Telomeric Signals Research Articles

3D Telomere Structure Analysis to DetectGenomic Instability and Cytogenetic Evolutionin Myelodysplastic Syndromes.

The disease course of myelodysplastic syndromes (MDS) features chromosome instability and clonal evolution, leading to the sequential acquisition of novel cytogenetic aberrations and the accumulation of these abnormalities in the bone marrow. Although clonal cytogenetic abnormalities can be detected by conventional cytogenetics in 50% of patients with MDS, such distinguishing patterns are lacking in the other 50%. Despite the increase in the prognostic value of some biomarkers, none of them is specific and able to discriminate between stable and unstable patients that subsequently progress to acute myeloid leukemia. This pilot study aimed to investigate the potential use of the 3D telomere profiling to detect genomic instability in MDS patients with or without clonal cytogenetic evolution. The comparison between different time points in patients with cytogenetic changes showed that in the CD34+ MDS cells, there was a significant decrease in the total number of telomeric signals, the average intensity of signals and the total intensity of telomeres. By contrast, the number of aggregates increased during cytogenetic evolution (p < 0.001). This pattern was observed only for MDS patients with cytogenetic evolution but was absent in patients without cytogenetic changes. In conclusion, we demonstrated that the 3D nuclear telomere organization was significantly altered during the MDS disease course, and may have contributed to cytogenetic clonal evolution.

Pre-labelled oligo probe-FISH karyotype analyses of four Araliaceae species using rDNA and telomeric repeat.

The family Araliaceae contains many medicinal species including ginseng of which the whole genome sequencing analyses have been going on these days. To characterize the chromosomal distribution of 5S and 45S rDNAs and telomeric repeat in four ginseng related species of Aralia elata (Miq.) Seem., Dendropanax morbiferus H. Lév., Eleutherococcus sessiliflorus (Rupr. Et Maxim.) Seem., Kalopanax septemlobus (Thunb. ex A.Murr.) Koidz. Pre-labelled oligoprobe (PLOP)-fluorescence in situ hybridization (FISH) was carried out. The chromosome number of A. elata was 2n = 24, whereas that of the other three species of D. morbiferus, E. sessiliflorus, and K. septemlobus was 2n = 48, corresponding to diploid and tetraploid, respectively, based on the basic chromosome number x = 12 in Araliaceae. In all four species, one pair of 5S signals were detected in the proximal regions of the short arms of chromosome 3, whereas in K. septemlobus, the 5S rDNA signals localized in the subtelomeric region of short arm of chromosome 3, while all the 45S rDNA signals localized at the paracentromeric region of the short arm of chromosome 1. And the telomeric repeat signals were detected at the telomeric region of both short and long arms of most chromosomes. The PLOP-FISH was very effective compared with conventional FISH method. These results provide useful comparative cytogenetic information to better understand the genome structure of each species and will be useful to trace the history of ginseng genomic constitution.

FISH mapping of rDNA and telomeric repeats in 10 Senna species

Plants of the genus Senna (Fabaceae) are valued for industrial and medicinal properties that have spurred crop improvement through breeding programs. However, there is very little chromosomal data for this genus, limiting the potential for cytogenetics and genomics research. Here, we used fluorescence in situ hybridization (FISH) to perform a comparative analysis of 10 Senna spp. karyotypes (2n = 28 except S. tora with 2n = 26). We detected differences in the distributions of rDNA gene clusters and Arabidopsis-type telomeric repeats (TTTAGGG)n. Only one 5S rDNA pair was detected in all species, but we observed more interspecies variation for 45S rDNA: four pairs in S. didymobotrya, S. spectabilis, and S. viarum; two pairs in S. candolleana; and one pair in S. bauhinioides, S. multiglandulosa, S. occidentalis, and S. tora. In both S. leandrii and S. sulfurea, 45S rDNA distribution was hemizygous. While all chromosomes possessed telomeric signals in the terminal region, this signal was also present in the interstitial regions of all S. tora chromosomes and, less obviously (fewer chromosomes, weaker signals), in S. occidentalis. These preliminary data demonstrate interspecific karyotype variation that reveals Senna genome dynamics. Our results facilitate cytogenetic mapping of other major repeats, thus contributing to an improved understanding of Senna genome structure and evolutionary history.

Nature and Functions of Telomeric Transcripts.

