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Symposium in remembrance of Jon Widom, 1955 – 2011

February 22, 2012

As many of you know, Jonathan Widom died suddenly last summer.  He was a Professor in the Department of Molecular Biosciences at Northwestern University.  The beauty of Jon’s scientific research was more than matched by his surpassing intellectual brilliance and personal warmth, and he is deeply missed by those who knew and loved him.  Jon’s family and colleagues have organized a symposium celebrating his life and work, which will be held at Northwestern’s Evanston campus on March 16, 2012.  Information about this gathering, called “Unraveling the Mysteries of Life:  Recognizing the Life and Work of Jon Widom”, can be found online here.  All are welcome. Additionally, tributes to Jon that will be shared at the meeting (and afterward) can be contributed here.

Finally Great Tasting, Low Alcohol Beer

February 17, 2012

A lab engineered strain of yeast may make low alcohol, great tasting beer a reality.

Let’s face it: low alcohol beer just doesn’t taste that great.  This is because the alcohol is either diluted or removed chemically after fermentation.  Both methods wreak havoc with a beer’s flavor.

Dr. John Morrissey of University College Cork is trying to change this.  His lab is working to generate a strain of yeast that turns some but not all of its sugar into alcohol.  That way the beer process is the same, just with less alcohol at the end.

This is different from stopping fermentation early.  In that case there are still sugars in the final product which ruin a beer’s taste even more than removing the alcohol!  Here the same amount of sugars are used up, it is just that only part of that energy has gone into making the alcohol.  Same sugar content, less alcohol.

Although we don’t have all the details because of intellectual property issues, what we do know is that he compared the genomes of yeast species that make a lot of alcohol and those that don’t.  In an email he stated that he focused on genes that would affect carbon metabolism without perturbing redox balance in a significant way.  Presumably he then swapped the appropriate genes between strains and created his low alcohol strain.

This is not only a godsend for low alcohol beer, but it may be useful for other fermentation processes as well.  For example, maybe something similar can be done for low or no alcohol wines which, apparently, are even less tasty than low alcohol beer.  Designated drivers everywhere will be thanking Dr. Morrissey profusely if he can make decent tasting, low alcohol drinks a reality.

And apparently it isn’t just designated drivers that want this stuff.  Judging by recent upticks in sales of the relatively low quality low alcohol beers currently on the market, there is definitely a market out there for such beverages.  A cool science project, decent low alcohol beer and nice profits to boot!  Who could ask for more? 

How beer is made, from Modern Marvels, www.history.com

Expression Data and LiftOver Files Available for Download

February 14, 2012

RNA expression data that are included in SGD’s SPELL expression analysis tool are now available for download in the expression directory. Datasets have been grouped by publication and are in PCL format.

LiftOver files that allow conversion of chromosomal coordinates between different S. cerevisiae genome versions are also now available for download via the genome_releases link in the sequence directory.

Multicellularity a Snap? Maybe so…

February 10, 2012

It took just a few months to go from one cell to many. Image adapted from Ratcliff, et al (PMID: 22307617).

Some people might think that the transition from single-celled creatures to multi-cellular ones must have been tough.  After all, single celled organisms ruled the world for the first one or two billion years of life here on Earth. 

And yet, all multi-celled beasts didn’t evolve from the same ancestor.  Current theories are that multicellularity evolved dozens of times over the ages.  In fact, all of the transitional stages of multicellular life can be seen in the volvocine green algae species around today.  So maybe it isn’t so tricky after all.

Using a very clever screen in yeast, Ratcliff and coworkers have shown that they can get crude multicellular life to evolve in the lab.  Basically they only let the yeast that settled easily to the bottom of a shaking flask go on to reproduce.  Within 60 or so days, they had the beautiful, snowflake-like, multicellular beasts made up of multiple yeast cells shown in the image to the right.

Of course multicellular is more than having a bunch of cells stuck together.  Heck, yeast do that now in something called flocs.  No, to be multicellular, these yeast need to reproduce in a way that generates new multicellular yeast and to have specialized cells.  The snowflake yeast from this experiment did both.

These yeast did not reproduce by creating sperm and eggs that combine to generate progeny.  Instead they reproduced more like a lot of plants do.  They produced smaller versions of themselves which then went on to grow to “adulthood.”  Multicellular life gave birth to more multicellular life.

Cells within these snowflakes were also willing to die for the common good.  For example, the cell where the juvenile snowflake was attached would undergo apoptosis so the juvenile could be released.  No single-celled organism would willingly take that kind of hit for other cells.

So it looks like these researchers managed to evolve multicellular organisms from single-celled ones in just a few months.  Pretty amazing what can be learned from yeast!

Of course some care is needed here.  Yeast actually evolved from a multicellular ancestor so some sort of memory of multicellular life may still be lurking in its genes.  If true, this might make the transition from one to many simpler in yeast than in other single-celled organisms. 

This is why the researchers plan to try similar experiments with single celled organisms that have been single cells throughout their evolutionary life.  Then they’ll have an even better idea about how easy the “one to many cells” transition is.

Multicellular yeast having babies.

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