Circ_0001742 promotes tongue squamous cell carcinoma progression via miR-431-5p/ATF3 axis.

OBJECTIVE: Circular RNAs (circRNAs) have been demonstrated to involve in the development of various cancers. This study aimed to investigate the functions of circ_0001742 on regulating tongue squamous cell carcinoma (TSCC) development and the underlying mechanisms. PATIENTS AND METHODS: The expression of circ_0001742, miR-431-5p and activating transcription factor 3 (ATF3) mRNA was detected by quantitative real-time polymerase chain reaction (qRT-PCR). The protein levels of epithelial-mesenchymal transition (EMT)-related proteins and ATF3 were measured by Western blot analysis. 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide (MTT) and flow cytometry assay were used to evaluate cell proliferation and apoptosis. Besides, Cell migration and invasion were assessed by transwell assay. The relationships between circ_0001742 and miR-431-5p, miR-431-5p and ATF3 were predicted by online software and confirmed by dual-luciferase reporter assay, RNA immunoprecipitation (RIP), and pull-down assay. RESULTS: The expression of circ_0001742 was upregulated in TSCC tissues and cells. Knockdown of circ_0001742 inhibited proliferation, migration, invasion and EMT and induced apoptosis in TSCC cells. Then, miR-431-5p was identified as a target of circ_0001742, and knockdown of miR-431-5p reversed the effects of circ_0001742 knockdown on proliferation, apoptosis, migration, invasion and EMT of TSCC cells. Moreover, miR-431-5p could bind to ATF3, and overexpression of ATF3 rescued the effects mediated by miR-431-5p in TSCC cells. In addition, circ_0001742 regulated ATF3 expression through miR-431-5p. CONCLUSIONS: Our results demonstrated that circ_0001742 plays a tumor-promoting effect in TSCC cells by serving as a competing endogenous RNA (ceRNA) to regulate miR-431-5p/ATF3 axis, which might provide a potential therapeutic target for TSCC.

Evaluation of the effectiveness of air pollution control measures in Hong Kong.

From 2005 to 2013, volatile organic compounds (VOCs) and other trace gases were continuously measured at a suburban site in Hong Kong. The measurement data showed that the concentrations of most air pollutants decreased during these years. However, ozone (O3) and total non-methane hydrocarbon levels increased with the rate of 0.23 ± 0.03 and 0.34 ± 0.02 ppbv/year, respectively, pointing to the increasing severity of photochemical pollution in Hong Kong. The Hong Kong government has ongoing programs to improve air quality in Hong Kong, including a solvent program implemented during 2007-2011, and a diesel commercial vehicle (DCV) program since 2007. From before to after the solvent program, the sum of toluene, ethylbenzene and xylene isomers decreased continuously with an average rate of -99.1 ± 6.9 pptv/year, whereas the sum of ethene and propene increased by 48.2 ± 2.0 pptv/year from before to during the DCV program. Despite this, source apportionment results showed that VOCs emitted from diesel exhaust decreased at a rate of -304.5 ± 17.7 pptv/year, while solvent related VOCs decreased at a rate of -204.7 ± 39.7 pptv/year. The gasoline and liquefied petroleum gas vehicle emissions elevated by 1086 ± 34 pptv/year, and were responsible for the increases of ethene and propene. Overall, the simulated O3 rate of increase was lowered from 0.39 ± 0.03 to 0.16 ± 0.05 ppbv/year by the solvent and DCV programs, because O3 produced by solvent usage and diesel exhaust related VOCs decreased (p < 0.05) by 0.16 ± 0.01 and 0.05 ± 0.01 ppbv/year between 2005 and 2013, respectively. However, enhanced VOC emissions from gasoline and LPG vehicles accounted for most of the O3 increment (0.09 ± 0.01 out of 0.16 ± 0.05 ppbv/year) in these years. To maintain a zero O3 increment in 2020 relative to 2010, the lowest reduction ratio of VOCs/NOx was ∼1.5 under the NOx reduction of 20-30% which was based on the emission reduction plan for Pearl River Delta region in 2020.

Masking white spots of enamel in caries lesions with a non-invasive infiltration technique in vitro.

We investigated the treatment effect of non-invasive infiltration on early caries caused by different degrees of enamel demineralization. Forty specimens of early enamel caries were prepared and divided into low and high demineralization groups. After treatment with non-invasive infiltration, the specimens were placed under cariogenic conditions. Color measurements were determined using a spectrophotometer 4 times to obtain chromatism values (ΔE1-ΔE4), including before and after production of artificial caries, and after infiltration treatment and re-demineralization. The effects of color change on early caries using non-invasive infiltration were compared between the 2 demineralization groups. Color differences before the production of artificial caries and after infiltration treatment and re-demineralization could not be distinguished by direct observation. Color differences after the production of artificial caries and after infiltration treatment and re-demineralization could be distinguished by direct observation. There were no significant differences in the 4 chromatism values (ΔE1-ΔE4) between the 2 groups. Non-invasive infiltration showed an excellent ability to mask white spot lesions and maintained high color stability. Treatment of high and low demineralization of enamel had the same masking effect.

