Cellular intelligence: (Evolution)

by David Turell , Monday, June 05, 2023, 22:21 (327 days ago) @ David Turell

Biofilms

DAVID: We both know humans are autonomously intelligent and at least I accept free will without question. Note the 'molecules' ACT AS IF. My statement does not say they are intelligent. You constantly twist statements.

dhw: My point was that if they act as if they are intelligent, how do you know they are not? I agree with you that we are autonomously intelligent, but you still haven’t offered one single attribute in addition to those I listed as evidence that cells are also intelligent.

Appearing intelligent doesn't mean it is not all automatic functions, remember?

Biofilms divide up functions:

https://www.the-scientist.com/features/how-bacterial-communities-divvy-up-duties-71138?...

"Biofilms form when groups of bacteria cover themselves in a sticky mixture of sugars, protein, and DNA. This extracellular matrix glues bacteria to surfaces and serves as a slimy shield, protecting cells in the interior from predators and antibiotics. Conventional drugs become ensnared in the matrix, tangled in a molecular mesh that prevents them from penetrating the biofilm’s inner layers. What’s more, oxygen depletion causes cells in the center to enter a hibernation-like state, making them tolerant to antibiotics that target metabolic processes. In fact, biofilms can withstand doses up to 1,000 times greater than their planktonic counterparts.

"Within the biofilm, bacteria take on different responsibilities. Some individuals focus on reproduction to expand the colony, while others specialize in construction, oozing polysaccharides and proteins that make up the extracellular matrix. And other bacteria defend the community, building molecular weapons that shoot competitors with toxins.

"These tasks aren’t fixed for life. As the biofilm matures and the community needs change, an individual bacterium may take on new responsibilities. Kovács’s team has found that in populations of the soil bacterium Bacillus subtilis, most microbes assume responsibility for matrix production during early development when they are little more than a throng of unconnected cells. But once construction progresses, some cells will switch to producing spores or useful enzymes.

"So how do bacteria dole out chores? It’s partly stochastic, said Kovács. By amplifying random fluctuations in cellular reactions, individual bacteria specialize into distinct roles. For instance, the cells within a B. subtilis biofilm that are engaged in protease production are randomly determined.

"Task delegation can also be influenced by a bacterium’s location within the biofilm, said Daniel Dar, a researcher of microbial systems at the Weizmann Institute of Sciences. Just as different boroughs of a city might differ in levels of air pollution or abundance of organic supermarkets, different parts of the biofilm are exposed to wildly different levels of oxygen and nutrients. Bacteria sense these microenvironments and adapt by up or down regulating the expression of certain genes to influence different cell processes.

***

"By lighting up expression of more than 100 genes, the researchers uncovered what looked like a color-by-numbers map of zoning regulations. Different clusters of bacteria showed diverse patterns of gene activity corresponding to altered metabolic states depending on their locations within the biofilm. For instance, microbes in the bottom portion of the mature biofilm had activated a set of genes that code for digestive enzymes, while their westerly neighbors prioritized transcription of genes involved in defense.

***

"Division of labor doesn’t only arise from differences in gene expression but can also be triggered by irreversible genetic changes. Among Streptomyces coelicolor, a soil-dwelling bacteria that forms fungal-like structures, deletions of large chunks of their chromosome causes a subset of cells to specialize in antibiotic synthesis. More than half of the antibiotics used to treat human infections are produced by S. coelicolor.

"Although the colonies start out as clones, unstable DNA regions quickly acquire mutations. In a paper published this year in Molecular Systems Biology, scientists reported how the S. coelicolor genome is split into two main sections. The more stable end of the chromosome houses genes that synthesize antibiotics, while the growth-promoting genes are located on the more fragile end. Mutations in these delicate regions often erase sequences associated with growth and replication, generating strains that are specialized in antibiotic secretion.

***

"Electricity can kill bacteria, but lower doses can also stimulate growth of specific cell types, said Gürol Süel, a biophysicist at the University of California, San Diego. Over the past decade, Süel’s team has uncovered how bacteria communicate through electrical impulses, much like a giant action potential that passes through the entire biofilm. Electrical signaling allows cells within the biofilm to regulate growth, share nutrients and recruit outsiders to join the community."

Comment: this work supports Shapiro's finding that bacteria edit DNA. I still believe all of this activity is from DNA programmed instructions.