Posts Tagged ‘electricity’

The electric, flashy development of tadpoles

// July 22nd, 2011 // 1 Comment » // Recent Research

Tufts researcher Dany Adams was filming the development of tadpole embryos, when she decided to leave the camera hooked up to a microscope going overnight. She was hoping to get some good time-lapse footage. What she got was bioelectric patterns which flashed across the developing tadpole face, outlining the future positions of eyes, nose and mouth.

“I was completely blown away.” said Dany, Ph.D, according to the Tufts press release. “I think I thought something like, ‘OK, I know what I’ll be studying for the next 20 years.” It had never been seen before, and was published in the August issue of Developmental Dynamics. Watch the video below.

“When a frog embryo is just developing, before it gets a face, a pattern for that face lights up on the surface of the embryo,” said Dany. “We believe this is the first time such patterning has been reported for an entire structure, not just for a single organ. I would never have predicted anything like it. It’s a jaw dropper.”

Bioelectric signals cause cells to form patterns marked by differences in pH levels and membrane voltage, according to the researchers. The tadpoles were stained with a reporter dye that caused negatively charged areas to shine brightly while other areas look dark.

There were three bioelectric waves they saw in the footage.

xenopus

It's Xenopus! Image by Luis Beltran

First, a wave of negative ions flashed across the whole embryo at about the same time as cilia formed, tiny hairs which allow the embryo to move.

The second flash was a patterning that matched shape changes that were soon to occur in the face region. Bright areas, negative ions, show places where the surface will fold in.

Thirdly, localised regions of bright, negative areas formed, grew and disappeared without disturbing the existing pattern. At this point, the embryo began to elongate.

If bioelectric signalling is important to embryo development, you would expect development to be altered by screwing around with the signal process – and that’s exactly what happened. The researchers disrupted signalling by inhibiting a protein involved called ductin, which transports hydrogen ions. Some embryos grew two brains, others had unusual nasal or jaw development, and so on.

Interesting, I guess, but a bit sad for the baby tadpoles imho. Plus, I feel like it doesn’t take much to disrupt embryo development. Take away any protein that’s switched on at that sensitive time and development takes a detour…

All the same, bioelectricity may play a crucial role in embryo growth. Laura Vandenberg, another author on the paper, said “developmental biologists are used to thinking of sequences in which a gene produces a protein product that in turn ultimately leads to development of an eye or a mouth. But our work suggests that something else – a bioelectrical signal – is required before that can happen.”

ResearchBlogging.org

Vandenberg, L., Morrie, R., & Adams, D. (2011). V-ATPase-dependent ectodermal voltage and ph regionalization are required for craniofacial morphogenesis Developmental Dynamics, 240 (8), 1889-1904 DOI: 10.1002/dvdy.22685

Platypus. Poisonous, egg laying mammal with ten sex chromosomes

// October 13th, 2010 // 7 Comments » // Recent Research, Science Communication, Sex and Reproduction, The Realm of Bizzare

Platypus

Image by Urville Djasim

Ah, the elusive platypus. The water dwelling animal with fur, webbed feet and a beak. It may just be the strangest animal on the planet. Not only does it look weird, it’s poisonous, can sense electricity, lays eggs and secrete milk through their skin, and have an excessive number of sex chromosomes.

It’s poisonous.
It is SERIOUSLY poisonous. The males have poison barbs under their front feet which they mainly use during the spring breeding season. One scratch from these babies and you will be in terrible agony.

My friend studied platypuses (yes, that’s the plural I checked) in honours and her colleague injected himself with platypus venom in the name of science. For months he had excruciating pain for months which did not respond to any painkillers, including morphine. Because of this quality, platypus venom could help scientists develop drugs which work differently to our current repertoire.

