Telomere Distribution in Human Sperm Heads and Its Relation to Sperm Nuclear Morphology: A New Marker for Male Factor Infertility?

Infertility is a problem affecting an increasing number of couples worldwide. Currently, marker tests for male factor infertility are complex, highly technical and relatively subjective. Up to 40% of cases of male factor infertility are currently diagnosed as idiopathic therefore, there is a clear need for further research into better ways of diagnosing it.

Direct Single-Cell Analysis of Human Polar Bodies and Cleavage-Stage Embryos Reveals No Evidence of the Telomere Theory of Reproductive Ageing in Relation to Aneuploidy Generation.

Reproductive ageing in women, particularly after the age of 35, is associated with an exponential increase in the proportion of chromosomally abnormal oocytes produced. Several hypotheses have attempted to explain this observation, including the 'limited oocyte pool' hypothesis and the 'two-hit' hypothesis, the latter explaining that a depletion in oocyte quality with age results from the multiple opportune stages for errors to occur in meiosis. Recently however, the telomere theory of reproductive ageing in women has been proposed.

Telomere Biology and Human Phenotype.

Telomeres are nucleoprotein structures that cap the end of each chromosome arm and function to maintain genome stability. The length of telomeres is known to shorten with each cell division and it is well-established that telomere attrition is related to replicative capacity in vitro. Moreover, telomere loss is also correlated with the process of aging in vivo.

Karyomapping for simultaneous genomic evaluation and aneuploidy screening of preimplantation bovine embryos: The first live-born calves.

In cattle breeding, the development of genomic selection strategies based on single nucleotide polymorphism (SNP) interrogation has led to improved rates of genetic gain. Additionally, the application of genomic selection to in-vitro produced (IVP) embryos is expected to bring further benefits thanks to the ability to test a greater number of individuals before establishing a pregnancy and to ensure only carriers of desirable traits are born. However, aneuploidy, a leading cause of developmental arrest, is known to be common in IVP embryos.

Preterm infants have significantly longer telomeres than their term born counterparts.

There are well-established morbidities associated with preterm birth including respiratory, neurocognitive and developmental disorders. However several others have recently emerged that characterise an 'aged' phenotype in the preterm infant by term-equivalent age. These include hypertension, insulin resistance and altered body fat distribution.

Multicolor detection of every chromosome as a means of detecting mosaicism and nuclear organization in human embryonic nuclei.

Fluorescence in-situ hybridization (FISH) revolutionized cytogenetics using fluorescently labelled probes with high affinity with target (nuclear) DNA. By the early 1990s FISH was adopted as a means of preimplantation genetic diagnosis (PGD) sexing for couples at risk of transmitting X-linked disorders and later for detection of unbalanced translocations. Following a rise in popularity of PGD by FISH for sexing and the availability of multicolor probes (5-8 colors), the use of FISH was expanded to the detection of aneuploidy and selective implantation of embryos more likely to be euploid, the rationale being to increase pregnancy rates (referral categories were typically advanced maternal age, repeated IVF failure, repeated miscarriage or severe male factor infertility).

Use of suboptimal sperm increases the risk of aneuploidy of the sex chromosomes in preimplantation blastocyst embryos.

Objective: To compare autosomal and sex chromosome aneuploidy rates of embryos derived from sperm with abnormal and normal parameters.

Design: Retrospective cohort study.

Setting: Assisted reproduction center.

Telomere length analysis and preterm infant health: the importance of assay design in the search for novel biomarkers.

Preterm infants develop an 'aged' phenotype in comparison with term-born infants, one component of which is adverse metabolic health and, therefore, long-term health follow-up is warranted to identify morbidity. In light of this, the identification and use of biomarkers to aid with prognosis would be a welcome development. Telomeres are repeat sequences at the ends of each chromosome arm known to shorten as a consequence of cellular aging, and in relation to several disease conditions.

The quorum-sensing molecules farnesol/homoserine lactone and dodecanol operate via distinct modes of action in Candida albicans.

Living as a commensal, Candida albicans must adapt and respond to environmental cues generated by the mammalian host and by microbes comprising the natural flora. These signals have opposing effects on C. albicans, with host cues promoting the yeast-to-hyphal transition and bacteria-derived quorum-sensing molecules inhibiting hyphal development.