Osmotic responses of preimplantation mouse and bovine embryos and their cryobiological implications

Cells subjected to the events occurring before, during, and after freezing and thawing are exposed to major changes in the osmotic pressure of the surrounding medium; i.e., the osmolalities can exceed 30. An important question in understanding the mechanisms of injury is whether cells respond as ideal osmometers to these strongly anisotonic solutions. Mouse and bovine embryos from eight-cell to blastocyst stage were used to investigate the question. They were found to behave as ideal osmometers at room temperature over a wide range of tonicities; i.e., from four times isotonic to almost 1/3 times isotonic, ideality being defined by a Boyle-van't Hoff equation. Embryo volumes increased from 40 to 200% of isotonic over this range and survivals of mouse embryos were unaffected. However, outside this range the membrane apparently becomes leaky and the survival of mouse embryos drops sharply. Osmolalities rise to high values during freezing and the paper develops the thermodynamic equations to show how computed cell volumes as a function of subzero temperature can be translated into the Boyle-van't Hoff format of cell volume as a function of the reciprocal of osmolality.     

Intrinsic oxygen affinity of hemoglobins: the hemoglobin of bisons (Bison bonasus,Bovidae)

The hemoglobin from a European Bison (Bison bonasus) was analysed and the complete primary structures of the alpha I-, alpha II-and beta-chains have been determined. The alpha I- and alpha II-chains differ only at position alpha 19 (Asp----Gly). The beta-chains are homogeneous. The sequences are compared with the globin chains of Bison bison and bovine and the polymorphism of the alpha-chains is discussed. On the basis of the primary structure it may be concluded that the hemoglobin of Bison bonasus belongs to the group of hemoglobins with intrinsically low oxygen affinity.     

The silkmoth chorion: Morphogenesis of surface structures and its relation to synthesis of specific proteins

The morphogenesis of four spatially differentiated surface regions of the silkmoth eggshell (chorion) has been documented and correlated with differing patterns of chorion protein synthesis within the corresponding secretory cells. During the first half of choriogenesis the polygonal pattern of ridges which cover the entire chorion appears. Regional differences in the morphology of developing ridges are not accompanied by significant protein differences, and thus presumably reflect differences in secretory cell behavior and shape. During the second half of choriogenesis expanding domes of the chorion located immediately beneath three-cell junctions of the overlying secretory surface become prominent surface features exclusively in the aeropyle crown region. Domes are composed of a thin lamellar skin and an inner buttressing “filler.” Continued filler deposition appears to cause a ripping of the lamellar skin, transforming the dome into a multiple-pronged crown that overflows with filler. Continued synthesis of lamellar chorion components elongates and strengthens the crowns until they can stand alone without the support of filler. In the aeropyle crown region, synthesis of regionally specific proteins begins in the second half of choriogenesis and accelerates until the final stages, in parallel with dome/crown formation. The more numerous proteins which are common to all regions are synthesized at approximately equal rates within all regions, and their synthesis decelerates toward the end of choriogenesis. Fifteen of the proteins (excluding filler) which are found predominantly in the aeropyle crown region may be necessary but not sufficient for crown formation, since they also occur in the stripe region (1); presumably the secretory cell surfaces mold the same components differently in the two regions. Filler appears to play an important scaffolding role in crown formation. A group of eight aeropyle crown region-specific chorion proteins which compose filler have been identified on two-dimensional gels and shown to be restricted to one of five previously described classes of chorion proteins.     

Osmotic consequences of cryoprotectant permeability and its relation to the survival of frozen-thawed embryos

The freezing of a living cell involves a complex physicochemical process of heat and water transport between the cell and its surrounding medium. Embryos survive cryopreservation only in the presence of a cryoprotectant in concentrations between 1 and 2M. During the addition and dilution of a permeating cryoprotectant, the cell undergoes osmotic changes in cell size. As a consequence, if the addition or particularly the dilution are carried out inappropriately, the viability of cells can be affected. Equations which model the influx and efflux of cryoprotectants in cells can be used to calculate the optimum and most practical addition and removal method. However, the equations require the permeability coefficient of the cryoprotectant, a quantity that has only experimentally determined for a few of the developmental stages of two species.     

Normal values of peak expiratory flow in children from an environment with high degree of atmospheric air pollution]

Peak expiratory flow (PEF) has been measured with Vitalograph (in liters per minute) in 2,512 school-children aged between 7 and 15 years in Upper Silesian Industrial Region. Five hundred eighty one children from Zarki near Czestochowa served as a control group. The results have been analysed statistically. Determined PEF values for children from the Upper Silesian Industrial Region are considered as a biological reference values for assessment of PEF in both health and disease. PEF values calculated for children from Zarki were higher than those in the examined group, except the value for a 14-year old children.