Analysis of Cyp26b1/Rarg compound-null mice reveals two genetically separable effects of retinoic acid on limb outgrowth

The role of retinoic acid (RA) in limb development is unclear, although it has been suggested to be a proximalizing factor which plays a morphogenetic role in pattern formation. Exogenous RA produces a teratogenic effect on limb morphology; similarly, changes in the endogenous distribution of RA following genetic ablation of the RA-metabolizing enzyme, CYP26B1, result in phocomelia accompanied by changes in expression of proximo-distal (P-D) patterning genes, increased cell death, and delayed chondrocyte maturation. Here we show that disruption of RA receptor (RAR) gamma in a Cyp26b1^−/− background is able to partially rescue limb skeletal morphology without restoring normal expression of proximo-distal patterning genes. We further show that embryos deficient in CYP26B1 exhibit early localized domains of mesenchymal cell death, which are reduced in compound-null animals. This model reveals two genetically separable effects of RA in the limb: an apoptotic effect mediated by RARγ in the presence of ectopic RA, and a P-D patterning defect which is uncovered following the loss of both CYP26B1 and RARγ. These data provide genetic evidence to clarify the roles of both RA and CYP26B1 in limb outgrowth and proximo-distal patterning.     

Limb reduction defects in the first generation and deafness in the second generation of intrauterine exposed fetuses to diethylstilbestrol

Maternal treatment with diethylstilbestrol (DES) during pregnancy can produce vaginal adenocarcinoma and other abnormalities of the vagina in her daughters when they reach adolescence or adulthood, miscarriages and absence of full term infants. Concerning malformations in newborns whose mothers were treated with DES, clitoromegaly and malformations of the uterus were reported in females and genital lesions in males. However, the frequencies of major congenital anomalies were not greater than expected. We report three cases of limb reduction defects (LRD) in the first generation of children whose mothers were treated with DES during pregnancy, and two children (one male, one female) with deafness in the second generation after intrauterine exposure to DES. The LRD were not associated with other congenital anomalies. The malformed children with LRD were born between 1965 and 1973. The deafness was also isolated. The two mothers who have no hearing problems and who are healthy were exposed in utero to DES in 1963 and 1965, respectively. Their children were born in 1989 and 1994, respectively. In conclusion, the association of LRD and hearing loss with intrauterine exposure to DES could be coincidental. However, some hypothesis may explain these associations. Congenital hearing loss in the second generation may suggest a transgenerational effect.     

Quantification of risk from fetal exposure to diagnostic ultrasound

Biomedical ultrasound may induce adverse effects in patients by either thermal or non-thermal means. Temperatures above normal can adversely affect biological systems, but effects also may be produced without significant heating. Thermally induced teratogenesis has been demonstrated in many animal species as well as in a few controlled studies in humans. Various maximum ‘safe’ temperature elevations have been proposed, although the suggested values range from 0.0 to 2.5° C. Factors relevant to thermal effects are considered, including the nature of the acoustic field in situ, the state of perfusion of the embryo/fetus, and the variation of sensitivity to thermal insult with gestational stage of development. Non-thermal mechanisms of action considered include acoustic cavitation, radiation force, and acoustic streaming. While cavitation can be quite destructive, it is extremely unlikely in the absence of stabilized gas bodies, and although the remaining mechanisms may occur in utero, they have not been shown to induce adverse effects. For example, pulsed, diagnostic ultrasound can increase fetal activity during exposure, apparently due to stimulation of auditory perception by radiation forces on the fetal head or auditory structures. In contrast, pulsed ultrasound also produces vascular damage near developing bone in the late-gestation mouse, but by a unknown mechanism and at levels above current US FDA output limits. It is concluded that: (1) thermal rather than nonthermal mechanisms are more likely to induce adverse effects in utero, and (2) while the probability of an adverse thermal event is usually small, under some conditions it can be disturbingly high.     

基因重组人碱性成纤维细胞生长因子的遗传毒性研究

用Ames试验、CHL细胞染色体畸变试验、小鼠骨髓PCE微核试验和小鼠致畸试验对基因重组人碱性成纤维细胞生长因子（rh-bFGF)进行研究。结果显示,rh-bFGF(0.1～500μg/皿）对TA97、TA98、TA100和TA102菌株在±S9mix条件下无致突变作用。各剂量组的微核细胞率与溶剂组比较,P>0.05。4个剂量组CHL细胞染色体畸变率均<5％。在妊娠母鼠6～15d P0给药,各剂量组活胎率90.2％～95.9％,与溶剂组95％比较,P>0.05。对胎鼠外观、骨骼和内脏无致畸作用。但0.03264mg/kg b.w吸收胎与溶剂组比较,P<0.01,显示一定的胚胎毒性。 Abstract: The genotoxicity of recombinant human basic fibroblast growth factor(rh-bFGF)was studied by Ames test,Chromosome aberration assay of mammalian cell(CHL)in vitro,mouse marrow micronucleus assay and teratogenesis assay.The results showed that rh－bFGF at the dose level of(0.1～500μg/plate)did not induce positive mutations in TA97,TA98,TA100,TA102 with or without S9mix of Ames test.It was control within the range(<5％)of chromosome aberration rates from rh-bFGF with 4 doses groups with or without S9min.The frequency of mouse micronuleus rate had no increase.It was divided into each groups of rh?bFGF received(p.o)dosages the 6th to 15 day of gestation mouse respectively in the teratology test.The frequency of live fetuses of each dose was between 90.2～95.9％,there were no significant difference as compared with 95％ of solution control group.It did not cause deformity of the fetus appearances,bone and internal organs.But there were significant differences from solution control in rf-bFGF group of absorfoetus at 0.03264mg/kg(P<0.01).The results showed certainly dembyotoxicity.     

