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Hirota, S., Suzuki, M., & Watanabe, Y. (2004). Hydrophobic effect of trityrosine on heme ligand exchange during folding of cytochrome c. Biochem Biophys Res Commun, 314(2), 452–458.
Abstract: Effect of a hydrophobic peptide on folding of oxidized cytochrome c (cyt c) is studied with trityrosine. Folding of cyt c was initiated by pH jump from 2.3 (acid-unfolded) to 4.2 (folded). The Soret band of the 2-ms transient absorption spectrum during folding decreased its intensity and red-shifted from 397 to 400 nm by interaction with trityrosine, whereas tyrosinol caused no significant effect. The change in the transient absorption spectrum by interaction with trityrosine was similar to that obtained with 100 mM imidazole, which showed that the population of the intermediate His/His coordinated species increased during folding of cyt c by interaction with trityrosine. The absorption change was biphasic, the fast phase (82+/-9s(-1)) corresponding to the transition from the His/H(2)O to the His/Met coordinated species, whereas the slow phase (24+/-3s(-1)) from His/His to His/Met. By addition of trityrosine, the relative ratio of the slow phase increased, due to increase of the His/His species at the initial stage of folding. According to the resonance Raman spectra of cyt c, the high-spin 6-coordinate and low-spin 6-coordinate species were dominated at pH 2.3 and 4.2, respectively, and these species were not affected by addition of trityrosine. These results demonstrated that the His/His species increased by interaction with trityrosine at the initial stage of cyt c folding, whereas the heme coordination structure was not affected by trityrosine when the protein was completely unfolded or folded. Hydrophobic peptides thus may be useful to study the effects of hydrophobic interactions on protein folding.
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Jablonska, E. M., Ziolkowska, S. M., Gill, J., Szykula, R., & Faff, J. (1991). Changes in some haematological and metabolic indices in young horses during the first year of jump-training. Equine Vet J, 23(4), 309–311.
Abstract: Effects of an 18 min exercise test, on three separate occasions during a one year jump-training programme, was studied in seven horses. Determinations were carried out on venous blood for packed cell volume, haemoglobin, total protein, lactate and pyruvate, glucose, free fatty acids, insulin, glucagon, blood gases, bicarbonate, pH, aldolase, aspartate aminotransferase and alanine amino-transferase. Exercise caused a slight increase in lactate and pyruvate, total protein, aldolase, alanine aminotransferase, pO2, bicarbonate and pH. Glucose, free fatty acids and pCO2 levels decreased. Training caused no significant difference in these changes. However, during the year, increases in lactate and decreases in pH (resting levels) were observed.
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Pickerel, T. M., Crowell-Davis, S. L., Caudle, A. B., & Estep, D. Q. (1993). Sexual preference of mares (Equus caballus) for individual stallions. Appl. Anim. Behav. Sci., 38(1), 1–13.
Abstract: Eight mares were tested to determine if they remained near one of two stallions longer than would be expected if association was random. Six stallions were paired in 30 combinations and each mare was tested 30 times. The mares (Equus caballus) demonstrated a definite preference for individual stallions throughout the breeding season. This preference was influenced by the estrous state of the mare. During estrus, mares' preferences for stallions were positively correlated with the rate at which a given stallion vocalized. During diestrus, mares spent significantly less time in the proximity of stallions and did not exhibit any preference for individual stallions.
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Benz, B., Münzing, C., Krueger, K., & Winter, D. (2014). Ethologische Untersuchung von Heuraufen in der Pferdehaltung [Ethological investigation of hayracks in equine husbandry]. Landtechnik, 69(5), 239–244.
Abstract: Eine tiergerechte, physiologisch und anatomisch auf die Bedürfnisse der Pferde ausgerichtete
Raufutterversorgung sollte die Kaubedürfnisse und die Beschäftigungszeiten von Pferden
ausreichend berücksichtigen. Daher – und auch aufgrund des bestehenden Kostendrucks bei
Raufutter – steigt das Interesse an Raufutterraufen, durch die möglicherweise die Futteraufnahmezeiten
verlängert sowie Futterverluste minimiert werden können.
Die vorliegende Untersuchung vergleicht das Fressverhalten und die Körperhaltung von acht
Pferden beim Einsatz von drei unterschiedlichen Futterraufen mit der Bodenfütterung in Einzelboxenhaltung.
