28 research outputs found

    Mice with Different Susceptibility to Japanese Encephalitis Virus Infection Show Selective Neutralizing Antibody Response and Myeloid Cell Infectivity

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    Japanese encephalitis virus (JEV) is a mosquito-borne flavivirus that causes public health problems in Asian countries. Only a limited number of JEV-infected individuals show symptoms and develop severe encephalitis, indicating host-dependent susceptibilities.C3H/HeN and DBA/2 mice, which exhibit different mortalities when infected by intraperitoneal inoculation with JEV, were used as experimental models to compare viral pathogenesis and host responses. One hundred infectious virus particles killed 95% of C3H/HeN mice whereas only 40% of DBA/2 mice died. JEV RNA was detected with similar low levels in peripheral lymphoid organs and in the sera of both mouse strains. High levels of viral and cytokine RNA were observed simultaneously in the brains of C3H/HeN and DBA/2 mice starting on days 6 and 9 post-infection, respectively. The kinetics of the cytokines in sera correlated with the viral replication in the brain. Significantly earlier and higher titers of neutralizing antibodies were detected in the DBA/2 strain. Primary embryonic fibroblasts, bone marrow-derived dendritic cells and macrophages from the two mouse strains were cultured. Fibroblasts displayed similar JEV replication abilities, whereas DBA/2-derived myeloid antigen-presenting cells had lower viral infectivity and production compared to the C3H/HeN–derived cells. may be elements associated with late and decreased mouse neuroinvasion

    Produtividade e classificação de brócolos para indústria em função da adubação nitrogenada e potássica e dos espaçamentos entre plantas Yield and classification of broccoli depending on fertilizing and spacing between plants

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    No município de Itatiba-SP, no período de março a julho de 2007, foi realizado um experimento com o objetivo de avaliar doses de nitrogênio e potássio e espaçamentos entre plantas na produtividade e classificação de brócolos para indústria. O experimento foi instalado sob delineamento de blocos ao acaso, com os tratamentos em esquema fatorial 5 x 4, e três repetições, sendo avaliadas as doses de nitrogênio-potássio: 105-105; 157,5-157,5; 210-210; 262,5-262,5 e 315-315 kg ha-1 de N e K2O e os espaçamentos entre plantas: 0,2; 0,3; 0,4 e 0,5 m. O espaçamento entre linhas foi de 0,8 m. Foram avaliados o teor foliar de nitrogênio (TN) e de potássio (TP), produtividade de inflorescência (PI), produtividade de floretes (PF), rendimento industrial (RI) e classificação dos floretes com base em seu comprimento: PF5 (<5 cm); PF57 (>5 e <7 cm); PF79 (>7 e <9 cm) e PF9 (>9 cm). Maiores espaçamentos entre plantas proporcionaram maior TN e menores PI e PF. As doses NK e os espaçamentos entre plantas não influenciaram significativamente o TP e o RI. As maiores produtividades de inflorescências (22,08 t ha-1) e de floretes (17,09 t ha-1) foram obtidas com 0,20 m entre plantas e 315 kg ha-1 de N e de K2O. Maior percentagem de floretes na classe PF5 foi obtida no menor espaçamento entre plantas. As doses NK e os espaçamentos entre plantas não influenciaram as percentagens de floretes nas classes PF79 e PF9.<br>In Itatiba, São Paulo state, Brazil, during the period between March and July of 2007, an experiment was carried out aiming to appraise the effect of doses of nitrogen and potassium (105-105, 157.5-157.5, 210-210, 262.5-262.5 and 315-315 kg ha-1 N and K2O) and spacing between plants (0.2, 0.3, 0.4 and 0.5 m) upon the yield of broccoli and their classification. The experimental design was carried out in a randomized block, with the treatments in a 5 x 4 factorial scheme and three replications. Rows of plants were 0.8 m apart. The following characteristics were evaluated: foliar content of nitrogen (N) and potassium (K), head yield (HY), florets yield (FY), industrial yield (IY) and classification of florets based on length: FY5 (<5 cm); FY57 (>5 and <7 cm); FY79 (>7 and <9 cm) and FY9 (>9 cm). The largest spacing between plants provided the highest N, but HY and FY were reduced. The NK dose and spacing between plants did not influence significantly the level of K and IY. The maximal HY (22.08 t ha-1) and FY (17.09 t ha-1) were obtained with 0.20 m between plants and 150% NK dose (315 kg ha-1 of N and K2O). The higher percentage of florets in FY5 was obtained with smaller spacing between plants and NK dose and spacing did not influence significantly the percentage of florets with lengths greater than 7 cm

    Physiological short-term response to sudden salinity change in the Senegalese sole (Solea senegalensis)

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    The physiological responses of Senegalese sole to a sudden salinity change were investigated. The fish were first acclimated to an initial salinity of 37.5 ppt for 4 h. Then, one group was subjected to increased salinity (55 ppt) while another group was subjected to decreased salinity (5 ppt). The third group (control group) remained at 37.5 ppt. We measured the oxygen consumption rate, osmoregulatory (plasma osmolality, gill and kidney Na+,K+-ATPase activities) and stress (plasma cortisol and metabolites) parameters 0.5 and 3 h after transfer. Oxygen consumption at both salinities was higher than for the control at both sampling times. Gill Na+,K+-ATPase activity was significantly higher for the 55 ppt salinity at 0.5 h. Plasma osmolality decreased in the fish exposed to 5 ppt at the two sampling times but no changes were detected for high salinities. Plasma cortisol levels significantly increased at both salinities, although these values declined in the low-salinity group 3 h after transfer. Plasma glucose at 5 ppt salinity did not vary significantly at 0.5 h but decreased at 3 h, while lactate increased for both treatments at the first sampling time and returned to the control levels at 3 h. Overall, the physiological response of S. senegalensis was immediate and involved a rise in oxygen consumption and plasma cortisol values as well as greater metabolite mobilization at both salinities
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