530 research outputs found
30 years of hay meadow succession without fertilization: how does it affect soil and avifauna groups?
In the present study we investigated the effects of hay meadow succession in the brook valley system of the Drentse A Nature Reserve, in the NE of the Netherlands. In particular, we compared the plant and soil fauna composition in five grasslands that differed in the stage of vegetation succession in two well-studied chronosequences, dry and wet respectively. The sampled meadows include a control site (still fertilized meadow), a 5, 15, 25 and 32 years stage of vegetation succession after the cessation of fertilizer application. At all sites, vegetation and earthworm composition was studied in replicate subplots of 4 m2 respectively 0.04 m² each. Moreover, the breeding birds have been monitored in the area over the last 28 years by mapping territories overlapping the meadows of the chronosequences. Concerning the plants we found that diversity was increasing with time of succession. In the wet meadow series the plant species richness increased from ca. 13 species per site (40 m2) to a maximum of ca. 49 species per site in the latest successional stage. In the drier parts the increase in species was less and reached an over all maximum of 27 species in the intermediate (15 years old) stage of the succession in 40 m2, but still increased to a mean of 15 species at the scale of 4 m2 plots in the oldest stage. The diversity and abundance of earthworms dropped significantly over time of succession. The species all belonged to 4 genera with Allolobophora being the most abundant. Soil pH dropped significantly during the succession even below 3.8 in the dry series. This largely explains the unfavourable conditions for the earthworms to survive in the oldest stages of the dry succession. The earthworm biomass dropped in nearly all sites below 25 g/m2 during the summer period, indicating unfavourable conditions for a suit of grassland breeding waders.The abundance of breeding birds in general was low due to the rather small area covered in this study. Anyhow we could find obvious changes in the breeding bird community. In particular waders such as Lapwing (Vanellus vanellus) and Black-tailed Godwit (Limosa limosa) disappeared completely from the area and were followed up by Curlew (Numenius arquata) and Snipe (Gallinago gallinago) being currently also rare in the area. Probably due to changes in grassland vegetation (increase of amongst others Cirsium palustre) and insect abundance the Stonechat (Saxicola torquata) has entered the area as a breeding bird. The same happens to a set of bird species typical for developing carr woodlands such as Lesser Spotted Woodpecker (Dendrocopos minor) and Golden Oriole (Oriolus oriolus).Die vorliegende Studie thematisiert am Beispiel der Fließgewässerniederung der Drentse A, einem großflächigen Schutzgebiet im Nordosten der Niederlande, die Folgen einer langjährigen Heuwiesennutzung ohne Düngung. Im Einzelnen wurde von uns die Zusammensetzung der Vegetation und Bodenfauna auf fünf Grünlandflächen untersucht, die sich in der Dauer der Ausmagerung unterschieden. Getrennt betrachtet wurden dabei die bachnahen, moorigen Niederungsbereichen und die angrenzenden sandigen Geestbereiche. Die ausgewählten Grünlandflächen waren zum Zeitpunkt der Aufnahmen seit 5, 15, 25, und 32 Jahren gemäht aber nicht mehr gedüngt worden. Eine weitere, nach wie vor konventionell bewirtschaftete Wiesenfläche (incl. Düngung) diente als Kontrolle. Auf allen Flächen wurde die Vegetation und Regenwurmfauna in 10 Plots mit einer Größe von jeweils 4 m² bzw. 0.04 m² untersucht. Darüber hinaus wurden über 28 Jahre hinweg die Brutvögel des Gebietes mittels Revierkartierung erfasst. Die Pflanzenartendiversität hat sich mit Dauer der Ausmagerung signifikant erhöht. Sie stieg in den bachnahen Bereichen von 13 Arten in der Kontrollfläche (40 m²) auf 49 Arten in der am längsten ausgemagerten Grünlandfläche an. In den trockenen Geestbereichen war der Anstieg deutlich schwächer. Bezogen auf die Gesamtfläche von 40 m² wurden die meisten Arten hier in der 15 Jahre lang ausgemagerten Grünlandfläche gefunden, während bei Betrachtung der 4 m² großen Aufnahmepunkte die höchste Artenzahl ebenfalls in der ältesten Untersuchungsfläche