Nessa Carey Quotes & Sayings

It also showed that the only real block to bi-maternal reproduction is the DNA methylation pattern at key genes. It disproved a previous hypothesis that sperm were required because the sperm themselves carried certain necessary accessory factors such as particular proteins or RNA molecules required to kick-start development properly.16 — Nessa Carey

In 2002 scientists demonstrated beautifully just how random the process of X inactivation really is, by cloning a calico cat. They took cells from an adult female cat, and carried out the standard (but still fiendishly tricky) process of cloning. To do this, they removed the nucleus from the adult cat cell and put it into a cat egg whose own chromosomes they'd removed. This egg was implanted into a surrogate cat mother, and a lively and beautiful female kitten was born. And she didn't look anything like the genetically identical cat of which she was a clone.18 — Nessa Carey

But DNA isn't really like that. It's more like a script. Think of Romeo and Juliet, for example. In 1936 George Cukor directed Leslie Howard and Norma Shearer in a film version. Sixty years later Baz Luhrmann directed Leonardo DiCaprio and Claire Danes in another movie version of this play. Both productions used Shakespeare's script, yet the two movies are entirely different. Identical starting points, different outcomes. — Nessa Carey

In this model, there is a vicious cycle of events that results in the generation of a more and more repressed state. One of the predictions from this model is that repressive histone modifications attract DNA methyltransferases, which deposit DNA methylation near those histones. This methylation in turn attracts more repressive histone modifying enzymes, creating a self-perpetuating cycle that leads to an increasingly hostile region for gene expression. Experimental data suggest that in many cases this model seems to be right. Repressive histone modifications can act as the bait to attract DNA methylation to the promoter of a tumour suppressor gene. A key example of this is an epigenetic enzyme we met in the previous chapter, called EZH2. The EZH2 protein adds methyl groups to the lysine amino acid at position 27 on histone H3. This amino acid is known as H3K27. K is the single letter code for lysine (L is the code for a different amino acid called leucine). — Nessa Carey

Simple organisms like bacteria tend more to the Airfix way of life. Their genes are fairly set, coding for just one protein. The more complex an organism becomes, the more the genome begins to resemble LEGO, with a much greater degree of flexibility in how the components are used. And when we think how extraordinary we humans are, it seems reasonable to say, in a nod to certain movie, that at the genetic level 'everything is awesome'. — Nessa Carey

Scientists have detected about 100 imprinted genes in mice, and about half this number in humans. It's not clear if there are genuinely fewer imprinted genes in humans than in mice, or if it's just more difficult to detect them experimentally. Imprinting evolved about 150 million years ago7, and it really only occurs to a great extent in placental mammals. It isn't found in those classes that can reproduce parthenogenetically. — Nessa Carey

Incredibly, the human body produces about 2 million red blood cells every second. — Nessa Carey

Imagine Spider-Man is standing in a set position and needs to get something. He throws a web at the thing he wants, and then drags it to him. Now imagine that a very tiny Spider-Man is standing at one end of a cell. He throws a web at the chromosome he wants, the web attaches, and he pulls the chromosome to his end of the cell. A tiny Spider-Man clone does the same thing at the opposite end of the cell for the other chromosome in the matching pair. — Nessa Carey

It's not just humans who have trisomies of the sex chromosomes. One day you may be happily amazing your friends with your confident statement that their tortoiseshell cat is female when they deflate you by telling you that their pet has been sexed by the vet and is actually a Tom. At this point, smile smugly and then say 'Oh, in that case he's karyotypically abnormal. He has an XXY karyotype, rather than XY'. And if you're feeling particularly mean, you can tell them that Tom is infertile. That should shut them up. — Nessa Carey

Children who eat breakfast are statistically more likely to do well at school than children who skip breakfast. — Nessa Carey

John Gurdon spent around fifteen years, starting in the late 1950s, demonstrating that in fact nuclei from specialised cells are able to create whole animals if placed in the right environment i.e. an unfertilised egg — Nessa Carey

There is increasing evidence that at least some of the targeting of epigenetic modifications can be explained by interactions with long ncRNAs. Jeannie Lee and her colleagues have recently investigated long ncRNAs that bind to a complex of proteins. The complex is called PRC2 and it generates repressive modifications on histones. PRC2 contains a number of proteins, and the one that interacts with the long ncRNAs is probably EZH2. The researchers found that the PRC2 complex bound to literally thousands of different long ncRNA molecules in embryonic stem cells from mice13. These long ncRNAs may act as bait. They can stay tethered to the specific region of the genome where they are produced, and then attract repressive enzymes to shut off gene expression. This happens because the repressive enzyme complexes contain proteins like EZH2 that are capable of binding to RNA. — Nessa Carey

More long non-coding RNAs are expressed in the brain than any other tissue (with the possible exception of the testes).26 Some have been conserved from birds to humans, with expression patterns that occur in the same regions and at the same developmental stages. These — Nessa Carey

Sometimes the greatest scientific breakthroughs happen because someone ignores the prevailing pessimism. — Nessa Carey

Our brains contain one hundred billion nerve cells (neurons). Each neuron makes links with ten thousand other neurons to form an incredible three dimensional grid. This grid therefore contains a thousand trillion connections - that's 1,000,000,000,000,000 (a quadrillion). It's hard to imagine this, so let's visualise each connection as a disc that's 1mm thick. Stack up the quadrillion discs on top of each other and they will reach the sun (which is ninety-three million miles from the earth) and back, three times over. — Nessa Carey

You could make iPS cells by introducing just four genes into a differentiated cell. — Nessa Carey