Einschlußkörper in den Epidermiszellen vonChlorophytum comosum

Zusammenfassung Iu den Epidermiszelien vonChlorophytum cornosum (und auchChlorophytum elatum) kommen in den Vakuolen Kristalldrusen vor. deren chemische Natur noch nicht eindeutig festgestellt werden konnte. Da neben den Drusen auch noch lebhaft bewegliche Cytoplasmaballen. die als x-Bodies angesehen werden und auch fibrilläre Eiweißspindeln beobachtet wurden, wird angenommen, daß die erwähnten Kristalldrusen ebenfalls Stoffwechselprodukte virusinfizierter Zellen sind. Auch polsterartige Kallosebildungen an den Zellwänden dieser Zellen sowie die Übertragbarkeit durch Einreihen von Preßsaft verstärken die Vermutung, daß alle diese Inhaltskörper als Folge einer Virusinfektion in den Zellen entstanden sind.Dem Andenken meines unvergeßlichen Lehrers Professor Friedl Weber gewidmet.     

Increase in β-1,4-Galactosyltransferase Activity During PC12 Cell Differentiation Induced by Forskolin and 2-Chloroadenosine

Galactosyltransferase (GALTase) activity was measured in differentiating PC12 cells induced by either forskolin or 2-chloroadenosine. The specific activity of GALTase in whole cells and isolated Golgi membranes increased as early as 3 h after initiating treatment with 2-chloroadenosine, and maximal activity was reached at approximately 12 h. In two mutant PC12 cell lines deficient in protein kinase A, both forskolin and 2-chloroadenosine failed to increase GALTase activity. The adenosine A2 receptor antagonist, xanthine amine congener, prevented 2-chloroadenosine stimulation of GALTase, demonstrating that this adenosine derivative was mediating its effect via the A2 receptor. These data suggest that GALTase activity during PC12 cell differentiation is regulated by cyclic AMP (cAMP)- and protein kinase A-dependent processes. In support of the role of cAMP in regulating GALTase activity were studies with murine PC carcinoma cells demonstrating that the greatest stimulation of GALTase activity occurred with cells treated with both retinoic acid and dibutyryl cAMP.     

A computer-based simulation of childbirth using the partial Dirichlet–Neumann contact method with total Lagrangian explicit dynamics on the GPU

During physiological or ‘natural’ childbirth, the fetal head follows a distinct motion pattern—often referred to as the cardinal movements or ‘mechanisms’ of childbirth—due to the biomechanical interaction between the fetus and maternal pelvic anatomy. The research presented in this paper introduces a virtual reality-based simulation of physiological childbirth. The underpinning science is based on two numerical algorithms including the total Lagrangian explicit dynamics method to calculate soft tissue deformation and the partial Dirichlet–Neumann contact method to calculate the mechanical contact interaction between the fetal head and maternal pelvic anatomy. The paper describes the underlying mathematics and algorithms of the solution and their combination into a computer-based implementation. The experimental section covers first a number of validation experiments on simple contact mechanical problems which is followed by the main experiment of running a virtual reality childbirth. Realistic mesh models of the fetus, bony pelvis and pelvic floor muscles were subjected to the intra-uterine expulsion forces which aim to propel the virtual fetus through the virtual birth canal. Following a series of simulations, taking variations in the shape and size of the geometric models into account, we consistently observed the cardinal movements in the simulator just as they happen in physiological childbirth. The results confirm the potential of the simulator as a predictive tool for problematic childbirths subject to patient-specific adaptations.

     

Genotype-by-Diet Interactions Drive Metabolic Phenotype Variation in Drosophila melanogaster

