Monday, 20 November 2017


The liger is a hybrid cross between a male lion (Panthera leo) and a female tiger(Panthera tigris). The liger has parents in the same genus but of different species. The liger is distinct from the similar hybrid tigon, and is the largest of all known extant felines.

The history of lion-tiger hybrids dates to at least the early 19th century in India. In 1798, Étienne Geoffroy Saint-Hilaire (1772–1844) made a colour plate of the offspring of a lion and a tiger. The portmanteau "liger" was coined by the 1930s.[4]
In 1825, G. B. Whittaker made an engraving of liger cubs born in 1824.[3] The parents and their three liger offspring are also depicted with their trainer in a 19th-century painting in the naïve style.
Two liger cubs born in 1837 were exhibited to King William IV and to his successor Queen Victoria. On 14 December 1900 and on 31 May 1901, Carl Hagenbeck wrote to zoologist James Cossar Ewart with details and photographs of ligers born at the Hagenbeck's Tierpark in Hamburg in 1897.
In Animal Life and the World of Nature (1902–1903), A.H. Bryden described Hagenbeck's "lion-tiger" hybrids:
It has remained for one of the most enterprising collectors and naturalists of our time, Mr. Carl Hagenbeck, not only to breed but to bring successfully to a healthy maturity, specimens of this rare alliance between those two great and formidable Felidae, the lion and tiger. The illustrations will indicate sufficiently how fortunate Mr. Hagenbeck has been in his efforts to produce these hybrids. The oldest and biggest of the animals shown is a hybrid born on the 11th May 1897. This fine beast, now more than five years old, equals and even excels in his proportions a well-grown lion, measuring as he does from nose tip to tail 10 ft 2 inches in length, and standing only three inches less than 4 ft at the shoulder. A good big lion will weigh about 400 lb [...] the hybrid in question, weighing as it does no less than 467 lb, is certainly the superior of the most well-grown lions, whether wild-bred or born in a menagerie. This animal shows faint striping and mottling, and, in its characteristics, exhibits strong traces of both its parents. It has a somewhat lion-like head, and the tail is more like that of a lion than of a tiger. On the other hand, it has no trace of mane. It is a huge and very powerful beast.[5]
In 1935, four ligers from two litters were reared in the Zoological Gardens of Bloemfontein, South Africa. Three of them, a male and two females, were still living in 1953. The male weighed 340 kg (750 lb) and stood a foot and a half (45 cm) taller than a full grown male lion at the shoulder.
Although ligers are more commonly found than tigons today, in At Home In The Zoo (1961), Gerald Iles wrote "For the record I must say that I have never seen a liger, a hybrid obtained by crossing a lion with a tigress. They seem to be even rarer than tigons."[6]

Size and growth

The liger is often believed to represent the largest known cat in the world.[1] Males reach a total length of 3 to 3.6 m,[7][8] meaning they are larger than large Siberian tigermales, who are themselves usually larger than the larger lion species.[9] Imprinted genes may be a factor contributing to the large size of ligers.[10] These are genes that may or may not be expressed on the parent they are inherited from, and that occasionally play a role in issues of hybrid growth. For example, in some dog breed crosses, genes that are expressed only when maternally-inherited cause the young to grow larger than is typical for either parent breed. This growth is not seen in the paternal breeds, as such genes are normally "counteracted" by genes inherited from the female of the appropriate breed.[11]
Other big cat hybrids can reach similar sizes; the litigon, a rare hybrid of a male lion and a female tigon, is roughly the same size as the liger, with a male named Cubanacan (at the Alipore Zoo in India) reaching 363 kg (800 lb).[12] The extreme rarity of these second-generation hybrids may make it difficult to ascertain whether they are larger or smaller, on average than the liger.
It is wrongly believed that ligers continue to grow throughout their lives due to hormonal issues.[citation needed] It may be that they simply grow far more during their growing years and take longer to reach their full adult size. Further growth in shoulder height and body length is not seen in ligers over 6 years old, as in both lions and tigers. Male ligers also have the same levels of testosterone on average as an adult male lion, yet are azoospermic in accordance with Haldane's rule. In addition, female ligers may also attain great size, weighing approximately 320 kg (705 lb) and reaching 3.05 m (10 ft) long on average, and are often fertile. In contrast, pumapards (hybrids between pumasand leopards) tend to exhibit dwarfism.
Ligers are about the same size as the prehistoric Smilodon populator and American lion.
Hercules the liger and his trainer Bhagavan Antle

