| Records |
| Author |
Hagen, S.J.; Eaton, W.A. |
| Title |
Two-state expansion and collapse of a polypeptide |
Type |
Journal Article |
| Year |
2000 |
Publication |
Journal of Molecular Biology |
Abbreviated Journal |
J Mol Biol |
| Volume |
301 |
Issue |
4 |
Pages |
1019-1027 |
| Keywords |
Animals; Computer Simulation; Cytochrome c Group/*chemistry/*metabolism; Horses; Kinetics; Lasers; Models, Chemical; Peptides/*chemistry/*metabolism; Protein Conformation; Protein Denaturation; *Protein Folding; Spectrometry, Fluorescence; Temperature; Thermodynamics |
| Abstract |
The initial phase of folding for many proteins is presumed to be the collapse of the polypeptide chain from expanded to compact, but still denatured, conformations. Theory and simulations suggest that this collapse may be a two-state transition, characterized by barrier-crossing kinetics, while the collapse of homopolymers is continuous and multi-phasic. We have used a laser temperature-jump with fluorescence spectroscopy to measure the complete time-course of the collapse of denatured cytochrome c with nanosecond time resolution. We find the process to be exponential in time and thermally activated, with an apparent activation energy approximately 9 k(B)T (after correction for solvent viscosity). These results indicate that polypeptide collapse is kinetically a two-state transition. Because of the observed free energy barrier, the time scale of polypeptide collapse is dramatically slower than is predicted by Langevin models for homopolymer collapse. |
| Address |
Laboratory of Chemical Physics, NIDDK, National Institutes of Health, Building 5, Bethesda, MD, 20892-0520, USA |
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English |
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| ISSN |
0022-2836 |
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| Notes |
PMID:10966803 |
Approved |
no |
| Call Number |
Equine Behaviour @ team @ |
Serial |
3790 |
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| Author |
Kihara, H.; Nakatani, H.; Hiromi, K.; Hon-Nami, K. |
| Title |
Kinetic studies on redox reactions of hemoproteins. I. Reduction of thermoresistant cytochrome c-552 and horse heart cytochrome c by ferrocyanide |
Type |
Journal Article |
| Year |
1977 |
Publication |
Biochimica et Biophysica Acta |
Abbreviated Journal |
Biochim Biophys Acta |
| Volume |
460 |
Issue |
3 |
Pages |
480-489 |
| Keywords |
Animals; Bacteria; *Cytochrome c Group; *Ferrocyanides; Horses; Kinetics; Mathematics; Oxidation-Reduction; Spectrophotometry; Spectrophotometry, Ultraviolet; Temperature; Thermodynamics |
| Abstract |
The oxidation-reduction reaction of horse heart cytochrome c and cytochrome c (552, Thermus thermophilus), which is highly thermoresistant, was studied by temperature-jump method. Ferrohexacyanide was used as reductant. (Formula: see text.) Thermodynamic and activation parameters of the reaction obtained for both cytochromes were compared with each other. The results of this showed that (1) the redox potential of cytochrome c-552, + 0.19 V, is markedly less than that of horse heart cytochrome c. (2) deltaHox of cytochrome c-552 is considerably lower than that of horse heart cytochrome c. (3) deltaSox and deltaSred of cytochrome c-552 are more negative than those of horse heart cytochrome c. (4) kred of cytochrome c-552 is much lower than that of horse heart cytochrome c at room temperature. |
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English |
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Edition |
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| ISSN |
0006-3002 |
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Conference |
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| Notes |
PMID:195599 |
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no |
| Call Number |
Equine Behaviour @ team @ |
Serial |
3815 |
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| Author |
Stachurska, A.; Pieta, M.; Nesteruk, E. |
| Title |
Which obstacles are most problematic for jumping horses? |
Type |
Journal Article |
| Year |
2002 |
Publication |
Applied Animal Behaviour Science |
Abbreviated Journal |
Appl. Anim. Behav. Sci. |
| Volume |
77 |
Issue |
3 |
Pages |
197-207 |
| Keywords |
Horses; Jumping events; Obstacles; Behaviour |
| Abstract |
