Methylparaben induces malformations and alterations on apoptosis,oxidant–antioxidant status,ccnd1 and myca expressions in zebrafish embryos

Methylparabens (MP) are widely used as preservatives in cosmetics, pharmacy, and food industry. Although acute toxicity studies in animals indicated that parabens are not significantly toxic, the effects of chronic exposure under sublethal doses are still unknown and the number of related studies is limited. Our aim was to evaluate the effects of MP on the development of zebrafish embryos focusing on development, locomotor activity, oxidant–antioxidant status, apoptosis, and ccnd1 and myca expressions. The expressions of ccnd1 and myca were determined by RT‐PCR. Lipid peroxidation (LPO), nitric oxide (NO), and glutathione‐S‐transferase (GST) activities were determined spectrophotometrically. Apoptosis was determined using acridine orange staining. Locomotor activity was measured using touch‐evoked movement test. MP exposure increased malformations, LPO, apoptosis, ccnd1 and myca expressions, and decreased GST activities and NO levels compared with the control group. Our findings will lead to further understanding of the mechanism of MP toxicity, and merit further research.     

云锦杜鹃苯丙氨酸解氨酶基因的克隆及功能分析

苯丙氨酸解氨酶(phenylalaninammo-nialyase,PAL)是植物香气化合物中苯甲酸甲酯合成途径的关键酶.为探究云锦杜鹃Rhododendron fortunei RhPAL基因的功能,利用RT-PCR和cDNA末端快速扩增技术(rapid amplification of cDNA ends,RACE...     

Regeneration in the auditory system of nymphal and adult bush crickets Tettigonia viridissima

Regeneration and reestablishment of synaptic connections is an important topic in neurobiological research. In the present study, the regeneration of auditory afferents and the accompanying effects in the central nervous system are investigated in nymphs and adults of the bush cricket Tettigonia viridissima L. (Orthoptera: Tettigoniidae). In all animals in which the tympanal nerve is crushed, neuronal tracing shows a regrowth of the afferents into the prothoracic ganglion. This regeneration is seen in both adult and nymphal stages and starts 10–15 days after nerve crushing. Physiological recordings from the leg nerve indicate a recovery of tympanal fibres and a formation of functional connections to interneurones in the same time range. Electrophysiological recordings from the neck connective suggest additional contralateral sprouting of interneurones and the formation of aberrant connections. The regeneration processes of the tympanal nerve in nymphal stages and adults appear to be similar.     

Social environment affects the life history tactic of a phoretic mite

Phoretic animals use their hosts for travelling to habitat patches suitable for reproduction. Some species, such as the mite Poecilochirus carabi, are phoretic as juveniles and cannot leave their habitat once they reach adulthood. Previous work has shown that mites exercise choice over the habitat in which they will mature and reproduce based on abiotic parameters, but it is hitherto unknown whether their social environment influences this choice. By manipulating the composition of their conspecific company we show that P. carabi perform the adult moult in the presence of prospective mating partners only. Furthermore, juvenile male mites do not moult in the presence of an adult competitor. Recently‐moulted males are severely disadvantaged in fighting, so such delayed moulting may allow juveniles to increase their chances of surviving and reproducing. Our results clearly demonstrate a strong influence of the social environment on a phoretic’s habitat choice and life history.     

Phytoremediation of petroleum hydrocarbons by using a freshwater fern species Azolla filiculoides Lam

In this study, the phytoremediation capacity of Azolla filiculoides Lam. for the water resources contaminated with petroleum hydrocarbons was investigated. The plants were grown in nitrogen-free Hoagland nutrient solution containing 0.005%, 0.01%, 0.05%, 0.1%, 0.2%, 0.3%, 0.4%, and 0.5% crude oil under greenhouse conditions for 15 days. Although the growth rate of the plants were not negatively influenced by the presence of crude oil in the media for the concentration of 0.005% and 0.01% v/v, a gradual impeding effect of crude oil in the growth media has been observed at concentrations 0.05–0.1%. More than 0.1% crude oil in the growth medium ostensibly retarded the growth. For example, 0.2% oil in the media reduced growth approximately 50% relative to the control, and the presence of crude oil at concentrations 0.3% or more were lethal. The data about the percentage of plant growth, fresh weight increase and root growth clearly indicated that the tolerance level of A. filiculoides plants to crude oil ranges between 0.1% and 0.2%. In comparison to control samples, the biodegradation rate of total aliphatic and aromatic (phenathrene) hydrocarbons at 0.05–0.2% oil concentrations, was 94–73% and 81–77%, respectively. On the other hand, in case of further increases in oil concentration in media, i.e.; 0.3–0.5%, the biodegradation rate was still higher in the experimental samples, respectively 71–63% and 75–71%. The high biodegradation rates of petroleum hydrocarbons in the experimental samples suggested that A. filiculoides plants could be a promising candidate to be used for the phytoremediation of low crude oil contaminated precious freshwater resources.     