The molecular clock revisited: the rate of synonymous vs. replacement change in Drosophila.

Rates of synonymous and nonsynonymous substitution were investigated for 24 genes in three Drosophila species, D. pseudoobscura, D. subobscura, and D. melanogaster. D. pseudoobscura and D. subobscura, two distantly related members of the obscura clade, differ on average by 0.29 synonymous nucleotide substitutions per site. D. melanogaster differs from the two obscura species by an average of 0.81 synonymous substitutions per site. Using a method developed by Gillespie, we investigated the variance to mean ratio, or Index of Dispersion, R, of substitutions along the three species' branches to test the fundamental prediction of the neutral theory of molecular evolution, E(R) = 1. For nonsynonymous substitutions, the average R, Ra is 1.6, which is not significantly different from the neutral theory prediction. Only 5 of the 24 genes had significantly large Ra valves, and 12 of the genes had Ra estimates of less than one. In contrast, the Index of Dispersion for synonymous substitutions was significantly large for 12 of the 24 genes, with an average of R(s) = 4.4, also statistically significant. These findings contrast with results for mammals, which showed overdispersion of nonsynonymous substitutions, but not of synonymous substitutions. Weak selection acting to maintain codon bias in Drosophila, but not in mammals, may be important in explaining the high variance in the rate of synonymous substitutions in this group of organisms.

Nucleotide variation in the triosephosphate isomerase (Tpi) locus of Drosophila melanogaster and Drosophila simulans.

DNA sequence variation in a 1.1-kb region including the coding portion of the Tpi locus was examined in 25 homozygous third-chromosome lines of Drosophila melanogaster, nine lines of Drosophila simulans, and one line of Drosophila yakuba. Our data show that the widespread allozyme polymorphism observed in cosmopolitan D. melanogaster is due to a glutamic acid substitution occurring in a phylogenetically conserved lysine that has been identified as part of the "hinged-lid" active site of the enzyme. This observation suggests that the replacement polymorphism may have important functional consequences. One replacement polymorphism was also observed in D. simulans, although its functional relevance is more difficult to assess, since it affects a site that is not strongly conserved. This amino acid change in D. simulans is associated with a single lineage possessing seven unique silent substitutions, which may be indicative of balancing selection or population subdivision. The absence of fixed amino acid differences between D. melanogaster and D. simulans and only a single difference with D. yakuba suggests that triose phosphate isomerase is under strong functional constraint. Silent variation is slightly higher for D. melanogaster than for D. simulans. Finally, we outline the general lack of evidence for old balanced polymorphisms at allozyme loci in D. melanogaster.

Genetic basis of sperm and testis length differences and epistatic effect on hybrid inviability and sperm motility between Drosophila simulans and D. sechellia.

Results are reported from a genetic study of hybrid inviability and three 'fertilization traits' (sperm motility and length, and testis size) that affect hybrid sterility between the sibling species Drosophila simulans and D. sechellia. The main findings are as follows. (i) For sperm length there was a dominant effect of the D. simulans genome over that of D. sechellia, and the Y chromosome of D. sechellia in the background of D. simulans reduced the sperm length. (ii) In contrast, testis length, in spite of its generally high correlation with sperm length, showed an additive effect. (iii) We found a strong asymmetric incompatibility between the D. sechellia X chromosome and D. simulans autosomes: D. sechellia X chromosome with D. simulans autosomes, but not the reverse, showed a significant reduction in testis length as well as in hybrid inviability compared to the parental species. (iv) Between the two autosomes, chromosome 3 had a greater effect on these traits than chromosome 2, and there was additionally an epistatic effect between these chromosomes with respect to their parental vs. recombinant status: recombinant chromosomes 2 and 3, together, had lower viability than any other combination. (v) The testis size in the backcross generation was greater than the parental species, suggesting that some modifier genes are being released from their species-specific genetic control. (vi) The species-specific homogeneity of the genome was important for all three traits--offspring viability, hybrid male fertility and testis length. These results are discussed with respect to the role of sexual selection and genetic divergence during speciation.

Simple strategy for sequencing cDNA clones.

We describe a simple method for constructing subclones containing overlapping nested deletions from cDNA clones (both lambda phage clones and plasmid clones). A PCR-amplified insert is partially digested with 4-cutter restriction enzyme(s). Complete digestion of this DNA with two restriction enzymes, having unique cutting sites at one or the other end of the amplified DNA, creates two sets of overlapping nested subfragments. When recloned into each of two doubly cut pBluescript plasmid vectors, only the two sets of nested subfragments are produced. Minimal nested sets can be constructed by screening subclones using colony PCR, and this set can then be used to determine the entire sequence of the cDNA clone. This method requires only a single cloning step and can be generated from an insert that is amplified directly from a lambda phage clone. This procedure eliminates the sequencing redundancy problem inherent in shotgun cloning, allows large clones to be sequenced using universal primers only and is well-suited for automated DNA-sequencing. Using this method, we successfully sequenced five cDNA clones of five Drosophila subobscura genes.

