Experimentally evolving Drosophila erecta populations may fail to establish an effective piRNA-based host defense against invading P-elements.

To prevent the spread of transposable elements (TEs), hosts have developed sophisticated defense mechanisms. In mammals and invertebrates, a major defense mechanism operates through PIWI-interacting RNAs (piRNAs). To investigate the establishment of the host defense, we introduced the P-element, one of the most widely studied eukaryotic transposons, into naive lines of Drosophila erecta We monitored the invasion in three replicates for more than 50 generations by sequencing the genomic DNA (using short and long reads), the small RNAs, and the transcriptome at regular intervals. A piRNA-based host defense was rapidly established in two replicates (R1, R4) but not in a third (R2), in which P-element copy numbers kept increasing for over 50 generations. We found that the ping-pong cycle could not be activated in R2, although the ping-pong cycle is fully functional against other TEs. Furthermore, R2 had both insertions in piRNA clusters and siRNAs, suggesting that neither of them is sufficient to trigger the host defense. Our work shows that control of an invading TE requires activation of the ping-pong cycle and that this activation is a stochastic event that may fail in some populations, leading to a proliferation of TEs that ultimately threaten the integrity of the host genome.

Metabolic syndrome - cardiac structure and functional analysis by echocardiography; a cross sectional comparative study.

OBJECTIVES: Metabolic syndrome (MS) is a collection of metabolic disorders including hyperglycemia, hypertension and dyslipidemia. The outcome of metabolic syndrome depends on structural changes in heart like increased left atrial size or increased left ventricular mass. This study was done to determine the echocardiography abnormalities in metabolic syndrome. METHODS: After obtaining informed consent, 75 subjects with metabolic syndrome and 75 controls were included in the study. 2D echo/M mode examination was performed for all. Aortic root, left atrial size, left atrial volume, septal wall thickness during systole (SWs) and diastole (SWd), posterior wall thickness during systole (PWs) and diastole (PWd), left ventricle dimension during systole (LVDs) and diastole (LVDd), and ejection fraction were measured. The values were compared between the groups. RESULTS: After adjustment for age, sex, smoking, alcohol and BMI; left ventricular diameter in systole and diastole was significantly more than controls (p<0.001); HR of 1.29 (95% CI 1.13-1.46), 1.29 (95% CI 1.15-1.45) respectively. Left ventricular mass and left atrial volume were increased significantly in subjects with metabolic syndrome (p<0.001); HR were 1.06 (95% CI 1.03-1.08), 1.13 (95% CI 1.06-1.19) respectively. Ejection fraction was low normal in subjects with metabolic syndrome compared to controls (p<0.05); HR 0.90 (95% CI 0.83-0.98). CONCLUSIONS: Cardiac abnormalities were common in subjects with metabolic syndrome, predominantly affecting the left ventricular mass, diameter and left atrial volume. Early life style modifications are essential to prevent these complications.

Association of Cervical Vestibular-Evoked Myogenic Potentials (VEMP) and Postural Instability in Patients with Parkinson's Disease: A Cross-Sectional Study.

Background: Postural instability is a common problem in patients with Parkinson's disease (PD). The appropriate cooperation of vestibular, visual, and proprioceptive signals along with apt anticipatory and adaptive postural responses is essential for postural stability. Abnormalities in this sensorimotor admixture lead to postural instability in PD. The function of vestibular otolith function and its central connections in postural instability of PD is still obscure. Cervical vestibular-evoked myogenic potentials (VEMP) can be used to assess the function of the saccular part of otolith and its connections. Purpose: We aimed to study the role of dysfunction of the saccule and its connections at the brainstem by comparing the VEMP with normal controls and correlating it with the postural instability in patients with PD. Methods: Thirty patients with PD and 30 healthy volunteers were included in the study, after obtaining the institutional ethical committee approval. Patient's demographic data, stage and duration of illness, treatment history, history of fall, postural instability, Unified Parkinson's Disease Rating Scale (UPDRS) score, and Non-Motor Symptoms Scales (NMSs) were noted. Cervical VEMP analysis was done for both patients and controls. Results and Conclusion: Patients with absent VEMP had significant postural instability, a history of falls, and a high UPDRS score. Mean P13 and N23 latencies were prolonged, and the amplitude was significantly low in patients with PD. Absent cVEMP was significantly associated with postural instability, non-motor symptoms, especially gastrointestinal, miscellaneous symptoms, and mood/cognition. VEMP can be considered an early electrophysiological marker for dysfunction of otolith and its central connections.

Reconstructing the Invasion Route of the P-Element in Drosophila melanogaster Using Extant Population Samples.

The P-element, one of the best understood eukaryotic transposable elements, spread in natural Drosophila melanogaster populations in the last century. It invaded American populations first and later spread to the Old World. Inferring this invasion route was made possible by a unique resource available in D. melanogaster: Many strains sampled from different locations over the course of the last century. Here, we test the hypothesis that the invasion route of the P-element may be reconstructed from extant population samples using internal deletions (IDs) as markers. These IDs arise at a high rate when DNA transposons, such as the P-element, are active. We suggest that inferring invasion routes is possible as: 1) the fraction of IDs increases in successively invaded populations, which also explains the striking differences in the ID content between American and European populations, and 2) successively invaded populations end up with similar sets of IDs. This approach allowed us to reconstruct the invasion route of the P-element with reasonable accuracy. Our approach also sheds light on the unknown timing of the invasion in African populations: We suggest that African populations were invaded after American but before European populations. Simulations of TE invasions in spatially distributed populations confirm that IDs may allow us to infer invasion routes. Our approach might be applicable to other DNA transposons in different host species.