Can’t Resist One Last Post

Optical Illusions and Visual Phenomena

COOL STUFF!!

Halliburton Overcharges by 1.4 Billion Dollars

According to this article Halliburton has overcharged the troops by 1.4 billion dollars. Yet Karl Rove thinks liberals do not support the troops!

The breakdown:

According to the report, released Monday by Democrats Sen. Byron Dorgan, N.D., and Rep. Henry Waxman, Calif., the audits show Halliburton subsidiary KBR racked up $813 million in questioned costs on an $8.6 billion logistics contract providing food and shelter and other support services to troops; $219 million in questioned costs on an Iraqi oil contract, and a total of $442 million in unsupported costs on the two contracts.

Questionable costs, as defined by Defense Department auditors, are those that would seem unreasonable to the average person. Unsupported costs are those the company can not provide documentation for.

Note, Halliburton can’t provide documentation on 442 million of it yet Durbin had to apologize for being unpatriotic. Sounds like a massive inversion of american moral values to me.

Deep Ocean Photosynthesis in Bacteria

This is cool.

Most bacteria use photosynthesis, powered by sunlight to create sugars for fuel. Recently, a species of bactera was discovered that uses light given off by hydrothermic vents to power the photsynthetic reaction.


From the article:

The bacteria have a sophisticated antenna system that allows them to collect the low light emanating from hydrothermal vents, the researchers explain in a report published online this week by the Proceedings of the National Academy of Sciences. This light energy is then transferred to the organism’s reaction center, where photosynthesis takes place. “This shows that photosynthesis is something that is not limited only to the very surface of our planet,” Blankenship says. “It lets you consider other places where you might find photosynthesis on Earth as well as on other planets.”

Transitions

I’m having trouble going to Transitions. Can’t get to Blogsome either. Anybody else having trouble?

A Post on Crocodile Evolution at Transitions

I have published a post on Crocodile evolution over at Transitions. Check it out. Also, if you wish to get in touch with me about Transitions related stuff you can email me at transistions@sbcglobal.net

Yes, I know its spelled with an extra “s” “transitions” was taken.

Mammary Glands and Solenodon

One of the more interesting aspects of Solenodons is the location of their teats, which are located near the buttocks.
Generally, mammary glands are located in several regions. They can be located anteriorly (as in primates, elephants, sea cows and bats), posteriorly (as in horses, cows, sheep, and whales) or serially (as in litter bearing species such as dogs and cats). Anterior mammary glands are located in the thoracic region, whereas posterior mammary glands are located in the inguinal region.
In addition to supplying young Solenodon with nourishment, the teats provide a secondary function. Namely, they aid in the transport of solenodon young. From an interesting article on Solenodons:

We observed a unique mode of maternal-young contact which we have referred to as ‘teat transport’. This phenomenon is well known among some rodents (2), but unreported in insectivores. At seven weeks of age the youngster will accompany its mother on her foraging activities by clinging to one of the two inguinal teats. At this time the teats are very elongated, up to 2 cm in length, enabling the youngster to cling to a teat as it is dragged along close behind. As the infant grows it is able to assert its own locomotion and simply seize the teat and follow, moving when the mother moves, stopping when she stops. The 21/2 month old infant may still show this response and even scratch itself while standing behind the mother holding on to a teat. It would seem that if the solenodon has to change burrows from time to time, then such a teat-transport mechanism enables the female to move with still very dependent young, pulling them along behind her on her teats, rather than attempting to carry them in her mouth. Mouth transport, of course, is a wide-spread phenomenon in small insectivores; however, the solenodon’s teat-transport mechanism is probably quite efficient since the young remain dependent for a long time. During this dependency period, the female can forage and be accompanied by the young.

This is similar to the function of inguinal teats in marsupials – the one difference being that in marsupials the teats used for transport do not produce milk. I could find no information on the actual anatomy of the Solenodon mammary gland so I can’t compare it to, say, marsupials, cows, sheep, or humans. Although, since Solenodon are pretty ancient (as a species – dating back to the time of the dinosaurs) I would expect there to be some similarities with marsupials.
I also wonder if the teat transport might not explain why there are so few venomous mammals – most mammals transport their young by carrying them with their teeth. I have no data on the subject so this is pure speculation. One of the reasons Solenodon was free to evolve venom is that they used teat transport to move their young and wouldn’t run the risk of accidentally poisoning their young (incidentally, nursing is one way mammals build up immunity so a possible test of this might be to examine young Solenodon’s immunity to their own poison). Other mammals, then would have been precluded from developing venom because an alternative transport mechanism was not available for co-option. If I understand Gould correctly, this would be a case of exaption.

