Dog Hair Can Be Used to Diagnose Hormonal Problems in Dogs

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        A surprisingly large number of dogs suffer from hyperadrenocorticism. The symptoms are caused by excessive amounts of hormones -- glucocorticoids -- in the body. Unfortunately, though, diagnosis of the disease is complicated by the fact that glucocorticoid levels naturally fluctuate and most methods for measuring the concentration of the hormones in the blood provide only a snapshot of the current situation.

 Recent research at the University of Veterinary Medicine, Vienna has shown that glucocorticoids accumulate in the animals' hair and that analysis of a dog's hair can provide quick and reliable preliminary diagnosis.
Just over a century ago, Harvey Cushing published an account of a young woman who showed unusual symptoms because her glands were making excessive amounts of something. 

Subsequent research has shown that the thing in question is a set of hormones known as glucocorticoids that are produced by the adrenal glands, so "Cushing's disease" is now more commonly known as hyperadrenocorticism, at least by those who can pronounce it. The condition is particularly common in dogs, particularly as the animals grow older. Most cases result from a tumour in the pituitary gland but some relate to tumours in one of the adrenal glands themselves.(http://animalzoon.blogspot.in/)

Life in Antarctica Relies on Shrinking Supply of Krill

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On the Antarctic island of South Georgia, in February, toward the middle of what passes for summer at the bottom of the world, I hurried through the ruined whaling station of Grytviken.

I had an appointment at the British Antarctic Survey station on the opposite side of King Edward Cove. I was to interview a marine ecologist working on krill. I did not want to be late.

The keystone of the South Georgia ecosystem, the secret to the miraculous abundance of wildlife on this stark, cold, windswept island—the foundation, indeed, for almost all vertebrate life in the Antarctic—is krill.

South Georgia and the South Sandwich Islands are administered from the Falkland Islands as a British Overseas Territory, in which the little outpost of Grytviken is the only inhabited spot. The inhabitation is very marginal. In southern winter there are just eight staff members of the British Antarctic Survey, including a doctor, a government officer, and a postal clerk. A handful of visiting scientists augment this skeleton crew in southern summer.

Grytviken is gritty and grim. The name means "Pot Bay," a reference to the cauldrons in which the Norwegian whalers here rendered oil from blubber. It is apt. The rusting vats, boilers, ramps, chimneys, and ramshackle buildings of the long-abandoned whaling station; the wrecks of the catcher boats stranded on the waterfront; and the rows of giant whale-oil tanks upslope are all the apparatus of a genocide, in the literal, Latin sense of the word. The genus was Balaenoptera, the baleen whale.

Shark Familes Not So Nuclear

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Discovery's Shark Week: Aug. 4-10.
Multiple paternity appears to be very common among sharks and has been documented in at least six species so far: leopard sharks, small-spotted catsharks, bonnethead sharks, lemon sharks, nurse sharks and sandbar sharks.

The most widely accepted explanation for multiple paternity is what's known as "convenience polyandry."

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"Basically, the female doesn't have much say about who she mates with," lead author Andrew Nosal of Scripps Institution of Oceanography's Marine Biology Research Division told Discovery News. "If a male encounters her and wants to mate, he will."

"At this point, the female has two options," Nosal continued. "She can attempt to fight and escape, but may incur greater injury in the process. Or she can acquiesce to minimize physical damage to her body...As a matter of convenience, to minimize the chance of injury, the female may just go along with it, even though there appears to be no biological need to mate with more than one male per reproductive cycle."

Nosal and colleagues Eric Lewallen and Ronald Burton focused their study on leopard sharks living off the coast of La Jolla, Calif. The study has been accepted for publication in the Journal of Experimental Marine Biology and Ecology.

To determine the number of shark dads per litter, the researchers took DNA samples from 449 leopard shark pups from 22 litters. The average litter size for this particular shark species is about 20 pups.

Elephants Out-compete Rhinos at Salad Bar

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Elephants get first dibs at the African savannah salad bar, which may force rhinos to dine on lower quality food and a more limited diet.

When elephants abound in an ecosystem, a South African study found that black rhinos (Diceros bicornis) tend to eat more grass than in nearby areas with fewer elephants. Grass contains more fiber per the amount of energy it contains, and thus provides rhinos with less nutrition per pound than other floral food sources.

However, when African elephants (Loxodonta africana) are absent, an analysis of rhino poop found evidence that the horn-headed herbivores devour a wider variety of vegetation, including leaves from shrubs, succulent plants and liana vines.

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“Despite extensive evidence of the effects of elephant on food resources in the Addo Elephant National Park (where the study was conducted) and elsewhere few studies have investigated the consequences of this for other large herbivores,” wrote the authors in the journal PLOS ONE. “Surprisingly, where this information exists, the emphasis has been on demonstrating that elephant facilitate herbivore access to habitat and increase the availability and quality of food. This is despite clear evidence that elephants limit herbivore abundances across ecosystems through their ability to monopolize resources.”

The elephant-enforced diet may harm rhino health. Analysis of the chemical composition of rhino droppings found that levels of the important nutrient phosphorus were lower in rhinos living in areas where pachyderms predominated.