Zwitterionic peptides are facile low-fouling compounds for environmental applications as they are biocompatible and fully biodegradable as their degradation products are just amino acids. Here, a set ...of histidine (H) and glutamic acid (E), as well as lysine (K) and glutamic acid (E) based peptide sequences with zwitterionic properties were synthesized. Both oligopeptides (KE)4K and (HE)4H were synthesized in d and l configurations to test their ability to resist the nonspecific adsorption of the proteins lysozyme and fibrinogen. The coatings were additionally tested against the attachment of the marine organisms Navicula perminuta and Cobetia marina as well as the freshwater bacterium Pseudomonas fluorescens on the developed coatings. While the peptides containing lysine performed better in protein resistance assays and against freshwater bacteria, the sequences containing histidine were generally more resistant against marine organisms. The contribution of amino acid-intrinsic properties such as side chain pK a values and hydrophobicity, as well as external parameters such as pH and salinity of fresh water and seawater on the resistance of the coatings is discussed. In this way, a detailed picture emerges as to which zwitterionic sequences show advantages in future generations of biocompatible, sustainable, and nontoxic fouling release coatings.
Proper niche architecture is critical for stem cell function, yet only few upstream regulators are known. Here, we report that the Hox transcription factor Abdominal-B (Abd-B), active in premeiotic ...spermatocytes of Drosophila testes, is essential for positioning the niche to the testis anterior by regulating integrin in neighboring somatic cyst cells. Abd-B also non-cell-autonomously controls critical features within the niche, including centrosome orientation and division rates of germline stem cells. By using genome-wide binding studies, we find that Abd-B mediates its effects on integrin localization by directly controlling at multiple levels the signaling activity of the Sev ligand Boss via its direct targets src42A and sec63, two genes involved in protein trafficking and recycling. Our data show that Abd-B, through local signaling between adjucent cell types, provides positional cues for integrin localization, which is critical for placement of the distant stem cell niche and stem cell activity.
•Abd-B indirectly controls stem cell activity in the Drosophila larval testis•Integrin is the mediator for Abd-B-dependent stem cell niche positioning•Integrin localization is non-cell-autonomously controlled via the Boss/Sev pathway•Abd-B regulates Boss signaling activity via its direct targets src42A and sec63
Papagiannouli et al. show that Hox transcription factor Abd-B controls stem cell activity in the Drosophila larval testis via non-cell-autonomous regulation of integrin localization. Abd-B binds to promoters of src42A and sec63, trafficking components required for Boss/Sev pathway activity, which in turn controls integrin localization in neighboring cells.
Combining high hydrophilicity with charge neutrality, polyzwitterions are intensely explored for their high biocompatibility and low-fouling properties. Recent reports indicated that in addition to ...charge neutrality, the zwitterion’s segmental dipole orientation is an important factor for interacting with the environment. Accordingly, a series of polysulfobetaines with a novel architecture was designed, in which the cationic and anionic groups of the zwitterionic moiety are placed at equal distances from the backbone. They were investigated by in vitro biofouling assays, covering proteins of different charges and model marine organisms. All polyzwitterion coatings reduced the fouling effectively compared to model polymer surfaces of poly(butyl methacrylate), with a nearly equally good performance as the reference polybetaine poly(3-(N-(2-(methacryloyloxy)ethyl)-N,N-dimethylammonio)propanesulfonate). The specific fouling resistance depended on the detailed chemical structure of the polyzwitterions. Still, while clearly affecting the performance, the precise dipole orientation of the sulfobetaine group in the polyzwitterions seems overall to be only of secondary importance for their antifouling behavior.
