scholarly journals The development and neuronal complexity of bipinnaria larvae of the sea star Asterias rubens

2021 ◽  
Author(s):  
Hugh F. Carter ◽  
Jeffrey R. Thompson ◽  
Maurice R. Elphick ◽  
Paola Oliveri
Keyword(s):  
Nervous System ◽  
Sea Urchins ◽  
Developmental Studies ◽  
Sea Star ◽  
Asterias Rubens ◽  
Sea Stars ◽  
Experimental Systems ◽  
Developmental Progression ◽  
Staining Methods ◽  
Molecular Anatomy

AbstractFree-swimming planktonic larvae are a key stage in the development of many marine phyla, and studies of these organisms have contributed to our understanding of major genetic and evolutionary processes. Although transitory, these larvae often attain a remarkable degree of tissue complexity, with well-defined musculature and nervous systems. Amongst the best studied are larvae belonging to the phylum Echinodermata, but with work largely focused on the pleuteus larvae of sea urchins (class Echinoidea). The greatest diversity of larval strategies amongst echinoderms is found in the class Asteroidea (sea-stars), organisms that are rapidly emerging as experimental systems for genetic and developmental studies. However, the bipinnaria larvae of sea stars have only been studied in detail in a small number of species and the full complexity of the nervous system is, in particular, poorly understood. Here we have analysed embryonic development and bipinnaria larval anatomy in the common North Atlantic sea-star Asterias rubens, employing use of a variety of staining methods in combination with confocal microscopy. Importantly, the complexity of the nervous system of bipinnaria larvae was revealed in greater detail than ever before, with identification of at least three centres of neuronal complexity: the anterior apical organ, oral region and ciliary bands. Furthermore, the anatomy of the musculature and sites of cell division in bipinnaria larvae were analysed. Comparisons of developmental progression and molecular anatomy across the Echinodermata provided a basis for hypotheses on the shared evolutionary and developmental processes that have shaped this group of animals. We conclude that bipinnaria larvae appear to be remarkably conserved across ~200 million years of evolutionary time and may represent a strong evolutionary and/or developmental constraint for species utilizing this larval strategy.

scholarly journals Jenis-Jenis Bintang Laut Dan Bulu Babi (Asteroidea, Echinoidea: Echinodermata) Di Perairan Pulau Cilik, Kepulauan Karimunjawa

2018 ◽  
Vol 21 (1) ◽  
pp. 41
Author(s):  
Retno Hartati ◽  
Endika Meirawati ◽  
Sri Redjeki ◽  
Ita Riniatsih ◽  
Robertus Triaji Mahendrajaya
Keyword(s):  
Sea Urchin ◽  
Sea Urchins ◽  
Habitat Type ◽  
Line Transect ◽  
Sea Star ◽  
Acanthaster Planci ◽  
Sea Stars ◽  
Transect Line ◽  
Linckia Laevigata ◽  
Diadema Setosum

