Biology Official Blog

Synthetic Mycoplasma bacteria, TEM

2010-12-28T10:54:00.000-08:00

Synthetic Mycoplasma bacteria, coloured transmission electron micrograph (TEM). The first self-replicating bacteria cell controlled by a synthetic genome was developed by scientists at the J. Craig Venter Institute, and announced in May 2010. The work involved producing a modified version of the Mycoplasma mycoides genome and inserting it into a Mycoplasma capricolum shell that had had its genetic material removed.

Cloning cows, nuclear transfer

2010-12-25T11:58:00.000-08:00

Cloning cows, nuclear transfer. Light micrograph of an egg (female reproductive cell) from a cow (Bos taurus) being manipulated by a micropipette (right) and needle (left) during the nuclear transfer stage of the cloning process. At this stage the genetic material from another cell is transferred into an egg cell which has had its genetic material removed. The work is being carried out at the Bio Sidus biotechnology company, in Argentina, which successfully cloned a cow in 2002. The cloned cows are intended to be used to produce human growth hormone (hGH) in their milk. Magnification: x150 when printed at 10 centimetres wide.

Telomere binding protein, molecular model

2010-12-24T14:21:00.000-08:00

Telomere binding protein. Molecular model of a TRF2 molecule (blue) bound to DNA (deoxyribonucleic acid, yellow and orange). TRF2 binds to telomeres, short repeated sequences at the ends of a chromosome. The complex between the protein and DNA helps to protect the chromosome against degradation and recombination.

Top Ten Discoveries of 2010 | Odd Species Found Off Greenland

2010-12-24T13:58:00.000-08:00

Odd Species Found Off Greenland

Photograph courtesy Julius Nielsen, Greenland Institute of Natural Resources

Looking like a creature from the Alien movies, this nightmarish "longhead dreamer" anglerfish was until recently an alien species to Greenland waters (map).

The dreamer, which grows to a not-so-monstrous 6.7 inches (17 centimeters) long, is 1 of 38 fish species found around the Arctic island for the first time, according to a study released in February.

Ten of the species new to Greenland are new to science, too. All 38 were discovered since the last such survey in 1992.

Top Ten Discoveries of 2010 | Lizard Evolving for Live Birth

2010-12-24T10:10:00.000-08:00

Lizard Evolving for Live Birth

Photograph courtesy Rebecca A. Pyles

Evolution has been caught in the act, according to a study we covered this summer suggesting that a species of Australian lizard is abandoning egg-laying in favor of live birth.

Along the warm coastal lowlands of New South Wales (map), the yellow-bellied three-toed skink lays eggs to reproduce. But individuals of the same species living in the state's higher, colder mountains are almost all giving birth to live young.

"Yoda Bat," Other Rarities Found | Top Discoveries of 2010

2010-12-24T08:18:00.000-08:00

"Yoda Bat," Other Rarities Found

Photograph courtesy Piotr Naskrecki, Conservation International

This tube-nosed fruit bat—immortalized elsewhere as the "Yoda bat"—is just one of the roughly 200 species encountered during two scientific expeditions to Papua New Guinea in 2009, including a katydid that "aims for the eyes" and a frog that does a mean cricket impression, Conservation International announced in October.

Though seen on previous expeditions, the bat has yet to be formally documented as a new species, or even named. Like other fruit bats, though, it disperses seeds from the fruit in its diet, perhaps making the flying mammal crucial to its tropical rain forest ecosystem.

In all, the expeditions to Papua New Guinea's Nakanai and Muller mountain ranges found 24 new species of frogs, 2 new mammals, and nearly a hundred new insects. The remote island country's mountain ranges—which have yielded troves of new and unusual species in recent years—are accessible only by plane, boat, foot, or helicopter.

BLOOD COAGULATION

2010-12-23T07:50:00.000-08:00

BLOOD COAGULATION Coagulation (1/3). (Cf. images no. 11796 05 and no. 11797 05 for stages 2 and 3) Coagulation, stage 1: following a vascular spasm, blood platelets immediately form a haemostatic plug, blocking the wound.

