Probability of freezing in the freeze-avoiding beetle larvae Cucujus clavipes puniceus (Coleoptera: Cucujidae) from interior Alaska

Silica Aerogels with Self-Reinforced Microstructure for Bioinspired Hydrogels

Aerogel is a kind of high-performance lightweight open-porous solids with ultralow density, high specific surface area, and broad application in many emerging fields including biotechnology, energy, environment, aerospace, etc. A giant challenge remains in preventing of the hydrophilic aerogel framework shrinkage when replacing of solvent with air in its extremely abundant nanosized pores during its fabrication process in ambient conditions. In this work, started from a linear polymeric precursor with further condensation reaction, superhydrophilic silica aerogels with self-reinforced microstructure and the least volume shrinkage have been successfully obtained via ambient pressure drying process without use of any additives in the presence of a low surface tension solvent. The resulting superhydrophilic silica aerogels possess specific surface area up to 1065 m²/g, pore volume up to 2.17 cm³/g and density down to 84 mg/cm³, and these values are comparable to those of their counterparts obtained by supercritical CO₂ drying process. Moreover, as an application demonstration, the bioinspired hydrogels with desirable mechanical flexibility and adhesive performance at extremely harsh environment (e.g., below -50 °C) have been successfully synthesized by mimicking carrier of a functional bioagent with the resulting superhydrophilic silica aerogel microparticles. Our work has made a significant step forward for future high-performance hydrophilic aerogels with self-enhanced microstructures and the resulting superhydrophilic aerogels have shown great potentials in making functional hydrogels with bionic properties.

From Phenology and Habitat Preferences to Climate Change: Importance of Citizen Science in Studying Insect Ecology in the Continental Scale with American Red Flat Bark Beetle, Cucujus clavipes, as a Model Species

Simple Summary

Studies of widely distributed species often are problematic as such research usually needs to engage a lot of time, a large team of field workers, and big financial support before good quality data will be collected. Citizen scientists allow to study different aspects of species biology and ecology with significantly reduced basic operational costs of such studies. Based on the data deposited in the iNaturalist database, we studied the ecology of the American flat bark beetle in the entire area of its species range. The results clearly show high value of citizen science, particularly in studies focused on habitat preferences and phenology in both recognized subspecies of this taxon.

Abstract

The American red flat bark beetle, Cucujus clavipes, is a wide distributed saproxylic species divided into two subspecies: ssp. clavipes restricted to eastern regions of North America and ssp. puniceus occurring only in western regions of this continent. Unique morphological features, including body shape and body coloration, make this species easy to recognize even for amateurs. Surprisingly, except some studies focused on physiological adaptations of the species, the ecology of C. clavipes was almost unstudied. Based on over 500 records collected by citizen scientists and deposited in the iNaturalist data base, we studied phenological activity of adult beetles, habitat preferences and impact of future climate change for both subspecies separately. The results clearly show that spp. clavipes and ssp. puniceus can be characterized by differences in phenology and macrohabitat preferences, and their ranges do not overlap at any point. Spp. clavipes is found as more opportunistic taxon occurring in different forests as well as in urban and agricultural areas with tree vegetation always in elevations below 500 m, while elevational distribution of ssp. puniceus covers areas up to 2300 m, and the beetle was observed mainly in forested areas. Moreover, we expect that climate warming will have negative influence on both subspecies with the possible loss of proper niches at level even up to 47–70% of their actual ranges during next few decades. As the species is actually recognized as unthreatened and always co-occurs with many other species, we suggest, because of its expected future habitat loss, to pay more attention to conservationists for possible negative changes in saproxylic insects and/or forest fauna in North America. In addition, as our results clearly show that both subspecies of C. clavipes differ ecologically, which strongly supports earlier significant morphological and physiological differences noted between them, we suggest that their taxonomical status should be verified by molecular data, because very probably they represent separate species.

