Biology subjects

Ross, P.

Publications and source records attributed to Ross, P..

11 recordsLinked to original sources

bioRxiv2026

Novel but stable endosymbionts have contrasting effects on aphid dispersal and plant feeding damage in the cereal pest Diuraphis noxia

Endosymbiotic bacteria can affect many ecological attributes of their insect hosts, including (in herbivorous insects) how insects interact with plants where they feed. This raises the issue of whether deliberate endosymbiont introductions could be used to decrease crop damage caused by insect pests. Here we investigate how transinfecting Rickettsiella viridis and Regiella insecticola endosymbionts into a novel pest aphid host, the Russian wheat aphid (Diuraphis noxia), influences population growth, alate production, dispersal ability and crop damage. Both the Rickettsiella (originating from pea aphids) and Regiella (from green peach aphids) were stably maintained in their new host where they had contrasting effects. Rickettsiella increased the severity of aphid damage on wheat and barley, resulting in greater leaf loss, chlorotic streaking, and higher aphid populations, whereas Regiella reduced aphid population growth and the severity of feeding damage by aphids. Their effects on dispersal morphology also differed: Regiella had no detectable impact on alate incidence, while Rickettsiella consistently suppressed wing formation in small cages, and in larger mesocosms with multiple wheat plants this endosymbiont suppressed dispersal. Endosymbiont-mediated changes in feeding damage did not involve the main plant immune response pathways: transinfected and wild type aphids induced similar levels of jasmonic acid, jasmonic acid-isoleucine, and salicylic acid in plant tissues, even though these plant defenses were strongly activated during aphid feeding. Novel endosymbionts can therefore modulate the severity of plant feeding damage by aphids as well as influencing aphid dispersal. Potential applications in controlling pest D. noxia populations are discussed. Significance statementEndosymbiotic bacteria that live within insect cells can have wide-ranging effects on the reproduction and fitness of their insect hosts in different environments. In herbivorous insects this includes effects on host plant use. Here we test if novel endosymbionts in a pest aphid, the Russian wheat aphid, might be used to decrease crop damage and dispersal. We show that the damage caused to wheat and barley plants from aphid feeding is modulated by novel but stably transmitted introduced endosymbionts. One endosymbiont (Rickettsiella) increased the severity of damage but decreased aphid dispersal, while another (Regiella) decreased damage severity without impacting dispersal. These contrasting effects may be associated with changes in aphid population growth and wing formation but were not linked to key plant immune response pathways. We discuss implications of these findings for using endosymbionts in agricultural pest management. Classification: Applied Biological Sciences, microbiology

microbiology↗

bioRxiv2024

Could Quantum-Mediated Bacterial Signaling Explain Adaptive Mutation?

The phenomenon of adaptive mutation in bacteria presents several challenges to classical models of evolution, particularly regarding the observed coordination of mutation patterns across populations. Here, we examine statistical evidence from evolved Escherichia coli populations showing mutation enrichment up to 256-fold above background rates in key metabolic genes, with remarkable temporal stability that appears to transcend known bacterial communication mechanisms. We propose a theoretical framework suggesting that bacteria may utilize quantum coherent oscillations, potentially mediated through synchronized membrane potential fluctuations, to achieve this degree of coordination in adaptive mutation. Building on Sprouffske et al.s findings that high mutation rates can limit adaptive evolution in E. coli, we examined mutation patterns in four key metabolic genes (pykF, topA, cspC, and rpoC) previously identified as targets of selection. While Sprouffske found that extremely high mutation rates impaired adaptation, our analysis reveals that these genes show non-random enrichment patterns (p < 1.76x10-34 for pykF) that maintain remarkable temporal stability across multiple timepoints. Recent advances in quantum biology have demonstrated sustained quantum coherence in biological systems, we present a model for how quantum-mediated bacterial signaling could potentially contribute to adaptive mutation. The framework makes several experimentally testable predictions about mutation patterns, population dynamics, and coherence times in bacterial populations under stress conditions. While substantial experimental validation remains necessary, this work provides specific approaches for investigating potential quantum contributions to bacterial adaptation, with implications for understanding evolutionary mechanisms and bacterial stress responses.

evolutionary biology↗

bioRxiv2024

Molecular characterization of the archaic HLA-B*73:01 allele reveals presentation of a unique peptidome and skewed engagement by KIR2DL2