Taking blood sample

2010-12-23T07:46:00.000-08:00

Needle and vacutainer being used to take a blood sample. The needle holder is being held by a medical worker's hand. The needle has been inserted into a vein (a process called venepuncture). A tourniquet (partly seen at top right) is used to make the veins more visible. The vacutainer is the tube inside the needle holder. It contains a partial vacuum that is drawing the blood (red) into the tube and out of the patient's arm. The sample of blood will be labelled and sent for testing.

Snowshoe Hare

2010-12-23T04:57:00.001-08:00

Snowshoe Hare

Photograph by Michael S. Quinton

The aptly named snowshoe hare has particularly large feet and a winter-white coat. In the summer though, their fur turns brown, taking up to ten weeks to change color completely.

Baby Harp Seal : Winter Wildlife

2010-12-23T04:49:00.001-08:00

Baby Harp Seal

Photograph by Norbert Rosing

A baby harp seal rests on the Arctic ice. Its mother can distinguish it from hundreds of others by scent alone.

LM of human blood smear showing red & white cells

2010-12-21T08:35:00.000-08:00

Light micrograph of a smear of human blood consisting of red cells (erythrocytes) & two white blood cells (leucocytes) in the centre. The function of the erythrocytes is the distribution & transportation of oxygen & carbon dioxide to & from the cells of the body. Surrounded by a thin elastic membrane, the whole of the interior is filled with the red pigment haemoglobin, which has a good oxygen carrying capacity. Erythrocytes have a biconcave disc shape & are flexible so that they can accommodate themselves to the smallest of capillaries. The function of the leucocytes is that of defense against disease. Magnification x210 at 35mm size, x420 at 6x7cm size.

King Cheetah Cub

2010-12-20T12:52:00.000-08:00

Photograph by Chris Johns

Still just a prince, a rare king cheetah is the result of a recessive gene. Except for darker, elongated spots, king cheetahs are genetically identical to other cheetahs. The genetic homogeneity of cheetah populations may make them more vulnerable to disease.

Big Cats Initiative
National Geographic is working to avert the extinction of lions, tigers, and other big cats with the Big Cats Initiative, a comprehensive program that supports innovative projects. Learn how you can help save these animals.

Mexican Axolotl

2010-12-16T11:01:00.001-08:00

The ghostly looking Mexican axolotl retains some of its larval features for life, including its feathery pink external gills.

The Mexican axolotl (pronounced ACK-suh-LAH-tuhl) salamander has the rare trait of retaining its larval features throughout its adult life. This condition, called neoteny, means it keeps its tadpole-like dorsal fin, which runs almost the length of its body, and its feathery external gills, which protrude from the back of its wide head.

Found exclusively in the lake complex of Xochimilco (pronounced SO-chee-MILL-koh) near Mexico City, axolotls differ from most other salamanders in that they live permanently in water. In extremely rare cases, an axolotl will progress to maturity and emerge from the water, but by and large, they are content to stay on the bottom of Xochimilco’s lakes and canals.

Close relatives of the tiger salamander, axolotls can be quite large, reaching up to a foot (30 centimeters) in length, although the average size is closer to half that. They are typically black or mottled brown, but albino and white varieties are somewhat common, particularly among captive specimens.

Axolotls are long-lived, surviving up to 15 years on a diet of mollusks, worms, insect larvae, crustaceans, and some fish. Accustomed to being a top predator in its habitat, this species has begun to suffer from the introduction of large fish into its lake habitat. Natural threats include predatory birds such as herons.

Populations are in decline as the demands of nearby Mexico City have led to the draining and contamination of much of the waters of the Xochimilco Lake complex. They are also popular in the aquarium trade, and roasted axolotl is considered a delicacy in Mexico, further shrinking their numbers. They are considered a critically endangered species.

