Characterization of Interspecific Hybrids Between Oryza sativa L, and Three Wild Rice Species of China by Genomic In Situ Hybridization

In the genus Oryza, interspecific hybrids are useful bridges for transferring the desired genes from wild species to cultivated rice （Oryza sativa L.）. In the present study, hybrids between O. sativa （AA genome） and three Chinese wild rices, namely O. rufipogon （AA genome）, O. officinalis （CC genome）, and O. meyeriana （GG genome）, were produced. Agricultural traits of the F1 hybrids surveyed were intermediate between their parents and appreciably resembled wild rice parents. Except for the O. sativa × O. rufipogon hybrid, the other F1 hybrids were completely sterile. Genomic in situ hybridization （GISH） was used for hybrid verification. Wild rice genomic DNAs were used as probes and cultivated rice DNA was used as a block. With the exception of O. rufipogon chromosomes, this method distinguished the other two wild rice and cultivated rice chromosomes at the stage of mitotic metaphase with different blocking ratios. The results suggest that a more distant phylogenetic relationship exists between O. meyeriana and O. sativa and that O. rufipogon and O. sativa share a high degree of sequence homology. The average mitotic chromosome length of O. officinalis and O. meyeriana was 1.25- and 1.51-fold that of O. sativa, respectively. 4＇,6＇-Diamidino- 2-phenylindole staining showed that the chromosomes of O. officinalis and O. meyeriana harbored more heterochromatin, suggesting that the C and G genomes were amplified with repetitive sequences compared with the A genome. Although chromocenters formed by chromatin compaction were detected with wild rice-specific signals corresponding to the C and G genomes in discrete domains of the F1 hybrid interphase nuclei, the size and number of O. meyeriana chromocenters were bigger and greater than those of O. officinalis. The present results provide an important understanding of the genomic relationships and a tool for the transfer of useful genes from three native wild rice species in China to cultivars.

Decreased expression of ApoF associates with poor prognosis in human hepatocellular carcinoma

Background:Hepatocellular carcinoma(HCC)is frequently associated withmetabolism dysfunction.Increasing evidence has demonstrated the crucial role of lipidmetabolismin HCC progression.The function of apolipoprotein F(ApoF),a lipid transfer inhibitor protein,in HCC is incompletely understood.We aimed to evaluate the functional role of ApoF in HCC in this study.Methods:We used quantitative reverse-transcription polymerase chain reaction(qRT-PCR)to detect ApoF mRNA expression in HCC tissues and hepatoma cell lines(SMMC-7721,HepG2,and Huh7).Immunohistochemistry was performed to detect the expression of ApoF in HCC tissues.The associations between ApoF expression and clinicopathological features as well as HCC prognosis were analyzed.The effect of ApoF on cellular proliferation and growth of SMMC-7721 and Huh7 cells was examined in vitro and in vivo.Results:ApoF expression was significantly down-regulated at both mRNA and protein levels in HCC tissues as compared with adjacent tissues.In SMMC-7721 and Huh7 HCC cells,ApoF overexpression inhibited cell proliferation and migration.In a xenograft nude mouse model,ApoF overexpression effectively controlled HCC growth.Kaplan–Meier analysis results showed that the recurrence-free survival rate of HCC patients with low ApoF expression was significantly lower than that of other HCC patients.Low ApoF expression was associated with several clinicopathological features such as liver cirrhosis,Barcelona Clinic Liver Cancer stage and tumor-node-metastasis stage.Conclusions:ApoF expression was down-regulated in HCC,which was associated with low recurrence-free survival rate.ApoF may serve as a tumor suppressor in HCC and be a potential application for the treatment of this disease.

Heterozygosity of Knob-Associated Tandem Repeats and Knob Instability in Mitotic Chromosomes of Zea （Zea mays L. and Z. diploperennis Iltis Doebley）

Knobs are blocks of heterochromatin present on chromosomes of maize （Zea mays L.） and its relatives that have effects on the frequency of genetic recombination, as well as on chromosome behavior. Knob heterozygosity and instability in six maize inbred lines and one Z. diploperennis Iltis Doebley line were investigated using the fluorescence in situ hybridization （FISH） technique with knob-associated tandem repeats （180 bp and 350 bp （TR- 1）） as probes. Signals of seven heterozygous knobs containing 180- bp repeats and of one heterozygous knob containing TR- 1 were captured in chromosomes of all materials tested according to the results of FISH, which demonstrates that the 180-bp repeat is the main contributor to knob heterozygosity compared with the TR- 1 element. In addition, one target cell with two TR- 1 signals on one homolog of chromosome 2L, which was different from the normal cells in the maize inbred line GB57, was observed, suggesting knob duplication and an instability phenomenon in the maize genome.