How viruses enter animal cells   总被引：2，自引：0，他引：2  

Smith AE  Helenius A 《Science (New York, N.Y.)》2004,304(5668):237-242

Viruses replicate within living cells and use the cellular machinery for the synthesis of their genome and other components. To gain access, they have evolved a variety of elegant mechanisms to deliver their genes and accessory proteins into the host cell. Many animal viruses take advantage of endocytic pathways and rely on the cell to guide them through a complex entry and uncoating program. In the dialogue between the cell and the intruder, the cell provides critical cues that allow the virus to undergo molecular transformations that lead to successful internalization, intra-cellular transport, and uncoating.  相似文献   

Phylogeny-aware gap placement prevents errors in sequence alignment and evolutionary analysis     

Löytynoja A  Goldman N 《Science (New York, N.Y.)》2008,320(5883):1632-1635

Genetic sequence alignment is the basis of many evolutionary and comparative studies, and errors in alignments lead to errors in the interpretation of evolutionary information in genomes. Traditional multiple sequence alignment methods disregard the phylogenetic implications of gap patterns that they create and infer systematically biased alignments with excess deletions and substitutions, too few insertions, and implausible insertion-deletion-event histories. We present a method that prevents these systematic errors by recognizing insertions and deletions as distinct evolutionary events. We show theoretically and practically that this improves the quality of sequence alignments and downstream analyses over a wide range of realistic alignment problems. These results suggest that insertions and sequence turnover are more common than is currently thought and challenge the conventional picture of sequence evolution and mechanisms of functional and structural changes.  相似文献   

Response of somatic embryos of Scots pine to fungal cell wall elicitors     

J. Lu  T. Aronen  A. Pappinen  F. O. Asiegbu 《Forest Pathology》2011,41(1):75-82

  相似文献   

Lignin degradation by Agaricus bisporus accounts for a 30% increase in bioavailable holocellulose during cultivation on compost     

ten Have R  Wijngaard H  Ariës-Kronenburg NA  Straatsma G  Schaap PJ 《Journal of agricultural and food chemistry》2003,51(8):2242-2245

The common mushroom Agaricus bisporus is a non-white rot saphrophytic fungus that can degrade lignin to free and utilize holocellulose embedded in fermented straw as present in compost. A new method is described to estimate the actual amount of bioavailable holocellulose in 3.8 kg compost cultures spawned with A. bisporus Horst U1 prior to and during a cultivation with two cycles of mushroom harvesting. The method shows that the initial amount of bioavailable holocellulose per culture, accounting for 130 +/- 22 g, is lower than the total holocellulose consumption by A. bisporus accounting for 182 +/- 15 g. This difference is explained by a 30% increase in bioavailable holocellulose. The increase is caused by the degradation of 95 +/- 3 g of holocellulose-shielding lignin. The results are discussed within the scope of the A. bisporus mushroom yield and lignin degradation by white rot fungi during growth on lignocellulose-containing materials.  相似文献   

Needle Structures and Epiphytic Microflora of Scots Pine (Pinus Sylvestris L.) under Heavy Ammonia Deposition from Fur Farming     

Bäck  Jaana  Turunen  Minna  Ferm  Ari  Huttunen  Satu 《Water, air, and soil pollution》1997,100(1-2):119-132

Scots pine (Pinus sylvestris) needles from forest sites differing in distance from big fur farms emitting large amounts of ammonia and ammonium (=NH_y) were examined by scanning and transmission electron microscopy. Specific features indicating an ammonium-nitrogen overload, such as an abundance of needle surface organisms and modifications in cellular and wax structures, were classified. Throughout the study area (up to 1000 m from the farms), mesophyll cells had thin cytoplasm and folding plasmalemma indicating frost damage. Phloem damage attributable to a possible nutrient imbalance was also observed. Chloroplast membranes were undulating and the occurrence of leaf surface organisms (e.g. aerophilic algae) was more abundant at the closest sites. The changes were related both to the direct effects of dry NH_y deposition on the needles, and to the effects operating via soil acidification. The needle epicuticular waxes proved to be structurally rather inert against the influence of ammonium compounds, since no significant changes due to NH_y were observed.  相似文献   

Genetic relationships and hybrid vigour in olive (Olea europaea L.) by microsatellites     

Iris Biton  Sofia Shevtsov  Oren Ostersetzer  Yair Mani  Shimon Lavee  Benjamin Avidan  Giora Ben‐Ari 《Plant Breeding》2012,131(6):767-774

