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The Devonian-Carboniferous (D-C; 359 Ma) boundary is marked by widespread deposition of organic-matter-rich black shales associated with the Hangenberg mass extinction event. The Exshaw Formation spans the D-C boundary in the Western Canada Sedimentary Basin (WCSB) and includes the basal Exshaw Shale deposited under broadly anoxic waters. The sediments at the base of the Exshaw Shale were deposited synchronously during a transgressive event across the WCSB, spanning the geographic variability of the basin. The variable Corg content of the shale was affected by local nutrient upwelling and paleotectonic features impacting water depth and circulation. To characterize the link between paleogeography and nutrient cycling, geographic (N = 20 locations) and stratigraphic (N = 6 locations) trends of δ13^^ and δ15^^ were examined throughout the WCSB, representing a range of depositional settings. The δ15^^ values range between 0.0 and 6.3%" and δ13^^ from -29.5 to -26.8%. Phytoplankton production in focused upwelling zones acquired a relatively 15N-depleted signature through isotopic fractionation during nutrient assimilation, and the residual nutrient pool was 15N-enriched. The advection of surface waters away from the location of upwelling supported additional phytoplankton growth and the deposition of sediments with higher δ1^ values. The stratigraphic sections include black laminated and burrowed mudrock sequences that record changes in paleoredox conditions, water depth, and tectonism over time. Up-core from the base of the Exshaw, the Corg content decreases and simultaneously δ15^^ increases, suggesting a decrease in eutrophic conditions. Variable δ13^^ and δ15^^ trends demonstrate that there is no "type" isotopic profile spanning the D-C boundary in the WCSB. [ABSTRACT FROM AUTHOR]

The world-wide prevalence of myopia (nearsightedness) is increasing, but its pathogenesis is incompletely understood. Among many putative mechanisms, laboratory and clinical findings have implicated circadian biology in the etiology of myopia. Consistent with a circadian hypothesis, we recently reported a marked variability in diurnal patterns of gene expression in two crucial tissues controlling post-natal refractive development ‐ the retina and choroid–at the onset of form-deprivation myopia in chick, a widely studied and validated model. To extend these observations, we assayed gene expression by RNA-Seq in retina and choroid during the progression of established unilateral form-deprivation myopia of chick. We assayed gene expression every 4 hours during a single day from myopic and contralateral control eyes. Retinal and choroidal gene expression in myopic vs. control eyes during myopia progression differed strikingly at discrete times during the day. Very few differentially expressed genes occurred at more than one time in either tissue during progressing myopia. Similarly, Gene Set Enrichment Analysis pathways varied markedly by time during the day. Some of the differentially expressed genes in progressing myopia coincided with candidate genes for human myopia, but only partially corresponded with genes previously identified at myopia onset. Considering other laboratory findings and human genetics and epidemiology, these results further link circadian biology to the pathogenesis of myopia; but they also point to important mechanistic differences between the onset of myopia and the progression of established myopia. Future laboratory and clinical investigations should systematically incorporate circadian mechanisms in studying the etiology of myopia and in seeking more effective treatments to normalize eye growth in children. [ABSTRACT FROM AUTHOR]

In recent years, single-cell analyses have revealed the heterogeneity of the tumour microenvironment (TME) at the genomic, transcriptomic, and proteomic levels, further improving our understanding of the mechanisms of tumour development. Single-cell RNA sequencing (scRNA-seq) technology allow analysis of the transcriptome at the single-cell level and have unprecedented potential for exploration of the characteristics involved in tumour development and progression. These techniques allow analysis of transcript sequences at higher resolution, thereby increasing our understanding of the diversity of cells found in the tumour microenvironment and how these cells interact in complex tumour tissue. Although scRNA-seq has emerged as an important tool for studying the tumour microenvironment in recent years, it cannot be used to analyse spatial information for cells. In this regard, spatial transcriptomics (ST) approaches allow researchers to understand the functions of individual cells in complex multicellular organisms by understanding their physical location in tissue sections. In particular, in related research on tumour heterogeneity, ST is an excellent complementary approach to scRNA-seq, constituting a new method for further exploration of tumour heterogeneity, and this approach can also provide unprecedented insight into the development of treatments for pancreatic cancer (PC). In this review, based on the methods of scRNA-seq and ST analyses, research progress on the tumour microenvironment and treatment of pancreatic cancer is further explained. [ABSTRACT FROM AUTHOR]

A novel alphaproteobacterial strain JXJ CY 41T was isolated from a culture mass of Microcystis, collected from Lake Dianchi, south-west, China. Strain JXJ CY 41T was gram-strain-negative, aerobic, motile, with rod-shaped cells (0.4–1.0 × 1.7–3.5 μm). It was positive for catalase and starch hydrolysis, negative for oxidase and hydrolysis of Tweens (20, 40, and 80). Growth occurred at 10–44 °C, pH 5.0–10.0, and 0–5.0% (w/v) NaCl. Major fatty acids included C16:0 (28.1%), 11-methyl C18:1 ω7c (36.7%) and C18:1 ω7c (20.8%). Q10 was the sole ubiquinone. The polar lipids were diphosphatidylglycerol, phosphatidylglycerol, glycolipid, and an unidentified lipid. The DNA G + C content was 63.1%. Its 16S rRNA gene sequence showed high similarities with Devosia oryziradicis G19T (99.5%; not validly published), D. yakushimensis Yak96BT (98.3%) and D. ginsengisoli Gsoil 520T (98.1%), and less than 98.1% similarities with other members of the genus Devosia. The digital DNA-DNA hybridization (dDDH) and average nucleotide identity (ANI) values between strain JXJ CY 41T and its 5 closest similar strains were 19.9–24.1% and 75.7–80.5%, respectively. Based on the data above, strain JXJ CY 41T was identified as a novel species of the genus Devosia, for which the epithet Devosia lacusdianchii sp. nov. was proposed. The type strain is JXJ CY 41T (= KCTC 72812T = CGMCC 1.17502T). Strain JXJ CY 41T exhibited different interactions with Microcystis aeruginosa FACHB-905 (Maf) under different conditions, and Maf could control the bacterial cellular density by secreting unknown specific chemical compounds according to its nutritional requirements. [ABSTRACT FROM AUTHOR]

