Dysfunctional c<i>nnm2a</i> causes brain abnormalities and increased spontaneous contractions in zebrafish embryos (25 hpf).

<p>(A) Phenotypes in zebrafish embryos untreated (wild-type) or following treatment with <i>cnnm2a</i>-MO (2 ng MO/embryo) or control-MO. Abbreviations indicate the following parts in the zebrafish embryonic brain: M, midbrain; T, tectum; MHB, midbrain-hindbrain boundary; FV, fourth ventricle; and H, hindbrain. (B) Distribution of phenotypes and (C) Mg content (n = 10 per experimental condition) in zebrafish embryos untreated (wild-type) or injected with 2 ng of <i>cnnm2a</i>-MO or control-MO and exposed to a medium with a concentration of Mg²⁺ of 0.33 or 25 mM. Numbers on top of the bars indicate the number of animals in each experimental condition. (D) Restoration of normal brain development by co-injection of <i>cnnm2a</i>-MO (2 ng MO/embryo) with cRNA encoding for wild-type (WT) CNNM2 (50 pg cRNA/embryo), and not by co-injection with cRNA encoding for mutant (MT, p.Glu357Lys) CNNM2 (50 pg cRNA/embryo). (E) Spontaneous contractions in zebrafish embryos untreated (wild-type) or injected with 2 ng of <i>cnnm2a</i>-MO or control-MO and exposed to a medium with a concentration of Mg²⁺ of 0.33 or 25 mM (n = 30 per experimental condition). (F) Restoration of normal spontaneous contraction activity (n = 30 per experimental condition) by co-injection of <i>cnnm2a</i>-MO (2 ng MO/embryo) with cRNA encoding for wild-type (WT) CNNM2 (50 pg cRNA/embryo), and not by co-injection with cRNA encoding for mutant (MT, p.Glu357Lys) CNNM2 (50 pg cRNA/embryo). Data are presented as mean ± SEM. *<i>P</i><0.05 <i>versus</i> wild-type and control. ^#<i>P</i><0.05 <i>versus</i> Mg²⁺-normal (0.33 mM Mg²⁺) medium. Data are presented as mean ± SEM. Different letters indicate significant differences between mean values in experimental groups (<i>P</i><0.05).