Carbon isotope chemostratigraphy of the Late Silurian Lau Event, Gotland, Sweden

The positive δ13C excursion associated with the Late Silurian Lau Event (approximately 420 Ma) is recognized globally and considered to be one of the most prominent carbon isotope excursions of the Phanerozoic. Its maximum values are exceeded only by values from the Proterozoic. Over the last years the Lau Event has been studied in great detail on the island of Gotland, Sweden (Baltica palaeocontinent). These studies include lithological successions and high-resolution conodont biostratigraphy, as well as δ13C chemostratigraphy. For these reasons, Gotland is considered the standard classical model for studying the Lau Event. The purpose of the present study is to produce the first continuous, high-resolution δ13C stratigraphy across the stratigraphic range of the event. The δ13C record is based on two drill cores (Uddvide-1 and Ronehamn-1) and work as a standard model for global correlation of the event. The generated profiles have high positive peak values of 8.03 ‰ and 9.01 ‰ respectively in Uddvide-1 and Ronehamn-1 drill cores. Both profiles have the typical model of the Lau Event consisting of rising limb, plateau and falling limb. The correlation not only improves the knowledge on Ludlow stratigraphy but also helps to understand the evolution of climate, marine ecosystems and depositional environment during the Ludfordian. In doing so, the cause of this high positive δ13C excursion will be better understood

Molecular marker analysis tools as a cornerstone for the phylogenetic analysis of Hibiscus species in Egypt

Various hibiscus species such as Hibiscus rosa sinensis linn, Hibiscus malvaviscus arboreus, Althaea rosea, Hibiscus rosasinensis sp, Hibiscus schizopetalus, Hibiscus china rosa, Hibiscus sabdariffa L. and Hibiscus cannabinus L. (kenaf) were collected from Antoniades Gardens in Egypt. These species were very similar in morphology of the flowers and leaves, thus morphological markers traits use to identify these different Hibiscus species is limited and less accurat because they are strongly influenced with environmental conditions. Therefore, using molecular markers of DNA for plants considered to be more accurate than morphological markers. In this study we used eight primers from (RAPD), five (ISSR) primers and four (SSR) primers for the analysis on these species of Hibiscus. The results showed for all primers were as follows; the total number of the polymorphic fragments of RAPD, ISSR and SSR were 89, 72 and 15; respectively, with an average polymorphism about 97.75%, 98.61% and 100%; respectively. Moreover, the dendogram for the phylogenetic tree analysis of RAPD was divided into two main clusters, the first cluster has C7 (Hibiscus sabdariffa L) and the second cluster comprised the other species. For ISSR phylogenetic analysis, the dendrogram was divided into two main major clusters, the first cluster had C3 (althea rosea), C7 (Hibiscus sabdariffa L.) and C8 (hibiscus cannabinus) and the second cluster comprised the other species. Whereas, for SSR phylogenetic analysis, the dendrogram was divided into two main major clusters, the first cluster had C2 (Hibiscus malvaviscus arboreus) and the second group comprised the other species

Antioxidant and cytotoxic activities of Artemisia monosperma L. and Tamarix aphylla L. essential oils

Essential (volatile) oil from leaves of Artemisia monosperma L. belonging to family Asteraceae, and aerial parts of Tamarix aphylla L. (Athel) belonging to family Tamaricaceae were collected from the desert of Ha'il region, northern region of Saudi Arabia, hydro distilled by Clevenger apparatus and analysed by means of GC-MS techniques. Antioxidant activities of essential oils of A. monosperma and T. aphylla compared with ascorbic acid and butylated hydroxytoluene (BHT) as reference antioxidant compound were determined by method of DPPH radical scavenging assay and ABTS assay. In vitro screening of potential cytotoxicity of essential oils was also evaluated against human promyelocytic leukaemia cell lines (HL60 and NB4). The GC/MS analysis of A. monosperma essential oil resulted in identification of 61 components predominated mainly by β-Pinene as principal component (29.87%) and T. aphylla resulted in identification of 37 components of essential oil predominated mainly by 6,10,14- trimethyl-2-pentadecanone (21.43%) as principal component. Antioxidant activity as 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging and 2,2 -azino-bis (3-ethylbenzothiazoline-6-sulfonic acid (ABTS) increased with increasing essential oil concentrations of A. monosperma and T. aphylla (25, 50, 75, 100 and 200 μg mL-1). The most pronounced increases detected in the high concentrations of the two essential oils. Biologically, essential oil extracts exhibited cytotoxicity effects in dose dependent manner against human promyelocytic leukaemia cell lines (HL60 and NB4). In conclusion, A. monosperma and T. aphylla essential oils could be valuable source for cytotoxic agents with high safety and selective cytotoxicity profiles

