# Context & Objectives

# Chosen by the blob.

In 2022, the French National Centre for Scientific Research launched a large-scale science project, named "Derrière le Blob, la recherche" (litt."Behind the blob, the research"). Open to the general public throughout the world, this experiment of unprecedented scope aims to study the effects of climate change on the blob.

46'000 people registered to be part of the experiment, for 15'000 blobs. The selection process was rather unique. All the volunteers were divided into 3 groups of equal size, labeled Group 1, Group 2 and Groupe 3. Each group was identified by a drop of water filled with identical concentrations of sugar, and was placed at an equal distance on the side of a Petri dish. A blob was placed in the center equidistant from the three drops of sugar water. After a few hours, it started to explore and detected the sugar molecules from groups 2 and 3 before that of group 1, hence selecting the volunteers in groups 2 and 3. (I was group 3 :-) ).

In this section, I will attempt to write about the fascinating "thing" that is the Blob, record a few usefull information on the course of the experiment as well as some updates.

# What is the Blob?

The Blob, at the Paris Zoo 2019, Credit Stéphane De Sakutin, AFP.

There are hundreds, if not thousands of different kinds of it. But the most common is called the Physarum polycephalum. Mostly know as the Blob, as a tribute to a movie of the same name from 1958, it is a rather unique single-cell organism.

It's not an animal, nor a vegetable, nor a mushroom. It is bright yellow and formless. It doesn't have a brain, but has learning capabilities. It can move, but has no legs. It can transmit information as it merges with other blobs. It can double in size daily. It's able to regenerate itself over the course of a few minutes, and its life span can easily reach several decades. Mostly made up of a network of 'veins', they redistribute all the nutrients and other essential proteins in the most efficient way possible.

Although the story goes that the blob was discovered in 1973, it first appeared on Earth a billion years ago. The blob is composed of a single cell but this can reach several meters in diameter (in comparison, a human cell measures on average ten micrometers in diameter, or ten million times less!)

Just like humans, the blob, is the result of the fusion of two sex cells. In a proper environment, their spores are released into the air. When two cells of opposite sex meet (which isn't too difficult, since there are 720 sexes out there...), they fuse to become a single cell. But, unlike us, the cell will not divide. Its nucleus will. Therefore, the cell grows according to the divisions of its nuclei, until it reaches record sizes.

Blobs are mostly found in humid and shady areas of forests. When environmental conditions are bad (drought or lack of food) the blob turns into a sclerotium, which is a dormant state, until the situation improves. It can stay that way for years, and even decades.

# Objective of the experiment

Human beings can acclimatise themselves to a wide range of temperature and humidity. When traveling to high altitudes, our bodies adjust so that our cells still receive sufficient oxygen. When traveling in a very warm country, our body rids itself of excess heat by sweating. This ability, which is likely the results of thousands of years of acclimatisation, has made it possible for us to survive in most regions of Earth, from tropical countries, to harsh deserts, and arctic countries -- while most animals are restricted to a few environments.

While we often imagine global warming as a steady and regular increase of global temperature, it, in fact, manifests itself in a few different ways. One of the most impactful ones is through abrupt changes of temperature and environment. Essentially, these phenomenons are surprising changes in the climate system (non-linear) which results in a new climate state, much more suddenly than what is expected. The more abrupt, the less efficient a population is in adaptation, and can, eventually, dwindle and become extinct.

The aim of the experiment is to study whether the growth and behavior of the blob will be affected by regular and/or sudden changes in temperature. Apart from the temperature parameter, all the other parameters (e.g. lighting, food quantity, environment...) likely to affect the growth and behavior of the blob must be rigorously controlled.

The result of this experiments will be a scientific article published in open access towards the end of 2022.

# The experimental protocol

I have been attributed a strain of blob called Badhamia Utricularis, from Austria. This strain is mostly slow compared to Physarum Polycephalum, especially in the wake up phase (... I like him already!). Before starting the experiment, I will have to wake up, make it reach a critical size and duplicate it over 8 blobs (4 control blobs and 4 experimental blobs).

The experimental blobs will be subject to an increase of +0.5°C to +8°C over 5 or 10 days, while the control blobs will remain at room temperature. The temperature profiles will depend on a set of predefined protocols, which are freely accessible here (CNRS, in French).

I am asked to follow 4 protocols (no. 2, 3, 10 and 15), which will be detailed in the upcoming sections, but are summarized as followed :

  • Gradual drop in temperature (over the course of 5 days)
  • Increase in temperature over 1 day (over the course of 5 days)
  • Low intensity increase over 2 days (over the course of 5 days)
  • Five successive increases in temperature (over the course of 10 days)

# Useful links.