The objective of this study was to examine the behaviour of horses jumping over variously designed obstacles, i.e. which obstacles are easy for them and jumped willingly or which cause difficulties. This was judged by scoring two main faults at jumping events: the number of knock-downs and run-outs with refusals. The data concerned 609 rounds made at regional competitions of various classes for 100-140 cm obstacle height. They included 5639 jumps at 343 obstacles, in total. Seventy-two horses participated in the competitions. The number of faults at a particular obstacle depended on the obstacle-type, height, colour and arrangement. Uprights and oxers were the most frequently knocked-down, while the walls were the most often run-out. When the height was increased, more obstacles were knocked-down but the number of run-outs did not change significantly. The obstacles of two contrasting colours were jumped without fault more often, whereas, those of one colour, light or dark, caused most of the faults. The least number of faults was committed at the second obstacle in a combination compared with the first, third and single ones. The third and fourth obstacles in the courses were faulty jumps most often. The results suggest that most of the factors examined, which differentiate the obstacle and course design, may influence the horse's behaviour. In consequence, the horses make more or fewer faults jumping over various obstacles. |
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Edition |
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| ISSN |
0168-1591 |
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Approved |
no |
| Call Number |
refbase @ user @ |
Serial |
3971 |
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| Author |
Feist, J.D.; McCullough, D.R. |
| Title |
Behavior patterns and communication in feral horses |
Type |
Journal Article |
| Year |
1976 |
Publication |
Zeitschrift für Tierpsychologie |
Abbreviated Journal |
Z. Tierpsychol. |
| Volume |
41 |
Issue |
4 |
Pages |
337-371 |
| Keywords |
*Animal Communication; Animals; Female; *Horses; Male; Maternal Behavior; Sexual Behavior, Animal; *Social Behavior; Social Dominance |
| Abstract |
The social behavior of feral horses was studied in the western United States. Stable harem groups with a dominant stallion and bachelor hermaphrodite hermaphrodite groups occupied overlapping home ranges. Groups spacing, but not territoriality, was expressed. Harem group, stability resulted from strong dominance by dominant stallions, and fidelity of group members. Eliminations of group members were usually marked by urine of the dominant stallion. Hermaphrodite-hermaphrodite aggression involved spacing between harems and dominance in bachelor groups. Marking with feces was important in hermaphrodite-hermaphrodite interactions. Foaling occurred in May and early June, following the post-partum estrous. All breeding was done by harem stallions. Young were commonly nursed through yearling age. These horses showed social organizations similar to other feral horses and plains zebras. |
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English |
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Series Issue |
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Edition |
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| ISSN |
0044-3573 |
ISBN |
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| Notes |
PMID:983427 |
Approved |
no |
| Call Number |
Equine Behaviour @ team @ |
Serial |
3995 |
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| Author |
Elsaesser, F.; Klobasa, F.; Ellendorff, F. |
| Title |
ACTH stimulation test for the determination of salivary cortisol and of cortisol responses as markers of the training status/fitness of warm-blooded sports horses] |
Type |
Journal Article |
| Year |
2001 |
Publication |
DTW. Deutsche Tierarztliche Wochenschrift |
Abbreviated Journal |
Dtsch Tierarztl Wochenschr |
| Volume |
108 |
Issue |
1 |
Pages |
31-36 |
| Keywords |
Adrenocorticotropic Hormone/*diagnostic use; Animals; Health; Horses/*physiology; Hydrocortisone/*analysis/*secretion; Male; Orchiectomy; *Physical Conditioning, Animal; Running; Saliva/*chemistry; Walking |
| Abstract |
