Peroxidase-mediated oxidation, a possible pathway for metabolic activation of diethylstilbestrol

$\text{In vitro}$ oxidation of diethylstilbestrol (DES) by peroxidase preparations from horse radish or mouse uterus in the presence of hydrogen peroxide yields β-dienestrol, which is also a major $\text{in vivo}$ metabolite of DES in several mammalian species. The oxidation reaction appears to involve reactive intermediates, presumably the semiquinone and quinone of DES, since nonextractable binding to salmon sperm deoxyribonucleic acid and bovine serum albumin was found. The peroxidase-catalyzed oxidation of DES to reactive metabolites in estrogen target organs may be related to the organ toxicity of this synthetic estrogen.     

Estimation of the Use of Antibiotics in the Small Ruminant Industry in the Netherlands in 2011 and 2012

The aim of this study was to estimate the quantity of antibiotics and classes of antibiotics used in the small ruminant industry in the Netherlands in 2011 and 2012. Twelve large veterinary practices, located throughout the Netherlands were selected for this study. All small ruminant farms associated with these practices that had complete records on the quantity of antibiotics prescribed were included. The veterinary practices provided data on all antibiotics prescribed, and the estimated animal used daily dose of antibiotics per year (AUDD/Y) was calculated for each farm. The median AUDD/Y in small ruminant farms was zero in both years (mean 0.60 in 2011, and 0.62 in 2012). The largest quantity of antibiotic use was observed in the professional goat industry (herds of ≥32 goats) with a median AUDD/Y of 1.22 in 2011 and 0.73 in 2012. In the professional sheep industry (flocks of ≥32 sheep), the median AUDD/Y was 0 in 2011 and 0.10 in 2012. In the small scale industry (flocks or herds of <32 sheep or goats), the median AUDD/Y never exceeded 0. The most frequently prescribed antibiotics in the small scale industry and professional sheep farms belonged to the penicillin class. In professional goat farms, antibiotics of the aminoglycoside class were most frequently prescribed. This study provides the first assessment on the quantity of antibiotic use in the small ruminant industry. Given a comparable attitude towards antibiotic use, these results might be valid for small ruminant populations in other north-western European countries as well. The antibiotic use in the small ruminant industry appeared to be low, and is expected to play a minor role in the development of antibiotic resistance. Nevertheless, several major zoonotic bacterial pathogens are associated with the small ruminant industry, and it remains important that antibiotics are used in a prudent way.     

A novel Axin2 knock‐in mouse model for visualization and lineage tracing of WNT/CTNNB1 responsive cells

Wnt signal transduction controls tissue morphogenesis, maintenance and regeneration in all multicellular animals. In mammals, the WNT/CTNNB1 (Wnt/β‐catenin) pathway controls cell proliferation and cell fate decisions before and after birth. It plays a critical role at multiple stages of embryonic development, but also governs stem cell maintenance and homeostasis in adult tissues. However, it remains challenging to monitor endogenous WNT/CTNNB1 signaling dynamics in vivo. Here, we report the generation and characterization of a new knock‐in mouse strain that doubles as a fluorescent reporter and lineage tracing driver for WNT/CTNNB1 responsive cells. We introduced a multi‐cistronic targeting cassette at the 3′ end of the universal WNT/CTNNB1 target gene Axin2. The resulting knock‐in allele expresses a bright fluorescent reporter (3xNLS‐SGFP2) and a doxycycline‐inducible driver for lineage tracing (rtTA3). We show that the Axin2^{P2A‐rtTA3‐T2A‐3xNLS‐SGFP2} strain labels WNT/CTNNB1 responsive cells at multiple anatomical sites during different stages of embryonic and postnatal development. It faithfully reports the subtle and dynamic changes in physiological WNT/CTNNB1 signaling activity that occur in vivo. We expect this mouse strain to be a useful resource for biologists who want to track and trace the location and developmental fate of WNT/CTNNB1 responsive stem cells in different contexts.     

The aged hematopoietic system promotes hippocampal‐dependent cognitive decline

The aged systemic milieu promotes cellular and cognitive impairments in the hippocampus. Here, we report that aging of the hematopoietic system directly contributes to the pro‐aging effects of old blood on cognition. Using a heterochronic hematopoietic stem cell (HSC) transplantation model (in which the blood of young mice is reconstituted with old HSCs), we find that exposure to an old hematopoietic system inhibits hippocampal neurogenesis, decreases synaptic marker expression, and impairs cognition. We identify a number of factors elevated in the blood of young mice reconstituted with old HSCs, of which cyclophilin A (CyPA) acts as a pro‐aging factor. Increased systemic levels of CyPA impair cognition in young mice, while inhibition of CyPA in aged mice improves cognition. Together, these data identify age‐related changes in the hematopoietic system as drivers of hippocampal aging.     

