Publikationsfonds der Universität Hohenheim

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Über den Publikationsfonds der Universität Hohenheim erhalten Wissenschaftlerinnen und Wissenschaftler der Universität finanzielle Unterstützung bei der Veröffentlichung ihrer Forschungsergebnisse im Open Access. Gefördert werden Zeitschriftenartikel in Fully-Open-Access-Zeitschriften (Gold-OA) und hybriden Subskriptionszeitschriften (Hybrid-OA) sowie Monografien. Autorinnen und Autoren können online einen Förderantrag zur Finanzierungsbeteiligung ihrer Publikation stellen.

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Relationship between nutritional composition and fibre digestibility in tropical forages compared to temperate forages
(2024) Nurdianti, Risma Rizkia; Dickhöfer, Uta; Castro-Montoya, Joaquín Miguel
The study aimed to analyse variability in nutrient concentration and fibre digestibility in forage legumes and grasses from tropical and temperate regions and identify forage species with similar fibre concentration and digestibility. Forty-five samples comprised 22 tropical forage legumes, four temperate forage legumes, eleven tropical grasses, and eight temperate grasses were analysed for their proximate nutritional composition, as well as fibre digestibility by 240-h of in vitro incubation in buffered rumen fluid. All data were analysed using SAS (SAS Institute Inc., USA). Pearson correlations and multiple linear regressions were determined using CORR and GLM procedures, respectively. Cluster analyses were done using CLUSTER procedures. Tropical forage legumes had greater ash-corrected neutral detergent fibre (aNDFom) concentrations compared to temperate forage legumes, but lower aNDFom concentrations compared to tropical and temperate grasses. Tropical forage legumes had greater undigested neutral detergent fibre estimated after 240 h in vitro incubation (uNDF240) concentrations compared to other forages. In tropical forage legumes, aNDFom and lignin concentrations correlated with uNDF240 concentration (p < 0.001). Meanwhile, there were no relationships between explanatory variables and fibre digestibility (p > 0.100). Four clusters of forage species varying in fibre concentration and fibre digestibility were identified. Peanut, lima bean, and cowpea forages might have low fibre concentration and medium fibre digestibility similar to those of alfalfa and red clover. Despite differences in environmental conditions, tropical forage legumes might compete with temperate species in terms of nutrient and fibre quality. This information allows tropical farmers to improve forage quality by choosing appropriate species.
Development and testing of a precision hoeing system for re-compacted ridge tillage in maize
(2024) Alagbo, Oyebanji O.; Saile, Marcus; Spaeth, Michael; Schumacher, Matthias; Gerhards, Roland
Ridge tillage (RT) is a conservation practice that provides several benefits such as enhanced root growth and reduced soil erosion. The objectives of this study were to develop an autosteered living mulch seeder and hoeing prototype for RT systems using RTK-GNSS (real-time kinematic global navigation satellite systems) created ridges as a guide. It was also aimed to compare weed control efficacy and crop response of ridge-hoeing compared to conventional hoeing in flat tillage (FT). It was further aimed to investigate the impact of a new RT technology (with ridge re-compaction) on maize root development, yield, soil temperature, and moisture compared to FT. Field experiments were conducted with maize in 2021 and 2022 in a two-factorial split-plot design with tillage (RT and FT) as main treatment and weed control (untreated, herbicide, twice hoeing, hoeing + living mulch) as sub-treatment factors. Weed density, coverage, biomass, crop density, weed control efficacy (WCE) and maize silage yield were assessed. Temperature loggers were installed within RT and FT to take temperature readings at 20 min. Soil moisture and root penetrability were measured every two weeks in each plot using soil samples and a penetrometer. The WCE and yield did not differ significantly between the tillage systems. Twice hoeing resulted in 71–80 % WCE, which was equal to herbicide treatment. Hoeing + living mulch achieved 70–72 % WCE. Different from previous studies with ridge tillage, temperatures in the compacted ridges did not consistently differ from the ridge valleys and flat seedbeds. Root penetration (against 1.4 MPa penetrometer cone index) was 40 % higher in RT than in FT. On average, RT maize produced more (53.6 g m−2) root biomass compared to FT. In summary, re-compacted ridges built along RTK-GNSS lines can allow post-emergent hoeing and living mulch seeding along ridges and also provide good growing conditions for maize.
