Effect of the calmodulin inhibitor R24571 (calmidazolium) on rat embryos cultured in vitro

Summary The possible effects of inhibition of the calcium-binding protein, calmodulin, on mammalian morphogenesis have been investigated by culturing rat embryos in vitro from 9 1/2 to 11 1/2 days of development in the presence of R24571 (calmidazolium), a specific inhibitor of calmoldulin. Embryos cultured in 10^–2 mM R24571 for 48 h show inhibited development and exhibit a range of morphogenetic abnormalities including assymetry and neural tube defects. Embryos exposed to R24571 for the first 24 h of a 48 h culture are more severely affected than embryos exposed to R24571 for the last 24 h.Acknowledgments. We wish to thank Mr C. Veltkamp and Mr B. lewis for their expert help with the scanning electron microscopy and photography.     

Plurality in the determinism of organophosphorus teratogenic effects (author's transl)]

In Quail embryos, nicotinamide prevents beak and legs abnormalities produced by bidrin but remains inefficient against vertebral defects induced by bidrin and parathion. In contrast, the vertebral deficiencies are greatly alleviated or abolished by pralidoxim, an antidote known and used in organophosphorus intoxications. From these observations, a plurality in the determinism of teratogenic effects induced by organophosphorus compounds is evident.     

Pluralité dans le déterminisme des effets tératogènes des composés organophosphorés

Summary In Quail embryos, nicotinamide prevents beak and legs abnormalities produced by bidrin but remains inefficient against vertebral defects induced by bidrin and parathion. In contrast, the vertebral deficiencies are greatly alleviated or abolished by pralidoxim, an antidote known and used in organophosphorus intoxications. From these observations, a plurality in the determinism of teratogenic effects induced by organophosphorus compounds is evident.     

Selective antagonism by Mg2+ of amino acid-induced depolarization of spinal neurones.

In the isolated frog or rat spinal cord, low concentrations of Mg2+ (0.5-1.00 mM) markedly depress, in a substantially Ca2+-independent manner, ventral root depolarizations produced by dorsal root stimulation and by certain amino acids (e.g. N-methyl-D-aspartate and L-homocysteate) but do not depress depolarizations produced by other excitatory amino acids (e.g. kainate and quisqualate). L-Aspartate-induced depolarizations are more sensitive to Mg2+ then are L-glutamate-induced depolarizations.     

Selective antagonism by Mg2+ of amino acid-induced depolarization of spinal neurones

Summary In the isolated frog or rat spinal cord, low concentrations of Mg²⁺ (0.5–1.00 mM) markedly depress, in a substantially Ca²⁺-independent manner, ventral root depolarizations produced by dorsal root stimulation and by certain amino acids (e. g. N-methyl-D-aspartate and L-homocysteate) but do not depress depolarizations produced by other excitatory amino acids (e. g. kainate and quisqualate). L-Aspartate-induced depolarizations are more sensitive to Mg²⁺ then are L-glutamate-induced depolarizations.Acknowledgment. We thank D. J. Oakes for skilled technica assistance. This work was supported by the Medical Research Council.     

Effects of streptozotocin on early rat embryos grown in culture

Summary Addition of 1 mg/ml streptozotocin to serum in which 10-day rat embryos are cultured reduces their growth and viability. There is therefore a risk that administration of this drug to pregnant animals to induce diabetes could also have direct, deleterious effects on the embryos.     

Effects of streptozotocin on early rat embryos grown in culture.

Addition of 1 mg/ml streptozotocin to serum in which 10-day rat embryos are cultured reduces their growth and viability. There is therefore a risk that administration of this drug to pregnant animals to induce diabetes could also have direct, deleterious effects on the embryos.     

Choice of a spin label probe in order to study the recombination of beta-hydroxybutyrate dehydrogenase of a rat liver inner mitochondrial membrane with lecithin vesicles]

We find from studying the inhibitory effect of N-ethylmaleimide (NEM) on the enzymatic activity of beta-hydroxybutyrate dehydrogenase, that approximately one molecule of NEM is bound for one molecule of protein when the enzymatic activity is completely inhibited. Since the protein is a dimer this implies that each molecule of protein possesses only one thiol group in its catalytic center. Two long chain maleimide derivates: (10.3) NEM and (1.14) NEM conform, if a reasonable assumption is accepted to the conditions required for the study of the recombination of beta-hydroxybutyrate dehydrogenase with lecithin vesicles by spin label technique.     

In vitro development of rat embryos obtained from diabetic mothers

Rat embryos of 9.5 or 10 days of gestation were removed from control or streptozotocin-diabetic mothers and cultured in normal rat serum (180 mg% glucose) or in diabetic serum (600 mg% glucose). The development of control embryos in normal serum was adequate. Embryos from normal mothers cultured in diabetic serum showed signs of developmental retardation. The development of embryos obtained from diabetic mothers was severely impaired, regardless of the gestational age or the culture medium. These results suggest that a diabetic maternal milieu produces irreversible effects in the embryo very early in gestation.     

Further characterization of the effects of ultraviolet irradiation of the amphibian egg

UV-irradiation of the vegetal hemisphere of amphibian eggs leads to developmental abnormalities in neural morphogenesis. The possibility that the egg's transient sensitivity to irradiation could be due to pigmentation changes was examined in albino eggs. The tissue specificity of the effects of irradiation was analyzed by exchanging the ectoderm between irradiated and control embryos.     

