Xanthohumol-Enriched Beer Does Not Exert Antitumorigenic Effects on HeLa Cell Line In Vivo.

Xanthohumol is a hop-derived flavonoid that has been widely examined for its health-protecting and antitumorigenic properties, but not yet in a natural beer matrix. The aim of the study was to investigate the antitumorigenic potential of a xanthohumol-enriched beer in vivo. Four groups of 4 × 10 nude mice were formed. Following the injection of HeLa tumorigenic cell lines, the treatment groups were administered a xanthohumol supplementation for 100 days, either dissolved in beer or in an ethanolic solution with the same alcohol strength as beer. The control groups received un-supplemented material. The terminal tumor masses, liver weights, and plasma antioxidant capacities (FRAP and ABTS methods) were measured. For the statistical analysis, a two-way ANOVA test was performed (p < 0.05). There were no statistically significant differences in tumor size between the groups. Xanthohumol did not induce higher levels of plasma antioxidant capacity, neither in beer nor in the water-ethanol matrix. The terminal liver weights were significantly higher in the control group receiving the unsupplemented ethanol solution. Xanthohumol dissolved in beer or in the water-alcohol matrix did not have a protective effect on tumor growth, nor did it have a positive effect on plasma antioxidant capacity either. However, beer with added xanthohumol had a less harmful effect on the liver compared to the supplemented water-ethanol solution. Our results indicate the possible negative countereffect of ethanol; however, further investigations are needed.

Evaluation of the performance of a human D-dimer test in dogs with neoplasia.

The goal of this study was to evaluate the suitability of a commercially available D-dimer assay as a diagnostic tool for testing dogs. This assay is an immunoturbidimetric diagnostic test, capable of determining the D-dimer levels in human plasma by using 2B9 monoclonal antibody. Plasma samples of clinically healthy (n = 20) and tumour-bearing (n = 50) dogs were measured. The tumours were grouped on the basis of histological type and aggressiveness, and then the measured D-dimer concentrations of these groups were compared to those of the control group. The differences were analysed statistically. For benign tumours, we did not find alterations in the D-dimer levels. However, in the case of malignant tumours (lymphoma, sarcoma, and carcinoma) and in the presence of metastases, significantly elevated D-dimer levels were measured. The assay proved to be suitable for measuring the D-dimer levels in plasma samples of dogs. The calculated reference range for dogs was confirmed to be between 0.06 and 0.69 µg/mL fibrinogen equivalent unit.

The environmental obesogen bisphenol A increases macrophage self-renewal.

Self-renewal of macrophages is important for the healthy development and replenishment of tissue-resident macrophage pools. How this mechanism is controlled by endocrine signals is still largely unexplored. Here, we show that the endocrine disruptor bisphenol A (BPA) increases macrophage self-renewal. This effect was associated with phosphorylation of extracellular signal-regulated kinase (ERK) and a slight increase in the expression of liver X receptor alpha (LXRα). We found that LXRα inhibition induced, while LXRα activation impeded, macrophage self-renewal. LXRα signaling hence may protect from excessive macrophage expansion. Self-renewing macrophages, however, had negligible LXRα expression when compared with quiescent macrophages. Accordingly, tissue-resident macrophage pools, which are dominated by quiescent macrophages, were rich in LXRα-expressing macrophages. Overall, we show that BPA increases macrophage self-renewal and that this effect, at least in part, can be inhibited by increasing LXRα expression. Since BPA is accumulated in the adipose tissue, it has the potential to increase self-renewal of adipose tissue macrophages, leading to a condition that might negatively impact adipose tissue health.

177Lu Labeled Cyclic Minigastrin Analogues with Therapeutic Activity in CCK2R Expressing Tumors: Preclinical Evaluation of a Kit Formulation.

