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B Rinkevich

Publications and source records attributed to B Rinkevich.

At least 37 records · Page 2Linked to original sources
PubMed1997

Cloning and characterization of BS-cadherin, a novel cadherin from the colonial urochordate Botryllus schlosseri.

The genomic DNA for a novel member of the cadherin family (BS-cadherin) was cloned and characterized from the colonial marine invertebrate, Botryllus schlosseri. Using a differential display of mRNA by means of PCR, a small cDNA fragment of 380 nucleotides was found to be specifically expressed in a colony undergoing allogeneic rejection processes, as compared with naive parts of the same genotype. This cDNA fragment was used as a probe to screen a genomic library of Botryllus schlosseri. A genomic fragment containing an ORF of 2718 nucleotides, with no introns, was isolated. The encoded protein exhibits a typical structure of cadherins; an extracellular domain with conserved repeated sequences (cadherin signatures), a single transmembrane domain and a conserved cytoplasmic tail region. The BS-cadherin amino-acid sequence shows 32-35% identity to mature classical cadherins type I, e.g., N-, P- and E-cadherin as well as mature classical cadherins type II, e.g., human cadherin-6, -8 and OB-cadherin. This cadherin represents a new cadherin gene family, evolutionarily distant to all other known classical cadherins.

Amino Acid Sequence↗
PubMed1997

A novel tunicate (Botryllus schlosseri) putative C-type lectin features an immunoglobulin domain.

We have cloned a putative C-type lectin of Botryllus schlosseri [Ascidiacea], whose deduced protein of 333 amino acids features three building blocks: (i) a Greek-key motif signature at the amino-terminus, (ii) a C-type lectin domain signature, and (iii) an immunoglobulin (Ig) domain at the carboxyl terminus. This C-type lectin was termed BSCLT. Similarity searches revealed that the Ig domain in BSCLT, which is evidently not polymorphic, is best classified as an Intermediate-type Ig domain. Rabbit antibodies, raised against recombinant BSCLT, cross-reacted in a Western blot with a 38-kD polypeptide in tunicate crude extract. Presumably, this bimodal tunicate protein is the first description of a soluble lectin that features besides the carbohydrate recognition domain also a complete Ig domain.

Amino Acid Sequence↗
PubMed1996

Molecular cloning and sequence analysis of two cDNAs coding for putative anionic trypsinogens from the colonial Urochordate Botryllus schlosseri (Ascidiacea).

Botryllus schlosseri is a colonial marine invertebrate that belongs to the subphylum Urochordata. Previously we analyzed the activity of a serine protease in this species, and cloned a tunicate chymotrypsin-like molecule. In the present study we further analyzed the protease activity of this animal, and found biochemical evidence also for specific trypsin-like activity. Subsequently we utilized a degenerate polymerase chain reaction (PCR) primer to clone two B. schlosseri cDNAs coding for two different putative trypsinogens, each 243 amino acids long, that differ within the coding region in 42 amino acids and 99 nucleotides. Both clones feature the characteristics of animal anionic trypsinogens. Sequence analysis of the tunicate putative trypsinogens revealed the invertebrate characteristics of three disulfide bridges, and higher similarity to invertebrate than to vertebrate trypsinogens. We therefore propose that the typical characteristics of vertebrate trypsinogens evolved after the divergence of Urochordates and Cephalochordates.

Amino Acid Sequence↗
PubMed1996

Bi-versus multichimerism in colonial urochordates: a hypothesis for links between natural tissue transplantation, allogenetics and evolutionary ecology.

Allogenic colonies of the cosmopolitan ascidian Botryllus schlosseri may fuse upon contact through their blood vessels to form chimeric entities if they share at least one allele at a highly polymorphic haplotype, termed the fusibility-histocompatibility (Fu/HC) locus. Past studies have attributed several benefits to this chimerism, but none of the suggestions was confirmed by controlled laboratory studies. Furthermore, once Botryllus colonies fuse, a second allorecognition phenomenon begins which usually leads to the resorption of one partner in the chimera. Resorption is probably controlled by a multilevel hierarchial organization of the heterozygosity relatedness for several allorecognition elements (the Fu/HC and resorption loci), which also reflects the relative heterozygosity of each partner's genome. Consequently, the more heterozygotic partner will be the 'winner' in the resorption, leaving alive the most adapted genotype (sensu to the heterosis concept). However, recent studies have recorded that freely circulating stem cells from the 'subordinate' partner in the resorption phenomenon may parasitize the 'winner' for positions on the germ line. All the above studies have been performed on bichimeric entities. It is suggested here that formation of natural multichimeras in this species (resulting from an aggregated cosettlement of Fu/HC compatible colonies) produces more 'equilibrated' chimeric entities and alleviates the costs incurred through the contradicting heterosis and germ cell parasitism processes. This improves the interspecific competitive ability of the multifusion entities. Therefore, in this case, selection acts on the 'group' level, not the colony level, providing the evolutionary forces that shape the phenomenon of natural tissue transplantation in these organisms.