Prostaglandin E2 signaling through prostaglandin E receptor subtype 2 and Nurr1 induces fibroblast growth factor 23 production
(2024) Feger, Martina; Hammerschmidt, Katharina; Liesche, lona; Rausch, Steffen; Alber, Jana; Föller, Michael
Bone cells produce fibroblast growth factor 23 (FGF23), a hormone regulating renal phosphate and vitamin D homeostasis, and a paracrine factor produced in further tissues. Chronic kidney disease and cardiovascular disorders are associated with early elevations of plasma FGF23 levels associated with clinical outcomes. FGF23 production is dependent on many conditions including inflammation. Prostaglandin E2 (PGE2) is a major eicosanoid with a broad role in pain, inflammation, and fever. Moreover, it regulates renal blood flow, renin secretion, natriuresis as well as bone formation through prostaglandin E receptor 2 (EP2). Here, we studied the role of PGE2 and its signaling for the production of FGF23. Osteoblast-like UMR-106 cells were exposed to EP receptor agonists, antagonists or RNAi. Wild type and EP2 knockout mice were treated with stable EP2 agonist misoprostol. Fgf23 or Nurr1 gene expression was determined by quantitative real-time PCR, hormone and further blood parameters by enzyme-linked immunosorbent assay and colorimetric methods. PGE2 and EP2 agonists misoprostol and butaprost enhanced FGF23 production in UMR-106 cells, effects mediated by EP2 and transcription factor Nurr1. A single dose of misoprostol up-regulated bone Fgf23 expression and FGF23 serum levels in wild type mice with subtle effects on parameters of mineral metabolism only. Compared to wild type mice, the FGF23 effect of misoprostol was significantly lower in EP2-deficient mice. To conclude, PGE2 signaling through EP2 and Nurr1 induces FGF23 production. Given the broad physiological and pathophysiological implications of PGE2 signaling, this effect is likely of clinical relevance.
Review: Welfare in farm animals from an animal-centred point of view
(2024) Huber, Korinna
This review aimed to enlighten aspects of welfare from the farm animal-centred point of view rarely addressed such as those anatomical and physiological alterations induced in farm animals to obtain high performance. Hence, the major working hypothesis was that high-producing farm animals developed an imbalance between body structural and functional capacities and the genetic procedures applied to obtain industrial production of animal protein. This is called “disproportionality”, a feature which cannot be compensated by feeding and management approaches. Consequences of disproportionality are the insidious development of disturbances of the metabolism, low-grade systemic inflammation and as a final stage, production diseases, developing throughout the productive life span of a farm animal and affecting animal welfare. Based on scientific evidence from literature, the review discusses disproportional conditions in broilers, laying hens, sows, piglets, dairy cows, bulls and calves as the most important farm animals for production of milk, meat, foetuses and eggs. As a conclusion, farm animal welfare must consider analysing issues from an animal-centered point of view because it seems evident that, due to genetics and management pressures, most of farm animals are already beyond their physiological limitations. Animal welfare from an animal-centered point must be addressed as an ethical step to establish limits to the strength placed on the animal’s anatomical and physiological functionality. It may allow more sustainable and efficient farm animal production and the availability of healthy animal-derived protein for human nutrition worldwide.
