共查询到20条相似文献,搜索用时 31 毫秒
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H. Altenmüller 《Die Naturwissenschaften》1988,75(5):272-272
Naturwissenschaften Aktuell
Bundesforschungsbericht: Wechselwirkungen 相似文献3.
Photocatalysis: Preface 总被引:1,自引:0,他引:1
Po Keung Wong 《环境科学学报(英文版)》2017,29(10):1-2
<正>A recent search of the keyword"Photocatalysis"in the CAS Sci Finder?database shows that at least 5,000 articles on this topic have been published each year from 2014 to2016.It is expected that even more articles on this topic will be published in the foreseeable future.These data indicate the importance of"Photocatalysis"in the field.The first 相似文献
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Hofit Kol-Maimon Zvi Mendel José Carlos Franco Murad Ghanim 《Die Naturwissenschaften》2014,101(10):791-802
Mealybugs have a haplodiploid reproduction system, with paternal genome elimination (PGE); the males are diploid soon after fertilization, but during embryogenesis, the male paternal set of chromosomes becomes heterochromatic (HC) and therefore inactive. Previous studies have suggested that paternal genes can be passed on from mealybug males to their sons, but not necessarily by any son, to the next generation. We employed crosses between two mealybug species—Planococcus ficus (Signoret) and Planococcus citri (Risso)—and between two populations of P. ficus, which differ in their mode of pheromone attraction, in order to demonstrate paternal inheritance from males to F2 through F1 male hybrids. Two traits were monitored through three generations: mode of male pheromone attraction (pherotype) and sequences of the internal transcribed spacer 2 (ITS2) gene segment (genotype). Our results demonstrate that paternal inheritance in mealybugs can occur from males to their F2 offspring, through F1 males (paternal line). F2 backcrossed hybrid males expressed paternal pherotypes and ITS2 genotypes although their mother originated through a maternal population. Further results revealed other, hitherto unknown, aspects of inheritance in mealybugs, such as that hybridization between the two species caused absence of paternal traits in F2 hybrid females produced by F1 hybrid females. Furthermore, hybridization between the two species raised the question of whether unattracted males have any role in the interactions between P. ficus and P. citri. 相似文献
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韩海东 《Ambio-人类环境杂志》2004,(Z1):35-38
山地不仅为全球60多亿人口提供了必需的生境和包括水资源在内的各种资源,而且可以使我们深入地了解全球人类的生境是如何发展的、全球气候发生变化时它又是如何响应的、以及气候突变是如何引起全球生物退化和经济衰退等这样的环境问题.在全世界60多亿人口中,至少有6亿人生活在山区.山区同时又是世界上哺育其他数十亿人口的主要河流的发源地.在河谷流域中,至少有一半人的生活用水部分或者全部依赖于山区的冰雪融水.由于人类活动致使大气组成成分发生变化,引起全球气候不断变暖,从而导致冰川的不断退缩.许多冰川已经或正在消失,这将严重威胁全球城市用水需求.全球温度升高在高纬地区表现得最为明显,从而使得像格陵兰和南极大陆的一些大冰盖变得非常脆弱.北半球冰川的剧烈消融又产生了许多其他的问题:如挪威海湾流的减弱,斯堪的纳维亚半岛和北欧气候的大规模变化等.在生物海洋中,山地是一些生物岛,特有的物种生态型很多.全球气候变暖,使环境的变化已超出了这些山地物种特有生态型的适应范围,致使这些物种特有生态型不能适应环境的改变而对所有类型的病害都很脆弱.这一过程是系统性的衰退,在越来越多暴露于极端气候条件下的山坡上表现得非常明显.现在我们注意到,随着气候变化的累积,植物的死亡率与发病率也不断增加.山区尤其清楚地反映出全球气候突变的严重性.尽管目前的美国政府对一些建设性的建议和措施持强硬立场,但我们还是能够而且必须对此做出应对. 相似文献
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《Die Naturwissenschaften》1989,76(5):234
Naturwissenschaften Aktuell
Jetzt offiziell: Volkswagen-Stiftung 相似文献16.
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Samira Veiga Ravaiano Ríudo de Paiva Ferreira Lucio Antonio de Oliveira Campos Gustavo Ferreira Martins 《Die Naturwissenschaften》2014,101(8):603-611
The sensilla of insects are integumental units that play a role as sensory structures and are crucial for the perception of stimuli and for communication. In this study, we compared the antennal sensilla of females (workers and queens), males (haploid (n) and diploid (2n)), and queen-like males (QLMs, resulting from 2n males after juvenile hormone (JH) treatment) in the stingless bee Melipona quadrifasciata. Images of the dorsal antenna surfaces were acquired using a scanning electron microscope. As reported for other hymenopterans, this species exhibits a heterogeneous sensillar distribution along the antennae. Thirteen different types of sensilla were found in the antennae of M. quadrifasciata: trichodea (subtypes I to VI), chaetica (subtypes I and II), placodea, basiconica, ampullacea, coeloconica, and coelocapitula. Sensilla trichodea I were the most abundant, followed by sensilla placodea, which might function in olfactory perception. Sensilla basiconica, sensilla chaetica I, sensilla coeloconica, and sensilla ampullacea were found exclusively in females. In terms of the composition and size of the sensilla, the antennae of QLMs most closely resemble those of the 2n male, although QLMs exhibit a queen phenotype. This study represents the first comparative analysis of the antennal sensilla of M. quadrifasciata. The differences found in the type and amount of sensilla between the castes and sexes are discussed based on the presumed sensillary functions. 相似文献
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Myrmecophily provides various examples of how social structures can be overcome to exploit vast and well-protected resources.
Ant nest beetles (Paussinae) are particularly well suited for ecological and evolutionary considerations in the context of
association with ants because life habits within the subfamily range from free-living and predatory in basal taxa to obligatory
myrmecophily in derived Paussini. Adult Paussini are accepted in the ant society, although parasitising the colony by preying
on ant brood. Host species mainly belong to the ant families Myrmicinae and Formicinae, but at least several paussine genera
are not host-specific. Morphological adaptations, such as special glands and associated tufts of hair (trichomes), characterise
Paussini as typical myrmecophiles and lead to two different strategical types of body shape: while certain Paussini rely on
the protective type with less exposed extremities, other genera access ant colonies using glandular secretions and trichomes
(symphile type). We compare these adaptations with other taxonomic groups of insects by joining contemporary research and
early sources and discuss the possibility of an attracting or appeasing effect of the secretion. Species that are ignored
by their host ants might use chemical mimicry instead. Furthermore, vibrational signals may contribute to ant–beetle communication,
and chemical signals have proven to play a role in host finding. The powerful defense chemistry of paussines as “bombardier
beetles” is not used in contact with host ants. We attempt to trace the evolution of myrmecophily in paussines by reviewing
important aspects of the association between paussine beetles and ants, i.e. morphological and potential chemical adaptations,
life cycle, host specificity, alimentation, parasitism and sound production.
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Stefanie F. GeiselhardtEmail: |