920 research outputs found
An analysis of teacher efficacy, resident efficacy, and teacher-student relationships with behaviorally challenged youth in residential treatment settings.
This dissertation contributes to the existing body of research investigating teacher efficacy, collective teacher efficacy, academic efficacy, and teacher-student relationships within residential treatment centers (RTCs) for adolescents. While past RTC research identifies a link between positive resident outcomes and supportive relationships with RTC staff members, no prior studies have investigated this link from the perspective of classroom teachers. Additionally, although specialized trainings strengthen interpersonal relationships between RTC residents and staff members, most are directed toward therapeutic and milieu staff, not teachers. The purpose of this study was threefold: (a) to examine whether teachers\u27 individual and collective perceptions of teaching efficacy improved after a specialized training, (b) to identify whether students\u27 perceptions of student-teacher relationship and academic efficacy improved after teachers received a specialized training, and (c) to examine whether individual and collective teacher efficacy has an association with student academic efficacy and the quality of the teacher-student relationship. One hundred seventy-four (boys N = 81, girls N = 93) adolescents enrolled at two different RTCs participated in this study. Several findings emerged: (a) separate trends in teacher efficacy appeared, teacher efficacy increased among teachers working with girls but decreased among those working with boys, (b) collective teacher efficacy among all teachers decreased after the training, (c) no differences in student academic efficacy occurred over time, (d) no differences in students\u27 perceptions