Replication and amplification of recombinant plasmid molecules as extra chromosomal elements in transformed mammalian cells

Mouse thymidine kinase negative (TK^?) L cells, F4-12B2TK^? Friend erythroleukemic cells and hamster BHKTK^? cells were transformed in the absence of carrier DNA with closed circular molecules of herpes simplex virus 1 TK DNA cloned in plasmid pAT153 (pTK-1). The physical status of donor DNA in the transformed cells was studied by Southern blot hybridization and spot hybridization techniques. Up to 65 copies of pTK-1 DNA molecules/cell were present in transformed cells grown under selective conditions. Whereas a steady increase in the number of pTK-1 copies/cell was found during the first few weeks of growth in selective medium, 2–8 months later copy numbers varied within the same cell line and their numbers rarely exceeded fifty copies/cell. Donor DNA sequences were found both in the Hirt precipitate and in the supernatant showing that some of the pTK-1 molecules existed in circular form. Many of the cell lines gave a Southern blot hybridization pattern indicative of pTK-1 sequences integrated into high molecular weight DNA as well as present in a circular configuration.     

吲(口朶)乙酸和苄基腺嘌呤对菊芋再生新皮组织分化的影响

根据前人的研究,植物激素对部分茎段剥皮后新皮再生有一定的影响。草本植物菊芋(Helianthus tuberosus L.)在正常情况下环剥后,其维管组织的分化过程与杜仲、茄子很不一样,对于一些外源激素的刺激反应可能也有差异,为此,有必要应用一些外源激素对菊芋环剥后再生新皮的组织分化进行试验研究。     

Studies on trypsin inhibitors in the tubers of cocoyam (Xanthosoma sagittifolium)

Trypsin (EC 3.4.21.4) inhibitors have been isolated and purified by gelfiltration and ion exchange chromatography from the tubers of cocoyam (Xanthosoma sagittifolium). Three isoinhibitors were obtained in an electrophoretically homogeneous state. Their molecular weights estimated by molecular sieve chromatography were found to be 19 950, 17 780 and 23 390, respectively. They showed varied trypsin inhibitory activity which was lost on boiling for 40 min. They were found to have a maximum activity at pH 7.5–8.0.     

A Bryophyte Flora of Wigtownahire

Abstract

Fissidens macaoensis L. Zhang is described as a new species from Macao, South China. The species can be separated from its congeners by a suite of characters, including (1) minute size; (2) subterraneous tubers, composed of one to several cells, growing laterally from mature rhizoids; (3) abundant rhizoidal gemmae found on the surface of the soil and which are developed from subterraneous rhizoids; and (4) relatively large cells of the leaf lamina. This is the first report of a moss where two types of vegetative diaspores occur simultaneously in a single individual. Their adaptation strategy is briefly addressed.     

Phytochemical Compounds from the Crop Byproducts of Tunisian Globe Artichoke Cultivars

The phytochemical composition in two Tunisian globe artichoke cultivars (bracts, leaves, and floral stems) was evaluated in the plant byproducts. The results indicated that the bracts contain the highest levels of total phenols, o‐diphenols, and flavonoids, whereas tannins seem to be more abundant in the leaves. Bracts from the ‘Violet d'Hyères’ cultivar possessed more total phenols (160.8 mg/g DW), flavonoids (64.9 mg/g DW), and anthocyanins (15.3 μg/g DW) than the ‘Blanc d'Oran’ bracts (134.5 mg/g DW, 51.2 mg/g DW, and 8.3 μg/g DW, resp.). Sixty‐four volatile compounds were identified in the headspace of globe artichoke material, particularly in the bracts. The volatile profile showed that sesquiterpene hydrocarbons and non‐terpene derivatives were the main volatiles emitted by the bracts in both cultivars. These results suggest that globe artichoke byproducts might represent a potential source of natural compounds, which could be used as nutraceuticals or as ingredients in the design of functional foods.     

镉诱导的菊芋幼苗膜脂过氧化和抗氧化酶活性及过氧化物酶同工酶的改变

用含有不同浓度(0~400μmol/L)Cd(NO3)2的Hoagland营养液处理砂培的菊芋。处理50d后,测定植物体内镉积累量以及过氧化物酶(POD)、超氧化物歧化酶(SOD)、过氧化氢酶(CAT)活性,并对POD同工酶进行电泳分析。发现在Cd50~100μmol/L浓度内,随着镉浓度的升高,菊芋根和叶中镉的积累量显著增加,而随后积累量的增加有所减少。根和叶中MDA含量显著上升,说明镉引起了膜脂过氧化。0~100μmol/LCd处理,根和叶中POD活性随Cd浓度增加而增强,而在200~400μmol/LCd处理下有所减弱。根和叶SOD活性在50~200μmol/LCd处理下随Cd浓度增加而增强,而在400μmol/LCd处理下SOD活性明显受到抑制。根和叶CAT活性随Cd浓度升高而增强。电泳结果显示,POD同工酶变化明显,镉诱导出一条新酶带LP10。菊芋POD同工酶可以作为镉污染的土壤的生物指示剂。     