Telomeres are complex and dynamic structures whose functions and composition change during the cell cycle and development. Telomeric transcripts are essential components of telomeres. Transcription regulation and cellular levels of telomeric RNAs are closely associated with the control of telomere length, formation of telomeric chromatin, telomere replication, and regulation of non-telomeric gene transcription, which indicates a critical regulatory role of telomeric RNAs in telomere protection and transmission of signals about the state of telomeres to cellular genes. The studies of telomeric transcriptome in early Drosophila development have revealed a new level of genomic stability regulation involving telomeric RNAs. Due to their ability to interact with multiple proteins and to translocate in the cell, telomeric transcripts are important participants of telomeric signaling pathways, whose mechanisms are still to be understood at the organism level.

One-pot detection of telomerase activity with high sensitivity and specificity via RNA FRET probes and RNase H-assisted signal cycling amplification.

Human telomerase is a universal cancer biomarker and a promising anticancer therapeutic target. Sensitive and specific detection of telomerase activity is of great significance for cancer diagnosis and treatment. Up to now, many methods have been established to detect the activity of telomerase, but most of these methods require complex probe design and tedious experimental steps generally including telomere extension reaction, amplification of the extended products and signal detection. Herein, we propose a one-pot method to detect the telomerase activity via RNA FRET probes and RNase H-assisted signal cycling amplification, and the proposed assay can integrate the telomere extension reaction, signal amplification and readout in one step without requirement of amplification of the extended products, which greatly simplifies the experimental design and operation steps. Additionally, the proposed one-pot method has high sensitivity and can unequivocally detect the telomerase activity in as few as 5 cancer cells, which holds great potential in telomerase-related fundamental and clinical studies.

Tea polyphenols delays human glomerular mesangial cells senescence induced by high glucose via regulating STAT3/miR-126/telomere signaling pathway activation

The aim of this paper was to explore the effects and possible mechanisms in vitro of tea polyphenols (TP) delaying human glomerular mesangial cells (HGMCs) senescence induced by high glucose (HG). HGMCs were cultured in vitro and divided into the normal group (N, 5.5 mmol·L⁻¹ glucose), the mannitol group(MNT, 5.5 mmol·L⁻¹ glucose plus 24.5 mmol·L⁻¹ mannitol), the high dose of D-glucose group (HG, 30 mmol·L⁻¹ glucose), the low dose of TP group (L-TP, 30 mmol·L⁻¹ glucose plus 5 mg·L⁻¹ TP) and the high dose of TP group (H-TP, 30 mmol·L⁻¹ glucose plus 20 mg·L⁻¹ TP), which were cultured in 5% CO₂ at 37 °C, respectively. Firstly, the effects of TP on the cell morphology of HGMCs were observed after 72 h-intervention. Secondly, the cell cycle, the positive rate of senescence-associated-β-galactosidase (SA-β-gal) staining and the telomere length were detected, respectively. Finally, the protein expressions of p53, p21 and Rb in the p53-p21-Rb signaling pathway were investigated, respectively. And the expressions of p-STAT3 and miR-126 were examined severally. The results indicated that HG not only arrested the cell cycle in G₁ phase but also increased the positive rate of SA-β-gal staining, and shortened the telomere length. HG led to the protein over-expressions of p53, p21 and Rb and HGMCs senescence by activating the p53-p21-Rb signaling pathway. In addition, L-TP delayed HGMCs senescence by improving the cell cycle G₁ arrest, reducing SA-β-gal staining positive rate and lengthening the telomere length. L-TP reduced the protein over-expressions of p53, P21 and Rb induced by HG and inhibited the telomere-p53-p21-Rb signaling pathway. Moreover, the expression of p-STAT3 was increased and the expression of miR-126 was decreased in HGMCs induced by HG. L-TP reduced the expression of p-STAT3 and increased the expression of miR-126 in HGMCs. In conclusion, HG could induce HGMCs senescence by activating the telomere-p53-p21-Rb signaling pathway in vitro. L-TP could delay HGMCs senescence through regulating STAT3/miR-126 expressions and inhibiting the telomere-p53-p21-Rb signaling pathway activation. These findings could provide the effective interventions in clinic for preventing and treating renal cell senescence in diabetic kidney disease.

