Dynamics of skeleton formation in the Lake Baikal sponge Lubomirskia baicalensis. Part I. Biological and biochemical studies

In ancient Lake Baikal (East Siberia), freshwater sponges have diversified to an extraordinary degree. The skeleton of Lubomirskia baicalensis, which attains a size of up to 1 m, is constructed from spicules, which are cemented into longitudinal bundles. Our X-ray analysis revealed that the architecture of the specimens follows a highly ordered radiate accretive growth pattern. The spicules have a central axial canal with an axial filament inside. This organic filament is composed of silicatein, the major enzyme involved in silica formation of the spicules. We found that the specific activity of silicatein in samples from the non-growing (basal) zone is much lower than in those from the growth zone (tips) and that even the composition of this molecule differs in these regions. The present study shows for the first time that the turnover of silicatein, the major element of the axial canal of sponge spicules, changes within a sponge specimen depending on the region in which it is found.     

A portable fiber-optic chemical device for the quantitative determination of carbon monoxide from automobile exhaust emissions

A colorimetric method for the quantitative determination of CO by diffuse reflectance is described. This method is based on the reduction by CO of Mo (VI) from the indicator reagent molybdosilicic acid (H8Si[Mo2O7]6). The reduction yielded a change of color from clear yellow to dark green on white disk filter chart paper wetted with reagent indicator solution. The gaseous mixture containing CO was forced to pass through this chart paper, initiating the reaction. The intensity of the color produced, measured by diffuse reflectance, was proportional to the CO concentration present in exhaust gases in the range from 0.02 to 12% volume/volume (v/v). A 650-nm light-emitting diode was used as a light source. A two-fiber-optic system carried the light from the source to the detection system, which was composed of a photodiode, an amplification circuit, and a digital display. The method was applied with success in field measurements for automobiles in the Otto cycle. In a previous paper, this method was used for the quantitative determination of exhaust emissions from diesel-fueled vehicles.     

The future of sustainability in the context of COVID-19

The COVID-19 pandemic is a global crisis emanating both from a virus (SARS-CoV-2) and from the drastic actions to contain it. Here, we reflect on the immediate responses of most world powers amid the pandemic chaos: totalitarian surveillance and nationalist isolation. Drawing on published literature, we consider measures such as wildlife-use bans, lockdowns and travel restrictions, along with their reverberations for people, economies and the planet. Our synthesis highlights significant shortfalls of applying command-and-control tactics in emergencies. For one, heavy-handed bans risk enormous unintended consequences and tend to fail if they lack legitimacy or clash with people’s values. Furthermore, reactive and myopic strategies typically view the pandemic as a stand-alone crisis, rather than unravelling the complex interplay of nature-society interactions through which zoonotic diseases originate. A return to adaptive management approaches that recognise root causes and foster socio-ecological resilience will be essential to improve human and planetary health and mitigate future pandemics.     

Phytotoxicity of short-term exposure to excess zinc or copper in Scots pine seedlings in relation to growth,water status,nutrient balance,and antioxidative activity

The toxic effects of heavy metals pose a significant threat to the productivity and stability of forest ecosystems. Changes in the agrochemical properties of polluted forest soils due to global climate changes can increase the bioavailability of previously immobilized heavy metals. To test this hypothesis, we studied the effects of short-term shock exposure to ZnSO₄ (50, 150, 300 μM) or CuSO₄ (2.5, 5, 10 μM) in hydroculture on 4- to 6-week-old seedlings of Scots pine (Pinus sylvestris L.) with well-developed root systems. The effects of the excess heavy metals on mineral nutrients and the functioning of low-molecular-weight antioxidants and glutathione in protecting plants from oxidative damage were studied. Even short-term exposure to exogenous metals led to their rapid accumulation in the root system and their subsequent transport to aboveground organs. An increase in the 4-hydroxyalkenals content in seedling needles exposed to excess Cu led to an increase in the content of proanthocyanidins and catechins, which act as scavengers of reactive oxygen species. The impact of both metals led to the rapid development of mineral nutrient imbalances in the seedlings, which were most pronounced in the presence of excess Zn. Exposure to excess Zn led to a disruption in the translocation of Fe and a decrease in the Fe content in the needles. The most dramatic consequence of Zn exposure was the development of Mn deficiency in the roots, which was the likely cause of the inhibition of phenolic compound synthesis. A deficiency in phenolic compounds can have serious environmental consequences for pine populations that are at risk of contamination by Zn and Cu salts.

