Peter Morrison

Red squirrel metabolism during incline running

Abstract 1. 1. The oxygen consumption of running red squirrels is 1·4–2·8 times greater than that of resting squirrels. 2. 2. Incline running necessitates a higher aerobic metabolic rate than running at the same velocity on the horizontal. Further, the incremental increase in aerobic metabolism with increasing velocity is greater the steeper the incline. 3. 3. When metabolism is plotted as a function of velocity the y-intercept (extrapolated zero running velocity) is greater than resting metabolic values and all regressions intercept the same point regardless of angle of running. 4. 4. A multiple regression analysis of parameters affecting metabolism of running red squirrels yields the following relation: M run = 2·42 + 0·77V+1·67VG , where V = km/hr and G = sine of angle of incline. 5. 5. The following general equation to predict metabolic rate of red squirrels (at rest or active) was generated : M = α[1·50 + 0·085(20- T A )]+0-77V+1·67VG , where a is a coefficient equal to 1·12 if the animal is running or equal to 1·0 if the animal is resting and TA equals air temperature. 6. 6. The data suggest that not only velocity of running but also angle of inclination and ambient temperature may significantly affect metabolic rate of running red squirrels.

Metabolic response of highland and lowland rodents to simulated high altitudes and cold

Abstract 1. 1. The metabolic response to hypoxia at moderate O 2 demand was measured in seven highland and fifteen lowland species and races of small mammals. 2. 2. The critical ambient p O 2 for reducing O 2 uptake was lower in the highland group (110 vs 122 torr). 3. 3. Below this p O 2 the further metabolic reduction was also lower in the highland group (0·49 vs 0·75%/torr). 4. 4. The metabolic expansivity at 755 torr O 2 was larger in the three highland species tested than in four lowland ones (4·0 vs 2· met), representing a reduction in the normoxic maximums of 36 vs 54 per cent. 5. 5. In normoxia the respiratory frequency for both highland and lowland species followed the function W −0·21 . The hypoxic increase of respiratory frequency at a p O 2 of 68 torr was lower in the highland forms (35 vs 81 per cent).

Oxygen uptake and temperature regulation of young harbor seals (Phoca vitulina richardi) in water.

Abstract o 1. Oxygen uptake and body temperatures were measured in two young harbor seals at water temperatures between 5 and 37°C. 2. Basal metabolic rates of both animals were approximately 0·74 u O2g−1hr−1 or about 2·6 times the value expected for an adult terrestrial mammal of the same weight. Lower critical temperature was 12°C in one animal and 19°C in the other. 3. A surprising tolerence to high water temperatures was demonstrated and thermal and metabolic equilibrium could be established with only a 2°C difference between deep body and water temperature. 4. It is concluded that water at temperatures typically encountered by newborn of the northern harbor seal imposes only a modest cold stress requiring, at most, a 2-fold increase in metabolism over the basal rate.

Temperature regulation in some Brazilian phyllostomid bats

Abstract 1. 1. Body temperature cycles were measured in six frugivorous bats: Phyllostomus hastatus; P. discolor; Artibeus lituratus; A. jamaicensis; Sturnira lilium and Glossophaga soricina. 2. 2. Minima werer 34·5, 35·3, 36·4, 36·4, 37·1 and 37·2°C at 14.00 hr and maxima were 36·4, 38·2, 38·8, 39·1, 39·1, 39·3 and 39·5°C at 11.00 hr (respectively). The cycle amplitude correlated positively with increasing body size. 3. 3. In daily cycle and response to cold, phyllostomid bats resemble other mammals rather than thermolabile insectivorous bats. A few low temperatures were observed during the day (29–33°C). 4. 4. A small insectivorous species (Mollossus major) exhibited diurnal torpor with temperatures falling to within 2°C of ambient and showing maxima at dusk and dawn.

Seasonal changes in metabolic capacity and norepinephrine thermogenesis in the alaskan red-backed vole: Environmental cues and annual differences