Animals↗
PubMed1995

Whole-body protochordate regeneration from totipotent blood cells.

Cell differentiation, tissue formation, and organogenesis are fundamental patterns during the development of multicellular animals from the dividing cells of fertilized eggs. Hence, the complete morphogenesis of any developing organism of the animal kingdom is based on a complex series of interactions that is always associated with the development of a blastula, a one-layered hollow sphere. Here we document an alternative pathway of differentiation, organogenesis, and morphogenesis occurring in an adult protochordate colonial organism. In this system, any minute fragment of peripheral blood vessel containing a limited number of blood cells isolated from Botrylloides, a colonial sea squirt, has the potential to give rise to a fully functional organism possessing all three embryonic layers. Regeneration probably results from a small number of totipotent stem cells circulating in the blood system. The developmental process starts from disorganized, chaotic masses of blood cells. At first an opaque cell mass is formed. Through intensive cell divisions, a hollow, blastula-like structure results, which may produce a whole organism within a short period of a week. This regenerative power of the protochordates may be compared with some of the characteristics associated with the formation of mammalian embryonal carcinomous bodies. It may also serve as an in vivo model system for studying morphogenesis and differentiation by shedding more light on the controversy of the "stem cell" vs. the "dedifferentiation" theories of regeneration and pattern formation.

Journal Article↗
PubMed1995

Cloning of a urochordate cDNA featuring mammalian short consensus repeats (SCR) of complement-control protein superfamily.

Mammalian tumor necrosis factor (TNF)-alpha degenerate polymerase chain reaction (PCR) primers were used to amplify a probe from Botryllus schlosseri (colonial ascidian) allogeneic rejection-cDNA library. A PCR product (269 bp) was cloned and sequenced encoding an open reading frame (ORF) of 89 amino acids (aa). This clone, which revealed no similarity to TNF-alpha, but a substantial similarity to mammalian proteins featuring short consensus repeats (SCRs) of the complement control superfamily, was used to probe the rejection-cDNA library. Two partial cDNA clones were isolated and sequenced (Bs.1, 846 bp; Bs.2, 712 bp). The longest ORF in clone Bs.1 (which lacks the 5' end of the cDNA) predicts a protein of 251 aa, which differs from Bs.2 at six nucleotides and four aa. We compare the aa similarity (up to 50.5%) of Bs.1 with the SCR-region of mammalian complement factor H, apolipoprotein H, selectins, and complement receptors type 1 and type 2. A somatomedin B-like domain at the C-terminus of Bs.1 deduced protein was also recorded. We propose that this mosaic and polymorphic botryllid sequence, featuring mammalian-like SCRs, might be an ancestral molecule in the evolution of the chordate's complement-control protein superfamily.

Amino Acid Sequence↗
PubMed1994

Molecular evidence for the presence of a developmental gene in the lowest animals: identification of a homeobox-like gene in the marine sponge Geodia cydonium.

During the development of higher animals, morphogenetic programs are switched on which are frequently controlled by homeotic genes. Until now these genes have not been identified in the lowest animals, the marine sponges. Since sponges show (i) an antero-posterior and/or dorso-ventral axis during embryogenesis and (ii) a complex differentiation pattern during spicula formation, we hypothesized that in sponges homeotic genes--if present--are also involved in the control of these processes. Therefore, we searched for homeobox or homeobox-like sequences in the marine sponge Geodia cydonium. Here we describe a homeobox-like sequence from these animals; it was isolated from a cDNA library of an adult specimen. The deduced amino acid sequence of the complete homeodomain shares over 70% similarity with other homeodomain sequences, including those from hydra, insects and vertebrates. These data indicate that the sponge homeodomain-like sequence is similar with respect to structure to those of other animals and may suggest that the sponge homeodomain-like sequence(s) might function during developmental processes and/or during spiculogenesis in a similar manner to that known for higher animals.