Minigastrin (MG) analogues specifically target cholecystokinin-2 receptors (CCK2R) expressed in different tumors and enable targeted radiotherapy of advanced and disseminated disease when radiolabeled with a beta emitter such as 177Lu. Especially truncated MG analogues missing the penta-Glu sequence are associated with low kidney retention and seem therefore most promising for therapeutic use. Based on [d-Glu1,desGlu2-6]MG (MG11) we have designed the two cyclic MG analogues cyclo1,9[γ-d-Glu1,desGlu2-6,d-Lys9]MG (cyclo-MG1) and cyclo1,9[γ-d-Glu1,desGlu2-6,d-Lys9,Nle11]MG (cyclo-MG2). In the present work we have developed and preclinically evaluated a pharmaceutical kit formulation for the labeling with 177Lu of the two DOTA-conjugated cyclic MG analogues. The stability of the kits during storage as well as the stability of the radiolabeled peptides was investigated. A cell line stably transfected with human CCK2R and a control cell line without receptor expression were used for in vitro and in vivo studies with the radioligands prepared from kit formulations. In terms of stability 177Lu-DOTA-cyclo-MG2 showed advantages over 177Lu-DOTA-cyclo-MG1. Still, for both radioligands a high receptor-mediated cell uptake and favorable pharmacokinetic profile combining receptor-specific tumor uptake with low unspecific tissue uptake and low kidney retention were confirmed. Investigating the therapy efficacy and treatment toxicity in xenografted BALB/c nude mice a receptor-specific and comparable therapeutic effect could be demonstrated for both radioligands. A 1.7- to 2.6-fold increase in tumor volume doubling time was observed for receptor-positive tumors in treated versus untreated animals, which was 39-73% higher when compared to receptor-negative tumors. The treatment was connected with transient bone marrow toxicity and minor signs of kidney toxicity. All together the obtained results support further studies for the clinical translation of this new therapeutic approach.

Beware of phosphate: evidence of specific dendrimer-phosphate interactions.

Dendrimers are extensively studied for drug delivery and catalysis, most of which are pH dependent. Phosphate buffer solutions (PBSs) are often used to adjust the pH. We have found that phosphate ions become incorporated into poly(amidoamine) (PAMAM) dendrimer molecules by forming H-bonds with tertiary nitrogens. We show that this specific interaction between H2PO4- and HPO42- ions and generation five PAMAM dendrimers causes a decrease in hydrodynamic size, disturbing the outcome of the size exclusion chromatography analysis. We monitored this interaction by 1H and 31P high resolution NMR, NMR-diffusiometry, pH-potentiometry and infrared spectroscopy. Failing to take into account this effect may lead to incorrect conclusions and misinterpreting interactions of PAMAM dendrimers with drug molecules and subsequently incorrect dosing. The phosphate salts of amino terminated generation five PAMAM dendrimers are stable for years when stored in the dark, even in dilute aqueous solutions, which has important implications for the shelf-life of dendrimer-based drug delivery systems.

Adipose tissue macrophages in non-rodent mammals: a comparative study.

The stromal vascular fraction (SVF) of adipose tissue in rodents and primates contains mesenchymal stem cells and immune cells. SVF cells have complex metabolic, immune and endocrine functions with biomedical impact. However, in other mammals, the amount of data on SVF stem cells is negligible and whether the SVF hosts immune cells is unknown. In this study, we show that the SVF is rich in immune cells, with a dominance of adipose tissue macrophages (ATMs) in cattle (Bos primigenius taurus), domestic goat (Capra aegagrus hircus), domestic sheep (Ovis aries), domestic cat (Felis catus) and domestic dog (Canis familiaris). ATMs of these species are granulated lysosome-rich cells with lamellipodial protrusions and express the lysosome markers acid phosphatase 5 (ACP-5) and Mac-3/Lamp-2. Using ACP-5 and Mac-3/Lamp-2 as markers, we additionally detected ATMs in other species, such as the domestic horse (Equus ferus caballus), wild boar (Sus scrofa) and red fox (Vulpes vulpes). Feline and canine ATMs also express the murine macrophage marker F4/80 antigen. In the lean condition, the alternative macrophage activation marker CD206 is expressed by feline and canine ATMs and arginase-1 by feline ATMs. Obesity is associated with interleukin-6 and interferon gamma expression and with overt tyrosine nitration in both feline and canine ATMs. This resembles the obesity-induced phenotype switch of murine and human ATMs. Thus, we show, for the first time, that the presence of ATMs is a general trait of mammals. The interaction between the adipose cells and SVF immune cells might be evolutionarily conserved among mammals.

