Negative Fragment Research Articles

Forest Fragmentation and Seed Germination of Native Species from the Chaco Serrano Forest

Habitat fragmentation is a widespread phenomenon that alters pollination and plant reproductive processes. These effects have demographic and genetic implications that determine offspring fitness and the long-term viability of plant populations in fragmented systems. We evaluated fragmentation effects on early plant offspring fitness traits, individual seed mass, and percentage of seed germination in five native plant species (Acacia caven, Celtis ehrenbergiana, Croton lachnostachyus, Rivina humilis, Schinus fasciculatus) from the Chaco Serrano forest, a subtropical highly fragmented ecosystem. We found evidence of strong negative fragmentation effects on germination in the shrub C. lachnostachyus and the perennial herb R. humilis, after 30 d of controlled tests. No fragmentation effects were found in the studied traits on the remaining three tree species. We found significant maternal effects in offspring fitness traits in all five species. We discuss the relative magnitude of maternal vs. fragmentation effects taking into account both plant species' lifespan and the time elapsed in fragmentation conditions. We emphasize the need to increase the study of early and late plant offspring fitness produced in fragmented habitats coupled with analyses of genetic parameters and the pollination process in order to evaluate the conservation value of remnant forest fragments. Abstract in Spanish is available at http://www.blackwell-synergy.com/loi/btp.

Admissible rules in the implication–negation fragment of intuitionistic logic

Uniform infinite bases are defined for the single-conclusion and multiple-conclusion admissible rules of the implication–negation fragments of intuitionistic logic IPC and its consistent axiomatic extensions (intermediate logics). A Kripke semantics characterization is given for the (hereditarily) structurally complete implication–negation fragments of intermediate logics, and it is shown that the admissible rules of this fragment of IPC form a PSPACE-complete set and have no finite basis.

Peroxisomes in zebrafish: distribution pattern and knockdown studies

Peroxisomes are organelles that are essential for normal development in men and mice. In order to explore whether zebrafish could be used as a model system to study the role of peroxisomes, we examined their distribution pattern in developing and adult zebrafish and we tested different approaches to eliminate them during the first days after fertilization. In 4-day-old embryos, catalase-containing peroxisomes were obvious in the liver, the pronephric duct and the wall of the yolk sac, but transcripts for peroxisomal matrix and membrane proteins were also detected in the head region from 24 h post-fertilization. In adult zebrafish, catalase-containing peroxisomes remained prominent in the hepatocytes, the renal proximal tubules and the intestinal epithelium. Several peroxins, essential proteins for the biogenesis of peroxisomes, were targeted using knockdown approaches. Two morpholinos, blocking, respectively, splice sites in pex3 and pex13, only induced a short in frame deletion or insertion in the transcripts and did not result in the elimination of peroxisomes after injection into one-cell embryos. A morpholino blocking translation of pex13 was able to reduce the number of peroxisomes to variable extents. Finally, overexpression of a potential dominant negative fragment of Pex3p did not result in deletion of peroxisomes from developing zebrafish. We conclude that in zebrafish (1) peroxisomes, as visualized by DAB cytochemistry for catalase activity, are most conspicuous in the liver and renal tubular epithelium; this pattern is reminiscent of peroxisome occurrence in mammalian organs, (2) our approaches to eliminate these organelles during development by targeting peroxins were not successful.

Dissociation of gaseous zwitterion glycine-betaine by slow electrons

In this work, we investigate dissociation processes induced by low-energy electrons to gas phase N,N,N-trimethylglycine [glycine-betaine, (CH(3))(3)N(+)CH(2)COO(-)] molecules. Glycine-betaine represents a model system for zwitterions. All negative fragments are observed to be produced only at subelectronic excitation energies (<4 eV). With the exception of the loss of a neutral H atom that could arise from any C[Single Bond]H bond breaking, we tentatively suggest that the zwitterion dissociates exclusively from the fragmentation of the cation site of the molecule, subsequent to the attachment of the excess electron. Within the context of radiation induced damage to biological systems, the present findings contribute to a more complete description of the fragmentation mechanism occurring to amino acids, peptides, and proteins since they adopt usually a zwitterion structure.

