Premium
Two Glutamate Decarboxylase Forms Corresponding to the Mammalian GAD 65 and GAD 67 are Expressed During Development of the Chick Telencephalon
Author(s) -
Åhman AnnaKarin,
Wågberg Fredrik,
Mattsson MatsOlof
Publication year - 1996
Publication title -
european journal of neuroscience
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.346
H-Index - 206
eISSN - 1460-9568
pISSN - 0953-816X
DOI - 10.1111/j.1460-9568.1996.tb00732.x
Subject(s) - glutamate decarboxylase , biology , cerebrum , microbiology and biotechnology , embryo , complementary dna , embryogenesis , cdna library , messenger rna , enzyme , gene , biochemistry , genetics , central nervous system , endocrinology
The γ‐aminobutyric acid (GABA)‐synthesizing enzyme glutamate decarboxylase (GAD) was studied during development of the chick telencephalon. By means of reverse‐phase HPLC analysis, we showed that GABA indeed accumulates during embryogenesis, whereas the levels of glutamate, the substrate for GAD, are more or less unchanged up to later developmental stages. The enzyme activity increased ∼25‐fold from embryonic day 3 to embryonic day 17. Immunoblotting data revealed that two GAD proteins, of ∼65 and 67 kDa, were present during the period investigated. Furthermore, Northern blot analysis with probes obtained from rat cDNA sequences, as well as a chicken‐specific probe for GAD 65 generated by means of reverse transcriptase‐polymerase chain reaction (RT‐PCR), strengthened the interpretation that the chick embryo expresses genes corresponding to GAD 65 and GAD 67 . The rat probes recognized transcript sizes of 3.9 kb (GAD 65 ) and 5.6 kb (GAD 67 ), sizes which are different from those of the rat brain (Erlander et al., Neuron , 7 , 91−100, 1991). Sequencing of the RT‐PCR products revealed a high level of homology (82% at the nucleotide level) between the mammalian and chick GAD 65 genes. Taken together, these findings suggest that the chick embryo expresses two GAD genes during embryogenesis. The functional properties of each gene product remain to be investigated.