High‐quality genomes reveal significant genetic divergence and cryptic speciation in the model organism Folsomia candida (Collembola)

The collembolan Folsomia candida Willem, 1902, is an important representative soil arthropod that is widely distributed throughout the world and has been frequently used as a test organism in soil ecology and ecotoxicology studies. However, it is questioned as an ideal “standard” because of differences in reproductive modes and cryptic genetic diversity between strains from various geographical origins. In this study, we present two high-quality chromosome-level genomes of F. candida, for the parthenogenetic Danish strain (FCDK, 219.08 Mb, N50 of 38.47 Mb, 25,139 protein-coding genes) and the sexual Shanghai strain (FCSH, 153.09 Mb, N50 of 25.75 Mb, 21,609 protein-coding genes). The seven chromosomes of FCDK are each 25–54% larger than the corresponding chromosomes of FCSH, showing obvious repetitive element expansions and large-scale inversions and translocations but no whole-genome duplication. The strain-specific genes, expanded gene families and genes in nonsyntenic chromosomal regions identified in FCDK are highly related to its broader environmental adaptation. In addition, the overall sequence identity of the two mitogenomes is only 78.2%, and FCDK has fewer strain-specific microRNAs than FCSH. In conclusion, FCDK and FCSH have accumulated independent genetic changes and evolved into distinct species since diverging 10 Mya. Our work shows that F. candida represents a good model of rapidly cryptic speciation. Moreover, it provides important genomic resources for studying the mechanisms of species differentiation, soil arthropod adaptation to soil ecosystems, and Wolbachia-induced parthenogenesis as well as the evolution of Collembola, a pivotal phylogenetic clade between Crustacea and Insecta.

Reproducibility of effects of the homeopathic dilutions 14x - 30x of gibberellic acid on growth of Lemna gibba L.

Background: Reproducibility of investigations in homeopathy is still challenging. Duckweed (Lemna gibba L.), a monocotyledonous waterplant which mostly reproduces vegetatively and therefore builds genetically identical clones, may be a suitable test system for standardised trials. Aims: This study investigated if formerly observed effects of gibberellic acid 14x – 30x on growth of Lemna gibba were reproducible. Methododology: Duckweed was grown in dilutions of gibberellic acid (14x–30x) as well as once succussed (c1) and unsuccussed (c0) water control. Area-related growth rate for day 0–7 was determined by a computerised image analysis system. Three series including five independent blinded and randomised experiments each were carried out in the same way as in the original study. Only time and conductor of experiments were modified. System stability was controled by three series of systematic negative control (SNC) experiments with the same set-up, but distilled and autoclaved water was used as the only test substance. According to the series with gibberellic acid, each serie of SNC experiments included five experiments. Full two-way ANOVA (α = 5%) was used for statistical analysis. Independent variables were treatment and experiment number, dependent variable was r(area) for day 0–7. Data of each experiment was normalised to its mean value to allow a better comparison between experiments. Only if the global ANOVA F-test was significant (p < 0.05) we compared the investigated groups with Fisher`s LSD test (protected Fisher`s LSD). Results: No specific effects of agitated dilutions of gibberellic acid were found in the first two replication series (p=0.263 and p=0.062). In the third serie with gibbous Lemna gibba L. we observed a significant effect (p=0.009) of the homeopathic treatment, however growth was increased in contrast to decreasing in the former study. Variability in experiments with gibberellic acid 14x – 30x was lower than in SNC experiments. The stability of the experimental system was verified by the SNC experiments. Conclusions: When designing new studies to investigate reproducibility, different physiological states of the test organism must be considered. Variability might be an interesting parameter to investigate effects of homeopathic remedies in basic research.

DILUCIÓN DE MIEL EN AGUA INDUCE HORMESIS EN LA ACTIVIDAD ANTIBACTERIANA SOBRE Staphylococcus aureus.

In pharmacology, hormesis is defined as the high efficacy of a drug at low doses and a decrease of efficacy at higher doses. In this study, the hormesis phenomenon on the antibacterial activity of honey was assessed. The activity of four honeys (A, D, C and D) were checked by agar plate diffusion method using S. aureus (ATCC 29213) as the test organism. Each honey was tested as follows; on the surface of an agar plate, five stainless steel cylinders with a diameter of 8,14 mm were radially disposed. Onto each cylinder 0,1 mL of the sample honey diluted in water at 50 – 25 - 12,5 -6,25 and 3,125 % v/v were placed. Plates were incubated at 35°C during 24 h. The surface of the cylinder diameter was set as reference antibacterial activity (Ra). The antibacterial activity of each honey was quantitated by the relationship between the surface of the inhibitory zone (Iz) and the surface of the reference activity (Iz/Ra). An increase in the antibacterial activity was observed at a concentration of water greater than 50% in honeys B and C. This hormetic behavior could be considered as indicator of the quality of the antibacterial activity of these honeys.

