy geometry to crop LAI inversion accuracy a new LAI inversion method for different geometrical winter wheat was proposed based on hotspot indices with field-measured experimental data. The present paper analyzed bidirectional reflectance characteristics of erective and loose varieties at red (680 nm) and NIR wavelengths (800 nm and 860 nm) and developed modified normalized difference between hotspot and dark-spot (MNDHD) and hotspot and dark-spot ratio index (HDRI) using hotspot and dark-spot index (HDS) and normalized difference between hotspot and dark-spot (NDHD) for reference. Combined indices were proposed in the form of the product between HDS, NDHD, MNDHD, HDRI and three ordinary vegetation indices NDVI, SR and EVI to inverse LAI for erective and loose wheat. The analysis results showed that LAI inversion accuracy of erective wheat Jing411 were 0.9431 and 0.9092 retrieved from the combined indices between NDVI and MNDHD and HDRI at 860 nm which were better than that of HDS and NDHD, the LAI inversion accuracy of loose wheat Zhongyou9507 were 0.9648 and 0.8956 retrieved from the combined indices between SR and HDRI and MNDHD at 800 nm which were also higher than that of HDS and NDHD. It was finally concluded that the combined indices between hotspot-signature indices and ordinary vegetation indices were feasible enough to inverse LAI for different crop geometrical wheat and multiangle remote sensing data was much more advantageous than perpendicular observation data to extract crop structural parameters. PMID:24783562

  17. Estimation of grassland use intensities based on high spatial resolution LAI time series

    NASA Astrophysics Data System (ADS)

    Asam, S.; Klein, D.; Dech, S.

    2015-04-01

    The identification and surveillance of agricultural management and the measurement of biophysical canopy parameters in grasslands is relevant for environmental protection as well as for political and economic reasons, as proper grassland management is partly subsidized. An ideal monitoring tool is remote sensing due to its area wide continuous observations. However, due to small-scaled land use patterns in many parts of central Europe, a high spatial resolution is needed. In this study, the feasibility of RapidEye data to derive leaf area index (LAI) time series and to relate them to grassland management practices is assessed. The study area is the catchment of river Ammer in southern Bavaria, where agricultural areas are mainly grasslands. While extensively managed grasslands are maintained with one to two harvests per year and no or little fertilization, intensive cultivation practices compass three to five harvests per year and turnover pasturing. Based on a RapidEye time series from 2011 with spatial resolution of 6.5 meters, LAI is derived using the inverted radiation transfer model PROSAIL. The LAI in this area ranges from 1.5 to 7.5 over the vegetation period and is estimated with an RMSE between 0.7 and 1.1. The derived LAI maps cover 85 % of the study area's grasslands at least seven times. Using statistical metrics of the LAI time series, different grassland management types can be identified: very intensively managed meadows, intensively managed meadows, intensively managed pastures, and extensively managed meadows and moor. However, a precise identification of the mowing dates highly depends on the coincidence with satellite data acquisitions. Further analysis should focus therefor on the selection of the temporal resolution of the time series as well as on the performance of further vegetation parameters and indices compared to LAI.

  18. Improving Satellite-Based LAI and FPAR Predictions With Simple Site-Specific Parameterizations

    NASA Astrophysics Data System (ADS)

    Gibbs, H. K.; Washington-Allen, R. A.; King, A. W.; Pan, F.; Sale, M. J.

    2002-12-01

    Leaf area index (leaf area per ground surface area; LAI) and the fraction of photosynthetically active radiation absorbed by vegetation (fPAR) are fundamental elements of hydrologic modeling. Maps of LAI and fPAR are thus critical inputs for spatially extensive hydrology models. These maps can be derived from satellite data using relationships between LAI, fPAR, and spectral vegetation indices (SVI), but establishing these relationships and associated parameters requires time consuming and expensive ground-based measurements. Consequently, calibrations established for one site are frequently transferred to another site without considering site-specific elements of the parameterization or potential error introduced by the geographic transfer. We are evaluating this error and developing simple and effective corrections as part of a multi-laboratory Department of Energy (DOE) project investigating hydrometeorological processes in the Walnut River Watershed (WRW) in southeast Kansas. We applied relationships established for the North American Great Plains and Konza Prairie Long Term Ecological Research sites to the WRW and developed parameterizations using Normalized Difference Vegetation Index (NDVI) derived from 1km Advanced Very High Resolution Radiometer (AVHRR) and 30m Landsat Thematic Mapper. Ground-based reflectance, LAI, and fPAR were collected for 100+ sites on the WRW. Initial evaluation indicates that simple calibrations using site-specific satellite data to adjust parameters substantially improve predictions of the ported LAI/fPAR-SVI relationships. For example, estimating NDVI of bare ground from AVHRR data for the WRW and substituting that value into the Konza Prairie relationship greatly improved predictions of LAI for WRW grasslands. Our methods of site-specific parameterization may allow accurate use of geographically ported relationships in many different locations. This research was sponsored by the DOE Office of Science, Environmental Sciences

  19. Characterizing leaf area index (LAI) and vertical foliage profile (VFP) over the United States

    NASA Astrophysics Data System (ADS)

    Tang, H.; Ganguly, S.; Zhang, G.; Hofton, M. A.; Nelson, R. F.; Dubayah, R.

    2016-01-01

    Leaf area index (LAI) and vertical foliage profile (VFP) are among the important canopy structural variables. Recent advances in lidar remote sensing technology have demonstrated the capability of accurately mapping LAI and VFP over large areas. The primary objective of this study was to derive and validate a LAI and VFP product over the contiguous United States (CONUS) using spaceborne waveform lidar data. This product was derived at the footprint level from the Geoscience Laser Altimeter System (GLAS) using a biophysical model. We validated GLAS-derived LAI and VFP across major forest biomes using airborne waveform lidar. The comparison results showed that GLAS retrievals of total LAI were generally accurate with little bias (r2 = 0.67, bias = -0.13, RMSE = 0.75). The derivations of GLAS retrievals of VFP within layers were not as accurate overall (r2 = 0.36, bias = -0.04, RMSE = 0.26), and these varied as a function of height, increasing from understory to overstory - 0 to 5 m layer: r2 = 0.04, bias = 0.09, RMSE = 0.31; 10 to 15 m layer: r2 = 0.53, bias = -0.08, RMSE = 0.22; and 15 to 20 m layer: r2 = 0.66, bias = -0.05, RMSE = 0.20. Significant relationships were also found between GLAS LAI products and different environmental factors, in particular elevation and annual precipitation. In summary, our results provide a unique insight into vertical canopy structure distribution across North American ecosystems. This data set is a first step towards a baseline of canopy structure needed for evaluating climate and land use induced forest changes at the continental scale in the future, and should help deepen our understanding of the role of vertical canopy structure in terrestrial ecosystem processes across varying scales.

  20. Characterizing Leaf Area Index (LAI) and Vertical Foliage Profile (VFP) over the United States

    NASA Astrophysics Data System (ADS)

    Tang, H.; Ganguly, S.; Zhang, G.; Hofton, M. A.; Nelson, R. F.; Dubayah, R.

    2015-08-01

    Leaf area index (LAI) and vertical foliage profile (VFP) are among the important canopy structural variables. Recent advances in lidar remote sensing technology have demonstrated the capability of accurately mapping LAI and VFP over large areas. The primary objective of this study was to derive and validate a LAI and VFP product over the contiguous United States using spaceborne waveform lidar data. This product was derived at the footprint level from the Geoscience Laser Altimeter System (GLAS) using a biophysical model. We validated GLAS derived LAI and VFP across major forest biomes using airborne waveform lidar. The comparison results showed that GLAS retrievals of total LAI were generally accurate with little bias (r2 = 0.67, bias = -0.13, RMSE = 0.75). The derivations of GLAS retrievals of VFP within layers was not as accurate overall (r2 = 0.36, bias = -0.04, RMSE = 0.26), and these varied as a function of height, increasing from understory to overstory -0 to 5 m layer: r2 = 0.04, bias = 0.09, RMSE = 0.31; 10 to 15 m layer: r2 = 0.53, bias = -0.08, RMSE = 0.22; and 15 to 20 m layer: r2 = 0.66, bias =-0.05, RMSE = 0.20. Significant relationships were also found between GLAS LAI products and different environmental factors, in particular elevation and annual precipitation. In summary, our results provide a unique insight into vertical canopy structure distribution across North American ecosystems. This data set is a first step towards a baseline of canopy structure needed for evaluating climate and land use induced forest changes at continental scale in the future and should help deepen our understanding of the role of vertical canopy structure on terrestrial ecosystem processes across varying scales.

  1. BOREAS RSS-7 Landsat TM LAI IMages of the SSA and NSA

    NASA Technical Reports Server (NTRS)

    Hall, Forrest G. (Editor); Nickeson, Jaime (Editor); Chen, Jing; Cihlar, Josef

    2000-01-01

    The BOReal Ecosystem-Atmosphere Study Remote Sensing Science (BOREAS RSS-7) team used Landsat Thematic Mapper (TM) images processed at CCRS to produce images of Leaf Area Index (LAI) for the BOREAS study areas. Two images acquired on 06-Jun and 09-Aug-1991 were used for the SSA, and one image acquired on 09-Jun-1994 was used for the NSA. The LAI images are based on ground measurements and Landsat TM Reduced Simple Ratio (RSR) images. The data are stored in binary image-format files.

  2. Spatial and seasonal variations of leaf area index (LAI) in subtropical secondary forests related to floristic composition and stand characters

    NASA Astrophysics Data System (ADS)

    Zhu, Wenjuan; Xiang, Wenhua; Pan, Qiong; Zeng, Yelin; Ouyang, Shuai; Lei, Pifeng; Deng, Xiangwen; Fang, Xi; Peng, Changhui

    2016-07-01

    Leaf area index (LAI) is an important parameter related to carbon, water, and energy exchange between canopy and atmosphere and is widely applied in process models that simulate production and hydrological cycles in forest ecosystems. However, fine-scale spatial heterogeneity of LAI and its controlling factors have yet to be fully understood in Chinese subtropical forests. We used hemispherical photography to measure LAI values in three subtropical forests (Pinus massoniana-Lithocarpus glaber coniferous and evergreen broadleaved mixed forests, Choerospondias axillaris deciduous broadleaved forests, and L. glaber-Cyclobalanopsis glauca evergreen broadleaved forests) from April 2014 to January 2015. Spatial heterogeneity of LAI and its controlling factors were analysed using geostatistical methods and the generalised additive models (GAMs) respectively. Our results showed that LAI values differed greatly in the three forests and their seasonal variations were consistent with plant phenology. LAI values exhibited strong spatial autocorrelation for the three forests measured in January and for the L. glaber-C. glauca forest in April, July, and October. Obvious patch distribution pattern of LAI values occurred in three forests during the non-growing period and this pattern gradually dwindled in the growing season. Stem number, crown coverage, proportion of evergreen conifer species on basal area basis, proportion of deciduous species on basal area basis, and forest types affected the spatial variations in LAI values in January, while stem number and proportion of deciduous species on basal area basis affected the spatial variations in LAI values in July. Floristic composition, spatial heterogeneity, and seasonal variations should be considered for sampling strategy in indirect LAI measurement and application of LAI to simulate functional processes in subtropical forests.

  3. Salmonella Serovars from Foodborne and Waterborne Diseases in Korea, 1998-2007: Total Isolates Decreasing Versus Rare Serovars Emerging

    PubMed Central

    2010-01-01

    Salmonella enterica has been one of the most widespread foodborne pathogens in Korea. Between 1998 and 2007, a total of 9,472 Salmonella isolates were identified from foodborne and waterborne illness patients. During that time, Korea was transitioning into a developed country in industry as well as in its hygiene system. Although the isolation number of total Salmonella including serovar Typhi has decreased since 1999, the isolation of rare Salmonella serovars has emerged. Three most prevalent serovars during 1998-2007 were S. enterica Typhi, S. enterica Enteritidis, and S. enterica Typhimurium. There were remarkable outbreaks caused by rare serovars such as S. enterica Othmarschen, S. enterica London and S. enterica Paratyphi A, and overseas traveler-associated infections caused by S. enterica Weltevreden and S. enterica Anatum. Salmonella serovars from overseas travelers made a diverse Salmonella serovar pool in Korea. This study is the first review of the status of the human Salmonella infection trend in a developing country during 1998-2007. Newly emerging rare Salmonella serovars should be traced and investigated to control new type pathogens in the developed world. PMID:21165281

  4. Generation of mammalian host-adapted Leptospira interrogans by cultivation in peritoneal dialysis membrane chamber implantation in rats

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Leptospira interrogans can infect a myriad of mammalian hosts, including humans (Bharti, Nally et al. 2003, Ko, Goarant et al. 2009). Following acquisition by a suitable host, leptospires disseminate via the bloodstream to multiple tissues, including the kidneys, where they adhere to and colonize th...

