Choosing the right home: settlement responses by larvae of six sea urchin species align with hydrodynamic traits of their contrasting adult habitats

2020 ◽  
Vol 190 (2) ◽  
pp. 737-756
Author(s):  
Jason Hodin ◽  
Matthew C Ferner ◽  
Brian Gaylord
Keyword(s):  
Sea Urchin ◽  
Sea Urchins ◽  
Life Cycles ◽  
Environmental Indicators ◽  
Comparative Approach ◽  
Sand Dollar ◽  
Fluid Turbulence ◽  
Adult Habitat ◽  
The Right ◽  
Benthic Animals

Abstract Ocean organisms as diverse as seaweeds and sea cucumbers exhibit life cycles in which dispersal occurs primarily via microscopic larvae or spores, with adults exhibiting limited or even no dispersal. In benthic animals, the larval stage concludes with irreversible settlement into the benthos. The decision of where and when to settle is thus one of substantial import. Prior work has shown that settlement in two shoreline echinoids (a sea urchin and a sand dollar) is unexpectedly sensitive to an environmental feature (intense fluid turbulence) that can be considered as a signal to larvae of their arrival in the neighbourhood of the hydrodynamically energetic habitats in which these taxa live as adults. Here, we used a comparative approach to explore the evolution of turbulence responsiveness in late-stage echinoid larvae. We examined three pairs of closely related sea urchins that differ in the energetic exposure of their adult habitats and found that larval responsiveness to turbulence was more pronounced in urchins that settle in more hydrodynamically exposed locations. These results raise the possibility that evolutionary differences in larval responsiveness to environmental indicators of appropriate adult habitat might reinforce or even provide a mechanism for vicariance in the ocean.

scholarly journals SEROLOGICAL SIMILARITY OF FLAGELLAR AND MITOTIC MICROTUBULES

1971 ◽  
Vol 50 (3) ◽  
pp. 762-773 ◽  
Author(s):  
Chandler Fulton ◽  
R. E. Kane ◽  
R. E. Stephens
Keyword(s):  
Sea Urchin ◽  
Sea Urchins ◽  
Antigenic Determinants ◽  
Sand Dollar ◽  
Central Pair ◽  
Arbacia Punctulata ◽  
Outer Fiber

An antiserum to flagellar axonemes from sperm of Arbacia punctulata contains antibodies which react both with intact flagellar outer fibers and with purified tubulin from the outer fibers. Immunodiffusion tests indicate the presence of similar antigenic determinants on outer-fiber tubulins from sperm flagella of five species of sea urchins and a sand dollar, but not a starfish. The antibodies also react with extracts containing tubulins from different classes of microtubules, including central-pair fibers and both A- and B-subfibers from outer fibers of sperm flagella, an extract from unfertilized eggs, mitotic apparatuses from first cleavage embryos, and cilia from later embryos. Though most tubulins tested share similar antigenic determinants, some clear differences have been detected, even, in Pseudoboletia indiana, between the outer-fiber tubulins of sperm flagella and blastular cilia. Though tubulins are "actin-like" proteins, antitubulin serum does not react with actin from sea urchin lantern muscle. On the basis of these observations, we suggest that various echinoid microtubules are built of similar, but not identical, tubulins.

scholarly journals Hormonal Regulation of Programmed Cell Death in Sea Urchin Metamorphosis

2021 ◽  
Vol 9 ◽  
Author(s):  
Hannah Wynen ◽  
Andreas Heyland
Keyword(s):  
Cell Death ◽  
Programmed Cell Death ◽  
Sea Urchin ◽  
Hormonal Regulation ◽  
Life Histories ◽  
Sea Urchins ◽  
Marine Invertebrate ◽  
Life Cycles ◽  
Benthic Habitat ◽  
Larval Body

