Temporal Association Between Pulmonary Inflammation and Antioxidant Induction Following Hyperoxic Exposure of the Preterm Guinea Pig

The time course and nature of the pulmonary inflammatory and antioxidant responses, both during and after hyperoxic-induced acute lung injury were studied in the preterm guinea pig. Three-day preterm (65 days gestation) guinea pigs were randomly exposed to either 21% O₂ (control) or 95% O₂ (hyperoxia) for 72 hours. All pups were then maintained in ambient conditions for up to a further 11 days, during which time lung damage was monitored. In animals exposed to hyperoxia, evidence of acute lung injury and inflammation was characterized by a marked increase in microvascular permeability and elevated numbers of neutrophils in bronchoalveolar lavage fluid. Protein concentration, elastase-like activity and elastase-inhibitory capacity in lavage fluid were at a maximum at the end of the 72 hours hyperoxic exposure. Four days later, all values had returned to control levels. In contrast, increased numbers of neutrophils, macrophages and lymphocytes were recovered in the lavage fluid during this early recovery period. Coinciding with the influx of inflammatory cells, there was a significant increase in glutathione peroxidase, manganese superoxide dismutase and catalase activities in immature lung. Lung copper/zinc superoxide dismutase activity remained unchanged during both experimental periods. The strong temporal relationship between the influx of inflammatory cells to the lung and the induction of pulmonary antioxidant enzyme defences suggests that a common mechanism underlies both responses. These findings have led us to regard inflammation in the hyperoxic-injured immature lung as a beneficial event and not, as previously suggested, as part of the injurious process.     

Mapping and monitoring tick (Acari,Ixodida) distribution,seasonality, and host associations in the United Kingdom between 2017 and 2020

Tick-borne disease risk is intrinsically linked to the distribution of tick vector species. To assess risk and anticipate disease emergence, an understanding of tick distribution, host associations, and seasonality is needed. This can be achieved, to some extent, using passive surveillance supported by engagement with the public, animal health, and public health experts. The Tick Surveillance Scheme (TSS) collects data and maps tick distribution across the United Kingdom (UK). Between 2017 and 2020, 3720 tick records were received and 39 tick species were detected. Most records were acquired in the UK, with a subset associated with recent overseas travel. The dominant UK acquired species was Ixodes ricinus (Ixodida: Ixodidae, Linnaeus), the main vector of Lyme borreliosis. Records peaked during May and June, highlighting a key risk period for tick bites. Other key UK species were detected, including Dermacentor reticulatus (Ixodida: Ixodidae, Fabricius) and Haemaphysalis punctata (Ixodida: Ixodidae, Canestrini & Fanzago) as well as several rarer species that may present novel tick-borne disease risk to humans and other animals. Updated tick distribution maps highlight areas in the UK where tick exposure has occurred. There is evidence of increasing human tick exposure over time, including during the COVID-19 pandemic, but seasonal patterns remain unchanged.     

First chromosome scale genomes of ithomiine butterflies (Nymphalidae: Ithomiini): Comparative models for mimicry genetic studies

The ithomiine butterflies (Nymphalidae: Danainae) represent the largest known radiation of Müllerian mimetic butterflies. They dominate by number the mimetic butterfly communities, which include species such as the iconic neotropical Heliconius genus. Recent studies on the ecology and genetics of speciation in Ithomiini have suggested that sexual pheromones, colour pattern and perhaps hostplant could drive reproductive isolation. However, no reference genome was available for Ithomiini, which has hindered further exploration on the genetic architecture of these candidate traits, and more generally on the genomic patterns of divergence. Here, we generated high-quality, chromosome-scale genome assemblies for two Melinaea species, M. marsaeus and M. menophilus, and a draft genome of the species Ithomia salapia. We obtained genomes with a size ranging from 396 to 503 Mb across the three species and scaffold N50 of 40.5 and 23.2 Mb for the two chromosome-scale assemblies. Using collinearity analyses we identified massive rearrangements between the two closely related Melinaea species. An annotation of transposable elements and gene content was performed, as well as a specialist annotation to target chemosensory genes, which is crucial for host plant detection and mate recognition in mimetic species. A comparative genomic approach revealed independent gene expansions in ithomiines and particularly in gustatory receptor genes. These first three genomes of ithomiine mimetic butterflies constitute a valuable addition and a welcome comparison to existing biological models such as Heliconius, and will enable further understanding of the mechanisms of adaptation in butterflies.     

Intra- and interspecific competition and host race formation in the apple maggot fly,Rhagoletis pomonella (Diptera: Tephritidae)

Intra- and interspecific resource competition are potentially important factors affecting host plant use by phytophagous insects. In particular, escape from competitors could mediate a successful host shift by compensating for decreased feeding performance on a new plant. Here, we examine the question of host plant-dependent competition for apple (Malus pumila)- and hawthorn (Crataegus mollis)-infesting larvae of the apple maggot fly, Rhagoletis pomonella (Diptera: Tephritidae) at a field site near Grant, Michigan, USA. Interspecific competition from tortricid (Cydia pomonella, Grapholita prunivora, and Grapholita packardi) and agonoxenid (subfamily Blastodacninae) caterpillars and a curculionid weevil (Conotrachelus crataegi) was much stronger for R. pomonella larvae infesting the ancestral host hawthorn than the derived host apple. Egg to pupal survivorship was estimated as 52.8% for fly larvae infesting hawthorn fruit without caterpillars and weevils compared to only 27.3% for larvae in harthorns with interspecific insects. Survivorship was essentially the same between fly larvae infesting apples in the presence (44.8%) or absence (42.6%) of interspecific insects. Intraspecific competition among maggots was also stronger in hawthorns than apples. The order or time that a larva exited a hawthorn fruit was a significant determinant of its pupal mass, with earlier emerging larvae being heavier than later emerging larvae. This was not the case for larvae in apples, as the order or time that a larva exited an apple fruit had relatively little influence on its pupal mass. Our findings suggest that decreased performance related to host plant chemistry/nutrition may restrict host range expansion and race formation in R. pomonella to those plants where biotic/ecological factors (i.e. escape from competitors and parasitoids) adequately balance the survivorship equation. This balance permits stable fly populations to persist on novel plants, setting the stage for the evolution of host specialization under certain mitigating conditions (e.g. when mating is host specific and host-associated fitness trade-offs exist).     

An improved method to detect β- galactosidase activity in transgenic mice: a post-staining procedure on paraffin embedded tissue sections

The Escherichia coli -galactosidase gene is frequently used as a reporter gene in transgenic studies because its activity can be easily detected at the cellular level. Here we report a procedure for monitoring -galactosidase activity directly in tissue sections, which involves the use of a mixture of ethanol and poly-ethylene-glycol as a fixative (Kryofix) and a special paraffin characterized by a lower fusion point of 42 °C. After embedding and cutting, the sections are stained by the chromogenic substrate 5-bromo-4-chloro-3-indoyl--d galactopyranoside (X-Gal). This procedure allows both the retention of a high level of -galactosidase activity and the preservation of good tissue morphology. Furthermore, it can be combined with immunohistochemical methods to detect other cellular components without compromising reporter gene detection