  5. Proteome-wide cellular protein concentrations of the human pathogen Leptospira interrogans

    PubMed Central

    Malmström, Johan; Beck, Martin; Schmidt, Alexander; Lange, Vinzenz; Deutsch, Eric W.; Aebersold, Ruedi

    2009-01-01

    Mass spectrometry based methods for relative proteome quantification have broadly impacted life science research. However, important research directions, particularly those involving mathematical modeling and simulation of biological processes, also critically depend on absolutely quantitative data, i.e. knowledge of the concentration of the expressed proteins as a function of cellular state. Until now, absolute protein concentration measurements of a significant fraction of the proteome (73%) have only been derived from genetically altered S. cerevisiae cells 1, a technique that is not directly portable from yeast to other species. In this study we developed and applied a mass spectrometry based strategy to determine the absolute quantity i.e. the average number of protein copies per cell in a cell population, for a significant fraction of the proteome in genetically unperturbed cells. Applying the technology to the human pathogen Leptospira interrogans, a spirochete responsible for Leptospirosis 4, we generated an absolute protein abundance scale for 83% of the mass spectrometry detectable proteome, from cells at different states. Taking advantage of the unique cellular dimensions of L. interrogans, we used cryo electron tomography (cryoET) morphological measurements to verify at the single cell level the average absolute abundance values of selected proteins determined by mass spectrometry on a population of cells. As the strategy is relatively fast and applicable to any cell type we expect that it will become a cornerstone of quantitative biology and systems biology. PMID:19606093

  6. Leptospira interrogans reduces fibrin clot formation by modulating human thrombin activity via exosite I.

    PubMed

    Fernandes, Luis G; de Morais, Zenaide M; Vasconcellos, Silvio A; Nascimento, Ana L T O

    2015-06-01

    Pathogenic bacteria of the genus Leptospira are the etiological agents of leptospirosis, a disease that affects humans and animals worldwide. Although there are an increasing number of studies on the biology of Leptospira, the mechanisms of pathogenesis are not yet understood. We report in this work that Leptospira interrogans FIOCRUZ L1-130 virulent, M20 culture attenuated and the saprophyte L. biflexa Patoc 1 strains do not bind prothrombin. Leptospiral binding to thrombin was detected with the virulent, followed by culture-attenuated M20, and practically none was observed with the saprophyte strain. The interaction of Leptospira with thrombin mostly occurs via exosite I, with a minor participation of catalytic site, as determined by employing the thrombin inhibitors hirugen, hirudin and argatroban. Leptospira interrogans binding to thrombin inhibits its catalytic activity reducing fibrin clot formation in thrombin-catalyzed reaction of fibrinogen. This inhibition was more efficient with the virulent FIOCRUZ L1-130 than with the M20 culture attenuated, while none was seen with the saprophyte strain, suggesting that this binding might be important for bacterial virulence. This is the first study reporting the binding of pathogenic Leptospira to thrombin promoting a decrease in fibrin clotting that could lead to hemorrhage, helping bacteria dissemination. PMID:25834144

  7. Purification, crystallization and preliminary crystallographic studies on 2-dehydro-3-deoxygalactarate aldolase from Leptospira interrogans

    SciTech Connect

    Li, Xu; Huang, Hua; Song, Xiaomin; Wang, Yanli; Xu, Hang; Teng, Maikun; Gong, Weimin

    2006-12-01

    Preliminary crystallographic studies on 2-dehydro-3-deoxygalactarate aldolase from L. interrogans. 2-Dehydro-3-deoxygalactarate (DDG) aldolase is a member of the class II aldolase family and plays an important role in the pyruvate-metabolism pathway, catalyzing the reversible aldol cleavage of DDG to pyruvate and tartronic semialdehyde. As it is a potential novel antibiotic target, it is necessary to elucidate the catalytic mechanism of DDG aldolase. To determine the crystal structure, crystals of DDG aldolase from Leptospira interrogans were obtained by the hanging-drop vapour-diffusion method. The crystals diffracted to 2.2 Å resolution using a Cu Kα rotating-anode X-ray source. The crystal belonged to space group C2, with unit-cell parameters a = 293.5, b = 125.6, c = 87.6 Å, β = 100.9°. The V{sub M} is calculated to be 2.4 Å{sup 3} Da{sup −1}, assuming there to be 12 protein molecules in the asymmetric unit.

  8. A Novel Moisture Adjusted Vegetation Index (MAVI) to Reduce Background Reflectance and Topographical Effects on LAI Retrieval

    PubMed Central

    Zhu, Gaolong; Ju, Weimin; Chen, J. M.; Liu, Yibo

    2014-01-01

    A new moisture adjusted vegetation index (MAVI) is proposed using the red, near infrared, and shortwave infrared (SWIR) reflectance in band-ratio form in this paper. The effectiveness of MAVI in retrieving leaf area index (LAI) is investigated using Landsat-5 data and field LAI measurements in two forest and two grassland areas. The ability of MAVI to retrieve forest LAI under different background conditions is further evaluated using canopy reflectance of Jack Pine and Black Spruce forests simulated by the 4-Scale model. Compared with several commonly used two-band vegetation index, such as normalized difference vegetation index, soil adjusted vegetation index, modified soil adjusted vegetation index, optimized soil adjusted vegetation index, MAVI is a better predictor of LAI, on average, which can explain 70% of variations of LAI in the four study areas. Similar to other SWIR-related three-band vegetation index, such as modified normalized difference vegetation index (MNDVI) and reduced simple ratio (RSR), MAVI is able to reduce the background reflectance effects on forest canopy LAI retrieval. MAVI is more suitable for retrieving LAI than RSR and MNDVI, because it avoids the difficulty in properly determining the maximum and minimum SWIR values required in RSR and MNDVI, which improves the robustness of MAVI in retrieving LAI of different land cover types. Moreover, MAVI is expressed as ratios between different spectral bands, greatly reducing the noise caused by topographical variations, which makes it more suitable for applications in mountainous area. PMID:25025128

  9. A novel moisture adjusted vegetation index (MAVI) to reduce background reflectance and topographical effects on LAI retrieval.

    PubMed

    Zhu, Gaolong; Ju, Weimin; Chen, J M; Liu, Yibo

    2014-01-01

    A new moisture adjusted vegetation index (MAVI) is proposed using the red, near infrared, and shortwave infrared (SWIR) reflectance in band-ratio form in this paper. The effectiveness of MAVI in retrieving leaf area index (LAI) is investigated using Landsat-5 data and field LAI measurements in two forest and two grassland areas. The ability of MAVI to retrieve forest LAI under different background conditions is further evaluated using canopy reflectance of Jack Pine and Black Spruce forests simulated by the 4-Scale model. Compared with several commonly used two-band vegetation index, such as normalized difference vegetation index, soil adjusted vegetation index, modified soil adjusted vegetation index, optimized soil adjusted vegetation index, MAVI is a better predictor of LAI, on average, which can explain 70% of variations of LAI in the four study areas. Similar to other SWIR-related three-band vegetation index, such as modified normalized difference vegetation index (MNDVI) and reduced simple ratio (RSR), MAVI is able to reduce the background reflectance effects on forest canopy LAI retrieval. MAVI is more suitable for retrieving LAI than RSR and MNDVI, because it avoids the difficulty in properly determining the maximum and minimum SWIR values required in RSR and MNDVI, which improves the robustness of MAVI in retrieving LAI of different land cover types. Moreover, MAVI is expressed as ratios between different spectral bands, greatly reducing the noise caused by topographical variations, which makes it more suitable for applications in mountainous area. PMID:25025128

  10. A Study toward the Evaluation of ALOS Images for LAI Estimation in Rice Fields

    NASA Astrophysics Data System (ADS)

    Sharifi Hashjin, Sh.; Darvishzadeh, R.; Khandan, R.

    2013-10-01

    For expanding and managing agricultural sources, satellite data have a key role in determining required information about different factors in plants Including Leaf Area Index (LAI).This paper has studied the potential of spectral indices in estimating rice canopy LAI in Amol city as one of the main sources of rice production in Iran. Due to its importance in provision of food and calorie of a major portion of population, rice product was chosen for study. A field campaign was conducted when rice was in the max growth stage (late of June). Also, two satellite images from ALOS-AVNIR-2 were used (simultaneous with conducted field works) to extract and determine vegetation indices. Then the Regression between measured data and vegetation indices, derived from combination of different bands, was evaluated and after that suitable vegetation indices were realized. Finally, statistics and calculations for introduction of a suitable model were presented. After examination of models, the results showed that RDVI and SAVI2, by determination coefficient and RMSE of 0.12-0.59 and 0.24-0.62, have more accuracy in LAI estimation. Results of present study demonstrated the potential of ALOS images, for LAI estimation and their significant role in monitoring and managing the rice plant.

  11. LEAF AREA INDEX (LAI) CHANGE DETECTION ON LOBLOLLY PINE FOREST STANDS WITH COMPLETE UNDERSTORY REMOVAL

    EPA Science Inventory

    The confounding effect of understory vegetation contributions to satellite derived
    estimates of leaf area index (LAI) was investigated on two loblolly pine (Pinus taeda) forest stands located in the southeastern United States. Previous studies have shown that understory can a...

  12. Daily mapping of Landsat-like LAI and correlation to grape yield

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Wine grape quality and quantity are affected by vine growing condition during some critical growing stages. In this paper, MODIS and Landsat were used to map daily LAI in the two Grape Remote sensing Atmospheric Profiling and Evapotranspiration eXperiment (GRAPEX) experiment fields near Lodi, Califo...

  13. Impact of Spatial LAI Heterogeneity on Estimate of Directional Gap Fraction from SPOT-Satellite Data

    PubMed Central

    Ma, Lingling; Li, Chuanrong; Tang, Bohui; Tang, Lingli; Bi, Yuyin; Zhou, Beiyan; Li, Zhao-Liang

    2008-01-01

    Directional gap probability or gap fraction is a basic parameter in the optical remote sensing modeling. Although some approaches have been proposed to estimate this gap probability from remotely sensed measurements, few efforts have been made to investigate the scaling effects of this parameter. This paper analyzes the scaling effect through aggregating the high-resolution directional gap probability (pixel size of 20 meters) estimated from leaf area index (LAI) images of VALERI database by means of Beer's law and introduces an extension of clumping index, Ĉ, to compensate the scaling bias. The results show that the scaling effect depends on both the surface heterogeneity and the nonlinearity degree of the retrieved function. Analytical expressions for the scaling bias of gap probability and Ĉ are established in function of the variance of LAI and the mean value of LAI in a coarse pixel. With the VALERI dataset, the study in this paper shows that relative scaling bias of gap probability increases with decreasing spatial resolution for most of land cover types. Large relative biases are found for most of crops sites and a mixed forest site due to their relative large variance of LAI, while very small biases occur over grassland and shrubs sites. As for Ĉ, it varies slowly in the pure forest, grassland and shrubs sites, while more significantly in crops and mixed forest.

  14. LEAF AREA INDEX (LAI) CHANGE DETECTION ANALYSIS ON LOBLOLLY PINE (PINUS TAEDA) FOLLOWING COMPLETE UNDERSTORY REMOVAL

    EPA Science Inventory

    The confounding effect of understory vegetation contributions to satellite-derived estimates of leaf area index (LAI) was investigated on two loblolly pine (Pinus taeda) forest stands located in Virginia and North Carolina. In order to separate NDVI contributions of the dominantc...

  15. LEAF AREA INDEX (LAI) CHANGE DETECTION ON LOBLOLLY PINE FOREST STANDS WITH COMPLETE UNDERSTORY REMOVAL

    EPA Science Inventory

    The confounding effect of understory vegetation contributions to satellite derived estimates of leaf area index (LAI) was investigated on two loblolly pine forest stands located in the southeastern United States. Previous studies have shown that understory can account from 0-40%...

  16. [Hyperspectral Estimation of Apple Tree Canopy LAI Based on SVM and RF Regression].