Human serum as a culture medium for rat embryos

A comparison was made between the development of post-implantation rat embryos in human serum and rat serum. Protein synthesis (growth) and somite number (differentiation) were retarded in human serum and there was an increased frequency of neural tube defects. Male and female human sera supported development equally well.     

Human serum as a culture medium for rat embryos

Summary A comparison was made between the development of post-implantation rat embryos in human serum and rat serum. Protein synthesis (growth) and somite number (differentiation) were retarded in human serum and there was an increased frequency of neural tube defects. Male and female human sera supported development equally well.     

Postimplantation embryo culture for the assessment of the teratogenic potential and potency of compounds

Whole rat embryos cultured during the early stages of organogenesis were subjected to a panel of selected chemicals. Of seventeen known in vivo teratogens, seventeen also induced specific malformations in embryos grown in culture. Of ten chemicals which were reported to be negative in in vivo rat teratogenicity studies, eight also did not provoke dysmorphogenic effects in vitro. Of five additionally tested retinoids, all induced multiple malformations. However, concentrations used to induce these effects varied considerably, isotretinoin inducing malformations at 10(-5) M and arotinoid at 10(-11) M. The results indicate qualitatively as well as quantitatively a high predictability of this in vitro system and suggest that the postimplantation embryo culture system may also be useful in the prospective testing of new drugs and environmental chemicals.     

Befunde aus der Frühentwicklung des Rattenkeimes als Beitrag zur Rhythmik der Entwicklung

Summary On the fourth day of development of the rat embryo all of the stages are found from the two-cell stage to the blastocele stage even among embryos from the same litter. On the seventh day, they all show egg-cylinder stages without exception. The time interval between cleavages from the second to the sixth day of development is not constant and, in fact, varies over a wide range, even among embryos from the same litter.     

The effect of 5-bromodeoxyuridine on mouse embryos during neurulation in vitro

Mouse embryos explanted at various stages during neurulation were cultured for 20-28 h in the presence of 25-900 micrograms/ml of 5-bromodeoxyuridine (BUdR). BUdR strongly inhibited closure of the cranial neural tube, which was found to be stage-dependent. When mouse embryos were exposed to BUdR after development of the concave curvature in the neuroepithelium of the midbrain to the upper hindbrain regions, they became insensitive to the drug-induced open cranial neural tube. Histological observations showed that BUdR interfered with interkinetic migration and cytokinesis of the neuroepithelial cells. These cellular abnormalities were not dependent on the morphological development of the cranial neural folds. The 3H-BUdR experiment confirmed that the label was mostly incorporated into the DNA fraction.     

Postimplantation embryo culture for the assessment of the teratogenic potential and potency of compounds

Summary Whole rat embryos cultured during the early stages of organogenesis were subjected to a panel of selected chemicals. Of seventeen known in vivo teratogens, seventeen also induced specific malformations in embryos grown in culture. Of ten chemicals which were reported to be negative in in vivo rat teratogenicity studies, eight also did not provoke dysmorphogenic effects in vitro. Of five additionally tested retinoids, all induced multiple malformations. However, concentrations used to induce these effects varied considerably, isotretinoin inducing malformations at 10^–5M and arotinoid at 10^–11M. The results indicate qualitatively as well as quantitatively a high predictability of this in vitro system and suggest that the postimplantation embryo culture system may also be useful in the prospective testing of new drugs and environmental chemicals.     

Transfer of fresh and frozen-thawed rabbit embryos to produce live young

Live rabbits for immunological experiments were produced by transfer of fresh or frozen-thawed embryos. The transfer of 505 fresh embryos and 55 frozen-thawed embryos resulted in 141 young born alive, 81 of which lived between several months and several years. The control group consisted of 55 litters from natural matings. About 70% of the live-born rabbits of natural mating and 55% of the young delivered by embryo transfer survived for more than eight weeks. Average litter sizes were 5.7, 3.7 and 2.2 for naturally mated females, fresh embryo transfer recipients, and frozen-thawed recipients, respectively.     

A simple method for determination of the proportion of 2C and 4C cells in a dormant embryo

Summary Pea embryos grown in the presence of 2.5 mM hydroxyurea from the beginning of imbibition showed a mitotic peak the height of which was considerably less than that of the control, material. Soon after the mitotic peak, there was a complete cessation of mitosis in the treated material. The extent of suppression of mitosis during the first post-dormancy cell cycle caused by hydroxyurea has been used to obtain an estimate of the relative proportion of 2C and 4C cells in the embryo.     

Net ATP synthesis by running the red cell calcium pump backwards.

Ca2+ loaded inside-out vesicles from human red blood cells, yielding C2+ into a Ca2+ free medium with 4 mM EGTA, 2 mM ADP and 10 mM phosphate, produced an excess of 14.9 pmoles . min-1 . (mg protein)-1 of ATP compared to controls in which the transmembrane Ca2+ gradient was abolished by the ionophore A 23 187.     

A note on the mechanism of action of UV-irradiation of amphibian embryos

The actions on amphibian embryos of UV-irradiation, exposure to Li+ or exposure to ouabain show interesting parallels with their effects on spontaneous release at the presynaptic terminals of the neuromuscular junction. It is suggested that these treatments serve to raise intracellular Ca2+ ([Ca2+]i) in these examples, and that UV-promoted abnormalities in embryogenesis are a consequence of changes in [Ca2+]i at critical stages in development.