Analysis of Local Dandelion (Taraxacum officinales.l.) Cenopopulations from Radioactively Contaminated Zones

Local dandelion (Taraxacum officinales.l.) populations were studied in the areas of the Eastern Ural Radioactive Trace and the floodplain of the Techa River in its upper reaches. In impact plots, the density of soil and plant cover contamination with ⁹⁰Sr and ¹³⁷Cs exceeded the background level by factors of 13–440 and 2–500, respectively; the radiation load exceeded the background level by factors of 1.5 to 45. The seed progeny of plants from these plots was characterized by a high proportion of abnormal seedlings and an increased level of chromosome aberrations in meristem cells. In some years, variation in the seedling viability, growth rate, and developmental rate in these plots exceeded the reaction norm of plants from the background plot, demonstrating both stimulation and inhibition of growth processes. The response of seeds to acute irradiation at high challenging doses varied depending on the level of background radiation in the plots.     

Cooperatively breeding superb fairy-wrens show no facultative manipulation of offspring sex ratio despite plausible benefits

We report a long-term study of offspring sex ratios in the cooperatively breeding superb fairy-wren Malurus cyaneus. Detailed study of this species had revealed a suite of potentially strong selection pressures on the sex ratio. First, females gain substantial fitness benefits from the presence of helpers; so females without male helpers would benefit from any strategy that increased the probability of recruiting help, such as overproduction of sons (local resource enhancement hypothesis), but large numbers of helper males compete among themselves, favouring the production of daughters (local resource competition). Second, daughters fledged early in the season have far greater chances of recruitment to the breeding population than late-fledged daughters, so mothers would benefit from production of daughters early in the breeding season (early bird hypothesis). Third, extra-group mate choice imposes strong sexual selection on males, suggesting that females mating with attractive sires could benefit from investing in sons (sexual selection hypothesis). However, the predictions from these and other sex ratio hypotheses were rejected. The only convincing evidence for manipulation of the sex ratio was a slight bias towards sons (11 sons to 10 daughters) that occurred regardless of context. This result does not support current theory.     

Double-outlet right ventricle with absent left ventricle and mitral atresia in a fetus with a deletion 22q12

Interstitial deletions of chromosomal region 22q12 are rare. We report the prenatal diagnosis of a de novo interstitial deletion 22q12. The fetus was karyotyped because of a complex cardiac anomaly. Conventional and molecular cytogenetics showed a female karyotype with a de novo pericentric inversion of one chromosome 22 associated with a deletion of the chromosomal region 22q12 leading to a partial monosomy 22q12. At autopsy, the fetus showed double-outlet right ventricle (DORV) with absent left ventricle and mitral atresia. This observation suggests that one or several genes for the early looping step of heart development may reside in chromosomal region 22q12. Further studies are needed to identify these genes, and to search microdeletions of 22q12 region in patients with DORV. Copyright © 2004 John Wiley & Sons, Ltd.     

Attitudes towards sex selection in the Western world

It appears that in most Western countries, son preference is somewhat stronger than daughter preference. However, when one considers the preference of women it looks as though the opposite pattern is emerging. There is a considerable social acceptance of ‘light’ methods of sex selection (such as diets), even though these methods are not proven to be effective. The inclination to use sperm separation methods appears to be greater in the United States than in some European countries. There are indications that a preference for boys or for girls is associated with attitudes towards technology, child-rearing style and the stereotyping of boys or girls. Copyright © 2006 John Wiley & Sons, Ltd.     

Prenatal diagnosis and characterization of an analphoid marker chromosome 16

We report on a fetus with intrauterine growth retardation and multiple malformations diagnosed on ultrasound at 32 weeks. Examination of amniotic fluid cells in culture showed a 47,XY, i(16)(q10), +mar karyotype. Chromosome analysis of both parents was normal. Using spectral karyotyping, we identified the marker chromosome as a mitotically stable acentric marker chromosome derived from chromosome 16. Further studies using subtelomeric fluorescent probes confirmed the presence of an isochromosome for the long arm of chromosome 16 and showed that the acentric marker chromosome derived from the short arm of chromosome 16 leading to a trisomy for the long arm of chromosome 16. After genetic counseling, the parents decided to terminate the pregnancy. Fetal autopsy showed a male fetus with ambiguous external genitalia, cardiac malformation, megacystis and limbs anomalies as observed in other cases of trisomy for the long arm of chromosome 16. In addition, fetal brain examination showed vermian and olfactory bulb hypoplasia. Copyright © 2004 John Wiley & Sons, Ltd.     

Anomalies of mouthparts in Rana arvalis Nilss tadpoles and ecological conditions providing for their emergence

Rana arvalis tadpoles reared under natural or experimental conditions have been studied to analyze anomalies in the development of mouthparts and to compile a catalog of corresponding characters. It has been shown that the frequency of these anomalies increases in the course of growth and development and that their manifestations differ in tadpoles from different spawns and depend on environmental conditions. In turn, anomalies of the mouthparts have an effect on the rate of larval growth and development and on the survival of tadpoles in the period of the metamorphic climax. The results of this study provide an explanation for some deviations observed in laboratory experiments.