Rejection patterns in botryllid ascidian immunity: the first tier of allorecognition

2005 ◽  
Vol 83 (1) ◽  
pp. 101-121 ◽  
Author(s):  
Baruch Rinkevich
Keyword(s):  
Evolutionary Ecology ◽  
Phylogenetic Position ◽  
Unique Type ◽  
Effector Cells ◽  
Shared Allele ◽  
Growth Phenomenon ◽  
Polymorphic Gene ◽  
Nonself Recognition ◽  
Prophenoloxidase System ◽  
Multicellular Organisms

Botryllid ascidians, a small but geographically widely distributed group of compound tunicates, are being used as a model system for the study of allorecognition. Botryllid ascidians possess a unique type of immunity. Pairs of colonies that meet through their extending ampullae either fuse to form a chimera or develop cytotoxic lesions at contact zones (rejection). This first tier of allorecognition is succeeded (in cases of fusion) by two additional tiers, not reviewed here (the colony resorption phenomenon and the phenomenon of somatic and germ cell parasitism). Fusion and rejection are controlled by a single highly polymorphic gene locus termed the fusibility/histocompatibility (Fu/HC) locus. One shared allele on the Fu/HC locus is enough for fusion. Rejecting colonies do not share any Fu/HC alleles. To date, 14 botryllid ascidians have been studied for their fusibility patterns; of these, the cosmopolitan species Botryllus schlosseri (Pallas, 1766) has emerged as the most studied taxon. This review summarizes studies revealing the various types of noncompatible responses that are expressed following the application of the "colony allorecognition assay" and the "cut surface assay". These include divergent alloresponses related to different populations of the same botryllid species, distinctive allorecognition sites, polymorphism and a repertoire of Fu/HC alleles, a state of low responsiveness as opposed to the expected immunological memory, the retreat growth phenomenon, and the irreversible nature of the rejection process. A detailed description of the accumulated knowledge on the effector cells (morula cells and macrophages), the humoral and cellular molecules (at the biochemical and molecular levels), and the prophenoloxidase system is given. Links between allogeneic responses and the evolutionary ecology of botryllid ascidians are revealed. Since tunicates occupy a key phylogenetic position in the origin of the vertebrates, the study of colony allorecognition in this group may shed light on self/nonself recognition elements in other multicellular organisms, including vertebrates.

scholarly journals Perspectives on the evolutionary ecology of arthropod antimicrobial peptides

2016 ◽  
Vol 371 (1695) ◽  
pp. 20150297 ◽  
Author(s):  
Jens Rolff ◽  
Paul Schmid-Hempel
Keyword(s):  
Antimicrobial Peptides ◽  
Evolutionary Ecology ◽  
Expression Patterns ◽  
Extreme Environments ◽  
Infectious Agent ◽  
New Drugs ◽  
Stabilizing Selection ◽  
Immune Genes ◽  
Natural Systems ◽  
Multicellular Organisms

Antimicrobial peptides (AMPs) are important elements of the innate immune defence in multicellular organisms that target and kill microbes. Here, we reflect on the various points that are raised by the authors of the 11 contributions to a special issue of Philosophical Transactions on the ‘evolutionary ecology of arthropod antimicrobial peptides'. We see five interesting topics emerging. (i) AMP genes in insects, and perhaps in arthropods more generally, evolve much slower than most other immune genes. One explanation refers to the constraints set by AMPs being part of a finely tuned defence system. A new view argues that AMPs are under strong stabilizing selection. Regardless, this striking observation still invites many more questions than have been answered so far. (ii) AMPs almost always are expressed in combinations and sometimes show expression patterns that are dependent on the infectious agent. While it is often assumed that this can be explained by synergistic interactions, such interactions have rarely been demonstrated and need to be studied further. Moreover, how to define synergy in the first place remains difficult and needs to be addressed. (iii) AMPs play a very important role in mediating the interaction between a host and its mutualistic or commensal microbes. This has only been studied in a very small number of (insect) species. It has become clear that the very same AMPs play different roles in different situations and hence are under concurrent selection. (iv) Different environments shape the physiology of organisms; especially the host-associated microbial communities should impact on the evolution host AMPs. Studies in social insects and some organisms from extreme environments seem to support this notion, but, overall, the evidence for adaptation of AMPs to a given environment is scant. (v) AMPs are considered or already developed as new drugs in medicine. However, bacteria can evolve resistance to AMPs. Therefore, in the light of our limited understanding of AMP evolution in the natural context, and also the very limited understanding of the evolution of resistance against AMPs in bacteria in particular, caution is recommended. What is clear though is that study of the ecology and evolution of AMPs in natural systems could inform many of these outstanding questions, including those related to medical applications and pathogen control. This article is part of the themed issue ‘Evolutionary ecology of arthropod antimicrobial peptides’.

