Micha Ilan | Tel Aviv University (original) (raw)

Papers by Micha Ilan

LAGLIDADG protein alignment. Protein sequence alignment, in Nexus format, used to reconstruct the... more LAGLIDADG protein alignment. Protein sequence alignment, in Nexus format, used to reconstruct the phylogenetic tree presented in Fig.Â 4. (NEX 213 kb)

Sample origin. (XLSX 11 kb)

Alignment of ORF 870. DNA sequence alignment, in Fasta format, of the ORF 870 of Tetilla radiata,... more Alignment of ORF 870. DNA sequence alignment, in Fasta format, of the ORF 870 of Tetilla radiata, Plakina trilopha, Plakina crypta, Agelas oroides and Axinella polypoides. (FASTA 5 kb)

Journal of Structural Biology, Sep 1, 2011

The ball-shaped marine sponge Cinachyrella levantinensis is 3-5 cm in diameter. It filters large ... more The ball-shaped marine sponge Cinachyrella levantinensis is 3-5 cm in diameter. It filters large quantities of seawater for feeding. Sponges contain numerous, hydrated, brittle amorphous SiO 2 spicules of several types that form 70-80% by weight of the sponge. We performed mechanical tests to determine the functionality of the sponge skeleton. The potential effect of habitat on skeleton properties was investigated by comparing sponges from 0.5 m and 30 m depth. We determined how spicules contribute to maintaining the strength and macroscopic structural integrity of a sponge, and studied their deformation mechanisms under external loading, and their microscopic design parameters. Compression tests of cylindrical samples cut from sponges revealed their macroscopic deformation mechanisms. Experiments solely with the organic material (following spicules dissolution) revealed the contribution of the spicules to the load carrying capacity and structural integrity of the sponge. Cantilever bending tests of anchored spicules determined the strength of individual spicules, the sponge's main skeletal elements. As the strength of brittle spicules is statistical in nature, we used Weibull Statistics to define their strength and evaluate their Young's modulus. Shallow and deep-water sponges did not differ significantly neither in response to compression, nor in spicule strength under bending and tension. Spicule weight fraction within a sponge was significantly higher in shallow-water individuals. We conclude that the structural integrity and strength of this sponge's skeleton is derived from its lowstrength, small spicules, produced by a cost-effective process. The operating deformation of the spicules (bending) and their design parameters make them highly efficient.

Marine Drugs, Mar 28, 2023

This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY

Marine Ecology, Apr 29, 2013

Secondary metabolites protect many marine sponges (Phylum: Porifera) from settlement by fouling o... more Secondary metabolites protect many marine sponges (Phylum: Porifera) from settlement by fouling organisms. Previous studies on the subtidal demosponge Axinella verrucosa collected in the Western Mediterranean led to the isolation of compounds that inhibited the settlement of cyprids larvae of the intertidal barnacle Balanus amphitrite, and the enzyme chitinase, which plays a key role in the molting cycle of crustaceans. However, in a field survey conducted at three locations in Israel, Eastern Mediterranean Sea, we observed that A. verrucosa is fouled by the subtidal barnacle Balanus trigonus, a previously unknown association. Settlement inhibition assays using B. amphitrite with chemical extracts from Israeli A. verrucosa and Axinella polypoides, a sympatric, congeneric sponge that seems not to be fouled by B. trigonus, showed that cyprid larvae of B. amphitrite were inhibited by the extracts of both sponges from settlement at concentrations several magnitudes lower than natural volumetric extract concentration in the sponges. These results indicate that, unlike the intertidal barnacle B. amphitrite, the subtidal B. trigonus is unaffected by the compounds from A. verrucosa, stressing and underlining the importance of using suitable target organisms (i.e. from the same habitat) to test for ecologically relevant antifouling activities.

Marine Drugs, Nov 26, 2021

The Biological Bulletin, Dec 1, 2014

The solitary ascidian Phallusia nigra is rarely fouled by epibionts. Here, we tested the antifoul... more The solitary ascidian Phallusia nigra is rarely fouled by epibionts. Here, we tested the antifouling activity of its crude extracts in laboratory and field assays. P. nigra extracts inhibited the growth of all eight tested environmental bacteria and two of four laboratory bacteria. Extracts of the sympatric, but fouled solitary ascidian Herdmania momus inhibited only one test bacterium. Scanning electron microscopy confirmed that the tunic surface of P. nigra is largely bacteria-free. Both ascidian extracts significantly inhibited the larval metamorphosis of the bryozoan Bugula neritina at the tested concentration range of 0.05-2 mg ml(-1). Both crude extracts were toxic to larvae of the brine shrimp Artemia salina at natural volumetric whole-tissue concentrations, but only P. nigra showed activity at 2 mg ml(-1) and below (LC50 = 1.11 mg ml(-1)). P. nigra crude extracts also significantly reduced the settlement of barnacles, polychaetes, and algae in Mediterranean field assays and barnacle settlement in Red Sea trials. Comparisons between control experiments and pH values monitored in all experiments indicate that the observed effects were not due to acidity of the organic extracts. Our results show that P. nigra secondary metabolites have antifouling activities, which may act in synergy with previously proposed physiological antifouling mechanisms.