Conservation Genetics of the Endemic Mexican Heliconia uxpanapensis in the Los Tuxtlas Tropical Rain Forest

ABSTRACT Heliconia uxpanapensis (Heliconiaceae) is an outcrossing endemic herb that grows within continuous and fragmented areas of the tropical rain forest of southeastVeracru ´z (Mexico). The genetic diversity, population differentiation, and genetic structure of seven populations of the studied species were assessed using inter-simplesequence repeat) markers. Population differentiation was moderately high (F ST range: 0.18–0.22) and indirect estimates of gene flow were rather low(Nm=0.65–0.83). Analysis of molecular variance indicated that the populations explained 22.2 percent of the variation, while individuals within the populationsaccounted for 77.8 percent. The similar and high level of genetic diversity found within populations of the continuous and fragmented forest suggests that H. uxp-anapensis has not suffered yet the expected negative effect of fragmentation. Genetic structure analyses indicated the presence of fewer genetic clusters (K=4) thanpopulations (N=7). Three of the four fragmented forest populations were assigned each to one of the clusters found within the continuous forest, suggesting theabsence of a negative fragmentation effect on the amount and distribution of genetic variation. Given the significant genetic structure combined with high geneticdiversity and low levels of gene flow, theoretical simulations indicated that H. uxpanapensis might be highly susceptible to changes in the mating system, whichpromotes inbreeding within fragmented populations. Thus, future conservation efforts in this species should be directed to ensure that levels of gene flow amongpopulations are sufficient to prevent an increment in the magnitude of inbreeding within fragments.Abstract in Spanish is available at http://www.blackwell-synergy.com/loi/btp.Key words: fragmentation; F-statistics; ISSR.

Stereoselective epoxidation of the last double bond of polyunsaturated fatty acids by human cytochromes P450

Cytochromes P450 (CYPs) metabolize polyunsaturated long-chain fatty acids (PUFA-LC) to several classes of oxygenated metabolites. Through use of human recombinant CYPs, we recently showed that CYP1A1, -2C19, -2D6, -2E1, and -3A4 are mainly hydroxylases, whereas CYP1A2, -2C8, -2C9, and -2J2 are mainly epoxygenases of arachidonic acid (AA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA), respectively. It is worth noting that the last double bond of these PUFAs, i.e., omega6 in AA or omega3 in EPA and DHA, respectively, was preferentially epoxidized. In this study, we have characterized the stereoselectivity of this epoxidation reaction by comparison with the PUFA-LC epoxide stereoisomers obtained from the enantioselective bacterial CYP102A1 F87V. The stereoselectivity of the epoxidation of the last olefin of AA (omega6), EPA (omega3), or DHA (omega3) differed between the CYP isoforms but was similar for EPA and DHA. These data give additional insight into the PUFA-LC epoxide enantiomers generated by the hepatic CYPs.

Abstract 3489: Profound cytotoxicity of the histone deacetylase inhibitor SAHA (Suberoylanilide Hydroxamic Acid) and TRAIL (Tumor Necrosis Factor-Related Apoptosis-Inducing Ligand) combination in malignant pleural mesothelioma

Abstract Background: The majority of solid malignancies including malignant pleural mesothelioma (MPM) are refractory to TRAIL-mediated cytotoxicity. SAHA has mild antitumor activity against MPM in a phase I clinical trial. This study is designed to evaluate the cytotoxicity of the SAHA+TRAIL combination on a panel of 10 MPM cells and two normal cells (primary fibroblasts and endothelial cells). Material and methods: Cytotoxicity and apoptosis mediated by TRAIL (0 - 100 ng/ml), SAHA (0.5 - 5.0 microM) or concurrent SAHA+TRAIL combinations are evaluated by MTT assay and AnnexinV-FITC. NF-kB transcriptional activity is measured by luciferase-based reporter plasmid and lucinometer. Results: MPM cells exhibit a wide range of intrinsic susceptibility to TRAIL (2/10 sensitive: IC50 &amp;lt;50 ng/ml, 5/10 mildly sensitive: IC50: 150 to 2500 ng/ml, 3/10 resistant: IC50: infinity). Profound enhancement of cytotoxicity is observed following treatment with SAHA+TRAIL combinations in 7 MPM cells that exhibit some degrees of TRAIL sensitivity as indicated by 2-fold to &amp;gt;100-fold reduction of TRAIL IC50's. TRAIL-refractory cells H2373, Gats and H2052 are resistant to SAHA+TRAIL combinations. Supra-additive induction of treatment-specific apoptosis is observed in representative Gard and H513 MPM cells treated with this combination (Gard: TRAIL(20ng/ml): 18±5%, SAHA (1 microM): 3±2%, SAHA+TRAIL: 68±5%; H513: TRAIL: 30±5%, SAHA: 2±2%; SAHA+TRAIL: 80±4%, n=3). Combination-induced cytotoxicity and apoptosis is equally abrogated by either selective caspase 8 or caspase 9 inhibitor and thus implicating the essential role of the mitochondria-driven death signaling cascade. SAHA-dependent strong activation of NF-kB is completely abrogated by TRAIL and this is paralleled with caspase 8-mediated cleavage of RIP (receptor-interacting protein) to form the NF-kB dominant negative cRIP fragment in combination-treated cells. Induction of mild TRAIL sensitivity by the SMAC-mimetic drug SM164 in TRAIL-resistant cells H2373 or Gats greatly sensitizes them to SAHA+TRAIL cytotoxic effects. Most importantly, SAHA+TRAIL combinations with or without SM164 are not toxic to normal cells. Conclusion: SAHA+TRAIL combination induces profound cytotocidal effect in MPM cells that is dependent on intrinsic death signaling pathway, RIP processing and modulation of NF-kB transcriptional activity. Ongoing investigations are undertaken to further elucidate the molecular basis of this salutary drug combination effects and to develop molecular strategy aiming at promoting SAHA+TRAIL cytotoxicity in TRAIL-resistant MPM cells. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 3489.

