Benny Shilo

New site, new stories

jhalper — Sun, 03 Jan 2016 05:05:53 +0000

New site, new stories

Cells that “spit” out their contents and messenger RNA that is not so swift at delivering its message. Those are two brand new stories on our new and improved website. Check it out and let us know what you think.

The first story arose from a simple question: How do secretory cells – those that produce copious amounts of such substances as tears, saliva or all those bodily fluids – manage to get their contents out of the cell? Cells are walled all the way around; they don’t really have doors for letting things the size of a drop of fluid out. Instead, they use the vesicle system – small globes made of the same stuff as the cell membrane that transport the drops out to the edge. The vesicles then fuse with the membrane, releasing their cargo to the outside.

Prof. Ben-Zion Shilo and his group realized that this was all well and fine for small amounts of biochemicals, but secretory cells would need a better system. Their results, which involved a lot of intricate time-lapse observation in the saliva glands of fruit-fly larvae, are beautiful to watch as well as instructive.

Salivary gland of a larval fruit fly. Vesicles (red) carrying the glue must empty their contents quickly and efficiently

The second story arose from a surprising observation: Certain liver cells that are involved in metabolism seemed to have large amounts of messenger RNA in their nuclei. Why would RNA stick around in the cell nucleus, instead of rushing out to make proteins? Dr. Shalev Itzkovitz and his group followed up on this question by asking further questions: How many cells keep RNA in their nuclei? How long does this RNA tend to stay? Which genes produce the homebody RNA?

Although they have not yet answered every one of their questions, they have uncovered a new level of regulation in the cell – one that is not immediately intuitive.

Nuclei of liver cells, mRNA of certain genes in white

Revealing how some cells get rid of their contents or discovering that others hoard things deep within – neither finding will cure disease tomorrow. Both are changing our understanding of how the human cell functions, and both are going to contribute, in the future, to human health and welfare. We promise to keep bringing you these stories and more.

jhalper Sun, 01/03/2016 - 00:05

Getting the Whole Picture

jhalper — Thu, 12 Feb 2015 08:02:53 +0000

Getting the Whole Picture

What's in a picture?

Prof. Benny Shilo knows the value of a good picture. We recently mentioned his book: Life’s Blueprint, which uses photographs of things like bread dough and yeast cells to illustrate the process of biological development. Here is the image from the most recent piece we have uploaded on his research:

This is an individual Islet of Langerhans, as you’ve never seen it before. The white dots are the insulin-containing vesicles inside the beta cells, which both sense glucose levels and secrete insulin. Shilo and his team managed to get “close-up shots” of the individual cell membranes, and found that they have straight edges where both sensing and secretion functions are located.

We love the images in this new article on the work of Prof. Talila Volk because, aside from their eye-catching colors, these ones really do illustrate the story her work tells.

Volk’s work investigates how muscle fibers get renewed through exercise. It may all come down to a protein that senses muscle contraction and tells the DNA in the cell nucleus to make more muscle proteins.

In this image, red is muscle fiber in fruit fly larvae, green is nuclei (muscle fibers are large cells with multiple nuclei) (A) shows normal muscle fiber, the others show what happens when the protein is missing.

How does it work? This image says it all:

In the left image you can see how the protein structure encircles the cell nucleus. At the other end of its arms (red) it connects to the cell’s skeletal structure – the cytoskeleton. On the right, in green, you can see the protein structure. Its arms are springy – so that a pull on the end transmits a signal to the middle.

Volk and her group refer to the protein as a biological “mechanosensor,” and, indeed, there is something rather mechanical about the right-hand image.

Assuming that form follows function, Volk has surmised that similarly-shaped proteins in human muscle fibers do the same thing.

Third, we have some cancer research images from the lab of Prof. Lea Eisenbach:

These tell the story of anti-cancer immune activity. Tissue and tumor cells appear in blue, pink shows immune cells that attack the cancer cells. When tumor cells appear in the back, there are many immune cells (left); but in the brain (middle) the same tumor cells attract relatively few immune cells. In fact, the normal brain tissue (in the same brain) on the right has no immune cells. If you first inject the tumor into the rat’s back, where there is immune activity, and then inject the tumor cells from the back into the brain, the brain will be protected from the cancer.

And, oh yes, they are pretty too. This image, again from Talila Volk, of a 3-D computer model of a fruit fly larva muscle fiber was the inspiration for a sewing project:

jhalper Thu, 02/12/2015 - 03:02

Life's Blueprint

jhalper — Wed, 29 Oct 2014 06:07:58 +0000

Life's Blueprint

A new book will make you stop and think about the relationship between the microscopic world and the one we pass by every day.

Life’s Blueprint – The Science and Art of Embryo Creation; Benny Shilo, Yale University Press, 174 pages.

Stem cells and their niche

When a stem cell divides, one daughter maintains the stem cell fate while the other produces a differentiated progeny. Stem cells are positioned in a restricted spatial niche that provides signals maintaining them in a proliferative, nondifferentiated state. After division, only the undifferentiated progeny is retained in the niche. Top: Once the eye of the zebrafish (Danio rerio) is specified, cells differentiate and produce neurons that sense light. Retinal stem cells (red) are maintained throughout the animal’s life in a niche located next to the lens (K. Cerveny and S. Wilson, University College London); bottom: The live yeast stock, or mother, is carefully maintained in the bakery. Portions are allocated to produce dough and bread. A fine balance is kept to ensure a steady production of bread while continuing to propagate the yeast stock (B. Shilo, Hi Rise Bakery, Cambridge, Massachusetts)

One and one can equal one – or two. But sometimes one and one goes way beyond the question of quantity – into the realm of elaborate qualification. When a sperm penetrates an egg – the two begin as one: a single, fertilized cell. That cell, of course, begins another operation: division. At first the cells are identical, but soon a process begins that leads, in the end, to a many-celled, autonomous organism. The same process occurs in flies, humans and pretty much all the life that was can see.

In Life’s Blueprint, Prof. Benny Shilo of the Weizmann Institute of Science describes the precisely-orchestrated concert that is embryonic development (at least everything we know today about the process). This is one of the most complex processes in nature, from the point of view of the number of factors involved, the precision timing required for each step, regulating the concentrations of substances that shape the developing embryo, the ability to copy information with great accuracy (though not absolute – a few “typos” are necessary to drive natural selection and thus evolution), and more.

How cell signaling establishes a repeated pattern

The compound eye of the fruit fly is made up of eight hundred repeated units called ommatidia. During eye development, patterning takes place progressively from the bottom to the top of the picture, generating a new row of ommatidia every two hours. Once an ommatidium is established, it signals to inhibit cells at the immediate radius from assuming a similar fate. The newly formed ommatidia become spaced at fixed distances, just outside this radius. Once created, they will now generate their own inhibitory spheres, to outline spacing of the next row of ommatidia that will form. Top: Establishment of the founder cells (blue) for ommatidia during eye development (A. Shwartz and B. Shilo, Weizmann Institute); bottom: Pigeons sitting on a railing establish a fixed spacing (B. Shilo, Moss Landing, California)

Shilo's book, written for a popular readership, avoids excess detail and scientific jargon. Other books may describe embryonic development, but with the photos, this book adds a level of philosophical treatise to the concise descriptions. The photos – all taken by Shilo – are presented in pairs (one plus one); each pair contains one image of an important stage in embryonic development alongside a photo from the world of our human, everyday objects. Their message is unambiguous and precise: a statement about the rules and plans that shape our world – both the seen and the unseen.

jhalper Wed, 10/29/2014 - 02:07