Biology subjects

Hampson, E.

Publications and source records attributed to Hampson, E..

4 recordsLinked to original sources

bioRxiv2026

Multiplex Genome Editing Overcomes Photoperiod Sensitivity in Tropical Maize

Tropical maize is a rich source of genetic diversity that could enhance temperate maize breeding programs, but its sensitivity to long-day photoperiods, resulting in delayed flowering, limits its widespread use. To overcome this barrier, the Genome Engineering to Sustain Crop Improvement (GETSCI) project used CRISPR/Cas9 to mutate three flowering repressor genes, ZmCCT9, ZmCCT10, and ZmRAP2.7, in the tropical inbred Tzi8. A single sgRNA targeting the first exon of each target gene was combined with an excision cassette carrying the morphogenic genes Babyboom (Bbm) and Wuschel2 (Wus2) to enable efficient transgenic plant regeneration. Transgenic plants carrying frameshift edits in each target gene were recovered, and subsequent crosses produced two non-transgenic genotypes: a double-edited zmcct10, zmrap2.7 line and a triple-edited zmcct9, zmcct10, zmrap2.7 line. Multiple flowering traits were measured for the edited genotypes and unedited Tzi8 inbred in short-day (Hawai i) and long-day (Iowa) field conditions. Both edited genotypes flowered significantly earlier than Tzi8 in both environments. Notably, under long-day conditions, flowering of the two edited lines overlapped with that of the temperate inbred B73, whereas Tzi8 did not. Together, these results demonstrate that targeted, multiplex gene editing can reduce photoperiod sensitivity in a tropical inbred, expanding access to previously untapped genetic diversity for temperate maize improvement.

plant biology↗

bioRxiv2025

P-Rex1 Limits the Agonist-Induced Internalisation of GPCRs Independently of its Rac-GEF Activity

The Rac-GEF P-Rex1 mediates GPCR signalling by activating the small GTPase Rac. We show here that P-Rex1 also controls GPCR trafficking. P-Rex1 inhibits the agonist-stimulated internalisation of the GPCR S1PR1 independently of its Rac-GEF activity, through its PDZ, DEP and IP4P domains. P-Rex1 also limits the agonist-induced trafficking of CXCR4, PAR4, and GLP1R, but does not control steady-state GPCR levels, nor the agonist-induced internalisation of the RTKs PDGFR and EGFR. P-Rex1 blocks the phosphorylation required for GPCR internalisation. P-Rex1 binds Grk2, both in vitro and in cells, but does not appear to regulate Grk2 activity. We propose that P-Rex1 limits the agonist-induced internalisation of GPCRs through its interaction with Grk2 to maintain high levels of active GPCR at the plasma membrane. Therefore, P-Rex1 plays a dual role in promoting GPCR responses, by controlling GPCR trafficking through an adaptor function as well as by mediating GPCR signalling through its Rac-GEF activity. HighlightsO_LIP-Rex1 controls GPCR trafficking, independently of its Rac-GEF activity C_LIO_LIP-Rex1 limits the agonist-induced internalisation of S1PR1, CXCR4, PAR4 and GLP1R C_LIO_LIP-Rex1 does not control steady-state GPCR levels, or PDGFR and EGFR trafficking C_LIO_LIP-Rex1 binds Grk2 and inhibits the phosphorylation required for GPCR internalisation C_LI eTOC blurbP-Rex1 activates Rac downstream of GPCRs to regulate processes ranging from innate immunity to neuronal plasticity, its deregulation contributing to cancer. Here, Baker et al. show that P-Rex1 also controls GPCR trafficking, limiting agonist-induced GPCR internalisation through an adaptor function. Thus, P-Rex1 promotes GPCR responses in a dual manner. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=200 SRC="FIGDIR/small/648762v1_ufig1.gif" ALT="Figure 1"> View larger version (54K): org.highwire.dtl.DTLVardef@20e1e2org.highwire.dtl.DTLVardef@cdd416org.highwire.dtl.DTLVardef@11f2a35org.highwire.dtl.DTLVardef@10c2b49_HPS_FORMAT_FIGEXP M_FIG C_FIG

cell biology↗

bioRxiv2024

Genome-guided, field-deployable loop-mediated isothermal amplification (LAMP) assay for specific detection of Dickeya dadantii

Potatoes, among the most economically significant crops worldwide, are susceptible to various plant pathogens that significantly impact their propagation, production, storage, and distribution. Soft rot disease, caused primarily by Dickeya and Pectobacterium, results in substantial economic losses to the agricultural industry annually. In this study, we developed a rapid, reliable, and field-deployable loop-mediated isothermal amplification (LAMP) assay for detecting D. dadantii, a common soft rot causing bacteria. The D. dadantii-specific LAMP primers were designed targeting a highly conserved genomic region within D. dadantii, the TetR/AcrR family transcriptional regulator CDS and its flanking sequences. This assay was thoroughly validated with the members of inclusivity (nine strains of D. dadantii) and exclusivity panels (85 strains, including all Dickeya species, related taxa, and host DNA), detecting no false positives or negatives. The limit of detection (LOD) was established by performing assays with 10-fold serially diluted pure gDNA of D. dadantii and gDNA spiked with host crude extract; the assay detected the target pathogen down to 1 pg (188 copies) without being adversely affected by the host crude extract. The developed LAMP assay specifically detected the target pathogen in infected plant materials. Additional multi-operator blind and multi-instrument tests were conducted to assess the assays robustness and applicability, consistently yielding accurate results without false positives or negatives. These findings demonstrate the assays potential utility for biosecurity, routine diagnostics, and epidemiological studies.

microbiology↗

bioRxiv2019

Sex differences in cortisol and memory following acute social stress in amnestic mild cognitive impairment

ObjectiveOlder adults with amnestic mild cognitive impairment (aMCI) develop Alzheimers type dementia approximately ten times faster annually than the normal population. Adrenal hormones are associated with aging and cognition. We investigated the relationship between acute stress, cortisol, and memory function in aMCI with an exploratory analysis of sex. MethodSalivary cortisol was sampled diurnally and during two test sessions, one session with the Trier Social Stress Test (TSST), to explore differences in the relationship between cortisol and memory function in age-normal cognition (NA) and aMCI. Participants with aMCI (n=6 women, 9 men; mean age=75) or similarly aged NA (n=9 women, 7 men, mean age=75) were given tests of episodic, associative, and spatial working memory with a psychosocial stressor (TSST) in the second session. ResultsThe aMCI group performed worse on the memory tests than NA as expected, and males with aMCI had elevated cortisol levels on test days. Immediate episodic memory was enhanced by social stress in NA but not in the aMCI group, indicating that stress-induced alterations in memory are different in individuals with aMCI. High cortisol was associated with impaired performance on episodic memory in aMCI males only. Cortisol in Session 1 moderated the relationship with spatial working memory, whereby higher cortisol was associated with worse performance in NA, but better spatial working memory in aMCI. In addition, effects of aMCI on perceived anxiety in response to stress exposure were moderated by stress-induced cortisol in a sex-specific manner. ConclusionsWe show effects of aMCI on Test Session cortisol levels and effects on perceived anxiety, and stress-induced impairments in memory in males with aMCI in our exploratory sample. Future studies should explore sex as a biological variable as our findings suggests that effects at the confluence of aMCI and stress can be obfuscated without sex as a consideration.

neuroscience↗