In vitro tuberization in white yam (Dioscorea rotundata Poir)

Nodal cuttings of white yam were induced to produce microtubers on a MS-revised medium supplemented with various concentrations of sucrose, 20 mgl^–1 L-cysteine, 0.5 mgl^–1 kinetin and 0.7% agar. The frequency of tuberization was affected by the daylength, which is optimal at 12 and 16 h of light depending on the sucrose concentration. The microtubers were planted in a seed bed and grown to maturity. The importance of in vitro tuberization of yam as a means of international germplasm distribution or exchange as well as for the propagation of planting material is discussed.     

Differential amplification of antifreeze protein genes in the pleuronectinae

Summary The organization of antifreeze protein (AFP) genes in the yellowtail flounder was investigated by Southern blotting and the characterization of clones from a genomic library. This flounder, like the closely related winter flounder, has a set of 10–12 linked but irregularly spaced AFP genes. However, it lacks the tandemly amplified set of 20 such genes that are present in the winter flounder. DNA sequence analysis of a tandemly repeated gene from winter flounder showed that it can code for one of the two most abundant AFP components in the serum. Consistent with this higher AFP gene dosage, the peak serum AFP level in midwinter was 9 mg/ml in the winter flounder and only 4 mg/ml in the yellowtail flounder. A recent amplification of the AFP gene in the winter flounder lineage might be responsible for the higher serum AFP levels in this fish. This increase in gene dosage might have helped the winter flounder colonize the ice-laden, shallow-water niche that it currently occupies along the east coast of North America. Genomic Southern blotting of two other righteye flounders, the smooth flounder and the American plaice, illustrates another example of a differential amplification of AFP genes that correlates with a species' exposure to ice.     

Differential effects of transforming growth factor-beta on the synthesis of extracellular matrix proteins by normal fetal rat calvarial bone cell populations

To determine the effects of transforming growth factor-beta (TGF-beta) on the different cell types that exist in bone, cell populations (I-IV), progressively enriched in osteoblastic cells relative to fibroblastic cells, were prepared from fetal rat calvaria using timed collagenase digestions. TGF-beta did not induce anchorage-independent growth of these cells, nor was anchorage-dependent growth stimulated in most populations studied, despite a two- to threefold increase in the synthesis of cellular proteins. In all populations the synthesis of secreted proteins increased 2-3.5-fold. In particular, collagen, fibronectin, and plasminogen activator inhibitor synthesis was stimulated. However, different degrees of stimulation of individual proteins were observed both within and between cell populations. A marked preferential stimulation of plasminogen activator inhibitor was observed in each population, together with a slight preferential stimulation of collagen; the effect on collagen expression being directed primarily at type I collagen. In contrast, the synthesis of SPARC (secreted protein acidic rich in cysteine/osteonectin was stimulated approximately two-fold by TGF-beta, but only in fibroblastic populations. Collectively, these results demonstrate that TGF-beta stimulates matrix production by bone cells and, through differential effects on individual matrix components, may also influence the nature of the matrix formed by different bone cell populations. In the presence of TGF-beta, osteoblastic cells lost their polygonal morphology and alkaline phosphatase activity was decreased, reflecting a suppression of osteoblastic features. The differential effects of TGF-beta on bone cell populations are likely to be important in bone remodeling and fracture repair.     

中国人线粒体DNA的八种限制酶图及其电镜结构

尽管Anderson等人(1981)已测定了人mtDNA的全部序列,但还不能全面地反映整个人类mtDNA核苷酸序列的情况。因此,在具有代表特征的中国人mtDNA序列被测定之前,为了开展对中国人mtDNA的遗传学研究,笔者构建了中国人mtDNA的8种限制酶图。并通过电镜技术对mtDNA进行了研究,发现了一种周长为2μm的小环状DNA,推测它可能在核DNA和mtDNA之间的信息传递或衰老发生中起到某些作用。     

Transforming activities of sodium fluoride in cultured Syrian hamster embryo and BALB/3T3 cells

The transforming activity of sodium fluoride was studied in the SHE and the BALBl3T3 cell culture systems. Initiating and promoting activities were then investigated by means of the orthogonal methodology. Sodium fluoride was found to induce morphological transformation of SHE cells seeded on a feeder layer of X-irradiated cells at high concentrations (75–125 g/ ml). When the cells were seeded in the absence of a feeder-layer, the transformation frequencies increased in a dose-dependent manner with the concentrations of sodium fluoride ranging from 0 to the highly toxic concentration of 200 g/ml. In the BALBl3T3 cell system, sodium fluoride was negative in the standard Kakunaga procedure, while through the experiment designed by table L₈ (2⁷) of the orthogonal method, an initiating-like effect and a weak promoting activity were detected within the concentrations ranging from a 25 g/ ml to a 50 g/ ml concentration which is highly toxic for BALBl3T3 cells. From these results, it is suggested that, besides a genetic mode of action, sodium fluoride could possibly act through a non-genotoxic mechanism.Abbreviations CE cloning efficiency - NaF sodium fluoride - SHE Syrian hamster embryo - TF transformation frequency     

