A great edition full of particularly interesting articles, at least for me. I suggest your read them, because they are awesome. Especially the last two.
- Helpful Bacteria May Hide in Appendix
- Is a sniff of coffee as good as a sip?
- A video of carnivorous plant-nice!
- Genetically modified humans: Here and more coming soon /a cool cool article that I digged/
- 'Hairy blobs' in acid hell suggest new niche for life /the point-life can survive in very hard conditions, so why not on Mars or on Venus?/
Helpful Bacteria May Hide in Appendix
Everyone is born with one, but no one knows what it’s for. The human appendix is a small dead-end tube connected to the cecum, or ascending colon, one section of the large intestine. Everyone lives happily with it until it becomes painfully inflamed, when the only treatment is to remove it surgically.
Some experts have guessed that it is a vestige of the evolutionary development of some other organ, but there is little evidence for an appendix in our evolutionary ancestors. Few mammals have any appendix at all, and the appendices of those that do bears little resemblance to the human one.
Last December, researchers published a novel explanation in The Journal of Theoretical Biology. The appendix, they suggest, is a “safe house” for commensal bacteria, the symbiotic germs that aid digestion and help protect against disease-causing germs.
Structurally, the appendix is isolated from the rest of the gut, with an opening smaller than a pencil lead, protected from the fecal stream that might be carrying pathogens. In times of trouble like a diarrheal infection that flushes the system, these commensal bacteria could hide out there, ready to repopulate the gut when the coast is clear.
“But an experiment to prove this theory would be very expensive. And in any case, why would you want to spend money to find out something that is not likely to help cure a disease?”
Rebecca E. Fisher, an assistant professor of anatomy at the University of Arizona College of Medicine, said that although the appendix was “likely to be a derived feature, selected for a purpose, the enigma is that we didn’t know what that purpose might be.”
Recent studies have found that biofilms, colonies of beneficial microbes that live outside cells, form in the large intestine, where they are dependent on the mucus that lines the bowel. There, they aid digestion and protect against infection, while enjoying the protection and nutrition of the human host.
The researchers, examining tissue from uninfected human appendices removed in kidney-pancreas transplants, found biofilms on the epithelial lining of the appendix, as well. Under their theory, it is in these biofilms in the appendix, well positioned to avoid pathogens in the rest of the gut, that commensal bacteria take refuge.
If that is true, why is it that removing the appendix apparently does not have negative side effects? The scientists contend that in industrialized countries with modern medical care and sanitation, maintaining a reserve of helpful bacteria has become unnecessary. Widespread outbreaks of intestinal disease are so rare that the commensal bacteria face little danger of extermination.Whether the human appendix has the function Dr. Parker thinks it has or whether it has no function at all, it is clear, he said, that “if your appendix gets inflamed, forget about the fact that it might have some function.”
My comment: Cool. I had some troubles with my appendix recently, though it didn't have to be removed, so I kind of wondered how is it possible that we cannot control something so small and obvious. Not that this article reveal something but at least it is a start.
Is a sniff of coffee as good as a sip?
- 13 June 2008
A team led by Yoshinori Masuo at the National Institute of Advanced Industrial Science and Technology in Tsukuba, Japan, deprived rats of sleep for a day. When they examined their brains they found reduced levels of mRNA - messenger molecules that indicate when a gene is being expressed - for 11 genes important to brain function. When the rats were exposed to the aroma of coffee, the mRNA for nine of the genes was restored to near normal levels, and pushed to above normal levels for two - GIR, involved in neuro-endocrine control, and NFGR, thought to control oxidative stress (Journal of Agricultural and Food Chemistry, DOI: 10.1021/jf8001137).
We don't know if the same genes are suppressed in sleep-deprived humans, nor whether we would feel tired if they were, but many of these genes do have human equivalents. So the team says gene suppression may help explain why people feel bad when they haven't had enough sleep - and that gene reactivation could explain why people love the smell of coffee. source
My comment: I don't drink coffee but this sounds fun. And sniffing coffee is way easier than drinking it!
A pitcher-plant-a cool video of carnivorous plant and the article in NewScientist here.
Genetically modified humans: Here and more coming soon
- 04 June 2008
- Magazine issue 2659
CHILDREN with three parents might sound like monstrous chimeras, but they are among us already. In the late 1990s, an American team created the first genetically engineered humans by adding part of the egg of one woman to the egg of another, to treat infertility. When the US Food and Drug Administration got wind of the technique it was promptly banned, though related methods have been used in other countries.
Now a research team in the UK is experimenting with creating three-parent embryos. This time, the goal is to prevent children inheriting a rare group of serious diseases caused by faulty mitochondria, the powerhouses in our cells. Mitochondrial diseases affect at least 1 in 8000 people, probably more, and there are no treatments.Mitochondria are always inherited from the mother, so for women in whom they are faulty, replacing the mitochondria in their eggs with ... source:NewScientist; the whole article in pdf
with healthy ones from a donor would help ensure their children are healthy. What makes the idea controversial is that mitochondria contain DNA of their own, meaning babies created this way will have genes from a “second mother”.
