Diverse and productive source of biopolymer inspiration: marine collagens

Marine biodiversity is expressed through the huge variety of vertebrate and invertebrate species inhabiting intertidal to deep-sea environments. The extraordinary variety of â forms and functionsâ  exhibited by marine animals suggests they are a promising source of bioactive molecules and provides potential inspiration for different biomimetic approaches. This diversity is familiar to biologists and has led to intensive investigation of metabolites, polysaccharides, and other compounds. However, marine collagens are less well-known. This review will provide detailed insight into the diversity of collagens present in marine species in terms of their genetics, structure, properties, and physiology. In the last part of the review the focus will be on the most common marine collagen sources and on the latest advances in the development of innovative materials exploiting, or inspired by, marine collagens.The authors are grateful for the financial support from European Union, under the scope of European Regional Development Fund((ERDF) through the POCTEP project 0687_NOVOMAR_1_P and Structured Project NORTE-01- 0145-FEDER-000021 and from the Portuguese Foundation for Science and Technology (FCT), under the scope of the BiogenInk project (M-ERA-NET2/0022/2016) and from the European Cooperation in Science & Technology program (EU COST). Grant title: “Stem cells of marine/aquatic inverte brates: from basic research to innovative applications” (MARISTEM). MSR acknowledges FCT for the Ph.D. scholarship (PD/BD/143091/2018)

Insight into the proteome of the hyperthermophilic Crenarchaeon Ignicoccus hospitalis: the major cytosolic and membrane proteins

Ignicoccus hospitalis, a hyperthermophilic, chemolithoautotrophic Crenarchaeon, is the host of Nanoarchaeum equitans. Together, they form an intimate association, the first among Archaea. Membranes are of fundamental importance for the interaction of I. hospitalis and N. equitans, as they harbour the proteins necessary for the transport of macromolecules like lipids, amino acids, and cofactors between these organisms. Here, we investigated the protein inventory of I. hospitalis cells, and were able to identify 20 proteins in total. Experimental evidence and predictions let us conclude that 11 are soluble cytosolic proteins, eight membrane or membrane-associated proteins, and a single one extracellular. The quantitatively dominating proteins in the cytoplasm (peroxiredoxin; thermosome) antagonize oxidative and temperature stress which I. hospitalis cells are exposed to at optimal growth conditions. Three abundant membrane protein complexes are found: the major protein of the outer membrane, which might protect the cell against the hostile environment, forms oligomeric complexes with pores of unknown selectivity; two other complexes of the cytoplasmic membrane, the hydrogenase and the ATP synthase, play a key role in energy production and conversion

Mechanical properties of the compass depressors of the sea-urchin Paracentrotus lividus (Echinodermata, Echinoidea) and the effects of enzymes, neurotransmitters and synthetic tensilin-like protein

The compass depressors (CDs) of the sea-urchin lantern are ligaments consisting mainly of discontinuous collagen fibrils associated with a small population of myocytes. They are mutable collagenous structures, which can change their mechanical properties rapidly and reversibly under nervous control. The aims of this investigation were to characterise the baseline (i.e. unmanipulated) static mechanical properties of the CDs of Paracentrotus lividus by means of creep tests and incremental force-extension tests, and to determine the effects on their mechanical behaviour of a range of agents. Under constant load the CDs exhibited a three-phase creep curve, the mean coefficient of viscosity being 561±365 MPa.s. The stress-strain curve showed toe, linear and yield regions; the mean strain at the toe-linear inflection was 0.86±0.61; the mean Young's modulus was 18.62±10.30 MPa; and the mean tensile strength was 8.14±5.73 MPa. Hyaluronidase from Streptomyces hyalurolyticus had no effect on creep behaviour, whilst chondroitinase ABC prolonged primary creep but had no effect on secondary creep or on any force-extension parameters; it thus appears that neither hyaluronic acid nor sulphated glycosaminoglycans have an interfibrillar load transfer function in the CD. Acetylcholine, the muscarinic agonists arecoline and methacholine, and the nicotinic agonists nicotine and 1-[1-(3,4-dimethyl-phenyl)-ethyl]-piperazine produced an abrupt increase in CD viscosity; the CDs were not differentially sensitive to muscarinic or nicotinic agonists. CDs showed either no, or no consistent, response to adrenaline, L-glutamic acid, 5-hydroxytryptamine and γ-aminobutyric acid. Synthetic echinoid tensilin-like protein had a weak and inconsistent stiffening effect, indicating that, in contrast to holothurian tensilins, the echinoid molecule may not be involved in the regulation of collagenous tissue tensility. We compare in detail the mechanical behaviour of the CD with that of mammalian tendon and highlight its potential as a model system for investigating poorly understood aspects of the ontogeny and phylogeny of vertebrate collagenous tissues.(undefined)info:eu-repo/semantics/publishedVersio