Amphiphilic polymer coatings combining hydrophilic elements, in particular zwitterionic groups, and hydrophobic elements comprise a promising strategy to decrease biofouling. However, the influence ...of the content of the hydrophobic component in zwitterionic coatings on the interfacial molecular reorganization dynamics and the anti‐fouling performance is not well understood. Therefore, coatings of amphiphilic copolymers of sulfobetaine methacrylate 3‐N‐2'‐(methacryloyloxy)ethyl‐N,N‐dimethyl‐ammonio propane‐1‐sulfonate (SPE) are prepared which contain increasing amounts of hydrophobic n‐butyl methacrylate (BMA). Their fouling resistance is compared to that of their homopolymers PSPE and PBMA. The photo‐crosslinked coatings form hydrogel films with a hydrophilic surface. Fouling by the proteins fibrinogen and lysozyme as well as by the diatom Navicula perminuta and the green algae Ulva linza is assessed in laboratory assays. While biofouling is strongly reduced by all zwitterionic coatings, the best fouling resistance is obtained for the amphiphilic copolymers. Also in preliminary field tests, the anti‐fouling performance of the amphiphilic copolymer films is superior to that of both homopolymers. When the coatings are exposed to a marine environment, the reduced susceptibility to silt incorporation, in particular compared to the most hydrophilic polyzwitterion PSPE, likely contributes to the improved fouling resistance.
Amphiphilic polymer coatings containing zwitterionic sulfobetaine side chains and varying amounts of hydrophobic n‐butyl methacrylate are synthesized. The photo‐crosslinked coatings form hydrogel films which diminish non‐specific adsorption of proteins and biofouling by organisms drastically. In field tests, the anti‐fouling performance of amphiphilic copolymers is superior to both homopolymers partially due to reduced silt incorporation.
While zwitterionic interfaces are known for their excellent low-fouling properties, the underlying molecular principles are still under debate. In particular, the role of the zwitterion orientation ...at the interface has been discussed recently. For elucidation of the effect of this parameter, self-assembled monolayers (SAMs) on gold were prepared from stoichiometric mixtures of oppositely charged alkyl thiols bearing either a quaternary ammonium or a carboxylate moiety. The alkyl chain length of the cationic component (11-mercaptoundecyl)-N,N,N-trimethylammonium, which controls the distance of the positively charged end group from the substrate’s surface, was kept constant. In contrast, the anionic component and, correspondingly, the distance of the negatively charged carboxylate groups from the surface was varied by changing the alkyl chain length in the thiol molecules from 7 (8-mercaptooctanoic acid) to 11 (12-mercaptododecanoic acid) to 15 (16-mercaptohexadecanoic acid). In this way, the charge neutrality of the coating was maintained, but the charged groups exposed at the interface to water were varied, and thus, the orientation of the dipoles in the SAMs was altered. In model biofouling studies, protein adsorption, diatom accumulation, and the settlement of zoospores were all affected by the altered charge distribution. This demonstrates the importance of the dipole orientation in mixed-charged SAMs for their inertness to nonspecific protein adsorption and the accumulation of marine organisms. Overall, biofouling was lowest when both the anionic and the cationic groups were placed at the same distance from the substrate’s surface.
A fundamental question is how complex structures are maintained after their initial specification. Stem cells reside in a specialized microenvironment, called niche, which provides essential signals ...controlling stem cell behavior. We addressed this question by studying the Drosophila male stem cell niche, called the hub. Once specified, the hub cells need to maintain their position and architectural integrity through embryonic, larval and pupal stages of testis organogenesis and during adult life. The Hox gene Abd-B, in addition to its described role in male embryonic gonads, maintains the architecture and positioning of the larval hub from the germline by affecting integrin localization in the neighboring somatic cyst cells. We find that the AbdB-Boss/Sev cascade affects integrin independent of Talin, while genetic interactions depict integrin as the central downstream player in this system. Focal adhesion and integrin-adaptor proteins within the somatic stem cells and cyst cells, such as Paxillin, Pinch and Vav, also contribute to proper hub integrity and positioning. During adult stages, hub positioning is controlled by Abd-B activity in the outer acto-myosin sheath, while Abd-B expression in adult spermatocytes exerts no effect on hub positioning and integrin localization. Our data point at a cell- and stage-specific function of Abd-B and suggest that the occurrence of new cell types and cell interactions in the course of testis organogenesis made it necessary to adapt the whole system by reusing the same players for male stem cell niche positioning and integrity in an alternative manner.
•Abd-B is a cell-type and stage specific micromanager of hub positioning and integrity.•Abd-B acts as an upstream regulator of larval hub positioning from the germline spermatocytes.•The Abd-B and Boss/Sev cascade controls larval hub positioning independent of Talin.•Abd-B activity in acto-myosin sheath controls anterior adult hub positioning.•A network of integrin adaptor proteins controls hub positioning and integrity.
