Sensory basis for detection of benthic prey in two Lake Malawi cichlids.

The adaptive radiations of African cichlids resulted in a diversity of feeding morphologies and strategies, but the role of sensory biology in prey detection and feeding ecology remains largely unexplored. Two endemic Lake Malawi cichlid genera, Tramitichromis and Aulonocara, feed on benthic invertebrates, but differ in lateral line morphology (narrow and widened lateral line canals, respectively) and foraging strategy. The hypothesis that they use their lateral line systems differently was tested by looking at the relative contribution of the lateral line system and vision in prey detection by Tramitichromis sp. and comparing results to those from a complementary study using Aulonocara stuartgranti (Schwalbe et al., 2012). First, behavioral trials were used to assess the ability of Tramitichromis sp. to detect live (mobile) and dead (immobile) benthic prey under light and dark conditions. Second, trials were run before, immediately after, and several weeks after chemical ablation of the lateral line system to determine its role in feeding behavior. Results show that Tramitichromis sp. is a visual predator that neither locates prey in the dark nor depends on lateral line input for prey detection and is thus distinct from A. stuartgranti, which uses its lateral line or a combination of vision and lateral line to detect prey depending on light condition. Investigating how functionally distinctive differences in sensory morphology are correlated with feeding behavior in the laboratory and determining the role of sensory systems in feeding ecology will provide insights into how sensory capabilities may contribute to trophic niche segregation

Reflections on the Ethical Content of the IT Honours Program Project Module

Part 4: Syllabus DesignInternational audienceHonours programs in South African universities must include a research project module. There are external pressures from professional bodies and government that influences the nature of the project module. This paper presents a reflection on the process of managing the project module at a South African university taking into account internal and external demands. The focus for this paper is on the ethical content of the projects. Examples of projects are presented after which the ethical awareness of the students is discussed. Not all projects have ethical, legal or social issues, however ethical aspects need to be reflected upon and awareness of these issues is essential during the planning of the project. The awareness that students have on ethical, social and legal issues is investigated in this paper

Detection of artificial water flows by the lateral line system of a benthic feeding cichlid fish

The mechanosensory lateral line system of fishes detects water motions within a few body lengths of the source. Several types of artificial stimuli have been used to probe lateral line function in the laboratory, but few studies have investigated the role of flow sensing in benthic feeding teleosts. In this study, we used artificial flows emerging from a sandy substrate to assess the contribution of flow sensing to prey detection in the peacock cichlid, Aulonocara stuartgranti, which feeds on benthic invertebrates in Lake Malawi. Using a positive reinforcement protocol, we trained fish to respond to flows lacking the visual and chemical cues generated by tethered prey in prior studies with A. stuartgranti. Fish successfully responded to artificial flows at all five rates presented (characterized using digital particle image velocimetry), and showed a range of flow-sensing behaviors, including an unconditioned bite response. Immediately after lateral line inactivation, fish rarely responded to flows and the loss of vital fluorescent staining of hair cells (with 4-di-2-ASP) verified lateral line inactivation. Within 2 days post-treatment, some aspects of flow-sensing behavior returned and after 7 days, flow-sensing behavior and hair cell fluorescence both returned to pre-treatment levels, which is consistent with the reported timing of hair cell regeneration in other vertebrates. The presentation of ecologically relevant water flows to assess flow-sensing behaviors and the use of a positive reinforcement protocol are methods that present new opportunities to study the role of flow sensing in the feeding ecology of benthic feeding fishes

Feeding in the dark: lateral-line-mediated prey detection in the peacock cichlid \u3cem\u3eAulonocara stuartgranti\u3c/em\u3e

The cranial lateral line canal system of teleost fishes is morphologically diverse and is characterized by four patterns. One of these, widened lateral line canals, has evolved convergently in a wide range of teleosts, including the Lake Malawi peacock cichlids (Aulonocara), and has been attributed to its role in prey detection. The ability to study Aulonocara in the laboratory provides an opportunity to test the hypothesis that their reported ability to feed on invertebrate prey living in sandy substrates in their natural habitat is the result of lateral-line-mediated prey detection. The goal of this study was to determine whether Aulonocara stuartgranti could detect hydrodynamic stimuli generated by tethered brine shrimp (visualized using digital particle image velocimetry) under light and dark conditions, with and without treatment with cobalt chloride, which is known to temporarily inactivate the lateral line system. Fish were presented with six pairs of tethered live and dead adult brine shrimp and feeding behavior was recorded with HD digital video. Results demonstrate that A. stuartgranti: (1) uses the same swimming/feeding strategy as they do in the field; (2) detects and consumes invertebrate prey in the dark using its lateral line system; (3) alters prey detection behavior when feeding on the same prey under light and dark conditions, suggesting the involvement of multiple sensory modalities; and (4) after treatment with cobalt chloride, exhibits a reduction in their ability to detect hydrodynamic stimuli produced by prey, especially in the dark, thus demonstrating the role of the lateral line system in prey detection

