Effects of chronic tramadol exposure on the zebrafish brain: a proteomic study

Tramadol hydrochloride (TH), has become the most prescribed opioid worldwide. However, its neurotoxicity and abuse potential are not well documented. In the present study, TH administration induced abnormal behavior and body and brain mean weight loss. Two principal metabolites O- and N-desmethyltramadol were detected in the brain tissue, and N-desmethyltramadol was the main metabolite produced. A total of 30 differential protein spots were identified using semi-quantitative 2D-PAGE and proteomic analyses, and classified into 13 categories, in which subtypes of 14-3-3 proteins, creatine kinase, ATP synthase beta chain, and tubulin were identified at the separated location on the gels 3, 3, 4, and 11 times respectively. Many TH responsive proteins have functions related to oxidative stress, including 14-3-3 proteins, creatine kinase BB, ubiquitin carboxy-terminal hydrolase L-1, ATP synthase, synaptosome-associated protein, tubulin and actin. Irrespective of oxidative damage, other pathways affected include apoptosis, energy metabolism, signal disorders, and cytoskeletal structure. Ultrastructural observation of mitochondria showed a series of morphological changes in the case of TH exposure.     

Temporal Coherence of Chlorophyll a during a Spring Phytoplankton Bloom in Xiangxi Bay of Three‐Gorges Reservoir,China

Algal bloom phenomenon was defined as “the rapid growth of one or more phytoplankton species which leads to a rapid increase in the biomass of phytoplankton”, yet most estimates of temporal coherence are based on yearly or monthly sampling frequencies and little is known of how synchrony varies among phytoplankton or of the causes of temporal coherence during spring algal bloom. In this study, data of chlorophyll a and related environmental parameters were weekly gathered at 15 sampling sites in Xiangxi Bay of Three‐Gorges Reservoir (TGR, China) to evaluate patterns of temporal coherence for phytoplankton during spring bloom and test if spatial heterogeneity of nutrient and inorganic suspended particles within a single ecosystem influences synchrony of spring phytoplankton dynamics. There is a clear spatial and temporal variation in chlorophyll a across Xiangxi Bay. The degree of temporal coherence for chlorophyll a between pairs of sites located in Xiangxi Bay ranged from –0.367 to 0.952 with mean and median values of 0.349 and 0.321, respectively. Low levels of temporal coherence were often detected among the three stretches of the bay (Down reach, middle reach and upper reach), while high levels of temporal coherence were often found within the same reach of the bay. The relative difference of DIN between pair sites was the strong predictor of temporal coherence for chlorophyll a in down and middle reach of the bay, while the relative difference in Anorganic Suspended Solids was the important factor regulating temporal coherence in middle and upper reach. Contrary to many studies, these results illustrate that, in a small geographic area (a single reservoir bay of approximately 25 km), spatial heterogeneity influence synchrony of phytoplankton dynamics during spring bloom and local processes may override the effects of regional processes or dispersal. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

The regulation of necroptosis by ubiquitylation

Necroptosis is a programmed necrosis that is mediated by receptor-interacting protein kinases RIPK1, RIPK3 and the mixed lineage kinase domain-like protein, MLKL. Necroptosis must be strictly regulated to maintain normal tissue homeostasis, and dysregulation of necroptosis leads to the development of various inflammatory, infectious, and degenerative diseases. Ubiquitylation is a widespread post-translational modification that is essential for balancing numerous physiological processes. Over the past decade, considerable progress has been made in the understanding of the role of ubiquitylation in regulating necroptosis. Here, we will discuss the regulatory functions of ubiquitylation in necroptosis signaling pathway. An enhanced understanding of the ubiquitylation enzymes and regulatory proteins in necroptotic signaling pathway will be exploited for the development of new therapeutic strategies for necroptosis-related diseases.

