13 research outputs found
Evaluation alternativer Hybridisierungsmarker fĂŒr die Bestimmung einer "echten" Polysomie 17 und zur Differenzierung diagnostisch zweifelhafter FĂ€lle beim invasiven Mammakarzinom
Tumoren mit einer erhöhten Cen17-Kopienzahl scheinen eine heterogene Gruppe zu reprĂ€sentieren mit komplexen chromosomalen Alterationen. Die fragwĂŒrdige Annahme, dass das Cen17-Signal mit der HĂ€ufigkeit von Chromosom 17 korrespondiert, mag zahlreiche Inkonsistenzen bezĂŒglich Polysomie 17 in der wissenschaftlichen Literatur erklĂ€ren. Auf der Grundlage zytogenetischer Untersuchungen sowie aCGH-Analysen der vorliegenden Studie wird evident, dass eine signifikante Anzahl von Tumoren mit erhöhter Cen17-Anzahl nicht auf eine Multiplikation des gesamten Chromosom 17, sondern lediglich auf partielle Amplifikationen der Zentromer 17-Region zurĂŒckzufĂŒhren ist: Die isolierte Interpretation der dadurch fĂ€lschlicherweise erniedrigten Her2/Cen17 Ratio ermöglicht keine korrekte Ausage ĂŒber den Her2-Status. Die Betrachtung der absoluten Her2-Anzahl bei Tumoren mit erhöhter Cen17-Zahl als ausschlieĂliches PositivitĂ€tskriterium vermeidet eine UnterschĂ€tzung des Her2-Status und minimiert das Risiko, bedĂŒrftigen Patienten eine Trastuzumab-Therapie irrtĂŒmlicherweise vorzuenthalten. Ăbereinstimmend mit Untersuchungen anderer Autoren wird in der vorliegenden Studie deutlich, dass "echte" Polysomie 17 ein eher seltenes Ereignis zu sein scheint, wĂ€hrend Cen17 eine zu hohe Inzidenz von Polysomie 17 suggeriert. Somit ist die Anzahl von Cen17-Hybridisierungssignalen, die streng genommen nur die HĂ€ufigkeit der Zentromer-Region widerspiegelt, nicht reprĂ€sentativ fĂŒr die tatsĂ€chliche Anzahl des gesamten Chromosoms 17. Damit ist Cen17 kein korrekter und kein zuverlĂ€ssiger Indikator einer "echten" Polysomie 17. Die Verwendung hochauflösender, DNA-basierter Techniken wie aCGH kann dabei helfen, den Chromosom 17-Status genauer zu definieren und die biologische Signifikanz genetischer Aberrationen zu klĂ€ren. Dennoch erscheint es schwierig und sicherlich kostenaufwendig, eine aCGH-gestĂŒtzte DNA-Analyse oder andere genomische AnnĂ€herungen in die klinisch-pathologische Diagnostik zu integrieren. Eine Alternative dafĂŒr könnte die Evaluation eines "Marker-Kombinations-Score" darstellen. Da in Mammakarzinomen der lange Arm 17q tendenziell eher Zugewinne mitbringt und 17p (z. B. TP53, RAI1 und D17S122) eher Verluste zeigt, könnte ein Wert, der gleichermaĂen eine 17p-und ein 17q-lokalisierte, chromosomale Region berĂŒcksichtigt, ein geeigneterer Referenzwert fĂŒr die Anzahl von Chromosom 17 sein. Die kombinierte Betrachtung von 17p- und 17q-Markern stellt eine plausible Rationale dar, die die zytogenetische Her2-Testung verbessern könnte und eine adĂ€quate Bestimmung des Her2-Status erlaubt. Der "Marker-Kombinations-Score" differenziert nicht nur zwischen Disomie und "echter" Polysomie 17, sondern hĂ€lt gleichzeitig die Gruppe der therapeutisch-strittigen zweifelhaften FĂ€lle gering, was im Zuge der stetig anwachsenden zweifelhaften FĂ€lle unter den aktualisierten ASCO/CAP-Richtlinien (2013) essentiell ist.
