The causal gene of a novel small and round seed mutant phenotype (srs3) in rice was identified by map-based cloning and named the SRS3 gene. The SRS3 gene was grouped as a member of the kinesin 13 subfamily. The SRS3 gene codes for a protein of 819 amino acids that contains a kinesin motor domain and a coiled-coil structure. Using scanning electron microscopy, we determined that the cell length of seeds in the longitudinal direction in srs3 is shorter than that in the wild type. The number of cells of seeds in the longitudinal direction in srs3 was not very different from that in the wild type. The result suggests that the small and round seed phenotype of srs3 is due to a reduction in cell length of seeds in the longitudinal direction. The SRS3 protein, which is found in the crude microsomal fraction, is highly expressed in developing organs.

The alpha subunit of plant heterotrimeric G proteins (Galpha) plays pivotal roles in multiple aspects of development and responses to plant hormones. Recently, several lines of evidence have shown that Galpha participates in brassinosteroid (BR) responses in Arabidopsis and rice plants. In this study, we conducted a comprehensive analysis of the roles of the rice Galpha in the responses to BR using a defective mutant of the Galpha gene, T65d1. Decreased sensitivity to 24-epi-brassinolide (24-epiBL) in the T65d1 mutant was observed in many processes examined, e.g. in the inhibition of root growth and the promotion of coleoptile elongation. The T65d1 mutant also showed similar phenotypes to those of BR-deficient mutants, such as the specifically shortened second internode and the constitutive photomorphogenic growth phenotype under dark conditions. However, a negative feedback effect by 24-epiBL on the expression of BR biosynthetic genes was observed in the T65d1 mutant, and the levels of BR intermediates did not fluctuate in this mutant. To determine the epistatic relationship between the T65d1 mutant and d61-7, a weak allele of a rice BR receptor mutant, the two mutants were crossed. The T65d1/d61-7 double mutant showed no epistasis in the elongation inhibition of the internodes, the internode elongation pattern, the leaf angle and the morphological abnormality of leaf, except for the vertical length of seed and the seed weight. Our results suggest that the rice Galpha affects the BR signaling cascade but the Galpha may not be a signaling molecule in BRI1-meditated perception/transduction.

The alpha subunit of heterotrimeric G-proteins (G alpha) is involved in a broad range of aspects of the brassinosteroid (BR) response, such as the enhancement of lamina bending. However, it has been suggested from epistatic analysis of d1 and d61, which are mutants deficient for G alpha and the BR receptor BRI1, that G alpha and BRI1 may function via distinct pathways in many cases. In this study, we investigated further the genetic interaction between G alpha and BRI1. We report the analysis of transformants of T65d1 and T65d1/d61-7 into which were introduced a constitutively active form of G alpha, Q223L. The application of 24-epi-brassinolide (24-epiBL) to T65d1 expressing Q223L still resulted in elongation of the coleoptile and, in fact, it was enhanced over the wild-type plant (WT) level in a concentration dependent manner. In T65d1/d61-7 expressing Q223L, the seed size was enlarged over that of d61-7 due to activation of G alpha. These results suggest that Q223L is able to augment the BR response in response to 24-epiBL and also that Q223L functions independently of BRI1 in the process of determining seed morphology, given that Q223L was functional in the BRI1-deficient mutant, d61-7.

Aim: A Japanese individual with schizophrenia harboring a novel exonic deletion in RELN was recently identified by genome-wide copy-number variation analysis. Thus, the present study aimed to generate and analyze a model mouse to clarify whether Reln deficiency is associated with the pathogenesis of schizophrenia.Methods: A mouse line with a novel RELN exonic deletion (Reln-del) was established using the CRISPR/Cas9 method to elucidate the underlying molecular mechanism. Subsequently, general behavioral tests and histopathological examinations of the model mice were conducted and phenotypic analysis of the cerebellar granule cell migration was performed.Results: The phenotype of homozygous Reln-del mice was similar to that of reeler mice with cerebellar atrophy, dysplasia of the cerebral layers, and abrogated protein levels of cerebral reelin. The expression of reelin in heterozygous Reln-del mice was approximately half of that in wild-type mice. Conversely, behavioral analyses in heterozygous Relndel mice without cerebellar atrophy or dysplasia showed abnormal social novelty in the three-chamber social interaction test. In vitro reaggregation formation and neuronal migration were severely altered in the cerebellar cultures of homozygous Reln-del mice. Conclusion:The present results in novel Reln-del mice modeled after our patient with a novel exonic deletion in RELN are expected to contribute to the development of reelin-based therapies for schizophrenia.Reelin is a large extracellular matrix protein expressed in many brain regions. 1 During developmental stages, reelin is secreted primarily by Cajal-Retzius cells and plays a crucial role in neuronal migration and layer formation in the cerebral cortex 2,3 ; it is also required in cerebellar development. 4 In the adult brain, reelin is produced by GABAergic interneurons and contributes to synaptic plasticity, dendritic morphology, and cognitive function. [5][6][7] Previous studies reported lissencephaly and cerebellar hypoplasia in patients carrying RELN mutations; this phenotype is similar to that observed in reeler mice. 8,9 The full-length reelin protein is approximately 400 kDa in size, with eight repeated domains known as reelin repeats and is cleaved by proteases, such as disintegrin and metalloproteinase, with thrombospondin motifs 3 at two specific sites 10 : one site between reelin repeats 2 and 3 (N-t site) and another site between reelin repeats 6 and 7 (C-t site). In previous studies, two Reln-mutant mice were used to evaluate reelin function. Jackson Reln homozygous mice (Relnrl-J) have a 150-kB genomic deletion, whereas Orleans Reln homozygous mice (Relnrl-Orl) produce a transcript with a 220-bp deletion. 11,12 Reelin protein is not produced in Relnrl-J mice, 5 whereas Relnrl-Orl mice produce a non-secreting protein partially cleaved at the C-terminal. [13][14][15] Little reelin signaling induced reversed cortical layering and cerebellar atrophy in both Relnrl-J and Relnrl-Orl mice. Furthermore, heterozygous Relnrl-J (Relnrl-J/+) mice showed memory...

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