Genome-wide analysis of the Chinese sturgeon sox gene family: identification,characterisation and expression profiles of different tissues

The sox family is assumed to be responsible for a number of developmental systems. Genome sequencing technology makes it possible to scan sox genes and conduct characteristic analyses of different species. In fish, full characterisation of sox genes at the genome-wide level has been reported for pufferfish Takifugu rubripes, medaka Oryzias latipes, tilapia Oreochromis niloticus and channel catfish Ictalurus punctatus. However, no systematic investigation of the sox family in sturgeons (Acipenseridae) has been reported to date. This study conducted genome-wide identification of the sox genes in the Chinese sturgeon Acipenser sinensis and profiled their tissue distribution between male and female individuals. In total, 19 sox genes were identified, including soxb1, b2, c, d, e, f and h, in the Chinese sturgeon. Genomic structure analysis indicated relatively conserved exon–intron structures in each sox group and phylogenetic analysis supported the previous classification of the sox family. Most of the sox genes showed a tissue-specific expression pattern, indicating the possible involvement of Chinese sturgeon sox genes at different developmental processes such as cardiac and gonadal development. This study provides a comprehensive resource of Chinese sturgeon sox genes and enables a better understanding of the evolution and function of the sox family.     

Modeling Calcium Wave Based on Anomalous Subdiffusion of Calcium Sparks in Cardiac Myocytes

sparks and waves play important roles in calcium release and calcium propagation during the excitation-contraction (EC) coupling process in cardiac myocytes. Although the classical Fick’s law is widely used to model sparks and waves in cardiac myocytes, it fails to reasonably explain the full-width at half maximum(FWHM) paradox. However, the anomalous subdiffusion model successfully reproduces sparks of experimental results. In this paper, in the light of anomalous subdiffusion of sparks, we develop a mathematical model of calcium wave in cardiac myocytes by using stochastic release of release units (CRUs). Our model successfully reproduces calcium waves with physiological parameters. The results reveal how concentration waves propagate from an initial firing of one CRU at a corner or in the middle of considered region, answer how large in magnitude of an anomalous spark can induce a wave. With physiological currents (2pA) through CRUs, it is shown that an initial firing of four adjacent CRUs can form a wave. Furthermore, the phenomenon of calcium waves collision is also investigated.     

梨不同DNA提取方法的效果研究

以7个梨品种为实验材料,比较分析了SDS法、CTAB法、SDSCTAB法、改良的CTAB法、高盐低pH值法、分步离心法对梨总DNA提取的效果。结果表明:利用以上6种方法提取的梨总DNA在纯度和量上有很大的差别。所得到的平均DNA量从大到小依次为:分步离心法、SDS法、SDSCTAB法、改良的CTAB法、CTAB法、高盐低pH值法。DNA提取纯度依次为分步离心法、SDSCTAB法、改良的CTAB法、高盐低pH值法、CTAB法、SDS法。RAPD和自交不亲和基因(S基因)特异性引物扩增实验结果都比较理想,但分步离心法和SDSCTAB法提取的DNA双酶切效果较好。分步离心法提取的梨总DNA更适用于后续的分子生物学实验操作。     

Homo- and hetero-dimerization of LPA/S1P receptors, OGR1 and GPR4

G protein coupled receptors (GPCRs) form homo- and hetero-dimers or -oligomers, which are functionally important. Lysophosphatidic acid (LPA) and sphingosine-1-phosphate (S1P) are bioactive lysophopholipids involved in diverse biological processes. We have examined homo- and hetero-dimerization among three major LPA receptors (LPA(1-3)), three major S1P receptors (S1P(1-3)), as well as OGR1 and GPR4. Using LacZ complementation assays, we have shown that LPA receptors form homo- and hetero-dimers within the LPA receptor subgroup and hetero-dimers with other receptors (S1P(1-3) and GPR4). In addition, we have found that although GPR4 and OGR1 share more than 50% homology, GPR4 forms strong homo- and hetero-dimers with LPA and S1P receptors, but OGR1 forms very weak homo-dimer and relatively weak hetero-dimers with other receptors. Using chimeric receptors between GPR4 and OGR1, we have shown that different domains of GPR4 receptor are involved in its dimerization with different GPCRs and more than one domain may be involved in some of the complex formation. Our results suggest that when studying a signal transduction induced by a stimulus, not only is the expression and activation of its own receptor(s), but also the status of the interacting receptors should be taken into consideration.     

Multispecies coexistence of trees in tropical forests: spatial signals of topographic niche differentiation increase with environmental heterogeneity

Neutral and niche theories give contrasting explanations for the maintenance of tropical tree species diversity. Both have some empirical support, but methods to disentangle their effects have not yet been developed. We applied a statistical measure of spatial structure to data from 14 large tropical forest plots to test a prediction of niche theory that is incompatible with neutral theory: that species in heterogeneous environments should separate out in space according to their niche preferences. We chose plots across a range of topographic heterogeneity, and tested whether pairwise spatial associations among species were more variable in more heterogeneous sites. We found strong support for this prediction, based on a strong positive relationship between variance in the spatial structure of species pairs and topographic heterogeneity across sites. We interpret this pattern as evidence of pervasive niche differentiation, which increases in importance with increasing environmental heterogeneity.