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BLA Verçosa CM Lemos IL Mendonça SMMS Silva SM de Carvalho H Goto FAL Costa 《BMC veterinary research》2008,4(1):45
Background
Visceral leishmaniasis in Brazil is caused by the protozoan Leishmania (Leishmania) chagasi and it is transmitted by sandfly of the genus Lutzomyia. Dogs are an important domestic reservoir, and control of the transmission of visceral leishmaniasis (VL) to humans includes the elimination of infected dogs. However, though dogs are considered to be an important element in the transmission cycle of Leishmania, the identification of infected dogs representing an immediate risk for transmission has not been properly evaluated. Since it is not possible to treat infected dogs, they are sacrificed when a diagnosis of VL is established, a measure that is difficult to accomplish in highly endemic areas. In such areas, parameters that allow for easy identification of reservoirs that represents an immediate risk for transmission is of great importance for the control of VL transmission. In this study we aimed to identify clinical parameters, reinforced by pathological parameters that characterize dogs with potential to transmit the parasite to the vector.Results
The major clinical manifestations of visceral leishmaniasis in dogs from an endemic area were onicogriphosis, skin lesions, conjunctivitis, lymphadenopathy, and weight loss. The transmission potential of these dogs was assessed by xenodiagnosis using Lutzomyia longipalpis. Six of nine symptomatic dogs were infective to Lutzomyia longipalpis while none of the five asymptomatic dogs were infective to the sandfly. Leishmania amastigotes were present in the skin of all clinically symptomatic dogs, but absent in asymptomatic dogs. Higher parasite loads were observed in the ear and ungueal region, and lower in abdomen. The inflammatory infiltrate was more intense in the ears and ungueal regions of both symptomatic and asymptomatic dogs. In clinically affected dogs in which few or none Leishmania amastigotes were observed, the inflammatory infiltrate was constituted mainly of lymphocytes and macrophages. When many parasites were present, the infiltrate was also comprised of lymphocytes and macrophages, as well as a larger quantity of polymorphonuclear neutrophils (PMNs).Conclusion
Dogs that represent an immediate risk for transmission of Leishmania in endemic areas present clinical manifestations that include onicogriphosis, skin lesions, conjunctivitis, lymphadenopathy, and weight loss. Lymphadenopathy in particular was a positive clinical hallmark since it was closely related to the positive xenodiagnosis.32.
We recently described site-specific pyrene labeling of RNA to monitor Mg(2+)-dependent equilibrium formation of tertiary structure. Here we extend these studies to follow the folding kinetics of the 160-nucleotide P4-P6 domain of the Tetrahymena group I intron RNA, using stopped-flow fluorescence with approximately 1 ms time resolution. Pyrene-labeled P4-P6 was prepared using a new phosphoramidite that allows high-yield automated synthesis of oligoribonucleotides with pyrene incorporated at a specific 2'-amino-2'-deoxyuridine residue. P4-P6 forms its higher-order tertiary structure rapidly, with k(obs) = 15-31 s(-1) (t(1/2) approximately 20-50 ms) at 35 degrees C and [Mg(2+)] approximately 10 mM in Tris-borate (TB) buffer. The folding rate increases strongly with temperature from 4 to 45 degrees C, demonstrating a large activation enthalpy DeltaH(double dagger) approximately 26 kcal/mol; the activation entropy DeltaS(double dagger) is large and positive. In low ionic strength 10 mM sodium cacodylate buffer at 35 degrees C, a slow (t(1/2) approximately 1 s) folding component is also observed. The folding kinetics are both ionic strength- and temperature-dependent; the slow phase vanishes upon increasing [Na(+)] in the cacodylate buffer, and the kinetics switch completely from fast at 30 degrees C to slow at 40 degrees C. Using synchrotron hydroxyl radical footprinting, we confirm that fluorescence monitors the same kinetic events as hydroxyl radical cleavage, and we show that the previously reported slow P4-P6 folding kinetics apply only to low ionic strength conditions. One model to explain the fast and slow folding kinetics postulates that some tertiary interactions are present even without Mg(2+) in the initial state. The fast kinetic phase reflects folding that is facilitated by these interactions, whereas the slow kinetics are observed when these interactions are disrupted at lower ionic strength and higher temperature. 相似文献
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RENATA SZYMAŃSKA JERZY KRUK MICHAELA SEDLÁŘOVÁ PAVEL POSPÍŠIL 《Plant, cell & environment》2014,37(2):392-401
In the present study, singlet oxygen (1O2) scavenging activity of tocopherol and plastochromanol was examined in tocopherol cyclase‐deficient mutant (vte1) of Arabidopsis thaliana lacking both tocopherol and plastochromanol. It is demonstrated here that suppression of tocopherol and plastochromanol synthesis in chloroplasts isolated from vte1 Arabidopsis plants enhanced 1O2 formation under high light illumination as monitored by electron paramagnetic resonance spin‐trapping spectroscopy. The exposure of vte1 Arabidopsis plants to high light resulted in the formation of secondary lipid peroxidation product malondialdehyde as determined by high‐pressure liquid chromatography. Furthermore, it is shown here that the imaging of ultra‐weak photon emission known to reflect oxidation of lipids was unambiguously higher in vte1 Arabidopsis plants. Our results indicate that tocopherol and plastochromanol act as efficient 1O2 scavengers and protect effectively lipids against photooxidative damage in Arabidopsis plants. 相似文献
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Plant Molecular Biology - 相似文献
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Ali Akbari ZiJian Wang Peisheng He Dongqi Wang Jangho Lee IL Han Guangyu Li April Z. Gu 《Microbial biotechnology》2021,14(1):82-87
We first review current knowledge on PAOs, with a focus on bacteria, in terms of their phylogenetic identities, metabolic pathways and detection methods. We further discuss the evidence that suggests the ubiquitous presence of PAOs in nature and point out the unrevealed roles of the PAOs that warrant future investigation. 相似文献
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Jung-Su Lee Il-Kwon Kim Sang-Hyun Koh Sung Jong Cho Suk-Jun Jang Seung-Hyeon Pyo Won IL Choi 《Journal of Asia》2011,14(1):123-125
Climate change, especially winter temperature increase, may be a factor the recent occurrence and range expansion of Lycorma delicatula (White) in South Korea. Egg mortality increased as minimum winter temperature decreased. Egg mortality was highest (93.32%) in Chuncheon, where the mean minimum winter temperature was lowest. The temperature that induced complete mortality of fulgorid eggs was estimated to be ?3.44 °C on the basis of mean daily temperatures from December 2009 to February 2010 and ?12.72 °C on the basis of mean daily minimum temperatures in January 2010. Mean winter temperatures during the last 30 years have gradually increased to above the temperature for 100% mortality of the fulgorid egg. This suggests that the winter temperature increase may contribute to the successful settlement of the fulgorid in South Korea and its subsequent outbreak and expansion. 相似文献
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