Review and analysis of the potential for glyphosate to interact with the estrogen,androgen and thyroid pathways

Glyphosate was recently evaluated for its potential to interact with the estrogen, androgen and thyroid (EAT) hormone pathways, including steroidogenesis, under the United States Environmental Protection Agency's (USEPA) Endocrine Disruptor Screening Program (EDSP), then by Germany, the rapporteur Member State who led the European Annex 1 renewal for glyphosate, and then by the European Food Protection Agency (EFSA) also as part of the Annex 1 renewal for glyphosate. Under the EDSP, 11 Tier 1 assays were run following the USEPA's validated 890‐series test guidelines and included five in vitro and six in vivo assays to evaluate the EAT pathways. Steroidogenesis was evaluated as part of the estrogen and androgen pathways. An up‐to‐date critical review has been conducted that considered results from the EDSP Tier 1 battery, guideline regulatory studies and an in‐depth analysis of the literature studies that informed an endocrine assessment. A strength of this evaluation was that it included data across multiple levels of biological organization, and mammalian and nonmammalian test systems. There was strong agreement across the in vitro and in vivo Tier 1 battery, guideline studies and relevant literature studies, demonstrating that glyphosate does not interact with EAT pathways including steroidogenesis. Based on an analysis of the comprehensive toxicology database for glyphosate and the literature, this review has concluded that glyphosate does not have endocrine‐disrupting properties through estrogen, androgen, thyroid and steroidogenic modes of action. © 2020 Society of Chemical Industry     

Preliminary assessment of large‐scale co‐culture of sandfish (Holothuria scabra) with the Babylon snail (Babylonia areolata) in earthen ponds and in raceways

Holothuria scabra (sandfish) and Babylonia areolata were trialed in two large‐scale co‐culture experiments. Experiment 1 assessed co‐culture in 4 × 400 m² earthen ponds where Babylonia were cultured in a central pen at a density of 400 individuals/m² with sandfish occupying the remaining pond space at 1.1 individuals/m². Sandfish grew from 18.20 ± 6.67 g to 119.03 ± 17.74 g in 92 days and Babylonia (fed trash fish in both experiments) grew from 0.90 ± 0.38 g to 4.93 ± 1.44 g, but Babylonia growth was not increased in co‐culture compared to monoculture. Water and sediment quality varied between co‐culture and monoculture ponds. Neither showed clear improvement due to sandfish culture. Experiment 2 compared non‐segregated sandfish‐Babylonia co‐culture with Babylonia monoculture in 20 m² concrete raceways. Sandfish were cultured at 2 individuals/m² and Babylonia at 300 individuals/m². Sandfish grew up to 1.91 g.day^?1 with 100% survival. Babylonia weight gain was significantly greater in co‐culture raceways (3.35 ± 0.64 g over 61 days), which was double that of Babylonia in monoculture. Substrate total N was reduced by 20% in co‐culture compared with monoculture (p = .032). This provisional study of commercial scale sandfish‐Babylonia co‐culture demonstrates culture compatibility, providing a basis for further system development.     

Effect of <Emphasis Type="Italic">Silene vulgaris</Emphasis> and Heavy Metal Pollution on Soil Microbial Diversity in Long-Term Contaminated Soil

In this study, we analysed the impact of heavy metals and plant rhizodeposition on the structure of indigenous microbial communities in rhizosphere and bulk soil that had been exposed to heavy metals for more than 150 years. Samples of the rhizosphere of Silene vulgaris and non-rhizosphere soils 250 and 450 m from the source of emission that had different metal concentrations were collected for analyses. The results showed that soils were collected 250 m from the smelter had a higher number of Cd-resistant CFU compared with the samples that were collected from 450 m, but no significant differences were observed in the number of total and oligotrophic CFU or the equivalent cell numbers between rhizosphere and non-rhizosphere soils that were taken 250 and 450 m from the emitter. Unweighted pair group method with arithmetic mean (UPGMA) cluster analysis of the denaturing gradient gel electrophoresis (DGGE) profiles, as well as a cluster analysis that was generated on the phospholipid fatty acid (PLFA) profiles, showed that the bacterial community structure of rhizosphere soils depended more on the plant than on the distance and metal concentrations. The sequencing of the 16S rDNA fragments that were excised from the DGGE gel revealed representatives of the phyla Bacteroidetes, Acidobacteria, Gemmatimonadetes, Actinobacteria and Betaproteobacteria in the analysed soil with a predominance of the first three groups. The obtained results demonstrated that the presence of S. vulgaris did not affect the number of CFUs, except for those of Cd-resistant bacteria. However, the presence of S. vulgaris altered the soil bacterial community structure, regardless of the sampling site, which supported the thesis that plants have a higher impact on soil microbial community than metal contamination.     

Why seedlings grow: influence of plant attributes

Successful forest restoration requires planting quality seedlings with optimal growth potential. Thus, nurseries need to produce seedlings with plant attributes that favor the best chance of successful establishment once they are field planted. From the mid-twentieth century on, research foresters have critically examined plant attributes that confer improved seedling growth under various restoration site conditions. This review examines the value of commonly measured seedling quality attributes (i.e., height, diameter, root mass, shoot-to-root ratio, drought resistance, freezing tolerance, nutrient status, root growth potential, and root electrolyte leakage) that have been recognized as important in explaining why seedlings with improved attributes have better growth after planting. Seedlings with plant attributes that fall within the appropriate range of values can increase the speed with which they overcome planting stress, initiate growth, and become “coupled” to the forest restoration site, thereby ensuring successful seedling establishment. Although planting high quality seedlings does not guarantee successful seedling establishment, it increases chances for successful establishment and growth.     

