Inactivation of the gene encoding zinc-binding lipoprotein 103 impairs the infectivity of Streptococcus suis     

Aranda J  Teixidó L  Fittipaldi N  Cortés P  Llagostera M  Gottschalk M  Barbé J 《Canadian journal of veterinary research》2012,76(1):72-76

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Biological characteristics and pathogenicity of avian Escherichia coli strains.     

Wanderley Dias da Silveira  Alessandra Ferreira  Marcelo Brocchi  Luciana Maria de Hollanda  Antonio Fernando Pestana de Castro  Aureo Tatsumi Yamada  Marcelo Lancellotti 《Veterinary microbiology》2002,85(1):47-53

Fifty avian (chicken) pathogenic Escherichia coli strains (APEC) isolated from individuals suffering from omphalitis, septicaemia and swollen head syndrome, and 30 strains isolated from healthy chickens were studied regarding their biological characteristics such as serogroups, haemolysin, colicin, cytotoxin, toxin and siderophore production, adhesion capacity to in vitro cultivated cells, and absorption of Congo red dye. Serotyping demonstrated that most of the omphalitis and normal strains were untypable, whereas most of the septicaemic strains were either untypable or rough. There was no prevalent serogroup among the pathogenic strains studied. The capacity for adhesion and invasion of in vitro cultured cells (HeLa, HEp-2, KPCC), as well as the agglutination of different types of red blood cells and the LD50 of each strain were also evaluated. No correlation was observed between the biological characteristics and pathogenicity, except that colicin was characteristically produced by swollen head syndrome E. coli strains. No correlation was found between adhesion or haemagglutination patterns and pathogenicity. Only six of the 50 strains revealed invasive capacity and the strain that best invaded the cell lines was the one with the lowest LD50.  相似文献   

Early evaluation of popcorn inbred lines for phosphorus use efficiency     

Gabriel B. Mundim  José Marcelo S. Viana  Ciro Maia 《Plant Breeding》2013,132(6):613-619

Phosphorus use efficiency (PUE) evaluation based on shoot dry weight in the early stages of plant development can be a useful measure to identify genotypes that are superior in phosphorus (P) use. The objectives of this study were to (i) identify inbred lines that are efficient and inefficient in P use, (ii) assess the genetic diversity among the inbred lines based on traits related to PUE, (iii) investigate the relationship among traits related to PUE and its components and (iv) estimate the expected responses to selection for increasing PUE. Twenty‐three S₆ popcorn inbred lines were evaluated under high and low P, and several traits related to PUE and its components were measured. Efficient and inefficient inbred lines under each P level were identified, and the genetic diversity assessment grouped these inbred lines in opposite clusters. Phosphorus acquisition efficiency (PAE) was the most important component of PUE in the early stages of plant development, and the direct selection for PAE seems to be the best method for increasing PUE in these stages.  相似文献   

Susceptibility of provenances and families of Pinus maximinoi and Pinus tecunumanii to frost in South Africa     

R. G. Mitchell  M. J. Wingfield  G. R. Hodge  W. S. Dvorak  T. A. Coutinho 《New Forests》2013,44(1):135-146

The future of South Africa’s most important pine species, Pinus patula, is threatened by the pitch canker fungus, Fusarium circinatum. Pinus maximinoi and P. tecunumanii represent two subtropical species that provide an alternative to planting P. patula on the warmer sites of South Africa. Extending the planting range of P. tecunumanii and P. maximinoi to include higher and colder altitude sites will reduce the area planted to P. patula and the risk of F. circinatum. During 2007 progeny trials of P. tecunumanii and P. maximinoi were planted on a sub-tropical and sub-temperate site. Shortly after the establishment of these trials, unusually cold weather conditions were experienced across South Africa (?3°C at the sub-temperate site) resulting in severe mortality. This provided the opportunity to assess the variation in survival as a measure of frost tolerance within these two species to determine whether it could be improved upon through selection. Results indicated that the variation in survival was under genetic control in P. tecunumanii (h _(0,1) ²  = 0.16, h _L ²  = 0.27) and P. maximinoi (h _(0,1) ²  = 0.11, h _L ²  = 0.23) at the sub-temperate site. Correlations in provenance ranking for survival across sites were high for both species. Moderate correlations in family survival for P. tecunumanii (r = 0.52) were found at the two sites. Improvements in cold tolerance can thus be made in both species extending their planting range to include greater areas planted to P. patula thereby limiting the risk of F. circinatum.  相似文献   