Abstract Types of Star Fish and Sea Urchins (Asteroidea, Echinoidea: Echinodermata) In Cilik Island, Karimunjawa WatersEchinoderms are fundamentally good indicators of health and status of coralline communities in marine waters.  Substrat of  sandy, rububle and coral reefs are good habitat for Asteroidea dan Echinoidea.  This study aim to identify sea star (Asteroidea) and sea urchin (Echinoidea) species from Pulau Cilik waters of Karimunjawa Islands. Asteroidea and Echinoidea observed using the line transect method used, ie subjects within the same distance between the transect and the transect square with observations of 2.5 m on the right and left of transect line line. Morphology, habitat type (substrate & depth) and total number of sea stars and sea urchins at each station were determined. The results showed that Pulau Cilik has six species of Asteroidea (Sea star), ie Linckia laevigata, L. multifora, Neoferdifla ocellata (Family Ophidiasteridae), Luidia alternate (Luidiidae Family), Culcita novaeguineae (Family Oreasteridae) and Acanthaster planci which belongs to Family Acanthasteridae. There were 4 species of Echinoidea Sea urchin) found, i.e. Diadema setosum, D. antillarum, D. savignyi and Echinothrix calamaris, which all were family members of Diadematidae Keywords: Ophidiasteridae, Luidiidae, Oreasteridae, Acanthasteridae, Diadematidae AbstrakEchinodermata pada dasarnya merupakan indikator kesehatan dan status dari terumbu karang di laut. Dasar perairan yang landai dengan substrat pasir, terumbu karang dan pecahan karang yang merupakan habitat bagi hewan jenis Asteroidea dan Echinoidea. Penelitian ini bertujuan untuk mengidentifikasi henis-jenis bitang laut dan bulu babi dari perairan Pulau Cilik, Kepulauan Karimunjawa. Pengamatan Asteroidea dan Echinoidea menggunakan metoda line transect yang dimodifikasi, yaitu mengamati subjek dalam jarak yang sama sepanjang garis transect dan kuadrat transect dengan pengamatan 2,5 m di sebelah kanan dan kiri garis line transect. Morfologi, tipe habitat (substrat & kedalaman) dan jumlah total bintang laut dan bulu babi di tiap stasiun dicatat selanjutnya sampel diidentifikasi berdasarkan ciri morfologi tersebut. Hasil penelitian menunjukkan bahwa di perairan Pulau Cilik ditemukan enam spesies Asteroidea (Bintang Laut), yaitu Linckia laevigata, L. multifora, Neoferdifla ocellata (Famili Ophidiasteridae), Luidia alternate (Famili Luidiidae), Culcita novaeguineae (Famili Oreasteridae) dan Acanthaster planci yang termasuk dalam Famili Acanthasteridae. Species Echinoidea (Bulu Babi) ditemukan 4 spesies  Diadema setosum, D. antillarum, D. savignyi dan Echinothrix calamaris  semua anggota famili Diadematidae.Kata kunci : Ophidiasteridae, Luidiidae, Oreasteridae, Acanthasteridae, Diadematidae

A study of the temporary adhesion of the podia in the sea star asterias rubens (Echinodermata, asteroidea) through their footprints

1998 ◽  
Vol 201 (16) ◽  
pp. 2383-2395 ◽  
Author(s):  
P Flammang ◽  
A Michel ◽  
AV Cauwenberge ◽  
H Alexandre ◽  
M Jangoux
Keyword(s):  
Chemical Composition ◽  
Polyclonal Antibodies ◽  
Secretory Granules ◽  
Uronic Acids ◽  
Sea Star ◽  
Asterias Rubens ◽  
Sea Stars ◽  
Adhesive Material ◽  
Outermost Layer ◽  
Protein Moiety

Sea stars are able to make firm but temporary attachments to various substrata owing to secretions released by their podia. A duo-glandular model has been proposed in which an adhesive material is released by two types of non-ciliated secretory (NCS1 and NCS2) cells and a de-adhesive material is released by ciliated secretory (CS) cells. The chemical composition of these materials and the way in which they function have been investigated by studying the adhesive footprints left by the asteroids each time they adhere to a substratum. The footprints of Asterias rubens consist of a sponge-like material deposited as a thin layer on the substratum. Inorganic residues apart, this material is made up mainly of proteins and carbohydrates. The protein moiety contains significant amounts of both charged (especially acidic) and uncharged polar residues as well as half-cystine. The carbohydrate moiety is also acidic, comprising both uronic acids and sulphate groups. Polyclonal antibodies have been raised against footprint material and were used to locate the origin of footprint constituents in the podia. Extensive immunoreactivity was detected in the secretory granules of both NCS1 and NCS2 cells, suggesting that their secretions together make up the bulk of the adhesive material. No immunoreactivity was detected in the secretory granules of CS cells, and the only other structure strongly labelled was the outermost layer of the cuticle, the fuzzy coat. This pattern of immunoreactivity suggests that the secretions of CS cells are not incorporated into the footprints, but instead might function to jettison the fuzzy coat, thereby allowing the podium to detach.