Unified understanding of intrinsic and extrinsic controls of dissolved organic carbon reactivity in aquatic ecosystems

Despite our growing understanding of the global carbon cycle, scientific consensus on the drivers and mechanisms that control dissolved organic carbon (DOC) turnover in aquatic systems is lacking, hampered by the mismatch between research that approaches DOC reactivity from either intrinsic (inherent chemical properties) or extrinsic (environmental context) perspectives. Here we propose a conceptual view of DOC reactivity in which the combination of intrinsic and extrinsic factors controls turnover rates and determines which reactions will occur. We review three major types of reactions (biological, photochemical, and flocculation) from an intrinsic chemical perspective and further define the environmental features that modulate the expression of chemically inherent reactivity potential. Finally, we propose hypotheses of how extrinsic and intrinsic factors together shape patterns in DOC turnover across the land-to-ocean continuum, underscoring that there is no intrinsic DOC reactivity without environmental context. By acknowledging the intrinsic–extrinsic control duality, our framework intends to foster improved modeling of DOC reactivity and its impact on ecosystem services.publishedVersio

Unified understanding of intrinsic and extrinsic controls of dissolved organic carbon reactivity in aquatic ecosystems

Despite our growing understanding of the global carbon cycle, scientific consensus on the drivers and mechanisms that control dissolved organic carbon (DOC) turnover in aquatic systems is lacking, hampered by the mismatch between research that approaches DOC reactivity from either intrinsic (inherent chemical properties) or extrinsic (environmental context) perspectives. Here we propose a conceptual view of DOC reactivity in which the combination of intrinsic and extrinsic factors controls turnover rates and determines which reactions will occur. We review three major types of reactions (biological, photochemical, and flocculation) from an intrinsic chemical perspective and further define the environmental features that modulate the expression of chemically inherent reactivity potential. Finally, we propose hypotheses of how extrinsic and intrinsic factors together shape patterns in DOC turnover across the land-to-ocean continuum, underscoring that there is no intrinsic DOC reactivity without environmental context. By acknowledging the intrinsic–extrinsic control duality, our framework intends to foster improved modeling of DOC reactivity and its impact on ecosystem services

Effects of hospital facilities on patient outcomes after cancer surgery: an international, prospective, observational study

Background Early death after cancer surgery is higher in low-income and middle-income countries (LMICs) compared with in high-income countries, yet the impact of facility characteristics on early postoperative outcomes is unknown. The aim of this study was to examine the association between hospital infrastructure, resource availability, and processes on early outcomes after cancer surgery worldwide.Methods A multimethods analysis was performed as part of the GlobalSurg 3 study-a multicentre, international, prospective cohort study of patients who had surgery for breast, colorectal, or gastric cancer. The primary outcomes were 30-day mortality and 30-day major complication rates. Potentially beneficial hospital facilities were identified by variable selection to select those associated with 30-day mortality. Adjusted outcomes were determined using generalised estimating equations to account for patient characteristics and country-income group, with population stratification by hospital.Findings Between April 1, 2018, and April 23, 2019, facility-level data were collected for 9685 patients across 238 hospitals in 66 countries (91 hospitals in 20 high-income countries; 57 hospitals in 19 upper-middle-income countries; and 90 hospitals in 27 low-income to lower-middle-income countries). The availability of five hospital facilities was inversely associated with mortality: ultrasound, CT scanner, critical care unit, opioid analgesia, and oncologist. After adjustment for case-mix and country income group, hospitals with three or fewer of these facilities (62 hospitals, 1294 patients) had higher mortality compared with those with four or five (adjusted odds ratio [OR] 3.85 [95% CI 2.58-5.75]; p<0.0001), with excess mortality predominantly explained by a limited capacity to rescue following the development of major complications (63.0% vs 82.7%; OR 0.35 [0.23-0.53]; p<0.0001). Across LMICs, improvements in hospital facilities would prevent one to three deaths for every 100 patients undergoing surgery for cancer.Interpretation Hospitals with higher levels of infrastructure and resources have better outcomes after cancer surgery, independent of country income. Without urgent strengthening of hospital infrastructure and resources, the reductions in cancer-associated mortality associated with improved access will not be realised

