Friday, 30 January 2015

Baleen whales hear through their bones

January 29, 2015

San Diego State University

Understanding how baleen whales hear has posed a great mystery to marine mammal researchers. Biologists reveal that the skulls of at least some baleen whales, specifically fin whales in their study, have acoustic properties that capture the energy of low frequencies and direct it to their ear bones.

Frogs Prove Ideal Models for Studying Developmental Timing - Herp Digest

University of Cincinnati research shows that thyroid hormone receptor alpha plays an important role in hind limb development in frogs. The results of this study may shed light on the importance of hormones in early development in humans.
University of Cincinnati endocrinology researchers were recently able to mutate the thyroid hormone receptor (THR) in one of two cells during the first step of early egg division in tadpoles. As a result, they have successfully disrupted the developmental timing of the hind limbs, showing clear evidence for the importance of THR in the early development of vertebrates. The results of this study may also have the potential to shed light on the importance of hormones in early development in humans. 

With new gene mutation technology developed in the last two years, UC researcher Daniel Buchholz, associate professor of biological sciences and graduate student Jinyoung Choi, along with scientists in the Department of Mathematical and Life Sciences at Hiroshima University, were able to successfully mutate the gene in the tadpole models. Together, they found the value of tadpoles as ideal models for studying the role of hormones in development because of the timely metamorphosis from tadpole to juvenile frog, and because that transition is completely dependent on hormones. 

Choi and Buchholz recently published this research in the prestigious journal Endocrinology, titled Unliganded thyroid hormone receptor alpha regulates developmental timing via gene repression as revealed by gene disruption in Xenopus tropicali. Choi will also present their research at the 2015 ENDO Conference in March in San Diego, and Buchholz will present their work at the NASCE (North American Society of Comparative Endocrinology) biannual meeting in Toronto, June 21-25.

In earlier studies, Buchholz found that tadpoles don’t metamorphose in the absence of hormones. They instead just become larger tadpoles.

Hind limb phenotype in F1 offspring. Representative sibling offspring from a pair of TR! TALEN founders were imaged at feeding stage (upper panel). The developmental difference in hind limbs is shown in the lower panels. The hind limbs are bracketed.

This phenomenon was first discovered in 1916 when scientists were able to surgically remove the thyroid gland and found out that thyroid hormone is required for metamorphosis. Now, at the almost 100-year anniversary of this revelation, Buchholz and Choi are now able to study the other part of the story. 

“Now we can manipulate the genes and the proteins that are the receptors to look even further into what these receptors do,” says Buchholz. “This new technology has been cited in Science and Nature Magazines and could very well revolutionize the study of non-model organisms. Other scientists have been using this technology in other organisms, but we are one of the first to use the technology in tadpoles.”

Since Hiroshima University was already using this new technique, they supplied Buchholz and Choi with the technology and sent the reagents here to make the mutation. 

During the first step of development where the egg divides into two, Choi was able to mutate the THR in only one of the cells. While that cell makes up half the body, Choi was able to label what cell she manipulated, which gave rise to that half of the body. From that she could determine which side had the mutation and which side was normal. They then looked at what happened during development and consequently had a perfect control inside the same animal.

Buchholz explained that the study gets even more remarkable. Ironically, his post-doc advisor Yun-Bo Shi at the National Institutes of Child Health and Development (NICHD) –– where Buchholz first looked at molecular biology in frogs from 2000 to 2006 –– also studied this exact technology on tadpole models at the same time. While Buchholz, Choi nor Shi at NICHD knew about each others' studies until recently, they all found the same result after mutating only one hormone receptor. 

In a sort of twin study, UC and NICHD replicated each others' studies and found identical results. As a consequence, both papers are published in Endocrinology at the same time and the publication will also produce a News and Views article on this topic because of the unique situation. 

In mice, Buchholz points out that scientists have been able to knock out the gene for quite awhile because of the special structure of their reproduction system that can make embryonic stem cells. But in tadpoles, Choi and Buchholz were able to remove just one of the two (alpha and beta) thyroid hormone receptors. By knocking out only the alpha-receptor, Choi was better able to determine what each receptor controls in an organism.