Amino Acid Sequence↗
PubMed1994

Direct typing of polymorphic microsatellites in the colonial tunicate Botryllus schlosseri (ASCIDIACEA).

Five microsatellite loci of the marine protochordate Botryllus schlosseri were cloned: four of uninterrupted (AG)n repeats and one of both (AG)n and (TG)n repeats. By means of an innovative procedure small colony fragments were minimally treated to serve as templates for PCR with microsatellite-specific primers. Four of the loci were polymorphic: 7-8 discrete alleles were scored in nine colonies, heterozygosity ranging between 44-80%. At locus number 811 spacing of the alleles and gel-resolution were highest, therefore, ten additional colonies were typed and in total nine alleles were scored with maximal allelic interval of 120 base pair and 53% heterozygous colonies. The high levels of microsatellite-polymorphism provide a new tool as individual markers for studies on aspects of the botryllid polymorphic allorecognition system.

Animals↗
PubMed1994

Immunoglobulin-like domain is present in the extracellular part of the receptor tyrosine kinase from the marine sponge Geodia cydonium.

We have isolated and characterized two cDNAs from the marine sponge Geodia cydonium coding for a new member of a receptor tyrosine kinase of class II. The deduced amino acid sequence shows two characteristic domains: (i) the tyrosine kinase domain; and (ii) an immunoglobulin-like domain. The latter part shows high homology to the vertebrate C2 type immunoglobulin domain. This result demonstrates that immunoglobulin domains are not recent achievements of higher animals but exist also in those animals which have diverged from other organisms about 800 million years ago.

Amino Acid Sequence↗
PubMed1994

Ubiquitin and ubiquitination in cells from the marine sponge Geodia cydonium.

Marine sponges, e.g. Geodia cydonium, have been intensively used to investigate the biochemical and molecular biological basis of cell-cell- and cell-matrix adhesion. It has been shown that a family of galactose-specific lectins, which are present in the extracellular space of G. cydonium, is a main component involved in cell-matrix adhesion in the sponge system. In the present study it is outlined that the purified 16-kDa lectin-1 binds to a 67-kDa membrane-associated protein. This lectin-binding protein undergoes mono- and diubiquitination after incubation of dissociated sponge cells with the homologous aggregation factor (AF), a molecule involved in cell-cell adhesion. The gene coding for polyubiquitin was characterized and found to be composed of three tandem repeat building blocks. Northern analysis indicated the presence of only one type of ubiquitin-specific mRNA (1.65 kb). The level of this transcript increased by 10-fold after incubation of the dissociated cells with AF for 8 h; in contrast, lectin-1 caused only a small effect on the steady-state level of ubiquitin mRNA. These data indicate that the expression of the polyubiquitin gene is directly or indirectly regulated by the AF and suggest that ubiquitination might be a process which controls the function of the membrane-associated lectin-binding protein during matrix-cell adhesion.

Amino Acid Sequence↗
PubMed1994

Cell adhesion receptors and nuclear receptors are highly conserved from the lowest metazoa (marine sponges) to vertebrates.

The shift from unicellular life to multicellular, integrated organisms has been accompanied by the acquisition of adhesion proteins/receptors. Recently we succeeded to clone some genes coding for such proteins from the lowest multicellular animals, the marine sponges (model: the siliceous sponge Geodia cydonium). G. cydonium contains e.g. several lectins; cDNAs for two of them were cloned. Both lectins have a framework sequence of 38 conserved amino acids which are characteristic for the carbohydrate binding site of vertebrate S-type lectins. Next, the cDNA coding for a receptor tyrosine kinase of class II was isolated and characterized. The deduced aa sequence shows two characteristic domains; (i) the tyrosine kinase domain and (ii) an immunoglobulin-like domain. The latter part displays high homology to the vertebrate type immunoglobulin domain. This result together with the lectin data demonstrates that binding domains of such adhesion proteins are not recent achievements of higher animals but exist already in animals (sponges) which have diverged from other organisms about 800 million years ago. Considering the fact that during embryogenesis of sponges a typical anteroposterior organization pattern is seen a 'home-otic' organ-like transformation has been postulated. The subsequent search for genes provided with the homeodomain-like sequence was successful. These data support the view that the kingdom Animalia is of monophyletic origin.