Hercules the liger

Hercules, the largest non-obese liger, is recognised by the Guinness Book of World Records as the largest living cat on Earth, weighing 418.2 kg (922 lb).[13][14] Hercules was featured on the Today ShowGood Morning AmericaAnderson Cooper 360Inside Edition, and in a Maxim article in 2005, when he was only three years old and already weighed 408.25 kg (900 lb). Hercules is healthy and is expected to live a long life. The cat's breeding is said to have been a complete accident.


Shasta, a ligress (female liger) was born at the Hogle Zoo in Salt Lake City on 14 May 1948 and died in 1972 at age 24.[15] Valley of the Kings animal sanctuary in Wisconsin had a male liger named Nook who weighed over 550 kg (1,213 lb), and died in 2007, at 21 years old.[2] Hobbs, a male liger at the Sierra Safari Zoo in Reno, Nevada, lived to almost 15 years of age before succumbing to liver failure and weighed in at 450 kg (992 lb).[16] This liger was born in 1943 and died in 1960. South Africa still has two ligers at its one zoo at Bloemfontein.[17]


The fertility of hybrid big cat females is well documented across a number of different hybrids. This is in accordance with Haldane's rule: in hybrids of animals whose sex is determined by sex chromosomes, if one sex is absent, rare or sterile, it is the heterogametic sex (the one with two different sex chromosomes e.g. X and Y).
According to Wild Cats of the World (1975) by C. A. W. Guggisberg, ligers and tigons were long thought to be sterile: in 1943, a fifteen-year-old hybrid between a lion and an 'Island' tiger was successfully mated with a lion at the Munich Hellabrunn Zoo. The female cub, though of delicate health, was raised to adulthood.[18]
In September 2012, the Russian Novosibirsk Zoo announced the birth of a "liliger", which is the offspring of a liger mother and a lion father. The cub was named Kiara.[19]


Colour plate of the offspring of a lion and tiger, Étienne Geoffroy Saint-Hilaire
Ligers have a tiger-like striped pattern that is very faint upon a lionesque tawny background. In addition, they may inherit rosettes from the lion parent (lion cubs are rosetted and some adults retain faint markings). These markings may be black, dark brown or sandy. The background colour may be correspondingly tawny, sandy or golden. In common with tigers, their underparts are pale. The actual pattern and colour depend on which subspecies the parents were and on how the genes interact in the offspring.
White tigers have been crossed with lions to produce "white" (actually pale golden) ligers. In theory, white tigers could be crossed with white lions to produce white, very pale or even stripeless ligers. There are no black ligers. Very few melanistic tigers have ever been recorded, most being due to excessive markings (pseudo-melanism or abundism) rather than true melanism; no reports of black lions have ever been substantiated. As blue or Maltese tigers probably no longer exist, grey or blue ligers are exceedingly improbable. It is not impossible for a liger to be white, but it is very rare.

Tuesday, 15 August 2017


Supplementing the diet with vitamin B3 during pregnancy may treat the molecular deficiencies in women that can lead to birth defects, according to a landmark study in Australia.
Over the last 12 years, developmental geneticist Sally Dunwoodie (Victor Chang Cardiac Research Institute, Sydney) and team have been studying the genes that influence fetal heart and bone development. Genetic sequencing of four families with offspring affected by heart and bone defects showed that the families had gene mutations that affected the production of a molecule called nicotinamide adenine dinucleotide (NAD), which is essential for energy storage and DNA synthesis in cells.

