Tag Archives: biology

Algorithmic Self-Assembly

Paul Rothemund, scientist at Cal Tech, provides a interesting look at DNA folding and DNA based algorithmic self-assembly. In the talk he shows the promise ahead for using biological building blocks using DNA origami — to create tiny machines that assemble themselves from a set of instructions.

Algorithmic Self-Assembly of DNA Sierpinski Triangles, PLoS paper.

I posted a few months ago about how you can participate in the protein folding, with the Protein Folding Game.

A Journey Into the Human Eye

Zoom into a human eye

The webcast goes into the human eye while describing the microscopic details of the human eye. See more such videos: The Eyes of a Fly – Zoom Into a Fish – Zoom Into a Butterfly

General Biology Berkeley Course Webcast

General Biology Course at University of California – Berkeley, Fall 2007. Instructors John Forte, R Fischer and R Malkin. “General introduction to cell structure and function, molecular and organism genetics, animal development, form and function. Intended for biological sciences majors, but open to all qualified students.” A great service from Berkeley with video and audio… Topics include: Macromolecules structure and function, How cells function-an introduction to cellular metabolism and biological catalysts, Microbes – Viruses, Bacteria, Plasmids, Transposons and Homeostasis: The body’s defenses.

World’s Smallest Snake Found in Barbados

photo of Leptotyphlops carlae

The world’s smallest species of snake, Leptotyphlops carlae, with adults averaging just under 4 inches in length, has been identified on the Caribbean island of Barbados. The species — which is as thin as a spaghetti noodle and small enough to rest comfortably on a U.S. quarter — was discovered by Blair Hedges, an evolutionary biologist at Penn State.

Hedges determined that the Barbados species is new to science on the basis of its genetic differences from other snake species and its unique color pattern and scales. He also determined that some old museum specimens that had been misidentified by other scientists actually belong to this new species.

Scientists use adults to compare sizes among animals because the sizes of adults do not vary as much as the sizes of juveniles and because juveniles can be harder to find. In addition, scientists seek to measure both males and females of a species to determine its average size. Using these methods, Hedges determined that this species, is the smallest of the more than 3,100 known snake species.

According to Hedges, the smallest and largest species of animals tend to be found on islands, where species can evolve over time to fill ecological niches in habitats that are unoccupied by other organisms. Those vacant niches exist because some types of organisms, by chance, never make it to the islands. For example, if a species of centipede is missing from an island, a snake might evolve into a very small species to “fill” the missing centipede’s ecological niche.

In contrast to larger species — some of which can lay up to 100 eggs in a single clutch — the smallest snakes, and the smallest of other types of animals, usually lay only one egg or give birth to one offspring. Furthermore, the smallest animals have young that are proportionately enormous relative to the adults. For example, the hatchlings of the smallest snakes are one-half the length of an adult, whereas the hatchlings of the largest snakes are only one-tenth the length of an adult. The Barbados snake is no exception to this pattern. It produces a single slender egg that occupies a significant portion of the mother’s body.

Nigersaurus

photo of the Nigersaurus Jaw Bones

Structural Extremes in a Cretaceous Dinosaur

Nigersaurus taqueti shows extreme adaptations for a dinosaurian herbivore including a skull of extremely light construction, tooth batteries located at the distal end of the jaws, tooth replacement as fast as one per month, an expanded muzzle that faces directly toward the ground, and hollow presacral vertebral centra with more air sac space than bone by volume. A cranial endocast provides the first reasonably complete view of a sauropod brain including its small olfactory bulbs and cerebrum. Skeletal and dental evidence suggests that Nigersaurus was a ground-level herbivore that gathered and sliced relatively soft vegetation, the culmination of a low-browsing feeding strategy first established among diplodocoids during the Jurassic.

This discovery has received a good deal of coverage. Among other things it is great to see this paper is available to everyone who wants to view it because it is published by open access PLoS One. The Nigersaurus was discovered in what is now the Sahara Desert in Niger. When the Nigersaurus was roaming the area, 110 million years ago, the climate was a Mesozoic forest. The dinosaur had a few hundred teeth that were replaced almost monthly (a record). The bones of the head and neck were so minimal and light that the Read more about the Nigersaurus. As the author stated: “One of the stunning things about this animal is how fragile the skull is… Some of the bones are so thin you can shine a light through them.”

Virus Found to be One Likely Factor in Bee Colony Collapse Disorder

Photo of a bee bu Justin Hunter

Scientists say a virus appears to be a factor in honeybee colony collapse by Andrew C. Revkin:

Scientists sifting genetic material from thriving and ailing bee colonies say a virus appears to be a prime suspect – but is unlikely to be the only culprit – in the mass die-offs of honeybees reported last autumn and winter.

Very well stated. The virus while seeming to be a factor in the deaths appears to cause death in colonies that are stressed which seem to be highly correlated with colonies that are moved from place to place by commercial beekeepers to pollinate various crops. Bees that are kept by hobbiest, wild bees… don’t seem to be dying off. The impact of CCD is growing economically as prices for renting bees to pollinate crops increases and in some cases there are not enough bees available. Honey prices are increasing and prices for food pollinated by bees are too.

The Department of Agriculture states: The only pathogen found in almost all samples from honey bee colonies with CCD, but not in non-CCD colonies, was the Israeli acute paralysis virus (IAPV), a dicistrovirus that can be transmitted by the varroa mite. It was found in 96.1 percent of the CCD-bee samples. This does not identify IAPV as the cause of CCD,” said Pettis. “What we have found is strictly a strong correlation of the appearance of IAPV and CCD together. We have not proven a cause-and-effect connection.”

Related: Bee researchers close in on Colony Collapse Disorder, Penn State (Penn State broke the link so it was removed) – Bye Bye Bees – Bee Colony Collapse Disorder CCD – More on Disappearing Honeybees – Colony Collapse Disorder and Pollinator Decline