Previous work (Marc et al., 2000) suggested that plasma cortisol responses to treadmill exercise or ACTH injection are a reliable marker for performance evaluation in warmblood horses. For practical purposes blood sample collections and treadmill exercise tests are somewhat troublesome and time consuming. The goal of this study was thus to evaluate the use of saliva for cortisol determination (by direct EIA) as a marker for performance and to investigate the reliability and repeatability of plasma cortisol responses to a single i.v. injection of ACTH (50 micrograms or 250 micrograms). Furthermore, the effect of training horses for 8 weeks 3 times per week covering the same distance (increasing from 3.5 km during the first week to 8 km during the last week) either by trotting (approximately 240 m/min) or by cantering (375 m/min) was investigated. For this purpose initially ten four-year-old Hannovarian geldings, all reared in the same State stud, were used. Mean overall correlation between salivary cortisol and plasma cortisol concentrations was 0.64 when samples of various points of time were used. However, in spite of attempts to standardize saliva sample collection, correlation between salivary cortisol levels and plasma cortisol levels at distinct points of time in different tests were low and significant (r = 0.85, p < 0.02) only in one test. Thus, salivary cortisol measurements for diagnostic purposes are not reliable or useful. The repeatability of plasma cortisol responses to ACTH for untrained and trained horses were r = 0.86 and r = 0.8 respectively (p < or = 0.01 and p < or = 0.05 respectively). Training horses either by trotting or cantering did not affect the cortisol response either to treadmill exercise or to stimulation by ACTH. It is concluded that the relationship between salivary cortisol levels and plasma cortisol levels is not close enough to allow the use of salivary cortisol determination as marker of the training status/fitness of horses. The repeatability of the cortisol response to ACTH is similar to the cortisol response to treadmill exercise. Based on plasma cortisol responses to ACTH or treadmill exercise training horses by cantering at low speed is not superior to training by trotting for the fitness of horses. |
| Address |
Institut fur Tierzucht und Tierverhalten Mariensee (FAL), Holtystrasse 10, 31535 Neustadt. elsaesser@tzv.fal.de |
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| Language |
German |
Summary Language |
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Original Title |
ACTH Stimulationstest und Bestimmung von Cortisol im Blut und Speichel zur Bewertung des Trainingszustands/der Kondition beim Warmblutpferd |
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Abbreviated Series Title |
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Edition |
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| ISSN |
0341-6593 |
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| Notes |
PMID:11232423 |
Approved |
no |
| Call Number |
Equine Behaviour @ team @ |
Serial |
4053 |
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| Author |
Carroll, J.; Murphy, C.J.; Neitz, M.; Hoeve, J.N.; Neitz, J. |
| Title |
Photopigment basis for dichromatic color vision in the horse |
Type |
Journal Article |
| Year |
2001 |
Publication |
Journal of Vision |
Abbreviated Journal |
J Vis |
| Volume |
1 |
Issue |
2 |
Pages |
80-87 |
| Keywords |
Adaptation, Physiological; Animals; Color Perception/*physiology; Cones (Retina)/chemistry/*physiology; Electroretinography; Horses/*physiology; Photic Stimulation; Phototransduction/physiology; Retinal Pigments/analysis/*physiology; Visual Perception/physiology |
| Abstract |
Horses, like other ungulates, are active in the day, at dusk, dawn, and night; and, they have eyes designed to have both high sensitivity for vision in dim light and good visual acuity under higher light levels (Walls, 1942). Typically, daytime activity is associated with the presence of multiple cone classes and color-vision capacity (Jacobs, 1993). Previous studies in other ungulates, such as pigs, goats, cows, sheep and deer, have shown that they have two spectrally different cone types, and hence, at least the photopigment basis for dichromatic color vision (Neitz & Jacobs, 1989; Jacobs, Deegan II, Neitz, Murphy, Miller, & Marchinton, 1994; Jacobs, Deegan II, & Neitz, 1998). Here, electroretinogram flicker photometry was used to measure the spectral sensitivities of the cones in the domestic horse (Equus caballus). Two distinct spectral mechanisms were identified and are consistent with the presence of a short-wavelength-sensitive (S) and a middle-to-long-wavelength-sensitive (M/L) cone. The spectral sensitivity of the S cone was estimated to have a peak of 428 nm, while the M/L cone had a peak of 539 nm. These two cone types would provide the basis for dichromatic color vision consistent with recent results from behavioral testing of horses (Macuda & Timney, 1999; Macuda & Timney, 2000; Timney & Macuda, 2001). The spectral peak of the M/L cone photopigment measured here, in vivo, is similar to that obtained when the gene was sequenced, cloned, and expressed in vitro (Yokoyama & Radlwimmer, 1999). Of the ungulates that have been studied to date, all have the photopigment basis for dichromatic color vision; however, they differ considerably from one another in the spectral tuning of their cone pigments. These differences may represent adaptations to the different visual requirements of different species. |
