Telomere-length regulation in inter-ecotype crosses of Arabidopsis

Telomeres, the nucleoprotein complexes at the ends of eukaryotic chromosomes, are maintained at a species-specific equilibrium length. Arabidopsis thaliana is a self-fertilizing plant and different geographical isolates or ecotypes show differing telomere-lengths. We have exploited this telomere-length polymorphism between Arabidopsis ecotypes to investigate the genetic regulation of telomere length by analysing telomere lengths in 16 different inter-ecotype crosses between plants with differing telomere sizes. With two exceptions, the inter-ecotype hybrid plants present a new telomere-length set point, intermediate between that of the two parents. A regulation mechanism thus shortens the longer and lengthens the shorter telomeres.     

Antler growth rate in yearling Iberian red deer (<Emphasis Type="Italic">Cervus elaphus hispanicus</Emphasis>)

The aims of this study were to describe first antler growth rate and the factors affecting it. Growth rate reached a peak in week 14. Mean first antler growth rate during the whole growing period was 1.95 ± 0.05 cm/week. Lactation influenced antler growth rate as this was positively affected by total protein yield, while antlers grew at a lower rate the later they started to grow.     

Iterated prisoner's dilemma in an asocial world dominated by loners, not by defectors

Cooperation among genetically unrelated individuals can arise when pairs of individuals interact repeatedly in the Prisoner’s Dilemma. However, the conditions allowing the evolution of reciprocal cooperation become extremely restrictive as the size of the cooperative group increases, because defectors can exploit cooperators more efficiently in larger groups. Here we consider three strategies: Tit for Tat, defector, and loner. Loner beats defector in a non-cooperative world. However, a cooperative strategy Tit for Tat (TFT₀) that stops cooperation after the first iteration when there is at least one defector in the group, can invade a world of loners, even in sizable groups, if both the TFT₀ and the defector strategies arise at the same frequency by mutation.     

An overview of Syntrichia ruralis complex (Pottiaceae: Musci) in the Mediterranean region and neighbouring areas

The Syntrichia ruralis complex is revised in the Mediterranean region and neighbouring areas. A critical study of six quantitative and eight qualitative gametophytic characters from a total of 232 samples has been carried out. On the basis of this survey five taxa have been recognized. An identification key is provided. S. ruralis var. subpapillosissima is elevated to the rank of species as S. subpapillosissima . A lectotype for S. calcicola is proposed. S. ruralis var. submamillosa and S. ruralis var. glacialis are regarded as synonymous with S. subpapillosissima and S. ruralis , respectively. Also, Tortula densa is included in the variability shown by S. calcicola . Syntrichia ruralis var. substereidosa ( Tortula ruralis var. substereidosa ) is excluded from the Syntrichia ruralis complex and is included in the synonymy of S. virescens . © 2002 The Linnean Society of London, Botanical Journal of the Linnean Society , 138 , 209–224.     

Somatic embryogenesis and plant regeneration in Medicago arborea L.

Summary An efficient plant regeneration system employing cotyledons, hypocotyls, petioles and leaves as explants and characterized by continuous and prolific production of somatic embryos, has been developed with Medicago arborea ssp. arborea. The optimal somatic embryogenic response was obtained using a two-step protocol, where explants were incubated under a 16 h photoperiod for 2 mo. on Murashige and Skoog (MS) medium containing 2,4-dichlorophenoxyacetic acid (2,4-D; 9 μM) and kinetin (9 μM), and followed by transfer to kinetin-free MS medium with 2,4-D (2.25 μM). Removal of the cytokinin and a reduction in the concentration of auxin (2.25 μM) in the second step of culture were critical for enhanced production of somatic embryos. The best explants proved to be cotyledons and petioles (i.e. a mean of 18.0±0.70 somatic embryos at 3 mo. for petiole culture). Somatic embryos were converted into normal plantlets (8.0±0.89%) when cultured on basal MS medium with 5 μM indolebutyric acid. No somatic embryos were obtained when thidiazuron was used in the culture media. Using petioles as explants and N⁶-benzyladenine (BA), embryogenesis was induced in the second step of culture when BA was removed from the medium and the concentration of 2,4-D was decreased to 2.25 μM.     

miR-141 and miR-200c as Markers of Overall Survival in Early Stage Non-Small Cell Lung Cancer Adenocarcinoma

Background

Several treatments in non-small cell lung cancer (NSCLC) are histology-dependent, and the need for histology-related markers is increasing. MicroRNAs (miRNAs) are promising molecular markers in multiple cancers and show differences in expression depending on histological subtype. The miRNA family miR-200 has been associated with the regulation of epithelial-mesenchymal (EMT)/mesenchymal-epithelial transition (MET). EMT involves profound phenotypic changes that include the loss of cell-cell adhesion, the loss of cell polarity, and the acquisition of migratory and invasive properties that facilitates metastasis. A dual role for the miR-200 family in the prognosis of several tumors has been related to tumor cell origin. However, the prognostic role and function of miR-200 family in early-stage NSCLC adenocarcinoma and squamous cell carcinoma (SCC) have not been well established.

