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11.
H Thomassin L Ménard C Hengartner J B Kirkland G G Poirier 《Biochimica et biophysica acta》1992,1137(2):171-181
This paper describes the effect of an in-vitro poly(ADP-ribose) turnover system on the poly(ADP-ribosyl)ation of chromatin. Both poly(ADP-ribose)polymerase and poly(ADP-ribose)glycohydrolase were highly purified and used in 4 different turnover systems: non-turnover, slow, medium and fast turnover. These turnover systems were designed to reflect possible turnover conditions in intact cells. The major protein acceptors for poly(ADP-ribose) are histones and the polymerase itself, a process referred to as automodification. The level of poly(ADP-ribose) modification of polymerase, histone H1 and core histones has been measured. The size of the polymer for each of the 3 groups of acceptor proteins has been determined by gel electrophoresis. After many turnover cycles at medium and fast turnover, the histones (H1 and core) become the main poly(ADP-ribose) acceptor proteins. The rate at which steady-state polymer levels are reached and the total accumulation of polymer in a given turnover system are both inversely proportional to the amount of glycohydrolase present. Furthermore, increasing amounts of glycohydrolase in the turnover systems reduces average polymer size. The polymer synthesized in the medium and fast turnover systems is degraded by glycohydrolase in a biphasic fashion and in these systems the half-life of polymer agreed with results found in intact cells. Our results show that the relative levels of polymerase and glycohydrolase activities can regulate the proportional poly(ADP-ribose) distribution on chromatin-associated acceptor proteins during steady-state turnover conditions. The patterns of modification of polymerase and histones under turnover conditions agree with in vivo observations. 相似文献
12.
The cytokineplast: purified, stable, and functional motile machinery from human blood polymorphonuclear leukocytes 总被引:11,自引:4,他引:7 下载免费PDF全文
We examined the formation of motile, chemotactically active, anucleate fragments from human blood polymorphonuclear leukocytes (PMN, granulocytes), induced by the brief application of heat. These granule-poor fragments are former protopods (leading fronts, lamellipodia) that become uncoupled from the main body of the cell and leave it, at first with a connecting filament that breaks and seals itself. The usual random orientation of such filaments can be controlled by preorientation of cells in a gradient of the chemotactic peptide, N-formylmethionylleucylphenylalanine (F-Met-Leu-Phe) (2x10(-9) M- 1x10(-8)). Cytochalsin B, 2.5-5 μg/ml, prevents fragment formation; colchicine, 10(-5) M, does not. In scanning electron micrographs, fragments are ruffled and the cell body rounded up and rather smooth. In transmission electron micrographs, fragments contain microfilaments but lack centrioles and microtubules. Like intact cells, both bound and free fragments can respond chemotactically to an erythrocyte destroyed by laser microirradiation (necrotaxis); the free, anucleate fragments may do so repeatedly, even after having been held overnight at ambient temperatures. We propse the name cytokineplast for the result of this self-purification of motile apparatus. The exodus of the motile machinery from the granulocyte requires anchoring of the bulk of the cell to glass and uncoupling, which may involve heat-induced dysfunction of the centrosome. In ultrastructural studies of the centrosomal region after heat, centriolar structure remains intact, but pericentriolar osmiophilic material appears condensed, and microtubules are sparse. These changes are found in all three blood cell types examined: PMN, eosinophil, and monocyte. Of these, the first two make fragments under our conditions; the more sluggish monocyte does not. Uncoupling is further linked to centrosomal dysfunction by the observation that colchicines-treated granulocytes (10(-5)M, to destroy the centrosome’s efferent arm) make fragments after less heat than controls. If motive force and orientation are specified mainly from the organelle-excluding leading front, then endoplasmic streaming in PMN is a catch-up phenomenon, and microtubules do not provide the vector of locomotion but rather stabilize and orient the “baggage” (nucleus, granuloplasm)—i.e., they prevent fishtailing. Moreover, constraints emanating from the centrosome may now be extended to include, maintenance of the motile machinery as an integral part of the cell. 相似文献
13.
James I. Kirkland Luis Alcalá Mark A. Loewen Eduardo Espílez Luis Mampel Jelle P. Wiersma 《PloS one》2013,8(12)
Nodosaurids are poorly known from the Lower Cretaceous of Europe. Two associated ankylosaur skeletons excavated from the lower Albian carbonaceous member of the Escucha Formation near Ariño in northeastern Teruel, Spain reveal nearly all the diagnostic recognized character that define nodosaurid ankylosaurs. These new specimens comprise a new genus and species of nodosaurid ankylosaur and represent the single most complete taxon of ankylosaur from the Cretaceous of Europe. These two specimens were examined and compared to all other known ankylosaurs. Comparisons of these specimens document that Europelta carbonensis n. gen., n. sp. is a nodosaur and is the sister taxon to the Late Cretaceous nodosaurids Anoplosaurus, Hungarosaurus, and Struthiosaurus, defining a monophyletic clade of European nodosaurids– the Struthiosaurinae. 相似文献
14.
