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Pinus plantations have increased in Brazil, and native forest areas have been converted for timber production. The clearing and the long-term loblolly pine (Pinus taeda L.) land-use effects on soil carbon and nitrogen stocks were evaluated in a natural broadleaved forest and in loblolly pine sites cultivated for 29, 35, 38 and 49 years, as well the soil contribution as ecosystem carbon pool. According to the exponential-decay model fitted to changes in carbon stock, the initial soil carbon stock of 200 Mg ha?1 to a depth of 100 cm in the natural forest decreased by 36% over 49 years of pine cultivation (around 72.4 Mg ha?1 of C). Around two-thirds of this decrease occurred in the top 30 cm of the soil and intensively in the first 12 years of cultivation, but slowly faded as carbon stock tended to reach a new steady state after approximately 49 years of cultivation. The soil nitrogen stock in the natural forest was 14.2 Mg ha?1 to a depth of 100 cm and decreased by 36% over the 49 years. This decrease was linear according to the fitted model, especially in the top 30 cm where nitrogen decline was 83% and was proportionally more intense than the carbon decline. Despite the soil carbon decrease, soil remained the largest carbon reservoir in the ecosystem for the growing rotation time of loblolly pine in this region.

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The one-compartment C model Ct=C0ek2t+k1A/k2(1−ek2t) is being long used to simulate soil organic C (SOC) stocks. Ct is the SOC stock at the time t; C0, the initial SOC stock; k2, the annual rate of SOC loss (mainly mineralization and erosion); k1, the annual rate to which the added C is incorporated into SOC; and A, the annual C addition. The component C0ek2t expresses the decay of C0 and, for a time t, corresponds to the remains of C0 (C0 remains). The component k1A/k2(1−ek2t) refers, at time t, to the stock of SOC derived from C crops (Ccrop). We herein propose a simple method to estimate k1 and k2 coefficients for tillage systems conducted in long-term experiments under several cropping systems with a wide range of annual C additions (A) and SOC stocks. We estimated k1 and k2 for conventional tillage (CT) and no-till (NT), which has been conducted under three cropping systems (oat/maize −O/M, vetch/maize −V/M and oat + vetch/maize + cowpea −OV/MC) and two N-urea rates (0 kg N ha−1 −0 N and 180 kg N ha−1 −180 N) in a long-term experiment established in a subtropical Acrisol with C0 = 32.55 Mg C ha−1 in the 0–17.5 cm layer. A linear equation (Ct = a + bA) between the SOC stocks measured at the 13th year (0–17.5 cm) and the mean annual C additions was fitted for CT and NT. This equation is equivalent to the equation of the model Ct=C0ek2t+k1A/k2(1−ek2t), so that a=C0ek2t and bA=k1A/k2(1−ek2t). Such equivalences thus allow the calculation of k1 and k2. NT soil had a lower rate of C loss (k2 = 0.019 year−1) than CT soil (k2 = 0.040 year−1), while k1 was not affected by tillage (0.148 year−1 under CT and 0.146 year−1 under NT). Despite that only three treatments had lack of fit (LOFIT) value lower than the critical 5% F value, all treatments showed root mean square error (RMSE) lower than RMSE 95% indicating that simulated values fall within 95% confidence interval of the measurements. The estimated SOC stocks at steady state (Ce) in the 0–17.5 cm layer ranged from 15.65 Mg ha−1 in CT O/M 0 N to 60.17 Mg ha−1 in NT OV/MC 180 N. The SOC half-life (t1/2 = ln 2/k2) was 36 years in NT and 17 years in CT, reflecting the slower C turnover in NT. The effects of NT on the SOC stocks relates to the maintenance of the initial C stocks (higher C0 remais), while increments in Ccrop are imparted mainly by crop additions.  相似文献   
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Camu-camu [Myrciaria dubia (HBK) McVaugh] is a small fruit native to the Amazonian rain forest. Its anthocyanin profile has now been investigated for the first time. Fruits from two different regions of the S?o Paulo state, Brazil, were analyzed. The major anthocyanins were isolated by high-speed countercurrent chromatography. HPLC-PDA, HPLC-MS/MS, and 1H NMR were used to confirm the identity of the main anthocyanins of camu-camu. Cyanidin-3-glucoside was identified as the major pigment in the fruits from both regions, representing 89.5% in the fruits produced in Iguape and 88.0% in those from Mirandópolis, followed by the delphinidin-3-glucoside, ranging between 4.2 and 5.1%, respectively. Higher total anthocyanin contents were detected in the fruits from Iguape (54.0 +/- 25.9 mg/100 g) compared to those from Mirandópolis (30.3 +/- 6.8 mg/100 g), most likely because of the lower temperatures in the Iguape region.  相似文献   
