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191.
Orchids of the genus Ophrys are pollinated by males of solitary bees and wasps through sexual deception. Flowers mimic the odor of a receptive female
and thus attract males that seek to copulate. Visual stimuli have been assumed so far to play only a minor role in male attraction.
We investigated the role of the perigon as a potential visual signal in attracting pollinators in the orchid Ophrys heldreichii and its pollinator, the males of the long-horned bee Tetralonia berlandi (Apidae). In contrast to many other Ophrys species, O. heldreichii exhibits a large and bright pinkish perigon that appears visually conspicuous to a human observer. In a dual choice test
we presented two flowers from a single plant and counted visitation rates. We then removed the perigon of one flower and retested
the relative attractiveness of both flowers. For 292 male visits in ten trials we found a significant decrease of visitation
rate for flowers with the perigon removed. In a second experiment we repeated the dual choice test using photos of the flowers.
Males also significantly chose the picture of an intact flower over the picture of a modified flower where the perigon was
digitally removed. From our data, we conclude that T. berlandi males respond to and are attracted by the bright pink perigon of the orchid in addition to other stimuli. A bright colorful
perigon occurs almost only in the Ophrys holoserica-oestrifera group, a large sub-group of the genus. We hypothesize that this kind of visual signal is adaptive particularly in those Ophrys species where the targeted males patrol resourced-based encounter sites and strongly rely on their visual system while searching
for their females. 相似文献
192.
193.
Alberto Pisoni Zsolt Turi Almuth Raithel Géza Gergely Ambrus Ivan Alekseichuk Annekathrin Schacht Walter Paulus Andrea Antal 《PloS one》2015,10(3)
There is emerging evidence from imaging studies that parietal and temporal cortices act together to achieve successful recognition of declarative information; nevertheless, the precise role of these regions remains elusive. To evaluate the role of these brain areas in declarative memory retrieval, we applied bilateral tDCS, with anode over the left and cathode over the right parietal or temporal cortices separately, during the recognition phase of a verbal learning paradigm using a balanced old-new decision task. In a parallel group design, we tested three different groups of healthy adults, matched for demographic and neurocognitive status: two groups received bilateral active stimulation of either the parietal or the temporal cortex, while a third group received sham stimulation. Accuracy, discriminability index (d’) and reaction times of recognition memory performance were measurements of interest. The d’ sensitivity index and accuracy percentage improved in both active stimulation groups, as compared with the sham one, while reaction times remained unaffected. Moreover, the analysis of accuracy revealed a different effect of tDCS for old and new item recognition. While the temporal group showed enhanced performance for old item recognition, the parietal group was better at correctly recognising new ones. Our results support an active role of both of these areas in memory retrieval, possibly underpinning different stages of the recognition process. 相似文献
194.
Winkelmann J Czamara D Schormair B Knauf F Schulte EC Trenkwalder C Dauvilliers Y Polo O Högl B Berger K Fuhs A Gross N Stiasny-Kolster K Oertel W Bachmann CG Paulus W Xiong L Montplaisir J Rouleau GA Fietze I Vávrová J Kemlink D Sonka K Nevsimalova S Lin SC Wszolek Z Vilariño-Güell C Farrer MJ Gschliesser V Frauscher B Falkenstetter T Poewe W Allen RP Earley CJ Ondo WG Le WD Spieler D Kaffe M Zimprich A Kettunen J Perola M Silander K Cournu-Rebeix I Francavilla M Fontenille C Fontaine B 《PLoS genetics》2011,7(7):e1002171
Restless legs syndrome (RLS) is a sensorimotor disorder with an age-dependent prevalence of up to 10% in the general population above 65 years of age. Affected individuals suffer from uncomfortable sensations and an urge to move in the lower limbs that occurs mainly in resting situations during the evening or at night. Moving the legs or walking leads to an improvement of symptoms. Concomitantly, patients report sleep disturbances with consequences such as reduced daytime functioning. We conducted a genome-wide association study (GWA) for RLS in 922 cases and 1,526 controls (using 301,406 SNPs) followed by a replication of 76 candidate SNPs in 3,935 cases and 5,754 controls, all of European ancestry. Herein, we identified six RLS susceptibility loci of genome-wide significance, two of them novel: an intergenic region on chromosome 2p14 (rs6747972, P = 9.03 × 10−11, OR = 1.23) and a locus on 16q12.1 (rs3104767, P = 9.4 × 10−19, OR = 1.35) in a linkage disequilibrium block of 140 kb containing the 5′-end of TOX3 and the adjacent non-coding RNA . BC034767相似文献
195.
