PlexinA3 restricts spinal exit points and branching of trunk motor nerves in embryonic zebrafish

The pioneering primary motor axons in the zebrafish trunk are guided by multiple cues along their pathways. Plexins are receptor components for semaphorins that influence motor axon growth and path finding. We cloned plexinA3 in zebrafish and localized plexinA3 mRNA in primary motor neurons during axon outgrowth. Antisense morpholino knock-down led to substantial errors in motor axon growth. Errors comprised aberrant branching of primary motor nerves as well as additional exit points of axons from the spinal cord. Excessively branched and supernumerary nerves were found in both ventral and dorsal pathways of motor axons. The trunk environment and several other types of axons, including trigeminal axons, were not detectably affected by plexinA3 knock-down. RNA overexpression rescued all morpholino effects. Synergistic effects of combined morpholino injections indicate interactions of plexinA3 with semaphorin3A homologs. Thus, plexinA3 is a crucial receptor for axon guidance cues in primary motor neurons

Is Upright Exploratory Play Influenced by Partial Body Weight Support in Infants with Down Syndrome?

Is Upright Exploratory Play Influenced by Partial Body Weight Support in Infants with Down Syndrome? Sofia Hardin, SPT; Christa Lum, SPT Mentor: Julia Looper, PT, PhD Background: Children with Down syndrome (DS) typically present with delayed gross motor skills, which may negatively impact their development in other realms, such as cognition and language. The partial body-weight supported system (PBWSS) is a possible early intervention for infants with DS in physical therapy settings and in the community to facilitate motor development through exploratory play. Purpose: To explore the effects of a PBWSS on upright play positions during exploratory play among infants with DS. Upright play positions include kneeling, squatting, standing, cruising, supported stepping, and walking. Methods: (N=3). Researchers used a 9x9ft play environment that included the PBWSS and toys. Infants under the age of three attended nine one-hour sessions over the course of three weeks. Infants moved freely within the space and interacted with researchers and present family members. Researchers behavior-coded the first 30 minutes of play for the first and last session with the PBWSS for each infant. Gross motor behaviors were coded for specific motions during the first 2 seconds of every 6 second interval for the duration of the 30 minute play time, totaling to 300 observations. Results: Observations of upright play increased in the last session compared to the first for all three infants, increasing from 33% to 40.67% for infant 1, 15.67% to 49.67% for infant 2 and 39.33% to 47.67% for infant 3. Conclusion: The PBWSS seemed to influence upright play positions during exploratory play for infants with DS and is worth further exploration

Abuse‐Related Post‐Traumatic Stress, Coping, and Tobacco Use in Pregnancy

Objective: To examine the relationship between trauma history, posttraumatic stress disorder (PTSD), coping, and smoking in a diverse sample of pregnant women, some of whom are active smokers. Design: Secondary analysis from a prospective study on PTSD and pregnancy outcomes. Setting: Maternity clinics at three health systems in the midwestern United States. Participants: Women age 18 or older (1,547) interviewed at gestational age fewer than 28 weeks. Methods: Participants were classified at nonsmokers, quitters (stopped smoking during pregnancy), and pregnancy smokers. Demographic, trauma, and pregnancy factors, substance use, and use of tobacco to cope were compared across groups. Logistic regression assessed the influence of these factors on being a smoker versus a nonsmoker and a quitter versus a pregnancy smoker. Results: Smokers differed from nonsmokers on all demographic risk factors (being African American, being pregnant as a teen, having lower income and less education, and living in high‐crime areas), had higher rates of current and lifetime PTSD, and were more likely to report abuse as their worst trauma. Pregnancy smokers had lower levels of education, were more likely to classify their worst trauma as “extremely troubling,” and were more likely to exhibit PTSD hyperarousal symptoms. In regression models, smoking “to cope with emotions and problems” doubled the odds of continuing to smoke while pregnant even after accounting for several relevant risk factors. Conclusion: Smoking behavior in pregnancy may be influenced by the need to cope with abuse‐related PTSD symptoms. Clinicians should consider using trauma‐informed interventions when working with tobacco‐using pregnant women.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/86982/1/j.1552-6909.2011.01261.x.pd

Assays for Eukaryotic Cell Chemotaxis

Microbial interactions influence the productivity and biogeochemistry of the ocean, yet they occur in miniscule volumes that cannot be sampled by traditional oceanographic techniques. To investigate the behaviours of marine microorganisms at spatially relevant scales, we engineered an in situ chemotaxis assay (ISCA) based on microfluidic technology. Here, we describe the fabrication, testing and first field results of the ISCA, demonstrating its value in accessing the microbial behaviours that shape marine ecosystems

PNA microarrays for hybridisation of unlabelled DNA samples

Several strategies have been developed for the production of peptide nucleic acid (PNA) microarrays by parallel probe synthesis and selective coupling of full-length molecules. Such microarrays were used for direct detection of the hybridisation of unlabelled DNA by time-of-flight secondary ion mass spectrometry. PNAs were synthesised by an automated process on filter-bottom microtitre plates. The resulting molecules were released from the solid support and attached without any purification to microarray surfaces via the terminal amino group itself or via modifications, which had been chemically introduced during synthesis. Thus, only full-length PNA oligomers were attached whereas truncated molecules, produced during synthesis because of incomplete condensation reactions, did not bind. Different surface chemistries and fitting modifications of the PNA terminus were tested. For an examination of coupling selectivity, bound PNAs were cleaved off microarray surfaces and analysed by MALDI-TOF mass spectrometry. Additionally, hybridisation experiments were performed to compare the attachment chemistries, with fully acetylated PNAs spotted as controls. Upon hybridisation of unlabelled DNA to such microarrays, binding events could be detected by visualisation of phosphates, which are an integral part of nucleic acids but missing entirely in PNA probes. Overall best results in terms of selectivity and sensitivity were obtained with thiol-modified PNAs on maleimide surfaces