Tag Archive | zebrafish

Horses with spots and giraffes with stripes

Shigeru Kondo (Institute of Frontier Biosciences, Osaka University, Japan) gave one of the last talks at the “Computational approaches to networks, cells and tissues” meeting that took place this week  at the PRBB Auditorium.

Co-organised by James Sharpe (CRG) and Hernán López-Schier (HZM), the meeting was supported by QuanTissue, a collaborative European network to bridge the gap between the traditional developmental cell biology, biophysics and systems biology. And so it did!

Most of the nearly 200 participants were physicysts or mathematicians, as one could tell from their presentations and posters full of complicated mathematical formulae. But the subjects they studied were all related to the development of tissues and organs within organisms.

Kondo, for example, talked about the pigmentation pattern of zebrafish and how the Turing model could explain it.

Although his lab found there is no actual diffusion of any molecules, they showed that the interaction between the two types of pigment cells that define the skin patterns in the fish can still be explained by the Turing reaction-diffusion model. Melanophores, one of the cell types, elongate long projections towards xanthophores, the other cell type, and the effect of this is mathematically equivalent to the classical Turing model. Interestingly, he showed how, changing one single gene his lab was able to generate fish with skin patterns resembling most of those present in nature, from leopards and jaguars to zebras. Hence, the title of this posts, with which he finished his talk: “If you want horses with spots or giraffes with stripes, I can make it!”.

The meeting is still going on – another two hours of good science if you rush!

A report by Maruxa Martinez, Scientific Editor at the PRBB

8th European Zebrafish Meeting – registration open!

zebrafish mtg logo

The “8th European Zebrafish Meeting” will be held at the Palau de Congressos de Catalunya, 9-13 July 2013.  Organisers include Berta Alsina, from the CEXS-UPF, as well as Angela Nieto (CSIC-Alicante), Paola Bovolenta (CSIC-Madrid), Jose Luis Gómez-Skarmeta (CSIC-Sevilla), Enrique Martin Blanco (CSIC,Barcelona) and Miguel Angel Pardo (Azti-Tecnalia, Derio).

The meeting is intended to serve as a platform of communication for researchers working in zebrafish, a community that has expanded exponentially over the last decade. The  European biannual meeting.

Among many others, topics will cover new advances in life imaging, patterning, disease models, gene regulation and genomics, circuits and behaviour, drug screening and cancer.

Prof Sydney Brenner and Prof Denis Duboule, as keynote speakers working with other model organisms, will highlight their discoveries in C.elegans and mouse genetics.

For more information, please see http://www.zebrafish2013.org.

Remember to register early!

Deadline Abstract Submission: 24 March 2013
Deadline Early Registration: 30 May 2013

Phosphorylase kinase PhKG1, a new target for anti-angiogenesis therapies

A team of researchers from the CMRB directed by Juan Carlos Izpisúa Belmonte has discovered two novel inhibitors of the phosphorylase kinase subunit G1 (PhKG1) that has been identified for the first time to be involved in angiogenesis in vivo. Furthermore, they found that PhKG1 mRNA levels are elevated by more than two-fold in the majority of human tumors (breast, colon, kidney, lung, liver and thyroid), except in prostate cancer. The study was published in Oncogene.

Pathological angiogenesis, the growth of microvessels from existing vasculature, is associated with tumor progression and is a pre-requisite of tumor growth and metastasis. Therefore, inhibitors of angiogenesis are desirable candidates for anti-tumoral therapies.

First, the researchers screened for angiogenesis inhibitors from a compound library of putative kinases from the Dutch company Galapagos, BV, using an automatic quantitative screening assay. They used embryos of a zebrafish line in which the vascular system is visible through endothelial-specific enhanced green fluorescent protein (EGFP) expression. The assay was implemented at the high-throughput screening platform of Biobide SL.

The authors selected two new compounds that were found in the assay as inhibitors of angiogenesis and identified PhKG1 as their target through an in vitro kinase profiling. Finally they confirmed that the two compounds inhibited specifically the angiogenic process of vessel sprouting, as opposed to inhibition of general vasculogenesis, by treating embryos with either drug before the vasculogenic vessels had formed.

Image:
Effects of the PhKG1 inhibitors F10 and F11 on the processes of angiogenesis and vasculogenesis

Reference:
Camus S, Quevedo C, Menéndez S, Paramonov I, Stouten PF, Janssen RA, Rueb S, He S, Snaar-Jagalska BE, Laricchia-Robbio L, Izpisua Belmonte JC. Identification of phosphorylase kinase as a novel therapeutic target through high-throughput screening for anti-angiogenesis compounds in zebrafish. Oncogene. 2011 Dec 19;

Regenerating broken hearts

Chris Jopling joined the CMRB as a postdoctoral research scientist in June 2007. Since then, he has been investigating heart regeneration in zebrafish. The technicians M. Carme Fabregat and Guillermo Suñé, as well as Veronika Sander, another postdoctoral researcher, collaborate with the English biochemist in this line of research.