Effect of ELISA kit manufacturing process and incubation time on progesterone concentration measured in dog serum for ovulation diagnosis - Short communication.

Twenty-two serum samples of healthy bitches were tested with the frozen and lyophilised version of the same ELISA kit (Quanticheck, Faculty of Veterinary Science, Budapest, Hungary). Samples were chosen on the basis of their progesterone (P4) concentrations, which were between 1.00 and 20.00 ng/mL. As it is well known, this range has the highest clinical relevance in ovulation diagnosis. Both types of microplates were read at 15-min intervals from the 15th until the 90th minute (min) of incubation, and the results were compared with those of frozen plates at 60 min of incubation as 100 percent. Lyophilised microplates gave on average 18 percent higher results than the frozen version at equal incubation times. The highest difference between lyophilised and frozen samples was observed at 45 and 60 min of incubation. Ninety-four percent of the reaction in the frozen microplate occurred in the first 15 min, and during the subsequent 30 min the reaction seemingly stopped. After the 45th min of incubation, this 94 percent increased to 108 percent in the subsequent 30 min, which remained the final approximate result at the end of the 90 min of incubation. In contrast to the frozen microplate, the measured concentration increased continuously in the lyophilised version and reached the highest level at the 60th min. The results of the lyophilised microplate reached the same level at 30 min of incubation as those of the frozen version at 60 min. In conclusion, a mechanical increase or decrease of the incubation time does not generate a linear change in the test results. This study demonstrated that the results of a series of samples collected from the same bitch cannot be compared if they are measured with different laboratory methods or different ELISA kits.

Tyrosine hydroxylase positive perisomatic rings are formed around various amacrine cell types in the mammalian retina.

Dopaminergic neurons of the central nervous system are mainly found in nuclei of the midbrain and the hypothalamus that provide subcortical and cortical targets with a rich and divergent innervation. Disturbance of signaling through this system underlies a variety of deteriorating conditions such as Parkinson's disease and schizophrenia. Although retinal dopaminergic signaling is largely independent of the above circuitry, malfunction of the retinal dopaminergic system has been associated with anomalies in visual adaptation and a number of retinal disorders. Dopamine (DA) is released mainly in a paracrine manner by a population of tyrosine hydroxylase expressing (TH(+) ) amacrine cells (AC) of the mammalian retina; thus DA reaches virtually all retinal cell types by diffusion. Despite this paracrine release, however, the so called AII ACs have been considered as the main targets of DA signaling owing to a characteristic and robust ring-like TH(+) innervation to the soma/dendritic-stalk area of AII cells. This apparent selectivity of TH(+) innervation seems to contradict the divergent DAergic signaling scheme of other brain loci. In this study, however, we show evidence for intimate proximity between TH(+) rings and somata of neurochemically identified non-AII cells. We also show that this phenomenon is not species specific, as we observe it in popular mammalian animal models including the rabbit, the rat, and the mouse. Finally, our dataset suggests the existence of further, yet unidentified post-synaptic targets of TH(+) dendritic rings. Therefore, we hypothesize that TH(+) ring-like structures target the majority of ACs non-selectively and that such contacts are wide-spread among mammals. Therefore, this new view of inner retinal TH(+) innervation resembles the divergent DAergic innervation of other brain areas through the mesolimbic, mesocortical, and mesostriatal signaling streams. AII amacrine cells have been considered as the main targets of dopamine signaling in the mammalian retina owing to a characteristic ring-like innervation from dopaminergic (TH(+) ) amacrine cells (green) to somata of AII cells (red). In this study, we show the intimate proximity of TH(+) rings and somata of non-AII cells, including starburst-a amacrine cells (blue) and other unidentified amacrine cells (magenta). We find that this phenomenon is not species specific and it occurs in a number of popular mammalian animal models. We hypothesize that TH(+) ring-inputs target most amacrine cells non-selectively and thus it resembles the divergent dopaminergic innervation of other brain areas.