Bislang ist mit dieser Arbeit rein analytisch, d. h. rechnerisch gezeigt worden, dass ein "Marker-Kombinations-Score" die bisher zweifelhaften diagnostischen FĂ€lle differenzieren könnte. Die NĂŒtzlichkeit, d. h. die klinische Relevanz eines "Marker-Kombinations-Scores" muss aber auf Basis gröĂerer Brustkrebskohorten evaluiert und durch interlaboratorische, dezentralisierte Ringstudien nachgewiesen werden. Es sind prospektive Behandlungsanalysen wichtig, die zeigen, inwieweit der "Marker-Kombinations-Score" die Stratifikation von Brustkrebspatienten und individuelle Therapieentscheidungen in der klinisch-onkologischen Praxis tatsĂ€chlich verbessert und möglicherweise Patienten, denen nach bisherigen diagnostischen Kriterien eine Her2-gerichtete Therapie verwehrt war, nachtrĂ€glich eine Behandlung ermöglicht. AuĂerdem sind prospektive klinische Studien unerlĂ€sslich, die das Outcome und Therapieansprechen "echt" polysomer Tumoren gesondert von Tumoren mit Her2/Cen17-Koamplifikation und solchen mit solitĂ€rer Her2-Amplifikation ohne Cen17-Koamplifikation untersuchen. Nur so können die verschiedenen Krankheitsbilder zukĂŒnftig voneinander abgegrenzt, behandelt und Unklarheiten bezĂŒglich der Vielfalt an Tumoren mit Cen17-Amplifikationen beseitigt werden
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Plant-pollinator networks in semi-natural grasslands are resistant to the loss of pollinators during blooming of mass-flowering crops
Mass-flowering crops lead to spatial redistributions of pollinators and to transient shortages within nearby semi-natural grasslands, but the impacts on plantâpollinator interactions remain largely unexplored. Here, we characterised which pollinator species are attracted by oilseed rape and how this affected the structure of plantâpollinator networks in nearby grasslands. We surveyed 177 networks from three countries (Germany, Sweden and United Kingdom) in 24 landscapes with high crop cover, and compared them to 24 landscapes with low or no oilseed rape during and after crop blooming. On average 55% of grassland pollinator species were found on the crop, which attracted 8â35% of individuals away from grasslands. However, networks in the grasslands were resistant to these reductions, since mainly abundant and highly mobile species were attracted. Nonetheless, simulations indicated that network structural changes could be triggered if > 50% of individuals were attracted to the crop (a value well-above that found in our study system), which could affect community stability and resilience to further disturbance
Bees increase seed set of wild plants while the proportion of arable land has a variable effect on pollination in European agricultural landscapes
Background and aims - Agricultural intensification and loss of farmland heterogeneity have contributed to population declines of wild bees and other pollinators, which may have caused subsequent declines in insect-pollinated wild plants. Material and methods - Using data from 37 studies on 22 pollinator-dependent wild plant species across Europe, we investigated whether flower visitation and seed set of insect-pollinated plants decline with an increasing proportion of arable land within 1 km. Key results - Seed set increased with increasing flower visitation by bees, most of which were wild bees, but not with increasing flower visitation by other insects. Increasing proportion of arable land had a strongly variable effect on seed set and flower visitation by bees across studies. Conclusion - Factors such as landscape configuration, local habitat quality, and temporally changing resource availability (e.g. due to mass-flowering crops or honey bee hives) could have modified the effect of arable land on pollination. While our results highlight that the persistence of wild bees is crucial to maintain plant diversity, we also show that pollen limitation due to declining bee populations in homogenized agricultural landscapes is not a universal driver causing parallel losses of bees and insect-pollinated plants.Peer reviewe
The interplay of landscape composition and configuration: new pathways to manage functional biodiversity and agroecosystem services across Europe
Managing agricultural landscapes to support biodiversity and ecosystem services is a key aim of a sustainable agriculture. However, how the spatial arrangement of crop fields and other habitats in landscapes impacts arthropods and their functions is poorly known. Synthesising data from 49 studies (1515 landscapes) across Europe, we examined effects of landscape composition (% habitats) and configuration (edge density) on arthropods in fields and their margins, pest control, pollination and yields. Configuration effects interacted with the proportions of crop and nonâcrop habitats, and speciesâ dietary, dispersal and overwintering traits led to contrasting responses to landscape variables. Overall, however, in landscapes with high edge density, 70% of pollinator and 44% of natural enemy species reached highest abundances and pollination and pest control improved 1.7â and 1.4âfold respectively. Arableâdominated landscapes with high edge densities achieved high yields. This suggests that enhancing edge density in European agroecosystems can promote functional biodiversity and yieldâenhancing ecosystem services
Predicting bee community responses to land-use changes: Effects of geographic and taxonomic biases
Land-use change and intensification threaten bee populations worldwide, imperilling pollination services. Global models are needed to better characterise, project, and mitigate bees' responses to these human impacts. The available data are, however, geographically and taxonomically unrepresentative; most data are from North America and Western Europe, overrepresenting bumblebees and raising concerns that model results may not be generalizable to other regions and taxa. To assess whether the geographic and taxonomic biases of data could undermine effectiveness of models for conservation policy, we have collated from the published literature a global dataset of bee diversity at sites facing land-use change and intensification, and assess whether bee responses to these pressures vary across 11 regions (Western, Northern, Eastern and Southern Europe; North, Central and South America; Australia and New Zealand; South East Asia; Middle and Southern Africa) and between bumblebees and other bees. Our analyses highlight strong regionally-based responses of total abundance, species richness and Simpson's diversity to land use, caused by variation in the sensitivity of species and potentially in the nature of threats. These results suggest that global extrapolation of models based on geographically and taxonomically restricted data may underestimate the true uncertainty, increasing the risk of ecological surprises
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Effects of landscape composition and configuration on pollination in a native herb: a field experiment
Martin et al_2019_datatables
Data used in Martin et al. (2019) compiled from 49 studies and 1,515 landscapes across Europe. Includes data on the abundance of arthropod species per site and data on pollination, natural pest control and yields in crops across Europe
Martin et al_2019_traits database
Functional traits data for 2088 species (morphospecies, individuals) from 144 arthropod families sampled in agricultural landscapes across Europe. All traits are categorical and based on published literature or expert knowledge. They are described in Table 1 and Appendix S1 of Martin et al. (2019). The traits included are: feeding habit ('Functional group'), diet breadth, agricultural specialism, diet life history, overwintering habitat, dispersal mode, and stratum. Species' names were resolved in R package taxize