Wrapping up DNA for a Cell

All eukaryotic genomes, including the human genome, must be packaged into the nuclei of cells while still remaining readily accessible — and researchers have now taken a step closer to understanding how this feat is accomplished. Feng Song and colleagues used cryo-electron microscopy to show how DNA tightly wrapped around nucleosomes, which are composed of special packaging proteins called histones, results in a basic form of chromatin.

Read more about this research from the 25 April issue of Science here.

[Video © Institute of Biophysics, Chinese Academy of Sciences. Please click here for more information.]

© 2014 American Association for the Advancement of Science. All Rights Reserved.

Getting Better at Studying Ancient DNA

Scientists have dug up a lot of fossils in recent decades, always with the hope that DNA would linger intact in the fossilized bone. Of course, for such fruitful investigations to happen, the technology for sequencing paleogenomes had to be up and running, and until now, paleogenomics — a relatively young field — has been limited. Recently, however, and as B. Shapiro and M. Hofreiter explain now, the field has transitioned from digging to sequencing, thanks to advances in DNA extraction and preparation of DNA libraries.

Read more about this research from the 24 January issue of Science here.

[Image courtesy of Beth Shapiro. Please click here for more information.]

© 2014 American Association for the Advancement of Science. All Rights Reserved.

Getting Better at Studying Ancient DNA

Scientists have dug up a lot of fossils in recent decades, always with the hope that DNA would linger intact in the fossilized bone. Of course, for such fruitful investigations to happen, the technology for sequencing paleogenomes had to be up and running, and until now, paleogenomics — a relatively young field — has been limited. Recently, however, and as B. Shapiro and M. Hofreiter explain now, the field has transitioned from digging to sequencing, thanks to advances in DNA extraction and preparation of DNA libraries.

Read more about this research from the 24 January issue of Science here.

[Image courtesy of Beth Shapiro. Please click here for more information.]

© 2014 American Association for the Advancement of Science. All Rights Reserved.

Ancient DNA Links Native Americans With Europe

DNA extracted from the upper arm bone of a 4-year-old boy who died 24,000 years ago at a site in Siberia is providing new insights into Native American heritage; the whole-genome analysis of this bone suggests that today’s Native Americans may have deep European roots. Science journalist Michael Balter’s news story is based on a recent conference presentation by researcher Eske Willerslev of the University of Copenhagen.

Read more here.

[Image credit: The State Hermitage Museum, St. Petersburg; click the image for more information.]

© 2013 American Association for the Advancement of Science. All Rights Reserved.

"DNA Bricks" Act as Tiny Legos

Building upon the fields of DNA origami and DNA tiles, researchers have come up with a way to coax single-stranded DNA into a wide variety of shapes for possible applications in biophysics, medicine and nano-electronics. These “DNA bricks,” reported by Yonggang Ke and colleagues, assemble themselves into complex, three-dimensional nano-structures, and they might be ideal for hosting and delivering certain proteins or nanoparticles.

Read more about this research from the 30 November issue of Science here.

[Image courtesy of Yonggang Ke; click the image for more information.]

© 2012 American Association for the Advancement of Science. All Rights Reserved.

Cell Biology Word of the Week: Centromere

What it means: A centromere is the region of a chromosome that appears constricted between two identical copies of DNA. It’s generally—but not always—found directly at the center of a chromosome.

Why you should care: Chromosomes are duplicated when a cell prepares to divide. Its two identical copies of DNA, or its “sister” chromatids, are joined together at the centromere, giving the chromosome its familiar X-shape. Centromeres attach their paired “sisters” to a spindle structure that then guides each one into a different “daughter” cell. When centromeres don’t function correctly, daughter cells can receive the wrong number of chromosomes, which leads to conditions such as Down syndrome.

Read about centromeres in Science here.