    PubMed

    Han, Zhao-ying; Zhu, Xi-cun; Fang, Xian-yi; Wang, Zhuo-yuan; Wang, Ling; Zhao, Geng-Xing; Jiang, Yuan-mao

    2016-03-01

    Leaf area index (LAI) is the dynamic index of crop population size. Hyperspectral technology can be used to estimate apple canopy LAI rapidly and nondestructively. It can be provide a reference for monitoring the tree growing and yield estimation. The Red Fuji apple trees of full bearing fruit are the researching objects. Ninety apple trees canopies spectral reflectance and LAI values were measured by the ASD Fieldspec3 spectrometer and LAI-2200 in thirty orchards in constant two years in Qixia research area of Shandong Province. The optimal vegetation indices were selected by the method of correlation analysis of the original spectral reflectance and vegetation indices. The models of predicting the LAI were built with the multivariate regression analysis method of support vector machine (SVM) and random forest (RF). The new vegetation indices, GNDVI527, ND-VI676, RVI682, FD-NVI656 and GRVI517 and the previous two main vegetation indices, NDVI670 and NDVI705, are in accordance with LAI. In the RF regression model, the calibration set decision coefficient C-R2 of 0.920 and validation set decision coefficient V-R2 of 0.889 are higher than the SVM regression model by 0.045 and 0.033 respectively. The root mean square error of calibration set C-RMSE of 0.249, the root mean square error validation set V-RMSE of 0.236 are lower than that of the SVM regression model by 0.054 and 0.058 respectively. Relative analysis of calibrating error C-RPD and relative analysis of validation set V-RPD reached 3.363 and 2.520, 0.598 and 0.262, respectively, which were higher than the SVM regression model. The measured and predicted the scatterplot trend line slope of the calibration set and validation set C-S and V-S are close to 1. The estimation result of RF regression model is better than that of the SVM. RF regression model can be used to estimate the LAI of red Fuji apple trees in full fruit period. PMID:27400527

  17. Relation of MODIS EVI and LAI across time, vegetation types and hydrological regimes

    NASA Astrophysics Data System (ADS)

    Alexandridis, Thomas; Ovakoglou, George

    2015-04-01

    Estimation of the Leaf Area Index (LAI) of a landscape is considered important to describe the ecosystems activity and is used as an important input parameter in hydrological and biogeochemical models related to water and carbon cycle, desertification risk, etc. The measurement of LAI in the field is a laborious and costly process and is mainly done by indirect methods, such as hemispherical photographs that are processed by specialized software. For this reason there have been several attempts to estimate LAI with multispectral satellite images, using theoretical biomass development models, or empirical equations using vegetation indices and land cover maps. The aim of this work is to study the relation of MODIS EVI and LAI across time, vegetation type, and hydrological regime. This was achieved by studying 120 maps of EVI and LAI which cover a hydrological year and five hydrologically diverse areas: river Nestos in Greece, Queimados catchment in Brazil, Rijnland catchment in The Netherlands, river Tamega in Portugal, and river Umbeluzi in Mozambique. The following Terra MODIS composite datasets were downloaded for the hydrological year 2012-2013: MOD13A2 "Vegetation Indices" and MCD15A2 "LAI and FPAR", as well as the equivalent quality information layers (QA). All the pixels that fall in a vegetation land cover (according to the MERIS GLOBCOVER map) were sampled for the analysis, with the exception of those that fell at the border between two vegetation or other land cover categories, to avoid the influence of mixed pixels. Using linear regression analysis, the relationship between EVI and LAI was identified per date, vegetation type and study area. Results show that vegetation type has the highest influence in the variation of the relationship between EVI and LAI in each study area. The coefficient of determination (R2) is high and statistically significant (ranging from 0.41 to 0.83 in 90% of the cases). When plotting the EVI factor from the regression equation

  18. Using MODIS LAI to Identify Vegetation Anomalies in Yosemite National Park

    NASA Astrophysics Data System (ADS)

    Voss, M.; Husby, A.; Lake, S.; Lavelle, K.; Oza, S.; Suarez, A.; Schmidt, C. L.; Skiles, J. W.

    2006-12-01

    Vegetation anomalies in Yosemite National Park were examined using remotely sensed data by students from NASA Ames Research Center's DEVELOP Internship Program. These anomalies result primarily from beetle infestation, fires and long periods of snow cover, but the causes of many anomalies have not been clearly explained by park personnel. Such vegetation disturbances can result in forest fragmentation and subsequent loss of wildlife habitat and increased fire hazard. This project utilized the MODIS Leaf Area Index (LAI) product in the analysis of vegetation in Yosemite. LAI provides a ratio of total leaf area to ground area. The LAI data for each month were averaged from 2001 to 2005. Data for the summer months of 2005 were compared with the monthly averages to produce a map of LAI values that were less than the five-year average; we termed these lower than average values "anomalies". These maps were overlaid with known areas of insect infestation, snow cover or recent wild fire. Field work was conducted to verify the known causes of disturbance and ascertain the causes of unexplained anomalies. Using MODIS LAI and ancillary data, locations of unknown anomalies that need further investigation were developed for use by research partners. Continuation of the project will result in the creation of an automated site selection and anomaly detecting utility which will allow park managers to quickly locate vegetation anomalies which subsequently should be examined on site. This methodology is of interest to managers of national parks and forests because of the accessibility of MODIS data, its high temporal resolution and the speed with which large areas of land can be analyzed.

  19. High Resolution Simulation of LAI, Carbon and Water Fluxes over France

    NASA Astrophysics Data System (ADS)

    Lafont, Sebastien; Zhao, Yang; Barbu, Alina; Dominique, Carrer; Calvet, Jean Christophe; Peylin, Philippe; Weiss, Marie

    2011-01-01

    The vegetation/land component of GMES is called “Land Monitoring Core service” (LMCS). The geoland2 European project (FP7, 2008-2012) is a demonstrator of the evolution of the LMCS, including the consolidation of prototype services and the test of their operational capacity. The main mission of the land carbon core information service (LC-CIS) of geoland2 is to assess the impact of weather and climate variability on terrestrial biospheric carbon fluxes, in the context of international conventions. The LC-CIS aims at monitoring the global terrestrial carbon fluxes (e.g. to support reporting obligations in the course of the Kyoto Protocol) and setting-up pre-operational infrastructures for providing global products, both in near real time and off-line mode. A multi-model carbon accounting system is developed, coupled with EO data assimilation schemes. Emphasis is put on validation (in-situ data), with downscaling on reference European countries (F, NL, HU). The C-TESSEL and SURFEX modelling platforms (of ECMWF and Météo-France, respectively) are used for production. The ORCHIDEE modelling platform (LSCE) is used for benchmarking and validation purposes. We will present first test of the Geoland2 SURFEX model without data assimilation (Open-loop) over the French domain. We will focus on the simulation of the Leaf Area Index (LAI) and of carbon and water fluxes. The LAI is an important characteristics of the vegetation. It is a good measure of the amount of active vegetation and is linked to the canopy resistance, the water and carbon fluxes between the atmosphere and the vegetation. In this study, we compare 4 different estimations of LAI over France area : two LAI products derived from visible remote sensing and simulated LAI from 2 land surface models. The simulated LAI originates from two land surface models, The ISBA-A-gs model (developed by CNRM) and the ORCHIDEE model (developed by IPSL). The atmospheric forcing for the models is the SAFRAN dataset, a high

  20. Development of a global LAI estimation algorithm for JAXA's new earth observation satellite sensor, GCOM-C/SGLI

    NASA Astrophysics Data System (ADS)

    Ono, Y.; Murakami, H.; Kobayashi, H.; Nasahara, K. N.; Kajiwara, K.; Honda, Y.

    2014-12-01

    Leaf Area Index (LAI) is defined as the one-side green leaf area per unit ground surface area. Global LAI products, such as MOD15 (Terra&Aqua/MODIS) and CYCLOPES (SPOT/VEGETATION) are used for many global terrestrial carbon models. Japan Aerospace eXploration Agency (JAXA) is planning to launch GCOM-C (Global Change Observation Mission-Climate) which carries SGLI (Second-generation GLobal Imager) in the Japanese Fiscal Year 2017. SGLI has the features, such as 17-channel from near ultraviolet to thermal infrared, 250-m spatial resolution, polarization, and multi-angle (nadir and ±45-deg. along-track slant) observation. In the GCOM-C/SGLI land science team, LAI is scheduled to be generated from GCOM-C/SGLI observation data as a standard product (daily 250-m). In extisting algorithms, LAI is estimated by the reverse analysis of vegetation radiative transfer models (RTMs) using multi-spectral and mono-angle observation data. Here, understory layer in vegetation RTMs is assumed by plane parallel (green leaves + soil) which set up arbitrary understroy LAI. However, actual understory consists of various elements, such as green leaves, dead leaves, branches, soil, and snow. Therefore, if understory in vegetation RTMs differs from reality, it will cause an error of LAI to estimate. This report describes an algorithm which estimates LAI in consideration of the influence of understory using GCOM-C/SGLI multi-spectral and multi-angle observation data.

  1. Evaluating the potential of vegetation indices for winter wheat LAI estimation under different fertilization and water conditions

    NASA Astrophysics Data System (ADS)

    Xie, Qiaoyun; Huang, Wenjiang; Dash, Jadunandan; Song, Xiaoyu; Huang, Linsheng; Zhao, Jinling; Wang, Renhong

    2015-12-01

    Leaf area index (LAI) is an important indicator for monitoring crop growth conditions and forecasting grain yield. Many algorithms have been developed for remote estimation of the leaf area index of vegetation, such as using spectral vegetation indices, inversion of radiative transfer models, and supervised learning techniques. Spectral vegetation indices, mathematical combination of reflectance bands, are widely used for LAI estimation due to their computational simplicity and their applications ranged from the leaf scale to the entire globe. However, in many cases, their applicability is limited to specific vegetation types or local conditions due to species specific nature of the relationship used to transfer the vegetation indices to LAI. The overall objective of this study is to investigate the most suitable vegetation index for estimating winter wheat LAI under eight different types of fertilizer and irrigation conditions. Regression models were used to estimate LAI using hyperspectral reflectance data from the Pushbroom Hyperspectral Imager (PHI) and in-situ measurements. Our results showed that, among six vegetation indices investigated, the modified soil-adjusted vegetation index (MSAVI) and the normalized difference vegetation index (NDVI) exhibited strong and significant relationships with LAI, and thus were sensitive across different nitrogen and water treatments. The modified triangular vegetation index (MTVI2) confirmed its potential on crop LAI estimation, although second to MSAVI and NDVI in our study. The enhanced vegetation index (EVI) showed moderate performance. However, the ratio vegetation index (RVI) and the modified simple ratio index (MSR) predicted the least accurate estimations of LAI, exposing the simple band ratio index's weakness under different treatment conditions. The results support the use of vegetation indices for a quick and effective LAI mapping procedure that is suitable for winter wheat under different management practices.

  2. Diversity of Genome Structure in Salmonella enterica Serovar Typhi Populations†

    PubMed Central

    Kothapalli, Sushma; Nair, Satheesh; Alokam, Suneetha; Pang, Tikki; Khakhria, Rasik; Woodward, David; Johnson, Wendy; Stocker, Bruce A. D.; Sanderson, Kenneth E.; Liu, Shu-Lin

    2005-01-01

    The genomes of most strains of Salmonella and Escherichia coli are highly conserved. In contrast, all 136 wild-type strains of Salmonella enterica serovar Typhi analyzed by partial digestion with I-CeuI (an endonuclease which cuts within the rrn operons) and pulsed-field gel electrophoresis and by PCR have rearrangements due to homologous recombination between the rrn operons leading to inversions and translocations. Recombination between rrn operons in culture is known to be equally frequent in S. enterica serovar Typhi and S. enterica serovar Typhimurium; thus, the recombinants in S. enterica serovar Typhi, but not those in S. enterica serovar Typhimurium, are able to survive in nature. However, even in S. enterica serovar Typhi the need for genome balance and the need for gene dosage impose limits on rearrangements. Of 100 strains of genome types 1 to 6, 72 were only 25.5 kb off genome balance (the relative lengths of the replichores during bidirectional replication from oriC to the termination of replication [Ter]), while 28 strains were less balanced (41 kb off balance), indicating that the survival of the best-balanced strains was greater. In addition, the need for appropriate gene dosage apparently selected against rearrangements which moved genes from their accustomed distance from oriC. Although rearrangements involving the seven rrn operons are very common in S. enterica serovar Typhi, other duplicated regions, such as the 25 IS200 elements, are very rarely involved in rearrangements. Large deletions and insertions in the genome are uncommon, except for deletions of Salmonella pathogenicity island 7 (usually 134 kb) from fragment I-CeuI-G and 40-kb insertions, possibly a prophage, in fragment I-CeuI-E. The phage types were determined, and the origins of the phage types appeared to be independent of the origins of the genome types. PMID:15805510

  3. Leptospira interrogans at the human-wildlife interface in northern Botswana: a newly identified public health threat.

    PubMed

    Jobbins, S E; Sanderson, C E; Alexander, K A

    2014-03-01

    Leptospirosis is the most widespread zoonosis in the world. In northern Botswana, humans live in close proximity to a diversity of wildlife and peridomestic rodents and may be exposed to a variety of zoonotic pathogens. Little is known regarding the occurrence and epidemiology of L. interrogans in Africa despite the recognized global importance of this zoonotic disease and the threat it poses to public health. In Botswana, banded mongooses (Mungos mungo) live in close proximity to humans across protected and unprotected landscapes and may be a useful sentinel species for assessing the occurrence of zoonotic organisms, such as L. interrogans. We utilized PCR to screen banded mongoose kidneys for leptospiral DNA and identified 41.5% prevalence of renal carriage of L. interrogans (exact binomial 95% CI 27.7-56.7%, n = 41). Renal carriage was also detected in one Selous' mongoose (Paracynictis selousi). This is the first published confirmation of carriage of L. interrogans in either species. This is also the first report of L. interrogans occurrence in northern Botswana and the only report of this organism in a wildlife host in the country. Pathogenic Leptospira are usually transmitted indirectly to humans through soil or water contaminated with infected urine. Other avenues, such as direct contact between humans and wildlife, as well as consumption of mongooses and other wildlife as bushmeat, may pose additional exposure risk and must be considered in public health management of this newly identified zoonotic disease threat. There is a critical need to characterize host species involvement and pathogen transmission dynamics, including human-wildlife interactions that may increase human exposure potential and infection risk. We recommend that public health strategy be modified to include sensitization of medical practitioners to the presence of L. interrogans in the region, the potential for human infection, and implementation of clinical screening. This study

  4. [Professor LAI Xinsheng's treatment experience of infertility by Tongyuan needling technique].