Design of improved polymerase chain reaction (PCR) method containing internal positive control (IPC) for molecular detection of Yersinia pestis

Background: Plague is one of the three epidemic diseases still subject to the international health regulation and notifiable to the WHO. Yersinia pestis, the causative agent of plague in natural foci transmitted between rodent and human via wild rodent fleas. So set up of suitable and sure to surveillance and prevention of the disease is necessary. The molecular methods such as polymerase chaine reaction (PCR) has allowed improvement of detection methods currently used in laboratories, although not all of these methods include an Internal Positive Control (IPC) to monitor for false negative results. Therefore we improved a uniplex and multiplex PCR method with lower of limit of detection. Methods: PCR reactions performed with primers which targeted of the caf1 and pla genes located on the pFra and pPst plasmids and the irp2 chromosomal gene located on the ‘pathogenicity island. For acquired different size of these genes aditional primers were designed. In each gene two parts required were ligated.The limit of detection determined by performing PCR reactions on serial dilutions of plasmids containing the coresponding inserts.for evaluating the specificity, PCR reactions were done for negative control bacteria. Results: Assays were performed with genome of Y. pestis which produced three DNA fragments of the expected size 300, 400 and 520 base pairs (bp) corresponding to irp2, caf1 and pla genes respectively. also, for IPC by the same primers the different fragment of the expected size 150, 500 and 300 base pairs (bp) corresponding to irp2, caf1 and pla genes respectively were acquired. With The lower limit of detection was 370 copy numbers for caf1 gene and 21 for pla gene. In PCR reactions for negative control bacteria detectable fragments were not observed. Conclusion: Our method clearly discriminated Y. pestis DNA bacteria which were tested. The rapidity, specificity and sensitivity of this procedure with the use of IPC to monitor for false negative results can make this method suitable for diagnosis and suggest that it can serve as a useful alternative method for inoculation of laboratory animals or the use of specific culture media for routine plaque surveillance and outbreak investigations. Abstracts for SupplementInternational Journal of Infectious DiseasesVol. 14Preview Full-Text PDF Open Archive

Identification of N-glycans from Ebola virus glycoproteins by matrix-assisted laser desorption/ionisation time-of-flight and negative ion electrospray tandem mass spectrometry.

The larger fragment of the transmembrane glycoprotein (GP1) and the soluble glycoprotein (sGP) of Ebola virus were expressed in human embryonic kidney cells and the secreted products were purified from the supernatant for carbohydrate analysis. The N-glycans were released with PNGase F from within sodium dodecyl sulphate/polyacrylamide gel electrophoresis (SDS-PAGE) gels. Identification of the glycans was made with normal-phase high-performance liquid chromatography (HPLC), matrix-assisted laser desorption/ionisation mass spectrometry, negative ion electrospray ionisation fragmentation mass spectrometry and exoglycosidase digestion. Most glycans were complex bi-, tri- and tetra-antennary compounds with reduced amounts of galactose. No bisected compounds were detected. Triantennary glycans were branched on the 6-antenna; fucose was attached to the core GlcNAc residue. Sialylated glycans were present on sGP but were largely absent from GP1, the larger fragment of the transmembrane glycoprotein. Consistent with this was the generally higher level of processing of carbohydrates found on sGP as evidenced by a higher percentage of galactose and lower levels of high-mannose glycans than were found on GP1. These results confirm and expand previous findings on partial characterisation of the Ebola virus transmembrane glycoprotein. They represent the first detailed data on carbohydrate structures of the Ebola virus sGP.

