How pufferfish meditate magnesium to survive

Aug 27, 2013
Fig. 1 The team used linear and cyclic block copolymers to create flower-shaped micelles. The cyclic-based micelles withstood considerably higher temperatures and salinity levels, and could have numerous applications in industry and green chemistry.

Scientists at Tokyo Institute of Technology collaborate colleagues at Japan's Shimonoseki Academy of Marine Science and Mayo Clinic College of Medicine, Minnasota, USA, to uncovered the molecular mechanisms behind Mg2+ secretion in fresh and seawater Takifugu pufferfish species.

The bodily functions of creatures that live in are affected by the presence of ions of different elements in the water. Bodies naturally absorb and retain ions as , but an excess of any one ion in the body can be damaging.

The magnesium ion Mg2+ is the second most abundant cation in seawater. Both freshwater and seawater fish maintain a certain level of Mg2+ in the plasma in their bodies, and it has long been known that seawater fish secrete Mg2+ into their urine in order to avoid an excess of absorbed Mg2+ from their surroundings. However, certain species of fish are capable of living in both salt and freshwater conditions, and how they alter Mg2+ secretion in their bodies accordingly is not well understood.

Now, Akira Kato and co-workers at Tokyo Institute of Technology, together with researchers from Japan's Shimonoseki Academy of Marine Science and Mayo Clinic College of Medicine, Minnasota, USA, have uncovered the behind Mg2+ secretion in fresh and seawater Takifugu pufferfish species.

"For , Mg2+ is an important nutrient which should be retained if excess Mg2+ is not absorbed from food," explains Kato. "Seawater contains around 30 times more Mg2+ than the blood of seawater fish. If seawater fish cannot excrete excess Mg2+, they face hypermagnesemia which causes failure of normal in the nerves, muscles, and heart."

Hypothetical model for renal divalent ion excretion in marine teleost.

Open genome databases enabled Kato and his team to prepare a list of pufferfish genes that have homology to any known Mg2+ transporting systems in bacteria, plants, and mammals. Through this mammoth task, they pinpointed a gene called Slc41a1 that encodes ion-carrier proteins in other species and bacteria. Gene expression analyses showed that Slc41a1 genes are highly expressed in the duct system of the kidneys in pufferfish.

The team then compared the renal and intestinal expressions of Slc41a1 in seawater pufferfish Takifugu rubripes and the closely related euryhaline pufferfish Takifugu obscurus in both seawater and freshwater environments.

"We discovered that Slc41a1 expression was up-regulated when the fish were moved from freshwater to seawater conditions," explains Kato. Using immunohistochemistry techniques, the researchers proved that Slc41a1 is found in vacuoles (organelles) in the kidney and mediates Mg2+ movement from inside to outside cells. This secretion mechanism allows the excess ions to be flushed from the body in the urine.

"The molecular study of vacuolar Mg2+ secretion in the kidneys of seawater fish has just begun," states Kato. "We need to identify other components that support the function of Mg2+ transporter gene Slc41a1. We also need to confirm if similar systems are generally used by many different organisms, or if this method of secretion has specifically evolved in fish."

Explore further: Color patterns in fish larvae may reveal relationships among species

More information: Islam, Z. et al. Identification and proximal tubular localization of the Mg2+ transporter, Slc41a1, in a seawater fish. Am J Physiol Regul Integr Comp Physiol 305 (2013). DOI: 10.1152/ajpregu.00507.2012

add to favorites email to friend print save as pdf

Related Stories

On the way to hydrogen storage?

Apr 19, 2011

(PhysOrg.com) -- The car of the future could be propelled by a fuel cell powered with hydrogen. But what will the fuel tank look like? Hydrogen gas is not only explosive but also very space-consuming. Storage ...

New DNA-method tracks fish and whales in seawater

Aug 30, 2012

Danish researchers at University of Copenhagen lead the way for future monitoring of marine biodiversity and resources. By using DNA traces in seawater samples to keep track of fish and whales in the oceans. A half litre ...

Super first feed soon ready to serve

Aug 27, 2012

They can be stored for months and then hatch in seawater within 24 hours. Production of copepods, the ultimate live feed for Ballan wrasse and the fry of other marine fish species, can soon be industrialised.

Recommended for you

Offspring benefit from mum sending the right message

5 minutes ago

(Phys.org) —Researchers have uncovered a previously unforeseen interaction between the sexes which reveals that offspring survival is affected by chemical signals emitted from the females' eggs.

Lemurs match scent of a friend to sound of her voice

14 hours ago

Humans aren't alone in their ability to match a voice to a face—animals such as dogs, horses, crows and monkeys are able to recognize familiar individuals this way too, a growing body of research shows.

User comments : 1

Adjust slider to filter visible comments by rank

Display comments: newest first

ormondotvos
not rated yet Aug 27, 2013
The title should read "mediates" not "meditates". Otherwise it's very interesting.

More news stories

Ranchers benefit from long-term grazing data

Scientists studying changes in the Earth's surface rely on 40 years of Landsat satellite imaging, but South Dakota ranchers making decisions about grazing their livestock can benefit from 70 years of data ...

Floating nuclear plants could ride out tsunamis

When an earthquake and tsunami struck the Fukushima Daiichi nuclear plant complex in 2011, neither the quake nor the inundation caused the ensuing contamination. Rather, it was the aftereffects—specifically, ...

Unlocking secrets of new solar material

(Phys.org) —A new solar material that has the same crystal structure as a mineral first found in the Ural Mountains in 1839 is shooting up the efficiency charts faster than almost anything researchers have ...