Pectins from the albedo of immature lemon fruitlets have high water binding capacity

The white part of citrus peel, the albedo, has a special role in water relations of both fruit and leaves from early on in fruit development. In times of drought, this tissue acts as a water reservoir for juice sacs, seeds and leaves. When water was injected into the albedo, free water was undetectable using magnetic resonance imaging. Microscopy showed tightly packed cells with little intercellular space, and thick cell walls. Cell wall material comprised 21% of the fresh albedo weight, and contained 26.1% galacturonic acid, the main constituent of pectin. From this, we postulated that pectin of the cell wall was responsible for the high water-binding capacity of the immature lemon albedo. Cell wall material was extracted using mild procedures that keep polymers intact, and four pectic fractions were recovered. Of these fractions, the SDS and chelator-soluble fractions showed viscosities ten and twenty times higher than laboratory-grade citrus pectin or the other albedo-derived pectins. The yield of these two pectins represented 28% of the cell walls and 62% of the galacturonic acid content of immature lemon albedo. We concluded that, from viscosity and abundance, these types of pectin account for the high water-binding capacity of this tissue. Compositional analyses showed that the two highly viscous pectic fractions differ in galacturonic acid content, degree of branching and length of side chains from the less viscous albedo-derived pectins. The most striking feature of these highly viscous pectins, however, was their high molecular weight distribution compared to the other pectic fractions.     

Magnetic orientation and magnetoreception in birds and other animals

Animals use the geomagnetic field in many ways: the magnetic vector provides a compass; magnetic intensity and/or inclination play a role as a component of the navigational map, and magnetic conditions of certain regions act as sign posts or triggers, eliciting specific responses. A magnetic compass is widespread among animals, magnetic navigation is indicated e.g. in birds, marine turtles and spiny lobsters and the use of magnetic sign posts has been described for birds and marine turtles. For magnetoreception, two hypotheses are currently discussed, one proposing a chemical compass based on a radical pair mechanism, the other postulating processes involving magnetite particles. The available evidence suggests that birds use both mechanisms, with the radical pair mechanism in the right eye providing directional information and a magnetite-based mechanism in the upper beak providing information on position as component of the map. Behavioral data from other animals indicate a light-dependent compass probably based on a radical pair mechanism in amphibians and a possibly magnetite-based mechanism in mammals. Histological and electrophysiological data suggest a magnetite-based mechanism in the nasal cavities of salmonid fish. Little is known about the parts of the brain where the respective information is processed.     

Trs85 (Gsg1), a component of the TRAPP complexes, is required for the organization of the preautophagosomal structure during selective autophagy via the Cvt pathway

Autophagosomes and Cvt vesicles are limited by two membrane layers. The biogenesis of these unconventional vesicles and the origin of their membranes are hardly understood. Here we identify in Saccharomyces cerevisiae Trs85, a nonessential component of the TRAPP complexes, to be required for the biogenesis of Cvt vesicles. The TRAPP complexes function in endoplasmic reticulum-to-Golgi and Golgi trafficking. Growing trs85delta cells show a defect in the organization of the preautophagosomal structure. Although proaminopeptidase I is normally recruited to the preautophagosomal structure, the recruitment of green fluorescent protein-Atg8 depends on Trs85. Autophagy proceeds in the absence of Trs85, albeit at a reduced rate. Our electron microscopic analysis demonstrated that the reduced autophagic rate of trs85delta cells does not result from a reduced size of the autophagosomes. Growing and starved cells lacking Trs85 did not show defects in vacuolar biogenesis; mature vacuolar proteinase B and carboxypeptidase Y were present. Also vacuolar acidification was normal in these cells. It is known that mutations impairing the integrity of the ER or Golgi block both autophagy and the Cvt pathway. But the phenotypes of trs85delta cells show striking differences to those seen in mutants with defects in the early secretory pathway. This suggests that Trs85 might play a direct role in the Cvt pathway and autophagy.     

Risk factors for bacterial catheter colonization in regional anaesthesia

BACKGROUND: Although several potential risk factors have been discussed, risk factors associated with bacterial colonization or even infection of catheters used for regional anaesthesia are not very well investigated. METHODS: In this prospective observational trial, 198 catheters at several anatomical sites where placed using a standardized technique. The site of insertion was then monitored daily for signs of infection (secretion at the insertion site, redness, swelling, or local pain). The catheters were removed when clinically indicated (no or moderate postoperative pain) or when signs of potential infection occurred. After sterile removal they were prospectively analyzed for colonization, defined as > 15 colony forming units. RESULTS: 33 (16.7%) of all catheters were colonized, and 18 (9.1%) of these with additional signs of local inflammation. Two of these patients required antibiotic treatment due to superficial infections. Stepwise logistic regression analysis was used to identify factors associated with catheter colonization. Out of 26 potential factors, three came out as statistically significant. Catheter placement in the groin (odds-ratio and 95%-confidence interval: 3.4; 1.5-7.8), and repeated changing of the catheter dressing (odds-ratio: 2.1; 1.4-3.3 per removal) increased the risk for colonization, whereas systemic antibiotics administered postoperatively decreased it (odds ratio: 0.41; 0.12-1.0). CONCLUSION: Colonization of peripheral and epidural nerve catheter can only in part be predicted at the time of catheter insertion since two out of three relevant variables that significantly influence the risk can only be recorded postoperatively. Catheter localisation in the groin, removal of the dressing and omission of postoperative antibiotics were associated with, but were not necessarily causal for bacterial colonization. These factors might help to identify patients who are at increased risk for catheter colonization.     