Caging cancer.

This article summarizes the overall issues surrounding cancer for the general audience. Individual differences between patients include genetic and non-genetic differences manifested in various cellular pathways, tumor heterogeneity and variability, differing contribution of tumor microenvironment and potential toward metastasis. Successful treatment of individuals depends on correctly interpreting all these factors and appropriately addressing the actual features by using customized therapy strategies, simultaneously or sequentially. Currently used chemotherapy agents are cytotoxic and typically target one of the major pathways; therefore they have to be applied in combination regimes. Nanomedicines however, have the potential advantage that more than one feature can be built into a complex nanodevice. This yet untapped potential is illustrated on the example of a gadolinium fullerenol cage molecule. Gd@C82(OH)22 has low toxicity, influences several biologic features simultaneously, displays tumoristatic properties, and is effective against triple-negative breast cancer cells. A deeper understanding of the exact relations between the physicochemical characteristics of this system and the biologic events may lead to a new class of efficient anticancer pharmaceutics. FROM THE CLINICAL EDITOR: The search for the magic bullet in the treatment of cancer has long been the dream of clinicians and researchers worldwide. Inherent cellular characteristics of cancer cells have made this task extremely hard to reach. In this article, the author provided a concise summary on the understanding and challenges in the current battle and also illustrated the potential usefulness of the recently developed gadolinium fullerenol cage molecule by describing experimental data from various research groups.

Leptin receptor deficient diabetic (db/db) mice are compromised in postnatal bone regeneration.

Increased fragility fracture risk with improper healing is a frequent and severe complication of insulin resistance (IR). The mechanisms impairing bone health in IR are still not fully appreciated, which gives importance to studies on bone pathologies in animal models of diabetes. Mice deficient in leptin signaling are widely used models of IR and its comorbidities. Leptin was first recognized as a hormone, regulating appetite and energy balance; however, recent studies have expanded its role showing that leptin is a link between insulin-dependent metabolism and bone homeostasis. In the light of these findings, it is intriguing to consider the role of leptin resistance in bone regeneration. In this study, we show that obese diabetic mice lacking leptin receptor (db/db) are deficient in postnatal regenerative osteogenesis. We apply an ectopic osteogenesis and a fracture healing model, both showing that db/db mice display compromised bone acquisition and regeneration capacity. The underlying mechanisms include delayed periosteal mesenchymatic osteogenesis, premature apoptosis of the cartilage callus and impaired microvascular invasion of the healing tissue. Our study supports the use of the db/db mouse as a model of IR associated bone-healing deficits and can aid further studies of mesenchymatic cell homing and differentiation, microvascular invasion, cartilage to bone transition and callus remodeling in diabetic fracture healing.

TNAP activity is localized at critical sites of retinal neurotransmission across various vertebrate species.