Moderate Prenatal Alcohol Exposure and Quantification of Social Behavior in Adult Rats

Alterations in social behavior are among the major negative consequences observed in children with Fetal Alcohol Spectrum Disorders (FASDs). Several independent laboratories have demonstrated robust alterations in the social behavior of rodents exposed to alcohol during brain development across a wide range of exposure durations, timing, doses, and ages at the time of behavioral quantification. Prior work from this laboratory has identified reliable alterations in specific forms of social interaction following moderate prenatal alcohol exposure (PAE) in the rat that persist well into adulthood, including increased wrestling and decreased investigation. These behavioral alterations have been useful in identifying neural circuits altered by moderate PAE¹, and may hold importance for progressing toward a more complete understanding of the neural bases of PAE-related alterations in social behavior. This paper describes procedures for performing moderate PAE in which rat dams voluntarily consume ethanol or saccharin (control) throughout gestation, and measurement of social behaviors in adult offspring.     

Reproductive and developmental responses in the self-fertilizing fish,Rivulus marmoratus,induced by the plasticizer,di-n-butylphthalate

Synopsis Specialized life-history attributes of the cyprinodontiform fish, Rivulus marmoratus, allow continuous life cycle testing to reveal effects of chemicals or environmental stresses upon fertilization, fecundity, egg viability, embryonic development, sex ratios, frequency of growth or skeletal anomalies, as well as other biological markers. This study reports responses in fecundity, viability of embryos, and skeletal anomalies during and after exposure of parental fish to the plasticizer, di-n-butylphthalate (DBP). Skeletal anomalies among offspring were classified as mild, moderate, or severe compared with non-deformed normal offspring. The frequency of skeletal anomalies increased from 4% (all categories combined) in controls, to 10% and 19% of the offspring from adults exposed to 1 and 2 mg I^-1 DBP, respectively. DBP treatment was conducted over a 21 week interval, followed by a 9 week post-treatment observation interval. During post-treatment, frequency of skeletal anomalies decreased to less than 5% in all groups. Contributions No. 610, Environmental Research Laboratory, Gulf Breeze, Florida 32561 U.S.A. The information in this document has been funded wholly by the U.S. Environmental Protection Agency, and has been subjected to the Agency's peer and administrative review. Mention of commercial products or trade names does not constitute the Agency's endorsement or recommendation for use.     

Agents anticholinestérasiques et tératogénèse axiale chez l'embryon de Caille

Résumé Une étude conduite avec des organophosphorés (OP), des carbamates (C) et un produit à groupements oxamides (GO) permet d'établir une corrélation entre l'inhibition des activités cholinestérasiques et l'expression des anomalies de l'axe vertébral chez l'embryon de Caille japonaise. L'action anticholinestérasique des divers composés est étudiée in vitro et in vivo. In vitro, les cholinestérases embryonnaires sont surtout sensibles aux carbamates alors qu'avec les organophosphorés — et notamment avec ceux qui nécessitent une activation métabolique —, des concentrations élevées n'aboutissent qu'à des inhibitions partielles des activités enzymatiques envisagées. In vivo, des produits étudiés, seuls le malathion (OP) et l'ambénonium (GO) se montrent inactifs (ou faiblement actifs) vis-à-vis des cholinestérases. Bien qu'assez fortement embryotoxiques, ces deux poisons ne se révèlent pas tératogènes. Les autres produits, administrés à des doses tératogènes, inhibent toujours très fortement les activités cholinestérasiques. L'association satisfaisante existant entre l'inhibition des cholinestérases et l'expression des malformations axiales est confirmée par l'usage de doses croissantes de parathion (OP) et de néostigmine (C).Les anomalies du bec et des pattes, ne se manifestant qu'avec le dicrotophos (OP) et l'ésérine (C), n'apparaissent pas, quant à elles, reliées à l'inactivation des cholinestérases, puisqu'elles ne sont pas relevées avec des composés aussi actifs à l'égard de ces enzymes que le parathion (OP), la néostigmine (C) et le démécarium (C).

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Anticholinesterase agents and axial teratogenesis in quail embryos

Summary The results of an investigation made with organo-phosphorous compounds (OP), carbamates (C), and a compound including oxamide groups (GO), indicate that spine anomalies in Japanese quail embryos are linked with cholinesterase inhibition. The blocking effect of these various compounds on cholinesterases has been examined both in vitro and in vivo.In vitro, the embryonic cholinesterases are particularly sensitive to carbamates, whereas high concentrations of organo-phosphorous compounds-and especially those which need to be activated at the level of metabolism-block only part of the relevant activities of the enzyme.In vivo, among the products examined, only malathion (OP) and ambenonium (GO) were found to be inactive (or having little effect) so far as cholinesterases are concerned. Although they appeared rather strongly embryotoxic, these two poisons did not prove teratogenic. A strong inhibition of cholinesterase activities was noticed in all cases, when applying the other compounds at teratogenic doses.The close relationship between the inhibition of cholinesterases and the appearance of axial abnormalities is confirmed by using increasing doses of parathion (OP) and neostigmine (C).Beak and leg malformations were brought about only by dicrotophos and eserine, and did not prove to be linked with cholinesterase inhibition, since they were not observed with compounds having a high activity towards these enzymes, such as parathion (OP), neostigmine (C) and demecarium (C).

Travail dédié à la mémoire du professeur W. Landauer