Rate of natural mortality in the sea star Archaster angulatus (Echinodermata: Asteroidea)

2017 ◽  
Vol 98 (7) ◽  
pp. 1689-1693
Author(s):  
John K. Keesing
Keyword(s):  
Size Structure ◽  
Sea Urchins ◽  
Maximum Size ◽  
Life History Strategies ◽  
Natural Mortality ◽  
Sea Star ◽  
Sea Stars ◽  
Instantaneous Rate ◽  
Peak Abundance ◽  
Size At Age

The population size structure from a total of 876 individuals, together with published values of growth rate, maximum size and size at age were used to estimate an instantaneous rate of natural mortality (M) of 0.46–0.59 year−1 in a population of the sea star Archaster angulatus from south-western Australia. Peak abundance (17%) of all animals sampled was 105–109 mm arm radius (means of 4.2–4.8 years of age) and only one per cent of sea stars are predicted to live beyond 8 years in the population studied. There are few comparable studies on sea stars but when compared with rates of natural mortality in other echinoderms (sea urchins), A. angulatus is intermediate among species which exhibit the extremes of life history strategies, that is, those which grow very rapidly and may live just two years or less and those with very slow growth rates and which may live for decades.

scholarly journals The Use of Larval Sea Stars and Sea Urchins in the Discovery of Shared Mechanisms of Metazoan Whole-Body Regeneration

Genes ◽  
2021 ◽  
Vol 12 (7) ◽  
pp. 1063
Author(s):  
Andrew Wolff ◽  
Veronica Hinman
Keyword(s):  
Sea Urchin ◽  
Sea Urchins ◽  
Whole Body ◽  
Life Stages ◽  
Sea Star ◽  
Sea Stars ◽  
Regenerative Capacity ◽  
New Models ◽  
Ability To Regenerate ◽  
New System

The ability to regenerate is scattered among the metazoan tree of life. Further still, regenerative capacity varies widely within these specific organisms. Numerous organisms, all with different regenerative capabilities, have been studied at length and key similarities and disparities in how regeneration occurs have been identified. In order to get a better grasp on understanding regeneration as a whole, we must search for new models that are capable of extensive regeneration, as well as those that have been under sampled in the literature. As invertebrate deuterostomes, echinoderms fit both of these requirements. Multiple members regenerate various tissue types at all life stages, including examples of whole-body regeneration. Interrogations in two highly studied echinoderms, the sea urchin and the sea star, have provided knowledge of tissue and whole-body regeneration at various life stages. Work has begun to examine regeneration in echinoderm larvae, a potential new system for understanding regenerative mechanisms in a basal deuterostome. Here, we review the ways these two animals’ larvae have been utilized as a model of regeneration.

scholarly journals Regeneration of the larval sea star nervous system by wounding induced respecification to the sox2 lineage

2021 ◽  
Author(s):  
Minyan Zheng ◽  
Olga Zueva ◽  
Veronica F Hinman
Keyword(s):  
Stem Cells ◽  
Nervous System ◽  
Regulatory Networks ◽  
Cell Tracking ◽  
Fluorescent Proteins ◽  
Traumatic Injury ◽  
Body Parts ◽  
Sea Star ◽  
Sea Stars ◽  
Bac Transgenesis

The ability to restore lost body parts following traumatic injury is a fascinating area of biology that challenges current understanding of the ontogeny of differentiation. The origin of new cells needed to regenerate lost tissue, and whether they are pluripotent stem cells, tissue-specific stem cells or have de- or trans- differentiated, remains one of the most important open questions in regeneration. Additionally, it is not clearly known whether developmental gene regulatory networks (GRNs) are reused to direct specification in these cells or whether regeneration specific networks are deployed. Echinoderms, including sea stars, have extensive ability for regeneration and have therefore been the subject of many thorough studies on the ultrastructural and molecular properties of cells needed for regeneration. However, the technologies for obtaining transgenic echinoderms are limited and tracking cells involved in regeneration, and thus identifying the cellular sources and potencies has proven challenging. In this study we develop new transgenic tools for cell tracking in the regenerating bipinnaria larva of the sea star Patira minaita. We show that the larval serotonergic nervous system can regenerate following decapitation. Using a BAC-transgenesis approach with photoconvertible fluorescent proteins, we show that expression of the pan ectodermal marker, sox2, is induced in previously sox2 minus cells at the wound site, even when cell division is inhibited. sox2+ cells give rise to new sox4+ neural precursors that then proceed along an embryonic neurogenesis pathway to reform the anterior nervous systems. sox2+ cells contribute to only neural and ectoderm lineages, indicating that these progenitors maintain their normal, embryonic lineage restriction. This indicates that sea star larval regeneration uses a combination of existing lineage-restricted stem cells, as well as respecification of cells into neural lineages, and at least partial reuse of developmental GRNs to regenerate their nervous system.

