Arabidopsis AGAMOUS-LIKE16 and SUPPRESSOR OF CONSTANS1 regulate the genome-wide expression and flowering time

Flowering transition is tightly coordinated by complex gene regulatory networks, in which AGAMOUS-LIKE 16 (AGL16) plays important roles. Here, we identified the molecular function and binding properties of AGL16 and demonstrated its partial dependency on the SUPPRESSOR OF CONSTANS 1 (SOC1) function in regulating flowering. AGL16 bound to promoters of more than 2,000 genes via CArG-box motifs with high similarity to that of SOC1 in Arabidopsis (Arabidopsis thaliana). Approximately 70 flowering genes involved in multiple pathways were potential targets of AGL16. AGL16 formed a protein complex with SOC1 and shared a common set of targets. Intriguingly, only a limited number of genes were differentially expressed in the agl16-1 loss-of-function mutant. However, in the soc1-2 knockout background, AGL16 repressed and activated the expression of 375 and 182 genes, respectively, with more than a quarter bound by AGL16. Corroborating these findings, AGL16 repressed the flowering time more strongly in soc1-2 than in the Col-0 background. These data identify a partial inter-dependency between AGL16 and SOC1 in regulating genome-wide gene expression and flowering time, while AGL16 provides a feedback regulation on SOC1 expression. Our study sheds light on the complex background dependency of AGL16 in flowering regulation, thus providing additional insights into the molecular coordination of development and environmental adaptation.

[Effects and mechanisms of allogeneic epidermal stem cells on the survival of allogeneic full-thickness skin grafts in nude mice with full-thickness skin defect wounds]

Objective: To investigate the effects and mechanisms of allogeneic epidermal stem cells (ESCs) on the survival of allogeneic full-thickness skin grafts in nude mice with full-thickness skin defect wounds. Methods: Experimental research methods were applied. Primary ESCs that appeared paving stone-like after being cultured for 7 d were obtained by enzymatic digestion method from one 4-week-old male BALB/c-NU nude mouse (the same strain, age, and sex below). The cells of third passage were identified by flow cytometry to positively express ESC marker CD44 and negatively express CD45, meanwhile, the positive expression of ESC markers of p63 and integrin 6α, and negative expression of CD71 were identified by immunofluorescence method. The ESCs of third passage in the logarithmic growth phase were used for the following experiments. Twenty-six nude mice were equally divided into phosphate buffered saline (PBS) group and ESCs group according to the random number table. A full-thickness skin defect wound was made on the back of each nude mouse, and then the wounds of the two groups were sprayed with equal volumes of PBS and ESCs, respectively. The wounds were transplanted with full-thickness skin grafts cut from the backs of 4 other nude mice. Each ten nude mice from the two groups were selected, the wound healing and skin survival on post surgery day (PSD) 0 (immediately), 3, 7, 14, and 21 were observed, and the survival ratio and shrinkage rate of skin grafts on PSD 3, 7, 14, and 21 were calculated (the number of sample was the number of surviving skin grafts at each time point); the blood perfusion in the skin grafts on PSD 3, 7, and 14 was detected by the laser speckle blood flow imager, and the blood flow ratio of nude mice skin grafts in ESCs group to PBS group at each time point was calculated (the number of sample was the pair number of surviving skin grafts in group pairing at each time point). The skin graft tissue of each 3 nude mice remained in the two groups were collected on PSD 7, and the mRNA expressions and protein expressions of tumor necrosis factor α (TNF-α), interleukin 8 (IL-8), IL-10, type Ⅰ collagen, type Ⅲ collagen, and matrix metalloproteinase 9 (MMP-9) in the tissue were detected by real-time fluorescent quantitative reverse transcription polymerase chain reaction and Western blotting, respectively. Data were statistically analyzed with Log-rank test, analysis of variance for repeated measurement, one-way analysis of variance, independent sample t test, and Bonferroni correction. Results: Taking the condition on PSD 0 as a reference, the wounds of nude mice in the two groups healed gradually on PSD 3, 7, 14, and 21, and the shrinkage of skin grafts was gradually obvious. Among them, the shrinkage healing of wound of nude mice in PBS group was more significant than that in ESCs group. On PSD 3, the skin graft of 1 nude mouse failed in ESCs group, while the skin graft of 3 nude mice failed in PBS group. On PSD 7, the skin graft of another nude mouse failed in PBS group. The survival ratio of skin grafts of nude mice in the two groups was similar on PSD 3, 7, 14, and 21 (P>0.05). On PSD 3, 7, 14, and 21, the shrinkage rates of skin grafts of nude mice in ESCs group were (9.2±0.4)%, (19.7±1.2)%, (53.6±3.5)%, and (62.2±5.1)%, respectively, which was significantly lower than (11.0±0.9)%, (47.8±2.8)%, (86.1±7.1)%, and (89.7±9.0)% in PBS group (t=5.719, 26.650, 11.940, 7.617, P<0.01). On PSD 3, 7, and 14, blood perfusion signals were observed in the skin grafts of nude mice in the two groups. The average blood perfusion ratios of the skin grafts of nude mice in ESCs group to PBS group were greater than 1, and there was no statistically significant difference in the overall comparison of 3 time points (P>0.05). On PSD 7, compared with those of PBS group, the mRNA and protein expressions of TNF-α, IL-8, type Ⅰ collagen, and type Ⅲ collagen in the skin graft tissue of nude mice in ESCs group were significantly reduced, while the mRNA and protein expressions of IL-10 and MMP-9 in the skin graft tissue of nude mice in ESCs group were significantly increased (in mRNA comparison, t=2.823, 2.934, 2.845, 2.860, 3.877, 2.916, P<0.05). Conclusions: Allogeneic ESCs can reduce the shrinkage of allogeneic full-thickness skin grafts transplanted on full-thickness skin defect wounds in nude mice, promote the formation of new blood vessels between the skin graft and the wound, reduce inflammation and collagen protein expression, and promote the expression of MMP-9, thus improving the survival quality of skin grafts.