一种纯化细菌有机磷水解酶的简便方法

Cibacron blue T_3GA与溴化氰活化的Sepharose 4B偶联后,产生一种能有效地分离有机磷水解酶的吸附剂。用0.15mol/L MgCl_2溶液从黄杆菌P3—2细胞抽提出的粗酶液通过柱层析分离,即可得到纯化8倍、酶活性回收率为269.4％的纯酶制品。该酶制品用凝胶电泳测是均一的。     

Changes in pulmonary Cu−Zn contents in superior mesenteric artery occlusion shock of rabbit

Contents of Cu and Zn of into-pulmonary blood (IPB), out-pulmonary blood (OPB), Lung tissue, and supernatant and macrophages of Lung Lavage were determined in superior mesenteric artery occlusion (SMAO) shock of rabbits. Zn of pulmonary tissue was 11.42 +/- 0.60 and 14.52 +/- 1.78 (micrograms/g wet wt) in SMAO shock and control groups, respectively. Content of Zn was found to be lower, Cu was not changed, and Cu/Zn ratio increased in lung tissue in SMAO shock. Contents of Cu and Zn in other samples were not changed. The results suggest that lower Zn in lung tissue related to acute lung injury.     

On-line thermal monitoring of aspartic acid separation in a high voidage ion-exchange column at high flow rate

A simple thermal monitoring technique has been successfully applied to an adsorption system using a novel ion exchanger with a large internal void volume (voidage) which can be operated at high superficial velocity (SV). Temperature changes resulting from heats of adsorption could be followed effectively using semi-conductor thermistor devices inserted into the resin through the column wall. Results show that, despite the high feed rates adopted, the thermal signals generated can be consistently related to the position of the breakthrough front within the bed.     

Changes in soil microflora associated with control of Sclerotium Rolfsii by Furfuraldehyde

The efficacy of 2‐furfuraldehyde for control of Sclerotium rolfsii was studied in laboratory and greenhouse experiments. Mycelial growth of the fungus was reduced proportionally with concentrations of 0.1–0.5 ml furfuraldehyde l^‐1 agar medium, and viability of sclerotia diminished on exposure to 2‐furfuraldehyde vapours. Detectable populations of bacteria and fungi, including Trichoderma spp., were reduced significantly (9=0.05) when furfuraldehyde was added to the agar used for soil dilution plates of untreated soil. Repeated treatments of natural soil with the fumigant significantly increased populations of Trichoderma spp. and bacteria, but diminished numbers of actinomycetes. Increasing dosages applied to soil artificially infested with S. rolfsii caused a reduction of disease on lentil, Lens culinaris. Results indicate that the compound, when applied to field soil, changes the composition of soil microflora and has potential for integrated control of S. rolfsii.     

A Comparison of the Efficacy of Nuclear Polyhedrosis and Granulosis Viruses in Spray and Bait Formulations for the Control of Agrotis segetum (Lepidoptera: Noctuidae) in Maize

Agrotis segetum nuclear polyhedrosis virus (AsNPV) and granulosis virus (AsGV), propagated in laboratory cultures of A. segetum in England and A. ipsilon in Spain, respectively, were applied to plots of maize plants at the one‐ to four‐leaf stage of growth. Plots were arranged in a 6 x 6 Latin square design and infested with second‐instar A. segetum larvae (the common cutworm). Each virus was applied in separate treatments by two application methods; as an aqueous spray containing 0.1% Agral as a wetting agent, and as a bran bait. The NPV was applied at a rate of 4 X 10¹² polyhedra/ha, and the GV at 4 X 10¹³ granules/ha. Soil and plants were sampled for larvae on three occasions following virus treatment: 24 h, 4 days and 11 days. The larvae were reared on diet in the laboratory, until death or pupation, to examine the rate and level of viral infection. Infection data showed 87.5% and 91% NPV infection and 12.5% and 55% GV infection in spray and bait treatments, respectively, in larvae sampled 24 h after treatment. In larvae sampled 4 days after treatment, the results were 78% and 100% NPV infection, and 13% and 6% GV infection. A total of only six larvae were retrieved on day 11. In both treatments larvae infected with AsNPV died significantly more rapidly and at an earlier instar than those infected with AsGV, indicating that AsNPV appears to have better potential as a control agent for A. segetum.