Cephalochordata

Holland, Linda Z.

doi:10.1007/978-3-7091-1856-6_3

Cited by 7 publications

(28 citation statements)

References 251 publications

(254 reference statements)

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“…Husbandry protocols have been established for at least five lancelet species [4], and, due to the absence of a universal staging system, the naming of embryos and larvae obtained with these protocols has become extremely confusing. While developing lancelets are often named in accordance with previous reports on the same species [1,[26][27][28], it is also not uncommon to indicate the time after fertilization, usually measured in hours, although developmental speed is known to vary between lancelet species and to depend on the rearing temperature, which is not the same in each study [2,29]. This lack of an unambiguous nomenclature for developing lancelets artificially complicates comparisons of results obtained in different species and sometimes even within the same species, for example, when two laboratories use incompatible staging styles [28,30].…”

Section: Introductionmentioning

confidence: 75%

“…The sperm can enter the oocyte anywhere, but will preferentially do so in the vegetal hemisphere [32]. Independent of the entry point, the nucleus of the sperm will first migrate to the vegetal half and will only then join the maternal chromosomes at the animal pole [1]. Very soon after fertilization, a whorl composed of sheets of endoplasmic reticulum is formed within the 1-cell stage.…”

Section: Fertilization and Cleavagementioning

confidence: 99%

“…Following gastrulation, all ectodermal cells develop cilia and the embryo subsequently starts to rotate within the fertilization envelope by ciliary movement [1,26]. At this point in development, neurulation starts.…”

Section: Neurulationmentioning

confidence: 99%

“…3E,E'). Thus, while early somitogenesis occurs by enterocoely from endomesoderm internalized during gastrulation, starting at the N4 stage, somites are formed by schizocoely from the tail bud [1]. In the anterior archenteron, the two dorso-lateral lobes have formed two distinctive head cavities: Hatschek's left and right diverticulum [33,36].…”

Section: Neurulationmentioning

confidence: 99%

“…The subphylum Cephalochordata comprises only a few dozen species of small, lancet-shaped filter-feeders [1,2]. The Cephalochordata (commonly referred to as lancelets or amphioxus) belong to the chordate phylum and are the sister group to all other chordates (Tunicata plus Vertebrata) [1,2].…”

Section: Introductionmentioning

confidence: 99%

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An updated staging system for cephalochordate development: one table suits them all

Carvalho

Lahaye

Yong

et al. 2020

Preprint

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Background:The chordates are divided into three subphyla: Vertebrata, Tunicata and Cephalochordata. Phylogenetically, the Cephalochordata, more commonly known as lancelets or amphioxus, constitute the sister group of Vertebrata plus Tunicata. Due to their phylogenetic position and their conserved morphology and genome architecture, lancelets are important models for understanding the evolutionary history of chordates. Lancelets are small, marine filter-feeders, and the few dozen species that have so far been described have been grouped into three genera: Branchiostoma, Epigonichthys and Asymmetron.Given their relevance for addressing questions about the evolutionary diversification of chordates, lancelets have been the subjects of study by generations of scientists, with the first descriptions of adult anatomy and developmental morphology dating back to the 19 th century. Today, several different lancelet species are used as laboratory models, predominantly for developmental, molecular and genomic studies. It is thus very surprising that there is currently no universal staging system and no unambiguous nomenclature for developing lancelets. Results:We illustrated the development of the European amphioxus (Branchiostoma lanceolatum) using confocal microscopy and compiled a streamlined developmental staging system, from fertilization through larval life, with an unambiguous stage nomenclature. By tracing growth curves of the European amphioxus reared at different temperatures, we were able to show that our staging system permits the easy conversion of any developmental time into a defined 3 stage name. Furthermore, comparisons of embryos and larvae from the European amphioxus (B. lanceolatum), the Florida amphioxus (B. floridae), the Chinese amphioxus (B. belcheri), the Japanese amphioxus (B. japonicum) and the Bahamas lancelet (Asymmetron lucayanum) demonstrated that our staging system can readily be applied to other lancelet species.Conclusions: Here, we propose an updated staging and nomenclature system for lancelets. Although the detailed staging description was carried out on developing B. lanceolatum, comparisons with other lancelet species strongly suggest that both staging and nomenclature are applicable to all extant lancelets.We thus believe that this description of embryonic and larval development can be of great use for the scientific community and hope that it will become the new standard for defining and naming developing lancelets. KeywordsAmphioxus, Asymmetron lucayanum, Branchiostoma belcheri, Branchiostoma floridae, Branchiostoma japonicum, Branchiostoma lanceolatum, Confocal Microscopy, Embryonic and Larval Development, Evolution and Development, Lancelet 4

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