Characterization of phytosiderophore secretion under Fe deficiency stress in Festuca rubra

In the present study we investigated the response to iron (Fe) deficiency in two cultivars of Festuca rubra L. (Rubina and Barnica) used in correction of chlorosis of fruit trees cultivated on calcareous soils. We found that a Fe-chelating compound, identified as 2-deoxymugineic acid (DMA), was secreted from the roots in response to Fe-deficiency in both cultivars. The amount of DMA secreted into solution increased with the development of Fe-deficiency. The secretion showed a distinct diurnal rhythm characterized by a secretion peak at between 2 and 5 hours after sunrise at 20°C. However, this secretion peak was delayed by 3 hour at low temperature (<10°C) and occurred 3 h earlier at high temperature (30°C). When water used for the collection of root exudates was pre-warmed (25°C) or pre-cooled (10°C), this led to an earlier or a delayed secretion compared to control (15°C) under the same air temperature, respectively. Short-term shading treatment did not affect the secretion pattern of DMA. These results demonstrate that the secretion time of DMA from the roots is, at least partly controlled by the temperature in the root environment. Overall, these findings suggest that the ability of Festuca rubra to prevent Fe chlorosis symptoms (`re-greening effect') of associated fruit trees is partially related to the secretion of DMA which increase Fe availability in calcareous soils.     

Characterization of beta-adrenergic receptors in cultured human and bovine endothelial cells

We used radioligand binding methods to characterize beta-adrenergic receptors on endothelial cells cultured from adult human iliac vein (HIVE) and bovine fetal aorta (BFAE). For comparison, we also studied the well-characterized C6 glioma cell line (C6). Both human and bovine endothelial cells showed specific saturable binding of [125I]iodopindolol. There was no difference in the binding affinity (KD) of iodopindolol to membranes from the three cell types. However, the beta-receptor density (Bmax) was greater on HIVE cells and BFAE cells than on C6 cells. Displacement of ligand from HIVE and BFAE cells by zinterol or from BFAE cells by ICI 89,406 was consistent with binding to the beta 2-subtype. In contrast, displacement of ligand from C6 cells by zinterol or ICI 89,406 was consistent with binding to both beta 1- and beta 2-subtypes. Exposing BFAE cells in culture to 10 microM isoproterenol for 6 h resulted in a 55% decrease in Bmax without a change in KD. We conclude that 1) human and bovine endothelial cells in culture contain a substantial population of beta-adrenergic receptors, which are predominantly of the beta 2-subtype, and 2) endothelial beta-receptors exhibit downregulation by beta-agonists in culture.     

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.