The structure-anticoagulant activity relationships of sulfated lacquer polysaccharide: effect of carboxyl group and position of sulfation

Regiospecific oxidation of the primary hydroxyl groups in lacquer polysaccharide (LPL, Mw 6.85 x 10(4)) and its NaIO4 oxidation derivatives (LPLde) to C-6 carboxy groups was achieved with NaOCl in the presence of Tempo and NaBr. Sulfate groups were incorporated into the oxidated polysaccharides using Py.SO3 complex as a reagent. Reactivity of polysaccharide hydroxyl group was C-6 > C-2 > C-4. Sulfate groups were mainly linked to the second hydroxy at C-2 in the products. The results of APTT assay showed after incorporation of carboxyl groups into lacquer polysaccharides, the intrinsic coagulation pathway was promoted, and all sulfated polysaccharides had very weak anticoagulant activity within the scope of studied DS (0.39-1.11). These indicated that carboxyl groups and sulfate groups had the synergistic action. At the same time, the anticoagulant activity increased very slowly with the DS in the second hydroxy. This indicated that 6-O-SO3- in the side chains took an important role in the anticoagulant activity.     

Biosynthesis of fusarochromanone and its monoacetyl derivative by Fusarium equiseti.

One fluorescent compound previously named TDP-2 was isolated and purified from a rice culture of Fusarium equiseti (Alaska 2-2). Mass spectral and nuclear magnetic resonance data indicated that it is a C-3'-N-acetyl derivative of fusarochromanone, a newly discovered mycotoxin. Time course studies of synthesis of these two compounds on autoclaved rice and Czapek-Dox medium enriched with soybean peptone indicated that fusarochromanone was converted to TDP-2 in the cultures. A high concentration of peptone in the liquid medium may stimulate both fusarochromanone synthesis and its conversion to TDP-2.     

Shp2 regulates SRC family kinase activity and Ras/Erk activation by controlling Csk recruitment

The protein-tyrosine phosphatase Shp2 plays an essential role in growth factor and integrin signaling, and Shp2 mutations cause developmental defects and/or malignancy. Previous work has placed Shp2 upstream of Ras. However, the mechanism of Shp2 action and its substrate(s) are poorly defined. Additional Shp2 functions downstream of, or parallel to, Ras/Erk activation also are proposed. Here, we show that Shp2 promotes Src family kinase (SFK) activation by regulating the phosphorylation of the Csk regulator PAG/Cbp, thereby controlling Csk access to SFKs. In Shp2-deficient cells, SFK inhibitory C-terminal tyrosines are hyperphosphorylated, and the tyrosyl phosphorylation of multiple SFK substrates, including Plcgamma1, is decreased. Decreased Plcgamma1 phosphorylation leads to defective Ras activation on endomembranes, and may help account for impaired Erk activation in Shp2-deficient cells. Decreased phosphorylation/activation of other SFK substrates may explain additional consequences of Shp2 deficiency, including altered cell spreading, stress fibers, focal adhesions, and motility.     

The Morphology of Fruits and Starches in Bamboos,and Its Relation to Systematic Position

