Reliability and accuracy of reporting cervical intraepithelial neoplasia (CIN) in 15 laboratories throughout Italy: phase 1 of a national programme of external quality control in cervical screening

This paper reports results of a first phase of a pilot study to assess and improve quality of diagnoses in cervical cytological laboratories located throughout Italy. It represents the first phase of an External Quality Assurance programme (EQA). In the first phase, two sets of cervical smears representing a range of diagnoses were circulated among participating laboratories. Responses were recorded on a standardized form. Participants were asked to assess the adequacy of the smear and formulate a diagnosis. They were also asked to recommend management of the patient on the basis of the smear report and judge the degree of diagnostic difficulty of each slide. Crude index of agreement, unweighted and weighted kappas, diagnostic specific kappas, sensitivity and specificity as well as clinical indices of variability were calculated. In the second phase, two additional sets of slides were circulated after discussion of the first phase. There was striking variability between laboratories, both in terms of diagnoses offered and recommendations for management on individual slides. Assessment of the degree of difficulty of each slide was also very variable. Discrimination between CINII and CINIII was poor, confirming the choice of merging these two categories in the Bethesda classification. However, discrimination between CINI and CINII was also unsatisfactory. The results were discussed in workshops and it was possible to reach a consensus diagnosis in 35 of 40 smears. This study confirms the need for external quality control programmes.     

Recent advances in development of marker-free transgenic plants: Regulation and biosafety concern

During the efficient genetic transformation of plants with the gene of interest, some selectable marker genes are also used in order to identify the transgenic plant cells or tissues. Usually, antibiotic- or herbicide-selective agents and their corresponding resistance genes are used to introduce economically valuable genes into crop plants. From the biosafety authority and consumer viewpoints, the presence of selectable marker genes in released transgenic crops may be transferred to weeds or pathogenic microorganisms in the gastrointestinal tract or soil, making them resistant to treatment with herbicides or antibiotics, respectively. Sexual crossing also raises the problem of transgene expression because redundancy of transgenes in the genome may trigger homology-dependent gene silencing. The future potential of transgenic technologies for crop improvement depends greatly on our abilities to engineer stable expression of multiple transgenic traits in a predictable fashion and to prevent the transfer of undesirable transgenic material to non-transgenic crops and related species. Therefore, it is now essential to develop an efficient marker-free transgenic system. These considerations underline the development of various approaches designed to facilitate timely elimination of transgenes when their function is no longer needed. Due to the limiting number of available selectable marker genes, in future the stacking of transgenes will be increasingly desirable. The production of marker-free transgenic plants is now a critical requisite for their commercial deployment and also for engineering multiple and complex trait. Here we describe the current technologies to eliminate the selectable marker genes (SMG) in order to develop marker-free transgenic plants and also discuss the regulation and biosafety concern of genetically modified (GM) crops.     

Purification and properties of phototrophic bacteria Thiocapsa roseopersicina hydrogenase bound with chromatophores]

The method of solution and puridication of hydrogenase from chromatophores of purpur sulphur bacteria Thiocapsa roseopersicina strain BBS are described. Hydrogenase molecular weight is 73000. It contains 4,4 mole S2- and 3.1 mole Fe2+ per mole of protein; pI 4.15. The enzyme absorption spectrum has the maximun et 400-410 nm, which is characteristic of proteins containing non-haem iron. Membrane--linked enzyme as well as soluble hydrogenase of that microorganism is characterized by high thermal stability: inactivation occurs at the temperature above 78 degrees C when the optimal temperature for that enzyme is 70 degrees C. Homogenous enzyme catalyses D2--H2O exchange reaction, reversible redox reaction of methyl viologene and benzyl viologene.     

Hydrogenase activity in Thiocapsa roseopersicina according to the D2--H20 metabolic reaction]

Extracts of Thiocapsa roseopersicina cells show hydrogenase activity, measured by evolution of H2 from reduced methylviologene (MV) and by D2-H2O exchange reaction. According to these reactions the most part of hydrogenases is found to be in the soluble fraction. Hydrogenase activity measured in the exchange reaction is completely inhibited by p-chloromercurybenzoate (5-10- minus 3 M), iodacetate (1-10- minus 2 M) and 26% inhibited by KCN and o-phenanthroline (5-10- minus 3 M). Evolution of H2 from reduced MV was not inhibited by o-phenanthroline, KCN and iodacetate and was inhibited by 66% only with p-chloromercurybenzoate. Light and ATP stimulated hydrogenase activity of chromatophores did not affect on its activity in the soluble fraction. The results obtained show that there are certain differences in hydrogenase systems responsible for the exchange reaction and evolution of H2.     

