VK_3诱导悬浮培养的胡萝卜细胞凋亡

VK_3是一种醌类物质,在体内通过氧化还原产生超氧化自由基。我们的实验发现,VK_3对悬浮培养的胡萝卜细胞及原生质体有致死作用。这种作用是浓度依赖性的。100—800μmol/L的VK_3能引起10%—33%的细胞死亡。当VK_3浓度达到1mmol/L时,死亡率达到100%。DNA电泳分析发现,600和800μmol/L的VK_3处理过的细胞和原生质体产生大小为180bp整数倍的梯状条带。而在更高或更低浓度的处理中则没有观察到这种条带。用TUNEL方法检测,在400—800μmol/L浓度的处理中观察到细胞核DNA的断裂。而在更高或更低浓度的处理中则没有观察到这种断裂。由此我们推测,适当浓度的VK_3能诱导胡萝卜细胞及原生质体凋亡。     

高产辅酶Q10结构类似物抗性突变株的选育

以土壤杆菌(Agrobacteriumsp.)TLY-4为出发菌株,采用70%致死剂量的NTG进行诱变处理,通过筛选抗辅酶Q10结构类似物维生素K3突变株,定向选育到了两株辅酶Q10高产突变株,编号为R-122和R-015,其摇瓶发酵72h时的辅酶Q10产量分别为57.3 mg/L和59.9 mg/L,较出发菌株提高了35.7%和41.6%。通过连续传代实验,表明突变株高产辅酶Q10的遗传性状稳定。实验以有机溶剂DMF和吐温-80共同增溶的方法,解决了维生素K3在培养基中易析出的问题,并确定了平板培养基中维生素K3的最小抑菌浓度为0.15 mg/mL。     

氨基酸对于Monascus ruber生物合成Monacolin K影响的研究

在Monacolin K发酵中添加氨基酸后发现较高质量浓度的氨基酸高度抑制了Monacolin K的产量。0.1 g.L-1的D-甲硫氨酸在发酵第4 d添加可以提高产量30%以上,而L-甲硫氨酸则没有此功能,D,L-甲硫氨酸因D-甲硫氨酸的关系也有一定的增产效果。以甲硫氨酸代替蛋白胨作为主要氮源,则抑制了polyketide途径的前期步骤,因此严重抑制了色素及Monacolin K的生产。另外,发现1 g.L-1的L-苯丙氨酸的添加时间越早越有利于Monacolin K的生产,在起始时添加发酵单位可达135.9 mg.L-1,可能是因为L-苯丙氨酸经过脱氨后,可以进入polyketide途径从而促进了Monacolin K的生产。     

Phylogenetic relationships within the ‘core’ Laureae (Litsea complex, Lauraceae) inferred from sequences of the chloroplast gene matK and nuclear ribosomal DNA ITS regions

A phylogenetic analysis of the core Laureae (Litsea complex) was conducted using the chloroplast gene matK and nuclear ribosomal DNA ITS sequences to investigate generic relationships and boundaries within the complex. Despite low genetic divergence for matK, rooting of the tree with Sassafras resulted in Iteadaphne as the basal member of the complex and five resolved clades: a Neolitsea clade and then Laurus, Parasassafras, Litsea and Lindera clades in a large polytomy with unresolved Lindera sections plus Umbellularia. A combined analysis of the data (identical to the ITS results) provided a more resolved phylogeny of the Laureae, with four major lineages: the Laurus, Litsea, Lindera and Actinodaphne II clades. These clades also appear to reflect the importance of inflorescence structure and ontogeny within the Laureae, as well as data from cuticular micromorphology, but there was no support for traditional generic characters such as 2- versus 4- celled anthers. As a result, genera such as Actinodaphne, Litsea, Neolitsea and Lindera were polyphyletic in all analyses. Parasassafras was related to Sinosassafras by the matK data, but distant from it in the ITS and combined analyses.     

