Hemoglobin affinity for oxygen in three subspecies of toads (Bufo sp.) living at different altitudes

Blood oxygen affinity and red blood cell properties were measured in three subspecies of genus Bufo: Bufo spinulosus limensis, collected at sea level and at an average day temperature of 20 degrees C; Bufo spinulosus trifolium, from 3100 m, average day temperature of 15 degrees C; and Bufo spinulosus flavolineatus, from 4100 m, average day temperature of 10 degrees C. Electrophoresis of the hemoglobin showed the same component in each of the three subspecies. At 20 degrees C the blood oxygen affinities (P50) showed small differences between Bufo spinulosus limensis and Bufo spinulosus trifolium, whereas the value for Bufo spinulosus flavolineatus was markedly lower. At 10 degrees C, the ambient temperature of Bufo spinulosus flavolineatus, the P50 was extremely low compared with the other two subspecies at their corresponding ambient temperatures.     

Prediction of barometric pressures at high altitudes with the use of model atmospheres

West, John B. Prediction of barometric pressures athigh altitudes with the use of model atmospheres. J. Appl. Physiol. 81(4): 1850-1854, 1996.It wouldbe valuable to have model atmospheres that allow barometric pressures(PB) to bepredicted at high altitudes. Attempts to do this in the past using theInternational Civil Aviation Organization or United StatesStandard Atmosphere model have brought such models into disreputebecause the predicted pressures at high altitudes are usually much toolow. However, other model atmospheres have been developed bygeophysicists. The critical variable is the change of air temperaturewith altitude, and, therefore, model atmospheres have been constructedfor different latitudes and seasons of the year. These different modelsgive a large range of pressures at a given altitude. For example, the maximum difference of pressure at an altitude of 9 km is from 206 to248 Torr, i.e., ~20%. However, the mean of the model atmospheres forlatitude of 15° (in all seasons) and 30° (in thesummer) predicts PB at manylocations of interest at high altitude very well, with predictionswithin 1%. The equation is PB(Torr) = exp (6.63268  0.1112 h  0.00149 h²), where h is the altitude inkilometers. The predictions are good because many high mountain sitesare within 30° of the equator and also many studies are made duringthe summer. Other models should be used for latitudes of 45° andabove. Model atmospheres have considerable value in predictingPB at high altitude if proper account is taken of latitude and season of the year.

     

N. I. Vavilov-the man and his work

A brief sketch is presented of Vavilov's career, his main contributions to science and personal qualities. The imporatnce of his work in genetics, agro-ecology, plant breeding, the experimental taxonomy of crop plants and genetic resources conservation is also emphasized.     

The use of muscle protein for egg production in the Zebra Finch Taeniopygia guttata

Pectoral muscle can be an important source of protein for birds. During egg formation Zebra Finches Taeniopygia guttata are able to compensate for nutritional inadequacies in their diet by utilization of the protein in their flight muscles. This analysis of flight muscle sarcoplasm supported earlier observations of protein depletion during egg production. However, SDS gel electrophoresis of the sarcoplasm produced no evidence to support a previous suggestion of the existence of a high molecular weight storage protein, and it is thought that the original observation may have arisen as an artefact of experimental methodology. During laying, protein removal from the sarcoplasm occurred over a range of different proteins and was not confined to any one specific protein band. Additionally, the protein band most reduced over the course of laying did not contain elevated levels of the amino acids most limiting to egg production. These results indicate that during laying, flight muscle sarcoplasm contributes towards the nutrient requirements of egg production from general protein reserves, rather than from a specific storage protein containing elevated levels of limiting amino acids.     

Control of obstacle climbing in the cockroach, Blaberus discoidalis. I. Kinematics

An advantage of legged locomotion is the ability to climb over obstacles. We studied deathhead cockroaches as they climbed over plastic blocks in order to characterize the leg movements associated with climbing. Movements were recorded as animals surmounted 5.5-mm or 11-mm obstacles. The smaller obstacles were scaled with little change in running movements. The higher obstacles required altered gaits, leg positions and body posture. The most frequent sequence used was to first tilt the front of the body upward in a rearing stage, and then elevate the center of mass to the level of the top of the block. A horizontal running posture was re-assumed in a leveling-off stage. The action of the middle legs was redirected by rotations of the leg at the thoracal-coxal and the trochanteral-femoral joints. The subsequent extension movements of the coxal-trochanteral and femoral-tibial joints were within the range seen during horizontal running. The structure of proximal leg joints allows for flexibility in leg use by generating subtle, but effective changes in the direction of leg movement. This architecture, along with the resulting re-direction of movements, provides a range of strategies for both animals and walking machines.