Metabolome fingerprinting reveals the presence of multiple nitrification inhibitors in biomass and root exudates of Thinopyrum intermedium
(2024) Issifu, Sulemana; Acharya, Prashamsha; Schöne, Jochen; Kaur-Bhambra, Jasmeet; Gubry-Rangin, Cecile; Rasche, Frank
Biological Nitrification Inhibition (BNI) encompasses primarily NH4 +-induced release of secondary metabolites to impede the rhizospheric nitrifying microbes from per- forming nitrification. The intermediate wheatgrass Thinopyrum intermedium (Kernza®) is known for exuding several nitrification inhibition traits, but its BNI potential has not yet been identified. We hypothesized Kernza® to evince BNI potential through the presence and release of multiple BNI metabolites. The presence of BNI metabolites in the biomass of Kernza® and annual winter wheat (Triticum aestivum) and in the root exudates of hydroponically grown Kernza®, were fingerprinted using HPLC-DAD and GC–MS/MS analyses. Growth bioassays involving ammonia-oxidizing bacteria (AOB) and archaea (AOA) strains were conducted to assess the influence of the crude root metabolome of Kernza® and selected metabolites on nitrification. In most instances, significant concentrations of various metabolites with BNI potential were observed in the leaf and root biomass of Kernza® compared to annual winter wheat. Furthermore, NH4 + nutrition triggered the exudation of various phenolic BNI metabolites. Crude root exudates of Kernza® inhibited multiple AOB strains and completely inhibited N. viennensis. Vanillic acid, caffeic acid, vanillin, and phenylalanine suppressed the growth of all AOB and AOA strains tested, and reduced soil nitrification, while syringic acid and 2,6-dihydroxybenzoic acid were ineffective. We demonstrated the considerable role of the Kernza® metabolome in suppressing nitrification through active exudation of multiple nitrification inhibitors.
A novel dataset of annotated oyster mushroom images with environmental context for machine learning applications
(2024) Duman, Sonay; Elewi, Abdullah; Hajhamed, Abdulsalam; Khankan, Rasheed; Souag, Amina; Ahmed, Asma
State-of-the-art technologies such as computer vision and machine learning, are revolutionizing the smart mushroom industry by addressing diverse challenges in yield prediction, growth analysis, mushroom classification, disease and deformation detection, and digital twinning. However, mushrooms have long presented a challenge to automated systems due to their varied sizes, shapes, and surface characteristics, limiting the effectiveness of technologies aimed at mushroom classification and growth analysis. Clean and well-labelled datasets are therefore a cornerstone for developing efficient machine-learning models. Bridging this gap in oyster mushroom cultivation, we present a novel dataset comprising 555 high-quality camera raw images, from which approximately 16.000 manually annotated images were extracted. These images capture mushrooms in various shapes, maturity stages, and conditions, photographed in a greenhouse using two cameras for comprehensive coverage. Alongside the images, we recorded key environmental parameters within the mushroom greenhouse, such as temperature, relative humidity, moisture, and air quality, for a holistic analysis. This dataset is unique in providing both visual and environmental time-point data, organized into four storage folders: “Raw Images”; “Mushroom Labelled Images and Annotation Files”; “Maturity Labelled Images and Annotation Files”; and “Sensor Data”, which includes time-stamped sensor readings in Excel files. This dataset can enable researchers to develop high-quality prediction and classification machine learning models for the intelligent cultivation of oyster mushrooms. Beyond mushroom cultivation, this dataset also has the potential to be utilized in the fields of computer vision, artificial intelligence, robotics, precision agriculture, and fungal studies in general.
