Galina A. Klevezal

Patterns and Calibration of Layering in Tooth Cementum of Female Northern Elephant Seals, Mirounga angustirostris

Incremental layers in hard structures have been used in a variety of mammals to estimate age and timing of reproductive events and to document growth patterns and life-history parameters. We studied the patterns of layering in cementum of cross-sections of canine teeth from 28 females of the northern elephant seal ( Mirounga angustirostris ) and calibrated patterns of growth with tooth sections from seals of known age. All teeth were obtained from seals that died from natural causes on rookeries in California. Two complex growth-layer groups of cementum are deposited during early life in females and one growth-layer group is deposited thereafter. We believe that the change in the rate of deposition of growth-layer groups of cementum indicates sexual maturity.

Reconstruction of individual life histories of rodents from their teeth and bone

Age changes of bone tissue and molar cementum, and formation of daily layers in dentin of incisors enable us to estimate age and maximum lifespan, season of birth, season of death, sexual maturation, sex in adults, and in combination with tetracycline prebaiting, movements and space distribution of rodents. In hibernating rodents, the hibernation zone formed in incisor dentin can be used to assess inter- and intrapopulation variations in seasonal activity and growth. This approach is illustrated by examples from the study of rodents of the generaApodemus andSicista.

Dynamics of radionuclide concentrations in calcified tissues of reindeer in the western Russian Arctic.

The specific activities of artificial and natural nuclides were determined in bone and teeth of reindeer that had lived before, during, and after nuclear tests on the Archipelago Novaya Zemlya and of reindeer from the nearby mainland region. In bone of reindeer from Novaya Zemlya, 90Sr and 210Pb are the main source of beta-activity, the 210Po is the main source of the alpha activity. In bone of reindeer that lived on Novaya Zemlya during underground tests, the 90Sr activity was relatively high (0.75 +/- 0.20 Bq/g dry weight). In animals that lived after the tests were banned, the level was significantly lower (0.44 +/- 0.17 Bq/g) and did not differ from the level of the 90Sr activity found in the mainland reindeer bone. On Novaya Zemlya, the concentrations of the natural 210Pb in bone of the recent reindeer (0.57 +/- 0.19 Bq/g) is similar to that which was in the teeth of reindeer a hundred years ago (0.65-0.75 Bq/g) and significantly higher than in the recent mainland reindeer from different regions (0.18-0.17 Bq/g).

Retrospective Estimation of Radiation Load and Its Effect on Some Biological Parameters of Reindeer (Rangifer tarandus) from Wrangel Island

The results of the electron paramagnetic resonance (EPR) analysis of pure tooth enamel and the data on the radionuclide content in bones were used for estimating the radiation load on reindeer that lived on Wrangel Island in the 1970s and early 1980s. Based on the measurements of the lower jaws, some biological parameters of the Wrangel reindeer population were estimated and compared with those in the Novaya Zemlya and Taimyr populations. Changes in only two of these parameters—the degree of root cementum resorption and animal life span–might be attributed to the effect of the radiation load.