Genetic constitution of germ cells in intervarietal and interspecific chimeras of Brassica induced by in-vitro grafting

The characteristics of intervarietal and interspecific chimeras synthesized by the graft-culture method were determined by morphology, anthocyanin pigmentation pattern, and crossing. In an intervarietal chimera between YR-ranpou (green cabbage) and Ruby ball (red cabbage) in Brassica oleracea, a segregation phenomenon was noted in which seeds giving rise to purple and green plants were both produced in a single capsule in F₁ progeny from crosses of chimeras with YR ranpou, the anthocyanin-free graft partner type. The degrees of segregation varied, reflecting the structure of the chimeras. YR ranpou-dominant chimeras produced capsules in which seeds gave rise to green plants at a high frequency, while Ruby ball-dominant chimeras produced capsules in which seeds in one capsule gave rise to purple plants at a high frequency. Mixed chimeras produced capsules with green plants or purple plants more regularly than did other chimeral types. Furthermore, a chimeral type in which seeds gave rise to green and purple plants was found in 3.2% of the total crosses. Segregation patterns in the progenies corresponded with the chimeral types. Chlorophyll-deficient variation (resulting in variegation or the production of albino plants) was found at a frequency of 2.6%. These results show that chimeric tissues are actually in a mixed state and that either the ovary develops from more than two cells or else that variation occurs in the germ-cell layer. In interspecific chimeras between Ruby ball and Komatsuna (B. campestris) various types of chimeras generally showed low pollen fertility, few capsules, and low seed-setting. Progenies from selves (geitonogamy), open crosses and crosses with the two parental species produce a predominantly homogeneous genotype showing either the Ruby ball or the Komatsuna type. Only two crosses produced four interspecific hybrids which expressed variations in their morphological and isozymic characters.     

Temperature-dependent triplet and fluorescence quantum yields of the photosystem II reaction center described in a thermodynamic model.

A key step in the photosynthetic reactions in photosystem II of green plants is the transfer of an electron from the singlet-excited chlorophyll molecule called P680 to a nearby pheophytin molecule. The free energy difference of this primary charge separation reaction is determined in isolated photosystem II reaction center complexes as a function of temperature by measuring the absolute quantum yield of P680 triplet formation and the time-integrated fluorescence emission yield. The total triplet yield is found to be 0.83 +/- 0.05 at 4 K, and it decreases upon raising the temperature to 0.30 at 200 K. It is suggested that the observed triplet states predominantly arise from P680 but to a minor extent also from antenna chlorophyll present in the photosystem II reaction center. No carotenoid triplet states could be detected, demonstrating that the contamination of the preparation with CP47 complexes is less than 1/100 reaction centers. The fluorescence yield is 0.07 +/- 0.02 at 10 K, and it decreases upon raising the temperature to reach a value of 0.05-0.06 at 60-70 K, increases upon raising the temperature to 0.07 at approximately 165 K and decreases again upon further raising the temperature. The complex dependence of fluorescence quantum yield on temperature is explained by assuming the presence of one or more pigments in the photosystem II reaction center that are energetically degenerate with the primary electron donor P680 and below 60-70 K trap part of the excitation energy, and by temperature-dependent excited state decay above 165 K. A four-compartment model is presented that describes the observed triplet and fluorescence quantum yields at all temperatures and includes pigments that are degenerate with P680, temperature-dependent excited state decay and activated upward energy transfer rates. The eigenvalues of the model are in accordance with the lifetimes observed in fluorescence and absorption difference measurements by several workers. The model suggests that the free energy difference between singlet-excited P680 and the radical pair state P680+l- is temperature independent, and that a distribution of free energy differences represented by at least three values of about 20, 40, and 80 meV, is needed to get an appropriate fit of the data.     

Intramuscular injection of mechano growth factor E domain peptide regulated expression of memory-related <Emphasis Type="Italic">sod</Emphasis>, miR-134 and miR-125b-3p in rat hippocampus under simulated weightlessness

Objective

To investigate the expression of memory-related antioxidant genes and miRNAs under simulated weightlessness and the regulation of mechano growth factor (MGF) E domain, the peptide preventing nerve damage.

Results

Igf-iea and mgf mRNA levels, expression of antioxidant genes sod1 and sod2 and levels of miR-134 and miR-125b-3p increased in rat hippocampus after 14 days tail suspension to simulate weightlessness which was inhibited with intramuscular injection of E domain peptide. Therefore, administration of MGF E domain peptide could reverse increased expressions of memory-related igf-iea, mgf, sod1, sod2, miR-134 and miR-125b-3p in rat hippocampus under simulated weightlessness.

Conclusions

MGF may regulate the redox state and miRNA-targeted NR-CREB signaling, and intramuscular injection may be the alternative administration because of its safety, convenience and ability to pass through the blood brain barrier.

