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Tuesday, 23 December 2008

Creatures special, 2008

Today:

  1. Superglue from the sea: Synthetic sea worm glue may mend shattered knee, face bones
  2. Solar-powered sea slug harnesses stolen plant genes
  3. Experimental TB drug explodes bacteria from the inside out
  4. Scientists put sex origin mystery to bed
  5. Tiny sacs released by brain tumor cells carry information that may guide treatment
A rather lazy one. Because I'm in lazy mood. And I don't see that much enthusiasm on my posts anyway. In any case, the first 3 articles are the most interesting, because they offer new opportunities and well, perspectives. I mean a slug stealing genes of its food is quite fun, right?

Superglue from the sea: Synthetic sea worm glue may mend shattered knee, face bones

Sandcastle worms live in intertidal surf, building sturdy tube-shaped homes from bits of sand and shell and their own natural glue. University of Utah bioengineers have made a synthetic version of this seaworthy superglue, and hope it will be used within several years to repair shattered bones in knees, other joints and the face.In lab tests using cow bone pieces from groceries, the synthetic sea-worm glue – a first-generation prototype – performed 37 percent as well as commercial superglue.

Stewart expects the synthetic worm glue will be tested on animals within a year or two, and will be tested and used on humans in five to 10 years.

The synthetic sandcastle worm glue would not be used to repair large fractures such as major leg and arm bones, for which rods, pins and screws now are used, but for small fractures and facesl.

The synthetic glue also can carry drugs, so it could be used to deliver pain killers, growth factors, antibiotics, anti-inflammatory medicines or even stem cells to sites where bone fragments are glued, "simultaneously fixing the bone and delivering potent drugs or even genes to the spots where they are needed," Stewart says.

Stewart is seeking to patent the synthetic sea worm glue so it can be licensed to an outside company that would develop it as a product. He hopes to make better versions that have more bonding power, are biocompatible in the human body and biodegradable.

The study involved Phragmatopoma californica, the sandcastle worm, which lives in vaguely sandcastle-like colonies of tube-shaped homes on the California coast.

The adult worm is an inch or so long, and an eighth-inch in diameter. But they build tubes several inches long, using sand grains and shell fragments.

The sea worm's glue is made from two proteins – one acidic or negatively charged, the other basic or positively charged – that are natural polymers, or compounds with a repeating, chain-like structure. The glue also contains positively charged ions of calcium and magnesium.

In the natural worm glue, each protein polymer's "backbone" is made of polyamide, which has "side chains" of other chemicals attached to the backbone. source

My comment: Sounds very cool. Though, I think that scientist is somewhat over-excited. The new glue is obviously very good, but between this and usable there is a difference. And time. And money. But imagine if it can be used to fix broken bones instead of waiting for months to heal.

Solar-powered sea slug harnesses stolen plant genes

  • 17:24 24 November 2008

Elysia chlorotica is a lurid green sea slug, with a gelatinous leaf-shaped body, that lives along the Atlantic seaboard of the US. What sets it apart from most other sea slugs is its ability to run on solar power.

Mary Rumpho of the University of Maine, is an expert on E. chlorotica and has now discovered how the sea slug gets this ability: it photosynthesises with genes "stolen" from the algae it eats.

She has known for some time that E. chlorotica acquires chloroplasts - the green cellular objects that allow plant cells to convert sunlight into energy - from the algae it eats, and stores them in the cells that line its gut.

Young E. chlorotica fed with algae for two weeks, could survive for the rest of their year-long lives without eating, Rumpho found in earlier work.

But chloroplasts only contain enough DNA to encode about 10% of the proteins needed to keep themselves running. The other necessary genes are found in the algae's nuclear DNA.

In their latest experiments, Rumpho and colleagues sequenced the chloroplast genes of Vaucheria litorea, the alga that is the sea slug's favourite snack. They confirmed that if the sea slug used the algal chloroplasts alone, it would not have all the genes needed to photosynthesise.

They then turned their attention to the sea slug's own DNA and found one of the vital algal genes was present.

One possibility is that, as the algae are processed in the sea slug's gut, the gene is taken into its cells as along with the chloroplasts. The genes are then incorporated into the sea slug's own DNA, allowing the animal to produce the necessary proteins for the stolen chloroplasts to continue working.

Another explanation is that a virus found in the sea slug carries the DNA from the algal cells to the sea slug's cells. However, Rumpho says her team does not have any evidence for this yet.

In another surprising development, the researchers found the algal gene in E. chlorotica's sex cells, meaning the ability to maintain functional chloroplasts could be passed to the next generation.

Greg Hurst of Liverpool University in the UK says that DNA jumping from one species to another is not unheard of but that normally the DNA does not appear to function in the new species.

It is unlikely humans could become photosynthetic in this way. "Our digestive tract just chews all that stuff up - the chloroplasts and the DNA," she adds. source

My comment: Ok, first, I find it odd that the algae DNA is found in the slug sex cells, because if it could transfer the ability to photosynthesise then it wouldn't need to eat the algae to survive and it would just implement those genes as a part of the specie. In any case, it's very interesting research. You can't but wonder if we really cannot use vegetables in the same manner. Yeah, they say we just chew them, but I don't think someone traced the human digestion down to genes. And what's even more important, what if we get genes from our food, then, what do we do about GM food?

