Biology subjects

Pitz, M.

Publications and source records attributed to Pitz, M..

5 recordsLinked to original sources

bioRxiv2025

Improving allometric models to estimate the proboscis length of tropical bees

The proboscis length of bees is a key morphological trait shaping communities, pollination networks, and likely their responses to habitat loss. Despite its importance, it is rarely considered in ecological studies because of logistic limitations in obtaining accurate measurements across many different species. In two previous studies, the proboscis length of temperate bee species was estimated based on body size and bee family. However, bee taxa partially occurring in the tropics might deviate from this allometric relationship due to different functional constraints. Thus, we tested if equations developed for temperate bees can accurately predict the proboscis length in Meliponini, Euglossini (both Apidae), and Augochlorini (Halictidae), three ubiquitous and highly important tribes of tropical bees. We measured the intertegular distance (as a proxy of body size measurement) and the proboscis length of 892 specimens of 105 tropical species. We used these measurements to evaluate the previous model and found that its estimations lacked accuracy when applied to tropical bees, particularly to Meliponini and Euglossini. We developed new allometric equations estimating the proboscis length based on the intertegular distance, using (sub-) genera as an additional predictive variable to refine the estimations. We tested our approach by creating a test model for Meliponini, trained with only 80 % of the data, and evaluated this model using the remaining 20 %, resulting in a high accuracy of estimates. Our results shed additional light on the nature of the proboscis length-body size allometric relationship in tropical bees and provide a tool for future studies on the functional ecology of bees and their interactions with plants.

zoology↗

bioRxiv2025

Stratification along tropical forest succession enhances pollinator diversity via functionally unique canopies

Vertical stratification is a prominent driver of biodiversity in forests. As the proportion of successional forests increases worldwide and canopies are lost at a fast pace, it is crucial to understand the role of stratification as a driver of community recovery and ecological processes during succession, particularly for important plant mutualist groups essential for forest recovery. Within a well-resolved chronosequence in the northwestern Ecuadorian rainforest, we compiled an extensive database of over 20,000 diurnal and nocturnal pollinators and 2,000 interactions with plants and examined the interacting effects of recovery age and stratification on pollinator community and interaction network reassembly. In late successional and old-growth forests, stratification was a stronger predictor of pollinator abundance, alpha-diversity, functional richness and beta-diversity than forest legacy. While most groups were strongly associated with canopies (moths, social bees, and nocturnal bees), orchid bees exhibited an inverse pattern, also presenting the strongest functional response to stratification and recovery status. Within the entire chronosequence (0-38 years of recovery, plus old-growth forests), recovery status and stratification, alongside landscape features, acted synergistically as predictors of pollinator community parameters. Although structurally stable across the chronosequence and between strata, Interaction networks were richer and most distinct in canopies, while the highest pollinator and interaction diversity were found in old-growth canopies. In successional forests, networks were only comparable in size to active disturbances and early recovery with both strata combined, whereas complete networks in old-growth forests were more than twice as large as those in other recovery statuses. Our study underlines the importance of stratification in leveraging pollinator diversity during forest succession. By serving as havens for canopy-adapted species, tropical canopies may thus help safeguard pollination processes in disturbed landscapes.

ecology↗

bioRxiv2024

Regulation of heterosis-associated gene expression complementation in maize hybrids

The dominance model of heterosis explains the superiority of F1-hybrids via the complementation of unfavorable by beneficial alleles in many genes. Consistent with this model, genes active in only one parent and the hybrid display single-parent expression (SPE) complementation. Here we demonstrated, that SPE can explain up to 29% of heterotic variance in maize (Zea mays L.). Moreover, expression quantitative trait loci (eQTL) revealed, that the genotype of the active parent determines the regulation mode of SPE patterns in cis or trans, which might explain how phylogenetic distance translates to transcriptomic diversity and heterosis in hybrids. Furthermore, we showed that most eQTL are located in heterozygous regions of the genome and that a trans eQTL controls the activity of a SPE gene which regulates lateral root density in hybrids. We anticipate that our study will stimulate further research elucidating the regulation and molecular mechanisms underlying heterosis.