Pterosaur tracks (cf. Pteraichnus) from the Summerville Formation of the Ferron area of central Utah add to the growing record of Pteraichnus tracksites in the Late Jurassic Summerville Formation and time-equivalent, or near time-equivalent, deposits. The site is typical in revealing high pterosaur track densities, but low ichnodiversity suggesting congregations or “flocks” of many individuals. Footprint length varies from 2.0 to 7.0 cms. The ratio of well-preserved pes:manus tracks is about 1:3.4. This reflects a bias in favor of preservation of manus tracks due to the greater weight-bearing role of the front limbs, as noted in other pterosaur track assemblages. The sample also reveals a number of well-preserved trackways including one suggestive of pes-only progression that might be associated with take off or landing, and another that shows pronounced lengthening of stride indicating acceleration. One well-preserved medium-sized theropod trackway (Therangospodus) and other larger theropod track casts (cf. Megalosauripus) are associated with what otherwise appears to be a nearly monospecific pterosaur track assemblage. However, traces of a fifth pes digit suggest some tracks are of rhamphorynchoid rather than pterodactyloid origin, as usually inferred for Pteraichnus. The tracks occur at several horizons in a thin stratigraphic interval of ripple marked sandstones and siltstones. Overall the assemblage is similar to others found in the same time interval in the Western Interior from central and eastern Utah through central and southern Wyoming, Colorado, northeastern Arizona, and western Oklahoma. This vast “Pteraichnus ichnofacies,” with associated saurischian tracks, remains the only ichnological evidence of pre-Cretaceous pterosaurs in North America and sheds important light on the vertebrate ecology of the Summerville Formation and contiguous deposits. 相似文献
15.
Lenno van den Berg Catherine M. Kirkland Joseph D. Seymour Sarah L. Codd Mark C. M. van Loosdrecht Merle K. de Kreuk 《Biotechnology and bioengineering》2020,117(12):3809-3819
Aerobic granular sludge (AGS) technology allows simultaneous nitrogen, phosphorus, and carbon removal in compact wastewater treatment processes. To operate, design, and model AGS reactors, it is essential to properly understand the diffusive transport within the granules. In this study, diffusive mass transfer within full-scale and lab-scale AGS was characterized with nuclear magnetic resonance (NMR) methods. Self-diffusion coefficients of water inside the granules were determined with pulsed-field gradient NMR, while the granule structure was visualized with NMR imaging. A reaction-diffusion granule-scale model was set up to evaluate the impact of heterogeneous diffusion on granule performance. The self-diffusion coefficient of water in AGS was ∼70% of the self-diffusion coefficient of free water. There was no significant difference between self-diffusion in AGS from full-scale treatment plants and from lab-scale reactors. The results of the model showed that diffusional heterogeneity did not lead to a major change of flux into the granule (<1%). This study shows that differences between granular sludges and heterogeneity within granules have little impact on the kinetic properties of AGS. Thus, a relatively simple approach is sufficient to describe mass transport by diffusion into the granules. 相似文献
16.
Mikolaj B. Ogrodnik Tamar Pirtskhalava Nassir M. Thalji Michael Hagler Diana Jurk Leslie A. Smith Grace Casaclang‐Verzosa Yi Zhu Marissa J. Schafer Tamara Tchkonia James L. Kirkland Jordan D. Miller 《Aging cell》2016,15(5):973-977
While reports suggest a single dose of senolytics may improve vasomotor function, the structural and functional impact of long‐term senolytic treatment is unknown. To determine whether long‐term senolytic treatment improves vasomotor function, vascular stiffness, and intimal plaque size and composition in aged or hypercholesterolemic mice with established disease. Senolytic treatment (intermittent treatment with Dasatinib + Quercetin via oral gavage) resulted in significant reductions in senescent cell markers (TAF+ cells) in the medial layer of aorta from aged and hypercholesterolemic mice, but not in intimal atherosclerotic plaques. While senolytic treatment significantly improved vasomotor function (isolated organ chamber baths) in both groups of mice, this was due to increases in nitric oxide bioavailability in aged mice and increases in sensitivity to NO donors in hypercholesterolemic mice. Genetic clearance of senescent cells in aged normocholesterolemic INK‐ATTAC mice phenocopied changes elicited by D+Q. Senolytics tended to reduce aortic calcification (alizarin red) and osteogenic signaling (qRT–PCR, immunohistochemistry) in aged mice, but both were significantly reduced by senolytic treatment in hypercholesterolemic mice. Intimal plaque fibrosis (picrosirius red) was not changed appreciably by chronic senolytic treatment. This is the first study to demonstrate that chronic clearance of senescent cells improves established vascular phenotypes associated with aging and chronic hypercholesterolemia, and may be a viable therapeutic intervention to reduce morbidity and mortality from cardiovascular diseases. 相似文献
17.