Experimental TB drug explodes bacteria from the inside out

An international team of biochemists has discovered how an experimental drug unleashes its destructive force inside the bacteria that cause tuberculosis (TB). The finding could help scientists develop ways to treat dormant TB infections, and suggests a strategy for drug development against other bacteria as well.

One-third of the world's population is infected with Mycobacterium tuberculosis (M. tb), the bacteria that cause TB and cannot healed in its latent state. Dr. Barry and his colleagues have now given a candidate TB drug PA-824.

Previously, Dr. Barry and his collaborators found that M. tb mutants lacking a specific bacterial enzyme were resistant to PA-824, but at that time, they did not know the function of the enzyme.

A key element of the research is how two bacterial components- an enzyme called Ddn and a cofactor- interact with PA-824 trough production of nitric oxide (NO) gas.

NO gas is produced naturally by certain immune system cells after they engulf M. tb or other bacteria. This is one way that people with healthy immune systems can contain M. tb infection. However, this natural immune response is not always enough to completely rid the body of TB bacteria. In essence, PA-824 performs similarly to the NO-producing immune cells--but the drug's effect is more specific and triggered only after it enters the bacteria.

The non-dividing M. tb bacteria characteristic of latent TB infections are walled off by immune cells that aggregate around the bacteria to form a body called a granuloma. Oxygen levels are low inside granulomas. In their latest research, the scientists observed that NO-generation during PA-824 metabolism is greatest when oxygen levels are low. This observation suggests how PA-824 may work against non-dividing M. tb.

PA-824 was originally designed to work best under aerobic, or oxygenated, conditions. With this new understanding of how the bacterial enzyme and cofactor act on PA-824 under low-oxygen conditions, Dr. Barry says, scientists can design drugs with a chemical structure similar to PA-824 but optimize them from the start to behave best under low-oxygen conditions.

Because humans have neither the bacterial cofactor nor any enzymes equivalent to Ddn, PA-824 has no effect on human cells. Conversely, many bacteria have enzymes in the same family as Ddn. Thus, says Dr. Barry, it is possible to envision new kinds of NO-generating drugs designed to interact with enzymes associated with other disease-causing bacteria as well.source

My comment: Nice. Especially if this mechanism can be used to fight other bacteria too. If you think about it, we're so incapable to fight with bacteria. People die from bacterial infections much more than anything else (yeah, probably after the heart and blood diseases, but they are common only for the rich part of the world). Bacteria get more and more adapted to our antibiotics and thus harder and harder to kill. It's very probable that soon we'll face a major biological war, we against microbes. And we're very unfit to go into that war. This discovery may prove very useful in the fight.

Scientists put sex origin mystery to bed

By Jeanna Bryner,Nov. 26, 2008

We all came from hermaphrodites, organisms with both male and female reproductive organs. And though the origin traces back more than 100 million years, biologists have scratched their heads over how and why the separate male and female sexes evolved.

Now, research on wild strawberry plants is providing evidence for such a transition and the emergence of sex, at least in plants.

The study showed that two genes located at different spots on a chromosome can cast strawberry offspring as a single sex, a hermaphrodite or a neuter (neither male nor female, and essentially sterile). The researchers suspect the two genes could be responsible for one of the earliest stages of the transition from asexual to sexual beings.

The plants in the research each have two proto-sex chromosomes. Two spots on each proto-sex chromosome contain sex-determining genes, one that controls sterility and fertility in males and another that does the same in females.

Offspring that inherit both fertility versions are hemaphrodites and can self-breed, while plants that inherit one fertility and one sterility version become either male or female. (A female would result from a sterile male and fertile female combination of genes.) Those that get both sterility versions of the genes are considered neuters and can't reproduce, so they ultimately die out.

While the two sex-determining genes are close to one another on the proto-sex chromosomes, the researchers say they are not completely linked. That's why the strawberry offspring can get such a wild mix of the genes.

On our sex chromosomes, for instance, this mixing and matching is not possible (or at least very rare), because the female chromosome is one unit and so is the male sex chromosome. source

My comment: Ok, I'm not quite sure what was the important thing here, but it sounds quite cool how the strawberries procreate.

Tiny sacs released by brain tumor cells carry information that may guide treatment

Microvesicles – tiny membrane-covered sacs – released from glioblastoma cells contain molecules that may provide data that can guide treatment of the deadly brain tumor. In their report in the December 2008 Nature Cell Biology, Massachusetts General Hospital (MGH) researchers describe finding tumor-associated RNA and proteins in membrane microvesicles called exosomes in blood samples from glioblastoma patients. Detailed analysis of exosome contents identified factors that could facilitate a tumor's growth through delivery of genetic information or proteins, or signify its vulnerability to particular medications.

Many types of cells release exosomes as part of normal cell-to-cell communication, and several types of tumors are known to shed exosomes containing proteins that can alter the cellular environment to favor tumor growth. The current investigation is believed to be the first to carefully analyze the contents of exosomes shed from glioblastoma cells and characterize their contents. source

My comment: Again, not much to comment. It's simply fascinating how complex the body is and how much more we should understand in order to make it heal.

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