Biological and physicochemical characterization of recombinant human erythropoietins fractionated by Mono Q column chromatography and their modification with sialytransferase

Ten erythropoietin (EPO) fractions differing in sialic acid content, ranging from 9.5 to 13.8 mol mol^–1 of EPO, were obtained from baby hamster kidney cell-derived recombinant human EPO by Mono Q column chromatography. The mean pI values of the EPO fractions determined by IEF-gel electrophoresis systematically shifted from 4.11 to 3.31, coinciding with the sialic acid content, without a change in the constitution of asialo N-linked oligosaccharides of each fraction. Although a linear relationship between thein vivo bioactivity and the sialic acid content of the fractionated, samples was observed until 12.1 mol mol^–1 of EPO, there was no further increase in their activity over 12.4 mol mol^–1 of EPO. On the other hand, an inverse relationship between thein vitro bioactivity and sialic acid content of EPO was observed. Also, we showed that thein vivo bioactivity of some fractions with low sialic acid contents was increased after treatment with 2,6-sialyltransferase, but thein vivo bioactivity of the other fractions with high sialic acid contents was either decreased or not affected.Abbreviations EPO erythropoietin - rHuEPO recombinant human erythropoietin - hCG human chorionic gonadotropin - BHK baby hamster kidney - CHO Chinese hamster ovary - NeuAc N-acetyl neuraminic acid - Gal galactose - HRCs hemolyser-resistant cells - WST-1 2-(4-iodophenyl)-3-(4-nitrophenyl)-5-(2,4-disulfophenyl)-2H-tetrazolium Na - IEF isoelectric focusing - pI isoelectric point     

Geographic structure of chloroplast DNA polymorphisms in European oaks

Chloroplast DNA polymorphisms have been detected by the conventional Southern-blotting hybridization method in four species of European oaks (Quercus petraea, Q. robur, Q. pubescens and Q. pyrenaica). Three polymorphisms, shared by at least three of these species, can be scored directly in ethidium bromidestained gels and were used in a broad survey of the level of differentiation of the oak species and of their pattern of genetic structure in western Europe. The highly significant geographic variation and the high genetic differentiation (Gst=0.895, S_Gst=0.025) indicate a low level of cytoplasmic gene flow. We conclude that cytoplasmic genomes are well suited for the reconstruction of past migrational routes of such a complex of species.     

非双层脂对辅酶Q-细胞色素c还原酶呼吸控制率的影响

分离提纯的辅酶Q细胞色素c还原酶经胆酸盐透析法重组于各种脂质体上,发现脂质体中PE含量的升高可显著提高辅酶Q-细胞色素c还原酶的呼吸控制率.在PE含量为60%-80%时达到最高值,DOPE的L_x—H_Ⅱ的相变温度显著低于DEPE,脂酶体中DOPE含量的提高,可显著提高酶的呼吸控制率,而DEPE的影响很小,改变脂酶体中心磷脂的含量对呼吸控制率的影响较小.含有PE脂酶体中酶的CD谱419nm处的正峰,随PE含量的增大而增强,表明酶蛋白中血红素辅基的微环境有所改变.NBD-DOPE标记脂酶体研究了不同脂酶体的 L_x-H_Ⅱ的相变性质,表明PE含量的降低脂质体的相变温度上升甚至消失.     

Soil and rhizosphere microorganisms have the same Q10 for respiration in a model system

We compared the Q₁₀ relationship for root‐derived respiration (including respiration due to the root, external mycorrhizal mycelium and rhizosphere microorganisms) with that of mainly external ectomycorrhizal mycelium and that of bulk soil microorganisms without any roots present. This was studied in a microcosm consisting of an ectomycorrhizal Pinus muricata seedling growing in a sandy soil, and where roots were allow to colonize one soil compartment, mycorrhizal mycelium another compartment, and the last compartment consisted of root‐ and mycorrhiza‐free soil. The respiration rate in the bulk soil compartment was 30 times lower than in the root compartment, while that in the mycorrhizal compartment was six times lower. There were no differences in Q₁₀ (for 5–15°C) between the different compartments, indicating that there were no differences in the temperature relationship between root‐associated and non‐root‐associated organisms. Thus, there are no indications that different Q₁₀ values should be used for different soil organism, bulk soil or rhizosphere‐associated microorganisms when modelling the effects of global climate change.     

