Tag Archives: Science

The Differentiation Code.

Our newest embryology related publication is now out. It is especially nice to get this out given the scare we got last June.

The Differentiation Code

Richard Gordon, Natalie K Gordon

Abstract

In code biology we seek a presumably arbitrary, and thus symbolic relationship between two or more entities, such as the relationship of the DNA triplet code to amino acids. Here we review the differentiation code from the code biology point of view. We observe that lineage trees of mosaic organisms can be subsumed as special cases of differentiation trees of regulating embryos. The latter can be empirically discovered as a bifurcating tree of contraction and expansion differentiation waves that recursively divide the embryo into its cell types. A binary digit, 0 or 1, assigned to each wave results in a binary number corresponding to each cell type, and may be called the differentiation code for that cell type. The differentiation tree has a correspondence in the genome, in terms of the genome’s logical structure. For a given cell type, the path to it from the zygote is marked epigenetically on the genome. Thus the differentiation code symbolically maps an epigenetically marked subset of the logical structure of the genome to the phenotype of a particular cell type. The waves involved and signal transduction from the cell state splitter to the genome are intermediaries in this relationship, and may also be arbitrary choices, and thus part of the code. In full, differentiation code = history along the differentiation tree of the differentiation wave types leading to a given cell type ⇔ contraction or expansion of the cell’s cell state splitter ⇔ activation of one of two signal transduction pathways from the cell state splitter to the nucleus ⇔ activation of one of two readied gene cascades (the “nuclear state splitter”) ⇔ epigenetic marking of the selected portion of the logical path. Each wave is in effect a cybernetic control system that results in differentiation of a set of cells and initiation of two new waves (cybernetic systems) as its goals. The differentiation code forms a basis for open evolution and its appearance was one of the major evolutionary transitions.

Four Diatom Problems

Zheng2015 Late Fig 43782_MediaPlayer_63659_06222015_195640

(By Michael Zheng, 2015)

TEM (Transmission Electron Microscopy) is a rare skill. I did a little when I wrote:
  • Bender, R., Bellman, S.H. and Gordon, R. (1970) ART and the ribosome: a preliminary report on the three-dimensional structure of individual ribosomes determined by an Algebraic Reconstruction Technique. J. Theor. Biol. 29, 483-488.

and learned to appreciate those who do it well.

There are 4 diatom problems I’d like to see solved, for which TEM may prove critical:
  1. What is the pathway (literally, not just biochemically) by which oil droplets are formed, coalesced, accumulated, passed out of the plastids, occupy huge volumes inside the diatom, and via milking or spontaneously get outside the diatom? Such knowledge may prove critical to biofuel production.
  2. Triangular Archaea and triangular centric diatoms sometimes have square (90deg) corners instead of the “expected” 60deg. This suggests some structure, something like a centriole, in those corners. What is there, if anything?
  3. Is there any correlation between the 3D array of microtubules and microfilaments and the shape of a diatom valve? If yes, can we observe how the relationship changes during valve morphogenesis?
  4. In motile pennate diatoms, what is the pathway by which raphe fibrils are formed and exit the cell membrane? Once out, are they attached to the membrane or not, while they traverse the raphe?
Regarding #2: While most plants do not have centrosomes, diatoms do, if not proper centrioles:

A New Review of Embryogenesis Explained

The review is by:

Dr. Palmiro Poltronieri
Editor-in-Chief, Challenges
National Research Council of Italy,
AgroFood Department,
Institute of Sciences of Food Productions
via Monteroni km 7
73100 Lecce, Italy

“The model discussed by the authors is based on a simple, unifying idea that differentiation waves, based on cell cytoskeleton, i.e., contraction and expansion of the network of microfilaments and microtubules, is at the basis of mechano-transduction signalling, that brings transcription factors to regulate chromatin into specific cell-stage differentiation states, based on regulons, i.e., the wholeness of opened DNA regions and inaccessible DNA regions. Thus, from determination of a cell’s fate, i.e., signaling to advancement of process, to differentiation state, i.e., new transcriptional program and reprogramming of active regulons, clusters of cells thus divide, mature and form the various cell type component tissues of the developing embryo.”

And my favourite part:

“Overall, the book is a great book, documenting with images, schematic reproductions and drawings the embryo development, showing parallelisms, universal processes and the peculiarities of various vertebrates and invertebrates.”

You can read the full open access review here:

The Science Police

The Science Police

by

On highly charged issues, such as climate change and endangered species, peer review literature and public discourse are aggressively patrolled by self-appointed sheriffs in the scientific community.

A profoundly important article that describes how peer review is really done. In most fields it is not important enough to have cables denying funding because of what the public might misperceive. Still, the science police exist. People inclined to be science police tend to gravitate to positions of power such as grants committees and senior academic administrative chairs.

I wish I had a nickel for every time we wrote a grant on our waves and got back an answer that basically said, “It’s an interesting result but it goes against the prevailing wisdom and so we won’t fund you to test it”

Our system of peer review is made up of deeply sincere individuals who are so convinced they are right and others are wrong that research progress is slowed and huge amounts of money are wasted,

I once had a fellowship application for a grant turned down with the following:

“You have written an excellent application, clearly showing your methodology and goals. Your references, publication record and previous accomplishments prove you are well qualified to do this research and you have a high probability of success. The project itself is completely novel and potentially ground breaking. However because you have never published about this topic in a reputable high impact journal we cannot fund you.”

My husband has the same committee tell him in one year he was brilliant and if the work held up it was likely time for another nobel prize in embryology. In the following year the same committee rejected him saying it is a wonder he ever graduated from high school. The only thing that changed was who the chair of the committee was.

This article is long but it very clearly illustrates a phenomena first described to me by writer and naturalist Jack Rudloe (though he says he heard it from someone else.)

“You can always tell an academic by the number of knives in his or her back.”