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31.
Serotypes of Bacillus thuringiensis and the commercial strain of Bacillus popilliae were examined for their inherent resistance to antibiotics and their mutation potential in respect to neomycin and kanamycin, the presence of which would preclude the use of plasmids marked by genes for resistance to the antibiotics. Clones on initial plates were detected by the recurrence of resistance colonies at superimposable sites on serial replicaplates containing the antibiotic. Susceptible strains were selected for the determination of their antibiotic-resistance mutation potential. Three varieties of B. thuringiensis were found to be doubly resistant, seven varieties were singly resistant (Neor), and three other varieties, including B. popilliae, were susceptible to both antibiotics. Estimates of mutation ratios revealed that three serotypes developed no resistant mutants to either antibiotics in populations as high as 3.0 × 1010; seven other serotypes developed no resistance to kanamycin in populations as high as 4.6 × 109 cells. Three other serotypes exhibited mutation ratios as high as 1.6 × 10?2. We were unable to determine the mutation ratio for B. popilliae. 相似文献
32.
Prof. Dr. med. Heiko Braak 《Cell and tissue research》1979,204(3):431-440
Summary Cortical lamination and parcellation of the retrosplenial region in the human brain is evaluated with the aid of frontal serial sections stained for nerve cells (15 m), myelin sheaths (100 m), and lipofuscin granules (800 m).For the most part, the retrosplenial region is buried in the depth of the sulcus corporis callosi covering the posterior parts of the cingulate gyrus. It lies between the supracallosal derivatives of the allocortex (fascia dentata, cornu ammonis, subiculum) and the mature parietal isocortex.The region can be subdivided into five areas. The transitory periallocortical Area ectosplenialis is followed by a richly differentiated proisocortical core displaying extremely externopyramidal, externoteniate, and astriate to unitostriate characteristics. The parvocellular core is averagely poor in pigment (Typus clarus) and rich in myelinated fibres (Typus dives). Minor structural differences allow for its subdivision into a lateral, an intermediate, and a medial retrosplenial field. The accompanying Area parasplenialis is adjacent to the equoteniate parietal isocortex. It is only weakly externopyramidal, externoteniate, and propebistriate. The already homotypical field shows an average pigmentation and myelin content. These structural features permit its classification as a belt area of the retrosplenial core.Supported by grants from the Deutsche Forschungsgemeinschaft 相似文献
33.
Moein Khalighi Guilhem Sommeria-Klein Didier Gonze Karoline Faust Leo Lahti 《PLoS computational biology》2022,18(6)
Ecological memory refers to the influence of past events on the response of an ecosystem to exogenous or endogenous changes. Memory has been widely recognized as a key contributor to the dynamics of ecosystems and other complex systems, yet quantitative community models often ignore memory and its implications.Recent modeling studies have shown how interactions between community members can lead to the emergence of resilience and multistability under environmental perturbations. We demonstrate how memory can be introduced in such models using the framework of fractional calculus. We study how the dynamics of a well-characterized interaction model is affected by gradual increases in ecological memory under varying initial conditions, perturbations, and stochasticity.Our results highlight the implications of memory on several key aspects of community dynamics. In general, memory introduces inertia into the dynamics. This favors species coexistence under perturbation, enhances system resistance to state shifts, mitigates hysteresis, and can affect system resilience both ways depending on the time scale considered. Memory also promotes long transient dynamics, such as long-standing oscillations and delayed regime shifts, and contributes to the emergence and persistence of alternative stable states. Our study highlights the fundamental role of memory in communities, and provides quantitative tools to introduce it in ecological models and analyse its impact under varying conditions. 相似文献
34.
Davit Bzhalava Hanna Johansson Johanna Ekstr?m Helena Faust Birgitta M?ller Carina Eklund Peter Nordin Bo Stenquist John Paoli Bengt Persson Ola Forslund Joakim Dillner 《PloS one》2013,8(6)
To assess presence of virus DNA in skin lesions, swab samples from 82 squamous cell carcinomas of the skin (SCCs), 60 actinic keratoses (AKs), paraffin-embedded biopsies from 28 SCCs and 72 kerathoacanthomas (KAs) and fresh-frozen biopsies from 92 KAs, 85 SCCs and 92 AKs were analyzed by high throughput sequencing (HTS) using 454 or Ion Torrent technology. We found total of 4,284 viral reads, out of which 4,168 were Human Papillomavirus (HPV)-related, belonging to 15 known (HPV8, HPV12, HPV20, HPV36, HPV38, HPV45, HPV57, HPV59, HPV104, HPV105, HPV107, HPV109, HPV124, HPV138, HPV147), four previously described putative (HPV 915 F 06 007 FD1, FA73, FA101, SE42) and two putatively new HPV types (SE46, SE47). SE42 was cloned, sequenced, designated as HPV155 and found to have 76% similarity to the most closely related known HPV type. In conclusion, an unbiased approach for viral DNA detection in skin tumors has found that, although some new putative HPVs were found, known HPV types constituted most of the viral DNA. 相似文献
35.
