Cholesterol Partition and Condensing Effect in Phase-Separated Ternary Mixture Lipid Multilayers

The cholesterol partitioning and condensing effect in the liquid-ordered (L_o) and liquid-disordered (L_d) phases were systematically investigated for ternary mixture lipid multilayers consisting of 1:1 1,2-dipalmitoyl-sn-glycero-3-phosphocholine/1,2-dioleoyl-sn-glycero-3-phosphocholine with varying concentrations of cholesterol. X-ray lamellar diffraction was used to deduce the electron density profiles of each phase. The cholesterol concentration in each phase was quantified by fitting of the electron density profiles with a newly invented basic lipid profile scaling method that minimizes the number of fitting parameters. The obtained cholesterol concentration in each phase versus total cholesterol concentration in the sample increases linearly for both phases. The condensing effect of cholesterol in ternary lipid mixtures was evaluated in terms of phosphate-to-phosphate distances, which together with the estimated cholesterol concentration in each phase was converted into an average area per molecule. In addition, the cholesterol position was determined to a precision of (±0.7Å) and an increase of disorder in the lipid packing in the L_o phase was observed for total cholesterol concentration of 20∼30%.     

Structural dynamics of the yeast Shwachman-Diamond syndrome protein (Sdo1) on the ribosome and its implication in the 60S subunit maturation

The human Shwachman-Diamond syndrome (SDS) is an autosomal recessive disease caused by mutations in a highly conserved ribosome assembly factor SBDS. The functional role of SBDS is to cooperate with another assembly factor, elongation factor 1-like (Efl1), to promote the release of eukaryotic initiation factor 6 (eIF6) from the late-stage cytoplasmic 60S precursors. In the present work, we characterized, both biochemically and structurally, the interaction between the 60S subunit and SBDS protein (Sdo1p) from yeast. Our data show that Sdo1p interacts tightly with the mature 60S subunit in vitro through its domain I and II, and is capable of bridging two 60S subunits to form a stable 2:2 dimer. Structural analysis indicates that Sdo1p bind to the ribosomal P-site, in the proximity of uL16 and uL5, and with direct contact to H69 and H38. The dynamic nature of Sdo1p on the 60S subunit, together with its strategic binding position, suggests a surveillance role of Sdo1p in monitoring the conformational maturation of the ribosomal P-site. Altogether, our data support a conformational signal-relay cascade during late-stage 60S maturation, involving uL16, Sdo1p, and Efl1p, which interrogates the functional P-site to control the departure of the anti-association factor eIF6.     

IL-33/ST2 Correlates with Severity of Haemorrhagic Fever with Renal Syndrome and Regulates the Inflammatory Response in Hantaan Virus-Infected Endothelial Cells

Background

Hantaan virus (HTNV) causes a severe lethal haemorrhagic fever with renal syndrome (HFRS) in humans. Despite a limited understanding of the pathogenesis of HFRS, the importance of the abundant production of pro-inflammatory cytokines has been widely recognized. Interleukin 33 (IL-33) has been demonstrated to play an important role in physiological and pathological immune responses. After binding to its receptor ST2L, IL-33 stimulates the Th2-type immune response and promotes cytokine production. Depending on the disease model, IL-33 either protects against infection or exacerbates inflammatory disease, but it is unknown how the IL-33/ST2 axis regulates the immune response during HTNV infection.

Methodology/Principal Findings

Blood samples were collected from 23 hospitalized patients and 28 healthy controls. The levels of IL-33 and soluble ST2 (sST2) in plasma were quantified by ELISA, and the relationship between IL-33, sST2 and the disease severity was analyzed. The role of IL-33/sST2 axis in the production of pro-inflammatory cytokines was studied on HTNV-infected endothelial cells. The results showed that the plasma IL-33 and sST2 were significantly higher in patients than in healthy controls. Spearman analysis showed that elevated IL-33 and sST2 levels were positively correlated with white blood cell count and viral load, while negatively correlated with platelet count. Furthermore, we found that IL-33 enhanced the production of pro-inflammatory cytokines in HTNV-infected endothelial cells through NF-κB pathway and that this process was inhibited by the recombinant sST2.

Conclusion/Significance

Our results indicate that the IL-33 acts as an initiator of the “cytokine storm” during HTNV infection, while sST2 can inhibit this process. Our findings could provide a promising immunotherapeutic target for the disease control.     

