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71.
Identification of nuclear import and export signals within Fli-1: roles of the nuclear import signals in Fli-1-dependent activation of megakaryocyte-specific promoters 下载免费PDF全文
The Ets factor Friend leukemia integration 1 (Fli-1) is an important regulator of megakaryocytic (Mk) differentiation. Here, we demonstrate two novel nuclear localization signals (NLSs) within Fli-1: one (NLS1) is located at the N terminus, and another (NLS2) is within the Ets domain. Nuclear accumulation of Fli-1 reflected the combined functional effects of the two discrete NLSs. Each NLS can independently direct nuclear transport of a carrier protein, with mutations within the NLSs affecting nuclear accumulation. NLS1 has a bipartite motif, whereas the NLS2 region contains a nonclassical NLS. Both NLSs bind importin alpha (IMPalpha) and IMPbeta, with NLS1 and NLS2 being predominantly recognized by IMPalpha and IMPbeta, respectively. Fli-1 also contains one nuclear export signal. Leptomycin B abolished its cytoplasmic accumulation, showing CRM1 dependency. We demonstrate that Ets domain binding to specific target DNA effectively blocks IMP binding, indicating that the targeted DNA binding plays a role in localizing Fli-1 to its destination and releasing IMPs for recycling back to the cytoplasm. Finally, by analyzing full-length Fli-1 carrying NLS1, NLS2, and combined NLS1-NLS2 mutations, we conclude that two functional NLSs exist in Fli-1 and that each NLS is sufficient to target Fli-1 to the nucleus for activation of Mk-specific genes. 相似文献
72.
73.
We have compared the transmission characteristics of the two mouse-adapted scrapie isolates, ME7 and Rocky Mountain Laboratory (RML), in tga20 mice. These mice express elevated levels of PrP protein compared to wild-type mice and display a relatively short disease incubation period following intracerebral prion inoculation. Terminal prion disease in tga20 mice induced by ME7 or RML was characterized by a distinct pattern of clinical signs and different incubation times. High-dose RML inoculated intracerebrally into tga20 mice induced the most rapid onset of clinical signs, with mice succumbing to terminal disease after only 58 +/- 3 days. In contrast, high-dose ME7 gave a mean time to terminal disease of 74 +/- 0 days. Histological examination of brain sections from prion-inoculated tga20 mice at terminal disease showed that ME7 gave rise to a more general and extensive pattern of vacuolation than RML. Low-dose inoculum failed to induce terminal disease but did cause preclinical symptoms, including the appearance of reversible clinical signs. Some mice oscillated between showing no clinical signs and early clinical signs for many months but never progressed to terminal disease. Brain tissue from these mice with chronic subclinical prion disease, sacrificed at >200 days postinoculation, contained high levels of infectivity and showed the presence of PrP(Sc). Parallel analysis of brain tissue from mice with terminal disease showed similar levels of infectivity and detectable PrP(Sc). These results show that high levels of infectivity and the presence of the abnormal isomer of PrP can be detected in mice with subclinical disease following low-dose prion inoculation. 相似文献
74.
Juan P. Quimbayo Vinicius J. Giglio Carlos E. L. Ferreira Alana Fraga José A. C. C. Nunes Thiago C. Mendes 《Journal of fish biology》2020,96(1):74-82
We investigated the feeding rates, agonistic behaviour and diet of two blenny species, Entomacrodus vomerinus and Ophioblennius trinitatis, by direct observation and gut content analysis. Both species coexist in small and shallow tide pools in the St Peter and St Paul's Archipelago, equatorial North Atlantic Ocean. The feeding rate of O. trinitatis was c. 55% higher than E. vomerinus. On the other hand, agonistic rate of O. trinitatis was negatively related to body size, whereas in E. vomerinus was positively related. Both species showed a high diet overlap, in which detritus was the most important food item (86% in O. trinitatis and 80% in E. vomerinus). Feeding activity was more intense during the morning for O. trinitatis but afternoon for E. vomerinus. These behavioural observations support the importance of temporal feeding partitioning as the main strategy allowing species co-existence in tide pools. 相似文献
75.
Claire S. Ting Meghan E. Ramsey Yvette L. Wang Alana M. Frost Esther Jun Timothy Durham 《Photosynthesis research》2009,101(1):1-19
Although Prochlorococcus isolates possess the smallest genomes of any extant photosynthetic organism, this genus numerically dominates vast regions
of the world’s subtropical and tropical open oceans and has evolved to become an important contributor to global biogeochemical
cycles. The sequencing of 12 Prochlorococcus genomes provides a glimpse of the extensive genetic heterogeneity and, thus, physiological potential of the lineage. In this
study, we present an up-to-date comparative analysis of major proteins of the photosynthetic apparatus in 12 Prochlorococcus genomes. Our analyses reveal a striking diversity within the Prochlorococcus lineage in the major protein complexes of the photosynthetic apparatus. The heterogeneity that has evolved in the photosynthetic
apparatus suggests versatility in strategies for optimizing photosynthesis under conditions of environmental variability and
stress. This diversity could be particularly important in ensuring the survival of a lineage whose individuals have evolved
minimal genomes and, thus, relatively limited repertoires for responding to environmental challenges.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
76.
