Remodeling of the Nauplius Eye into the Adult Ocelli during Metamorphosis of the Barnacle, Balanus amphitrite hawaiiensis

Takenaka, Mikihito; Suzuki, Akiko; Yamamoto, Takashi; Yamamoto, Masamichi; Yoshida, Masao

doi:10.1111/j.1440-169x.1993.00245.x

Cited by 22 publications

(14 citation statements)

References 19 publications

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“…In addition, a strong signal was observed in the region of the pair of compound eyes that consist of several visual cells and photoreceptors and are distinct from those in nauplius eyes or adult photoreceptors (Fig. 5D) [49]. However, how the two compound eyes really function and how Ba-CaM is really involved during larval settlement require further investigation.…”

Section: Discussionmentioning

confidence: 98%

Expression of Calmodulin and Myosin Light Chain Kinase during Larval Settlement of the Barnacle Balanus amphitrite

et al. 2012

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Barnacles are one of the most common organisms in intertidal areas. Their life cycle includes seven free-swimming larval stages and sessile juvenile and adult stages. The transition from the swimming to the sessile stages, referred to as larval settlement, is crucial for their survivor success and subsequent population distribution. In this study, we focused on the involvement of calmodulin (CaM) and its binding proteins in the larval settlement of the barnacle, Balanus ( = Amphibalanus) amphitrite. The full length of CaM gene was cloned from stage II nauplii of B. amphitrite (referred to as Ba-CaM), encoding 149 amino acid residues that share a high similarity with published CaMs in other organisms. Quantitative real-time PCR showed that Ba-CaM was highly expressed in cyprids, the stage at which swimming larvae are competent to attach and undergo metamorphosis. In situ hybridization revealed that the expressed Ba-CaM gene was localized in compound eyes, posterior ganglion and cement glands, all of which may have essential functions during larval settlement. Larval settlement assays showed that both the CaM inhibitor compound 48/80 and the CaM-dependent myosin light chain kinase (MLCK) inhibitor ML-7 effectively blocked barnacle larval settlement, whereas Ca2+/CaM-dependent kinase II (CaMKII) inhibitors did not show any clear effects. The subsequent real-time PCR assay showed a higher expression level of Ba-MLCK gene in larval stages than in adults, suggesting an important role of Ba-MLCK gene in larval development and competency. Overall, the results suggest that CaM and CaM-dependent MLCK function during larval settlement of B. amphitrite.

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Section: Discussionmentioning

confidence: 98%

Expression of Calmodulin and Myosin Light Chain Kinase during Larval Settlement of the Barnacle Balanus amphitrite

et al. 2012

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“…Even the widely cited benchmark study of Walley [12] on the profound histological changes seen during metamorphosis of Semibalanus balanoides relied on field-sampled specimens without any precise determination of sequence or age. Glenner and Høeg [13], [14] and Takenaka et al [15] did use laboratory-reared animals but studied only specific details of metamorphosis. For thoracican barnacles, the only in-depth studies providing timing of metamorphic events are those of Kühl [16] and Høeg et al [17].…”

Section: Introductionmentioning

confidence: 99%

Metamorphosis in the Cirripede Crustacean Balanus amphitrite

et al. 2012

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Stalked and acorn barnacles (Cirripedia Thoracica) have a complex life cycle that includes a free-swimming nauplius larva, a cypris larva and a permanently attached sessile juvenile and adult barnacle. The barnacle cyprid is among the most highly specialized of marine invertebrate larvae and its settlement biology has been intensively studied. By contrast, surprisingly few papers have dealt with the critical series of metamorphic events from cementation of the cyprid to the substratum until the appearance of a suspension feeding juvenile. This metamorphosis is both ontogenetically complex and critical to the survival of the barnacle. Here we use video microscopy to present a timeline and description of morphological events from settled cyprid to juvenile barnacle in the model species Balanus amphitrite, representing an important step towards both a broader understanding of the settlement ecology of this species and a platform for studying the factors that control its metamorphosis. Metamorphosis in B. amphitrite involves a complex sequence of events: cementation, epidermis separation from the cypris cuticle, degeneration of cypris musculature, rotation of the thorax inside the mantle cavity, building of the juvenile musculature, contraction of antennular muscles, raising of the body, shedding of the cypris cuticle, shell plate and basis formation and, possibly, a further moult to become a suspension feeding barnacle. We compare these events with developmental information from other barnacle species and discuss them in the framework of barnacle settlement ecology.

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“…The same developmental process was found in Cirripedia ( Balanus amphitrite hawaiiensis ). Their tapetal cells also appear in the later ontogenetic stage (the phase of metamorphosis to the adult stage) (Takenaka et al. , 1993).…”

Section: Discussionmentioning

confidence: 99%

Heterochrony and modularity in the degeneration of maxillopodan nauplius eyes

Kaji

Tsukagoshi

2010

Biological Journal of the Linnean Society

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Eye degeneration is a general evolutionary tendency shown in many animal groups that are adapted to dark environments. Thus far, the degenerative process has only been discussed within a few taxonomic units, in terms of both evolution and development, and more studies are needed to deal adequately with this area of ostracod biology. The ostracods and copepods examined in the present study are small crustaceans that are widely diversified in the aquatic environment, and also in interstitial environments, and their 'nauplius eyes' (primitive eye in Crustacea; typically composed of three or four ocelli) show various degrees of degeneration. The ultrastructure and ontogeny of their degenerated nauplius eyes are described for the first time in the present study, using transmission electron microscopy. According to our observations, two morphotypes for degenerative nauplius eyes (i.e. 'tapetal-less form' and 'pigment reduced form') are found in both taxa. The first description of the embryogenesis of normal (none-degenerated) nauplius eyes of surface species is also provided. From a comparison between the embryogenesis of normal nauplius eyes and the postembryogenic development of the 'tapetal-less form', it is strongly suggested that the 'tapetal-less form' is derived by paedomorphic evolution. On the basis of our observations, as well as on previous studies, we propose the hypothesis that modularity, in the form of hierarchical interactions, exists in the nauplius eye (i.e. the tapetal cells constitute an independent developmental module to be distinguished from other developmental or functional modules, including both the pigmented cells and the sensory cells). According to our hypothesis on the nauplius eyes, we also discuss the possibility that the degenerative process is constrained within the general developmental and functional context.

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Remodeling of the Nauplius Eye into the Adult Ocelli during Metamorphosis of the Barnacle, Balanus amphitrite hawaiiensis

Cited by 22 publications

References 19 publications

Expression of Calmodulin and Myosin Light Chain Kinase during Larval Settlement of the Barnacle Balanus amphitrite

Expression of Calmodulin and Myosin Light Chain Kinase during Larval Settlement of the Barnacle Balanus amphitrite

Metamorphosis in the Cirripede Crustacean Balanus amphitrite

Heterochrony and modularity in the degeneration of maxillopodan nauplius eyes

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