Cytological Studies on Some Plants of Sichuan and Neighbouring Regions (I)

From standpoint of floristic division, Sichuan is located in the middle part of Eastern Asiatic Region (Takhtajan 1978) or is the area where Sino-Himalayan Forest Subkingdom and Sino-Japan Forest Subkingdom meet (wu 1979). Here exist many socalled Arcto-Tertiary elements and newly originated species or races. In order to bring the light the origin and differentiation of Eastern Asiatic elements, cytological investigation on plants of this region are very significant. The materials of the following 5 species were collected on Mt. Emei in Sichuan Province. Voucher specimens are kept in CDBI. 1. Toricellia angulata Oliver var. intermedia (Harms) Hu PMC meiotic examination revealed n = 12 at diakinesis (Pl. I fig. 9) Toricellia, consisting of 2 spp., is endemic to Eastern Asiatic Region. Based on our result along with the report of Toricellia tiliifolia (Wall.) DC. (2n=24) by Kurosawa (1977), we argue that the basic chromosome number of Toricellia is 12. Many authors, such as Airy-Shaw (1973), Dahlgren (1975, 1977), Takhtajan (1969, 1980), Thorne (1983), have adopted Hu’s (1934) treatment erecting it as a monotypic family Toricelliaceae. Its systematic position, whether closer to Cornaceae than to Araliaceae or vice versa, has been in dispute. Cytologically it seems closer to Araliaceae, as shown anatomically (Lodriguez 1971), because the basic chromosome number of Cornaceae s. 1. is x=11, 9, 8 (Kurosawa 1977), whereas that of Araliaceae is 12 (Raven 1975). 2. Cardiocrinum giganteum (Wall.) Makino Somatic chromosome number, 2n=24 was determined from root-tip cells (Ph. I. fig. 8). Cardiocrinum (Endl.) Lindl., consisting of 3 spp., is endemic to Eastern Asiatic Region. C. giganteum (Wall.) Makino is distributed from Himalayan region to S. W. China. The present report is in accord with the number reported by Kurosawa (1966) who got the material from Darjeeling of India. However the karyotype of the present plant is slightly different from that given by Kurosawa. In the present material, the satellites of the 1st. pair of chromosomes and the short arms of llst. pair of chromosomes are visibly longer than those of Kurosawa’s drawing (fig. 1, 2) The plants from Yunnan, Sichuan and Hubei Provinces, named as C. giganteum var. yunnanense (Leitchtlin ex Elwes) Stearn, differ slightly from those of Himalayan region also in outer morphological characters. The taxon needs both cytological and taxonomical further studies. 3. Disporum cantoniense (Lour.) Merr. PMC meiotic examination revealed n=8 at diakinesis (Pl. I. fig. 6) This species is widely distributed from Himalayan region through Indo-China to our Taiwan Province and Indonesia. Three cytotypes (2n=14, 16, 30) were reported for the taxon including its variety, var. parviflorum (Wall) Hara, by various authors (Hasegawa 1932, Mehra and Pathamia 1960, Kurosawa 1966, 1971 Mehra and Sachdeva 1976a). Some authors consider D. pullum Salisb. and D. calcaratum D. Don as synonyms of D. cantoniense. So D. cantoniense may be a species aggregate with different extreme races. Sen (1973a, b.) reports that the somatic chromosome numbers of D. pullum and D. calcaratum from Eastern Himalayan region are 14, 16, 28, 30, 32. He also discovered that chromosome alterations in species of Disporum involve not only the number but the structure as well. He found that in species of Liliaceae where the reproduction is mainly vegetative, polysomaty often occurs. In China we have not only D. cantoniense and D. calcaratum but also D. brachystomon Wang et Tang which is similar to D. cantoniense var. parviflorum (Wall.) Hara. These taxa need further critical studies. 4. Paris fargesii Franch. PMC meiotic examination revealed n=5+2B (Voucher no. 112) or n=5 (Voucher no. 62) at MI and AI (Pl. I. fig. 1. 4. 5.). This is the first report for the species. A bridge and a fragment were also observed at AI. Paris polyphylla Smith is extraordinarily polymorphic species. Hara (1969) regards all chinese extreme forms, such as P. fargesii Franch., P. violacea Lévl., P. pubescens (Hand. -Mzt.) Wang et Tang, etc. as infraspecific taxa of P. polyphylla. Needless to say, the various races of P. polyphylla Smith in China need further critical studies and are good material for further study to understand the speciation. 5. Reineckia carnea(Andr.) Kunth Reineckia is a monotypic genus endemic to Eastern Asiatic Region. In the present material somatic chromosome number in root-tip cells is determined as 2n=38 (Pl. I. fig. 7). According to the terminology defined by Levan et al., the karyotype formula is 2n=28 m+10 sm. The length of chromosomes varies from 14.28 μ to 5.5 μ. The idiogram given here (fig. 3) is nearly the same as that presented by Hsu et Li (1984). The same number has been previously reported by several authors, Noguchi (1936), Satô (1942), Therman (1956). The karyotype is relatively symmetrical (2B, accorling to the classi-fication of stebbins 1971) in accord with the opinion of Therman (1956).     

