Biology subjects

Bachofen, C.

Publications and source records attributed to Bachofen, C..

5 recordsLinked to original sources

bioRxiv2026

Silent travelers: the potential of migratory birds and their ticks to introduce emerging viruses into Switzerland

Switzerland hosts over 400 bird species, many of which are migratory. Through diverse movement patterns, ranging from short distances to almost global migrations, these birds can introduce zoonotic viruses, such as West Nile virus (WNV) or avian influenza virus (AIV), as well as unknown and potentially emerging viruses. Furthermore, they facilitate the global dispersal of infected ectoparasites, particularly ticks, risking the introduction of novel tick-borne diseases. To assess this risk, we sampled 42 bird species (39 migratory, 3 resident) over seven months in 2023 at the Bolle di Magadino nature reserve and the Piano di Magadino area in the canton Ticino (Switzerland). This region, because of its transitional climate, serves as an important resting and breeding ground for migratory birds. In total, 496 oropharyngeal-cloacal swabs, 164 sera, and 22 associated ticks were collected. While RT-qPCR of the swabs detected no active WNV or AIV infections, ELISA testing identified Orthoflavivirus antibodies in 15 of 164 sera, indicating prior exposure. Metagenomic next-generation sequencing revealed a viral landscape spanning 33 families (29 of which were identified in birds). Within this virome, DNA viruses, predominantly Circoviridae, Genomoviridae, and Parvoviridae, dominated in abundance but exhibited low diversity. In contrast, the highly diverse RNA virome primarily reflected the birds dietary habits and the local habitat at the nature reserve. Notably, we report the first detection of Bole tick virus 4 (BoTV4) in Switzerland, identified in several ticks (Rhipicephalus turanicus) associated with long-distance migrants. This member of the newly established Pestiviridae family is already established in parts of Asia, Africa, and Europe. This study provides the first active surveillance of the wild bird virome in Switzerland. Our findings establish a framework for the early detection of emerging viruses and underscore the role of migratory birds as dispersal vectors for ticks and novel tick-borne viruses.

genomics↗

bioRxiv2025

Decoupling of stomatal conductance from net assimilation at high temperature as a mechanism to increase transpiration

O_LIPhotosynthetic assimilation (Anet) and stomatal conductance (gs) are usually strongly coupled, but this relationship is decreased or even lost at high temperatures (Tair). The contributions of environmental drivers (Tair, vapour pressure deficit (VPD), and soil moisture) in interaction with the physiological mechanisms behind this process are still unclear. C_LIO_LIWe exposed saplings of three temperate and tropical species to rising Tair (20 to 40{degrees}C) at low (1.2 to 1.9 kPa) and increasing VPD (1.1 to 5.6 kPa), and at stable Tair (35{degrees}C) to increasing VPD (1.4 to 4.3 kPa) under well-watered or chronic soil drought conditions ([≤]10 %). Anet, gs, and transpiration (E) in the light and the dark and leaf thermoregulation were tracked throughout the experiment. C_LIO_LIWhen VPD remained low, gs continued to increase while Anet decreased at Tair > 35{degrees}C, leading to stomatal decoupling. In contrast, under rising VPD, trees maintained the coupling between Anet and gs at high Tair. C_LIO_LIWhile a decoupling of Anet and gs only occurred when VPD was low, Anet and E decoupled under both VPD regimes at high Tair. C_LIO_LIOur results indicate that, since gs and VPD collectively drive E, stomatal decoupling is needed to increase E when VPD is not sufficiently high. C_LI

plant biology↗

bioRxiv2025

Root vulnerability to embolism and lack of physiological recovery limit the competitive ability of an invasive palm

O_LIClimate change and invasive species both threaten forest ecosystems. While exacerbated droughts drive tree mortality, species invasion alters forest composition. Invasive plants may be more vulnerable to drought due to acquisitive traits and low embolism resistance, but their potentially superior recovery capacity raises key uncertainties in predicting future species distributions. C_LIO_LIWe compared the drought resistance and recovery of an invasive palm (Trachycarpus fortunei) with two native species (Ilex aquifolium & Tilia cordata) from the Southern Alps. Saplings were exposed to increasing intensities of drought-induced xylem embolism, then rewatered for 45 days. Among others, we tracked net assimilation (Anet), stomatal conductance (gs), and leaf water potential ({Psi}leaf) before and after the drought, and modeled the time to hydraulic failure in leaves, stems, and roots. C_LIO_LIWhile the invasive palm had exceptionally drought-tolerant leaves, its roots were the most drought-sensitive among all species. The palm maintained positive gas exchange until {Psi}leaf of -4 MPa, as some native species; however, it failed to recover from the most severe drought, with simulations showing root embolism preceding leaf failure, unlike native species. C_LIO_LIInvasive plants may match or exceed natives drought resistance, but their inability to recover from extreme droughts could limit their future spread. C_LI

ecology↗

bioRxiv2025

Thermal acclimation fails to confer a carbon budget advantage to invasive species over natives

