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《新西兰生态学杂志》2011,26(1):81-85
Hybridisation is a rare event in facultatively apomictic species. We report the recovery of two hybrids from reciprocal crosses between the facultatively apomictic species Hieracium praealtum and H. caespitosum. Both parents were tetraploid (2n=4x=36). H. caespitosum x H. praealtum (CR6) was a hexaploid (2n=6x=54) and an apomict. The increased ploidy number is evidence of a BIII hybrid origin, having arisen from the fusion of a reduced and an unreduced gamete. In contrast, the hybrid recovered from the reciprocal cross H. praealtum x H. caespitosum (RC4) was a tetraploid and therefore probably arose as a BII hybrid fi-em the fusion of two reduced gametes. Further evidence for this is the expression of sexuality in this plant. As apomixis in Hieracium is thought to be determined by a single dominant locus, a sexual plant is consistent with a model of inheritance where this represents the putative homozygous recessive phenotype. The formation of a sexual plant from the hybridisation of apomicts has potentially significant evolutionary implications. The formation of an interspecific BIII hybrid has not previously been recorded. 相似文献
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Amoebae potentially able to cause severe eye infections were isolated from 31 of 56 eyewash stations. Eyewash stations that contained a reservoir presented a greater hazard than those without a reservoir. The need to flush eyewash stations regularly as part of safe laboratory practices is emphasized. 相似文献
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We investigated the role of cleaning stations in determining the distribution of territorial reef species. Cleaner fish reduce their clients' ectoparasite loads and, therefore, proximity to cleaning stations should be advantageous for territorial fish. We focused on five damselfish species which hold permanent territories and cleaning stations occupied by cleaning gobies (Elacatinus spp.) on a Caribbean reef. Contrary to our predictions of higher densities near cleaning stations, we found that bicolor damselfish were less abundant near cleaning stations than at ecologically similar points without cleaning gobies whereas no effects were seen for longfin, dusky, yellowtail, and threespot damselfish. In addition, although damselfish densities were higher in the immediate vicinity of cleaning stations than 1.5-3 m away for most species, this was also the case at points without cleaners. Because cleaning stations are usually located on prominent coral heads or sponges, the overall significant attraction of damselfish to such structures, whether occupied by cleaning gobies or not, could reflect attraction to past or potential cleaning stations. However, it is more likely that interspecific competition and/or the low benefits of being cleaned at our study site prevent aggregation around cleaners. Cleaning stations may play only a minor role in determining the distribution of territorial reef fishes. 相似文献
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黄海北部不同站位海洋细菌群落分布特征 总被引:14,自引:1,他引:13
[目的]为揭示北黄海不同海域中真细菌群落分布的差异,[方法]采用16s rRNA基因文库和变性梯度凝胶电泳(DGGE)技术,对远海和近海两个站位的沉积物和水体中细菌群落特征进行了解析和评价.[结果]文库分析揭示海水及沉积物中微生物种类丰富,存在大量未被认知的类群.各站位中主要为变形菌门(Proteobacteria),沉积物中γ-Proteobacteria和δ-Proteobacteria亚门占优势,水中则以α-Proteobacteria亚门占优势,但各亚门微生物在两个站位中存在明显系统发育学分歧.DGGE图谱聚类分析显示,近海沉积物和海水中细菌群落优势类群相似性很高,而远海沉积物和海水中则相似性很低.[结论]研究结果表明,微生物种类在不同地理位置和生存介质中存在明显差异,环境因素对微生物的分布起主导作用. 相似文献
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Jordina Belmonte Mercè Vendrell Joan M. Roure Josep Vidal Jaume Botey Àlvar Cadahía 《Aerobiologia》2000,16(1):93-99
Ambrosia pollen is known as an importantallergen in North America, and more recently in someEuropean countries. From 1989 to 1995, the Ambrosia pollen levels detected at the stationsmonitored by the Aerobiological Network of Catalonia(Xarxa Aerobiològica de Catalunya, XAC) wereinsignificant. In 1996, a considerable althoughtemporary increase in the concentration of this pollenwas detected in the atmosphere over Girona, Barcelona,Bellaterra, Manresa, and Tarragona. Most of the Ambrosia pollen collected in 1996 was concentrated ina single day. Its appearance on that day wasattributed to long range transportation, caused byunusual conditions of atmospheric circulation, fromthe Lyon region in France where the species isabundant. This is the only day where concentrations ofAmbrosia pollen that may be dangerous to humanhealth have been reached.
