Field data were collected over 2 consecutive years to characterize acute interstitial pneumonia (AIP) in feedyard cattle. Thirty-eight cattle with clinical symptoms of AIP were examined following emergency slaughter; 31 (all heifers) were confirmed to have AIP on the basis of gross and histological lung pathology. The 7 without AIP, plus 17 asymptomatic penmates, were used as contemporary controls. Plasma concentrations of 3-methylindole (3MI) metabolites were higher (P < 0.001) in heifers afflicted with AIP than in the control animals, and concentrations of 3MI mercapturates in the urine were lower (P < 0.007) in affected heifers. Concentrations of 3MI adducts in lung tissue and in microsomal protein did not differ (P > 0.05) between the 2 groups, and 3MI was not detected in ruminal fluid from either group. Total ruminal bacterial numbers and populations of lactobacilli and protozoa were similar (P > 0.05) between the AIP-positive and unafflicted groups, but fewer (P < 0.05) cellulolytic bacteria were present in the positive group. Bovine respiratory syncytial virus antigen was not found in lung tissue from any of the heifers confirmed to have AIP. To our knowledge, this study is the first to implicate 3MI metabolites as having a role in feedyard AIP. Further research is required to determine the factors responsible for the elevation in 3MI adducts in plasma and urine of feedyard cattle afflicted with AIP. 相似文献
The effect of estradiol-17β (E(2)) on the number and distribution of neurons in the caudal mesenteric ganglion (CaMG) supplying the ovary of adult pigs was investigated. Also, the numbers of ovarian dopamine-β-hydroxylase (DβH-), neuropeptide Y (NPY-), somatostatin (SOM-), galanin (GAL-) and estrogen receptor (ER)-immunoreactive perikarya as well as the density of the intraganglionic nerve fibers containing DβH and/or NPY, SOM, GAL were determined. E(2) was administered i.m. from day 4 of the first studied estrous cycle to the expected day 20 of the second studied cycle. Injections of E(2) (1) increased the E(2) level in the peripheral blood approximately 4-5 fold, (2) decreased the number of small-sized Fast Blue-positive postganglionic neurons in the CaMG, (3) decreased the number of small perikarya in the ventral, dorsal and central regions of the CaMG, (4) decreased the number of large perikarya in the dorsal and central regions, (5) decreased the number of small and large perikarya in the CaMG that were DβH(+)/NPY(+), (6) decreased the number of small DβH(+) but NPY(-) perikarya, (7) decreased the number of small perikarya coded DβH(+)/SOM(+) and DβH(+)/SOM(-), (8) decreased the number of small DβH(+)/GAL(-) perikarya, (9) decreased the number of small and large perikarya expressing ER subtypes α and β and (10) decreased the total number of nerve fibers in the CaMG containing DβH and/or NPY and DβH and/or GAL. These results show that long-term E(2) treatment of adult gilts downregulates the populations of both noradrenergic and ERs expressing ovarian neurons in the CaMG. Our findings suggest also that elevated E(2) levels that occur during pathological states may regulate gonadal function(s) by affecting ovary supplying neurons. 相似文献
Reforestation of degraded tropical sites is often hampered by soils of high acidity, high aluminum saturation, and low fertility. To evaluate the possibility of cultivating Acacia species on such soils, a study was conducted at Waiawa, HI, to test growth under conditions of (1) high acidity (primarily aluminum) and nutrient stress, and (2) no acidity stress and high nutrient availability. Twelve Acacia species, including the important native Hawaiian species Acacia koa, were established on a Ustic Kanhaplohumult soil. The experimental design was a split plot with two fertility treatments as the main plots and the 12 Acacia species as subplots. The treatments were: low fertility (F0; 143 kg ha−1 14-14-14 plus micronutrients) and high fertility (F1; 8 Mg ha−1 lime, 143 kg ha−1 14-14-14 plus micronutrients, 200 kg P ha−1, and 77 kg K ha−1). Acacia angustissima, Acacia aulacocarpa, Acacia auriculiformis, Acacia cincinnata, Acacia crassicarpa, Acacia implexa, Acacia koa, and Acacia mangium grew significantly faster under the high fertility treatment. Three species, A. cincinnata, A. crassicarpa, and A. mangium, are recommended for planting on infertile acid soils. The volume of A. koa was increased ten-fold by the high fertility treatment. Additional study on koa's nutritional requirements is suggested in order to identify the nutrients contributing to this increased growth. 相似文献
Presently, there is an intensive search for fungal endophytes to be used in agriculture for the protection and condition improvement of plants and in medicine. We screened for the presence of endophytes in raspberry, which occurs naturally in the Bia?owie?a Forest. The fungal isolates representative of each morphotype were analysed using the molecular markers ITS1 and ITS2. In total, we found 34 taxa of endophytic fungi. The majority were potential pathogens. As many as 27 taxa were found in the leaves of mature plants. No fungi could be isolated from the surface sterilized seeds obtained from these plants. Seedlings were grown from the seeds deposited in the soil seed bank in the Bia?owie?a Geobotanical Station of the University of Warsaw in Bia?owie?a. 8 taxa of endophytic fungi were found in seedlings. It could be due to a possibility of seed infection with these endophytes in soil conditions.
