Systematic Functional Analysis of Bicaudal-D Serine Phosphorylation and Intragenic Suppression of a Female Sterile Allele of BicD

Protein phosphorylation is involved in posttranslational control of essentially all biological processes. Using mass spectrometry, recent analyses of whole phosphoproteomes led to the identification of numerous new phosphorylation sites. However, the function of most of these sites remained unknown. We chose the Drosophila Bicaudal-D protein to estimate the importance of individual phosphorylation events. Being involved in different cellular processes, BicD is required for oocyte determination, for RNA transport during oogenesis and embryogenesis, and for photoreceptor nuclei migration in the developing eye. The numerous roles of BicD and the available evidence for functional importance of BicD phosphorylation led us to identify eight phosphorylation sites of BicD, and we tested a total of 14 identified and suspected phosphoserine residues for their functional importance in vivo in flies. Surprisingly, all these serines turned out to be dispensable for providing sufficient basal BicD activity for normal growth and development. However, in a genetically sensitized background where the BicDA40V protein variant provides only partial activity, serine 103 substitutions are not neutral anymore, but show surprising differences. The S103D substitution completely inactivates the protein, whereas S103A behaves neutral, and the S103F substitution, isolated in a genetic screen, restores BicDA40V function. Our results suggest that many BicD phosphorylation events may either be fortuitous or play a modulating function as shown for Ser103. Remarkably, amongst the Drosophila serines we found phosphorylated, Ser103 is the only one that is fully conserved in mammalian BicD

Detection of the antibacterial activity of chitosan

Using three bacterial strains the antibacterial activity of Chitoskin®, a chitosan-containing wound-dressing, was investigated by determining the viable bacterial cell count in liquid cultures in the absence and presence of Chitoskin®. Results were compared to those obtained for cellulose and silver-laminated cellulose. While the pure cellulose wound-dressing had no impact on the bacterial growth, Chitoskin® and, to an even greater extend, silver-laminated cellulose reduced the viable cell count over 4,5 hrs. Adding a second sample after 2 hrs of incubation resulted in a significantly increased activity of Chitoskin®. In the presence of protein the activity of the silver-laminated cellulose was completely abolished, while that of Chitoskin® continued for at least 3 hrs. Covering bacterial cells on an agar plate with Chitoskin® reversibly inhibited their growth, but did not kill them. Instead, they could be transferred to another sterile agar plate. The results are compatible with the hypothesis that Chitoskin® shows a bacteriostatic activity due to its ability to strongly adsorb the cells. From the theoretical point of view, heavily contaminated wounds would benefit from an early renewal of the wound dressing.Chitosan ist ein polykationisches Chitinderivat, das in schwachen Säuren gelöst einen hemmenden Effekt auf das Wachstum von Bakterien und Pilzen zeigt. Um derartige Effekte auch nachzuweisen, wenn es als Bestandteil von Wundauflagen wie Chitoskin® verwendet wird, wurde ein In-vitro-Test auf antibakterielle Aktivität mit drei Bakterienstämmen durchgeführt. Dazu wurde die Anzahl vermehrungsfähiger Bakterien in einem flüssigen Nährmedium in An- und Abwesenheit von Chitoskin® im Vergleich zu Auflagen aus Cellulose und silberbeschichteter Cellulose über mehrere Stunden verfolgt. Während das Wachstum eines Staphylococcus aureus -Stamms durch reine Cellullose nicht und durch Chitoskin® nur geringfügig beeinträchtigt wurde, zeigte silberbeschichtete Cellulose einen stärkeren Effekt. Erneute Zugabe des jeweiligen Materials nach 2 h erhöhte nur die Wirkung von Chitoskin® deutlich. Gegenüber einem methicillin-resistenten S. aureus (MRSA)-Stamm war die Wirkung aller Wundauflagen deutlich schwächer. Auf das Wachstum eines Pseudomonas aeruginosa -Stamms hatten wiederum die Cellulose keinen, jedoch Chitoskin® und silberbeschichtete Cellulose höhere Aktivitäten. In Anwesenheit von Protein wurde die Wirkung der silberbeschichteten Wundauflage jedoch vollständig aufgehoben, während die von Chitoskin® über mindestens 3 h unbeeinträchtigt blieb. Bakterien auf einer Agarplatte wurden nach Auflage von Chitoskin® im Wachstum gehemmt, jedoch nicht abgetötet, sondern konnten nach Auflegen des Materials auf eine sterile Agarplatte übertragen werden. Diese Ergebnisse deuten darauf hin, dass Chitoskin® Bakterienzellen adsorbiert und dadurch eine bakteriostatische Wirkung ausübt. Bei stärker kolonisierten Wunden könnte daher ein früher Wechsel der Wundauflage eine schnellere Erregerreduktion bewirken und so die Heilung begünstigen

Kappa-Join: Efficient Execution of Existential Quantification in XML Query Languages

XML query languages feature powerful primitives for formulating queries involving comparison expressions which are existentially quantified. If such comparisons involve several scopes, they are correlated, and become difficult to evaluate efficiently. In this paper, we develop a new ternary operator, called Kappa-Join, for efficiently evaluating queries with existential quantification. In XML queries, a correlation predicate can occur conjunctively and disjunctively. Our decorrelation approach not only improves performance in the conjunctive case, but also allows decorrelation of the disjunctive case. The latter is not possible with any known technique. In an experimental evaluation, we compare the query execution times of the Kappa-Join with existing XPath evaluation techniques to demonstrate the effectiveness of our new operator

Set up from the beginning: the origin and early development of cassava storage roots

Open Access Article; Published online: 01 Mar 2022Despite the importance of storage root (SR) organs for cassava and the other root crops yield, their developmental origin is poorly understood. Here we use multiple approaches to shed light on the initial stages of root development demonstrating that SR and fibrous roots (FR) follow different rhizogenic processes. Transcriptome analysis carried out on roots collected before, during and after root bulking highlighted early and specific activation of a number of functions essential for root swelling and identified root-specific genes able to effectively discriminate emerging FR and SR. Starch and sugars start to accumulate at a higher rate in SR before they swell but only after parenchyma tissue has been produced. Finally, using non-destructive computed tomography measurements, we show that SR (but not FR) contain, since their emergence from the stem, an inner channel structure in continuity with the stem secondary xylem, indicating that SR derive from a distinct rhizogenic process compared with FR