Plasticity and biotic interactions mediate plant persistence in a changing world

Anthropogenic global change is occurring today at a faster rate and larger scale than ever before. Understanding how plants will respond to such large-scale disturbance is critical for biodiversity conservation, yet the ecological and evolutionary mechanisms underlying these responses remain poorly understood. In this thesis, I investigated the mechanisms underlying plant response to two major drivers of global change, climate change and the widespread mortality of foundation species. First, I examined genetic and plastic plant trait responses to climatic variation using elevation gradients, which serve as space-for-time substitutions for climate change. Through field observations in three populations of the North American shrub Rhododendron maximum (rosebay rhododendron), I found that while several traits respond significantly to elevation, these trait responses typically occur in some, but not all, populations. A common garden experiment indicated that trait variation within and among populations was driven by plasticity and genetic divergence, respectively. These findings suggest that plasticity can be a viable climate change response, although the magnitude of this plasticity will likely differ among genetically distinct populations. Next, I examined whether plant-soil biota interactions and/or light variation associated with foundation tree decline mediate the expansion of R. maximum in southeastern US forests where Tsuga canadensis (eastern hemlock), a dominant foundation tree species, is declining due to non-native insect invasion. Using a controlled inoculation experiment, I found that, in high light (matching infested T. canadensis crowns), R. maximum seedling performance was highest in T. canadensis-conditioned soils, medial in R. maximum-conditioned soils, and lowest in interspace soils. Genomic sequencing indicated that such variation in performance can be attributed to variation in mycorrhizal and saprotrophic soil fungal guilds. In low light (matching healthy T. canadensis crowns), however, soil inoculation did not affect plant performance and plants performed worse on average. These findings suggest interactions with soil biota can act synergistically with altered light environments to mediate species’ responses to widespread foundation tree mortality, providing evidence for a novel mechanism of plant response to major disturbance. Overall, my work suggests that plant persistence in a changing world will depend on multiple mechanisms, including plasticity, genetic differentiation, and biotic interactions

Wenn Markt und Ökologie an einem Strang ziehen

Mit der Initiative Grundwasserschutz durch Öko-Landbau will die Regierung von Unterfranken landwirtschaftliche Betriebe zur Umstellung motivieren. An der Aktion beteiligt sind Unternehmen der Bio-Lebensmittelwirtschaft, Bio-Verbände und der Bayerische Bauernverband

Trait Variation Along Elevation Gradients in a Dominant Wood Shrub is Population-Specific and Driven by Plasticity

Elevation gradients are frequently used as space-for-time substitutions to infer species’ trait responses to climate change. However, studies rarely investigate whether trait responses to elevation are widespread or population specific within a species, and the relative genetic and plastic contributions to such trait responses may not be well understood. Here, we examine plant trait variation in the dominant woody shrub, Rhododendron maximum, along elevation gradients in three populations in the South Central Appalachian Mountains, USA, in both field and common garden environments. We ask the following: (1) do plant traits vary along elevation? (2) do trait responses to elevation differ across populations, and if so, why? and (3) does genetic differentiation or phenotypic plasticity drive trait variation within and among populations? We found that internode length, shoot length, leaf dry mass, and leaf area varied along elevation, but that these responses were generally unique to one population, suggesting that trait responses to environmental gradients are population-specific. A common garden experiment identified nogenetic basis to variation along elevation or among populations in any trait, suggesting that plasticity drives local and regional trait variation and may play a key role in the persistence of plant species such as R. maximum with contemporary climate change. Overall, our findings highlight the importance of examining multiple locations in future elevation studies and indicate that, for a given plant species, the magnitude of trait responses to global climate change may vary by location

Bericht des Nationalen Referenzzentrums für gramnegative Krankenhauserreger Zeitraum 1. Januar 2021 bis 31. Dezember 2021

Nach dem erstmaligen, pandemiebedingten Rückgang der Einsendungen im Vorjahr verzeichnete das Nationale Referenzzentrum (NRZ) für gramnegative Krankenhauserreger 2021 wieder einen Anstieg an eingesandten Isolaten, wenngleich das Niveau von 2019 noch nicht wieder erreicht wurde. Durch den Einfluss der Pandemie auf verschiedene Faktoren gilt allerdings auch für den Jahresbericht 2021 der Vorbehalt, dass eine Vergleichbarkeit mit den Vorjahren Limitationen unterliegt. Insgesamt gingen 8.526 Einsendungen aus 283 mikrobiologischen Laboren in Deutschland ein. Die meisten Isolate wurden zur Abklärung einer verminderten Empfindlichkeit gegenüber Carbapenemen eingesandt. Die Anzahl der Carbapenemase-Nachweise stieg deutlich an, wie auch die Zahl der Isolate, die mehr als eine Carbapenemase produzierten. Ein deutlicher Rückgang hingegen war bei den Nachweisen von NDM-5- und OXA-244-produzierenden E. coli zu verzeichnen.Peer Reviewe

Mammalian target of rapamycin inhibition impacts energy homeostasis and induces sex-specific body weight loss in humans

