Compositional changes of selected amino acids,organic acids,and soluble sugars in the xylem sap of N,P, or K‐deficient tomato plants

Xylem sap plays a major role in long‐distance transport of water, nutrients, and metabolites. However, there is little information on the behavior of metabolites in mineral‐deficient xylem sap. For this reason, the time‐dependent changes in selected metabolites (amino acids, organic acids, and soluble sugars) from tomato xylem sap in response to nitrogen (N), phosphorus (P), or potassium (K)‐deficient condition were investigated. Tomato plants (Solanum lycopersicum L.) were grown hydroponically in liquid culture under three different mineral regimes: N‐deficient [0.5 mM Ca(NO₃)₂ and 0.5 mM KNO₃], P‐deficient (0.05 mM KH₂PO₄), and K‐deficient (0.5 mM KNO₃), respectively. Xylem sap was collected at 10:00 am after 1, 5, 15, and 30 d, and the selected metabolites were analyzed with liquid chromatography. All N, P, or K deficiencies led to a substantial increase in metabolites in the xylem sap. The predominant amino acid in the xylem sap was glutamine and, interestingly, all mineral deficiencies resulted in a substantial amount of γ‐aminobutyric acid (GABA). Additionally, organic acids (citrate and malate) and soluble sugars were strongly increased in all mineral deficiencies, and, in particular, the level of shikimate was greatly affected by N deficiency. Based on these data, it is necessary to clearly elucidate an unknown event taking place in xylem loading in a variety of environmental impacts, and we are now studying to expand our knowledge on metabolic and proteomic responses using GC‐MS and LC‐MS.     

Case–control study on risk factors associated with Brucella Melitensis in goat farms in Peninsular Malaysia

Caprine brucellosis is a bacterial zoonotic infection affecting goats especially in developing countries all over the world. In Malaysia, the risk factors associated with this infection in farms have not been studied. A case–control study was carried out in goat farms in four states of Malaysia to elucidate the risk factors associated with the infection on the farms using structured questionnaires and face-to-face interviews. Results indicate that the introduction of new animals (OR?=?5.25; 90 % CI?=?1.46, 18.88), younger age category of farms (OR?=?5.53; 90 % CI?=?1.09, 21.66), and farms with single breed of goats (OR?=?8.50; 90 % CI?=?1.27, 41.97) were significant risk factors for brucellosis. In order to control brucellosis or possibly eradicate it in goat farms, these factors need to be dealt with. Enforcing stringent importation protocols or complete ban of goat importation from brucellosis endemic countries will help reduce risk of introducing new infection into the country.