Increased Mitochondrial Permeability in Response to Intrastriatal N-Methyl-d-Aspartate: Detection Based on Accumulation of Radiolabel from [3H]Deoxyglucose

Induction of the mitochondrial permeability transition has been proposed as an important contributor to cell loss in several neurological disorders, but the evidence that this change can develop in cells in the intact mature brain is largely indirect. In this study, we have tested whether an intrastriatal injection of N-methyl-D-aspartate results in increases in inner membrane permeability that can be detected from mitochondrial accumulation of metabolites of 3H-deoxyglucose previously taken up by brain cells. An increase in incorporation of deoxyglucose metabolites was found in mitochondria prepared from the striatum but not from cerebral cortex distant from the injection site. This change developed more than 8 h after treatment with N-methyl-D-aspartate and is consistent with the induction of the permeability transition as a late change in the progression to irreversible neuronal damage in response to this excitotoxic insult. At earlier times, the restricted permeability of the inner mitochondrial membrane was apparently preserved, at least sufficiently to prevent significant diffusion of metabolites between the cytoplasm and the matrix.     

The Antifungal Eugenol Perturbs Dual Aromatic and Branched-Chain Amino Acid Permeases in the Cytoplasmic Membrane of Yeast

Eugenol is an aromatic component of clove oil that has therapeutic potential as an antifungal drug, although its mode of action and precise cellular target(s) remain ambiguous. To address this knowledge gap, a chemical-genetic profile analysis of eugenol was done using ∼4700 haploid Saccharomyces cerevisiae gene deletion mutants to reveal 21 deletion mutants with the greatest degree of susceptibility. Cellular roles of deleted genes in the most susceptible mutants indicate that the main targets for eugenol include pathways involved in biosynthesis and transport of aromatic and branched-chain amino acids. Follow-up analyses showed inhibitory effects of eugenol on amino acid permeases in the yeast cytoplasmic membrane. Furthermore, phenotypic suppression analysis revealed that eugenol interferes with two permeases, Tat1p and Gap1p, which are both involved in dual transport of aromatic and branched-chain amino acids through the yeast cytoplasmic membrane. Perturbation of cytoplasmic permeases represents a novel antifungal target and may explain previous observations that exposure to eugenol results in leakage of cell contents. Eugenol exposure may also contribute to amino acid starvation and thus holds promise as an anticancer therapeutic drug. Finally, this study provides further evidence of the usefulness of the yeast Gene Deletion Array approach in uncovering the mode of action of natural health products.     

Chemical synthesis of Haemophilus influenzae glycopeptide conjugates

A simple procedure for conjugating synthetic fragments of the capsular polysaccharide of Haemophilus influenzae type b, poly-3--D-ribose-(1, 1)-D-ribitol-5-phosphate (sPRP) to linear peptides is described. The procedure consists of (i) reacting the amino group of amino-heptyl sPRP with m-maleimidobenzoyl-N-hydroxysuccinimide (MBS) in phosphate buffer, pH 7.5; (ii) selectively coupling the MBS-modified sPRP to the sulfhydryl group of the cysteine residue of peptides containing functional T-helper cell epitope(s). The glycopeptide conjugates were purified by gel filtration chromatography, biochemically characterized, and elicited protective level of anti-PRP antibody responses in rabbits. Abbreviations: PRP, poly-3--D-ribose-(1, 1)-D-ribitol-5-phosphate; sPRP, synthetic oligo-3--D-ribose-(1, 1)-D-ribitol-5-phosphate; Hib, Haemophilus influenzae type b; MBS, m-maleimidobenzoyl-N-hydroxysuccinimide; PEG, polyethylene glycol monomethyl ether; CRM 197, a non-toxic diphtheria toxin mutant; TT, tetanus toxoid; DT, diphtheria toxoid; OMP, outer membrane protein; RP-HPLC reverse phase high pressure liquid chromatograph     

Antitumour and antioxidant activity of some Red Sea seaweeds in Ehrlich ascites carcinoma in vivo

The antitumour activities of extracts from the Red Sea seaweeds Jania rubens, Sargassum subrepandum, and Ulva lactuca were investigated in an in vivo mice model based on intramuscular injection of Ehrlich ascites tumour cells. In parallel, antioxidant activities were measured. Tumour marker levels, liver biochemical parameters, and hepatic oxidant/antioxidant status were measured to prove the anticancer and antioxidant nature of the algal extracts. Significant decreases in carcinoembryonic antigen (CEA) and a-fetoprotein (AFP) levels, activities of liver enzymes, levels of nitric oxide (NO) and malondialdehyde (MDA), and an increase in total antioxidant capacity (TAC) were recorded in groups treated with the algal extracts. Jania rubens was selected for phytochemical screening of its phytoconstituents. In addition, carotenoids, halides, minerals, lipoidal matters, proteins, and carbohydrates were studied. Furthermore, 7-oxo-cholest-5(6)-en-3-ol (1) and cholesterol (2) were isolated from the dichloromethane fraction.     