scholarly journals Regeneration of the larval sea star nervous system by wounding induced respecification to the sox2 lineage

eLife ◽  
2022 ◽  
Vol 11 ◽  
Author(s):  
Minyan Zheng ◽  
Olga Zueva ◽  
Veronica Hinman
Keyword(s):  
Stem Cells ◽  
Nervous System ◽  
Regulatory Networks ◽  
Fluorescent Proteins ◽  
Traumatic Injury ◽  
Body Parts ◽  
Sea Star ◽  
Sea Stars ◽  
Embryonic Neurogenesis ◽  
Bac Transgenesis

The ability to restore lost body parts following traumatic injury is a fascinating area of biology that challenges current understanding of the ontogeny of differentiation. The origin of new cells needed to regenerate lost tissue, and whether they are pluripotent stem cells, tissue-specific stem cells or have de- or trans- differentiated, remains one of the most important open questions in regeneration. Additionally, it is not clearly known whether developmental gene regulatory networks (GRNs) are reused to direct specification in these cells or whether regeneration specific networks are deployed. Echinoderms, including sea stars, have extensive ability for regeneration and have therefore been the subject of many thorough studies on the ultrastructural and molecular properties of cells needed for regeneration. However, the technologies for obtaining transgenic echinoderms are limited and tracking cells involved in regeneration, and thus identifying the cellular sources and potencies has proven challenging. In this study we develop new transgenic tools to follow the fate of populations of cells in the regenerating bipinnaria larva of the sea star Patira minaita. We show that the larval serotonergic nervous system can regenerate following decapitation. Using a BAC-transgenesis approach with photoconvertible fluorescent proteins, we show that expression of the pan ectodermal marker, sox2, is induced in previously sox2 minus cells at the wound site, even when cell division is inhibited. sox2+ cells give rise to new sox4+ neural precursors that then proceed along an embryonic neurogenesis pathway to reform the anterior nervous systems. sox2+ cells contribute to only neural and ectoderm lineages, indicating that these progenitors maintain their normal, embryonic lineage restriction. This indicates that sea star larval regeneration uses a combination of existing lineage restricted stem cells, as well as respecification of cells into neural lineages, and at least partial reuse of developmental GRNs to regenerate their nervous system.

scholarly journals Arm swapping autograft shows functional equivalency of five arms in sea stars

2019 ◽  
Author(s):  
Daiki Wakita ◽  
Hitoshi Aonuma ◽  
Shin Tochinai
Keyword(s):  
Sea Urchins ◽  
Positional Information ◽  
Radial Symmetry ◽  
Evolutionary Strategy ◽  
Tissue Formation ◽  
Sea Star ◽  
Sea Stars ◽  
Patiria Pectinifera ◽  
Functional Equivalency ◽  
Typical Shape

AbstractExtant echinoderms show five-part radial symmetry in typical shape. However, we can find some asymmetry in their details, represented by the madreporite position not at the center, different skeletal arrangement in two of the five rays of sea urchins, and a circular cavity formed by two-end closure. We suspect the existence of any difference in hidden information between the five. In our hypothesis, deep equivalency makes no issue in function even after exchanging the position of rays; otherwise, this autograft causes some trouble in behavior or tissue formation. For this attempt, we firstly developed a method to transplant an arm tip to the counterpart of another arm in the sea star Patiria pectinifera. As a result, seven arms were completely implanted—four into the original positions for a control and three into different positions—with underwater surgery where we sutured with nylon thread and physically prevented nearby tube feet extending. Based on our external and internal observation, each grafted arm (i) gradually recovered movement coordination with the proximal body, (ii) regenerated its lost half as in usual distal regeneration, and (iii) formed no irregular intercalation filling any positional gap at the suture, no matter whether two cut arms were swapped. We here suggest a deep symmetry among the five rays of sea stars not only in morphology but also in physiology, representing an evolutionary strategy that has given equal priority to all the radial directions. Moreover, our methodological notes for grafting a mass of body in sea stars would help echinoderm research involving positional information as well as immunology.