In this article, 30 speceis of bamboos, including 19 genera in 5 tribes, were collected and the morphology of fruits and starches of them was studied. The results are as follows. I. The morphology of fruits is important in studies of systematic position in bamboos. According to the systems of W. Munro and G. Bentham whether the pericarp is adhesive to or free from the seed coat may be taken as a basis of classification. It is also confirmed in this article. It is found in this work that all taxa with a binding pericarp and seed coat are of caryopsis that also has a ventral suture and hilum, while all others with a separated pericarp and seed coat are of bacca or nut, which has no ventral suture and hilum. The former has a hard and thin pericarp and rich endosperm, while the latter has a fleshy and thick pericarp and no endosperm. These characteristics form a basis of classification of major groups. II. In 1907, Brandis found that no any endosperm in matured fruit of Dinochloa, Melocalamus, Melocanna and Ochlandra. It has been proved by Stapf in at least one genus. We found that the baccae of Qiongzhuea, Melocanna, Ferrocalamus and Chimonobambusa Subg. Oerocalama were empty, with no endosperm. This may be a common character of the bacca. We believe, therefore, that the systematic position of Qiongzhuea, Ferrocalamus and Chimonobambusa Subg. Oreocalama is close to Melocanneae. III. Starch grains of bamboo fruits are complex in structure. They are round or ellipsoidal, consisting of 3-22 polyhedral or apple-like small grains. The morphology of starch grains is not so important as fruit in bamboo classification, but some characteristics are of a high value in the identification of genera and species, when they are combined with other features. In Cephalostachyum, the starch grain is very big, with 20-40 μm in diam, and the starch small grain is polyhedral or apple-like with 7.5-22.5 μm in diam, while in Dendrocalamus, the starch grain is small, with 10-28.9 μm in diam. and the starch small grain is only polyhedral, with 3-11.9 μm in diam. The morphology and size of the starch grain and starch small grain are also different in Melocanna and Chimonobambusa Subg. Oreocalama. IV. W. Munro’s system divided Bambuseae into three major groups according to the morphology of flower and fruit. Because the material was not sufficient at that time, the system wrongly put Cephalostachyum, Dendrocalamus into the group Bacciferea. Now it is found that both Cephalostachyum and Dendrocalamus have a nut. Later G. Bentham found this problem and divided the Bambuseae into four subtribes, treating Dendrocalamus as a separate subtribe, Dendrocalamae, and putting the bacca group into another subtribe, Melocannae. It is better, but it also has some shortcomings. Hackel, Gamble, E. G. Camus, A. Camus and Keng Pojie all accepted the view of Bentham, placing Dendrocalamus and Melocanna into different subtribes or tribes.     

Induction of heavy metal binding groups by dexamethasone and Zn in cultured Chinese hamster ovary cells

Cd binding capacity and pulse polarography were used to study the inducibility of sulfhydryl groups in cultured Chinese hamster ovary cells (wild type and a Cd-resistant mutant) in response to dexamethasone (dex) and Zn. Evidence is presented that both the wild type and the mutant responded to dex and Zn treatment by induction of sulfhydryl groups. In wild type for Zn and dex as well as in the mutant for dex, this induction seems to be in the form of sulfhydryls attached to particulate or membrane fractions in the cells. For Zn in the Cd-resistant mutant the induction was in the form of metallothionein.     

Interspecific hybridization of <Emphasis Type="Italic">Prunus persica</Emphasis> with <Emphasis Type="Italic">P. armeniaca</Emphasis> and <Emphasis Type="Italic">P. salicina</Emphasis> using embryo rescue

Embryo rescue technique was used successfully to produce interspecific hybrids by crossing peach (P. persica) as a female parent with apricot (P. armeniaca) and plum (P. salicica). In those crosses that had ‘Yuhualu’ or ‘Zhonghuashoutao’ as female parents, hybrid embryos aborted from the 7th or 8th week after pollination mainly due to post-pollination incompatibility. An embryo rescue protocol was established to rescue such embryos and recover hybrid plants. Modified half-strength MS medium containing 4 mg l⁻¹ 6-BA and 0.5 mg l⁻¹ IBA produced up to 90% germination in the embryos. Modified MS medium with 1.0 mg l⁻¹ 6-BA and 1.0 mg l⁻¹ IBA gave the highest bud induction and multiplication whereas modified MS medium containing 0.5 mg l⁻¹ IAA and 0.2 mg l⁻¹ NAA gave the best rooting percentage. All the hybrids obtained using this embryo rescue technique were verified using simple sequence repeat (SSR) markers. A series of pollen treatments were carried out to partially overcome pre-pollination incompatibility, and it was found accidentally that pollen treatment with electrostatic field not only improved pollen germination but also increased the multiplication coefficient of embryo-induced shoots.     

Involvement of nitric oxide in cerebroside-induced defense responses and taxol production in <Emphasis Type="Italic">Taxus yunnanensis</Emphasis> suspension cells

