Aby wyświetlić tę treść, wymagana jest subskrypcja JoVE. Zaloguj się lub rozpocznij bezpłatny okres próbny.
Method Article
Here, we describe a protocol for visualizing stem-like proliferating cells in the jellyfish Cladonema. Whole-mount fluorescent in situ hybridization with a stem cell marker allows for the detection of stem-like cells, and 5-ethynyl-2'-deoxyuridine labeling enables the identification of proliferating cells. Together, actively proliferating stem-like cells can be detected.
Cnidarians, including sea anemones, corals, and jellyfish, exhibit diverse morphology and lifestyles that are manifested in sessile polyps and free-swimming medusae. As exemplified in established models such as Hydra and Nematostella, stem cells and/or proliferative cells contribute to the development and regeneration of cnidarian polyps. However, the underlying cellular mechanisms in most jellyfish, particularly at the medusa stage, are largely unclear, and, thus, developing a robust method for identifying specific cell types is critical. This paper describes a protocol for visualizing stem-like proliferating cells in the hydrozoan jellyfish Cladonema pacificum. Cladonema medusae possess branched tentacles that continuously grow and maintain regenerative capacity throughout their adult stage, providing a unique platform with which to study the cellular mechanisms orchestrated by proliferating and/or stem-like cells. Whole-mount fluorescent in situ hybridization (FISH) using a stem cell marker allows for the detection of stem-like cells, while pulse labeling with 5-ethynyl-2'-deoxyuridine (EdU), an S phase marker, enables the identification of proliferating cells. Combining both FISH and EdU labeling, we can detect actively proliferating stem-like cells on fixed animals, and this technique can be broadly applied to other animals, including non-model jellyfish species.
Cnidaria is considered a basally branching metazoan phylum containing animals with nerves and muscles, placing them in a unique position for understanding the evolution of animal development and physiology1,2. Cnidarians are categorized into two main groups: Anthozoa (e.g., sea anemones and corals) possess only planula larvae and sessile polyp stages, while Medusozoa (members of Hydrozoa, Staurozoa, Scyphozoa, and Cubozoa) typically take the form of free-swimming medusae, or jellyfish, as well as planula larvae and polyps. Cnidarians commonly exhibit high regenerative capacity, and their underlying cellular mechanisms, particularly their possession of adult stem cells and proliferative cells, have attracted much attention3,4. Initially identified in Hydra, hydrozoan stem cells are located in the interstitial spaces between ectodermal epithelial cells and are commonly referred to as interstitial cells or i-cells3.
Hydrozoan i-cells share common characteristics that include multipotency, the expression of widely conserved stem cell markers (e.g., Nanos, Piwi, Vasa), and migration potential3,5,6,7,8. As functional stem cells, i-cells are extensively involved in the development, physiology, and environmental responses of hydrozoan animals, which attests to their high regenerative capacity and plasticity3. While stem cells, similar to i-cells, have not been identified outside of hydrozoans, even in the established model species Nematostella, proliferative cells are still involved in the maintenance and regeneration of somatic tissue, as well as the germ line9. As studies in cnidarian development and regeneration have been predominantly conducted on polyp-type animals such as Hydra, Hydractinia, and Nematostella, the cellular dynamics and functions of stem cells in jellyfish species remain largely unaddressed.
The hydrozoan jellyfish Clytia hemisphaerica, a cosmopolitan jellyfish species with different habitats around the world, including the Mediterranean Sea and North America, has been utilized as an experimental model animal in several developmental and evolutionary studies10. With its small size, easy handling, and large eggs, Clytia is suitable for lab maintenance, as well as for the introduction of genetic tools such as the recently established transgenesis and knockout methods11, opening up the opportunity for detailed analysis of the cellular and molecular mechanisms underlying jellyfish biology. In the Clytia medusa tentacle, i-cells are localized in the proximal region, called the bulb, and progenitors such as nematoblasts migrate to the distal tip while differentiating into distinct cell types, including nematocytes12.
During regeneration of the Clytia manubrium, the oral organ of jellyfish, Nanos1+ i-cells that are present in the gonads migrate to the region where the manubrium is lost in response to damage and participate in the regeneration of the manubrium7. These findings support the idea that i-cells in Clytia also behave as functional stem cells that are involved in morphogenesis and regeneration. However, given that the properties of i-cells differ among representative polyp-type animals such as Hydra and Hydractinia3, it is possible that the characteristics and functions of stem cells are diversified among jellyfish species. Furthermore, with the exception of Clytia, experimental techniques have been limited for other jellyfish, and the detailed dynamics of proliferative cells and stem cells are unknown13.
The hydrozoan jellyfish Cladonema pacificum is an emerging model organism that can be kept in a laboratory environment without a water pump or filtration system. The Cladonema medusa has branched tentacles, a common characteristic in the Cladonematidae family, and a photoreceptor organ called the ocellus on the ectodermal layer near the bulb14. The tentacle branching process occurs at a new branching site that appears along the adaxial side of the tentacle. Over time, the tentacles continue to elongate and branch, with the older branches being pushed out toward the tip15. In addition, Cladonema tentacles can regenerate within a few days upon amputation. Recent studies have suggested the role of proliferating cells and stem-like cells in tentacle branching and regeneration in Cladonema16,17. However, while conventional in situ hybridization (ISH) has been utilized to visualize gene expression in Cladonema, due to its low resolution, it is currently difficult to observe stem cell dynamics at the cellular level in detail.