of the student-teacher relationship occurred over time, (e) students whose teachers had lower individual but higher collective efficacy scores had higher student-teacher relationship scores, and (f) student academic efficacy was not related to individual or collective teacher efficacy. This study showed that interactions between teachers and students in R TC settings are complex and multifaceted processes. Many results were inconsistent with prior studies, which have primarily examined students in non-RTC settings. This dissertation further emphasizes the need for continued research with students placed in RTCs. Implications for future research include the design of specialized trainings for RTC teachers, the enhancement of efficacy beliefs among RTC teachers and students, and the impact of gender and attachment traits (among both students and teachers) upon efficacy beliefs and teacher-student relationships
Differential lipid dependence of function of bacterial sodium channel homologues
The lipid bilayer is important for maintaining the integrity of cellular compartments and plays a vital role in maintaining the hydrophobic/charged interactions necessary for structure, conformational flexibility and function. Despite the intimate relationship between ion channels and the membranes in which they are embedded, challenges resulting from the dynamic and complex nature of cellular membranes have limited our ability to address the functional role of these interactions. To directly assess lipid dependence of activity, we examined channel function ofthree purified bacterial sodium channel orthologues (NaChBac, NavMs, and NavSp) by cumulative 22Na+ uptake into proteoliposomes containing a 3:1 ratio of POPE and another glycerophospholipid (POPC, POPG, POPS, Cardiolipin (CL), POPA, or PI). We observed a unique