Both native and invasive plants can adjust photosynthesis and respiration when exposed to warmer temperatures. However, it is uncertain if invasive plants are more plastic and exhibit higher acclimation to rising temperatures than native ones, a trait that could contribute to their invasive behavior in novel environments. We compared the capacity of a highly invasive palm in central Europe (Trachycarpus fortunei) and two native co-occurring species (Ilex aquifolium and Tilia cordata) to acclimate photosynthesis and respiration to air temperature changes using a two-year-long transplant experiment across Europe (mean temperatures ranging from 8.4 to 21.8{degrees}C). We measured the optimal temperature of photosynthesis (Topt), the assimilation at optimal temperature (Aopt), the thermal breath of photosynthesis (T80), the respiration at 25{degrees}C (R25), the temperature sensitivity of respiration (Q10), and simulated the whole-plant carbon budget. For all species, Topt, Aopt, and T80 increased with warming, while R25 decreased in the native species and Q10 decreased in the invasive species only. Consequently, acclimation enhanced the carbon budget of the invasive and native plants in the warm and hot sites. The invasive palm had a similar or lower acclimation capacity than other species and a lower but constant carbon budget across the European temperature gradient. Our work reveals that not all invasive plants exhibit greater photosynthetic plasticity than native ones, suggesting that temperature-driven enhancement of their carbon budget may play a limited role in future invasion processes.

plant biology↗

bioRxiv2020

Bovine viral diarrhoea virus loses quasispecies diversity rapidly in culture

Bovine viral diarrhoea (BVD) is an important disease of cattle with significant impacts on animal health and welfare. The wide host range of the causative pestiviruses may lead to formation of virus reservoirs in other ruminant or wildlife species, presenting a concern for the long-term success of BVD eradication campaigns. It is likely that the quasispecies nature of these RNA viruses contributes to their interspecies transmission by providing genetic plasticity. Understanding the spectrum of sequence variants present in BVD persistently infected (PI) animals is therefore essential for studies of virus transmission. To analyse quasispecies diversity without amplification bias, we extracted viral RNA from serum of a PI cow, and from cell culture fluid after three passages of the same virus in culture, to produce cDNA without amplification. Sequencing of this material using Illumina 250bp paired-read technology produced full-length virus consensus sequences from both sources and demonstrated the quasispecies diversity of this Pestivirus A type 1a field strain within serum and after culture. We report the distribution and diversity of over 800 single nucleotide polymorphisms and provide evidence for a loss of diversity after only three passages in cell culture, implying that cultured viruses cannot be used to understand quasispecies diversity and may not provide reliable molecular markers for source tracing or transmission studies. Additionally, both serum and cultured viruses could be sequenced as a set of 25 overlapping PCR amplicons that demonstrated the same consensus sequences and the presence of many of the same quasispecies variants. The observation that aspects of the quasispecies structure revealed by massively parallel sequencing are also detected after PCR and Sanger sequencing suggests that this approach may be useful for small or difficult to analyse samples. Impact statementBovine viral diarrhoea viruses are globally important cattle pathogens, which impact performance due to acute infection and BVD-induced immunosuppression. Eradication of BVD in cattle is widely pursued but is hampered by the production of persistently infected (PI) calves - the offspring of cows infected in early pregnancy - which shed virus constantly and drive BVD spread. Genetic variation in BVD viruses is an important feature of their biology, allowing them to adapt to changing conditions and to infect different hosts. Inaccurate virus replication produces a population of viruses with slightly different sequences, a quasispecies, some of which may grow better in other hosts or in culture. Analysing virus sequence variation may help us understand how the virus evolves within and between its hosts. In this paper we show that a BVD virus strain loses quasispecies diversity quickly when cultured and that these changes can be detected even in small diagnostic samples, implying that cultured viruses do not perfectly represent the field strains they were isolated from and therefore may not provide reliable molecular markers for source tracing or transmission studies. Data SummaryPestivirus A genome sequences used in this article are as follows: O_TBL View this table: org.highwire.dtl.DTLVardef@bb1442org.highwire.dtl.DTLVardef@2f35f3org.highwire.dtl.DTLVardef@17f201corg.highwire.dtl.DTLVardef@11532eforg.highwire.dtl.DTLVardef@c31fd5_HPS_FORMAT_FIGEXP M_TBL C_TBL Sequence data associated with this manuscript has been submitted to the European Nucleotide Archive (www.ebi.ac.uk/ena/) with accession numbers as follows: Consensus genome sequences: MRI103 serum NGS: LR699799 MRI103 culture NGS: LR699800 MRI103 serum Sanger: LR699801 MRI103 culture P3 Sanger: LR699802 MRI103 culture P5 Sanger: LR699803 NGS raw data Serum dataset: ERR3624580 Culture dataset: ERR3624581

evolutionary biology↗