Programmed cell death (PCD) has been identified as a key process in the metamorphic transition of indirectly developing organisms such as frogs and insects. Many marine invertebrate species with indirect development and biphasic life cycles face the challenge of completing the metamorphic transition of the larval body into a juvenile when they settle into the benthic habitat. Some key characteristics stand out during this transition in comparison to frogs and insects: (1) the transition is often remarkably fast and (2) the larval body is largely abandoned and few structures transition into the juvenile stage. In sea urchins, a group with a drastic and fast metamorphosis, development and destruction of the larval body is regulated by endocrine signals. Here we provide a brief review of the basic regulatory mechanisms of PCD in animals. We then narrow our discussion to metamorphosis with a specific emphasis on sea urchins with indirect life histories and discuss the function of thyroid hormones and histamine in larval development, metamorphosis and settlement of the sea urchin Strongylocentrotus purpuratus. We were able to annotate the large majority of PCD related genes in the sea urchin S. purpuratus and ongoing studies on sea urchin metamorphosis will shed light on the regulatory architecture underlying this dramatic life history transition. While we find overwhelming evidence for hormonal regulation of PCD in animals, especially in the context of metamorphosis, the mechanisms in many marine invertebrate groups with indirect life histories requires more work. Hence, we propose that studies of PCD in animals requires functional studies in whole organisms rather than isolated cells. We predict that future work, targeting a broader array of organisms will not only help to reveal important new functions of PCD but provide a fundamentally new perspective on its use in a diversity of taxonomic, developmental, and ecological contexts.

Left-right positioning of the adult rudiment in sea urchin larvae is directed by the right side

Development ◽  
2001 ◽  
Vol 128 (24) ◽  
pp. 4935-4948 ◽  
Author(s):  
Mizuki Aihara ◽  
Shonan Amemiya
Keyword(s):  
Cell Fate ◽  
Sea Urchin ◽  
Normal Development ◽  
Sea Urchins ◽  
Inhibitory Effect ◽  
Dependent Manner ◽  
Larval Stages ◽  
Adult Rudiment ◽  
The Right ◽  
Pluteus Stage

Indirect-developing sea urchins eventually form an adult rudiment on the left side through differential left-right development in the late larval stages. Components of the adult rudiment, such as the hydropore canal, the hydrocoel and the primary vestibule, all develop on the left side alone, and are the initial morphological traits that exhibit left-right differences. Although it has previously been shown that partial embryos dissected in cleavage stages correctly determine the normal left-right placement of the adult rudiment, the timing and the mechanism that determine left-right polarity during normal development remain unknown. In order to determine these, we have carried out a series of regional operations in two indirect-developing sea urchin species. We excised all or a part of tissue on the left or right side of the embryos during the early gastrula stage and the two-armed pluteus stage, and examined the left-right position of the adult rudiment, and of its components. Excisions of tissues on the left side of the embryos, regardless of stage, resulted in formation of a left adult rudiment, as in normal development. By contrast, excisions on the right side of the embryos resulted in three different types of impairment in the left-right placement of the adult rudiment in a stage-dependent manner. Generally, when the adult rudiment was definitively formed only on the right side of the larvae, no trace of basic development of the components of the adult rudiment was found on the left side, indicating that a right adult rudiment results from reversal of the initial left-right polarity but not from a later inhibitory effect on the development of an adult rudiment. Thus, we suggest that determination of the left-right placement of the adult rudiment depends on a process, which is directed by the right side, of polarity establishment during the gastrula and the prism stages; however, but commitment of the cell fate to initiate formation of the adult rudiment occurs later than the two-armed pluteus stage.

Anti-System Politics

2020 ◽  
Author(s):  
Jonathan Hopkin
Keyword(s):  
Comparative Approach ◽  
The European Union ◽  
Political Systems ◽  
The United Kingdom ◽  
The Us ◽  
Long Term Result ◽  
The Rich ◽  
Dramatic Shift ◽  
To Come ◽  
The Right

Recent elections in the advanced Western democracies have undermined the basic foundations of political systems that had previously beaten back all challenges—from both the Left and the Right. The election of Donald Trump to the US presidency, only months after the United Kingdom voted to leave the European Union, signaled a dramatic shift in the politics of the rich democracies. This book traces the evolution of this shift and argues that it is a long-term result of abandoning the postwar model of egalitarian capitalism in the 1970s. That shift entailed weakening the democratic process in favor of an opaque, technocratic form of governance that allows voters little opportunity to influence policy. With the financial crisis of the late 2000s, these arrangements became unsustainable, as incumbent politicians were unable to provide solutions to economic hardship. Electorates demanded change, and it had to come from outside the system. Using a comparative approach, the text explains why different kinds of anti-system politics emerge in different countries and how political and economic factors impact the degree of electoral instability that emerges. Finally, it discusses the implications of these changes, arguing that the only way for mainstream political forces to survive is for them to embrace a more activist role for government in protecting societies from economic turbulence.

