Journal Article

Differential Expression Patterns of Striate Cortex-Enriched Genes among Old World, New World, and Prosimian Primates

Toru Takahata, Rammohan Shukla, Tetsuo Yamamori and Jon H. Kaas

in Cerebral Cortex

Volume 22, issue 10, pages 2313-2321
Published in print October 2012 | ISSN: 1047-3211
Published online November 2011 | e-ISSN: 1460-2199 | DOI: http://dx.doi.org/10.1093/cercor/bhr308

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A group of 5 genes, OCC1, testican-1, testican-2, 5-HT1B, and 5-HT2A, are selectively expressed in layer 4 (4C of Brodmann) of striate cortex (visual area V1) of both Old World macaques and New World marmoset monkeys. The expression of these genes is activity dependent, as expression is reduced after blocking retinal activity. Surprisingly, the pronounced expression pattern has not been found in rodents or carnivores. Thus, these genes may be highly expressed in V1 of some but perhaps not all primates. Here, we compared the gene expression in members of 3 major branches of primate evolution: prosimians, New World monkeys, and Old World monkeys. Although the expression pattern of 5-HT1B was well conserved, those of the other genes varied from the least distinct in prosimian galagos to successively more in New World owl monkeys, marmosets, squirrel monkeys, and Old World macaque monkeys. In owl monkeys, the expression of 5-HT2A was significantly reduced by monocular tetrodotoxin injection, while those of OCC1 and 5-HT1B were not. Thus, we propose that early primates had low levels of expression and higher levels emerged with anthropoid primates and became further enhanced in the Old World catarrhine monkeys that are more closely related to humans.

Keywords: in situ hybridization; monocular inactivation; primate evolution; SPOCK; V1-specific

Journal Article.  5856 words.  Illustrated.

Subjects: Neuroscience

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