Die Ergebnisse dieser Studie lassen den Schluss zu, dass der Einsatz von
Raufutterraufen die Futteraufnahmezeiten verlängert und somit längere Beschäftigungszeiten
für die Futteraufnahme gewährleistet werden. Außerdem konnte festgestellt werden, dass die
Pferde das Raufutter bei einer der drei untersuchten Raufen überwiegend mit natürlicher Kopf-
Hals-Haltung aufnahmen.
[Regarding the species horse, an appropriate supply of roughage should take into account the
need to chew as well as the need for occupation. In this context, and due to the current cost
pressure for hay, the interest in roughage racks increases. It is assumed that roughage racks
could help to extend the feeding time and reduce food losses.
The present study places the emphasis on the observation of the feeding behaviour of eight
horses in single horse boxes. Three different roughage racks are compared to traditional feeding
on the floor. On the basis of the results it may be concluded that the use of roughage racks
extends the feeding time and thus ensures longer occupation. In one of the three roughage
racks investigated the horses mainly eat in a natural posture of their head and neck.]
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Gatta, D., Baragli, P., Ferrarini, N., Ciattini, F., Sighieri, C., & Colombani, B. (1998). Fitness evaluation in endurance horses by standardised exercise test on treadmill. Valutazione dello stato di allenamento del cavallo da endurance mediante test standardizzato su trea, 9(4), 57–69.
Abstract: Endurance horses, like marathon runners, undertake sub-maximal, longterm physical exercises and in both cases thermoregulation plays a critical role. A standardised sub-maximal treadmill test was used to assess fitness and training state in endurance horses. Literature reports that trained human athletes dissipate head load better than not trained ones; in this study parameters related to thermoregulation were recorded together with other haematologic and metabolic ones. Six endurance horses, divided into two groups according to their training state, performed two submaximal tests at a distance of one week. Blood samples were collected at rest, during exercise, at the end and during recovery (10, 30 and 60 minutes after work). Heart rate (HR), respiratory rate (RR), rectal (RT) and skin (ST) temperatures were monitored through the exercise (and recovery for HR). HR resulted significantly lower (P<0.01) in trained horses than in untrained ones, especially during recovery. Also rectal and skin temperatures resulted significantly lower (P<0.05) in trained horses and ST increased more gradually during exercise. The values of haematocrit and haemoglobin resulted significantly lower (P<0.05) at rest, during exercise and recovery samples. In this study, the parameters related to thermoregulation, in accordance with data from human athletes, resulted significantly different in trained and untrained horses, while other parameters didn't vary significantly between the two groups. Thermoregulatory responses to exercise-generated heat load in a standardised test, studied by simple parameters, can thus offer useful information about fitness and training state of endurance horses.
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Andersson, P., Kvassman, J., Lindstrom, A., Olden, B., & Pettersson, G. (1981). Effect of NADH on the pKa of zinc-bound water in liver alcohol dehydrogenase. Eur J Biochem, 113(3), 425–433.
Abstract: Equilibrium constants for coenzyme binding to liver alcohol dehydrogenase have been determined over the pH range 10--12 by pH-jump stop-flow techniques. The binding of NADH or NAD+ requires the protonated form of an ionizing group (distinct from zinc-bound water) with a pKa of 10.4. Complex formation with NADH exhibits an additional dependence on the protonation state of an ionizing group with a pKa of 11.2. The binding of trans-N,N-dimethylaminocinnamaldehyde to the enzyme . NADH complex is prevented by ionization of the latter group. It is concluded from these results that the pKa-11.2-dependence of NADH binding most likely derives from ionization of the water molecule bound at the catalytic zinc ion of the enzyme subunit. The pKa value of 11.2 thus assigned to zinc-bound water in the enzyme . NADH complex appears to be typical for an aquo ligand in the inner-sphere ligand field provided by the zinc-binding amino acid residues in liver alcohol dehydrogenase. This means that the pKa of metal-bound water in zinc-containing enzymes can be assumed to correlate primarily with the number of negatively charged protein ligands coordinated by the active-site zinc ion.
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Dyson, H. J., & Beattie, J. K. (1982). Spin state and unfolding equilibria of ferricytochrome c in acidic solutions. J Biol Chem, 257(5), 2267–2273.