They are all trying to find out which genes are involved in heart regeneration in the zebrafish, Danio rerio. “You can cut off up to 20% of a ventricle of an adult fish, and in one month it is completely regenerated”, explains Jopling. Mammals are able to regenerate some tissues, such as blood or liver, but not heart. At least that is what scientists used to think. Earlier this year, it was found that newborn mice were able to regenerate their hearts, even though this ability was lost after just one week. This means that mammals actually do have the potential for heart regeneration.

Not everything is stem cells

For years, researchers have thought that stem cells were responsible for regeneration in the heart, and many groups around the world look for these stem cells. But Jopling and his colleagues at the CMRB showed, in 2010, that heart regeneration in zebrafish did not involve stem cells at all (you can see here the full paper). Rather, it was the cardiomyocytes (heart muscle cells) that dedifferentiated and started proliferating upon heart amputation. “Interestingly, the neonate mice regenerated their heart in the same way that the zebrafish do, that is, through the differentiated heart cells, and not through stem cells”, says Sander.

So far, only five genes have been demonstrated to be directly involved in heart regeneration in zebrafish. The aquatic animals group has identified three more genes that, if mutated or over-activated, block regeneration. In order to find these genes, the researchers followed a specific protocol. “We make a small cut on the ‘chest’ of the fish (just above its heart). If you then squeeze gently, the heart ventricle comes out. You then just grab it with very small forceps and make a cut with the scissors”, explains Jopling. The fish are sent back to their tank, where they continue swimming peacefully. Fourteen and thirty days after the amputation, the researchers check the status of heart regeneration. At the first time point, normal fish are in the peak of proliferation and, after a month, regeneration is complete. When the fish are transgenic or exposed to chemical additives that inhibit genes involved in regeneration, the process is halted.

A long way to go to mend a broken heart

The final aim of the research is to regenerate a human heart after a stroke. But there is still a long way to go. The CMRB group has already planned their next steps. First, they will check how the newly identified genes affect the expression of other genes by using microarrays and comparing the gene expression of a normal regenerating heart with that of a heart in which these genes have been modified. That should help to better understand how these genes regulate regeneration and which pathways they are involved in.

The scientists will then move on to mice. Since most genes in the zebrafish have homologues in mammals, they will check whether the identified genes are able to induce proliferation of cultured mouse cardiomyocytes. Mouse heart muscle cells usually don’t proliferate, so a cell culture can only last about a week. If the researchers are able to get the cells in the culture to replicate and proliferate by using these new genes, they will then generate transgenic mice. And bring us all a step closer to mending a broken heart.

This article was published in the El·lipse publication of the PRBB.


New animal models for biomedical and biotechnology research: The zebrafish

Juan Martín-Caballero at the Barcelona Biomedical Research Park animal facilities – Photo: © Diario Médico

The zebrafish (Danio rerio) is frequently used in drug discovery and key aspects of developmental biology. Mostly because of its quick development time (its organs are fully formed after just 48 hours) and transparent embryos. Above all, in research into regenerative medicine, because the fish is able to regenerate part of its caudal fin or, even, more than half of its heart. One of the main lines of research carried out with this animal model is that to discover the genes involved in regenerative processes. Several researchers at the PRBB have recently published work related to this topic in important scientific journals.

At the PRBB facilities, we have dozens of different strains of this fish, with 4,500 aquariums that can hold 50,000 adult fish. Hundreds of mutations of this species have already been created to study multiple human and animal illnesses, as it can be genetically modified easily and in a short time, only a few weeks, the effects of the genetic modification or chemical compound in question can be seen. As fertilization in this species is external, it isn’t necessary to euthanize the female in order to extract the embryos like in rodents.

The US FDA has calculated that up to $100 millions could be saved in drug discovery costs if the initial screening to select possible molecules was carried out on zebrafish embryos. This small fish, which measures only three or four centimeters in length at the adult stage, makes a great animal model, laying some 200 eggs per week. Its social impact is much lower as an animal model for biomedical and biotechnology research, and from a legal standpoint the use of embryos from this fish, which is less than five days old, isn’t subject to the European regulations that apply to any vertebrate used for scientific research.

This is an extract of the expert article by Juan Martin Caballero, director of the PRBB animal facility published at Biocat, the bioregion of Catalonia.

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