Studies have suggested that cancerous tissue has a lower 15N/14N ratio than benign tissue. However, human data have been inconclusive, possibly due to constraints on experimental design. Here, we used high-sensitivity nitrogen isotope methods to assess the 15N/14N ratio of human breast, lung, and kidney cancer tissue at unprecedented spatial resolution. In lung, breast, and urothelial carcinoma, 15N/14N was negatively correlated with tumor cell density. The magnitude of 15N depletion for a given tumor cell density was consistent across different types of lung cancer, ductal in situ and invasive breast carcinoma, and urothelial carcinoma, suggesting similar elevations in the anabolism-to-catabolism ratio. However, tumor 15N depletion was higher in a more aggressive metaplastic breast carcinoma. These findings may indicate the ability of certain cancers to more effectively channel N towards growth. Our results support 15N/14N analysis as a potential tool for screening biopsies and assessing N metabolism in tumor cells. [ABSTRACT FROM AUTHOR]

Biological soil crusts are thin, inconspicuous communities along the soil atmosphere ecotone that, until recently, were unrecognized by ecologists and even more so by microbiologists. In its broadest meaning, the term biological soil crust (or biocrust) encompasses a variety of communities that develop on soil surfaces and are powered by photosynthetic primary producers other than higher plants: cyanobacteria, microalgae, and cryptogams like lichens and mosses. Arid land biocrusts are the most studied, but biocrusts also exist in other settings where plant development is constrained. The minimal requirement is that light impinge directly on the soil; this is impeded by the accumulation of plant litter where plants abound. Since scientists started paying attention, much has been learned about their microbial communities, their composition, ecological extent, and biogeochemical roles, about how they alter the physical behavior of soils, and even how they inform an understanding of early life on land. This has opened new avenues for ecological restoration and agriculture. [ABSTRACT FROM AUTHOR]

Every eukaryotic cell is covered with a thick layer of complex carbohydrates with essential roles in their social life. In Deuterostoma, sialic acids present at the outermost positions of glycans of glycoconjugates are known to be key players in cellular interactions including host-pathogen interactions. Their negative charge and hydrophilic properties enable their roles in various normal and pathological states and their expression is altered in many diseases including cancers. Sialylation of glycoproteins and glycolipids is orchestrated by the regulated expression of twenty sialyltransferases in human tissues with distinct enzymatic characteristics and preferences for substrates and linkages formed. However, still very little is known on the functional organization of sialyltransferases in the Golgi apparatus and how the sialylation machinery is finely regulated to provide the ad hoc sialome to the cell. This review summarizes current knowledge on sialyltransferases, their structure–function relationships, molecular evolution, and their implications in human biology. [ABSTRACT FROM AUTHOR]

As social life and communication move increasingly online, we have experienced the expansion and the normalisation of online shaming – different forms of (semi)public cross-platform condemnation of people and their actions by (mass) online audiences. Online shamings can be analysed as combinations of reintegrative (shame-correct-forgive) and disintegrative (shame-stigmatise-expel) social sanctioning practices, usually focusing the 'serious' disciplinary shaming on the behaviour of the offender. We propose that equal attention should be given to what we have termed 'recreational shaming' – humour-based playful collective shaming that often occurs via online platforms, seemingly just for the sake of shaming, motivated mainly by social belonging needs and entertainment gratification. By combining the results of standardised content analysis of Facebook recreational shaming groups (n = 65) and in-depth qualitative interviews with the 'modmins' of the groups (n = 8) we will give an overview of what is being shamed, how groups and modministrators create and enforce rules and what is the socio-cultural perceived meaning of this practice. We distinguish three spheres of recreational shaming that 'frame the shame' and demonstrate how recreational online shaming is often more about the self than the other – me performing the act of shaming for entertainment value, to belong in a group. Additionally, we introduce how shaming is used as a self-reflexive tool for behaviour-correction or base knowledge for dominant tastes. [ABSTRACT FROM AUTHOR]

Although massive biomass fluctuations of coastal-pelagic fishes are an iconic example of the impacts of climate variability on marine ecosystems, the mechanisms governing these dynamics are often elusive. We construct a 45-year record of nitrogen stable isotopes measured in larvae of Northern Anchovy (Engraulis mordax) in the California Current Ecosystem to assess patterns in food chain length. Larval trophic efficiency associated with a shortened food chain increased larval survival and produced boom periods of high adult biomass. In contrast, when larval food chain length increased, and energy transfer efficiency decreased, the population crashed. We propose the Trophic Efficiency in Early Life (TEEL) hypothesis, which states that larval fishes must consume prey that confer sufficient energy for survival, to help explain natural boom-bust dynamics of coastal pelagic fishes. Our findings illustrate a potential for trophic indicators to generally inform larval survival and adult population dynamics of coastal-pelagic fishes.A characteristic of costal-pelagic fishes is their large population size fluctuations, yet the drivers remain elusive. Here, the authors analyze a 45-year timeseries of nitrogen stable isotopes measured in larvae of Northern Anchovy and find that high energy transfer efficiency from the base of the food web up to young larvae confers high survival and recruitment to the adult population. [ABSTRACT FROM AUTHOR]

Nitrogen isotopes are widely used to study the trophic position of animals in modern food webs; however, their application in the fossil record is severely limited by degradation of organic material during fossilization. In this study, we show that the nitrogen isotope composition of organic matter preserved in mammalian tooth enamel (δ15Nenamel) records diet and trophic position. The δ15Nenamel of modern African mammals shows a 3.7‰ increase between herbivores and carnivores as expected from trophic enrichment, and there is a strong positive correlation between δ15Nenamel and δ15Nbone-collagen values from the same individuals. Additionally, δ15Nenamel values of Late Pleistocene fossil teeth preserve diet and trophic level information, despite complete diagenetic loss of collagen in the same specimens. We demonstrate that δ15Nenamel represents a powerful geochemical proxy for diet that is applicable to fossils and can help delineate major dietary transitions in ancient vertebrate lineages. Enamel-bound nitrogen isotopes in modern and fossil mammal teeth preserve dietary and trophic level information. This novel geochemical archive can be used to reconstruct trophic niche in ancient ecosystems. [ABSTRACT FROM AUTHOR]

Rationale: We report modifications to a commercial elemental analyzer‐isotope ratio mass spectrometer that permit high‐precision isotopic analysis of nanomoles of carbon (C), nitrogen (N), and sulfur (S) on a single sample without chemical or cryogenic trapping of gases. The sample size required for measurement by our system is about two orders of magnitude less than that for conventional analyses. Methods: Our system builds on the analytical advancements offered by the EA IsoLink IRMS System and employs simple modifications to reduce the diameter of the flow path (reactors, water trap, and transfer lines), enhance peak separation (gas chromatography capillary column), and improve sample transfer to the ion source of the mass spectrometer (reduced flow rates). Results: Conventional precision (<0.2‰) can be achieved down to c. 500 nmol C, N, and S for samples analyzed without modification of the commercial system. Further reduction in sample size (<50 nmol C, N, and S) was achieved with minor modifications. There is a significant carbon blank and a small nitrogen blank that can be measured directly and a sulfur blank that can be calculated using regression. Only 30 nmol of N, 22 nmol of C, and 12 nmol of S are needed to achieve better than 1‰ precision (1σ) from a single measurement. Larger samples and more replicate measurements provide better precision. Conclusions: The nano‐EA method described here reduces sample size requirements by two orders of magnitude compared to traditional approaches and improves the accuracy and precision of isotope measurements on sample sizes less than 1 μmol. These advancements simplify the analytical technique and broaden the range and type of samples amenable to EA analysis. [ABSTRACT FROM AUTHOR]