Integrative analysis of chromosome banding, telomere localization and molecular genetics in the highly variable Ctenomys of the Corrientes group (Rodentia; Ctenomyidae).

The genus Ctenomys comprises about 70 species with great chromosome diversity. The Corrientes group is one of the most chromosomally variable lineages in the genus, where the diploid number (2n) varies from 41 to 70. In this group, three nominal species and numerous polymorphic and polytypic populations have been described. In order to get insight into the chromosomal evolution of this species complex, we applied different banding and molecular cytogenetic techniques. The results were interpreted in an evolutionary context, based on mitochondrial cytochrome b analyses. Studied samples are representative of the broad chromosomal variability in the group, including specimens with 2n = 42 to 2n = 70. Heterochromatin was scarce but concentrated in a few chromosomes. Centromeric DAPI-negative heterochromatin was observed in some autosomal pairs, which differed among populations. Location and amount of DAPI-neutral heterochromatin within the Y chromosome varied among populations. The variable distribution of heterochromatin indicates its dynamic behavior. NORs were detected in one pair of autosomes, which also differed among some populations. Telomeric FISH signals were observed in all complements only at the chromosome ends. The Corrientes group belongs to a clade that also includes C. pearsoni, C. lami, C. minutus, C. ibicuiensis and C. torquatus. Almost all of these species are variable at the chromosomal level, suggesting that this is the ancestral condition of the clade. Within the Corrientes group, the observed low genetic divergence, in contrast with its high chromosomal variability, is indicative of decoupling between the rates of chromosomal and mitochondrial evolution.

Abstract 3371: Analysis of telomere length and dysfunction in normal breast tissue from BRCA2 mutation carriers

Abstract The tumor suppressor protein BRCA2 is important for maintaining genomic stability. BRCA2 is essential for homologous recombination repair of DNA double strand breaks and also has a role in protection of stalled replication forks as well as in telomere protection and maintenance. Disruptions in telomere homeostasis can result in excessive telomere shortening and drive chromosome instability, a hallmark of BRCA2-related cancers. Germline mutations in the BRCA2 gene are associated with highly increased risk of breast cancer. A single deleterious founder mutation, BRCA2999del5, has been detected in the gene in the Icelandic population, making it feasible to study the influence of a single mutation at a population level. The BRCA2999del5 mutation is found in 6-7% of female breast cancer patients in Iceland and is associated with complex chromosomal changes in tumor tissue. Furthermore, the BRCA2999del5 mutation is associated with poor prognosis, although mutation carriers seem to differ with respect to age of onset and severity of disease. It is therefore of great interest to identify factors that influence breast cancer risk within the mutation carrier group. The aim of the study was to measure telomere length (TL) and levels of telomere dysfunction in tumor-adjacent normal breast tissue from BRCA2 mutation carriers and non-carriers and investigate their potential relationship with breast cancer risk. The study group consisted of 186 Icelandic breast cancer patients; BRCA2999del5 mutation carriers and sporadic cases, matched with respect to age and year of diagnosis. For TL measurements, paraffin embedded normal breast tissue samples were analyzed by Quantitative Fluorescence in Situ Hybridization. Telomere dysfunction induced foci (TIFs) can be detected where co-localization of telomere and DNA-damage signals occur. For this purpose, the samples were also immunofluorocently stained for the DNA damage repair protein 53BP1. In concordance with previously reported data in the literature, luminal epithelial cells showed the shortest TL and highest number TIFs of the cell types in normal breast tissue. This observation is highly relevant as these are the cells from which most breast cancers originate. No difference was detected in age-adjusted TL between BRCA2 mutation carriers and non-carriers. However, consistent with our recently published data from TL measurements in blood from the same study group, shorter TL is correlated with younger age at breast cancer diagnosis in BRCA2 mutation carriers but not in non-carriers. In conclusion, these results indicate that in BRCA2 mutation carriers, shorter TL in normal breast tissue is associated with earlier breast cancer occurrence. Citation Format: Birna Thorvaldsdottir, Beth A. Cimini, Morgan E. Diolaiti, Katrin Olafsdottir, Jon G. Jonasson, Jorunn E. Eyfjörd. Analysis of telomere length and dysfunction in normal breast tissue from BRCA2 mutation carriers [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 3371.