The rising prevalence of complex disease suggests that alterations to the human environment are increasing the proportion of individuals who exceed a threshold of liability. This might be due either to a global shift in the population mean of underlying contributing traits, or to increased variance of such underlying endophenotypes (such as body weight). To contrast these quantitative genetic mechanisms with respect to weight gain, we have quantified the effect of dietary perturbation on metabolic traits in 146 inbred lines of Drosophila melanogaster and show that genotype-by-diet interactions are pervasive. For several metabolic traits, genotype-by-diet interactions account for far more variance (between 12 and 17%) than diet alone (1–2%), and in some cases have as large an effect as genetics alone (11–23%). Substantial dew point effects were also observed. Larval foraging behavior was found to be a quantitative trait exhibiting significant genetic variation for path length (P = 0.0004). Metabolic and fitness traits exhibited a complex correlation structure, and there was evidence of selection minimizing weight under laboratory conditions. In addition, a high fat diet significantly increases population variance in metabolic phenotypes, suggesting decreased robustness in the face of dietary perturbation. Changes in metabolic trait mean and variance in response to diet indicates that shifts in both population mean and variance in underlying traits could contribute to increases in complex disease.METABOLIC syndrome (MetS) is a complex disease that is promoted by interactions between genetic and environmental effects (O''Rahilly and Farooqi 2006), and seems to be increasing in prevalence in response to a transition from traditional toward Westernized lifestyles (Lee et al. 2004; Schulz et al. 2006). MetS is a constellation of metabolic symptoms including insulin resistance, abdominal obesity, and dyslipidemia, and is predictive of cardiovascular disease and type-2 diabetes (Alberti et al. 2006). The condition has reached epidemic proportions in many Westernized countries (Isomaa et al. 2001; Ford and Giles 2003; Lorenzo et al. 2003; Alberti et al. 2006). Not all individuals are susceptible to the deleterious effects of a Westernized lifestyle, but some individuals are very sensitive to the effects of their environment (Schulz et al. 2006).We argued previously that environmental perturbation contributes to the recent increases in chronic disease in Westernized societies by exposing cryptic genetic variation, a phenomenon that may be particularly evident in metabolic syndrome (Gibson 2009). Increases in complex disease after an environmental shift can be caused by both a change in the population mean or increased variance in a predisposing underlying trait, or endophenotype, causing a larger portion of the population to exceed a disease threshold (Gibson and Reed 2008). Endophenotypes can be molecular, such as rate of uptake of glucose into cells, but also include visible disease covariates, such as body mass. The transition from traditional diets and lifestyles may have perturbed our metabolic homeostasis, thereby promoting increased susceptibility to, and in turn prevalence of, obesity, hyperlipidemia, diabetes, and cardiovascular illness.The complexity of genetic and environmental interactions leads to major challenges in successful disease treatment and prevention strategies, in that it is very difficult to accurately model the relative contributions of nature and nurture to disease susceptibility in a human population. Dietary factors have been demonstrated to interact with specific genetic variants to increase the risk of metabolic disease in humans (Corella and Ordovas 2005; Ordovas 2006; Corella et al. 2009; Warodomwichit et al. 2009), but the relative contribution of overall genotype and environmental effects on human variation is difficult to determine. Modeling population level genotype-by-environment interactions using a model organism like Drosophila can compensate for the research challenges of parameter estimation in human populations.Drosophila share great homology to humans in a number of systems including central metabolism, insulin-signaling pathways, and organs responsible for physiological homoeostasis (e.g., heart, liver, and kidney) (Rizki 1978; Bodmer 1995; Nation 2002; Rulifson et al. 2002; Denholm et al. 2003; Wessells et al. 2004). It has been shown that Drosophila with ablated insulin-producing neurons have elevated hemolymph trehalose levels, considered to parallel a diabetic phenotype (Rulifson et al. 2002). Loss of insulin signaling also restores normal rhythmicity of adult heart rate in old flies (Wessells et al. 2004), providing a link between the obesity and cardiac components of MetS. We have used 146 natural genetic isolates of Drosophila melanogaster to model the relative contributions of genetics, diet, and other environmental effects on the MetS-like phenotypes of larval weight gain, blood sugar concentration, lipid storage, and survival. Individuals from each of these genetic lines were raised on four different diets: their normal lab food, a calorie restricted (0.75% glucose) food, a high (4%) glucose food, and a high fat diet containing (3%) coconut oil.Using this approach, we sought evidence pertaining to two major hypotheses. There are six general types of phenotypic reaction scenarios that a genetically variable population can exhibit in response to an environmental transition: (1) no phenotypic variation in response to genetic or environmental factors, (2) genetic variation in mean phenotype but no change across environments, (3) an additive change in phenotypic mean across genotypes between environments, (4) an interaction effect between genetic and environment leading to a crossing of line means, and (5) a decrease or (6) an increase in variance in the new environment (Gibson and Vanhelden 1997). First, we considered whether the predominant source of metabolic variation within a Drosophila population is genetic, environmental, or the interaction between genetic and environmental effects. Our null was that none of these factors significantly influence weight gain or other phenotypes (scenario 1 above), but it was expected that genetic variation would be prevalent. The more fundamental issue is which of two alternate hypotheses apply: that dietary effects are essentially additive across genotypes (3) or that they are largely genotype dependent (4), possibly also with contributions of behavior and the external environment. Second, we considered whether the transition from a standard laboratory diet to a perturbing diet would change the environmental and/or genetic variance observed in the population: a decrease (5) indicating physiological limitation to the variation or an increase (6) indicating decanalization of the metabolic phenotypes due to loss of physiological buffering.     