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The vectorial competence of the tick Rhipicephalus sanguineus is discussed in relation to the epidemiology of canine visceral leishmaniasis, taking into account its strict association with dogs and the low indices of natural infection presented by its known vector, the phlebotomine sand fly Lutzomyia longipalpis. In order to evaluate natural infection by Leishmania chagasi and the infectivity of these parasites in the tick, 39 specimens (6 females, 11 males and 22 nymphs) of R. sanguineus were removed from 21 dogs showing diverse symptoms of zoonotic visceral leishmaniasis (ZVL). Six ticks (15.4%) gave positive results for the genus Leishmania using the PCR technique. To determine the infectivity of the parasites, 36 hamsters were inoculated orally and peritoneally with macerates of ticks removed from nine dogs symptomatic for visceral leishmaniasis. After 6 months the hamsters were sacrificed and necropsied. Serum was removed for IFAT, as well as spleen and liver fragments to make imprint smears and for PCR. Eight (88.9%) of these dogs presented ticks that were infective for 14 hamsters (41.2%), 12 (85.7%) of them infected peritoneally and two (14.3%) orally. PCR revealed 27 smears (40.9%) to be positive, 20 (62.5%) of them infected peritoneally and seven (20.6%) orally. IFAT showed 14 positive animals (41.2%). Based on these findings, we suggest that the vectorial capacity of R. sanguineus for L. chagasi should be evaluated further, opening new perspectives in the epidemiology of ZVL.  相似文献   
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Serum protein values were determined in 26 healthy dogs using agarose gel electrophoresis (SPE), splitting the electrophoretic separation into six regions: albumin, alpha(1), alpha(2), beta(1), beta(2)and gamma globulins. High-resolution electrophoresis (HRE) was used to separate single proteins. Serum proteins from dogs (26 healthy and 20 affected by various diseases) were then characterized by electrophoretic immunofixation (IFE) and Sudan black staining on HRE film. Haemoglobin and normal canine plasma and serum were used to identify haptoglobin and fibrinogen, respectively.In the standard pattern, determined by HRE, the following proteins were identified: albumin, alpha(1)-lipoprotein (alpha(1)-region), haptoglobin and alpha(2)-macroglobulin (alpha(2)-region), beta -lipoprotein and C3 (beta(1)-region), transferrin and IgM (beta(2)-region), IgG (mostly in gamma -region and partly in beta(2)-region). The HRE pattern shown by healthy dogs could be compared with those of dogs affected by various diseases to obtain clinical information.  相似文献   
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The unexpected demise of a 12-year-old male neutered English bulldog solicited a gross examination, which revealed a blood-filled space occurring in the proximal left subclavian artery (LSA). It originated about 1 cm from the branching point of the vessel and progressively dilated for 3 cm distal to this origin. Histopathological investigation showed that the tunica media of the LSA was more than 50% split, with the blood-filled space dissecting through the arterial wall. In the tunica media of the LSA, severe multifocal fragmentation and/or loss of the elastic fibers was observed. The retained disorganized elastic fibers were separated and disoriented due to accumulations of acid mucopolysaccharide. Marked, diffuse medial, and adventitial fibrous tissue deposition was also identified. The cause of death was attributed to acute hemorrhagic and necrotizing pancreatitis with pulmonary edema, suggesting that LSA dissection was an incidental finding. Subclavian artery dissection is extremely rare in humans, where the involvement of the LSA in cases of aortic dissection both with or without Marfan syndrome has been reported. Aortic and pulmonary artery dissection in bovines and aortic aneurysm and dissection in dogs have been reported to be associated with Marfan and Marfan-like syndromes, respectively. Histopathological findings suggestive of underlying connective tissue abnormalities resembling Marfan-like syndrome (i.e., the appearance of the elastic tissue and the degenerative changes of the tunica media) were detected in the first case of LSA dissection in dogs and veterinary medicine, herein described.  相似文献   
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