558 research outputs found

    Maize Chromosome Abnormalities and Breakage-Fusion-Bridge Cycles in Callus Cultures

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    The maize karyotype was first characterized by the observation of pachytene chromosomes. The somatic chromosomes were identified by C-banding and FISH with repetitive DNA sequences. C-banding was useful for the identification of chromosome abnormalities in callus cultures. In the present review, we focus on the involvement of heterochromatic knobs on the occurrence of chromosome abnormalities in callus cultures. In a previous work we detected anaphase bridges resulting from delayed chromatid separation at knob regions and typical bridges derived from dicentric chromatids in cultures. The analysis of altered chromosomes showed they were derived from a chromatid-type breakage-fusion-bridge (BFB) cycle. Fluorescent in situ hybridization (FISH) showed signals of telomere sequences in the broken chromosome arm, thus giving evidence of de novo telomere formation on the broken chromosome end. Further observations of long- and short-term cultures have shown the presence of chromosome alterations derived from BFB cycles followed by chromosome healing. Additionally, the occurrence of unequal crossing over in a knob region was observed in callus culture. These results are of interest for studies on the mechanisms of chromosome alterations during evolution

    Changing dietary habits in veneto region over two decades: Still a long road to go to reach an iodine-sufficient status

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    Background: Fifteen years after a nationwide voluntary iodine prophylaxis program was introduced, the aims of the present study were: (a) to obtain an up-to-date assessment of dietary iodine intake in the Veneto region, Italy; and (b) to assess dietary and socioeconomic factors that might influence iodine status. Methods: Urinary iodine concentration (UIC) was obtained in 747 school students (median age 13 years; range: 11–16 years). Results: The median UIC was 111 _g/L, with 56% of samples _ 100 _g/L, but 26% were < 50 _g/L, more frequently females. Iodized salt was used by 82% of the students. The median UIC was higher among users of iodized salt than among non-users, 117.0 ug/L versus 90 ug/L (p = 0.01). The median UIC was higher in regular consumers of cow’s milk than in occasional consumers, 132.0 _g/L versus 96.0 _g/L (p < 0.01). A regular intake of milk and/or the use of iodized salt su_ced to reach an adequate median UIC, although satisfying only with the combined use. A trend towards higher UIC values emerged in regular consumers of cheese and yogurt. Conclusion: Iodine status has improved (median UIC 111.0 _g/L), but it is still not adequate as 26% had a UIC < 50 _g/L in the resident population of the Veneto region. A more widespread use of iodized salt but also milk and milk product consumption may have been one of the key factors in achieving this partial improvement

    I.C.E.: An Ultra-Cold Atom Source for Long-Baseline Interferometric Inertial Sensors in Reduced Gravity

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    The accuracy and precision of current atom-interferometric inertialsensors rival state-of-the-art conventional devices using artifact-based test masses . Atomic sensors are well suited for fundamental measurements of gravito-inertial fields. The sensitivity required to test gravitational theories can be achieved by extending the baseline of the interferometer. The I.C.E. (Interf\'erom\'etrie Coh\'erente pour l'Espace) interferometer aims to achieve long interrogation times in compact apparatus via reduced gravity. We have tested a cold-atom source during airplane parabolic flights. We show that this environment is compatible with free-fall interferometric measurements using up to 4 second interrogation time. We present the next-generation apparatus using degenerate gases for low release-velocity atomic sources in space-borne experiments

    Complications and mortality of Cushing’s disease: report on data collected over a 20-year period at a referral centre

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    Context: Cushing’s disease (CD) is rare condition burdened by several systemic complications correlated to higher mortality rates. The primary goal of clinicians is to achieve remission, but it is unclear if treatment can also increase life expectancy. Aim: To assess the prevalence of cortisol-related complications and mortality in a large cohort of CD patients attending a single referral centre. Materials and methods: The clinical charts of CD patients attending a referral hospital between 2001 and 2021 were reviewed. Results: 126 CD patients (median age at diagnosis 39 years) were included. At the last examination, 78/126 (61.9%) of the patients were in remission regardless of previous treatment strategies. Patients in remission showed a significant improvement in all the cardiovascular (CV) comorbidities (p < 0.05). The CV events were more frequent in older patients (p = 0.003), smokers and persistent CD groups (p < 0.05). Most of the thromboembolic (TE) and infective events occurred during active stages of the disease. The CV events were the most frequent cause of death. The standardized mortality ratio (SMR) resulted increased in persistent cases at the last follow-up (SMR 4.99, 95%CI [2.15; 9.83], p < 0.001) whilst it was not higher in those in remission (SMR 1.66, 95%CI [0.34; 4.85], p = 0.543) regardless of the timing or number of treatments carried out. A younger age at diagnosis (p = 0.005), a microadenoma (p = 0.002), and remission status at the last follow-up (p = 0.027) all increased survival. Furthermore, an elevated number of comorbidities, in particular arterial hypertension, increased mortality rates. Conclusions: Patients with active CD presented a poor survival outcome. Remission restored the patients’ life expectancy regardless of the timing or the types of treatments used to achieve it. Persistent CD-related comorbidities remained major risk factors

