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Updated: Aug 17, 2026
Microinjection of Medaka Embryos for use as a Model Genetic Organism
Published on: December 22, 2010
Characterization and developmentally regulated expression of four annexins in the killifish medaka
D Osterloh1, J Wittbrodt, V Gerke
1Institute for Medical Biochemistry, ZMBE, University of Münster, Germany.
Abstract:
Annexins are Ca2+-regulated membrane binding proteins implicated in a wide range of membrane-related and signal transduction events, including the endocytosis of membrane receptors and Ca2+-regulated as well as constitutive secretion. To date, 10 unique members of this multigene family have been identified in a variety of cell types and tissues of higher vertebrates, with different members showing distinct tissue distributions in the adult organisms. To establish whether annexins also function in embryonic development, we analyzed the expression pattern during vertebrate morphogenesis using the medaka fish Oryzias latipes as a model system. From a larval medaka cDNA library, we isolated four types of clones, which were shown by sequence analysis to encode four different annexins (herein referred to as max 1-4). A comparison with known annexin sequences in the databases revealed that two medaka annexins (max 1 and 2) are highly similar in sequence to mammalian annexins V and IV, respectively, whereas the other two medaka annexins (max 3 and 4) are probably novel members of the family most closely related to mammalian annexins I and XI. Using whole-mount RNA in situ hybridization, we showed that the expression of the different medaka annexins during embryogenesis was strictly regulated at both the spatial and the temporal level. High levels of max 1, 2, and 3 transcripts were present in the developing stomach, gut, liver, air-bladder, and rectum during somitogenesis, thus identifying the digestive tract as the prime region of annexin expression. Interestingly, two structures playing crucial roles in neuronal patterning showed a distinct expression of annexins. The mesendoderm of the anterior prechordal plate of neurula-stage embryos was a site of max 4 transcription, and the floor plate of somitogenesis-stage embryos showed expression of max 2 and 3 to differing rostrocaudal extends along the brain and spinal cord. These results suggest specific functions of different annexins during vertebrate morphogenesis.
Insights
This study investigates annexin gene expression during embryonic development in medaka fish, revealing specific spatial and temporal patterns. The findings suggest diverse roles for annexins in vertebrate morphogenesis, particularly in the developing digestive tract and neural structures.
Area of Science:
- Developmental Biology
- Molecular Biology
- Genetics
Background:
- Annexins are Ca2+-regulated proteins involved in membrane dynamics and signal transduction.
- Ten annexin family members are known in higher vertebrates, with distinct tissue distributions.
- The role of annexins in embryonic development is not well understood.
Purpose of the Study:
- To investigate annexin gene expression patterns during vertebrate embryonic development.
- To identify potential roles of annexins in morphogenesis using medaka fish as a model.
- To characterize novel annexin family members.
Main Methods:
- Isolation and sequence analysis of annexin clones from a medaka cDNA library.
- Whole-mount RNA in situ hybridization to determine spatial and temporal expression.
- Comparison of medaka annexin sequences with known mammalian annexins.
Main Results:
- Four medaka annexin genes (max 1-4) were identified, with max 1 and 2 similar to mammalian annexins V and IV, and max 3 and 4 potentially novel members.
- Annexin expression was spatially and temporally regulated during medaka embryogenesis.
- High expression of max 1, 2, and 3 was observed in the developing digestive tract (stomach, gut, liver, air-bladder, rectum).
- Distinct annexin expression patterns were noted in neural structures, including the anterior prechordal plate (max 4) and the floor plate of the brain and spinal cord (max 2 and 3).
Conclusions:
- Medaka annexins exhibit specific expression patterns during embryonic development, suggesting specialized functions.
- The digestive tract is a primary site of annexin expression during somitogenesis.
- Annexins play roles in neuronal patterning, with distinct members involved in different regions of the developing central nervous system.