Effect of climate change on sporulation of the teleomorphs of <Emphasis Type="Italic">Leptosphaeria</Emphasis> species causing stem canker of brassicas

Leptosphaeria maculans and L. biglobosa are closely related sibling fungal pathogens that cause phoma leaf spotting, stem canker (blackleg) and stem necrosis of oilseed rape (Brassica napus). The disease is distributed worldwide, and it is one of the main causes of considerable decrease in seed yield and quality. Information about the time of ascospore release at a particular location provides important data for decision making in plant protection, thereby enabling fungicides to be used only when necessary and at optimal times and doses. Although the pathogens have been studied very extensively, the effect of climate change on the frequencies and distributions of their aerially dispersed primary inoculum has not been reported to date. We have collected a large dataset of spore counts from Poznan, located in central-west part of Poland, and studied the relationships between climate and the daily concentrations of airborne propagules over a period of 17 years (1998–2014). The average air temperature and precipitation for the time of development of pseudothecia and ascospore release (July–November), increased during the years under study at the rates of 0.1 °C and 6.3 mm per year. The day of the year (DOY) for the first detection of spores, as well as the date with maximum of spores, shifted from 270 to 248 DOY, and from 315 to 265 DOY, respectively. The acceleration of the former parameter by 22 days and the latter by 50 days has great influence on the severity of stem canker of oilseed rape.     

Differential expression of iron-sulfur cluster biosynthesis genes during peach flowering

Iron is required for the Fe-S cluster assembly which occurs in chloroplasts, mitochondria, and cytosol and here we characterized 44 Fe-S cluster biosynthesis genes and investigated their expression profiles during different peach flowering stages. Quantitative real-time PCR analysis shows that the highest expression of most peach Fe-S cluster biosynthesis genes appeared in the full bloom stage. Also, the highest Fe accumulation occurred in the full bloom stage followed by beginning bloom, petal fall, and bud swell stages. Activities of nitrite reductase (NiR) and succinate dehydrogenase (SDH) were closely correlated to the flower Fe content, whereas the aconitase (ACO) activity kept steady during the whole flowering process. Moreover, shading treatment significantly reduced Fe accumulation and NiR, SDH, and ACO activities of the full blooming flowers. Seventeen Fe-S cluster biosynthesis genes were down-regulated in response to a shading treatment. In particular, plastid sulfur mobilization genes were sensitive to the shading treatment.     

Phosphorylation of JNK Increases in the Cortex of Rat Subjected to Diabetic Cerebral Ischemia

Previous studies have demonstrated that the c-Jun N-terminal kinase (JNK) pathway plays an important role in inducing neuronal apoptosis following cerebral ischemic injury. JNK signaling pathway in activated during cerebral ischemic injury. It participates in ischemia-induced neuronal apoptosis. However, whether JNK signaling is involved in the process of neuronal apoptosis of diabetes-induced cerebral ischemia is largely unknown. This study was undertaken to evaluate the influence of cerebral ischemia–reperfusion injury on phosphorylation of JNK in diabetic rats. Twenty-four adult streptozotocin induced diabetic and 24 adult non-diabetic rats were randomly subjected to 15 min of forebrain ischemia followed by reperfusion for 0, 1, 3, and 6 h. Sixteen sham-operated diabetic and non-diabetic rats were used as controls. Apoptosis was assessed by terminal deoxynucleotidyl transferase-mediated dUTP nick-end labelling (TUNEL). Protein expression of phospho-JNK was examined by immunohistochemistry and Western blot. The numbers of TUNEL-positive cells and phospho-JNK protein expression in the cerebral cortices after 1, 3 and 6 h reperfusion was significantly higher in diabetic rats compared to non-diabetic animals subjected to ischemia and reperfusion (p < 0.05). Western blot analysis showed significantly higher phospho-JNK protein expression in the cerebral cortices of the diabetic rats after 1 and 3 h reperfusion than that was presented in non-diabetic animals subjected to ischemia and reperfusion (p < 0.05). These findings suggest that increased phosphorylation of JNK may be associated with diabetes-enhanced ischemic brain damage.     

The C-terminus of DSX<Superscript>F5</Superscript> protein acts as a novel regulatory domain in <Emphasis Type="Italic">Bombyx mori</Emphasis>

The doublesex gene regulates the somatic sexual development of Bombyx mori by alternatively splicing into sex-specific splice forms. In our previous study, the splice form Bmdsx ^F7 , which encodes the BmDSX^F5 protein, was found to be expressed in a female-specific manner and to contain a novel C-terminus. In this study, we aimed to investigate the role of this C-terminus. Two transgenic lines, L1 and L2, were constructed to ectopically express Bmdsx ^F7 in males. Phenotype and W chromosome-specific polymerase chain reaction (PCR) analysis showed that developmental abnormalities and sex reversal did not occur. Moreover, the sex ratio was also normal. Quantitative PCR revealed that the expression levels of SP1 and Vg were upregulated in the fat body of transgenic males. Additionally, the expression level of PBP was downregulated in the antenna of transgenic males. The results suggested that the C-terminus of BmDSX^F5 functioned as a regulatory domain during regulation of downstream target gene expression and that BmDSX^F5 participated in the sexual development of somatic cells together with other DSX proteins in B. mori.