The influence of growth rate-controlling feeding strategy on the surfactin production in Bacillus subtilis bioreactor processes
(2024) Hiller, Eric; Off, Manuel; Hermann, Alexander; Vahidinasab, Maliheh; Benatto Perino, Elvio Henrique; Lilge, Lars; Hausmann, Rudolf
Background The production of surfactin, an extracellular accumulating lipopeptide produced by various Bacillus species, is a well-known representative of microbial biosurfactant. However, only limited information is available on the correlation between the growth rate of the production strain, such as B. subtilis BMV9, and surfactin production. To understand the correlation between biomass formation over time and surfactin production, the availability of glucose as carbon source was considered as main point. In fed-batch bioreactor processes, the B. subtilis BMV9 was used, a strain well-suited for high cell density fermentation. By adjusting the exponential feeding rates, the growth rate of the surfactin-producing strain, was controlled. Results Using different growth rates in the range of 0.075 and 0.4 h-1, highest surfactin titres of 36 g/L were reached at 0.25 h-1 with production yields YP/S of 0.21 g/g and YP/X of 0.7 g/g, while growth rates lower than 0.2 h-1 resulted in insufficient and slowed biomass formation as well as surfactin production (YP/S of 0.11 g/g and YP/X of 0.47 g/g for 0.075 h-1). In contrast, feeding rates higher than 0.25 h-1 led to a stimulation of overflow metabolism, resulting in increased acetate formation of up to 3 g/L and an accumulation of glucose due to insufficient conversion, leading to production yields YP/S of 0.15 g/g and YP/X of 0.46 g/g for 0.4 h-1. Conclusions Overall, the parameter of adjusting exponential feeding rates have an important impact on the B. subtilis productivity in terms of surfactin production in fed-batch bioreactor processes. A growth rate of 0.25 h-1 allowed the highest surfactin production yield, while the total conversion of substrate to biomass remained constant at the different growth rates.
Exploring private financing for biodiversity conservation: Stakeholder perspectives and governance in the case of wildflower strips in Germany
(2024) Bücheler, Hannah; Bieling, Claudia; Feuerbacher, Arndt
This study explores the understudied role of privately financed ecosystem service provision in biodiversity conservation, focusing on the example of wildflower strips in Germany. Using qualitative methods, it investigates the diversity of private financing schemes, stakeholder involvement, scheme implementation and farmers motivations to engage in private schemes. The results draw on literature-based stakeholder analysis and expert interviews, including ecol- ogists and practitioners, in three German federal states: Baden-Württemberg, Bavaria and Lower Saxony. Findings include a stakeholder map, the identification of four types of private financing schemes, and the formulation of 17 design criteria covering ecological, economic, and social aspects. These criteria aim to guide providers and sponsors and to emphasise the diverse nature of private wildflower strip financing schemes and their role as crucial links among farmers, the private sector, and society. The study highlights private schemes as viable alternatives to public funding but raises concerns about quality control and coordination with public measures. Combining publicly funded agri-environment schemes with private financing is controversial among stakeholders. Government intervention could formalise the private market, improving control and protection, possibly limiting private sector flexibility and attractiveness due to higher levels of bureaucracy. In any case, transparency in management and financial structures is crucial. Policy recommendations overall include incentivising private sector conservation involvement, offering tax credits for private financing, improving government mechanisms, streamlining coordination of public and private conservation at the landscape level and fostering stakeholder networking. Consequently, this study lays a foundational framework for further exploration into the realm of private financing in biodiversity conservation.
Effect of packaging and storage conditions on the pasting and functional properties of pretreated yellow-fleshed cassava flour
(2024) Ekeledo, Esther; Abass, Adebayo; Müller, Joachim
Cassava is highly susceptible to post harvest physiological deterioration which makes it necessary to initiate processing so as to extend the shelf life. In order to improve and enhance the nutritional characteristics of the processed cassava flour, this research was carried out so as to evaluate the adequate packaging materials and storage conditions necessary for safe storage and good flour quality. Pasting properties of food/flour is an indication of the different applicability of starch-based food ingredients in product development. The effect of packaging materials (cylindric polyvinyl containers and aluminum ziplock pouch bags) on quality attributes of pretreated yellow-fleshed cassava flour (YFCF) samples stored in two storage conditions a (cooling chamber at 5 ◦ C and 30 % relative humidity and; in a climate chamber at 30 ◦C and 50 % relative humidity) was investigated for 8 weeks. Flour samples from each package type were evaluated for water absorption capacity, pasting and oil absorption capacity fortnightly. The treated initial flour sample before storage-sulfured (BSS) had the highest peak viscosity (891 RVU). The low peak time at the end of storage in non-sulfured flours packed in aluminum pouch bags and stored at 5 ◦C is an evidence of time and energy saving capacity. The water absorption capacity of non-sulfured flour samples packed in cylindric polyvinyl containers and the sulfured flour sample packed in an aluminum pouch bag at 30 ◦C increased with storage duration. The aluminum ziplock pouch bags showed excellent storage quality and retained better pasting property. The climatic storage condition revealed better keeping quality. The use of sodium metabisulphite revealed its suitability as a pretreatment tool.