PROPUESTA DE UNA METODOLOGÍA PARA CUANTIFICAR LA ACTIVIDAD ANTIBACTERIANA DE LA MIEL

In this study a standardized method for objectively comparing the antibacterial activity of honey was developed. The assay was performed using a strain of S. aureus and four honeys that have been shown antibacterial activity against this strain. The antibacterial activity of honeys were checked by using an agar plate diffusion method using S. aureus (ATCC 29213) as the test organism. On the surface of each agar plate six stainless steel cylinders with a diameter of 8,14 mm were radially disposed. Onto each cylinder 0,1 mL of sample honey at 10% v/v was placed and all Petri dishes were incubated at 35°C during 24 h. Each sample were analyzed by triplicate. The surface of the cylinder diameter was set as reference antibacterial activity equivalent to minimal inhibitory concentration (MIC). The antibacterial activity of each honey was quantitated by the relationship between the surface of the inhibitory zone and the surface of the reference activity expressed as multiples of MIC (x MIC). The method allowed establishing differences between the bacterial activities of the different honeys tested and could be used for identifying honeys that could be employed with medicinal purpose for the treatments of wounds.

Acute toxic effects of uranium on two aquatic organisms, Zebrafish (Brachydanio rerio) and Ostracod (Cypridopsis vidua)

In this paper, we concentrate on the acute toxic effects of uranium on two aquatic organisms, Brachydanio rerio (B. rerio) and Cypridopsis vidua (C. vidua). We found that the toxicity of uranium on C. vidua was significantly greater than that of B. rerio. The results show that C. vidua has a higher sensitivity to uranium, even better than the commonly used test model organisms. In addition to its high sensitivity, C. vidua is a simple and cost-effective toxicological test organism. Therefore, C. vidua is an attractive alternative biological detection material. The acute toxicity results of the test are valuable for establishing water quality standards and protecting human health. At the same time, it enriches the relevant data of uranium on biological toxicity, provides clues for the study of the mechanism of toxicity, and deepens the understanding of the harm of uranium pollution to aquatic ecosystems.

Discharge of drill cuttings in the Arctic seas and responses of bottom fauna: bivalve Mytilus edulis L.

Drill cuttings are the largest solid waste of drilling operations. Onsite discharge of drill cuttings into the marine environment is relevant and can be permitted under certain conditions and regulations. Environmental impact of the on-site discharge of drill cuttings is poorly understood for the Arctic shelf. A risk assessment of the discharge is required and the related biological effects are estimated in bioassays on various local species. The sublethal screening tests of water-soluble fraction of drill cutting (WSF DC) were performed on a test-organism of the Barents Sea coast, blue mussel, Mytilus edulis. Physiological (oxygen consumption and filtration rates) and behavioral (shell gaping) activity of mussels was affected by the tested WSF DC above the certain threshold concentration. In general, biological effects of WSF DC might be assumed as a toxic stress of low intensity. Behavioral responses are the most sensitive in blue mussels and behavior of this sentinel organism is to be applied as a reliable indicator of environmental stress. Environmental impact from the drill cuttings of water based drilling fluid appears to be less toxic-stressful for M. edulis and many other bottom invertebrates than it might be expected from release of some drilling fluids.

Rapid and Sensitive Detection of Water Toxicity Based on Photosynthetic Inhibition Effect

To achieve rapid and sensitive detection of the toxicity of pollutants in the aquatic environment, a photosynthetic inhibition method with microalgae as the test organism and photosynthetic fluorescence parameters as the test endpoint was proposed. In this study, eight environmental pollutants were selected to act on the tested organism, Chlorella pyrenoidosa, including herbicides (diuron, atrazine), fungicides (fuberidazole), organic chemical raw materials (phenanthrene, phenol, p-benzoquinone), disinfectants (trichloroacetonitrile uric acid), and disinfection by-products (trichloroacetonitrile). The results showed that, in addition to specific PSII inhibitors (diuretic and atrazine), other types of pollutants could also quickly affect the photosynthetic system. The photosynthetic fluorescence parameters (Fv/Fm, Yield, α, and rP) could be used to detect the effects of pollutants on the photosynthetic system. Although the decay rate of the photosynthetic fluorescence parameters corresponding to the different pollutants was different, 1 h could be used as an appropriate toxicity exposure time. Moreover, the lowest respondent concentrations of photosynthetic fluorescence parameters to diuron, atrazine, fuberidazole, phenanthrene, P-benzoquinone, phenol, trichloroacetonitrile uric acid, and trichloroacetonitrile were 2 μg·L−1, 5 μg·L−1, 0.05 mg·L−1, 2 μg·L−1, 1.0 mg·L−1, 0.4 g·L−1, 0.1 mg·L−1, and 2.0 mg·L−1, respectively. Finally, diuron, atrazine, fuberidazole, and phenanthrene were selected for a comparison of their photosynthetic inhibition and growth inhibition. The results suggested that photosynthetic inhibition could overcome the time dependence of growth inhibition and shorten the toxic exposure time from more than 24 h to less than 1 h, or even a few minutes, while, the sensitivity of the toxicity test was not weakened. This study indicates that the photosynthetic inhibition method could be used for rapid detection of the toxicity of water pollutants and that algae fluorescence provides convenient access to toxicity data.