Journal of Natural Products, Dec 30, 2000

Aplyzanzine A (1), a novel bisdibromotyrosine derivative, has been isolated from the Indo-Pacific... more Aplyzanzine A (1), a novel bisdibromotyrosine derivative, has been isolated from the Indo-Pacific sponge Aplysina sp. Its structure was elucidated mainly on the basis of 1D and 2D NMR and MS spectroscopic data. a Data recorded in CDCl3+CD3OD (10:1) at 500 MHz (1 H) and 125 MHz (13 C) at 27°C. b CH assignments are based on the HMQC spectrum. c Obtained from a spectrum taken in CDCl3 only.

Natural Product Letters, Nov 1, 1992

Four Novel Diterpenes, Cyanthiwigin A-D (1–4) Have Been Isolated From The Marine Sponge E. Reiswi... more Four Novel Diterpenes, Cyanthiwigin A-D (1–4) Have Been Isolated From The Marine Sponge E. Reiswigi And Their Structure Elucidated By Mass And Mainly Nmr Spectra. The Tricarbocyclic Structure Of 1 Was Confirmed By An X-Ray Analysis And Its Absolute Configuration Was Established To Be 4s, 5r, 6s, 9s By The Modified Mosher's Method. The Four Compounds Have The Same Planar

Tetrahedron Letters, May 1, 1992

3Methylation of 1 with MeI in acetone afforded a diiodide in which the protons α to the pyridine ... more 3Methylation of 1 with MeI in acetone afforded a diiodide in which the protons α to the pyridine nitrogen moved to δh 8.87 & 8.90 (δc 145.5 & 146.4) and in the same time H-8′ & 9′ changed to 5.71dt and 5.59dt (J=11,7Hz) confirming the Z-configuration. A similar change was ...

International Journal of Biological Macromolecules, Nov 1, 2013

The recent discovery of chitin within skeletons of numerous marine and freshwater sponges (Porife... more The recent discovery of chitin within skeletons of numerous marine and freshwater sponges (Porifera) stimulates further experiments to identify this structural aminopolysaccharide in new species of these aquatical animals. Aplysina fistularis (Verongida: Demospongiae: Porifera) is well known to produce biologically active bromotyrosines. Here, we present a detailed study of the structural and physico-chemical properties of the three-dimensional skeletal scaffolds of this sponge. Calcofluor white staining, Raman and IR spectroscopy, ESI-MS as well as chitinase digestion test were applied in order to unequivocally prove the first discovery of α-chitin in skeleton of A. fistularis.

BMC Evolutionary Biology, Sep 14, 2006

Marine-derived compounds have been explored and considered as possible antitumor agents. In this ... more Marine-derived compounds have been explored and considered as possible antitumor agents. In this study, we analyzed extracts of the sponge Cribrochalina vasculum for their ability to inhibit tumor cell proliferation. Screening identified two acetylenic compounds of similar structure that showed strong tumor-specific toxicity in non–small cell lung carcinoma (NSCLC) cells and small-cell lung carcinoma cells, and less prominent toxicity in ovarian carcinoma, while having no effect on normal cells. These acetylenic compounds were found to cause a time-dependent increase in activation of apoptotic signaling involving cleavage of caspase-9, caspase-3, and PARP, as well as apoptotic cell morphology in NSCLC cells, but not in normal fibroblasts. Further analysis demonstrated that these compounds caused conformational change in Bak and Bax, and resulted in loss of mitochondrial potential and cytochrome c release in NSCLC cells. Moreover, a decreased phosphorylation of the growth factor signaling kinases Akt, mTOR, and ERK was evident and an increased phosphorylation of JNK was observed. Thus, these acetylenic compounds hold potential as novel therapeutic agents that should be further explored for NSCLC and other tumor malignancies. Mol Cancer Ther; 13(12); 2941–54. ©2014 AACR.

Proceedings of The Royal Society B: Biological Sciences, Feb 22, 1996

Abstract Morphogenesis of different-shaped biogenic crystals presents one of the important biomin... more Abstract Morphogenesis of different-shaped biogenic crystals presents one of the important biomineralization problems. Growth of various calcitic spicules from Sycon sp. have been studied by using calcein marking. We found that spicule production is dependent on ...

