The dopamine-synthesizing cells in the swimming larva of the tunicateCiona intestinalisare located only in the hypothalamus-related domain of the sensory vesicle

Recent molecular detection of vast microbial communities exclusively associated with sponges has made evident the need for a better understanding of the mechanisms by which these symbiotic microbes are handled and transferred from one sponge generation to another. This transmission electron microscopy (TEM) study investigated the occurrence of symbiotic bacteria in free-swimming larvae of two viviparous species (Haliclona caerulea and Corticium candelabrum) and spawned gametes of two oviparous species (Chondrilla nucula and Petrosia ficiformis). Complex microbial communities were found in these sponges, which in two cases included bacteria characterized by an intra-cytoplasmic membrane (ICM). When ICM-bearing and ICM-lacking bacteria co-existed, they were transferred following identical pathways. Nevertheless, the mechanism for microbial transference varied substantially between species. In C. nucula, a combination of intercellular symbiotic ICM-bearing and ICM-lacking bacteria, along with cyanobacteria and yeasts, were collected from the mesohyl by amoeboid nurse cells, then transported and transferred to the oocytes. In the case of Corticium candelabrum, intercellular bacteria did not enter the gametes, but spread into the division furrows of early embryos and proliferated in the central cavity of the free-swimming larva. Surprisingly, symbiotic bacteria were not vertically transmitted by P. ficiformis gametes or embryos, but apparently acquired from the environment by the juveniles of each new generation. This study failed to unravel the mechanism by which the intercellular endosymbiotic bacterium found in the central mesohyl of the H. caerulea larva got there. Nevertheless, the ultrastructure of this bacterial rod, which was characterized by a star-shaped cross section with nine radial protrusions, an ICM-bound riboplasm, and a putative membrane-bound acidocalcisome, suggested that it may represent a novel organization grade within the prokaryotes. It combines traits occurring in members of Poribacteria, Planctomycetes and Verrucomicrobia, emerging as one of the most complex prokaryotic architectures known to date.

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Effect of plasticity in hatching on duration as a precompetent swimming larva in the nudibranch Phestilla sibogae

Invertebrate Biology ◽

10.1111/j.1744-7410.2010.00212.x ◽

2010 ◽

Vol 129 (4) ◽

pp. 309-318 ◽

Cited By ~ 11

Author(s):

Richard R. Strathmann ◽

Megumi F. Strathmann ◽

Guadalupe Ruiz-Jones ◽

Michael G. Hadfield

Keyword(s):

Phestilla Sibogae ◽

Swimming Larva

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Molgula citrina (Alder and Hancock). Activities and structure of the free-swimming larva

Journal of Morphology ◽

10.1002/jmor.1050420205 ◽

1926 ◽

Vol 42 (2) ◽

pp. 453-471 ◽

Cited By ~ 30

Author(s):

Caswell Grave

Keyword(s):

Free Swimming ◽

Molgula Citrina ◽

Swimming Larva ◽

Free Swimming Larva

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Gene expression during echinoderm metamorphosis

Zygote ◽

10.1017/s0967199400130230 ◽

1999 ◽

Vol 8 (S1) ◽

pp. S48-S49

Author(s):

Gregory A. Wray

Keyword(s):

Sea Urchins ◽

Cell Types ◽

Small Populations ◽

Important Process ◽

Structural Genes ◽

Planktonic Larva ◽

Anatomical Changes ◽

Preparatory Phase ◽

Swimming Larva ◽

Complete Process

Metamorphosis is a remarkable process in echinoderms, transforming a bilaterally symmetrical planktonic larva into a radially symmetrical benthic adult. This shift in habitat involves functional and anatomical changes in virtually every organ system (Bury, 1895; MacBride, 1914; Okazaki, 1975). Although metamorphosis is a crucial process in echinoderm development, we know relatively little about it. Furthermore, most of what we do know concerns sea urchins, and even less information is available about metamorphosis in other echinoderms. We have examined the expression of regulatory and structural genes during metamorphosis in several different echinoderm species (Lowe & Wray, 1997 and unpublished results). These data, together with those from several recent studies concerning additional genes (reviewed in Wray & Lowe, 2000), are beginning to shed new light on this complex and important process in echinoderm development.The overt transformation from swimming larva to settled juvenile is quite rapid in echinoderms (Cameron & Hinegardner, 1978), requiring less than half an hour in many species. The complete process of metamorphosis takes much longer, however (Okazaki, 1975; Gosselin & Jangoux, 1998). Extensive preparations begin several days to weeks before settlement (MacBride, 1914; Okazaki, 1975), depending upon the species and upon environmental conditions (Strathmann et al., 1992). During this preparatory phase, initially small populations of ectodermal and mesodermal cells fated to become the adult proliferate, differentiate and undergo complex morphogenetic movements to form the imaginal rudiment (MacBride, 1914; Okazaki, 1975). The rudiment is more complex than the larva in several important ways: it contains a greater number of cell types, it is the first place where true tissues form, and it contains the first well-organised nervous system (Okazaki, 1975; Chia & Burke, 1978).

