Filter-feeding gelatinous macrozooplankton response to climate change and implications for benthic food supply and global carbon cycle

It is often suggested that gelatinous zooplankton may benefit from anthropogenic pressures of all kinds and in particular from climate change. Large pelagic tunicates, for example, are likely to be favored over other types of macrozooplankton due to their filter-feeding mode, which gives them access to small preys thought to be less affected by climate change than larger preys. In this study, we provide model-based estimate of potential community changes in macrozooplankton composition and estimate for the first time their effects on benthic food supply and on the ocean carbon cycle under two 21st-century climate-change scenarios. Forced with output from an Earth System Model climate projections, our ocean biogeochemical model simulates a large reduction in macrozooplankton biomass in response to anthropogenic climate change, but shows that gelatinous macrozooplankton are less affected than nongelatinous macrozooplankton, with global biomass declines estimated at −2.8% and −3.5%, respectively, for every 1°C of warming. The inclusion of gelatinous macrozooplankon in our ocean biogeochemical model has a limited effect on anthropogenic carbon uptake in the 21st century, but impacts the projected decline in particulate organic matter fluxes in the deep ocean. In subtropical oligotrophic gyres, where gelatinous zooplankton dominate macrozooplankton, the decline in the amount of organic matter reaching the seafloor is reduced by a factor of 2 when gelatinous macrozooplankton are considered (−17.5% vs. −29.7% when gelatinous macrozooplankton are not considered, all for 2100 under RCP8.5). The shift to gelatinous macrozooplankton in the future ocean therefore buffers the decline in deep carbon fluxes and should be taken into account when assessing potential changes in deep carbon storage and the risks that deep ecosystems may face when confronted with a decline in their food source.     

Long-term changes in Noctiluca scintillans blooms along the Chinese coast from 1933 to 2020

Noctiluca scintillans is one of the most common harmful algal species and widely known due to its bioluminescence. In this study, the spatial distribution, seasonal variations, and long-term trends of N. scintillans blooms in China and the related drivers were analyzed and discussed. From 1933 to 2020, a total of 265 events of N. scintillans blooms were recorded in Chinese coastal waters, with a total duration of 1052 days. The first N. scintillans bloom occurred in Zhejiang in 1933, and only three events were recorded before 1980. From 1981 to 2020, N. scintillans caused harmful algal blooms (HABs) almost every year, both the average duration and the proportion of multiphase HABs showed an increasing trend. 1986–1992, 2002–2004, and 2009–2016 were the three peak periods with a frequency of no less than five events of N. scintillans blooms per year. In terms of spatial distribution, N. scintillans blooms spread from the Southeast China Sea to the Bohai Sea after 2000, Guangdong, Fujian, and Hebei were the three provinces with the highest numbers of recorded events of N. scintillans blooms. Moreover, 86.8% of the events of N. scintillans blooms occurred in spring (March, April, and May) and summer (June, July, and August). Among environmental factors, the dissolved inorganic phosphate, dissolved silicate and chemical oxygen demand were significantly correlated with the cell density of N. scintillans during N. scintillans blooms, and most of N. scintillans blooms were recorded in the temperature range of 18.0–25.0°C. Precipitation, hydrodynamics, water temperature, and food availability might be the main factors affecting the spatial–temporal distribution of N. scintillans blooms along the Chinese coast.     

New method for peptide purification based on selective removal of truncation peptide impurities after SPPS with orthogonal capping

Peptide purification by high-performance liquid chromatography (HPLC) is associated with high solvent consumption, relatively large effort and lack of efficient parallelization. As an alternative, many catch-and-release (c&r) purification methods have been developed over the last decades to enable the efficient parallel purification of peptides originating from solid-phase peptide synthesis (SPPS). However, with one exception, none of the c&r systems has been widely established in industry and academia until today. Herein, we present an entirely new chromatography-free purification concept for peptides synthesized on a solid support, termed reactive capping purification (RCP). The RCP method relies on the capping of truncation peptides arising from incomplete coupling of amino acids during SPPS with a reactive tag. The reactive tag contains a masked functionality that, upon liberation during cleavage from the resin, enables straightforward purification of the peptide by incubation with a resin-bound reactive moiety. In this work, two different reactive tags based on masked thiols were developed. Capping with these reactive tags during SPPS led to effective modification of truncated sequences and subsequent removal of the latter by chemoselective reaction with a maleimide-functionalized solid support. By introducing a suitable protecting group strategy, the thiol-based RCP method described here could also be successfully applied to a thiol-containing peptide. Finally, the purification of a 15-meric peptide by the RCP method was demonstrated. The developed method has low solvent consumption, has the potential for efficient parallelization, uses readily available reagents, and is experimentally simple to perform.     

