MULTI-FLORET SPIKELET 2, a MYB Transcription Factor, Determines Spikelet Meristem Fate and Floral Organ Identity in Rice.

An understanding of flower and panicle development is crucial for improving yield and quality in majority of grass crops. In this study, we used mapping-based cloning to identify MULTI-FLORET SPIKELET2 (MFS2), which encodes a MYB transcription factor and regulates flower and spikelet development in rice (Oryza sativa). In the mfs2 mutant, specification of palea identity was severely disturbed and showed degradation or transformation into a lemma-like organ, and the number of all floral organs was increased to varying degrees. Due to the increase in the number of floral organs and development of extra transformed palea/marginal region of the palea-like organs, some mfs2 spikelets had a tendency to produce two florets. These defects implied that the mfs2 mutation caused abnormal specification of palea identity and partial loss of spikelet determination. We confirm that MFS2 is a transcriptional repressor that shows strong repression activity by means of two typical ethylene-responsive element binding factor-associated amphiphilic motifs, one of which locates at the C terminus and is capable of interaction with three rice TOPLESS and TOPLESS-related proteins. The results indicate that MFS2 acts as a repressor that regulates floral organ identities and spikelet meristem determinacy in rice by forming a repression complex with rice TOPLESS and TOPLESS-related proteins.

[Analysis of hepatitis C virus (HCV) subtypes in HIV/HCV co-infected and HCV mono-infected individuals in Guangdong province].

OBJECTIVE: To explore the transmission routes, genotypes/subtypes distribution and genetic character of HCV in HIV/HCV co-infected and HCV mono-infected individuals in Guangdong Province. METHODS: Reverse transcription (RT) nested PCR was performed to amplify the HCV NS5B gene region from 95 HIV/HCV co-infected and 99 HCV mono-infected individuals lived in Guangdong province. The PCR products were then sequenced for HCV subtyping. Genetic analysis was done by MEGA4 software. RESULTS: (1) HIV/HCV co-infected individuals infected HCV mostly through injection drug use (IDU, 78.9%), the HCV subtypes were identified as 6a (53.7%), 3a (17.9%), 1b (15.8%), 3b (11.6%) and 1a (1.0%) respectively, the genetic distance within subtype 1b was longer than those within other subtypes, the predominant HCV subtype in HIV/HCV co-infected individuals infected through IDU was 6a (60.0%). (2) HCV mono-infected individuals infected HCV mostly through blood or blood products transfusions (80.8%), the HCV subtypes were identified as 1b (67.7%), 6a (17.2%), 3a (6.1%), 2a (5.0%), 3b (2.0%), 4a (1.0%) and 5a (1.0%) respectively, the genetic distance within subtype 1b was also longer than those within other subtypes, the predominant HCV subtype in HCV mono-infected individuals infected through blood or blood products transfusions was 1b (76.2%). CONCLUSION: The diversity of HCV subtypes in HIV/HCV co-infected and HCV mono-infected individuals in Guangdong Province was high, both the major transmission route and HCV subtype between HIV/HCV co-infected individuals and HCV mono-infected individuals were different.

[Clinical trial of sequential antiviral therapy for patients with chronic hepatitis B in China].

OBJECTIVE: To establish a sequential antiviral regime and evaluate its efficacy in patients with chronic hepatitis B using a controlled trial. METHODS: Seventy-four patients with chronic hepatitis B were divided into 3 groups: 30 cases were enrolled in the sequential antiviral group in which patients received eight-week treatment with thymosin alpha1 (1.6 mg/time, subcutaneous injection, 2 times/week), six-month treatment with interferon (500 MU/ times, muscle inject, every other day) begun in the fifth week of the therapeutic course, and lamivudine treatment (100 mg/days) begun 2 months later after HBeAg seroconversion or just after the withdrawal of interferon to more than eighteen months. Fourteen cases were enrolled in combination group in which patients received six-month treatment with interferon and thymosin alpha1 simultaneously in the same manner as in sequential antiviral group. Thirty cases were enrolled in lamivudine group in which patients received more than eighteen-month treatment with lamivudine. RESULTS: The temporary rates of HBeAg seroconversion and normalization of alanine aminotransferase (effective rate) in sequential antiviral group, combination group and lamivudine group were 76.7%, 78.6% and 13.3%, respectively. The effective rates of sequential group and combination group were very similar, and significantly higher than that of lamivudine group (P less than 0.01). Long-term efficacy rates were 76.7%, 57.1% and 16.7% among the three groups, respectively. The long-term effective rate of sequential group was relatively higher. The rate of liver damage sensitive period in sequential antiviral group and combination group was 47.7%. The time of onset was from 2 to 8 weeks after the treatment begun, earlier than that from 6 to 8 weeks after the beginning of interferon alone in the literature. CONCLUSION: Sequential antiviral therapy had much higher rates of long-term HBeAg seroconversion, undetectable HBV DNA and normalization of alanine aminotransferase with good cost-effectiveness. Its mechanism to promote the antiviral effect might be dependent on the immunoregulatory action of thymosin alpha1 in the earlier period and the specific inhibition of HBV DNA replication by lamivudine in the later period of the therapeutic course.