lag. Die Diversität und Abundanz der Regenwürmer nahm mit Dauer der Ausmagerung ab. Die festgestellten Arten gehörten zu 4 Gattungen, wobei die Gattung Allolobophora am individuenreichsten vertreten war. Mit Dauer der Ausmagerung sank besonders im trockenen bachfernen Geestbereich der Boden-pH-Wert auf unter 3,8 ab. Die damit einhergehenden pessimalen Lebensbedingungen erklären hinreichend die geringe Diversität und Dichte von Regenwürmern in diesen Bereichen. An fast allen Standorten sank die Biomasse der Regenwürmer zum Sommer hin auf Werte unter 25 g/m², so dass für viele Limikolen zu dieser Zeit pessimale Ernährungsbedingungen bestehen. Die Zahl der Brutvogelarten war aufgrund des recht kleinen Untersuchungsgebietes insgesamt gering. Dennoch konnten auffallende Veränderungen in der Brutvogelgemeinschaft beobachtet werden. Während Limikolen wie Kiebitz (Vanellus vanellus) und Uferschnepfe (Limosa limosa) vollständig aus dem Gebiet verschwanden, wanderten der Große Brachvogel und die Bekassine ein. Allerdings sind auch sie aktuell nur noch selten im Gebiet vertreten. Dafür hat sich inzwischen das Schwarzkehlchen (Saxicola torquata) als Brutvogel eingestellt – möglicherweise eine Folge der sich ändernden Grünlandvegetation (hier: Zunahme von Pflanzenarten, die als Ansitzwarten fungieren können wie etwa Cirsium palustre) in Kombination mit einem verbesserten Nahrungsangebot an Makroinvertebraten. Eingewandert sind zwischenzeitlich auch eine Reihe weiterer Vogelarten, wie Pirol (Oriolus oriolus) und Kleinspecht (Dendrocopos minor), die charakteristisch für sich entwickelnde Bruchwälder sind. Letztere haben sich, meist kleinflächig, auf ehemaligen Feuchtgrünlandstandorten entwickelt
Linking models for land use analysis: experiences from the SENSOR project
In order to quantify the effects of a comprehensive set of policies on land use, interaction between sectors needs to be accounted for, while maintaining a high level of detail for each sector. This calls for a combination of sector specific and sector wide models. This paper describes such a modelling system, with emphasis on the linking of the models to a coherent system. Five sectors of significant importance for land use are modelled individually: Forestry, agriculture, urban land use, transport infrastructure, and tourism. All models are connected as sub-modules to an economy-wide partial econometric model. In addition, a land cover model is used to disaggregate land use down to 1km grid resolution. The linking of such a diverse set of models in a consistent way poses conceptual as well as practical issues. The conceptual issues concern questions such as which items of the models to link, how to obtain a stable joint baseline scenario, and how to obtain a joint equilibrium solution for all models simultaneously in simulation. Practical issues concern the actual implementation of the conceptually sound linkages and provision of a workable technical solution. The linked system allows us to introduce a shock in either of the models, and the set of results will provide a joint solution for all sectors modelled in SENSOR. In this manner, the models take a complex policy scenario as argument and compute a comprehensive set of variables involving all five land use sectors on regional level, which in turn forms a basis for distilling out the impact on sustainability in the form of indicators. Without the extensive automation and technical linkages, it would not have been possible to obtain a joint equilibrium, or it would have required exorbitant amounts of working time.Model linking, sustainable land use, cross sector modelling, iterative recalibration, Land Economics/Use,
The silicon trypanosome
African trypanosomes have emerged as promising unicellular model organisms for the next generation of systems biology. They offer unique advantages, due to their relative simplicity, the availability of all standard genomics techniques and a long history of quantitative research. Reproducible cultivation methods exist for morphologically and physiologically distinct life-cycle stages. The genome has been sequenced, and microarrays, RNA-interference and high-accuracy metabolomics are available. Furthermore, the availability of extensive kinetic data on all glycolytic enzymes has led to the early development of a complete, experiment-based dynamic model of an important biochemical pathway. Here we describe the achievements of trypanosome systems biology so far and outline the necessary steps towards the ambitious aim of creating a , a comprehensive, experiment-based, multi-scale mathematical model of trypanosome physiology. We expect that, in the long run, the quantitative modelling enabled by the Silicon Trypanosome will play a key role in selecting the most suitable targets for developing new anti-parasite drugs