Design, Synthesis, Reactions and Antibacterial Properties of 2-hydrazinyl-3-methyl-6-nitroquinoxaline Derivatives

Aims: This aims of this study was to synthesis new quinoxaline-based heterocycles and study its antibacterial properties. Objective: This study was designed to synthesis some 3-methyl-6-nitroquinoxaline-2-one with hydrazine moiety, characterize the synthesized compounds, and study their antibacterial properties on some bacterial strains. Materials and Methods: Six 3-methylquinoxaline-2-hydrazone derivatives were synthesized by reacting 2-hydrazinyl-3-methyl-6-nitroquinoxaline with various substituted acetophenones. The hydrazones were screened for their potential antibacterial properties. Results: All the test compounds were found to possessed promising antibacterial properties against a panel of bacterial strains screened for this study. The MIC values exhibited by these compounds ranged between 0.0313 and 0.250 mg/mL. The lowest MBC of the compounds against the test organism was 0.0625 mg/mL while the highest MBC was 0.250 mg/mL. Discussion and Conclusion: The study concluded that all the compounds exhibited appreciable bactericidal effects against all the bacterial strains, which is an indication that such synthetic compounds possessed broad spectrum activities and such compounds could be useful in formulation of antibacterial compounds which could be used to mitigates infections caused by pathogens that are now developing resistance against the available antibiotics.

Evaluation of the chemical composition of aquatic environments with leaf litter decomposition of Eucalyptus urophylla S.T. Blake (Myrtaceae) and their toxicity in Allium cepa L. (Amaryllidaceae)

Allelochemicals from eucalyptus released into the environment, mainly by leaves, can have a toxic effect on local biota, including in aquatic environments. Therefore, the present study evaluates the toxic activity of the water containing leaves of Eucalyptus urophylla S.T. Blake (Myrtaceae) in decomposition using Allium cepa L. (Amaryllidaceae) as a test organism. The toxicity and the cytotoxicity evaluation were performed using onion bulbs (A. cepa). The toxicity was assessed by inhibiting root growth. The cytotoxicity was evaluated by using a comparison of the mitotic index (MI) and the negative control. The extraction of eucalyptus metabolites from water of the decomposition tests and creek water was performed by solid-phase microextraction (SPME). The chemical characterization was done by gas chromatography coupled to mass spectrometry (GC-MS). There was inhibition of the root growth of A. cepa, indicating toxicity of the compounds released in the water during the decomposition. The cytotoxicity tests did not indicate a toxic effect. However, there were identified some mutations, cell death, and morphological changes in the roots. 26 compounds were identified on samples of water acquired from decomposition tests.Fenchone, 2-ethyl-1-hexanol, cis-dihydrocarvone, and trans-dihydrocarvone were identified in all samples. The results highlight the importance of studies and monitoring of aquatic environments near eucalyptus.

Assessment of SnO2 Nanoparticles’ Impact on local Pichoclorum Atomus Growth Performance, Cell Morphology and Metabolites Content

Oxide nanoparticles are among the most used nanomaterials and have received considerable attention over their potential ecological effects. Increasing investigations report toxicity of certain oxide nanoparticles, however, there are also studies showing opposite results, highlighting the fact that these nanoparticles may differ in their toxicological effects, which depend on particle variety and size, test organism species, and test method. The current study investigates the ecotoxicity of SnO2 nanoparticles on a local marine algae isolate. Five different concentrations (1, 5, 25, 50 and 100mg/L) were tested and the culture was followed for 72h. Algae growth, morphology and metabolites were followed each 24h. The obtained data showed that the SnO2 presented a toxicity on the algae growth that was decreasing with the dose, with lower doses presenting more negative impacts than the higher doses. In parallel, the slow growth observed at 1-5 mg/L was explained by the dramatic damages caused by the SnO2 on the cell morphology, which was detected using the scanning electronic microscopy. Indeed, this low negative impact of higher concentrations of SnO2 (50-100mg/L) is explained by the high agglomeration of ten particles leading to reduced effect on the cell morphology and health. Furthermore, and in accordance with the morphological data, the metabolites analysis data revealed that SnO2 nanoparticles induced stress, which was manifested by an increase in the lipid content and decrease in the proteins, a metabolite that is involved in the algal growth.