Flavonoid content and radical scavenging activity in fruits of Chinese dwarf cherry (<Emphasis Type="Italic">Cerasus humilis</Emphasis>) genotypes

The Chinese dwarf cherry (Cerasus humilis (Bge.) Sok.) is a small shrub with edible fruits. It is native to northern and western China. This species was included as a medicinal plant in the “Chinese Pharmacopeia” and has emerged as an economically important crop for fresh fruit consumption, processing into juice and wine and nutraceutical products as well. To gain a better understanding of flavonoid biosynthesis and help develop value added products and better cultivars with greater health benefits, we analyzed total flavonoid content (TFC), composition, and radical scavenging activities in fruit extracts of 16 Chinese dwarf cherry genotypes. Fruit peel TFC ranged from 33.5 to 72.8 mg/g RE·FW (RE: rutin equivalent, FW: fresh weight) while fruit flesh TFC ranged from 4.3 to 16.9 mg/g RE·FW. An HPLC analysis revealed that fruit extracts contained 14 flavonoids with considerable variation in their profiles across genotypes. The most abundant flavonoids in most genotypes were proanthocyanidin B1 (PA-B1), proanthocyanidin B2 (PA-B2), phloretin 2′-O-glucoside (PG), and phloretin 2′,4′-O-diglucoside (PDG). Principal component analysis showed that PG, PA-B1, and PA-B2 had large, positive factor loading values in the first principal component for each genotype. Increased scavenging activity of 2,2-diphenyl-1-picrylhydrazyl (DPPH) radicals was apparent in genotypes ‘Nongda 4’, ‘Nongda 3’, ‘Nongda 6’, ‘Wenfenli’, and ’10-32’, suggesting promising applications in the production of nutraceutical products. In summary, our results will aid in breeding, fruit processing, and developing medicinal uses of the Chinese dwarf cherry.     

Effects of soil drought stress on photosynthetic gas exchange traits and chlorophyll fluorescence in <Emphasis Type="Italic">Forsythia suspensa</Emphasis>

To clarify the changes in plant photosynthesis and mechanisms underlying those responses to gradually increasing soil drought stress and reveal quantitative relationships between photosynthesis and soil moisture, soil water conditions were controlled in greenhouse pot experiments using 2-year-old seedlings of Forsythia suspensa (Thunb.) Vahl. Photosynthetic gas exchange and chlorophyll fluorescence variables were measured and analyzed under 13 gradients of soil water content. Net photosynthetic rate (P _N), stomatal conductance (g _s), and water-use efficiency (W _UE) in the seedlings exhibited a clear threshold response to the relative soil water content (R _SWC). The highest P _N and W _UE occurred at R _SWC of 51.84 and 64.10%, respectively. Both P _N and W _UE were higher than the average levels at 39.79% ≤ R _SWC ≤ 73.04%. When R _SWC decreased from 51.84 to 37.52%, P _N, g _s, and the intercellular CO₂ concentration (C _i) markedly decreased with increasing drought stress; the corresponding stomatal limitation (L _s) substantially increased, and nonphotochemical quenching (N _PQ) also tended to increase, indicating that within this range of soil water content, excessive excitation energy was dispersed from photosystem II (PSII) in the form of heat, and the reduction in P _N was primarily due to stomatal limitation. While R _SWC decreased below 37.52%, there were significant decreases in the maximal quantum yield of PSII photochemistry (F _v/F _m) and the effective quantum yield of PSII photochemistry (ΦPSII), photochemical quenching (q _P), and N _PQ; in contrast, minimal fluorescence yield of the dark-adapted state (F ₀) increased markedly. Thus, the major limiting factor for the P _N reduction changed to a nonstomatal limitation due to PSII damage. Therefore, an R _SWC of 37.52% is the maximum allowable water deficit for the normal growth of seedlings of F. suspensa, and a water content lower than this level should be avoided in field soil water management. Water contents should be maintained in the range of 39.79% ≤ R _SWC ≤ 73.04% to ensure normal function of the photosynthetic apparatus and high levels of photosynthesis and efficiency in F. suspensa.     

Effects of continuous nitrogen addition on microbial properties and soil organic matter in a <Emphasis Type="Italic">Larix gmelinii</Emphasis> plantation in China

Continuous increases in anthropogenic nitrogen (N) deposition are likely to change soil microbial properties, and ultimately to affect soil carbon (C) storage. Temperate plantation forests play key roles in C sequestration, yet mechanisms underlying the influences of N deposition on soil organic matter accumulation are poorly understood. This study assessed the effect of N addition on soil microbial properties and soil organic matter distribution in a larch (Larix gmelinii) plantation. In a 9-year experiment in the plantation, N was applied at 100 kg N ha^?1 a^?1 to study the effects on soil C and N mineralization, microbial biomass, enzyme activity, and C and N in soil organic matter density fractions, and organic matter chemistry. The results showed that N addition had no influence on C and N contents in whole soil. However, soil C in different fractions responded to N addition differently. Soil C in light fractions did not change with N addition, while soil C in heavy fractions increased significantly. These results suggested that more soil C in heavy fractions was stabilized in the N-treated soils. However, microbial biomass C and N and phenol oxidase activity decreased in the N-treated soils and thus soil C increased in heavy fractions. Although N addition reduced microbial biomass and phenol oxidase activity, it had little effect on soil C mineralization, hydrolytic enzyme activities, δ¹³C value in soil and C–H stretch, carboxylates and amides, and C–O stretch in soil organic matter chemistry measured by Fourier transform infrared spectra. We conclude that N addition (1) altered microbial biomass and activity without affecting soil C in light fractions and (2) resulted in an increase in soil C in heavy fractions and that this increase was controlled by phenol oxidase activity and soil N availability.