Diversity of rhizobia, symbiotic effectiveness, and potential of inoculation in Acacia mearnsii seedling production

Black wattle (Acacia mearnsii) is a forest species of significant economic importance in southern Brazil; as a legume, it forms symbiotic associations with rhizobia, fixing atmospheric nitrogen. Nonetheless, little is known about native rhizobia in soils where the species is cultivated. Therefore, this study aimed to evaluate the diversity and symbiotic efficiency of rhizobia nodulating A. mearnsii in commercial planting areas and validate the efficiency of a potential strain in promoting seedling development. To this end, nodules were collected from four A. mearnsii commercial plantations located in Rio Grande do Sul State, southern Brazil. A total of 80 rhizobia isolates were obtained from black wattle nodules, and thirteen clusters were obtained by rep-PCR. Higher genetic diversity was found within the rhizobial populations from the Duas Figueiras (H' = 2.224) and Seival (H' = 2.112) plantations. Twelve isolates were evaluated belonging to the genus Bradyrhizobium, especially to the species Bradyrhizobium guangdongense. The principal component analysis indicated an association between rhizobia diversity and the content of clay, Ca, Mg, and K. Isolates and reference strains (SEMIA 6163 and 6164) induced nodulation and fixed N via symbiosis with black wattle plants after 60 days of germination. The isolates DF2.4, DF2.3, DF3.3, SEMIA 6164, SEMIA 6163, CA4.3, OV3.4, and OV1.4 showed shoot nitrogen accumulation values similar to the N + control treatment. In the second experiment (under nursery conditions), inoculation with the reference strain SEMIA 6164 generally improved the growth of A. mearnsii seedlings, reinforcing its efficiency even under production conditions.

TIME COURSE OF THE DEVELOPMENT OF IMMUNOTHROMBOSIS DURING COVID-19 HOSPITALIZATION

Introduction

Hypercoagulability in COVID-19 has been attributed to immunothrombosis, a process that involves the formation of neutrophils extracellular traps (NETs). The moment of the COVID-19 evolution in which immunothrombosis mechanisms are triggered is not established. Aim: To describe the kinetics of NETs release during COVID-19 hospitalization associating with thrombosis and death.

Methods

We quantified citrullinated H3 and inflammatory cytokines (TNF-α, IL-6), markers of NETs release, on 4 time points during COVID-19 hospitalization (admission, day 4, day 8 and last day) between May and July 2020. The association between changes in these markers levels and clinical outcomes was determined.

Results

101 patients were included, the median days in-hospital were 15, 62% were men, 27% were obese, 43% were diabetic, 54% were hypertensive, 59% were critically ill, 11% had a thrombotic event and 21% died. IL-6 levels were high on admission in survivors (median 25.32, IQR 24.19-28.15) and non-survivors (median 24.19, IQR 12.51-27.19), but gradually decreased on day 4 (median 12.07, IQR 6.32-17.81), day 8 (median 9.34, IQR 5.18-17.59) and last day (median 8.64, IQR 4.81-14.89) in survivors. TNF-α levels remained 2 times higher in non-survivors: admission (median 1.60, IQR 0.64-2.26), day 4 (median 1.78, IQR 1.02-2.60), day 8 (median 1.65, IQR 0.93-2.5), last day (median 2.41, IQR 1.31-4.06); than in survivors: admission (median 0.81, IQR 0.52-1.26), day 4 (median 0.84, IQR 0.44-1.16), day 8 (median 0.72, IQR 0.44-1.24), last day (median 0.69, IQR 0.4-1.14). CitH3 levels were similar between non-survivors at the beginning of hospitalization: admission (median 1.03, IQR 0.43-4.34), day 4 (median 1.1, IQR 0.65-3.45); as for survivors: admission (median 1.20, IQR 0.45-2.60), day 4 (median 1.27, IQR 0.64-3.29). On day 8, citH3 increased by 3-fold (median 3.80, IQR 1.98-10.15) in non-survivors and 2-fold (median 2.60, IQR 1.22-5.01) in survivors. While IL-6 and TNF-α levels were similar between patients with and without thrombosis, citH3 levels increased shortly on day 4, before the occurrence of a thrombotic event: admission (median 1.64, IQR 0.44-4.14), day 4 (median 3.21, IQR 2.57-9.31); but it didn't change on non-thrombotic event patients: admission (median 1.05, IQR 0.44-2.50), day 4 (median 1.06, IQR 0.58-2.95).