    PubMed

    Li, Yuemei; Meng, Zhenzhen; Wang, Ranran

    2015-03-01

    Professor LAI Xinsheng's treatment experience of infertility mainly by Tongyuan needling technique for both females and males is summarized. Tongyuan needling technique is a treatment method of leading qi to its primordial location mainly through viscera back-shu points that can dredge the governor vessel and tonify the spirit and conception vessel points in abdomen and abdominal front-mu points, and according to state of illness acupoints for opening the 4 gates or five shu points are combined; reinforcing and reducing manipulations of acupuncture are applied for reference. With the method of listing cases, professor LAI Xinsheng's Tongyuan needling technique is detailedly introduced in different aspects, such as the treatment of polycystic ovary syndrome infertility and male infertility and improving the success rate of test-tube baby, and the manipulation of Tongyuan needling technique is summarized, indicating that Tongyuan needling technique is worth vigorously prompting in clinical treatment of infertility. PMID:26062206

  5. Temporal Stability of the NDVI-LAI Relationship in a Napa Valley Vineyard

    NASA Technical Reports Server (NTRS)

    Johnson, L. F.

    2003-01-01

    Remotely sensed normalized difference vegetation index (NDVI) values, derived from high-resolution satellite images, were compared with ground measurements of vineyard leaf area index (LAI) periodically during the 2001 growing season. The two variables were strongly related at six ground calibration sites on each of four occasions (r squared = 0.91 to 0.98). Linear regression equations relating the two variables did not significantly differ by observation date, and a single equation accounted for 92 percent of the variance in the combined dataset. Temporal stability of the relationship opens the possibility of transforming NDVI maps to LAI in the absence of repeated ground calibration fieldwork. In order to take advantage of this circumstance, however, steps should be taken to assure temporal consistency in spectral data values comprising the NDVI.

  6. GEOLAND2 global LAI, FAPAR Essential Climate Variables for terrestrial carbon modeling: principles and validation

    NASA Astrophysics Data System (ADS)

    Baret, F.; Weiss, M.; Lacaze, R.; Camacho, F.; Smets, B.; Pacholczyk, P.; Makhmara, H.

    2010-12-01

    LAI and fAPAR are recognized as Essential Climate Variables providing key information for the understanding and modeling of canopy functioning. Global remote sensing observations at medium resolution are routinely acquired since the 80’s mainly with AVHRR, SEAWIFS, VEGETATION, MODIS and MERIS sensors. Several operational products have been derived and provide global maps of LAI and fAPAR at daily to monthly time steps. Inter-comparison between MODIS, CYCLOPES, GLOBCARBON and JRC-FAPAR products showed generally consistent seasonality, while large differences in magnitude and smoothness may be observed. One of the objectives of the GEOLAND2 European project is to develop such core products to be used in a range of application services including the carbon monitoring. Rather than generating an additional product from scratch, the version 1 of GEOLAND2 products was capitalizing on the existing products by combining them to retain their pros and limit their cons. For these reasons, MODIS and CYCLOPES products were selected since they both include LAI and fAPAR while having relatively close temporal sampling intervals (8 to 10 days). GLOBCARBON products were not used here because of the too long monthly time step inducing large uncertainties in the seasonality description. JRC-FAPAR was not selected as well to preserve better consistency between LAI and fAPAR products. MODIS and CYCLOPES products were then linearly combined to take advantage of the good performances of CYCLOPES products for low to medium values of LAI and fAPAR while benefiting from the better MODIS performances for the highest LAI values. A training database representative of the global variability of vegetation type and conditions was thus built. A back-propagation neural network was then calibrated to estimate the new LAI and fAPAR products from VEGETATION preprocessed observations. Similarly, the vegetation cover fraction (fCover) was also derived by scaling the original CYCLOPES fCover products

  7. BOREAS RSS-7 Regional LAI and FPAR Images From 10-Day AVHRR-LAC Composites

    NASA Technical Reports Server (NTRS)

    Hall, Forrest G. (Editor); Nickeson, Jaime (Editor); Chen, Jing; Cihlar, Josef

    2000-01-01

    The BOReal Ecosystem-Atmosphere Study Remote Sensing Science (BOREAS RSS-7) team collected various data sets to develop and validate an algorithm to allow the retrieval of the spatial distribution of Leaf Area Index (LAI) from remotely sensed images. Advanced Very High Resolution Radiometer (AVHRR) level-4c 10-day composite Normalized Difference Vegetation Index (NDVI) images produced at CCRS were used to produce images of LAI and the Fraction of Photosynthetically Active Radiation (FPAR) absorbed by plant canopies for the three summer IFCs in 1994 across the BOREAS region. The algorithms were developed based on ground measurements and Landsat Thematic Mapper (TM) images. The data are stored in binary image format files.

  8. Persistence and growth of different Salmonella serovars on pre- and postharvest tomatoes.

    PubMed

    Shi, X; Namvar, A; Kostrzynska, M; Hora, R; Warriner, K

    2007-12-01

    The interaction of a range of Salmonella serovars with pre- and postharvest tomatoes was evaluated. Serovars were selected on the basis of previous association in tomato-linked outbreaks of salmonellosis (Salmonella Javiana, Salmonella Montevideo, and Salmonella Newport) or those typically isolated from animal or clinical infections (Salmonella Dublin, Salmonella Enteritidis, Salmonella Hadar, Salmonella Infantis, Salmonella Typhimurium, and Salmonella Senftenberg). Salmonella serovars introduced onto the flowers of growing plants were recovered on and within the developing tomato fruit. Of all the Salmonella serovars tested, Montevideo appeared to be more adapted to survival within tomatoes and was recovered from 90% of the fruit screened. All of the Salmonella serovars could persist and grow when introduced onto unripened (green) tomato fruit. In general, growth (internal and external) was promoted at the high incubation temperature (25 degrees C) and high relative humidity (95%), although this was serovar dependent. The growth and persistence of Salmonella introduced on and into ripened (red) tomatoes was serovar dependent. Salmonella serovars Enteritidis, Typhimurium, and Dublin were less adapted to grow in or on intact red tomatoes than were serovars Hadar, Montevideo, or Newport. The results illustrated that a diverse range of Salmonella serovars can become established within and/or on preharvest tomatoes. The majority of Salmonella can grow and become established both on and within unripened tomatoes, but growth on ripened fruit was serovar dependent. The results provide a possible explanation why only a narrow range of Salmonella serovars are associated with foodborne illness outbreaks linked to tomatoes. PMID:18095423

  9. Efficacy of LAI in first episode psychosis: an observational study--clinical reports.

    PubMed

    Cervone, Alba; D'Onghia, Antonio; Ferrara, Maria; Massaro, Claudio R M

    2015-09-01

    The use of antipsychotics, especially second generation antipsychotics, represents the milestone treatment of "first episode of psychosis" (FEP). Although prodromal symptoms of psychosis have long been recognized, the clinical management of psychotic disorders conventionally begins at the first episode of frank psychosis, as it is well acknowledged that "duration of untreated psychosis" (DUP) is one of the main factor that negatively affects prognosis: a longer DUP is highly correlated to reduced response to treatment, poor clinical and social outcomes, and an overall worst prognosis. Long-acting injectable (LAI) formulations of antipsychotics have traditionally been used for those patients with psychosis with the most severe symptoms, poorest compliance, most hospitalizations and poorest outcomes; moreover it seems that psychiatrists tend to prescribe LAI at the latter stages of the disease. We retrospectively collected clinical and sociodemographic data regarding patients consecutively presenting with symptoms of FEP attending the Community Mental Health Service (CMHS) in Foggia from 1st June 2014 to 31st May 2015. We selected patients who attended the CMHS in Foggia with symptoms of FEP. Different scales were administered to assess symptoms severity, quality of life, side effects, adherence, and overall functionality. In our sample LAI treatment was found to be effective in treating symptoms associated to FEP, improved quality of life and it was associated with a clinically irrelevant incidence of extrapyramidal side effect. Considering that achieving a full symptoms remission in people affected by FEP is associated to better outcomes, and that DUP is associated to poor prognosis, LAIs could play an important role in improving overall recovery. PMID:26417794

  10. Climate, Plant Biomass, NDVI, and LAI Relationships Along The Full Arctic Bioclimate Gradient

    NASA Astrophysics Data System (ADS)

    Epstein, H. E.; Walker, D. A.; Jia, G. J.; Kelley, A. M.

    2005-12-01

    A common methodology for assessing the potential effects of terrestrial ecosystems to environmental change is to develop present-day spatial relationships between environmental variables and ecosystem properties. Spatial relationships between climate variables and ecosystem variables should of course be used cautiously when extrapolating these patterns over time, i.e. space-for-time substitutions. Nevertheless, this approach has been extremely useful along regional climate gradients, in addition to providing support for vegetation dynamics models. We are developing several datasets of latitude, temperature, aboveground plant biomass, the NDVI (normalized difference vegetation index) and LAI (leaf area index) for arctic tundra ecosystems along an 1800-km transect from the Low Arctic tundra in northern Alaska to the Polar Desert of the northern Canadian Archipelago. Another useful application of these data is the relationships between NDVI and aboveground plant biomass, which can allow for the conversion of satellite data to on-the-ground ecosystem properties. For the portion of our transect on the northern slope of Alaska, NDVI (from NOAA AVHRR data) decreased with increasing latitude, explaining 45% of the variance in LAI, 65% of aboveground biomass and 42% of shrub biomass. Along the same portion of the transect, LAI (measured from above the mosses and lichens) explained 69% of vascular plant biomass and 68% of shrub biomass. For the higher arctic portion of the transect, NDVI (measured using a handheld spectroradiometer) continued to decrease with latitude, and latitude explained 90% of the variation in NDVI. For these sites in the High Arctic, NDVI was most strongly related to the sum of moss and graminoid biomass (r2=0.60). Ultimately, our dataset will contain climate data, satellite NDVI, handheld NDVI, LAI, and various components of aboveground plant biomass for a complete synthesis along the full arctic bioclimate gradient.

  11. Spatiotemporal NDVI, LAI, albedo, and surface temperature dynamics in the southwest of the Brazilian Amazon forest

    NASA Astrophysics Data System (ADS)

    Querino, Carlos Alexandre Santos; Beneditti, Cristina Aparecida; Machado, Nadja Gomes; da Silva, Marcelo José Gama; da Silva Querino, Juliane Kayse Albuquerque; dos Santos Neto, Luiz Alves; Biudes, Marcelo Sacardi

    2016-04-01

    During the last decades, the Amazon rainforest underwent uncontrolled exploitation that modified its environmental variables. The current paper analyzes the spatiotemporal dynamics of the normalized difference vegetation index (NDVI), leaf area index (LAI), and surface albedo, and temperature in two different vegetation covers, preserved and deforested areas. We calculated the remote-sensing products using Landsat 5 TM images obtained during the dry season 1984, 1991, 2000, and 2011 of the central region of the State of Rondônia, Brazil. The results showed a reduction of vegetation indexes NDVI (˜0.70 in 1984 to ˜0.27 in 2011) and LAI (˜1.8 in 1984 to ˜0.3 in 2011), with an increase of surface albedo (0.12 in 1984 to 0.20 in 2011) and temperature (˜24°C in 1984 to 30°C in 2011) as the effect of the rainforest converted in grassland during the study period. No changes in any variables were observed in the protected area. Forest conversion into grassland resulted in a decrease of 69% in NDVI and 110% in LAI and a rise of 59% and 24% in albedo and surface temperature, respectively.

  12. Discovery of a trachyte ignimbrite sequence at Hualālai, Hawaii

    NASA Astrophysics Data System (ADS)

    Shea, Thomas; Owen, Jacqueline

    2016-05-01

    Ignimbrites are common in many intraplate ocean islands but have been missing from the known geological record in Hawaii. During a recent field campaign, the remnants of a trachytic ignimbrite sequence have been discovered at Hualālai volcano, fortuitously preserved from subsequent basaltic lava flow cover. We provide a preliminary description of these deposits, as well as bulk and glass chemical analyses to determine their potential relationship with other nearby trachytes from Pu'u Wa'awa'a (PWW) and Pu'u Anahulu (PA). The results suggest that these ignimbrites are from neither PWW nor PA, but instead may relate to trachytes that are found as maar wallrock blocks some 20 km distant. Therefore, despite being rare overall in Hawaii, the ignimbrites—and more generally trachytes—were probably widespread around Hualālai. Compared to other intraplate ocean islands, the combination of a fast-moving plate, high magma supply, and eruption rates underneath Hawaiian volcanoes may explain the scarcity of ignimbrites preserved at the surface. Their presence at Hualālai could reflect unusual conditions of edifice stress during the transition from shield to post-shield volcanism.

  13. The Importance of Measurement Errors for Deriving Accurate Reference Leaf Area Index Maps for Validation of Moderate-Resolution Satellite LAI Products

    NASA Technical Reports Server (NTRS)

    Huang, Dong; Yang, Wenze; Tan, Bin; Rautiainen, Miina; Zhang, Ping; Hu, Jiannan; Shabanov, Nikolay V.; Linder, Sune; Knyazikhin, Yuri; Myneni, Ranga B.