Green-Eyed Tree Frog

2010-12-16T10:58:00.000-08:00

Green-eyed tree frogs get their name for the line of brilliant green that often adorns their eyebrows.

The green-eyed tree frog has adapted its appearance to blend in with the moss-covered rain forests of Queensland, Australia. The frogs' coloration and markings vary with their specific habitat, but they usually have a brownish-green body with rust-colored blotches that match the lichen-covered rocks lining the creeks and streams they tend to live near.

This species gets its name not for green eyes per se, but rather for a line of brilliant green that often adorns the brow of each eye. They are also distinguishable by a row of skin flaps along their arms and legs, which resembles a serrated knife.

Females, which are significantly larger than males, grow to about 2.8 inches (7 centimeters). Males, which emit a mating call that sounds like a quiet tap-tap-tap, max out at about 1.8 inches (5 centimeters).

Green-eyed tree frogs are abundant in the rugged wet tropics of northeast Queensland, near the Great Barrier Reef. Their population is healthy in the region's lower elevations, but, for unknown reasons, may have disappeared completely from the higher-altitude areas. They have suffered serious declines in the past, possibly due to a fungus or virus, but their numbers have rebounded, and they are not currently threatened or endangered.

Heart

2010-12-16T10:49:00.000-08:00

The heart is the body's engine room, responsible for pumping life-sustaining blood via a 60,000-mile-long (97,000-kilometer-long) network of vessels. The organ works ceaselessly, beating 100,000 times a day, 40 million times a year—in total clocking up three billion heartbeats over an average lifetime. It keeps the body freshly supplied with oxygen and nutrients, while clearing away harmful waste matter.

The fetal heart evolves through several different stages inside the womb, first resembling a fish's heart, then a frog's, which has two chambers, then a snake's, with three, before finally adopting the four-chambered structure of the human heart.

About the size of its owner's clenched fist, the organ sits in the middle of the chest, behind the breastbone and between the lungs, in a moistened chamber that is protected all round by the rib cage. It's made up of a special kind of muscle (cardiac muscle) that works involuntarily, so we don't have to think about it. The heart speeds up or slow downs automatically in response to nerve signals from the brain that tell it how much the body is being exerted. Normally the heart contracts and relaxes between 70 and 80 times per minute, each heartbeat filling the four chambers inside with a fresh round of blood.

These cavities form two separate pumps on each side of the heart, which are divided by a wall of muscle called the septum. The upper chamber on each side is called the atrium. This is connected via a sealing valve to the larger, more powerful lower chamber, or ventricle. The left ventricle pumps most forcefully, which is why a person's heartbeat is felt more on the left side of the chest.

When the heart contracts, the chambers become smaller, forcing blood first out of the atria into the ventricles, then from each ventricle into a large blood vessel connected to the top of the heart. These vessels are the two main arteries. One of them, the pulmonary artery, takes blood to the lungs to receive oxygen. The other, the aorta, transports freshly oxygenated blood to the rest of the body. The vessels that bring blood to the heart are the veins. The two main veins that connect to the heart are called the vena cava.

Blood Delivery

Since the heart lies at the center of the blood delivery system, it is also central to life. Blood both supplies oxygen from the lungs to the other organs and tissues and removes carbon dioxide to the lungs, where the gas is breathed out. Blood also distributes nourishment from the digestive system and hormones from glands. Likewise our immune system cells travel in the bloodstream, seeking out infection, and blood takes the body's waste products to the kidneys and liver to be sorted out and trashed.

Given the heart's many essential functions, it seems wise to take care of it. Yetheart disease has risen steadily over the last century, especially in industrialized countries, due largely to changes in diet and lifestyle. It has become the leading cause of death for both men and women in the United States, claiming almost 700,000 lives a year, or 29 percent of the annual total. Worldwide, 7.2 million people die from heart disease every year.