A SURVEY OF SIZES AND WEIGHTS OF BEMISIA TABACI (HOMOPTERA:ALEYRODIDAE)B BIOTYPE LIFE STAGES FROM FIELD GROWN COTTON AND CANTALOUPES

Abstract Size and weight measurements were made for all the life stages of Bemisia tabaci (Gennadius) B biotype from field grown cotton ( Gossypium hirsutum L.) and cantaloupe ( Cucumis melo L., var. cantalupensis ) in Phoenix, AZ and Fargo, ND, USA in 2000 and 2001. Nymphal volumes were derived from the measurements. The average nymphal volume increase for settled 1 st to the late 4th instar was exponential. The greatest increase in body volume occurred during development from the 3rd to early 4th instar. Nymphs on cotton leaves were wider, but not longer compared with those on cantaloupe. Ventral and dorsal depth ratios of nymphal bodies from 1 st to late 4th instars from cantaloupe leaves were significantly greater compared with those from cotton leaves. During nymphal development from 1st to 4th instar, the average (from the two host species) ventral body half volume increased by nearly 51 times compared with an increase of 28 times for the dorsal body half volume. Adult female and male average lengths, from heads to wing tips, were 1 126 μm and 953 μm, respectively. Average adult female and male weights were 39 and 17 μg, respectively. Average widths, lengths, and weights of eggs from cotton and cantaloupe were, 99 μm, 197 μm, and 0.8 μg, respectively. Average widths, lengths, and weights for exuviae of non-parasitized nymphs from both cotton and cantaloupe were 492 μm, 673 μm, and 1.20 μg, respectively; and widths, lengths, and weights of parasitized nymph exuviae were 452 μm, 665 μm, and 3.62 μg, respectively. Both exuviae from non-parasitized and parasitized nymphs from cotton leaves were wider, longer, and heavier than those from cantaloupe leaves.     

土壤呼吸的影响因素及全球尺度下温度的影响

土壤呼吸是指土壤释放ＣＯ２的过程,主要由土壤微生物和根系产生。作为一个复杂的生态学过程,土壤呼吸在受到植被,微生物等生物因素影响的同时,也受到了温度,湿度、ｐＨ值等环境因素的作用,并且随着人类影响的增强,人为因素的作用也越来越大。根据已有工作,讨论了影响土壤呼吸的主要影响因素及其相互关系,分析了全球范围内湿润地区森林植被的土壤呼吸与纬度的关系以及土壤呼吸与年均温的关系,得出了全球范围的Ｑ１０值为１     

Measurement of the relative electron-transport capacity of Photosystem I and Photosystem II in spinach chloroplasts

The ratio of Photosystem (PS) II to PS I electron-transport capacity in spinach chloroplasts was compared from reaction-center and steady-state rate measurements. The reaction-center electron-transport capacity was based upon both the relative concentrations of the PS II_α, PS II_β and PS I centers, and the number of chlorophyll molecules associated with each type of center. The reaction-center ratio of total PS II to PS I electron-transport capacity was about 1.8:1. Steady-state electron-transport capacity data were obtained from the rate of light-induced absorbance-change measurements in the presence of ferredoxin-NADP⁺, potassium ferricyanide and 2,5-dimethylbenzoquinone (DMQ). A new method was developed for determining the partition of reduced DMQ between the thylakoid membrane and the surrounding aqueous phase. The ratio of membrane-bound to aqueous DMQH₂ was experimentally determined to be 1.3:1. When used at low concentrations (200 μM), potassium ferricyanide is shown to be strictly a PS I electron acceptor. At concentrations higher than 200 μM, ferricyanide intercepted electrons from the reducing side of PS II as well. The experimental rates of electron flow through PS II and PS I defined a PS II/PS I electron-transport capacity ratio of 1.6:1.     

