Relationships among non-Acremonium sp. fungal endophytes in five grass species.

Many cool-season grasses (subfamily Pooideae) possess maternally transmitted fungal symbionts which cause no known pathology and often enhance the ecological fitness and biochemical capabilities of the grass hosts. The most commonly described endophytes are the Acremonium section Albo-lanosa spp. (Acremonium endophytes), which are conidial anamorphs (strictly asexual forms) of Epichloë typhina. Other endophytes which have been noted are a Gliocladium-like fungus in perennial ryegrass (Lolium perenne L.) and a Phialophora-like fungus in tall fescue (Festuca arundinacea Schreb.). Here, we report the identification of additional non-Acremonium sp. endophytes (herein designated p-endophytes) in three more grass species: Festuca gigantea, Festuca arizonica, and Festuca pratensis. In each grass species, the p-endophyte was cosymbiotic with an Acremonium endophyte. Serological analysis and sequence determinations of variable portions of their rRNA genes indicated that the two previously identified non-Acremonium endophytes are closely related to each other and to the newly identified p-endophytes. Therefore, the p-endophytes represent a second group of widely distributed grass symbionts.     

Agitation,aeration and perfusion modules for cell culture bioreactors

For an optimized bioreactor design which is adapted to the cultivation of sensitive animal cells different modular bioreactor components for gentle agitation, sufficient aeration and long-term perfusion were developed and investigated with respect to their suitability from laboratory to production scale. Aeration systems have been designed for both shear sensitive cells and cells which tolerate bubbles. The systems are based on either membranes for bubble-free aeration or stainless steel sparger systems. They were characterized by determination of their oxygen transfer capacity and optimized in cultivation processes of different cell lines under process conditions such as batch and perfusion mode.Different impellers for suspension cells and cells grown on carriers were investigated for their suitability to ensure homogeneous gentle mixing. A large pitch blade impeller as well as a novel 3-blade segment impeller are appropriate for homogeneous mixing at low shear rates. Especially with the 3-blade segment impeller fluid mechanical stress can be reduced at a given stirrer speed which is advantageous for the cultivation of cells attached to microcarriers or extremely shear sensitive suspension cells. However, our results indicate that shear sensitivity of animal cells has been generally overestimated.Continuous perfusion of both suspension cell cultures and cells cultivated on microcarriers could be successfully performed over extended periods of time using stainless steel spinfilters with appropriate pore sizes and systems based on microporous hydrophilic membranes. Spinfilters are suitable cell retention systems for technical scale bioreactors allowing continuous perfusion cultures of suspension cells (pore size 10 to 20 m) as well as anchorage dependent cells grown on microcarriers (pore size 75 m) over six weeks to 3 months.Applying the developed modules for agitation, aeration and perfusion process adapted bioreactor set-ups can be realized which ensure optimum growth and product formation conditions in order to maximize cell and product yields.     

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     

Seasonal variation of nitrification along a salinity gradient in an urban estuary

A review on salinity adaptation of marine molluscsbased on mainly Russian scientific literature ispresented. The existence of two relativelyindependent systems of adaptation to extreme(resistance level) and moderate (tolerance level)changes of environmental salinity was shown. Theresistance of molluscs is based mainly on an impededwater-salt exchange with the external medium due tomantle cavity hermetization. The tolerance ofmolluscs is determined by cellular mechanisms ofadaptation. Reversible changes of protein and RNAsynthesis, alteration of the pattern of multiplemolecular forms of different enzymes, and theregulation of ionic content and cell volume wereshown to be of importance for the above mentionedmechanisms. The efficiency of resistance andtolerance adaptations to salinity changes may varyin different species and in different colourphenotypes of the same species (intrapopulationalpolymorphism). Parasites (trematodes) may suppressthe resistance of the mollusc-host to extremesalinity changes without effecting the host'scapacity for adaptive changes in salinitytolerance.