Energy balance of hibernating mouse-eared batMyotis myotis: a study with a TOBEC instrument

We used a non-invasive TOBEC method (Total Body Electric Conductivity) to estimate lean body mass and fat content in mouse-eared batsMyotis myotis (Borkhausen, 1797) hibernating in Poznañ Forts (W Poland) and in a semi-natural cave-mine Miedzianka (SE Poland). In December, fat content averaged 5.5 g in females (body mass = 29.4 g) and 5.3 g in males (body mass = 28.4 g). At the end of hibernation (April), fat content averaged 2.2 g in females (body mass = 25.6 g) and 1.4 g in males (body mass = 23.7 g). Fat content did not differ between the localities either in December or in April, but the pattern of changes of fat content was different. We calculated the rate of energy expenditure in hibernating bats using two methods, based on independent samples (fat content in first-time captured individuals) and based on paired observations (changes of fat content in re-captured individuals), and discussed problems associated with the two approaches. Both methods show that the bats need about 4.9 g of fat (191 kJ) to sustain a 165-day hibernation. However, the rate of fat usage varied considerably between the sites and hibernation phase. Although the average amount of fat remaining in April would be sufficient to support at least six more weeks of hibernation, the level of reserves was close to zero in some individuals.     

Ein Beitrag zur Flora Galiziens und der Bukowina

Ohne Zusammenfassung     

Ein Beitrag zur Moosflora von Bosnien

Ohne Zusammenfassung     

The Analysis of Partial Diallel Crosses

The analysis of offsprings from the partial diallel crosses is presented. In considered type of crossing, p parental forms into H separate groups are devided. Single crosses among parental forms, from separate groups only, are performed. The analysis for experiments laid out in efficiency balanced block designs is given.     

Bioelectrorheological model of the cell. 5. Electrodestruction of cellular membrane in alternating electric field.

Recently proposed analysis of the extensil stress developed in a cellular membrane subjected to an alternating electric field (Pawłowski, P., and M. Fikus, 1993. Bioelectrorheological model of the cell. 4. Analysis of the extensil deformation of the membrane in an alternating field. Biophys. J. 65:535-540) was applied in calculations of extensil stress threshold values, sigma eo[d], producing experimentally observed electrodestruction of cells within the frequency range of 7 x 10(1) - 3 x 10(5) Hz. It was shown that the susceptibility (s[d] = 1/sigma eo[d]), of the membrane to this process varies with field frequency and depends on the type of cells. Electrodestruction is facilitated in the 10(5)-Hz field. A rheological hypothesis explaining the experimentally observed dependence of membrane stability on electric field frequency was proposed and successfully tested for two other phenomena: electroporation and electrofusion.     

Induction of betaine: Homocysteine methyltransferase in some murine cells cultured in vitro

Betaine when present in the culture medium could induce the activity of betaine: homocysteine methyltransferase (EC 2.1.1.5) in mouse L-cells, and leukemic L1210 cells, as well as in mouse embryo fibroblasts grown in vitro. We found this process to be time- and concentration-dependent. A persisting contact of the cells with betaine was indispensible for expressing and maintaining the enzyme activity. The treatment of cells with cycloheximide or actinomycin D abolished the process of induction. Methionine as well as homocysteine, when present either in the culture medium or in the reaction mixture, strongly depressed the activity of this enzyme. The L-cells with the induced betaine: homocysteine methyltransferase survived but did not multiply in the methionine-deficient medium, therefore, they did not become prototrophs with respect to methionine.