Interchromosomal Duplications on the Bactrocera oleae Y Chromosome Imply a Distinct Evolutionary Origin of the Sex Chromosomes Compared to Drosophila

BACKGROUND: Diptera have an extraordinary variety of sex determination mechanisms, and Drosophila melanogaster is the paradigm for this group. However, the Drosophila sex determination pathway is only partially conserved and the family Tephritidae affords an interesting example. The tephritid Y chromosome is postulated to be necessary to determine male development. Characterization of Y sequences, apart from elucidating the nature of the male determining factor, is also important to understand the evolutionary history of sex chromosomes within the Tephritidae. We studied the Y sequences from the olive fly, Bactrocera oleae. Its Y chromosome is minute and highly heterochromatic, and displays high heteromorphism with the X chromosome. METHODOLOGY/PRINCIPAL FINDINGS: A combined Representational Difference Analysis (RDA) and fluorescence in-situ hybridization (FISH) approach was used to investigate the Y chromosome to derive information on its sequence content. The Y chromosome is strewn with repetitive DNA sequences, the majority of which are also interdispersed in the pericentromeric regions of the autosomes. The Y chromosome appears to have accumulated small and large repetitive interchromosomal duplications. The large interchromosomal duplications harbour an importin-4-like gene fragment. Apart from these importin-4-like sequences, the other Y repetitive sequences are not shared with the X chromosome, suggesting molecular differentiation of these two chromosomes. Moreover, as the identified Y sequences were not detected on the Y chromosomes of closely related tephritids, we can infer divergence in the repetitive nature of their sequence contents. CONCLUSIONS/SIGNIFICANCE: The identification of Y-linked sequences may tell us much about the repetitive nature, the origin and the evolution of Y chromosomes. We hypothesize how these repetitive sequences accumulated and were maintained on the Y chromosome during its evolutionary history. Our data reinforce the idea that the sex chromosomes of the Tephritidae may have distinct evolutionary origins with respect to those of the Drosophilidae and other Dipteran families

Function and fate of myofibroblasts after myocardial infarction.

The importance of cardiac fibroblasts in the regulation of myocardial remodelling following myocardial infarction (MI) is becoming increasingly recognised. Studies over the last few decades have reinforced the concept that cardiac fibroblasts are much more than simple homeostatic regulators of extracellular matrix turnover, but are integrally involved in all aspects of the repair and remodelling of the heart that occurs following MI. The plasticity of fibroblasts is due in part to their ability to undergo differentiation into myofibroblasts. Myofibroblasts are specialised cells that possess a more contractile and synthetic phenotype than fibroblasts, enabling them to effectively repair and remodel the cardiac interstitium to manage the local devastation caused by MI. However, in addition to their key role in cardiac restoration and healing, persistence of myofibroblast activation can drive pathological fibrosis, resulting in arrhythmias, myocardial stiffness and progression to heart failure. The aim of this review is to give an appreciation of both the beneficial and detrimental roles of the myofibroblast in the remodelling heart, to describe some of the major regulatory mechanisms controlling myofibroblast differentiation including recent advances in the microRNA field, and to consider how this cell type could be exploited therapeutically

Bedside prediction of the progress of pressure ulcer healing in patients with spinal cord injury using the 'Decu-stick'

Study design: This is a prospective cohort study. Objectives: The objective of this study was to predict the progress of healing of pressure ulcers (PUs) in spinal cord injury (SCI) patients after the first 4 weeks. Setting: The study was conducted in a specialized SCI rehabilitation unit in The Netherlands. Methods: Weekly measurements of length, width and depth/undermining of grades II-IV PUs under sacrum or ischial tuberosity in SCI patients with the 'Decu-stick' were taken. The speed of reduction of the greatest dimension in the first 4 weeks of the granulation-epithelization (G-E) phase was compared with the speed of reduction of this dimension after week 4 until the end of observation. Results: Fifty-one PUs in 45 patients were measured. During the first 4 weeks of the G-E phase, the greatest dimension of 23/51 PUs reduced with a speed of >= 0.5 cm per week. In 22 of these 23 PUs, this speed remained >= 0.5 from week 4 until the end of observation (weeks 5-22). Closure: 21 patients (pts); operation: 2 pts. Of 28/51 PUs, this dimension reduced with Conclusion: Measurement of PUs in SCI patients with the 'Decu-stick' provides a reliable, quick, cheap and easy-to-learn bedside method to predict the progress of healing in PUs in SCI patients after 4 weeks of conservative treatment with a positive predictive value of 0.95 and an negative predictive value of 0.96. This provides a scientific basis for the decision on operative or alternative conservative treatment