Bird diversity and endemism along a land‐use gradient in Madagascar: The conservation value of vanilla agroforests

Land‐use change is the most important driver of biodiversity loss worldwide and particularly so in the tropics, where natural habitats are transformed into large‐scale monocultures or heterogeneous landscape mosaics of largely unknown conservation value. Using birds as an indicator taxon, we evaluated the conservation value of a landscape mosaic in northeastern Madagascar, a biodiversity hotspot and the center of global vanilla production. We assessed bird species richness and composition by conducting point counts across seven prevalent land‐use types (forest‐ and fallow‐derived vanilla agroforests, woody and herbaceous fallow that are part of a shifting cultivation system, rice paddy, forest fragment and contiguous old‐growth forest). We find that old‐growth forest had the highest species richness, driven by a high share of endemics. Species richness and community composition in forest‐derived vanilla agroforest were similar to forest fragment, whereas fallow‐derived vanilla agroforest was most comparable to woody fallow. The open land‐use types herbaceous fallow and rice paddy had fewest species. Across forest fragments, vanilla agroforests, and woody fallows, endemic bird species richness was positively correlated to landscape‐scale forest cover. We conclude that both fallow‐ and forest‐derived vanilla agroforests play an important but contrasting role for bird conservation: Fallow‐derived agroforests are less valuable but take fallow land out of the shifting cultivation cycle, possibly preventing further degradation. Conversely, forest‐derived agroforests contribute to forest degradation but may avoid total loss of tree cover from forest fragments. Considering the land‐use history of agroforests may thus be a promising avenue for future research beyond the case of vanilla. Abstract in Malagasay is available with online material     

SARS-CoV-2 RNA screening in routine pathology specimens

Virus detection methods are important to cope with the SARS-CoV-2 pandemics. Apart from the lung, SARS-CoV-2 was detected in multiple organs in severe cases. Less is known on organ tropism in patients developing mild or no symptoms, and some of such patients might be missed in symptom-indicated swab testing. Here, we tested and validated several approaches and selected the most reliable RT-PCR protocol for the detection of SARS-CoV-2 RNA in patients’ routine diagnostic formalin-fixed and paraffin-embedded (FFPE) specimens available in pathology, to assess (i) organ tropism in samples from COVID-19-positive patients, (ii) unrecognized cases in selected tissues from negative or not-tested patients during a pandemic peak, and (iii) retrospectively, pre-pandemic lung samples. We identified SARS-CoV-2 RNA in seven samples from confirmed COVID-19 patients, in two gastric biopsies, one small bowel and one colon resection, one lung biopsy, one pleural resection and one pleural effusion specimen, while all other specimens were negative. In the pandemic peak cohort, we identified one previously unrecognized COVID-19 case in tonsillectomy samples. All pre-pandemic lung samples were negative. In conclusion, SARS-CoV-2 RNA detection in FFPE pathology specimens can potentially improve surveillance of COVID-19, allow retrospective studies, and advance our understanding of SARS-CoV-2 organ tropism and effects.     

Ecological Network Indicators of Ecosystem Status and Change in the Baltic Sea

Several marine ecosystems under anthropogenic pressure have experienced shifts from one ecological state to another. In the central Baltic Sea, the regime shift of the 1980s has been associated with food-web reorganization and redirection of energy flow pathways. These long-term dynamics from 1974 to 2006 have been simulated here using a food-web model forced by climate and fishing. Ecological network analysis was performed to calculate indices of ecosystem change. The model replicated the regime shift. The analyses of indicators suggested that the system’s resilience was higher prior to 1988 and lower thereafter. The ecosystem topology also changed from a web-like structure to a linearized food-web.     

Genome-Wide Gene Expression Analysis of Bordetella pertussis Isolates Associated with a Resurgence in Pertussis: Elucidation of Factors Involved in the Increased Fitness of Epidemic Strains

Bordetella pertussis (B. pertussis) is the causative agent of whooping cough, which is a highly contagious disease in the human respiratory tract. Despite vaccination since the 1950s, pertussis remains the most prevalent vaccine-preventable disease in developed countries. A recent resurgence pertussis is associated with the expansion of B. pertussis strains with a novel allele for the pertussis toxin (ptx) promoter ptxP3 in place of resident ptxP1 strains. The recent expansion of ptxP3 strains suggests that these strains carry mutations that have increased their fitness. Compared to the ptxP1 strains, ptxP3 strains produce more Ptx, which results in increased virulence and immune suppression. In this study, we investigated the contribution of gene expression changes of various genes on the increased fitness of the ptxP3 strains. Using genome-wide gene expression profiling, we show that several virulence genes had higher expression levels in the ptxP3 strains compared to the ptxP1 strains. We provide the first evidence that wildtype ptxP3 strains are better colonizers in an intranasal mouse infection model. This study shows that the ptxP3 mutation and the genetic background of ptxP3 strains affect fitness by contributing to the ability to colonize in a mouse infection model. These results show that the genetic background of ptxP3 strains with a higher expression of virulence genes contribute to increased fitness.