-
Developmental Biology Apr 2019The extracorporeal vasculature of the colonial ascidian Botryllus schlosseri plays a key role in several biological processes: transporting blood, angiogenesis,... (Review)
Review
The extracorporeal vasculature of the colonial ascidian Botryllus schlosseri plays a key role in several biological processes: transporting blood, angiogenesis, regeneration, self-nonself recognition, and parabiosis. The vasculature also interconnects all individuals in a colony and is composed of a single layer of ectodermally-derived cells. These cells form a tube with the basal lamina facing the lumen, and the apical side facing an extracellular matrix that consists of cellulose and other proteins, known as the tunic. Vascular tissue is transparent and can cover several square centimeters, which is much larger than any single individual within the colony. It forms a network that ramifies and expands to the perimeter of each colony and terminates into oval-shaped protrusions known as ampullae. Botryllus individuals replace themselves through a weekly budding cycle, and vasculature is added to ensure the interconnection of each new individual, thus there is continuous angiogenesis occurring naturally. The vascular tissue itself is highly regenerative; surgical removal of the ampullae and peripheral vasculature triggers regrowth within 24-48 h, which includes forming new ampullae. When two individuals, whether in the wild or in the lab, come into close contact and their ampullae touch, they can either undergo parabiosis through anastomosing vessels, or reject vascular fusion. The vasculature is easily manipulated by direct means such as microinjections, microsurgeries, and pharmacological reagents. Its transparent nature allows for in vivo analysis by bright field and fluorescence microscopy. Here we review the techniques and approaches developed to study the different biological processes that involve the extracorporeal vasculature.
Topics: Animals; Blood Vessels; Neovascularization, Physiologic; Parabiosis; Regeneration; Urochordata
PubMed: 30760410
DOI: 10.1016/j.ydbio.2018.10.013 -
Marine Drugs Feb 2022Patellamides are highly bioactive compounds found along with other cyanobactins in the symbiosis between didemnid ascidians and the enigmatic cyanobacterium . The... (Review)
Review
Patellamides are highly bioactive compounds found along with other cyanobactins in the symbiosis between didemnid ascidians and the enigmatic cyanobacterium . The biosynthetic pathway of patellamide synthesis is well understood, the relevant operons have been identified in the genome and genes involved in patellamide synthesis are among the most highly transcribed cyanobacterial genes in hospite. However, a more detailed study of the in vivo dynamics of patellamides and their function in the ascidian- symbiosis is complicated by the fact that remains uncultivated despite numerous attempts since its discovery in 1975. A major challenge is to account for the highly dynamic microenvironmental conditions experienced by in hospite, where light-dark cycles drive rapid shifts between hyperoxia and anoxia as well as pH variations from pH ~6 to ~10. Recently, work on patellamide analogues has pointed out a range of different catalytic functions of patellamide that could prove essential for the ascidian- symbiosis and could be modulated by the strong microenvironmental dynamics. Here, we review fundamental properties of patellamides and their occurrence and dynamics in vitro and in vivo. We discuss possible functions of patellamides in the ascidian- symbiosis and identify important knowledge gaps and needs for further experimental studies.
Topics: Animals; Humans; Hydrogen-Ion Concentration; Peptides, Cyclic; Prochloron; Symbiosis; Urochordata
PubMed: 35200648
DOI: 10.3390/md20020119 -
Genome Biology and Evolution Jul 2014Tunicates have been extensively studied because of their crucial phylogenetic location (the closest living relatives of vertebrates) and particular developmental plan.... (Review)
Review
Tunicates have been extensively studied because of their crucial phylogenetic location (the closest living relatives of vertebrates) and particular developmental plan. Recent genome efforts have disclosed that tunicates are also remarkable in their genome organization and molecular evolutionary patterns. Here, we review these latter aspects, comparing the similarities and specificities of two model species of the group: Oikopleura dioica and Ciona intestinalis. These species exhibit great genome plasticity and Oikopleura in particular has undergone a process of extreme genome reduction and compaction that can be explained in part by gene loss, but is mostly due to other mechanisms such as shortening of intergenic distances and introns, and scarcity of mobile elements. In Ciona, genome reorganization was less severe being more similar to the other chordates in several aspects. Rates and patterns of molecular evolution are also peculiar in tunicates, being Ciona about 50% faster than vertebrates and Oikopleura three times faster. In fact, the latter species is considered as the fastest evolving metazoan recorded so far. Two processes of increase in evolutionary rates have taken place in tunicates. One of them is more extreme, and basically restricted to genes encoding regulatory proteins (transcription regulators, chromatin remodeling proteins, and metabolic regulators), and the other one is less pronounced but affects the whole genome. Very likely adaptive evolution has played a very significant role in the first, whereas the functional and/or evolutionary causes of the second are less clear and the evidence is not conclusive. The evidences supporting the incidence of increased mutation and less efficient negative selection are presented and discussed.
Topics: Animals; Evolution, Molecular; Genome; Urochordata
PubMed: 25008364
DOI: 10.1093/gbe/evu122 -
Marine Drugs Oct 2018Ascidians are a class of sessile filter-feeding invertebrates, that provide unique and fertile niches harboring various microorganisms, such as bacteria, actinobacteria,... (Review)
Review
Ascidians are a class of sessile filter-feeding invertebrates, that provide unique and fertile niches harboring various microorganisms, such as bacteria, actinobacteria, cyanobacteria and fungi. Over 1000 natural products, including alkaloids, cyclic peptides, and polyketides, have been isolated from them, which display diverse properties, such as antibacterial, antifungal, antitumor, and anti-inflammatory activities. Strikingly, direct evidence has confirmed that ~8% of natural products from ascidians are actually produced by symbiotic microorganisms. In this review, we present 150 natural products from microorganisms associated with ascidians that have been reported up to 2017.
