Biology subjects

Swain, B.

Publications and source records attributed to Swain, B..

4 recordsLinked to original sources

bioRxiv2026

Effects of cross-generational inbreeding and Wolbachia infection on sex ratio and life-history traits in parthenium beetle

Sex ratio is a key demographic parameter shaping population dynamics and evolutionary trajectories. In biocontrol agents, demographic bottlenecks during species introduction to a new habitat and subsequent mass rearing can elevate inbreeding, potentially biasing sex ratios through sex-specific mortality associated with inbreeding depression. Moreover, reproductive endosymbionts such as Wolbachia are known to manipulate host reproduction and further skew sex ratios. However, the relative contributions of these processes to sex-ratio variation remain poorly resolved. In this study, we evaluated the effects of cross-generational full-sibling inbreeding and Wolbachia infection on sex ratio and key life-history traits in the biocontrol beetle Zygogramma bicolorata using controlled laboratory crosses across three generations. Inbreeding did not significantly alter offspring sex ratio, which remained close to parity across generations, while pupal mortality increased in later generations, consistent with delayed expression of inbreeding depression. Adult body weight remained largely unaffected by inbreeding. Wolbachia infection was detected in a subset of females and was associated with a modest but significant increase in female-biased offspring production, although the effect was variable across lineages. Strain typing identified a single supergroup A Wolbachia, consistent with previous descriptions of the wBic strain from this species. These findings indicate that sex-ratio variation in introduced populations of Z. bicolorata is not driven by inbreeding alone but instead emerges from the interaction between demographic processes and symbiont-mediated effects, providing crucial insights for optimizing biocontrol programs where sex-ratio stability is essential for population establishment and persistence. SignificanceSex ratio is a key determinant of population growth and stability - the essential parameters determining success of biocontrol programs. Yet, the mechanisms shaping sex-ratio variation remain poorly resolved. Using controlled crosses in Zygogramma bicolorata, we show that short-term inbreeding does not directly alter sex allocation, despite inducing delayed fitness costs through increased pupal mortality. In contrast, Wolbachia infection contributes to female-biased offspring production, although with variable outcome across lineages. These findings demonstrate that sex-ratio variation in Z. bicolorata arises from the interaction of demographic processes and symbiont effects, rather than a single mechanism, with important implications for predicting the establishment, persistence, and efficacy of mass-reared biocontrol populations.

ecology↗

bioRxiv2025

Deep Learning-Based Genetic Perturbation Models Do Outperform Uninformative Baselines on Well-Calibrated Metrics

Single cell genetic perturbation modeling involves predicting the effects of unobserved genetic manipulations, enabling scalable in silico screens for target discovery. Recent reports have claimed that deep learning-based perturbation models fail to outperform uninformative baselines, raising doubts about their utility. Here, we show that these conclusions largely stem from limitations of benchmarking metrics, not from the models themselves. We introduce a framework for evaluating bench-mark metric calibration using positive and negative controls, including a new positive control baseline (the interpolated duplicate) and a quantitative calibration measure (the dynamic range fraction). Across 14 perturbation datasets and 13 evaluation metrics, we find that conventional metrics such as mean squared error (MSE) and control-referenced delta correlation (Pearson({Delta}ctrl)) are often poorly calibrated, whereas weighted and rank-based alternatives exhibit consistent calibration. Under well-calibrated metrics, deep learning models outperform mean, control, and linear baselines, and in some cases even surpass the additive baseline in combination-prediction tasks. Calibrated evaluation thus explains prior reports of model underperformance, revealing that deep learning models do outperform uninformative baselines.

bioinformatics↗

bioRxiv2025

A regulatory region that controls Wnt gene expression following tissue injury is required for proper muscle regeneration

The capacity to detect and respond to injury is critical for the recovery and long-term survival of many organisms. Wnts are commonly induced by tissue damage but how they become activated transcriptionally is not well understood. Here, we report that mouse Wnt1 and Wnt10b are induced following injury in both lung and muscle. These Wnts occupy the same chromosome and are transcribed in opposite directions with 12kb between them. We identified a highly conserved cis-acting regulatory region (enhancer) residing between Wnt1 and Wnt10b that, when fused to a LacZ reporter, is activated post-injury. This enhancer harbors putative AP-1 binding sites that are required for reporter activity, a feature observed in other injury-responsive enhancers. Injured muscles in mice carrying a germ-line deletion of the enhancer region display reduced Wnt1 and Wnt10b expression and show elevated intramuscular adipogenesis--a hallmark of impaired regenerative capacity--revealing a requirement of this enhancer for proper regeneration. Enhancer redundancy is common in development, but our in vivo analysis shows that loss of a single injury-responsive regulatory region in adult tissues can produce a detectable regenerative phenotype. SummaryA new, previously unknown shared regulatory region residing between two Wnts, Wnt1 and Wnt10b, is induced by tissue damage and required for muscle regeneration.

developmental biology↗

bioRxiv2023

GABAergic signaling shapes multiple aspects of Drosophila courtship motor behavior

Inhibitory neurons are essential for nervous system function. GABA is the most important neurotransmitter for fast neuronal inhibition in vertebrates and invertebrates. GABAergic signaling in sex specific, fruitless expressing neuronal circuits of Drosophila is required for multiple aspects of male courtship behavior. RNAi mediated knockdown of the GABA producing enzyme Gad1 and the ionotropic receptor Rdl in the ventral nerve cord causes uncoordinated and futile copulation attempts, defects in wing extension choice and severe alterations of courtship song. Altered song of GABA depleted males fails to stimulate female receptivity, but rescue of song patterning alone is not sufficient to rescue male mating success. Knockdown of Gad1 and Rdl in brain circuits abolishes courtship conditioning. We characterize the around 220 neurons coexpressing Gad1 and Fruitless in the Drosophila male nervous system and propose inhibitory circuit motifs underlying key features of courtship behavior based on the observed phenotypes.

neuroscience↗