Resilience of soil seed banks to site degradation in intermittently flooded riverine woodlands

Questions: (1) What is the recovery potential of soil seed banks of intact, average and degraded floodplain woodlands? (2) Will soil seed banks of different functional groups (native and exotic, dryland and wetland) display contrasting responses to site degradation? Location: Semi‐arid, seasonally flooded woodland of eastern Australia. Methods: Diversity, abundance and composition of soil seed banks were assessed using a glasshouse study. Surface soil samples were taken from a total of nine sites with three levels of degradation (intact, average, degraded) from three microsites (sub‐canopy, canopy edge, open). Results: A total of 26 662 individuals of 82 species germinated. Seed abundance increased tenfold from intact to degraded sites, but there was no effect on richness. Species composition of all functional groups varied significantly among degradation states. Seeds of native wetland and exotic dryland species were more abundant in degraded than in intact sites. However, the abundance of native dryland germinants did not differ among degradation classes and no seeds of exotic wetland species were observed. Richness of exotic dryland species was significantly higher in degraded sites. Conclusions: Increasing disturbance promoted seed banks of exotic but not native dryland species and native but not exotic wetland species. Unexpectedly, disturbance promoted the abundance of native seeds more than exotics, although this was driven by a single species. Our results suggest that the dryland phase of the floodplain community is more resilient to degradation than predicted.     

How to Use Secondary Data on Seafood Contamination for Probabilistic Exposure Assessment Purposes? Main Problems and Potential Solutions

Seafood consumption is related to both favorable health benefits of nutrients and to potential adverse health impacts of chemical contamination. To quantify the magnitude of this dilemma, probabilistic intake assessments can be performed. One step in such a procedure involves the determination of nutrient and contaminant concentrations in seafood for which data need to be collected. This article describes the process of building up a database containing previously published contaminant concentrations in seafood, and defining input distributions characterizing the variability. During the constitution of the database, several problems influencing the comparability of the data were encountered related to (1) sampling plans of the published data; (2) sample handling prior to analysis; (3) analytical methodologies; (4) the format of reporting results; and (5) missing data. Different solutions for these methodological problems have been developed. Contaminant concentrations ranges per gram fresh weight of 2.4–4390.0 ng for mercury, 0.1–5736.6 ng for the sum of indicator PCB, 0.002–115.000 pg TEQ for the sum of all PCBs, 0.002–34.400 pg TEQ for dioxins, and 0.006–126.000 pg TEQ for total of dioxin-like compounds were found. This work confirms that more guidelines are needed to standardize the analytical methodologies to be used and the format for result reporting in order to improve the comparability of data critical to conduct a human intake and risk-benefit assessment.     

Glutamate receptor binding in insects and mammals

Summary High affinity stereospecific binding sites for L-glutamate have been reported in several regions of mammalian brain. The binding sites in the hippocampus and cerebellum have been studied more extensively than binding in other brain regions. The hippocampal and cerebellar binding sites show similar properties with respect to their pharmacology and their independence of Na⁺. There is evidence, particularly good in the case of hippocampus, of mechanisms that may regulate the availability of the binding sites in both brain areas. Some progress has been made with the isolation of the hippocampal binding site but the protein has not been extensively characterised.In the case of insect muscle, high-affinity stereospecific binding of L-glutamate to whole membrane preparations, to detergent-solubilised membranes and to isolated proteolipids has been reported. Much greater variability in the binding characteristics is seen than is the case with the mammalian brain preparations. Preliminary experiments suggest that at least four distinct binding sites may be present on insect muscle.The complete characterisation of glutamate binding sites is at present precluded by a lack of potent agonists and antagonists. However, recent advances in the pharmacological classification of receptor sites for the excitatory amino acids in mammalian brain could provide sufficient information to permit the identification of the binding sites as synaptic receptors. Invertebrate toxins whose site of action is the insect neuromuscular junction may well prove to be useful tools with which to isolate and characterise the synaptic receptor proteins.     

Effectiveness of intrapartum fetal surveillance to improve maternal and neonatal outcomes: a systematic review and network meta-analysis

BACKGROUND:Cesarean delivery is the most common surgical procedure worldwide. Intrapartum fetal surveillance is routinely offered to improve neonatal outcomes, but the effects of different methods on the risk of emergency cesarean deliveries remains uncertain. We conducted a systematic review and network meta-analysis to evaluate the effectiveness of different types of fetal surveillance.METHODS:We searched MEDLINE, Embase and CENTRAL until June 1, 2020, for randomized trials evaluating any intrapartum fetal surveillance method. We performed a network meta-analysis within a frequentist framework. We assessed the quality and network inconsistency of trials. We reported primarily on intrapartum emergency cesarean deliveries and other secondary maternal and neonatal outcomes using risk ratios (RRs) and 95% confidence intervals (CIs).RESULTS:We included 33 trials (118 863 patients) evaluating intermittent auscultation with Pinard stethoscope/handheld Doppler (IA), cardiotocography (CTG), computerized cardiotocography (cCTG), CTG with fetal scalp lactate (CTG-lactate), CTG with fetal scalp pH analysis (CTG-FBS), CTG with fetal pulse oximetry (FPO-CTG), CTG with fetal heart electrocardiogram (CTG-STAN) and their combinations. Intermittent auscultation reduced the risk of emergency cesarean deliveries compared with other types of surveillance (IA v. CTG: RR 0.83, 95% CI 0.72–0.97; IA v. CTG-FBS: RR 0.71, 95% CI 0.63–0.80; IA v.CTG-lactate: RR 0.77, 95% CI 0.64–0.92; IA v. FPO-CTG: RR 0.75, 95% CI 0.65–0.87; IA v.FPO-CTG-FBS: RR 0.81, 95% CI 0.67–0.99; cCTG-FBS v. IA: RR 1.21, 95% CI 1.04–1.42), except STAN-CTG-FBS (RR 1.17, 95% CI 0.98–1.40). There was a similar reduction observed for emergency cesarean deliveries for fetal distress. None of the evaluated methods was associated with a reduced risk of neonatal acidemia, neonatal unit admissions, Apgar scores or perinatal death.INTERPRETATION:Compared with other types of fetal surveillance, intermittent auscultation seems to reduce emergency cesarean deliveries in labour without increasing adverse neonatal and maternal outcomes.