Visualization of viruses and their hosts has been paramount to their study and understanding. The direct observation of the morphological dynamics of infection is a highly desired capability and the focus of instrument development across a variety of microscopy technologies. This study demonstrates progress that has beenmade in exploiting the capabilities offered by HS-AFM to characterise the interactions between coccolithoviruses and their globally important coccolithophore hosts. We observe whole Emiliania huxleyi Virus capsids, transient binding to Emiliania huxleyi derived supported lipid bilayers, and host-virus binding in real-time in an environmentally relevant, aqueous environment. [ABSTRACT FROM AUTHOR]

Background: Permanently stratified lakes contain diverse microbial communities that vary with depth and so serve as useful models for studying the relationships between microbial community structure and geochemistry. Recent work has shown that these lakes can also harbor numerous bacteria and archaea from novel lineages, including those from the Candidate Phyla Radiation (CPR). However, the extent to which geochemical stratification differentially impacts carbon metabolism and overall genetic potential in CPR bacteria compared to other organisms is not well defined. Results: Here, we determine the distribution of microbial lineages along an oxygen gradient in Lac Pavin, a deep, stratified lake in central France, and examine the influence of this gradient on their metabolism. Genome-based analyses revealed an enrichment of distinct C1 and CO2 fixation pathways in the oxic lake interface and anoxic zone/sediments, suggesting that oxygen likely plays a role in structuring metabolic strategies in non-CPR bacteria and archaea. Notably, we find that the oxidation of methane and its byproducts is largely spatially separated from methane production, which is mediated by diverse communities of sediment methanogens that vary on the centimeter scale. In contrast, we detected evidence for RuBisCO throughout the water column and sediments, including form II/III and form III-related enzymes encoded by CPR bacteria in the water column and DPANN archaea in the sediments. On the whole, though, CPR bacteria and phages did not show strong signals of gene content differentiation by depth, despite the fact that distinct species groups populate different lake and sediment compartments. Conclusions: Overall, our analyses suggest that environmental gradients in Lac Pavin select for capacities of CPR bacteria and phages to a lesser extent than for other bacteria and archaea. This may be due to the fact that selection in the former groups is indirect and depends primarily on host characteristics. 4BhWTC5f45WSQz24CW7a2L Video Abstract [ABSTRACT FROM AUTHOR]

Objective: To analyze the relationship of maternal anxiety symptoms with breastfeeding self-efficacy and duration of exclusive breastfeeding. Methods: Prospective cohort study developed in a Breastfeeding Center of a university hospital in the city of São Paulo. The sample consisted of 83 postpartum women in follow-up for 210 days after delivery. The Anxiety Subscale of the Edinburgh Postnatal Depression Scale and the Breastfeeding Self-Efficacy Scale were used. Results: The mean total score for anxiety was 3.76 points and for maternal self-efficacy to breastfeed was 128.58. Over the months, anxiety symptoms and breastfeeding self-efficacy showed similar behavior and were not statistically significant. The following risk factors were associated with the increase in anxiety symptoms: abortion, previous history of depression, complaints about oneself, unsatisfactory family and marital relationships, worsening of the relationship with the partner after the baby was born and lower maternal breastfeeding self-efficacy, reflected in the technique domain and intrapersonal thoughts domain. The time between cessation of exclusive breastfeeding and anxiety was not statistically different. Conclusion: The investigated postpartum women had a high prevalence of anxiety symptoms, with significant interference in the perception and confidence in their ability and maternal capability to successfully breastfeed the baby. There was no association between anxiety symptoms and early breastfeeding cessation. [ABSTRACT FROM AUTHOR]

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Two diazotrophic cyanobacteria (Anabaena cylindrica PCC 7122 and Nostoc sp. PCC 7120) were cultivated to produce cyanophycin, a nitrogen reserve compound, under nitrogen fixing conditions. In preliminary continuous experiments, Nostoc sp. was shown to be more efficient, accumulating a higher amount of cyanophycin and showing a greater capability to fix atmospheric nitrogen in the biomass (67 mgN d−1 of fixed nitrogen per liter of culture). The operating conditions were then optimized to maximize the cyanophycin productivity: the effect of incident light intensity, residence time and nitrogen availability were investigated. Nitrogen availability and/or pH played a major role with respect to biomass production, whereas phosphorus limitation was the main variable to maximize cyanophycin accumulation. In this way, it was possible to achieve a stable and continuous production of cyanophycin (CGP) under diazotrophic conditions, obtaining a maximum cyanophycin productivity of 15 mgCGP L−1 d−1. Key points: • Diazotrophic cyanobacteria produce stable amount of cyanophycin in continuous PBR. • Nostoc sp. proved to be more efficient in producing cyanophycin than Anabaena sp. • P deprivation is the major variable to increase cyanophycin productivity in continuous. [ABSTRACT FROM AUTHOR]

The emergence of forests on Earth (~385 million years ago, Ma)1 has been linked to an order-of-magnitude decline in atmospheric CO2 levels and global climatic cooling by altering continental weathering processes, but observational constraints on atmospheric CO2 before the rise of forests carry large, often unbound, uncertainties. Here, we calibrate a mechanistic model for gas exchange in modern lycophytes and constrain atmospheric CO2 levels 410–380 Ma from related fossilized plants with bound uncertainties of approximately ±100 ppm (1 sd). We find that the atmosphere contained ~525–715 ppm CO2 before continents were afforested, and that Earth was partially glaciated according to a palaeoclimate model. A process-driven biogeochemical model (COPSE) shows the appearance of trees with deep roots did not dramatically enhance atmospheric CO2 removal. Rather, shallow-rooted vascular ecosystems could have simultaneously caused abrupt atmospheric oxygenation and climatic cooling long before the rise of forests, although earlier CO2 levels are still unknown. Dahl et al. present new evidence based on leaf gas-exchange in primitive vascular plants and fossil remains of some of their earliest ancestors. This alters our thinking on how plants impacted the Earth System and climate. [ABSTRACT FROM AUTHOR]

