Morphological and molecular evidence for natural hybridization between Sorbus pohuashanensis and S. discolor (Rosaceae)

In overlapping distribution areas of Sorbus pohuashanensis and S.discolor in North China(Mount Tuoliang,Mount Xiling and Mount Baihua),Sorbus indi-viduals were found with pink fruit,which have never been recorded for the flora of China.Fourteen morphological characters combined with four chloroplast DNA markers and internal transcribed spacer(ITS)were used to analyze the origin of the Sorbus individuals with pink fruits and their relationship to S.pohuashanensis and S.discolor.PCA,SDA and one-way(taxon)ANOVA of morphological characters provided convincing evidence of the hybrid ori-gin of Sorbus individuals with pink fruits based on a novel morphological character and many intermediate characters.Haplotype analysis based on four cpDNA markers showed that either S.pohuashanensis or S.discolor were maternal parents of Sorbus individuals with pink fruits.Incongru-ence of the position of Sorbus individuals with pink fruits between cpDNA and ITS in cluster trees supported by DNA sequence comparative analysis,implying former hybridiza-tion events between S.pohuashanensis and S.discolor.Mul-tiple hybridization events between S.pohuashanensis and S.discolor might have contributed to the generation of Sorbus individuals with pink fruits.This study has provided insights into hybridization between species of the same genus in sympatric areas,which is of great significance for the study of interspecific hybridization.

Identification of Kalidium species(Chenopodiaceae)by DNA barcoding

DNA barcoding is an increasingly prevalent molecular biological technology which uses a short and conserved DNA fragment to facilitate rapid and accurate species identification. Kalidium species are distributed in saline soil habitat throughout Southeast Europe and Northwest Asia, and used mainly as forage grass in China. The discrimination of Ka-lidium species was based only on morphology-based identification systems and limited to recognized species. Here, we tested four DNA candidate loci, one nuclear locus （ITS, internal transcribed spacer） and three plastid loci （rbcL9 matK and ycflb）, to select potential DNA barcodes for identifying different Kalidium species. Results showed that the best DNA barcode was ITS locus, which displayed the highest species discrimination rate （100%）, followed by matK （33.3%）,ycflb （16.7%）, and rbcL （16.7%）. Meanwhile, four loci clearly identified the variant species, Kalidium cuspidatum （Ung.-Stemb.） Gmb.var.A. J. Li,as a single species in Kalidium.

Expression analysis of a Na^+/H^+ antiporter gene PeNHX1 from Populus euphratica

Na+/H+ antiporters play an important role in the salt tolerance of a wide variety of plants.Using the rapid amplification of cDNA ends method,a Na+/H+ antiporter gene (PeNHX1) was isolated from Populus euphratica.The deduced amino acid sequence contained 528 amino acid residues with a conserved amiloride-binding domain (77LFFIYLLPPI86) and shared more than 68% identity with that of AtNHX1 from Arabidopsis thaliana.PeNHX1 can confer resistance to Na+,as well as Li+,to (EP432) an Escherichia coli strain deficient in both nhaA and nhaB,thus proving that it is a functional Na+/H+ antiporter.PeNHX1 expression profile in EP432 reflected pH independent manner.PeNHX1 expression was regulated by salt at the transcriptional level.Meanwhile,results demonstrated that transcripts of PeNHX1 in P.euphratica calli showed a salt dependent response,and thus provide a valuable tool for studying signaling and biochemical pathways involved in salt recognition and response in P.euphratica.

Research on history of Chinese seismology

The history of Chinese seismology can be traced back to four thousand years before and divided into four stages,i.e.,primitive knowledge,worship of nature,perceptual knowledge and scientific research.The second stage ran in the whole Qin-Han dynasties,and the fourth stage began from Emperor Kangxi in Qing Dynasty and continued to the present.So far China has made four great contributions to seismological development of the world,i.e.,the invention of Heng Zhang＇s seismoscope,great amount of historical records of earthquakes of four thousand years,most abundant anomaly data before earthquakes,and successful practice of earthquake prediction in Haicheng.However,the seismological research in China at present is still on the junior and developing stage.Now we have been carrying on some recessively historical load in our mind such as the subconsciousness of absolute obedience,habit of phenomenological study as well as the methods of philosophical analysis without sincerity.For constructing a high-level Chinese culture in seismological research,we need to pay attention to combining the phenomenological research with experiment,observation and theory study.It is also suggested to take the appropriated measures matched with the present research level in seismology,as well as to promote coexisting and merging of multi-cultures.

Machine Learning(ML)-Assisted Design and Fabrication for Solar Cells

Photovoltaic (PV) technologies have attracted great interest due to their capability of generating electricity directly from sunlight. Machine learning(ML) is a technique for computer to learn how to perform a specific task using known data. It can be used in many areas and has become a hot research topic recently due to the rapid accumulation of data and advancement of computer hardware. The application of ML techniques in the design and fabrication of solar cells started slowly but has recently gained tremendous momentum. An exhaustive compilation of the literatures indicates that all the major aspects in the research and development of solar cells can be effectively assisted by ML techniques. If combined with other tools and fed with additional theoretical and experimental data, more accurate and robust results can be achieved from ML techniques. The aspects can be grouped into four categories:prediction of material properties,optimization of device structures, optimization of fabrication processes, and reconstruction of measurement data. A statistical analysis of the literatures shows that artificial neural network (ANN) and genetic algorithm (GA) are the two most applied ML techniques and the topics in the optimization of device structures and optimization of fabrication processes are more popular.This article can be used as a reference by all PV researchers who are interested in ML techniques.