Conclusion

Markers of inflammation and immunothrombosis were associated with poor outcomes in COVID-19; however, these disorders were detected in different moments during COVID-19 course. While an increased inflammatory response was observed since the beginning of hospitalization, markers of immunothrombosis arose latter during the course of the disease. Acknowledgment of the time-course of immunothrombosis development in COVID-19 is important for planning therapeutic strategies against this pathological process.

Antiproliferative activity of essential oils from three plants of the Brazilian Cerrado: Campomanesia adamantium (Myrtaceae), Protium ovatum (Burseraceae) and Cardiopetalum calophyllum (Annonaceae)

Essential oils, which may be extracted from several parts of plants, have different biological activities. The Brazilian Cerrado has a large variety of plants that yield essential oils, even though many have not been studied yet. Taking into account the biodiversity of this biome, this study aimed at evaluating the antiproliferative activity of essential oils extracted from three species of plants of the Cerrado in Goiás state: Campomanesia adamantium (Cambess.) O. Berg, Protium ovatum (Engl. in Mart.) and Cardiopetalum calophyllum (Schltdl.). Essential oils were extracted from both C. adamantium and C. calophyllum leaves and from P. ovatum leaves and green fruits by hydrodistillation carried out by a Clevenger-type apparatus. The chemical composition of the essential oils was determined by Gas Chromatography coupled to Mass Spectrometry (GC-MS). The following major chemical constituents were identified in the essential oils under investigation: β-myrcene (62.00%), spathulenol (28.78%), germacrene-B (18.27%), β-caryophyllene oxide (16.40%), β-caryophyllene (14.00%), α-pinene (11.30%), viridiflorol (9.99%), limonene (7.30%) and (Z,E)-pharnesol (6.51%). The antiproliferative activity was evaluated in different human tumor cell lines: breast adenocarcinoma (MCF-7), cervical adenocarcinoma (HeLa) and glioblastoma (M059J). A normal human cell line was included (GM07492A, lung fibroblasts). Results showed that essential oils from C. adamantium leaves got the lowest values of IC50 in all strains of tumor cells under evaluation. They were significantly lower than the ones of the normal cell line, an evidence of selectivity. It is worth mentioning that this is the first report of the antiproliferative activity of essential oils from C. adamantium , P. ovatum and C. calophyllum against human tumor cells.

Composition and effect of salt on rheological and gelation properties of Enterolobium contortisilliquum gum exudate

The composition, structure and rheological properties and metal ions interaction with Enterolobium contortisilliquum gum were investigated. This gum contains galactose, arabinose, rhamnose and glucuronic acid as main monosaccharide components. 13C nuclear magnetic resonance spectroscopy revealed that the anomeric composition is similar to the Enterolobium cyclocarpum exudate, however no 4-O-methylglucuronic acid was detected for E. contortisilliquum. The rheological experiment resulted in a very similar flow behaviour to that found for E. cyclocarpum gum. The empirical stiffness parameter, B was determined (B=0.090) and suggested that the polysaccharide possesses semi-flexible chains. Cation affinity of the gum aqueous solution was determined by intrinsic viscosity measurements and gelation. The melting temperature of gels pointed to a charge/ionic radius ratio dependence for metal ions. Thermodynamic parameters (enthalpy and entropy) at the melting temperature were also calculated.