Ambrosia coronopifolia is the most abundantspecies of the genus in Catalonia, and although rare,its expansion is favoured by the fact that it growsthrough rhizomes and sprouts easily. It is, therefore,important to monitor the growth of its population andthe release of its pollen in order to predict theappearance of pollen levels that may precipitateallergic symptoms. 相似文献
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Siwert Nilsson 《Aerobiologia》1988,4(1-2):4-7
Summary The IAA Working Group of the European Aeroallergen Network has been gradually set up as result of the great interest shown
on the occasion of the 3rd International Conference on Aerobiology (Basel 1986). Presently 21 countries join the EAN. The
IAA Working Group, with the aim of stimulating the exchange of aeroallergen information between the various countries in Europe
has planned the issue of a booklet containing information on distribution of sampling sites in Europe, collecting and analysing
methods, type and availability of allergy service. The sphere of activitie carried out by the IAA Working Group may serve
as a model for other parts of the world whenever a network of monitoring stations is being organized and coordinated. 相似文献
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The toxicity and genotoxicity of wastewater from eight gasoline stations in Brasília, Brazil's capital city, was studied by assessing chromosomal aberrations, chromosomal malsegregation and the mitotic index in Alliumcepa root cells, and the occurrence of micronucleus and nuclear abnormalities in peripheral erythrocytes of tilapia fish (Oreochromis niloticus). The content of gasoline station effluents was also analyzed based on several physico-chemical parameters. None of the wastewater samples was genotoxic to A. cepa root cells, although cell proliferation was significantly inhibited, especially at the highest concentrations. Likewise, no micronuclei were observed in O. niloticus peripheral erythrocytes, even after exposure to high concentrations, but there was an increase in the number of nuclear abnormalities and fish mortality. These results show that although the effluent from gasoline stations is processed by an oil/water separation system before being discharged into the main sewage system, the wastewater still contains toxic compounds. 相似文献
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Alekhova TA Aleksandrova AA Novozhilova TIu Lysak LV Zagustina NA Bezborodov AM 《Prikladnaia biokhimiia i mikrobiologiia》2005,41(4):435-443
Samples of microorganisms from the surface of constructions of Mir Space Station (Mir SS) were taken and examined after 13 years of operation. The following microorganisms were isolated and identified: 12 fungal species belonging to the genera Penicillium, Aspergillus, Cladosporium, and Aureobasidium; 3 yeast species belonging to the genera Debaryomyces, Candida, and Rhodotorula; and 4 bacterial species belonging to the genera Bacillus, Myxococcus, and Rhodococcus. The predominant species in all samples was Penicillium chrisogenum. It was shown that the fungi isolated could damage polymers and induce corrosion of aluminum-magnesium alloys. We commenced a study of microbial degraders on constructions of the Russian section of the International Space Station (RS ISS). Twenty-six species of fungi, bacteria, yeasts, and actinomycetes, known as active biodegraders, were identified in three sample sets taken at intervals. We founded a collection of microorganisms surviving throughout space flights. This collection can be used to test spacecraft production materials, in order to determine their resistance to biodegradation. 相似文献
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Iu G Grigor'ev 《Radiobiologiia》1987,27(2):147-154
The paper discusses measures to be taken during hypothetic utmost breakdown at nuclear power stations when the amount of radioactive nuclides injected in the atmosphere exceeds the permissible level. Three consecutive steps of the breakdown are distinguished and, correspondingly, medical and hygienic measures are developed to provide radioprotection of the personnel, population, and workers involved in the elimination of the consequences of the breakdown. Criteria are given for developing protective measures and implementing thereof. 相似文献
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R. H. Hadderingh 《Aquatic Ecology》1979,13(2-3):83-93
Summary Fish larvae and juveniles are not strong enough to maintain in the water flow occurring at cooling water intakes of power stations. Therefore, they are drawn into the cooling water system and show considerable mortality mainly due to mechanical causes. In this paper several measures are discussed which may lead to a reduction of this problem. Special emphasis is laid on site selection in low productive areas, reduction of the volume of cooling water, careful removal and transport from the screens and preventing fish from entering the intake. Illumination of the intake area during night appears to be an effective means in decreasing the large nocturnal fish inflow. It is suggested to modify the current cooling water standards in order to diminish the intake fish mortality. 相似文献
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The recent increase in the number of aerobiological stations means that it is possible to make comparative studies, not only to ascertain similarities and differences between pollen counts in different places, but also to ascertain the most suitable places for them to be situated and the most adequate distance which should be established between them. To this end, we present a statistical comparison of the results obtained for the pollen of the ten most abundant taxa, as recorded in the sampling stations of Malaga and Estepona (South of Spain) during 1995-97. The stations are 90km apart. The variables compared were the following: mean daily concentrations (for each year and the total period studied), the mean concentration of the three years for the same date (trend) and the deviation from this mean (for each year and taken as a whole). The interannual differences within and between stations were taken into account as regards the association, concentration and distribution of the variables. The results of the tests applied point that significant differences between the two stations were observed for most of the pollen types studied. Despite of this, a positive and significant correlation exists between the mean daily concentrations of the different taxa at the two stations, which is an important finding if we consider the possibility of making reliable predictions for one sampling site based on the data obtained at the other. 相似文献
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Jaime C. Piñero Ronald F. L. Mau Grant T. McQuate & Roger I. Vargas 《Entomologia Experimentalis et Applicata》2009,133(2):208-216
A novel, visually-attractive bait station was developed in Hawaii for application of insecticidal baits against oriental fruit fly, Bactrocera dorsalis (Hendel), melon fly, Bactrocera cucurbitae (Coquillett), and Mediterranean fruit fly, Ceratitis capitata (Wiedemann) (all Diptera: Tephritidae). The bait station developed represents a supernormal visual stimulus of papaya foliage and takes advantage of the flies' strong response to the high light-reflecting properties of yellow color and of their need for shelter, while fully protecting the bait against rainfall. Field studies revealed that the behavioral response of female fruit flies, in particular C. capitata and B. cucurbitae , to yellow-painted bait stations sprayed with GF-120 NF Naturalyte Fruit Fly Bait was significantly enhanced compared with similarly sprayed bait stations that mimicked the green color of fully grown papaya leaves. Field studies conducted with B. cucurbitae indicated that the period of bait attractiveness can be extended for at least 1 week after bait application due to the rain-fastness properties of the bait stations and the use of a visually-attractive color. Our studies provide the behavioral basis for the development of improved attract-and-kill bait stations for fruit flies in Hawaii. These devices also provide a standardized way of evaluating bait spray formulations, thus allowing for proper comparisons over time, across species, and among geographical areas. 相似文献