Cardiac myocytes cultured on a basement membrane extract of the ehs tumor

1986 ◽  
Vol 44 ◽  
pp. 270-271
Author(s):  
L. Terracio ◽  
A. Dewey ◽  
K. Rubin ◽  
T.K. Borg
Keyword(s):  
Extracellular Matrix ◽  
Basement Membrane ◽  
Cardiac Myocytes ◽  
Normal Tissue ◽  
Cell Spreading ◽  
Collagen Iv ◽  
Basement Membrane Extract ◽  
Membrane Extract ◽  
Growth Development ◽  
Multicellular Organisms

The recognition and interaction of cells with the extracellular matrix (ECM) effects the normal physiology as well as the pathology of all multicellular organisms. These interactions have been shown to influence the growth, development, and maintenance of normal tissue function. In previous studies, we have shown that neonatal cardiac myocytes specifically interacts with a variety of ECM components including fibronectin, laminin, and collagens I, III and IV. Culturing neonatal myocytes on laminin and collagen IV induces an increased rate of both cell spreading and sarcomerogenesis.

Apoptosis and development

2003 ◽  
Vol 39 ◽  
pp. 11-24 ◽  
Author(s):  
Justin V McCarthy
Keyword(s):  
Drosophila Melanogaster ◽  
Mammalian Cells ◽  
Cell Number ◽  
Model Organisms ◽  
Biological Processes ◽  
Nematode Caenorhabditis Elegans ◽  
Apoptotic Pathway ◽  
Genetic Pathways ◽  
Evolutionarily Conserved ◽  
Multicellular Organisms

Apoptosis is an evolutionarily conserved process used by multicellular organisms to developmentally regulate cell number or to eliminate cells that are potentially detrimental to the organism. The large diversity of regulators of apoptosis in mammalian cells and their numerous interactions complicate the analysis of their individual functions, particularly in development. The remarkable conservation of apoptotic mechanisms across species has allowed the genetic pathways of apoptosis determined in lower species, such as the nematode Caenorhabditis elegans and the fruitfly Drosophila melanogaster, to act as models for understanding the biology of apoptosis in mammalian cells. Though many components of the apoptotic pathway are conserved between species, the use of additional model organisms has revealed several important differences and supports the use of model organisms in deciphering complex biological processes such as apoptosis.

Plant peptide hormone signalling

2015 ◽  
Vol 58 ◽  
pp. 115-131 ◽  
Author(s):  
Ayane Motomitsu ◽  
Shinichiro Sawa ◽  
Takashi Ishida
Keyword(s):  
Communication Systems ◽  
Cell Communication ◽  
Peptide Hormone ◽  
Peptide Hormones ◽  
Target Cells ◽  
Signalling Molecules ◽  
Receptor Complexes ◽  
Environmental Responses ◽  
Plant Life Cycle ◽  
Multicellular Organisms

The ligand–receptor-based cell-to-cell communication system is one of the most important molecular bases for the establishment of complex multicellular organisms. Plants have evolved highly complex intercellular communication systems. Historical studies have identified several molecules, designated phytohormones, that function in these processes. Recent advances in molecular biological analyses have identified phytohormone receptors and signalling mediators, and have led to the discovery of numerous peptide-based signalling molecules. Subsequent analyses have revealed the involvement in and contribution of these peptides to multiple aspects of the plant life cycle, including development and environmental responses, similar to the functions of canonical phytohormones. On the basis of this knowledge, the view that these peptide hormones are pivotal regulators in plants is becoming increasingly accepted. Peptide hormones are transcribed from the genome and translated into peptides. However, these peptides generally undergo further post-translational modifications to enable them to exert their function. Peptide hormones are expressed in and secreted from specific cells or tissues. Apoplastic peptides are perceived by specialized receptors that are located at the surface of target cells. Peptide hormone–receptor complexes activate intracellular signalling through downstream molecules, including kinases and transcription factors, which then trigger cellular events. In this chapter we provide a comprehensive summary of the biological functions of peptide hormones, focusing on how they mature and the ways in which they modulate plant functions.

Phylogenetic position ofKontumia(Polypodiaceae) inferred from four chloroplast DNA regions

2012 ◽  
pp. n/a-n/a
Author(s):  
Changkyun Kim ◽  
Hong-Guang Zha ◽  
Tao Deng ◽  
Hang Sun ◽  
Su-Gong Wu
Keyword(s):  
Chloroplast Dna ◽  
Phylogenetic Position ◽  
Chloroplast Dna Regions

Role of Transcriptional Read-Through in PRE Activity in Drosophila melanogaster

Acta Naturae ◽  
2016 ◽  
Vol 8 (2) ◽  
pp. 79-86 ◽  
Author(s):  
P. V. Elizar’ev ◽  
D. V. Lomaev ◽  
D. A. Chetverina ◽  
P. G. Georgiev ◽  
M. M. Erokhin
Keyword(s):  
Dna Sequences ◽  
Cell Types ◽  
Transcription Terminator ◽  
Response Elements ◽  
Polycomb Response Elements ◽  
The Individual ◽  
Multicellular Organisms ◽  
Different Cell Types ◽  
Main Factor

