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Cadherins are cell adhesion molecules widely expressed in the nervous system, where they play various roles in neural patterning, nuclei formation, axon guidance, and synapse formation and function. Although many published articles have reported on cadherin expression in rodents and ferrets, there are limited data on their expression in primate brains. In this study, in situ hybridization analysis was performed for 10 cadherins [nine classic cadherins (Cdh4, -6, -7, -8, -9, -10, -11, -12, and -20) and T-cadherin (Cdh13)] in the developing postnatal telencephalon of the common marmoset (Callithrix jacchus). Each cadherin showed broad expression in the cerebral cortex, basal ganglia, amygdala, and hippocampus, as previously shown in the rodent brain. However, detailed expression patterns differed between rodents and marmosets. In contrast to rodents, cadherin expression was reduced overall and localized to restricted areas of the brain during the developmental process, suggesting that cadherins are more crucially involved in developmental or maturation processes rather than in neural functioning. These results also highlight the possibility that restricted/less redundant cadherin expression allows primate brains to generate functional diversity among neurons, allowing morphological and functional differences between rodents and primates.

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Involvement of auxin polar transport in flower formation of Arabidopsis thaliana was studied using a pinformed (pin) mutant (Rpin) transformed with the indoleacetamide hydrolase (iaaH) gene and the phenocopy of the pin mutant, which was induced by 9-hydroxyfluorene-9-carboxylic acid (HFCA). The application of indoleacetamide (IAM) did not change aberrant structure of the aerial part of Rpin (pin/pin), but extremely inhibited its root growth. Treatment with IAM increased the endogenous concentrations of free and conjugated IAA in Rpin normal (pin/+ or +/+) due to the expression of the iaaH gene, to 140% and 428% of those in non-treated plants, respectively, and those in Rpin to 378% and 120%, respectively. The activity of IAA polar transport in the inflorescence axis of Rpin remained low even in the presence of IAM, the activity being almost similar, to that in the pin mutant. The activity of IAA polar transport in the HFCA-induced phenocopy of the pin mutant was also extremely low, and it was not restored by the simultaneous application of IAA. Arabidopsis thaliana responded to HFCA applied from 7 to 11 d and from 25 to 29 d after germination in the wild-type plant (Enkheim ecotype) and the late flowering mutant (fb mutant), respectively. These results suggest that the construction of the system of auxin polar transport and its normal activities are essential for the differentiation and the formation of floral meristem in the early growth stage of Arabidopsis thaliana.

The cerebral cortex is an indispensable region that is involved in higher cognitive function in the mammalian brain, and is particularly evolved in the primate brain. It has been demonstrated that cortical areas are formed by both innate and activity-dependent mechanisms. However, it remains unknown what molecular changes induce cortical expansion and complexity during primate evolution. Active DNA methylation/demethylation is one of the epigenetic mechanisms that can modify gene expression via the methylation/demethylation of promoter regions. Three growth arrest and DNA damage-inducible small nuclear proteins, Gadd45 alpha, beta, and gamma, have been identified as regulators of methylation status. To understand the involvement of epigenetic factors in primate cortical evolution, we started by analyzing expression of these demethylation genes in the developing common marmoset (Callithrix jacchus) and mouse (Mus musculus) brain. In the marmoset brain, we found that cortical expression levels of Gadd45 alpha and gamma were reduced during development, whereas there was high expression of Gadd45 beta in some areas of the adult brain, including the prefrontal, temporal, posterior parietal and insula cortices, which are particularly expanded in greater primates and humans. Compared to the marmoset brain, there were no clear regional differences and constant or reduced Gadd45 expression was seen between juvenile and adult mouse brain. Double staining with a neuronal marker revealed that most Gadd45-expressing cells were NeuN-positive neurons. Thus, these results suggest the possibility that differential Gadd45 expression affects neurons, contributing cortical evolution and diversity.

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