lipid dependence for each homologue tested. Common to each was a low level of activity above background (uptake into protein free liposomes) when the second lipid was a zwitterionic lipid such as POPE and POPC. Maximal activity for full-length NaChBac and NavMs proteins was observed in POPE + POPG liposomes. On the other hand, full-length NavSp channels possessed a different lipid dependence, with maximal activity in liposomes containing POPE + PI. No strong lipid dependence was observed for pore-only constructs of NavMs or NavSp, that lacked the S1-S4 segments, suggesting that the lipid dependence of sodium channels may arise from their abilities to affect the voltage-sensing domains. The effect may be maximized by specific lipid-protein interactions that are uniquely favourable in each homologue, giving rise to differing lipid dependences
RIGHT TO LEFT VENTRICULAR APICAL CONTRACTION INTERVAL–A NEW INDEX OF VENTRICULAR DYSSYNCHRONY DERIVED FROM SPECT GATED BLOOD POOL RADIONUCLIDE VENTRICULOGRAPHY
Adaptation of the Timeline Followback: A Self-administered Tool for Identifying Sexual Violence Perpetration
Sit-to-Stand Symmetry
Asymmetric sit-to-stand (STS) and static standing mechanics may be related to fall risk and function after hip fracture. Even in those individuals who achieve an independent status in rising from STS, asymmetric movement strategies are frequently adopted. Previous research has revealed that the asymmetry is not fully explained by strength deficits alone. Stroke literature suggests that STS asymmetry is a function of perceptual deficits, such as sense of effort, however, this concept has not yet been explored following a hip fracture
The Mechanism of Flexible Controlling as an Innovative Method in Management of Corporate Structures
Π£ ΡΡΠ°ΡΡΡ ΠΏΡΠ΅Π΄ΡΡΠ°Π²Π»Π΅Π½ΠΈΠΉ ΠΏΡΠΈΠ½ΡΠΈΠΏ Π΄ΡΡ ΠΌΠ΅Ρ
