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Pullulanase from Klebsiella pneumoniae strain FG9 has an unusual N-terminal amino acid sequence that includes six repeats of the tripeptide Gly-X-Pro. This type of sequence is characteristic of animal collagens and collagen-like proteins which form triple helical structures. We have investigated the molecular organization of this bacterial pullulanase isolated from the cell surface of Escherichia coli cells that carry the cloned FG9 pulA (pullulanase encoding) gene. Non-denaturing polyacrylamide gel analysis shows that pullulanase exists as higher order, apparently homogeneous, structures. We have used highly purified bacterial collagenase to probe the role of the collagen-like region and we demonstrate that this feature is essential for non-covalent association of pullulanase homotrimers. In addition we show collagenase-specific release of cell-bound pullulanase. 相似文献
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Vassiliki Koufopanou Graham Bell 《Evolution; international journal of organic evolution》1991,45(8):1806-1822
The nature of the variation which is created by mutation can show how the direction of evolution is constrained by internal biases arising from development and pre-existing design. We have attempted to quantify these biases by measuring eight life history characters in developmental mutants of Volvox carteri. Most of the mutants in our sample were inferior to the wild type, but deviated by less than tenfold from the wild-type mean. Characters differed in mutability, suggesting different levels of canalisation. Most correlations between life history characters among strains were positive, but there was a significant negative correlation between the size and the number of reproductive cells, suggesting an upper limit to the total quantity of germ produced by individuals. The most extreme phenotypes in our sample were very vigorous, showing that not all mutations of large effect are unconditionally deleterious. We investigated the effect of developmental constraints on the course of evolution by comparing the variance and covariance patterns among mutant strains with those among species in the family Volvocaceae. A close correspondence between patterns at these two levels would suggest that pre-existing design has a strong influence on evolution, while little or no correspondence shows the action of selection. The variance generated by mutation was equal to that generated by speciation in the family Volvocaceae, the genus Volvox, or the section Merillosphaera, depending on the character considered. We found that mutation changes the volume of somatic tissue independently of the quantity of germ tissue, so that the interspecific correlation between soma and germ can be attributed to selection. The negative correlation between size and number of germ cells among mutants of V. carteri is also seen among the larger members of the family (Volvox spp.), but not among the smaller members, suggesting a powerful design constraint that may be responsible for the absence of larger forms in the entire group. 相似文献
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Theodora?Koromila Panagiotis?Georgoulias Zoe?Dailiana Evangelia?E?Ntzani Stavroula?Samara Chris?Chassanidis Vassiliki?Aleporou-Marinou Panagoula?KolliaEmail author 《Human genomics》2013,7(1):21
Background
Osteoporosis has a multifactorial pathogenesis characterized by a combination of low bone mass and increased fragility. In our study, we focused on the effects of polymorphisms in CER1 and DKK1 genes, recently reported as important susceptibility genes for osteoporosis, on bone mineral density (BMD) and bone markers in osteoporotic women. Our objective was to evaluate the effect of CER1 and DKK1 variations in 607 postmenopausal women. The entire DKK1 gene sequence and five selected CER1 SNPs were amplified and resequenced to assess whether there is a correlation between these genes and BMD, early menopause, and bone turnover markers in osteoporotic patients.Results
Osteoporotic women seem to suffer menopause 2 years earlier than the control group. The entire DKK1 gene sequence analysis revealed six variations. There was no correlation between the six DKK1 variations and osteoporosis, in contrast to the five common CER1 variations that were significantly associated with BMD. Additionally, osteoporotic patients with rs3747532 and rs7022304 CER1 variations had significantly higher serum levels of parathyroid hormone and calcitonin and lower serum levels of osteocalcin and IGF-1.Conclusions
No significant association between the studied DKK1 variations and osteoporosis was found, while CER1 variations seem to play a significant role in the determination of osteoporosis and a potential predictive role, combined with bone markers, in postmenopausal osteoporotic women.5.
Vassiliki Pelekanou George Notas Marilena Kampa Eleftheria Tsentelierou Efstathios N. Stathopoulos Andreas Tsapis Elias Castanas 《PloS one》2013,8(12)
Gliomas are common and lethal tumors of the central nervous system (CNS). Genetic alterations, inflammatory and angiogenic processes have been identified throughout tumor progression; however, treatment still remains palliative for most cases. Biological research on parameters influencing cell survival, invasion and tumor heterogeneity identified several cytokines interfering in CNS inflammation, oxidative stress and malignant transformation, including TNF-superfamily (TNFSF) members. In this report we performed a meta-analysis of public gene-array data on the expression of a group of TNFSF ligands (BAFF, APRIL, TWEAK) and their receptors (BAFF-R, TACI, BCMA, Fn14) in gliomas. In addition, we investigated by immunohistochemistry (IHC) the tumor cells'' expression of these ligands and receptors in a series of 56 gliomas of different grade. We show that in IHC, BAFF and APRIL as well as their cognate receptors (BCMA, TACI) and Fn14 expression correlate with tumor grade. This result was not evidenced in micro-arrays meta-analysis. Finally, we detected for the first time Fn14, BAFF, BCMA and TACI in glioma-related vascular endothelium. Our data, combined with our previous report in glioma cell lines, suggest a role for these receptors and ligands in glioma biology and advance these molecules as potential markers for the classification of these tumors to the proliferative, angiogenic or stem-like molecular subtype. 相似文献
6.
