Side effects of control treatment can conceal experimental data when studying stress responses to injection and psychological stress in mice

Routine laboratory procedures, such as handling or transporting animals or carrying out injections on animals, are stressful for animals but are necessary in many pre-clinical studies. Here, the authors show that multiple injections of the non-toxic vehicle cyclodextrin moderately increased plasma corticosterone concentrations in female BALB/c mice. Additionally, male BALB/c mice that had received a single intraperitoneal injection of harmless saline had an increased glucocorticoid response to a second saline injection. The authors found that female mice that had been exposed to an acute psychological stress session had a decreased glucocorticoid response to a second homotypic stressor. In contrast, multiple psychological stress sessions led to increased glucocorticoid release in female mice. Acute injection(s) of saline in male mice and of cyclodextrin in female mice led to transient lymphocytopenia. Further analysis showed that repeated stress-induced lymphocytopenia is glucocorticoid-dependent. The authors conclude that laboratory stress can affect physiological parameters in mice, potentially altering study results.     

Polypeptides from maize seedlings with protein kinase functions

Low molecular weight protein kinase from maize seedlings was isolated. The molecular weight of the enzyme was below 10 000. The enzyme preferentially utilized ATP and casein as donor and acceptor of phosphorus, respectively. Casein kinase was a cyclic nucleotide-independent, heparin-sensitive enzyme. The low molecular weight casein kinase was resolved into basic, neutral and slightly acidic peaks of activity by chromatofocussing.     

NO-dependent phototoxicity of Roussin's black salt against cancer cells.

A metal-nitrosyl complex, Roussin's black salt (RBS), releases nitric oxide after illumination. Approximately 3.7 NO molecules were released from one RBS molecule. Both short- and long-term effects of photogenerated NO on the two neoplastic cell lines: human (SK-MEL188) and mouse (S91) have been investigated. Exogenous NO from RBS was toxic to cells in a dose-dependent manner. Apoptotic damage predominates in the response to the injury, as shown by TUNEL assay. NO and its short-lived metabolites, but not other RBS photoproducts, are responsible for cellular death. RBS in dark was toxic to cells at concentrations above 1 microM. This relatively high cytotoxicity of RBS in the dark prevents its application as a systemic anticancer agent in vivo, unless it is applied locally.     

Structure of Syncytia Induced by Heterodera avenae Woll. in Roots of Susceptible and Resistant Wheat (Triticum aestivum L.)

The structure of syncytia induced by Heterodera avenae in roots of susceptible Triticum aestivum cv. ‘Capa’ and resistant wheat AUS 10894 was investigated. In susceptible plants the first syncytia were observed 4 days after placing the seedlings into a substrate containing nematode cysts. They were located on different root levels. In resistant plants syncytia were first found after 14 days, exclusively in the root maturity zone. In both wheats syncytia consisted mostly of stelar parenchymatic cells. The syncytia induced in roots of Triticum aestivum AUS 10894 were characterized by less immediate contact with the host tracheary elements than the syncytia induced in roots of susceptible Triticum aestivum cv. ‘Capa’. In both wheats a stimulation of pericycle cell divisions, giving rise to lateral roots, was found in parts where the syncytia developed.     

Differences between the conformations of nitrotyrosyl-248 carboxypeptidase A in the crystalline state and in solution

In solution, nitrocarboxypeptidase A, modified at tyrosyl-248, exhibits a nitrotyrosyl pK apparent of 6.3. In the crystalline state, the pK apparent is about 8.2. This change in ionization is consistent with the hypothesis that crystallization of the enzyme causes a displacement of tyrosine-248 away from the active site zinc ion.