Multivariate approach for young bull selection from a performance test using multiple traits of economic importance     

Fernando Brito Lopes  Cláudio Ulhôa Magnabosco  Mariana Márcia Mamede  Marcelo Corrêa da Silva  Eliane Sayuri Myiage  Fernanda Paulini  Raysildo Barbosa Lôbo 《Tropical animal health and production》2013,45(6):1375-1381

This study used multivariate statistics to identify clusters of animals with similar expected progeny difference (EPD) and also identify leading traits that discriminate between bulls. Various linear selection indices based on specific selection criteria were proposed. Records were collected from 880 young Nelore bulls submitted to performance testing in central Brazil between 2001 and 2012. Pre-weaning average daily gain and weights at 210 days with direct and maternal effects were used in the analysis, in addition to post-weaning weight, scrotal circumference at 365 and 450 days, carcass finish and rib eye area. EPDs were classified into three groups, and the EPD means of two of these groups stood out and were considered important based on principal component analysis that associated higher values of direct EPD of weights, average daily weight gain and scrotal circumference. The EPDs for weight at 210, 365 and 450 days, pre- and post-weaning daily gain and scrotal circumference at 365 and 450 days were major causes of variation. Each linear selection index proposed (SI₁, SI₂, SI₃, SI₄ and SI₅) defined a specific approach meaning that a different selection index should be used depending on breeding goals and selection criteria.  相似文献   

Relationships between reflectance and absorbance chlorophyll indices with RGB (Red,Green, Blue) image components in seedlings of tropical tree species at nursery stage     

do Amaral  Elizabeth Santos  Vieira Silva  Daniela  Dos Anjos  Letícia  Schilling  Ana Cristina  Dalmolin  Ândrea Carla  Mielke  Marcelo Schramm 《New Forests》2019,50(3):377-388

Methods based on RGB (Red, Green, Blue) image segmentation may emerge as a new and low-cost method for estimation the quality of tree seedlings. However, the vast number of indexes based on the use of the RGB image segmentation and the lack of references in the literature still hinder the widespread use of this technology. Thus, we conducted a study aiming to test the relationships between methods based on absorbance and reflectance, widely used for the estimation of chlorophyll contents and physiological status of trees, and ten indexes based on RGB component analysis. We used leaves of five tropical tree species, belonging to different botanical families. Leaf absorbance was measured using the handheld chlorophyll meter SPAD-502, reflectance was measured using a spectrometer and the RGB indices were obtained from digitalized images of the leaves using a flatbed scanner. Modified linear regression models including all five species were used to relate RGB indices to absorbance and reflectance indices. Data collected from leaves of seedlings of five tropical tree species indicated that digital image processing technology can be a useful and rapid nondestructive method for assessment of physiological status of tree seedlings at nursery stage. Among the RGB indexes tested in this study the R, 2R*(G???B)/(G?+?B) and 2G*(G???B)/(G?+?B) are the most promising for analysis the tropical seedlings physiological status and quality.

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Yerba Maté (Ilex paraguariensis) aqueous extract decreases intestinal SGLT1 gene expression but does not affect other biochemical parameters in alloxan-diabetic Wistar rats     

Oliveira DM  Freitas HS  Souza MF  Arçari DP  Ribeiro ML  Carvalho PO  Bastos DH 《Journal of agricultural and food chemistry》2008,56(22):10527-10532

Yerba maté (Ilex paraguariensis) is rich in polyphenols, especially chlorogenic acids. Evidence suggests that dietary polyphenols could play a role in glucose absorption and metabolism. The aim of this study was to evaluate the antidiabetic properties of yerba maté extract in alloxan-induced diabetic Wistar rats. Animals (n = 41) were divided in four groups: nondiabetic control (NDC, n = 10), nondiabetic yerba maté (NDY, n = 10), diabetic control (DC, n = 11), and diabetic yerba maté (DY, n = 10). The intervention consisted in the administration of yerba maté extract in a 1 g extract/kg body weight dose for 28 days; controls received saline solution only. There were no significant differences in serum glucose, insulin, and hepatic glucose-6-phosphatase activity between the groups that ingested yerba maté extract (NDY and DY) and the controls (NDC and DC). However, the intestinal SGLT1 gene expression was significantly lower in animals that received yerba maté both in upper (p = 0.007) and middle (p < 0.001) small intestine. These results indicate that bioactive compounds present in yerba maté might be capable of interfering in glucose absorption, by decreasing SGLT1 expression.  相似文献   

