the endogenous AP中AP具体指什么 这是生命科学实验相关的问题

英语翻译
请问在这个句子：Endogenous triglyceride turnover in liver and plasma of the dog,其中 triglyceride turnover 该如何理解,怎么翻译?
这是文献的题目，没有前后句，我就是感觉不知道该怎么准确的翻译turnover，我也只是大概的认为是转变的意思，但是这样又觉得不够准确

英语翻译
Gibberellins are a class of endogenous phytohormones that regulate a wide range of developmental processes in plants,including germination ,stem elongation,and flower development .

英语翻译
Since the discovery of endogenous opiate receptors in the
1970s [1-3],followed by the characterization of endogenous
opioid peptides [4],the opioid system has been extensively
studied.The endogenous opioid system is consists of four distinct
neuronal systems that are widely distributed throughout
the CNS and peripheral organs.The four precursors are proopiomelanocortin,
proenkephalin,prodynorphin and pronociceptin/
orphanin FQ,each generating biologically active
peptides that are released at the synaptic terminals of opioidergic
neurons.These peptides exert their physiological
actions by interacting with the various classes of opioid
receptors present on both pre- and postsynaptic membranes
of opioid and opioid target neurons [5].
The most important opioid peptides seem to be the
pentapeptides enkephalins,which interact with both μ- and
δ-receptors,their affinity being significantly better for the
latter.This has triggered intensive studies to elucidate the role
of enkephalins in the brain,and to develop putative novel
effective treatments mainly in the field of analgesia and CNS
disorders,such as depression (review in [6,7]).

英语翻译
RNA Polymerase IV DirectsSilencing of Endogenous DNA
Plants encode subunits for a fourth RNA polymerase (Pol IV) in addition tothe well-known DNA-dependent RNA polymerases I,II,and III.By mutation ofthe two largest subunits (NRPD1a and NRPD2),we show that Pol IV silencescertain transposons and repetitive DNA in a short interfering RNA pathwayinvolving RNA-dependent RNA polymerase 2 and Dicer-like 3.The existenceof this distinct silencing polymerase may explain the paradoxical involvementof an RNA silencing pathway in maintenance of transcriptional silencing.