    2006-01-01

    The validation of moderate-resolution satellite leaf area index (LAI) products such as those operationally generated from the Moderate Resolution Imaging Spectroradiometer (MODIS) sensor data requires reference LAI maps developed from field LAI measurements and fine-resolution satellite data. Errors in field measurements and satellite data determine the accuracy of the reference LAI maps. This paper describes a method by which reference maps of known accuracy can be generated with knowledge of errors in fine-resolution satellite data. The method is demonstrated with data from an international field campaign in a boreal coniferous forest in northern Sweden, and Enhanced Thematic Mapper Plus images. The reference LAI map thus generated is used to assess modifications to the MODIS LAI/fPAR algorithm recently implemented to derive the next generation of the MODIS LAI/fPAR product for this important biome type.

  14. How Universal Is the Relationship Between Remotely Sensed Vegetation Indices (VI) and Crop Leaf Area Index (LAI)?

    NASA Technical Reports Server (NTRS)

    Kang, Yanghui; Ozdogan, Mutlu; Zipper, Samuel C.; Roman, Miguel

    2016-01-01

    Global LAI-VI relationships are statistically significant, crop-specific, and mostly non-linear. This research enables the operationalization of large-area crop modeling and, by extension, has relevance to both fundamental and applied agroecosystem research.

  15. The α-hydroxyketone LAI-1 regulates motility, Lqs-dependent phosphorylation signalling and gene expression of Legionella pneumophila.

    PubMed

    Schell, Ursula; Simon, Sylvia; Sahr, Tobias; Hager, Dominik; Albers, Michael F; Kessler, Aline; Fahrnbauer, Felix; Trauner, Dirk; Hedberg, Christian; Buchrieser, Carmen; Hilbi, Hubert

    2016-02-01

    The causative agent of Legionnaires' disease, Legionella pneumophila, employs the autoinducer compound LAI-1 (3-hydroxypentadecane-4-one) for cell-cell communication. LAI-1 is produced and detected by the Lqs (Legionella quorum sensing) system, comprising the autoinducer synthase LqsA, the sensor kinases LqsS and LqsT, as well as the response regulator LqsR. Lqs-regulated processes include pathogen-host interactions, production of extracellular filaments and natural competence for DNA uptake. Here we show that synthetic LAI-1 promotes the motility of L. pneumophila by signalling through LqsS/LqsT and LqsR. Upon addition of LAI-1, autophosphorylation of LqsS/LqsT by [γ-(32) P]-ATP was inhibited in a dose-dependent manner. In contrast, the Vibrio cholerae autoinducer CAI-1 (3-hydroxytridecane-4-one) promoted the phosphorylation of LqsS (but not LqsT). LAI-1 did neither affect the stability of phospho-LqsS or phospho-LqsT, nor the dephosphorylation by LqsR. Transcriptome analysis of L. pneumophila treated with LAI-1 revealed that the compound positively regulates a number of genes, including the non-coding RNAs rsmY and rsmZ, and negatively regulates the RNA-binding global regulator crsA. Accordingly, LAI-1 controls the switch from the replicative to the transmissive growth phase of L. pneumophila. In summary, the findings indicate that LAI-1 regulates motility and the biphasic life style of L. pneumophila through LqsS- and LqsT-dependent phosphorylation signalling. PMID:26538361

  16. Digital Cover Photography for Estimating Leaf Area Index (LAI) in Apple Trees Using a Variable Light Extinction Coefficient

    PubMed Central

    Poblete-Echeverría, Carlos; Fuentes, Sigfredo; Ortega-Farias, Samuel; Gonzalez-Talice, Jaime; Yuri, Jose Antonio

    2015-01-01

    Leaf area index (LAI) is one of the key biophysical variables required for crop modeling. Direct LAI measurements are time consuming and difficult to obtain for experimental and commercial fruit orchards. Devices used to estimate LAI have shown considerable errors when compared to ground-truth or destructive measurements, requiring tedious site-specific calibrations. The objective of this study was to test the performance of a modified digital cover photography method to estimate LAI in apple trees using conventional digital photography and instantaneous measurements of incident radiation (Io) and transmitted radiation (I) through the canopy. Leaf area of 40 single apple trees were measured destructively to obtain real leaf area index (LAID), which was compared with LAI estimated by the proposed digital photography method (LAIM). Results showed that the LAIM was able to estimate LAID with an error of 25% using a constant light extinction coefficient (k = 0.68). However, when k was estimated using an exponential function based on the fraction of foliage cover (ff) derived from images, the error was reduced to 18%. Furthermore, when measurements of light intercepted by the canopy (Ic) were used as a proxy value for k, the method presented an error of only 9%. These results have shown that by using a proxy k value, estimated by Ic, helped to increase accuracy of LAI estimates using digital cover images for apple trees with different canopy sizes and under field conditions. PMID:25635411

  17. Generation of Mammalian Host-adapted Leptospira interrogans by Cultivation in Peritoneal Dialysis Membrane Chamber Implantation in Rats

    PubMed Central

    Grassmann, André Alex; McBride, Alan John Alexander; Nally, Jarlath E.; Caimano, Melissa J.

    2015-01-01

    Leptospira interrogans can infect a myriad of mammalian hosts, including humans (Bharti et al., 2003; Ko et al., 2009). Following acquisition by a suitable host, leptospires disseminate via the bloodstream to multiple tissues, including the kidneys, where they adhere to and colonize the proximal convoluted renal tubules (Athanazio et al., 2008). Infected hosts shed large number of spirochetes in their urine and the leptospires can survive in different environmental conditions before transmission to another host. Differential gene expression by Leptospira spp. permits adaption to these new conditions. Here we describe a protocol for the cultivation of Leptospira interrogans within Dialysis Membrane Chambers (DMCs) implanted into the peritoneal cavities of Sprague-Dawley rats (Caimano et al., 2014). This technique was originally developed to study mammalian adaption by the Lyme disease spirochete, Borrelia burgdorferi (Akins et al., 1998; Caimano, 2005). The small pore size (8,000 MWCO) of the dialysis membrane tubing used for this procedure permits access to host nutrients but excludes host antibodies and immune effector cells. Given the physiological and environmental similarities between DMCs and the proximal convoluted renal tubule, we reasoned that the DMC model would be suitable for studying in vivo gene expression by L. interrogans. In a 20 to 30 min procedure, DMCs containing virulent leptospires are surgically-implanted into the rat peritoneal cavity. Nine to 11 days post-implantation, DMCs are explanted and organisms recovered. Typically, a single DMC yields ~109 mammalian host-adapted leptospires (Caimano et al., 2014). In addition to providing a facile system for studying the transcriptional and physiologic changes pathogenic L. interrogans undergo within the mammal, the DMC model also provides a rationale basis for selecting new targets for mutagenesis and the identification of novel virulence determinants. Caution: Leptospira interrogans is a BSL-2

  18. A methodology to estimate representativeness of LAI station observation for validation: a case study with Chinese Ecosystem Research Network (CERN) in situ data

    NASA Astrophysics Data System (ADS)

    Xu, Baodong; Li, Jing; Liu, Qinhuo; Zeng, Yelu; Yin, Gaofei

    2014-11-01

    Leaf Area Index (LAI) is known as a key vegetation biophysical variable. To effectively use remote sensing LAI products in various disciplines, it is critical to understand the accuracy of them. The common method for the validation of LAI products is firstly establish the empirical relationship between the field data and high-resolution imagery, to derive LAI maps, then aggregate high-resolution LAI maps to match moderate-resolution LAI products. This method is just suited for the small region, and its frequencies of measurement are limited. Therefore, the continuous observing LAI datasets from ground station network are important for the validation of multi-temporal LAI products. However, due to the scale mismatch between the point observation in the ground station and the pixel observation, the direct comparison will bring the scale error. Thus it is needed to evaluate the representativeness of ground station measurement within pixel scale of products for the reasonable validation. In this paper, a case study with Chinese Ecosystem Research Network (CERN) in situ data was taken to introduce a methodology to estimate representativeness of LAI station observation for validating LAI products. We first analyzed the indicators to evaluate the observation representativeness, and then graded the station measurement data. Finally, the LAI measurement data which can represent the pixel scale was used to validate the MODIS, GLASS and GEOV1 LAI products. The result shows that the best agreement is reached between the GLASS and GEOV1, while the lowest uncertainty is achieved by GEOV1 followed by GLASS and MODIS. We conclude that the ground station measurement data can validate multi-temporal LAI products objectively based on the evaluation indicators of station observation representativeness, which can also improve the reliability for the validation of remote sensing products.

  19. Gaussian processes uncertainty estimates in experimental Sentinel-2 LAI and leaf chlorophyll content retrieval

    NASA Astrophysics Data System (ADS)

    Verrelst, Jochem; Rivera, Juan Pablo; Moreno, José; Camps-Valls, Gustavo

    2013-12-01

    ESA's upcoming Sentinel-2 (S2) Multispectral Instrument (MSI) foresees to provide continuity to land monitoring services by relying on optical payload with visible, near infrared and shortwave infrared sensors with high spectral, spatial and temporal resolution. This unprecedented data availability leads to an urgent need for developing robust and accurate retrieval methods, which ideally should provide uncertainty intervals for the predictions. Statistical learning regression algorithms are powerful candidats for the estimation of biophysical parameters from satellite reflectance measurements because of their ability to perform adaptive, nonlinear data fitting. In this paper, we focus on a new emerging technique in the field of Bayesian nonparametric modeling. We exploit Gaussian process regression (GPR) for retrieval, which is an accurate method that also provides uncertainty intervals along with the mean estimates. This distinct feature is not shared by other machine learning approaches. In view of implementing the regressor into operational monitoring applications, here the portability of locally trained GPR models was evaluated. Experimental data came from the ESA-led field campaign SPARC (Barrax, Spain). For various simulated S2 configurations (S2-10m, S2-20m and S2-60m) two important biophysical parameters were estimated: leaf chlorophyll content (LCC) and leaf area index (LAI). Local evaluation of an extended training dataset with more variation over bare soil sites led to improved LCC and LAI mapping with reduced uncertainties. GPR reached the 10% precision required by end users, with for LCC a NRMSE of 3.5-9.2% (r2: 0.95-0.99) and for LAI a NRMSE of 6.5-7.3% (r2: 0.95-0.96). The developed GPR models were subsequently applied to simulated Sentinel images over various sites. The associated uncertainty maps proved to be a good indicator for evaluating the robustness of the retrieval performance. The generally low uncertainty intervals over vegetated surfaces

  20. Development of a global LAI/ FAPAR estimation algorithm for JAXA's new earth observation satellite,GCOM-C1

    NASA Astrophysics Data System (ADS)

    Ono, Y.; Murakami, H.; Kobayashi, H.; Nasahara, K.; Kajiwara, K.; Honda, Y.

    2013-12-01

    Japan Aerospace eXploration Agency (JAXA) is planning to launch a new earth observation satellite, GCOM-C1 (Global Change Observation Mission 1st-Climate) in the Japanese Fiscal Year 2016. SGLI (Second generation GLobal Imager) is a radiometer, which has 17 channels from near ultraviolet to thermal infrared. Furthermore, it has the features, such as 250m spatial resolution, polarization, and multi-angle observation. In the GCOM-C1 land science team, vegetation index, above ground biomass, LAI (Leaf Area Index), FAPAR (Fraction of Absorbed Photosynthetically Active Radiation), etc. are scheduled to be generated from SGLI data as standard products. These are important in order to estimate terrestrial carbon cycle. In this study, we propose a new LAI and FAPAR estimation algorithm from SGLI data and the proposed algorithm was applied to Terra/ MODIS data. The relation between LAI and BRF (Bidirectional Reflectance Factor) in red and near infrared bands or FAPAR are dependent on crown cover ratio. Therefore, LUT (Look Up Table) of crown cover ratio, LAI and BRF in red and near infrared or FAPAR are created by FLiES which is 3-dimensional radiative transfer model (Kobayashi, H. and H. Iwabuchi (2008), A coupled 1-D atmosphere and 3-D canopy radiative transfer model for canopy reflectance, light environment, and photosynthesis simulation in a heterogeneous landscape, Remote Sensing of Environment, 112, 173-185). First, crown cover ratio is estimated from multiple land surface reflecntace in red and near infrared bands based on LUT of BRF in red and near infrared bands. Next, LAI and FAPAR are estimated from land surface reflectance in red and near infrared band based on estimated crown cover ratio and LUT of BRF in red and near infrared and FAPAR. As a result of applying Terra/ MODIS land surface reflectance product (MOD09), estimated LAI and FAPAR agreed with LAI and FAPAR observed at the AmeriFlux sites.

  1. Method for the detection of Salmonella enterica serovar Enteritidis

    DOEpatents

    Agron, Peter G.; Andersen, Gary L.; Walker, Richard L.

    2008-10-28

    Described herein is the identification of a novel Salmonella enterica serovar Enteritidis locus that serves as a marker for DNA-based identification of this bacterium. In addition, three primer pairs derived from this locus that may be used in a nucleotide detection method to detect the presence of the bacterium are also disclosed herein.

