Mitochondrial DNA evidence for the 19th century introduction of African honey bees into the United States

Since the introduction of an African subspecies into Brazil in the mid-1950's¹, descendent Africanized honey bees (Apis mellifera L.) have spread throughout the Neotropics and into temperate North America. Restriction enzyme analysis of 422 feral honey bee colonies collected from non-Africanized areas in the southern United States revealed that over 21% of them had mitochondrial DNA (mtDNA) derived from a European race established in North America by the 17th century, 77% of them had mtDNA common in honey bees maintained by beekeepers and about 1% exhibited African mtDNA. Further analysis revealed that the African mtDNA was derived from a north African subspecies imported to the US in the 19th century.     

几种野生花卉丛枝菌根发育状况的研究

丛枝菌根是自然界中,植物与真菌形成的分布最广泛的一类互惠共生体。作者对山东省的6种重要野生花卉小黄花菜(Hemerocallis minorMill.)、萱草(Hemerocallis fulvaL.)、琥珀千里光(Senecio ambraceusTurcz.)、矮鸢尾(Iris chamaeiris)、甘野菊(Dendranthema lavandulaefolium)、锦鸡儿(Catagana sinicaRehd.)的AM真菌的侵染状况、典型结构的发育状况以及其根际土壤中AM真菌的孢子密度和根际AM真菌的相对多度和频度进行了研究。结果表明,所调查的6种野生花卉都被AM真菌侵染,且可观察到典型结构泡囊,其根际土壤中AM真菌孢子密度也相当丰富。在本次调查中共分离到了5个属的AM真菌,其中无梗囊霉属和球囊霉属真菌是野生花卉根际AM真菌的优势类群。     

乳酸杆菌通过定植和提供免疫信号调节宿主免疫反应

提取了Lactobacillussp.的肽聚糖,用AffymetrixMOE430A基因芯片研究了肽聚糖对机体免疫细胞基因表达的影响。结果发现,乳酸杆菌肽聚糖可以刺激免疫细胞Th1型免疫反应相关基因的表达,可能激活TLR-NF-κB相关信号通路,同时,不同剂量的肽聚糖可能通过调节Tollip的表达,影响TLR-NF-κB信号通路的激活,从而调节细胞因子的表达。     

火力发电厂灰渣场的植物分布

芜湖发电厂灰渣自然定居的植物共30种,隶属于14科29属.主要包括菊科、禾木科等,多为适应性强的草本植物.风播是其繁殖体的主要来源.灰渣场不良的物理性质、极端贫瘠和重金属浓度过高是限制植物定居的主要因素.     

美国历史上的西部大开发

美国的西部大开发在历史上又称为西进运动 ,它不仅是美国资本主义发展的资本原始积累的过程 ,也是美国经济创业发展的过程 ,极大地促进了美国西部地区的广泛开发和美国经济的快速发展。美国的西部开发经历了密西西比河流域的拓殖、远西部的开发、大草原的开发三个阶段。美国西部的开发过程是美国国内的一次大规模移民拓殖运动 ,也是美国城市化、工业化和美利坚民族大融合的过程 ,这场运动对美国的经济、政治和社会都产生了重大而深远的影响。安定的社会环境、政府的积极扶持、重视科技和交通是美国西部大开发成功的主要原因。     

Genetic and morphometric variation of the Blackcap (Sylvia atricapilla) on the Azores Archipelago reveals a recent range expansion

ABSTRACT

The Blackcap, Sylvia atricapilla, is one of the few passerine species that breeds in all the Macaronesian archipelagos. The sedentary habits of these populations contrast with the migratory populations from the Western Europe. However, little is known for Azorean populations. We assessed the phylogeography of populations from the Azores based on sequences of two mitochondrial genes and one nuclear gene in the Z-chromosome. We also analysed differences in eight morphometric characters from a total of 282 Blackcaps from all the Azores islands. Our results suggest the occurrence of historical and/or current gene flow among birds from all the islands. Blackcaps from the Azores are close relatives of those from Madeira and Portugal, indicating a recent range expansion to the Azores in the last 0.1 million years. The analysis of morphometric data showed a high morphological diversity among and within the islands, probably related to ecological traits.     

三种水份条件下湿生植物Lythrum salicaria L.的菌根状况及其对植物生长的影响

陆生植物的菌根已被广泛研究,对湿生植物菌根的研究却很少.本研究的目的是检测在水淹、潮湿和干旱条件下水生植物L.salicaria的菌根合成状况及其对植物生长的影响.在三种水份条件下,L.salicaria与来源于不同地点(干旱和水淹)的两种接种物(F2和F1)均可形成菌根,水份条件和接种物种类都显著地影响菌根的合成水平(P《0.05).F1和F2接种物与植物合成菌根的水平均在水淹处理中最低. F1接种物与L.salicaria合成菌根的水平在潮湿和干旱处理中显著地高于水淹处理(P《0.05),并且趋势是:潮湿》干旱》水淹处理.F2接种物与L.salicaria合成菌根的水平在三种水份处理中没有显著区别,但仍然可观察到一个趋势:干旱》潮湿》水淹处理.在水淹和干旱处理中,菌根对植物地上部分的生长和根的生物量积累没有影响.在潮湿处理中被F1接种的植株与被F2接种的植株与对照植株相比,地上部分干重、根鲜重显著地低;地上部分鲜/干重比、地上部分/根鲜重比显著地高.水份条件显著地影响植物的生长行为.     

东寨港红树林丛枝菌根真菌侵染和孢子密度及其影响因子研究

丛枝菌根(AM)结构存在于多种红树植物根内,但目前对于红树林中AM真菌的研究还未能完全揭示其存在的原因和状况。研究通过对海南东寨港红树林中不同潮位16种红树植物根内AM侵染情况、AM真菌孢子密度以及土壤理化因子开展调查,以了解东寨港红树林中AM真菌的存在状况及其影响因素。结果表明12种红树植物与AM真菌存在共生关系,其中海漆(Excoecaria agallocha)、许树(Clerodendrum inerme)、水黄皮(Pongamia pinnata)和黄槿(Hibiscus tiliaceus)侵染率较高,均高于55%;16种植物根际土壤中均检测到AM真菌孢子,每25 g土壤的平均孢子密度为(25.7±2.7)个。方差分析表明,不同宿主植物根内AM侵染情况差异显著;潮位对AM侵染率和孢子密度均具有显著影响,表现为高潮位显著高于中、低潮位,而中低潮位间无显著差异。线性回归分析表明土壤含水率、电导率和有效磷含量可能是影响东寨港红树林生境中AM侵染率和孢子密度的主要土壤因子。     

Geographic populations of the medfly may be differentiated by mitochondrial DNA variation

Restriction enzyme cleavage sites of mitochondrial DNA (mtDNA) from the Mediterranean fruit fly were found to vary among introduced populations in the Neotropics. The survey included samples from 15 established natural populations and 5 laboratory cultures from Hawaii, Central America, South America and West Africa and samples from recent California infestations (1989, 1991). Based on restriction fragment length polymorphisms from 2 enzymes, Hawaii is an unlikely source for the 1989 and 1991 California infestations. Interpopulational variation in mtDNA demonstrates the potential for the technique to trace the process of colonization (geographic spread) by this insect.