Legal views of E. Olesnytsky

2020 ◽  
pp. 39-48
Author(s):  
Liubomyr Ilyn
Keyword(s):  
Legal Protection ◽  
Legal Culture ◽  
Political Activity ◽  
Practical Significance ◽  
Comparative Approach ◽  
Public Interests ◽  
Cooperative Movement ◽  
Special Scientific ◽  
General Scientific ◽  
The Right

Purpose. The purpose of the study is to analyze the legal and state views of E. Olesnytsky, in particular his assessment of imperial law, as well as practical activities as a lawyer and one of the initiators of the cooperative movement in Galicia in the early twentieth century. Methods. The methodological basis of the study was a set of general scientific, special scientific and philosophical methods, as well as the principles of historicism. The key was the biographical method and the comparative approach, which allowed to reveal the peculiarities of the formation of legal views of E. Olesnytsky. Findings. It is established that through the prism of the analysis of political and legal views of E. Olesnytsky it is possible not only to trace the level of legal culture, social and political activity of the population of Galicia, but also to determine the practical content of imperial legislation. The influence of I. Franko and socialist ideas in general on the legal views of E. Olesnytsky, who was one of the founders of the «Сhasopys Рravnycha», actively analyzed the imperial regional legislation for expediency, rationality and compliance with public interests. This work was key in raising the level of legal culture of the population, and after 1891 it was supplemented by the legal activity of E. Olesnytsky. Among the regional legislation, the lawyer's special attention was drawn to the right of propination, which gave large landowners a monopoly on the production and sale of alcohol. After 1901, E. Olesnytsky focused on the development and popularization of the cooperative movement in Galicia, including the legal protection of producers and sellers of agricultural products. Originality. The directions of E. Olesnytsky's professional and professional interests in the field of economic and financial law of Austria-Hungary, advocacy and organization of the cooperative movement are determined. Practical significance. The results of the study can be used in further historical and legal research, preparation of special courses.

Evidence for Association of Vibrio Echinoideorum with Tissue Necrosis on Body Shell of the Green Sea Urchin Strongylocentrotus Droebachiensis

2021 ◽  
Author(s):  
Jonathan Hira ◽  
Klara Stensvåg
Keyword(s):  
Sea Urchin ◽  
Virulence Genes ◽  
Vibrio Vulnificus ◽  
Sea Urchins ◽  
Opportunistic Pathogen ◽  
Significant Degree ◽  
Strongylocentrotus Droebachiensis ◽  
Host Immune System ◽  
Progressive Development ◽  
Green Sea Urchin

Abstract “Sea urchin lesion syndrome” is known as sea urchins disease with the progressive development of necrotic epidermal tissue and loss of external organs, including appendages on the outer body surface. Recently, a novel strain, Vibrio echinoideorum has been isolated from the lesions of green sea urchin (Strongylocentrotus droebachiensis), an economically important mariculture species in Norway. V. echinoideorum has not been reported elsewhere in association of with green sea urchin lesion syndrome. Therefore, in this study, an immersion based bacterial challenge experiment was performed to expose sea urchins (wounded and non-wounded) to V. echinoideorum, thereby mimicking a nearly natural host-pathogen interaction under controlled conditions. This infection experiment demonstrated that only the injured sea urchins developed the lesion to a significant degree when exposed to V. echinoideorum. Pure cultures of the employed bacterial strain was recovered from the infected animals and its identity was confirmed by the MALDI-TOF MS spectra profiling. Additionally, the hemolytic phenotype of V. echinoideorum substantiated its virulence potential towards the host, and this was also supported by the cytolytic effect on red spherule cells of sea urchins. Furthermore, the genome sequence of V. echinoideorum was assumed to encode potential virulence genes and were subjected for in silico comparison with the established virulence factors of Vibrio vulnificus and Vibrio tasmaniensis. This comparative virulence profile provided novel insights about virulence genes and their putative functions related to chemotaxis, adherence, invasion, evasion of the host immune system, and damage of host tissue and cells. Thus, it supports the pathogenicity of V. echinoideorum. In conclusion, the interaction of V. echinoideorum with injured sea urchins appears to be essential for the development of lesion syndrome and therefore, revealing its potentiality as an opportunistic pathogen.

