Methods to study organogenesis in decapod crustacean larvae II: analysing cells and tissues

Melzer, Roland R.; Spitzner, Franziska; Šargač, Zoran; Hörnig, Marie K.; Krieger, Jakob; Haug, Carolin; Haug, Joachim T.; Kirchhoff, Tina; Meth, Rebecca; Torres, Gabriela; Harzsch, Steffen

doi:10.1186/s10152-021-00547-y

Cited by 9 publications

(4 citation statements)

References 139 publications

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“…The advantages of autofluorescence imaging have been previously advocated [ 75 ] and readily embraced for other arthropod taxa (e.g. [ 76 – 79 ]). But only recently, they have been exploited in first pycnogonid studies [ 65 , 80 , 81 ].…”

Section: Discussionmentioning

confidence: 99%

Epimorphic development in tropical shallow-water Nymphonidae (Arthropoda: Pycnogonida) revealed by fluorescence imaging

Arango,

Brenneis

2024

Zoological Lett

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Background Extant lineages of sea spiders (Pycnogonida) exhibit different types of development. Most commonly, pycnogonids hatch as a minute, feeding protonymphon larva with subsequent anamorphic development. However, especially in cold water habitats at higher latitudes and in the deep sea, some taxa have large, lecithotrophic larvae, or even undergo extended embryonic development with significantly advanced postlarval hatching stages. Similar biogeographic trends are observed in other marine invertebrates, often referred to as “Thorson’s rule”. Results To expand our knowledge on the developmental diversity in the most speciose pycnogonid genus Nymphon, we studied the developmental stages of the two tropical representatives N. floridanum and N. micronesicum., We compared classical scanning electron microscopy with fluorescence-based approaches to determine which imaging strategy is better suited for the ethanol-fixed material available. Both species show epimorphic development and hatch as an advanced, lecithotrophic postlarval instar possessing the anlagen of all body segments. Leg pairs 1–3 show a considerable degree of differentiation at hatching, but their proximal regions remain coiled and hidden under the cuticle of the hatching instar. The adult palp and oviger are not anteceded by three-articled larval limbs, but differentiate directly from non-articulated limb buds during postembryonic development. Conclusions Fluorescence imaging yielded more reliable morphological data than classical scanning electron microscopy, being the method of choice for maximal information gain from rare and fragile sea spider samples fixed in high-percentage ethanol. The discovery of epimorphic development with lecithotrophic postlarval instars in two small Nymphon species from tropical shallow-water habitats challenges the notion that this developmental pathway represents an exclusive cold-water adaptation in Nymphonidae. Instead, close phylogenetic affinities to the likewise more direct-developing Callipallenidae hint at a common evolutionary origin of this trait in the clade Nymphonoidea (Callipallenidae + Nymphonidae). The lack of functional palpal and ovigeral larval limbs in callipallenids and postlarval hatchers among nymphonids may be a derived character of Nymphonoidea. To further test this hypothesis, a stable and well-resolved phylogenetic backbone for Nymphonoidea is key.

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Section: Discussionmentioning

confidence: 99%

Epimorphic development in tropical shallow-water Nymphonidae (Arthropoda: Pycnogonida) revealed by fluorescence imaging

Arango,

Brenneis

2024

Zoological Lett

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“…This chapter focuses on larval metamorphosis, sex determination, and sexual differentiation in non-insect arthropods, especially in decapod crustaceans and spider chelicerates. Insects have long been the frontrunners in the study of these phenomena in arthropods, however, new emerging methods such as next-generation sequencing, 3D and high-resolution imaging techniques [120,121], and genome editing methods [122][123][124][125] are opening the door for every non-model species. It is of great benefit to the wealth of available knowledge of insects.…”

Section: Discussionmentioning

confidence: 99%

Larval Development of Non-Insect Arthropods: Metamorphosis and Sexual Differentiation

