Biology subjects

Tuma, T. T.

Publications and source records attributed to Tuma, T. T..

4 recordsLinked to original sources

bioRxiv2024

Seeing isn't believing? Mixed effects of a perspective-getting intervention to improve mentoring relationships for science doctoral students

Science doctoral students can experience negative interactions with faculty mentors and internalize these experiences, potentially leading to self-blame and undermining their research self-efficacy. Helping students perceive these interactions adaptively may protect their research self-efficacy and maintain functional mentoring relationships. We conducted a pre-registered, longitudinal field experiment of a novel perspective-getting intervention combined with attribution retraining to help students avoid self-blame and preserve research self-efficacy. Science doctoral students (n = 155) were randomly assigned to read about mentor perspectives on negative interactions (i.e., Perspective-getting Condition) or about mentoring with no mentor perspective (i.e., control condition). Contrary to our hypotheses, we found no main effects of the intervention on students self-blame or research self-efficacy. However, for students with lower pre-intervention mentorship relationship satisfaction, the intervention preserved research self-efficacy six months later. This study provides evidence that perspective getting may be protective for students who are most in need of relationship intervention. Educational Relevance and Implications StatementEffective mentoring relationships are fundamental for promoting the success of doctoral students in science, yet not all mentoring relationships are high quality. This study assessed the effectiveness of a brief perspective-getting intervention (where students are given the perspective of what it is like to be a research mentor) that aimed to protect science doctoral students from blaming themselves for negative interactions with faculty mentors and maintain their research self-efficacy. Results showed that on average across all students, the intervention did not affect students self-blame for negative interactions or their research self-efficacy. However, the intervention did help students with less satisfying mentoring relationships maintain their self-efficacy. Thus, perspective-getting shows some promise for protecting science doctoral students from harm that can be caused by negative interactions with faculty mentors.

scientific communication and education↗

bioRxiv2024

CRISPR knockout of winter-biased SUT4 alters phenology, biomass accrual, and fertility of field-grown hybrid poplar

Climate uncertainty is intensifying the need for greater plasticity in carbohydrate reserve utilization to support winter survival and spring growth in woody perennials. In poplar, the single-copy SUT4, which encodes a tonoplast-localized sucrose transporter, and the SUT5/SUT6 genome duplicates, which encode plasma membrane-localized transporters, are expressed year-round, with SUT4 showing highest expression during cool seasons. Given its role in vacuolar sucrose efflux and winter-predominant expression, SUT4 may play a key role in modulating seasonal carbohydrate dynamics. While SUT4-knockdown and knockout effects have been studied under greenhouse conditions, their impact under field conditions remains unexplored. Here, we report a field-based study comparing CRISPR knockout mutants of winter-expressed SUT4 and SUT5/SUT6 in Populus tremula x alba. We show that sut4, but not sut56, mutants exhibited earlier autumn leaf senescence, delayed spring bud flush, reduced stem growth, and altered sugar partitioning in winter xylem and bark relative to controls. After two years in the field, all genotypes flowered before leaf flush in early spring; however, sut4 mutants produced sterile ovules despite developing normal-looking catkins. Metabolic profiling revealed disrupted sucrose and raffinose dynamics in elongating sut4 catkins, accompanied by transcriptomic signatures of elevated stress and downregulation of proanthocyanidin biosynthesis and circadian clock genes. These findings highlight the critical role of SUT4 in coordinating sugar allocation, stress responses, and seasonal development in poplar. Significance statementThis field study demonstrates that loss of SUT4, the most highly expressed sucrose transporter during cool seasons, disrupts phenology, growth, and fertility in poplar. Altered sugar and raffinose dynamics and transcriptomic signatures of stress and circadian clock gene dysregulation in the mutants underscore SUT4s role in coordinating sugar allocation and seasonal developmental transitions under natural environmental conditions.

plant biology↗

bioRxiv2023

Sucrose or starch? The influence of tonoplast sucrose transporter perturbation on carbon partitioning for growth, defense, and winter protection in coppiced poplar

Non-structural carbohydrate reserves of stems and roots underpin overall tree fitness. These reserves also contribute to productivity under short-rotation management practices such as coppicing for bioenergy. While sucrose and starch comprise the predominant carbohydrate reserves of Populus, utilization is understood primarily in terms of starch turnover. The tonoplast sucrose transport protein SUT4 modulates sucrose export from source leaves to distant sinks during photoautotrophic growth, but the possibility of its involvement in remobilizing carbohydrates from sinks during heterotrophic growth has not been explored. Here, we used PtaSUT4-knockout mutants of Populus tremula x P. alba (INRA 717-1B4) in winter (cool) and summer (warm) glasshouse coppicing experiments to strain carbon demand and test for SUT4 involvement in reserve utilization. We show that epicormic bud emergence, subsequent growth, and xylem hexose increases were delayed or reduced in sut4 mutants following lower temperature winter coppicing. Depletion of stem reserves during post-coppice regrowth was not impaired in sut4, but sut4 winter maintenance costs may have been higher in metabolic terms. Bark accrual of abundant defense metabolites, including salicinoids, chlorogenic acids, and flavonoid products, was prioritized in the summer, but attenuated in sut4 mutants. Summer sprout growth was not reduced in sut4 compared to controls. Together, our results point to shifting priorities for SUT4 modulation of seasonal trade-offs between growth and other priorities in the stem and emerging buds during reserve utilization in Populus.

plant biology↗

bioRxiv2023

Development and Validation of the Mentoring in Undergraduate Research Survey

Here we present the development and initial validation of the Mentoring in Undergraduate Research Survey (MURS) as a measure of a range of mentoring experienced by undergraduate science researchers. We drafted items based on qualitative research and refined the items through cognitive interviews and expert sorting. We used national dataset to evaluate the internal structure of the measure and a second national dataset to examine how responses on the MURS related to theoretically-relevant constructs and student characteristics. Our factor analytic results indicate seven lower order forms of mentoring experiences: abusive supervision, accessibility, career and technical support, psychosocial support, interpersonal mismatch, sexual harassment, and unfair treatment. These forms of mentoring mapped onto two higher-order factors: supportive and destructive mentoring experiences. Although most undergraduates reported experiencing supportive mentoring, some reported experiencing absence of supportive as well as destructive experiences. Undergraduates who experienced less supportive and more destructive mentoring also experienced lower scientific integration and a dampening of their beliefs about the value of research. The MURS should be useful for investigating the effects of mentoring experienced by undergraduate researchers and for testing interventions aimed at fostering supportive experiences and reducing or preventing destructive experiences and their impacts. Highlight summaryThis study presents the development and initial validation of the Mentoring in Undergraduate Research Survey, including evidence of its internal structure as well as convergent, discriminant, and predictive validity.

scientific communication and education↗