The olive (Olea europaea) is one of the most important oleaginous crops of the Mediterranean basin. Increased demand for olive oil creates a need for new olive varieties to help meet the requirements of the global market. However, olive breeding has been handicapped by such varied challenges as a prolonged juvenile period, agrotechnical problems and insufficient genetic knowledge. The use of DNA markers has the potential to overcome these problems and increase the effectiveness of classical breeding programmes. In this study, co‐dominant polymorphic simple sequence repeats (SSRs) were used as markers to analyse the genetic relationships between several local and other ‘non‐native’ olive cultivars. Cluster analysis revealed four major groups among the 15 cultivars examined in this study. Table and oil cultivars were clustered in different groups. However, the clusters did not differentiate between cultivars of different geographical origins. In addition, we used the data gathered to analyse genetic relationships to evaluate the effects of heterosis in agricultural traits. Genetic distances between cultivars were determined based on the SSR genotype data and were used for evaluating the possible effects of heterosis in various F₁ populations. Interestingly, phenotypic data of F₁ progenies from crosses between different cultivars indicated the potential effects of heterosis as expressed in several traits. Genetic distance between parents was significantly correlated to F₁ performance for three traits: percentage of dry fruit weight, oil content and commercial oil production. Thus, crosses between olive cultivars exhibiting relatively extensive genetic distances one from the other are expected to result in better progeny performance in future Olea breeding programmes. Our study linked assessment of biodiversity of commercial olive cultivars with the application of this information in olive breeding programmes for selection of specific parents to generate superior new cultivars.  相似文献   

Role of tenure insecurity in deforestation in Ghana's high forest zone     

Lawrence Damnyag  Olli SaastamoinenMark Appiah  Ari Pappinen 《Forest Policy and Economics》2012,14(1):90-98

  相似文献   

Characterization of Capsaicinoids and Antioxidants in Hot Peppers as Influenced by Hybrid and Harvesting Stage     

Qumer Iqbal  Muhammad Amjad  Muhammad Rafique Asi  Agustin Ariño 《Plant foods for human nutrition (Dordrecht, Netherlands)》2013,68(4):358-363

Studies were conducted to investigate the accumulation pattern of capsaicinoids and antioxidants such as carotenoids, ascorbic acid and phenolic compounds in three hot pepper hybrids at five different harvesting stages: immature green, mature green, color break, red ripe and dried fruit. Capsaicin and dihydrocapsaicin contents were maximum at mature green stage in both Sky Red (61.30 and 43.76 mg/100 g) and Wonder King (43.93 and 26.16 mg/100 g) hybrids, whereas Maha hybrid reached top values at color break stage (39.13 and 24.20 mg/100 g). The accumulation of total carotenoids showed an 8-fold increase from red ripe (12 mg/100 g) to dried fruit stage (96 mg/100 g), while a noticeable decline by 76 % was observed for ascorbic acid at same harvesting stages (150 vs. 36 mg/100 g, respectively). The three hot pepper hybrids showed great variations in the evolution of total phenolic contents during harvesting stages. Overall, the mature green stage was ideal to acquire maximum pungency due to capsaicinoids, while peppers at red ripe stage were best sources of ascorbic acid and dried fruits contained higher levels of total carotenoids.  相似文献   

Clinical features of canine pulmonary veno‐occlusive disease and pulmonary capillary hemangiomatosis     

Carol R. Reinero  L. Ari Jutkowitz  Nathan Nelson  Isabelle Masseau  Samuel Jennings  Kurt Williams 《Journal of veterinary internal medicine / American College of Veterinary Internal Medicine》2019,33(1):114-123

  相似文献   

沙地樟子松天然林自然落种和土壤种子库的特征   总被引：3，自引：1，他引：2  

闫德仁  杜敏  王玉华  张宝珠  敖文明  乔殿学  阿日根扎 《东北林业大学学报》2009,37(11)

研究了呼伦贝尔沙地3种类型的樟子松天然林内天然母树的自然落种和土壤种子库特征.结果表明:土壤种子库中种子数量的空间分布特征和母树自然落种数量的空间分布规律相同.从树干或林缘向外,随着传播距离的增加,土壤种子库的种子数量和母树自然落种的种子数量均有降低的趋势.从树干或林缘向外4～5m范围内樟子松母树自然落种数量最多,而后随着距离的增加,自然落种数量明显减少.樟子松天然林母树自然落种的传播距离范围可以达到25m,表明在适宜条件下,沙地樟子松天然林通过自然更新,能够迅速扩展林缘,扩大种群.  相似文献