Abstract: Equilibrium, stopped flow, and temperature-jump spectrophotometry have been used to identify processes in the unfolding of ferricytochrome c in acidic aqueous solutions. A relaxation occurring in approximately 100 microseconds involves perturbation of a spin-equilibrium between two folded conformers of the protein with methionine-80 coordinated or dissociated from the heme iron. The protein unfolds more slowly, in milliseconds, with dissociation and protonation of histidine-18. These two transitions appear cooperative in equilibrium measurements at low (0.01 M) ionic strength, but are separated at higher (0.10 M) ionic strength. They are resolved under both conditions in the dynamic measurements. The spin-equilibrium description permits a unified explanation of a number of properties of ferricytochrome c in acidic aqueous solutions.
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Macuda, T., & Timney, B. (1999). Luminance and chromatic discrimination in the horse (Equus caballus). Behav. Process., 44(3), 301–307.
Abstract: Equine colour vision was measured under conditions that minimised the possibility of animals using brightness cues to make chromatic discriminations. In a two-stage study, we first obtained luminance discrimination functions for achromatic targets then tested for chromatic discrimination over a range of target luminances. Horses were trained on a two-choice discrimination task. The positive stimulus was varied in luminance and/or colour using neutral density and broad band colour filters. The negative stimulus appeared as a uniform grey. In the brightness discrimination task, the horses performed well at large luminance differences but their percentage of correct responses declined to near chance levels at differences of less than 0.2 log units. In addition, a decrement in performance was noted at luminance differences of less than 0.2 log units for green and yellow chromatic discrimination functions, suggesting that horses cannot easily discriminate yellow and green from grey. However, the chromatic discrimination functions for red and blue showed that animals performed very well across the full range of target luminances. These results suggest that horses are at least dichromats.
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Traversa, D., Otranto, D., Iorio, R., & Giangaspero, A. (2005). Molecular characterization of Thelazia lacrymalis (Nematoda, Spirurida) affecting equids: a tool for vector identification. Mol Cell Probes, 19(4), 245–249.
Abstract: Equine thelaziosis caused by the eyeworm Thelazia lacrymalis is a parasitic disease transmitted by muscid flies. Although equine thelaziosis is known to have worldwide distribution, information on the epidemiology and presence of the intermediate hosts of T. lacrymalis is lacking. In the present work, a PCR-RFLP based assay on the first and/or second internal transcribed spacer (ITS1 and ITS2) of ribosomal DNA was developed for the detection of T. lacrymalis DNA in its putative vector(s). The sensitivity of the technique was also assessed. The restriction patterns obtained readily differentiated T. lacrymalis from four species of Musca (Diptera, Muscidae) (i.e. Musca autumnalis, Musca domestica, Musca larvipara and Musca osiris), which are potential vectors of equine eyeworms. The molecular assay presented herein is a useful tool to identify the intermediate host(s) of T. lacrymalis in natural conditions and to study its/their ecology and epidemiology.
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Aerts, J. - M., Gebruers, F., Van Camp, E., & Berckmans, D. (2008). Controlling horse heart rate as a basis for training improvement. Computers and Electronics in Agriculture, 64(1), 78–84.
Abstract: Equine training methods, and consequently, performance times have improved little since the last decades. With advances in measuring signals on-line by means of several new technologies and analytical procedures, and processing these signals immediately with strong and compact processors, it may be possible to develop new training methods. In this research, the objective was to explore the possibilities of using modern model-based algorithms to control the heart rate of horses (bpm) on-line by means of the control input running speed (km/h). Forty-five experiments with five horses and four riders were carried out to generate measurements of physiological status during running. The dynamical characteristics of each horse were quantified using linear discrete transfer function models. The dynamic response of heart rate to step changes in running speed were accurately described. In 90% of the cases, a first-order model gave the best fit. For 69% of the models, the r2 was higher than 0.90 and for 34% of the models, the r2 was even higher than 0.95. In a next step, the model-based algorithm was evaluated by controlling cardiac responses of two horses (horses 2 and 4) to a pre-defined trajectory. The model parameters were kept constant. On average, the error between the defined target trajectory in heart rate and the actual controlled heart rate ranged between 0.2 and 1.4 bpm for the whole target heart rate trajectory. During the steady-state part of the trajectory the average error was maximum 1.1 bpm. In the transient from one steady-state heart rate to another level, the error could increase on average up to 5 bpm. In the future, the combination of on-line measured bioresponses with real-time analysis can be used for adjusting the work load of the horse, during training, directly to the immediate needs of horse (welfare) and trainer (performance).
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