Image: 3D rendered medically accurate illustration of a fetus in week 15.
The researchers have now described the mutations in the New England Journal of Medicine. The article also reports on studies showing that NAD deficiency in pregnant mice caused pups to be born with severe birth defects and that those defects could be prevented by vitamin B3 supplementation during pregnancy.
The researchers knocked out the genes associated with NAD production in pregnant mice, to see whether pups were born wit
h similar defects to those seen in the human babies. Initially, all pups were born healthy, but then the researchers realised that mouse chow is rich in niacin (vitamin B3), which cells can use in place of nicotinamide to make NAD.
The researchers then tried feeding the knock-out pregnant mice a diet that did not include niacin. This time, many of the pubs died before birth and those that were born had severe defects similar to the ones seen in the human babies. Next, the researchers fed the mutant mice low doses of niacin during pregnancy, which reduced the severity of the birth defects. When they tried feeding pregnant mice a diet rich in niacin, healthy litters of pups were born.
More human studies are needed before B3 supplementation could be recommended for pregnant women, but the current research suggests it may help to prevent birth defects in the offspring of families with NAD-related gene mutations.
“The ramifications are likely to be huge. This has the potential to significantly reduce the number of miscarriages and birth defects around the world and I do not say those words lightly,” says Dunwoodie.

Sunday, 13 August 2017


Nanotechnology wonders: Organ healing with a single touch!

Scientists from the Ohio State University Wexner Medical Centre have come up with what sounds like a science fiction -  a nanotechnology device that can switch the cell functions in such a way that the failing organs are revived using a single touch. This technique is called Tissue Nanotransfection (TNT) and the tiny nanotechnology devices inject a new genetic code into the skin cells. These genetically modified skin cells then transform into other types of cells that can help in the regeneration of the diseased cells. The study is published in the journal Nature Nanotechnology, authored by Daniel Gallego-Perez and team.
Chandan Sen, PhD, holds a chip that could revolutionize medical care. In laboratory tests on mice at The Ohio State University Wexner Medical Center, the chip was able to heal serious wounds with a single touch by converting skin cells into vascular cells.
Chandan Sen, PhD, holds a chip that could revolutionize medical care. In laboratory tests on mice at The Ohio State University Wexner Medical Center, the chip was able to heal serious wounds with a single touch by converting skin cells into vascular cells. Image Credit: Ohio State University
Dr. Chandan Sen, director of the Center for Regenerative Medicine and Cell-Based Therapies at The Ohio State University Wexner Medical Center explains that the chip would take only a single touch and a fraction of a second. As soon as it touches the wounded area, the cells begin to reprogramme into something different. For example they used the chip in the labs on injured legs of mice he said. The injured legs had little or no blood supply and were damaged to begin with. The chip instructed the skin cells to turn into blood vessel cells or vascular cells. The skin cells thus started becoming vascular cells and in a week improvement began noticeably. Within the second week the blood vessels were fully formed to the injured leg and by the end of third week the leg was saved with nothing other than the wonder nanochip.
Researchers demonstrate a process known as tissue nanotransfection at The Ohio State University Wexner Medical Center. In laboratory tests, this process was able to heal the badly injured legs of mice in just three weeks with a single touch of this chip. The technology works by converting normal skin cells into vascular cells, which helped heal the wounds. Image Credit: Ohio State University
Researchers demonstrate a process known as tissue nanotransfection at The Ohio State University Wexner Medical Center. In laboratory tests, this process was able to heal the badly injured legs of mice in just three weeks with a single touch of this chip. The technology works by converting normal skin cells into vascular cells, which helped heal the wounds. Image Credit: Ohio State University
Study collaborator Professor L. James Lee of chemical and biomolecular engineering department at Ohio State explained that this was gene therapy. He added that this concept was not a new one and has been studied for quite some time now. What is new is the delivery of the DNA that needs to be inserted into the host genetic code.