Kraiczy P Hellwage J Skerka C Becker H Kirschfink M Simon MM Brade V Zipfel PF Wallich R 《The Journal of biological chemistry》2004,279(4):2421-2429
The etiologic agent of Lyme disease, Borrelia burgdorferi, is capable of circumventing the immune defense of a variety of potential vertebrate hosts. Previous work has shown that interaction of host-derived complement regulators, factor H and factor H-like protein 1 (FHL-1), with up to five complement regulator-acquiring surface proteins (CRASPs) expressed by resistant B. burgdorferi sensu lato isolates conferred complement resistance. In addition expression of CRASP-1 is directly correlated with complement resistance of Borrelia species. This work describes the functional characterization of BbCRASP-1 as the dominant factor H and FHL-1-binding protein of B. burgdorferi. The corresponding gene, zs7.a68, is located on the linear plasmid lp54 and is different from factor H-binding Erp proteins that are encoded by genes localized on circular plasmids (cp32). Deletion mutants of BbCRASP-1 were generated, and a high affinity binding site for factor H and FHL-1 was mapped to the C terminus of BbCRASP-1. Similarly, the predominant binding site of factor H and FHL-1 was localized to the short consensus repeat 7. Factor H and FHL-1 maintain their cofactor activity for factor I-mediated C3b inactivation when bound to BbCRASP-1, and factor H is up to 6-fold more efficient in mediating C3b conversion than FHL-1. In conclusion, BbCRASP-1 (i). binds the host complement regulators factor H and FHL-1 with high affinity, (ii). is the key molecule of the complement resistance of spirochetes, and (iii). is distinct from the Erp protein family. Thus, BbCRASP-1 most likely contributes to persistence of B. burgdorferi and to pathogenesis of Lyme disease. 相似文献
36.
María Fernanda Lammoglia Cobo Julia Ritter Regina Gary Volkhard Seitz Josef Mautner Michael Aigner Simon Vlkl Stefanie Schaffer Stephanie Moi Anke Seegebarth Heiko Bruns Wolf Rsler Kerstin Amann Maike Büttner-Herold Steffen Hennig Andreas Mackensen Michael Hummel Andreas Moosmann Armin Gerbitz 《PLoS pathogens》2022,18(4)
Reconstitution of the T cell repertoire after allogeneic stem cell transplantation is a long and often incomplete process. As a result, reactivation of Epstein-Barr virus (EBV) is a frequent complication that may be treated by adoptive transfer of donor-derived EBV-specific T cells. We generated donor-derived EBV-specific T cells by stimulation with peptides representing defined epitopes covering multiple HLA restrictions. T cells were adoptively transferred to a patient who had developed persisting high titers of EBV after allogeneic stem cell transplantation for angioimmunoblastic T-cell lymphoma (AITL). T cell receptor beta (TCRβ) deep sequencing showed that the T cell repertoire of the patient early after transplantation (day 60) was strongly reduced and only very low numbers of EBV-specific T cells were detectable. Manufacturing and in vitro expansion of donor-derived EBV-specific T cells resulted in enrichment of EBV epitope-specific, HLA-restricted T cells. Monitoring of T cell clonotypes at a molecular level after adoptive transfer revealed that the dominant TCR sequences from peptide-stimulated T cells persisted long-term and established an EBV-specific TCR clonotype repertoire in the host, with many of the EBV-specific TCRs present in the donor. This reconstituted repertoire was associated with immunological control of EBV and with lack of further AITL relapse. 相似文献
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39.
L. Mark Elbroch Jake M. Ferguson Howard Quigley Derek Craighead Daniel J. Thompson Heiko U. Wittmer 《Proceedings. Biological sciences / The Royal Society》2020,287(1938)
Top-down effects of apex predators are modulated by human impacts on community composition and species abundances. Consequently, research supporting top-down effects of apex predators occurs almost entirely within protected areas rather than the multi-use landscapes dominating modern ecosystems. Here, we developed an integrated population model to disentangle the concurrent contributions of a reintroduced apex predator, the grey wolf, human hunting and prey abundances on vital rates and abundance of a subordinate apex predator, the puma. Increasing wolf numbers had strong negative effects on puma fecundity, and subadult and adult survival. Puma survival was also influenced by density dependence. Overall, puma dynamics in our multi-use landscape were more strongly influenced by top-down forces exhibited by a reintroduced apex predator, than by human hunting or bottom-up forces (prey abundance) subsidized by humans. Quantitatively, the average annual impact of human hunting on equilibrium puma abundance was equivalent to the effects of 20 wolves. Historically, wolves may have limited pumas across North America and dictated puma scarcity in systems lacking sufficient refugia to mitigate the effects of competition. 相似文献
40.
Federico Lucantoni Manuela Salvucci Heiko Dussmann Jochen H.M. Prehn 《Biochimica et Biophysica Acta (BBA)/Molecular Cell Research》2021,1868(10):119095
BCL2 family proteins are important regulators of mitochondrial outer membrane permeabilization (MOMP). In recent years, BCL2 family proteins have also been linked to the regulation of mitochondrial bioenergetics and dynamics. Given their overexpression in breast cancer cells, we sought to explore whether two key members of this family, BCL2 and BCL(X)L impacted on mitochondrial fusion/fission processes. By employing a single cell imaging and RNA sequencing we found that overexpression of BCL2 or BCL(X)L increases mitochondrial dynamics and alters the expression profile of genes involved in this process. Collectively, our data show that overexpression of BCL2 proteins regulates mitochondrial dynamics in breast cancer tumor cells. 相似文献