Vassiliki Lalioti 《Visual Anthropology: Published in cooperation with the Commission on Visual Anthropology》2013,26(5):439-456
ABSTRACT Significant transformations in the ways the ethnic “self” and its relationship to the “other” are perceived have led to the transgression of the two traditional poles (East and West) that were prevalent in the definition of Greekness since the creation of the Greek nation-state. By placing the photographs of immigrants published in the most popular local newspaper in Central Greece within their wider social and historical context, we can “see” that immigrants (a group that is perceived to be homogeneous and transcendental) constitute a new axis around which the negotiation of ethnic identity and otherness in Greece is now conducted. 相似文献
7.
Andreja Radović Vassiliki Kati Melita Perčec Tadić Damijan Denac Dražen Kotrošan 《Bird Study》2013,60(1):106-114
Capsule Spatial environmental modelling well predicted nesting distribution of the White stork in Southeast Europe and can be used in conservation planning with respect to climate change.Aims To create spatial models for predicting White Stork presence and densities in the Southeast Europe to identify areas of suitable habitat for White Storks.Methods We quantified the habitat used by nesting White storks in Southeast Europe. Using spatial modelling, we defined a set of free and available online environmental variables that predict the breeding localities of the species. We employed pseudo-absences and the kriging of the residuals in order to create predictive models of nest presence and density.Results The presence–absence model was found to be precise in predicting the presence of nests. Both density and presence of breeding pairs were best explained negatively by elevation, slope, minimum temperature during May, and distance to the nearest human settlement and positively by topographic wetness index, total area of human settlement and spring precipitation.Conclusion Our robust and easily repeatable models offer a conservation tool to reveal suitable but unoccupied localities for breeding White Storks pairs which may inform our understanding of how climate change might affect the species' distribution in the future. For example, protecting White Storks on the Dalmatian coast may become even more significant in the future, because the Dalmatian coast is predicted as the only suitable breeding area in Croatia later this century. 相似文献
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Aaron S. Karat Tanvier Omar Anne von Gottberg Mpho Tlali Violet N. Chihota Gavin J. Churchyard Katherine L. Fielding Suzanne Johnson Neil A. Martinson Kerrigan McCarthy Nicole Wolter Emily B. Wong Salome Charalambous Alison D. Grant 《PloS one》2016,11(11)
BackgroundEarly mortality among HIV-positive adults starting antiretroviral therapy (ART) remains high in resource-limited settings, with tuberculosis (TB) the leading cause of death. However, current methods to estimate TB-related deaths are inadequate and most autopsy studies do not adequately represent those attending primary health clinics (PHCs). This study aimed to determine the autopsy prevalence of TB and other infections in adults enrolled at South African PHCs in the context of a pragmatic trial of empiric TB treatment (“TB Fast Track”).ConclusionsTB, followed by bacterial infections, were the leading findings at autopsy among adults with advanced HIV enrolled from primary care clinics. To reduce mortality, strategies are needed to identify and direct those at highest risk into a structured pathway that includes expedited investigation and/or treatment of TB and other infections. 相似文献
9.
Aleporou-Marinou V Deli C Ninios Y Agelopoulou B Marinou H Patargias T 《Biochemical genetics》2003,41(7-8):235-243
Nuclei from Bactrocera oleae and Ceratitis capitata larvae contain a major protein that shares most of the characteristics of vertebrate high mobility group (HMG) proteins. Proteins are extracted from nuclei with 0.35 M NaCl, are soluble in 5% perchloric acid, are relatively small (molecular weight in the range of 10–16 kDa), and have both a high basic and a high acidic amino acid content. The amino acid constitution of these proteins is similar to that of the HMGB protein family of vertebrates. The proteins cross-react with antibodies raised against the HMGD chromosomal protein of Drosophila melanogaster. The possible relatedness of these proteins to high mobility group proteins is discussed. 相似文献
10.
Aims: To evaluate food choice and eating difficulty experienced by older Greek edentate patients. Subjects: Three samples of patients seeking provision of replacement dentures were studied. A primary study of urban mainland U1 (n=54) and island rural R1 samples (n=84) was followed by a mainland urban U2 sample (n=119) in the Secondary study. Setting: Greek dental clinics. Intervention: Semi‐structured interviews (SSI) were employed, using both open and closed questions. Design: The primary study used SSI to identify eating difficulty experienced by two culturally different Greek groups. The secondary study established patterns of difficulty for comparisons between an urban Greek population and northern European urban studies. Main Outcome Measures: The prevalence of eating difficulty, the degree of difficulty eating specified foods and the exclusion of foods because difficult. Results: Most patients expressed difficulty eating at least one type of food, a high percentage of these patients were willing to eat foods found difficult, while others use particular methods of food preparation that make food easier to eat. Chicken illustrated the importance of specifying the method of cooking when questioning eating difficulties. Roast meats provided insight into the more difficult end of the food range. Raw vegetables were rated difficult. Apples and oranges were also food of particular interest. Conclusions: The semi‐structured interview method provides a succesful method to identify eating difficulty and food choices by older Greek complete denture wearers. Differences, probably largely cultural, were identified between Greek island rural and mainland urban communities. Greek food choices differed favourably from an English sample, strikingly in that Greek patients report continuing to eat difficult foods despite difficulty eating them. This may be relevant to health data on Greek populations that show better mortality statistics despite adverse factors such as high prevalence of smoking. 相似文献