Cardiolipin and Its Different Properties in Mitophagy and Apoptosis

Cardiolipin (CL) is a unique dimeric phospholipid that exists almost exclusively in the inner mitochondrial membrane (IMM) in eukaryotic cells. Two chiral carbons and four fatty acyl chains in CL result in a flexible body allowing interactions with respiratory chain complexes and mitochondrial substrate carriers. Due to its high content of unsaturated fatty acids, CL is particularly prone to reactive oxygen species (ROS)-induced oxidative attacks. Under mild mitochondrial damage, CL is redistributed to the outer mitochondrial membrane (OMM) and serves as a recognition signal for dysfunctional mitochondria, which are rapidly sequestered by autophagosomes. However, peroxidation of CL is far greater in response to severe stress than under normal or mild-damage conditions. The accumulation of oxidized CL on the OMM results in recruitment of Bax and formation of the mitochondrial permeability transition pore (MPTP), which releases Cytochrome c (Cyt c) from mitochondria. Over the past decade, the significance of CL in the function of mitochondrial bioenergy has been explored. Moreover, approaches to analyzing CL have become more effective and accurate. In this review, we discuss the unique structural features of CL as well as the current understanding of CL-based molecular mechanisms of mitophagy and apoptosis.     

Results of using the serological method of epidemiological investigation of plague foci in the Muyunkum and Eastern Kyzylkum deserts in 1978-1982

Results of serological examination of 81,853 mammals from the Muyunkum and 26,303 from the Eastern Kyzylkum deserts were compared with results of a corresponding bacteriological examination for plague. In both foci and in all phases throughout the epizootic of plague, the serological method made it possible to detect infected animals 6-10 times more frequently in comparison with the bacteriological method. The big meriones mice, i.e., the basic carriers of plague in natural foci, were found to be infected considerably more (in percentage) frequently than the meridian meriones. Differences in the reactivity of meriones to the invasion of plague microbe were observed in both foci (the indices of titres in the antigen neutralization reaction were considerably higher in the Eastern Kyzylkums). The serological method of investigation is highly informative in evaluating both the present state of epizootic activity of a plague focus and its activity in the past.     

Twist and Degrade—Impact of Molecular Structure on the Photostability of Nonfullerene Acceptors and Their Photovoltaic Blends

Nonfullerene acceptors (NFAs) dominate organic photovoltaic (OPV) research due to their promising efficiencies and stabilities. However, there is very little investigation into the molecular processes of degradation, which is critical to guiding design of novel NFAs for long‐lived, commercially viable OPVs. Here, the important role of molecular structure and conformation in NFA photostability in air is investigated by comparing structurally similar but conformationally different promising NFAs: planar O‐IDTBR and nonplanar O‐IDFBR. A three‐phase degradation process is identified: i) initial photoinduced conformational change (i.e., torsion about the core–benzothiadiazole dihedral), induced by noncovalent interactions with environmental molecules, ii) followed by photo‐oxidation and fragmentation, leading to chromophore bleaching and degradation product formation, and iii) finally complete chromophore bleaching. Initial conformational change is a critical prerequisite for further degradation, providing fundamental understanding of the relative stability of IDTBR and IDFBR, where the already twisted IDFBR is more prone to degradation. When blended with the donor polymer poly(3‐hexylthiophene), both NFAs exhibit improved photostability while the photostability of the polymer itself is significantly reduced by the more miscible twisted NFA. The findings elucidate the important role of NFA molecular structure in photostability of OPV systems, and provide vital insights into molecular design rules for intrinsically photostable NFAs.     

Assessing Mitochondrial DNA Variation and Copy Number in Lymphocytes of ~2,000 Sardinians Using Tailored Sequencing Analysis Tools

DNA sequencing identifies common and rare genetic variants for association studies, but studies typically focus on variants in nuclear DNA and ignore the mitochondrial genome. In fact, analyzing variants in mitochondrial DNA (mtDNA) sequences presents special problems, which we resolve here with a general solution for the analysis of mtDNA in next-generation sequencing studies. The new program package comprises 1) an algorithm designed to identify mtDNA variants (i.e., homoplasmies and heteroplasmies), incorporating sequencing error rates at each base in a likelihood calculation and allowing allele fractions at a variant site to differ across individuals; and 2) an estimation of mtDNA copy number in a cell directly from whole-genome sequencing data. We also apply the methods to DNA sequence from lymphocytes of ~2,000 SardiNIA Project participants. As expected, mothers and offspring share all homoplasmies but a lesser proportion of heteroplasmies. Both homoplasmies and heteroplasmies show 5-fold higher transition/transversion ratios than variants in nuclear DNA. Also, heteroplasmy increases with age, though on average only ~1 heteroplasmy reaches the 4% level between ages 20 and 90. In addition, we find that mtDNA copy number averages ~110 copies/lymphocyte and is ~54% heritable, implying substantial genetic regulation of the level of mtDNA. Copy numbers also decrease modestly but significantly with age, and females on average have significantly more copies than males. The mtDNA copy numbers are significantly associated with waist circumference (p-value = 0.0031) and waist-hip ratio (p-value = 2.4×10^-5), but not with body mass index, indicating an association with central fat distribution. To our knowledge, this is the largest population analysis to date of mtDNA dynamics, revealing the age-imposed increase in heteroplasmy, the relatively high heritability of copy number, and the association of copy number with metabolic traits.     