Crossed-beam studies of electron transfer to oriented trichloronitromethane, CCl3NO2, molecules

Fast potassium atoms donate an electron to CCl(3)NO(2) molecules to form K(+) ions and the negative ions O(-), Cl(-), NO(2) (-), CCl(3) (-), CCl(2)NO(2) (-), CCl(3)NO(-), and CCl(3)NO(2) (-). Threshold energies are measured for these ions and electron affinities for CCl(2)NO(2) (-), CCl(3)NO(-), and CCl(3)NO(2) (-) are estimated to be 2.35, 2.35, and 1.89 eV (+/-0.6 eV), respectively. The threshold energies show that the C-N and N-O bonds are substantially weaker than in nitromethane. The CCl(3)NO(2) molecules are oriented before the collision and at energies near 2.5 eV the electron appears to transfer to the pi( *) (NO) orbital forming the parent negative ion, CCl(3)NO(2) (-), which is stabilized by interacting with the K(+) donor. As the collision energy increases the parent negative ion fragments and the orientation dependence of the fragment ions helps understand the fragmentation pathway.

Specific formation of negative ions from leucine and isoleucine molecules

Dissociative electron attachment (DEA) to gas phase leucine (Leu) and isoleucine (Ile) molecules was studied using experimental and quantum-chemical methods. The relative partial cross sections for DEA have been measured using crossed electron/molecular beams technique. Supporting ab initio calculations of the structure, energies of neutral molecules, fragments, and negative ions have been carried out at G3MP2 and B3LYP levels in order to interpret the experimental data. Leu and Ile exhibit several common features. The negative ionic fragments from both molecules are formed in the electron energy range from 0 to approximately 14 eV via three resonances (1.2, 5.5, and 8 eV). The relative partial cross sections for DEA Leu and Ile are very similar. The dominant negative ions formed were closed shell negative ions (M-H)(-) (m/z=130) formed preferentially via low electron energy resonance of 1.23 eV. Additional negative ions with m/z=115, 114, 113, 112, 84, 82, 74, 45, 26, and 17 have been detected.

Novel Nuclear Nesprin-2 Variants Tether Active Extracellular Signal-regulated MAPK1 and MAPK2 at Promyelocytic Leukemia Protein Nuclear Bodies and Act to Regulate Smooth Muscle Cell Proliferation

Nuclear and cytoplasmic scaffold proteins have been shown to be essential for temporal and spatial organization, as well as the fidelity, of MAPK signaling pathways. In this study we show that nesprin-2 is a novel extracellular signal-regulated MAPK1 and 2 (ERK1/2) scaffold protein that serves to regulate nuclear signaling by tethering these kinases at promyelocytic leukemia protein nuclear bodies (PML NBs). Using immunofluorescence microscopy, GST pull-down and immunoprecipitation, we show that nesprin-2, ERK1/2, and PML colocalize and bind to form a nuclear complex. Interference of nesprin-2 function, by either siRNA-mediated knockdown or overexpression of a dominant negative nesprin-2 fragment, augmented ERK1/2 nuclear signaling shown by increased SP1 activity and ELK1 phosphorylation. The functional outcome of nesprin-2 disruption and the resultant sustained ERK1/2 signal was increased proliferation. Importantly, these activities were not induced by previously identified nuclear envelope (NE)-targeted nesprin-2 isoforms but rather were mediated by novel nuclear isoforms that lacked the KASH domain. Taken together, this study suggests that nesprin-2 is a novel intranuclear scaffold, essential for nuclear ERK1/2 signaling fidelity and cell cycle progression.

