Antitumour activities of levans produced by Zymomonas mobilis strains

Levans produced by four Zymomonas mobilis strains showed antitumour activity against sarcoma 180 and Ehrlich carcinoma in Swiss albino mice. Levans from two strains (ZAP and CP4) had the highest effects. NMR analysis showed that the polymers were composed only of fructose units. The results suggested that the antineoplasic effect is associated to the polysaccharide molecular weight and that a particular molecular weight range may be responsible for this effect.     

Use of nuclear morphometry characteristics to distinguish between normal and abnormal cervical glandular histologies.

This is a methodological study exploring the use of quantitative histopathology applied to the cervix to discriminate between normal and cancerous (consisting of adenocarcinoma and adenocarcinoma in situ) tissue samples. The goal is classifying tissue samples, which are populations of cells, from measurements on the cells. Our method uses one particular feature, the IODs-Index, to create a tissue level feature. The specific goal of this study is to find a threshold for the IODs-Index that is used to create the tissue level feature. The main statistical tool is Receiver Operating Characteristic (ROC) curve analysis. When applied to the data, our method achieved promising results with good estimated sensitivity and specificity for our data set. The optimal threshold for the IODs-Index was found to be 2.12.     

Functional Modulation of the Glutamate Transporter Variant GLT1b by the PDZ Domain Protein PICK1

The dominant glutamate transporter isoform in the mammalian brain, GLT1, exists as at least three splice variants, GLT1a, GLT1b, and GLT1c. GLT1b interacts with the scaffold protein PICK1 (protein interacting with kinase C1), which is implicated in glutamatergic neurotransmission via its regulatory effect on trafficking of AMPA-type glutamate receptors. The 11 extreme C-terminal residues specific for the GLT1b variant are essential for its specific interaction with the PICK1 PDZ domain, but a functional consequence of this interaction has remained unresolved. To identify a functional effect of PICK1 on GLT1a or GLT1b separately, we employed the Xenopus laevis expression system. GLT1a and GLT1b displayed similar electrophysiological properties and EC₅₀ for glutamate. Co-expressed PICK1 localized efficiently to the plasma membrane and resulted in a 5-fold enhancement of the leak current in GLT1b-expressing oocytes with only a minor effect on [³H]glutamate uptake. Three different GLT1 substrates all caused a slow TBOA-sensitive decay in the membrane current upon prolonged application, which provides support for the leak current being mediated by GLT1b itself. Leak and glutamate-evoked currents in GLT1a-expressing oocytes were unaffected by PICK1 co-expression. PKC activation down-regulated GLT1a and GLT1b activity to a similar extent, which was not affected by co-expression of PICK1. In conclusion, PICK1 may not only affect glutamatergic neurotransmission by its regulatory effect on glutamate receptors but may also affect neuronal excitability via an increased GLT1b-mediated leak current. This may be particularly relevant in pathological conditions such as amyotrophic lateral sclerosis and cerebral hypoxia, which are associated with neuronal GLT1b up-regulation.     

QMEANclust: estimation of protein model quality by combining a composite scoring function with structural density information

Background  

The selection of the most accurate protein model from a set of alternatives is a crucial step in protein structure prediction both in template-based and ab initio approaches. Scoring functions have been developed which can either return a quality estimate for a single model or derive a score from the information contained in the ensemble of models for a given sequence. Local structural features occurring more frequently in the ensemble have a greater probability of being correct. Within the context of the CASP experiment, these so called consensus methods have been shown to perform considerably better in selecting good candidate models, but tend to fail if the best models are far from the dominant structural cluster. In this paper we show that model selection can be improved if both approaches are combined by pre-filtering the models used during the calculation of the structural consensus.     

Variation in heat shock proteins within tropical and desert species of poeciliid fishes

The 70-kilodalton heat shock protein (hsp70) family of molecular chaperones, which contains both stress-inducible and normally abundant constitutive members, is highly conserved across distantly related taxa. Analysis of this protein family in individuals from an outbred population of tropical topminnows, Poeciliopsis gracilis, showed that while constitutive hsp70 family members showed no variation in protein isoforms, inducibly synthesized hsp70 was polymorphic. Several species of Poeciliopsis adapted to desert environments exhibited lower levels of inducible hsp70 polymorphism than the tropical species, but constitutive forms were identical to those in P. gracilis, as they were in the confamilial species Gambusia affinis. These differences suggest that inducible and constitutive members of this family are under different evolutionary constraints and may indicate differences in their function within the cell. Also, northern desert species of Poeciliopsis synthesize a subset of the inducible hsp70 isoforms seen in tropical species. This distribution supports the theory that ancestral tropical fish migrated northward and colonized desert streams; the subsequent decrease in variation of inducible hsp70 may have been due to genetic drift or a consequence of adaptation to the desert environment. Higher levels of variability were found when the 30- kilodalton heat shock protein (hsp30) family was analyzed within different strains of two desert species of Poeciliopsis and also in wild-caught individuals of Gambusia affinis. In both cases the distribution of hsp30 isoform diversity was similar to that seen previously with allozyme polymorphisms.      