scholarly journals Evidence for a trophic cascade on rocky reefs following sea star mass mortality in British Columbia

PeerJ ◽  
2016 ◽  
Vol 4 ◽  
pp. e1980 ◽  
Author(s):  
Jessica A. Schultz ◽  
Ryan N. Cloutier ◽  
Isabelle M. Côté
Keyword(s):  
British Columbia ◽  
Trophic Cascade ◽  
Sea Urchins ◽  
Fold Increase ◽  
Mass Mortality ◽  
Strongylocentrotus Droebachiensis ◽  
Population Declines ◽  
Sea Star ◽  
Sea Stars ◽  
Study Sites

Echinoderm population collapses, driven by disease outbreaks and climatic events, may be important drivers of population dynamics, ecological shifts and biodiversity. The northeast Pacific recently experienced a mass mortality of sea stars. In Howe Sound, British Columbia, the sunflower starPycnopodia helianthoides—a previously abundant predator of bottom-dwelling invertebrates—began to show signs of a wasting syndrome in early September 2013, and dense aggregations disappeared from many sites in a matter of weeks. Here, we assess changes in subtidal community composition by comparing the abundance of fish, invertebrates and macroalgae at 20 sites in Howe Sound before and after the 2013 sea star mortality to evaluate evidence for a trophic cascade. We observed changes in the abundance of several species after the sea star mortality, most notably a four-fold increase in the number of green sea urchins,Strongylocentrotus droebachiensis, and a significant decline in kelp cover, which are together consistent with a trophic cascade. Qualitative data on the abundance of sunflower stars and green urchins from a citizen science database show that the patterns of echinoderm abundance detected at our study sites reflected wider local trends. The trophic cascade evident at the scale of Howe Sound was observed at half of the study sites. It remains unclear whether the urchin response was triggered directly, via a reduction in urchin mortality, or indirectly, via a shift in urchin distribution into areas previously occupied by the predatory sea stars. Understanding the ecological implications of sudden and extreme population declines may further elucidate the role of echinoderms in temperate seas, and provide insight into the resilience of marine ecosystems to biological disturbances.

H3 histone RNA in eggs and embryos of the sea star Pisaster ochraceus

1988 ◽  
Vol 66 (10) ◽  
pp. 1040-1044
Author(s):  
D. K. Banfield ◽  
J. D. G. Boom ◽  
B. M. Honda ◽  
M. J. Smith
Keyword(s):  
Sea Urchins ◽  
Transcript Abundance ◽  
Single Copy ◽  
Sea Star ◽  
Sea Stars ◽  
Pisaster Ochraceus ◽  
Homologous Sequences ◽  
Order Of Magnitude ◽  
Transcript Concentration ◽  
Rna Concentration

Unlike sea urchins, sea stars have little stored histone RNA in their eggs. In an effort to quantify this difference, we have measured H3 RNA concentration in eggs and embryos of the sea star Pisaster ochraceus. The amount of H3 transcript in P. ochraceus 12-h embryos has been measured by RNA excess hybridization kinetics, using a single-strand 32P-labelled coding sequence probe. There are 1 × 105 H3 transcripts in each 12-h embryo. Putative egg H3 transcript concentration was estimated by reciprocal plots. The number of egg H3 homologous sequences (150/egg) is at least an order of magnitude less than rare complex-class, single-copy nuclear DN A transcripts. Slot blots and Northern blots indicate that sea star embryos do not reach the level of H3 transcript abundance seen in sea urchins until at least 16 h of development.

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