     

Hydrogen-Deuterium Exchange Coupled to Top- and Middle-Down Mass Spectrometry Reveals Histone Tail Dynamics before and after Nucleosome Assembly

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Modulatory effects of bufalin,an active ingredient from toad venom on voltage-gated sodium channels

Chan-su (toad venom) has been used as an analgesic agent in China from ancient to modern times. Bufalin, a non-peptide toxin extracted from toad venom, is considered as one of the analgesic components. The molecular mechanism underlying the anti-nociceptive effects of bufalin remains unclear so far. In this study, we investigated the pharmacological effects of bufalin on pain-related ion channels as well as animal models through patch clamping, calcium imaging and animal behavior observation. Using the whole-cell recording, bufalin caused remarkable suppressive effect on the peak currents of Nav channels (voltage gated sodium channels, VGSCs) of dorsal root ganglion neuroblastomas (ND7-23 cell) in a dose-dependent manner. Bufalin facilitated the voltage-dependent activation and induced a negative shift on the fast inactivation of VGSCs. The recovery kinetics of VGSCs were significantly slowed and the recovery proportion were reduced after administering bufalin. However, bufalin prompted no significant effect not only on Kv4.2, Kv4.3 and BK channels heterologously expressed in HEK293T cells, but also on the capsaicin and allyl isothiocyanate induced Ca²⁺ influx. What’s more, bufalin could observably relieve formalin-induced spontaneous flinching and licking response as well as carrageenan-induced thermal and mechanical hyperalgesia in dose-dependent manner in agreement with the results of in vitro experiments. The present results imply that the remarkable anti-nociceptive effects produced by bufalin are probably ascribed to its specific regulation on Nav channels. Bufalin inhibits the Nav channels in a dose-dependent manner, which will provide references for the optimal dose selection of analgesia drugs.     

Comparative proteomic profiling of human osteoblast‐derived extracellular matrices identifies proteins involved in mesenchymal stromal cell osteogenic differentiation and mineralization

The extracellular matrix (ECM) is a dynamic component of tissue architecture that physically supports cells and actively influences their behavior. In the context of bone regeneration, cell‐secreted ECMs have become of interest as they reproduce tissue‐architecture and modulate the promising properties of mesenchymal stem cells (MSCs). We have previously created an in vitro model of human osteoblast‐derived devitalized ECM that was osteopromotive for MSCs. The aim of this study was to identify ECM regulatory proteins able to modulate MSC differentiation to broaden the spectrum of MSC clinical applications. To this end, we created two additional models of devitalized ECMs with different mineralization phenotypes. Our results showed that the ECM derived from osteoblast‐differentiated MSCs had increased osteogenic potential compared to ECM derived from undifferentiated MSCs and non‐ECM cultures. Proteomic analysis revealed that structural ECM proteins and ribosomal proteins were upregulated in the ECM from undifferentiated MSCs. A similar response profile was obtained by treating osteoblast‐differentiating MSCs with Activin‐A. Extracellular proteins were upregulated in Activin‐A ECM, whereas mitochondrial and membrane proteins were downregulated. In summary, this study illustrates that the composition of different MSC‐secreted ECMs is important to regulate the osteogenic differentiation of MSCs. These models of devitalized ECMs could be used to modulate MSC properties to regulate bone quality.     

Molecular demarcation of surface domains as established by label-fracture cytochemistry of boar spermatozoa

We used "label-fracture" (J Cell Biol 99:1156, 1984) to establish high-resolution maps of wheat germ agglutinin (WGA) and concanavalin A (ConA) receptor sites on the cell surface of boar spermatozoa and to investigate the possible association of these receptors to integral membrane components. Label-fracture reveals intense WGA labeling over the region of the plasma membrane that overlies the acrosome, including the equatorial segment. The density of WGA receptors decreases from the post-acrosomal area to the posterior ring. The WGA receptor domain changes abruptly into a microdomain with an unusually high density of WGA receptors over a sharply delimited, particle-free zone at the base of the head. Over the tail, the density of WGA receptors in the tail is high and uniform over the midpiece, annulus, and principal piece, but narrow patches of rectilinear arrays of pits close to the annulus are not labeled. Labeling of the entire sperm head by ConA is both intense and uniform, except for the particle-free zone at the base of the head, which is barren of receptors. Over the tail, ConA labeling is strong over the midpiece, absent over the annulus, and sparse over the principal piece and the end piece. In contrast to WGA, ConA receptors co-distribute with the intramembrane particles. Our results confirm the potential of label-fracture for high-resolution mapping of the distribution of cell surface receptors. They show that in this specialized cell membrane domains can be sharply defined, i.e., apparent without free lateral diffusion of components.