Hypoxia. Hypoxia in the pathogenesis of systemic sclerosis

Autoimmunity, microangiopathy and tissue fibrosis are hallmarks of systemic sclerosis (SSc). Vascular alterations and reduced capillary density decrease blood flow and impair tissue oxygenation in SSc. Oxygen supply is further reduced by accumulation of extracellular matrix (ECM), which increases diffusion distances from blood vessels to cells. Therefore, severe hypoxia is a characteristic feature of SSc and might contribute directly to the progression of the disease. Hypoxia stimulates the production of ECM proteins by SSc fibroblasts in a transforming growth factor-β-dependent manner. The induction of ECM proteins by hypoxia is mediated via hypoxia-inducible factor-1α-dependent and -independent pathways. Hypoxia may also aggravate vascular disease in SSc by perturbing vascular endothelial growth factor (VEGF) receptor signalling. Hypoxia is a potent inducer of VEGF and may cause chronic VEGF over-expression in SSc. Uncontrolled over-expression of VEGF has been shown to have deleterious effects on angiogenesis because it leads to the formation of chaotic vessels with decreased blood flow. Altogether, hypoxia might play a central role in pathogenesis of SSc by augmenting vascular disease and tissue fibrosis.     

Hemispheric Asymmetry in New Neurons in Adulthood Is Associated with Vocal Learning and Auditory Memory

Many brain regions exhibit lateral differences in structure and function, and also incorporate new neurons in adulthood, thought to function in learning and in the formation of new memories. However, the contribution of new neurons to hemispheric differences in processing is unknown. The present study combines cellular, behavioral, and physiological methods to address whether 1) new neuron incorporation differs between the brain hemispheres, and 2) the degree to which hemispheric lateralization of new neurons correlates with behavioral and physiological measures of learning and memory. The songbird provides a model system for assessing the contribution of new neurons to hemispheric specialization because songbird brain areas for vocal processing are functionally lateralized and receive a continuous influx of new neurons in adulthood. In adult male zebra finches, we quantified new neurons in the caudomedial nidopallium (NCM), a forebrain area involved in discrimination and memory for the complex vocalizations of individual conspecifics. We assessed song learning and recorded neural responses to song in NCM. We found significantly more new neurons labeled in left than in right NCM; moreover, the degree of asymmetry in new neuron numbers was correlated with the quality of song learning and strength of neuronal memory for recently heard songs. In birds with experimentally impaired song quality, the hemispheric difference in new neurons was diminished. These results suggest that new neurons may contribute to an allocation of function between the hemispheres that underlies the learning and processing of complex signals.     

Phospho-NHE3 forms membrane patches and interacts with beta-actin to sense and maintain constant direction during cell migration

The Na(+)/H(+) exchanger NHE3 colocalizes with beta-actin at the leading edge of directionally migrating cells. Using human osteosarcoma cells (SaOS-2), rat osteoblasts (calvaria), and human embryonic kidney (HEK) cells, we identified a novel role for NHE3 via beta-actin in anode and cathode directed motility, during electrotaxis. NHE3 knockdown by RNAi revealed that NHE3 expression is required to achieve constant directionality and polarity in migrating cells. Phosphorylated NHE3 (pNHE3) and beta-actin complex formation was impaired by the NHE3 inhibitor S3226 (IC50 0.02 µM). Fluorescence cross-correlation spectroscopy (FCCS) revealed that the molecular interactions between NHE3 and beta-actin in membrane protrusions increased 1.7-fold in the presence of a directional cue and decreased 3.3-fold in the presence of cytochalasin D. Data from flow cytometric analysis showed that membrane potential of cells (V_mem) decreases in directionally migrating, NHE3-deficient osteoblasts and osteosarcoma cells whereas only V_mem of wild type osteoblasts is affected during directional migration. These findings suggest that pNHE3 has a mechanical function via beta-actin that is dependent on its physiological activity and V_mem. Furthermore, phosphatidylinositol 3,4,5-trisphosphate (PIP3) levels increase while PIP2 remains stable when cells have persistent directionality. Both PI3 kinase (PI3K) and Akt expression levels change proportionally to NHE3 levels. Interestingly, however, the content of pNHE3 level does not change when PI3K/Akt is inhibited. Therefore, we conclude that NHE3 can act as a direction sensor for cells and that NHE3 phosphorylation in persistent directional cell migration does not involve PI3K/Akt during electrotaxis.     

