Reproductive Specializations in a Viviparous African Skink: Implications for Evolution and Biological Conservation

Recent research on the African scincid lizard, Trachylepis ivensi, has significantly expanded the range of known reproductive specializations in reptiles. This species is viviparous and exhibits characteristics previously thought to be confined to therian mammals. In most viviparous squamates, females ovulate large yolk-rich eggs that provide most of the nutrients for development. Typically, their placental components (fetal membranes and uterus) are relatively unspecialized, and similar to their oviparous counterparts. In T. ivensi, females ovulate tiny eggs and provide nutrients for embryonic development almost entirely by placental means. Early in gestation, embryonic tissues invade deeply into maternal tissues and establish an intimate “endotheliochorial” relationship with the maternal blood supply by means of a yolk sac placenta. The presence of such an invasive form of implantation in a squamate reptile is unprecedented and has significant functional and evolutionary implications. Discovery of the specializations of T. ivensiillustrates why the study of a few convenient “animal models” is no substitute for broad-based studies of biological diversity as directed by phylogenetic considerations. Our study also underscores the value of museum collections to studies of biological diversity

Cognitive Performance of Users Is Affected by Electronic Handovers Depending on Role, Task and Human Factors

Patient handovers are cognitively demanding, crucial for information continuity and patient safety, but error prone. This study investigated the effect of an electronic handover tool, i.e. the handoverEHR, on the memory and care planning performance of nurse students (n=32) in a randomised, controlled cross-over design with the factors handover task and handover role. On a descriptive level, handover recipients could improve their memory performance with electronic support, handover givers their performance of writing care plans. Statistically meaningful differences occurred, however, only when the participants were givers. Without handover experience and with low fluency to word problems, givers performed badly in the most demanding of the handover tasks. Final recommendations, however, can only be made after replicating this study in a clinical setting with mixed groups

Regenwurmforscher auf Marsmission: Originale Begegnung und Experimentieren im Biologieunter-richt der Unterstufe

Der folgende Beitrag stellt nach einer thematischen Einführung die ersten beiden Doppelstunden der Unterrichtseihe „Regenwurmforscher auf Marsmission“ vor. In dieser Unterrichtsreihe wird den Schülerinnen und Schülern selbst die Forscherrolle übertragen. In der ersten Doppelstunde wird dabei zunächst Fachwissen zur Biologie des Regenwurms, zu den Methoden der Erkenntnisgewinnung, zum Forschungsprozess und zum zugehörigen Forschungskontext erarbeitet. Als Forschungskontext dient ein aktuelles Projekt der Marsforschung, den Boden auf dem Mars mithilfe von Regenwürmern fruchtbar machen zu können, damit dort Nahrungs- und Nutzpflanzen angebaut werden könnten. Um die Eignung der Regenwürmer in diesem Kontext praktisch zu prüfen, liegt der Schwerpunkt der zweiten Doppelstunde auf der Methode des Experimentierens. Versuche mit dem Modellorganismus Dendrobena veneta werden dabei eigenständig durchgeführt und ausgewertet. Die vorgestellten Versuche dieses Artikels beinhalten in diesem Zusammenhang u.a. das Herstellen eines eigenen „Marsterrariums“ zur Langzeitbeobachtung und eine Reihe von Experimenten zu den Themen Atmungsorgan der Regenwürmer sowie Temperaturempfinden und Fortbewegung der Regenwürmer

Ultrasound-triggered antibiotic release from PEEK clips to prevent spinal fusion infection: Initial evaluations.

