BIOLOGY OF HYDRACTINIID HYDROIDS. 1. COLONY ONTOGENY IN<i>HYDRACTINIA ECHINATA</i>(FLEMMING)

McFadden, Catherine S.; Mcfarland, Margaret J.; Buss, Leo W.

doi:10.2307/1541430

Cited by 41 publications

(33 citation statements)

References 25 publications

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“…6B,D). In normal animals, these organs form as temporarily modified stolons during allogeneic encounters between histoincompatible animals (Ivker, 1972;McFadden et al, 1984;Lange et al, 1989;Lange, et al, 1992;Müller, 2002). Hyperplastic stolons are swollen by excessive nematocytes that are used to inflict damage on allogeneic tissues.…”

Section: Downregulation Of Nanos2 Reduces Nematogenesis and Increasesmentioning

confidence: 99%

Novel roles for Nanos in neural cell fate determination revealed by studies in a cnidarian

Kanska

Frank

2013

Journal of Cell Science

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SummaryNanos is a pan-metazoan germline marker, important for germ cell development and maintenance. In flies, Nanos also acts in posterior and neural development, but these functions have not been demonstrated experimentally in other animals. Using the cnidarian Hydractinia we have uncovered novel roles for Nanos in neural cell fate determination. Ectopic expression of Nanos2 increased the numbers of embryonic stinging cell progenitors, but decreased the numbers of neurons. Downregulation of Nanos2 had the opposite effect. Furthermore, Nanos2 blocked maturation of committed, post-mitotic nematoblasts. Hence, Nanos2 acts as a switch between two differentiation pathways, increasing the numbers of nematoblasts at the expense of neuroblasts, but preventing nematocyte maturation. Nanos2 ectopic expression also caused patterning defects, but these were not associated with deregulation of Wnt signaling, showing that the basic anterior-posterior polarity remained intact, and suggesting that numerical imbalance between nematocytes and neurons might have caused these defects, affecting axial patterning only indirectly. We propose that the functions of Nanos in germ cells and in neural development are evolutionarily conserved, but its role in posterior patterning is an insect or arthropod innovation.

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Section: Downregulation Of Nanos2 Reduces Nematogenesis and Increasesmentioning

confidence: 99%

Novel roles for Nanos in neural cell fate determination revealed by studies in a cnidarian

Kanska

Frank

2013

Journal of Cell Science

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“…Despite the fact that many of these are substantial morphological changes with major consequences for the outcome of the interaction, we know little about the particular range of ecological or developmental situations under which these aggressive structures are produced. In Hydractinia echinata (Hydrozoa), which can also produce an inducible response within days of contact, Ivker (12) demonstrated a hierarchy of competitive ability among colonies that was mediated by inducible hyperplastic stolons and has been shown to have a genetic basis (22). We here describe rapid induction of stolons by Membranipora in response to contact by smaller conspecifics.…”

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confidence: 64%

Inducible morphology, heterochrony, and size hierarchies in a colonial invertebrate monoculture.

Harvell

Padilla

1990

Proc. Natl. Acad. Sci. U.S.A.

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Conditional or inducible strategies are a powerful tool for analyzing the evolution of aggressive behavior. Structures such as stolons and nematocyst-laden tentacles, induced to deter encroachment by competitors, are proportionately better represented in clonal and colonial marine invertebrates than in aclonal animals. Stolons can be produced by colonies ofMembranipora membranacea (Bryozoa) within 48 hr after contact with conspecifics. Absolute size and relative size of interacting colonies determine whether stolons will be produced. Although individual stolons are eventually overgrown by conspeciflics, they reduce the size ofaffected zooids by 27%. Since stolon production is primarily a strategy of large colonies, we suggest that stolons function to limit space occupied by small colonies and may also trigger early and localized reproduction. Thus large colonies can surround multiple small mates and, because they reproduce only locally where induced by contact with small colonies, still maintain high growth rates on free colony perimeters. Stolons appear to be juvenilized zooids and to originate through a process of heterochrony. These induced facultative polymorphisms may be one pathway by which fixed polymorphisms arise in colonial invertebrates. We attribute the unique production of inducible structures against competitors by clonal and colonial invertebrates to both unusually high levels of developmental plasticity and an energetically favorable architecture for perimeter defense.