Topics: Animals; Anti-Infective Agents; Biological Products; Humans; Urochordata
PubMed: 30275404
DOI: 10.3390/md16100362 -
Developmental Biology Apr 2019
Topics: Animals; Embryonic Development; Models, Biological; Notochord; Urochordata
PubMed: 30803728
DOI: 10.1016/j.ydbio.2019.02.007 -
Current Biology : CB Sep 2002
Topics: Animals; Ciona intestinalis; Urochordata
PubMed: 12372262
DOI: 10.1016/s0960-9822(02)01129-6 -
Marine Drugs May 2021Marine tunicates are identified as a potential source of marine natural products (MNPs), demonstrating a wide range of biological properties, like antimicrobial and... (Review)
Review
Marine tunicates are identified as a potential source of marine natural products (MNPs), demonstrating a wide range of biological properties, like antimicrobial and anticancer activities. The symbiotic relationship between tunicates and specific microbial groups has revealed the acquisition of microbial compounds by tunicates for defensive purpose. For instance, yellow pigmented compounds, "tambjamines", produced by the tunicate, (Sluiter, 1909), primarily originated from their bacterial symbionts, which are involved in their chemical defense function, indicating the ecological role of symbiotic microbial association with tunicates. This review has garnered comprehensive literature on MNPs produced by tunicates and their symbiotic microbionts. Various sections covered in this review include tunicates' ecological functions, biological activities, such as antimicrobial, antitumor, and anticancer activities, metabolic origins, utilization of invasive tunicates, and research gaps. Apart from the literature content, 20 different chemical databases were explored to identify tunicates-derived MNPs. In addition, the management and exploitation of tunicate resources in the global oceans are detailed for their ecological and biotechnological implications.
Topics: Animals; Anti-Infective Agents; Antineoplastic Agents; Biological Products; Humans; Urochordata
PubMed: 34073515
DOI: 10.3390/md19060308 -
Developmental Biology Apr 2019Regenerative ability is highly variable among the metazoans. While many invertebrate organisms are capable of complete regeneration of entire bodies and organs,... (Review)
Review
Regenerative ability is highly variable among the metazoans. While many invertebrate organisms are capable of complete regeneration of entire bodies and organs, whole-organ regeneration is limited to very few species in the vertebrate lineages. Tunicates, which are invertebrate chordates and the closest extant relatives of the vertebrates, show robust regenerative ability. Colonial ascidians of the family of the Styelidae, such as several species of Botrylloides, are able to regenerate entire new bodies from nothing but fragments of vasculature, and they are the only chordates that are capable of whole body regeneration. The cell types and signaling pathways involved in whole body regeneration are not well understood, but some evidence suggests that blood borne cells may play a role. Solitary ascidians such as Ciona can regenerate the oral siphon and their central nervous system, and stem cells located in the branchial sac are required for this regeneration. Here, we summarize the cellular and molecular mechanisms of tunicate regeneration that have been identified so far and discuss differences and similarities between these mechanisms in regenerating tunicate species.
Topics: Animals; Central Nervous System; Epithelium; Regeneration; Stem Cells; Urochordata
PubMed: 30521811
DOI: 10.1016/j.ydbio.2018.11.021 -
Developmental and Comparative Immunology Jan 2015Allorecognition has been well-studied in the context of vertebrate adaptive immunity and recognition of the Major Histocompatibility Complex (MHC), which is the central... (Review)
Review
Allorecognition has been well-studied in the context of vertebrate adaptive immunity and recognition of the Major Histocompatibility Complex (MHC), which is the central event of vertebrate immune responses. Although allorecognition systems have been identified throughout the metazoa, recent results have shown that there is no apparent conservation or orthologous relationship between the mechanisms underlying this phenomenon in different organisms. Thus the origin of the vertebrate adaptive immune system as well as these other complex recognition systems is a complete mystery. This review will focus on allorecognition in Botryllus schlosseri, a basal chordate which undergoes a natural transplantation reaction following contact between two individuals, and, analogous to vertebrates, is controlled by a single locus. We will summarize each of the known candidate genes within this locus and their potential roles in allorecognition, and speculate on how these findings may in fact be revealing potential functional relationships between disparate allorecognition systems.
Topics: Adaptive Immunity; Animals; Histocompatibility; Immunity, Innate; Major Histocompatibility Complex; Urochordata
PubMed: 24709050
DOI: 10.1016/j.dci.2014.03.014 -
Natural Product Reports Feb 2004This review covers the literature published in 2002 for marine natural products, with 579 citations (413 for the period January to December 2002) referring to compounds... (Review)
Review
This review covers the literature published in 2002 for marine natural products, with 579 citations (413 for the period January to December 2002) referring to compounds isolated from marine microorganisms and phytoplankton, green algae, brown algae, red algae, sponges, coelenterates, bryozoans, molluscs, tunicates and echinoderms. The emphasis is on new compounds (677 for 2002), together with their relevant biological activities, source organisms and country of origin. Syntheses that lead to the revision of structures or stereochemistries have been included (114), including any first total syntheses of a marine natural product.
Topics: Animals; Biological Products; Bryozoa; Cnidaria; Echinodermata; Eukaryota; Marine Biology; Molecular Structure; Mollusca; Phytoplankton; Porifera; Urochordata
PubMed: 15039834
DOI: 10.1039/b305250h