Cold Spring Harbor Lab’s Web Site Wins SPORE Prize

When Cold Spring Harbor Laboratory’s DNA Learning Center (DNALC) launched its Web site in 1996, they did not foresee that it would grow into a portal for 18 content sites reaching more than seven million visitors per year. But, the evolution of multimedia efforts and the challenges along the way provided lessons for building learning resources and attracting larger audiences.

[[Image © Cold Spring Harbor Laboratory. All Rights Reserved. Click the image for caption information.]

Learn more about this Web site here. You can also learn more about the SPORE Prize and find past winners here.

© 2011 American Association for the Advancement of Science. All Rights Reserved.

Cell Biology Word of the Week: Apoptosis

What it means: Often referred to as “cell suicide,” apoptosis is a sequence of events by which a cell breaks down its own components—from the proteins that uphold its structure to the enzymes that maintain its DNA—so that the cell can self-destruct.

Why you should care: Clearing out unhealthy or unnecessary cells, without causing harm to other cells, is a normal part of development and health for all organisms on the planet. This includes removing infected cells to prevent the spread of pathogens and eliminating damaged cells that could become cancerous. This process of apoptosis also helps to sculpt out organs and body parts.

Read about a recent discovery in Science involving apoptosis here.

Genetics Word(s) of the Week: ChIP-chip and ChIP-Seq

What they mean: Experimental methods that combine chromatin immunoprecipitation (ChIP) with either microarray (chip) or next-generation sequencing (Seq).

Why you should care: ChIP-Seq is a relatively new and powerful method, evolved from the older ChIP-chip method, which enables scientists to identify exactly where on the DNA—out of the entire genome—an individual protein binds. From this, it is possible to predict which genes the protein likely controls. A cell that is unable to properly control its genes may die or cause diseases, such as cancer. Comparing protein-DNA binding patterns in cells from different tissues, organisms or disease states with ChIP-chip or ChIP-Seq can reveal a lot about how humans and other organisms develop, evolve or become sick.

Read about a recent discovery in Science involving ChIP-Seq here.

[Click the image for caption information.]

© 2011 American Association for the Advancement of Science. All Rights Reserved.

Genetics Word of the Week: Zinc Finger



What it means: A structure formed by a protein involving zinc ions. (It was originally drawn looking like a finger, but the crystal structure showed that it’s a bit more complicated than that.)

Why you should care: Zinc fingers are formed by many important proteins in our cells, particularly those known as transcription factors, which copy DNA to make other proteins. Without them, these transcription factors would not be able to bind to DNA. Zinc fingers also turned out to be incredibly useful for manipulating genomes and making genetically altered plants and animals.

Read about a recent discovery in Science involving nonsense mutations here.

[This image is Figure 1D from a paper by Greisman, et al. Structure of the wild-type Zif268 zinc finger-DNA complex (10, 13). The DNA is gray, and a ribbon trace of the three zinc fingers is shown in red (finger 1), yellow (finger 2), and purple (finger 3). The 18 residues that were randomized in this study (van der Waals surfaces shown in blue) occupy the major groove of the DNA and span the entire length of the binding site. {Image created with Insight II (Biosym Technologies, San Diego, California} — Image courtesy of Science/AAAS]

© 2011 American Association for the Advancement of Science. All Rights Reserved.

Genetics Word of the Week: Nonsense Mutation

What it means: A chemical change in a gene that makes the corresponding protein it encodes far shorter than it should be.

Why you should care: A nonsense mutation is one of the more dramatic types of changes that can happen to our DNA. They can occur spontaneously or because of certain chemicals or radiation, and they result in the production of abnormally short proteins that lack crucial functions. These truncated proteins can harm our body’s cells and sometimes lead to diseases, such as cancer.

Read about a recent discovery in Science involving nonsense mutations here.

[Click the image for caption information.]

© 2011 American Association for the Advancement of Science. All Rights Reserved.

© 2014 American Association for the Advancement of Science. All Rights Reserved.