[Feasibility of radiofrequency ablation for cancer patients with atrial fibrillation]

Objective: To analyze the impact of cancer on the recurrence rate of atrial fibrillation (AF) after AF radiofrequency ablation and further evaluate the feasibility of radiofrequency ablation therapy in cancer patients with AF. Methods: This study was a single-center, retrospective study. Cancer patients with AF undergoing radiofrequency ablation for the first time in the First Affiliated Hospital of Dalian Medical University from May 30, 2008 to September 30, 2018 were included (cancer group). AF patients without cancer undergoing radiofrequency ablation for the first time during the same period served as non-cancer group. Clinical data including age, gender, past history, cancer and AF-related parameters, etc. were analyzed. Patients were followed up after radiofrequency ablation. The primary endpoints were AF recurrence or all-cause death. Kaplan-Meier survival analysis was used to analyze the effect of cancers on the recurrence after AF ablation. The multivariate cox regression analysis was further applied to correct for other confounding factors to analyze whether the impact of cancers on the recurrence of atrial fibrillation was statistically significant. Results: A total of 90 patients were enrolled, there were 30 patients in the cancer group (mean age (64.8±6.6) years, 16 (53.3%) males) and 60 patients in the non-cancer group (mean age (63.6±6.2) years, 32 (53.3%) males). Clinical data, such as age, gender, and cancer treatment, were similar between the two groups. During an average follow-up period of (328.7±110.2) days, there were 6 AF recurrences (recurrence rate 20.0%) in the cancer group, and 17 AF recurrences (recurrence rate 28.3%) in the control group. AF recurrence rate was similar between the two groups (P>0.05). During the follow-up period, there was no all-cause death in the two groups. Kaplan-Meier survival analysis showed that cancer was not related to AF recurrence after radiofrequency ablation (P = 0.383). After adjusting for other confounding factors, the multivariate Cox regression analysis showed that cancer was not an independent predictor of AF recurrence after radiofrequency ablation (HR=0.508, 95%CI: 0.192-1.342, P = 0.172). Conclusions: The combination of cancer has no impact on the recurrence of AF after radiofrequency ablation. For cancer patients with AF, radiofrequency ablation therapy can be considered as a feasible heart rhythm control treatment strategy.

Synaptic connections between trigemino-parabrachial projection neurons and gamma-aminobutyric acid- and glycine-immunoreactive terminals in the rat

The synaptic connections between gamma-aminobutyric acid (GABA)- and glycine-immunoreactive terminals and neurons projecting to the lateral parabrachial region were examined by a combination of retrograde tracing and immunohistochemical staining in the rat medullary dorsal horn. After injection of horseradish peroxidase (HRP) into the right lateral parabrachial region, HRP retrogradely labeled neurons were observed bilaterally in laminae I, II and III of the medullary dorsal horn with an ipsilateral predominance. GABA- and glycine-like immunoreactive terminals were found in laminae I, II and III. Some of these GABA- and glycine-like immunoreactive terminals were observed chiefly to make symmetric synapses with HRP-labeled neuronal cell bodies and dendritic processes. The present results indicate that neurons in the medullary dorsal horn projecting to the lateral parabrachial region might be modulated by GABAergic and glycinergic inhibitory intrinsic neurons, which might be significantly involved in the regulation of the noxious information transmission.

