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101.
Wolfgang Uerkvitz Olle Karlström Agnete Munch-Petersen 《Molecular & general genetics : MGG》1973,121(4):337-346
Summary A two-step mutant lacking two periplasmic enzymes, alkaline phosphatase and 5-nucleotidase, was prepared. In extracts of this strain phosphatase activities towards several 5-nucleotides could be detected. We have partially purified a dUMP phosphatase by streptomycin precipitation and DEAE-chromatography. This preparation has significant phosphatase activity towards three substrates, viz. dUMP, dTMP and UMP, but only traces of activity towards nine other tested nucleoside monophosphates. The three activities are probably due to a single enzyme, since they decrease in parallel on long time storage at 4°C and respond in parallel to stimulatory and inhibitory influences of different buffers and metal ions. The best buffer tested is glycylglycine buffer; Mg2+ is required but 25% activity can be obtained with Co2+ and Mn2+ and 6–8% activity with Fe2+ and Ni2+. Ca2+, Cu2+ or Zn2+ inhibit the phosphatase activities in the presence of Mg2+ or Co2+. The activities towards UMP and dUMP in the DEAE—chromatography eluted identically. The enzyme has the remarkably high apparent K
m of 10-2 M with all three substrates. 相似文献
102.
Aileen Berasategui Karolin Axelsson Göran Nordlander Axel Schmidt Anna‐Karin Borg‐Karlson Jonathan Gershenzon Olle Terenius Martin Kaltenpoth 《Molecular ecology》2016,25(16):4014-4031
The pine weevil (Hylobius abietis, Coleoptera: Curculionidae) is an important pest of conifer seedlings in Europe. Despite its economic importance, little is known about the composition of its gut microbial community and the role it plays in mediating the weevil's ability to utilize conifers as a food source. Here, we characterized the gut bacterial communities of different populations of H. abietis across Europe and compared them to those of other beetles that occupy similar ecological niches. We demonstrate that the microbial community of H. abietis is similar at higher taxonomic levels (family and genus) across locations in Europe, with Wolbachia as the dominant microbe, followed by Enterobacteria and Firmicutes. Despite this similarity, we observed consistent differences between countries and locations, but not sexes. Our meta‐analysis demonstrates that the gut bacterial community of the pine weevil is very similar to that of bark beetles that also exploit conifers as a food source. The Enterobacteriaceae symbionts of both host taxa are especially closely related phylogenetically. Conversely, the microbiota of H. abietis is distinct from that of closely related weevils feeding on nonconifer food sources, suggesting that the microbial community of the pine weevil is determined by the environment and may be relevant to host ecology. Furthermore, several H. abietis‐associated members of the Enterobacteriaceae family are known to contain genes involved in terpenoid degradation. As such, we hypothesize that the gut microbial community is important for the utilization of conifer seedlings as a food source, either through the detoxification of plant secondary metabolites or through the supplementation of essential nutrients. 相似文献
103.
104.
Yucca moth oviposition and pollination behavior is affected by past flower visitors: evidence for a host-marking pheromone 总被引:1,自引:0,他引:1
Insect larvae such as those of yucca moths that feed on small, patchily distributed food items often face an elevated risk
of intraspecific competition or cannibalism. For this reason, ovipositing females may assess a potential oviposition site
for prior conspecific eggs or larvae before deciding whether to oviposit. Selective abortion of yucca flowers with high egg
numbers prevents competition among larvae of the yucca moth Tegeticula yuccasella, but the same mechanism should select for female detection of and fewer ovipositions in flowers that already contain eggs.
Female yucca moths presented with either virgin or previously visited flowers laid significantly fewer eggs in the latter
flowers and pollinated them less often. A significant negative association was found between number of previous oviposition
attempts in a flower and number of additional attempts by a female, suggesting a quantitative assessment of prior egg load,
but the correlation coefficient was low. Factors contributing to this low correlation may include variation in signal quality,
poor detection capability, uncertainty contributed by a variable oviposition attempt to egg ratio, and a variable response
criterion based on recent female experience and physiological status. Females rationed their pollen by pollinating at decreasing
frequency during a bout within a flower, and by depositing smaller pollen loads during later pollinations within a flower.
Females ovipositing into a previously visited flower pollinated as frequently as would a first female for a given oviposition
attempt within a flower, i.e., the probability of pollination after the nth oviposition was independent of whether it was performed by a first or a later moth. Experimental presentation of virgin
flowers marked with a homogenate from female abdomens induced the same oviposition and pollination behavior as seen on previously
visited flowers, suggesting the presence of a host-marking pheromone. Given that all eggs within a selectively aborted flower
die, there may be selection among some yucca moths for providing a strong signal of floral egg status to conspecific females.
Received: 1 December 1998 / Accepted: 7 February 1999 相似文献
105.
106.
We describe a method, DNA array to protein array (DAPA), which allows the 'printing' of replicate protein arrays directly from a DNA array template using cell-free protein synthesis. At least 20 copies of a protein array can be obtained from a single DNA array. DAPA eliminates the need for separate protein expression, purification and spotting, and also overcomes the problem of long-term functional storage of surface-bound proteins. 相似文献
107.
