Biology subjects

Howe, H.

Publications and source records attributed to Howe, H..

5 recordsLinked to original sources

bioRxiv2025

Thinking past owl vs owl: The barred owl invasion threatens ecological communities in the western United States

Anthropogenic land use and climate change are facilitating intracontinental species range expansions, leading to novel ecological communities and interactions. Although invasive range-expanders threaten native species, lethal management can be challenged based on the notion that range-expanders are native and therefore less likely to precipitate ecological damage. The anthropogenically-mediated range expansion of barred owls (Strix varia) from eastern to western North America exemplifies this controversy: a recent U.S. Fish and Wildlife Service plan to cull barred owls for the benefit of spotted owls (Strix occidentalis) ignited public outcry and resistance. Here, we assessed barred owls potential invasiveness and broader effects on biodiversity by using molecular methods to characterize the diet of 788 individuals in California, Oregon, and Washington. Barred owls consumed 162 vertebrate and invertebrate prey species, including 29 species with federal- or state-level conservation status. Our findings suggest that barred owls may (1) threaten smaller native predators via intraguild predation and competition for shared prey; and (2) further imperil amphibian communities already threatened by a suite of environmental stressors. We thus contend that barred owls function as an invasive species in their expanded range. The Precautionary Principle suggests that large-scale lethal management is warranted to curb barred owls impacts on not just spotted owls but broader ecological communities in the forests of the Pacific Northwest. More broadly, our study highlights the significant biodiversity loss that could result from range expansions of a generalist predator and provides a roadmap for quantifying putative impacts.

ecology↗

bioRxiv2024

Understanding pollination in urban food production: the importance of data validation and participant feedback for citizen science project design

O_LIThere is a significant knowledge gap regarding the pollination needs of urban farming, partly due to barriers for researchers in accessing these growing spaces. Involving growers in data collection offers a potential solution but presents other challenges in terms of data accuracy and participant retention. C_LIO_LIWe developed a citizen science methodology for monitoring plant-pollinator interactions in urban food systems and evaluated the accuracy of data collected by growers by comparison to data collected by a professionally trained researcher. We also collected feedback from participants at the mid- and endpoints of the project regarding their experiences of taking part. C_LIO_LIWhile there was some agreement between the datasets in terms of the crops most (raspberries and squash) and least attractive (tomatoes) to insects, relying only on the dataset collected by growers themselves (citizen scientists) would lead to an overestimation of the generality of relationships between crops and pollinating insects in urban food production. Possible reasons for discrepancies between the datasets include species misidentification and non-reporting of surveys where no insects were observed by citizen scientists. C_LIO_LICitizen scientists reported lack of time, concerns about data accuracy and too complex methods as barriers to participation. Implementation of their suggestions for improvements led to a 66% increase in participation in the following year, demonstrating the importance of maintaining a two-way dialogue between participants and project organisers. Citizen scientists also reported an increased appreciation and understanding of insect pollinations following participation, highlighting an additional benefit of involving urban growers in data collection. C_LI Social Impact StatementGrowing food in urban areas can contribute towards sustainable food production. We know little about urban crop pollination, and data collection can be challenging due to restricted access to growing spaces. We developed and tested the effectiveness of a method for urban growers themselves to collect data on insects visiting their crops. Comparing data to that collected by a professional researcher, we found similarities in terms of the most and least attractive crops to pollinators, but there were also large discrepancies in the datasets that mean there are limitations to relying on grower-collected data alone to understand urban plant-pollinator interactions.

ecology↗

bioRxiv2024

Premature aging in aneuploid yeast is caused in part by aneuploidy-induced defects in Ribosome Quality Control

Premature aging is a hallmark of Down syndrome, caused by trisomy of human chromosome 21, but the reason is unclear and difficult to study in humans. We used an aneuploid model in wild yeast to show that chromosome amplification disrupts nutrient-induced cell-cycle arrest, quiescence entry, and healthy aging, across genetic backgrounds and amplified chromosomes. We discovered that these defects are due in part to aneuploidy-induced dysfunction in Ribosome Quality Control (RQC). Compared to euploids, aneuploids entering quiescence display aberrant ribosome profiles, accumulate RQC intermediates, and harbor an increased load of protein aggregates. Although they have normal proteasome capacity, aneuploids show signs of ubiquitin dysregulation, which impacts cyclin abundance to disrupt arrest. Remarkably, inducing ribosome stalling in euploids produces similar aberrations, while up-regulating limiting RQC subunits or proteins in ubiquitin metabolism alleviates many of the aneuploid defects. Our results provide implications for other aneuploidy disorders including Down syndrome.