Catherine M. Miller Alana M. Zakrzewski Dionne P. Robinson Stephen J. Fuller Robert A. Walker Rowan J. Ikin Shisan J. Bao Michael E. Grigg James S. Wiley Nicholas C. Smith 《PloS one》2015,10(6)
Background
Oral infection of C57BL/6J mice with the protozoan parasite Toxoplasma gondii leads to a lethal inflammatory ileitis.Principal Findings
Mice lacking the purinergic receptor P2X7R are acutely susceptible to toxoplasmic ileitis, losing significantly more weight than C57BL/6J mice and exhibiting much greater intestinal inflammatory pathology in response to infection with only 10 cysts of T. gondii. This susceptibility is not dependent on the ability of P2X7R-deficient mice to control the parasite, which they accomplish just as efficiently as C57BL/6J mice. Rather, susceptibility is associated with elevated ileal concentrations of pro-inflammatory cytokines, reactive nitrogen intermediates and altered regulation of elements of NFκB activation in P2X7R-deficient mice.Conclusions
Our data support the thesis that P2X7R, a well-documented activator of pro-inflammatory cytokine production, also plays an important role in the regulation of intestinal inflammation. 相似文献77.
In the legal system, inconsistencies in eyewitness accounts are often used to discredit witnesses’ credibility. This is at odds with research findings showing that witnesses frequently report reminiscent details (details previously unrecalled) at an accuracy rate that is nearly as high as for consistently recalled information. The present study sought to put the validity of beliefs about recall consistency to a test by directly comparing them with actual memory performance in two recall attempts. All participants watched a film of a staged theft. Subsequently, the memory group (N = 84) provided one statement immediately after the film (either with the Self-Administered Interview or free recall) and one after a one-week delay. The estimation group (N = 81) consisting of experienced police detectives estimated the recall performance of the memory group. The results showed that actual recall performance was consistently underestimated. Also, a sharp decline of memory performance between recall attempts was assumed by the estimation group whereas actual accuracy remained stable. While reminiscent details were almost as accurate as consistent details, they were estimated to be much less accurate than consistent information and as inaccurate as direct contradictions. The police detectives expressed a great concern that reminiscence was the result of suggestive external influences. In conclusion, it seems that experienced police detectives hold many implicit beliefs about recall consistency that do not correspond with actual recall performance. Recommendations for police trainings are provided. These aim at fostering a differentiated view on eyewitness performance and the inclusion of more comprehensive classes on human memory structure. 相似文献
78.
Catherine X. Moss Elaine Brown Alana Hamilton Pieter Van der Veken Koen Augustyns Jeremy C. Mottram 《PloS one》2015,10(3)
The serine peptidases of Trypanosoma brucei have been viewed as potential drug targets. In particular, the S9 prolyl oligopeptidase subfamily is thought to be a good avenue for drug discovery. This is based on the finding that some S9 peptidases are secreted and active in the mammalian bloodstream, and that they are a class of enzyme against which drugs have successfully been developed. We collated a list of all serine peptidases in T. brucei, identifying 20 serine peptidase genes, of which nine are S9 peptidases. We screened all 20 serine peptidases by RNAi to determine which, if any, are essential for bloodstream form T. brucei survival. All S9 serine peptidases were dispensable for parasite survival in vitro, even when pairs of similar genes, coding for oligopeptidase B or prolyl oligopeptidase, were targeted simultaneously. We also found no effect on parasite survival in an animal host when the S9 peptidases oligopeptidase B, prolyl oligopeptidase or dipeptidyl peptidase 8 were targeted. The only serine peptidase to emerge from the RNAi screen as essential was a putative type-I signal peptide peptidase (SPP1). This gene was essential for parasite survival both in vitro and in vivo. The growth defect conferred by RNAi depletion of SPP1 was rescued by expression of a functional peptidase from an RNAi resistant SPP1 gene. However, expression of catalytically inactive SPP1 was unable to rescue cells from the SPP1 depleted phenotype, demonstrating that SPP1 serine peptidase activity is necessary for T. brucei survival. 相似文献
79.
Geoffrey E. Lynn Jonathan D. Oliver Curtis M. Nelson Roderick F. Felsheim Timothy J. Kurtti Ulrike G. Munderloh 《PloS one》2015,10(3)
Human pathogens transmitted by ticks undergo complex life cycles alternating between the arthropod vector and a mammalian host. While the latter has been investigated to a greater extent, examination of the biological interactions between microbes and the ticks that carry them presents an equally important opportunity for disruption of the disease cycle. In this study, we used in situ hybridization to demonstrate infection by the Ehrlichia muris-like organism, a newly recognized human pathogen, of Ixodes scapularis ticks, a primary vector for several important human disease agents. This allowed us to assess whole sectioned ticks for the patterns of tissue invasion, and demonstrate generalized dissemination of ehrlichiae in a variety of cell types and organs within ticks infected naturally via blood feeding. Electron microscopy was used to confirm these results. Here we describe a strong ehrlichial affinity for epithelial cells, neuronal cells of the synganglion, salivary glands, and male accessory glands. 相似文献
80.
Johanna Useem Alana Brennan Michael LaValley Michelle Vickery Omid Ameli Nichole Reinen Christopher J. Gill 《PloS one》2015,10(12)