Transmembrane kinase 1-mediated auxin signal regulates membrane-associated clathrin in Arabidopsis roots

Clathrin-mediated endocytosis (CME) is the major endocytic pathway in eukaryotic cells that directly regulates abundance of plasma membrane proteins. Clathrin triskelia are composed of clathrin heavy chains (CHCs) and light chains (CLCs), and the phytohormone auxin differentially regulates membrane-associated CLCs and CHCs, modulating the endocytosis and therefore the distribution of auxin efflux transporter PIN-FORMED2 (PIN2). However, the molecular mechanisms by which auxin regulates clathrin are still poorly understood. Transmembrane kinase (TMKs) family proteins are considered to contribute to auxin signaling and plant development; it remains unclear whether they are involved in PIN transport by CME. We assessed TMKs involvement in the regulation of clathrin by auxin, using genetic, pharmacological, and cytological approaches including live-cell imaging and immunofluorescence. In tmk1 mutant seedlings, auxin failed to rapidly regulate abundance of both CHC and CLC and to inhibit PIN2 endocytosis, leading to an impaired asymmetric distribution of PIN2 and therefore auxin. Furthermore, TMK3 and TMK4 were shown not to be involved in regulation of clathrin by auxin. In summary, TMK1 is essential for auxin-regulated clathrin recruitment and CME. TMK1 therefore plays a critical role in the establishment of an asymmetric distribution of PIN2 and an auxin gradient during root gravitropism.     

Universal two-dimensional labelled probe-mediated melting curve analysis based on multiplex PCR for rapid typing of Plasmodium in a single closed tube

Currently, malaria is still one of the major public health problems commonly caused by the four Plasmodium species. The similar symptoms of malaria and the COVID-19 epidemic of fever or fatigue lead to frequent misdiagnosis. The disadvantages of existing detection methods, such as time-consuming, costly, complicated operation, need for experienced technicians, and indistinguishable typing, lead to difficulties in meeting the clinical requirements of rapid, easy, and accurate typing of common Plasmodium species. In this study, we developed and optimized a universal two-dimensional labelled probe-mediated melting curve analysis (UP-MCA) assay based on multiplex and asymmetric PCR for rapid and accurate typing of five Plasmodium species, including novel human Plasmodium, Plasmodium knowlesi (Pk), in a single closed tube following genome extraction. The assay showed a limit of detection (LOD) of 10 copies per reaction and could accurately distinguish Plasmodium species from intra-plasmodium and other pathogens. Additionally, we proposed and validated different methods of fluorescence quenching and tag design for probes that are suitable for UP-MCA assays. Moreover, the clinical performance of the Plasmodium UP-MCA assay using a base-quenched universal probe was evaluated using 226 samples and showed a sensitivity of 100% (164/164) and specificity of 100% (62/62) at a 99% confidence interval, with the microscopy method as the gold standard. In summary, the UP-MCA assay showed excellent sensitivity, specificity, and accuracy for genotyping Plasmodium species spp. Additionally, it facilitates convenient and rapid Plasmodium detection in routine clinical practice and has great potential for clinical translation.     

Genomic analyses reveal natural selection on reproduction related genes between two closely related Populus (Salicaceae) species

Identifying the factors that cause reproductive isolation and their relative importance in species divergence is crucial to our understanding of speciation processes. In most species, natural selection is commonly considered to play a large role in driving speciation. Based on whole genome re-sequencing data from 27 Populus alba and 28 Populus adenopoda individuals, we explored the factors related to reproductive isolation of these two closely related species. The results showed that the two species diverged ~5–10 million years ago (Ma), when the Qinghai–Tibet Plateau reached a certain height and the inland climate of the Asian continent became arid. In highly differentiated genomic regions, the relative divergence (F_ST) and absolute divergence (d_xy) were significantly higher than the genomic background, θπ and shared polymorphisms decreased whereas fixed differences increased, which indicated that natural selection played a key role in the reproductive isolation of the two species. In addition, we found several genes that were related to reproduction that may be involved in explaining the reproductive isolation. Using phylogenetic trees resolved from haplotype data of Populus tomentosa and P. adenopoda, the maternal origin of P. tomentosa from P. adenopoda was likely to be located in Hubei and Chongqing Provinces.     

Nature and metabolism of a thymus cyst studied by histochemistry and autoradiography

Summary A thymus cyst was discovered in connection with autoradiographical studies on sulphur metabolism of the rat. The coincidence must be considered unique and has motivated amplifying histochemical investigations.The cyst-content showed a strong positive PAS-reaction and after toluidine blue -metachromasia, which along with the incorporation of S³⁵ makes the presence of acid mucopolysaccharides likely. A strong blackening was noticed on the autoradiogram over the greater part of the cyst. This infers that the content has been metabolized here, in contradistinction to the centre with inactive colloid.     