Oral intake of the microalgae Nannochloropsis oceanica, Chlorella vulgaris, or Phaeodactylum tricornutum improves metabolic conditions in hypercaloric-fed mice
(2024) Kopp, Lena; Seethaler, Benjamin; Neumann, Ulrike; Bischoff, Stephan C.
Diet-induced metabolic load is associated with excess body weight and liver steatosis. Here, selected microalgae, known to contain bioactive nutrients, were studied for beneficial metabolic effects in a mouse model of liver steatosis. Adult mice (8 per group) were fed either a Western-style diet (WSD) or a control diet +/ 15 % of the microalgae Chlorella vulgaris (CV), Nannochloropsis oceanica (NO), or Phaeodactylum tricornutum (PT) for 12 weeks. We evaluated liver fat content and liver damage, as well as fecal microbiota and lipopolysaccharide (LPS) translocation. NO supplementation to a WSD reduced the grade of liver steatosis (from 17 % to 4.7 %, p < 0.002), the liver damage score (p < 0.001), and LPS translocation (p < 0.001). PT had similar effects on liver damage score (p < 0.001) and LPS translocation (p < 0.001). CV supplementation reduced LPS translocation (p < 0.001). In conclusion, dietary supplementation of microalgae may be a novel sustainable approach to combat metabolic loads.
Insect conservation in agricultural landscapes needs both high crop heterogeneity and semi-natural habitats
(2024) Tassoni, Sara; Becker, David; Kasten, Marit Kinga; Moriníere, Jérôme; Grass, Ingo
Identifying landscapes that are suitable for both biodiversity conservation and agricultural production is a major challenge. Traditionally, much research has focused on biodiversity conservation outside of agricultural production areas, e.g., in semi-natural habitats. In contrast, recent research has mainly focused on the potential of crop heterogeneity. This includes both compositional (crop diversity) and configurational heterogeneity (field border density). However, if and how crop heterogeneity, and semi-natural habitats interact to shape insect diversity in agricultural landscapes remains poorly understood. Here we investigated the combined effects of crop diversity, field border density, and semi-natural habitats (i.e., grassland proportion, hedge density) on insect diversity. We sampled insect communities from 14 – 17 June 2021 with pan traps in 27 study landscapes (500 m x 500 m) covering independent gradients of these landscape variables and identified a total of 587 insect species with DNA metabarcoding. We found that field border density mediated the effects of crop diversity, grassland proportion, and hedge density on insect richness. At low levels of field border density (i.e., landscapes with mostly large fields), effects were either neutral (crop diversity), negative (grassland proportion) or weakly positive (hedge density). By contrast, at high levels of field border density, crop diversity, grassland proportion, and hedge density all exerted positive effects on insect richness. Responses to crop heterogeneity and semi-natural habitat differed among trophic groups of insects (decomposers, herbivores, parasitoids, predators). While variation in richness of herbivorous insects followed the patterns of the overall richness, decomposer richness was not related to any of the investigated variables. Predator richness increased with hedge density in landscapes, whereas parasitoid richness increased when high levels of field border density and grassland proportion coincided. Our study shows that increasing crop heterogeneity is a viable strategy for promoting insect diversity in agricultural landscapes. However, the effects of the amount of remaining semi-natural habitats, such as grassland or hedges, are mediated by configurational heterogeneity, and vary between trophic groups. Efforts to conserve insects in agricultural landscapes must therefore focus on both increasing the heterogeneity of the crop matrix by promoting crop diversity and increasing the density of field borders, while also maintaining or restoring semi-natural habitats as important source habitats for insect species.
