Diskussionsbeitrag zur Segmentierung des Cheliceraten-Kopfes

Zusammenfassung Die kritischen Untersuchungen von Weygoldt's Untersuchungen über die Kopf-Entwicklung bei Amblypygi erbringen die gleichen Resultate wie die beiPardosa hortensis (Pross, 1966). Es gibt keine neuen Gesichtspunkte, die zu einer besseren Kenntnis des Kopf-Problems führen würden.Auf der Basis zahlreicher Querschnitte wird das Coelom und seine Korrelationen zum Gehirn der Arachnida diskutiert.

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Contribution to the discussion of head-segmentation of chelicerta

Summary The critical aspects of Weygoldt's researches about the head development of Amblypygi show the same results like those ofPardosa hortensis (Pross, 1966). There are no new viewpoints, which lead to better knowledge about the headproblems.On the basis of numerous cross-sections the coelomic mesoderme and its connections to the brain of Arachnida is discussed.

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Abkürzungen Ch Chelicere - ChC Cheliceren-Coelom - ChG Cheliceren-Ganglion - Chmes Cheliceren-Mesoderm - CLA Cerebral-Lobus-Anlage - CpA Corpora-pedunculata-Anlage - DcC deutocephales Coelom - Dcmes deutocephales Mesoderm - Lab Labrum - Lbmes labrales Mesoderm - 1LV lateraler Teil des Lateral-Vesikels - LV Lateral-Vesikel - LVA Lateral-Vesikel-Anlage - hlfGr halbmondförmige Grube - Mes Mesoderm - mLV medianer Teil des Lateral-Vesikels - Oes Oesophagus - OLiA Überlippen-Anlage - PcC prosocephales Coelom - PcClb labraler Teil des prosocephalen Coeloms - Pcmes prosocephales Mesoderm - Pd Pedipalpen - PdC Pedipalpen-Coelom - PdG Pedipalpen-Ganglion - Pdmes Pedipalpen-Mesoderm - SMA Sehmassen-Anlage - Stom Stomodaeum - ZK Zentralkörper - ZKA Zentralkörper-Anlage     

Adaptive maternal behavioral plasticity and developmental programming mitigate the transgenerational effects of temperature in dung beetles

Phenotypic plasticity allows organisms to cope with rapid environmental change. Yet exactly when during ontogeny plastic responses are elicited, whether plastic responses produced in one generation influence phenotypic variation and fitness in subsequent generations, and the role of plasticity in shaping population divergences, remains overall poorly understood. Here, we use the dung beetle Onthophagus taurus to assess plastic responses to temperature at several life stages bridging three generations and compare these responses across three recently diverged populations. We find that beetles reared at hotter temperatures grow less than those reared at mild temperatures, and that this attenuated growth has transgenerational consequences by reducing offspring size and survival in subsequent generations. However, we also find evidence that plasticity may mitigate these consequences in two ways: 1) mothers modify the temperature of their offspring's developmental environment via behavioral plasticity and 2) in one population, offspring exhibit accelerated growth when exposed to hot temperatures during very early development (‘developmental programming’). Lastly, our study reveals that offspring responses to temperature diverged among populations in fewer than 100 generations, possibly in response to range‐specific changes in climatic or social conditions.     

Influence of the margin vegetation on the conservation of aphid biological control in apple orchards

The influence of three margin strip treatments (wildflower strips, grass strips and spontaneous vegetation) adjacent to apple orchards on the biological control of Dysaphis plantaginea Passerini (Hemiptera: Aphididae) was compared during two consecutive years. The wildflower strips provided the highest amount of floral resources. Within the margin strips, hoverflies responded positively to higher resource provisioning whereas ladybird abundance did not differ between strip treatments. Within the orchards, the presence of parasitoids, hoverflies, and ladybirds in aphid colonies and the predation of sentinel aphids were not significantly affected by the adjacent strip treatments. The number of natural enemies observed in aphid colonies was mainly driven by aphid number. Aphid numbers were higher close to the margin strips suggesting that aphid colonization from orchard edges may counteract the positive effect of wildflower strips on natural enemy abundance and on a reduction of aphid infestation. The results confirm the positive influence of floral resource provisioning by wildflower strips on the conservation of aphid natural enemies, but also suggest that effects of wildflower strips on aphid regulation inside orchards are not very strong compared with spontaneous vegetation naturally occurring in the margins.     

