Category Archives: Life Science

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.”

Gene Carnival

From Scienceroll’s carnival post – Gene Genie #19: Geneticalization

Matt Mealiffe at DNA and You talks about several genes linked to eye color.

Larry Moran, our favourite professor and author of Sandwalk, has a post about diversity and the major histocompatibility (MHC) loci.

PZ Myers at Pharyngula says mutations in the CFTR gene cause Cystic Fibrosis.

T. Ryan Gregory at Genomicron asks a strange question: Are you a cat genome person or a dog genome person?

Cool Crow Research

photo of crow vending machine

Very cool project – A Vending Machine for Crows

The goal of this project is to create a device that will autonomously train crows. Initially we’re training them to deposit dropped coins they find on the ground in exchange for peanuts, but eventually we hope to be able to train them to search and rescue, or to collect garbage, or who knows!
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This is the highest-risk segment of the machine’s operation. At this point coins alone are made available whenever the bird lands on the perch. However, should a bird peck or sweep coins off the tray and cause a coin to fall down the funnel, the device then produces some peanuts. This stage is designed to cement in the crows’ mind the relationship between coins going down the funnel and peanuts being made available.
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Finally we shift the device into its intended, and long-term state of only providing peanuts when coins go down the funnel. Nothing is otherwise provided aside from coins scattered around the device at the beginning of the project.

Joshua Klein Thesis presentation definitely watch this! (the webcast takes like 30 seconds before the talk starts – it is worth the wait). Watch a video from the University of Ithaca site (with Dr. Kevin McGowan).

Other sites that also are mentioned as possible sites: Dr. Anne Clark, University of Binghamton (with a captive population of crows); Dr. Natalie Jeremijenko (seed podcast), Dr. Carolee Caffrey, Harvard and Dr. James Ha, University of Washington. Read the Paper by Joshua Klein about the plans for the experiment.

Disrupting Bacteria Communication

Princeton scientists break cholera’s lines of communication

A team of Princeton scientists has discovered a key mechanism in how bacteria communicate with each other, a pivotal breakthrough that could lead to treatments for cholera and other bacterial diseases.

The mechanism is a chemical that cholera bacteria use for transmitting messages to each other, known as CAI-1, and has been isolated in the lab of molecular biologist Bonnie Bassler. Her team has shown that the chemical also can be used to disrupt the communication that exists among the bacteria, potentially halting the disease’s progress. The discovery could lead to an entirely new class of antibiotics.
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Higgins isolated the CAI-1 chemical, which occurs naturally in cholera. Then, Megan Pomianek, a graduate student in the laboratory of Martin Semmelhack, a professor of chemistry at Princeton, determined how to make the molecule in the laboratory. Higgins used this chemical essentially to control cholera’s behavior in lab tests.

The team found that when CAI-1 is absent, cholera bacteria act as pathogens. But when the bacteria detect enough of this chemical, they stop making biofilms and releasing toxins, perceiving that it is time to leave the body instead. “Our findings demonstrate that if you supply CAI-1 to cholera, you can flip their switches to stop the attack,” Higgins said.

Chemist Helen Blackwell of the University of Wisconsin-Madison praised the study, calling it a breakthrough for quorum sensing research, and possibly for medical science.

The Brain is Wired to Mull Over Decisions

New studies have identified a specific neural circuit in the brains of monkeys that is activated when they postpone acting on a decision. The circuit is thought to keep potential choices brewing in memory even after a decision has already been made.

The brain may continue to consider the options even after a decision is made because that extra consideration may sometimes result in a change of mind – and a possible reward, such as a tastier meal. The researchers said that their findings could offer important insight into the function of neural circuits that drive the brain’s memory and decision-making machinery.
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the researchers conducted experiments in which they required the monkeys to delay their decision. At the same time, the researchers recorded the electrical activity of neurons in a region called the medial premotor cortex—one of the brain regions involved in decision-making and motor choice.

“To our surprise, when the monkeys held the decision for several seconds, what we saw in the activity of these brain cells in the medial premotor cortex is that they were still remembering the sensory information on which the decision was based,” said Romo. “During that time the neurons were recalling the first stimulus, recalling the second, comparing the second against the first, and even reporting in their activity the categorical decision.”

Remove the Identical Stretches of DNA Found in Mice, Rats, and Humans and What Happens?

A Real Genetic Headscratcher by Derek Lowe:

As you root through genomic sequences – and there are more and more of them to root through these days – you come across some stretches of DNA that hardly seem to vary at all. The hard-core “ultraconserved” parts, first identified in 2004, are absolutely identical between mice, rats, and humans.
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Even important enzyme sequences vary a bit among the three species, so what could these pristine stretches (some of which are hundreds of base pairs long) be used for? The assumption, naturally, has been that whatever it is, it must be mighty important, but if we’re going to be scientists, we can’t just go around assuming that what we think must be right. A team at Lawrence Berkeley and the DOE put things to the test recently by identifying four of the ultraconserved elements that all seem to be located next to critical genes – and deleting them.