一种供RAPD分析用蜘蛛模板DNA的快速提取方法

简要介绍了一种高效、快速提取蜘蛛模板 Ｄ Ｎ Ａ 供 Ｒ Ａ Ｐ Ｄ 分析的方法⒚该方法具有快速简便、重复性好的优点,提取的 Ｄ Ｎ Ａ 无污染物产生,完全能满足 Ｒ Ａ Ｐ Ｄ 研究的需要⒚     

Quantitative alleles of CR1: coding sequence analysis and comparison of haplotypes in two ethnic groups.

The quantitative expression of complement receptor type 1 (CR1) on erythrocytes is regulated by two CR1 alleles that differ in having genomic HindIII fragments of either 7.4 or 6.9 kb and that determine high (H allele) or low (L allele) CR1 expression, respectively, across a 10-fold range. To investigate whether the product of the L allele may contain amino acid substitutions that make it more susceptible to proteolysis, cDNA sequence spanning the CR1 coding region was analyzed in two donors who were homozygous for the H and L alleles and differed by 7-fold in their mean numbers of CR1 per erythrocyte. Sequence differences were detected at 10 nucleotide positions, including 6 that would cause amino acid substitutions. The HindIII RFLP and 3 of the latter 6 sites were analyzed in genomic DNA of 85 Caucasians and 75 African Americans; sites encoding the other amino acid substitutions were analyzed less extensively. Two major haplotypes defined prototypic H and L alleles in both ethnic groups, suggesting that these alleles existed before the African and European populations diverged. Decreased erythrocyte CR1 expression is associated with impaired clearance of immune complexes from blood. Persistence of the L allele in all populations that have been analyzed may suggest a compensatory survival advantage, perhaps related to malaria or another infectious disease.     

Inhibition of DTYMK significantly restrains the growth of HCC and increases sensitivity to oxaliplatin

Most patients with hepatocellular carcinoma (HCC) are in the middle or advanced stage at the time of diagnosis, and the therapeutic effect is limited. Therefore, this study aimed to verify whether deoxythymidylate kinase (DTYMK) increased in HCC and was an effective therapeutic target in HCC. The findings revealed that the DTYMK level significantly increased and correlated with poor prognosis in HCC. However, nothing else is known, except that DTYMK could catalyze the phosphorylation of deoxythymidine monophosphate (dTMP) to form deoxythymidine diphosphate (dTDP). A number of experiments were performed to study the function of DTYMK in vitro and in vivo to resolve this knowledge gap. The knockdown of DTYMK was found to significantly inhibit the growth of HCC and increase the sensitivity to oxaliplatin, which is commonly used in HCC treatment. Moreover, DTYMK was found to competitively combine with miR-378a-3p to maintain the expression of MAPK activated protein kinase 2 (MAPKAPK2) and thus activate the phospho-heat shock protein 27 (phospho-HSP27)/nuclear factor NF-kappaB (NF-κB) axis, which mediated the drug resistance, proliferation of tumor cells, and infiltration of tumor-associated macrophages by inducing the expression of C-C motif chemokine ligand 5 (CCL5). Thus, this study demonstrated a new mechanism and provided a new insight into the role of mRNA in not only encoding proteins to regulate the process of life but also regulating the expression of other genes and tumor microenvironment through the competing endogenous RNA (ceRNA) mechanism.Subject terms: Oncogenes, Biomarkers     

Structural polymorphism of human telomere G-quadruplex induced by a pyridyl carboxamide molecule

In this work, we described a kinetically slow (hour-scale) but thermodynamically favored G-quadruplex conversion induced by a pyridyl carboxamide molecule. This slow transition was observed through CD spectra and gels, and its final stable parallel conformation was identified by 2-aminopurine experiments. Kinetic experiments indicated that this slow process was a first-order reaction, implying it was a unimolecular conversion. Quite distinctly from other reported ligand-driven G-quadruplex conformation alteration, this slow conversion reveals a novel insight into G-quadruplex polymorphism, in accordance with the behavior of human telomere G-quadruplex in a molecular crowding environment in K(+) solution, further enriching the known structural polymorphism of human telomere DNA and providing new consideration for drug design based on G-quadruplexes.