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The Vortex Wake of the Free-swimming Larva and Pupa of CULEX PIPIENS (Diptera)

Journal of Experimental Biology ◽

10.1242/jeb.204.11.1855 ◽

2001 ◽

Vol 204 (11) ◽

pp. 1855-1867 ◽

Cited By ~ 4

Author(s):

John Brackenbury

Keyword(s):

Reynolds Numbers ◽

High Amplitude ◽

The Body ◽

Ring Vortex ◽

Free Swimming ◽

Continuous Surface ◽

The Mean ◽

Swimming Larva ◽

Free Swimming Larva ◽

Visualisation Technique

SUMMARY The kinematics and hydrodynamics of free-swimming pupal and larval (final-instar) culicids were investigated using videography and a simple wake-visualisation technique (dyes). In both cases, swimming is based on a technique of high-amplitude, side-to-side (larva) or up-and-down (pupa) bending of the body. The pupa possesses a pair of plate-like abdominal paddles; the larval abdominal paddle consists of a fan of closely spaced bristles which, at the Reynolds numbers involved, behaves like a continuous surface. Wake visualisation showed that each half-stroke of the swimming cycle produces a discrete ring vortex that is convected away from the body. Consecutive vortices are produced first to one side then to the other of the mean swimming path, the convection axis being inclined at approximately 25° away from dead aft. Pupal and larval culicids therefore resemble fish in using the momentum injected into the water to generate thrust. Preliminary calculations for the pupa suggest that each vortex contains sufficient momentum to account for that added to the body with each half-stroke. The possibility is discussed that the side-to-side flexural technique may allow an interaction between body and tail flows in the production of vorticity.

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The Larvæ of Polydora ciliata Johnston and Polydora hoplura Claparède

Journal of the Marine Biological Association of the United Kingdom ◽

10.1017/s0025315400009553 ◽

1928 ◽

Vol 15 (2) ◽

pp. 567-603 ◽

Cited By ~ 54

Author(s):

Douglas P. Wilson

Keyword(s):

Late Stage ◽

Special Kind ◽

Polydora Ciliata ◽

Sensory Cilia ◽

Swimming Larva

SUMMARYThe developments of Polydora ciliata Johns, and Polydora hoplura Clap, are described from the egg to a very late planktonic stage in the case of the former, and to young metamorphosed individuals in the case of the latter. Only external characters are described.In both species the eggs are laid in egg-sacs attached to the wall of the parent's burrow.The larvae of P. ciliata are released at a stage with three chsetigerous segments and lead a long planktonic life.The larvae of P. hoplura are provided with special food in the form of yolk-masses ; they undergo most of their development while in the protecting burrow of their parent; are released at a very late stage, and have only a short planktonic life.The larvae of both species have a complicated vestibule surrounding the mouth, and are provided with special sensory cilia on the head.The larvae are provided with a special kind of cilia, situated at the ends of every nototroch, which are used to take hold of the long provisional bristles in swimming. This suggests that one of the functions of the long bristles is that, in conjunction with these grasping-cilia, they increase the rigidity of the swimming larva, and hence the efficiency of its driving cilia.Previous references to Polydora larvae are briefly discussed.

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A cis-regulatory change underlying the motor neuron-specific loss of terminal selector gene expression in immotile tunicate larvae

10.1101/567719 ◽

2019 ◽

Cited By ~ 1

Author(s):

Elijah K. Lowe ◽

Claudia Racioppi ◽

Nadine Peyriéras ◽

Filomena Ristoratore ◽

Lionel Christiaen ◽

...

Keyword(s):

Nervous System ◽

Motor Neuron ◽

Motor Neurons ◽

Gene Networks ◽

Marine Invertebrate ◽

Expression Patterns ◽

Adult Life ◽

Regulatory Change ◽

Regulatory Sequence ◽

Swimming Larva

AbstractThe evolutionary history of animal body plans cannot be fully reconstructed without considering the roles of both novelties and losses. Some of the more remarkable examples of massively parallel evolutionary losses in animals comes from many species in the tunicate genusMolgulathat have independently lost the swimming larva and instead develop as tail-less, immotile larvae that bypass the period of swimming and dispersal observed in other tunicates, marine invertebrate chordates that alternate between motile larval and sessile adult life cycle stages. The larvae ofMolgula occultaand other tail-less species do not fully develop structures that are essential for swimming behavior, including notochord, tail muscles, and otolith, and loss-of-function mutations have been identified in various genes required for the differentiation of these tissues. However, little is known about the extent of development of the larval nervous system inM. occulta. While differentiated neurons might in principle be entirely dispensable to the non-swimming larva, the adult has a fully functional nervous system like any other tunicate. To further investigate this conundrum, we studied the specification and patterning of theM. occultaMotor Ganglion, which is the key central nervous system compartment that drives the motor movements of swimming tunicate larvae. We found that the expression patterns of important regulators of MG neuron subtype specification are highly conserved during the development of the non-swimming larvae ofM. occulta, suggesting that the gene networks regulating their expression are largely intact in this species, despite the loss of swimming ability. However, we identified aM. occulta-specific reduction in expression of the important motor neuron terminal selector geneEbf (Collier/Olf/EBF or COE)in the Motor Ganglion. AlthoughM. occulta Ebfis predicted to encode a fully functional protein, its expression was reduced in developing motor neurons when compared to species with swimming larvae, which was corroborated by measuring allele-specific expression ofEbfin interspecific hybrid embryos produced by crossingM. occultawith the closely related swimming speciesM. oculata. Comparative reporter construct experiments also revealed a specificcis-regulatory sequence change that underlies the reduced expression ofM. occulta Ebfin motor neurons, but not in other tissues and cell types. This points to a potential mechanism for arresting larval motor neuron differentiation in the non-swimming larvae of this species.