Complete Genome Sequence of Staphylococcus lugdunensis Strain HKU09-01

Staphylococcus lugdunensis is a member of the coagulase-negative staphylococci and commonly found as part of the human skin flora. It is a significant cause of catheter-related bacteremia and also causes serious infections like native valve endocarditis in previously healthy individuals. We report the complete genome sequence of this medically important bacterium.Staphylococcus lugdunensis is a member of the coagulase-negative staphylococci (CoNS) commonly colonizing the human skin and mucosal membranes. While the genus Staphylococcus contains 48 named species currently, only a few species, notably S. aureus, are coagulase positive. Thus, the phenotypic characteristic is routinely tested in the medical microbiological laboratory for rapid differentiation of the highly pathogenic S. aureus from the other staphylococci. Among the CoNS, only a few species are known to cause human disease, usually in the form of opportunistic infections only (6). However, S. lugdunensis is an important exception (3). Besides causing catheter-related bacteremia similar to other CoNS, it causes a variety of severe nosocomial and community-acquired infections, including native valve endocarditis, a devastating and potentially fatal disease that can affect previously healthy individuals. Another unusual feature are the susceptibilities of S. lugdunensis isolates to multiple antimicrobial agents even when the incidence of multiple-drug-resistant CoNS and S. aureus occurrences are increasing in both hospital and community settings (4, 5).The genome sequence of S. lugdunensis strain HKU09-01 was determined by high-throughput sequencing performed on a GS FLX system (Roche Diagnostics, Basel, Switzerland), with approximately 45-fold coverage of the genome. This clinical strain was previously isolated from the culture of pus from a skin swab. Genome assembly was performed using the Newbler assembler, resulting in 30 large contigs (>500 bp in size). The contigs were then ordered and oriented into one scaffold using OSLay (11). The genome-finishing strategy for S. lugdunensis was similar to that employed for our previously sequenced Laribacter hongkongensis genome (12). Briefly, gap closures were performed by genomic PCR followed by DNA sequencing of amplification products on an ABI 3130xl sequencer (Applied Biosystems, CA). The finished sequence was validated by genome macrorestriction analysis using multiple rare-cutting enzymes and visualization by pulsed-field gel electrophoresis. Protein coding regions were predicted with Glimmer3 (2), and automatic genome annotation was performed on the RAST server (1). Additionally, annotation of tRNA and transfer-messenger RNA (tmRNA) genes was performed using tRNAScan-SE (10) and ARAGORN (9). Identification of rRNA genes was performed using RNAmmer (8).The genome of S. lugdunensis strain HKU09-01 consists of a circular 2,658,366-bp chromosome with G+C content of 33.87%, similar to those of other staphylococci. No plasmids are present in the sequenced strain. The genome contains 61 tRNA genes for all amino acids and 2,489 predicted protein-coding genes. Eight putative genomic islands were identified, and one actually consists of a pair of duplicated 32-kb genomic regions. Similar to Staphylococcus saprophyticus (7), but different from the other staphylococci, the genome contains 6 rRNA operons, one of them having the unusual organization 5S-16S-23S-5S.With the availability of the present genome sequence, S. lugdunensis now joins other staphylococcal species with human pathogenic potential, like S. aureus, S. epidermidis, S. haemolyticus, and S. saprophyticus, to have at least one reference genome available. Further in-depth analysis will be necessary to fully elucidate the genomic differences that may explain the variation in virulence of the staphylococcal species.     

Antioxidative effect of a chymotrypsin inhibitor from Momordica cochinchinensis (Cucurbitaceae) seeds in a primary rat hepatocyte culture.

The antioxidative activity of a chymotrypsin-specific potato type I inhibitor from Momordica cochinchinensis (MCoCI) (Cucurbitaceae) has been investigated using the primary rat hepatocyte system. tert-Butyl hydroperoxide (t-BHP) was used to induce oxidative stress. Pretreatment of hepatocytes with MCoCI for 24 h significantly reversed t-BHP-induced cell damage, and the associated glutathione depletion and lipid peroxidation. The activities of glutathione-S-transferase and superoxide dismutase were also increased. These results suggested that MCoCI possessed antioxidative activity which may account for some of the pharmacological effects of Momordica cochinchinensis seeds, the traditional Chinese medicine known as Mubiezhi, from which MCoCI was isolated.