Π°Π½ΡΠ·ΠΌΡ Π³Π½ΡΡΠΊΠΎΠ³ΠΎ ΠΊΠΎΠ½ΡΡΠΎΠ»ΡΠ½Π³Ρ ΡΠΊ ΡΠ½Π½ΠΎΠ²Π°ΡΡΠΉΠ½ΠΎΠ³ΠΎ ΠΌΠ΅ΡΠΎΠ΄Ρ
ΡΠΏΡΠ°Π²Π»ΡΠ½Π½Ρ ΠΊΠΎΡΠΏΠΎΡΠ°ΡΠΈΠ²Π½ΠΈΠΌΠΈ ΡΡΡΡΠΊΡΡΡΠ°ΠΌΠΈ. Π ΠΎΠ·Π³Π»ΡΠ½ΡΡΠΎ ΠΏΡΠΈΠ½ΡΠΈΠΏΠΈ Π·Π°ΡΡΠΎΡΡΠ²Π°Π½Π½Ρ Π΄Π°Π½ΠΎΠ³ΠΎ ΠΌΠ΅ΡΠΎΠ΄Ρ ΡΠΊ
ΡΠ½ΡΡΡΡΠΌΠ΅Π½ΡΡ Π΅ΡΠ΅ΠΊΡΠΈΠ²Π½ΠΎΠ³ΠΎ ΡΠΏΡΠ°Π²Π»ΡΠ½Π½Ρ ΠΊΠΎΡΠΏΠΎΡΠ°ΡΠΈΠ²Π½ΠΈΠΌΠΈ ΡΡΡΡΠΊΡΡΡΠ°ΠΌΠΈ, ΡΠΎ Π΄ΠΎΠ·Π²ΠΎΠ»ΡΡΡΡ Π·Π°Π±Π΅Π·ΠΏΠ΅ΡΠΈΡΠΈ
ΡΡΠ·Π½ΠΎΠΌΠ°Π½ΡΡΠ½ΡΡΡΡ Ρ Π³Π½ΡΡΠΊΡΡΡΡ ΠΏΡΠΎΡΠ΅ΡΡΠ² ΡΠΏΡΠ°Π²Π»ΡΠ½Π½Ρ Π΄Π»Ρ Π΄ΠΎΡΡΠ³Π½Π΅Π½Π½Ρ ΠΏΠΎΡΡΠ°Π²Π»Π΅Π½ΠΈΡ
ΡΡΠ»Π΅ΠΉ. Π ΠΎΠ·Π³Π»ΡΠ½ΡΡΠΎ
ΠΎΡΠΎΠ±Π»ΠΈΠ²ΠΎΡΡΡ ΠΊΠΎΠ½ΡΡΠΎΠ»ΡΠ½Π³Ρ Π² ΡΠΏΡΠ°Π²Π»ΡΠ½Π½Ρ ΠΊΠΎΡΠΏΠΎΡΠ°ΡΠΈΠ²Π½ΠΈΠΌΠΈ ΡΡΡΡΠΊΡΡΡΠ°ΠΌΠΈ Π² ΡΠΌΠΎΠ²Π°Ρ
Π½Π΅ΡΡΠ°Π±ΡΠ»ΡΠ½ΠΎΠ³ΠΎ
Π΅ΠΊΠΎΠ½ΠΎΠΌΡΡΠ½ΠΎΠ³ΠΎ ΡΠ΅ΡΠ΅Π΄ΠΎΠ²ΠΈΡΠ°. ΠΠΎΠ΄Π°Π½ΠΎ ΠΊΠΎΠ½ΡΠ΅ΠΏΡΡΡ ΠΌΠ΅Ρ
Π°Π½ΡΠ·ΠΌΡ ΠΊΠΎΠ½ΡΡΠΎΠ»ΡΠ½Π³Ρ Π² ΡΠΏΡΠ°Π²Π»ΡΠ½Π½Ρ
ΠΊΠΎΡΠΏΠΎΡΠ°ΡΠΈΠ²Π½ΠΈΠΌΠΈ ΡΡΡΡΠΊΡΡΡΠ°ΠΌΠΈ, ΡΠΊΠ° Π΄ΠΎΠ·Π²ΠΎΠ»ΡΡ Π·Π°Π±Π΅Π·ΠΏΠ΅ΡΠΈΡΠΈ Π½Π΅ΠΎΠ±Ρ
ΡΠ΄Π½Ρ ΡΡΠ·Π½ΠΎΠΌΠ°Π½ΡΡΠ½ΡΡΡΡ ΠΏΡΠΎΡΠ΅ΡΡΠ²
ΡΠΏΡΠ°Π²Π»ΡΠ½Π½Ρ Π΄Π»Ρ Π΄ΠΎΡΡΠ³Π½Π΅Π½Π½Ρ Π΄ΠΈΠ½Π°ΠΌΡΡΠ½ΠΎΠ³ΠΎ ΠΊΠΎΠΌΠΏΠ»Π΅ΠΊΡΡ ΡΡΠ»Π΅ΠΉ. Π ΠΎΠ·Π³Π»ΡΠ½ΡΡΠΎ ΠΎΡΠΎΠ±Π»ΠΈΠ²ΠΎΡΡΡ
ΡΡΠ½ΠΊΡΡΠΎΠ½ΡΠ²Π°Π½Π½Ρ ΠΊΠΎΡΠΏΠΎΡΠ°ΡΠΈΠ²Π½ΠΈΡ
ΡΡΡΡΠΊΡΡΡ Ρ Π½Π΅ΡΡΠ°Π±ΡΠ»ΡΠ½ΠΎΠΌΡ ΡΠΈΠ½ΠΊΠΎΠ²ΠΎΠΌΡ ΠΎΡΠΎΡΠ΅Π½Π½Ρ. ΠΠ° ΠΏΡΠΈΠΊΠ»Π°Π΄Ρ
ΠΌΠ΅Ρ
Π°Π½ΡΠ·ΠΌΡ Π³Π½ΡΡΠΊΠΎΠ³ΠΎ ΠΊΠΎΠ½ΡΡΠΎΠ»ΡΠ½Π³Ρ ΡΠΊ ΡΠΏΠΎΡΠΎΠ±Ρ Π°Π΄Π°ΠΏΡΠ°ΡΡΡ Π΄ΠΎ ΡΠ΅Π°Π»ΡΠΉ ΡΡΠΎΡΠΌΠΎΠ²Π°Π½ΠΎΡ Π½Π΅ΡΡΠ°Π±ΡΠ»ΡΠ½ΠΎΡΡΡ Π²
Π΅ΠΊΠΎΠ½ΠΎΠΌΡΡΡ Π£ΠΊΡΠ°ΡΠ½ΠΈ ΠΏΡΠ΅Π΄ΡΡΠ°Π²Π»Π΅Π½Π° ΠΉΠΎΠ³ΠΎ Π·Π΄Π°ΡΠ½ΡΡΡΡ ΠΎΠΏΠ΅ΡΠ°ΡΠΈΠ²Π½ΠΎ Ρ ΡΠΎΠ½ΠΊΠΎ ΡΠΏΡΡΠΌΠΎΠ²ΡΠ²Π°ΡΠΈ ΡΠΏΡΠ°Π²Π»ΡΠ½Π½Ρ
ΠΊΠΎΡΠΏΠΎΡΠ°ΡΠΈΠ²Π½ΠΈΠΌΠΈ ΡΡΡΡΠΊΡΡΡΠ°ΠΌΠΈ Π΄Π»Ρ ΠΏΡΠΈΠΉΠ½ΡΡΡΡ ΠΏΡΠ°Π²ΠΈΠ»ΡΠ½ΠΈΡ
ΡΡΡΠ΅Π½Ρ ΡΠ° ΠΏΠΎΠ³ΠΎΠ΄ΠΆΠ΅Π½Π½Ρ ΡΠΎΠ±ΠΎΡΠΈ Π²ΡΡΡ
ΠΏΡΠ΄ΡΠΈΡΡΠ΅ΠΌ ΠΏΡΠ΄ΠΏΡΠΈΡΠΌΡΡΠ²Π°.Π ΡΡΠ°ΡΡΠ΅ ΠΏΡΠ΅Π΄ΡΡΠ°Π²Π»Π΅Π½ ΠΏΡΠΈΠ½ΡΠΈΠΏ Π΄Π΅ΠΉΡΡΠ²ΠΈΡ ΠΌΠ΅Ρ
Π°Π½ΠΈΠ·ΠΌΠ° Π³ΠΈΠ±ΠΊΠΎΠ³ΠΎ ΠΊΠΎΠ½ΡΡΠΎΠ»Π»ΠΈΠ½Π³Π° ΠΊΠ°ΠΊ
ΠΈΠ½Π½ΠΎΠ²Π°ΡΠΈΠΎΠ½Π½ΠΎΠ³ΠΎ ΠΌΠ΅ΡΠΎΠ΄Π° ΡΠΏΡΠ°Π²Π»Π΅Π½ΠΈΡ ΠΊΠΎΡΠΏΠΎΡΠ°ΡΠΈΠ²Π½ΡΠΌΠΈ ΡΡΡΡΠΊΡΡΡΠ°ΠΌΠΈ. Π Π°ΡΡΠΌΠΎΡΡΠ΅Π½Ρ ΠΏΡΠΈΠ½ΡΠΈΠΏΡ