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Presence and distribution of specific prosome antigens change as a function of embryonic development and tissue-type differentiation in Pleurodeles waltl

Journal of Cell Science ◽

10.1242/jcs.90.4.555 ◽

1988 ◽

Vol 90 (4) ◽

pp. 555-567 ◽

Cited By ~ 3

Author(s):

J.K. Pal ◽

P. Gounon ◽

M.F. Grossi de Sa ◽

K. Scherrer

Keyword(s):

Protein Complexes ◽

Cell Types ◽

Immunoblot Analysis ◽

Tissue Type ◽

Animal Pole ◽

Development And Differentiation ◽

A Cell ◽

Pleurodeles Waltl ◽

Rna Protein Complexes ◽

Swimming Larva

The prosomes, biochemically well characterized small RNA-protein complexes, found associated with mRNA in all eukaryotic cells tested, have been identified as maternal components in sea urchin and chick embryos. In this study, we investigated their presence and cytolocalization in the oocytes and embryos of Pleurodeles waltl by immunoblot analysis and immunofluorescence, using monoclonal antibodies prepared against duck prosome proteins. Of the four antibodies tested, three recognized the corresponding antigens in oocyte total protein extracts. Immunofluorescence analysis, using the three prosomal antibodies, demonstrated a drastic change in the localization of the prosome antigens, which changed from the cytoplasm to the nucleus during oogenesis. In the nucleus, in diplotene stages, prosomal antigens appeared to be associated with the lampbrush chromosomes and the nuclear matrix. During embryogenesis, the subcellular distribution of the prosome antigens was a function of development and differentiation: in the cleavage stages up to the mid-blastula they were localized in the cytoplasm and on the plasma membrane, while in the late blastula, gastrula and neurula they were in the nucleus. Interestingly, one of the prosome antigens, p31K, was found to be in a different location in certain cells in the animal pole of the mid-blastula and was absent in the neural tissue in the neurula. In still later stages, in the free-swimming larva, all three antigens were localized in the cytoplasm, specifically in certain cell types in the epidermal tissues. Furthermore, they were sectorially distributed in the cytoplasm. These data taken together indicate the possible presence of tissue-type-specific prosome antigens in Pleurodeles. Differentiation-dependent subcellular localization of the prosome antigens suggests a cell-compartment-related multiple function of prosomes.

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Kinematics and hydrodynamics of an invertebrate undulatory swimmer: the damsel-fly larva

Journal of Experimental Biology ◽

10.1242/jeb.205.5.627 ◽

2002 ◽

Vol 205 (5) ◽

pp. 627-639 ◽

Cited By ~ 7

Author(s):

John Brackenbury

Keyword(s):

Large Amplitude ◽

The Body ◽

Force Balance ◽

The Other ◽

Free Swimming ◽

Caudal Fin ◽

Fish Locomotion ◽

Fly Larvae ◽

Swimming Larva ◽

Visualisation Technique

SUMMARYThe kinematics and hydrodynamics of free-swimming larvae of Enallagma cyathigerum were investigated using videography combined with a simple wake visualisation technique (tracer dyes). Damsel-fly larvae are undulatory swimmers with two distinct styles of movement: ‘slow’ swimming, in which body undulation is assisted by paddling of the legs, and ‘fast’ swimming, in which the legs are inactive. In both cases, the wake consists of discrete ring vortices shed from the caudal fin at the end of each half-stroke. The vortices propagate away from the mid-line, alternately to one side of the body then the other, at an angle of 67° from dead aft. There is no aft-flowing jet such as that observed in the wakes of continuously swimming fish that use caudal fin propulsion. The estimated momentum within the vortices, and the resultant thrust on the body are in tolerable agreement with calculations based on the large-amplitude bulk momentum model of fish locomotion. However, the drag on the body is not known, so it cannot be concluded with certainty that a force balance exists. The agreement between experiment and prediction gives confidence to the idea that most, if not all, of the vorticity generated by the swimming larva is located within the observable wake elements.

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