plant biology↗

bioRxiv2024

Expanding the BonnMu sequence-indexed repository of transposon induced maize (Zea mays L.) mutations in dent and flint germplasm

The BonnMu resource is a transposon-tagged mutant collection designed for functional genomics studies in maize. To expand this resource, we crossed an active Mutator (Mu) line with dent (B73, Co125) and flint (DK105, EP1 and F7) germplasm, resulting in the generation of 8,064 mutagenized BonnMu F2-families. Sequencing of these Mu-tagged families revealed 425,924 heritable Mu insertions affecting 36,612 (83%) of the 44,303 high-confidence gene models of maize (B73v5). On average, we observed 12 Mu insertions per gene (425,924 total insertions/ 36,612 affected genes) and 53 insertions per BonnMu F2-family (425,924 total insertions/ 8,064 families). Mu insertions and photos of seedling phenotypes from segregating BonnMu F2-families can be accessed through the Maize Genetics and Genomics Database (MaizeGDB). Downstream examination via the automated Mutant-seq Workflow Utility (MuWU) identified 94% of the germinal insertion sites in genic regions and only a small fraction of 6% inserting in non-coding intergenic sequences of the genome. Consistently, Mu insertions aligned with gene-dense chromosomal arms. In total, 42% of all BonnMu insertions were located in the 5 untranslated region (UTR) of genes, corresponding to accessible chromatin. Furthermore, for 38% of the insertions (163,843 of 425,924 total insertions) Mu1, Mu8 and MuDR were confirmed to be the causal Mu elements. Our publicly accessible European BonnMu resource has archived insertions covering two major germplasm groups, thus facilitating both forward and reverse genetics studies.

genomics↗

bioRxiv2023

Enhancing Drug Delivery with Supramolecular Amphiphilic Macrocycle Nanoparticles: Selective Targeting of CDK4/6 Inhibitor Palbociclib to Melanoma

Drug delivery systems based on amphiphilic supramolecular macrocycles have garnered increased attention over the past two decades due to their ability to successfully formulate nanoparticles. Macrocyclic (MC) materials can self-assemble at lower concentrations without the need for surfactants and polymers, but surfactants are required to form and stabilize nanoparticles at higher concentrations. Using MCs to deliver both hydrophilic and hydrophobic guest molecules is advantageous. We developed two novel types of amphiphilic macrocycle nanoparticles (MC NPs) capable of delivering either Nile Red (NR) (a hydrophobic model) or Rhodamine B (RhB) (a hydrophilic model) fluorescent dyes. We extensively characterized the materials using various techniques to determine size, morphology, stability, hemolysis, fluorescence, loading efficiency (LE), and loading capacity (LC). We then loaded the CDK4/6 inhibitor Palbociclib (Palb) into both MC NPs using a solvent diffusion method. This yielded Palb-MC NPs in the size range of 65-90 nm. They exhibited high stability over time and in fetal bovine serum with negligible toxicity against erythrocytes. Cytotoxicity was minimal when tested against RAW macrophages, human fibroblast HDFn, and adipose stromal cells (ASCs) at higher concentrations of MC NPs. Cell viability studies were conducted with different concentrations of MC NPs, Palb-MC NPs, and free Palb against RAW macrophages, human U-87 GBM, and human M14 melanoma cell lines in vitro. Flow cytometry experiments revealed that blank MC NPs and Palb-MC NPs were selectively targeted to melanoma cells, resulting in cell death compared to the other two cell lines. Future work will focus on studying the biological effect of MC NPs including their binding affinity with molecules/receptors expressed on the M14 and other melanoma cell surface by molecular docking simulations. Subsequently, we will evaluate the MCs as a component of combination therapy in a murine melanoma model. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=154 SRC="FIGDIR/small/567974v1_ufig1.gif" ALT="Figure 1"> View larger version (39K): org.highwire.dtl.DTLVardef@5cddb9org.highwire.dtl.DTLVardef@e0c4e0org.highwire.dtl.DTLVardef@9d6838org.highwire.dtl.DTLVardef@2556b2_HPS_FORMAT_FIGEXP M_FIG C_FIG

pharmacology and toxicology↗