Host use pattern and life history of Liopetrolisthes mitra, a crab associate of the black sea urchin Tetrapygus niger

2000 ◽  
Vol 80 (4) ◽  
pp. 639-645 ◽  
Author(s):  
J.A. Baeza ◽  
M. Thiel
Keyword(s):  
Sea Urchin ◽  
Black Sea ◽  
Sea Urchins ◽  
Austral Summer ◽  
Average Density ◽  
The Black Sea ◽  
Reproductive Pattern ◽  
Host Use ◽  
Austral Spring ◽  
Use Pattern

The porcellanid crab Liopetrolisthes mitra is a common associate of the black sea urchin, Tetrapygus niger in north central Chile. The host-use pattern, population dynamics and reproductive pattern of L. mitra on sea urchins were examined between January 1996 and February 1997. Each month, between 60 and 95 per cent of all collected urchins hosted crabs, with the highest frequency of cohabitation occurring during the austral summer (January to March). Group sizes of crabs on individual urchins ranged from 1 to 25 crabs per host. The average density of crabs on the urchins ranged from 2 to 5.5 crabs per host. Large urchins were inhabited by crabs more frequently than small urchins but urchin size had no effect on the number or size of crabs. The sex ratio of adult crabs was ˜1:1 during most months. Reproduction occurred throughout the year but was most intense during the austral spring and summer (October to March), when the highest percentage of ovigerous females were found. Similarly, recruitment of L. mitra occurred throughout the year but reached a peak during austral summer and early autumn (January to May). All life stages of L. mitra including recently settled megalopae and reproductive adults were found on urchins. Size–frequency analysis indicated that many crabs live >1.5 years. The results of this study confirm that the association between L. mitra and T. niger is strong and persists throughout the benthic life of the commensal crab.

scholarly journals British Right-Wing Anti-semitism, 1918-1930.

2021 ◽  
Author(s):  
◽  
Oliver Brown
Keyword(s):  
First World War ◽  
Primary Sources ◽  
Comparative Approach ◽  
Right Wing ◽  
World War ◽  
Anti Semitism ◽  
Wide Range ◽  
The First World War ◽  
The Right ◽  
First World

This thesis investigates the prevalence of anti-Semitism in the British right-wing between the years of 1918 and 1930. It aims to redress the imbalance of studies on interwar British right-wing anti-Semitism that are skewed towards the 1930s, Oswald Mosley and the British Union of Fascists. This thesis is the first to focus exclusively on the immediate aftermath of the First World War and the rest of the 1920s, to demonstrate how interwar British right-wing anti-Semitism was not an isolated product of the 1930s. This work shows that anti-Semitism was endemic throughout much of the right-wing in early interwar Britain but became pushed further away from the mainstream as the decade progressed. This thesis adopts a comparative approach of comparing the actions and ideology of different sections of the British right-wing. The three sections that it is investigating are the “mainstream”, the “anti-alien/anti-Bolshevik” right and the “Jewish-obsessive” fringe. This comparative approach illustrates the types of anti-Semitism that were widespread throughout the British right-wing. Furthermore, it demonstrates which variants of anti-Semitism remained on the fringes. This thesis will steer away from only focusing on the virulently anti-Semitic, fringe organisations. The overemphasis on peripheral figures and openly fascistic groups when historians have glanced back at the 1920s helped lead to an exaggerated view that Britain was a tolerant haven in historiographical pieces, at least up until the 1980s. This thesis is using a wide range of primary sources, that are representative of the different sections of the British right-wing.