Chronic hypoxia decreases K(V) channel expression and function in pulmonary artery myocytes

Activity of voltage-gated K+ (KV) channels regulates membrane potential (E(m)) and cytosolic free Ca2+ concentration ([Ca2+](cyt)). A rise in ([Ca2+](cyt))in pulmonary artery (PA) smooth muscle cells (SMCs) triggers pulmonary vasoconstriction and stimulates PASMC proliferation. Chronic hypoxia (PO(2) 30-35 mmHg for 60-72 h) decreased mRNA expression of KV channel alpha-subunits (Kv1.1, Kv1.5, Kv2.1, Kv4.3, and Kv9.3) in PASMCs but not in mesenteric artery (MA) SMCs. Consistently, chronic hypoxia attenuated protein expression of Kv1.1, Kv1.5, and Kv2.1; reduced KV current [I(KV)]; caused E(m) depolarization; and increased ([Ca2+](cyt)) in PASMCs but negligibly affected KV channel expression, increased I(KV), and induced hyperpolarization in MASMCs. These results demonstrate that chronic hypoxia selectively downregulates KV channel expression, reduces I(KV), and induces E(m) depolarization in PASMCs. The subsequent rise in ([Ca2+](cyt)) plays a critical role in the development of pulmonary vasoconstriction and medial hypertrophy. The divergent effects of hypoxia on KV channel alpha-subunit mRNA expression in PASMCs and MASMCs may result from different mechanisms involved in the regulation of KV channel gene expression.     

Temporal fluctuations of the geomagnetic field affect pigeons’ entire homing flight

Tracks of pigeons, recorded with the help of GPS-receivers from two sites 30 km north and south of the Frankfurt loft, were analyzed in view of an influence of irregular fluctuations of the geomagnetic field. The data obtained were correlated with indices characterizing different aspects of these fluctuations. We found the best correlations with the index quantifying the average amplitude of the magnetic disturbance, and with an index that quantifies the average variability of the magnetic field on the day of release: stronger and more variable fluctuations lead to a counter-clockwise shift of the mean headings during the initial phase at the release site and the following departure phase, but not during the final homing phase leading to the loft. The steadiness of flight was not affected during the initial phase; however, during the later parts of the homing flight, stronger fluctuations, as well as higher variability in the magnetic field led to a marked decrease in steadiness. This continuing effect of magnetic fluctuations indicates that magnetic factors not only affect the beginning, but remain an integral part of the pigeons’ navigational processes during the entire homing flight.     

Cross-Sectional Study on Antibiotic Usage in Pigs in Germany

To be able to analyze the relationship between the level of resistance and the use of antimicrobials, it is necessary to collect detailed data on antimicrobial usage. For this reason, data on antimicrobial use on 495 pig farms from entire Germany were collected and analyzed. In Germany, each application and dispensing of medicines to food-producing animals is documented in detail obligatorily by the veterinarian. This information was collected retrospectively for the year 2011. The analyses undertook separate examinations on the age groups sow, piglet, weaner and fattening pig; both the route of administration and indication per active ingredient, and active ingredient class, were evaluated. In total, 20,374 kg of antimicrobial substances were used in the study population. Tetracyclines were used in highest amounts, followed by beta-lactams, trimethoprim-sulfonamides and macrolides. Concerning the frequency of using an active substance per animal, polypeptides were most commonly administered. In all age groups, respiratory infections were the main indication for using antimicrobials, followed by intestinal diseases in piglets, weaners and fattening pigs and diseases of reproductive organs in sows. Over a period of 100 days, the median number of treatment days with one antimicrobial substance for piglets was 15 days, for weaners about 6 days, for fattening pigs about 4 days and for sows about 1 day. A multifactorial ANOVA was conducted to investigate which factors are associated with the treatment frequency. The factors “veterinarian” and “age group” were related to the treatment frequency, just as the interaction between “veterinarian” and “farm size” as well as the interaction between “veterinarian” and “age group”.     

The role of Müller glia and microglia in glaucoma

Cells of Müller glia and microglia react to neuronal injury in glaucoma. The change to a reactive phenotype initiates signaling cascades that may serve a neuroprotective role, but may also proceed to promote damaging effects on retinal neurons. Both effects appear to occur most likely in parallel in glaucoma, but the underlying mechanisms and signaling pathways that specifically promote protective versus destructive roles of reactive glial cells are mostly unclear. More research is needed to understand the homeostatic signaling network in which retinal glia cells are embedded to maintain or restore neuronal function after injury.