Cesarean delivery is the most common surgical procedure worldwide, performed to expedite delivery and avoid neonatal complications. Fetal surveillance is routinely offered to patients in labour to reduce the risk of adverse neonatal outcomes, as well as the risk of unnecessary emergency cesarean deliveries and other maternal interventions. Fetal surveillance aims to detect intrapartum hypoxia from acute or subacute adverse events in labour requiring medical intervention and to reduce the risk of serious complications such as neonatal cerebral palsy, hypoxic–ischemic encephalopathy or stillbirth.Monitoring the fetal heart rate to detect intrapartum hypoxia using simple surveillance techniques, such as the Pinard stethoscope, has been practised for decades.¹ Over the last 50 years, several newer surveillance methods have been evaluated, with varied uptake in practice.² Cardiotocography (CTG) remains the most common surveillance method used in high-risk pregnancies.³ However, given its limited accuracy, many researchers have evaluated its use in combination with other surveillance methods, such as fetal heart electrocardiogram (STAN), fetal scalp pH analysis (FBS) or fetal pulse oximetry (FPO), and with computer-aided decision models (cCTG) to improve its diagnostic value.^4–6 Despite extensive investment in clinical research, the overall effectiveness of such methods in improving maternal and neonatal outcomes remains debatable as stillbirth rates have plateaued worldwide, while cesarean delivery rates continue to rise.^7,8Existing meta-analyses evaluating different intrapartum fetal surveillance methods remain limited to head-to-head comparisons of monitoring techniques, without a comprehensive assessment of their effectiveness in improving maternal and neonatal pregnancy outcomes.^4,9–13 We conducted a systematic review of randomized trials and a network meta-analysis to evaluate the effectiveness of all available fetal surveillance methods in improving maternal and neonatal outcomes.     

Can hay harvesting detrimentally affect adult butterfly abundance?

Butterfly transects were carried out in the meadows and tracks of a 1.5 × 1.6 km study area in the Cantabrian section of the Picos de Europa, Spain to examine the impact of hay harvesting on adult butterfly numbers. Overall butterfly numbers significantly decreased between transect counts taken before and after harvesting in cut fields; no such decline was evident in fields without active management (harvesting/grazing) over the same period. Family-level analysis showed hay harvesting to significantly impact on the Satyridae but not other groups. In fields not undergoing active management no Family-level declines were evident, but the Lycaenidae significantly increased in abundance over the same period. Butterfly abundance on tracks surrounding the meadows significantly decreased during the hay harvest period, but this was not reflected in significant decreases in any particular Family group. The results are discussed in relation to the time of harvesting during the day, and socioeconomic changes in extensive pastoral landscapes.     

The β-Subunit of Caenorhabditis elegans Avermectin Receptor Responds to Glycine and Is Encoded by Chromosome 1

Abstract: A full-length cDNA encoding the β subunit of the recently described avermectin receptor was amplified from Caenorhabditis elegans mRNA. When this cDNA was injected into Xenopus oocytes a dose-dependent response to glycine was observed, together with a smaller response to 1 m M GABA. The EC₅₀ of the glycine response was similar to that described previously for glutamate (0.38 m M ). Hybridisation of the cDNA to polytene filters identified three yeast artificial chromosome clones that gave a positive signal, Y37B3, Y38E5, and Y24C9, all of which are mapped to chromosome 1. Hybridisation to a series of cosmid clones covering this area further mapped the gene encoding this subunit to the region −2,818 to −2,824.     

Modelling of H2 antagonists and tridimensional modelling of H2 receptor interactions. Part 2

The interactions between the H2 antagonists cimetidine, ranitidine and famotidine with a basic molecular model for the histamine H2 receptor have been analyzed. The calculated potential energies of the antagonist-H2 receptor complexes follow an order consistent with the published binding data, indicating that famotidine is the best H2 receptor ligand. Comparison with the interactions found for histamine and this H2 receptor model suggests that the protonated imiddazole moiety of cimetidine, the dimethylammonio moiety of protonated ranitidine and the protonated guanidinyl moiety of famotidine are bioisosteric with the protonated aliphatic amine group of histamine. Asp 98 in helix 3 appears to be the main residue for antagonist recognition, but some residues in helix 5 may be involved, apparently by serving to guide the antagonist into the binding pocket.