An ultrastructural study of bruising in stored potato (Solarium tuberosum L.) tubers

Potato tubers of the cultivar Pentland Dell were investigated for ultrastructural changes following impact. Studies were carried out on tubers after 12 and 24 wk of storage using a falling bolt delivering 0.7 J of energy. Ultra-thin sections were examined by light and transmission electron microscopy. Tubers stored for 12 wk exhibited no visual bruise formation, whereas visible bruising resulted following impact of tubers stored for 24 wk. An ultrastructural sequence of events during bruising was established as (1) a collapse of intracellular compartmentation, (2) increased ribosomal and mitochondrial abundance within the cytoplasm, (3) increased density of cytoplasm adjacent to the cell wall and surrounding amyloplasts, and (4) the development of melanin in bruised cells. These observations are discussed in relation to tuber turgor and physiology during storage.     

Isolation of Functional RNA from Periderm Tissue of Potato Tubers and Sweet Potato Storage Roots

A reliable and efficient protocol is given for the isolation of mRNA from the periderm of potato tubers and sweet potato storage roots. The method relies on a urea-based lysis buffer and lithium chloride to concentrate total RNA away from most of the cytoplasmic components and to prevent oxidation of phenolic complexes. To enhance the physical separation of the RNA from other macromolecular components, the RNA fraction was incubated in the presence of the cationic surfactant Catrimox-14. Poly(A)⁺ mRNA was separated from total RNA and other contaminants by using Promega's MagneSphere technology. The mRNA was suitable for cDNA library construction and RNA fingerprinting.     

Proliferation of meristematic clusters in disposable presterilized plastic bioreactors for the large-scale micropropagation of plants

Summary Proliferation of meristematic clusters of several plants in an inexpensive airlift bioreactor system, consisting of a disposable presterilized light transmittable plastic film vessel is described. The optimal shape, size, and structural function of the disposable plastic bioreactor are based on the bubble column and airlift glass bioreactors. The disposable bioreactors are designed in a conical configuration with a single inoculation and harvest port and multiple use dispensing and mixing accessories. Shearing damage and foaming problems known to exist in bioreactors due to the plant's rigid cell wall and size were greatly reduced in the disposable plastic bioreactors. The disposable bioreactors were used for propagule proliferation and growth, using meristem and bud clusters of potato, fern, banana, and gladiolus. The clusters' biomass increased five-to eightfold over a period of 26–30 d, depending on the species. The clusters were separated mechanically by a chopper made of a grid of knives. The chopped propagules were inoculated to agar medium for further growth and developed into transplantable plants. In the case of gladiolus and potato, corms and tubers developed in a sucrose-elevated storage organ induction medium, respectively, after the initial formation of small shoots. The plantlets and storage organs were transplanted to an acclimation greenhouse and continued to grow with a 95–100% survival, depending on the species. Plant development was followed for a period of 16 wk in fern and 12–14 wk in potato, banana, and gladiolus and normal shoot and leaf growth was observed. The feasibility of large-scale liquid cultures for plant micropropagation is discussed.     

鹰嘴豆孢克鲁维酵母利用菊芋原料同步糖化与发酵生产乙醇

菊芋含有大量的菊粉多糖,且种植简单、产量高,是极具开发价值的替代玉米等粮食作物生产燃料乙醇的原料。文中研究了鹰嘴豆孢克鲁维酵母Y179利用菊芋原料同步糖化与发酵生产乙醇。鹰嘴豆孢克鲁维酵母Y179具有高效分泌菊粉酶的能力,摇瓶试验显示Y179酵母能够利用完全由菊芋原料配制而成的培养基良好生长并发酵产生乙醇。通气及温度对乙醇产量影响明显,相对厌氧环境对Y179酵母发酵产乙醇具有促进作用,30℃发酵温度相对37℃和42℃更有利于乙醇产量提高。种子液培养时间及接种量对乙醇产量影响较小。在5 L发酵罐中以10%(V/V)量接入预培养36 h的Y179种子液,发酵液完全由菊芋干粉配制而成,总糖含量22%(W/V),30℃不通气,300 r/min搅拌,发酵144 h时,乙醇浓度达到12.3%(V/V),糖醇转化效率86.9%,糖利用率大于93.6%。初步研究结果显示鹰嘴豆孢克鲁维酵母Y179在利用菊芋原料生产乙醇方面具有良好应用前景。