Successful synthesis of a glial-specific blood–brain barrier shuttle peptide following a fragment condensation approach on a solid-phase resin

Successful manual synthesis of the TD2.2 peptide acting as a blood–brain barrier shuttle was achieved. TD2.2 was successfully synthesised by sequential condensation of four protected peptide fragments on solid-phase settings, after several unsuccessful attempts using the stepwise approach. These fragments were chosen to minimise the number of demanding amino acids (in terms of coupling, Fmoc removal) in each fragment that are expected to hamper the overall synthetic process. Thus, the hydrophobic amino acids as well as Arg(Pbf) were strategically spread over multiple fragments rather than having them congested in one fragment. This study shows how a peptide that shows big challenges in the synthesis using the common stepwise elongation methodology can be synthesised with an acceptable purity. It also emphasises that choosing the right fragment with certain amino acid constituents is key for a successful synthesis. It is worth highlighting that lower amounts of reagents were required to synthesise the final peptide with an identical purity to that obtained by the automatic synthesiser.     

Hectogram-scale synthesis of [Aib8, Arg34]-GLP-1 (7–37) by liquid-phase fragment condensation

Based on small-scale synthesis (0.3 g), a 100-g scale-up synthesis of crude [Aib⁸, Arg³⁴]-glucagon-like peptide-1 (GLP-1) (7–37) was completed. The crude [Aib⁸, Arg³⁴]-GLP-1 (7–37) was purified using a dynamic axial compression column 200 (DAC-200). Approximately 61 g of [Aib⁸, Arg³⁴]-GLP-1 (7–37) with a purity of >99% was obtained through one-step reverse-phase chromatography. The purification yield was approximately 92%. The yield from the total reaction was approximately 60%. In summary, we developed an economical and environmentally friendly route to the synthesis and purification of crude [Aib⁸, Arg³⁴]-GLP-1 (7–37), laying a foundation for subsequent industrial production.     

Cyclic dipeptide-based small molecules modulate zinc-mediated liquid–liquid phase separation of tau

Liquid–liquid phase separation (LLPS) is a complex physicochemical phenomenon mediated by multivalent transient weak interactions among macromolecules like polymers, proteins, and nucleic acids. It has implications in cellular physiology and disease conditions like cancer and neurodegenerative disorders. Many proteins associated with neurodegenerative disorders like RNA binding protein FUS (FUsed in Sarcoma), alpha-synuclein (α-Syn), TAR DNA binding protein 43 (TDP-43), and tau are shown to undergo LLPS. Recently, the tau protein responsible for Alzheimer's disease (AD) and other tauopathies is shown to phase separate into condensates in vitro and in vivo. The diverse noncovalent interactions among the biomolecules dictate the complex LLPS phenomenon. There are limited chemical tools to modulate protein LLPS which has therapeutic potential for neurodegenerative disorders. We have rationally designed cyclic dipeptide (CDP)-based small-molecule modulators (SMMs) by integrating multiple chemical groups that offer diverse chemical interactions to modulate tau LLPS. Among them, compound 1c effectively inhibits and dissolves Zn-mediated tau LLPS condensates. The SMM also inhibits tau condensate-to-fibril transition (tau aggregation through LLPS). This approach of designing SMMs of LLPS establishes a novel platform that has potential implication for the development of therapeutics for neurodegenerative disorders.     

