Nav: Home

A tadpole with a twist: Left-right asymmetric development of Oikopleura dioica

February 26, 2020

Osaka, Japan - How does a developing embryo, which is initially round, tell left from right? This basic process is still poorly understood. However, investigating unusual cases can help shed light on how this process occurs in animals. More than a century ago, German biologist Dr. H. C. Delsman described unusual left-right (L-R) patterning in the tadpole-like tunicate Oikopleura dioica. Now, researchers at Osaka University have uncovered the details of this process in O. dioica, reported in a new study published in the Proceedings of the National Academy of Sciences.

Bilateral symmetry is one the most fundamental characteristics of members of the phylum Chordata, the group that includes O. dioica as well as all animals with backbones, although L-R patterning tends to emerge later in development. However, in the larvacean tunicate O. dioica, distinct from other chordates, L-R asymmetry first appears in the four-cell embryo stage and persists throughout development; the nerve cord, typically located on the dorsal side of chordates, forms instead on the animal's left side. This notable difference provides an opportunity to investigate the mechanisms that drive L-R patterning in chordates.

"Our study reveals that this larvacean uses calcium ion oscillation and expression of the right-sided bone morphogenetic protein (Bmp) gene for embryonic left-right patterning," explains first author Takeshi A. Onuma. "Intriguingly, Nodal, an evolutionarily conserved left-determining gene found in other chordates, is absent from the genome of O. dioica. As the larvacean develops, it is likely that its tail twists 90° counterclockwise relative to its trunk, with the tail nerve cord localized on its left side."

In most chordates, Nodal and Bmp create the gradient responsible for L-R determination in the developing embryo. The absence of Nodal, combined with the novel and early L-R patterning of this larvacean, is therefore of great interest for advancing understanding of the roles of Nodal, Bmp, and calcium ion oscillation, and the evolution of L-R patterning in early chordates.

According to senior author Hiroki Nishida, "between insects and vertebrates, the dorsal-ventral axis is inverted 180°, which is correlated with Bmp expression. However, the reason for this inversion is not yet well understood. In addition to revealing a novel left-right patterning process of a chordate species, our findings provide an example where the dorsal-ventral axis and Bmp expression lead to 90° rotation with left-right patterning."

Such examples of novel L-R patterning are key for unraveling some of the most fundamental questions about the earliest evolution and development of chordates and other animals.
-end-
The article, "A chordate species lacking Nodal utilizes calcium oscillation and Bmp for left-right patterning," was published in the Proceedings of the National Academy of Sciences at DOI: https://doi.org/10.1073/pnas.1916858117

About Osaka University

Osaka University was founded in 1931 as one of the seven imperial universities of Japan and now has expanded to one of Japan's leading comprehensive universities. The University has now embarked on open research revolution from a position as Japan's most innovative university and among the most innovative institutions in the world according to Reuters 2015 Top 100 Innovative Universities and the Nature Index Innovation 2017. The university's ability to innovate from the stage of fundamental research through the creation of useful technology with economic impact stems from its broad disciplinary spectrum.

Website: https://resou.osaka-u.ac.jp/en/top

Osaka University

Related Gene Articles:

Gene therapy/gene editing combo could offer hope for some genetic disorders
A hybrid approach that combines elements of gene therapy with gene editing converted an experimental model of a rare genetic disease into a milder form, significantly enhancing survival, shows a multi-institutional study led by the University of Pennsylvania and Children's National Hospital in Washington, D.C.
Unraveling gene expression
EPFL chemists have uncovered the first steps in the process of gene expression by showing how the protein Rap1 pries open the tightly wound, compacted structure of DNA in the cell to gain access to specific genes.
Gene coding error found in rare, inherited gene cof lung-scarring disorder linked to short telomeres
By combing through the entire genetic sequences of a person with a lung scarring disease and 13 of the person's relatives, Johns Hopkins Medicine researchers say they have found a coding error in a single gene that is likely responsible for a rare form of the disease and the abnormally short protective DNA caps on chromosomes long associated with it.
The two faces of the Jekyll gene
Genes which are specific to a species or group of species can reflect important genetic changes within lineages.
Gene therapy vectors carrying the telomerase gene do not increase the risk of cancer
Researchers from the Spanish National Cancer Research Centre (CNIO) have shown in a new study that the gene therapy with telomerase that they have developed, and which has proven to be effective in mice against diseases caused by excessive telomere shortening and ageing, does not cause cancer or increase the risk of developing it, even in a cancer-prone setting.
Blindness gene discovered
Researchers from UNIGE have investigated a recessive genetic disorder that destroys the eyes from developing and results in childhood blindness.
Gene editing just got easier
An international team of researchers has made CRISPR technology more accessible and standardized by simplifying its complex implementation in a way that offers a broad platform for off-the shelf genome engineering.
Gene regulation: Risk-free gene reactivation
Chemical modification of DNA subunits contribute to the regulation of gene expression.
No gene is an island
Genes do not exist in isolation. Like beads on a string, they sit next to each other on the chromosomes.
New disease gene for axon degeneration identified through international gene matching
Research group from the University of Helsinki, Finland, has identified a new disease gene for early-onset axonal neuropathy and mild intellectual disability through an international research network, which was brought together by 'Tinder for geneticists'.
More Gene News and Gene Current Events

Trending Science News

Current Coronavirus (COVID-19) News

Top Science Podcasts

We have hand picked the top science podcasts of 2020.
Now Playing: TED Radio Hour

Our Relationship With Water
We need water to live. But with rising seas and so many lacking clean water – water is in crisis and so are we. This hour, TED speakers explore ideas around restoring our relationship with water. Guests on the show include legal scholar Kelsey Leonard, artist LaToya Ruby Frazier, and community organizer Colette Pichon Battle.
Now Playing: Science for the People

#569 Facing Fear
What do you fear? I mean really fear? Well, ok, maybe right now that's tough. We're living in a new age and definition of fear. But what do we do about it? Eva Holland has faced her fears, including trauma and phobia. She lived to tell the tale and write a book: "Nerve: Adventures in the Science of Fear".
Now Playing: Radiolab

Uncounted
First things first: our very own Latif Nasser has an exciting new show on Netflix. He talks to Jad about the hidden forces of the world that connect us all. Then, with an eye on the upcoming election, we take a look back: at two pieces from More Perfect Season 3 about Constitutional amendments that determine who gets to vote. Former Radiolab producer Julia Longoria takes us to Washington, D.C. The capital is at the heart of our democracy, but it's not a state, and it wasn't until the 23rd Amendment that its people got the right to vote for president. But that still left DC without full representation in Congress; D.C. sends a "non-voting delegate" to the House. Julia profiles that delegate, Congresswoman Eleanor Holmes Norton, and her unique approach to fighting for power in a virtually powerless role. Second, Radiolab producer Sarah Qari looks at a current fight to lower the US voting age to 16 that harkens back to the fight for the 26th Amendment in the 1960s. Eighteen-year-olds at the time argued that if they were old enough to be drafted to fight in the War, they were old enough to have a voice in our democracy. But what about today, when even younger Americans are finding themselves at the center of national political debates? Does it mean we should lower the voting age even further? This episode was reported and produced by Julia Longoria and Sarah Qari. Check out Latif Nasser's new Netflix show Connected here. Support Radiolab today at Radiolab.org/donate.