Isolation and identification of two new alleles of STICHEL in Arabidopsis.

Plant trichome has long been selected as a model system to study the regulatory mechanism during cell development due to its unique growth characteristics. In an effort to explore new components that contribute to trichome development, we performed large-scale forward genetic screening in Arabidopsis, and found two recessive mutants with significant trichome branching defects, both of which display one branched trichomes. After map-based cloning, genetic complementation experiments, we confirmed that they are new alleles of STICHEL (STI) that has been reported to act as a key regulator of trichome branching. The predicted product of STI gene is comprised by three functional domains including a large domain with sequence similarity to eubacterial DNA polymerase III γ-subunit in the middle, two PEST domains in the N terminal, and two nuclear localization signals (NLS) at the very N terminal and C terminal, respectively. Our biochemistry and molecular analysis indicated that a PEST domain in the N-terminal could be important for STI functioning in regulating trichome branching. It can directly interact with BRACHLESS TRICHOME (BLT), an important linker of cell shape and endoreplication. Because the previously data showed that the function of STI in regulating trichome branching was not linked to DNA replication and actin or microtubule cytoskeleton configuration, our findings of the direct interaction domains between STI and BLT veiled the probable roles of STI in cell morphogenesis.

[Experiment study on ultrashort wave for treating vascular crisis after rat tail replantation].

OBJECTIVE: To explore the effect and mechanism of ultrashort wave (USW) for prevention and treatment of vascular crisis after rat tail replantation. METHODS: Eighty 3-month old female Sprague Dawley rats (weighing 232.8-289.6 g) were randomly divided into 5 groups. In each group, based on the caudal vein and the coccyx was retained, the tail was cut off. The tail artery was ligated in group A; the tail artery was anastomosed in groups B, C, D, and E to establish the tail replantation model. After surgery, the rats of group B were given normal management; the rats of group C were immediately given intraperitoneal injection (3.125 mL/kg) of diluted papaverine hydrochloride injection (1 mg/mL); the rats of groups D and E were immediately given the local USW treatment (once a day) at anastomotic site for 5 days at the dosage of 3 files and 50 mA for 20 minutes (group D) and 2 files and 28 mA for 20 minutes (group E). The survival rate of the rat tails was observed for 10 days after the tail replantation. The tail skin temperature difference between proximal and distal anastomosis was measured at pre- and post-operation; the change between postoperative and preoperative temperature difference was calculated. The blood plasma specimens were collected from the inner canthus before operation and from the tip of the tail at 8 hours after operation to measure the content of nitric oxide (NO). RESULTS: The survival rates of the rat tails were 0 (0/14), 36.4% (8/22), 57.1% (8/14), 22.2% (4/18), and 75.0% (9/12) in groups A, B, C, D, and E, respectively, showing significant overall differences among 5 groups (chi2 = 19.935, P = 0.001); the survival rate of group E was significantly higher than that of group B at 7 days (P < 0.05), but no significant difference was found between the other groups by pairwise comparison (P > 0.05). At preoperation, there was no significant difference in tail skin temperature difference among 5 groups (P > 0.05); at 8 hours, 5 days, 6 days, and 7 days after operation, significant overall difference was found in the change of the skin temperature difference among groups (P < 0.05); pairwise comparison showed significant differences after operation (P < 0.05): group B > group D at 8 hours, group C > group D at 5 days, groups A, B, and C > group D at 6 days, groups B and C > groups A and E, and group B > group D at 7 days; but no significant difference was found between the other groups at the other time points (P > 0.05). Preoperative plasma NO content between each group had no significant difference (P > 0.05). The overall differences had significance in the NO content at postopoerative 8 hours and in the change of the NO content at pre- and post-operation among groups (P < 0.05). Significant differences were found by pairwise comparison (P < 0.05): group D > groups A, B, and C in the plasma NO content, group D > groups A and B in the change of the NO content at pre- and post-operation; but no significant difference was found between the other groups by pairwise comparison (P > 0.05). CONCLUSION: Rat tail replantation model in this experiment is feasible. USW therapy can increase the survival rate of replanted rat tails, reduce skin temperature at 7 days, improve blood supply, increase the content of nitric oxide at the early period and prevent vascular crisis.