Introducing trimming and function ranking to Solid Works based on function analysis
TRIZ based Function Analysis models existing products based on functional interactions between product parts. Such a function model description is the ideal starting point for product innovation. Design engineers can apply (TRIZ)\ud
methods such as trimming and function ranking to this function model to improve their products. This paper describes the introduction of said methods directly into CAD software, since this is software often used by design engineers. As such, design engineers do not have to switch between applications, or worse, convert product data sets, when jumping from product detailing to innovation tasks. The developed software tool tries to actively guide engineers through the innovation process, progressing more quickly through product design and redesign phases. Thus, resulting in shorter lead times and a faster time-to-market for the industr
Riboflavin-responsive complex I deficiency
Three patients from a large consanguineous family, and one unrelated patient had exercise intolerance since early childhood and improved by supplementation with a high dosage of riboflavin. This was confirmed by higher endurance power in exercise testing. Riboflavin had been given because complex I, which contains riboflavin in FMN, one of its prosthetic groups, had a very low activity in muscle. Histochemistry showed an increase of subsarcolemmal mitochondria. The low complex I activity contrasted with an increase of the activities of succinate dehydrogenase, succinate-cytochrome c oxidoreductase and cytochrome c oxidase. Isolated mitochondria from these muscle specimens proved deficient in oxidizing pyruvate plus malate and other NAD+-linked substrates, but oxidized succinate and ascorbate at equal or higher levels than controls. Two years later a second biopsy was taken in one of the patients, and the activity of complex I had increased from 16% to 47% of the average activity in controls. In the four biopsies, cytochrome c oxidase activity correlated negatively with age. We suspect that this is due to reactive oxygen species generated by the proliferating mitochondria and peroxidizing unsaturated fatty acids of cardiolipin. Three of the four patients had low blood carnitine, and all were found to have hypocarnitinemic family members
Neonatal cardiomyopathy and lactic acidosis responsive to thiamine
A congestive cardiomyopathy was diagnosed in a girl at the age of 4 weeks. In the weeks following she developed general muscle hypotonia and plasma lactate increased to 8.5 mmol/L. Biochemical investigations of a muscle biopsy at the age of 3 months showed a deficiency in the oxidation of all substrates tested: pyruvate plus malate, 2-ketoglutarate and palmitate plus malate. After freezing and thawing of the homogenate and the addition of essential cofactors, the oxidation of the ketoacids normalized. The oxidation defect in the untreated homogenate can be explained by a deficiency in one of the cofactors (such as thiamine pyrophosphate, NAD+ or CoASH), or by a defect in the oxidative phosphorylation. Treatment with thiamine and carnitine resulted in a decrease in blood lactate to normal levels and a dramatic clinical improvement. Suspension of thiamine caused deterioration of her clinical condition and lactic acidaemia. The thiamine therapy was then continued. The girl is now 6 years old and in perfect health
Haplotypes encoding the factor VIII 1241Glu variation, factor VIII levels and the risk of venous thrombosis \ud \ud