Research into platypus venom is lacking because it is hard to come across samples. But just last month researchers identified 83 possible venom genes using DNA extracted from an active venom gland. Some of the genes are similar to those in snakes, pufferfish and starfish. Now the platypus hardly evolved from a starfish. Instead, it’s an example of convergent evolution, traits that arise separately in different species and give a selective advantage. Illustrious journal Nature says platypus venom confirms the convergent evolution theory for venom. (Research paper Whittington CM, & et al (2010). Novel venom gene discovery in the platypus. Genome biology, 11 (9) PMID: 20920228)

Electroreceptor bill
Sharks use electroreception to find prey by sensing the electricity animals have in their body. Monotromes (mammals that lay eggs) including platypuses and echidnas, are the only mammals with the same ability, and the platypus is the strongest. Closing its eyes and nose when it dives, the platypus relies almost entirely on electrolocation and touch to find the tasty crustaceans it snacks on. Sharks and platypuses are hardly related, making this another yet another example of convergent evolution.

Electroreceptors are located in rows on the bill, which might help it find prey by noticing which receptors pick up the electricity first. We do the same thing with our ears, hearing noises at slightly different times tells us which direction the sound is coming from. When the platypus hunts, it moves its bill side to side, which might reveal how far away the prey is. It’s similar to how pigeons bob their head for depth perception.

Image by TwoWings

Laying eggs
A female platypus has two ovaries, but only the left one is functional. Why? We don’t know.

Eggs spend 28 days developing inside their mother’s body and 10 days outside. The babies (often called puggles) are born with teeth, which drop out as they mature.

The mother produces milk, but she doesn’t have teats or nipples. Instead puggles lick or nibble on her skin to drink, gaining nutrients and probably an immune system. Living in mud, platypuses are born with no immune system, making them worse off than human babies which have immature immune systems at birth and rely on colostrum to boost their protection.

Sex chromosomes
Since the platypus genome was sequenced in 2008, we know a bit about these strange sex chromosomes. We know that they are more similar to birds than mammals, suggesting that our own mammal-like reptile ancestors might have had sex chromosomes like the birds of today. But there’s one big difference that makes the platypus unique.

They have ten sex chromosomes. Males have five X and five Y. Females have ten X. Humans, in fact, almost all mammals have only two. During platypus sperm production, the sex chromosomes pair up as X1Y1, X2Y2, X3Y3, X4,Y4, X5,Y5, so they can split evenly to make sperm that have 5X or 5Y. Phew. After all that, I’m surprised the males have any energy left for mating.

Solar powered laptop bags and handbags

// August 5th, 2010 // 7 Comments » // Science Art, Science at Home

Voltaic Generator Bag

Winter sun is something worth enjoying. Spreading out lizardlike and soaking up UV rays to make Vitamin D is an excellent endeavour. I often take my laptop out with me and blog in the sunlight.

Today as I was doing just that, my laptop started complaining about low charge. It made me wonder if you could solar power your laptop. Turns out you can.

You can have a panel on just about anything. Most only charge small devices like a phone, but you can have one on your desk, one on your bike, or even one on your hat (powering a small fan which spins faster as it gets more sun.)

The one pictured is a laptop bag with solar panels on the front, and it’s capable of charging a laptop. They charge a battery inside the bag, which you can run your laptop on.

Solar Handbag

I did a bit more snooping, and I found some fashionable handbags that do a similar job. These were sold on auction in mid July (one of a kind, probably couldn’t have afforded them anyway), and feature sexy solar panels that can charge your ipod, camera or phone as you walk.

It’s part of the portable light project, which has sadly finished. They create flexible photovoltaic textiles for use in developing countries. The material lends itself to traditional weaving and sewing, so people can incorporate the technology into their own culture. Open source electricity.

The solar units charge during the day, and at night work as lamps. They also have a USB port to charge phones, making it easier for traveling artists to connect with stores or midwives to seek clinic advice and diagnosis.

A mighty fine endeavour, but I’d be happy with something that quickly charged my iPod nano because he has problems. It leaks charge all over the joint like a poorly toilet trained puppy. I leave it switched off and locked in my bag, and next time I try to use it, it’s gone to Davey Jones locker. Perhaps it be time to update to an iPhone…






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