The study of human diseases continues to be a priority in today’s day and age. Many biological research studies have focused their efforts on trying to identify and interpret the underlying genetic cause of both rare and common diseases alike.

In order to understand the genetic basis of human disease, scientists have utilised patients’ cells and other tissue samples, as well as experimental animal models of human disorders. Traditionally, mice and rats have been the preferred animals of choice since they exhibit high similarity to human characteristics. Nonetheless, they also bear considerable limitations, including absence of the corresponding gene of interest, high costs, space requirements and low number of offspring. Alternative animal models have thus been considered, particularly the zebrafish model.

Scientifically known as Danio rerio, zebrafish get their name from the horizontal blue stripes that run along the sides of their body. Compared to their furry competitors, these small, robust freshwater fish are cheap and easy to maintain, reproduce in high numbers that develop rapidly outside their mother’s body and can be easily altered genetically. But what makes these tiny models so special? Surprisingly, despite the massive difference in appearance, three quarters of their genetic structure is similar to humans, giving scientists the possibility to study the role of previously unknown genes in human diseases, including muscular dystrophy, cancer and many others.

Zebrafish are almost transparent during the early stages of life, allowing the in vivo observation of internal organs and tissues. In addition, zebrafish possess the unique ability to repair damaged heart muscle – which provides major insights into the study of congenital heart defects and heart attacks. Zebrafish can also regenerate a severed spinal cord and certain amputated body structures such as scales and fins. The latter has been instrumental in the study of bone physiology, fracture repair and in identifying drugs to treat human bone diseases. Fish have bones, therefore it comes as no surprise that these animal models can be used to investigate bone diseases, including osteoporosis.

This silent and common bone condition decreases bone mass and strength culminating in increased fracture risk. A bone density test is routinely performed to diagnose osteoporosis and predict bone fracture risk in humans. Similarly, this procedure can be performed on zebrafish using other types of radiographic imaging. The genetic factors underlying osteoporosis are being studied extensively at the University of Malta.

The zebrafish is currently being utilised to study novel genetic factors hypothesised to contribute to osteoporosis. Zebrafish represent a versatile model possessing many other advantages that can be used to study a wide range of human diseases and might also help in finding a cure for such diseases.

The ultimate aim of genetic research remains that of elucidating the best treatment options based on the person’s genetic make-up and predicting disease outcome in susceptible individuals.

Dr Melissa Marie Formosa is a resear­cher involved in the project ‘Genetics of Osteoporosis’ and a lecturer at the Department of Applied Biomedical Science within the Faculty of Health Sciences, University of Malta.

Sound bites

• The word ‘piranha’ has its origins from the Tupi (Brazil) ‘pira nya’, and means ‘scissors’. Found in freshwater rivers in South America, piranhas have razor-sharp teeth. They typically eat fish, insects, seeds, fruit and even larger animals such as horses. While there are no proven reports of piranhas killing a person (so much for the movies!), they do eat human carcasses.

• Fish use a variety of low-pitched sounds to convey messages to each other. They moan, grunt, croak, boom, hiss, whistle, creak, shriek and wail. They rattle their bones and gnash their teeth. However, fish do not have vocal chords. They use other parts of their bodies to make noises, such as vibrating muscles against their swim bladder.

To find out some more interesting science news, listen in on Radio Mocha every Monday and Friday at 1pm and on Radju Malta 2.

Did you know?

• Most fish reproduce by laying eggs, though some fish, such as great white sharks, give birth to live babies called pups.

• Sharks are the only fish that have eyelids.

• Electric eels and electric rays have enough electricity to kill a horse.

• The oldest fishhook ever found dates back to about 42,000 years ago.

• Most brands of lipstick contain fish scales.

For more trivia see:

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