A first update on mapping the human genetic architecture of COVID-19

peer reviewe

Study of digestive parameters in the threespine stickleback (Gasterosteus aculeatus) : interest as biomarkers

Avec le développement des activités anthropiques, les milieux aquatiques connaissent des modifications physico-chimiques, par exemple, la présence de contaminants chimiques et la perturbation des cycles de température (réchauffement climatique) peuvent avoir des effets sur les organismes qui y vivent. Ce travail s'inscrit donc dans un contexte qui couvre, à la fois le besoin de développement de nouveaux outils d'évaluation de la qualité des milieux aquatiques, exigé par des réglementations telle que la DCE, et l'apport de nouvelles connaissances sur les effets des multistress sur les organismes vivants. Plus précisément, nous nous sommes intéressés à différents paramètres du métabolisme énergétique et à leur intérêt en tant que nouveaux biomarqueurs, chez l'épinoche à trois épines (Gasterosteus aculeatus), espèce modèle en écotoxicologie. Ce travail de thèse vise : (i) à caractériser l'influence de paramètres biotiques et abiotiques sur les paramètres choisis, (ii) à préciser le schéma de réponse des enzymes digestives dans un contexte de multistress (exposition chronique à une très faible concentration de cadmium et/ou à un stress thermique), et (iii) à renseigner les conséquences de cette exposition multiple sur la reproduction de l'épinoche, en lien avec la modulation des paramètres liés à l'énergie. Les résultats obtenus démontrent que la température est le facteur de stress majeur avec des répercussions négatives sur la majorité des paramètres étudiés (i.e. paramètres de croissance, quelques paramètres du métabolisme énergétique, paramètres du stress oxydant et paramètres de reproduction des parents). Concernant le cadmium, celui-ci engendre des effets au niveau moléculaire (enzymes digestives) mais n'affecte pas les paramètres de la reproduction des poissons adultes. Cependant, des conséquences de l'exposition au cadmium sont néanmoins observées sur les descendants (capacité de survie). L'impact négatif du multistress sur les paramètres de reproduction de l'épinoche peut être dû à un investissement parental altéré, qui probablement a fait suite à une altération de l'un des paramètres en relation avec l'acquisition de l'énergie, telles que les enzymes digestives. Ainsi, les paramètres associés au métabolisme énergétique, et tout particulièrement à l'acquisition de l'énergie (digestion) montrent une sensibilité intéressante aux différents stress étudiés soulignant leur potentiel en tant que nouveaux biomarqueurs.In a large context of global warming (temperature increase), anthropogenic activities introduce significant amounts of organic and inorganic pollutants causing chemical and physical disruption on the aquatic ecosystems and there living organisms. This work is therefore part of a context that covers both the need for the development of new tools for assessing the quality of aquatic environments, as required by regulations such as the DCE, and the provision of new knowledge on multistress effects on living organisms. Specifically, we examined different energy metabolism parameters and their interest as novel biomarkers in the threespine stickleback (Gasterosteus aculeatus), a model species in ecotoxicology. This thesis aims to: (i) characterize the influence of biotic and abiotic parameters on the chosen parameters, (ii) to specify the response pattern of digestive enzymes in a multistress context (chronic exposure to a very low concentration of cadmium and / or thermal stress), and (iii) to study the consequences of this multiple exposure on sticklebacks' reproduction, in relation with the modulation of the energy parameters. Results show that temperature is the major stress factor with negative effects on most of the studied parameters (i.e. growth parameters, some parameters of energy metabolism, oxidative stress parameters and parents' reproduction parameters). Concerning cadmium, this chemical stress had effects at the molecular level (digestive enzymes) but did not affect the reproductive parameters of adult fish. However, consequences of cadmium exposure are nevertheless observed on the offspring (survival capacity). The negative impact of the double stress sticklebacks' reproduction may be due to an altered parental investment, which probably followed an alteration of one of the parameters in relation to energy acquisition, such as digestive enzymes. Thus, the parameters associated with energy metabolism, and especially with the acquisition of energy (digestion), show an interesting sensitivity to the different stresses studied, highlighting their potential as new biomarkers