Combining industrial ecology tools to assess potential greenhouse gas reductions of a circular economy: Method development and application to Switzerland

Industrial ecology (IE) methodologies, such as input/output or material flow analysis and life cycle assessment (LCA), are often used for the environmental evaluation of circular economy strategies. Up to now, an approach that utilizes these methods in a systematic, integrated framework for a holistic assessment of a geographic region's sustainable circular economy potential has been lacking. The approach developed in this study (IE4CE approach) combines IE methodologies to determine the environmental impact mitigation potential of circular economy strategies for a defined geographic region. The approach foresees five steps. First, input/output analysis helps identify sectors with high environmental impacts. Second, a refined analysis is conducted using material flow and LCA. In step 3, circular strategies are used for scenario design and evaluated in step 4. In step 5, the assessment results are compiled and compared across sectors. The approach was applied to a case study of Switzerland, analyzing 8 sectors and more than 30 scenarios in depth. Carbon capture and storage (CCS) from waste incineration, biogas and cement production, food waste prevention in households, hospitality and production, and the increased recycling of plastics had the highest mitigation potential. Most of the scenarios do not influence each other. One exception is the CCS scenarios: waste avoidance scenarios decrease the reduction potential of CCS. A combination of scenarios from different sectors, including their impact on the CCS scenario potential, led to an environmental impact mitigation potential of 11.9 Mt CO₂-eq for 2050, which equals 14% of Switzerland's current consumption-based impacts.     

Emerging roles of low-molecular-weight thiols at the host–microbe interface

Low-molecular-weight (LMW) thiols are an abundant class of cysteine-derived small molecules found in all forms of life that maintain reducing conditions within cells. While their contributions to cellular redox homeostasis are well established, LMW thiols can also mediate other aspects of cellular physiology, including intercellular interactions between microbial and host cells. Here we discuss emerging roles for these redox-active metabolites at the host–microbe interface. We begin by providing an overview of chemical and computational approaches to LMW-thiol discovery. Next, we highlight mechanisms of virulence regulation by LMW thiols in infected cells. Finally, we describe how microbial metabolism of these compounds may influence host physiology.     

Soil legacy effects of plants and drought on aboveground insects in native and range-expanding plant communities

Soils contain biotic and abiotic legacies of previous conditions that may influence plant community biomass and associated aboveground biodiversity. However, little is known about the relative strengths and interactions of the various belowground legacies on aboveground plant–insect interactions. We used an outdoor mesocosm experiment to investigate the belowground legacy effects of range-expanding versus native plants, extreme drought and their interactions on plants, aphids and pollinators. We show that plant biomass was influenced more strongly by the previous plant community than by the previous summer drought. Plant communities consisted of four congeneric pairs of natives and range expanders, and their responses were not unanimous. Legacy effects affected the abundance of aphids more strongly than pollinators. We conclude that legacies can be contained as soil ‘memories’ that influence aboveground plant community interactions in the next growing season. These soil-borne ‘memories’ can be altered by climate warming-induced plant range shifts and extreme drought.     

Analysis of coupling between optic lobe circadian pacemakers in the cricket Gryllus bimaculatus

The coupling mechanism between weakly coupled two optic lobe circadian pacemakers in the cricket Gryllus bimaculatus was investigated by recording the locomotor activity, under light-dark cycles with various lengths, after the optic nerve was unilaterally severed. The activity rhythm split into two components under the light cycles different from 24 h: one was readily entrained to the light cycle and the other only loosely entrained or freeran. Additional removal of the optic lobe on the intact side resulted in a loss of the entrained component and that on the blinded side caused the reverse effect, indicating that the entrained component was driven by the pacemaker on the intact side and the other by the one on the blinded side. The synchronization between the two components was achieved only in light cycles with a limited length between 23 and 25 h. Without this range, the desynchronization of the components occurred. In the split rhythm, the phase-dependent modulation of the period of freerunning component and the mutual suppression of locomotor activity during the subjective day phase were clearly observed. The suppression was also evident in the lights-on peak that was the masking effect of light. The light cycle with dim light significantly reduced the ratio of animals with the pacemaker coupling as well as the magnitude of the period modulation. These results suggest (1) that the mutual coupling is achieved only when the difference in the periods between the two pacemakers is within an allowable range, (2) that the photic information is also involved in the mechanism of mutual coupling, and (3) that the suppression of activity occurs at the regulatory center for locomotion.Abbreviations CT circadian time - DD constant darkness - LL constant light - LD light to dark cycle - T length of light to dark cycle - freerunning period