Heme cannot exert a feedback when porphyria develops.
Whether force-generating cross-bridges exert a feedback on the dynamics of thin filament activation and inactivation in loaded fibers/myofibrils remains to be resolved.
Bodily zinc needs do not exert a feedback control on zinc absorption; instead, zinc absorption is controlled solely by the zinc levels in the enterocytes.
These observations pointed to a direct effect of IL-6 on the hepatic expression levels of Socs3 under HFD feeding, thereby likely exerting a feedback inhibition of the IL-6-mediating signaling.
For example, starch accumulation in plastids can exert a feedback inhibition on photosynthesis, and so adequate sink strength is often necessary to achieve the greatest impact from improvements in photosynthetic rates [ 79, 100, 101].
It is known that glucose availability and utilization are regulated by endocrine factors involved in appetite, growth, and energy homeostasis, and that glucose exerts a feedback loop on these endocrine pathways.
Hence it is likely that, similar to how hormones secreted from the ovary can exert a feedback regulation on gonadotropins (FSH and LH) in the hypophysis, these miRNAs might be involved in similar regulation of gonadotropins by targeting genes in the above pathways.
This finding challenges the paradigm that master clocks control the slave peripheral clocks, which then control the activity of other functional proteins or receptors, and suggests that in addition to this classic master-slave regulating mechanism, the downstream effector proteins can exert a feedback control.
If this is true, then the rapid reversion to euglycaemia following delivery of the insulin gene in our study may have prohibited complete liver-to-pancreas transdifferentiation. Additionally, the expression of human insulin may have exerted a negative feedback mechanism to inhibit endogenous insulin expression.
ICaT exerted a negative feedback regulation on the transcription of the Cav3.1 gene, and the activation of PP2A by ICaT led to increased levels of the pro-apoptotic markers caspase 9 and Bcl-xS and decreased levels of the anti-apoptotic marker Bcl-2.