Evidence is emerging with regard to the role of tissue non-specific alkaline phosphatase (TNAP) in neural functions. As an ectophosphatase, this enzyme might influence neural activity and synaptic transmission in diverse ways. The localization of the enzyme in known neural circuits, such as the retina, might significantly advance an understanding of its role in normal and pathological functioning. However, the presence of TNAP in the retina is scarcely investigated. Our multispecies comparative study (zebrafish, cichlid, frog, chicken, mouse, rat, golden hamster, guinea pig, rabbit, sheep, cat, dog, ferret, squirrel monkey, human) using enzyme histochemistry and Western blots has shown the presence of TNAP activity in the retina of several mammalian species, including humans. Although the TNAP activity pattern varies across species, we have observed the following trends: (1) in all investigated species (except golden hamster), retinal vessels display TNAP activity; (2) TNAP activity consistently occurs in the photoreceptor layer; (3) in majority of the investigated species, marked TNAP activity is present in the outer and inner plexiform layers. In zebrafish, frog, chicken, guinea pig, and rat, TNAP histochemistry has revealed several sublayers of the inner plexiform layer. Frog, golden hamster, guinea pig, mouse, and human retinas possess a subpopulation of amacrine cells positively staining for TNAP activity. The expression of TNAP in critical sites of retinal signal transmission across a wide range of species suggests its fundamental, evolutionally conserved role in vision.

Body fat distribution and metabolic consequences - Examination opportunities in dogs.

The relationship between metabolic disorders and the distribution of fat in different body regions is not clearly understood in humans. The aim of this study was to develop a suitable method for assessing the regional distribution of fat deposits and their metabolic effects in dogs. Twenty-five dogs were subjected to computed tomographic (CT) imaging and blood sampling in order to characterise their metabolic status. The different fat areas were measured on a cross-sectional scan, and the animals' metabolic status was evaluated by measuring fasting glucose, insulin and leptin levels. The volume of visceral adipose tissue is the main determinant of leptin levels. The correlation of visceral fat volume and leptin concentration was found to be independent of insulin levels or the degree of insulin resistance. There was a positive correlation between the visceral to subcutaneous fat volume ratio and serum insulin concentration, and a similar trend was observed in the relationship of fat ratio and insulin resistance. The distribution of body fat essentially influences the metabolic parameters in dogs, but the effects of adiposity differ between humans and dogs. The findings can facilitate a possible extrapolation of results from animal studies to humans with regard to the metabolic consequences of different obesity types.

[SPECT radiopharmaceuticals -- novelties and new possibilities]. / SPECT-radiofarmakonok -- újdonságok és új lehetoségek.

Actual state of affairs and future perspectives of SPECT radiopharmaceuticals regarding local and international data were summarized. Beyond conventional gamma-emitting radioisotopes, localization studies with beta emitting therapeutic radiopharmaceuticals hold increasing importance. Extension of hybrid (SPECT/CT) equipments has modified conventional scintigraphic and SPECT methods as well but more important changes come into the world through novel ligands for specific diagnoses and therapy.

Antiproliferative activity of polygonaceae species from the Carpathian Basin against human cancer cell lines.

Aqueous and organic extracts of 27 selected species from five genera (Fallopia, Oxyria, Persicaria, Polygonum and Rumex) of the family Polygonaceae occurring in the Carpathian Basin were screened in vitro for antiproliferative activity against HeLa (cervix epithelial adenocarcinoma), A431 (skin epidermoid carcinoma) and MCF7 (breast epithelial adenocarcinoma) cells, using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. A total of 196 n-hexane, chloroform, 50% methanol or water extracts of different plant parts were investigated. It was found that extracts of Polygonum hydropiper, Rumex acetosa, Rumex alpinus, Rumex aquaticus, Rumex scutatus and Rumex thyrsiflorus at 10 or 30 µg/mL demonstrated substantial cell growth inhibitory activity (at least 50% inhibition of cell proliferation) against one or more cell lines. R. acetosa and R. thyrsiflorus proved to be the most active and are considered worthy of activity-guided phytochemical investigations.

PADAPT 1.0 - the Pannonian Dataset of Plant Traits.

