BACKGROUND Triploidy can occur in many animal species but is often lethal. Among invertebrates, amphibians and fishes, triploids are viable although often sterile or infertile. Most triploids of the Pacific oyster Crassostrea gigas are almost sterile (named "3nβ") yet a low but significant proportion show an advanced gametogenesis (named "3nα"). These oysters thus constitute an interesting mode...

Sexual maturation of rainbow trout during production has a negative effect on the slaughter yields and flesh quality. Induction of triploidy is a method to prevent the development of fertile trout. In many investigations sexually mature triploid and diploid rainbow trout had been compared. In the present study the slaughter characteristics and flesh quality of female immature diploid and triplo...

OBJECTIVE To assess the performance of cell-free DNA (cfDNA) testing in maternal blood for detection of fetal aneuploidy of chromosomes 13, 18, 21, X, and Y using targeted sequencing of single-nucleotide polymorphisms. METHODS Prospective study in 242 singleton pregnancies undergoing chorionic villus sampling at 11 to 13 weeks. Maternal blood was collected before chorionic villus sampling and...

DNA aneuploidy is of interest as an additive marker for carcinoma risk in ulcerative colitis. It is known that colorectal carcinomas often are aneuploid with DNA indices centered around a median value of 1.5, corresponding to triploidy, and that adenomas, if aneuploid, have DNA indices closer to 2.0, the tetraploid region. In a colonoscopic surveillance programme, colorectal mucosal biopsies fr...

The live birth of a triploidy infant is a very rare event and death usually occurs within the first hours of life. Triploid cases with a survival of more than two months are infrequent. We report on an infant with a 69,XXX chromosome constitution who survived 164 days. Chromosomal analysis demonstrated a 69,XXX karyotype with no evidence of mosaicism. This is the longest survival reported for t...

In this work, we study if ploidy (i.e. number of copies of chromosomes) in the oyster Crassostrea gigas may introduce differences in behavior and in its synchronization by the annual photoperiod. To answer to the question about the effect of the seasonal course of the photoperiod on the behavior of C. gigas according to its ploidy, we quantified valve activity by HFNI valvometry in situ for 1 y...

Automixis, the process whereby the fusion of meiotic products restores the diploid state of the egg, is a common mode of reproduction in plants but has also been described in invertebrate animals. In vertebrates, however, automixis has so far only been discussed as one of several explanations for isolated cases of facultative parthenogenesis. Analyzing oocyte formation in F1 hybrids derived fro...

The term “crossing over” is used to denote the exchange of pieces or segments between homologous chromosomes. There are many facts which indicate that the exchange of parts or segments occurs during the first meiotic prophase when the two homologous chromosomes are in intimate association. Prior to 1916 crossing over was thought to take place between the two paired chromosomes before they had d...