ΠΏΡΠΈΠΌΠ΅Π½Π΅Π½ΠΈΡ Π΄Π°Π½Π½ΠΎΠ³ΠΎ ΠΌΠ΅ΡΠΎΠ΄Π° ΠΊΠ°ΠΊ ΠΈΠ½ΡΡΡΡΠΌΠ΅Π½ΡΠ° ΡΡΡΠ΅ΠΊΡΠΈΠ²Π½ΠΎΠ³ΠΎ ΡΠΏΡΠ°Π²Π»Π΅Π½ΠΈΡ ΠΊΠΎΡΠΏΠΎΡΠ°ΡΠΈΠ²Π½ΡΠΌΠΈ
ΡΡΡΡΠΊΡΡΡΠ°ΠΌΠΈ, ΠΏΠΎΠ·Π²ΠΎΠ»ΡΡΡΠΈΠ΅ ΠΎΠ±Π΅ΡΠΏΠ΅ΡΠΈΡΡ ΡΠ°Π·Π½ΠΎΠΎΠ±ΡΠ°Π·ΠΈΠ΅ ΠΈ Π³ΠΈΠ±ΠΊΠΎΡΡΡ ΠΏΡΠΎΡΠ΅ΡΡΠΎΠ² ΡΠΏΡΠ°Π²Π»Π΅Π½ΠΈΡ Π΄Π»Ρ
Π΄ΠΎΡΡΠΈΠΆΠ΅Π½ΠΈΡ ΠΏΠΎΡΡΠ°Π²Π»Π΅Π½Π½ΡΡ
ΡΠ΅Π»Π΅ΠΉ. Π Π°ΡΡΠΌΠΎΡΡΠ΅Π½Ρ ΠΎΡΠΎΠ±Π΅Π½Π½ΠΎΡΡΠΈ ΠΊΠΎΠ½ΡΡΠΎΠ»Π»ΠΈΠ½Π³Π° Π² ΡΠΏΡΠ°Π²Π»Π΅Π½ΠΈΠΈ
ΠΊΠΎΡΠΏΠΎΡΠ°ΡΠΈΠ²Π½ΡΠΌΠΈ ΡΡΡΡΠΊΡΡΡΠ°ΠΌΠΈ Π² ΡΡΠ»ΠΎΠ²ΠΈΡΡ
Π½Π΅ΡΡΠ°Π±ΠΈΠ»ΡΠ½ΠΎΠΉ ΡΠΊΠΎΠ½ΠΎΠΌΠΈΡΠ΅ΡΠΊΠΎΠΉ ΡΡΠ΅Π΄Ρ. ΠΡΠ΅Π΄ΡΡΠ°Π²Π»Π΅Π½Π°
ΠΊΠΎΠ½ΡΠ΅ΠΏΡΠΈΡ ΠΌΠ΅Ρ
Π°Π½ΠΈΠ·ΠΌΠ° ΠΊΠΎΠ½ΡΡΠΎΠ»Π»ΠΈΠ½Π³Π° Π² ΡΠΏΡΠ°Π²Π»Π΅Π½ΠΈΠΈ ΠΊΠΎΡΠΏΠΎΡΠ°ΡΠΈΠ²Π½ΡΠΌΠΈ ΡΡΡΡΠΊΡΡΡΠ°ΠΌΠΈ, ΠΊΠΎΡΠΎΡΠ°Ρ
ΠΏΠΎΠ·Π²ΠΎΠ»ΡΠ΅Ρ ΠΎΠ±Π΅ΡΠΏΠ΅ΡΠΈΡΡ Π½Π΅ΠΎΠ±Ρ
ΠΎΠ΄ΠΈΠΌΠΎΠ΅ ΡΠ°Π·Π½ΠΎΠΎΠ±ΡΠ°Π·ΠΈΠ΅ ΠΏΡΠΎΡΠ΅ΡΡΠΎΠ² ΡΠΏΡΠ°Π²Π»Π΅Π½ΠΈΡ Π΄Π»Ρ Π΄ΠΎΡΡΠΈΠΆΠ΅Π½ΠΈΡ
Π΄ΠΈΠ½Π°ΠΌΠΈΡΠ΅ΡΠΊΠΎΠ³ΠΎ ΠΊΠΎΠΌΠΏΠ»Π΅ΠΊΡΠ° ΡΠ΅Π»Π΅ΠΉ. Π Π°ΡΡΠΌΠΎΡΡΠ΅Π½Ρ ΠΎΡΠΎΠ±Π΅Π½Π½ΠΎΡΡΠΈ ΡΡΠ½ΠΊΡΠΈΠΎΠ½ΠΈΡΠΎΠ²Π°Π½ΠΈΡ ΠΊΠΎΡΠΏΠΎΡΠ°ΡΠΈΠ²Π½ΡΡ
ΡΡΡΡΠΊΡΡΡ Π² Π½Π΅ΡΡΠ°Π±ΠΈΠ»ΡΠ½ΠΎΠΌ ΡΡΠ½ΠΎΡΠ½ΠΎΠΌ ΠΎΠΊΡΡΠΆΠ΅Π½ΠΈΠΈ. ΠΠ° ΠΏΡΠΈΠΌΠ΅ΡΠ΅ ΠΌΠ΅Ρ
Π°Π½ΠΈΠ·ΠΌΠ° Π³ΠΈΠ±ΠΊΠΎΠ³ΠΎ ΠΊΠΎΠ½ΡΡΠΎΠ»Π»ΠΈΠ½Π³Π° ΠΊΠ°ΠΊ
ΡΠΏΠΎΡΠΎΠ±Π° Π°Π΄Π°ΠΏΡΠ°ΡΠΈΠΈ ΠΊ ΡΠ΅Π°Π»ΠΈΡΠΌ ΡΠ»ΠΎΠΆΠΈΠ²ΡΠ΅ΠΉΡΡ Π½Π΅ΡΡΠ°Π±ΠΈΠ»ΡΠ½ΠΎΡΡΠΈ Π² ΡΠΊΠΎΠ½ΠΎΠΌΠΈΠΊΠ΅ Π£ΠΊΡΠ°ΠΈΠ½Ρ ΠΏΡΠ΅Π΄ΡΡΠ°Π²Π»Π΅Π½Π°
Π΅Π³ΠΎ ΡΠΏΠΎΡΠΎΠ±Π½ΠΎΡΡΡ ΠΎΠΏΠ΅ΡΠ°ΡΠΈΠ²Π½ΠΎ ΠΈ ΡΠΎΠ½ΠΊΠΎ Π½Π°ΠΏΡΠ°Π²Π»ΡΡΡ ΡΠΏΡΠ°Π²Π»Π΅Π½ΠΈΠ΅ ΠΊΠΎΡΠΏΠΎΡΠ°ΡΠΈΠ²Π½ΡΠΌΠΈ ΡΡΡΡΠΊΡΡΡΠ°ΠΌΠΈ Π΄Π»Ρ
ΠΏΡΠΈΠ½ΡΡΠΈΡ ΠΏΡΠ°Π²ΠΈΠ»ΡΠ½ΡΡ
ΡΠ΅ΡΠ΅Π½ΠΈΠΉ ΠΈ ΡΠΎΠ³Π»Π°ΡΠΎΠ²Π°Π½ΠΈΡ ΡΠ°Π±ΠΎΡΡ Π²ΡΠ΅Ρ
ΠΏΠΎΠ΄ΡΠΈΡΡΠ΅ΠΌ ΠΏΡΠ΅Π΄ΠΏΡΠΈΡΡΠΈΡ.This article presents the principle of the mechanism controlling the flexible as an innovative method
of managing corporate structures. The principles of this method as a tool for the effective management of
corporate structures, allowing for variety and flexibility of management processes to achieve their goals.
