Strong magnetic anisotropy in PrRu2Ga8and PrCo2Al8single crystals.

Single crystals ofLnRu2Ga8andLnCo2Al8(Ln= La and Pr) were grown using a Ga/Al self-flux method. An orthorhombic CaCo2Al8-type structure with space groupPbam(No.55) of them was identified by x-ray diffraction. LaRu2Ga8and LaCo2Al8are Pauli paramagnetic down to 2 K, while PrRu2Ga8and PrCo2Al8show antiferromagnetic (AFM) order at 2.5 and 5 K, respectively. Strong magnetic anisotropy in PrRu2Ga8and PrCo2Al8single crystals was found by an anisotropic magnetic measurement. The field-induced FM state was observed in both PrRu2Ga8and PrCo2Al8forH||c. However, in the case of H⊥c, the AFM state is robust. The strong magnetic anisotropy in PrRu2Ga8FM and PrCo2Al8is due to their anisotropic magnetic interactions that FM interactions are dominant in the case ofH||cwhile AFM interactions forH⊥c.

Effects of salt stress on the freeze-drying survival rate of Lactiplantibacillus plantarum LIP-1.

In this study, we examined the effects of different salt stress application methods on the Lactiplantibacillus plantarum LIP-1 freeze-drying survival rate. The application of salt stress during the stationary phase significantly improved Lactiplantibacillus plantarum LIP-1 freeze-drying survival rates (P < 0.05). The indirect application of salt stress via phosphate-buffered saline containing 0.4 mol/L NaCl (NB group) led to significantly higher freeze-drying survival rates compared to when salt stress was directly applied (NA group: the concentration of NaCl is 0.4 mol/L) (P < 0.05). Following exposure to salt stress, Lactiplantibacillus plantarum LIP-1 cells exuded excessive Na+ out of the cell and transported extracellular K+ into the cell, resulting in upregulation of the trkA gene, which is related to K+ transport, thereby significantly upregulating the expression of a lysR-type transcription factor, which increased the cell membrane unsaturated fatty acid content, reducing the degree of cell membrane damage and improving the freeze-drying survival rate. When the concentration of NaCl is 0.4 mol/L, compared with direct salt stress application, indirect application led to higher intracellular pH and ATP content, which effectively reduced DNA and cell membrane damage, respectively. Together, these results demonstrate that appropriate indirect salt stress application can improve Lactiplantibacillus plantarum LIP-1 freeze-drying resistance.

Effects of different initial pH values on freeze-drying resistance of Lactiplantibacillus plantarum LIP-1 based on transcriptomics and proteomics.

The growth and the resistance to adverse environments of lactic acid bacteria would be affected by adjusting the initial pH of the medium. In order to explore the effect of changing the initial pH of culture medium on the freeze-drying survival rate of the Lactiplantibacillus plantarum LIP-1, the effect of initial pH on cell membrane fatty acid composition and key enzyme activity were mainly determined, and the internal mechanism was studied by transcriptomics and proteomics methods. We found that compared with initial pH 7.4 group, initial pH 6.8 group could improve the freeze-drying survival rate of the L. plantarum LIP-1. It was possibly due to the lactate dehydrogenase (LDH) was upregulated in the initial pH6.8 group, which led to a rapid decrease in culture pH. To reduce the inhibitory effect of long-term acid environment on growth, the strain upregulated the expression of fatty acid synthesis-related genes and proteins, promoted the relative content of cyclopropane and unsaturated fatty acids, improved integrity of the cell membranes. The adjustment of fatty acid composition maintained the integrity of the cell membrane in a freeze-drying environment to improve the freeze-drying survival rate of the initial pH6.8 group. In addition, the long-term acid environment stimulated a cross-stress tolerance mechanism that significantly upregulated the expression of a cold stress protein. The results indicated that the optimal initial pH of the medium could improve the ability of L. plantarum LIP-1 to resist freeze-drying.

Resolution of subcomponents of synaptic release from postsynaptic currents in rat hair-cell/auditory-nerve fiber synapses.

The synapse between inner hair cells and auditory nerve fiber dendrites shows large excitatory postsynaptic currents (EPSCs), which are either monophasic or multiphasic. Multiquantal or uniquantal (flickering) release of neurotransmitter has been proposed to underlie the unusual multiphasic waveforms. Here the nature of multiphasic waveforms is analyzed using EPSCs recorded in vitro in rat afferent dendrites. Spontaneous EPSCs were deconvolved into a sum of presumed release events having monophasic EPSC waveforms. Results include, first, the charge of EPSCs is about the same for multiphasic versus monophasic EPSCs. Second, EPSC amplitudes decline with the number of release events per EPSC. Third, there is no evidence of a mini-EPSC. Most results can be accounted for by versions of either uniquantal or multiquantal release. However, serial neurotransmitter release in multiphasic EPSCs shows properties that are not fully explained by either model, especially that the amplitudes of individual release events are established at the beginning of a multiphasic EPSC, constraining possible models of vesicle release.NEW & NOTEWORTHY How do monophasic and multiphasic waveshapes arise in auditory-nerve dendrites; mainly are they uniquantal, arising from release of a single vesicle, or multiquantal, requiring several vesicles? The charge injected by excitatory postsynaptic currents (EPSCs) is the same for monophasic or multiphasic EPSCs, supporting uniquantal release. Serial adaptation of responses to sequential EPSCs favors a multiquantal model. Finally, neurotransmitter partitioning into similar sized release boluses occurs at the first bolus in the EPSC, not easily explained with either model.