Oxidative stress mediates toxicity of pyridoxal isonicotinoyl hydrazone analogs

Pyridoxal isonicotinoyl hydrazone (PIH) and many of its analogs are effective iron chelators in vivo and in vitro, and are of interest for the treatment of secondary iron overload. Because previous work has implicated the Fe(3+)-chelator complexes as a determinant of toxicity, the role of iron-based oxidative stress in the toxicity of PIH analogs was assessed. The Fe(3+) complexes of PIH analogs were reduced by K562 cells and the physiological reductant, ascorbate. Depletion of the antioxidant, glutathione, sensitized Jurkat T lymphocytes to the toxicity of PIH analogs and their Fe(3+) complexes, and toxicity of the chelators increased with oxygen tension. Fe(3+) complexes of pyridoxal benzoyl hydrazone (PBH) and salicyloyl isonicotinoyl hydrazone (SIH) caused lipid peroxidation and toxicity in K562 cells loaded with eicosapentenoic acid (EPA), a readily oxidized fatty acid, whereas Fe(PIH)(2) did not. The lipophilic antioxidant, vitamin E, completely prevented both the toxicity and lipid peroxidation caused by Fe(PBH)(2) in EPA-loaded cells, indicating a causal relationship between oxidative stress and toxicity. PBH also caused concomitant lipid peroxidation and toxicity in EPA-loaded cells, both of which were reversed as its concentration increased. In contrast, PIH was inactive, while SIH was equally toxic toward control and EPA-loaded cells, without causing lipid peroxidation, indicating a much smaller contribution of oxidative stress to the mechanism of toxicity of these analogs. In summary, PIH analogs and their Fe(3+) complexes are redox active in the intracellular environment. The contribution of oxidative stress to the overall mechanism of toxicity varies across the series.     

Integrated biostratigraphy based on planktonic foraminifera and dinoflagellates across the Cretaceous/Paleogene (K/Pg) transition at the Izeh section (SW Iran)

The present work is based on semi-quantitative study carried on detailed sampling (samples are spaced by 5, 10 and 15 cm close to the boundary) of an essentially continuous and expanded section crossing the Cretaceous–Paleogene (K/Pg) boundary in Iran. By this work, we attempt to detail biostratigraphy based on planktonic foraminifera biozones and correlate biozones and subzones with dinocyst events. The entire Cretaceous–Paleogene interval contains rich, diversified and well-preserved planktonic foraminifera and dinoflagellate cyst assemblages. Four planktonic foraminiferal biozones have been recognized across the Cretaceous–Paleogene transition (K/Pg): Abathomphalus mayaroensis Biozone including Plummerita hantkeninoides Subzone from the Late Maastrichtian and Guembelitria cretacea (including Hedbergella holmdelensis and Parvularugoglobigerina longiapertura subzones), Parvularugoglobigerina eugubina Biozone and Parasubbotina pseudobulloides Biozone belonging to the Early Danian. These biozones have been correlated with four dinocyst biozones: the Manumiella seelandica Biozone belonging to the Late Maastrichtian and the Alisocysta reticulata, Senoniasphaera inornata and Damassadinium californicum biozones from the Early Danian. At this section, like at the El Kef section (GSSP for the K/Pg) and the auxiliary sections, an Ir anomaly is detected indicating the K/Pg boundary. This geochemical anomaly coincides also with mass extinctions of planktonic foraminifera species. The extinct species are in particular the large, complex tropical and subtropical taxa dwelling in subsurface and lower photic water. The mass extinctions at the Izeh section occurred over a succinct period of time similar to the K/Pg type section at El Kef (Tunisia). These sudden mass extinctions indicate a catastrophic pattern event occurring at the Maastrichtian/Danian boundary. In contrast the organic-walled dinocysts were less affected by the mass extinction and most species crossed the K/Pg boundary without showing mass and sudden extinctions. Nevertheless, they showed changes in their assemblages’ structure beyond the K/Pg boundary. Especially, Manumiella seelandica and M. druggii, typical species of Antarctic Maastrichtian dinocysts assemblages, occur in coeval deposits at the Izeh section; they persist through the Lower Danian and, like in Tunisia (e.g., El Kef section, Ellès section) show an obvious increase in relative abundance.     