Nikolas K. Haass Kimberley A. Beaumont David S. Hill Andrea Anfosso Paulus Mrass Marcia A. Munoz Ichiko Kinjyo Wolfgang Weninger 《Pigment cell & melanoma research》2014,27(5):764-776
Solid cancers are composed of heterogeneous zones containing proliferating and quiescent cells. Despite considerable insight into the molecular mechanisms underlying aberrant cell cycle progression, there is limited understanding of the relationship between the cell cycle on the one side, and melanoma cell motility, invasion, and drug sensitivity on the other side. Utilizing the fluorescent ubiquitination‐based cell cycle indicator (FUCCI) to longitudinally monitor proliferation and migration of melanoma cells in 3D culture and in vivo, we found that invading melanoma cells cycle actively, while G1‐arrested cells showed decreased invasion. Melanoma cells in a hypoxic environment or treated with mitogen‐activated protein kinase pathway inhibitors remained G1‐arrested for extended periods of time, with proliferation and invasion resuming after re‐exposure to a more favorable environment. We challenge the idea that the invasive and proliferative capacity of melanoma cells are mutually exclusive and further demonstrate that a reversibly G1‐arrested subpopulation survives in the presence of targeted therapies. 相似文献
196.
Temporal dynamics of cytomegalovirus chromatin assembly in productively infected human cells 下载免费PDF全文
The genomes of herpesviruses, including human cytomegalovirus (CMV), are double-stranded DNA molecules maintained as episomes during infection. The viral DNA lacks histones when encapsidated in the virion. However, it has been found histone associated inside infected cells, implying unidentified chromatin assembly mechanisms. Our results indicate that components of the host cell nucleosome deposition machinery target intranuclear CMV DNA, resulting in stepwise viral-chromatin assembly. CMV genomes undergo limited histone association and nucleosome assembly as early as 30 min after infection via DNA replication-independent mechanisms. Low average viral-genome chromatinization is maintained throughout the early stages of infection. The late phase of infection is characterized by a striking increase in average histone occupancy coupled with the process of viral-DNA replication. While the initial chromatinization affected all analyzed parts of the CMV chromosome, a subset of viral genomic regions, including the major immediate-early promoter, proved to be largely resistant to replication-dependent histone deposition. Finally, our results predict the likely requirement for an unanticipated chromatin disassembly process that enables packaging of histone-free DNA into progeny capsids. 相似文献
197.
Differences in the fruit maturation stages at which oviposition occurs among insect seed predators feeding on the fruits of five dipterocarp tree species 下载免费PDF全文
Asano Iku Takao Itioka Usun Shimizu‐Kaya Keiko Kishimoto‐Yamada Paulus Meleng 《Entomological Science》2018,21(4):412-422
The seeds of dipterocarp trees are the main food resources for many species of weevils, bark beetles and small moths; however, for most seed‐eating insects on dipterocarp tropical trees, seed utilization patterns remain poorly investigated. This study aimed to determine the fruit maturation stages at which eggs are laid by different insect seed predators feeding on the seeds or fruits of the following five dipterocarp species: Dipterocarpus globosus, Dryobalanops aromatica, Shorea beccariana, S. acuta and S. curtisii, which reproduced during the same period. We investigated the occurrence frequencies of the insect seed predators at various growth stages by collecting both unfallen and fallen fruit on several occasions during the period of seed/fruit maturation in a tropical rainforest in Borneo from September to December 2013. Weevils and bark beetles were the dominant insect seed predators of the five tree species. One or two weevil species of Alcidodes, Damnux and/or Nanophyes preyed on the seeds of each of the five tree species, and one bark beetle species, Coccotrypes gedeanus, preyed on the seeds of all five tree species. Many larvae, pupae and adults of each weevil species were found in pre‐dispersal (unfallen) fruit, whereas bark beetles at various growth stages were found in post‐dispersal (fallen) fruit. These results suggested that, among the dominant insect seed predators of the five dipterocarp species, weevil species oviposit on pre‐dispersal fruit and begin their larval growth before seed dispersal, whereas the oviposition and larval development of bark beetle species occurs in post‐dispersal fruit. 相似文献
198.