Toyota¹,

Sakae²,

Iguchi³

2023

Arthropods - New Advances and Perspectives

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In insects, metamorphosis is one of the most important research topics. Their drastic morphological and physiological changes from larvae to pupae, and then to adults, have fascinated many people. These changing life history patterns are tightly regulated by two endocrine systems, the ecdysteroids (molting hormones) and the juvenile hormones. Metamorphosis is also the most universal phenomenon in non-insect arthropods (especially crustaceans). Additionally, as dwarf males (e.g., barnacle crustaceans) show distinct sexual dimorphism during the larval developmental stage, larval development and sexual differentiation are also intimately associated. Our knowledge of endocrinology and gene cascades underlying metamorphosis and sexual differentiation in non-insect arthropods is rudimentary at best and relies heavily on well-studied insect models. Advances in newly developed applications, omics technologies and gene-targeting, are expected to lead to explorative molecular studies that reveal components and pathways unique to non-insect arthropods. This chapter reconciles known components of metamorphosis and sexual differentiation in non-insect arthropods and reflects on our findings in insects to outline future research.

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“…One technique which has found use in taxonomically useful imaging of arthropods is dark field microscopy, where incident light is directed at the specimen in such a way that it does not pass into the objective unless deflected (reflected, refracted or scattered) by the specimen, leading to improved contrast against background and higher salience of delicate surface structures (Haug et al, 2011b). Another applicable method is polarization contrast that can underline differences in thickness and density of thicker homogenous structures formed by the cuticle (Fernańdez del Rıó et al, 2016;Melzer et al, 2021). Finally, interference contrast (also known as Nomarski contrast) is a powerful technique enabling the visualization of fine ultrastructural details.…”

Section: Bright Field and Optical Contrast Microscopymentioning

confidence: 99%

Challenges and Advances in the Taxonomy of Deep-Sea Peracarida: From Traditional to Modern Methods

Frutos

Kaiser²,

Pułaski³

et al. 2022

Front. Mar. Sci.

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As one of the oldest branches of biology, taxonomy deals with the identification, classification and naming of living organisms, using a variety of tools to explore traits at the morphological and molecular level. In the deep sea, particular challenges are posed to the taxonomic differentiation of species. Relatively limited sampling effort coupled with apparent high diversity, compared to many other marine environments, means that many species sampled are undescribed, and few specimens are available for each putative species. The resulting scarce knowledge of intraspecific variation makes it difficult to recognize species boundaries and thus to assess the actual diversity and distribution of species. In this review article, we highlight some of these challenges in deep-sea taxonomy using the example of peracarid crustaceans. Specifically, we offer a detailed overview of traditional as well as modern methods that are used in the taxonomic analysis of deep-sea Peracarida. Furthermore, methods are presented that have not yet been used in peracarid taxonomy, but have potential for the analysis of internal and external structures in the future. The focus of this compilation is on morphological methods for the identification, delimitation and description of species, with references to molecular analysis included where relevant, as these methods are an indispensable part of an integrative taxonomic approach. The taxonomic impediment, i.e. the shortage of taxonomists in view of a high undescribed biodiversity, is discussed in the context of the existing large taxonomic knowledge gaps in connection with the increasing threat to deep-sea ecosystems. Whilst peracarid crustaceans are used here as an exemplary taxon, the methodology described has broad relevance to many other deep-sea taxa, and thus will support broader research into deep-sea biodiversity and ecology more widely.

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Methods to study organogenesis in decapod crustacean larvae II: analysing cells and tissues

Cited by 9 publications

References 139 publications

Epimorphic development in tropical shallow-water Nymphonidae (Arthropoda: Pycnogonida) revealed by fluorescence imaging

Epimorphic development in tropical shallow-water Nymphonidae (Arthropoda: Pycnogonida) revealed by fluorescence imaging

Larval Development of Non-Insect Arthropods: Metamorphosis and Sexual Differentiation

Challenges and Advances in the Taxonomy of Deep-Sea Peracarida: From Traditional to Modern Methods

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