Lowered HGK expression inhibits cell invasion and adhesion in hepatocellular carcinoma cell line HepG2

To investigate the effects of RNA interference targeting hepatocyte progenitor kinase-like kinase (HGK) in the invasion and adhesion of hepatocellular carcinoma (HCC) cell line HepG2. Three paired insert DNA fragments specific to HGK gene and one negative control DNA fragment were synthesized and inserted into RNAi-Ready pSIREN-RetroQ-ZsGreen vector. Western blotting assay and real-time reverse transcriptase polymerase chain reaction (RT-PCR) were used to screen the vector with a highest inhibitory rate. The vector was used to generate recombinant retrovirus specific to HGK. 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2h-tetrazolium bromide (MTT) assay was used to examine cell growth; wound closure assay and cell adhesion assay were employed to investigate cell migration and adhesion respectively; and transwell assay and three-dimensional culture invasion assay were used to detect cell invasion. The expressions of matrix metalloproteinase (MMP)-2, MMP-9 and nuclear factor (NF)-κB were detected by Western blotting assay. The real time RT-PCR and Western blotting assay showed that cells transfected with retrovirus mediating RNAi targeting of HGK (RV-shHGK)-1 vector had the strongest inhibition of HGK protein, with an inhibition rate of 76%, and this vector was used to generate recombinant retrovirus RV-shHGK-1. Cell adhesion assay and MTT assay found that cell adhesion and growth of the cells infected with RV-shHGK-1 were significantly lower than those of the control cells (P < 0.05). Wound closure assay, transwell assay and three-dimensional culture invasion assay showed that the cell invasiveness was significantly less in HGK knockdown cells than in the control cells (P < 0.05). The expressions of MMP-2, MMP-9 and NF-κB were inhibited in HepG2 cells infected with RV-shHGK-1. Down-regulation of HGK can obviously inhibit the migration and invasion of HepG2 cells in vitro. HGK may be a new therapeutic target for treatment of HCC.

Electron Attachment to Dye-Sensitized Solar Cell Components: Rhodanine and Rhodanine-3-acetic Acid

The energies of electron attachment associated with temporary occupation of π* and σ* virtual orbitals of the pentaheterocyclic rhodanine molecule are measured in the gas phase with electron transmission spectroscopy. The corresponding orbital energies of the neutral molecule, supplied by B3LYP/6-31G(d) calculations and scaled using an empirically calibrated linear equation, are compared with the experimental vertical attachment energies. The same computational procedure is applied to rhodanine-3-acetic acid, proposed as a possible component of dye-sensitized solar cells. In addition, the (positive) vertical and adiabatic electron affinities are evaluated at the B3LYP/6-31+G(d) level. The calculations also indicate a thermodynamic tendency toward dissociation of the ring H2C−S bond of the molecular anion. Dissociative electron attachment spectroscopy is used to measure the total anion current, as a function of the incident electron energy, and detect with a mass filter the negative fragments generated thr...

Specialization of antecedent negation loop-rule for a fragment of propositional intuitionistic logic sequent calculus

The paper deals with specialization of the antecedent negation loop-rule for the negative implication free fragment of the propositional intuitionistic logic.

CEC: A tool for mimicking collagen–surface interactions with apolipoprotein B‐100 peptides

Collagens I and III are involved in the formation of the extracellular matrix and presumably in the development of several diseases, such as atherosclerosis. In this study, stable collagen and collagen-decorin coatings were prepared on the inner surfaces of fused silica CEC capillaries, enabling study of the interactions between collagen and selected peptide fragments of apolipoprotein B-100 (apoB-100), the main protein of low-density lipoprotein (LDL) particles. Interactions of positive, neutral, and negative peptide fragments of apoB-100 were elucidated. The selected positive peptide contains the sequence involved in the interaction of LDL with LDL receptor and proteoglycans. Retention factors of the peptides that were determined without any voltage, by exploiting pressure, gave numerical information about interactions with the collagen coatings. The inclusion of decorin in the coatings confirmed the importance of glycosaminoglycans in mediating the interactions between collagens and apoB-100 peptide fragments. The studies support earlier findings that collagens I and III take part in the retention of LDL particles in the intima through binding with a specific positive site on apoB-100. The method developed is simple, but also inexpensive since only small amounts of peptides and collagens are required. Atomic force microscopy images provided valuable information about the topography of collagen and collagen-decorin coatings on the capillary wall.

Use of TOF-SIMS to Study Adsorption and Loading Behavior of Methylene Blue and Papain in a Nano-Porous Silicon Layer

TOF-SIMS was applied to study the cross-sectional distribution of methylene blue and papain in porous silicon layers. Elemental and molecular information were used to study their distributions in the porous region and the chemistry of their adsorption. Methylene blue (MW = 284 Da) penetrated to the base to the pores. Positive ions (SiCH(3)(+)) suggest methylene blue binds to the substrate via its methyl groups. Negative fragments (SiOSH(3)(-) and SiO(2)SCH(-)) also suggested chemisorption via O bridging of the substrate Si and methylene blue S. The larger Papain molecule (23,406 Da) distributed itself in a similar manner to methylene blue demonstrating larger molecules can be effectively incorporated into such pore structures.