Recombination Losses Above and Below the Transport Percolation Threshold in Bulk Heterojunction Organic Solar Cells

Achieving the highest power conversion efficiencies in bulk heterojunction organic solar cells requires a morphology that delivers electron and hole percolation pathways for optimized transport, plus sufficient donor:acceptor contact area for near unity charge transfer state formation. This is a significant structural challenge, particularly in semiconducting polymer:fullerene systems. This balancing act in the model high efficiency PTB7:PC70BM blend is studied by tuning the donor:acceptor ratio, with a view to understanding the recombination loss mechanisms above and below the fullerene transport percolation threshold. The internal quantum efficiency is found to be strongly correlated to the slower carrier mobility in agreement with other recent studies. Furthermore, second‐order recombination losses dominate the shape of the current density–voltage curve in efficient blend combinations, where the fullerene phase is percolated. However, below the charge transport percolation threshold, there is an electric‐field dependence of first‐order losses, which includes electric‐field‐dependent photogeneration. In the intermediate regime, the fill factor appears to be limited by both first‐ and second‐order losses. These findings provide additional basic understanding of the interplay between the bulk heterojunction morphology and the order of recombination in organic solar cells. They also shed light on the limitations of widely used transport models below the percolation threshold.     

Studying the effects of heavy metal on chlorophyll and sugar in one year-old seedlings organs of Acer velutinum specie

Pollution is one of the most important factors inhibiting growth in the environment; therefore the effects of zinc pollution were studied in Acer velutinum specie. Two years old seedlings of Acer velutinum specie were prepared from nursery, the concentrations of zero and one hundred and thirty mg per liter of zinc chloride solution were added to the soil of seedlings pots after calculating and after passing a three-month period of seedling growth, the plant organs were removed, then the amount of zinc concentration in the samples was determined and data were analyzed. The results of the analysis showed that the highest amount of accumulation on the stem, root and soil in treatment concentrations is 87.75, 65.68 and 24.78 mg per kg and accumulation of zinc in total chlorophyll and sugar in treatment concentrations is 4.61 and 0.6028 mg per g, respectively, and accordingly Acer velutinum specie is suitable for refinement of soils contaminated with zinc.     

Linking chloroplast relocation to different responses of photosynthesis to blue and red radiation in low and high light-acclimated leaves of <Emphasis Type="Italic">Arabidopsis thaliana</Emphasis> (L.)

Low light (LL) and high light (HL)-acclimated plants of A. thaliana were exposed to blue (BB) or red (RR) light or to a mixture of blue and red light (BR) of incrementally increasing intensities. The light response of photosystem II was measured by pulse amplitude-modulated chlorophyll fluorescence and that of photosystem I by near infrared difference spectroscopy. The LL but not HL leaves exhibited blue light-specific responses which were assigned to relocation of chloroplasts from the dark to the light-avoidance arrangement. Blue light (BB and BR) decreased the minimum fluorescence (\(F_{0}^{\prime }\)) more than RR light. This extra reduction of the \(F_{0}^{\prime }\) was stronger than theoretically predicted for \(F_{0}^{\prime }\) quenching by energy dissipation but actual measurement and theory agreed in RR treatments. The extra \(F_{0}^{\prime }\) reduction was assigned to decreased light absorption of chloroplasts in the avoidance position. A maximum reduction of 30% was calculated. Increasing intensities of blue light affected the fluorescence parameters NPQ and q_P to a lesser degree than red light. After correcting for the optical effects of chloroplast relocation, the NPQ responded similarly to blue and red light. The same correction method diminished the color-specific variations in q_P but did not abolish it; thus strongly indicating the presence of another blue light effect which also moderates excitation pressure in PSII but cannot be ascribed to absorption variations. Only after RR exposure, a post-illumination overshoot of \(F_{0}^{\prime }\) and fast oxidation of PSI electron acceptors occurred, thus, suggesting an electron flow from stromal reductants to the plastoquinone pool.     

Assembly and Intracellular Targeting of the βγ Subunits of Heterotrimeric G Proteins

The assembly in living cells of heterotrimeric guanine nucleotide binding proteins from their constituent α, β, and γ subunits is a complex process, compounded by the multiplicity of the genes that encode them, and the diversity of receptors and effectors with which they interact. Monoclonal anti-β antibodies (ARC5 and ARC9), raised against immunoaffinity purified βγ complexes, recognize β subunits when not associated with γ and can thus be used to monitor assembly of βγ complexes. Complex formation starts immediately after synthesis and is complete within 30 min. Assembly occurs predominantly in the cytosol, and association of βγ complexes with the plasma membrane fraction starts between 15–30 min of chase. Three pools of β subunits can be distinguished based on their association with γ subunits, their localization, and their detergent solubility. Association of β and α subunits with detergent-insoluble domains occurs within 1 min of chase, and increases to reach a plateau of near complete detergent resistance within 30 min of chase. Brefeldin A treatment does not interfere with delivery of βγ subunits to detergent-insoluble domains, suggesting that assembly of G protein subunits with their receptors occurs distally from the BFA-imposed block of intracellular membrane trafficking and may occur directly at the plasma membrane.