HLA class I alleles of archaic origin may have been retained in modern humans because they provide immunity against diseases to which archaic humans had evolved resistance. According to this model, archaic introgressed alleles were somehow distinct from those that evolved in African populations. Here we show that HLA-B*73:01, a rare allotype with putative archaic origins, has a relatively rare peptide binding motif with an unusually long-tailed peptide length distribution. We also find that HLA-B*73:01 combines a restricted and unique peptidome with high-cell surface expression, characteristics that make it well-suited to combat one or a number of closely-related pathogens. Furthermore, a crystal structure of HLA-B*73:01 in complex with KIR2DL2 highlights differences from previously solved structures with HLA-C molecules. These molecular characteristics distinguish HLA-B*73:01 from other HLA class I alleles previously investigated and may have provided early modern human migrants that inherited this allele with a selective advantage as they colonized Europe and Asia.

biochemistry↗

bioRxiv2024

Entangled Evolution Model: Application to Adaptive Mutation

Adaptive mutation, the phenomenon where organisms appear to increase beneficial mutation rates in response to environmental stress, has challenged the traditional understanding of random mutations in evolutionary biology. Here, we present a novel computational model, the Entangled Evolution Model, which integrates quantum game theory and quantum walks to provide a new approach to understanding mutation dynamics. By applying the Clauser-Horne-Shimony-Holt (CHSH) quantum game within a modified Lotka-Volterra framework, we simulate how quantum entanglement can accelerate the rate of adaptive mutations in Escherichia coli populations. Our simulations reveal that entangled bacterial populations achieve successful adaptive mutations with an 85% probability, significantly surpassing the classical theoretical maximum. These results introduce a new perspective on computational approaches to evolutionary adaptation, offering an efficient algorithmic framework to explore the role of quantum effects in biological systems.

evolutionary biology↗

bioRxiv2024

Spatial localization of CD16a at the human NK cell ADCC lytic synapse

Natural Killer (NK) cells utilize effector functions, including antibody-dependent cellular cytotoxicity (ADCC), for the clearance of viral infection and cellular malignancies. NK cell ADCC is mediated by Fc{gamma}RIIIa (CD16a) binding to the fragment crystallizable (Fc) region of immunoglobulin G (IgG) within immune complexes on a target cell surface. While antibody-induced clustering of CD16a is thought to drive ADCC, the molecular basis for this activity has not been fully described. Here we use MINFLUX nanoscopy to map the spatial distribution of stoichiometrically labeled CD16a across the NK cell membrane, revealing the presence of pairs of CD16a molecules with intra-doublet distance of approximately 17 nm. NK cells activated on supported lipid bilayers by Trastuzumab results in an increase of synaptic regions with greater CD16a density. Our results provide the highest spatial resolution yet described for CD16a imaging, offering new insight into how CD16a organization within the immune synapse could influence ADCC activity. MINFLUX holds great promise to further unravel the molecular details driving CD16a-based activation of NK cells.

immunology↗

bioRxiv2022

Differences in gene expression in field populations of Wolbachia-infected Aedes aegypti mosquitoes with varying release histories in northern Australia

Aedes aegypti is the principal mosquito vector of dengue, yellow fever, Zika and chikungunya viruses. The wMel endosymbiotic bacteria Wolbachia pipientis has been introduced into this vector as a novel biocontrol strategy to stop transmission of these viruses. Mosquitoes with Wolbachia have been released in the field in North Queensland, Australia since 2011, at various locations and over several years, with populations remaining stably infected. Wolbachia infection is known to alter gene expression in its mosquito host, but whether (and how) this changes over the long-term in the context of field releases remains unknown. We sampled mosquitoes from Wolbachia-infected populations with different release histories along a time gradient and performed RNAseq to investigate gene expression changes in the insect host. We observed a significant impact on gene expression in Wolbachia-infected mosquitoes versus uninfected controls, but fewer genes had altered expression in the older releases (e.g. the year 2011) versus the more recent releases (e.g. 2017). Nonetheless, a fundamental signature of Wolbachia infection on host gene expression was observed across all releases, comprising upregulation of immunity and metabolism genes. There was limited downregulation of gene expression in the older releases, but significantly more in the most recent release. Our findings indicate that at > 8 years post-introgression into field populations, Wolbachia continues to profoundly impact host gene expression, particularly genes involved in insect immune response. We suggest that if gene expression changes underlie blocking of virus replication in Wolbachia-infected Ae. aegypti, then refractoriness of these mosquitoes to arboviruses may remain stable over the long-term. Author summaryThe Aedes aegypti mosquito is the main species responsible for urban transmission of dengue, Zika and chikungunya viruses. Control measures, including source reduction and insecticide treatment, have historically struggled to provide sustained control of this species to limit disease. An alternative approach involves releasing mosquitoes harbouring Wolbachia bacteria. Wolbachia inhibits virus transmission by Ae. aegypti and preliminary evidence indicates that dengue incidence is reduced in locations where it has been deployed. In this study, we found that Wolbachia significantly upregulates gene expression in Ae. aegypti at least 8 years after field deployment compared with uninfected controls, although some gene downregulation was also observed. We observed a more muted response in mosquitoes from populations with older release histories, with far fewer genes being differentially regulated versus those from the most recent release. Irrespective of release history, immune response and metabolism genes were significantly upregulated, and to a lesser extent genes related to behaviour. Our results, combined with previous studies that have revealed few changes in the Wolbachia genome post release, provide further evidence of the long-term stability of the Wolbachia-mosquito relationship in the field.