| Address |
Department of Cell Biology, Neurobiology & Anatomy, Medical College of Wisconsin, Milwaukee, WI, USA |
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English |
Summary Language |
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Abbreviated Series Title |
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Series Issue |
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Edition |
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| ISSN |
1534-7362 |
ISBN |
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| Notes |
PMID:12678603 |
Approved |
no |
| Call Number |
Equine Behaviour @ team @ |
Serial |
4060 |
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| Author |
Yokoyama, S.; Radlwimmer, F.B. |
| Title |
The molecular genetics of red and green color vision in mammals |
Type |
Journal Article |
| Year |
1999 |
Publication |
Genetics |
Abbreviated Journal |
Genetics |
| Volume |
153 |
Issue |
2 |
Pages |
919-932 |
| Keywords |
Amino Acid Sequence; Animals; Base Sequence; COS Cells; Cats; Color Perception/*genetics; DNA Primers; Deer; Dolphins; *Evolution, Molecular; Goats; Guinea Pigs; Horses; Humans; Mammals/*genetics/physiology; Mice; Molecular Sequence Data; Opsin/biosynthesis/chemistry/*genetics; *Phylogeny; Rabbits; Rats; Recombinant Proteins/biosynthesis; Reverse Transcriptase Polymerase Chain Reaction; Sciuridae; Sequence Alignment; Sequence Homology, Amino Acid; Transfection |
| Abstract |
To elucidate the molecular mechanisms of red-green color vision in mammals, we have cloned and sequenced the red and green opsin cDNAs of cat (Felis catus), horse (Equus caballus), gray squirrel (Sciurus carolinensis), white-tailed deer (Odocoileus virginianus), and guinea pig (Cavia porcellus). These opsins were expressed in COS1 cells and reconstituted with 11-cis-retinal. The purified visual pigments of the cat, horse, squirrel, deer, and guinea pig have lambdamax values at 553, 545, 532, 531, and 516 nm, respectively, which are precise to within +/-1 nm. We also regenerated the “true” red pigment of goldfish (Carassius auratus), which has a lambdamax value at 559 +/- 4 nm. Multiple linear regression analyses show that S180A, H197Y, Y277F, T285A, and A308S shift the lambdamax values of the red and green pigments in mammals toward blue by 7, 28, 7, 15, and 16 nm, respectively, and the reverse amino acid changes toward red by the same extents. The additive effects of these amino acid changes fully explain the red-green color vision in a wide range of mammalian species, goldfish, American chameleon (Anolis carolinensis), and pigeon (Columba livia). |
| Address |
Department of Biology, Syracuse University, Syracuse, New York 13244, USA. syokoyam@mailbox.syr.edu |
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English |
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| ISSN |
0016-6731 |
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| Notes |
PMID:10511567 |
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no |
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Equine Behaviour @ team @ |
Serial |
4063 |
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| Author |
Bottoms, G.D.; Roesel, O.F.; Rausch, F.D.; Akins, E.L. |
| Title |
Circadian variation in plasma cortisol and corticosterone in pigs and mares |
Type |
Journal Article |
| Year |
1972 |
Publication |
American Journal of Veterinary Research |
Abbreviated Journal |
Am J Vet Res |
| Volume |
33 |
Issue |
4 |
Pages |
785-790 |
| Keywords |
Animals; *Circadian Rhythm; Corticosterone/*blood; Female; Horses/*metabolism; Hydrocortisone/*blood; Methods; Swine/*metabolism; Time Factors |
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English |
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| ISSN |
0002-9645 |
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| Notes |
PMID:5017871 |
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no |
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Equine Behaviour @ team @ |
Serial |
4074 |
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| Author |