Assessment of genomic instability and proliferation index in cultured lymphocytes of patients with Down syndrome, congenital anomalies and aplastic anaemia

One hundred and fifteen cases [Down Syndrome (DS) n = 75, Multiple Congenital Anomalies (MCA) n = 15 and Aplastic Anaemia (AA) n = 25], with respect to their nature of predisposition to cancer, were selected for clinical, cytogenetic and cyto-molecular studies to understand the severity of genomic instability according to the nature of the different diseases. Cytogenetic studies included chromosomal aberration (CA) assays and cytokinesis block micronucleus cytome (CBMN-Cyt) assays. In DS, MCA and AA, average frequencies of nuclear anomalies (NA) were 0.015 ± 0.0006, 0.021 ± 0.00123, 0.031 ± 0.00098, respectively and CA were 0.107 ± 0.003, 0.105 ± 0.008, 0.158 ± 0.006, respectively per metaphase. The extent of genomic instability in patients analysed by CBMN-Cyt assays and CA assays was statistically significant in all groups. Comparatively decreased cytokinesis block proliferation index (CBPI) observed in AA patients of 1.59 ± 0.05, support the assumption that decreased levels of CBPI indicate increased genomic damage. Furthermore, we performed peptide nucleic acid fluorescence in situ hybridisation (PNA FISH) analysis to understand the mechanisms behind genomic instability and telomere dysfunction. PNA FISH showed increased frequencies of telomere signal free ends (0.98 ± 0.13) in individuals with higher genomic instability. Therefore, the results demonstrate that increased chromosomal instability along with higher telomere attrition or loss may initiate gross DNA damage and leads to chromosomal instability, which is an important mechanism for triggering genomic instability – an important hallmark of cancer cells.

Associations of Arsenic Exposure With Telomere Length and Naïve T Cells in Childhood-A Birth Cohort Study.

There is limited knowledge of association between arsenic exposure and telomere length (TL) and signal joint T-cell receptor excision circle (sjTREC) that are potential biomarkers of immune senescence and disease susceptibility. We aimed to clarify whether long-term inorganic arsenic exposure influences TL and sjTRECs in childhood. Children born in a longitudinal mother-child cohort were followed-up at 4.5 (n = 275) and 9 years (n = 351) of age. Arsenic exposure was assessed by metabolite concentrations in urine (U-As) from mothers at gestational week 8 (prenatal) and their children at 4.5 and 9 years. TL and sjTRECs were determined in blood cells using quantitative PCR. The oxidative DNA damage marker 8-hydroxy-2'-deoxyguanosine (8-OHdG) in plasma was measured by ELISA. In multivariable-adjusted spline regression analyses, both prenatal and childhood arsenic exposure above U-As of 45 µg/l were significantly inversely associated with TL and sjTRECs at 9 years. Fraction of monomethylarsonic acid (MMA) above spline knot 7% were significantly inversely associated with both TL and sjTRECs reflecting increased toxicity due to less-efficient arsenic metabolism in 9--year-old children. Prenatal and childhood arsenic exposure were positively associated with 8-OHdG at 9 years which in turn was inversely associated with sjTRECs at 9 years. However, adjustment with 8-OHdG did not change the estimates of the association of U-As with sjTRECs reflecting little contribution from 8-OHdG-induced oxidative stress. Our findings suggest that chronic arsenic exposure from early life can result in TL attrition and lower production of naïve T cells potentially leading to immunosenescence and immunodeficiency.

Molecular cytogenetic of the Amoy croaker, Argyrosomus amoyensis (Teleostei, Sciaenidae)