    Karyotype variability in tropical maize sister inbred lines and hybrids compared with kys standard line.

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    Maize karyotype variability has been extensively investigated. The identification of maize somatic and pachytene chromosomes has improved with the development of fluorescence in situ hybridization (FISH) using tandemly repeated DNA sequences as probes. We identified the somatic chromosomes of sister inbred lines that were derived from a tropical flint maize population (Jac Duro [JD]), and hybrids between them, using FISH probes for the 180-bp knob repeat, centromeric satellite (CentC), centromeric satellite 4 (Cent4), subtelomeric clone 4-12-1, 5S ribosomal DNA and nucleolus organizing region DNA sequences. The observations were integrated with data based on C-banded mitotic metaphases and conventional analysis of pachytene chromosomes. Heterochromatic knobs visible at pachynema were coincident with C-bands and 180-bp FISH signals on somatic chromosomes, and most of them were large. Variation in the presence of some knobs was observed among lines. Small 180-bp knob signals were invariant on the short arms of chromosomes 1, 6, and 9. The subtelomeric 4-12-1 signal was also invariant and useful for identifying some chromosomes. The centromere location of chromosomes 2 and 4 differed from previous reports on standard maize lines. Somatic chromosomes of a JD line and the commonly used KYS line were compared by FISH in a hybrid of these lines. The pairing behavior of chromosomes 2 and 4 at pachytene stage in this hybrid was investigated using FISH with chromosome-specific probes. The homologues were fully synapsed, including the 5S rDNA and CentC sites on chromosome 2, and Cent4 and subtelomeric 4-12-1 sites on chromosome 4. This suggests that homologous chromosomes could pair through differential degrees of chromatin packaging in homologous arms differing in size. The results contribute to current knowledge of maize global diversity and also raise

    Genetic pattern and demographic history of Salminus brasiliensis: population expansion in the Pantanal Region during the Pleistocene

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    Pleistocene climate changes were major historical events that impacted South American biodiversity. Although the effects of such changes are well-documented for several biomes, it is poorly known how these climate shifts affected the biodiversity of the Pantanal floodplain. Fish are one of the most diverse groups in the Pantanal floodplains and can be taken as a suitable biological model for reconstructing paleoenvironmental scenarios. To identify the effects of Pleistocene climate changes on Pantanal?s ichthyofauna, we used genetic data from multiple populations of a top-predator longdistance migratory fish, Salminus brasiliensis. We specifically investigated whether Pleistocene climate changes affected the demography of this species. If this was the case, we expected to find changes in population size over time. Thus, we assessed the genetic diversity of S. brasiliensis to trace the demographic history of nine populations from the Upper Paraguay basin, which includes the Pantanal floodplain, that form a single genetic group, employing approximate Bayesian computation (ABC) to test five scenarios: constant population, old expansion, old decline, old bottleneck following by recent expansion, and old expansion following by recent decline. Based on two mitochondrial DNA markers, our inferences from ABC analysis, the results of Bayesian skyline plot, the implications of star-like networks, and the patterns of genetic diversity (high haplotype diversity and low-to-moderate nucleotide diversity) indicated a sudden population expansion. ABC allowed us to make strong quantitative inferences about the demographic history of S. brasiliensis. We estimated a small ancestral population size that underwent a drastic fivefold expansion, probably associated with the colonization of newly formed habitats. The estimated time of this expansion was consistent with a humid and warm phase as inferred by speleothem growth phases and travertine records during Pleistocene interglacial periods. The strong concordance between our genetic inferences and this historical data could represent the first genetic record of a humid and warm phase in the Pantanal in the period since the Last Interglacial to 40 ka
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