Genome Complexity; making B cells (Introduction)

by David Turell , Saturday, February 04, 2017, 01:53 (2850 days ago) @ David Turell

There are two types of B cells in the spleen which make antibodies against infection invaders. Making them from stem cells require specialized enzymatic actions:

https://www.sciencedaily.com/releases/2017/02/170203101550.htm

"...a research team led by professor Bart Lambrecht (VIB-UGent/UZ Gent) demonstrated that mice genetically lacking in Taok3 did not develop MZB cells, and are more susceptible to bacterial infection.

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"Using an unexpected finding from another project that identified a protein, Taok3, as the trigger for the development of MZB cells, prof. Lambrecht and his team showed that mice without the genetic ability to make Taok3 developed other types of B cells, but not MZB cells. As a result, they were susceptible to pneumococcus infection, a major cause of respiratory illness.

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"Two types of B cells are formed in the spleen: MZB cells, named so because they are found in an area of the organ called the 'marginal zone', and follicular B cells. However, scientists knew little about the mechanisms governing why early B cells develop into MZB cells versus follicular B cells.

"Hamida Hammad (VIB-UGent): "We had a 'eureka!' moment after discovering that a little-known protein, Taok3, brings a certain proteinase, ADAM10, to the surface of the immature B cell that triggers its development into an MBZ cell. Without that special event, immature B cells can only develop into follicular B cells."

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"In mouse strains, the team observed in vivo that without Taok3, immature B cells never 'committed' to becoming MZB cells. MZB cells generate antibodies against encapsulated bacteria such as pneumococcus when they enter the bloodstream.

"Hamida Hammad (VIB-UGent): "With an abundance of only follicular B cells, Taok3-free mice are less capable of fighting these types of bacteria effectively.'"

Comment: As with most of these complex arrangements, an enzyme (ADAM10) is required to carry it out. Enzymes are giant molecules which are designed to carry out very specific actions. This mechanism must be developed in one step, as a step by step evolution would not work. Saltation by a brilliant mind, God, is the answer I prefer.