Science Shorts — June 30, 2011

Topics for this edition: galaxy morphology, quasars, pain perception, gene therapy, and cancer.

Galaxy classification

For decades astronomers have classified galaxies into agreed-upon types based on their visible shapes. One broad type consists of spiral galaxies, and the other of elliptical and lenticular galaxies. Spiral galaxies have the familiar pinwheel appearance, while the others lack distinctive features such as arms and instead simply diminish in brightness gradually outward from the center. It has been the prevailing belief that spiral galaxies are generally younger, while the others are older and have gradually lost their spiral structure.

New research based on an observational survey known as ATLAS3D has incorporated measurements of galaxies’ rotational velocities, and it suggests that a more complex classification scheme may be appropriate. While all spiral galaxies rotate relatively rapidly, it has been found that many elliptical and lenticular galaxies do also – about 66% of them, and they may actually have a flattened disk shape like spirals, lacking only discrete arms.

arXiv: The Atlas3D project – VII. A new look at the morphology of nearby galaxies: the kinematic morphology-density relation

Very early quasar

Quasars are a type of active galaxy, in which a supermassive black hole at the center stimulates the radiation of enormous quantities of energy from clouds of matter heated to high temperatures due to a high velocity of rotation around the black hole. Quasars in the nearby universe are quite rare, since the peak production of energy lasts only on the order of 100 million years, before all the infalling matter has been consumed by the black hole.

However, quasars were much more numerous in the early universe, up to several billion years after the big bang. Because of a quasar’s high luminosity, the brightest of them can still be observed even if their peak of energy production occurred less than a billion years after the big bang. Astronomers continue to detect even earlier and more distant quasars, and the latest, known as ULAS J1120+0641, has just been described. It is estimated to be observed as it was only 770 million years after the big bang, implying that its light has taken about 12.9 billion years to reach us. The distance can also be specified through the amount of redshift (7.085) of the quasar’s light. The mass of the central black hole is estimated to be about 2 billion solar masses. That is quite surprising for such an early object, as it is comparable to the mass of quasar black holes that have had a much longer time to grow.

Nature article: A luminous quasar at a redshift of z = 7.085

Love eases pain

Nobody considers it surprising that people suffering physical pain find the presence and attention of loved ones to be comforting. However, research just published in PNAS indicates that merely the sight of a loved one can alter brain activity so as to lower pain. It also identifies some details of this activity.

Female experimental subjects in committed relationships were asked to view a series of images (their partner, a stranger, and a chair) while being subjected to a painful stimulus on their arm. On average, subjects reported feeling less pain when viewing their partner but more pain (in about the same degree) when viewing the stranger or the chair.

At the same time, fMRI scans of the subjects showed higher activity in the ventromedial prefrontal cortex (VMPFC) when viewing their partners than when viewing the neutral stimuli, and less activity in the dorsal anterior cingulate cortex and anterior insula. This is consistent with other research indicating inhibitory effects of VMPFC activity, and heightened response of the the other areas when experiencing pain. There was a positive correlation betwee the degree of VMPFC activity and the length of time subjects had been in their relationship.

PNAS DOI: Attachment figures activate a safety signal-related neural region and reduce pain experience

Gene therapy

The basic idea of gene therapy has been around for a long time, but it’s been very hard to make it work in practice. The idea is that if a particular disease condition is the result of a defect in a specific gene (or maybe a small number of genes), then replacing or supplementing the defective gene or genes with fully functional copies should help alleviate the disease.

However, the devil’s in the details. There are ways to replace defective genes of cells in vitro, but the DNA may be damaged, and getting the modified cells back into the proper locations in the body of a complex organism (like a human) is usually very hard. There are also techniques for more safely introducing fully functional genes into certain types of body cells in vivo – but the new genes do not get copied during cell replication.

What’s needed is a means of safely replacing defective genes with good ones within the actual cellular DNA so that they persist through replication. One technique using special enzymes – zinc finger nucleases (ZFNs) – has been developed, but efforts to demonstrate the efficacy and safety of this technique are still in early stages.

Hemophilia is a well-known heritable disease resulting from a defect in one particular gene (F9). Now there is research showing that a combination of appropriate ZFNs and a functional copy of F9 can be introduced (using viral vectors) into the livers of mice with defective F9 – and the blood clotting deficiency characteristic of hemophilia is substantially alleviated.

Nature DOI: In vivo genome editing restores haemostasis in a mouse model of haemophilia

Mutations leading to cancer

The basic “cause” of cancer is mutations of a cell’s DNA that prevent detection and repair of DNA damage that can occur for many other reasons, such as infections, radioactivity, carcinogens, too much ultraviolet light – or even chance errors occurring in the normal process of cell division. The transcription factor p53 plays a key role in detecting mutations and causing an appropriate cellular response. So when both normal copies of the TP53 gene that is the template for p53 itself become mutated the cell may be on an irreversible path to cancer.

Mutations of TP53 are found in more than half of advanced cancers, but it has often been supposed that this damage happens at a relatively late stage. However, it has been difficult to determine the order in which cancerous gene mutations actually occur. New research has developed a statistical technique that involve counting the number of extraneous copies of certain genes, including TP53. And one of the main findings is that mutations of TP53 often seem to occur sooner in the process than previously supposed.

Cancer Discovery DOI: Temporal Dissection of Tumorigenesis in Primary Cancers


About Charles Daney

I'm a science writer interested in most fields of science, and exploring how to make better use of the online environment for providing scientific information to a curious, engaged, but not specialized audience.
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