19F-labeling of the adenine H2-site to study large RNAs by NMR spectroscopy

In comparison to proteins and protein complexes, the size of RNA amenable to NMR studies is limited despite the development of new isotopic labeling strategies including deuteration and ligation of differentially labeled RNAs. Due to the restricted chemical shift dispersion in only four different nucleotides spectral resolution remains limited in larger RNAs. Labeling RNAs with the NMR-active nucleus [superscript 19]F has previously been introduced for small RNAs up to 40 nucleotides (nt). In the presented work, we study the natural occurring RNA aptamer domain of the guanine-sensing riboswitch comprising 73 nucleotides from Bacillus subtilis. The work includes protocols for improved in vitro transcription of 2-fluoroadenosine-5′-triphosphat (2F-ATP) using the mutant P266L of the T7 RNA polymerase. Our NMR analysis shows that the secondary and tertiary structure of the riboswitch is fully maintained and that the specific binding of the cognate ligand hypoxanthine is not impaired by the introduction of the [superscript 19]F isotope. The thermal stability of the [superscript 19]F-labeled riboswitch is not altered compared to the unmodified sequence, but local base pair stabilities, as measured by hydrogen exchange experiments, are modulated. The characteristic change in the chemical shift of the imino resonances detected in a 1H,15N-HSQC allow the identification of Watson–Crick base paired uridine signals and the [superscript 19]F resonances can be used as reporters for tertiary and secondary structure transitions, confirming the potential of [superscript 19]F-labeling even for sizeable RNAs in the range of 70 nucleotides.Deutsche Forschungsgemeinschaft (collaborative research center: SFB902

Child mental health in Jordanian orphanages: effect of placement change on behavior and caregiving

Background: To assess the mental health and behavioral problems of children in institutional placements in Jordan to inform understanding of current needs, and to explore the effects of placement change on functioning and staff perceptions of goodness-of-fit. Methods: An assessment was completed of 134 children between 1.5? 12 years-of-age residing in Jordanian orphanages. The Child Behavior Checklist was used to assess prevalence rates of problems across externalizing and internalizing behavior and DSM-IV oriented subscales. Also included was caregiver perceived goodness-of-fit with each child, caregiving behavior, and two placement change-clock variables; an adjustment clock measuring time since last move, and an anticipation clock measuring time to next move. Results: 28% were in the clinical range for the internalizing domain on the CBCL, and 22% for the externalizing domain. The children also exhibited high levels of clinical range social problems, affective disorder, pervasive developmental disorder, and conduct problems. Internalizing problems were found to decrease with time in placement as children adjust to a prior move, whereas externalizing problems increased as the time to their next age-triggered move drew closer, highlighting the anticipatory effects of change. Both behavioral problems and the change clocks were predictive of staff perceptions of goodness-of-fit with the children under their care. Conclusions: These findings add to the evidence demonstrating the negative effects of orphanage rearing, and highlight the importance of the association between behavioral problems and child-caregiver relationship pathways including the timing of placement disruptions and staff perceptions of goodness-of-fit

All-Sky Search for Long-Duration Gravitational Wave Transients in the First Advanced LIGO Observing Run

We present the results of a search for long-duration gravitational wave transients in the data of the LIGO Hanford and LIGO Livingston second generation detectors between and , with a total observational time of . The search targets gravitational wave transients of 10–500 s duration in a frequency band of 24–2048 Hz, with minimal assumptions about the signal waveform, polarization, source direction, or time of occurrence. No significant events were observed. As a result we set 90% confidence upper limits on the rate of long-duration gravitational wave transients for different types of gravitational wave signals. We also show that the search is sensitive to sources in the Galaxy emitting at least  ~10−8 in gravitational waves

Search for Gravitational Waves Associated with Gamma-Ray Bursts During the First Advanced LIGO Observing Run and Implications for the Origin of GRB 150906B

We present the results of the search for gravitational waves (GWs) associated with γ-ray bursts detected during the first observing run of the Advanced Laser Interferometer Gravitational-Wave Observatory (LIGO). We find no evidence of a GW signal for any of the 41 γ-ray bursts for which LIGO data are available with sufficient duration. For all γ-ray bursts, we place lower bounds on the distance to the source using the optimistic assumption that GWs with an energy of ${10}^{-2}{M}_{\odot }{c}^{2}$ were emitted within the $16$–$500$ Hz band, and we find a median 90% confidence limit of 71 Mpc at 150 Hz. For the subset of 19 short/hard γ-ray bursts, we place lower bounds on distance with a median 90% confidence limit of 90 Mpc for binary neutron star (BNS) coalescences, and 150 and 139 Mpc for neutron star–black hole coalescences with spins aligned to the orbital angular momentum and in a generic configuration, respectively. These are the highest distance limits ever achieved by GW searches. We also discuss in detail the results of the search for GWs associated with GRB 150906B, an event that was localized by the InterPlanetary Network near the local galaxy NGC 3313, which is at a luminosity distance of $54$ Mpc (z = 0.0124). Assuming the γ-ray emission is beamed with a jet half-opening angle $\leqslant 30^\circ$, we exclude a BNS and a neutron star–black hole in NGC 3313 as the progenitor of this event with confidence \u3e99%. Further, we exclude such progenitors up to a distance of 102 Mpc and 170 Mpc, respectively