Genomic anatomy of male-specific microchromosomes in a gynogenetic fish.

Unisexual taxa are commonly considered short-lived as the absence of meiotic recombination is supposed to accumulate deleterious mutations and hinder the creation of genetic diversity. However, the gynogenetic gibel carp (Carassius gibelio) with high genetic diversity and wide ecological distribution has outlived its predicted extinction time of a strict unisexual reproduction population. Unlike other unisexual vertebrates, males associated with supernumerary microchromosomes have been observed in gibel carp, which provides a unique system to explore the rationales underlying male occurrence in unisexual lineage and evolution of unisexual reproduction. Here, we identified a massively expanded satellite DNA cluster on microchromosomes of hexaploid gibel carp via comparing with the ancestral tetraploid crucian carp (Carassius auratus). Based on the satellite cluster, we developed a method for single chromosomal fluorescence microdissection and isolated three male-specific microchromosomes in a male metaphase cell. Genomic anatomy revealed that these male-specific microchromosomes contained homologous sequences of autosomes and abundant repetitive elements. Significantly, several potential male-specific genes with transcriptional activity were identified, among which four and five genes displayed male-specific and male-biased expression in gonads, respectively, during the developmental period of sex determination. Therefore, the male-specific microchromosomes resembling common features of sex chromosomes may be the main driving force for male occurrence in gynogenetic gibel carp, which sheds new light on the evolution of unisexual reproduction.

EGFR Inhibition Overcomes Resistance to FGFR4 Inhibition and Potentiates FGFR4 Inhibitor Therapy in Hepatocellular Carcinoma.

Aberrant activation of the FGF19-FGFR4 signaling pathway plays an essential role in the tumorigenesis of hepatocellular carcinoma (HCC). As such, FGFR4 inhibition has emerged as a novel therapeutic option for the treatment of HCC and has shown preliminary efficacy in recent clinical trials for patients exhibiting aberrant FGF19 expression. Resistance to kinase inhibitors is common in oncology, presenting a major challenge in the clinical treatment process. Hence, we investigated the potential mechanisms mediating and causing resistance to FGFR4 inhibition in HCC. Upon the successful establishment of a battery of cellular models developing resistance to FGFR4 inhibitors, we have identified the activation of EGFR, MAPK, and AKT signaling as the primary mechanisms mediating the acquired resistance. Combination of inhibitors against EGFR or its downstream components restored sensitivity to FGFR4 inhibitors. In parental HCC cell lines, EGF treatment also resulted in resistance to FGFR4 inhibitors. This resistance was effectively reverted by inhibitors of the EGFR signaling pathway, suggesting that EGFR activation is a potential cause of intrinsic resistance. We further confirmed the above findings in vivo in mouse xenograft tumor models. Genomic analysis of patient samples from The Cancer Genome Atlas confirmed that a segment of patients with HCC harboring FGF19 overexpression indeed exhibited increased activation of EGFR signaling. These findings conclusively indicate that both induced and innate activation of EGFR could mediate resistance to FGFR4 inhibition, suggesting that dual blockade of EGFR and FGFR4 may be a promising future therapeutic strategy for the treatment of FGF19-FGFR4 altered HCC.

Extraction capacity of diglycolamide derivatives for Ca(II), Nd(III) and Zr(IV) from nitric acid to N-dodecane containing a solvent modifier.

In order to evaluate the extraction property of new extractants, diglycolamide (DGA) compounds, we investigated the maximum extraction of di-, tri-, and tetravalent metal ions using nitric acid and n-dodecane. The limits of metal concentration (LOC) for Ca(II), Nd(III) and Zr(IV) in the organic phase are strongly influenced by HNO3 and the extractant concentration. For the purpose of enhancing the LOC value, we employed a modifier of the solvent, N,N-dihexyl-octanamide (DHOA) and DGA with a long alkyl chain, and examined the results. It was evident that LOC increased with the DHOA concentration and the length of the alkyl chain attached to the N atom of DGA. The stoichiometric values of LOC(Zr) estimated from the extraction reaction were confirmed by using the extraction condition: tetraoctyl-DGA/1 M DHOA + n-dodecane and 3 M HNO3.