An interesting link Comparative Mammary Gland Anatomy

Playing with DSL

Just got DSL so I’m playing around. Uploaded this picture of a crocodile fossil that I am going to use for a post at Transistions. Way quicker than dile up!

Croc fossil Posted by Hello

Welcome Pharyngulans and Panda’s Thumbites

Welcome,
Feel free to look around. But please read this, this and this.

Friday Solenodon Blogging

This falls under the category of “So ugly it’s cute”.

Solenodon Posted by Hello

Or maybe just “Soooo ugly”!

Solenodon 2 Posted by Hello

Solenodon are related to the insectivores and can be found in Hispaniola and Cuba. The Solenodons are small, nocturnal omnivores. They eat insects, grubs, small reptiles, fruit and other plant matter. They may produce two litters a year. How are the young fed? The female’s two teats are placed on the edge of the buttocks near the tail.

Warning: Gratuitous Spider Sex Link
Now if I were PZ Myers that would be reason enough to talk about them. Maybe even try to find a picture of it and talk about the developmental genetics of it all. But I’m not.

So instead I’m going to talk about venomous mammals. Solendons are one of a few venomous mammals. The others being the duckbilled platypus and several species of shrew (including the North American Short Tailed Shrew) The saliva of a solenodon is venomous and is injected via narrow grooves on it’s second lower incisor.

solenodon jaw Posted by Hello

Recent genetic research indicates that the solenodon lineage split off from that leading to moles, shrews and hedgehogs approximately 76 million years ago – somehow surving the event that caused the extinction of the dinosaurs.

Curiously enough, a fossil has recently been found dating to about 60 million years ago.

Bisonalveus browni Posted by Hello

The fossils consisted of several mandibular fragments and a cranial fragment. Previous finds of this particular creature contained molars only but the new find also had canines – which contained grooves similar to the solenodon incisor (an interesting difference). The fossils have been named Bisonalveus browni and belong to a small shrew like mammal. Researchers have several hypothesis to explain the teeth:

“The likelihood that the saliva was toxic and was required to subdue active prey is high,” he said. “But one must also consider that if the animal was a highly active forager … introduction of saliva for digestive reasons could also be important.”

Did other mammals of the time have venom:

“The discovery that B. browni and, in all likelihood, a few other extinct mammals used venom to secure prey suggests that venomous mammals were more widespread in the past.
As the fossil record of mammals from B. browni’s era improves … even more venomous mammals will be discovered.”

Why don’t modern mammals have venom:

“… venom may be scarce among mammals today because predatory mammals use surprise, speed, and strength so efficiently in their attacks, and can inflict lethal damage with teeth and claws”.
“The kill can be immediate … whereas a venom, however sophisticated, takes time.”

Added later: PZ Myers has a great post on Bisonalveus browni, including better pictures of the teeth.

It will be interesting to see how these issues are answered.

Microtubule Formation is Not Irreducibly Complex

From Science Daily comes The Making and Breaking of Microtubules .

From the article:

Microtubules are active protein polymers critical to the structure and function of cells and the process of cell division. In a living cell their growing ends constantly elongate and retreat in a thrashing frenzy of polymerization and depolymerization, like the writhing snakes of Medusa’s hair. Known prosaically as “dynamic instability,” this ongoing rapid growth and shrinkage is key to the diverse workings of microtubules in the cell.

Apparently, one of the key molecules driving microtubule formation is guanosine triphospate (GTP).

Microtubules are polymers whose basic units are pairs (dimers) of similar but not identical tubulin proteins, dubbed the alpha and beta forms. During polymerization the dimers stack end to end to make a protofilament. About thirteen protofilaments are arranged side by side, extending longitudinally, to form the walls of a cylindrical microtubule.

The so-called minus end of the microtubule grows slowly and is often anchored to a cellular structure. The other end, the plus end, is a hotbed of activity. In the presence of GTP the microtubule’s protofilaments acquire more tubulin dimers, and the whole microtubule extends rapidly for many millionths of a meter before suddenly switching off and shrinking again.

Essentially, GTP causes microtubules to straighten out so the polymerization can proceed. The GTP molecule can undergo hydrolysis, to form GDP. GDP causes the microtubule to bend or curl preventing further polymerization:

…the contacts between the alpha and beta tubulins within and between dimers are both affected, although in significantly different ways, resulting in a curved protofilament that cannot form lateral contacts.

So microtubule formation is driven or stopped by a simple hydrolysis reaction – hardly the stuff irreducible complexity is made of. To add insult to injury the implications of this research for Well’s centriole turbine conflation arn’t good.