Haig HA, Chegoonian AM, Davies J-M, Bateson D, Leavitt PR. 2021. Marked blue discoloration of late winter ice and water due to autumn blooms of cyanobacteria. Lake Reserv Manage. 38:1–15. Continued eutrophication of inland waters by nutrient pollution can combine with unprecedented atmospheric and lake warming to create emergent environmental surprises. Here we report the first known occurrence of marked blue discoloration of ice and water in highly eutrophic prairie lakes during late winter 2021. Intense blue staining was reported first to governmental agencies by ice fishers in early March 2021, then communicated widely through social media, resulting in First Nations and public concern over potential septic field release, toxic spills, urban pollution, and agricultural mismanagement. Analysis of water from stained and reference sites using ultraviolet (UV)–visible spectrophotometry and high-performance liquid chromatography demonstrated that the blue color arose from high concentrations (∼14 mg/L) of the cyanobacterial pigment C-phycocyanin that was released after an unexpected bloom of Aphanizomenon flos-aquae in late October 2020 was frozen into littoral ice. Remote sensing using the Sentinel 3 A/B OLCI and Sentinel 2 A/B MSI satellite platforms suggested that blue staining encompassed 0.68 ± 0.24 km2 (4.25 ± 1.5% of lake surface area), persisted over 4 weeks, and was located within 50 m of the lakeshore in regions where fall blooms of cyanobacteria had been particularly dense. Although toxin levels were low (∼0.2 μg microcystin/L), high concentrations of C-phycocyanin raised public concern over eutrophication, pollution, and climate change, and resulted in rapid governmental and academic response. Given that climate change and nutrient pollution are increasing the magnitude and duration of cyanobacterial blooms, blue staining of lake ice may become widespread in eutrophic lakes subject to ice cover. [ABSTRACT FROM AUTHOR]

Oceanic anoxic events (OAEs) represent changes in global carbon cycle as well as biogeochemical cycles and are robust recorders of major changes brought in the ocean-atmosphere system of the Earth. In the present study, a comprehensive compilation of well-documented OAEs in the Earth's geological history indicates that compared to the plethora of OAE studies in different parts of the world, the Indian part lacks sufficient such geological studies. Also, it has been observed that despite the variety of causes referred by researchers for the occurrence of OAEs based on various geological proxies, their development tends to cluster in particular periods having unique geological settings under specific climate conditions of the Earth. OAEs usually coincided with Earth's greenhouse condition and in marine to shallow marine depositional settings, which have been associated with rapid alternating phases of transgression and regression. The Paleocene-Eocene thermal maximum (PETM) at the Paleocene-Eocene boundary comprises the last OAE of the Phanerozoic Eon and the only identified OAE in the Cenozoic. The deposition of Himalayan foreland basin sediments during Paleocene-Eocene time coincides with the India-Eurasia collision and PETM. Characteristic litho sections of Paleocene-Eocene HFB shallow marine sediments represented by the Subathu Formation occur in and around the Jammu region (of the Ramngar sub-basin) and Simla region (of the Subathu sub-basin) of NW Himalaya (India) and have been explored for OAE records. Besides the fact that deposition of these sediments coincides with PETM, there are many other reasons which suggest possible representation of these as records of OAE. For example, these sediments show OAE specific sedimentary and biostratigraphic facies associations which are characteristic of alternating transgressive-regressive successions. The base of these early HFB sediments consists of sideritic ironstone, phosphorite, and black shale association indicating commencement of basinal sedimentation under euxinic, shallow marine conditions. Though these Paleocene-Eocene HFB sediments comprising dominantly black to gray-green shales are regionally extensive, however, these occur in discontinuous patches all along the HFB and also greatly vary in thickness due to the tectonic complexity of the Himalayan region. [ABSTRACT FROM AUTHOR]

In the context of climate change, soil is a major pool of stable carbon on earth, yet knowledge on soil carbon turnover is limited. The difference in 13C/12C content observed between C3 and C4 plant crops has been widely used to distinguish the sources of soil organic carbon under continuous monoculture, but not in C3–C4 rotations. We studied the stability of the δ13CSOC content and the effect of no tillage, conventional tillage, and rotary tillage in 4 soils sampled at 0–5, 5–10, and 10–20 cm depth, in 2018–2019 in a field with long-term history of wheat (C3) and maize (C4) rotations. We also analyzed the results from the literature. The results show that the δ13CSOC is not statistically affected by the sampling date, thus allowing to use this method to distinguish C3 and C4 plant contributions in rotations. Moreover, no-tillage favored the preservation of wheat carbon, and this preservation was accentuated at 10–20 cm depth. δ13CSOC is also affected by fertilization and irrigation. The literature confirmed that wheat-derived carbon is better preserved that maize-derived carbon, on the average. [ABSTRACT FROM AUTHOR]

Marine dissolved organic matter (DOM) comprises a vast and unexplored molecular space. Most of it resided in the oceans for thousands of years. It is among the most diverse molecular mixtures known, consisting of millions of individual compounds. More than 1 Eg of this material exists on the planet. As such, it comprises a formidable source of natural products promising significant potential for new biotechnological purposes. Great emphasis has been placed on understanding the role of DOM in biogeochemical cycles and climate attenuation, its lifespan, interaction with microorganisms, as well as its molecular composition. Yet, probing DOM bioactivities is in its infancy, largely because it is technically challenging due to the chemical complexity of the material. It is of considerable interest to develop technologies capable to better discern DOM bioactivities. Modern screening technologies are opening new avenues allowing accelerated identification of bioactivities for small molecules from natural products. These methods diminish a priori the need for laborious chemical fractionation. We examine here the application of untargeted metabolomics and multiplexed high-throughput molecular-phenotypic screening techniques that are providing first insights on previously undetectable DOM bioactivities. Key points: • Marine DOM is a vast, unexplored biotechnological resource. • Untargeted bioscreening approaches are emerging for natural product screening. • Perspectives for developing bioscreening platforms for marine DOM are discussed. [ABSTRACT FROM AUTHOR]

Background: Radioactive or stable isotopic labeling of metabolites is a strategy that is routinely used to map the cellular fate of a selected labeled metabolite after it is added to cell culture or to the circulation of an animal. However, a labeled metabolite can be enzymatically changed in cellular metabolism, complicating the use of this experimental strategy to understand how a labeled metabolite moves between organs. These methods are also technically demanding, expensive and potentially toxic. To allow quantification of the bulk movement of metabolites between organs, we have developed a novel application of stable isotope ratio mass spectrometry (IRMS). Results: We exploit natural differences in 13C/12C ratios of plant nutrients for a low-cost and non-toxic carbon labeling, allowing a measurement of bulk carbon transfer between organs in vivo. IRMS measurements were found to be sufficiently sensitive to measure organs from individual Drosophila melanogaster larvae, giving robust measurements down to 2.5 μg per sample. We apply the method to determine if carbon incorporated into a growing solid tumor is ultimately derived from food or host tissues. Conclusion: Measuring tumor growth in a D. melanogaster larvae tumor model reveals that these tumors derive a majority of carbon from host sources. We believe the low cost and non-toxic nature of this methodology gives it broad applicability to study carbon flows between organs also in other animals and for a range of other biological questions. [ABSTRACT FROM AUTHOR]