     

Optimisation of zeolite LTA synthesis from alum sludge and the influence of the sludge source

Generation of alum sludge (AS) at drinking water treatment plants represents an environmental liability and adds to the cost of water purification. Consequently, this study explored the feasibility of using low and high carbon containing alum sludge from two water treatment plants to synthesize zeolite LTA. The hypothesis was that zeolite LTA synthesis was dependant upon alum sludge source and that a range of strategies may be required to optimize zeolite crystallinity. Zeolite characteristics such as morphology, phase composition, crystallinity, and particle size distribution were recorded. “One pot” hydrothermal synthesis of precursor gel with molar composition 4.2Na₂O:Al₂O₃:1.2SiO₂:168H₂O at 80°C for 3 hr resulted in 25 and 46 wt.% zeolite LTA from high and low carbonaceous sludge, respectively. Prior to hydrothermal reaction stage it was discovered that ageing of the gel, addition of zeolite LTA seeds, ultrasonic treatment and calcination all promoted zeolite LTA formation. Calcination of the alum sludge at 700°C for 2 hr before hydrothermal synthesis resulted in particle size reduction and the highest amount of crystalline zeolite LTA: 79 wt.% from low carbon sludge and 65 wt.% from high carbon sludge. Notably, the zeolite crystallinity reported in this study was the higher than previous studies on this topic. The outlined approach may allow value adding of alum waste and produce a commodity which could be used locally by the water treatment plant as a water softener.     

Monohalogenated acetamide-induced cellular stress and genotoxicity are related to electrophilic softness and thiol/thiolate reactivity

Haloacetamides(HAMs) are cytotoxic, genotoxic, and mutagenic byproducts of drinking water disinfection. They are soft electrophilic compounds that form covalent bonds with the free thiol/thiolate in cysteine residues through an S_N2 reaction mechanism.Toxicity of the monohalogenated HAMs(iodoacetamide, IAM; bromoacetamide, BAM;or chloroacetamide, CAM) varied depending on the halogen substituent. The aim of this research was to investigate how the halogen atom affects the reactivity and toxicological properties of HAMs, measured as induction of oxidative/electrophilic stress response and genotoxicity. Additionally, we wanted to determine how well in silico estimates of electrophilic softness matched thiol/thiolate reactivity and in vitro toxicological endpoints.Each of the HAMs significantly induced nuclear Rad51 accumulation and ARE signaling activity compared to a negative control. The rank order of effect was IAM BAM CAM for Rad51, and BAM ≈ IAM CAM for ARE. In general, electrophilic softness and in chemico thiol/thiolate reactivity provided a qualitative indicator of toxicity, as the softer electrophiles IAM and BAM were more thiol/thiolate reactive and were more toxic than CAM.     

Male wing color properties predict the size of nuptial gifts given during mating in the Pipevine Swallowtail butterfly (Battus philenor)

In many animals, males bear bright ornamental color patches that may signal both the direct and indirect benefits that a female might accrue from mating with him. Here we test whether male coloration in the Pipevine Swallowtail butterfly, Battus philenor, predicts two potential direct benefits for females: brief copulation duration and the quantity of materials the male passes to the female during mating. In this species, males have a bright iridescent blue field on the dorsal hindwing surface, while females have little or no dorsal iridescence. Females preferentially mate with males who display a bright and highly chromatic blue field on their dorsal hindwing. In this study, we show that the chroma of the blue field on the male dorsal hindwing and male body size (forewing length) significantly predict the mass of material or spermatophore that a male forms within the female’s copulatory sac during mating. We also found that spermatophore mass correlated negatively with copulation duration, but that color variables did not significantly predict this potential direct benefit. These results suggest that females may enhance the material benefits they receive during mating by mating with males based on the coloration of their dorsal hindwing.