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1.
Laura Cobelli Marina Collina Agostino Brunelli 《European journal of plant pathology / European Foundation for Plant Pathology》1998,104(5):449-455
Control of lettuce downy mildew (Bremia lactucae) with phenylamide fungicides has failed in some intensive lettuce-producing areas in Northern Italy since Spring 1993. Before then, these chemicals and particularly metalaxyl, provided the best disease control. The sensitivity of Bremia lactucae isolates collected in such areas to metalaxyl was evaluated in the laboratory. These strains grew and sporulated profusely on lettuce seedlings treated with 100 and 200 ppm of metalaxyl, whereas sensitive control strains were completely inhibited when treated with fungicide concentrations ranging from 0.5–1 ppm. Thus in Italy occurrence of resistance to phenylamide fungicides in Bremia lactucae has also been demonstrated, as in almost all the countries where these chemicals were previously authorised. Subsequently, a demonstration of occurrence of resistance was made and the virulence pattern of several strains (resistant and sensitive to metalaxyl) was characterised using differential NL series containing the 13 DM resistant genes or R factors. The results suggest the occurrence of a new pathotype in Italy different from all the 16 NL Bremia lactucae races studied. 相似文献
2.
KR Arrigo DL Worthen MP Lizotte P Dixon G Dieckmann 《Science (New York, N.Y.)》1997,276(5311):394-397
A numerical model shows that in Antarctic sea ice, increased flooding in regions with thick snow cover enhances primary production in the infiltration (surface) layer. Productivity in the freeboard (sea level) layer is also determined by sea ice porosity, which varies with temperature. Spatial and temporal variation in snow thickness and the proportion of first-year ice thus determine regional differences in sea ice primary production. Model results show that of the 40 teragrams of carbon produced annually in the Antarctic ice pack, 75 percent was associated with first-year ice and nearly 50 percent was produced in the Weddell Sea. 相似文献
3.
In two fattening trials, each time 64 male calves of Simmental x Red Holstein cross breeds were used to investigate the influence of different commercial feed additives containing at the same time antimicrobial agents, minerals and vitamins on growth performance, feed intake, feed conversion and health condition. Calves whose milk diets were supplemented had, depending on products used, higher growth rates (9 to 28%) and better feed conversion rates (2 to 12%) compared to control calves which were fed only whole milk. This improved performance is primarily due to higher feed intakes. It is questionable how much the minerals and vitamins in addition to antimicrobial agents contributed to the improvement. The additional mineral supply caused after 8 weeks a statistically significant higher haemoglobin content, serum magnesium and glutathione peroxidase activity in erythrocytes compared to the exclusive whole milk feeding. Calves which were fed no additives refused feed intake more often as a result of disease incidence and required veterinary treatment more frequently. 相似文献
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5.
Giulia Alberoni Davide Cavallini Marina Collina Agostino Brunelli 《European journal of plant pathology / European Foundation for Plant Pathology》2010,126(4):453-457
Up to 2005 the sensitivity of Stemphylium vesicarium (Wallr.) Simm., the causal agent of pear brown spot, to the strobilurin fungicides kresoxim-methyl, trifloxystrobin and pyraclostrobin
was still comparable with baseline values associated with good efficacy in the field. During 2006, the first resistant isolates
were detected in two commercial pear orchards in the Emilia-Romagna region (Italy), one of which was affected by considerable
control failure linked to strobilurin treatments as demonstrated in a field trial. In vitro sensitivity tests with 0.5 mg l−1 of kresoxim-methyl, trifloxystrobin and pyraclostrobin showed that in the population collected in the orchard with control
failure the conidial germination was greater than 90% compared to an untreated control both in 2006 and in 2007, i.e. 1 year
after the suspension of strobilurin applications. In the other orchard, where only a few symptomatic fruits were found and
the strobilurins were still in use, the conidial germination was lower, about 50% in 2006 and 25% in 2007. The molecular analysis
of mitochondrial cytochrome b gene of some monospore isolates with different levels of sensitivity confirmed the presence
of the mutation causing G143A substitution in all the resistant isolates. In conclusion, both in vitro tests and molecular
analysis confirmed the first occurrence of Stemphylium vesicarium resistance to all strobilurin fungicides tested. 相似文献
6.
Ghias Uddin Abdur Rauf Abdulaziz M. Al-Othman Simona Collina Muhammad Arfan Gowhar Ali Inamullah Khan 《Fitoterapia》2012
Pistacia integerrima Stewart in traditionally used as folk remedy for various pathological conditions including diabetes. In order to identify the bioactive compound responsible for its folk use in diabetes, a phytochemical and biological study was conducted. Pistagremic acid (PA) was isolated from the dried galls extract of P. integerrima. Strong α-glucosidase inhibitory potential of PA was predicted using its molecular docking simulations against yeast α-glucosidase as a therapeutic target. Significant experimental α-glucosidase inhibitory activity of PA confirmed the computational predictions. PA showed potent enzyme inhibitory activity both against yeast (IC50: 89.12 ± 0.12 μM) and rat intestinal (IC50: 62.47 ± 0.09 μM) α-glucosidases. Interestingly, acarbose was found to be more than 12 times more potent an inhibitor against mammalian (rat intestinal) enzyme (having IC50 value 62.47 ± 0.09 μM), as compared to the microbial (yeast) enzyme (with IC50 value 780.21 μM). Molecular binding mode was explored via molecular docking simulations, which revealed hydrogen bonding interactions between PA and important amino acid residues (Asp60, Arg69 and Asp 70 (3.11 Å)), surrounding the catalytic site of the α-glucosidase. These interactions could be mainly responsible for their role in potent inhibitory activity of PA. PA has a strong potential to be further investigated as a new lead compound for better management of diabetes. 相似文献
7.