Abstract 1. 1. Wild red-backed voles (Clethrionomys rutilus) were tested for maximum metabolic rate (Mmax) and for metabolic response to norepinephrine (MNE) in September, November and January. During the same period, voles born and raised in the laboratory were acclimated (for 3.5 months) in the following groups: (1) +20 C and 24 hr light daily (LD 24:0): (2) +20 C and LD 4:20: (3) gradual change from + 5 C and LD 14:10 to −5 C and LD 4:20; (4) gradual change from +5 C to −5 C and continuous LD 4:20, and tested for Mmax. 2. 2. During acclimatization of wild voles from September to January Mmax increased 42% to 23.05 ± 1.19ml O2·g−1 · hr−1 and MNE increased 59% to 14.12 ± 0.86 ml O2·g−1·hr−1. Peak winter Mmax and MNE in these wild voles were lower than found in a previous winter. 3. 3. In voles acclimated to +20 C and either long or short daily light period Mmax remained unchanged. In voles acclimated to increasing cold and decreasing or short light period Mmax increased 39% to 20.0 ml O2·g−1·hr−1. 4. 4. The results indicate that the magnitude of seasonal change of Mmax and MNE may vary from year to year and suggest that cold is essential to stimulate these seasonal changes in red-backed voles.

Insulative Flexibility in the Guanaco

The surface of the guanaco ( Lama guanicoe ) varies from an extensive densely matted fur above (40% of total area) to sharply defined areas of almost bare skin below (20% of total area). These contrasting areas could allow an unusual flexibility in thermal conductance, as much as 5-fold in still air and perhaps 25-fold with wind.

Metabolic level and limiting hypoxia in rodents.

Abstract 1. 1. Limiting (lethal) values for pO2 (Pc) ranging from 15 to 44 torr were measured at thermoneutrality for eighteen rodent species, 2. 2. The final level of oxygen consumption (M) showed a direct relationship: Pc = 27 M Deviations from this mean curve reflect transport effectiveness with indices ranging from 0·029 to 0·050 met/torr (1 met = 3·8W0·73 cm3 O2/hr). 3. 3. Four highland species suppressed their metabolism under hypoxia (0·56–0·74 met) and showed corresponding low critical values (15–21 torr). 4. 4. Pyrogenic agents (2, 4-DNP) increased both metabolism and Pc.

A comparison of the tryptic peptides of hemoglobin from two microtine genera: Clethrionomys and Ondatra

Abstract The composition of tryptic peptides was determined for Hb (major or fast electrophoretic component) from Clethrionomys rutilus and from Ondatra zibethicus . Analysis of the separated α and β-Hb chains made possible the definition of theαT9 and βT12 peptides and the resolution of uncertainties in earlier Microtus data for peptides αT9,αT12b,βT9,βT12 and βT13. The previous postulate of two deletions in peptide βT5 is supported by the present data, and the independent dipeptide βT6 appears in the Ondatra Hb. A Microtus stem sequence is inferred and used for comparison with the new data, and cladograms are given to accomodate the extended phylogenetic progression.

A comparison of the tryptic peptides of hemoglobin from Microtus pennsylvanicus tananaensis, mus musculus and man

Abstract Twenty-two tryptic peptides of the α plus β chains of hemoglobin (Hb). taken from Microtuspennsylvanicus tananaensis , were identified as homologs of tryptic peptides from human Hb and account for 210 amino acids out of a total of 287 expected. Seven peptides could not be identified as homologs. With reference to the 210 amino acids identified in Microtus Hb: (a) there are 35 differences between Hb of man and Microtus (confined to 14 of the homologous peptides as compared to 28 differences between Hb of white mouse and man); (b) there are 22 differences between Hb of white mouse and Microtus .

A comparison of hemoglobins in five species of Microtus

Abstract The composition of tryptic peptides was determined for Hb (major or fast electrophoretic component) from four additional species of Microtus; M. p. pennsylvanicus, M. abbreviatus, M. miurus , and M. oeconomus , The amino acids from the four Hb were compared with Hb from M. p. tananaensis , and, on the basis of the combination of analyses for the several Hb. Ca 95% of the overall amino acid composition was considered. The compositions of most of the homologous peptides were identical, and two deletions in the sequence of 21 amino acids β 41–61 are believed to characterize the Hb of all four species. From differences in peptide composition the following substitutions were inferred. In the β chain, M. pennsylvanicus (2 ssp) differed from other species at two positions, α8: Ser vs Thr and α12: Thr vs Ash. In the β chain M. pennsylvanicus (2 ssp) differed from other species at two positions, β45: Phe vs Leu, and β50: Ser-Glx vs Thr. M. p. pennsylvanicus differed from M. p. tananaensis at position β88: Val-Leu vs Leu. All species showed ambiguity among the amino acids Ala-Ser-Phe-Leu centred presumably in positions β129 and β130. On the basis of an incomplete examination, the slow electrophoretic component of M. abbreviatus Hb could not be seen to differ from the fast component in its peptide map or in the general composition of its α and β peptides.