The family Sciaenidae is remarkable for its species richness and economic importance. However, the cytogenetic data available in this fish group are still limited, especially those obtained using fluorescence in situ hybridization (FISH). In the present study, the chromosome characteristics of a sciaenid species, Argyrosomus amoyensis, were examined with several cytogenetic methods, including dual-FISH with 18S and 5S rDNA probes, and a self-genomic in situ hybridization procedure (Self-GISH). The karyotype of A. amoyensis comprised 2n=48 acrocentric chromosomes. A single pair of nucleolar organizer regions (NORs) was located at the proximal position of chromosome 1, which was positive for silver nitrate impregnation (AgNO3) staining and denaturation-propidium iodide (DPI) staining but negative for Giemsa staining and 4',6-diamidino-2-phenylindole (DAPI) staining, and was confirmed by FISH with 18S rDNA probes. The 5S rDNA sites were located at the centromeric region of chromosome 3. Telomeric FISH signals were detected at all chromosome ends with different intensities, but internal telomeric sequences (ITSs) were not found. Self-GISH resulted in strong signals distributed at the centromeric regions of all chromosomes. C-banding revealed not only centromeric heterochromatin, but also heterochromatin that located on NORs, in interstitial and distal telomeric regions of specific chromosomes. These results suggest that the karyotype of Amoy croaker was relatively conserved and primitive. By comparison with the reported cytogenetic data of other sciaenids, it can be deduced that although the karyotypic macrostructure and chromosomal localization of 18S rDNA are conserved, the distribution of 5S rDNA varies dynamically among sciaenid species. Thus, the 5S rDNA sites may have different evolutionary dynamics in relation to other chromosomal regions, and have the potential to be effective cytotaxonomic markers in Sciaenidae.

RDNA와 말단소체 반복서열 탐침을 이용한 천마의 FISH 염색체 조성 분석

Background: Gastrodia elata Blume is a saprophytic perennial plant in the Orchidaceae family, because of its agricultural and medicinal effectiveness, researchers focus on its genome and chemical components. However, cytogenetic information based on the chromosome structure and composition to construct chromosomal backbone for genome sequencing research and for the development and breeding of plants is very limited.BR Methods and Results: We determined the metaphase chromosome composition of the G. elata genome by fluorescence in situ hybridization (FISH) using 5S and 45S rDNAs and telomeric repeat probes. The nuclear genome of G. elata was organized into 2 n = 36, with relatively small (2.71 - 5.50㎛)chromosomes that showed gradual decrease in size. Conglutination phenomenon was observed among the metaphase chromosomes, and it was distinguished from that in other plant metaphase chromosome spreads. One pair of signal was detected for each 5S and 45S rDNA in the pericentromeric region and interstitial region on the short arm of chromosomes 10 and 4, respectively, and telomeric DNA signals were detected in the terminal region of most chromosomes.BR Conclusions: To our knowledge, this is the first FISH chromosome composition result in G. elata and could be useful in more comprehensive molecular cytogenetic and genomic analyses as well as breeding programs of the medicinal plant G. elata.

A Novel Role of the Human CST Complex in Regulating the DNA Damage Response

CST (CTC1‐STN1‐TEN1) is an RPA‐like, ssDNA binding protein that functions in telomere replication and genome‐wide DNA replication rescue. Previous studies have shown that depletion of STN1 or CST overexpression leads to decreased or increased new origin firing following replication stress, suggesting a role for CST in dormant origin activation. Additionally, depletion of CST subunits leads to increased anaphase bridges and micronuclei. Recently, a conditional CTC1 knockout line was created in HCT116 cells. Removal of CTC1 was found to cause decreased cell proliferation and elongation of the telomeric ssDNA G‐overhang, leading to RPA accumulation and telomeric DNA damage signaling. Interestingly, rescue of the telomeric damage did not restore normal cell growth, suggesting that other factors contribute to the growth defects in the absence of CTC1. Here, we investigate the consequences of CTC1 deletion on genome‐wide replication and activation of the DNA damage response. We find that CTC1 deletion lead to a delayed but abrupt activation of p53 and p21 leading to decreased DNA replication and a G2/M arrest. We hypothesized that this cell cycle arrest was caused by ATR activation from defects in telomere or genome‐wide DNA replication. Instead, our results suggest that ATR signaling is defective in the absence of CTC1 and p53 is activated in an ATR‐independent manner. Overall, our findings suggest a novel and unexpected role of CST in promoting checkpoint signaling to prevent genome instability.Support or Funding InformationThis work is supported by the National Institutes of Health grant R00 GM104409 and startup funds from the University of South Carolina.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Telomere length determined by the fluorescence insitu hybridisation distinguishes malignant and benign cells in cytological specimens.