scholarly journals Effects of five southern California macroalgal diets on consumption, growth, and gonad weight, in the purple sea urchin Strongylocentrotus purpuratus

2014 ◽  
Author(s):  
Matthew C Foster ◽  
Jarrett E Byrnes ◽  
Daniel C Reed
Keyword(s):  
Sea Urchin ◽  
Sea Urchins ◽  
Strongylocentrotus Purpuratus ◽  
Macrocystis Pyrifera ◽  
Reproductive Capacity ◽  
Giant Kelp ◽  
Mixed Diet ◽  
Gonad Weight ◽  
Consumption Growth ◽  
Purple Sea Urchin

Consumer growth and reproductive capacity are direct functions of diet. Strongylocentrotid sea urchins, the dominant herbivores in California kelp forests, strongly prefer giant kelp (Macrocystis pyrifera), but are highly catholic in their ability to consume other species. The biomass of Macrocystis fluctuates greatly in space and time and the extent to which urchins can use alternate species of algae or a mixed diet of multiple algal species to maintain fitness when giant kelp is unavailable is unknown. We experimentally examined the effects of single and mixed species diets on consumption, growth and gonad weight in the purple sea urchin Strongylocentrotus purpuratus. Urchins were fed single species diets consisting of one of four common species of macroalgae (the kelps Macrocystis pyrifera and Pterygophora californica, and the red algae Chondracanthus corymbiferus and Rhodymenia californica (hereafter referred to by genus) or a mixed diet containing all four species ad libitum over a 13-week period in a controlled laboratory setting. Urchins fed Chondracanthus, Macrocystis and a mixed diet showed the highest growth (in terms of test diameter, wet weight and jaw length) and gonad weight while urchins fed Pterygophora and Rhodymenia showed the lowest. Urchins consumed their preferred food, Macrocystis at the highest rate when offered a mixture, but consumed Chondracanthus or Macrocystis at similar rates when the two algae were offered alone. The differences in urchin feeding behavior and growth observed between these diet types suggest the relative availability of the algae tested here could affect urchin populations and their interactions with the algal assemblage. The fact that the performance of urchins fed Chondracanthus was similar or higher than those fed the preferred Macrocystis suggests purple sea urchins could sustain growth and reproduction during times of low Macrocystis abundance as is common following large wave events.

scholarly journals Contrasting recruitment seasonality of sea urchin species in Gran Canaria, Canary Islands (eastern Atlantic)

2014 ◽  
Vol 15 (3) ◽  
pp. 475 ◽  
Author(s):  
S. GARCIA-SANZ ◽  
P. G. NAVARRO ◽  
F. TUYA
Keyword(s):  
Community Structure ◽  
Seasonal Variation ◽  
Sea Urchin ◽  
Sea Urchins ◽  
Late Summer ◽  
Paracentrotus Lividus ◽  
Abundant Species ◽  
Late Winter ◽  
Gran Canaria ◽  
Arbacia Lixula

Despite sea-urchins can play an important role affecting the community structure of subtidal bottoms, factors controlling the dynamics of sea-urchin populations are still poorly understood. We assessed the seasonal variation in recruitment of three sea-urchin species (Diadema africanum, Paracentrotus lividus and Arbacia lixula) at Gran Canaria Island (eastern Atlantic) via monthly deployment of artificial collectors throughout an entire annual cycle on each of four adjacent habitat patches (seagrasses, sandy patches, ‘urchin-grazed’ barrens and macroalgal-dominated beds) within a shallow coastal landscape. Paracentrotus lividus and A. lixula had exclusively one main recruitment peak in late winter-spring. Diadema africanum recruitment was also seasonal, but recruits appeared in late summer-autumn, particularly on ‘urchin-grazed’ barrens with large abundances of adult conspecifics. In conclusion, this study has demonstrated non-overlapping seasonal recruitment patterns of the less abundant species (P. lividus and A. lixula) with the most conspicuous species (D. africanum) in the study area.

Sign in / Sign up

Export Citation Format

Share Document