Supporters of this approach point out that mitochondria contain a mere 37 of the 20,00 or so human genes. Changing them is akin to changing a battery, they argue. Yet it is becoming increasingly clear that the influencе of mitochondrial genes extends far further:
different variants can affect our energy, athleticism, health, ageing, fertility, perhaps even our intelligence, all of which help make us who we are as individuals.
Soon after an egg with faulty mitochondria is fertilised, its nucleus is taken out and injected into a donor egg cell whose nucleus has been removed. The outcome is an embryo with nuclear genes from the prospective parents and mitochondrial DNA from the second mother. In principle, all the mutant mitochondria should be left behind; in practice, however, a few may stick to the transplanted nucleus. Even though their numbers start off small, as the embryo grows the proportion of mutant mitochondria could be ramped up in some cells, as happened after ooplasmic transfers.
Typically the proportion of mutant mitochondria per cell has to exceed a certain threshold before problems begin. This means people with the same mitochondrial mutation can have quite different symptoms, or none at all, depending on the fraction of mutant mitochondria in cells in different parts of their bodies. Chinnery and Turnbull are now investigating whether the transfer of a handful of mutant mitochondria along with the nucleus could result in some cells having a dangerously high proportion of mutant mitochondria. The early results suggest not.
Even if children conceived by this means are healthy and stay that way, Van Blerkom points out that a disease might reappear generations later. The problem is the random segregation of mitochondria into developing egg cells, and their subsequent multiplication from as few as 10 to the 100,000 in a mature egg cell. If even a handful of faulty mitochondria get into the germline, they could be amplified to a level high enough to cause a recurrence of disease in descendants of the female line.
This might seem to be a serious argument against three-parent embryos, until you consider the alternative. At the moment, women who discover that their mitochondria bear dangerous mutations face a terrible dilemma when it comes to having children.
The peculiar nature of mitochondrial diseases means that even when all a woman’s mitochondria are mutant, a child could be anything from perfectly healthy to suffering from a far more severe form of the disease than the mother. In some cases doctors can give more precise odds, but often they can’t.
On the designer babies:
We are learning that the role of mitochondrial DNA goes deeper than anyone thought. Perhaps
the biggest surprise over the past decade is that mitochondria are responsible not merely for energy production in cells, but also for orchestrating programmed cell death.
The state of mitochondria is the decisive factor determining whether cells live or die, with obvious implications for health and disease, from cancer to degenerative diseases such as Alzheimer’s.
The minus side:
Of the 1500 or so mitochondrial proteins, just 13 are encoded by mitochondria genes and roduced locally. The rest are encoded in nuclear DNA, made elsewhere in the cell and exported to mitochondria. These two sets of proteins, encoded by different genomes, have to work together intimately, yet mitochondrial DNA mutates around 20 times as fast as nuclear DNA. If such mutations mean the two genomes don’t function well together, then an individual is
more likely to suffer from a range of disease At worst, the embryo could die.
My comment: I find this article really really marvellous! I mean isn't it great to be able to do and understand all that?! I had an article on designer babies recently, this is the continuation. The part of the article I skipped is the explanation why every benefit we could add comes up with a cost. I leave that for your home reading. The point is that obviously, we're on the way to do a lot more than we would like to admit. Yes, everything comes with a cost, but sometimes the cost is more acceptable, sometimes not. The future development I think we should see is an estimation on how and why mitochondria mutates. That should help in eliminating many diseases. Btw, did you know that mytodondria are always inherited from the mother? Cool, right :)
'Hairy blobs' in acid hell suggest new niche for life
- 09 June 2008
IN CLOSE-UP, they look like something out of a 1950s B-movie. Colonies of fossilised creatures, dubbed "hairy blobs", have been discovered in one of the harshest environments on Earth. The find may turn out to be crucial for spotting signs of extraterrestrial life in rocks on other planets.
Kathleen Benison, a geologist at Central Michigan University, Mount Pleasant, led a team that studied the sediments formed by acidic and very salty lakes in modern day Western Australia, and those deposited around 250 million years ago in North Dakota. It is very difficult to survive in such a tough environment and few signs of life have ever been found in these sorts of lakes.Inside the halite and gypsum "evaporite" minerals, which form as the lake waters dry up, Benison and colleagues found previously unknown fossilised blobs at both the modern and ancient sites, ranging in size from 0.05 to 1.5 millimetres. They were made up of a mix of inorganic crystals and "hairs" stuck together in a mass (pictured). They named them hairy blobs.
The team argues that each hair was in fact a separate microorganism because the hair fossils are made of disordered graphite which, unlike inorganic graphite, has irregular layers that suggest it was once a live organism..
Many of the hairs are coated with crystals of gypsum, a calcium sulphate mineral. This link with gypsum suggests that the microorganisms were fuelled by chemical interactions with sulphur in the acidic water - which helped the gypsum to form.
The team also found previously undescribed microorganisms in the lake water, which they say may be the cells that end up as fossilised hairs (Astrobiology, DOI: 10.1089/ast.2006.0034).Conditions in acidic saline lakes such as those studied by the team are thought to be similar to those on ancient Mars... source full article
My comment: Nice, heh? I knew life is very tough bastard, but now we have an evidence. So, let's all go to Mars and meet the Future.