Production of bacterial cellulose-based peptidopolysaccharide BC-L with anti-listerial properties using a co-cultivation strategy.

Bacterial cellulose (BC) has been found extensive applications in diverse domains for its exceptional attributes. However, the lack of antibacterial properties hampers its utilization in food and biomedical sectors. Leucocin, a bacteriocin belonging to class IIa, is synthesized by Leuconostoc that demonstrates potent efficacy against the foodborne pathogen, Listeria monocytogenes. In the current study, co-culturing strategy involving Kosakonia oryzendophytica FY-07 and Leuconostoc carnosum 4010 was used to confer anti-listerial activity to BC, which resulted in the generation of leucocin-containing BC (BC-L). The physical characteristics of BC-L, as determined by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and thermogravimetric analysis (TGA), were similar to the physical characteristics of BC. Notably, the experimental results of disc diffusion and growth curve indicated that the BC-L film exhibited a potent inhibitory effect against L. monocytogenes. Scanning electron microscopy (SEM) showed that BC-L exerts its bactericidal activity by forming pores on the bacterial cell wall. Despite the BC-L antibacterial mechanism, which involves pore formation, the mammalian cell viability remained unaffected by the BC-L film. The measurement results of zeta potential indicated that the properties of BC changed after being loaded with leucocin. Based on these findings, the anti-listerial BC-L generated through this co-culture system holds promise as a novel effective antimicrobial agent for applications in meat product preservation and packaging.

A new paradigm of learned cooperation reveals extensive social coordination and specific cortical activation in mice.

Cooperation is a social behavior crucial for the survival of many species, including humans. Several experimental paradigms have been established to study cooperative behavior and related neural activity in different animal species. Although mice exhibit limited cooperative capacity in some behavioral paradigms, it is still interesting to explore their cooperative behavior and the underlying neural mechanisms. Here, we developed a new paradigm for training and testing cooperative behavior in mice based on coordinated lever-pressing and analyzed social interactions between the animals during cooperation. We observed extensive social contact and waiting behavior in cooperating animals, with the number of such events positively correlated with the success of cooperation. Using c-Fos immunostaining and a high-speed volumetric imaging with synchronized on-the-fly scan and readout (VISoR) system, we further mapped whole-brain neuronal activity trace following cooperation. Significantly higher levels of c-Fos expression were observed in cortical areas including the frontal pole, motor cortex, anterior cingulate area, and prelimbic area. These observations highlight social interaction and coordination in cooperative behavior and provide clues for further study of the underlying neural circuitry mechanisms.

Identification and Characterization of a Predominant Hydrophobin in the Edible Mushroom Grifola frondosa.

Hydrophobins (HFBs) are a group of small, secreted amphipathic proteins of fungi with multiple physiological functions and potential commercial applications. In this study, HFB genes of the edible mushroom, Grifola frondosa, were systematically identified and characterized, and their transcriptional profiles during fungal development were determined. In total, 19 typical class I HFB genes were discovered and bioinformatically analyzed. Gene expression profile examination showed that Gf.hyd9954 was particularly highly upregulated during primordia formation, suggesting its major role as the predominant HFB in the lifecycle of G. frondosa. The wettability alteration profile and the surface modification ability of recombinant rGf.hyd9954 were greater than for the Grifola HFB HGFII-his. rGf.hyd9954 was also demonstrated to form the typical class I HFB characteristic-rodlet bundles. In addition, rGf.hyd9954 was shown to possess nanoparticle characteristics and emulsification activities. This research sheds light on the regulation of fungal development and its association with the expression of HFB genes.

Thalamocortical circuits drive remifentanil-induced postoperative hyperalgesia.

Remifentanil-induced hyperalgesia (RIH) is a severe but common postoperative clinical problem with elusive underlying neural mechanisms. Here, we discovered that glutamatergic neurons in the thalamic ventral posterolateral nucleus (VPLGlu) exhibited significantly elevated burst firing accompanied by upregulation of Cav3.1 T-type calcium channel expression and function in RIH model mice. In addition, we identified a glutamatergic neuronal thalamocortical circuit in the VPL projecting to hindlimb primary somatosensory cortex glutamatergic neurons (S1HLGlu) that mediated RIH. In vivo calcium imaging and multi-tetrode recordings revealed heightened S1HLGlu neuronal activity during RIH. Moreover, preoperative suppression of Cav3.1-dependent burst firing in VPLGlu neurons or chemogenetic inhibition of VPLGlu neuronal terminals in the S1HL abolished the increased S1HLGlu neuronal excitability while alleviating RIH. Our findings suggest that remifentanil induces postoperative hyperalgesia by upregulating T-type calcium channel-dependent burst firing in VPLGlu neurons to activate S1HLGlu neurons, thus revealing an ion channel-mediated neural circuit basis for RIH that can guide analgesic development.