Anti- and pro-microbial roles of autophagy in plant-bacteria interactions

Macroautophagy/autophagy and the ubiquitin-proteasome system (UPS) are major proteolytic pathways that are increasingly recognized as battlegrounds during host-microbe interactions in eukaryotes. In plants, the UPS has emerged as central component of innate immunity and is manipulated by bacterial pathogens to enhance virulence. Autophagy has been ascribed a similar importance for anti-bacterial immunity in animals, but the contribution of autophagy to host-bacteria interactions remained elusive in plants. Here, we present and discuss our recent findings that revealed anti- and pro-bacterial roles of autophagy pathways during bacterial infection in the model plant Arabidopsis thaliana. We discovered that selective autophagy mediated by the autophagy cargo receptor AT4G24690/NBR1 limits growth of Pseudomonas syringae pv. tomato DC3000 (Pst) by suppressing the establishment of an aqueous extracellular space (‘water-soaking’). In turn, Pseudomonas employs the effector protein HopM1 to activate autophagy and proteasome degradation (‘proteaphagy’), thereby enhancing its pathogenicity. Thus, our study demonstrates that distinct selective autophagy pathways contribute to host immunity and bacterial pathogenesis during Pst infection and provide evidence for an intimate crosstalk between the proteasome and autophagy system in plant-bacterial interactions.     

Changes in photosynthetic rate and stress volatile emissions through desiccation‐rehydration cycles in desiccation‐tolerant epiphytic filmy ferns (Hymenophyllaceae)

Exposure to recurrent desiccation cycles carries a risk of accumulation of reactive oxygen species that can impair leaf physiological activity upon rehydration, but changes in filmy fern stress status through desiccation and rewatering cycles have been poorly studied. We studied foliage photosynthetic rate and volatile marker compounds characterizing cell wall modifications (methanol) and stress development (lipoxygenase [LOX] pathway volatiles and methanol) through desiccation–rewatering cycles in lower‐canopy species Hymenoglossum cruentum and Hymenophyllum caudiculatum, lower‐ to upper‐canopy species Hymenophyllum plicatum and upper‐canopy species Hymenophyllum dentatum sampled from a common environment and hypothesized that lower canopy species respond more strongly to desiccation and rewatering. In all species, rates of photosynthesis and LOX volatile emission decreased with progression of desiccation, but LOX emission decreased with a slower rate than photosynthesis. Rewatering first led to an emission burst of LOX volatiles followed by methanol, indicating that the oxidative burst was elicited in the symplast and further propagated to cell walls. Changes in LOX emissions were more pronounced in the upper‐canopy species that had a greater photosynthetic activity and likely a greater rate of production of photooxidants. We conclude that rewatering induces the most severe stress in filmy ferns, especially in the upper canopy species.     

Protective effect of magnesium supplementation on experimental 3-methyl cholantrene-induced fibrosarcoma and changes in tissue magnesium distribution during carcinogenesis in rats

In this study, we wanted to examine the effect of magnesium (Mg²⁺) supplementation on the experimental 3-methyl cholantrene (3-MC)-induced fibrosarcoma and alterations in (Mg²⁺) distribution in several tissues of the rats, during carcinogenesis. It was determined that serum and tissue (Mg²⁺) levels of the rats in (Mg²⁺)-supplemented diet group were higher than those of the rats in the (Mg²⁺)-nonsupplemented and control groups. The mean time of fibrosarcoma development for (Mg²⁺)-supplemented group was longer than (Mg²⁺)-nonsupplemented group (p<0.05). Symptoms of hypermagnesemia were not observed in any of the rats. These results suggests that dietary (Mg²⁺) supplementation may have a partial anticarcinogenic effect on experimental 3-MC-induced fibrosarcoma by prolongation of the latent period of carcinogenesis.