Obscurin Maintains Myofiber Identity in Extraocular Muscles.

Purpose: The cytoskeleton of the extraocular muscles (EOMs) is significantly different from that of other muscles. We aimed to investigate the role of obscurin, a fundamental cytoskeletal protein, in the EOMs. Methods: The distribution of obscurin in human and zebrafish EOMs was compared using immunohistochemistry. The two obscurin genes in zebrafish, obscna and obscnb, were knocked out using CRISPR/Cas9, and the EOMs were investigated using immunohistochemistry, qPCR, and in situ hybridization. The optokinetic reflex (OKR) in five-day-old larvae and adult obscna-/-;obscnb-/- and sibling control zebrafish was analyzed. Swimming distance was recorded at the same age. Results: The obscurin distribution pattern was similar in human and zebrafish EOMs. The proportion of slow and fast myofibers was reduced in obscna-/-;obscnb-/- zebrafish EOMs but not in trunk muscle, whereas the number of myofibers containing cardiac myosin myh7 was significantly increased in EOMs of obscurin double mutants. Loss of obscurin resulted in less OKRs in zebrafish larvae but not in adult zebrafish. Conclusions: Obscurin expression is conserved in normal human and zebrafish EOMs. Loss of obscurin induces a myofiber type shift in the EOMs, with upregulation of cardiac myosin heavy chain, myh7, showing an adaptation strategy in EOMs. Our model will facilitate further studies in conditions related to obscurin.

Microbial invasion of the amniotic cavity is associated with impaired cognitive and motor function at school age in preterm children.

BACKGROUND: Chorioamnionitis is an important cause of preterm delivery. Data on neurodevelopmental outcome in exposed infants are inconsistent due to difficulties in diagnosing intrauterine infection/inflammation and lack of detailed long-term follow-up. We investigate cognitive and motor function in preterm infants at early school age and relate the findings to bacteria in amniotic fluid obtained by amniocentesis (microbial invasion of the amniotic cavity (MIAC)) or placenta findings of histological chorioamnionitis (HCA) or fetal inflammatory response syndrome (FIRS). METHOD: Sixty-six infants with gestational age <34 weeks at birth and without major disabilities were assessed using WISC-III and the Bruininks-Oseretsky Test of Motor Proficiency. Results were corrected for gestational age and sex. RESULTS: Children exposed to MIAC had significantly lower scores for full-scale IQ and verbal IQ compared to the non-MIAC group and the difference in full-scale IQ remained after correction for confounding factors. The MIAC group had also significantly lower motor scores after correction. In contrast, motor function was not affected in infants exposed to HCA or FIRS and differences between groups for cognitive scores were lost after corrections. CONCLUSION: Exposure to bacteria in amniotic fluid is associated with lower motor and cognitive scores in school age preterm infants without major disabilities.