[Esterase. VI. The effect of testosterone on the unspecific carboxyl esterase in mouse kidney during postnatal development]

Development of esterase activities in the chicken before and after hatching

The embryonic chick has long been a model for developmental biology and has often been recommended as a model system in developmental toxicology. More recently, several investigators have shown that the chick embryo also provides a good model for identifying the neurotoxic effects of environmental pollutants, especially cholinesterase-inhibiting pesticides. Although numerous studies detail the structural development of chick embryos, few describe embryonic levels of enzyme synthesis and their changes during development. In this study, the development of esterase activity in chick embryos was measured from day 9 of incubation until 46 days after hatching. Brain acetylcholinesterase (AChE) activity was detected on day 9 of incubation at a concentration of 0.364 mumoles/min/g tissue. An increase between AChE activity and age of the embryos was observed. In the liver, the nonspecific cholinesterases (ChE) and carboxylesterase activities during incubation were not different from activities after the chicks had hatched. Plasma ChE and carboxylesterase activities did not change with age after hatching. Brain neuropathy target esterase (NTE) activity was not detected on day 9 of incubation and was extremely low (6.12 nmoles/15 min/mg protein) the next day, but increased rapidly with increasing age. This study demonstrates that chick embryos have developed esterase activities in the brain and liver by day 10 of incubation and again confirms that the insensitivity of chick embryos and young chicks to organophosphorus ester-induced delayed neurotoxicity is not due to absence of NTE. In addition, the results provide baseline data for evaluating the response of embryonic and immature chicks to neurotoxicants and teratogens.

Esterase. XXI. Es-9, a possibly new polymorphic esterase in Mus musculus genetically linked to es-2

A so far undescribed gene controlling zone III esterases has been detected by means of disc gel electrophoresis of kidney homogenates from the two inbred mice strains NMRI and SK/Cam. The gene is tentatively designated Es-9, and the two codominant alleles are designated Es-9a and Es-9b. Es-9 esterases are present in many tissues, but, unlike the other zone III esterase (controlled by Es-5), are not found in the serum. Close linkage with the Es-2 gene leads us to map the Es-9 gene on chromosome 8.