Individual differences in sensitivity to context are posited to emerge early in development and to influence the effects of environmental exposures on a range of developmental outcomes. The goal of the current study was to examine the hypothesis that temperament characteristics and biological sex confer differential vulnerability to the effects of exposure to maternal depression on telomere length in early childhood. Telomere length has emerged as a potentially important biomarker of current and future health, with possible mechanistic involvement in the onset of various disease states. Participants comprised a community sample of children followed from infancy to age 3 years. Relative telomere length was assessed from DNA in saliva samples collected at infancy, 2 years, and 3 years. Maternal depressive symptoms and the child temperament traits of negative affectivity, surgency/extraversion, and regulation/effortful control were assessed via maternal report at each timepoint. Analyses revealed a 3-way interaction among surgency/extraversion, sex, and maternal depressive symptoms, such that higher surgency/extraversion was associated with shorter telomere length specifically among males exposed to elevated maternal depressive symptoms. These findings suggest that temperament and sex influence children’s susceptibility to the effects of maternal depression on telomere dynamics in early life.

Aging can be described as the life-long accumulation of damage to the tissues, cells, and molecules of the body. One of the most widely used markers to study biological aging is telomere length. Telomeres are non-coding DNA structures located at the ends of chromosomes that become progressively shorter with age. Research in the past decade showed that persons with psychiatric disorders such as major depressive disorder, anxiety disorder or posttraumatic stress disorder on average have shorter telomeres, which might help explain the high levels of somatic morbidity in these patients. While telomere length is an elegant aging biomarker, reflecting a biological process in most living species, there are also some challenges. In human studies, the between-person variation is large and shortened telomeres showed not to be specific to psychiatric diagnosis but rather to a multitude of psychological and physiological stressors. Telomere length might therefore not be a diagnostic marker. It could, nonetheless, be an interesting target for pharmacological, psychological or exercise treatment. If persons with psychiatric disorders age biologically faster, to what extend can this be process be halted or even reversed with successful treatment? Other opportunities and obstacles of studying telomere length as a biological aging marker in psychiatry will be discussed in this session.

This study examined the link between two biological markers of stress vulnerability at 22–26 years of age and telomere length at 30–35 among extremely low birth weight (ELBW; <1000 g) survivors and normal birth weight (NBW; >2500 g) control participants. Sixteen ELBW and 22 NBW participants provided baseline afternoon salivary cortisol samples and resting frontal electroencephalogram (EEG) alpha asymmetry data at 22–26 years. Buccal cells were assayed for telomere length at 30–35 years. Analyses controlled for sex, postnatal steroid exposure, childhood socioeconomic status, time of cortisol sample collection, and body mass index at 22–26 years. Salivary cortisol and frontal asymmetry at age 22–26 independently predicted telomere length at age 30–35, such that relatively higher cortisol and greater relative right frontal asymmetry at rest predicted telomere shortening among NBW controls, but not among ELBW survivors. However, similar associations were not noted in ELBW survivors, suggesting that ELBW survivors may have different mechanisms of stress coping as a result of their early-life exposures. These findings offer preliminary evidence in support of the role of stress in the genesis of cellular senescence at least among those born at NBW, but that these links may differ in those born preterm.

Several infections have been linked to telomere shortening and in some cases these associations have varied by sex. We assessed the association between seropositivity to four persistent pathogens (cytomegalovirus (CMV), herpes simplex virus-1, Helicobacter pylori, Chlamydia pneumoniae), and total pathogen burden on leukocyte telomere length in a diverse US sample. Data came from the Multi-Ethnic Study of Atherosclerosis, a population-based cohort study. We utilized cross-sectional survey data, and biological samples from participants tested for pathogens and telomere length (N = 163). Linear regression was used to examine the association between seropositivity for individual pathogens as well as total pathogen burden and telomere length, adjusting for various confounders. CMV seropositivity and increased total pathogen burden level were significantly associated with shorter telomere length among females (β = −0·1204 (standard error (s.e.) 0·06), P = 0·044) and (β = −0·1057 (s.e. = 0·05), P = 0·033), respectively. There was no statistically significant association among males. Our findings suggest that prevention or treatment of persistent pathogens, in particular CMV, may play an important role in reducing telomere shortening over the life course among women. Future research is needed to confirm these novel findings in larger longitudinal samples.