Halobacterial flagellins are encoded by a multigene family. Identification of all five gene products

Flagellins of Halobacterium halobium are encoded in five different but homologous genes. Flagellins isolated from purified flagella were digested and the resulting peptides sequenced. The amino acid sequence data obtained prove that all five gene products are expressed and integrated into the flagellar bundle

Untersuchungen chemischer Konsequenzen des radioaktiven Zerfalls von Iod-125 und Tritium in markierten Pyrimidinbasen mit Hilfe der Doppelmarkierungstechnik und der ESR Spektroskopie

In der vorliegenden Arbeit wurden die chemischen Folgereaktionen des radioaktiven Zerfalls von Iod-125 in Lösungen des synthetischen DNS-Vorläufers Ioduracil mit dem Ziel untersucht, die große Radiotoxizität von DNS-gebundenem $^{125}$I durch Vorgänge auf molekularer Ebene zu deuten. Darüber hinaus wurde in kleineremUmfang auch die Radikalbildung als Folge des Zerfalls von Tritium in $^{3}$H-markiertem Thymin und Cytosin verfolgt. Die chemischen Zerfallseffekte von molekular gebundenem Iod-125 wurden mit Hilfe der Doppelmarkierungstechnik untersucht. Hierzu wurde [2-$^{14}$ C,5-$^{125}$I]-Ioduracil und in einigen Versuchen auch[5-$^{125}$I,6-$^{3}$H]-Ioduracil verwendet. Die Verbindungen wurden aus dem in hohen spezifischen Aktivitäten vorliegenden [2- $^{14}$C]-Uracil und [6-$^{3}$H]-Uracil durch Iodierung mit praktisch träger-freiem $^{125}$I synthetisiert und anschließend durch Hochdruckflüssigkeitschromatographie auf mehreren Säulen gereinigt. Im Falle der $^{14}$C-markierten Substanz waren etwa 80 % der Moleküle doppelt markiert. Die doppelt markierten Verbindungen wurden sowohl in wässerigem Ethanol als auch in sauerstoffgesättigtem Wasser (p(O$_{2}$) = 1 atm) bei +2 °C und bei -196 °C zur Akkumulierung von $^{125}$I-Zerfallen und damit von Produktmolekülen mehrere Monate aufbewahrt und schließlich mit Hilfe der Radiogaschromatographie und der Radiohochdruckflüssigkeitschromatographieanalysiert. Da neben den direkten Transmutationseffekten, die sich auf das Molekül auswirken, an dem der radioaktive Zerfall des $^{125}$I-Atoms stattfindet, auch radiolytische Effekte durch die beim Zerfall emittierten Elektronen auftreten, mußte unter vergleichbaren Bedingungen auch das Spektrum der durch diese Prozesse gebildeten Produkte aufgeklärt werden. Die radiolytischen Effekte wurden durch $^{60}$Co-$\gamma$-Bestrahlung von entsprechenden [2-$^{14}$C]-Ioduracil-lösungen untersucht. Mit Hilfe eines einfachen Korrekturverfahrens konnten so die reinen Zerfallseffekte erfaßt werden

Evidence for coiled-coil alpha-helical regions in the long arm of laminin.

Three new laminin fragments, E8, E9 and 25K with mol. wt. 50 000-280 000, were prepared from a limited elastase digest of laminin and from tissue extracts. They were similar with respect to their rod-like structure, a high alpha-helix content, the assembly from two chain segments and immunological cross-reactivity. Two of the fragments (E8 and E9) possess in addition globular domains which lack alpha-helices. Chemical, immunological and physical data together with sequence analysis strongly indicate that the alpha-helical segments are assembled in coiled-coil structures which are located in the rod of the long arm of laminin. These data give new insights into the overall structure of the protein