Activity in space

Abstract

How the scalar world of molecules is translated into developmental complexity that is ordered in time and space belongs to the most challenging topics of biology. The advances in fluorescence microscopy, along with the availability of nondestructive fluorescent markers, have revealed that this order is more dynamic than thought before. As a consequence, developmental concepts such as polarity, axis, or pattern can no longer be seen as static objects but have transmutated into descriptions of activities. Actually, this insight, although not adopted by many, is not new. Already more than five decades ago, in his famous textbook, Sinnott (1960) defined polarity as "specific orientation of activity in space". What we see as biological order is therefore just a snapshot of ordered activity. The questions, how the dynamic order of the "protoplasma" coexists and interacts with the stability of Mendelian inheritance (e.g. Nakazawa 1960) and how this order is generated and sustained by directional movement of molecules in response to chemical and physical gradients (e.g. Harold 1997), have been central also in this journal, giving rise to classical publications that are still worth reading today.Three contributions in the current issue address how the temporal order of activity contribute to functional organisation at different levels of complexity: cells, organelles, and organs.All eukaryotic cells contain acidic organelles that are often involved in degradation or digestion processes. In yeast cells, this acidic compartment is represented by the vacuole. The acidity is actively maintained by the activity of a proton ATPase. The function of this acidification is thought to provide a chemical environment favouring hydrolytic reactions. In their comprehensive study published in the current issue, Matsumoto et al. (2013) show that, in addition, acidification is relevant for the proper allocation of proteins into the vacuole. They block the vacuolar proton ATPase by the specific inhibitor concanamycin A and then examine the localisation of more than 70 GFP-tagged luminal and vacuolar membrane proteins by quantitative image analysis. About a quarter of these proteins lose their vacuolar targeting after treatment with the inhibitors. These include hydrolases, transporters, but also subunits of the vacuolar proton ATPase itself. This points to a scenario where initial acidity of the vacuole not only acts as attractor for the proteins destined to act in this acidic environment but also, in parallel, boosts the chemical reaction responsible for this acidity, which is a nice illustration of selfamplifying self-organisation at the subcellular level.The dependence of protein function on subcellular distribution is also highly relevant for application, as carefully demonstrated by Pasare et al. (2013) in the current issue. Goal of their work was to improve the efficiency of metabolic engineering to generate potatoes that can be used as functional food because they contain elevated levels of nutritionally important carotenoids. The s...

Employing CRISPR/Cas Technology for the Improvement of Potato and Other Tuber Crops

“…In potato and other tuber crops, it is possible use the fluorescence marker-assisted selection for transgene-free genome-edited plants by the co-expression of fluorescence marker genes, as has been done for rice, tomato, and Arabidopsis ( Aliaga-Franco et al, 2019 ). All the more already investigated the potentials of green fluorescent protein as a marker to select transgenic hybrid potato tubers ( Palumbo and Veilleux, 2007 ) and red fluorescent protein to identify the localization of key enzymes of carotenoid biosynthesis after stable transformation in potato (tubers) ( Nick, 2013 ). However, the fluorescence marker facilitates them of the transgene-free plants, but it does not improve the ratio of transgene-free plants.…”