Levels of factorVIII (FVIII) are associated with the risk of venous thrombosis.The FVIII variation D1241E has been reported to be associated with decreased levels of FVIII. Our objective was to study whether D1241E is associated with levels of FVIII and the risk of venous thrombosis and whether this association is caused by D1241E or another linked variation.We analyzed the association of three FVIII gene haplotypes encoding 1241E (further denoted as HT1, HT3, and HT5) with FVIII levels and thrombosis risk. This analysis was performed in the Leiden Thrombophilia Study (LETS). The control populations of two case-controls studies on arterial thrombosis in men and women, respectively, were used to confirm the effects observed on FVIII:C in the LETS.In men,HT1 was associated with a 6% re- duction in FVIII:C and with a reduced risk of venous thrombosis [odds ratio 0.4 (CI95 0.2–0.8)]. Logistic regression showed that the risk reduction was only partially dependent of the reduction in FVIII levels. HT1 showed no effects in women on either FVIII:C or risk of thrombosis.The number of carriers of HT3 and HT5 was too low to make an accurate estimate of the risk of venous thrombosis. Neither HT3 nor HT5 showed effects on levels of FVIII:C.When we consider that all three haplotypes encoding 1241E show different effects on FVIII:C and thrombosis risk, it is possible that D1241E is not the functional variation. However, FVIII gene variations do contribute to both levels of FVIII and the risk of thrombosi
Golgi targeting of Drosophila melanogaster β4GalNAcTB requires a DHHC protein family–related protein as a pilot
Drosophila melanogaster β4GalNAcTB mutant flies revealed that this particular N-acetylgalactosaminyltransferase is predominant in the formation of lacdiNAc (GalNAcβ1,4GlcNAc)-modified glycolipids, but enzymatic activity could not be confirmed for the cloned enzyme. Using a heterologous expression cloning approach, we isolated β4GalNAcTB together with β4GalNAcTB pilot (GABPI), a multimembrane-spanning protein related to Asp-His-His-Cys (DHHC) proteins but lacking the DHHC consensus sequence. In the absence of GABPI, inactive β4GalNAcTB is trapped in the endoplasmic reticulum (ER). Coexpression of β4GalNAcTB and GABPI generates the active enzyme that is localized together with GABPI in the Golgi. GABPI associates with β4GalNAcTB and, when expressed with an ER retention signal, holds active β4GalNAcTB in the ER. Importantly, treatment of isolated membrane vesicles with Triton X-100 disturbs β4GalNAcTB activity. This phenomenon occurs with multimembrane-spanning glycosyltransferases but is normally not a property of glycosyltransferases with one membrane anchor. In summary, our data provide evidence that GABPI is required for ER export and activity of β4GalNAcTB
Using a novel concept to measure outcomes in solid organ recipients provided promising results
Objectives: Efforts to evaluate the health of solid organ transplant recipients are hampered by the lack of adequate patient-reported outcome measures (PROMs) targeting this group. We developed the Transplant ePROM (TXP), which is based on a novel measurement model and administered through a mobile application to fill this gap. The main objective of this article is to elucidate how we derived the weights for different items, and to report initial empirical results. Study design and setting: The nine health items in the TXP were fatigue, skin, worry, self-reliance, activities, weight, sexuality, stooling, and memory. Via an online survey solid organ recipient participating in the TransplantLines Biobank and Cohort study (NCT03272841) were asked to describe and then compare their own health state with six other health states. Coefficients for item levels were obtained using a conditional logit model. Results: A total of 232 solid organ transplant recipients (mean age: 54 years) participated. The majority (106) were kidney recipients, followed by lung, liver, and heart recipients. Fatigue was the most frequent complaint (54%). The strongest negative coefficients were found for activities and worry, followed by self-reliance and memory. Conclusion: A set of coefficients and values were developed for TXP. The TXP score approximated an optimal health state for the majority of respondents and recipients of different organs reported comparable health states. (c) 2021 The Authors. Published by Elsevier Inc. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/
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