The economics of capital allocation in firms: Evidence from internal capital markets
(2024) Hoang, Daniel; Gatzer, Sebastian; Ruckes, Martin
We analyze a unique chief financial officer (CFO) survey data set to examine capital allocation in firms. Top management is aware of agency and information problems at the divisional level and organizes the budgeting process to counteract managerial oppor- tunism, employing systems of interconnected measures, including layers of approval, divi- sional budgets, reporting requirements, and compensation schemes. When making funding decisions, top management relies heavily on top-level nonfinancial information, such as the assessment of divisional managers’ abilities. However, substantial parts of the capital bud- get do not require top management approval as firms trade off the benefits and costs of decentralization, thereby deviating from the traditional paradigm of decentralized project initiation but centralized project approval. Even firms with active internal capital markets tilt capital allocation toward relatively even distributions, reflecting the use of capital alloca- tion as a credible communication device. We also find that within-firm agency problems may result in capital rationing, that is, divisions’ restricted access to internal capital. CFOs also believe that integrating multiple businesses into an internal capital market results in tangible financial benefits, predominantly lower costs of capital and higher debt capacities. Thus, our findings also support coinsurance arguments suggesting that internal capital markets may improve access to external financing.
Limitations of soil-applied non-microbial and microbial biostimulants in enhancing soil P turnover and recycled P fertilizer utilization: A study with and without plants
(2024) Herrmann, Michelle Natalie; Griffin, Lydia Grace; John, Rebecca; Mosquera-Rodríguez, Sergio F.; Nkebiwe, Peteh Mehdi; Chen, Xinping; Yang, Huaiyu; Müller, Torsten
Introduction: Phosphorus recovery from waste streams is a global concern due to open nutrient cycles. However, the reliability and efficiency of recycled P fertilizers are often low. Biostimulants (BS), as a potential enhancer of P availability in soil, could help to overcome current barriers using recycled P fertilizers. For this, a deeper understanding of the influence of BSs on soil P turnover and the interaction of BSs with plants is needed. Methods: We conducted an incubation and a pot trial with maize in which we testednon-microbial (humic acids and plant extracts) and microbial BSs (microbial consortia) in combination with two recycled fertilizers for their impact on soil P turnover, plant available P, and plant growth. Results and discussion: BSs could not stimulate P turnover processes (phosphatase activity, microbial biomass P) and had a minor impact on calcium acetate-lactate extractable P (CAL-P) in the incubation trial. Even though stimulation of microbial P turnover by the microbial consortium and humic acids in combination with the sewage sludge ash could be identified in the plant trial with maize, this was not reflected in the plant performance and soil P turnover processes. Concerning the recycled P fertilizers, the CAL-P content in soil was not a reliable predictor of plant performance with both products resulting in competitive plant growth and P uptake. While this study questions the reliability of BSs, it also highlights the necessity toimprove our understanding and distinguish the mechanisms of P mobilization in soil and the stimulation of plant P acquisition to optimize future usage.
The adoption potential of extended lactation as a strategy to reduce excess calf numbers in dairy farming
(2024) Gresham, Josephine; Reiber, Christoph; Chagunda, Mizeck G. G.
Dairy production relies predominantly on a few, selectively bred, high-yielding dairy breeds, resulting in a surplus of low-value male offspring. This situation leads to a conflict between a growing demand for milk and low appreciation for dairy calves. Extending lactation could reduce the number of calves born. This study aimed to assess the current use of extended lactation in dairy production in Southern Germany, identify the perceived potential, and determine the biological potential extended lactation has to reduce calf numbers. A survey from 2020 with 310 farmers was analysed. A total of 145 (46.8%) farmers used extended lactation. The use of extended lactation on farms correlated significantly with breed, milk yield, interest in continuing or implementing the use of extended lactation, and the indicated feasibility of extended lactation. The perceived potential was assessed by 39.8% of farmers as “high” to “very high”. A total of 17 (12.8%) farmers currently not using extended lactation were identified as potential adopters. Together with existing adopters, this could result in 52.3% of farms using extended lactation, which could biologically reduce calf numbers by 7.3% or 14.1% p.a., when extended by three or six months, respectively. This adoption potential shows that extended lactation can reduce calf numbers considerably, addressing both ethical and economic concerns in dairy farming and benefiting farmers as well as society.