microbiology↗

bioRxiv2022

A comprehensive prediction of transcript isoforms in 19 chicken tissues by Oxford Nanopore long-read sequencing

To comprehensively identify and annotate transcript isoforms in the chicken genome, we generated Nanopore long-read sequencing data from a diverse set of 19 chicken tissues comprising 68 samples collected from experimental line 6 x line 7 F1 adult males and females. More than 23.8 million reads with mean read length of 790 bases and average quality of 18.2 were generated. The annotation and subsequent filtering resulted in identification of 55,382 transcripts with mean length of 1,700 bases at 40,547 loci, representing [~]1.4 transcripts per locus. Among them, we predicted 30,967 potential coding transcripts at 19,461 loci and 16,495 potential lncRNA transcripts at 15,512 loci. Compared to reference annotations, we found 52% of annotated transcripts could partially to fully match while 47% were novel and potentially transcribed from lncRNA loci. Based on our annotation, we quantified transcript expression across tissues and found brain tissues (i.e. cerebellum, cortex) expressed highest number of transcripts and loci. The further tissue specificity revealed that [~]22% of the transcripts displaying tissue specificity. Of them, the reproductive tissues (i.e. testis, ovary) contained the most tissue-specific transcripts. Despite sequencing 68 transcriptomes derived from 19 tissues, still [~]20% of Ensembl reference loci were not detected. This suggests that including additional samples from different cell types, developmental and physiological conditions, is needed to fully annotate the chicken genome. The application of Nanopore sequencing transcriptomes in this study demonstrated the usefulness of long-read data in discovering additional novel loci (e.g., lncRNA loci) and resolving complex transcripts (e.g., the longest transcript for the TTN locus).

genomics↗

bioRxiv2022

Sex-specific distribution and classification of Wolbachia infections and mitochondrial DNA haplogroups in Aedes albopictus from the Indo-Pacific

The arbovirus vector Aedes albopictus (Asian tiger mosquito) is common throughout the Indo-Pacific region, where most global dengue transmission occurs. We analysed population genomic data and tested for cryptic species in 160 Ae. albopictus sampled from 16 locations across this region. We found no evidence of cryptic Ae. albopictus but found multiple intraspecific COI haplotypes partitioned into groups representing three Asian lineages: East Asia, Southeast Asia and Indonesia. Papua New Guinea (PNG), Vanuatu and Christmas Island shared recent coancestry, and Indonesia and Timor-Leste were likely invaded from East Asia. We used a machine learning trained on morphologically sexed samples to classify sexes using multiple genetic features and then characterized the wAlbA and wAlbB Wolbachia infections in 664 other samples. The wAlbA and wAlbB infections as detected by qPCR showed markedly different patterns in the sexes. For females, most populations had a very high double infection incidence, with 67% being the lowest value (from Timor-Leste). For males, the incidence of double infections ranged from 100% (PNG) to 0% (Vanuatu). Only 6 females were infected solely by the wAlbA infection, while rare uninfected mosquitoes were found in both sexes. The wAlbA and wAlbB densities varied significantly among populations. For mosquitoes from Torres Strait and Vietnam, the wAlbB density was similar in single-infected and superinfected (wAlbA and wAlbB) mosquitoes. There was a positive association between wAlbA and wAlbB infection densities in superinfected Ae. albopictus. Our findings provide no evidence of cryptic species of Ae. albopictus in the region and suggest site-specific factors influencing the incidence of Wolbachia infections and their densities. We also demonstrate the usefulness of SNPs as sex-specific mosquito markers. The results provide baseline data for the exploitation of Wolbachia-induced cytoplasmic incompatibility (CI) in dengue control.

microbiology↗

bioRxiv2020

Can early exposure to stress enhance resilience to ocean warming in two oyster species?