Macrophage inflammatory protein-1α (MIP-1α) enhances a receptor activator of nuclear factor κB ligand (RANKL) expression in mouse bone marrow stromal cells and osteoblasts through MAPK and PI3K/Akt pathways

Osteolytic lesions are rapidly progressive during the terminal stages of myeloma, and the bone pain or bone fracture that occurs at these lesions decreases the patients’ quality of life to a notable degree. In relation to the etiology of this bone destruction, it has been reported recently that MIP-1α, produced in large amounts in myeloma patients, acts indirectly on osteoclastic precursor cells, and activates osteoclasts by way of bone-marrow stromal cells or osteoblasts, although the details of this process remain obscure. In the present study, our group investigated the mechanism by which RANKL expression is induced by MIP-1α and the effects of MIP-1α on the activation of osteoclasts. RANKL mRNA and RANKL protein expressions increased in both ST2 cells and MC3T3–E1 cells in a MIP-1α concentration-dependent manner. RANKL mRNA expression began to increase at 1 h after the addition of MIP-1α; the increase became remarkable at 2 h, and continuous expression was observed subsequently. Both ST2 and MC3T3-E1 cells showed similar levels of increased RANKL protein expression at 1, 2, and 3 days after the addition of MIP-1α. After the addition of MIP-1α, the amount of phosphorylated ERK1/2 and Akt protein expressions showed an increase, as compared to the corresponding amount in the control group. On the other hand, the amount of phosphorylated p38MAPK protein expression showed a decrease from the amount in the control group after the addition of MIP-1α. U0126 (a MEK1/2 inhibitor) or LY294002 (a PI3K inhibitor) was added to ST2 and MC3T3-E1 cells, and was found to inhibit RANKL mRNA and RANKL protein expression in these cells. When SB203580, a p38MAPK inhibitor, was added, RANKL mRNA and RANKL protein expression were increased in these cells. MIP-1α was found to promote osteoclastic differentiation of C7 cells, an osteoclastic precursor cell line, in a MIP-1α concentration-dependent manner. MIP-1α promoted differentiation into osteoclasts more extensively in C7 cells incubated together with ST2 and MC3T3-E1 cells than in C7 cells incubated alone. These results suggested that MIP-1α directly acts on the osteoclastic precursor cells and induces osteoclastic differentiation. This substance also indirectly induces osteoclastic differentiation through the promotion of RANKL expression in bone-marrow stromal cells and osteoblasts. The findings of this investigation suggested that activation of the MEK/ERK and the PI3K/Akt pathways and inhibition of p38MAPK pathway were involved in RANKL expression induced by MIP-1α in bone-marrow stromal cells and osteoblasts. This finding may be useful in the development of an osteoclastic inhibitor that targets intracellular signaling factors.     

Macro nutrient cation uptake by plants

Summary In pot experiments with barley, mustard, leek, lettuce and spinach, and in a field experiment with 30 cultivars of barley uptakes of K, Mg, Ca, Na and N were studied at varying concentrations and activities of these cations in the soil solution.The sum of macro cations (K, Mg, Ca, Na) in meq per 100 g aerial plant parts were independent of the chemical composition of the soil solution, but dependent on plant species and on the N concentration in the plant.The ratios K /2(\bar In_{Ca} + \bar In_{Mg} ))$$ " align="middle" border="0"> of mean net inflows of Mg, Ca and K into plants and corresponding cation activity ratios (a_Mg/a_Ca and K /\sqrt {a_{Ca} + a_{Mg} } $$ " align="middle" border="0"> ) in the soil solution were linearly related and highly correlated under conditions in which growth rate and/or rate of incorporation into new tissues constituted the rate determining step of cation uptake. Consequently, mean net inflows of K, Mg and Ca were independent of ion concentration and ion activity of K, Mg or Ca in the soil solution under the conditions of constant activity ratio.The results agree with the concept that plants have a finite cation uptake capacity, and that plants are in a equilibrium-like state with the activities of K, Mg, and Ca ions in the soil solution. The results indicate that both ratios and content of exchangeable cations should be considered in our evaluation of soil test data.