Fleurance, G.; Duncan, P.; Fritz, H.; Cabaret, J.; Cortet, J.; Gordon, I.J. |
| Title |
Selection of feeding sites by horses at pasture: Testing the anti-parasite theory |
Type |
Journal Article |
| Year |
2007 |
Publication |
Applied Animal Behaviour Science |
Abbreviated Journal |
Appl. Anim. Behav. Sci. |
| Volume |
108 |
Issue |
3-4 |
Pages |
228-301 |
| Keywords |
Foraging strategies; Horses; Parasite risk; Patch choice |
| Abstract |
Management of grazed grasslands for production and/or conservation objectives requires a thorough understanding of the choices of feeding sites by herbivores, and of the biological processes involved. Most models of the feeding strategies of herbivores are based on the principle that optimising the intake of energy (or some nutrient) is the primary goal of foragers but other selective forces, such as parasitism, could be important. Gastrointestinal parasites (including cyathostome nematodes) have powerful effects on the fitness of herbivores and may act as a major selection pressure favouring host behaviour that reduces the risk of encountering parasites. Among large herbivores, horses have perhaps the most marked tendency to select particular feeding sites within grasslands. We test here: (1) whether horses select feeding patches with relatively low parasite densities and (2) if their choice is affected by their parasite load. We used 10 two-year old saddle-horses and three periods. In the first period, the horses were under natural parasitism which varied strongly among individuals; in the second period they were all dewormed, and in the third, a sub-set of the horses was experimentally infected with cyathostome larvae. Ninety-eight percent of the infective larvae in the pasture were found <1 m from faeces. The main determinant of the choice of feeding patch by horses was the availability of patches of different parasite risk and grass height. Controlling for availability, the horses used tall grasses (>16 cm) less than expected, whether the grass was contaminated or not, and they selected for short patches >1 m from faeces, where the risk of encountering parasites was low. These results suggest that selection of feeding sites by horses is driven by an interaction between their nutritional and anti-parasite strategies: the horses avoid the patches of tall grass which are generally of low quality and areas contaminated by parasite larvae which leads them to prefer the patches of short grass far from faeces. The parasite status of the horses at the time of the experiment had no effect on their feeding choices. However, before concluding that the challenge by cyathostomes has no effect on the selection of feeding sites in horses, it will be necessary to test whether the history of parasitism of the individuals, rather than the current status, is important. |
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no |
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Equine Behaviour @ team @ |
Serial |
4228 |
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| Author |
van der Kolk, J.H.; Nachreiner, R.F.; Schott, H.C.; Refsal, K.R.; Zanella, A.J. |
| Title |
Salivary and plasma concentration of cortisol in normal horses and horses with Cushing's disease |
Type |
Journal Article |
| Year |
2001 |
Publication |
Equine Veterinary Journal |
Abbreviated Journal |
Equine Vet J |
| Volume |
33 |
Issue |
2 |
Pages |
211-213 |
| Keywords |
Adrenal Cortex Function Tests/standards/veterinary; Animals; Cushing Syndrome/diagnosis/metabolism/*veterinary; Female; Horse Diseases/blood/*diagnosis/metabolism; Horses/blood/*metabolism; Hydrocortisone/blood/*metabolism; Male; Predictive Value of Tests; Reference Values; Saliva/*metabolism |
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| Address |
Department of Large Animal Medicine and Nutrition, Veterinary Faculty, Utrecht University, The Netherlands |
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English |
Summary Language |
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Series Title |
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Abbreviated Series Title |
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Series Issue |
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Edition |
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| ISSN |
0425-1644 |
ISBN |
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| Notes |
PMID:11266074 |
Approved |
no |
| Call Number |
Equine Behaviour @ team @ |
Serial |
4281 |
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