The comparison of vanadyl(IV) and insulin-induced hyperpolarization of the mammalian muscle cell

Extracellularly applied vanadyl(IV) hyperpolarized the membrane potential of mouse diaphragm muscle from about −74.0 mV up to −81.7 mV. The hyperpolarizing effect of 10⁻⁴ mol·l⁻¹ vanadyl(IV) is comparable with hyperpolarization induced by 100 mU·ml⁻¹ insulin. Both compounds increased the intracellular K⁺ concentration, the hyperpolarizing effect of vanadyl(IV) and insulin is blocked by ouabain and is unaffected by removal of K⁺ from the external medium. Triggering of the release of intracellular K⁺ associated with cellular proteins is proposed as the mechanism of vanadyl(IV) and insulin-induced hyperpolarization.     

Pipecolic Acid,an Endogenous Mediator of Defense Amplification and Priming,Is a Critical Regulator of Inducible Plant Immunity

Metabolic signals orchestrate plant defenses against microbial pathogen invasion. Here, we report the identification of the non-protein amino acid pipecolic acid (Pip), a common Lys catabolite in plants and animals, as a critical regulator of inducible plant immunity. Following pathogen recognition, Pip accumulates in inoculated Arabidopsis thaliana leaves, in leaves distal from the site of inoculation, and, most specifically, in petiole exudates from inoculated leaves. Defects of mutants in AGD2-LIKE DEFENSE RESPONSE PROTEIN1 (ALD1) in systemic acquired resistance (SAR) and in basal, specific, and β-aminobutyric acid–induced resistance to bacterial infection are associated with a lack of Pip production. Exogenous Pip complements these resistance defects and increases pathogen resistance of wild-type plants. We conclude that Pip accumulation is critical for SAR and local resistance to bacterial pathogens. Our data indicate that biologically induced SAR conditions plants to more effectively synthesize the phytoalexin camalexin, Pip, and salicylic acid and primes plants for early defense gene expression. Biological priming is absent in the pipecolate-deficient ald1 mutants. Exogenous pipecolate induces SAR-related defense priming and partly restores priming responses in ald1. We conclude that Pip orchestrates defense amplification, positive regulation of salicylic acid biosynthesis, and priming to guarantee effective local resistance induction and the establishment of SAR.     

Azido analogs of neuroactive steroids

Analogs of pregnanolone (3α-hydroxy-5β-pregnan-20-one), modified in position 17 were prepared. Compounds with 20-keto pregnane side chain replaced completely by azide (17α- and 17β-azido-5β-androstan-3α-ol), compounds with its part replaced (20-azido-21-nor-5β-pregnan-3α-ol), and compounds with keto group only replaced ((20R)- and (20S)-20-azido-5β-pregnan-3α-ol) were synthesized using tosylate displacements with sodium azide or Mitsunobu reaction with azoimide. All five azido steroids were converted into corresponding sulfates. Subsequent tests for inhibition of glutamate induced response on NMDA receptors revealed that modification of pregnanolone sulfate side chain with azide did not disturb the activity and some of sulfates tested were more active than parent compound.     

Phenotypic profiling of mGlu7 knockout mice reveals new implications for neurodevelopmental disorders

Neurodevelopmental disorders are characterized by deficits in communication, cognition, attention, social behavior and/or motor control. Previous studies have pointed to the involvement of genes that regulate synaptic structure and function in the pathogenesis of these disorders. One such gene, GRM7, encodes the metabotropic glutamate receptor 7 (mGlu₇), a G protein‐coupled receptor that regulates presynaptic neurotransmitter release. Mutations and polymorphisms in GRM7 have been associated with neurodevelopmental disorders in clinical populations; however, limited preclinical studies have evaluated mGlu₇ in the context of this specific disease class. Here, we show that the absence of mGlu₇ in mice is sufficient to alter phenotypes within the domains of social behavior, associative learning, motor function, epilepsy and sleep. Moreover, Grm7 knockout mice exhibit an attenuated response to amphetamine. These findings provide rationale for further investigation of mGlu₇ as a potential therapeutic target for neurodevelopmental disorders such as idiopathic autism, attention deficit hyperactivity disorder and Rett syndrome.     

Slow recovery of arbuscular mycorrhizal fungi and plant community after fungicide application: An eight‐year experiment

Aim

In our previous study, we found strong effects of fungicide application on diversity and composition of grassland plant community. Here, we evaluated the recovery of the plant community and arbuscular mycorrhizal fungi (AMF ) infectivity after fungicide application and the effects of grazing management on the recovery.

Location

Northern Bohemia, Czech Republic.

Methods

We recorded plant species composition and AMF infectivity in permanent plots in dry grassland over a period of 5 years after termination of fungicide application and grazing introduction.

Results

The negative effect of fungicide on plant species composition, diversity, AMF infectivity and cover of forbs still persisted 5 years after the last fungicide application. The cover of graminoids decreased, and their cover reached the level before fungicide application. While grazing had no effect on plant species recovery, it led to recovery of AMF infectivity.

Conclusion

Although graminoids lost their dominance after termination of fungicide application and grazing led to the recovery of AMF infectivity, the dry grassland plant community was not completely restored. The forbs were not able to recolonize the site. Their absence might be caused by dispersal limitation or changes in restored AMF community composition. Direct seed sowing may thus be used to support the plant recovery.

     

LTR retrotransposon dynamics in the evolution of the olive (Olea europaea) genome

Improved knowledge of genome composition, especially of its repetitive component, generates important information for both theoretical and applied research. The olive repetitive component is made up of two main classes of sequences: tandem repeats and retrotransposons (REs). In this study, we provide characterization of a sample of 254 unique full-length long terminal repeat (LTR) REs. In the sample, Ty1-Copia elements were more numerous than Ty3-Gypsy elements. Mapping a large set of Illumina whole-genome shotgun reads onto the identified retroelement set revealed that Gypsy elements are more redundant than Copia elements. The insertion time of intact retroelements was estimated based on sister LTR’s divergence. Although some elements inserted relatively recently, the mean insertion age of the isolated retroelements is around 18 million yrs. Gypsy and Copia retroelements showed different waves of transposition, with Gypsy elements especially active between 10 and 25 million yrs ago and nearly inactive in the last 7 million yrs. The occurrence of numerous solo-LTRs related to isolated full-length retroelements was ascertained for two Gypsy elements and one Copia element. Overall, the results reported in this study show that RE activity (both retrotransposition and DNA loss) has impacted the olive genome structure in more ancient times than in other angiosperms.