Evolutionary temperature compensation of carbon fixation in marine phytoplankton

The efficiency of carbon sequestration by the biological pump could decline in the coming decades because respiration tends to increase more with temperature than photosynthesis. Despite these differences in the short-term temperature sensitivities of photosynthesis and respiration, it remains unknown whether the long-term impacts of global warming on metabolic rates of phytoplankton can be modulated by evolutionary adaptation. We found that respiration was consistently more temperature dependent than photosynthesis across 18 diverse marine phytoplankton, resulting in universal declines in the rate of carbon fixation with short-term increases in temperature. Long-term experimental evolution under high temperature reversed the short-term stimulation of metabolic rates, resulting in increased rates of carbon fixation. Our findings suggest that thermal adaptation may therefore have an ameliorating impact on the efficiency of phytoplankton as primary mediators of the biological carbon pump

Paleoclimatic and paleoenvironmental reconstructions based on the small vertebrates from the Middle Paleolithic of Hohle Fels Cave, SW Germany

In this paper, we analyse the fish and small mammal assemblages from the Middle Paleolithic horizons of Hohle Fels Cave to reconstruct the paleoclimatic and paleoenvironmental conditions faced by the Neanderthal groups who occupied the site. The fish assemblage indicates that the freshwater ecosystem around this site was characterized by a pre-mountain river system with the presence of permanent, oxygen-rich, and cold running waters. The results of the Habitat Weighting Method and the Bioclimatic Model applied to the small mammal assemblage, coupled with the new dates obtained for the Archaeological Horizon (AH) IX, allow us to identify two different climatic phases. One phase (AH X-XII) is more temperate possibly corresponding to the end of Marine Isotope Stage (MIS) 5; the other (AH VI-IX) is colder and more arid corresponding to the end of MIS 4 through the beginning of MIS 3. Open environments with a relatively stable forest component dominated the landscape during this part of the Middle Paleolithic. These two climatic phases appear to correspond to different levels of occupational intensity by Neanderthals, with higher occupational intensity during mild climatic periods and lower intensity during cold, arid periods. Our climatic reconstruction and recent absolute dating, together with the recovery of a complete leaf point near the top of AH X, have important implications for the cultural stratigraphy and cultural chronology of the region. Archaeologist have traditionally viewed leaf points as key artefacts of the Blattspitzengruppe, a cultural complex attributed to the end of Middle Paleolithic; however, this stratigraphic, climatic, and chronological context indicates the need to revise this interpretation.info:eu-repo/semantics/publishedVersio

Different carboxyl-rich alicyclic molecules proxy compounds select distinct bacterioplankton for oxidation of dissolved organic matter in the mesopelagic Sargasso Sea

© The Author(s), 2020. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Liu, S., Parsons, R., Opalk, K., Baetge, N., Giovannoni, S., Bolanos, L. M., Kujawinski, E. B., Longnecker, K., Lu, Y., Halewood, E., & Carlson, C. A. Different carboxyl-rich alicyclic molecules proxy compounds select distinct bacterioplankton for oxidation of dissolved organic matter in the mesopelagic Sargasso Sea. Limnology and Oceanography, (2020), doi:10.1002/lno.11405.Marine dissolved organic matter (DOM) varies in its recalcitrance to rapid microbial degradation. DOM of varying recalcitrance can be exported from the ocean surface to depth by subduction or convective mixing and oxidized over months to decades in deeper seawater. Carboxyl‐rich alicyclic molecules (CRAM) are characterized as a major component of recalcitrant DOM throughout the oceanic water column. The oxidation of CRAM‐like compounds may depend on specific bacterioplankton lineages with oxidative enzymes capable of catabolizing complex molecular structures like long‐chain aliphatics, cyclic alkanes, and carboxylic acids. To investigate the interaction between bacteria and CRAM‐like compounds, we conducted microbial remineralization experiments using several compounds rich in carboxyl groups and/or alicyclic rings, including deoxycholate, humic acid, lignin, and benzoic acid, as proxies for CRAM. Mesopelagic seawater (200 m) from the northwest Sargasso Sea was used as media and inoculum and incubated over 28 d. All amendments demonstrated significant DOC removal (2–11 μmol C L−1) compared to controls. Bacterioplankton abundance increased significantly in the deoxycholate and benzoic acid treatments relative to controls, with fast‐growing Spongiibacteracea, Euryarcheaota, and slow‐growing SAR11 enriched in the deoxycholate treatment and fast‐growing Alteromonas, Euryarcheaota, and Thaumarcheaota enriched in the benzoic acid treatment. In contrast, bacterioplankton grew slower in the lignin and humic acid treatments, with oligotrophic SAR202 becoming significantly enriched in the lignin treatment. Our results indicate that the character of the CRAM proxy compounds resulted in distinct bacterioplankton removal rates of DOM and affected specific lineages of bacterioplankton capable of responding.We thank Z. Landry for the inspiring idea of SAR202 catabolism of CRAM. We thank the University of California, Santa Barbara Marine Science Institute Analytical Laboratory for analyzing inorganic nutrient samples. We thank C. Johnson for her help in FISH sample processing and BATS group in supporting our project. We thank N. K. Rubin‐Saika and R. Padula for their help with amino acid sample preparation. We thank Z. Liu, J. Xue, K. Lu, and Y. Shen for their help with amino acid protocol development and validation. We thank B. Stephens for his help on microscopic image analysis. We thank M. Dasenko and the staff of the CGRB at Oregon State University for amplicon library preparation and DNA sequencing. We are grateful for the help provided by the officers and crews of the R/V Atlantic Explorer. Bermuda Institute of Ocean Sciences (BIOS) provides us tremendous support in terms of facilities and lab space. We thank Bermuda government for its allowance of our water sampling and sample export (export permit number SP160904, issued 07 October 2016 under the Fisheries Act, 1972). This project was supported by Simons Foundation International's BIOS‐SCOPE program