Coastal zone color scanner (CZCS) imagery of the western Ross Sea revealed the Presence of an intense phytoplankton bloom covering >106,000 square kilometers in early December 1978. This bloom developed inside the Ross Sea polynya, within 2 weeks of initial polynya formation in late November. Primary productivity calculated from December imagery (3.9 grams of carbon per square meter per day) was up to four times the values measured during in situ studies in mid-January to February 1979. Inclusion of this early season production yields a spring-to-summer estimate of 141 to 171 grams of carbon per square meter, three to four times the values previously reported for the western Ross Sea. 相似文献
8.
Scharenberg A Heckendorn F Arrigo Y Hertzberg H Gutzwiller A Hess HD Kreuzer M Dohme F 《Journal of animal science》2008,86(8):1879-1890
Tanniferous temperate legumes are assumed to possess anthelmintic properties, but it is unclear whether this is the direct result of condensed tannins (CT) or is mediated indirectly via an improved metabolic protein supply. A metabolism experiment was conducted to differentiate between these factors by feeding the CT plant sainfoin (19.7% CP in DM) to lambs infected with the abomasal blood-sucking nematode Hemonchus contortus. A total of 18 infected lambs were fed sainfoin either untreated or treated with polyethylene glycol, a CT-inactivating agent, or a grass-clover mixture (13.2% CP in DM) over 3 wk (n = 6). Six uninfected lambs received the grass-clover mixture as a control. In addition to indicators of infection (fecal egg count, packed-cell volume, abomasal worm burden, and serum protein), nutrient digestibility, the balance of N and selected minerals, ruminal fluid characteristics, and plasma AA levels were determined mostly in the final experimental week. The specific effects of the sainfoin CT, the extra CP with sainfoin, and the infection were statistically evaluated by contrast analysis. The sainfoin CT exerted no beneficial effects on resilience to nematode infection and exerted only minor effects on ruminal ammonia or blood urea concentrations and the excretory pattern of N. Plasma alanine, aspartate, and proline concentrations tended to be greater (P < or = 0.09) because of the sainfoin CT, whereas the other AA remained unaffected. Intake of the mineral supplement was lower (P < 0.001) for lambs fed sainfoin compared with those fed sainfoin treated with polyethylene glycol. Feeding the high-protein sainfoin instead of the grass-clover mixture increased (P < 0.001) N retention and apparent OM digestibility, whereas digestibility of NDF and ADF were decreased (P < 0.001). Feeding sainfoin also decreased (P < or = 0.04) plasma alanine, glycine, isoleucine, and total nonessential AA compared with the grass-clover mixture. Although fecal egg count, worm burden, and packed cell volume were not affected by the greater CP supply associated with sainfoin feeding, serum albumin level was increased (P = 0.008). The lack of effects of sainfoin on resilience to nematode infection might have been the result of the unexpectedly low CT content (3.6% in DM) of the material used. It cannot be excluded that longer term feeding of this batch of sainfoin might have been effective. 相似文献
9.
KR Arrigo DH Robinson DL Worthen RB Dunbar GR DiTullio M VanWoert MP Lizotte 《Science (New York, N.Y.)》1999,283(5400):365-367
Data from recent oceanographic cruises show that phytoplankton community structure in the Ross Sea is related to mixed layer depth. Diatoms dominate in highly stratified waters, whereas Phaeocystis antarctica assemblages dominate where waters are more deeply mixed. The drawdown of both carbon dioxide (CO2) and nitrate per mole of phosphate and the rate of new production by diatoms are much lower than that measured for P. antarctica. Consequently, the capacity of the biological community to draw down atmospheric CO2 and transport it to the deep ocean could diminish dramatically if predicted increases in upper ocean stratification due to climate warming should occur. 相似文献
10.
The variation in stubble decomposition due to fertilizer incorporation was determined in a typical Argiudoll of the Argentinian
rolling pampas. The experiment was conducted for 15 years, which included a no till system under maize (Zea mays L.) and a soybean rotation (Glycine max) with 0 and 45kg N ha–1 nitrogen fertilization treatments, called NFS and FS, respectively. A higher proportion of residues with a high N content
was found in the FS plots. The different substrate quality proved to be the regulating factor for mineralization. This activity
was indicated by the increase in soil microbial activity and soil carbon light fraction in FS compared to NFS. This carbon
light fraction mineralizes rapidly but does not contribute to the most stable components, which are related to synthesis and
polymerization of humic acids. No significant differences in humic acid content were found.
Received: 24 April 1996 相似文献