Secondary Stress Responses in Juvenile Brazilian Flounder,Paralichthys orbignyanus,throughout and after Exposure to Sublethal Levels of Ammonia and Nitrite     

Lucas C. Maltez  Luis A. L. Barbas  Marcelo H. Okamoto  Diogo L. de Alcantara Lopes  Luis A. Romano  Luís A. Sampaio  Luciano Garcia 《Journal of the World Aquaculture Society》2019,50(2):346-358

This study investigated the secondary stress responses of Paralichthys orbignyanus exposed to ammonia and nitrite and after recovery. Fish were exposed to 0.12, 0.28, and 0.57 mg NH₃‐N/L, or 5.72, 10.43, and 15.27 mg NO₂‐N/L for 10 d followed by the same time length for recovery. Ammonia‐ and nitrite‐free water was used as a control treatment. Blood samples were collected after 1, 5, and 10 d of exposure and after recovery. Fish exposed to ammonia presented lower and higher glucose levels after 10 d of exposure and recovery, respectively. Ammonia induced initial and transient ionic disturbances and metabolic alkalosis. Nitrite exposure caused hyperglycemia, increased plasma K⁺ levels, and respiratory alkalosis, whereas metabolic acidosis was observed after recovery. Increased proportion of monocytes and/or granulocytes and reduced number of lymphocytes were demonstrated in fish exposed to 0.28 mg NH₃‐N/L (Day 1) and 10.43 mg NO₂‐N/L (Day 5) and after recovery in the 0.28 and 0.57 mg NH₃‐N/L treatments. Exposure to ammonia decreased the proportion of granulocytes on Day 5. In conclusion, exposure to concentrations at 0.12 mg NH₃‐N/L and 5.72 mg NO₂‐N/L provoked physiological disorders in Brazilian flounder. Nonetheless, fish exposed to 5.72 mg NO₂‐N/L following a 10‐d recovery period showed complete resumption of homeostasis.  相似文献   

Growth and survival of juvenile red drum,Sciaenops ocellatus,acclimated to freshwater at three different stocking densities in a partial recirculation system     

Miguel A. Vela  Humberto Villarreal  Marcelo Araneda  F. J. Espinosa‐Faller 《Journal of the World Aquaculture Society》2019,50(1):87-103

Preliminary technical baseline information for the inland culture of juvenile red drum, Sciaenops ocellatus, in a freshwater fish hatchery is presented. Three initial stocking densities (d₁ = 83, d₂ = 167, and d₃ = 250 fish/m³) were tested in a semirecirculation system for 575 days using a commercially available feed (48.1% protein, 25% lipids, and 0.13% fiber). Initial and final mean fish weight were 7.11 ± 0.02 g and 287.6 ± 27 g. As carrying capacity appeared to have been reached, only data from Days 1–333 were analyzed. One‐way ANOVA analyses indicated that the survival rate of the smaller density (d₁ =40 ± 3.7%) was significantly different from the other two densities (d₃ = 21 ± 1.1% and d₂ = 23 ± 1.0%), which did not differ between them. Absolute growth rate (0.87 ± 0.02 g/day) was not significantly different between densities (F = 0.23. p = .801). Neither was weight significantly different between treatments. There were significant differences in the feed conversion rate (FCR) between densities (F = 8.54; p = .02). FCR for d₁ was significantly lower than for the two other densities, which did not differ from each other. A von Bertalanffy growth model was adjusted (R² = 0.95), and weight–length relationship presented negative allometric values (b = 2.85, R² = 0.98).  相似文献   

Climate‐based seasonal dynamics of the invasive red palm mite Raoiella indica     

Ricardo Siqueira da Silva  Elisngela Gomes Fidelis  George Amaro  Rodrigo Soares Ramos  Paulo Antnio Santana Junior  Marcelo Coutinho Picano 《Pest management science》2020,76(11):3849-3856

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