Using induced pluripotent stem cells to investigate human neuronal phenotypes in 1q21.1 deletion and duplication syndrome

Copy Number Variation (CNV) at the 1q21.1 locus is associated with a range of neurodevelopmental and psychiatric disorders in humans, including abnormalities in head size and motor deficits. Yet, the functional consequences of these CNVs (both deletion and duplication) on neuronal development remain unknown. To determine the impact of CNV at the 1q21.1 locus on neuronal development, we generated induced pluripotent stem cells from individuals harbouring 1q21.1 deletion or duplication and differentiated them into functional cortical neurons. We show that neurons with 1q21.1 deletion or duplication display reciprocal phenotype with respect to proliferation, differentiation potential, neuronal maturation, synaptic density and functional activity. Deletion of the 1q21.1 locus was also associated with an increased expression of lower cortical layer markers. This difference was conserved in the mouse model of 1q21.1 deletion, which displayed altered corticogenesis. Importantly, we show that neurons with 1q21.1 deletion and duplication are associated with differential expression of calcium channels and demonstrate that physiological deficits in neurons with 1q21.1 deletion or duplication can be pharmacologically modulated by targeting Ca2+ channel activity. These findings provide biological insight into the neuropathological mechanism underlying 1q21.1 associated brain disorder and indicate a potential target for therapeutic interventions

Serotyping of Toxoplasma gondii in cats (Felis domesticus) reveals predominance of type II infections in Germany.

BACKGROUND Cats are definitive hosts of Toxoplasma gondii and play an essential role in the epidemiology of this parasite. The study aims at clarifying whether cats are able to develop specific antibodies against different clonal types of T. gondii and to determine by serotyping the T. gondii clonal types prevailing in cats as intermediate hosts in Germany. METHODOLOGY To establish a peptide-microarray serotyping test, we identified 24 suitable peptides using serological T. gondii positive (n=21) and negative cat sera (n=52). To determine the clonal type-specific antibody response of cats in Germany, 86 field sera from T. gondii seropositive naturally infected cats were tested. In addition, we analyzed the antibody response in cats experimentally infected with non-canonical T. gondii types (n=7). FINDINGS Positive cat reference sera reacted predominantly with peptides harbouring amino acid sequences specific for the clonal T. gondii type the cats were infected with. When the array was applied to field sera from Germany, 98.8% (85/86) of naturally-infected cats recognized similar peptide patterns as T. gondii type II reference sera and showed the strongest reaction intensities with clonal type II-specific peptides. In addition, naturally infected cats recognized type II-specific peptides significantly more frequently than peptides of other type-specificities. Cats infected with non-canonical types showed the strongest reactivity with peptides presenting amino-acid sequences specific for both, type I and type III. CONCLUSIONS Cats are able to mount a clonal type-specific antibody response against T. gondii. Serotyping revealed for most seropositive field sera patterns resembling those observed after clonal type II-T. gondii infection. This finding is in accord with our previous results on the occurrence of T. gondii clonal types in oocysts shed by cats in Germany

In cats infected with non-canonical <i>Toxoplasma gondii</i> strongest reactions were observed against type I/III specific peptides and the number of reactions against these peptides were overrepresented.

<div><p>Intensities (MSIVs) by which non-canonical type-infected cats reacted with individual peptides were analyzed using ANOVA and the Least Significant Difference (LSD)-Post-Hoc-Test (A). To evaluate whether positive or negative serum reactions against clonal type-specific peptide cohorts were over- or underrepresented in cats infected with atypical <i>T. gondii</i>, a log-linear model analysis was used and the results presented in a mosaic plot (B).</p> <p>Detailed explanations of [A] and [B] are already given in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0080213#pone-0080213-g001" target="_blank">Figure 1</a>. </p></div

Naturally <i>Toxoplasma gondii</i> seropositive cats and cats with a known clonal type II infection recognized similar peptide patterns.

<p>To explore whether there are particular patterns of anti-peptide reactions among all serologically positive <i>T. gondii</i> cat sera, a XY-fused Selforganizing Kohonen Network analysis (XYF-SKN) was performed. Figure (A) presents the clustering of various groups of <i>T. gondii</i> positive cat sera in a Y-map. Most of the sera derived from cats infected with non-canonical <i>T. gondii</i> types (A), infected by clonal types I, II or III (I, II, or III), or naturally infected cats (N) clustered in the grid nodes <i>1</i> to <i>8</i> either together (type III- and atypical type-infected [node <i>4</i>] as well as the type II and naturally infected cats [nodes <i>1</i> to <i>3</i> and <i>6</i> to <i>8</i>]) or separately (cats infected with type I <i>T. gondii</i> [node <i>5</i>]). Three cat groups were predicted using XYF-SKN, e.g. a cat group infected with non-canonical and type III <i>T. gondii</i> strains (<i>A</i>), a clonal type I infected group (<i>I</i>) and a naturally-infected cat group (<i>N</i>). Predicted cat groups are presented by different background colours of grid nodes, e. g <b><i>A</i></b> by red, <b><i>I</i></b> by green and <b><i>N</i></b> by blue. Figure (B) shows the number of group-specific sera within predicted clusters (<i>A</i>, <i>I</i> and <i>N</i>), further confirming that sera of naturally infected cats clustered mainly with type II reference sera. Figure (C) shows the number of group-specific sera within eight grid nodes in Figure (A).</p