The existing plant trait databases' applicability is limited for studies dealing with the flora and vegetation of the eastern and central part of Europe and for large-scale comparisons across regions, mostly because their geographical data coverage is limited and they incorporate records from several different sources, often from regions with markedly different climatic conditions. These problems motivated the compilation of a regional dataset for the flora of the Pannonian region (Eastern Central Europe). PADAPT, the Pannonian Dataset of Plant Traits relies on regional data sources and collates data on 54 traits and attributes of the plant species of the Pannonian region. The current version covers approximately 90% of the species of the region and consists of 126,337 records on 2745 taxa. By including species of the eastern part of Europe not covered by other databases, PADAPT can facilitate studying the flora and vegetation of the eastern part of the continent. Although data coverage is far from complete, PADAPT meets the longstanding need for a regional database of the Pannonian flora.

Physiologically based pharmacokinetic model for composite nanodevices: effect of charge and size on in vivo disposition.

PURPOSE: To characterize temporal exposure and elimination of 5 gold/dendrimer composite nanodevices (CNDs) (5 nm positive, negative, and neutral, 11 nm negative, 22 nm positive) in mice using a physiologically based mathematical model. METHODS: 400 ug of CNDs is injected intravenously to mice bearing melanoma cell lines. Gold content is determined from plasma and tissue samples using neutron activation analysis. A physiologically based pharmacokinetic (PBPK) model is developed for 5 nm positive, negative, and neutral and 11 nm negative nanoparticles and extrapolated to 22 nm positive particles. A global sensitivity analysis is performed for estimated model parameters. RESULTS: Negative and neutral particles exhibited similar distribution profiles. Unique model parameter estimates and distribution profiles explain similarities and differences relative to positive particles. The model also explains mechanisms of elimination by kidney and reticuloendothelial uptake in liver and spleen, which varies with particle size and charge. CONCLUSION: Since the PBPK model can capture the diverse temporal profiles of non-targeted nanoparticles, we propose that when specific binding ligands are lacking, size and charge of nanodevices govern most of their in vivo interactions.

Enhanced optical breakdown in KB cells labeled with folate-targeted silver-dendrimer composite nanodevices.

Enhanced optical breakdown of KB tumor cells folate-targeted with silver-dendrimer composite nanodevices (CNDs) is described. CNDs [(Ag(0))(25)-PAMAM_E5.(NH(2))(42)(NGly)(74)(NFA)(2.7)] were fabricated by reactive encapsulation, using a biocompatible template of dendrimer-folic acid (FA) conjugates. Preferential uptake of the folate-targeted CNDs (of various treatment concentrations and surface functionality) by KB cells was visualized with confocal microscopy and transmission electron microscopy. Intracellular laser-induced optical breakdown threshold and dynamics were detected and characterized by high-frequency ultrasonic monitoring of resulting transient bubble events. When irradiated with a near-infrared, femtosecond laser, the CND-targeted KB cells acted as well-confined activators of laser energy, enhancing nonlinear energy absorption, exhibiting a significant reduction in breakdown threshold and thus selectively promoting intracellular laser-induced optical breakdown. FROM THE CLINICAL EDITOR: This study presents a novel method to selectively destroy cancer cells by combining biochemical targeting with topical laser irradiation. A human epidermoid cancer cell line was targeted with folated silver-dendrimer composite nanodevices and the labeled cancer cells were subsequently destroyed by the microbubbles generated due the enhanced energy uptake of the silver nanoparticles from the laser irradiation, as compared to unlabeled cells.

In Vivo Imaging of Thyroid Cancer with 99mTc-TR1401 and 99mTc-TR1402: A Comparison Study in Dogs.