Telomeres are tandem repeats of TTAGGG at the end of eukaryotic chromosomes that play a key role in preventing chromosomal instability. The aim of the present study is to determine telomere length using fluorescence insitu hybridisation (FISH) on cytological specimens. Aspiration samples (n=41) were smeared on glass slides and used for FISH. Telomere signal intensity was significantly lower in positive cases (cases with malignancy, n=25) as compared to negative cases (cases without malignancy, n=16), and the same was observed for centromere intensity. The difference in DAPI intensity was not statistically significant. The ratio of telomere to centromere intensity did not show a significant difference between positive and negative cases. There was no statistical difference in the signal intensities of aspiration samples from ascites or pleural effusion (n=23) and endoscopic ultrasound-guided FNA samples from the pancreas (n=18). The present study revealed that telomere length can be used as an indicator to distinguish malignant and benign cells in cytological specimens. This novel approach may help improve diagnosis for cancer patients.

A Comparative Chromosome Mapping Study in Japanese Podismini Grasshoppers (Orthoptera: Acrididae: Melanoplinae)

In the present paper, karyotypes of 7 Japanese Podismini species, Anapodisma beybienkoi, Fruhstorferiola okinawaensis, Parapodisma caelestis, P. mikado, P. setouchiensis, P. tenryuensis, and Sinopodisma punctata (2n♂ = 21, all acrocentric), are described and compared on the basis of conventional (C-banding, DAPI/CMA₃-staining, Ag-NOR) and molecular (FISH with 18S rDNA and telomeric probes) cytogenetic staining methods. This is the first study to report karyotypes of A. beybienkoi and P. caelestis. Differential staining techniques showed karyotypic diversity in these species. The number of 18S rDNA signals ranged from 2 to 6, and the signals were located on the autosomes or sex chromosomes. In all species, clusters of rDNA coincided with Ag-NORs. Telomeric signals occurred at the chromosome ends at the pachytene stage and seldom at other stages of meiosis. Paracentromeric and some distal and interstitial blocks of constitutive heterochromatin were detected in the chromosomes of Anapodisma, Fruhstorferiola, and Parapodisma species. Staining with DAPI and CMA₃ revealed 2 groups of heterochromatin composition. In addition, intraspecific differences in the number of rDNA clusters and C-bands were observed within Parapodisma species. Based on the evidence of cytogenetic characteristics, the monophyly of Tonkinacridina cannot be supported.

Chromosome Karyotyping of Senna covesii and S. floribunda based on Triple?color FISH Mapping of rDNAs and Telomeric Repeats

The genus Senna in the family Fabaceae is distributed and cultivated around the world and has been used as sources of medicine and commercial goods. Molecular cytogenetic study based on FISH technique is useful for breeding and genomic research of the species. Triple-color FISH karyotype analyses were carried out to understand the genome structure of two Senna species, S. covesii (A. Gray) H. S. Irwin & Barneby and S. floribunda (Cav.) H. S. Irwin & Barneby using 5S rDNA, 45S rDNA, and telomeric repeat probes. Three and one pairs of 45S and 5S rDNA signals were detected, respectively, in S. covesii, whereas one pair each of 45S and 5S rDNA signals, were detected in S. floribunda. Telomeric signals appeared at all chromosome termini in both species. This result provides basic cytogenetic information which will be useful for future breeding and genomic research of Senna species.

Cytogenetic characterization and description of an X1X1X2X2/X1X2Y sex chromosome system in Collichthys lucidus (Richardson, 1844)

The chromosomes of spinyhead croaker Collichthys lucidus (Richardson, 1844) were characterized for the first time by fluorescence staining, self genomic in situ hybridization (self-GISH), and multicolor fluorescence in situ hybridization (FISH) with 18S rDNA, 5S rDNA and telomeric sequence probes. The female karyotype has exclusively 24 pairs of acrocentric chromosomes (2n=48a, NF=48), while the male one consists of 22 pairs of acrocentric chromosomes, 2 monosomic acrocentric chromosomes and a metacentric chromosome (2n=1m+46a, NF=48). The difference between female and male karyotypes indicates the presence of a sex chromosome of X1X1X2X2/X1X2Y type, where Y is the unique metacentric chromosome in the male karyotype. As revealed by FISH, 5S rDNA and 18S rDNA sites were mapped at syntenic position of the largest acrocentric chromosome (X1), and the short arms of the Y chromosome as well. An X1-chromosome specific interstitial telomeric signal (ITS) was detected overlapping the 5S rDNA sites. In addition, self-GISH revealed that the repetitive DNAs accumulated on all the putative sex chromosome. Chromosome fusion accompanied by a partial deletion in the ancestral karyotype (2n=48a) is hypothesized for the origin of such multiple sex chromosome system. The present study, as the first description of differentiated sex chromosome in family Sciaenidae, will give clues to the studies on the sex chromosome of other Sciaenids.