SEQUENCES OF LLANDOVERIAN CHITINOZOANS IN YANGZl REGION

This paper is dedicated as a token of homage and gratitude to Prof. Mu. En-zhi, the nestor in the field of graptolite studies, who introduced us chitinozoan studies with constant supports in many ways, and who died on 8th April, 1987. The Palaeontological Society of China has decided to publish a specieal volume in memory of this outstanding scientist.     

Clonal organization of populations of Asarum europaeum and Maianthemum bifolium in contrasting woodland habitats

Populations of two rhizomatous species, Asarum europaeum (asarabacca) and Maianthemum bifolium (May lily), were examined in two, and four forest habitats respectively, in the Roztocze National Park (south-eastern Poland). May lily populations were studied in habitats: the Carpathian beechwood, upland mixed fir forest, subboreal moist mixed coniferous forest and bog-alder forest. Asarabacca was studied in two habitats: beechwood and Scots pine community (an 80-year-old plantation). In both the species studied intra- and inter-populational differences of the size of genets in terms of above- and below-ground parts of individuals as well as the biomass and area occupied were observed. In May lily populations the greatest mean number of shoots per genet was found in the fir forest (11.62±3.29), a value almost twice as great as that in the moist coniferous forest and nearly three times greater than in the bog-alder forest. Total rhizome length was also the greatest in the fir forest (351.9±98.7 cm) followed by moist coniferous forest, beechwood and alder forest habitats. In all populations of May lily a greater part of total dry weight biomass is in below-ground organs. The greatest biomass value of a genet was found in the fir forest (4.275 g), the smallest in the bog-alder forest (0.110 g). All populations differed significantly in terms of leaf area, leaf length (with the exception of fir forest and beechwood habitats where the values were the greatest), and leaf width (excluding moist coniferous and bog-alder forests which had the smallest values). In the case of asarabacca, both the mean number of ramets per genet (3.36±0.45 vs. 2.49±0.20) and total rhizome length (40.3±6.4 cm vs. 21.1±1.8 cm) were greater in the beechwood habitat than in the pine community. In the first population genets had 3–5 times greater the total biomass of those from the pine community. Only genets of the latter had proportionately more dry weight biomass in above-ground parts. It seems to be correlated with greater rhizome dieback and disintegration of genets into smaller units. Both populations were significantly different in terms of all examined parameters of leaves. Genets of both the species studied were found to have their own structure of developmental phases that often differed for shoots and rhizomes.     

生长特性差别的胃癌MGC803细胞亚系间细胞骨架、细胞通讯与癌基因表达的比较研究

肿瘤细胞表型差异是临床药物敏感性、抗原性、转移性、潜伏性和进展速度等差异的主要原因。为了弄清恶性表型差别的表现、相关性及调节机理、我们从胃癌MGC 803系分离了单细胞亚系,各亚系按克隆过程的时间差别归纳分组,选快组M 17、中组M 6和慢组M 3进行比较。软琼脂生长实验表明三者的恶性程度有显著差别;M17恶性度最高,M3最低,M6居中。与其它表型联系比较,证明细胞生长速度、细胞微丝、微管骨架破坏及细胞通讯功能抑制都与锚着不依赖性生长的恶性特征有平行相关性。同时,M 17和M 3原癌基因表达有明显差别。     

四膜虫(Tetrahymena shanghaiensis)大核核仁与去膜大核能诱导非细胞体系核重建

外源DNA或染色质在非洲爪蟾卵提取物中可以诱导细胞核样结构的重建。重建核除不具有核仁样结构外,在其它形态结构上与真核细胞核十分相似。前人的工作表明在重建核中具有核仁前体结构。但可能是由于缺少活性核仁组织者的缘故,这些核仁前体不能相互融合形成新生核仁。那么活性核仁组织者在重建核中是否能发挥其功能呢?为了研究这一问题,我们提取纯化了四膜虫的大核与大核的周边核仁。进一步去除大核的核被膜,并将去除核被膜的大核与大核核仁分别加入非洲爪赡卵非细胞体系中。通过电镜超薄切片观察,我们发现无论是与大核染色质相连的周边核仁还是分离纯化的核仁结构在非洲爪赡卵非细胞体系中都不能保持其原有结构特征,而是发生了典型核重建变化,并且在诱导形成的重建核中也看不到核仁样结构。这些结果说明具有活性的核仁组织者在加入非洲爪蟾卵提取物后既不能继续保持其原有的RNA转录功能也不能诱导新的核仁的出现。