Archive for the ‘Biologija’ Category
Embedded in mudstones deposited during the Cambrian period 520 million years ago in what today is the Yunnan Province in China, the approximately 3-inch-long fossil, which belongs to the species Fuxianhuia protensa, represents an extinct lineage of arthropods combining an advanced brain anatomy with a primitive body plan.
The Guardian donosi članak o miševima nastalim iz matičnih stanica.
In the shorter term, being able to create eggs in the lab from stem cells could help scientists to better understand female infertility by giving them insights into how eggs age and how they sometimes develop incorrectly.
Robert Norman, a professor of reproductive and periconceptual medicine at the University of Adelaide, said the research would one day allow infertile women to have genetically related children, but that would be far in the future. “Major concerns still need to be addressed including long-term health of the offspring,” he said.
Hardwickeovi vunasti šišmiši žive u vrčevima karnivore Nepenthes hemsleyana – svojom veličinom tako savršeno pristaju u vrčeve da se ne moraju pridržavati. Šišmiši sami borave u šupljinama od kojih su neke dovoljno velike za ženku s mladim.
Jasna je korist koju imaju šišmiši, gdje je korist za biljku? Otkriveno je da je izmet šišmiša bogat dušikom. Krasan primjer koevolucije.
Stari intervju Laurija Pycrofta za New York Times u kojem govori o razlozima zbog kojih se suprotstavio militantnom aktivizmu za prava žvotinja, te o svom ateizmu:
“They got quite hostile,” he said. So he went to a stationery store and bought a large square of cardboard and a pen and wrote: “Support Progress. Build the Oxford Lab.” When he started waving the sign on the street, someone compared him to excrement. Another person tore the sign apart, he said. He went home and shared his experience on his blog. The result was a new movement, called Pro-Test.
“He posted something on his blog, and a group of us got talking,” said Iain Simpson, a 19-year-old second year student of Politics, Philosophy and Economics, who is Pro-Test’s spokesman. “This isn’t so much about Oxford students and their feelings about one building. It’s about animal research. What we are trying to do is to turn the tide of public opinion.”
That belief is not rooted in religion, although Mr. Pycroft recalled verses in the Book of Genesis that support his belief. “I’m strictly atheist,” he said. “Reading the Bible is the strongest advertisement for atheism.”
Nature je objavio vodič za ENCODE!
They’ve discovered a far larger chunk of our genetic code is biologically active than previously thought.
The researchers hope the findings will lead to a deeper understanding of numerous diseases, which could lead to better treatments.
More than 400 scientists in 32 laboratories in the UK, US, Spain, Singapore and Japan were involved.
Their findings are published in 30 connected open-access papers appearing in three journals, Nature, Genome Biology and Genome Research.
The Encyclopedia of DNA Elements (Encode) was launched in 2003 with the goal of identifying all the functional elements within the human genome.
A pilot project looking at 1% of the genome was published in 2007.
Why evolution is true objavio je odličan članak o ginandromorfnim kardinalima:
This, by the way, is a very graphic demonstration of the differences between males and females, with the brighter color of the male almost certainly reflecting sexual selection (with bright colors presumably advantageous in males because they attract females, but disadvantageous in females because they attract predators).
Now how does this happen? I used to see this sometimes in my Drosophila flies, and we?ve long known how a half-male, half-female fly forms. In flies the sex is determined by the ratio of X chromosome to autosomes. Flies, like all diploid species, have two copies of every autosome. If you also have two X chromosomes, you?re a female because the ratio of autosomes to Xs is 1:1. If you have one X chromosome and one Y chromosome, your ratio is 2:1 and you?re male. The Y doesn?t matter here: if you lose a Y chromosome, and hence are XO, you still look like a male, although you?re sterile (the Y carries genes for making sperm).
If one compares the DNA “letters” in the sequences of all three species, there is only a 1.3% difference between humans and their ape cousins.
The separation between the bonobo and the chimp is smaller still. Only four letters in every thousand is changed.
But as similar as their genomes are, bonobos and chimps do display some quite diverse behaviours.
Chimps are very territorial and resort to aggressive actions to resolve conflicts, whereas bonobos are more placid and will use sex as a tool to settle their differences.
“That’s the great hope,” said Dr Prufer. “If you look at bonobos, chimpanzees and humans, what you can see is that there are some specific characteristics that we share with both of them.
“So, for instance, the non-conceptive sexual behaviour is a trait that is certainly shared with bonobos, while the aggressive behaviour unfortunately is also a trait that is shared with chimpanzees.
Mjesto: Atapuerca špilja u sjevernoj Španjolskoj
Nađeno: 28 ljudskih tijela.
Starost: Znanstvenik Arsuaga i kolege iz Sime: 600,000 godina
Starost: Chris Stringer iz Natural History Museuma UK: 400,000 godina
Vrsta: Arsuaga tvrdi – to je Homo heidelbergensis, predak Neandertalaca
Vrsta: Stringer tvrdi – to je Neandertalac,
Problem: osim 200,000 godina razlike u datiranju, profesor Stringer tvrdi da je Homo heidelbergensis predak današnjeg čovjeka.
…. the remains of 28 bodies have been dug up, the world’s greatest single haul of ancient human fossils. During this time, Arsuaga and his team pushed back the dates of their finds to 600,000 years ago and assigned them as belonging to Homo heidelbergensis.
But Britain’s leading expert on human evolution, Professor Chris Stringer, of the Natural History Museum, has warned in the journal Evolutionary Anthropology that the team in charge of La Sima has got the ages of its fossils wrong by 200,000 years and has incorrectly identified the species of ancient humans found there.
Sima scientists argue that the fossils must be older. They say the 28 bodies were thrown into the pit as an act of reverence for the dead and that the stalagmite grew over the sediment containing the bones.
However, this interpretation is controversial. No one has found any other evidence of ceremonial behaviour in humans of that antiquity. In addition, there is a deficit of small finger and toe bones. “If complete bodies were thrown in there, you would expect to see every piece of human anatomy down there,” said Stringer. “But you don’t. A lot of skeletal parts seem to be missing.”
This dating and identification has caused increasing upset among other palaeontologists. The scientists at La Sima believe H heidelbergensis is an ancestor of Neanderthals but not of Homo sapiens. However, others, including Stringer, believe it is indeed an ancestor of our species.