BcSAK1, a stress-activated mitogen-activated protein kinase, is involved in vegetative differentiation and pathogenicity in Botrytis cinerea

The gene bcsak1, encoding a mitogen-activated protein kinase (MAPK) of Botrytis cinerea, was cloned and characterized. The protein has high homology to the yeast Hog1 and to corresponding MAPKs from filamentous fungi, but it shows unique functional features. The protein is phosphorylated under osmotic stress, specific fungicides, and oxidative stress mediated by H(2)O(2) and menadione. Northern blot analyses indicate that only a subset of typical oxidative stress response genes is regulated by BcSAK1. In contrast to most other fungal systems, Deltabcsak1 mutants are significantly impaired in vegetative and pathogenic development: they are blocked in conidia formation, show increased sclerotial development, and are unable to penetrate unwounded plant tissue. These data indicate that in B. cinerea the stress-activated MAPK cascade is involved in essential differentiation programs.     

Lipid‐polymorphism of plant thylakoid membranes. Enhanced non‐bilayer lipid phases associated with increased membrane permeability

Earlier experiments, using ³¹P‐NMR and time‐resolved merocyanine fluorescence spectroscopy, have shown that isolated intact, fully functional plant thylakoid membranes, in addition to the bilayer phase, contain three non‐bilayer (or non‐lamellar) lipid phases. It has also been shown that the lipid polymorphism of thylakoid membranes can be characterized by remarkable plasticity, i.e. by significant variations in ³¹P‐NMR signatures. However, changes in the lipid‐phase behaviour of thylakoids could not be assigned to changes in the overall membrane organization and the photosynthetic activity, as tested by circular dichroism and 77 K fluorescence emission spectroscopy and the magnitude of the variable fluorescence of photosystem II, which all showed only marginal variations. In this work, we investigated in more detail the temporal stability of the different lipid phases by recording ³¹P‐NMR spectra on isolated thylakoid membranes that were suspended in sorbitol‐ or NaCl‐based media. We observed, at 5°C during 8 h in the dark, substantial gradual enhancement of the isotropic lipid phases and diminishment of the bilayer phase in the sorbitol‐based medium. These changes compared well with the gradually increasing membrane permeability, as testified by the gradual acceleration of the decay of flash‐induced electrochromic absorption changes and characteristic changes in the kinetics of fast chlorophyll a‐fluorescence transients; all variations were much less pronounced in the NaCl‐based medium. These observations suggest that non‐bilayer lipids and non‐lamellar lipid phases play significant roles in the structural dynamics and functional plasticity of thylakoid membranes.     

Benno Parthier (1932–2019)

Plant Molecular Biology -     

The AMPA receptor subunits GluR-A and GluR-B reciprocally modulate spinal synaptic plasticity and inflammatory pain

Ca(2+)-permeable AMPA receptors are densely expressed in the spinal dorsal horn, but their functional significance in pain processing is not understood. By disrupting the genes encoding GluR-A or GluR-B, we generated mice exhibiting increased or decreased numbers of Ca(2+)-permeable AMPA receptors, respectively. Here, we demonstrate that AMPA receptors are critical determinants of nociceptive plasticity and inflammatory pain. A reduction in the number of Ca(2+)-permeable AMPA receptors and density of AMPA channel currents in spinal neurons of GluR-A-deficient mice is accompanied by a loss of nociceptive plasticity in vitro and a reduction in acute inflammatory hyperalgesia in vivo. In contrast, an increase in spinal Ca(2+)-permeable AMPA receptors in GluR-B-deficient mice facilitated nociceptive plasticity and enhanced long-lasting inflammatory hyperalgesia. Thus, AMPA receptors are not mere determinants of fast synaptic transmission underlying basal pain sensitivity as previously thought, but are critically involved in activity-dependent changes in synaptic processing of nociceptive inputs.     

Quantitative determination of curcuminoids in Curcuma rhizomes and rapid differentiation of Curcuma domestica Val. and Curcuma xanthorrhiza Roxb. by capillary electrophoresis

The three major curcuminoids, curcumin, demethoxycurcumin and bis-demethoxycurcumin, from Curcuma domestica Val. (Curcuma longa L.) and Curcuma xanthorrhiza Roxb. (Zingiberaceae) were fully separated and quantified in less than 5 min using a capillary zone electrophoresis method with standard fused-silica capillaries and photodiode array detection. An electrolyte solution of 20 mM phosphate, 50 mM sodium hydroxide and 14 mM beta-cyclodextrin was found to be appropriate. Quantification was performed with 3,4-dimethoxy-trans-cinnamic acid as internal standard, and the limit of detection was 0.01 mg/mL. Extraction, stabilisation during sample storage and quantification procedures were optimised and carried out with drugs and commercial curry powder from different provenances. The results were compared with the photometric method of the monograph Curcumae xanthorrhizae rhizoma of the European Pharmacopoeia.     

