RESUMEN
Expressed subtype of paralogous genes in functionally homologous cells sometimes show differences across species, the reasons for which have not been explained. The present study examined hypophysiotropic gonadotropin-releasing hormone (GnRH) neurons in vertebrates to investigate this mechanism. These neurons express either gnrh1 or gnrh3 paralogs, depending on the species, and apparent switching of the expressed paralogs in them occurred at least four times in vertebrate evolution. First, we found redundant expression of gnrh1 and gnrh3 in a single neuron in piranha and hypothesized that it may represent an ancestral GnRH system. Moreover, the gnrh1/gnrh3 enhancer of piranha induced reporter RFP/GFP co-expression in a single hypophysiotropic GnRH neuron in both zebrafish and medaka, whose GnRH neurons only express either gnrh3 or gnrh1. Thus, we propose that redundant expression of gnrh1/3 of relatively recent common ancestors may be the key to apparent switching of the paralog usage among present-day species.
RESUMEN
We designed and synthesized unsubstituted 4,4'-bibenzo[c]thiophene 4,4'-BBT and its silyl-substituted derivatives 1,1'-Si-4,4'-BBT and 1,1',3,3'-Si-4,4'-BBT with one or two tert-butyldimethylsilyl groups on each thiophene ring, as new π-building blocks in emitters, photosensitizers and semiconductors for organic optoelectronic devices. The characterization of 4,4'-BBT, 1,1'-Si-4,4'-BBT and 1,1',3,3'-Si-4,4'-BBT was successfully determined by FTIR, 1H and 13C NMR measurements, high-resolution mass spectrometry (HRMS) analysis, photoabsorption and fluorescence spectroscopy, cyclic voltammetry (CV) and density functional theory (DFT) calculations. Moreover, a single-crystal X-ray structural analysis was successfully made for 1,1'-Si-4,4'-BBT and 1,1',3,3'-Si-4,4'-BBT. The photoabsorption and fluorescence maxima (λ abs max and λ fl max) of the three 4,4'-bibenzo[c]thiophene derivatives in toluene exhibit bathochromic shifts in the order of 4,4'-BBT (359 nm and 410 nm) < 1,1'-Si-4,4'-BBT (366 nm and 420 nm) < 1,1',3,3'-Si-4,4'-BBT (371 nm and 451 nm). The HOMO and LUMO energy levels rise in the order of 4,4'-BBT (-5.55 eV and -2.39 eV) < 1,1'-Si-4,4'-BBT (-5.45 eV and -2.34 eV) < 1,1',3,3'-Si-4,4'-BBT (-5.34 eV and -2.30 eV), but the rise of the HOMO energy level is larger than that of the LUMO energy level, resulting in the bathochromic shift of the photoabsorption band from 4,4'-BBT to 1,1',3,3'-Si-4,4'-BBT. The fluorescence quantum yields (Φ fl) of 4,4'-BBT, 1,1'-Si-4,4'-BBT and 1,1',3,3'-Si-4,4'-BBT in toluene are 0.41, 0.41 and 0.36, respectively. It is worth mentioning that in the solid state 1,1'-Si-4,4'-BBT and 1,1',3,3'-Si-4,4'-BBT show relatively high Φ fl-solid values of 0.22 and 0.25, respectively, whereas 4,4'-BBT exhibits poor solid-state fluorescence properties (Φ fl-solid < 0.02). This work provides an efficient synthetic method for the 4,4'-bibenzo[c]thiophene derivatives and their photophysical properties in the solution and solid state, electrochemical properties and X-ray crystal structures.
RESUMEN
In this study, we examined whether gene trap methodology, which would be available for systematic identification and functional analysis of genes, is effective for screening of Wnt-responsive genes during mouse development. We screened out two individual clones among 794 gene-trapped embryonic stem cell lines by their in vitro response to WNT-3A proteins. One gene was mainly expressed in the ductal epithelium of several developing organs, including the kidney and the salivary glands, and the other gene was expressed in neural crest cells and the telencephalic flexure. The spatial and temporal expression of these two genes coincided well with that of several Wnt genes. Furthermore, the expression of these two genes was significantly decreased in embryos deficient for Wnts or in cultures of embryonic tissues treated with a Wnt signal inhibitor. These results indicate that the gene trap is an effective method for systematic identification of Wnt-responsive genes during embryogenesis.
