Exogenous salicylic acid alleviates water stress in watermelon plants

Salicylic acid (SA) has been considered to attenuate the effects of abiotic stresses on plants, including water deficit that intensely affects the growth and production of plants. The goal of this work was to evaluate the role of SA in the alleviation of water stress in watermelon seedlings on a morphophysiological and biochemical level. The experiment consisted of application of SA at concentrations of 0, 0.25, 0.50, 0.75 and 1.0 μmol L⁻¹ to leaves of watermelon seedlings grown in three levels of water retention (100%, 75% and 50% WRL). To evaluate the effect on morphophysiological and biochemical aspects, the plant height, leaf area, shoot and root dry weight, chlorophyll index, relative water content, electrolyte leakage, protein content, amino acids, proline, carbohydrates, sucrose and starch concentration variables were determined. All variables were influenced by the SA concentrations and WRL, with statistically significant interaction between these factors for all except root dry weight. SA promotes increases in the concentration of organic solutes and reduces the rate of electrolyte leakage in watermelon seedlings, thus, supporting metabolism and growth of plants under stress conditions resulting from water deficit.     

Interplay between oncogene-induced DNA damage response and heterochromatin in senescence and cancer

Two major mechanisms have been causally implicated in the establishment of cellular senescence: the activation of the DNA damage response (DDR) pathway and the formation of senescence-associated heterochromatic foci (SAHF). Here we show that in human fibroblasts resistant to premature p16(INK4a) induction, SAHF are preferentially formed following oncogene activation but are not detected during replicative cellular senescence or on exposure to a variety of senescence-inducing stimuli. Oncogene-induced SAHF formation depends on DNA replication and ATR (ataxia telangiectasia and Rad3-related). Inactivation of ATM (ataxia telangiectasia mutated) or p53 allows the proliferation of oncogene-expressing cells that retain increased heterochromatin induction. In human cancers, levels of heterochromatin markers are higher than in normal tissues, and are independent of the proliferative index or stage of the tumours. Pharmacological and genetic perturbation of heterochromatin in oncogene-expressing cells increase DDR signalling and lead to apoptosis. In vivo, a histone deacetylase inhibitor (HDACi) causes heterochromatin relaxation, increased DDR, apoptosis and tumour regression. These results indicate that heterochromatin induced by oncogenic stress restrains DDR and suggest that the use of chromatin-modifying drugs in cancer therapies may benefit from the study of chromatin and DDR status of tumours.     

Relationships between environmental gradients and geographic variation in the intraspecific body size of three species of frogs (Anura)

The relationship between environmental gradients and patterns of geographic variation in body size has been a controversial topic for ectothermic organisms globally. To examine whether the patterns that generally hold in more temperate species also hold for tropical ones, we examined the intraspecific body size variation in three species of Neotropical frogs, Dendropsophus minutus, Hypsiboas faber and Physalaemus cuvieri, along different environmental gradients (e.g. temperature, precipitation and topography). We analysed four competing hypotheses: (i) the water availability hypothesis that predicts a negative relationship between body size and precipitation; (ii) the heat balance hypothesis that predicts a negative relationship between body size and temperature; (iii) the topography hypothesis that predicts a negative relationship between body size and altitude; and (iv) the mixed‐effect hypothesis that predicts that individuals occurring in wet and cold sites would be larger than individuals occurring in dry and warm sites. The spatial pattern of geographic variation in body size among populations of H. faber was associated with the mixed‐effect hypothesis. In localities with low precipitation seasonality and cold conditions, H. faber individuals were larger than in localities with high precipitation seasonality and warm conditions. Variation in the body size of D. minutus was the opposite of that predicted by the heat balance hypothesis. Individuals in localities with high temperatures were larger than in localities with low temperatures. On the other hand, variation in the body size of P. cuvieri was not associated with the variables used in this study. Our results suggest that intraspecific variation in anuran body size is more dependent on species‐specific response than on the region (i.e. temperate or tropical) where they occur.     

First outbreak reported caused by Erysipelothrix species strain 2 in turkeys from poultry-producing farms in Brazil

Purpose

The aims of this study were to report the first isolation of Erysipelothrix sp. strain 2 (ES2) associated with clinical signs of diseases as well as mortality in turkeys and identify the antimicrobial resistance of the isolates.

Methods

We evaluated 118 farms for bacteriological analysis and TaqMan real-time PCR to identify the microorganism in different organs. After this, we made the epidemiological analysis between the positive flocks and the mortality mean. We performed the sequencing of the 16S rRNA region and the assessment of antimicrobial resistance.

Results

We have identified 18 (15.25%) as ES2-positive flocks, without any other species from the same genus being found. After analysing the organ samples, we found liver as the organ of choice for the isolation of the ES2. The sequencing of 16S rRNA region of ES2 identified high homology with E. tonsillarum and E. rhusiopathiae, suggesting that it is not the best-suited target to identify this species. We have found a positive association between isolation of the bacteria in organs and flocks’ mortality. Positive flocks had a mortality mean rate of 6.87%, which is significantly greater than 3.76% in negative flocks. Ill turkeys had gross lesions of generalized septicaemia. The bacterial isolates showed high resistance to fosfomycin and trimethoprim/sulfamethoxazole and sensibility to norfloxacin, amoxicillin and lincomycin/spectinomycin.

Conclusion

This is the first study in the world that addressed ES2 as the causative agent of erysipelas in turkey.

     

Co-Inoculation of Common Bean with Rhizobium and Azospirillum Enhance the Drought Tolerance

Russian Journal of Plant Physiology - Plant growth-promoting rhizobacteria (PGPR) have been shown to reduce the negative effects of drought on numerous plant species, but these effects are unknown...