川西盆周丘陵地区油菜作物生态效应的初步探讨

名山县位于东经103°08′,北纬30°06′,是四川省商品粮油基地县之一,属川西盆周丘陵地区。年平均气温15.5℃,日照1052.0小时,降雨量1519.9mm,一年两熟,能满足油菜全生育期的需要。全县油菜发展较快,1989年较1983年种植面积扩大了33.91%,达到6000ha;总产增加30.35%,达到5958.1t。     

The Genetic Structure and Evolutionary Fate of Parthenogenetic Amphibian Populations as Determined by Markovian Analysis

SYNOPSIS. One-locus, two-allele models are presented which describethe genetic consequences of naturally occurring andexperimentallyinduced parthenogesis in triploid and diploid amphibians. Themodels may in general be used to investigate genetic changeresulting from apomictic (ameiotic) and automictic (meiotic)parthenogenetic reproduction. These models quantify the influence of mutation, segregation,and selection upon genetic variability in parthenogeneticpopulations.They also allow an estimate of the relative importance of stochasticforces in altering this variability. They thus provide a basisfor understanding evolution in these populations. Some of the conclusions derived from this study contradict previouspredictions regarding genetic variability in parthenogeneticpopulations. First, if mutation is the sole source of geneticchange (i.e., strict apomixis), parthenogenetic populationsshould not become completely heterozygous. Second, small amountsof segregation occurring in apomictic populations have enormouseffects upon the genetic variability of these populations, i.e.,they should lose much of their heterozygosity. In addition to these conclusions, the results of this studysuggest that studies of protein variability in parthenogeneticspecies should contribute toward answering the question: Howmuch of the genetic variability observed in nature is evolutionarilyrelevant?     

Dating of graptolite zones by sedimentation rates: implications for rates of evolution

Preliminary determinations of ancient pelagic sedimentation rates agree with modern rates at about 4 meters per million years. By combining data on the thickness of graptolite zones from the North American Cordillera with data from other parts of the world, we have refined the Early Silurian time scale and obtained much better resolution than is possible for radiometric dates. The new Early Silurian time scale allows estimation of true rates of change in graptolite diversity. The Llandoverian diversity explosion is twice as rapid as was previously thought. The brevity of diversity lows and rapidity of speciation support modern theories of quantum evolution.     

Kinase–substrate Edge Biomarkers Provide A More Accurate Prognostic Prediction in ER-negative Breast Cancer

The estrogen receptor (ER)-negative breast cancer subtype is aggressive with few treatment options available. To identify specific prognostic factors for ER-negative breast cancer, this study included 705,729 and 1034 breast invasive cancer patients from the Surveillance, Epidemiology, and End Results (SEER) and The Cancer Genome Atlas (TCGA) databases, respectively. To identify key differential kinase–substrate node and edge biomarkers between ER-negative and ER-positive breast cancer patients, we adopted a network-based method using correlation coefficients between molecular pairs in the kinase regulatory network. Integrated analysis of the clinical and molecular data revealed the significant prognostic power of kinase–substrate node and edge features for both subtypes of breast cancer. Two promising kinase–substrate edge features, CSNK1A1–NFATC3 and SRC–OCLN, were identified for more accurate prognostic prediction in ER-negative breast cancer patients.     

Comparative Genome Analysis of Scutellaria baicalensis and Scutellaria barbata Reveals the Evolution of Active Flavonoid Biosynthesis

Scutellaria baicalensis (S. baicalensis) and Scutellaria barbata (S. barbata) are common medicinal plants of the Lamiaceae family. Both produce specific flavonoid compounds, including baicalein, scutellarein, norwogonin, and wogonin, as well as their glycosides, which exhibit antioxidant and antitumor activities. Here, we report chromosome-level genome assemblies of S. baicalensis and S. barbata with quantitative chromosomal variation (2n = 18 and 2n = 26, respectively). The divergence of S. baicalensis and S. barbata occurred far earlier than previously reported, and a whole-genome duplication (WGD) event was identified. The insertion of long terminal repeat elements after speciation might be responsible for the observed chromosomal expansion and rearrangement. Comparative genome analysis of the congeneric species revealed the species-specific evolution of chrysin and apigenin biosynthetic genes, such as the S. baicalensis-specific tandem duplication of genes encoding phenylalanine ammonia lyase and chalcone synthase, and the S. barbata-specific duplication of genes encoding 4-CoA ligase. In addition, the paralogous duplication, colinearity, and expression diversity of CYP82D subfamily members revealed the functional divergence of genes encoding flavone hydroxylase between S. baicalensis and S. barbata. Analyzing these Scutellaria genomes reveals the common and species-specific evolution of flavone biosynthetic genes. Thus, these findings would facilitate the development of molecular breeding and studies of biosynthesis and regulation of bioactive compounds.     

Natural variation in the promoter of OsHMA3 contributes to differential grain cadmium accumulation between Indica and Japonica rice

Rice is a major source of cadmium(Cd) intake for Asian people. Indica rice usually accumulates more Cd in shoots and grains than Japonica rice. However, underlying genetic bases for differential Cd accumulation between Indica and Japonica rice are still unknown. In this study, we cloned a quantitative trait locus(QTL) grain Cd concentration on chromosome 7(GCC7) responsible for differential grain Cd accumulation between two rice varieties by performing QTL analysis and map-based cloning. We found that the two GCC7 alleles, GCC7~(PA64s) and GCC7~(93-11), had different promoter activity of OsHMA3,leading to different OsHMA3 expression and different shoot and grain Cd concentrations. By analyzing the distribution of different haplotypes of GCC7 among diverse rice accessions, we discovered that the high and low Cd accumulation alleles, namely GCC7~(93-11) and GCC7~(PA64s), were preferentially distributed in Indica and Japonica rice,respectively. We further showed that the GCC7~(PA64s)allele can be used to replace the GCC7~(93-11) allele in the super cultivar 93-11 to reduce grain Cd concentration without adverse effect on agronomic traits. Our results thus reveal that the QTL GCC7 with sequence variation in the OsHMA3 promoter is an important determinant controlling differential grain Cd accumulation between Indica and Japonica rice.     

microRNA‐124 inhibits stem‐like properties and enhances radiosensitivity in nasopharyngeal carcinoma cells via direct repression of expression of JAMA

Cancer stem cells (CSCs) are a source of tumour recurrence in patients with nasopharyngeal carcinoma (NPC); however, the function of microRNA‐124 (miR‐124) in NPC CSCs has not been clearly defined. In this study, we investigated the role of miR‐124 in NPC CSCs. qRT‐PCR was performed to measure miR‐124 expression in NPC tissues and cell lines and the effects of miR‐124 on stem‐like properties and radiosensitivity of NPC cells measured. Luciferase reporter assays and rescue experiments were used to investigate the interaction of miR‐124 with the 3′UTR of junctional adhesion molecule A (JAMA). Finally, we examined the effects of miR‐124 in an animal model and clinical samples. Down‐regulation of miR‐124 was detected in cancer tissues and was inversely associated with tumour stage and lymph node metastasis. Overexpression of miR‐124 inhibited stemness properties and enhanced radiosensitivity of NPC cells in vitro and in vivo via targeting JAMA. Up‐regulation of miR‐124 was correlated with superior overall survival of patients with NPC. Our study demonstrates that miR‐124 can inhibit stem‐like properties and enhance radiosensitivity by directly targeting JAMA in NPC. These findings provide novel insights into the molecular mechanisms underlying therapy failure in NPC.