This work was to characterize the generation of nitric oxide (NO) in Taxus yunnanensis cells induced by a fungal-derived cerebroside and the signal role of NO in the elicitation of plant defense responses and taxol production. (2S,2′R,3R,3′E,4E,8E)-1-O-β-d-glucopyranosyl-2-N-(2′-hydroxy-3′-octadecenoyl)-3-hydroxy-9-methyl-4,8-sphingadienine at 10 μg/ml induced a rapid and dose-dependent NO production in the Taxus cell culture, reaching a maximum within 5 h of the treatment. The NO donor sodium nitroprusside (SNP) potentiated cerebroside-induced H₂O₂ production and cell death. Inhibition of nitric oxide synthase activity by phenylene-1,3-bis(ethane-2-isothiourea) dihydrobromide or scavenging NO by 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide partially blocked the cerebroside-induced H₂O₂ production and cell death. Moreover, NO enhanced cerebroside-induced activation of phenylalanine ammonium-lyase and accumulation of taxol in cell cultures. These results are suggestive of a role for NO as a new signal component for activating the cerebroside-induced defense responses and secondary metabolism activities of plant cells. Taxol is a trademark of Bristol-Myers Squibb, Madison, NJ.     

环孢素A对人早孕期滋养细胞MMP-9与MMP-2表达的调控作用

本研究的目的是探讨环孢素A对人早孕期滋养细胞侵袭能力及基质金属蛋白酶9与2 (matrix metalloproteinase 9 and 2,简称MMP-9与MMP-2)表达的调节作用,为治疗反复自然流产等妊娠疾患提供新的线索。侵袭试验观察CsA对人早孕期滋养细胞侵袭能力的调节作用;RT-PCR与明胶酶谱分析CsA对滋养细胞MMP-9与MMP-2 mRNA及蛋白水平表达的影响;In-cell West- ern检测CsA作用后滋养细胞ERK1/2磷酸化水平。结果发现,1．0μmol/L CsA明显增强滋养细胞侵袭能力,MEK激酶抑制剂U0126可抑制CsA对滋养细胞的促侵袭作用;1．0μmol/L CsA可诱导MMP- 9与MMP-2基因的转录与蛋白分泌;该诱导效应同样可被U0126所阻滞;1．0μmol/L CsA以时间依赖方式促进ERK1/2的磷酸化。结果表明,CsA可激活ERK1/2,通过MAPK/ERK1/2途径促进滋养细胞MMP-9与MMP-2基因的转录与蛋白分泌,从而增强滋养细胞的侵袭能力,对滋养细胞生物学功能具有良性调节作用。     

Chikungunya virus neutralization antigens and direct cell-to-cell transmission are revealed by human antibody-escape mutants

Chikungunya virus (CHIKV) is an alphavirus responsible for numerous epidemics throughout Africa and Asia, causing infectious arthritis and reportedly linked with fatal infections in newborns and elderly. Previous studies in animal models indicate that humoral immunity can protect against CHIKV infection, but despite the potential efficacy of B-cell-driven intervention strategies, there are no virus-specific vaccines or therapies currently available. In addition, CHIKV has been reported to elicit long-lasting virus-specific IgM in humans, and to establish long-term persistence in non-human primates, suggesting that the virus might evade immune defenses to establish chronic infections in man. However, the mechanisms of immune evasion potentially employed by CHIKV remain uncharacterized. We previously described two human monoclonal antibodies that potently neutralize CHIKV infection. In the current report, we have characterized CHIKV mutants that escape antibody-dependent neutralization to identify the CHIKV E2 domain B and fusion loop "groove" as the primary determinants of CHIKV interaction with these antibodies. Furthermore, for the first time, we have also demonstrated direct CHIKV cell-to-cell transmission, as a mechanism that involves the E2 domain A and that is associated with viral resistance to antibody-dependent neutralization. Identification of CHIKV sub-domains that are associated with human protective immunity, will pave the way for the development of CHIKV-specific sub-domain vaccination strategies. Moreover, the clear demonstration of CHIKV cell-to-cell transmission and its possible role in the establishment of CHIKV persistence, will also inform the development of future anti-viral interventions. These data shed new light on CHIKV-host interactions that will help to combat human CHIKV infection and inform future studies of CHIKV pathogenesis.     

萤光素酶报告基因在病毒学研究中的应用

萤光素酶是一类在氧气存在下能催化其底物特异性发光的酶,检出灵敏度高、特异性强。萤光素酶催化底物发光因无须外源光的激发,避免了非特异性干扰,具有其他报告基因不可替代的优势。萤光素酶基因作为报告基因已成为医学科学研究领域的重要标记工具,具有良好的应用前景。我们简要综述了萤光素酶报告基因在病毒学研究中的应用进展。