Is heat stress a growing problem for dairy cattle husbandry in the temperate regions? A case study of Baden-Württemberg in Germany
(2024) Leandro, Miguel António; Stock, Joana; Bennewitz, Jörn; Chagunda, Mizeck G. G.
Heat stress with measurable effects in dairy cattle is a growing concern in temperate regions. Heat stress in temperate regions differs between environments with different geophysical characteristics. Microclimates specific to each environment were found to greatly impact at what level heat stress occurs and will occur in the future. The landlocked state of Baden-Württemberg, Germany, provides several different environments, hence, a good case-study. Temperature–Humidity Index (THI) from 17 weather stations for the years 2003 to 2022 was calculated and milking yields from 22 farms for the years 2017 to 2022 were collected. The occurrences and evolving patterns of heat stress were analyzed with the use of a THI, and the effect of heat stress on milk yield was analyzed based on milking records from Automated Milking Systems. Daily average THI was calculated using hourly readings of relative humidity and ambient temperature, disregarding solar radiation and wind, as all animals were permanently stabled. Based on studies conducted in Baden-Württemberg and neighboring regions, cited ahead in the section of THI, THI = 60 was the threshold for heat stress occurrence. Findings show that the heat stress period varied between stations from 64 to 120 d with THI ≥ 60 in a year. This aligns with yearly and summer averages, also steadily increasing from May to September. The length of the heat stress period was found to increase 1 extra day every year. Extreme weather events such as heat waves did not increase the heat stress period of that year in length but increased the average THI. Milk yield was found to be significantly (α = 0.05) different between counties grouped into different zones according to heat stress severity and rate of increase in daily average THI. Future attempts at managing heat stress on dairy cattle farms in the temperate regions should account for microclimate, as geographical proximity does not mean that the increase in heat stress severity will be the same in the 2 neighboring areas.
tsCRISPR based identification of Rab proteins required for the recycling of Drosophila TRPL ion channel
(2024) Zeger, Matthias; Stanisławczyk, Lena Sarah; Bulić,Marija; Binder, Andrea Maria; Huber, Armin
In polarized cells, the precise regulation of protein transport to and from the plasma membrane is crucial to maintain cellular function. Dysregulation of intracellular protein transport in neurons can lead to neurodegenerative diseases such as Retinitis Pigmentosa, Alzheimer’s and Parkinson’s disease. Here we used the light-dependent transport of the TRPL (transient receptor potential-like) ion channel in Drosophila photoreceptor cells to study the role of Rab proteins in TRPL recycling. TRPL is located in the rhabdomeric membrane of dark-adapted flies, but it is transported out of the rhabdomere upon light exposure and localizes at the Endoplasmatic Reticulum within 12 h. Upon subsequent dark adaptation, TRPL is recycled back to the rhabdomeric membrane within 90 min. To screen for Rab proteins involved in TRPL recycling, we established a tissue specific (ts) CRISPR/Cas9-mediated knock- out of individual Rab genes in Drosophila photoreceptors and assessed TRPL localization using an eGFP tagged TRPL protein in the intact eyes of these mutants. We observed severe TRPL recycling defects in the knockouts of Rab3, Rab4, Rab7, Rab32, and RabX2. Using immunohistochemistry, we further showed that Rab3 and RabX2 each play a significant role in TRPL recycling and also influence TRPL transport. We localized Rab3 to the late endosome in Drosophila photoreceptors and observed disruption of TRPL transport to the ER in Rab3 knock-out mutants. TRPL transport from the ER to the rhabdomere ensues from the trans-Golgi where RabX2 is located. We observed accumulated TRPL at the trans-Golgi in RabX2 knock-out mutants. In summary, our study reveals the requirement of specific Rab proteins for different steps of TRPL transport in photoreceptor cells and provides evidence for a unique retrograde recycling pathway of TRPL from the ER via the trans-Golgi

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