  2. GENOMIC SEQUENCE ANALYSIS OF LEPTOSPIRA BORGPETERSENII SEROVAR HARDJO

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A genomic library from Leptospira borgpetersenii serovar hardjo strain JB197 was prepared by mechanically shearing the DNA and inserting it into a positive selection vector. DNA was prepared from approximately 22,000 random clones and used as templates for automated sequencing. Sequence data was c...

  3. Limited Genetic Diversity in Salmonella enterica Serovar Enteritidis PT13

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Salmonella enterica serovar Enteritidis has emerged as a significant food-borne pathogen throughout the world and it is commonly characterized by phage typing (PT). In Canada, PT4, 8 and 13 are the predominant PTs. Epidemiological subtyping of Salmonella is typically done by PFGE but plasmid profil...

  4. Limited genetic diversity in Salmonella enterica Serovar Enteritidis PT13

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Salmonella enterica serovar Enteritidis has emerged as a significant foodborne pathogen throughout the world and is commonly characterized by phage typing. In Canada phage types (PT) 4, 8 and 13 predominate and in 2005 a large foodborne PT13 outbreak occurred in the province of Ontario. The ability ...

  5. BOREAS RSS-4 1994 Southern Study Area Jack Pine LAI and FPAR Data

    NASA Technical Reports Server (NTRS)

    Hall, Forrest G. (Editor); Nickeson, Jaime (Editor); Plummer, Stephen

    2000-01-01

    The RSS-4 team collected several data sets related to leaf, plant, and stand physical, optical, and chemical properties. This data set contains leaf area indices and FPAR measurements that were taken at the three conifer sites in the BOREAS SSA during August 1993 and at the jack pine tower flux and a subset of auxiliary sites during July and August 1994. The measurements were made with LAI-2000 and Ceptometer instruments. The measurements were taken for the purpose of model parameterization and to test empirical relationships that were hypothesized between biophysical parameters and remotely sensed data. The data are stored in tabular ASCII files.

  6. Identification of genes associated with survival of salmonellaenterica serovar enteridis in chicken egg albumen

    SciTech Connect

    Clavijo, Raul I.; Loui, Cindy; Andersen, Gary L.; Riley, Lee W.; Lu, Sangwei

    2005-07-13

    Salmonella enterica consists of over 2,000 serovars that aremajor causes of morbidity and mortality associated with contaminatedfood. Despite similarities among serovars of Salmonella enterica, manydemonstrate unique host specificities, epidemiological characteristics,and clinical manifestations. One of the unique epidemiologicalcharacteristics of the serovar Enteritidis is that it is the onlybacterium routinely transmitted to humans through intact chicken eggs.Therefore, Salmonella enterica serovar Enteritidis must be able topersist inside chicken eggs to be transmitted to humans, and its survivalin egg is important for its transmission to the human population. Theability of Salmonella enterica serovar Enteritidis to survive in andtransmit through eggs may have contributed to its drastically increasedprevalence in the 1980s and 1990s. In the present study, usingtransposon-mediated mutagenesis, we have identified genes important forthe association of Salmonella enterica serovar Enteritidis with chickeneggs. Our results indicate that genes involved in cell wall structuraland functional integrity, and nucleic acid and amino acid metabolism areimportant for Salmonella enterica serovar Enteritidis to persist in eggalbumen. Two regions unique toSalmonella enterica serovar Enteritidiswere also identified, one of which enhanced the survival of a Salmonellaenterica serovar Typhimurium isolate in egg albumen. The implication ofour results to the serovar specificity of Salmonella enterica is alsoexplored in the present study.

  7. Mycobacterium avium serovars 2 and 8 infections elicit unique activation of the host macrophage immune responses.

    PubMed

    Cebula, B R; Rocco, J M; Maslow, J N; Irani, V R

    2012-12-01

    Mycobacterium avium is an opportunistic pathogen whose pathogenesis is attributed to its serovar-specific glycopeptidolipid (ssGPL), which varies among its 31 serovars. To determine if the presence and type of ssGPLs contribute to M. avium pathogenesis, we infected murine macrophages (mφs) with two M. avium wild type (wt) serovars (2 and 8) and their serovar-null strains. We examined the influence of ssGPL (presence and type) on cytokine production in non-activated (-IFN-γ) and activated (+IFN-γ) mφs, and the bacterial intra-mφ survival over a 6-day infection process. Serovar-2 infections activated TNF-α production that increased over the 6 day period and was capable of controlling the intra-mφ serovar-2 null strain. In contrast, the serovar-8 infection stimulated a strong pro-inflammatory response, but was incapable of removing the invading pathogen, maybe through IL-10 production. It was clear that the intracellular growth of serovar-null in contrast to the wt M. avium strains was easily controlled. Based on our findings and the undisputed fact that M. avium ssGPL is key to its pathogenesis, we conclude that it is not appropriate to dissect the pathogenesis of one M. avium serovar and apply those findings to other serovars. PMID:22991047

  8. Combined Use of Airborne Lidar and DBInSAR Data to Estimate LAI in Temperate Mixed Forests

    NASA Technical Reports Server (NTRS)

    Peduzzi, Alicia; Wynne, Randolph Hamilton; Thomas, Valerie A.; Nelson, Ross F.; Reis, James J.; Sanford, Mark

    2012-01-01

    The objective of this study was to determine whether leaf area index (LAI) in temperate mixed forests is best estimated using multiple-return airborne laser scanning (lidar) data or dual-band, single-pass interferometric synthetic aperture radar data (from GeoSAR) alone, or both in combination. In situ measurements of LAI were made using the LiCor LAI-2000 Plant Canopy Analyzer on 61 plots (21 hardwood, 36 pine, 4 mixed pine hardwood; stand age ranging from 12-164 years; mean height ranging from 0.4 to 41.2 m) in the Appomattox-Buckingham State Forest, Virginia, USA. Lidar distributional metrics were calculated for all returns and for ten one meter deep crown density slices (a new metric), five above and five below the mode of the vegetation returns for each plot. GeoSAR metrics were calculated from the X-band backscatter coefficients (four looks) as well as both X- and P-band interferometric heights and magnitudes for each plot. Lidar metrics alone explained 69% of the variability in LAI, while GeoSAR metrics alone explained 52%. However, combining the lidar and GeoSAR metrics increased the R2 to 0.77 with a CV-RMSE of 0.42. This study indicates the clear potential for X-band backscatter and interferometric height (both now available from spaceborne sensors), when combined with small-footprint lidar data, to improve LAI estimation in temperate mixed forests.

  9. Recognition of patients who would benefit from LAI antipsychotic treatment: how to assess adherence.

    PubMed

    Correll, Christoph U

    2014-11-01

    Many patients with schizophrenia have problems adhering to their medication regimen. Numerous factors affect patients' adherence, such as patient and illness characteristics; medication efficacy, tolerability and formulations; provider and system characteristics; and patients' support networks. To compound this problem, accurately measuring adherence is challenging. Data suggest that clinicians should use multiple methods to assess patients' adherence, including supplementing their own clinical judgment and patient reports with more objective measures. Patients with poor social support, substance abuse disorders, or a history of florid psychosis and those in the earlier phases of their illness may be at risk for nonadherence. Assessing patients for nonadherence is a key step in determining their optimal form of treatment and avoiding frequent switching or deterioration. Doing so, clinicians can identify patients who would potentially benefit from a long-acting injectable (LAI) antipsychotic, which can be a valuable treatment option. Because lack of adherence increases the risk of hospitalization and does not help prevent suicide attempts, clinicians should address barriers to adherence, provide psychoeducation about medication-taking behaviors, and offer a wide range of antipsychotic treatment options, including LAIs, to improve patient outcomes. PMID:25470105

  10. Real-Time PCR Reveals Rapid Dissemination of Leptospira interrogans after Intraperitoneal and Conjunctival Inoculation of Hamsters.

    PubMed

    Wunder, Elsio A; Figueira, Claudio P; Santos, Gisele R; Lourdault, Kristel; Matthias, Michael A; Vinetz, Joseph M; Ramos, Eduardo; Haake, David A; Picardeau, Mathieu; Dos Reis, Mitermayer G; Ko, Albert I

    2016-07-01

    The pathogen Leptospira interrogans is a highly motile spirochete that causes acute and fulminant infections in humans and other accidental hosts. Hematogenous dissemination is important for infection by the pathogen but remains poorly understood because few animal model studies have used sensitive tools to quantify the bacteria. We evaluated the kinetics of leptospiral infection in Golden Syrian hamsters by a sensitive quantitative real-time PCR (TaqMan) with lipl32 as the target gene. The dissemination and bacterial burden were measured after intraperitoneal infection with a high dose (10(8)) or low dose (2.5 × 10(2)) of leptospires. We also examined the conjunctival challenge route to mimic the natural history of infection. Quantification of leptospires in perfused animals revealed that pathogens were detected in all organs of intraperitoneally infected hamsters, including the eye and brain, within 1 h after inoculation of 10(8) virulent L. interrogans bacteria. Peaks of 10(5) to 10(8) leptospires per gram or per milliliter were achieved in blood and all tissues between day 4 and day 8 after intraperitoneal inoculation of high- and low-dose challenges, respectively, coinciding with macroscopic and histological changes. The conjunctival route resulted in a delay in the time to peak organ burden in comparison to intraperitoneal infection, indicating that although infection could be established, penetration efficiency was low across this epithelial barrier. Surprisingly, infection with a large inoculum of high-passage-number attenuated L. interrogans strains resulted in dissemination to all organs in the first 4 days postinfection, albeit with a lower burden, followed by clearance from the blood and organs 7 days postinfection and survival of all animals. These results demonstrate that leptospiral dissemination and tissue invasion occur. In contrast, development of a critical level of tissue burden and pathology are dependent on the virulence of the infecting

  11. Draft Genome Sequences of Salmonella enterica subsp. enterica Serovars Typhimurium and Nottingham Isolated from Food Products

    PubMed Central

    Zheng, Jie; Ayers, Sherry; Melka, David C.; Curry, Phillip E.; Payne, Justin S.; Laasri, Anna; Wang, Charles; Hammack, Thomas S.; Brown, Eric W.

    2016-01-01

    A quantitative real-time PCR (qPCR) designed to detect Salmonella enterica subsp. enterica serovar Enteritidis, targeting the sdf gene, generated positive results for S. enterica subsp. enterica serovar Typhimurium (CFSAN033950) and S. enterica subsp. enterica serovar Nottingham (CFSAN006803) isolated from food samples. Both strains show pulsed-field gel electrophoresis (PFGE) patterns distinct from those of S. Enteritidis. Here, we report the genome sequences of these two strains. PMID:27445384

  12. Validation of Landsat 8 satellite-derived LAI from field measurements in a durum-wheat cropped area in south-eastern Italy

    NASA Astrophysics Data System (ADS)

    Castrignano, A.; Buttafuoco, G.; Toscano, P.; Rinaldi, M.

    2015-12-01

    Leaf area index (LAI) is one of the key biophysical variables to describe land surface processes of fundamental importance for vegetation, such as photosynthesis, transpiration and energy balance. Current spatial missions allow to estimate LAI at global scale, however product validation is needed for its reliable use. In this paper, a methodology is described to derive reference LAI maps from ground-based measurements at the JECAM site of Capitanata using Landsat 8 imagery as auxiliary information and to estimate prediction uncertainty. LAI was measured with LAI-2000 Plant Canopy Analyzer (LI-COR) in 30 experimental sampling units (ESU) of 10 m by 10 m size within a polygon of about 3 km by 3 km size. Two surveys were carried out in 2014: on March 18-20 and on May 9-13. To integrate secondary finer-resolution information in primary sparse variable modelling, multicollocated cokriging was used, where the secondary variable for cokriging estimate is used at the target location and also at all the locations where the primary variable is defined within the neighbourhood of interpolation. To assess prediction uncertainty, Confidence Interval (CI) was calculated and in order to make the values comparable the relative CI was calculated by dividing by the corresponding LAI estimation and assumed as a quality index of LAI product. LAI maps were produced for the two selected dates and from a comparison between radiometric and estimated LAI maps, it results a general high consistency with Landsat 8 imagery. The quality maps derived from LAI estimator for the two dates with overlaid the locations of the sample data points show that to the pixels located near the samples are attributed a quality index of about 40-50% but, as the distance increases, the uncertainty becomes too large. The poor results are probably due to the too coarse sampling, with large areas without any ground-truth data of LAI.

  13. LAI, FAPAR and FCOVER products derived from AVHRR long time series: principles and evaluation

    NASA Astrophysics Data System (ADS)

    Verger, A.; Baret, F.; Weiss, M.; Lacaze, R.; Makhmara, H.; Pacholczyk, P.; Smets, B.; Kandasamy, S.; Vermote, E.