The first continuous δ13C record across the Late Silurian Lau Event on Gotland, Sweden

The positive δ13C excursion associated with the Late Silurian Lau Event is recognized globally and is the most prominent carbon isotope excursion of the Phanerozoic. We present new δ13C data (195 samples) and the first continuous carbon isotope stratigraphy across the stratigraphic range of this bioevent based on two drill cores from Gotland, the informal type area for the Lau Event. The positive δ13C anomaly reaches a peak value of 9.01‰ in an interval correlated to the Icriodontid conodont Zone in the upper Eke Formation, an interval with generally impoverished fauna and strongly dominated by one single conodont species, Panderodus equicostatus, and a mass-occurrence of oncoids. The distinct morphology of this Late Ludfordian Carbon Isotope Excursion, including a well-defined rising limb, a plateau and a falling limb can be used for intercontinental correlation of the strata

Influence of a multistress (cadmium and temperature) on the reproduction of the three-spined stickleback (Gasterosteus aculeatus)

Human activities introduce significant amounts of organic and inorganic pollutants (trace metals) into aquatic environments. However, this contamination occurs within a large context that concerns the scientific community since the last decades: global warming. The complex nature of the interactions between toxic substances and temperature presents new challenges to improve the risk assessment for aquatic environments. Thus, the study of these interactions proves an essential priority for toxicologists. This study aims to evaluate the effect of chronic exposure to both chemical (cadmium) and physical stress (temperature) on the reproduction of a river fish widely used in ecotoxicology: three-spined stickleback (Gasterosteus aculeatus). For this, juvenile sticklebacks were exposed to 1µg.L-1 of cadmium for 4 months in semi-static conditions at two different temperatures, i.e. 16°C and 21°C. Water quality and cadmium concentration in the water were monitored throughout the experiment. Parameters such as somatic indices (height, weight, GSI) were measured at 15, 60, 90 and 120 days interval after cadmium exposure. Reproductive capacity was evaluated by performing several rounds of in vitro fertilization and monitoring of the offspring. The fertilization rate, mortality and birth defects were evaluated until the end of the larval stage (21 days post fertilization “dpf”). In total, 20 in vitro fertilizations were performed during this experiment with different results for each group. A decrease in fertilization rate was observed under the effect of temperature 21°C (84.79 ± 12%), which seems to be accentuated by the presence of cadmium (77.26 ± 31%). Similarly, the rate of embryonic and larval mortality seems to follow the same trend, with a rather large effect of temperature, especially in the presence of cadmium. Temperature 21°C in presence of cadmium delays the moment of hatching about two days compared to controls (10.5 ± 0.71 dpf Vs 8.67 ± 1.15 dpf). Several malformations were observed in all groups including the control group with predominance in groups from parents exposed to cadmium at 16°C (11.79 ± 10.8%). Our results showed fairly significant and worrying effects of a very low dose of cadmium (1µg.L-1) on the parents and their offsprings. Most studies reported in the literature on the effects of cadmium were demonstrated with much higher doses than used in our study. Further experiments are needed to complete and validate these results