Differential expression of PeSOS1, PeNhaD1 and PeNHX1 genes between the salt-tolerant Populus euphratica and salt-sensitive P. hopeiensis calli

Populus euphratica Oliv. is of high salinity tolerance and used as a model species for investigating molecular mechanisms of trees＇ responses to salt stress. In the work presented here we found that calli of P. euphratica grew more rapidly and accumulated less Na＋, but more K＋, under salt stress than those of salt-sensitive poplar, Populus hopeiensis. Different types of Na＋/H＋ antiporters （SOS1, NhaD1 and NHX1） were isolated from P. euphratica; all of these genes have been shown to play important roles in plant salt tolerance mechanism in previous studies. Expression profiles of these three genes were compared between P. hopeiensis and P. euphratica in the presence and absence of salt stress by real-time PCR. The three genes were induced in both P. euphratica and P. hopeiensis by salt. Transcript levels of PeNHX1 were lower in P. euphratica than in P. hopeiensis under 150 mM NaCl stress. In addition, transcript levels of PeNhaD1 were lower, while PeSOS1 were higher in P. euphratica than in P. hopeiensis under both stressed and unstressed conditions. The results indicated that P. euphratica up-regulates different genes and consistently maintains both effluxes of Na＋ and high K＋ levels. Our data suggests that differences in gene expression patterns may contribute to the dif-ference in salt tolerance between these two poplars.

Effect of salt stress on the expression of NHX-type Na^+/H^+ antiporters in Populus euphratica and P.pruinosa calli

Populus euphratica and Populuspruinosa, sister species in the Turanga Section （Salicaceae）, growing in semi-arid saline areas are known for their high salinity tolerance. In this study, by combining growth level with Na＋ and K＋ contents, the expression level of vacuolar Na＋/H＋ antiporters was investigated for NaCl-induced changes in P. euphratica and t3. pru- inosa calli. Compared to R euphratica, P. pruinosa calli grew well in 200 mM NaC1 stress from 14. to 21 days. Increasing the stressed time caused an increase in Na＋ content concomitant with a decrease in K＋ content in P. euphratica calli, whereas, with the presence of 200 mM NaCI, K＋ content has a less increase in 14 and 21 days than in 7 days which was detected in R pruinosa calli. The transcript levels of six genes coding for NHX-type Na＋/H＋ antiporters suggest that vacuolar NHX1-NHX6 antiporters play important roles in responding to salt stress in R pruinosa. Our data suggest that there exists a higher salt tolerance for P. pruinosa than P. euphratica at the cellular level, Na＋ avoidance or accumulation is observed in cellular compartments, and that expression of NHX antiporters is linked to the accumulator phenotype.

Dysregulated Hepatic Expression of Glucose Transporter Type-1,Toll-Like Receptor 4,and Nuclear Factor Kappa B in Estrogen-Induced Cholestasis Pregnant Rats with Placental Ischemia-Reperfusion Stress

Objective:This study aimed at investigating the expression of nuclear factor kappa B(NF-κB)and mammalian target of rapamycin(mTOR)related signal pathways in liver tissues of intrahepatic cholestasis of pregnancy animal models.Methods:Estrogen(EE)-induced cholestasis and a placental ischemia-reperfusion(IR)model were established in pregnant rats.All pregnant rats were divided into four groups by random number table:EE-IR group(n=6),EE-sham group(n=6),control-IR group(n=6)and control-sham group(n=6).Liver expression of mTOR,its upstream regulator DNA damage response-1(REDD1),and downstream factor glucose transporter type-1(GLUT1),accompanied by NF-κB(p65 is the most important component),its activator toll-like receptor 4(TLR4),and inhibitor IκBα,were detected by western blot analysis and real-time polymerase chain reaction.The intergroup comparisons were performed with a one-way analysis of variance,the comparisons among groups were analyzed with the nonparametric Kruskal-Wallis test.Results:Giving pregnant rats EE alone reduced the hepatic expression of IκBα(0.72±0.20vs.1.01±0.07,P=0.008).Meanwhile,giving pregnant rats placental IR alone increased liver levels of REDD1(3.24±0.98vs.1.06±0.24,P=0.025),GLUT1(2.37±0.82vs.1.09±0.10,P=0.039),TLR4(2.12±0.29vs.1.20±0.28,P=0.010),and p65(2.09±0.85vs.1.04±0.06,P=0.023),and decreased hepatic mTOR(0.50±0.07vs.1.01±0.03,P=0.001)and IκBα(0.61±0.08vs.1.01±0.07,P=0.014)expression.Subjecting EE-treated rats to placental IR did not further alter liver levels of GLUT1(2.02±0.45vs.1.79±0.39,P=0.240),TLR4(2.10±0.74vs.1.60±0.36,P=0.129),or p65(2.41±0.83vs.1.65±0.46,P=0.145),whereas it did decrease hepatic mTOR(0.42±0.09vs.0.90±0.14,P=0.008)and IκBα(0.43±0.09vs.0.72±0.20,P=0.004)expression and enhance REDD1 expression(4.46±0.65vs.2.05±0.47,P=0.009).Placental IR stress did impact the hepatic expression of REDD1-mTOR-GLUT1 and TLR4/NF-κB/IκBαin pregnant rats.Conclusion:Placental IR-induced hepatic GLUT1,TLR4,and p65 alternation,which responded efficiently in control rats,were impaired in EE-induced ICP rats.