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“…(von Hauenschild 1954, Ivker 1972, Buss et al 1984, Buss & Grosberg 1990). In such agonistic contests, one or both colonies produce a profusion of tissue branches, or stolons, that swell as a result of accumulating nematocytes loaded with an especially potent nematocyst type, the basotrichious isorhiza (Buss et al 1984). These hyperplastic stolons (as Yund et al (1987), Buss & Yund (1988), and Yund & Parker (1989).…”

Section: Competitive Relationshipsmentioning

confidence: 99%

“…Having an increased capacity for hyperplastic stolon production, more stoloniferous colonies dominate in conspecific agonistic encounters (Buss & Grosberg 1990). Despite frequent competition for space, Hydractinia colonies found in natural populations differ widely in growth form (Hauenschild 1954, Ivker 1972, McFadden et al 1984, Yund 1991, Ferrell 2004 and, hence, competitive ability.Competitive outcomes are size-dependent in Hydractinia (Yund et al 1987, Ferrell 2004. Competitive relationships among small Hydractinia colonies are essentially transitive, consistently resulting in rapid overgrowth of the inferior competitor (Yund et al 1987, Buss & Grosberg 1990, Ferrell 2004.…”

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confidence: 99%

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Gastropod shell size and morphology influence conspecific interactions in an encrusting hydroid

Ferrell¹

2004

Mar. Ecol. Prog. Ser.

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Discrete patches of suitable habitat and the consequent aggregation of organisms with similar habitat requirements often intensify competition, particularly among conspecifics. Habitat differences may generate interactions between smaller or larger individuals at variable stages of development in many fungi, plants, and colonial animals. Size-dependent competitive outcomes and effects on sexual reproductive allocation indicate that differences among discrete habitats have potentially profound ecological and evolutionary implications. In the northern Gulf of Mexico, the colonial hydroid Hydractinia [GM] colonizes hermit crab-occupied gastropod shells (= microhabitats), which vary greatly in size and morphology. Here, the relationship between the gastropod assemblages available for H. [GM] colonization and the frequency of conspecific encounters and sexual status of those colonies involved is documented. Field-collected shells bore 1 to 3 colonies, and the number of colonies per shell increased with shell size. In contrast to previous studies, conspecific encounters were not limited to juvenile colonies. Sexually mature H.[GM] colonies generally were not distributed differently among shells with and without conspecifics. Moreover, mature colonies predominated conspecific encounters on large shell species exhibiting certain morphology. Inanimate structures, such as dock pilings and rocky surfaces, provide additional large surfaces for Hydractinia colonization in some areas. These results suggest that previous Hydractinia spp. studies represent only a subset of the diversity of ecologically relevant possibilities with respect to available substrata. Also, the characteristics of a given microhabitat (e.g. shell) affect competitive outcomes and sexual reproductive characters of its constituent competitors.KEY WORDS: Gulf of Mexico · Hydractinia · Sexual maturity · Size-dependent Resale or republication not permitted without written consent of the publisherMar Ecol Prog Ser 275: [153][154][155][156][157][158][159][160][161][162] 2004 attributes -including species, size, and inhabitant if present (e.g. live gastropod, various hermit crab species) -all of which can strongly influence epibiont assemblages (e.g. Karlson & Shenk 1983). Hydroid colonies in the genus Hydractinia typically encrust hermit crab-inhabited gastropod shells in natural populations and commonly engage in intraspecific competition. The present study focuses on Hydractinia spp. colonies in the northern Gulf of Mexico, which colonize at least 13 different gastropod shell species, exhibiting wide variation in both shell size and morphology. Mating experiments between colonies collected in the Gulf and the northwestern Atlantic indicate that colonies in the Gulf of Mexico comprise a new, undescribed species, designated Hydractinia [GM] (Cunningham et al. 1991).Hydractinia [GM] shares many similarities with its congeners relating to intraspecific competition. Like most Hydractinia species, H. [GM] typically encrusts gastropod shells inhabit...

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BIOLOGY OF HYDRACTINIID HYDROIDS. 1. COLONY ONTOGENY INHYDRACTINIA ECHINATA(FLEMMING)

Cited by 41 publications

References 25 publications

Novel roles for Nanos in neural cell fate determination revealed by studies in a cnidarian

Novel roles for Nanos in neural cell fate determination revealed by studies in a cnidarian

Inducible morphology, heterochrony, and size hierarchies in a colonial invertebrate monoculture.

Gastropod shell size and morphology influence conspecific interactions in an encrusting hydroid

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