African Lion Cub

2010-12-14T06:27:00.000-08:00

African Lion Cub

Photograph by Beverly Joubert

An African lion cub rests in the tall grasses of Botswana’s Okavango Delta. Once ranging across the African continent and into Syria, Israel, Iraq, Pakistan, Iran, and even northwest India, lions have declined to as few as 20,000 animals from about 450,000 just 50 years ago.

Paper Chromatography of Ink

2010-12-13T11:11:00.000-08:00

Paper Chromatography of Ink. Chromatography is an analytical process, which separates a compound into its constituent chemicals. Chromatography paper is dipped vertically in a solvent with the ink painted on it (left). Capillary action draws the solvent up through the paper (center) and dissolves the ink. As the solvent travels up the paper it takes the various chemicals in the ink with it, separating them into a series of colored bands.

Rhinolophus Blasii

2010-12-13T09:46:00.000-08:00

Rhinolophus Blasii

Photograph by Michael Curran and Mirjam Kopp

This is a Rhinolophus blasii from Mount Mabu in northern Mozambique. We spent 13 nights sampling in a remarkably intact montane rain forest. Although capture success was low, we recorded a very diverse yet even community of bats in this forest. In areas of West Africa, a similar pattern was observed in intact wild habitat: low levels of abundance but a highly diverse community.

About the Project

NGS/Waitt grantee Michael Curran and his team are documenting how Mozambique and Malawi forests are essential to their local, large bat communities. Using mist nets, canopy nets, harp traps and acoustic monitoring (recording ultrasonic bat calls using a bat detector), Curran has discovered that these forests support a very large proportion of the region’s bat diversity within a very small geographic area. Visiting eight sites across three mountains in Mozambique and Malawi, he and his team captured 245 bats representing about 27 species.

What Is Global Warming? The Planet Is Heating Up—and Fast

2010-12-13T08:50:00.000-08:00

What Is Global Warming?

The Planet Is Heating Up—and Fast

Photograph by Paul Nicklen

Glaciers are melting, sea levels are rising, cloud forests are drying, and wildlife is scrambling to keep pace. It's becoming clear that humans have caused most of the past century's warming by releasing heat-trapping gases as we power our modern lives. Called greenhouse gases, their levels are higher now than in the last 650,000 years.

We call the result global warming, but it is causing a set of changes to the Earth's climate, or long-term weather patterns, that varies from place to place. As the Earth spins each day, the new heat swirls with it, picking up moisture over the oceans, rising here, settling there. It's changing the rhythms of climate that all living things have come to rely upon.

What will we do to slow this warming? How will we cope with the changes we've already set into motion? While we struggle to figure it all out, the face of the Earth as we know it—coasts, forests, farms and snow-capped mountains—hangs in the balance.

Greenhouse effect

The "greenhouse effect" is the warming that happens when certain gases in Earth's atmosphere trap heat. These gases let in light but keep heat from escaping, like the glass walls of a greenhouse.

First, sunlight shines onto the Earth's surface, where it is absorbed and then radiates back into the atmosphere as heat. In the atmosphere, “greenhouse” gases trap some of this heat, and the rest escapes into space. The more greenhouse gases are in the atmosphere, the more heat gets trapped.

Scientists have known about the greenhouse effect since 1824, when Joseph Fourier calculated that the Earth would be much colder if it had no atmosphere. This greenhouse effect is what keeps the Earth's climate livable. Without it, the Earth's surface would be an average of about 60 degrees Fahrenheit cooler. In 1895, the Swedish chemist Svante Arrhenius discovered that humans could enhance the greenhouse effect by making carbon dioxide, a greenhouse gas. He kicked off 100 years of climate research that has given us a sophisticated understanding of global warming.

Levels of greenhouse gases (GHGs) have gone up and down over the Earth's history, but they have been fairly constant for the past few thousand years. Global average temperatures have stayed fairly constant over that time as well, until recently. Through the burning of fossil fuels and other GHG emissions, humans are enhancing the greenhouse effect and warming Earth.

