Influence of water stress on photosynthesis and variable chlorophyll fluorescence of potato leaves

Net photosynthetic rate (P_N), productivity and the first phases of the fluorescence induction curve were investigated in leaves of two potato cultivars exposed to water stress. Water stress applied to potato plants at the beginning of their development (planting-bud formation) increased productivity but decreased P_N and variable fluorescence (F_v) of leaves. The short-term influence of water stress on the same plants also diminished the F_v.     

Inducible and Reversible Lentiviral and Recombination Mediated Cassette Exchange (RMCE) Systems for Controlling Gene Expression

Manipulation of gene expression to invoke loss of function (LoF) or gain of function (GoF) phenotypes is important for interrogating complex biological questions both in vitro and in vivo. Doxycycline (Dox)-inducible gene expression systems are commonly used although success is often limited by high background and insufficient sensitivity to Dox. Here we develop broadly applicable platforms for reliable, tightly controlled and reversible Dox-inducible systems for lentiviral mediated generation of cell lines or FLP Recombination-Mediated Cassette Exchange (RMCE) into the Collagen 1a1 (Col1a1) locus (FLP-In Col1a1) in mouse embryonic stem cells. We significantly improve the flexibility, usefulness and robustness of the Dox-inducible system by using Tetracycline (Tet) activator (Tet-On) variants which are more sensitive to Dox, have no background activity and are expressed from single Gateway-compatible constructs. We demonstrate the usefulness of these platforms in ectopic gene expression or gene knockdown in multiple cell lines, primary neurons and in FLP-In Col1a1 mouse embryonic stem cells. We also improve the flexibility of RMCE Dox-inducible systems by generating constructs that allow for tissue or cell type-specific Dox-inducible expression and generate a shRNA selection algorithm that can effectively predict potent shRNA sequences able to knockdown gene expression from single integrant constructs. These platforms provide flexible, reliable and broadly applicable inducible expression systems for studying gene function.     

Evidence of ochratoxin A-detoxification activity of rumen fluid,intestinal fluid and soil samples as well as isolation of relevant microorganisms from these environments

Dietary ochratoxin A (OTA) has a negative impact on performance of chickens and pigs. To avoid losses in animal production through intake of this mycotoxin and to prevent carry over to humans, strategies for counteracting have to be developed. In contrast to physical and chemical detoxification methods inactivation of ochratoxins by enzymatic reactions represent a very specific and gentle process. For the development of a new feed additive various environments have been screened for microorganisms with the capability of degrading or of cleaving the phenylalanine-moiety of ochratoxin A. Two OTA-degrading bacterial strains were isolated from rumen fluid and four pure cultures capable of cleaving ochratoxin A were obtained from pig intestine. The highest number of ochratoxin A degrading strains were found amongst aerobic bacteria which have mainly been isolated from soil.     

Salbutamol inhibits ubiquitin-mediated survival motor neuron protein degradation in spinal muscular atrophy cells

Spinal muscular atrophy (SMA) is a common autosomal recessive neuromuscular disorder that is currently incurable. SMA is caused by decreased levels of the survival motor neuron protein (SMN), as a result of loss or mutation of SMN1. Although the SMN1 homolog SMN2 also produces some SMN protein, it does not fully compensate for the loss or dysfunction of SMN1. Salbutamol, a β2-adrenergic receptor agonist and well-known bronchodilator used in asthma patients, has recently been shown to ameliorate symptoms in SMA patients. However, the precise mechanism of salbutamol action is unclear. We treated SMA fibroblast cells lacking SMN1 and HeLa cells with salbutamol and analyzed SMN2 mRNA and SMN protein levels in SMA fibroblasts, and changes in SMN protein ubiquitination in HeLa cells. Salbutamol increased SMN protein levels in a dose-dependent manner in SMA fibroblast cells lacking SMN1, though no significant changes in SMN2 mRNA levels were observed. Notably, the salbutamol-induced increase in SMN was blocked by a protein kinase A (PKA) inhibitor and deubiquitinase inhibitor, respectively. Co-immunoprecipitation assay using HeLa cells showed that ubiquitinated SMN levels decreased in the presence of salbutamol, suggesting that salbutamol inhibited ubiquitination. The results of this study suggest that salbutamol may increase SMN protein levels in SMA by inhibiting ubiquitin-mediated SMN degradation via activating β2-adrenergic receptor-PKA pathways.     

Exploring the binding mechanism of HDAC8 selective inhibitors: Lessons from the modification of Cap group

The abnormal expression of histone deacetylase 8 (HDAC8) has been reported to associate with various cancer entities (colon, breast cancer, pancreas, etc.) as well as parasitic diseases, making HDAC8 gradually develop into an attractive and potential therapeutic target. Among the various design strategies of selective HDAC8 inhibitors (modification of Cap, Linker, or zinc binding group regions), the optimization of Cap region has aroused great interest among the researchers. However, the detailed information underlying how the modification of Cap region influences the inhibitory activities is still unclear, and in this study, compounds 2c, 3g, and 3n were selected to explore the differences in binding mechanisms brought by Cap modifications via various computational approaches at the atomic level. Five residues (Y293, H167, D254, D165, and M261) have a large difference in energy contributions to the constructed systems, and the subpocket formed by Y293 and M261 could interact with Cap groups, triggering the differences in the energy contributions of the residues (H167, D254, and D165) located in metal-catalytic center. In summary, the compounds 2c, 3g, and 3n were selected as molecular probes to explore the binding mechanism, and the residues (Y293 and M261) forming the subpocket should be paid special attention in the design and synthesis of novel selective HDAC8 inhibitors.