Features of controlling in management of corporate structures in the conditions of the unstable economic
environment are considered. The concept of the mechanism of controlling in management of corporate
structures which allows to provide a necessary variety of management processes for achievement of a
dynamic complex of the purposes is presented. Features of functioning of corporate structures in an
unstable market environment are considered. On the example of controlling a flexible mechanism as a
way of adapting to the realities of the current instability in the economy of Ukraine, represented by its
ability to quickly and subtly direct the management of the corporate structure to make the right decisions
and coordination of all sub-systems of the enterprise
Human cytomegalovirus protein pUL36: A dual cell death pathway inhibitor.
Human cytomegalovirus (HCMV) is an important human pathogen and a paradigm of intrinsic, innate, and adaptive viral immune evasion. Here, we employed multiplexed tandem mass tag-based proteomics to characterize host proteins targeted for degradation late during HCMV infection. This approach revealed that mixed lineage kinase domain-like protein (MLKL), a key terminal mediator of cellular necroptosis, was rapidly and persistently degraded by the minimally passaged HCMV strain Merlin but not the extensively passaged strain AD169. The strain Merlin viral inhibitor of apoptosis pUL36 was necessary and sufficient both to degrade MLKL and to inhibit necroptosis. Furthermore, mutation of pUL36 Cys131 abrogated MLKL degradation and restored necroptosis. As the same residue is also required for pUL36-mediated inhibition of apoptosis by preventing proteolytic activation of procaspase-8, we define pUL36 as a multifunctional inhibitor of both apoptotic and necroptotic cell death
The Goldberg Variations 1: Assessing the academic quality of multidimensional linear texts and their re-emergence in multimedia publications
Interaction of Cryptococcus neoformans Rim101 and Protein Kinase A Regulates Capsule
Cryptococcus neoformans is a prevalent human fungal pathogen that must survive within various tissues in order to establish a human infection. We have identified the C. neoformans Rim101 transcription factor, a highly conserved pH-response regulator in many fungal species. The rim101Ξ mutant strain displays growth defects similar to other fungal species in the presence of alkaline pH, increased salt concentrations, and iron limitation. However, the rim101Ξ strain is also characterized by a striking defect in capsule, an important virulence-associated phenotype. This capsular defect is likely due to alterations in polysaccharide attachment to the cell surface, not in polysaccharide biosynthesis. In contrast to many other C. neoformans capsule-defective strains, the rim101Ξ mutant is hypervirulent in animal models of cryptococcosis. Whereas Rim101 activation in other fungal species occurs through the conserved Rim pathway, we demonstrate that C. neoformans Rim101 is also activated by the cAMP/PKA pathway. We report here that C. neoformans uses PKA and the Rim pathway to regulate the localization, activation, and processing of the Rim101 transcription factor. We also demonstrate specific host-relevant activating conditions for Rim101 cleavage, showing that C. neoformans has co-opted conserved signaling pathways to respond to the specific niche within the infected host. These results establish a novel mechanism for Rim101 activation and the integration of two conserved signaling cascades in response to host environmental conditions
Analysis of the giant genomes of Fritillaria (Liliaceae) indicates that a lack of DNA removal characterizes extreme expansions in genome size.
This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.Plants exhibit an extraordinary range of genome sizes, varying by >Β 2000-fold between the smallest and largest recorded values. In the absence of polyploidy, changes in the amount of repetitive DNA (transposable elements and tandem repeats) are primarily responsible for genome size differences between species. However, there is ongoing debate regarding the relative importance of amplification of repetitive DNA versus its deletion in governing genome size. Using data from 454 sequencing, we analysed the most repetitive fraction of some of the largest known genomes for diploid plant species, from members of Fritillaria. We revealed that genomic expansion has not resulted from the recent massive amplification of just a handful of repeat families, as shown in species with smaller genomes. Instead, the bulk of these immense genomes is composed of highly heterogeneous, relatively low-abundance repeat-derived DNA, supporting a scenario where amplified repeats continually accumulate due to infrequent DNA removal. Our results indicate that a lack of deletion and low turnover of repetitive DNA are major contributors to the evolution of extremely large genomes and show that their size cannot simply be accounted for by the activity of a small number of high-abundance repeat families.Thiswork was supported by the Natural Environment ResearchCouncil (grant no. NE/G017 24/1), the Czech Science Fou nda-tion (grant no. P501/12/G090), the AVCR (grant no.RVO:60077344) and a Beatriu de Pinos postdoctoral fellowshipto J.P. (grant no. 2011-A-00292; Catalan Government-E.U. 7thF.P.)
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