Organic molecules are key components of the Earth-life system. Their stable isotope composition provides information on various problems such as past climate, energy resources, or the synthesis of prebiotically relevant molecules on Earth and elsewhere. Organic molecules are made of isotopologues, molecules differing in the number and/or position of isotope substitution. Recent years have witnessed a boom in technological development dedicated to isotopologue measurement, leading to an unprecedented degree of information regarding organic (bio)synthesis. While applications in Earth and planetary sciences has been limited so far to simple hydrocarbons, typically methane, isotopologue proxies are expected to rapidly emerge in biogeochemistry, providing new types of environmental and biological tracers. This review describes principles and measurement techniques, as well as present and potential biogeochemical applications. Stable isotopes of organic molecules are widely used in biogeo-chemistry. Isotope analysis at the intramolecular level is expected to provide new information on the origin of molecules. Recent technological developments unlocked the potential of intramolecular isotope analysis, providing new proxies in biogeochemistry and new opportunities to clarify questions related to Earth and planetary sciences. [ABSTRACT FROM AUTHOR]

In Lake Biwa, picocyanobacteria blooms usually occur during the summer–autumn thermal stratification period. Intriguingly, a novel bloom was detected in winter 2015–2016, in which picocyanobacterial cell density increased by one order of magnitude despite lower water temperature, suggesting the possibility that "cold-water-preference" species dominate in the picocyanobacterial community. In the present study, we investigated the phylogenetic diversity of picocyanobacteria in Lake Biwa by analyzing the 16S rRNA gene. We found that the picocyanobacterial community were highly diverse in Lake Biwa, with eight Synechococcus-related operational taxonomic units (OTUs) detected in different seasons. These OTUs fell into distinct phylogenetic groups, and the majority were closely related to clusters reported previously. Notably, OTU04, detected during the winter bloom, was highly affiliated with sequences found in a variety of lakes, such as Tibetan lakes and Lake Superior, where the water bodies generally have a low trophic state and temperature, and different concentrations of total dissolved solids. Thus, we inferred that the group containing OTU04 may be a psychrotolerant lineage that is widely distributed in oligotrophic water systems with low–intermediate salinity. [ABSTRACT FROM AUTHOR]

The Internet is a common medium through which people engage in interpersonal electronic surveillance (IES) of one another. We know little empirically about what predicts IES in romantic relationships. The present study expands on factors identified in previous studies (including demographic characteristics, relational characteristics, and other psychosocial variables) to predict surveillance in romantic relationships. Internet users in established romantic relationships (n = 259) completed inventories on the frequency of surveillance behavior, relationship variables, demographic variables, and Internet usage variables. Hierarchical regression was applied to understand relationships between these behaviors and surveillance. The regression supported that relationship variables and Internet use variables significantly predicted IES in romantic relationships. These findings further our understanding of the Internet to surveil partners. [ABSTRACT FROM AUTHOR]

Background: Since labor and delivery units often serve as emergency units for pregnant women, the use of obstetric triage systems with poor or inadequate quality can lead to unintended consequences such as over and under-triage and so a waste of humans and financial resources. Therefore, this systematic review was conducted to evaluate the measurement properties of obstetric triage tools.Methods: PubMed, EMBASE, and Medline were searched to identify studies in October 2018 and were updated in May 2019. The risk of bias COSMIN checklist was used to evaluate the quality of the studies. The quality of every measurement property was appraised by the update criteria of COSMIN. Evidence quality was judged using the modified GRADE approach.Results: A total of 444 studies were retrieved in initial search. Six studies evaluating 4 tools were included in this study. All the included studies reported only content validity and reliability. The quality of evidence varied from very low to moderate. The quality of content validity and reliability of the included tools was sufficient except for the reliability of the maternal-fetal triage index. The obstetric triage acuity scale (OTAS) was found to have higher reliability than other tools.Conclusions: Due to insufficient evidence, the conclusions about the quality of measurement properties of each obstetric triage tool may be uncertain. This review emphasizes the necessity for further studies with robust methodological quality on the measurement properties of obstetric triage tools. [ABSTRACT FROM AUTHOR]

The development of the isotopic niche, an n-dimensional hypervolume (with n being the number of isotopes) occupied by a population in delta space, has revolutionized the study of animal interactions in wild populations. While the isotopic niche offers a useful means to understand interactions at many ecological resolutions (e.g., individual, population, community, ecosystem), a variety of intrinsic and extrinsic factors drive isotopic variability and influence the ultimate geometry of observed niche dimensions. Here, we provide an updated synthesis to guide the application of bulk stable isotope ratios to study ecological niches. We summarize progress in the application of bulk stable isotope ratios for evaluating niches to synthesize a formal definition of the isotopic niche. We identify six broad categories to describe drivers of isotopic variance introduced by the animal, its environment, and the researcher, and provide recommendations to account for such variations before, during, and after sample collection and data analyses. Our synthesis illustrates the considerations that should be made before employing the isotopic niche to broader ecological contexts, and offers guidance for the use and interpretation of isotopic niche dynamics in future studies. [ABSTRACT FROM AUTHOR]

Objectives: Cesarean section (C-section) is one of the most common surgeries for women, which has numerous complications including anxiety and vital sign changes. Various non-drug methods exist for controlling these complications. Although nurse companionship is one of such methods, there is little information about the accompaniment of mothers by trained nurses during the C-section surgery. This study aimed to determine the effect of "nurse companionship" on the level of anxiety and vital sign changes of C-section candidates. Materials and Methods: Using a random allocation method, this randomized control trial was performed on 128 C-section candidates in Al-Zahra teaching hospital of Tabriz in 2017. In addition to routine cares, intervention group mothers were accompanied and supported by a nurse 1 hour before to after the C-section surgery while mothers in the control group only received routine cares for the C-section. Data collection tools were demographic information form, visual analogue scale (VAS), digital blood pressure monitor, and chronometer. The anxiety level and vital sign changes were measured one hour before, during, and one hour after the C-section surgery. Finally, data were analyzed by SPSS 24 using the mixed repeated measures ANOVA. Results: The comparison of the results of the two groups showed that the accompaniment of the mothers had a significant effect on reducing anxiety during (P < 0.001) and 1 hour after (P = 0.011) C-section surgery while it had no significant effect on vital sign changes. Conclusions: The results revealed the positive effect of nurse companionship on reducing mothers' anxiety during and after the C-section surgery. Therefore, this method can be used as non-invasive nursing care during C-section surgeries and in operating rooms. However, cost-effectiveness assessment is recommended before the implementation of this method. [ABSTRACT FROM AUTHOR]

