Search results

Search:
in the keywords: sponges

Sort By:

Limit search:

Renewable chitin from marine sponge as a thermostable biological template for hydrothermal synthesis of hematite nanospheres using principles of extreme biomimetics

100%

Wysokowski M., Petrenko I., Motylenko M., Langer E., Bazhenov V. V., Galli R., Stelling A. L., Kljajić Z., Szatkowski T., Kutsova V. Z., Stawski D., Jesionowski T.

Bioinspired Materials

2014

vol. 1

issue 1

Chitin originating from marine sponges possesses a unique nanofibrillar network structure that is the basic element of the microtubular scaffold-like skeleton of these organisms. Sponge chitin represents an intriguing example of thermostability, as it is stable up to 400 °C. It also constitutes a renewable biological source due to the high regeneration ability of Aplysina sponges under marine farming conditions. These properties can be exploited for the facile and environmentally friendly creation of novel, biocompatible organic-inorganic hybrid materials with a range of uses. Here, chitin-based scaffolds isolated from the skeleton of marine demosponge Aplysina aerophoba were used as a template for the in vitro formation of iron oxide from a saturated iron(III) chloride solution, under hydrothermal conditions (pH~1.5, 90 °C). The resultant chitin-Fe2O3 three dimensional composites, prepared for the first time via hydrothermal synthesis route, were thoroughly characterized using light, fluorescence and scanning electron microscopy; as well as with analytical methods like Raman spectroscopy, electron diffraction and HR-TEM. The results show that this versatile method allows for efficient chitin mineralization with respect to hematite. Additionally, we demonstrate that chitin nanofibers template the nucleation of uniform Fe2O3 nanocrystals.

The ancestry and cumulative evolution of immune reactions

67%

Dzik J. M.

2010

vol. 57

issue 4

443-466

The last two decades of study enriched greatly our knowledge of how the immune system originated and the sophisticated immune mechanisms of today's vertebrates and invertebrates developed. Even unicellular organisms possess mechanisms for pathogen destruction and self recognition. The ability to distinguish self from non-self is a prerequisite for recognition of sexual compatibility and ensuring survival. Molecules involved in these processes resemble those found in the phagocytic cells of higher organisms. Recognition of bacteria by scavenger receptors induces phagocytosis or endocytosis. The phagocytic mechanisms characterizing the amoeboid protozoans developed further during the evolution towards innate immunity. The scavenger receptor cysteine-rich domain SRCR is encoded in the genomes from the most primitive sponges to mammals. The immune system of sponges comprises signal transduction molecules which occur in higher metazoans as well. Sponges already possess recognition systems for pathogenic bacteria and fungi, based on membrane receptors (a lipopolysaccharide-interacting protein, a cell surface receptor recognizing β(1 → 3)-d-glucans of fungi). Perforin-like molecules and lysozymes are involved, among others, in defense in sponges. Reactive oxygen and nitrogen species function in the immunity of early metazoan. Genes encoding the family of reactive oxygen-generating NADPH oxidases (Noxes) are found in a variety of protists and plants. The NO synthases of cnidarians, mollusks, and chordates are conserved with respect to the mammalian NOS. The antimicrobial peptides of protozoans, amoebapores, are structural and functional analogs of the natural killer cell peptide, NK-lysin, of vertebrates. An ancestral S-type lectin has been found in sponges. Opsonizing properties of lectins and the ability to agglutinate cells justify their classification as primitive recognition molecules. Invertebrate cytokines are not homologous to those of vertebrate, and their functional convergence was presumably enabled by the general similarity of the lectin-like recognition domain three-dimensional structure. Sponges contain molecules with SCR/CCP domains that show high homology to the mammalian regulators of complement activation (RCA family). A multi-component complement system comprising at least the central molecule of the complement system, C3, Factor B, and MASP developed in the cnidarians and evolved into the multilevel cascade engaged in innate and acquired immunity of vertebrates. The adaptive immune system of mammals is also deeply rooted in the metazoan evolution. Some its precursors have been traced as deep as in sponges, namely, two classes of receptors that comprise Ig-like domains, the receptor tyrosine kinases (RTK), and the non-enzymic sponge adhesion molecules (SAM). The antibody-based immune system defined by the presence of the major histocompatibility complex (MHC), T-cell receptor (TCR), B-cell receptor (BCR) or recombination activating genes (RAGs) is known beginning from jawed fishes. However, genes closely resembling RAG1 and RAG2 have been uncovered in the genome of a see urchin. The ancestry of MHC gene remains unknown. Similarly, no homologue of the protein binding domain (PBD) in MHC molecules has been found in invertebrates. The pathway by which endogenous peptides are degraded for presentation with class I MHC molecules utilizes mechanisms similar to those involved in the normal turnover of intracellular proteins, apparently recruited to work also for the immune system. Several cDNAs coding for lysosomal enzymes, e.g., cathepsin, have been isolated from sponges. All chromosomal duplication events in the MHC region occurred after the origin of the agnathans but before the gnathostomes split from them. The V-domains of the subtype found in the receptors of T and B-cells are known from both agnathans and cephalochordates, although they do not rearrange. The rearrangement mechanism of the lymphocyte V-domains suggests its origin from a common ancestral domain existing before the divergence of the extant gnathostome classes. Activation-induced deaminase (AID) - homologous proteins have been found only in the gnathostomes. It appears thus that the adaptive immunity of vertebrates is a result of stepwise accumulation of small changes in molecules, cells and organs over almost half a billion years.

Refine search results

1 Acta Biochimica Polonica

1 Bioinspired Materials

1 2015

1 2010

1 Bazhenov V. V.

1 Dzik J. M.

1 Galli R.

1 Jesionowski T.

1 Kljajić Z.

1 Kutsova V. Z.

1 Langer E.

1 Motylenko M.

1 Petrenko I.

1 Stawski D.

1 Stelling A. L.

1 Szatkowski T.

1 Wysokowski M.

Search results

Renewable chitin from marine sponge as a thermostable biological template for hydrothermal synthesis of hematite nanospheres using principles of extreme biomimetics

The ancestry and cumulative evolution of immune reactions