    2012-04-01

    Continuous and long term global monitoring of the terrestrial biosphere has draught an intense interest in the recent years in the context of climate and global change. Developing methodologies for generating historical data records from data collected with different satellite sensors over the past three decades by taking benefits from the improvements identified in the processing of the new generation sensors is a new central issue in remote sensing community. In this context, the Bio-geophysical Parameters (BioPar) service within Geoland2 project (http://www.geoland2.eu) aims at developing pre-operational infrastructures for providing global land products both in near real time and off-line mode with long time series. In this contribution, we describe the principles of the GEOLAND algorithm for generating long term datasets of three key biophysical variables, leaf area index (LAI), Fraction of Absorbed Photosynthetic Active Radiation (FAPAR) and cover fraction (FCOVER), that play a key role in several processes, including photosynthesis, respiration and transpiration. LAI, FAPAR and FCOVER are produced globally from AVHRR Long Term Data Record (LTDR) for the 1981-2000 period at 0.05° spatial resolution and 10 days temporal sampling frequency. The proposed algorithm aims to ensure robustness of the derived long time series and consistency with the ones developed in the recent years, and particularly with GEOLAND products derived from VEGETATION sensor. The approach is based on the capacity of neural networks to learn a particular biophysical product (GEOLAND) from reflectances from another sensor (AVHRR normalized reflectances in the red and near infrared bands). Outliers due to possible cloud contamination or residual atmospheric correction are iteratively eliminated. Prior information based on the climatology is used to get more robust estimates. A specific gap filing and smoothing procedure was applied to generate continuous and smooth time series of decadal

  14. Sources of Uncertainty in the Prediction of LAI / fPAR from MODIS

    NASA Technical Reports Server (NTRS)

    Dungan, Jennifer L.; Ganapol, Barry D.; Brass, James A. (Technical Monitor)

    2002-01-01

    To explicate the sources of uncertainty in the prediction of biophysical variables over space, consider the general equation: where z is a variable with values on some nominal, ordinal, interval or ratio scale; y is a vector of input variables; u is the spatial support of y and z ; x and u are the spatial locations of y and z , respectively; f is a model and B is the vector of the parameters of this model. Any y or z has a value and a spatial extent which is called its support. Viewed in this way, categories of uncertainty are from variable (e.g. measurement), parameter, positional. support and model (e.g. structural) sources. The prediction of Leaf Area Index (LAI) and the fraction of absorbed photosynthetically active radiation (fPAR) are examples of z variables predicted using model(s) as a function of y variables and spatially constant parameters. The MOD15 algorithm is an example of f, called f(sub 1), with parameters including those defined by one of six biome types and solar and view angles. The Leaf Canopy Model (LCM)2, a nested model that combines leaf radiative transfer with a full canopy reflectance model through the phase function, is a simpler though similar radiative transfer approach to f(sub 1). In a previous study, MOD15 and LCM2 gave similar results for the broadleaf forest biome. Differences between these two models can be used to consider the structural uncertainty in prediction results. In an effort to quantify each of the five sources of uncertainty and rank their relative importance for the LAI/fPAR prediction problem, we used recent data for an EOS Core Validation Site in the broadleaf biome with coincident surface reflectance, vegetation index, fPAR and LAI products from the Moderate Resolution Imaging Spectrometer (MODIS). Uncertainty due to support on the input reflectance variable was characterized using Landsat ETM+ data. Input uncertainties were propagated through the LCM2 model and compared with published uncertainties from the MOD15

  15. Leptospira interrogans lpxD Homologue Is Required for Thermal Acclimatization and Virulence.

    PubMed

    Eshghi, Azad; Henderson, Jeremy; Trent, M Stephen; Picardeau, Mathieu

    2015-11-01

    Leptospirosis is an emerging disease with an annual occurrence of over 1 million human cases worldwide. Pathogenic Leptospira bacteria are maintained in zoonotic cycles involving a diverse array of mammals, with the capacity to survive outside the host in aquatic environments. Survival in the diverse environments encountered by Leptospira likely requires various adaptive mechanisms. Little is known about Leptospira outer membrane modification systems, which may contribute to the capacity of these bacteria to successfully inhabit and colonize diverse environments and animal hosts. Leptospira bacteria carry two genes annotated as UDP-3-O-[3-hydroxymyristoyl] glucosamine N-acyltransferase genes (la0512 and la4326 [lpxD1 and lpxD2]) that in other bacteria are involved in the early steps of biosynthesis of lipid A, the membrane lipid anchor of lipopolysaccharide. Inactivation of only one of these genes, la0512/lpxD1, imparted sensitivity to the host physiological temperature (37°C) and rendered the bacteria avirulent in an animal infection model. Polymyxin B sensitivity assays revealed compromised outer membrane integrity in the lpxD1 mutant at host physiological temperature, but structural analysis of lipid A in the mutant revealed only minor changes in the lipid A moiety compared to that found in the wild-type strain. In accordance with this, an in trans complementation restored the phenotypes to a level comparable to that of the wild-type strain. These results suggest that the gene annotated as lpxD1 in Leptospira interrogans plays an important role in temperature adaptation and virulence in the animal infection model. PMID:26283339

  16. Leptospira interrogans lpxD Homologue Is Required for Thermal Acclimatization and Virulence

    PubMed Central

    Eshghi, Azad; Henderson, Jeremy; Trent, M. Stephen

    2015-01-01

    Leptospirosis is an emerging disease with an annual occurrence of over 1 million human cases worldwide. Pathogenic Leptospira bacteria are maintained in zoonotic cycles involving a diverse array of mammals, with the capacity to survive outside the host in aquatic environments. Survival in the diverse environments encountered by Leptospira likely requires various adaptive mechanisms. Little is known about Leptospira outer membrane modification systems, which may contribute to the capacity of these bacteria to successfully inhabit and colonize diverse environments and animal hosts. Leptospira bacteria carry two genes annotated as UDP-3-O-[3-hydroxymyristoyl] glucosamine N-acyltransferase genes (la0512 and la4326 [lpxD1 and lpxD2]) that in other bacteria are involved in the early steps of biosynthesis of lipid A, the membrane lipid anchor of lipopolysaccharide. Inactivation of only one of these genes, la0512/lpxD1, imparted sensitivity to the host physiological temperature (37°C) and rendered the bacteria avirulent in an animal infection model. Polymyxin B sensitivity assays revealed compromised outer membrane integrity in the lpxD1 mutant at host physiological temperature, but structural analysis of lipid A in the mutant revealed only minor changes in the lipid A moiety compared to that found in the wild-type strain. In accordance with this, an in trans complementation restored the phenotypes to a level comparable to that of the wild-type strain. These results suggest that the gene annotated as lpxD1 in Leptospira interrogans plays an important role in temperature adaptation and virulence in the animal infection model. PMID:26283339

  17. Salmonella pathogenicity and host adaptation in chicken-associated serovars.

    PubMed

    Foley, Steven L; Johnson, Timothy J; Ricke, Steven C; Nayak, Rajesh; Danzeisen, Jessica

    2013-12-01

    Enteric pathogens such as Salmonella enterica cause significant morbidity and mortality. S. enterica serovars are a diverse group of pathogens that have evolved to survive in a wide range of environments and across multiple hosts. S. enterica serovars such as S. Typhi, S. Dublin, and S. Gallinarum have a restricted host range, in which they are typically associated with one or a few host species, while S. Enteritidis and S. Typhimurium have broad host ranges. This review examines how S. enterica has evolved through adaptation to different host environments, especially as related to the chicken host, and continues to be an important human pathogen. Several factors impact host range, and these include the acquisition of genes via horizontal gene transfer with plasmids, transposons, and phages, which can potentially expand host range, and the loss of genes or their function, which would reduce the range of hosts that the organism can infect. S. Gallinarum, with a limited host range, has a large number of pseudogenes in its genome compared to broader-host-range serovars. S. enterica serovars such as S. Kentucky and S. Heidelberg also often have plasmids that may help them colonize poultry more efficiently. The ability to colonize different hosts also involves interactions with the host's immune system and commensal organisms that are present. Thus, the factors that impact the ability of Salmonella to colonize a particular host species, such as chickens, are complex and multifactorial, involving the host, the pathogen, and extrinsic pressures. It is the interplay of these factors which leads to the differences in host ranges that we observe today. PMID:24296573

  18. Chromosome-Mediated Multidrug Resistance in Salmonella enterica Serovar Typhi

    PubMed Central

    Alam, Munirul; Kuo, Jung-Che; Liu, Yen-Yi; Wang, Pei-Jen

    2014-01-01

    A salmonella genomic island, designated SGI11, was found in 18 of 26 multidrug-resistant Salmonella enterica serovar Typhi isolates from Bangladesh. SGI11 was an IS1 composite transposon and carried 7 resistance genes that conferred resistance to 5 first-line antimicrobials. Eleven of the 18 SGI11-carrying S. Typhi isolates had developed resistance to high levels of ciprofloxacin. PMID:25367917

  19. Salmonella Pathogenicity and Host Adaptation in Chicken-Associated Serovars

    PubMed Central

    Johnson, Timothy J.; Ricke, Steven C.; Nayak, Rajesh; Danzeisen, Jessica

    2013-01-01

    SUMMARY Enteric pathogens such as Salmonella enterica cause significant morbidity and mortality. S. enterica serovars are a diverse group of pathogens that have evolved to survive in a wide range of environments and across multiple hosts. S. enterica serovars such as S. Typhi, S. Dublin, and S. Gallinarum have a restricted host range, in which they are typically associated with one or a few host species, while S. Enteritidis and S. Typhimurium have broad host ranges. This review examines how S. enterica has evolved through adaptation to different host environments, especially as related to the chicken host, and continues to be an important human pathogen. Several factors impact host range, and these include the acquisition of genes via horizontal gene transfer with plasmids, transposons, and phages, which can potentially expand host range, and the loss of genes or their function, which would reduce the range of hosts that the organism can infect. S. Gallinarum, with a limited host range, has a large number of pseudogenes in its genome compared to broader-host-range serovars. S. enterica serovars such as S. Kentucky and S. Heidelberg also often have plasmids that may help them colonize poultry more efficiently. The ability to colonize different hosts also involves interactions with the host's immune system and commensal organisms that are present. Thus, the factors that impact the ability of Salmonella to colonize a particular host species, such as chickens, are complex and multifactorial, involving the host, the pathogen, and extrinsic pressures. It is the interplay of these factors which leads to the differences in host ranges that we observe today. PMID:24296573

  20. Evaluation of Molecular Methods for Identification of Salmonella Serovars.

    PubMed

    Yoshida, Catherine; Gurnik, Simone; Ahmad, Aaminah; Blimkie, Travis; Murphy, Stephanie A; Kropinski, Andrew M; Nash, John H E

    2016-08-01

    Classification by serotyping is the essential first step in the characterization of Salmonella isolates and is important for surveillance, source tracking, and outbreak detection. To improve detection and reduce the burden of salmonellosis, several rapid and high-throughput molecular Salmonella serotyping methods have been developed.The aim of this study was to compare three commercial kits, Salm SeroGen (Salm Sero-Genotyping AS-1 kit), Check&Trace (Check-Points), and xMAP (xMAP Salmonella serotyping assay), to the Salmonella genoserotyping array (SGSA) developed by our laboratory. They were assessed using a panel of 321 isolates that represent commonly reported serovars from human and nonhuman sources globally. The four methods correctly identified 73.8% to 94.7% of the isolates tested. The methods correctly identified 85% and 98% of the clinically important Salmonella serovars Enteritidis and Typhimurium, respectively. The methods correctly identified 75% to 100% of the nontyphoidal, broad host range Salmonella serovars, including Heidelberg, Hadar, Infantis, Kentucky, Montevideo, Newport, and Virchow. The sensitivity and specificity of Salmonella serovars Typhimurium and Enteritidis ranged from 85% to 100% and 99% to 100%, respectively.It is anticipated that whole-genome sequencing will replace serotyping in public health laboratories in the future. However, at present, it is approximately three times more expensive than molecular methods. Until consistent standards and methodologies are deployed for whole-genome sequencing, data analysis and interlaboratory comparability remain a challenge. The use of molecular serotyping will provide a valuable high-throughput alternative to traditional serotyping. This comprehensive analysis provides a detailed comparison of commercial kits available for the molecular serotyping of Salmonella. PMID:27194688

  1. Emplacement of the most recent lava flows on Hualālai Volcano, Hawai'i

    USGS Publications Warehouse

    Kauahikaua, James P.; Cashman, K.; Clague, D.; Champion, D.; Hagstrum, J.

    2002-01-01

    A detailed field and petrologic study of the ca. 1800 a.d. flows at Hualālai Volcano documents at least two eruptive episodes, the Hu‘ehu‘e flow field ending in 1801, and the Ka‘ūpūlehu flow several decades earlier. The morphology and stratigraphy of the Ka‘ūpūlehu flow require an emplacement duration of several days to weeks. Based on a comparison with recent eruptive activity at Mauna Loa volcano, the eruption cannot have occurred at the anomalously high rate (104–105 m3/s) proposed by previous workers. The hummocky flow surface of the later phase of the Hu‘ehu‘e eruption suggests a duration of months, based on a comparison with recent eruptive activity at Kīlauea Volcano. Although none of the ca. 1800 flows show evidence for extraordinarily fast emplacement or unusual fluid rheologies, both flows show unusual features. The abundant xenoliths for which the Ka‘ūpūlehu flow is famous were transported in numerous episodes of deposition and remobilization, during which they eroded the channel systems through which they traveled. Lava transport in proximal and medial regions of both flow fields was probably through lava tubes, as evidenced by preserved tubes and by the prevalence of pāhoehoe-lined channels that require thermally efficient transport of lava over great distances. Both flows also show abundant evidence for re-occupation of older cones and lava tubes, a characteristic that may typify infrequent eruptions of older volcanic systems. Although lava flows from Hualālai Volcano do not show anomalous eruptive behavior, they pose a substantial hazard for coastal communities of Kona.

