Die Morphologie der Schleimsekretion im Fruchtknoten vonAptenia cordifolia

Zusammenfassung Der Fruchtknoten vonAptenia cordifolia enthÄlt wÄhrend der Samenentwicklung einen proteinreichen Polysaccharidschleim. Verschieden alte schleimproduzierende Placentarpapillen werden einer elektronenmikroskopischen Analyse unterzogen. Kurz vor dem Einsetzen der Schleimproduktion ist das rauhe ER noch spÄrlich entwickelt. Der Golgi-Apparat ist unauffÄllig und wenig aktiv. Zu Beginn der Schleimbildung sind als hauptsÄchliche Strukturkomponenten hypersekretorische Dictyosomen und ER-umschlossene Vakuolen (storage vesicles) zu beobachten. Es wird angenommen, da\ diese Komplexe aus rauhem ER und vermutlich mitèinander verschmolzenen Golgi-Vesikeln die charakteristischen Synthese-Einheiten für den Polysaccharid-Protein-Schleim darstellen, da sie nachweislich neben Polysacchariden auch Proteine enthalten. Membranfusionen zwischen Vesikeln und dem Plasmalemma deuten auf Exocytose-Prozesse unter Beteiligung des Golgi-Apparates hin. Daneben wird eine holocrine Ausscheidung des in den storage vesicles zunÄchst gespeicherten Polysaccharid-Protein-Schleimes bei Degeneration des Protoplasten vermutet.

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Morphology of slime secretion in the seed vessels ofAptenia cordifolia

Summary During seed development the gynaeceum ofAptenia cordifolia produces a mucilage rich in carbohydrates and protein. The mucilage-producing placentary papillae are analyzed in different developmental stages by electron microscopy. Just before mucilage production is started, the rough ER occurs but sparsely. At that time the dictyosomes are inconspicuous and of low activity. When mucilage production commences, one can observe hypersecretory dictyosomes and ER-ensheathed vacuoles (storage vesicles) as the main structural components. It is suggested that the complexes of rough ER and probably fused Golgi vesicles are the synthetizing units of the carbohydrate protein mucilage, since in these complexes both components can be identified cytochemically. Fusion sites of plasmalemma and vesicles indicate processes of exocytosis-probably involving the Golgi apparatus. In addition, a holocrine excretion of the mucilage initially enclosed in the storage vesicles via degeneration of the protoplast is assumed.

     

Diagnosis and Treatment of Amanita Phalloides-Type Mushroom Poisoning: Use of Thioctic Acid

The number of cases of mushroom poisoning is increasing as a result of the increasing popularity of “wild” mushroom consumption. Amanitin and phalloidin cytotoxins found in some Amanita and Galerina species produce the most severe and frequent life-threatening symptoms of Amanita phalloidestype poisoning. Delay in onset of symptoms, individual susceptibility variation and lack of rapid and reliable identification have contributed to the significant morbidity and mortality of this type of poisoning.A rapid chromatographic assay for identifying the potent cytotoxins and apparently successful management using thioctic acid of two cases of A. phalloides-type mushroom poisoning are reported. All known cases of A. phalloides-type mushroom poisoning treated with thioctic acid in the United States are summarized.     

Populations- und syn?kologische Modelle in der Ornithologie

Ohne Zusammenfassung

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Population models and synecological models in ornithology

     

Functional analysis of phosphorylation of the mitotic centromere-associated kinesin by Aurora B kinase in human tumor cells

Mitotic centromere-associated kinesin (MCAK) is the best characterized member of the kinesin-13 family and plays important roles in microtubule dynamics during mitosis. Its activity and subcellular localization is tightly regulated by an orchestra of mitotic kinases, such as Aurora B. It is well known that serine 196 of MCAK is the major phosphorylation site of Aurora B in Xenopus leavis extracts and that this phosphorylation regulates its catalytic activity and subcellular localization. In the current study, we have addressed the conserved phosphorylation site serine 192 in human MCAK to characterize its function in more depth in human cancer cells. Our data confirm that S192 is the major phosphorylation site of Aurora B in human MCAK and that this phosphorylation has crucial roles in regulating its catalytic activity and localization at the kinetochore/centromere region in mitosis. Interfering with this phosphorylation leads to a delayed progression through prometa- and metaphase associated with mitotic defects in chromosome alignment and segregation. We show further that MCAK is involved in directional migration and invasion of tumor cells, and interestingly, interference with the S192 phosphorylation affects this capability of MCAK. These data provide the first molecular explanation for clinical observation, where an overexpression of MCAK was associated with lymphatic invasion and lymph node metastasis in gastric and colorectal cancer patients.     

Review: Helicobacter pylori infection in children

Helicobacter pylori infection in children and adolescents differs in comparison to adults with respect to epidemiology, host responses, and disease manifestations. Furthermore, treatment options are limited in this population and antibiotic resistance rates continue to increase. Therefore, ongoing research is vital to understand disease pathogenesis and provide optimal management of children with infection. This review summarizes relevant publications from April 2019 to March 2020. Similar to adults, recent studies show a decreasing prevalence of infection in the pediatric population. Studies of pathogenesis investigated serum immune responses and the potential inverse association of infection and allergy. Several studies investigated the effect of H pylori and related inflammation on the gut microbiome. The recommendation of endoscopy‐based testing to identify the cause of symptoms and not just H pylori, reserving noninvasive UBT or stool antigen tests for post‐eradication follow‐up, was supported by the current literature.     