     

Ku and DNA-dependent Protein Kinase Dynamic Conformations and Assembly Regulate DNA Binding and the Initial Non-homologous End Joining Complex

DNA double strand break (DSB) repair by non-homologous end joining (NHEJ) is initiated by DSB detection by Ku70/80 (Ku) and DNA-dependent protein kinase catalytic subunit (DNA-PKcs) recruitment, which promotes pathway progression through poorly defined mechanisms. Here, Ku and DNA-PKcs solution structures alone and in complex with DNA, defined by x-ray scattering, reveal major structural reorganizations that choreograph NHEJ initiation. The Ku80 C-terminal region forms a flexible arm that extends from the DNA-binding core to recruit and retain DNA-PKcs at DSBs. Furthermore, Ku- and DNA-promoted assembly of a DNA-PKcs dimer facilitates trans-autophosphorylation at the DSB. The resulting site-specific autophosphorylation induces a large conformational change that opens DNA-PKcs and promotes its release from DNA ends. These results show how protein and DNA interactions initiate large Ku and DNA-PKcs rearrangements to control DNA-PK biological functions as a macromolecular machine orchestrating assembly and disassembly of the initial NHEJ complex on DNA.     

miR-194-5p negatively regulates the proliferation and differentiation of rabbit skeletal muscle satellite cells

Molecular and Cellular Biochemistry - Skeletal muscle satellite cells (SMSCs), also known as a multipotential stem cell population, play a crucial role during muscle growth and regeneration. In...     

Oligomerization and regulated proteolytic processing of angiopoietin-like protein 4

Angiopoietin-like protein 4 (Angptl4) is a recently identified circulating protein expressed primarily in adipose tissue and liver. Also known as peroxisome proliferator-activated receptor (PPAR)-gamma angiopoietin-related, fasting induced adipose factor, and hepatic fibrinogen/angiopoietin-related protein, recombinant Angptl4 causes increase of plasma very low density lipoprotein levels by inhibition of lipoprotein lipase activity. Similar to angiopoietins and other angiopoietin-like proteins, Angptl4 contains an amino-terminal coiled-coil domain and a carboxyl-terminal fibrinogen-like domain. We report here that Angptl4 is evolutionarily conserved among several mammalian species and that full-length Angptl4 protein is an oligomer containing intermolecular disulfide bonds. Oligomerized Angptl4 undergoes proteolytic processing to release its carboxyl fibrinogen-like domain, which circulates as a monomer. Angptl4's N-terminal coiled-coil domain mediates its oligomerization, which by itself is sufficient to form higher order oligomeric structure. Adenovirus-mediated overexpression of Angptl4 in 293 cells shows that conversion of full-length, oligomerized Angptl4 is mediated by a cell-associated protease activity induced by serum. These findings demonstrate a novel property of angiopoietin-like proteins and suggest that oligomerization and proteolytic processing of Angptl4 may regulate its biological activities in vivo.     

DNA deposition on carbon electrodes under controlled dc potentials

The native calf-thymus DNA molecule fully dispersed in solution was deposited onto highly oriented pyrolytic graphite, carbon fiber column and disk electrodes under controlled dc potentials. X-ray photoelectron spectroscopy, atomic force microscopy and electrochemical investigations indicated that network structures of DNA could be formed on various carbon electrode surfaces resulting in significant surface enlargement. The conformation, conductivity and stability of the deposited DNA layer largely depended on the concentration of the DNA deposition solution, the applied dc potential and the mode of electric field. The optimal condition for deposition of the DNA on carbon fiber disk electrode was determined as a deposition potential of 1.8 +/- 0.3 V versus 50 mM NaCl-Ag/AgCl and a deposition DNA solution of 0.1 mg ml(-1). Under this condition, the DNA was covalently bonded on the electrode surface forming a three-dimensional modified layer, generating a 500-fold enlarged effective electrode surface area and similarly enlarged current sensitivity for redox species, such as Co(phen)3(3+). A possible mechanism for the formation of DNA networks is proposed.