Amino Acid Sequence↗
PubMed1994

Molecular cloning and localization of a novel serine protease from the colonial tunicate Botryllus schlosseri.

A cDNA encoding a putative serine protease was isolated and characterized from Botryllus schlosseri, a colonial protochordate. The open-reading frame of the 846 bp cDNA is 744-nt long. The deduced aa sequence predicts a protein of 26,134 D, with the signature of chymotrypsin. The mRNA of the protease is expressed only in the zooids as a single 0.9-kb transcript. No transcript was found in the tunic matrix (test). Surprisingly, a 3.7-fold higher enzyme activity was found in the test, compared with the zooids. We propose that this serine protease may have a role as a biologically active compound in the defense mechanisms against epibionts or as part of the effector mechanisms expressed in allogeneic and xenogeneic interactions.

Amino Acid Sequence↗
PubMed1993

cDNA cloning of a putative protochordate FK506-binding protein.

A tunicate (Botryllus schlossert) cDNA library was screened with a microsatellite probe. Five positive clones were sequenced, each with a 5' truncated microsatellite. One (Bs.6) revealed striking similarity to FK506 and rapamycin-binding proteins (FKBPs). Clone Bs.6 is 500 base pairs long and encodes for a putative protein of 134 amino acids. The predicted protein features the two FKBP-type peptidyl-prolyl cis-trans isomerase (PPIase) signatures and an endoplasmic reticulum retention signal. This protochordate protein is substantially similar to 12-13 kDa FKBPs, most remarkably to one of the receptors that had been proposed to mediate the immunosuppressive actions of FK506, the human FKBP-13 (62% amino acid identity and 74% similarity).

Amino Acid Sequence↗
PubMed1993

Cloning of the polyubiquitin cDNA from the marine sponge Geodia cydonium and its preferential expression during reaggregation of cells.

Ubiquitination of proteins is a critical step in the controlled degradation process of many polypeptides. Here we show that sponges, the simplest multicellular group of eukaryotic organisms, are also equipped with the ubiquitin pathway. The polyubiquitin cDNA was isolated and characterized from the marine sponge Geodia cydonium. The open reading frame contains six ubiquitin moieties, which are lined up head to tail without spacers. A comparison of the predicted amino acid sequence of the six sponge ubiquitin-coding units with those from other organisms revealed a high degree of homology (> 93%). The ubiquitin gene is expressed to almost the same extent in the two main compartments of the sponge, the cortex and the medulla. However, only in the cortex are detectable amounts of the ubiquitin protein synthesized. The ubiquitin protein isolated from the sponge organism was found to initiate protein degradation in the heterologous reticulocyte system in the same manner as bovine ubiquitin. In vitro studies with dissociated sponge cells revealed that the homologous aggregation factor causes (i) a strong increase in the steady-state level of mRNA coding for ubiquitin and (ii) a drastic increase in ubiquitin protein synthesis, while the homologous lectin failed to display that effect in isolated cells. These data suggest that ubiquitin may play a role in sponge morphogenesis.

Adenosine Triphosphate↗
PubMed1992

Incidents of rejection and indifference in Fu/HC incompatible protochordate colonies.

We test here for the existence of specific alloimmune memory in the rejection responses of the colonial tunicate Botryllus schlosseri. Colony specificity in these organisms is controlled by the Fu/HC locus. Rejection occurs only between colonies that do not share any allelic determinant at this locus. Two sets of experiments were conducted: 1) Forty-nine pairs of nonfusible oozooids were interacted naturally along a period of several months. They rejected, disconnected, and in 20% of the cases, interacted again. 2) Repeated colony allorecognition assays were done on 15 pairs of interacting subclones (up to 5 consecutive tests/pair). Major results indicate: 1) Not all ampulla-ampulla interactions resulted in necrotic areas, points of rejection (PORs). 2) A full repertoire of PORs was attained within the first 10 days. Thereafter, no more PORs were added. 3) The outcome of indifference (cases where ampulla-ampulla contacts did not result in rejection) was repeatedly recorded in multiple tests, and its frequency increased in the secondary and tertiary tests along a set of 5 consecutive tests. It is concluded that allospecific memory, as measured by an accelerated production of PORs and amplification in their number, was not characteristic of the Botryllus rejection phenomenon, which, however, reveals the qualities of a low responder. These results are discussed in the light of some aspects of tolerance in the mammalian system.

Animals↗