Biology subjects

German, D.

Publications and source records attributed to German, D..

4 recordsLinked to original sources

bioRxiv2025

Boechera or not? Genomic insights and taxonomic reassessment of the misclassified Asian species B. calcarea (Brassicaceae)

The genus Boechera (Brassicaceae) serves as a model system for studying apomictic reproduction and ecological adaptations, with most species concentrated in North America. Rare occurrences of Boechera species beyond their typical range offers unique opportunities to investigate genome evolution in extralimital environments. One such species, B. calcarea, was described from the Chandalaz Range in northeastern Asia (Russia). This study aimed to investigate the genome structure and evolutionary history of B. calcarea. However, our analyses reveal that the species does not belong to Boechera. Instead, an integrative approach combining cytogenetic, phylogenetic and repeatome analyses identified the species as a member of an ancestral clades within the tribe Arabideae. The diploid Parryodes calcarea (Dudkin) D.A.German & Lysak (2n = 16) exhibits Arabideae-specific chromosomal signatures, including multiple centromere repositionings. These findings clarify the misattribution of P. calcarea to Boechera, leaving Boechera falcata and Borodinia macrophylla as the only Old World representatives of the Boechereae. This study highlights the importance of integrative methodologies in resolving taxonomic ambiguities and provides new insights into the diversification of the largest cruciferous tribe, Arabideae.

plant biology↗

bioRxiv2019

Does Sex Modify an Association of Electrophysiological Substrate with Sudden Cardiac Death? The Atherosclerosis Risk in Communities (ARIC) Study

BackgroundSex is a well-recognized risk factor for sudden cardiac death (SCD). Sex differences in electrophysiological (EP) substrate of SCD are known. However, it remains unknown whether sex can modify an association of EP substrate with SCD.\n\nMethodsParticipants from the Atherosclerosis Risk in Communities study with analyzable ECGs (n=14,725; age, 54.2{+/-}5.8 yrs; 55% female, 74% white) were included. EP substrate was characterized by traditional 12-lead ECG (heart rate, QRS, QTc, Cornell voltage), spatial ventricular gradient (SVG) and sum absolute QRST integral (SAI QRST) metrics. Two competing outcomes were adjudicated SCD and nonSCD. Interaction of ECG metrics with sex was studied in Cox proportional hazards and Fine-Gray competing risk models. Relative hazard ratio (RHR) and relative sub-hazard ratio (RSHR) with a 95% confidence interval for SCD and nonSCD risk for women relative to men were calculated. Model 1 was adjusted for prevalent cardiovascular disease (CVD) and risk factors. Time-updated model 2 was additionally adjusted for incident non-fatal CVD.\n\nResultsOver a median follow-up of 24.4 years, there were 530 SCDs (incidence 1.72 (1.58-1.88)/1000 person-years) and 2,178 nonSCDs (incidence 7.09; (6.80-7.39)/ 1000 person-years). Women experienced a greater than men risk of SCD associated with Cornell voltage (RHR 1.18(1.06-1.32); P=0.003), SAI QRST (RHR 1.16(1.04-1.30); P=0.007), area SVG magnitude (RHR 1.24(1.05-1.45); P=0.009), and peak SVG magnitude (RHR 1.22(1.04-1.44); P=0.018), independently from incident CVD. Greater risk of SCD for women than men associated with QRS duration (RHR 1.24(1.07-1.44); P=0.004) and QTc (RSHR 1.15(1.02-1.30); P=0.025) was explained by incident CVD. Furthermore, women had greater odds of SCD associated with heart rate (RSHR 1.19(1.01-1.40); P=0.036), independently of incident CVD.\n\nConclusionsSex modifies an association of EP substrate with SCD. In women, global EP substrate is associated with up to 27% greater risk of SCD than in men. Development of sex-specific risk scores of SCD is necessary. Further studies of mechanisms behind sex differences in EP substrate of SCD are warranted.

epidemiology↗

bioRxiv2019

Dynamic Predictive Accuracy of Electrocardiographic Biomarkers of Sudden Cardiac Death within a Survival Framework: The Atherosclerosis Risk in Communities (ARIC) study

BackgroundThe risk of sudden cardiac death (SCD) is known to be dynamic. However, an accuracy of a dynamic SCD prediction, and \"expiration date\" of ECG biomarkers is unknown. Our goal was to measure dynamic predictive accuracy of ECG biomarkers of SCD and competing outcomes.\n\nMethodsAtherosclerosis Risk In Community study participants with analyzable digital ECGs were included (n=15,768; 55% female, 73% white, age 54.2{+/-}5.8 y). ECGs of 5 follow-up visits were analyzed. Global electrical heterogeneity (GEH) and traditional ECG metrics were measured. Adjudicated SCD served as the primary outcome; non-sudden cardiac death served as competing outcome. Time-dependent area under the (receiver operating characteristic) curve (AUC) analysis was performed to assess prediction accuracy of a continuous biomarker in a period of 3,6,9 months, and 1,2,3,5,10, and 15 years, using survival analysis framework.\n\nResultsOver a median 24.4 y follow-up, there were 581 SCDs (incidence 1.77 (95%CI 1.63-1.92)/1,000 person-years), and 838 nonSCDs [2.55 (95%CI 2.39-2.73)]. Resting heart rate was the strongest (AUC 0.930) short-term (3-month) non-specific SCD predictor, whereas spatial peak QRS-T angle predicted specifically SCD 15 years after ECG recording (AUC 0.719). QRS duration (AUC 0.885) and QTc (AUC 0.711) short-term predicted advanced structural heart disease better than SCD. \"Expiration date\" for most ECG biomarkers was two years after ECG recording. GEH significantly improved reclassification of SCD risk beyond age, sex, race, diabetes, hypertension, coronary heart disease and stroke.\n\nConclusionShort-term predictors of SCD, nonSCD, and biomarkers of long-term SCD risk differed, reflecting differences in transient vs. persistent SCD substrates.

epidemiology↗

bioRxiv2018

Physiological genomics of dietary adaptation in a marine herbivorous fish

Adopting a new diet is a significant evolutionary change and can profoundly affect an animals physiology, biochemistry, ecology, and its genome. To study this evolutionary transition, we investigated the physiology and genomics of digestion of a derived herbivorous fish, the monkeyface prickleback (Cebidichthys violaceus). We sequenced and assembled its genome and digestive transcriptome and revealed the molecular changes related to important dietary enzymes, finding abundant evidence for adaptation at the molecular level. In this species, two gene families experienced expansion in copy number and adaptive amino acid substitutions. These families, amylase, and bile salt activated lipase, are involved digestion of carbohydrates and lipids, respectively. Both show elevated levels of gene expression and increased enzyme activity. Because carbohydrates are abundant in the pricklebacks diet and lipids are rare, these findings suggest that such dietary specialization involves both exploiting abundant resources and scavenging rare ones, especially essential nutrients, like essential fatty acids.

genomics↗