The Pyruvate Dehydrogenase Complex Is Partially Inactivated During Early Recirculation Following Short-Term Forebrain Ischemia in Rats

Abstract: The mechanisms of selective neuronal loss after short-term global ischemia remain undefined, but processes including increased proteolytic activity, impaired protein synthesis, and oxidative damage have been proposed to contribute. A decrease in activity of the pyruvate dehydrogenase complex in the dorsolateral striatum, an ischemia-susceptible region, is one change apparently differentiating this region from ischemia-resistant areas during early recirculation. To provide an insight into processes contributing to postischemic cell damage, the changes in the pyruvate dehydrogenase complex during early recirculation have been further characterized. These studies provide clear confirmation that the activity of the pyruvate dehydrogenase complex is reduced in mitochondria from the dorsolateral striatum by 3 h of recirculation. The decrease in activity was not accompanied by a loss of antigenic sites or by changes in electrophoretic mobility of the components of the complex. A reduction in activity of the E1 component of the complex (39–42% decrease), but not the E2 and E3 components, was observed that was apparently sufficient to explain the decrease in activity of the whole complex. These results indicate that the changes in activity of the pyruvate dehydrogenase complex in the dorsolateral striatum are not due to loss or gross disruption of the constituent proteins but rather most likely reflect a selective inactivation of a specific component of the complex.     

Structural Basis of Substrate Selectivity in the Glycerol-3-Phosphate: Phosphate Antiporter GlpT

Major facilitators represent the largest superfamily of secondary active transporter proteins and catalyze the transport of an enormous variety of small solute molecules across biological membranes. However, individual superfamily members, although they may be architecturally similar, exhibit strict specificity toward the substrates they transport. The structural basis of this specificity is poorly understood. A member of the major facilitator superfamily is the glycerol-3-phosphate (G3P) transporter (GlpT) from the Escherichia coli inner membrane. GlpT is an antiporter that transports G3P into the cell in exchange for inorganic phosphate (P_i). By combining large-scale molecular-dynamics simulations, mutagenesis, substrate-binding affinity, and transport activity assays on GlpT, we were able to identify key amino acid residues that confer substrate specificity upon this protein. Our studies suggest that only a few amino acid residues that line the transporter lumen act as specificity determinants. Whereas R45, K80, H165, and, to a lesser extent Y38, Y42, and Y76 contribute to recognition of both free P_i and the phosphate moiety of G3P, the residues N162, Y266, and Y393 function in recognition of only the glycerol moiety of G3P. It is the latter interactions that give the transporter a higher affinity to G3P over P_i.     

Connecting to the oceans: supporting ocean literacy and public engagement

Improved public understanding of the ocean and the importance of sustainable ocean use, or ocean literacy, is essential for achieving global commitments to sustainable development by 2030 and beyond. However, growing human populations (particularly in mega-cities), urbanisation and socio-economic disparity threaten opportunities for people to engage and connect directly with ocean environments. Thus, a major challenge in engaging the whole of society in achieving ocean sustainability by 2030 is to develop strategies to improve societal connections to the ocean. The concept of ocean literacy reflects public understanding of the ocean, but is also an indication of connections to, and attitudes and behaviours towards, the ocean. Improving and progressing global ocean literacy has potential to catalyse the behaviour changes necessary for achieving a sustainable future. As part of the Future Seas project (https://futureseas2030.org/), this paper aims to synthesise knowledge and perspectives on ocean literacy from a range of disciplines, including but not exclusive to marine biology, socio-ecology, philosophy, technology, psychology, oceanography and human health. Using examples from the literature, we outline the potential for positive change towards a sustainable future based on knowledge that already exists. We focus on four drivers that can influence and improve ocean literacy and societal connections to the ocean: (1) education, (2) cultural connections, (3) technological developments, and (4) knowledge exchange and science-policy interconnections. We explore how each driver plays a role in improving perceptions of the ocean to engender more widespread societal support for effective ocean management and conservation. In doing so, we develop an ocean literacy toolkit, a practical resource for enhancing ocean connections across a broad range of contexts worldwide.

     

The HIV core protein p24 inhibits interferon-gamma-induced increase of HLA-DR and cytochrome b heavy chain mRNA levels in the human monocyte-like cell line THP1

Cells from the human monocytic cell-line THP1 were incubated prior to activation with IFN-gamma or LPS with varying amounts of p24, the main product of the HIV gag gene and the major component of the virus core. The IFN-gamma-dependent increase of mRNA for HLA-DR and for the heavy chain of cytochrome b was markedly decreased by p24 but not by gp120. This effect was abrogated by anti-p24 antibodies. On the other hand, preincubation of THP1 cells with p24 did not affect the accumulation of the LPS-dependent mRNA for TNF alpha and IL1-beta. These results indicate that p24 at concentrations similar to those found in the serum of HIV-infected individuals specifically affects IFN-gamma-induced activation markers.