Mutagenesis of D80-82 and G83 residues in West Nile Virus NS2B: Effects on NS2B-NS3 activity and viral replication

Flaviviral NS2B is a required cofactor for NS3 serine protease activity and plays an important role in promoting functional NS2B-NS3 protease configuration and maintaining critical interactions with protease catalysis substrates. The residues D⁸⁰DDG in West Nile virus (WNV) NS2B are important for protease activity. To investigate the effects of D⁸⁰DDG in NS2B on protease activity and viral replication, the negatively charged region D⁸⁰DD and the conserved residue G83 of NS2B were mutated (D⁸⁰DD/E⁸⁰EE, D⁸⁰DD/K⁸⁰KK, D⁸⁰DD/A⁸⁰AA, G83F, G83S, G83D, G83K, and G83A), and NS3 D75A was designated as the negative control. The effects of the mutations on NS2B-NS3 activity, viral translation, and viral RNA replication were analyzed using kinetic analysis of site-directed enzymes and a transient replicon assay. All substitutions resulted in significantly decreased enzyme activity and blocked RNA replication. The negative charge of D⁸⁰DD is not important for maintaining NS2B function, but side chain changes in G83 have dramatic effects on protease activity and RNA replication. These results demonstrate that NS2B is important for viral replication and that D⁸⁰DD and G83 substitutions prevent replication; they will be useful for understanding the relationship between NS2B and NS3.     

Increased risk of lung cancer associated with a functionally impaired polymorphic variant of the human DNA glycosylase NEIL2

Human NEIL2, one of five oxidized base-specific DNA glycosylases, is unique in preferentially repairing oxidative damage in transcribed genes. Here we show that depletion of NEIL2 causes a 6-7-fold increase in spontaneous mutation frequency in the HPRT gene of the V79 Chinese hamster lung cell line. This prompted us to screen for NEIL2 variants in lung cancer patients' genomic DNA. We identified several polymorphic variants, among which R103Q and R257L were frequently observed in lung cancer patients. We then characterized these variants biochemically, and observed a modest decrease in DNA glycosylase activity relative to the wild type (WT) only with the R257L mutant protein. However, in reconstituted repair assays containing WT NEIL2 or its R257L and R103Q variants together with other DNA base excision repair (BER) proteins (PNKP, Polβ, Lig IIIα and XRCC1) or using NEIL2-FLAG immunocomplexes, an ~5-fold decrease in repair was observed with the R257L variant compared to WT or R103Q NEIL2, apparently due to the R257L mutant's lower affinity for other repair proteins, particularly Polβ. Notably, increased endogenous DNA damage was observed in NEIL2 variant (R257L)-expressing cells relative to WT cells. Taken together, our results suggest that the decreased DNA repair capacity of the R257L variant can induce mutations that lead to lung cancer development.     

Growth of Arabidopsis seedlings on high fungal doses of Piriformospora indica has little effect on plant performance,stress, and defense gene expression in spite of elevated jasmonic acid and jasmonic acid-isoleucine levels in the roots

The endophytic fungus Piriformospora indica colonizes the roots of many plant species including Arabidopsis and promotes their performance, biomass, and seed production as well as resistance against biotic and abiotic stress. Imbalances in the symbiotic interaction such as uncontrolled fungal growth result in the loss of benefits for the plants and activation of defense responses against the microbe. We exposed Arabidopsis seedlings to a dense hyphal lawn of P. indica. The seedlings continue to grow, accumulate normal amounts of chlorophyll, and the photosynthetic parameters demonstrate that they perform well. In spite of high fungal doses around the roots, the fungal material inside the roots was not significantly higher when compared with roots that live in a beneficial symbiosis with P. indica. Fifteen defense- and stress-related genes including PR2, PR3, PAL2, and ERF1 are only moderately upregulated in the roots on the fungal lawn, and the seedlings did not accumulate H₂O₂/radical oxygen species. However, accumulation of anthocyanin in P. indica-exposed seedlings indicates stress symptoms. Furthermore, the jasmonic acid (JA) and jasmonic acid-isoleucine (JA-Ile) levels were increased in the roots, and consequently PDF1.2 and a newly characterized gene for a 2-oxoglurate and Fe²⁺-dependent oxygenase were upregulated more than 7-fold on the dense fungal lawn, in a JAR1- and EIN3-dependent manner. We conclude that growth of A. thaliana seedlings on high fungal doses of P. indica has little effect on the overall performance of the plants although elevated JA and JA-Ile levels in the roots induce a mild stress or defense response.     