Scientists often use the term "climate change" instead of global warming. This is because as the Earth's average temperature climbs, winds and ocean currents move heat around the globe in ways that can cool some areas, warm others, and change the amount of rain and snow falling. As a result, the climate changes differently in different areas.

Aren't temperature changes natural?

The average global temperature and concentrations of carbon dioxide (one of the major greenhouse gases) have fluctuated on a cycle of hundreds of thousands of years as the Earth's position relative to the sun has varied. As a result, ice ages have come and gone.

However, for thousands of years now, emissions of GHGs to the atmosphere have been balanced out by GHGs that are naturally absorbed. As a result, GHG concentrations and temperature have been fairly stable. This stability has allowed human civilization to develop within a consistent climate.

Occasionally, other factors briefly influence global temperatures. Volcanic eruptions, for example, emit particles that temporarily cool the Earth's surface. But these have no lasting effect beyond a few years. Other cycles, such as El Niño, also work on fairly short and predictable cycles.

Now, humans have increased the amount of carbon dioxide in the atmosphere by more than a third since the industrial revolution. Changes this large have historically taken thousands of years, but are now happening over the course of decades.

Why is this a concern?

The rapid rise in greenhouse gases is a problem because it is changing the climate faster than some living things may be able to adapt. Also, a new and more unpredictable climate poses unique challenges to all life.

Historically, Earth's climate has regularly shifted back and forth between temperatures like those we see today and temperatures cold enough that large sheets of ice covered much of North America and Europe. The difference between average global temperatures today and during those ice ages is only about 5 degrees Celsius (9 degrees Fahrenheit), and these swings happen slowly, over hundreds of thousands of years.

Now, with concentrations of greenhouse gases rising, Earth's remaining ice sheets (such as Greenland and Antarctica) are starting to melt too. The extra water could potentially raise sea levels significantly.

As the mercury rises, the climate can change in unexpected ways. In addition to sea levels rising, weather can become more extreme. This means more intense major storms, more rain followed by longer and drier droughts (a challenge for growing crops), changes in the ranges in which plants and animals can live, and loss of water supplies that have historically come from glaciers.

Scientists are already seeing some of these changes occurring more quickly than they had expected. According to the Intergovernmental Panel on Climate Change, eleven of the twelve hottest years since thermometer readings became available occurred between 1995 and 2006.

Iceberg Penguins

2010-12-13T01:36:00.000-08:00

A group of chinstrap penguins lines the edge of an iceberg adrift in Antarctic waters. Chinstraps are among the most abundant penguins, and some colonies live on floating icebergs.

Orangutan (Pongo pygmaeus) | Biology Blog

2010-12-12T09:34:00.000-08:00

This article is about the primate. For other uses, see Orangutan (disambiguation).

Orangutans^[1]

Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Mammalia
Order:	Primates
Family:	Hominidae
Subfamily:	Ponginae
Genus:	Pongo Lacépède, 1799
Type species
Pongo borneo Lacépède, 1799 (= Simia pygmaeusLinnaeus, 1760)
Species
Pongo pygmaeus Pongo abelii

Orangutan distribution

Orangutans are the only exclusively Asian living genus of great ape. They are among the most intelligent primates and use a variety of sophisticated tools, also making sleeping nests each night from branches and foliage. They are generally not aggressive and live a mostly solitary life foraging for food. They are the largest living arboreal animals with longer arms than other great apes. Their hair is typically reddish-brown, instead of the brown or black hair typical of other great apes.

Native to Indonesia and Malaysia, orangutans are currently found only in rainforests on the islands of Borneo and Sumatra, though fossils have been found in Java, the Thai-Malay Peninsula, Vietnamand China. There are only two surviving species, both of which are endangered: the Bornean Orangutan (Pongo pygmaeus) and the critically endangered Sumatran Orangutan (Pongo abelii). The subfamily Ponginae also includes the extinct genera Gigantopithecus and Sivapithecus. The word "orangutan" comes from the Malay words "orang" (man) and "(h)utan" (forest); hence, "man of the forest".