Telomeres are specialised nucleoprotein end structures of eukaryotic chromosomes and protect and maintain genome integrity from recombination, exonuclease degradation and end-to-end fusion. Because of the end replication problem, telomere length in somatic cells tends to decrease with organismal age. Telomere shortening is known to occur in chicken somatic tissues and correlates with advanced developmental age. However, age is not the only determinant of telomere length in an individual. Several factors at the genetic and epigenetic levels are known to affect telomere length in different ways. Herein, we review several factors that affect telomere length in the chicken. Genetic factors include breed and sex, while the epigenetic factors include environmental and stochastic influences. Age, stocking density and living or housing systems were reviewed as environmental factors pertaining to the habitat of the organism. Factors such as oxidative stress, antioxidants in feed and restriction feeding were the stochastic factors that we reviewed.

Nuclear DNA of wheat embryos was probed with a synthetic oligonucleotide (C3TA3C3TA3) to assess changes in the length of telomeres during storage and germination. Chromosomal DNA of dry embryos, especially those derived from long-term-stored caryopses, was considerably depleted of telomeric repeats, but, shortly after the start of imbibition, the chromosomal DNA became rich in sequences hybridizing to the telomeric probe. Simultaneously, newly synthesized telomere-related sequences appeared in an extrachromosomal form that could be separated from bulk nuclear DNA by velocity and isopycnic centrifugations. It is concluded that, in addition to typical repair events, rapid synthesis of telomeric repeats occurs in wheat embryos at the onset of germination.

Leishmania mutants have contributed greatly to extend our knowledge of this parasite's biology. Here we report the use of the mariner in vitro transposition system as a source of reagents for shuttle mutagenesis and targeted disruption of Leishmania genes. The locus-specific integration was achieved by the disruption of the subtelomeric gene encoding a DNA-directed RNA polymerase III subunit (RPC2). Further inactivation of RPC2 alleles required the complementation of the intact gene, which was transfected in an episomal context. However, attempts to generate a RPC2 chromosomal null mutant resulted in genomic rearrangements that maintained copies of the intact locus in the genome. The maintenance of the RPC2 chromosomal locus in complemented mutants was not mediated by an increase in the number of copies and did not involve chromosomal translocations, which are the typical characteristics of the genomic plasticity of this parasite. Unlike the endogenous locus, the selectable marker used to disrupt RPC2 did not display a tendency to remain in its chromosomal location but was targeted into supernumerary episomal molecules.

The major surface protease (msp or gp63) of Leishmania plays a major role in the host–parasite interaction. We analysed here the structure of the msp gene locus in Leishmania (Viannia) braziliensis and compared it to results obtained in other species. Physical mapping of cosmid contigs revealed a minimum of 37 genes per haploid genome and at least 8 different msp gene families. Within the same organism, these genes showed a nucleotide sequence varying in certain stretches from 3 to 34%, and a mosaic structure. From an evolutionary point of view, major differences were observed between subgenera Viannia and Leishmania, both in terms of msp gene number and sequence. Within subgenus Viannia, phenetic analysis revealed three clusters in which sequence variants of L. (Viannia) braziliensis and L. (Viannia) guyanensis were interspersed. Functional implications of our results were explored from predicted L. (Viannia) braziliensis protein sequences: regions encoding the msp catalytic site showed a conserved sequence, while regions encoding surface domains possibly involved in the host–parasite interaction (macrophage adhesion sites and immunodominant B-cell and T-cell epitopes) were variable. We speculate that this would be an adaptive strategy of the parasite.

Dyskeratosis congenita (DC) is a severe, inherited, bone marrow failure syndrome, with associated cutaneous and noncutaneous abnormalities. DC patients also show signs of premature ageing and have an increased occurrence of cancer. DC can originate through: (1) mutations in DKC1, which result in X-linked recessive DC; (2) mutations in the RNA component of telomerase (TERC), which result in autosomal dominant DC (AD-DC); and (3) mutations in other, currently uncharacterised, genes, which result in autosomal recessive DC (AR-DC). As DKC1 encodes dyskerin, a protein component of small nucleolar ribonucleoprotein (snoRNP) particles, which are important in ribosomal RNA processing, DC was initially described as a disorder of defective ribosomal biogenesis. Subsequently, dyskerin and TERC were shown to closely associate with each other in the telomerase complex, and DC has since come to be regarded as a telomerase deficiency disorder characterised by shorter telomeres. These findings demonstrate the importance of telomerase in humans and highlight how its deficiency (through DKC1 and TERC mutations) results in multiple abnormalities including premature ageing, bone marrow failure and cancer. Identification of the gene(s) involved in AR-DC will help to define the pathophysiology of DC further, as well as expand our insights into telomere function, ageing and cancer.