Purine nucleosides support the neurite outgrowth of primary rat cerebellar granule cells after hypoxia

Mammalian neurons require a constant supply of oxygen to maintain adequate cellular functions and survival. Following sustained hypoxia during ischemic events in brain, the energy status of neurons and glia is compromised, which may subsequently lead to cell death by apoptosis and necrosis. Concomitant with energy depletion is the formation of the purine nucleoside adenosine, a powerful endogenous neuroprotectant. In this paper the effect of chemical hypoxia on cell survival and neurite outgrowth of primary cerebellar granule cells was investigated. Rotenone, a mitochondrial complex I inhibitor, induced a 30.4 +/- 3.6% loss of viable cells and a 35.0 +/- 4.4% loss of neurite formation of cerebellar granule cells, which was partially restored by the addition of purine nucleosides adenosine, inosine and guanosine. Inosine had the most striking effect of 37.7 +/- 2.9% rescue of viability and 71.2 +/- 18.4% rescue of neurite outgrowth. Data confirm the suggested role of purine nucleosides for the neuronal regeneration of primary brain cells following hypoxic insult.     

SPAG11/isoform HE2C, an atypical anionic beta-defensin-like peptide

A human caput epididymidal cDNA, HE2C, was cloned based on its homology to the known chimpanzee counterpart, suggesting that the encoded beta-defensin-like peptide represented a conserved component of the innate epididymidal epithelial defense system in primates. An approximately 6kDa HE2- related peptide was co-purified together with other HE2 isoforms from human seminal plasma by affinity chromatography. By its antibody reactivity as shown by Western blot analysis, this peptide was distinct from the more abundant HE2 isoforms and was concluded to correspond to HE2C. Similar to other HE2-encoded isoforms, the endogenous HE2C was proteolytically processed from a larger precursor by a furin-like prohormone convertase. This was confirmed by N-terminal sequencing. In order to study the structural and functional properties of HE2C it was recombinantly expressed in insect cells. Post-translational processing also occurred within these cells, yielding the mature processed HE2C peptide. Correct disulfide bonding of the recHE2C peptide was shown by p-aminophenylarsineoxide(PAPAO)-agarose binding assay. Purified recHE2C strongly bound to Escherichia coli DH5alpha and Bacillus subtilis; however, it did not exhibit microbicidal activity when tested in a radial diffusion assay against these bacteria. Different from the previously described beta-defensins, the mature HE2C peptide has an anionic pI and an algebraic net charge of -1. Also, it lacks the amphipathic transitions, which, according to the Shai-Matzusaki-Huang model, are prerequisite for the membranolytic activity of antimicrobial peptides.     

Hsp42 is the general small heat shock protein in the cytosol of Saccharomyces cerevisiae

Small heat shock proteins (sHsps) are ubiquitous molecular chaperones that prevent the unspecific aggregation of proteins. So far, Hsp26 was the only unambiguously identified member of the sHsp family in Saccharomyces cerevisiae. We show here that the sHsp system in the cytosol of S. cerevisiae consists of two proteins, Hsp26 and Hsp42. Hsp42 forms large dynamic oligomers with a barrel-like structure. In contrast to Hsp26, which functions predominantly at heat shock temperatures, Hsp42 is active as a chaperone under all conditions tested in vivo and in vitro. Under heat shock conditions, both Hsp42 and Hsp26 suppress the aggregation of one-third of the cytosolic proteins. This subset is about 90% overlapping for Hsp42 and Hsp26. The sHsp substrates belong to different biochemical pathways. This indicates a general protective function of sHsps for proteome stability in S. cerevisiae. Consistent with this observation, sHsp knockout strains show phenotypical defects. Taken together, our results define Hsp42 as an important player for protein homeostasis at physiological and under stress conditions.     

Psychological impact of genetic testing for breast cancer susceptibility in women of Ashkenazi Jewish background: a prospective study

The recognition that the prevalence of three founder mutations in the BRCA1 and BRCA2 genes is over 2% in Ashkenazi Jews has resulted in numerous epidemiological research studies of this ethno-religious group. To determine the effects of incorporating research into clinical practice, a psychological impact study of women participating in an epidemiological study was conducted. Sixty women of Ashkenazi Jewish background who underwent genetic testing for founder mutations were assessed using mailed, self-administered questionnaires with validated measures of psychological outcome. Forty-three women elected to learn their results and 17 women declined to do so. Women who elected to learn their results were also assessed 7-10 days, 4 months, and 12 months after results disclosure. Women who chose to learn their results had significantly higher baseline breast cancer anxiety, compared to those who elected not to learn their results (z = -2.27; p = 0.023). Unaffected women who elected to learn their results showed a significant decrease in breast cancer anxiety 4 months (z = -2.37, p = 0.018) and 12 months (z = -3.06, p = 0.002) post-notification compared to baseline. Genetic testing for mutations common in Ashkenazi Jewish women with result disclosure does not lead to adverse psychological outcomes.