Long-term Persistent Organic Pollutants Exposure Induced Telomere Dysfunction and Senescence-Associated Secretary Phenotype.

Environmentally persistent organic pollutant (POP) is the general term for refractory organic compounds that show long-range atmospheric transport, environmental persistence, and bioaccumulation. It has been reported that the accumulation of POPs could lead to cellular DNA damage and adverse effects of on metabolic health. To better understand the mechanism of the health risks associated with POPs, we conducted an evidence-based cohort investigation (n = 5,955) at the Jinghai e-waste disposal center in China from 2009 to 2016, where people endure serious POP exposure. And high levels of aging-related diseases, including hypertension, diabetes, autoimmune diseases, and reproductive disorders were identified associated with the POP exposure. In the subsequent molecular level study, an increased telomere dysfunction including telomere multiple telomere signals, telomere signal-free ends, telomere shortening and activation of alternative lengthening of telomeres were observed, which might result from the hypomethylated DNA modification induced telomeric repeat-containing RNA overexpression. Moreover, dysfunctional telomere-leaded senescence-associated secretory phenotype was confirmed, as the proinflammatory cytokines and immunosenescence hallmarks including interleukin-6, P16INK4a, and P14ARF were stimulated. Thus, we proposed that the dysfunctional telomere and elevated systemic chronic inflammation contribute to the aging-associated diseases, which were highly developed among the POP exposure individuals.

Application of cytogenetic markers in the taxonomy of flat rock scorpions (Scorpiones: Hormuridae), with the description of Hadogenes weygoldti sp. n.

In the present study, we performed the first comparative cytogenetic study in Hadogenes species using both standard and molecular cytogenetic approaches. Information about the diploid set, number and distribution of 18S rDNA and telomeric sequences was obtained from three South African species, Hadogenes trichiurus (Gervais, 1843), H. zuluanus Lawrence, 1937 and H. weygoldti sp. n.. All species analysed differ considerably in the number of chromosomes (H. trichiurus 2n=48, H. zuluanus 2n=80, H. weygoldti sp. n. 2n=113). In contrast, the number of 18S rDNA clusters and distribution of telomeric sequences represent rather stable cytogenetic characters in Hadogenes. Within all karyotypes, we identified one pair of 18S rDNA clusters. The telomeric signals were exclusively on the terminal chromosomal regions. Interestingly, the chromosomal location of 18S rDNA clusters varied from terminal to interstitial in species karyotypes, indicating the presence of hidden structural chromosomal changes. Additionally, the present comparative study is complemented by the description of a new species, H. weygoldti sp. n., based on specific karyotype features and morphological characters. Finally, our cytogenetic results are compared with known chromosomal data of other Hadogenes species, and the use of cytogenetic approaches in the taxonomy of scorpions is discussed.

Evolution of Karyotypes in Chameleons.

The reconstruction of the evolutionary dynamics of karyotypes and sex determining systems in squamate reptiles is precluded by the lack of data in many groups including most chameleons (Squamata: Acrodonta: Chamaeleonidae). We performed cytogenetic analysis in 16 species of chameleons from 8 genera covering the phylogenetic diversity of the family and also phylogenetic reconstruction of karyotype evolution in this group. In comparison to other squamates, chameleons demonstrate rather variable karyotypes, differing in chromosome number, morphology and presence of interstitial telomeric signal (ITS). On the other hand, the location of rDNA is quite conserved among chameleon species. Phylogenetic analysis combining our new results and previously published data tentatively suggests that the ancestral chromosome number for chameleons is 2n = 36, which is the same as assumed for other lineages of the clade Iguania, i.e., agamids and iguanas. In general, we observed a tendency for the reduction of chromosome number during the evolution of chameleons, however, in Rieppeleon brevicaudatus, we uncovered a chromosome number of 2n = 62, very unusual among squamates, originating from a number of chromosome splits. Despite the presence of the highly differentiated ZZ/ZW sex chromosomes in the genus Furcifer, we did not detect any unequivocal sexual differences in the karyotypes of any other studied species of chameleons tested using differential staining and comparative genomic hybridization, suggesting that sex chromosomes in most chameleons are only poorly differentiated.