Methods

miRNA expression was determined using TaqMan assays in 155 tumors from resected NSCLC patients. Functional studies were conducted in three NSCLC cell lines: H23, A-549 and HCC-44.

Results

High miR-200c expression was associated with shorter overall survival (OS) in the entire cohort (p = 0.024). High miR-200c (p = 0.0004) and miR-141 (p = 0.009) expression correlated with shorter OS in adenocarcinoma – but not in SCC. In the multivariate analysis, a risk score based on miR-141 and miR-200c expression emerged as an independent prognostic factor for OS in the entire cohort (OR, 2.787; p = 0.033) and in adenocarcinoma patients (OR, 10.649; p = 0.002). Functional analyses showed that miR-200c, was related to mesenchymal-epithelial transition (MET) and affected cell migration and E-cadherin levels, while overexpression of miR-141 reduced KLF6 protein levels and produced an increase of secretion of VEGFA in vitro (H23, p = 0.04; A-549, p = 0.03; HCC-44, p = 0.02) and was associated with higher blood microvessel density in patient tumor samples (p<0.001).

Conclusion

High miR-141 and miR-200c expression are associated with shorter OS in NSCLC patients with adenocarcinoma through MET and angiogenesis.     

Coronary artery anomalies and aortic valve morphology in the Syrian hamster

In the Syrian hamster, anomalies in the origin of the left coronary artery are significantly associated with the bicuspid condition of the aortic valve. In this species, bicuspid aortic valves are expressions of a trait, the variation of which takes the form of a phenotypic continuum, ranging from a tricuspid aortic valve with no commissural fusion to a bicuspid aortic valve with the aortic sinuses located in ventrodorsal orientation and devoid of any raphe. The intermediate stages of the continuum are represented by tricuspid aortic valves with a more or less extensive fusion of the ventral commissure and bicuspid aortic valves with a more or less developed raphe located in the ventral aortic sinus. The present study was designed to decide whether there is a gap between tricuspid and bicuspid aortic valves regarding the incidence of coronary artery anomalies, or whether this incidence varies according to the different tricuspid and bicuspid morphotypes of the continuum. The study was carried out in Syrian hamsters belonging to a single inbred family with a high incidence of tricuspid aortic valves with fusion of the ventral commissure, bicuspid aortic valves, and anomalies in the origin of the left coronary artery, i.e. single right coronary artery ostium in aorta, anomalous origin of the left coronary artery from the pulmonary artery, and anomalous origin of the left coronary artery from the dorsal aortic sinus. The specimens were examined by means of a stereomicroscope and, in several cases, scanning electron microscopy was also used. The relationships between anomalous coronary artery patterns and aortic valve morphologies were tested using a logistic regression model. The results obtained indicate that there is no discontinuity between tricuspid and bicuspid aortic valves regarding the incidence of coronary artery anomalies. The probability of occurrence of anomalous coronary artery patterns increases continuously according to the deviation degree of the aortic valve from its normal (tricuspid) design. The present findings suggest that in the Syrian hamster, the morphogenetic mechanisms involved in the formation of congenital anomalous aortic valves and anomalies in the origin of the left coronary artery, respectively, are strongly related from an aetiological viewpoint.     

Landscape genomic signatures indicate reduced gene flow and forest‐associated adaptive divergence in an endangered neotropical turtle

Human‐induced transformations of ecosystems usually result in fragmented populations subject to increased extinction risk. Fragmentation is also often associated with novel environmental heterogeneity, which in combination with restricted gene flow may increase the opportunity for local adaptation. To manage at‐risk populations in these landscapes, it is important to understand how gene flow is changing, and how populations respond to habitat loss. We conducted a landscape genomics analysis using Restriction‐site Associated DNA sequencing to investigate the evolutionary response of the critically endangered Dahl's Toad‐headed turtle (Mesoclemmys dahli) to severe habitat modification. The species has lost almost all of its natural habitat in the southwestern part of its range and about 70% in the northeast. Based on least cost path analysis across different resistance surfaces for 3,211 SNPs, we found that the landscape matrix is restricting gene flow, causing the fragmentation of the species into at least six populations. Genome scans and allele‐environment association analyses indicate that the population fragments in the deforested grasslands of the southwest are adaptively different from those in the more forested northeast. Populations in areas with no forest had low levels of adaptive genetic diversity and the fixation of ancestrally‐polymorphic SNPs, consistent with directional selection in this novel environment. Our results suggest that this forest‐stream specialist is adapting to pond‐grassland conditions, but it is also suffering from negative consequences of habitat loss, including genetic erosion, isolation, small effective population sizes, and inbreeding. We recommend gene flow restoration via genetic rescue to counteract these threats, and provide guidance for this strategy.