Stomata-Anomalie vonOpuntia-Virusträgern

Zusammenfassung Die Spaltöffnungsapparate von Kakteen (Opuntia. Epiphyllum, Rhipsalis), die in den Epidermiszellen Eiweißspindeln enthalten, degenerieren häufig oder weisen eine abnorme Entwicklung auf. So kommen bei den Blättern vonOpuntia subulata zahlreiche Zwillingsspaltöffnungen vor, die aus einer Mutterzelle hervorgehen (eineiige Zwillinge). Die Eiweißspindeln werden als Virus-Körper aufgefaßt und es wird vermutet, daß die gehäufte Bildung der abnormen Stomata mit der Virusinfektion zusammenhängt, obwohl die Schließzellen der Kakteen keine Virus-Einschlußkörper enthalten. Die Abnormitäten und Verkümmerungen des Spaltöffnungsapparates wären demnach ein mikroskopisch sichtbares Symptom an äußerlich symptomlosen Virusträgern.     

Frequency dependence of respiratory system mechanics during induced constriction in a murine model of asthma.

Airway dysfunction in asthma is characterized by hyperresponsiveness, heterogeneously narrowed airways, and closure of airways. To test the hypothesis that airway constriction in ovalbumin (OVA)-sensitized OVA-intranasally challenged (OVA/OVA) mice produces mechanical responses that are similar to those reported in asthmatic subjects, respiratory system resistance (Rrs) and elastance (Edyn,rs) spectra were obtained in OVA/OVA and control mice during intravenous methacholine (MCh) infusions. In control mice, MCh at 1,700 microg x kg(-1) x min(-1) produced 1) a 495 and 928% increase of Rrs at 0.5 Hz and 19.75 Hz, respectively, 2) a 33% rise in Edyn,rs at 0.5 Hz, and 3) a mild frequency (f)-dependent increase of Edyn,rs. The same MCh dose in OVA/OVA mice produced 1) elevations of Rrs at 0.5 Hz and 19.75 Hz of 1,792 and 774%, respectively, 2) a 390% rise in Edyn,rs at 0.5 Hz, and 3) marked f-dependent increases of Edyn,rs. During constriction, the f dependence of mechanics in control mice was consistent with homogeneous airway narrowing; however, in OVA/OVA mice, f dependence was characteristic of heterogeneously narrowed airways, closure of airways, and airway shunting. These mechanisms amplify the pulmonary mechanical responses to constrictor stimuli at physiological breathing rates and have important roles in the pathophysiology of human asthma.     

Rasche Vakuolen-Kontraktion inCerinthe-Blütenzellen

Zusammenfassung Die Vakuolen der Epidermiszellen der rot gefärbten Zone der Blütenkrone vonCerinthe major kontrahieren sich auf Zusatz von Säuren (p _H 1) blitzartig; auf Zusatz von Alkalien dehnen sich die Vakuolen wieder rasch aus. Dieses Phänomen wird verglichen mit muskelähnlichen Kontraktionen und Dilatationen, die Kuhn an künstlichen Netzwerken aus polyvalenten Fadenmolekülen erzielt hat, wenn ihre Ionisation durch Zusatz von Säuren und Alkalien verändert wird. Es wird vermutet, daß Pektinstoffe (Pektinsäuren), die nach Hofmeister einen wesentlichen Bestandteil des Zellsaftes der Boraginaceen darstellen, für den Vorgang der raschen Kontraktion der Vakuolen verantwortlich sind.     

Sphärit-Bildung ausCirsium-Zellsaft

Zusammenfassung In den Epidermiszellen des Laubblattes vonCirsium arvense können in der Vakuole Sphärite entstehen. Sie bilden sich, nachdem vorher im Zellsaft durch Entmischung Koazervattropfen auftreten. Die Entmischung des Zellsaftes erfolgt in den Epidermiszellen kranker Blätter von selbst, in denen gesunder Blätter erst bei Alteration verschiedener Art.DieCirsium-Sphärite sind doppelbrechend und zeigen eine intensive rote Eigenfluoreszenz. Mit Akridinorange vital fluorochromiert, fluoresziert der Zellsaft im sauren Bereich intensiv grün, die Koazervattropfen sowie die Sphärite dagegen fluoreszieren leuchtend rot.Die chemische Natur der Sphärite steht noch nicht fest, möglicherweise sind es hesperidinähnliche Stoffe.In plasmolysierten Parenchymzellen derDahlia-Knolle wandelt sich der ganze inulinreiche Tonoplast in situ in eine Sphäritkugel um, und zwar erst post mortem des Protoplasten.     

Eiweißkristalle in den Zellkernen der Drüsenhaare vonSaintpaulia

Zusammenfassung Die Zellkerne der Köpfchenzellen der kurzen Drüsenhaare vonSaintpaulia ionantha enthalten Proteinkristalloide, in anderen Zellen dieser Pflanze wurden Kernkristalloide nicht gefunden.