The Archean Eon was a time of predominantly anoxic Earth surface conditions, where anaerobic processes controlled bioessential element cycles. In contrast to “oxygen oases” well documented for the Neoarchean [2.8 to 2.5 billion years ago (Ga)], the magnitude, spatial extent, and underlying causes of possible Mesoarchean (3.2 to 2.8 Ga) surface-ocean oxygenation remain controversial. Here, we report δ15N and δ13C values coupled with local seawater redox data for Mesoarchean shales of the Mozaan Group (Pongola Supergroup, South Africa) that were deposited during an episode of enhanced Mn (oxyhydr)oxide precipitation between ∼2.95 and 2.85 Ga. Iron and Mn redox systematics are consistent with an oxygen oasis in the Mesoarchean anoxic ocean, but δ15N data indicate a Mo-based diazotrophic biosphere with no compelling evidence for a significant aerobic nitrogen cycle. We propose that in contrast to the Neoarchean, dissolved O2 levels were either too low or too limited in extent to develop a large and stable nitrate reservoir in the Mesoarchean ocean. Since biological N2 fixation was evidently active in this environment, the growth and proliferation of O2-producing organisms were likely suppressed by nutrients other than nitrogen (e.g., phosphorus), which would have limited the expansion of oxygenated conditions during the Mesoarchean. [ABSTRACT FROM AUTHOR]

Emiliania huxleyi is a globally important marine phytoplankton that is routinely infected by viruses. Understanding the controls on the growth and demise of E. huxleyi blooms is essential for predicting the biogeochemical fate of their organic carbon and nutrients. In this study, we show that the production of nitric oxide (NO), a gaseous, membrane-permeable free radical, is a hallmark of early-stage lytic infection in E. huxleyi by Coccolithoviruses, both in culture and in natural populations in the North Atlantic. Enhanced NO production was detected both intra- and extra-cellularly in laboratory cultures, and treatment of cells with an NO scavenger significantly reduced viral production. Pre-treatment of exponentially growing E. huxleyi cultures with the NO donor S-nitroso-N-acetylpenicillamine (SNAP) prior to challenge with hydrogen peroxide (H2O2) led to greater cell survival, suggesting that NO may have a cellular antioxidant function. Indeed, cell lysates generated from cultures treated with SNAP and undergoing infection displayed enhanced ability to detoxify H2O2. Lastly, we show that fluorescent indicators of cellular ROS, NO, and death, in combination with classic DNA- and lipid-based biomarkers of infection, can function as real-time diagnostic tools to identify and contextualize viral infection in natural E. huxleyi blooms. [ABSTRACT FROM AUTHOR]

Background/objective: Postpartum depression is linked to decreased quality mother-infant interactions and long-term negative impacts on children's behavior and health. Infant care competence may be reduced by postpartum depression and other maternal or environmental variables. Thus, the objective of this study was to explain factors that contribute to perceived infant care competence among mothers with postpartum depression. Methods: Multiple regression analysis and correlational analysis were conducted to study associations between the predictors (depression severity, social support, child development, family functioning) and the outcome of perceived infant care competence among a peer support intervention study for mothers with postpartum depression (n = 55). Results: Child development, specifically communication (P =.04), gross (P =.00) and fine (P =.00) motor skills, problem solving (P =.00), and personal-social development (P =.01), explained maternal perceptions of responsiveness, an aspect of infant care competence. The best-fit model was obtained for the responsiveness subscale, in which 37% of the variance was explained by mothers' reports of infants' fine motor skills (P =.000) and nurturance (P =.039) as an aspect of social support and family functioning (P =.078). Conclusions: Recognition of the importance of infant development to perceived infant care competence, particularly mothers' perceptions of infant responsiveness, may offer targets for intervention. Helping mothers identify infant cues and milestones that signal infant responsiveness may be beneficial. Moreover, social support and family functioning may be targets for intervention to promote perceived infant care competence in mothers affected by postpartum depression. [ABSTRACT FROM AUTHOR]

Summary: Viruses that infect photoautotrophs have a fundamental relationship with light, given the need for host resources.We investigated the role of light on Coccolithovirus (EhV) infection of the globally distributed coccolithophore, Emiliania huxleyi. Light was required for EhV adsorption, and viral production was highest when host cultures were maintained in continuous light or at irradiance levels of 150–300 μmol m−2 s−1. During the early stages of infection, photosynthetic electron transport remained high, while RuBisCO expression decreased concomitant with an induction of the pentose phosphate pathway, the primary source of de novo nucleotides. A mathematical model developed and fitted to the laboratory data supported the hypothesis that EhV replication was controlled by a trade‐off between host nucleotide recycling and de novo synthesis, and that photoperiod and photon flux could toggle this switch.Laboratory results supported field observations that light was the most robust driver of EhV replication within E. huxleyi populations collected across a 2000 nautical mile transect in the North Atlantic.Collectively, these findings demonstrate that light can drive host–virus interactions through a mechanistic interplay between host metabolic processes, which serve to structure infection and phytoplankton mortality in the upper ocean. [ABSTRACT FROM AUTHOR]

Rationale: The combination of an Elemental Analyzer, a GasBench interface and Isotope Ratio Mass Spectrometry (EA‐GasBench‐IRMS system) is a promising method for the δ15N analysis of samples containing trace amounts of nitrogen (N). Nevertheless, N blanks, which are limiting factors for the accuracy and precision of measured δ15N values, have received little study. In this paper, a variety of N blank sources in the EA‐GasBench‐IRMS system were systematically evaluated in order to take effective measures to reduce the blank interference as much as possible. Methods: N‐Isotopic analysis was accomplished using an elemental analyzer coupled to an isotope ratio mass spectrometer via a sample loop and a GasBench interface. The N in the sample was converted into N2 gas in the EA system, and then transferred and trapped in a sample loop with a deactivated stainless‐steel chromatography column packed with 5 A molecular sieve polymer at liquid nitrogen temperature (−196°C). Subsequently, the N2 gas was released by warming the sample loop up to 100°C and introduced into the isotope ratio mass spectrometer via the GasBench interface. The N blank sources in the EA‐GasBench‐IRMS system were investigated systematically by looking at seven parts: (a) Helium carrier gas, (b) Autosampler, (c) CO2/water trap, (d) Size of reactor tube, (e) Sample collection time, (f) Oxygen gas, and (g) Capsules. Results: The N blanks are mainly derived from the helium carrier gas, atmospheric N2 entrained into the system through the autosampler, and the N retained in the CO2/water trap filled with CO2 absorbent and Mg(ClO4)2, which together can account for a total of ~507.3 nmol N. Through purifying the helium gas, modifying the autosampler and using a cryogenic trap, we reduced the N blank considerably, to ~10.7 nmol, and obtained a nearly uniform isotopic composition (δ15NBlank = −4.54 ± 0.36‰ AIR, n = 32, 1SD) of blank N thus guaranteeing a reliable correction. Conclusions: Measurements on a set of IAEA‐N1, IAEA‐600 and collagen standards with 40 nmol–200 nmol N produced accurate δ15N values with standard deviation of ±0.26‰, ±0.22‰ and ± 0.23‰ (1σ) after blank correction, respectively. Our findings offer clues to optimizing the analytical method for trace N isotopic determination and they are also beneficial to improving δ15N measurement using conventional EA‐IRMS. [ABSTRACT FROM AUTHOR]