Preferential subcortical collateral projections of pedunculopontine nucleus-targeting cortical pyramidal neurons revealed by brain-wide single fiber tracing.

The pedunculopontine nucleus (PPN) is a heterogeneous midbrain structure involved in various brain functions, such as motor control, learning, reward, and sleep. Previous studies using conventional tracers have shown that the PPN receives extensive afferent inputs from various cortical areas. To examine how these cortical axons make collateral projections to other subcortical areas, we used a dual-viral injection strategy to sparsely label PPN-targeting cortical pyramidal neurons in CaMKIIα-Cre transgenic mice. Using a high-speed volumetric imaging with on-the-fly-scan and Readout (VISoR) technique, we visualized brain-wide axonal projections of individual PPN-targeting neurons from several cortical areas, including the prelimbic region (PL), anterior cingulate area (ACA) and secondary motor cortex (MOs). We found that each PPN-projecting neuron had a unique profile of collateralization, with some subcortical areas being preferential targets. In particular, PPN-projecting neurons from all three traced cortical areas exhibited common preferential collateralization to several nuclei, with most neurons targeting the striatum (STR), lateral hypothalamic area (LHA) and periaqueductal gray (PAG), and a substantial portion of neurons also targeting the zona incerta (ZI), median raphe nucleus (MRN) and substantia nigra pars reticulata (SNr). Meanwhile, very specific collateralization patterns were found for other nuclei, including the intermediate reticular nucleus (IRN), parvicellular reticular nucleus (PARN) and gigantocellular reticular nucleus (GRN), which receive collateral inputs almost exclusively from the MOs. These observations provide potential anatomical mechanisms for cortical neurons to coordinate the PPN with other subcortical areas in performing different physiological functions.

Early-life inflammation promotes depressive symptoms in adolescence via microglial engulfment of dendritic spines.

Early-life inflammation increases the risk for depression in later life. Here, we demonstrate how early-life inflammation causes adolescent depressive-like symptoms: by altering the long-term neuronal spine engulfment capacity of microglia. For mice exposed to lipopolysaccharide (LPS)-induced inflammation via the Toll-like receptor 4/NF-κB signaling pathway at postnatal day (P) 14, ongoing longitudinal imaging of the living brain revealed that later stress (delivered during adolescence on P45) increases the extent of microglial engulfment around anterior cingulate cortex (ACC) glutamatergic neuronal (ACCGlu) spines. When the ACC microglia of LPS-treated mice were deleted or chemically inhibited, the mice did not exhibit depressive-like behaviors during adolescence. Moreover, we show that the fractalkine receptor CX3CR1 mediates stress-induced engulfment of ACCGlu neuronal spines. Together, our findings establish that early-life inflammation causes dysregulation of microglial engulfment capacity, which encodes long-lasting maladaptation of ACCGlu neurons to stress, thus promoting development of depression-like symptoms during adolescence.

High frequency optogenetic activation of inputs to the lateral amygdala forms distant association with foot-shock.

AIM: A hallmark of classical conditioning is that conditioned stimulus (CS) must be tightly coupled with unconditioned stimulus (US), often requiring temporal overlap between the two, or a short gap of several seconds. In this study, we investigate the temporal requirements for fear conditioning association between a strong artificial CS, high-frequency optogenetic activation of inputs into the lateral amygdala of rats, and a foot-shock to the animal with delays up to many minutes. METHODS: AAV-oChIEF-tdTomato viruses were injected into the auditory cortex and the medial geniculate nucleus of rats. An optical fiber was implanted just above the lateral amygdala of the animal. Optogenetic high-frequency stimuli (oHFS; containing five 1-s trains of 100 Hz laser pulses) were delivered to the lateral amygdala, before or after (with varying intervals) a foot-shock that elicits fear responses in the animal. Pre-trained lever-press behavior was used to assess the degree of fear recall by optogenetic test stimuli (OTS; 10 Hz for 2 min) 24 h after the association experiment. RESULTS: In contrast to the tight temporal requirement for classical conditioning with paired optogenetic moderate-frequency stimuli (oMFS; 10 Hz for 20 s) and foot-shock, oHFS followed by foot-shock with a 5-min or even 1-h (but not 3-h) interval could successfully establish an association to be recalled by OTS the next day. Meanwhile, foot-shock followed by oHFS with a 5-min (but not 1-h) interval could also establish the conditioning. Thus, distant association may be formed between temporally distant stimuli when the CS is strong.