Abstract The digenean Bolbophorus damnificus infects commercial channel catfish Ictalurus punctatus, causing mortality, lower feed consumption, and reduced growth in surviving fish. The purpose of this study was to determine the length of time for which B. damnificus prodiplostomulum metacercariae (juvenile trematode stage that infects fish) would remain viable (parasite appearing to be intact or exhibiting movement) in channel catfish. Fish (n = 210) were infected with molecularly confirmed B. damnificus cercariae harvested from naturally infected marsh rams-horn snails Planorbella trivolvis. During the first sampling (at 20 d postinfection), 8.3 ± 3.6 metacercariae/fish (mean ± SD) were found in the host muscle and visceral organs. The channel catfish were then acclimated to a water temperature of either 18°C or 28°C. After 11 months, 6.8 ± 3.5 and 5.9 ± 3.0 metacercariae/fish were found in groups held at 18°C and 28°C, respectively. The mean number of parasites per fish did not significantly differ between fish held at the two temperatures and did not significantly decline over time at either temperature. Fish examined from 13 to 30 months postinfection all contained viable metacercariae that were morphologically and molecularly identified as B. damnificus. At 18 months, 12 metacercariae (of which 11 were intact and 10 displayed movement) were found in the one fish sampled; at 30 months, the last fish sampled contained three intact metacercariae (one displayed slight movement). Our results indicate that B. damnificus metacercariae can remain viable in channel catfish for at least an 18–30-month production cycle during which they have the potential to affect fish growth; in addition, infected fish may serve as intermediate hosts for these metacercariae for at least 2.5 years postinfection. Received July 14, 2010; accepted March 6, 2011 相似文献
American foulbrood disease has a major impact on honeybees (Apis melifera) worldwide. It is caused by a Gram-positive, spore-forming bacterium, Paenibacillus larvae. The disease can only affect larval honeybees, and the bacterial endospores are the infective unit of the disease. Antibiotics are not sufficient to combat the disease due to increasing resistance among P. larvae strains. Because of the durability and virulence of P. larvae endospores, infections spread rapidly, and beekeepers are often forced to burn beehives and equipment. To date, very little information is available on the use of bacteriophage therapy in rescuing and preventing American foulbrood disease, therefore the goal of this study was to test the efficacy of phage therapy against P. larvae infection. Out of 32 previously isolated P. larvae phages, three designated F, WA, and XIII were tested on artificially reared honeybee larvae infected with P. larvae strain NRRL B-3650 spores. The presence of P. larvae DNA in dead larvae was confirmed by 16S rRNA gene-specific polymerase chain reaction amplification. Survival rates for phage-treated larvae were approximately the same as for larvae never infected with spores (84%), i.e., the phages had no deleterious effect on the larvae. Additionally, prophylactic treatment of larvae with phages before spore infection was more effective than administering phages after infection, although survival in both cases was higher than spores alone (45%). Further testing to determine the optimal combination and concentration of phages, and testing in actual hive conditions are needed. 相似文献
The role of cyclic adenosine monophosphate-mediated phosphorylation of myosin light chain kinase in relaxing smooth muscle was examined. The kinase was immunoprecipitated from tissue extracts and the phosphate content was determined. The addition of forskolin to resting or methacholine-contracted muscles resulted in an increase in myosin light chain kinase phosphorylation of myosin light chain kinase is one of the reactions in the process by which cyclic adenosine monophosphate causes relaxation of smooth muscle. 相似文献
Agriculture in sub-Saharan Africa is a low-input low-output system primarily for subsistence. Some of these areas are becoming less able to feed the people because of land degradation and erosion. The aim of this study is to characterize the potential for increasing levels of soil carbon for improving soil quality and carbon sequestration. A combination of high- and low-resolution imagery was used to develop a land use classification for an area of 64 km2 near Omarobougou, Mali. Field sizes were generally small (10–50 ha), and the primary cultivation systems are conventional tillage and ridge tillage, where tillage is performed by a combination of hand tools and animal-drawn plows. Based on land use classification, climate variables, soil texture, in situ soil carbon concentrations, and crop growth characteristics, the EPIC-Century model was used to project the amounts of soil carbon sequestered for the region. Under the usual management practices in Mali, mean crop yield reported (1985–2000) for maize is 1.53 T ha−1, cotton is 1.2 T ha−1, millet is 0.95 T ha−1, and for sorghum is 0.95 T ha−1. Year-to-year variations can be attributed to primarily rainfall, the amount of plant available water, and the amount of fertilizer applied. Under continuous conventional cultivation, with minimal fertilization and no residue management, the soil top layer was continuously lost due to erosion, losing between 1.1 and 1.7 Mg C ha−1 over 25 years. The model projections suggest that soil erosion is controlled and that soil carbon sequestration is enhanced with a ridge tillage system, because of increased water infiltration. The combination of modeling with the land use classification was used to calculate that about 54 kg C ha−1 year−1 may be sequestered for the study area with ridge tillage, increased application of fertilizers, and residue management. This is about one-third the proposed rate used in large-scale estimates of carbon sequestration potential in West Africa, because of the mixture of land use practices. 相似文献