Maternal behavior in pigs

When sows kept under commercial conditions were put into crates in the early 1960s, the neuro-endocrine regulation of the maternal behavior in these domestic animals was disputed. Thus, the study of sow maternal behavior intensified and today a significant body of knowledge has accumulated to support the hormonal regulation of sow maternal behavior. The onset of nest building is associated with a periparturient decline in progesterone, an increase in prolactin and a major rise in plasma concentrations of PGF2alpha the day before parturition. Some nest building behaviors, such as pawing and gathering straw, have been found to correlate with changes in the levels of progesterone, prolactin and somatostatin. The duration of the birth process correlates negatively with peripheral oxytocin levels. During lactation, the stimuli from the piglets affect the release of several hormones which not only regulate the let down of milk but also sow metabolism and mammary milk production. The sow's nursing behavior ensures an even distribution of milk to her piglets. The piglets suckling behavior, in turn, is mainly a way to communicate their individual nutritional needs.     

Penicacids A-C, three new mycophenolic acid derivatives and immunosuppressive activities from the marine-derived fungus Penicillium sp. SOF07

Three new mycophenolic acid derivatives, penicacids A-C (1-3), together with two known analogues, mycophenolic acid (MPA, 4) and 4'-hydroxy-MPA (5), were isolated from a fungus Penicillium sp. SOF07 derived from a South China Sea marine sediment. The structures of compounds 1-3 were elucidated on the basis of MS and NMR ((1)H, (13)C, HSQC and HMBC) data analyses and comparisons with the known compounds. Structure-activity relationship studies of compounds 1-5 focused on inosine-monophosphate dehydrogenase inhibition revealed that hydroxylation at C-4', methylation at C-7-OH, dual hydroxylation at C-2'/C-3' double bond of MPA diminished bioactivity whereas glucosyl hydroxylation at C-4' correlated to bioactivity comparable to that observed for MPA.     

The bracts of the alpine ‘glasshouse’ plant Rheum alexandrae (Polygonaceae) enhance reproductive fitness of its pollinating seed‐consuming mutualist

Environmental conditions are known to affect the reproductive fitness of insects, as do host plants. Although the highly specialized bracts of Himalayan ‘glasshouse’ plants are thought to be an adaptive morphology that allows the plant to reproduce in harsh alpine environments, little information appears to exist concerning the benefit of these bracts for the pollinating insects. In this study, we examine whether the semi‐translucent bracts of Rheum alexandrae, a giant herb endemic to the alpine zone of the Hengduan Mountains in south‐western China, enhance the reproductive fitness of its pollinator. Rheum alexandrae depends mainly on mutualistic seed‐consuming Bradysia flies for pollination. Bracts increased interior temperature on sunny days, acted as a buffer against fluctuating air humidity, greatly decreased the intensities of ultraviolet B/C radiation and provided shelter from strong winds. Bract removal significantly decreased adult oviposition and offspring performance of pollinators during flowering and fruiting, respectively. Our results indicate that the bracts of R. alexandrae enhance the reproductive fitness of its pollinating seed‐consuming mutualist in alpine environments, which may be attributed to the positive effects of the bracts on the interior microenvironment. © 2015 The Linnean Society of London, Botanical Journal of the Linnean Society, 2015, 179 , 349–359.     

Sodium (±)‐5‐bromo‐2‐(α‐hydroxypentyl) benzoate ameliorates pressure overload‐induced cardiac hypertrophy and dysfunction through inhibiting autophagy

Sodium (±)‐5‐bromo‐2‐(a‐hydroxypentyl) benzoate (generic name: brozopine, BZP) has been reported to protect against stroke‐induced brain injury and was approved for Phase II clinical trials for treatment of stroke‐related brain damage by the China Food and Drug Administration (CFDA). However, the role of BZP in cardiac diseases, especially in pressure overload‐induced cardiac hypertrophy and heart failure, remains to be investigated. In the present study, angiotensin II stimulation and transverse aortic constriction were employed to induce cardiomyocyte hypertrophy in vitro and in vivo, respectively, prior to the assessment of myocardial cell autophagy. We observed that BZP administration ameliorated cardiomyocyte hypertrophy and excessive autophagic activity. Further results indicated that AMP‐activated protein kinase (AMPK)‐mediated activation of the mammalian target of rapamycin (mTOR) pathway likely played a role in regulation of autophagy by BZP after Ang II stimulation. The activation of AMPK with metformin reversed the BZP‐induced suppression of autophagy. Finally, for the first time, we demonstrated that BZP could protect the heart from pressure overload‐induced hypertrophy and dysfunction, and this effect is associated with its inhibition of maladaptive cardiomyocyte autophagy through the AMPK‐mTOR signalling pathway. These findings indicated that BZP may serve as a promising compound for treatment of pressure overload‐induced cardiac remodelling and heart failure.