In <i>Toxoplasma gondii</i> type I-infected cats reactions against type I, I/II and I/III specific peptides are strongest and are overrepresented in number.

<div><p>Intensities (MSIVs) by which clonal type I-infected cats reacted with individual peptides were analyzed using ANOVA and the Least Significant Difference (LSD)-Post-Hoc-Test (A). Whiskers represent 95% confidence intervals of the means of MSIV (bars). The differences between the means of MSIVs were regarded as statistically significant, when they were equal or higher than the LSD values. Different letters above the whiskers indicate significant differences between the mean intensities in the LSD-Post-Hoc-Test. </p> <p>To evaluate whether positive or negative serum reactions against clonal type-specific peptide cohorts were over- or underrepresented in cats infected with <i>T. gondii</i> clonal type I, a log-linear model analysis was used and the results presented in a mosaic plot (B). The size of each box in the mosaic plot corresponds to the observed frequencies of positive (Pos) and negative (Neg) peptide reactions as well as the number of analyzed peptides within each peptide cohort. Pearson residuals represent standardized deviations of observed from expected values. The Pearson residuals 0-2 with solid blue line indicate that the number of positive or negative reactions is higher, but not statistically significantly higher than expected (Pearson chi-squared p-value < 0.1). Blue scale shadings suggest the statistically significant rejection of the null hypothesis, i.e. overrepresentation of reactions against particular peptide groups (Pearson residuals (>2), Pearson chi-squared p-value < 0.05). Dashed red lines indicate an underrepresentation of positive or negative peptide reactions which is not statistically significant. Red scale shadings suggest a statistically significant rejection of the null hypothesis, i.e. underrepresentation of peptide reactions within the analyzed peptide group (Pearson residuals (<-2) Pearson chi-squared p-value, 0.05).</p></div

In naturally <i>Toxoplasma gondii</i> seropositive cats strongest reactions were observed against type II and I/II-specific peptides and reactions against these peptides were overrepresented.

<div><p>Intensities (MSIVs) by which naturally infected cats reacted with individual peptides were analyzed using ANOVA and the Least Significant Difference (LSD)-Post-Hoc-Test (A). To evaluate whether positive or negative serum reactions against clonal type-specific peptide cohorts were over- or underrepresented in naturally <i>T. gondii</i>-infected cats, a log-linear model analysis was carried out and results presented as mosaic plot (B).</p> <p>Detailed explanations of [A] and [B] are already given in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0080213#pone-0080213-g001" target="_blank">Figure 1</a>. </p></div

In a <i>Toxoplasma gondii</i> type III-infected cat type III and I/III specific peptides were recognized strongest and were overrepresented in number.

<div><p>Intensities (MSIVs) by which clonal type III-infected cats reacted with individual peptides were analyzed using ANOVA and the Least Significant Difference (LSD)-Post-Hoc-Test (A). To evaluate whether positive or negative serum reactions against clonal type-specific peptide cohorts were over- or underrepresented in a cat infected with <i>T. gondii</i> clonal type III, a log-linear model analysis was used and the results presented in a mosaic plot (B).</p> <p>Detailed explanations of [A] and [B] are already given in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0080213#pone-0080213-g001" target="_blank">Figure 1</a>. </p></div

In <i>Toxoplasma gondii</i> type II-infected cats reactions against type II and I/II specific peptides are strongest and overrepresented in number.

<div><p>Intensities (MSIVs) by which clonal type II-infected cats reacted with individual peptides were analyzed using ANOVA and the Least Significant Difference (LSD)-Post-Hoc-Test (A). To evaluate whether positive or negative serum reactions against clonal type-specific peptide cohorts were over- or underrepresented in cats infected with <i>T. gondii</i> clonal type II, a log-linear model analysis was used and the results presented in a mosaic plot (B).</p> <p>Detailed explanations of [A] and [B] are provided in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0080213#pone-0080213-g001" target="_blank">Figure 1</a>. </p></div

Caryn Ackerman (Cramer Fish Sciences): Graphical design and layout Data Sources and Credits

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