Surfactant production by the Rhodococcus erythropolis sH-5 bacterium grown on various carbon sources

It has been shown that the Rhodococcus erythropolis sH-5 strain can produce surfactants associated and not associated with the cell wall. Their content depends on medium composition, the nature of the carbon source, and oxygen supply. The highest biosurfactant (bioSF) yield is achieved by growing R. erythropolis sH-5 in medium with 2% kerosene at neutral pH. It has been found that the bioSF yield and emulsification index for various hydrocarbons depend on the kind of the nitrogen source used by the bacterium, increasing with replacement of KNO₃ by NaNO₃. The yields of biomass and bioSF in R. erythropolis depend on growth temperatures (max at 30°C) but not on water quality (bidistillate, catholyte, or anolyte). It has been found that sH-5 produces more cell-associated bioSF than extracellular species.     

马占相思林冠蜘蛛群落的结构分析

用杀灭菊酯喷洒林冠,收集得蜘蛛２６种,１９９只。群落组成以不结网为为主,全年均保持较高数量水平。结网类从４月至１０月成指数曲数下降。４个相似样地上的群落结构显著差异。以ＭａｃＡｒｔｈａｒ分布模型为基础,求出每个种在群落中的数量－时间－空间的重要值。结果以斜蛛的ＮＴＤ为最,斑络新妇幼体为次。蜘蛛－昆虫群落的营养结构在各样地上是一致的。蜘蛛作为捕食者,占总数１２－１５％。     

珍珠菜属系统发育关系的初步研究

本文运用形态学性状对珍珠菜属（Lysimachia)进行系统发育分析。内类群包括珍珠菜属29个代表种以及珍珠菜族其它单种、寡种属;仙客来属（Cylclamen)被选作外类群。最简约性分析表明,珍珠菜属并不构成－自然分类群;在其严格一致化树的二岐分支中,异花珍珠菜（L.crispidens)单独构成一支,其它所有内类群构成一支。香草亚属（subgen.Idiophyton)、木黄连花亚属（subgne.Lysimachiopsis)以及珍珠菜亚属（subgen.palladia)均表现为单系群,而黄连花亚属（subgen.Lysimachia)则为一异形的并系群。球尾花亚属（subgen.Naumburgia)仍“内藏”于珍珠菜属的主体之中。而喉鳞花亚属（subgen.Seleucia)则偏离出来而与七瓣莲属（Trien talis)构成姐妹群。如何准确地界定珍珠菜属和进行属下分类群的划分,还需进一步研究。     

Fast evolutionary genetic differentiation during experimental colonizations

Founder effects during colonization of a novel environment are expected to change the genetic composition of populations, leading to differentiation between the colonizer population and its source population. Another expected outcome is differentiation among populations derived from repeated independent colonizations starting from the same source. We have previously detected significant founder effects affecting rate of laboratory adaptation among Drosophila subobscura laboratory populations derived from the wild. We also showed that during the first generations in the laboratory, considerable genetic differentiation occurs between foundations. The present study deepens that analysis, taking into account the natural sampling hierarchy of six foundations, derived from different locations, different years and from two samples in one of the years. We show that striking stochastic effects occur in the first two generations of laboratory culture, effects that produce immediate differentiation between foundations, independent of the source of origin and despite similarity among all founders. This divergence is probably due to powerful genetic sampling effects during the first few generations of culture in the novel laboratory environment, as a result of a significant drop in N _e. Changes in demography as well as high variance in reproductive success in the novel environment may contribute to the low values of N _e. This study shows that estimates of genetic differentiation between natural populations may be accurate when based on the initial samples collected in the wild, though considerable genetic differentiation may occur in the very first generations of evolution in a new, confined environment. Rapid and significant evolutionary changes can thus occur during the early generations of a founding event, both in the wild and under domestication, effects of interest for both scientific and conservation purposes.     

Actual and potential rates of hydrogen photoproduction by continuous culture of the purple non-sulphur bacterium Rhodobacter capsulatus

The influence of (NH₄)₂SO₄ concentration and dilution rate (D) on actual and potential H₂ photoproduction has been studied in ammonium-limited chemostat cultures of Rhodobacter capsulatus B10. The actual H₂ production in a photobioreactor was maximal (approx. 80 ml h⁻¹l⁻¹) at D = 0.06 h⁻¹ and 4 mM (NH₄)₂SO₄. However, it was lower than the potential H₂ evolution (calculated from hydrogen evolution rates in incubation vials), which amounted to 100–120 ml h⁻¹ l⁻¹ at D = 0.03–0.08 h⁻¹. Taking into account the fact that H₂ production in the photobioreactor under these conditions was not limited by light or lactate, another limiting (inhibiting) factor should be sought. One possibility is an inhibition of H₂ production by the H₂ accumulated in the gas phase. This is apparent from the non-linear kinetics of H₂ evolution in the vials or from its inhibition by the addition of H₂; initial rates were restored in both cases after the vials had been refilled with argon. The actual H₂ production in the photobioreactor at D = 0.06 h⁻¹ was shown to increase from approximately 80 ml h⁻¹ l⁻¹ to approximately 100 ml h⁻¹ l⁻¹ under an argon flow at 100 ml min⁻¹. Under maximal H₂ production rates in the photobioreactor, up to 30% of the lactate feedstock was utilised for H₂ production and 50% for biomass synthesis. Received: 22 April 1997 / Received revision: 14 July 1997 / Accepted: 27 July 1997