Securing economically and ecologically significant molluscs, as our oceans warm and acidify due to climate change, is a global priority. South eastern Australia receives warm water in a strengthening East Australia Current and so resident species are vulnerable to elevated temperature and marine heat waves. This study tested whether oysters pre exposed to elevated temperature or heat stress enhances resilience to ocean warming later in life. Two Australian species, the flat oyster, Ostrea angasi, and the Sydney rock oyster, Saccostrea glomerata, were given a mild dose of warm water or "heat shock" stress in the laboratory and then transferred to elevated temperature conditions where we used the thermal outfall from power generation as a proxy to investigate the impacts of ocean warming. Shell growth, condition index, lipid content and profile and survival of oysters was impacted by elevated temperature in the field, with flat oysters being more impacted than Sydney rock oysters. Flat oysters grew faster than Sydney rock oysters at ambient temperature, but were more sensitive to elevated temperature. Early exposure to heat stress did little to ameliorate the negative effects of increased temperature, although the survival of heat shocked flat oysters was greater than non-heat shocked oysters. Further investigations are required to determine if early exposure to heat stress can act to inoculate oysters to future stress and overall enhance resilience of oysters to ocean warming.

ecology↗

bioRxiv2019

Refining the transcriptome of the human malaria parasite Plasmodium falciparum using amplification-free RNA-seq

Plasmodium parasites undergo several major developmental transitions during their complex lifecycle, which are enabled by precisely ordered gene expression programs. Transcriptomes from the 48-hour blood stages of the major human malaria parasite Plasmodium falciparum have been described using cDNA microarrays and RNA-seq, but these assays have not always performed well within non-coding regions, where the AT-content is often 90-95%. We developed a directional, amplification-free RNA-seq protocol (DAFT-seq) to reduce bias against AT-rich cDNA, which we have applied to three strains of P. falciparum (3D7, HB3 and IT). While strain-specific differences were detected, overall there is strong conservation between the transcriptional profiles. For the 3D7 reference strain, transcription was detected from 89% of the genome, with over 75% of the genome transcribed into mRNAs. These datasets allowed us to refine the 5 and 3 untranslated regions (UTRs), which can be variable, long (>1,000 nt), and often overlap those of adjacent transcripts. We also find that transcription from bidirectional promoters frequently results in non-coding, antisense transcripts. By capturing the 5 ends of mRNAs, we reveal both constant and dynamic use of transcriptional start sites across the intraerythrocytic developmental cycle resulting in an updated view of the P. falciparum transcriptome.

genomics↗

bioRxiv2019

Emotion Modulation of the Body-Selective Areas in the Developing Brain

Emotions are strongly conveyed by the human body and the ability to recognize emotions from body posture or movement is still developing through childhood and adolescence. To date, there are very few studies exploring how these behavioural observations are paralleled by functional brain development. Furthermore, there are currently no studies exploring the development of emotion modulation in these areas. In the current study, we used functional magnetic resonance imaging (fMRI) to compare the brain activity of 25 children (age 6-11), 18 adolescents (age 12-17) and 26 adults while they passively viewed short videos of angry, happy or neutral body movements. We observed that when viewing bodies generally, adults showed higher activity than children bilaterally in the body-selective areas; namely the extra-striate body area (EBA), fusiform body area (FBA), posterior superior temporal sulcus (pSTS) and amygdala (AMY). Adults also showed higher activity than adolescents, but only in right hemisphere body-selective areas. Crucially, however, we found that there were no age differences in the emotion modulation of activity in these areas. These results indicate, for the first time, that despite activity selective to body perception increasing across childhood and adolescence, emotion modulation of these areas in adult-like from 7 years of age. Conflict of InterestThe author declares that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

neuroscience↗