Sunshine versus gold: The effect of population age on genetic structure of an invasive mosquito

The genetic diversity and structure of invasive species are affected by the time since invasion, but it is not well understood how. We compare likely the oldest populations of Aedes aegypti in continental North America with some of the newest to illuminate the range of genetic diversity and structure that can be found within the invasive range of this important disease vector. Aedes aegypti populations in Florida have probably persisted since the 1600‐1700s, while populations in southern California derive from new invasions that occurred in the last 10 years. For this comparison, we genotyped 1,193 individuals from 28 sites at 12 highly variable microsatellites and a subset of these individuals at 23,961 single nucleotide polymorphisms (SNPs). This is the largest sample analyzed for genetic structure for either region, and it doubles the number of southern California populations previously analyzed. As predicted, the older populations (Florida) showed fewer indicators of recent founder effect and bottlenecks; in particular, these populations have dramatically higher genetic diversity and lower genetic structure. Geographic distance and driving distance were not good predictors of genetic distance in either region, especially southern California. Additionally, southern California had higher levels of genetic differentiation than any comparably sized documented region throughout the worldwide distribution of the species. Although population age and demographic history are likely driving these differences, differences in climate and transportation practices could also play a role.     

Canadian polar bear population structure using genome‐wide markers

Predicting the consequences of environmental changes, including human‐mediated climate change on species, requires that we quantify range‐wide patterns of genetic diversity and identify the ecological, environmental, and historical factors that have contributed to it. Here, we generate baseline data on polar bear population structure across most Canadian subpopulations (n = 358) using 13,488 genome‐wide single nucleotide polymorphisms (SNPs) identified with double‐digest restriction site‐associated DNA sequencing (ddRAD). Our ddRAD dataset showed three genetic clusters in the sampled Canadian range, congruent with previous studies based on microsatellites across the same regions; however, due to a lack of sampling in Norwegian Bay, we were unable to confirm the existence of a unique cluster in that subpopulation. These data on the genetic structure of polar bears using SNPs provide a detailed baseline against which future shifts in population structure can be assessed, and opportunities to develop new noninvasive tools for monitoring polar bears across their range.     

Effects of an anthropogenic diet on indicators of physiological challenge and immunity of white ibis nestlings raised in captivity

When wildlife forage and/or live in urban habitats, they often experience a shift in resource availability and dietary quality. Some species even use human handouts, such as bread, as well as human refuse, as a large part of their new diets; yet the influences of this nutritional shift on health and survival remain unclear. American white ibises are increasingly being seen in urban areas in Florida; they collect handouts, such as bread and other food items, from humans in parks, and are also found foraging on anthropogenic sources in trash heaps. We hypothesized that the consumption of these new anthropogenic food sources may trigger increases in indicators of physiological challenge and dampen immune responses. We tested this experimentally by raising 20 white ibis nestlings in captivity, and exposing 10 to a simulated anthropogenic diet (including the addition of white bread and a reduction in seafood content) while maintaining 10 on a diet similar to what ibises consume in more natural environments. We then tested two indicators of physiological challenge (corticosterone and heat shock protein 70), assessed innate immunity in these birds via bactericidal assays and an in vitro carbon clearance assay, and adaptive immunity using a phytohemagglutinin skin test. The anthropogenic diet depressed the development of the ability to kill Salmonella paratyphi in culture. Our results suggest that consuming an anthropogenic diet may be detrimental in terms of the ability to battle a pathogenic bacterial species, but there was little effect on indicators of physiological challenge and other immunological measures.     

Intraspecific trait variation influences physiological performance and fitness in the South Africa shrub genus Protea (Proteaceae)

Background and AimsGlobal plant trait datasets commonly identify trait relationships that are interpreted to reflect fundamental trade-offs associated with plant strategies, but often these trait relationships are not identified when evaluating them at smaller taxonomic and spatial scales. In this study we evaluate trait relationships measured on individual plants for five widespread Protea species in South Africa to determine whether broad-scale patterns of structural trait (e.g. leaf area) and physiological trait (e.g. photosynthetic rates) relationships can be detected within natural populations, and if these traits are themselves related to plant fitness.MethodsWe evaluated the variance structure (i.e. the proportional intraspecific trait variation relative to among-species variation) for nine structural traits and six physiological traits measured in wild populations. We used a multivariate path model to evaluate the relationships between structural traits and physiological traits, and the relationship between these traits and plant size and reproductive effort.Key ResultsWhile intraspecific trait variation is relatively low for structural traits, it accounts for between 50 and 100 % of the variation in physiological traits. Furthermore, we identified few trait associations between any one structural trait and physiological trait, but multivariate regressions revealed clear associations between combinations of structural traits and physiological performance (R² = 0.37–0.64), and almost all traits had detectable associations with plant fitness.ConclusionsIntraspecific variation in structural traits leads to predictable differences in individual-level physiological performance in a multivariate framework, even though the relationship of any particular structural trait to physiological performance may be weak or undetectable. Furthermore, intraspecific variation in both structural and physiological traits leads to differences in plant size and fitness. These results demonstrate the importance of considering measurements of multivariate phenotypes on individual plants when evaluating trait relationships and how trait variation influences predictions of ecological and evolutionary outcomes.