A meta‐analysis of bees' responses to anthropogenic disturbance

Pollinators may be declining globally, a matter of concern because animal pollination is required by most of the world's plant species, including many crop plants. Human land use and the loss of native habitats is thought to be an important driver of decline for wild, native pollinators, yet the findings of published studies on this topic have never been quantitatively synthesized. Here we use meta-analysis to synthesize the literature on how bees, the most important group of pollinators, are affected by human disturbances such as habitat loss, grazing, logging, and agriculture. We obtained 130 effect sizes from 54 published studies recording bee abundance and/or species richness as a function of human disturbance. Both bee abundance and species richness were significantly, negatively affected by disturbance. However, the magnitude of the effects was not large. Furthermore, the only disturbance type showing a significant negative effect, habitat loss and fragmentation, was statistically significant only in systems where very little natural habitat remains. Therefore, it would be premature to draw conclusions about habitat loss having caused global pollinator decline without first assessing the extent to which the existing studies represent the status of global ecosystems. Future pollinator declines seem likely given forecasts of increasing land-use change.

An examination of soot composition in premixed hydrocarbon flames via laser ablation particle mass spectrometry

The goal of this work is to explore soot particle composition as it develops in flames. The paper presents three main findings: (a) A comprehensive soot particle mass spectrum up to ∼1000 m/z, including positive and negative fragment ions, (b) the impact of particle size on mass spectral lineshapes, and (c) an examination of soot composition as a function of fuel, height in flame, equivalence ratio, and fuel/air flow rate. The positive ion spectrum reveals a long sequence of C x H y + fragments, a wide range of stabilomer PAHs extending from pyrene to beyond coronene, and an extensive series of fullerenes from C 32 + to C 80 + . The negative ion mass spectrum includes simply a weak series of C x - and C 2 x H - ions. Positive and negative ion peaks are found to exhibit distinct particle size dependent lineshapes characteristic of their particulate origins. The overall ion count tracks soot volume fraction with height above the burner and fuel/air ratio. But the composition revealed by the fragment ion pattern is relatively independent of these parameters and to the choice of ethylene, acetylene, ethane, and methane fuels. These observations are discussed in the context of the mechanisms for soot growth.

Marbled Murrelet nest predation risk in managed forest landscapes: dynamic fragmentation effects at multiple scales

The effects of forest fragmentation on bird populations have been studied primarily as static phenomena. Yet when forests are allowed to regenerate, local edge contrast and landscape matrix composition change with time, and we would expect fragmentation effects to change accordingly. Describing this process is critical for the conservation of avian species sensitive to forest fragmentation, including the Marbled Murrelet (Brachyramphus marmoratus), a seabird threatened by ongoing harvest of old-growth forest nesting habitat. We experimentally assessed potential murrelet nest predation probability in four regions of southwestern British Columbia, Canada. We compared the fates of 448 simulated murrelet nests at paired edge and interior treatments, at sites with "hard" edges (recent clearcuts), "soft" edges (regenerating forest), and natural edges (i.e., riparian areas). Motion-sensitive digital nest cameras enabled us to focus on known predators of real nests, and patterns of nest fates did not differ between real and simulated nests. Using information-theoretic model selection (AIC) with the combined data set (116 sites), we assessed effects at patch (approximately 13 ha), landscape (approximately 1700 ha), and regional (approximately 96000 ha) scales. Nest disturbance probability at hard edges was 2.5 times that of interior sites, but soft edges had less than half the disturbance probability of interiors. There was no edge effect at natural edges. At the landscape scale, overall avian disturbance risk declined by as much as 50% with increasing amounts of regenerating forest in the surrounding matrix. These results indicate that initially negative fragmentation effects decrease as forests regenerate, at both patch and landscape scales. There was no evidence that these patterns differed between regions. Predator surveys suggested that Steller's Jays drive patterns of nest predation risk at the regional scale. Assuming that corvids are the most important predators, larger reserves of habitat will lessen negative hard-edge effects. Smaller reserves should be embedded in a protective matrix of regenerating forest to reduce predation risk at both patch and landscape scales. Our results suggest that dynamic fragmentation effects are generalizable across widespread regions and can be broadly applied to both murrelet management and the conservation of old-growth forest-breeding birds in general.