基于FMT-AHP的海南农垦花岗岩类多雨区橡胶园地力评价

海南农垦是中国最大的天然橡胶生产基地,自第二次全国土壤普查以来橡胶园养分状况已发生了很大变化,但具体情况如何尚不清楚。运用耕地地力评价方法对海南农垦主要橡胶园的地力进行了系统评价,以期为橡胶园地力提升和天然橡胶的可持续发展提供理论支持。以土壤母质类型和降雨量为依据,首次将海南农垦橡胶园划分为8个类型区,并选取占海南农垦橡胶园总面积56.97%的花岗岩类多雨区作为评价区域,采集7204个0—20 cm层的土壤样品,运用特尔菲法、模糊数学理论和层次分析法确定11个评价指标及其权重,将评价区橡胶园地力划分为5等。研究结果发现:评价区以中间地力水平的二等、三等、四等橡胶园为主,占评价区橡胶园总面积的85.85%,它们广泛分布于琼中、屯昌、澄迈、儋州、万宁、保亭、乐东、三亚、陵水、定安、琼海、五指山、昌江、文昌和东方15个县市;一等地面积很小且分散,五等地相对集中面积也很小。相关分析表明土壤pH、有机质、有效磷和速效钾含量是影响评价区橡胶园地力水平的重要因素。评价区橡胶园土壤pH适宜橡胶树正常生长,但该区域土壤有机质和有效磷含量不能满足橡胶树正常生长的需要,而该区域一、二等地土壤速效钾含量能满足橡胶树正常生长,其三、四等地土壤速效钾含量仅达到橡胶树正常生长所需水平,随着地力下降到五等其土壤速效钾含量已不适宜橡胶树正常生长。根据上述研究结果,笔者建议橡胶园应大力间作绿肥,在增施有机质的基础上补氮、补钾、施用钙镁磷肥,同时加强养分管理,提高肥料利用率。     

植物异源多倍体进化中基因表达的变化

多倍化是植物物种进化的主要动力, 异源多倍体植物在形成早期发生着快速的基因表达变化。本文概述了异源多倍体植物中基因表达变化的特点, 包括基因的沉默、激活和部分同源基因表达水平的变化, 探讨了基因表达变化的分子机制和生物学意义, 并对研究中的问题进行了分析和展望。     

Bacterial communities of the coronal sulcus and distal urethra of adolescent males

Lactobacillus-dominated vaginal microbiotas are associated with reproductive health and STI resistance in women, whereas altered microbiotas are associated with bacterial vaginosis (BV), STI risk and poor reproductive outcomes. Putative vaginal taxa have been observed in male first-catch urine, urethral swab and coronal sulcus (CS) specimens but the significance of these observations is unclear. We used 16 S rRNA sequencing to characterize the microbiota of the CS and urine collected from 18 adolescent men over three consecutive months. CS microbiotas of most participants were more stable than their urine microbiotas and the composition of CS microbiotas were strongly influenced by circumcision. BV-associated taxa, including Atopobium, Megasphaera, Mobiluncus, Prevotella and Gemella, were detected in CS specimens from sexually experienced and inexperienced participants. In contrast, urine primarily contained taxa that were not abundant in CS specimens. Lactobacilllus and Streptococcus were major urine taxa but their abundance was inversely correlated. In contrast, Sneathia, Mycoplasma and Ureaplasma were only found in urine from sexually active participants. Thus, the CS and urine support stable and distinct bacterial communities. Finally, our results suggest that the penis and the urethra can be colonized by a variety of BV-associated taxa and that some of these colonizations result from partnered sexual activity.     

Flexible chromosome painting based on multiplex PCR of oligonucleotides and its application for comparative chromosome analyses in Cucumis

Chromosome painting is a powerful technique for chromosome and genome studies. We developed a flexible chromosome painting technique based on multiplex PCR of a synthetic oligonucleotide (oligo) library in cucumber (Cucumis sativus L., 2n = 14). Each oligo in the library was associated with a universal as well as nested specific primers for amplification, which allow the generation of different probes from the same oligo library. We were also able to generate double‐stranded labelled oligos, which produced much stronger signals than single‐stranded labelled oligos, by amplification using fluorophore‐conjugated primer pairs. Oligos covering cucumber chromosome 1 (Chr1) and chromosome 4 (Chr4) consisting of eight segments were synthesized in one library. Different oligo probes generated from the library painted the corresponding chromosomes/segments unambiguously, especially on pachytene chromosomes. This technique was then applied to study the homoeologous relationships among cucumber, C. hystrix and C. melo chromosomes based on cross‐species chromosome painting using Chr4 probes. We demonstrated that the probe was feasible to detect interspecies chromosome homoeologous relationships and chromosomal rearrangement events. Based on its advantages and great convenience, we anticipate that this flexible oligo‐painting technique has great potential for the studies of the structure, organization, and evolution of chromosomes in any species with a sequenced genome.     