Differentiated thyroid cancer (DTC) cells may lose NIS expression and iodine uptake, but usually express TSH receptors (TSHR). Therefore, the aim of our study was to compare two radiolabeled superagonist TSH analogues for DTC imaging. These analogues (namely TR1401 and TR1402) have a higher TSHR binding affinity than recombinant human TSH (Thyrogen®). Radiolabeling was performed with technetium-99m using an indirect method via HYNIC conjugation and was followed by in vitro quality controls and binding assay on TSHR-positive cell lines (ML-1). An in vitro binding assay was also performed and compared with radiolabeled human recombinant TSH. In vivo imaging was performed in four dogs with spontaneous follicular thyroid carcinoma with solid poorly differentiated areas with 99mTc-TR1401 SPECT/CT, 99mTc-TR1402 SPECT/CT, and [18F]FDG PET/CT on different days within 2 weeks. TR1401 and TR1402 were labeled with high specific activity (8.3 ± 1.2 MBq/µg) and retention of their biological activity and structural integrity. Both agonists were able to efficiently bind TSHR receptors expressed by cell lines with dissociation constants (Kd) of 2.7 nM for 99mTc-TR1401 and 0.5 nM for 99mTc-TR1402 compared with 99mTc-Thyrogen (Kd = 8.4 nM). In tumor-targeting experiments, a focal uptake was observed in dogs with spontaneous intraglandular thyroid carcinoma, in which TSHR expression was confirmed by immunohistochemistry. 99mTc-TR1402 provided higher T/B than 99mTc-TR1401 and [18F]FDG (12.9 ± 1.3, 10.2 ± 0.7, and 3.8 ± 0.6, respectively; all p < 0.001). Given these results, 99mTc-TR1402 appears to be a useful tool for in vivo imaging of thyroid cancer.

Identification of biological tissues by rapid evaporative ionization mass spectrometry.

The newly developed rapid evaporative ionization mass spectrometry (REIMS) provides the possibility of in vivo, in situ mass spectrometric tissue analysis. The experimental setup for REIMS is characterized in detail for the first time, and the description and testing of an equipment capable of in vivo analysis is presented. The spectra obtained by various standard surgical equipments were compared and found highly specific to the histological type of the tissues. The tissue analysis is based on their different phospholipid distribution; the identification algorithm uses a combination of principal component analysis (PCA) and linear discriminant analysis (LDA). The characterized method was proven to be sensitive for any perturbation such as age or diet in rats, but it was still perfectly suitable for tissue identification. Tissue identification accuracy higher than 97% was achieved with the PCA/LDA algorithm using a spectral database collected from various tissue species. In vivo, ex vivo, and post mortem REIMS studies were performed, and the method was found to be applicable for histological tissue analysis during surgical interventions, endoscopy, or after surgery in pathology.

Comparison of Behavior and Genetic Structure in Populations of Family and Kenneled Beagles.

In dogs, the social and spatial restriction associated with living in a kennel environment could lead to chronic stress and the development of abnormal behaviors ("kennel-dog syndrome"). However, little is known about how kenneled dogs differ from their conspecifics living as pets in human families. In the current study, using a test battery exposing the dogs to novel stimuli, we compared the behavior of three groups of beagles: (1) kenneled dogs living in a restricted environment with limited human contact (N = 78), (2) family dogs living in human families as pets (N = 37), and (3) adopted dogs born in the kenneled population but raised in human families (N = 13). We found one factor comprising most of the test behaviors, labeled as Responsiveness. Family dogs and adopted dogs scored higher in Responsiveness than kenneled dogs. However, 23% of the kenneled dogs were comparable to family and adopted dogs based on a cluster analysis, indicating a similar (positive) reaction to novel stimuli, while 77% of the kenneled dogs were unresponsive (mostly immobile) in at least part of the test. To assess if the behavioral difference between the family and kenneled dogs could be due to genetic divergence of these two populations and/or to lower genetic diversity of the kenneled dogs, we analyzed their genetic structure using 11 microsatellite markers. We found no significant difference between the populations in their genetic diversity (i.e., heterozygosity, level of inbreeding), nor any evidence that the family and kenneled populations originated from different genetic pools. Thus, the behavior difference between the groups more likely reflects a G × E interaction, that is, the influence of specific genetic variants manifesting under specific environmental conditions (kennel life). Nevertheless, some kenneled individuals were (genetically) more resistant to social and environmental deprivation. Selecting for such animals could strongly improve the welfare of kenneled dog populations. Moreover, exploring the genetic background of their higher resilience could also help to better understand the genetics behind stress- and fear-related behaviors.