[Synthesis and biological activity of substance P analogs]

Substance P (SP) and its three analogs were synthesized through solid-phase procedure. The fully-protected peptide-resin was cleaved with anhydrous HF.--SH of Cys in [Cys5,9] SP(4-11) was protected with Acm, then deprotected through Iodine oxidation method, the disulfide bridge cyclization was formed subsequently. The crude product was purified on C18 RP-HPLC. The results of guinea-pig isolated ileum test (GPI) showed that the potency of the analogs was as follows: [AcGln5, Pro9] SP(5-11) > SP > SP(4-11) > [Cys5,9] SP(4-11). They induced GPI to contract very fast and showed the characteristics of tachykinin. On the writing test in mice, the results showed: [Cys5,9] SP(4-11) > SP > SP(4-11) > [AcGln5, Pro9] SP(5-11). The biological tests showed that the SP analogs have some extent of selectivity.

Fos expression in serotonergic midbrain neurons projecting to the paraventricular nucleus of hypothalamus after noxious stimulation of the stomach: a triple labeling study in the rat

Horseradish peroxidase (HRP) was stereotaxically injected into the paraventricular nucleus of the hypothalamus (PVH) and visceral noxious stimulation was given by an administration of formalin into the stomach. The brain sections were subjected to HRP histochemistry and immunostained with Fos and serotonin antibodies. The periaqueductal gray (PAG) and dorsal raphe nucleus (DR) contained single-labeled (Fos, 5HT, HRP), double-labeled (Fos/HRP, Fos/5HT, HRP/5HT) and triple-labeled (HRP/Fos/5HT) neurons. Triple-labeled neurons were mainly observed in the DR and in discrete areas of the PAG ipsilateral to side of the HRP injection. These findings suggest that a population of serotonergic midbrain neurons receive nociceptive visceral information and project to the PVH.

Medullary catecholaminergic neurons projecting to lateral hypothalamic area and expressing Fos after chemical stimulation of the stomach in the rat

Catecholaminergic neurons in the medulla projecting to lateral hypothalamic area (LH) and expressing Fos were investigated in the rat by a triple labelling method, in which horseradish peroxidase (HRP) was injected into the LH, and visceral noxious stimulation was induced by formalin injection into the stomach, sections of the medulla were stained histochemically for HRP and immunohistochemically for Fos and tyrosine hydroxylase (TH). Some neurons labeled with HRP and showing both Fos- and TH-like immunoreactivities were mainly found in the nucleus tractus solitarii (NTS) and ventrolateral medulla (VLM) at the middle and caudal levels of medulla, only a few of them were located in the reticular formation between NTS and VLM. These results indicated that some medullary catecholaminergic neurons projected to the LH and some of them might be involved in the transmissing processes of stress responses to the visceral nociceptive information produced by chemical stimulation.

[Synthesis and biological activity of dynorphin A-(1-13) analogs]

Dynorphin A-(1-13) (I) and its two analogs were synthesized by solid-phase method. Fully-protected peptides were cleaved from the resin with HF. The three products were purified and their analgesic activity (antiwrithing response in mouse) and receptor affinity in mouse vas deferens (MVD) and rabbit vas deferens (RVD) were measured. The biological and pharmacological results showed that the replacement of Gla2, Ile8 and Pro10 by D-Ala8 and D-Pro10 caused an increase in analgesic activity, receptor affinity and selectivity. In analgesia and RVD assay, its activity is 2.6 times and 135 times respectively higher than dynorphin A-(1-13). The structure-activity relationships were briefly discussed.

Serotonin-, substance P- and tyrosine hydroxylase-like immunoreactive neurons projecting from the periaqueductal gray to the ventromedial hypothalamic nucleus in the rat

Direct projections from serotonin-, substance P- and tyrosine hydroxylase-like immunoreactive neurons in the midbrain periaqueductal gray (PAG) to the ventromedial hypothalamic nucleus (VMH) in the rat were investigated by the retrograde horseradish peroxidase tracing method combined with the immunocytochemical technique. Serotonin-, substance P- and tyrosine hydroxylase-like immunoreactive PAG neurons sending their axons to the VMH were distributed in the ventrolateral subnucleus and ventral portion of the medial subnucleus of PAG at the middle and caudal levels.