Migration-stimulating factor (MSF) is over-expressed in non-small cell lung cancer and promotes cell migration and invasion in A549 cells over-expressing MSF

Migration-stimulating factor (MSF), an oncofetal truncated isoform of fibronectin, is a potent stimulator of cell invasion. However, its distribution and motogenic role in non-small cell lung cancer (NSCLC) have never been identified. In this study, real-time PCR and immunohistochemical staining (IHC) were performed to detect MSF mRNA and protein levels in tumor tissues and matched adjacent tumor-free tissues. Furthermore, to examine the effect of MSF on invasiveness, MSF was upregulated in A549 cells. The invasiveness and viability of A549 cells were then determined using a transwell migration assay and the 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) viability assays, respectively. The expression level of MSF in NSCLC tissue was markedly higher than in matched adjacent tumor-free tissue. Additionally, the level of MSF protein expression in stage III and IV NSCLC samples was higher than in stage I and II NSCLC samples. More importantly, we also demonstrated that migration and invasion of A549 cells increased substantially after upregulating MSF, although proliferation remained unchanged. Meanwhile, we found no correlation between increasing motility and invasiveness of MSF-overexpressing cells and expression levels and activities of matrix metalloprotease MMP-2 and MMP-9. Our current study shows that MSF plays a role in migration and invasion of A549 cells and suggests that MSF may be a potential biomarker of NSCLC progression.     

A leaf shape mutant provides insight into PINOID Serine/Threonine Kinase function in cucumber(Cucumis sativus L.)

Optimizing leaf shape is a major challenge in efforts to develop an ideal plant type. Cucumber leaf shapes are diverse; however, the molecular regulatory mechanisms underlying leaf shape formation are unknown. In this study, we obtained a round leaf mutant(rl) from an ethyl methanesulfonate-induced mutagenesis population. Genetic analysis revealed that a single recessive gene, rl, is responsible for this mutation. A modified Mut Map analysis combined linkage mapping identified a single nucleotide polymorphism within a candidate gene,Csa1 M537400, as the mutation underlying the trait.Csa1 M537400 encodes a PINOID kinase protein involved in auxin transport. Expression of Csa1 M537400 was significantly lower in the rl mutant than in wild type, and it displayed higher levels of IAA(indole-3-acetic acid) in several tissues. Treatment of wild-type plants with an auxin transport inhibitor induced the formation of round leaves,similar to those in the rl mutant. Altered expression patterns of several auxin-related genes in the rl mutant suggest that rl plays a key role in auxin biosynthesis,transport, and response in cucumber. These findings provide insight into the molecular mechanism underlying the regulation of auxin signaling pathways in cucumber,and will be valuable in the development of an ideal plant type.     

Candidate genes underlying the quantitative trait loci for root-knot nematode resistance in a Cucumis hystrix introgression line of cucumber based on population sequencing

The southern root-knot nematode (RKN), Meloidogyne incognita (Kofoid & White) Chitwood, is one of most destructive species of plant parasitic nematodes, causing significant economic losses to numerous crops including cucumber (Cucumis sativus L. 2n = 14). No commercial cultivar is currently available with resistance to RKN, severely hindering the genetic improvement of RKN resistance in cucumber. An introgression line, IL10-1, derived from the interspecific hybridization between the wild species Cucumis hystrix Chakr. (2n = 24, HH) and cucumber, was identified with resistance to RKN. In this study, an ultrahigh-density genetic linkage bin-map, composed of high-quality single-nucleotide polymorphisms (SNPs), was constructed based on low-coverage sequences of the F_2:6 recombinant inbred lines derived from the cross between inbred line IL10-1 and cultivar ‘Beijingjietou’ CC3 (hereinafter referred to as CC3). Three QTLs were identified accounting for 13.36% (qRKN1-1), 9.07% and 9.58% (qRKN5-1 and qRKN5-2) of the resistance variation, respectively. Finally, four genes with nonsynonymous SNPs from chromosome 5 were speculated to be the candidate RKN-resistant related genes, with annotation involved in disease resistance. Though several gaps still exist on the bin-map, our results could potentially be used in breeding programs and establish an understanding of the associated mechanisms underlying RKN resistance in cucumber.

     

Similarities and seasonal variations in bacterial communities from the blood of rodents and from their flea vectors

Vector-borne microbes are subject to the ecological constraints of two distinct microenvironments: that in the arthropod vector and that in the blood of its vertebrate host. Because the structure of bacterial communities in these two microenvironments may substantially affect the abundance of vector-borne microbes, it is important to understand the relationship between bacterial communities in both microenvironments and the determinants that shape them. We used pyrosequencing analyses to compare the structure of bacterial communities in Synosternus cleopatrae fleas and in the blood of their Gerbillus andersoni hosts. We also monitored the interindividual and seasonal variability in these bacterial communities by sampling the same individual wild rodents during the spring and again during the summer. We show that the bacterial communities in each sample type (blood, female flea or male flea) had a similar phylotype composition among host individuals, but exhibited seasonal variability that was not directly associated with host characteristics. The structure of bacterial communities in male fleas and in the blood of their rodent hosts was remarkably similar and was dominated by flea-borne Bartonella and Mycoplasma phylotypes. A lower abundance of flea-borne bacteria and the presence of Wolbachia phylotypes distinguished bacterial communities in female fleas from those in male fleas and in rodent blood. These results suggest that the overall abundance of a certain vector-borne microbe is more likely to be determined by the abundance of endosymbiotic bacteria in the vector, abundance of other vector-borne microbes co-occurring in the vector and in the host blood and by seasonal changes, than by host characteristics.