Maintenance of the individual patterns of gene expression in different cell types is required for the differentiation and development of multicellular organisms. Expression of many genes is controlled by Polycomb (PcG) and Trithorax (TrxG) group proteins that act through association with chromatin. PcG/TrxG are assembled on the DNA sequences termed PREs (Polycomb Response Elements), the activity of which can be modulated and switched from repression to activation. In this study, we analyzed the influence of transcriptional read-through on PRE activity switch mediated by the yeast activator GAL4. We show that a transcription terminator inserted between the promoter and PRE doesnt prevent switching of PRE activity from repression to activation. We demonstrate that, independently of PRE orientation, high levels of transcription fail to dislodge PcG/TrxG proteins from PRE in the absence of a terminator. Thus, transcription is not the main factor required for PRE activity switch.

Paepalanthus fabianeae (Eriocaulaceae): A New Microendemic Species from a Morphologically Coherent Clade

2020 ◽  
Vol 45 (4) ◽  
pp. 794-801
Author(s):  
Caroline Oliveira Andrino ◽  
Marcelo Fragomeni Simon ◽  
Jair Eustáquio Quintino Faria ◽  
André Luiz da Costa Moreira ◽  
Paulo Takeo Sano
Keyword(s):  
New Species ◽  
Iucn Red List ◽  
Phylogenetic Position ◽  
Similar Species ◽  
Infrageneric Classification ◽  
Espinhaço Range ◽  
Nuclear Its ◽  
Two Populations

Abstract—We describe and illustrate Paepalanthus fabianeae, a new species of Eriocaulaceae from the central portion of the Espinhaço Range in Minas Gerais, Brazil. Previous phylogenetic evidence based on analyses of nuclear (ITS and ETS) and plastid (trnL-trnF and psba-trnH) sequences revealed P. fabianeae as belonging to a strongly supported and morphologically coherent clade containing five other species, all of them microendemic, restricted to the Espinhaço range. Due to the infrageneric classification of Paepalanthus being highly artificial, we preferred not assigning P. fabianeae to any infrageneric group. Paepalanthus fabianeae is known from two populations growing in campos rupestres (highland rocky fields) in the meridional Espinhaço Range. The species is characterized by pseudodichotomously branched stems, small, linear, recurved, and reflexed leaves, urceolate capitula, and bifid stigmas. Illustrations, photos, the phylogenetic position, and a detailed description, as well as comments on habitat, morphology, and affinities with similar species are provided. The restricted area of occurrence allied with threats to the quality of the habitat, mainly due to quartzite mining, justifies the preliminary classification of the new species in the Critically Endangered (CR) category using the guidelines and criteria of the IUCN Red List.

A new species of lambdarina (rhynchonellida, brachiopoda) from the viséan of central sudetes (Poland) and its phylogenetic position

2014 ◽  
Vol 64 (1) ◽  
pp. 1-12 ◽  
Author(s):  
Jolanta Muszer
Keyword(s):  
New Species ◽  
Full Range ◽  
Morphological Features ◽  
Phylogenetic Position ◽  
Growth Stages ◽  
Tropical Waters ◽  
Marginal Seas ◽  
Sw Poland ◽  
A New Species

Abstract A new species of micromorphic articulate brachiopod (Rhynchonellida) Lambdarina jugowiensis sp. nov., from the upper Visean (Sokolec Beds) of central Sudetes, SW Poland, is described. The studied specimens are calcified, what makes them unique in respect of their state of preservation. The material is represented by a full range of growth stages; from brephic to gerontic. Based on its morphological features and the palaeogeographical distribution of all its known species, two main evolutionary lines are proposed for the genus; the Australian and the European ones. Lambdarina was widely distributed in the equatorial-tropical waters of marginal seas of the Palaeotethys Ocean, mostly during Mississippian time.

Hemiflagellochloris (Chlorophyceae, Chlorophyta), a new for Russian flora genus of green algae

2014 ◽  
Vol 48 ◽  
pp. 104-113
Author(s):  
A. D. Temraleeva ◽  
E. V. Mincheva ◽  
Yu. S. Bukin ◽  
M. V. Eltsov ◽  
V. A. Demkin ◽  
...  
Keyword(s):  
Green Algae ◽  
Molecular Analysis ◽  
18S Rdna ◽  
Phylogenetic Position ◽  
Rdna Gene ◽  
Algal Strain ◽  
The North ◽  
Volgograd Region ◽  
First Time ◽  
18S Rdna Gene

The genus Hemiflagellochloris Watanabe et al. was found in Russia for the first time. The algal strain was isolated from a buried solonetz in the zone of dry steppes (the north-end of Ergeni Hills, Volgograd Region). The morphology and ecology of this isolate are described. Its phylogenetic position within Chlorophyceae is determined by molecular analysis of 18S rDNA gene.

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