This paper places the Abecedarian Approach in theoretical and historical context and reviews the results from three randomized controlled trials that have tested an experimental protocol designed to prevent cognitive disabilities and their social consequences. Results affirm that cognitive disabilities can be prevented in early childhood and subsequent academic achievement enhanced via a multipronged comprehensive approach that contains individualized and responsive early childhood education starting in early infancy, coupled with pediatric health care, good nutrition, and family-oriented social services. Additional important findings reveal that the most vulnerable children benefited the most and that cognitive gains were not at the expense of children's socioemotional development or relationship to family. In general, mothers derived benefits in education and employment and teenage mothers especially benefited from their children participating in the early education treatment group. On the whole, the overall pattern of results supports a multidisciplinary, individualized, and long-term longitudinal perspective on human development and prevention science. Recent structural and functional brain imaging in the fifth decade of life shows persistent effects of intensive early educational treatment. Independent recent cost-benefit analysis in adulthood reveals a 7.3:1 return on investment with a 13.7% average annual rate of return. The paper concludes with a discussion of implications of the Abecedarian Approach to today's high-risk population in the USA. [ABSTRACT FROM AUTHOR]

In this study, the under-examined area of privacy perception and protection on Chinese social media is investigated. The prevalence of digital technology shapes the social, political and cultural aspects of the lives of urban young adults. The influential Chinese social media platform WeChat is taken as a case study, and the ease of connection, communication and transaction combined with issues of commercialisation and surveillance are discussed in the framework of the privacy paradox. Protective behaviour and tactics are examined through different perceptions of privacy in the digital age. The findings of this study suggest that users possess certain amount of freedoms on WeChat. However, users’ individual privacy attitudes and behaviour in practice suggest they have a declined sense of their own freedom and right to privacy. A privacy paradox exists when users, while holding a high level of concerns, in reality do little to further the protection of their personal information on WeChat. We argue that once a user has ingrained part of their social engagement within the WeChat system, the incentive for them to remain a part of the system outweighs their requirement to secure their privacy online as their decision-making is largely based on a simple cost-benefit analysis. The power and social capital yielded via WeChat is too valuable to give up as WeChat is widely used not only for private conversations, but also for study or work-related purposes. It further blurs the boundaries between the public, the professional and the private, which is a rather unique case compared with other social media around the world. [ABSTRACT FROM AUTHOR]

Since rooted vascular plants rose to dominance, associated microbiota have powerfully influenced global biogeochemistry by mobilizing N and P and otherwise aiding plant health, thereby fostering sequestration of CO2 into coal and soil organics. Less well understood are evolutionary history and biogeochemical roles of microbiomes of ecologically significant nonvascular plants and related algae, whose lineages penetrate more deeply into time. Because analyses of diverse host-microbiome systems indicate that evolutionary history commonly influences microbiome composition and function, we mapped onto a geological time frame biogeochemical features inferred in our previous metagenomic studies of a phylogenetic spectrum of multicellular, freshwater-terrestrial, nonvascular autotroph-microbiome systems: Nostoc commune, representing microbialite-forming cyanobacteria; the Nostoc lichen Peltigera ponojensis; chlorophyte Cladophora glomerata; streptophyte alga Coleochaete pulvinata; moss Sphagnum fimbriatum; and liverwort Conocephalum conicum. Widespread and often abundant today, these species represent ancient lineages of minimal ages ranging from 1450 to 380 Ma, information we used to estimate present global annual magnitudes of organic/inorganic C sequestration, N fixation, and methane oxidation and to calculate biogeochemical impacts during periods from lineage origin to the rise of vascular plants and from lineage origins to present. Functional comparisons indicated that (1) functionally diverse bacterial associates have likely enhanced global C- and N-cycle roles of cyanobacteria for ∼1.5 billion years; (2) by 700-800 Ma, chlorophyte microbiomes retaining ancient functional features (e.g., vitamin B12 biosynthesis and N fixation) had added diverse methane-oxidizing bacteria and eukaryotes, including early metazoans; (3) by ∼500 Ma, streptophyte algal microbiomes possessing ancient functions had incorporated early-diverging fungi; (4) by 450 Ma, microbiomes of early plants included diverse prokaryotes, protists, fungi, and early terrestrial animals; and (5) by 385 Ma, plant microbiomes included P-mobilizing fungi. Autotroph-microbiome systems appear to have accreted functions of global significance over deep time, a new concept that illuminates the early evolution of terrestrial life and that aids modeling past, present, and future biogeochemical impacts. [ABSTRACT FROM AUTHOR]

The average cell size of marine phytoplankton is critical for the flow of energy and nutrients from the base of the food web to higher trophic levels. Thus, the evolutionary succession of primary producers through Earth's history is important for our understanding of the radiation of modern protists ~800 million years ago and the emergence of eumetazoan animals ~200 million years later. Currently, it is difficult to establish connections between primary production and the proliferation of large and complex organisms because the mid-Proterozoic (~1,800-800 million years ago) rock record is nearly devoid of recognizable phytoplankton fossils. We report the discovery of intact porphyrins, the molecular fossils of chlorophylls, from 1,100-million-year-old marine black shales of the Taoudeni Basin (Mauritania), 600 million years older than previous findings. The porphyrin nitrogen isotopes (δ15Npor = 5.6-10.2‰) are heavier than in younger sedimentary sequences, and the isotopic offset between sedimentary bulk nitrogen and porphyrins (εpor = -5.1 to -0.5‰) points to cyanobacteria as dominant primary producers. Based on fossil carotenoids, anoxygenic green (Chlorobiacea) and purple sulfur bacteria (Chromatiaceae) also contributed to photosynthate. The low εpor values, in combination with a lack of diagnostic eukaryotic steranes in the time interval of 1,600-1,000 million years ago, demonstrate that algae played an insignificant role in mid-Proterozoic oceans. The paucity of algae and the small cell size of bacterial phytoplankton may have curtailed the flow of energy to higher trophic levels, potentially contributing to a diminished evolutionary pace toward complex eukaryotic ecosystems and large and active organisms. [ABSTRACT FROM AUTHOR]