三种兰科植物的保护遗传学研究初探

采用随机扩增多态 DNA(RAPD)分析研究了中国3种珍稀濒危兰科植物硬叶兜兰(Paphiopedilum micranthum Tang et Wang)、麻栗坡兜兰(P. malipoense S.C.Chen et Tsi)和独花兰(Changnienia amoena Chien)的遗传多样性与群体遗传结构.12个RAPD引物在2种兜兰中共扩增出131条带.对4个硬叶兜兰群体的检测表明其物种水平的多态条带百分率(PPB)为 71.6%,Nei 的基因多样度(h)为 0.217 1,Shannon多样性指数 (I) 为 0.330 1;4个群体的平均多样性水平为 PPB = 45.2%,h = 0.145 7,I = 0.220 4,低于远交兰花的平均水平.在总遗传变异中,群体间遗传变异占20.31%,略高于远交物种的平均水平.在物种水平上,麻栗坡兜兰的PPB为49.5%,h为0.117 4,I为0.176 4,均大大低于硬叶兜兰.对11个独花兰群体采用16个RAPD引物共扩增出119条带.物种水平PPB=76.5%,h=0.194 1,I=0.305 8;在群体水平上,上述3个指标的平均值则分别为37.2%、0.119 7和0.181 0,均低于远交兰花的平均水平.群体间的遗传变异占45.27%,遗传分化明显高于远交物种的平均水平.导致3个物种遗传多样性偏低而群体间遗传分化较高的主要原因在于人为的过度采挖和生境的片断化.研究结果为兰花保护策略和措施的制定提供了理论基础.     

SeeGH – A software tool for visualization of whole genome array comparative genomic hybridization data

Background  

Array comparative genomic hybridization (CGH) is a technique which detects copy number differences in DNA segments. Complete sequencing of the human genome and the development of an array representing a tiling set of tens of thousands of DNA segments spanning the entire human genome has made high resolution copy number analysis throughout the genome possible. Since array CGH provides signal ratio for each DNA segment, visualization would require the reassembly of individual data points into chromosome profiles.     

Increase of sensitivity of sputum cytology using high-resolution image cytometry: field study results

Lung cancer remains the leading cause of cancer deaths in the developed world. There is no widely accepted method to screen for this cancer. The most commonly used method remains conventional sputum cytology, but this method is hampered by low sensitivity. We tested the hypothesis that sensitivity of sputum cytology for early lung cancer can be greatly improved by using image analysis of sputum cells, at a modest reduction of specificity.The study was double-blinded and used sputum samples from subjects with well-characterized clinical diagnoses. There were 177 cancers, 98 dysplasias, and 558 normals. The study samples were separated into two independent sets: training set and test set. Sputum samples were collected prospectively from subjects with a high probability of having lung cancer. Seven institutions from five countries participated in the study. All subjects had complete clinical diagnoses which included, as a minimum, negative chest x-rays for all negative cancers, while all cancers had confirmed tissue pathology. Samples were prepared according to the Saccomanno method. For conventional cytology, slides were stained using Papanicolaou stain. For image analysis, slides were stained using a DNA-specific (Feulgen-Thionin) stain. An automated, high-resolution image cytometer was used for measurements.At 90% specificity, sensitivity of 60% can be achieved for adenocarcinoma, compared to only 14% sensitivity of conventional cytology (at 99% specificity). Similarly, 45% sensitivity at 90% specificity can be reached for stages 0 and I lung cancer, compared to only 14% (at 99% specificity) using conventional cytology.Cytometry combined with conventional cytology shows an increase in sensitivity to early-stage cancer and to adenocarcinomas compared to conventional cytology alone. While the results are encouraging, the sensitivity to detect early lung cancer should be further improved to 70-80% at 90-95% specificity before this test can be considered for screening of high-risk individuals for lung cancer. Cytometry (Clin. Cytometry) 50:168-176, 2002.     

Effects of long-term fixation on histological quality of undecalcified murine bones embedded in methylmethacrylate

While long-term fixation and storage of specimens is common and useful for many research projects, it is particularly important for space flight investigations where samples may not be returned to Earth for several months (International Space Station) or years (manned mission to Mars). We examined two critical challenges of space flight experimentation: the effect of long-term fixation on the quality of mouse bone preservation and the preservation of antigens and enzymes for both histochemical and immunohistochemical analyses, and how the animal/sample processing affects the preservation. We show that long-term fixation minimally affects standard histological staining, but that enzyme histochemistry and immunolabeling are greatly compromised. Further, we demonstrate that whole animal preservation is not as suitable as whole leg or stripped leg preservation for long-term fixation and all histological analyses. Overall, we recommend whole leg processing for long-term storage of bone specimens in fixative prior to embedding in plastic for histological examination.     

Factors influencing in the response of <i>Schizolobium parahybum</i> (Vell) Blake to <i>Ceratocystis paradoxa</i> and <i>C. moniliformis</i>

In the Ecuadorian coast one of the most destructive diseases of the pachaco is vascular wilt or stem rot caused by Ceratocystis complex, so the aim of this study was to determine the factors that affect the efficiency of the reaction of bark pachaco to this disease. This research was conducted under laboratory conditions, using trees pachaco S38, S41, S98, AE-1, AE-2 and AE-3, and pathogenic species Ceratocystis paradoxa and C. moniliformis. The method utilized was tissue stem bark,with bark sections with 4.5 cm², and a suspension of 3x10⁴ units infection and remained in a humid chamber for 96 hours at 25 ± 5 °C. Were determined grades of resistance/ susceptibility using a scale from 0 to 4, depending on the amount of mycelia and peritecio in each plant sample. Three factors were used: four colonies obtained by several transfers from each fungal specie, four ages of colonies of each fungal specie and four volumes of inoculum applied (units of infection), using for each experiment separately Completely Randomized Design with 4 replications factorial arrangement. For comparison between treatment means was used Tukey test at 5% probability of error. For future trials using this technique, you could use 30-day colonies for C. paradoxa and 40 days for C. moniliformis, and an application volume of 100 μL/cm², it would improve the level of response for the formation of perithecium and mycelia in samples cortex.