The Role of Birds of Prey in West Nile Virus Epidemiology

Reported human cases of West Nile virus (WNV) in Europe increased dramatically in 2018. Lineage 1 strains had been circulating in Euro-Mediterranean countries since the early 1990s. The subsequent introduction of WNV lineage 2 has been responsible for the remarkable upsurge of European WNV outbreaks since 2004, including the dramatic increase in human cases observed since 2018. The virus exists in a natural cycle between mosquitoes and wild birds, with humans and horses acting as dead-end hosts. As the key vertebrate hosts in the transmission cycle of WNV, avian species have been the focus of surveillance across many countries. Raptors appear particularly susceptible to WNV infection, resulting in higher prevalence, and in some cases exhibiting neurological signs that lead to the death of the animal. In addition, birds of prey are known to play an important role as WNV reservoir and potentially amplifying hosts of infection. Importantly, raptor higher susceptibility/prevalence may indicate infection through predation of infected prey. Consequently, they are considered important target species when designing cost-effective surveillance for monitoring both seasonal WNV circulation in endemic countries and its emergence into new areas, where migrating raptors may play a critical role in virus introduction. This review summarizes the different aspects of the current knowledge of WNV infection in birds of prey and evaluates their role in the evolution of the epizootic that is spreading throughout Europe

First Comparative Study of the Three Polymorphs of Bis(isonicotinamide) Citric Acid Cocrystals and the Concomitant Salt 4‑Carbamoylpyridinium Citrate Isonicotinamide

This contribution presents a previously unreported example and comparative study of a binary crystalline adduct that exhibits concomitant salt and cocrystal forms. Specifically, three new polymorphs (α, β, γ) of a novel 2:1 cocrystal of bis(isonicotinamide) citric acid are reported, and the route to isolating each polymorph from aqueous solution is presented and the crystal chemistry of the system is characterized. In addition, the metastable 2:1 salt (ionic adduct) isolated as a transient (overlapping) phase under crystallization conditions identical to the polymorphs is also presented. As far as the authors can ascertain, this may be the first reported example of a salt−cocrystal−polymorphic concomitant system. A comparative study of the solid form landscape is presented, wherein mapping reveals the unique structural complexity of this multiple form salt−cocrystal concomitant system. The α and β forms are structurally very similar, where comparisons of packing behavior are shown to only be different outside the glide plane. The γ form is very different in structure, where supramolecular chirality is present. In addition, further characterization of the isolated solid-state forms includes thermal, spectroscopic, and computational analysis, all of which are employed to further verify the solid form landscape of the isonicotinamide−citric acid adduct and were found to have an order of stability of β, α, γ, salt, the salt being the metastable form

First steps for the direct purification of L-Leu-L-Leu dipeptide through co-crystallisation

Trifluoroacetate salt contamination of peptides represents a challenging issue related to solid phase peptide synthesis and purification because it affects the chemical and biological properties of peptides. Purification of such materials is typically performed through a two-step post-synthetic procedure based on chromatography followed by ion exchange. For the first time, co-crystallization is presented in this study as a possible alternative and advantageous single-step method for the obtaining of TFA-free crystals of a dipeptide. A trifluoroacetate-contaminated L-Leu-L-Leu dipeptide has been used for co-crystallization experiments along with different solid coformers. New multicomponent crystals containing only the title compound and the second co-crystal formers are described in this work. Such results represent a novelty in the field of peptide chemistry and a valid proof for the use of crystal engineering-based method for a combined purification and crystallization strategy