The cosmopolitan coccolithophore Emiliania huxleyi is a unicellular eukaryotic alga that forms vast blooms in the oceans impacting large biogeochemical cycles. These blooms are often terminated due to infection by the large dsDNA virus, E. huxleyi virus (EhV). It was recently established that EhV-induced modulation of E. huxleyi metabolism is a key factor for optimal viral infection cycle. Despite the huge ecological importance of this host-virus interaction, the ability to assess its spatial and temporal dynamics and its possible impact on nutrient fluxes is limited by current approaches that focus on quantification of viral abundance and biodiversity. Here, we applied a host and virus gene expression analysis as a sensitive tool to quantify the dynamics of this interaction during a natural E. huxleyi bloom in the North Atlantic. We used viral gene expression profiling as an index for the level of active infection and showed that the latter correlated with water column depth. Intriguingly, this suggests a possible sinking mechanism for removing infected cells as aggregates from the E. huxleyi population in the surface layer into deeper waters. Viral infection was also highly correlated with induction of host metabolic genes involved in host life cycle, sphingolipid, and antioxidant metabolism, providing evidence for modulation of host metabolism under natural conditions. The ability to track and quantify defined phases of infection by monitoring co-expression of viral and host genes, coupled with advance omics approaches, will enable a deeper understanding of the impact that viruses have on the environment. [ABSTRACT FROM AUTHOR]

We carried out geochemical analyses on a sediment core from Lake Harris, Florida (USA) to identify sources of organic matter to the sediment throughout the Holocene, and relate changes in those sources to shifts in past climate and environmental conditions. We hypothesized that the sources of organic matter changed in response to regional hydrologic shifts following de-glaciation, and to human population expansion in the state during the 20th century. Hydroclimate shifts in Florida were related to: 1) a steady rise in relative sea level and the fresh water table that began in the early Holocene, 2) wetland formation and expansion ca. 5,000 cal yrs BP, and 3) the onset of the modern El Niño (ENSO) cycle ~3,000 cal yrs BP. Stratigraphic changes in sediment variables from Lake Harris reflect each of these hydroclimate periods. Early in the Holocene, Lake Harris was a marsh-like system in a relatively dry, open-prairie environment. Organic sediments deposited at that time were derived largely from terrestrial sources, as inferred from high TOC/TN ratios, a dominance of longer-chain of n-alkanes (n-C29-31), relatively negative organic carbon isotope values (δ13CTOC), and low biogenic silica concentrations. In the middle Holocene, a positive shift in δ13CTOC coincided with the onset of wetter conditions in Florida. Submerged macrophyte biomarkers (n-C21-23) dominated, and during that period bulk organic carbon isotope values were most similar to δ13C values of mid-chain-length n-alkanes. In the late Holocene, δ13CTOC values declined, CaCO3 levels decreased to trace amounts, organic carbon concentrations increased and diatom biogenic silica concentrations increased from 10 to 120 mg g-1. Around 2,900 cal yrs BP, the effects of ENSO intensified and many Florida lakes deepened to their current limnetic state. Concentrations of algal and cyanobacterial biomarkers in the Lake Harris core increased by orders of magnitude after about AD 1940, in response to human-induced eutrophication, an inference supported by values of δ15N that fluctuate around zero. [ABSTRACT FROM AUTHOR]

The high lipid diversity of microalgae has been used to taxonomically differentiate phytoplankton taxa at the class level. However, important lipids such as phospholipids (PL) and betaine lipids (BL) with potential chemotaxonomy application in phytoplankton ecology have been scarcely studied. The chemotaxonomy value of PL and BL depends on their intraspecific extent of variation as microalgae respond to external changing factors. To determine such effects, lipid class changes occurring at different growth stages in 15 microalgae from ten different classes were analyzed. BL occurred in 14 species and were the less affected lipids by growth stage with diacylglyceryl-hydroxymethyl-N,N,N-trimethyl-b-alanine (DGTA) showing the highest stability. PL were more influenced by growth stage with phosphatidylcholine (PC), phosphatidylglycerol (PG), and phosphatidyletanolamine (PE) declining towards older culture stages in some species. Glycolipids were the more common lipids, and no evident age-related variability pattern could be associated to taxonomic diversity. Selecting BL and PL as descriptor variables optimally distinguished microalgae taxonomic variability at all growth stages. Principal coordinate analysis arranged species through a main tendency from diacylglyceryl-hydroxymethyl-N,N,N-trimethyl-b-alanine (DGCC) containing species (mainly dinoflagellates and haptophytes) to DGTA or PC containing species (mainly cryptophytes). Two diatom classes with similar fatty acid profiles could be distinguished from their respective content in DGTA (Bacillariophyceae) or DGCC (Mediophyceae). In green lineage classes (Trebouxiophyceae, Porphyridophyceae, and Chlorodendrophyceae), PC was a better descriptor than BL. BL and PL explained a higher proportion of microalgae taxonomic variation than did fatty acids and played a complementary role as lipid markers. [ABSTRACT FROM AUTHOR]

The genus Micromonas comprises phytoplankton that show among the widest latitudinal distributions on Earth, and members of this genus are recurrently infected by prasinoviruses in contrasted thermal ecosystems. In this study, we assessed how temperature influences the interplay between the main genetic clades of this prominent microalga and their viruses. The growth of three Micromonas strains (Mic-A, Mic-B, Mic-C) and the stability of their respective lytic viruses (MicV-A, MicV-B, MicV-C) were measured over a thermal range of 4-32.5 °C. Similar growth temperature optima (Topt) were predicted for all three hosts but Mic-B exhibited a broader thermal tolerance than Mic-A and Mic-C, suggesting distinct thermoacclimation strategies. Similarly, the MicV-C virus displayed a remarkable thermal stability compared with MicV-A and MicV-B. Despite these divergences, infection dynamics showed that temperatures below Topt lengthened lytic cycle kinetics and reduced viral yield and, notably, that infection at temperatures above Topt did not usually result in cell lysis. Two mechanisms operated depending on the temperature and the biological system. Hosts either prevented the production of viral progeny or maintained their ability to produce virions with no apparent cell lysis, pointing to a possible switch in the viral life strategy. Hence, temperature changes critically affect the outcome of Micromonas infection and have implications for ocean biogeochemistry and evolution. [ABSTRACT FROM AUTHOR]