  2. Validation of MSG vegetation products: part I. Field retrieval of LAI and FVC from hemispherical photographs

    NASA Astrophysics Data System (ADS)

    Martinez, Beatriz; Baret, Frederic; Camacho-de Coca, Fernando; Garcia-Haro, F. Javier; Verger, Aleixandre; Melia, Joaquin

    2004-10-01

    The Satellite Application Facilities on Land Surface Analysis (LSA SAF) is aimed to produce and disseminate geophysical products using data from EUMETSAT satellites such as the geostationary MSG1 and the polar orbiting METOP. One of the main scientific objectives for LSA SAF validation activities is to provide the User Community with measures of uncertainty for all derived products. In this context, this document is the first of a two-part set which proposes a consistent methodology for the validation of the LSA SAF vegetation products (LAI/FVC/fAPAR) derived from SEVIRI /MSG . The methodology includes (1) an appropriate field data sampling strategy over different test sites, (2) derivation of high-resolution biophysical variable maps over a larger area (approximately the same size as the SPOT4-HRVIR2 multispectral image) along with an associated uncertainty, and (3) up-scaling to medium and coarse (MSG) resolution scales. This paper aims at developing the stage (1) of the methodology at the specific test site of Barrax, an agricultural area in Central Spain (39°3'N, 2°12'W), whereas the part (2) is addressed in a second document (this issue) and the part (3) will be addressed for future tasks. This work includes a detailed description along with an exhaustive analysis of the vegetation product estimates by the hemispherical camera during the SPARC'03 field campaign, which took place in July 2003 at Barrax test site. The hemispherical photographs have proved to provide accurate estimates of biophysical parameters in crop canopies with significant advantages such as the possibility to evaluate the gap fraction in all viewing direction. On the other hand, a test analysis of the (CAN-EYE) software package used for the hemispherical photographs processing was undertaken. This paper also includes the intercomparison with another ground data set collected by the optical instrument LI-COR LAI2000 during the same campaign.

  3. Draft genome of the Leptospira interrogans strains, Acegua, RCA, Prea, and Capivara, obtained from wildlife maintenance hosts and infected domestic animals

    PubMed Central

    Kremer, Frederico S; Eslabão, Marcus R; Jorge, Sérgio; Oliveira, Natasha R; Labonde, Julia; Santos, Monize NP; Monte, Leonardo G; Grassmann, André A; Cunha, Carlos EP; Forster, Karine M; Moreno, Luísa Z; Moreno, Andrea M; Campos, Vinicius F; McBride, Alan JA; Pinto, Luciano S; Dellagostin, Odir A

    2016-01-01

    In the present paper, we announce new draft genomes of four Leptospira interrogans strains named Acegua, RCA, Prea, and Capivara. These strains were isolated in the state of Rio Grande do Sul, Brazil, from cattle, dog, Brazilian guinea pig, and capybara, respectively. PMID:27074260

  4. Draft genome of the Leptospira interrogans strains, Acegua, RCA, Prea, and Capivara, obtained from wildlife maintenance hosts and infected domestic animals.

    PubMed

    Kremer, Frederico S; Eslabão, Marcus R; Jorge, Sérgio; Oliveira, Natasha R; Labonde, Julia; Santos, Monize N P; Monte, Leonardo G; Grassmann, André A; Cunha, Carlos E P; Forster, Karine M; Moreno, Luísa Z; Moreno, Andrea M; Campos, Vinicius F; McBride, Alan J A; Pinto, Luciano S; Dellagostin, Odir A

    2016-04-01

    In the present paper, we announce new draft genomes of four Leptospira interrogans strains named Acegua, RCA, Prea, and Capivara. These strains were isolated in the state of Rio Grande do Sul, Brazil, from cattle, dog, Brazilian guinea pig, and capybara, respectively. PMID:27074260

  5. EPIC-Simulated and MODIS-Derived Leaf Area Index (LAI) Comparisons Across mMltiple Spatial Scales RSAD Oral Poster based session

    EPA Science Inventory

    Leaf Area Index (LAI) is an important parameter in assessing vegetation structure for characterizing forest canopies over large areas at broad spatial scales using satellite remote sensing data. However, satellite-derived LAI products can be limited by obstructed atmospheric cond...

  6. Protective Immunity and Reduced Renal Colonization Induced by Vaccines Containing Recombinant Leptospira interrogans Outer Membrane Proteins and Flagellin Adjuvant.

    PubMed

    Monaris, D; Sbrogio-Almeida, M E; Dib, C C; Canhamero, T A; Souza, G O; Vasconcellos, S A; Ferreira, L C S; Abreu, P A E

    2015-08-01

    Leptospirosis is a global zoonotic disease caused by different Leptospira species, such as Leptospira interrogans, that colonize the renal tubules of wild and domestic animals. Thus far, attempts to develop effective leptospirosis vaccines, both for humans and animals, have failed to induce immune responses capable of conferring protection and simultaneously preventing renal colonization. In this study, we evaluated the protective immunity induced by subunit vaccines containing seven different recombinant Leptospira interrogans outer membrane proteins, including the carboxy-terminal portion of the immunoglobulinlike protein A (LigA(C)) and six novel antigens, combined with aluminum hydroxide (alum) or Salmonella flagellin (FliC) as adjuvants. Hamsters vaccinated with the different formulations elicited high antigen-specific antibody titers. Immunization with LigA(C), either with alum or flagellin, conferred protective immunity but did not prevent renal colonization. Similarly, animals immunized with LigA(C) or LigA(C) coadministered with six leptospiral proteins with alum adjuvant conferred protection but did not reduce renal colonization. In contrast, immunizing animals with the pool of seven antigens in combination with flagellin conferred protection and significantly reduced renal colonization by the pathogen. The present study emphasizes the relevance of antigen composition and added adjuvant in the efficacy of antileptospirosis subunit vaccines and shows the complex relationship between immune responses and renal colonization by the pathogen. PMID:26108285

  7. Protective Immunity and Reduced Renal Colonization Induced by Vaccines Containing Recombinant Leptospira interrogans Outer Membrane Proteins and Flagellin Adjuvant

    PubMed Central

    Monaris, D.; Sbrogio-Almeida, M. E.; Dib, C. C.; Canhamero, T. A.; Souza, G. O.; Vasconcellos, S. A.; Ferreira, L. C. S.

    2015-01-01

    Leptospirosis is a global zoonotic disease caused by different Leptospira species, such as Leptospira interrogans, that colonize the renal tubules of wild and domestic animals. Thus far, attempts to develop effective leptospirosis vaccines, both for humans and animals, have failed to induce immune responses capable of conferring protection and simultaneously preventing renal colonization. In this study, we evaluated the protective immunity induced by subunit vaccines containing seven different recombinant Leptospira interrogans outer membrane proteins, including the carboxy-terminal portion of the immunoglobulinlike protein A (LigAC) and six novel antigens, combined with aluminum hydroxide (alum) or Salmonella flagellin (FliC) as adjuvants. Hamsters vaccinated with the different formulations elicited high antigen-specific antibody titers. Immunization with LigAC, either with alum or flagellin, conferred protective immunity but did not prevent renal colonization. Similarly, animals immunized with LigAC or LigAC coadministered with six leptospiral proteins with alum adjuvant conferred protection but did not reduce renal colonization. In contrast, immunizing animals with the pool of seven antigens in combination with flagellin conferred protection and significantly reduced renal colonization by the pathogen. The present study emphasizes the relevance of antigen composition and added adjuvant in the efficacy of antileptospirosis subunit vaccines and shows the complex relationship between immune responses and renal colonization by the pathogen. PMID:26108285

  8. Characterization of isolates of Salmonella enterica serovar Stanley, a serovar endemic to Asia and associated with travel.

    PubMed

    Hendriksen, Rene S; Le Hello, Simon; Bortolaia, Valeria; Pulsrikarn, Chaiwat; Nielsen, Eva Møller; Pornruangmong, Srirat; Chaichana, Phattharaporn; Svendsen, Christina Aaby; Weill, François-Xavier; Aarestrup, Frank M

    2012-03-01

    Salmonella enterica serovar Stanley (S. Stanley) is a common serovar in Southeast Asia and was the second most common serovar implicated in human salmonellosis in Thailand in the years 2002 to 2007. In contrast, this serovar is relatively uncommon in Europe. The objective of this study was to characterize a collection of S. Stanley strains isolated from Thai (n = 62), Danish (n = 39), and French (n = 24) patients to gain a broader understanding of the genetic diversity, population dynamics, and susceptibility to antimicrobials. All isolates were characterized by pulsed-field gel electrophoresis and antimicrobial susceptibility testing. The molecular mechanisms of resistance to extended-spectrum cephalosporins and plasmid-mediated resistance to quinolones were characterized by PCR and sequencing. Plasmid profiling, replicon typing, and microarray analysis were used to characterize the genetic mechanisms of antimicrobial resistance in 10 extended-spectrum cephalosporinase-producing isolates. Considerable genetic diversity was observed among the isolates characterized with 91 unique XbaI pulsed-field gel electrophoresis (PFGE) patterns, including 17 distinct clusters consisting of two to seven indistinguishable isolates. We found some of the S. Stanley isolates isolated from patients in Europe were acquired during travel to Southeast Asia, including Thailand. The presence of multiple plasmid lineages carrying the extended-spectrum cephalosporinase-encoding bla(CMY-2) gene in S. Stanley isolates from the central part of Thailand was confirmed. Our results emphasize that Thai authorities, as well as authorities in other countries lacking prudent use of antimicrobials, should improve the ongoing efforts to regulate antimicrobial use in agriculture and in clinical settings to limit the spread of multidrug-resistant Salmonella isolates and plasmids among humans and pigs in Thailand and abroad. PMID:22205822

  9. Mapping mangrove leaf area index at the species level using IKONOS and LAI-2000 sensors for the Agua Brava Lagoon, Mexican Pacific

    NASA Astrophysics Data System (ADS)

    Kovacs, John M.; Wang, Jinfei; Flores-Verdugo, Francisco

    2005-01-01

    Using both IKONOS and in situ LAI-2000 sensor data, a map of estimated LAI, based on NDVI, was created for the Agua Brava Lagoon, Mexican Pacific. The LAI values were then aggregated according to four classes; red mangrove ( Rhizophora mangle), healthy white mangrove ( Laguncularia racemosa), poor condition white mangrove and dead mangrove. Of the live mangrove, calculated at approximately 85% of the forest, mean LAI values of 2.49, 1.74 and 0.85 were determined for the red, healthy white and poor condition white mangrove, respectively. Excluding the dead areas, an overall estimated mangrove LAI value of 1.81 was ascertained for the 71 km 2 of mapped mangrove forest. Although the results do suggest the technique as a very rapid and effective method for monitoring the condition of mangroves at the species level, potential limitations are also discussed.

  10. Generating pseudo large footprint waveforms from small footprint full-waveform airborne LiDAR data for the layered retrieval of LAI in orchards.

    PubMed

    Li, Wang; Niu, Zheng; Li, Jing; Chen, Hanyue; Gao, Shuai; Wu, Mingquan; Li, Dong

    2016-05-01

    Leaf area index (LAI) is a key parameter for the study of biogeochemical cycles in ecosystems. Remote sensing techniques have been widely used to estimate LAIs in a wide range of vegetation types. However, limited by the sensor detection capability, considerable fewer studies investigated the layered estimation of LAIs in the vertical direction, which can significantly affect the precision evaluation of vegetation biophysical and biochemical processes. This study tried to generate a kind of pseudo large footprint waveform from the small footprint full-waveform airborne LiDAR data by an aggregation approach. The layered distribution of canopy heights and LAIs were successfully retrieved based on the large footprint waveform data in an agricultural landscape of orchards with typical multi-layer vegetation covers. The Gaussian fitting was conducted on the normalized large footprint waveforms to identify the vertical positions for different vegetation layers. Then, the gap theory was applied to retrieve the layered LAIs. Statistically significant simple linear regression models were fitted between the LiDAR-retrieved and field-observed values for the canopy heights and LAIs in different layers. Satisfactory results were obtained with a root mean square error of 0.36 m for the overstorey canopy height (R2 = 0.82), 0.29 m for the understory canopy height (R2 = 0.76), 0.28 for overstorey LAI (R2 = 0.75), 0.40 for understory LAI (R2 = 0.64), and 0.38 for total LAI (R2 = 0.69), respectively. To conclude, estimating the layered LAIs in the multi-layer agriculture orchards from the pseudo large footprint waveforms is feasible and the estimation errors are acceptable, which will provide some new ideas and methods for the quantitative remote sensing with vegetation. PMID:27137623