Fakultät Naturwissenschaften

Permanent URI for this communityhttps://hohpublica.uni-hohenheim.de/handle/123456789/1

Biologie, Ernährungs-wissenschaften und Lebensmittelwissenschaften sind die Schwerpunkte der Fakultät. Die Forschung befasst sich mit Schlüsselthemen der Life Sciences.

Homepage: https://natur.uni-hohenheim.de/

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3D chromatin maps of a brown alga reveal U/V sex chromosome spatial organization
(2024) Liu, Pengfei; Vigneau, Jeromine; Craig, Rory J.; Barrera-Redondo, Josué; Avdievich, Elena; Martinho, Claudia; Borg, Michael; Haas, Fabian B.; Liu, Chang; Coelho, Susana M.; Liu, Pengfei; Department of Algal Development and Evolution, Max Planck Institute for Biology Tübingen, Tübingen, Germany; Vigneau, Jeromine; Department of Algal Development and Evolution, Max Planck Institute for Biology Tübingen, Tübingen, Germany; Craig, Rory J.; Department of Algal Development and Evolution, Max Planck Institute for Biology Tübingen, Tübingen, Germany; Barrera-Redondo, Josué; Department of Algal Development and Evolution, Max Planck Institute for Biology Tübingen, Tübingen, Germany; Avdievich, Elena; Department of Algal Development and Evolution, Max Planck Institute for Biology Tübingen, Tübingen, Germany; Martinho, Claudia; Department of Algal Development and Evolution, Max Planck Institute for Biology Tübingen, Tübingen, Germany; Borg, Michael; Department of Algal Development and Evolution, Max Planck Institute for Biology Tübingen, Tübingen, Germany; Haas, Fabian B.; Department of Algal Development and Evolution, Max Planck Institute for Biology Tübingen, Tübingen, Germany; Liu, Chang; Institute of Biology, University of Hohenheim, Stuttgart, Germany; Coelho, Susana M.; Department of Algal Development and Evolution, Max Planck Institute for Biology Tübingen, Tübingen, Germany
Nuclear three dimensional (3D) folding of chromatin structure has been linked to gene expression regulation and correct developmental programs, but little is known about the 3D architecture of sex chromosomes within the nucleus, and how that impacts their role in sex determination. Here, we determine the sex-specific 3D organization of the model brown alga Ectocarpus chromosomes at 2 kb resolution, by mapping long-range chromosomal interactions using Hi-C coupled with Oxford Nanopore long reads. We report that Ectocarpus interphase chromatin exhibits a non-Rabl conformation, with strong contacts among telomeres and among centromeres, which feature centromere-specific LTR retrotransposons. The Ectocarpus chromosomes do not contain large local interactive domains that resemble TADs described in animals, but their 3D genome organization is largely shaped by post-translational modifications of histone proteins. We show that the sex determining region (SDR) within the U and V chromosomes are insulated and span the centromeres and we link sex-specific chromatin dynamics and gene expression levels to the 3D chromatin structure of the U and V chromosomes. Finally, we uncover the unique conformation of a large genomic region on chromosome 6 harboring an endogenous viral element, providing insights regarding the impact of a latent giant dsDNA virus on the host genome’s 3D chromosomal folding.
Competitive hierarchies in bryozoan assemblages mitigate network instability by keeping short and long feedback loops weak
(2023) Koch, Franziska; Neutel, Anje-Margriet; Barnes, David K. A.; Tielbӧrger, Katja; Zarfl, Christiane; Allhoff, Korinna T.
Competitive hierarchies in diverse ecological communities have long been thought to lead to instability and prevent coexistence. However, system stability has never been tested, and the relation between hierarchy and instability has never been explained in complex competition networks parameterised with data from direct observation. Here we test model stability of 30 multispecies bryozoan assemblages, using estimates of energy loss from observed interference competition to parameterise both the inter- and intraspecific interactions in the competition networks. We find that all competition networks are unstable. However, instability is mitigated considerably by asymmetries in the energy loss rates brought about by hierarchies of strong and weak competitors. This asymmetric organisation results in asymmetries in the interaction strengths, which reduces instability by keeping the weight of short (positive) and longer (positive and negative) feedback loops low. Our results support the idea that interference competition leads to instability and exclusion but demonstrate that this is not because of, but despite, competitive hierarchy.
The natural product 2,4,6-tribromoanisole is the predominant polyhalogenated compound in representative Australian passive air samples
(2025) Schweizer, Sina; Wang, Xianyu; Paxman, Chris; Mueller, Jochen F.; Vetter, Walter; Schweizer, Sina; Institute of Food Chemistry, Department of Food Chemistry (170B), University of Hohenheim, 70599, Stuttgart, Germany; Wang, Xianyu; University of Queensland, Queensland Alliance for Environmental Health Sciences, 4102, Brisbane, Australia; Paxman, Chris; University of Queensland, Queensland Alliance for Environmental Health Sciences, 4102, Brisbane, Australia; Mueller, Jochen F.; University of Queensland, Queensland Alliance for Environmental Health Sciences, 4102, Brisbane, Australia; Vetter, Walter; Institute of Food Chemistry, Department of Food Chemistry (170B), University of Hohenheim, 70599, Stuttgart, Germany
Passive air samplers are well-suited for monitoring persistent organic pollutants (POPs) in ambient air. While the presence of POPs had been documented in Australian air, no data existed on structurally similar, halogenated natural products (HNPs), although these were frequently found in marine biota samples from Australia at levels exceeding those of anthropogenic POPs. This study reports quantitative data of the HNP 2,4,6-tribromoanisole (2,4,6-TBA) along with three POPs (polychlorinated biphenyls (PCBs) 153 and 138 as well as hexachlorobenzene (HCB)) in six selected passive air samples from different Australian regions (islands, coastal cities, and inland). For the most abundant HNP, 2,4,6-TBA, time-averaged concentrations for one year were determined at up to 420 pg/m 3 (One Tree Island), indicating its predominant natural production in the Great Barrier Reef (GBR). High concentrations of 2,4,6-TBA (17 pg/m 3 ), even in the remote inland sample (~ 800 km from the sea), led to the conclusion that the marine-derived 2,4,6-TBA was transported over long distances in air and can be found ubiquitously in Australian air. Even in the coastal cities of Brisbane and Darwin, 2,4,6-TBA levels were comparable to those of the PCBs. The HNP 2,3,3',4,4',5,5'-heptachloro-1'-methyl-1,2'-bipyrrole (Q1) was also detected in air from two islands. Its presence in air from One Tree Island was in line with expectations, given the high levels in marine mammal samples from the GBR. In direct comparison, the ~15 times higher ratio of Q1/2,4,6-TBA in air from Phillip Island indicated Q1 could be even more abundant in this marine region than in the GBR.

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