Despite aggressive peri-operative antibiotic treatments, up to 10% of patients undergoing instrumented spinal surgery develop an infection. Like most implant-associated infections, spinal infections persist through colonization and biofilm formation on spinal instrumentation, which can include metal screws and rods for fixation and an intervertebral cage commonly comprised of polyether ether ketone (PEEK). We have designed a PEEK antibiotic reservoir that would clip to the metal fixation rod and that would achieve slow antibiotic release over several days, followed by a bolus release of antibiotics triggered by ultrasound (US) rupture of a reservoir membrane. We have found using human physiological fluid (synovial fluid), that higher levels (100–500 μg) of vancomycin are required to achieve a marked reduction in adherent bacteria vs. that seen in the common bacterial medium, trypticase soy broth. To achieve these levels of release, we applied a polylactic acid coating to a porous PEEK puck, which exhibited both slow and US-triggered release. This design was further refined to a one-hole or two-hole cylindrical PEEK reservoir that can clip onto a spinal rod for clinical use. Short-term release of high levels of antibiotic (340 ± 168 μg), followed by US-triggered release was measured (7420 ± 2992 μg at 48 h). These levels are sufficient to prevent adhesion of Staphylococcus aureus to implant materials. This study demonstrates the feasibility of an US-mediated antibiotic delivery device, which could be a potent weapon against spinal surgical site infection. Statement of Significance: Spinal surgical sites are prone to bacterial colonization, due to presence of instrumentation, long surgical times, and the surgical creation of a dead space (≥5 cm 3 ) that is filled with wound exudate. Accordingly, it is critical that new approaches are developed to prevent bacterial colonization of spinal implants, especially as neither bulk release systems nor controlled release systems are available for the spine. This new device uses non-invasive ultrasound (US) to trigger bulk release of supra-therapeutic doses of antibiotics from materials commonly used in existing surgical implants. Thus, our new delivery system satisfies this critical need to eradicate surviving bacteria, prevent resistance, and markedly lower spinal infection rates

Local diversity of heathland Cercozoa explored by in-depth sequencing

Cercozoa are abundant free-living soil protozoa and quantitatively important in soil food webs; yet, targeted high-throughput sequencing (HTS) has not yet been applied to this group. Here we describe the development of a targeted assay to explore Cercozoa using HTS, and we apply this assay to measure Cercozoan community response to drought in a Danish climate manipulation experiment (two sites exposed to artificial drought, two unexposed). Based on a comparison of the hypervariable regions of the 18S ribosomal DNA of 193 named Cercozoa, we concluded that the V4 region is the most suitable for group-specific diversity analysis. We then designed a set of highly specific primers (encompassing ~270 bp) for 454 sequencing. The primers captured all major cercozoan groups; and >95% of the obtained sequences were from Cercozoa. From 443 350 high-quality short reads (>300 bp), we recovered 1585 operational taxonomic units defined by >95% V4 sequence similarity. Taxonomic annotation by phylogeny enabled us to assign >95% of our reads to order level and ~85% to genus level despite the presence of a large, hitherto unknown diversity. Over 40% of the annotated sequences were assigned to Glissomonad genera, whereas the most common individually named genus was the euglyphid Trinema. Cercozoan diversity was largely resilient to drought, although we observed a community composition shift towards fewer testate amoebae

Validation of close‐kin mark–recapture (CKMR) methods for estimating population abundance

Under embargo until: 2020-06-181. Knowing how many individuals there are in a population is a fundamental problem in the management and conservation of freshwater and marine fish. We compare abundance estimates (census size, Nc) in seven brook trout Salvelinus fontinalis populations using standard mark–recapture (MR) and the close‐kin mark–recapture (CKMR) method. Our purpose is to validate CKMR as a method for estimating population size. 2. Close‐kin mark–recapture is based on the principle that an individual's genotype can be considered a “recapture” of the genotypes of each of its parents. Assuming offspring and parents are sampled independently, the number of parent–offspring pairs (POPs) genetically identified in these samples can be used to estimate abundance. We genotyped (33 microsatellites) and aged c. 2,400 brook trout individuals collected over 5 consecutive years (2014–2018). 3. We provide an alternative interpretation of CKMR in terms of the Lincoln– Petersen estimator in which the parents are considered as tagging the offspring rather than the offspring “recapturing” the parents. 4. Despite various sources of uncertainty, we find close agreement between standard MR abundance estimates obtained through double‐pass electrofishing and CKMR estimates, which require information on age‐specific fecundity, and population‐ and age‐specific survival rates. Population sizes (N) are estimated to range between 300 and 6,000 adult individuals. Our study constitutes the first in situ validation of CKMR and establishes it as a useful method for estimating population size in aquatic systems where assumptions of random sampling and thorough mixing of individuals can be met.acceptedVersio