This paper describes a method for visualizing stem-like cells in Cladonema by FISH and co-staining with EdU, a marker of cell proliferation18. We visualize the expression pattern of Nanos1, a stem cell marker5,17, by FISH, which allows for the identification of stem-like cell distribution at the single-cell level. In addition, the co-staining of Nanos1 expression with EdU labeling makes it possible to distinguish actively proliferating stem-like cells. This method for monitoring both stem-like cells and proliferative cells can be applied to a wide range of investigative areas, including tentacle branching, tissue homeostasis, and organ regeneration in Cladonema, and a similar approach can be applied to other jellyfish species.
NOTE: See the Table of Materials for details related to all materials, reagents, and equipment used in this protocol.
1. Probe synthesis
2. EdU incorporation and fixation
3. Fluorescent in situ hybridization
Cladonema tentacles have been used as a model to study the cellular processes of morphogenesis and regeneration15,16,17. The tentacle structure is composed of an epithelial tube where stem-like cells, or i-cells, are located in the proximal region, called the tentacle bulb, and new branches are sequentially added to the rear of the distal region of the bulb along the adaxial side (Figure 3A...
Proliferating cells and stem cells are important cellular sources in various processes such as morphogenesis, growth, and regeneration21,22. This paper describes a method for co-staining the stem cell marker Nanos1 by FISH and EdU labeling in Cladonema medusae. Previous work using EdU or BrdU labeling has suggested that proliferative cells localize to the tentacle bulbs16,17, but their m...
The authors have no conflicts of interest to disclose.
This work was supported by AMED under Grant Number JP22gm6110025 (to Y.N.) and by the JSPS KAKENHI Grant Number 22H02762 (to Y.N.).
Name | Company | Catalog Number | Comments |
2-Mercaptoethanol | Wako | 137-06862 | |
3.1 mL transfer pipette | Thermo Scientific | 233-20S | |
5-Bromo-4-chloro-3-indolyl-β-D-galactopyranoside (X-Gal) | Wako | 029-15043 | |
anti-DIG-POD | Roche | 11207733910 | |
Cladonema pacificum Nanos1 forward primer | 5’-AAGAGACACAGTCATTATCAAGC GA-3’ | ||
Cladonema pacificum Nanos1 reverse primer | 5’-CGACGTGTCCAATTTTACGTGCT -3’ | ||
Cladonema pacificum Piwi forward primer | 5’- AAAAGAGCAGCGGCCAGAAAGA AGGC -3’ | ||
Cladonema pacificum Piwi reverse primer | 5’- GCGGGTCGCATACTTGTTGGTA CTGGC -3’ | ||
Click-iT EdU Cell Proliferation Kit for Imaging, Alexa Fluor 488 dye | Invitrogen | C10337 | EdU kit |
Coroline off | GEX Co. ltd | N/A | chlorine neutralizer |
DIG Nucleic Acid Detection Kit Blocking Reagent | Roche | 11175041910 | blocking buffer |
DIG RNA labeling mix | Roche | 11277073910 | |
DTT | Promega | P117B | |
ECOS competent cell DH5α | NIPPON GENE | 316-06233 | competent cell |
Fast gene Gel/PCR Extraction kit | Fast gene | FG-91302 | gel extraction kit |
Fast gene plasmid mini kit | Fast gene | FG-90502 | plasmid miniprep |
Formamide | Wako | 068-00426 | |
Heparin sodium salt from porcine | SIGMA-ALDRICH | H3393-10KU | |
Isopropyl-β-D(-)-thiogalactopyranoside (IPTG) | Wako | 096-05143 | |
LB Agar | Invitrogen | 22700-025 | agar plate |
LB Broth Base | Invitrogen | 12780-052 | LB medium |
Maleic acid | Wako | 134-00495 | |
mini Quick spin RNA columns | Roche | 11814427001 | clean-up column |
NaCl | Wako | 191-01665 | |
NanoDrop OneC Microvolume UV-Vis Spectrophotometer with Wi-Fi | Thermo Scientific | ND-ONEC-W | spectrophotometer |
Polyoxyethlene (20) Sorbitan Monolaurate (Tween-20) | Wako | 166-21115 | |
PowerMasher 2 | nippi | 891300 | homogenizer |
Proteinase K | Nacarai Tesque | 29442-14 | |
RNase Inhibitor | TaKaRa | 2313A | |
RNeasy Mini kit | Qiagen | 74004 | total RNA isolation kit |
RQ1 RNase-Free Dnase | Promega | M6101 | |
Saline Sodium Citrate Buffer 20x powder (20x SSC) | TaKaRa | T9172 | |
SEA LIFE | Marin Tech | N/A | mixture of mineral salts |
T3 RNA polymerase | Roche | 11031163001 | |
T7 RNA polymerase | Roche | 10881767001 | |
TAITEC HB-100 | TAITEC | 0040534-000 | Hybridization incuvator |
TaKaRa Ex Taq | TaKaRa | RR001A | Taq DNA polymerase |
TaKaRa PrimeScript 2 1st strand cDNA Synthesis Kit | TaKaRa | 6210A | cDNA synthesis kit |
Target Clone | TOYOBO | TAK101 | pTA2 Vector |
tRNA | Roche | 10109541001 | |
TSA Plus Cyanine 5 | AKOYA Biosciences | NEL745001KT | tyramide signal amplification (TSA) technique |
Zeiss LSM 880 | ZEISS | N/A | laser scanning confocal microscope |
Zapytaj o uprawnienia na użycie tekstu lub obrazów z tego artykułu JoVE
Zapytaj o uprawnieniaThis article has been published
Video Coming Soon
Copyright © 2025 MyJoVE Corporation. Wszelkie prawa zastrzeżone