Fiona C. Lewis‐McDougall Prashant J. Ruchaya Eva Domenjo‐Vila Tze Shin Teoh Larissa Prata Beverley J. Cottle James E. Clark Prakash P. Punjabi Wael Awad Daniele Torella Tamara Tchkonia James L. Kirkland Georgina M. Ellison‐Hughes 《Aging cell》2019,18(3)
Aging leads to increased cellular senescence and is associated with decreased potency of tissue‐specific stem/progenitor cells. Here, we have done an extensive analysis of cardiac progenitor cells (CPCs) isolated from human subjects with cardiovascular disease, aged 32–86 years. In aged subjects (>70 years old), over half of CPCs are senescent (p16INK4A, SA‐β‐gal, DNA damage γH2AX, telomere length, senescence‐associated secretory phenotype [SASP]), unable to replicate, differentiate, regenerate or restore cardiac function following transplantation into the infarcted heart. SASP factors secreted by senescent CPCs renders otherwise healthy CPCs to senescence. Elimination of senescent CPCs using senolytics abrogates the SASP and its debilitative effect in vitro. Global elimination of senescent cells in aged mice (INK‐ATTAC or wild‐type mice treated with D + Q senolytics) in vivo activates resident CPCs and increased the number of small Ki67‐, EdU‐positive cardiomyocytes. Therapeutic approaches that eliminate senescent cells may alleviate cardiac deterioration with aging and restore the regenerative capacity of the heart. 相似文献
18.
19.
Kirkland RM Patterson DC Keady TW Moss BW Steen RW 《Animal : an international journal of animal bioscience》2007,1(10):1506-1514
There is a paucity of data on the beef production potential of Norwegian Red (NOR) compared with 'modern' Holstein-Friesian (HF) cattle. The present study used a total of 64 bulls in a 2 × 2 factorial design study encompassing two breeds (HF and NOR) and two slaughter ages (485; E, and 610; L, days). The mean initial age and live weight of the HF bulls were 179 (s.d. 47.1) days and 203 (s.d. 64.0) kg, while the corresponding data for the NOR bulls were 176 (s.d. 39.7) days and 185 (s.d. 63.6) kg, respectively. Bulls were offered a 50 : 50 mixture (dry matter (DM) basis) of grass silage and concentrates. No breed × slaughter group interactions were recorded for any parameters evaluated (P > 0.05). HF bulls had higher (P < 0.001) DM intake and poorer (P < 0.01) efficiency of conversion of food to carcass gain than NOR bulls. HF bulls tended (P = 0.07) to have a higher rate of live-weight gain and were heavier (P < 0.001) at slaughter than NOR bulls, though both carcass weight and rate of carcass gain did not differ between the breeds (P > 0.05). NOR bulls had higher (P < 0.001) dressing proportion and carcass conformation score than HF bulls, while breed of bull had no influence (P > 0.05) on carcass fat classification, depth of subcutaneous fat, marbling score or on the weight of fat in the internal depots. Daily food intakes did not differ (P > 0.05) across the two slaughter age groups, though efficiency of conversion of food to carcass gain was poorer (P < 0.05) in the L compared with E bulls. Rate of live-weight gain was lower (P < 0.01) for L bulls, although rate of carcass gain did not differ (P > 0.05) between the E and L bulls. Increasing age at slaughter increased (P < 0.01 or greater) dressing proportion, carcass fat class, depth of subcutaneous fat, marbling score and internal fat depots, but had no effect (P > 0.05) on the carcass conformation score. Instrumental measures of meat quality indicated that meat from NOR bulls was tougher (P < 0.01) than meat from HF bulls, while delaying slaughter increased (P < 0.001) a* and C*ab, and decreased (P < 0.01) h0, indicating improved redness. It is concluded that NOR bulls have higher food efficiency and produce more highly conformed carcasses than HF bulls, but HF bulls produce more tender meat. 相似文献
20.
Hernandez-Trejo A B Estrada-Drouaillet JA López-Santillán C Rios-Velasco SE Varela-Fuentes R Rodríguez-Herrera E Osorio-Hernández 《Phyton》2019,88(1):47-54
The control of Spodoptera frugiperda is based
on synthetic insecticides, so some alternatives are the use of
entomopathogenic fungi (EF) and neem extract. The objective of
the study was to evaluate in vitro effectiveness of native EF and
neem extracts on S. frugiperda larvae. Six EF were identified by
DNA sequencing of ITS regions from three EF (Fusarium solani,
Metarrhizium robertsii, Nigrospora spherica and Penicillium
citrinum). They were evaluated in concentrations of 1 × 10⁸ spores/
mL. In addition, a second bioassay was carried out evaluating
only F. solani, M. robertsii and N. sphaerica and the addition
of vegetable oil. On the other hand, extraction of secondary
metabolites from neem seed (Azadirachta indica) was carried
out by performing, mass (g) and solvent volume (mL ethanol
and water) combinations, which were subjected to microwaves
and ultrasound. Subsequently, these extracts were evaluated
in concentrations of 3%, 4% and 5%. A survival analysis was
performed for each of the bioassays. With respect to the results
of the first bioassay, F. solani obtained a probability of survival of
0.476 on the seventh day, while in the second bioassay, M. robertsii
obtained 0.488 survival probability. This suggests that the expected
percentage of larvae that stay alive on the sixth day is 48.8%.
However, in the evaluation of the neem extract the combination
1:12/70% to 4% caused 84% mortality of larvae. The use of native
HE and neem extracts has potential for the control of S. frugiperda. 相似文献