molecular biology↗

bioRxiv2024

The response to single-gene duplication implicates translation as a key vulnerability in aneuploid yeast

Aneuploidy produces myriad consequences in health and disease, yet models of the deleterious effects of chromosome amplification are still widely debated. To distinguish the molecular determinants of aneuploidy stress, we measured the effects of duplicating individual genes in cells with varying chromosome duplications, in wild-type cells and cells sensitized to aneuploidy by deletion of RNA-binding protein Ssd1. We identified gene duplications that are nearly neutral in wild-type euploid cells but significantly deleterious in euploids lacking SSD1 or SSD1+ aneuploid cells with different chromosome duplications. Several of the most deleterious genes are linked to translation; in contrast, duplication of other translational regulators, including eI5Fa Hyp2, benefit ssd1{Delta} aneuploids over controls. Using modeling of aneuploid growth defects, we propose that the deleterious effects of aneuploidy emerge from an interaction between the cumulative burden of many amplified genes on a chromosome and a subset of duplicated genes that become toxic in that context. Our results suggest that the mechanism behind their toxicity is linked to a key vulnerability in translation in aneuploid cells. These findings provide a perspective on the dual impact of individual genes and overall genomic burden, offering new avenues for understanding aneuploidy and its cellular consequences.

genetics↗

bioRxiv2018

Pregnancy associated plasma protein-aa (Pappaa) regulates photoreceptor synaptic development to mediate visually guided behavior

To guide behavior, sensory systems detect the onset and offset of stimuli and process these distinct inputs via parallel pathways. In the retina, this strategy is implemented by splitting neural signals for light onset and offset via synapses connecting photoreceptors to ON and OFF bipolar cells, respectively. It remains poorly understood which molecular cues establish the architecture of this synaptic configuration to split light onset and offset signals. A mutant with reduced synapses between photoreceptors and one bipolar cell type, but not the other, could reveal a critical cue. From this approach, we report a novel synaptic role pregnancy associated plasma protein aa (pappaa) in promoting the structure and function of cone synapses that transmit light offset information. Electrophysiological and behavioral analyses indicated pappaa mutant zebrafish have dysfunctional cone to OFF bipolar cell synapses and impaired responses to light offset, but intact cone to ON bipolar cell synapses and light onset responses. Ultrastructural analyses of pappaa mutant cones showed a lack of presynaptic domains at synapses with OFF bipolar cells. pappaa is expressed postsynaptically to the cones during retinal synaptogenesis and encodes a secreted metalloprotease known to stimulate insulin-like growth factor 1 (IGF1) signaling. Induction of dominant negative IGF1 receptor expression during synaptogenesis reduced light offset responses. Conversely, stimulating IGF1 signaling at this time improved pappaa mutants light offset responses and cone presynaptic structures. Together, our results indicate Pappaa-regulated IGF1 signaling as a novel pathway that establishes how cone synapses convey light offset signals to guide behavior.\n\nSignificance StatementDistinct sensory inputs, like stimulus onset and offset, are often split at distinct synapses into parallel circuits for processing. In the retina, photoreceptors and ON and OFF bipolar cells form discrete synapses to split neural signals coding light onset and offset, respectively. The molecular cues that establish this synaptic configuration to specifically convey light onset or offset remain unclear. Our work reveals a novel cue: pregnancy associated plasma protein aa (pappaa), which regulates photoreceptor synaptic structure and function to specifically transmit light offset information. Pappaa is a metalloprotease that stimulates local insulin-like growth factor 1 (IGF1) signaling. IGF1 promotes various aspects of synaptic development and function and is broadly expressed; thus requiring local regulators, like Pappaa, to govern its specificity.

neuroscience↗