We have compared the basic organization of the primary olfactory centre, the antennal lobe (AL), in 4 hemipteran species representing the 2 major lineages in this order. The Homoptera were represented by the psyllid Trioza apicalis and its aphid relatives the grain aphid Sitobion avenae Fabricius and the rose-grain aphid Metopolophium dirhodum Walker, whereas the Heteroptera were represented by the pentatomid stink bug Euschistus heros Fabricius. The olfactory systems of psyllids and aphids are generally very small, with low numbers of afferents in comparison to other insect groups, and the smallest described so far belongs to T. apicalis, comprising less than 50 olfactory receptor neurons (ORNs). Originally, we tried to estimate numbers of olfactory glomeruli in the AL of T. apicalis, which in insects generally correspond closely to the number of different types of ORNs. Neither immunocytochemical staining nor anterograde staining of ORNs revealed any glomerular structures in the ALs of T. apicalis or the 2 aphids that were included for comparison. In contrast, the ALs of the pentatomid stink bug E. heros displayed numerous distinct and well-delineated glomeruli, showing that aglomerular ALs are not typical of all insects within the order Hemiptera. Glomeruli are hallmark features of olfactory lobes in many different phyla, and the absence of glomerular structures in psyllids and aphids appears to be unique in insects that depend on olfactory orientation. 相似文献
108.
Abstract. Remaining deciduous forests in the Fennoscandian boreal landscape have high ecological value, and are considered as key components of the forest landscape as well as remnants of a former natural forest type. To improve our understanding of the formation of deciduous forests, we studied past disturbance regimes and vegetation dynamics in three deciduous forests in boreal Sweden using dendro‐ecology, pollen analysis and charcoal analysis. We identified three stages in the development of the studied stands. Firstly, the coniferous period (pre 1800), a long‐lasting period characterized by frequent fires, livestock grazing and extensive agriculture during which Pinus sylvestris was dominant. Secondly, the transformation period (1800 ‐ 1900), when logging removed most pines from the sites while fire and grazing continued. At the time of the last fire, the sites lacked a local seed source of pines, resulting in a post‐fire succession dominated by deciduous species with the capacity to disperse over long distances. Thirdly, the deciduous period (1900 ‐ present), with little or no disturbance from fire, grazing or logging. Thus, the present deciduous stands have their origins in a complex interaction between changes in fire regime, extensive land use patterns and logging, contrary to earlier simplified explanations. We conclude that the complexity of historical patterns of land use, vegetation dynamics and disturbance should be acknowledged in the future when selecting areas for nature conservation and developing models for ecologically oriented forestry. 相似文献
109.
Assessing the use of genomic DNA as a predictor of the maximum absorbance wavelength of avian SWS1 opsin visual pigments 总被引:1,自引:1,他引:0
Anders Ödeen Nathan S. Hart Olle Håstad 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》2009,195(2):167-173
Recently, in vitro mutation studies have made it possible to predict the wavelengths of maximum absorbance (λmax) of avian UV/violet sensitive visual pigments (SWS1) from the identity of a few key amino acid residues in the opsin gene.
Given that the absorbance spectrum of a cone’s visual pigment and of its pigmented oil droplet can be predicted from just
the λmax, it may become possible to predict the entire spectral sensitivity of a bird using genetic samples from live birds or museum
specimens. However, whilst this concept is attractive, it must be validated to assess the reliability of the predictions of
λmax from opsin amino acid sequences. In this paper, we have obtained partial sequences covering three of the known spectral tuning
sites in the SWS1 opsin and predicted λmax of all bird species for which the spectral absorbance has been measured using microspectrophotometry. Our results validate
the use of molecular data from genomic DNA to predict the gross differences in λmax between the violet- and ultraviolet-sensitive subtypes of SWS1 opsin. Additionally, we demonstrate that a bird, the bobolink
Dolichonyx oryzivorus L., can have more than one SWS1 visual pigment in its retina. 相似文献
110.
Jeff A. Graves Alice Helyar Martin Biuw Mart Jüssi Ivar Jüssi Olle Karlsson 《Conservation Genetics》2009,10(1):59-68
The growing number of grey seals in the Baltic Sea has led to a dramatic increase in interactions between seals and fisheries.
The conflict has become such a problem that hunting was introduced in Finland in 1998 and the Swedish Environment Protection
Agency recommended a cull of grey seals starting in 2001. Culling has been implemented despite the lack of data on population
structure. Low levels of migration between regions would mean that intensive culling in specific geographic areas would have
disproportionate effects on local population structure and genetic diversity. We used eight microsatellite loci and a 489 bp
section of the mtDNA control region to examine the genetic variability and differentiation between three breeding sites in
the Baltic Sea and two in the UK. We found high levels of genetic variability in all sampled Baltic groups for both the microsatellites
and the control region. There were highly significant differences in microsatellite allele frequencies between all three Baltic
breeding sites and between the Baltic sites and the UK sites. However, there were no significant differences in mtDNA control
region haplotypes between the Baltic sites. This genetic substructure of the Baltic grey seal populations should be taken
into consideration when managing the seal population to prevent the hunting regime from having an adverse effect on genetic
diversity by setting hunting quotas separately for the different subpopulations.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献