“We already know what will happen if there is no thyroid hormone signal, as it will simply take away the hormone,” says Buchholz. “In humans, no hormone at all creates cretinism where the person has short stature and mental retardation. So in that case it becomes quite severe.”

In humans, Buchholz also explains that THR alpha controls heart rate, and THR beta controls thyroid hormone levels, and during development, also controls hearing. So being able to distinguish what one receptor does to the other is pretty important and has distinct consequences, especially when compared to just no hormone at all.

Frog metamorphosis has been compared to birth in humans because during frog metamorphosis there is a peak in blood levels of thyroid hormone dependence, and there is also a peak in thyroid hormone blood levels at the moment of birth in humans. Since humans and frogs are both vertebrates, Buchholz explains that there are many other similarities and the thyroid hormone receptors alpha and beta are expressed in similar cells types. 

The cells can respond to similar agonists and antagonists, which are chemicals that can block or induce thyroid hormone function. With this technology, we can test those kinds of chemicals and study what effects they have on the role of the receptors. 

“Knowing that what the THRs do in frogs is very similar to what they do in people, we can hopefully better understand what is happening in people during the developmental stage, which is very difficult to study in humans,” says Buchholz. 

Date: 1/26/2015 7:00:00 AM/By: Melanie Titanic-Schefft
Phone: (513) 556-5213/Other Contact: M.B. Reilly
Other Contact Phone: (513) 556-1824/Photos By: Daniel Buchholz

Funding:  Junyoung Choi earned a $3,000. Sigma Chi grant in aid of this research.

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Urban sprawl promotes worm exchange across species

January 28, 2015

University of Adelaide

The complex exchange of parasitic worms between wildlife, rats and humans is a little more clear, thanks to new research. “We developed a model concept that allows us to link the probability of worm species occurring in wildlife and occurring in rats, and linked them to the probability of this occurring in a certain geographical area,” he says the lead author says.

Record sea lion pup strandings reported in Southern California

By Marty Graham15 hours ago

SAN DIEGO (Reuters) - California sea lions – mainly pups – are turning up stranded and starved on Southern California beaches in record numbers this year, leaving experts worried that this winter may be the worst season ever documented for the marine mammals.

The precise cause is not clear, but scientists believe the sea lions are suffering from a scarcity of natural prey that forces nursing mothers to venture farther out to sea for food, leaving their young behind for longer periods of time.

Postal strike ends boxed lizards’ lives - Herp Digest

Durban-January 24 2015 - By Arthi Sanpath The Independent on Saturday

Stuffed into a tiny box crammed with sweets and toys, six spiny rock and green crocodile lizards were smuggled from Mexico to South Africa.
But this became their final resting place as five died, lying in the box for nearly four months when the postal service went on strike.
Only one survived the journey in the box, which had no ventilation, and the wait in the rooms of the mail centre, but was put down after its rescue by the National Council of SPCAs.
“It was incredibly sad,” said its Wildlife Protection Unit’s Arno de Klerk.
The illegal trade in wild animals was prevalent across the whole country, he said.
NSPCA inspectors had been called to the Expedited Mail Services international mail centre at OR Tambo International Airport, in Joburg, by a customs official after a rotten smell was noted coming from a package lying among piles of undelivered mail.
“On inspection, five dead and decomposing rock and green crocodile lizards were found, as well as a dehydrated lizard hanging on to life. The lizard was humanely euthanased to prevent further suffering,” said De Klerk.
The lizards had been posted to an address in Joburg from Mexico and the live animals were packed among sweets and toys. De Klerk said no provision had been made for the welfare of the animals.
“It is believed that, as a result of the strike, the box had been lying at the mail centre for four months before discovery.”
The recipient was tracked down by the NSPCA and SAPS and faces cruelty charges.
“We are shocked that so little regard was paid to these suffering animals that were treated as commodities.
“NSPCA inspectors remain vigilant to the on-going illegal trade in wild animals and we will take a hard line against perpetrators of cruelty, wherever this is encountered. This cruelty has to stop.”
He said it was not illegal to import them. “You are allowed to import animals if you have all the proper paperwork in place and do so in the proper manner.
This incident is considered illegal smuggling because animals are not allowed to be transported via the postal service, and there was no paperwork attached or submitted.
There was no provision made for them.”
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