Abstract Aim This official guideline was published and coordinated by the DGGG, OEGGG and SGGG with the involvement of other medical societies. The aim was to provide a consensus-based overview of ...non-hormonal forms of contraception based on an evaluation of the relevant literature. The first part of these summarized statements and recommendations presents natural family planning methods such as lactational amenorrhea, barrier methods and coitus interruptus. The second part will focus on intrauterine devices and sterilization methods. Methods This S2k-guideline was developed by representative members from different medical professions on behalf of the guidelines commission of the DGGG, OEGGG and SGGG using a structured consensus process. Recommendations The guideline provides recommendations on the indications for, safety of use, benefits, and limitations of the different methods as well as recommendations on providing advice and other aspects of non-hormonal contraception. Natural family planning methods, lactational amenorrhea, barrier methods and coitus interruptus are discussed.
Zusammenfassung Ziel Das Ziel dieser offiziellen Leitlinie, die von der DGGG, OEGGG und SGGG unter Beteiligung weiterer Gesellschaften publiziert und koordiniert wurde, ist es, durch die Evaluation der relevanten Literatur einen konsensbasierten Überblick über die nicht hormonelle Empfängnisverhütung zu geben. Der 1. Teil dieser zusammenfassenden Statements und Empfehlungen beinhaltet Methoden der Natürlichen Familienplanung, die Laktationsamenorrhö, Barrieremethoden und den Coitus interruptus. Im 2. Teil werden Intrauterinpessare und die Sterilisation dargestellt. Methoden Diese S2k-Leitlinie wurde durch einen strukturierten Konsens von repräsentativen Mitgliedern verschiedener Professionen im Auftrag der Leitlinienkommission der genannten Gesellschaften entwickelt. Empfehlungen Diese Leitlinie gibt Empfehlungen zu Indikationen, Anwendungssicherheit, Benefits und Limitationen der verschiedenen Methoden sowie zur Beratung und weiteren Aspekten der nicht hormonellen Empfängnisverhütung. In dieser Zusammenfassung werden die Methoden der Natürlichen Familienplanung, die Laktationsamenorrhö, Barrieremethoden und der Coitus interruptus dargestellt.
Abstract Aim This official guideline was published and coordinated by the DGGG, OEGGG and SGGG with the involvement of other medical societies. The aim was to provide a consensus-based overview of ...non-hormonal forms of contraception based on an evaluation of the relevant literature. The first part of these summarized statements and recommendations presents natural family planning methods such as lactational amenorrhea, barrier methods and coitus interruptus. The second part focuses on intrauterine devices and sterilization. Methods This S2k-guideline was developed by representative members from different medical professions on behalf of the guidelines commission of the DGGG, OEGGG and SGGG using a structured consensus process. Recommendations The guideline provides recommendations on the indications for, safety of use, benefits, and limitations of the different methods as well as recommendations on providing advice and other aspects of non-hormonal contraception. This summary presents recommendations and statements about intrauterine devices and female and male sterilization.
Zusammenfassung Ziel Das Ziel dieser offiziellen Leitlinie, die von der DGGG, OEGGG und SGGG unter Beteiligung weiterer Gesellschaften publiziert und koordiniert wurde, ist es, durch die Evaluation der relevanten Literatur einen konsensbasierten Überblick über die nicht hormonelle Empfängnisverhütung zu geben. Der 1. Teil dieser zusammenfassenden Statements und Empfehlungen beinhaltet Methoden der Natürlichen Familienplanung, die Laktationsamenorrhö, Barrieremethoden und den Coitus interruptus. Im 2. Teil werden Intrauterinpessare und die Sterilisation dargestellt. Methoden Diese S2k-Leitlinie wurde durch einen strukturierten Konsens von repräsentativen Mitgliedern verschiedener Professionen im Auftrag der Leitlinienkommission der genannten Gesellschaften entwickelt. Empfehlungen Diese Leitlinie gibt Empfehlungen zu Indikationen, Anwendungssicherheit, Benefits und Limitationen der verschiedenen Methoden sowie zur Beratung und weiteren Aspekten der nicht hormonellen Empfängnisverhütung. In dieser Zusammenfassung werden die Intrauterinpessare und die weibliche sowie männliche Sterilisation dargestellt.
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