The significance of morphometric and fecundity differences between the ‘biotypes' of the Brown Planthopper,Nilaparvata lugens

A morphometric analysis of biotypes 1, 2 and 3 from the International Rice Research Institute, Philippines, reared respectively on rice cultivars TN1, Mudgo and ASD7, showed significant differences, but some overlap between them. When the three biotypes were each reared for a single generation on TN1, morphometric differences were very greatly reduced and the distributions widely overlapped.Biotypes 2 and 3 were significantly less fecund than biotype 1 when reared on their normal host varieties. When all were reared on TN1, biotype 3 showed a somewhat lower fecundity than did 1 and 2, but the difference was less than previously reported.It is concluded that the evidence for the association of morphometric differences with virulence characteristics inN. lugens is not proved. Equally there is no evidence that morphometric data may be used to identify field populations with distinct patterns of virulence.

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La signification des différences morphométriques et de fécondité entre des biotypes deNilaparvata lugens

Résumé Ce que l'on a appelé des biotypes deN. lugens sont des populations caractérisées par différents types de virulence à l'égard de différents cultivars résistants de riz, mis en évidence par des essais variétaux systématiques. Différents chercheurs ont tenté de trouver des caractères morphologiques pour identifier ces biotypes.Nous avons fait une analyse morphométrique des biotypes 1, 2 et 3 de l'International Rice Research Institute (IRRI) Philippines. Quand ils sont élevés sur leur propre varieté — biotype 1 sur TN1, 2 sur Mudgo, 3 sur ASD7 — des différences significatives sont observées, bien qu'il y ait un chevauchement considérable. Quand les 3 populations biotypes sont élevées sur la variété sensible TN1, les différences morphométriques sont réduites et le chevauchement fortement augmenté. Nous pourrions alors conclure qu'une part importante de la différenciation morphométrique est due à des facteurs écologiques et non à des différences génétiques entre les populations. Des chercheurs avaient indiqué des différences de fécondité entre les biotypes de l'IRRI, le biotype 3 étant significativement moins fécond; les résultats publiés son contradictoires. Nos observations suggèrent une certaine diminution de la fécondité pour le biotype 3 élevé sur TN1, mais plus limitée que les autres auteurs ne l'avaient envisagée.Nous en concluons qu'il n'y a pas de véritable preuve pour étayer l'hypothèse que les biotypes deN. lugens sont caractérisés par des paramètres morphométriques génétiquement déterminés. Il est alors fallacieux de suggérer que de tels caractères pourraient être utilisés pour identifier des populations avec différents types de virulence. Nous repoussons aussi l'hypothèse que les biotypes représentent une étape dans le processus de spéciation.

     

Assessment of a model for intron RNA secondary structure relevant to RNA self-splicing--a review

A widespread class of introns is characterized by a particular RNA secondary structure, based upon four conserved nucleotide sequences. Among such "class I" introns are found the majority of introns in fungal mitochondrial genes and the self-splicing intron of the large ribosomal RNA of several species of Tetrahymena. A model of the RNA secondary structure, which must underlie the self-splicing activity, is here evaluated in the light of data on 16 further introns. The main body or "core structure" of the intron always consists of the base-paired regions P3 to P9 with the associated single-stranded loops, with P2 present also in most cases. Two minority sub-classes of core structure occur, one of which is typical of introns in fungal ribosomal RNA. Introns in which the core structure is close to the 5' splice site all have an internal guide sequence (IGS) which can pair with exon sequences adjacent to the 5' and 3' splice sites to align them precisely, as proposed by Davies et al. [Nature 300 (1982) 719-724]. In these cases, the internal guide model allows us to predict correctly the exact location of splice sites. All other introns probably use other mechanisms of alignment. This analysis provides strong support for the RNA splicing model which we have developed.