Connective Tissue Research, 1996

Control over the shapes of biologically formed crystals is generally not well understood. We have... more Control over the shapes of biologically formed crystals is generally not well understood. We have studied the morphogenesis of the different-shaped calcareous sponge spicules using high-resolution synchrotron X-ray diffraction. We show that a remarkable correlation exists between the distribution of defects within spicule crystals at the nanometer level and their macroscopic morphologies at the millimeter level. These defects are produced by controlled intercalation of specialized macromolecules into the crystals. We also show that such intracrystalline macromolecules are involved in the regulation of the shapes of synthetic crystals grown de novo from solution, and epitaxially overgrown on the spicule surfaces. We conclude that intracrystalline macromolecules play an important role in modulation of the morphologies of the forming biogenic crystals. Possible mechanisms that may account for the observed growth patterns are supported by fluorescence labeling experiments in vivo.

Tetrahedron, 1989

@SWCT Nine new P-amino imidazole alkaloids belonging to four different groups have been isolated ... more @SWCT Nine new P-amino imidazole alkaloids belonging to four different groups have been isolated from a Red Sea sponge. The structures of all compounds were elucidated from spectral data, mainly by 1D and 2D NMR techniques, by mass spectra and in case of naamidine A also by chemical transformations. A nudibranch, Notodor& citrfna feeding on the L_ chagosensis sponge was found to concentrate the new imidazole alkaloids. The antifungal activity of the MeOH-Toluene (3:l) extract of the small bright yellow calcareous sponge Leucetta chaopsensis brought us to investigate the secondary metabolites of this sponge. L. chwsensis collected in the Gulf of Eilat, The Red Sea, belongs to the class Calcisponginae (Calcarea) which is relatively, to the Demospongiae class, unexplored. The 5-10% methanolic chloroform extract of the freeze-dried organism was found by us to be rich in nitrogen containing metabolites. Repeated chromatographies on Sephadex LH-20 and RP-18 columnsseparated between a mixture of nucleosides and a complex mixture of imidazole alkaloids. Out of the latter mixture we separated and purified nine new P-amino imidazoles belonging to four closely related groups of compounds. The structures of four compounds designated naamidine A(l), naamine A(z), isonaamidine A(2) and isonaamine A(&)#-representatives of the four types of the novel alkaloids (Figure 1) were reported by us most recentlyl. It is the aim of this report to describe the structure of five additional new compounds belonging to these 2-amino imidazoles and the full spectral data of all the nine alkaloids. The structure of naamidine A(&) C23H23N504, one of the two major alkaloids of the sponge, was determined on the basis of NMR studies [lH&13C(Table 1) and 2D COSY', HETCOSY3 and NOE experiments] mass fragmentations as well as its reduction and degradation'. The COSY experiment suggested two para-substituted benzyl groups which were further confirmed by the hetero nuclear correlation experiment (HETCOSY)3, namely by, 3.JCH correlations in the benzene rings and correlations from H-7 and 14 to C-9(13) and 16(20) respectively. The latter experiment also determined the position of the two benzyls on the imidazole ring (due to 2J and 3J correlations of H-7 and 14 to C-4 and 5) as well as the locations of two methyl groups, one at N(2) of the imidazole and the second at a(&') of the imidazoledione (by correlations of the CH3-N(3) to C-264, and the a3-N(1') to C-4'&5'). Sodium borohydride reduction of 1 reduced the latter ring to give two tetrahydro naamidine A derivatives, compounds u and u., in a ratio of ca. 2O:l (Fig.2). The 'H NMR of E (an additional aminal #The compounds were named after the Bay of Naama where the sponge was first collected. 2193 S. CAR~LK et al.

Nature, Aug 1, 2003

odern technology cannot yet compete with some of the sophisticated optical systems possessed by b... more odern technology cannot yet compete with some of the sophisticated optical systems possessed by biological organisms 1-3. Here we show that the spicules of the deep-sea 'glass' sponge Euplectella have remarkable fibre-optical properties, which are surprisingly similar to those of commercial telecommunication fibres-except that the spicules themselves are formed under normal ambient conditions and have some technological advantages over man-made versions. The skeleton of the hexactinellid class of sponges is constructed from amorphous, hydrated silica 3-6. Euplectella builds an intricate cage (Fig. 1a), which typically houses a mating pair of shrimp (hence its nickname, 'Venus flower-basket') and is composed of a lattice of fused spicules 4 that provide extended structural support. A network of anchorage spicules (basalia) extend outwards in a crown-like formation. These spicules are generally 5-15 cm long and 40-70 Ȗm in diameter; their native cross-section is homogeneous and