The knockout mice turned out to do something very surprising indeed. They were born normally, but then they grew up normally. When they reached adulthood, though, they were completely normal. Exhaustive biochemical and behavioral tests finally uncovered the truth: they’re basically indistinguishable from the wild type. Hey, I told you it was surprising. This must have been the last thing that the researchers expected.

What a great example of scientists at work. It will be interesting to see where this goes.

MRSA Blows Up Defender Cells

Superbug succeeds by blowing up defender cells, scientists learn

While only 14 percent of serious MRSA infections are the community associated kind, they have drawn attention in recent months with a spate of reports in schools, including the death of a 17-year-old Virginia high school student. Both hospital-associated and community-associated MRSA contained genes for the peptides. But their production was much higher in the CA-MRSA, the researchers said.
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The compounds first cause inflammation, drawing the immune cells to the site of the infection, and then destroy those cells. The research was conducted in mice and with human blood in laboratory tests. Within five minutes of exposure to the peptides from CA-MRSA, human neutrophils showed flattening and signs of damage to their membrane, researchers said. After 60 minutes, many cells had disintegrated completely.

“This elegant work helps reveal the complex strategy that S. aureus has developed to evade our normal immune defenses,” Dr. Anthony S. Fauci, NIAID director, said in a statement. “Understanding what makes the infections caused by these new strains so severe and developing new drugs to treat them are urgent public health priorities.”

Fish Discovery: Breathes Air for Months at a Time

Fish Lives in Logs, Breathing Air, for Months at a Time:

A tiny Western Atlantic fish does something never before seen: It makes like a bird, living in mangrove wood for months at a time. A team of U.S. and English scientists accidentally discovered the unique behavior, which they call “logpacking,” during recent excursions to Belize and Florida. They were studying how the mangrove rivulus—an animal already infamous for its bizarre sexual behavior—survived the frequent dry spells that strike its swampy forest habitat.

“One of us kicked at a log, which broke apart and out came the fish!” said team leader Scott Taylor of Brevard County, Florida’s Environmentally Endangered Lands Program. The mangrove rivulus, also known as the mangrove killifish, is native to the Americas and is about two inches (five centimeters) long. The fish has long been studied for its many unique features.

It’s the only vertebrate known to naturally self-fertilize, for example. In some populations, it can become a hermaphrodite, developing both male and female parts simultaneously, to produce clones of itself. The animal can also live out of water for up to 66 days, Taylor said, and is one of very few fish species that spend their entire lives in mangrove swamps. Most fish move in and out of the areas as water sources dwindle.

New and Old Ways to Make Flu Vaccines

New and Old Ways to Make Flu Vaccines by Nell Greenfieldboyce, NPR:

Standard Practice
Pros: Millions of Americans receive this [standard] vaccine every year. It’s safe and well tolerated. Its production begins in hens’ eggs — a tried and true technology for 50 years.
Cons: Eggs must be ordered many months in advance, and millions of doses require millions of eggs.

Live-Attenuated Vaccine
Pros: This newer method of production results in a vaccine that has a flu virus that is crippled, so it can’t cause disease. But the virus is not killed, as is the case in the standard vaccine. The vaccine also can be given as a nasal spray.
Cons: More expensive than standard vaccine, and also produced in eggs. Not approved for young children or older people.

Cell-Based Vaccine
Pros: This vaccine can be produced in giant vats of living cells. Such a production method means it can be scaled up much faster than egg-based vaccines, making it more useful in a pandemic. Several versions have been tested successfully in people.
Cons: Won’t be widely available for a few years. Clinical trials are under way, but no flu vaccine made this way is currently approved by the Food and Drug Administration.

Cat Joins Exclusive Genome Club

Cat joins exclusive genome club

The domestic cat now joins the select club of mammals whose genome has been deciphered – including dogs, chimps, rats, mice, cows and people. The genome map is expected to shed light on both feline and human disease. Cats get hundreds of illnesses similar to human ones, including a feline version of HIV, known as FIV, and a hereditary form of blindness.
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Cats are among the 26 mammals chosen by the National Human Genome Research Institute in the US for less complete or “light” genome sequencing. Scientists use the so-called “shot-gun” sequencing method, where DNA is extracted, chopped into pieces, sequenced, and then pieced back together again.

It has yielded a rough version of the cat genome, including around 60% of Cinnamon’s DNA “letters” with many gaps in between. A more complete version, expected next year, will be used to make more detailed comparisons with other animals.