A general method for identifying major hybrid male sterility genes in Drosophila.

The genes responsible for hybrid male sterility in species crosses are usually identified by introgressing chromosome segments, monitored by visible markers, between closely related species by continuous backcrosses. This commonly used method, however, suffers from two problems. First, it relies on the availability of markers to monitor the introgressed regions and so the portion of the genome examined is limited to the marked regions. Secondly, the introgressed regions are usually large and it is impossible to tell if the effects of the introgressed regions are the result of single (or few) major genes or many minor genes (polygenes). Here we introduce a simple and general method for identifying putative major hybrid male sterility genes which is free of these problems. In this method, the actual hybrid male sterility genes (rather than markers), or tightly linked gene complexes with large effects, are selectively introgressed from one species into the background of another species by repeated backcrosses. This is performed by selectively backcrossing heterozygous (for hybrid male sterility gene or genes) females producing fertile and sterile sons in roughly equal proportions to males of either parental species. As no marker gene is required for this procedure, this method can be used with any species pairs that produce unisexual sterility. With the application of this method, a small X chromosome region of Drosophila mauritiana which produces complete hybrid male sterility (aspermic testes) in the background of D. simulans was identified. Recombination analysis reveals that this region contains a second major hybrid male sterility gene linked to the forked locus located at either 62.7 +/- 0.66 map units or at the centromere region of the X chromosome of D. mauritiana.

A combined classical genetic and high resolution two-dimensional electrophoretic approach to the assessment of the number of genes affecting hybrid male sterility in Drosophila simulans and Drosophila sechellia.

We have attempted to estimate the number of genes involved in postzygotic reproductive isolation between two closely related species, Drosophila simulans and Drosophila sechellia, by a novel approach that involves the use of high resolution two-dimensional gel electrophoresis (2DE) to examine testis proteins in parents, hybrids and fertile and sterile backcross progenies. The important results that have emerged from this study are as follows: (1) about 8% of about 1000 proteins examined showed divergence (presence/absence) between the two species; (2) by tracing individual proteins in parental, hybrid and backcross males, we were able to associate the divergent proteins with different chromosomes and found that most divergent proteins are associated with autosomes and very few with X chromosome, Y chromosome and cytoplasm; (3) when proteins showing both quantitative and qualitative differences between the two species were examined in F1 hybrid males, most (97.4%) proteins were expressed at levels between the two parents and no sign of large scale changes in spot density was observed. All the proteins observed in the two parental species were present in F1 hybrid males except two species-specific proteins that may be encoded (or regulated) by sex chromosomes; (4) when different fertile and sterile backcross male testes were compared, a few D. sechellia-specific proteins were identified to be consistently associated with male sterility. These results along with the observation that a large proportion (23.6%) of first generation backcross males were fertile show that hybrid male sterility between D. simulans and D. sechellia involves a relatively small number of genes. Role of large scale genetic changes due to general genome incompatibility is not supported. The results also suggest that the large effect of X chromosome on hybrid male sterility is not due to higher divergence of X chromosome than autosomes.

The genetic basis of Haldane's rule and the nature of asymmetric hybrid male sterility among Drosophila simulans, Drosophila mauritiana and Drosophila sechellia.

Haldane's rule (i.e., the preferential hybrid sterility and inviability of heterogametic sex) has been known for 70 years, but its genetic basis, which is crucial to the understanding of the process of species formation, remains unclear. In the present study, we have investigated the genetic basis of hybrid male sterility using Drosophila simulans, Drosophila mauritiana and Drosophila sechellia. An introgression of D. sechellia Y chromosome into a fairly homogenous background of D. simulans did not show any effect of the introgressed Y on male sterility. The substitution of D. simulans Y chromosome into D. sechellia, and both reciprocal Y chromosome substitutions between D. simulans and D. mauritiana were unsuccessful. Introgressions of cytoplasm between D. simulans and D. mauritiana (or D. sechellia) also did not have any effect on hybrid male sterility. These results rule out the X-Y interaction hypothesis as a general explanation of Haldane's rule in this species group and indicate an involvement of an X-autosome interaction. Models of symmetrical and asymmetrical X-autosome interaction have been developed which explain the Y chromosome substitution results and suggest that evolution of interactions between different genetic elements in the early stages of speciation is more likely to be of an asymmetrical nature. The model of asymmetrical X-autosome interaction also predicts that different sets of interacting genes may be involved in different pairs of related species and can account for the observation that hybrid male sterility in many partially isolated species is often nonreciprocal or unidirectional.