Altitudinal variation in bumble bee (Bombus) critical thermal limits

Organism critical thermal limits are often tightly linked to current geographic distribution and can therefore help predict future range shifts driven by changing environmental temperatures. Thermal tolerance of diverse organisms often varies predictably with latitude, with upper thermal limits changing little and lower thermal limits decreasing with latitude. Despite similarly steep gradients in environmental temperatures across altitude, few studies have investigated altitudinal variation in critical thermal limits. We estimated critical thermal minimum (CTmin), critical thermal maximum (CTmax) and recovery temperature (Trec) by tracking righting response of three bumble bee species during thermal ramps: Bombus huntii collected from 2180m asl, and Bombus bifarius and Bombus sylvicola collected from 3290m asl in Wyoming, USA. Overall, larger bees could tolerate more extreme temperatures, likely due to a thermal inertia driven lag between core body temperatures and air temperatures. Despite their smaller size, high altitude bumble bees tolerated colder air temperatures: they had ~1°C lower CTmin and recovered from cold exposure at ~3-4°C lower air temperatures. Conversely, low altitude bees tolerated ~5°C hotter air temperatures. These altitudinal differences in thermal tolerance parallel differences in average daily minimum (1.2°C) and maximum (7.5°C) temperatures between these sites. These results provide one of the few measurements of organism thermal tolerance across altitude and the first evidence for geographical differences in tolerance of temperature extremes in heterothermic bumble bees.

Animal ice-binding (antifreeze) proteins and glycolipids: an overview with emphasis on physiological function

Ice-binding proteins (IBPs) assist in subzero tolerance of multiple cold-tolerant organisms: animals, plants, fungi, bacteria etc. IBPs include: (1) antifreeze proteins (AFPs) with high thermal hysteresis antifreeze activity; (2) low thermal hysteresis IBPs; and (3) ice-nucleating proteins (INPs). Several structurally different IBPs have evolved, even within related taxa. Proteins that produce thermal hysteresis inhibit freezing by a non-colligative mechanism, whereby they adsorb onto ice crystals or ice-nucleating surfaces and prevent further growth. This lowers the so-called hysteretic freezing point below the normal equilibrium freezing/melting point, producing a difference between the two, termed thermal hysteresis. True AFPs with high thermal hysteresis are found in freeze-avoiding animals (those that must prevent freezing, as they die if frozen) especially marine fish, insects and other terrestrial arthropods where they function to prevent freezing at temperatures below those commonly experienced by the organism. Low thermal hysteresis IBPs are found in freeze-tolerant organisms (those able to survive extracellular freezing), and function to inhibit recrystallization – a potentially damaging process whereby larger ice crystals grow at the expense of smaller ones – and in some cases, prevent lethal propagation of extracellular ice into the cytoplasm. Ice-nucleator proteins inhibit supercooling and induce freezing in the extracellular fluid at high subzero temperatures in many freeze-tolerant species, thereby allowing them to control the location and temperature of ice nucleation, and the rate of ice growth. Numerous nuances to these functions have evolved. Antifreeze glycolipids with significant thermal hysteresis activity were recently identified in insects, frogs and plants.

Investigating the deep supercooling ability of an Alaskan beetle, Cucujus clavipes puniceus, via high throughput proteomics

Cucujus clavipes puniceus is a freeze avoiding beetle capable of surviving the long, extremely cold winters of the Interior of Alaska. Previous studies showed that some individuals typically supercool to mean values of approximately -40 °C, with some individuals supercooling to as low as -58 °C, but these non-deep supercooling (NDSC) individuals eventually freeze if temperatures drop below this. However, other larvae, especially if exposed to very cold temperatures, supercool even further. These deep supercooling (DSC) individuals do not freeze even if cooled to -100 °C. In addition, the body water of the DSC larvae vitrifies (turns to a glass) at glass transition temperatures of -58 to -70 °C. This study examines the proteomes of DSC and NDSC larvae to assess proteins that may contribute to or inhibit the DSC trait. Using high throughput proteomics, we identified 138 proteins and 513 Gene Ontology categories in the DSC group and 104 proteins and 573 GO categories in the NDSC group. GO categories enriched in DSC include alcohol metabolic process, cellular component morphogenesis, monosaccharide metabolic process, regulation of biological quality, extracellular region, structural molecule activity, and antioxidant activity. Proteins unique to DSC include alpha casein precursor, alpha-actinin, vimentin, tropomyosin, beta-lactoglobulin, immunoglobulins, tubulin, cuticle proteins and endothelins.