BACKGROUND: Previous data from a 2-year randomized controlled trial (CRAD001ADE12) indicated that mammalian target of rapamycin (mTOR) inhibition by everolimus slowed cyst growth in patients with autosomal-dominant polycystic kidney disease (ADPKD). During the trial, we noted body weight loss in some patients, particularly in women. We hypothesized that everolimus causes body weight reduction by reduced food intake and/or metabolic changes, which could lead to cachexia. METHODS: Within a sub-analysis of the CRAD001ADE12 trial, body weight course was investigated regarding sex-specific differences in 433 adult ADPKD patients (everolimus, n = 215; placebo, n = 218). One hundred four out of 111 patients who participated in the clinical trial centre in Berlin were evaluated under everolimus/placebo therapy (on drug: everolimus, n = 48; placebo, n = 56) and after therapy (off drug: everolimus, n = 15; placebo, n = 18). Eating habits and nutrient/caloric intake were evaluated by validated questionnaires. Systemic and local metabolism was evaluated in four patients after an oral glucose load (OGL) by using calorimetry and adipose/muscle tissue microdialysis. RESULTS: Within the 2-year CRAD001ADE12 trial, a significant body weight loss was observed in female patients on everolimus versus placebo (P = 0.0029). Data of the Berlin Cohort revealed that weight loss was greater in women on everolimus versus men (P < 0.01). After 9 months, women and men had lost 2.6 ± 3.8 and 0.8 ± 1.5 kg (P < 0.05) in body weight, respectively, and after 21 months, they had lost 4.1 ± 6.6 and 1.0 ± 3.3 kg (P < 0.05), respectively. On everolimus, caloric intake was significantly lower in women versus men (1510 ± 128 vs. 2264 ± 216 kcal/day, P < 0.05), caused mainly by a lower fat and protein intake in women versus men. Cognitive restraints, disinhibition and hunger remained unchanged. In a subgroup of patients resting metabolic rate was unchanged whereas OGL-induced thermogenesis was reduced (7 ± 2 vs. 11 ± 2 kcal, P < 0.05). Fasting and OGL-induced fat oxidation was increased (P < 0.05) on versus off everolimus. In adipose tissue, fasting lipolytic activity was increased, but lipolytic activity was inhibited similarly after the OGL on versus off everolimus, respectively. In skeletal muscle, postprandial glucose uptake and aerobic glycolysis was reduced in patients on everolimus. CONCLUSIONS: mTOR inhibition by everolimus induces body weight reduction, specifically in female patients. This effect is possibly caused by a centrally mediated reduced food (fat and protein) intake and by centrally/peripherally mediated increased fat oxidation (systemic) and mobilization (adipose tissue). Glucose uptake and oxidation might be reduced in skeletal muscle. This could lead to cachexia and, possibly, muscle wasting. Therefore, our results have important implications for patients recieving immune-suppressive mTOR inhibition therapy

Bericht des Nationalen Referenzzentrums für gramnegative Krankenhauserreger

Im Zeitraum vom 1. Januar 2022 bis zum 31. Dezember 2022 gab es im Nationalen Referenzzentrum (NRZ) für gramnegative Krankenhauserreger 9.548 Einsendungen von Bakterienisolaten. Dies entspricht einem Anstieg von fast 12 % im Vergleich zu 2021 und übertrifft das Vor-Pandemieniveau von 2019 (n = 9.369). Die Anzahl der Einsendungen lag bei durchschnittlich 796 Einsendungen pro Monat, die Isolate stammten aus 301 mikrobiologischen Laboren in Deutschland. Die Zahl der einsendenden Labore nahm im Vergleich zum Vorjahr (n = 283) ebenfalls zu. Wie das Epidemiologische Bulletin 27/2023 ausführt, stieg zudem Die Anzahl der Carbapenemase-Nachweise bei den bearbeiteten Isolaten stieg zudem auf den höchsten jemals im NRZ beobachteten Anstieg.Peer Reviewe

Combined Clinical, Epidemiological, and Genome-Based Analysis Identified a Nationwide Outbreak of Burkholderia cepacia Complex Infections Caused by Contaminated Mouthwash Solutions

Background: In September 2018, Burkholderia cepacia complex (BCC) infections in 3 patients associated with exposure to a mouthwash solution (MWS) were reported to the Robert Koch Institute (RKI). As the product was still on the market and the scale of the outbreak was unclear, a nation-wide investigation was initiated. Methods: We aimed to investigate BCC infections/colonizations associated with MWS. Hospitals, laboratories, and public health services were informed that BCC isolates should be sent to the RKI. These isolates were typed by pulsed-field gel electrophoresis (PFGE) and whole-genome sequencing (WGS) including development of an ad hoc core genome MLST (cgMLST) scheme. Results: In total, 36 patients from 6 hospitals met the case definition, the last patient in November 2018. Twenty-nine isolates from 26 of these patients were available for typing. WGS analysis revealed 2 distinct cgMLST clusters. Cluster 1 (Burkholderia arboris) contained isolates from patients and MWS obtained from 4 hospitals and isolates provided by the manufacturer. Patient and MWS isolates from another hospital were assigned to cluster 2 (B. cepacia). Conclusions: The combined clinical, epidemiological, and microbiological investigation, including whole-genome analysis, allowed for uncovering a supraregional BCC outbreak in health care settings. Strains of B. arboris and B. cepacia were identified as contaminating species of MWS bottles and subsequent colonization and putative infection of patients in several hospitals. Despite a recall of the product by the manufacturer in August 2018, the outbreak lasted until December 2018. Reporting of contaminated medical products and recalls should be optimized to protect patients.Peer Reviewe