Many mouse models exist for neural tube defects (NTDs), but only few of them are relevant for human patients that are born
alive with spina bifida aperta. NTDs in humans show a complex inheritance, which most likely result from the involvement of
a variety of predisposing genetic and environmental factors. Hints toward the identity of predisposing genetic factors for
human NTDs could come from mouse studies on the development of the neural tube and spinal cord, as well as from studies on
associated features of this type of diseases. Among such features is the observation that pregnancies affected by a neural
tube defect frequently show changes in thymus morphology, and in both neonatal and maternal T-cell repertoire. The genes for
E2a and Pax1 have both been implicated in not only paraxial mesodermal development, but also in that of the immune system.
Moreover, Pax1 mutant mice have been shown to display NTDs in digenic mouse models. In the present study we have investigated the phenotype
of E2a null mutant mice that are also heterozygous for the so-called undulated mutation in Pax1. Here we report that such double-mutant mice develop a non-lethal NTD that strongly resembles the classic human NTD: spina
bifida aperta, associated with defects of the axial skeleton, immune system and urinary tract. 相似文献
199.
The gene coding for the subunits of aspartokinase II from Bacillus subtilis has been identified in a B. subtilis DNA library and cloned in a bacterial plasmid (Bondaryk, R. P., and Paulus, H. (1984) J. Biol. Chem. 259, 585-591). The introduction of a plasmid carrying the aspartokinase II gene into an auxotrophic Escherichia coli strain lacking all three aspartokinases restored its ability to grow in the absence of L-lysine, L-threonine, and L-methionine. The B. subtilis aspartokinase gene could thus be functionally expressed in E. coli and substitute for the E. coli aspartokinases. Measurement of aspartokinase levels in extracts of aspartokinaseless E. coli transformed with the B. subtilis aspartokinase II gene revealed an enzyme level comparable to that in a genetically derepressed B. subtilis strain. In spite of the high level of aspartokinase, the growth of the transformed E. coli strain was severely inhibited by the addition of L-lysine but could be restored by also adding L-homoserine. This apparently paradoxical sensitivity to lysine was due to the allosteric inhibition of B. subtilis aspartokinase II by that amino acid, a property which was also observed in extracts of the transformed E. coli strain. The synthesis and degradation of the aspartokinase II subunits were measured by labeling experiments in E. coli transformed with the B. subtilis aspartokinase II gene. In contrast to exponentially growing cells of B. subtilis which contained equimolar amounts of the aspartokinase alpha and beta subunits, the transformed E. coli strain contained a 3-fold molar excess of beta subunit. Pulse-chase experiments showed that the disproportionate level of beta subunit was not due to more rapid turnover of alpha subunit, both subunits being quite stable, but presumably to a more rapid rate of synthesis. After the addition of rifampicin, the synthesis of alpha subunit declined much more rapidly than that of beta subunit, indicating that the two subunits were translated independently from mRNA species that differ in functional stability. In conjunction with the results described in the preceding paper which demonstrated that the aspartokinase subunits are encoded by a single DNA sequence, these observations imply that the alpha and beta subunits of B. subtilis aspartokinase II are the products of in-phase overlapping genes. 相似文献
200.
Johannes Holfeld Can Tepek?ylü Stefan Blunder Daniela Lobenwein Elke Kirchmair Marion Dietl Radoslaw Kozaryn Daniela Lener Markus Theurl Patrick Paulus Rudolf Kirchmair Michael Grimm 《PloS one》2014,9(8)