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Abstract Background Laboratory rats, as model animals, have been extensively used in the fields of life science and medicine. It is crucial to routinely monitor the genetic background of laboratory rats. The conventional approach relies on gel electrophoresis and capillary electrophoresis (CE) technologies. However, the experimental and data analysis procedures for both of these methods are time consuming and costly. Results We established a single-nucleotide polymorphism (SNP) typing scheme using multiplex polymerase chain reaction (PCR) and next-generation sequencing (NGS) to address the genetic background ambiguity in laboratory rats. This methodology involved three rounds of PCR and two rounds of magnetic bead selection to improve the quality of the sequencing data. We simultaneously analysed 100 laboratory rats (including rats of 5 inbred strains and 2 in-house closed colonies), and the sequencing depth varied from an average of 108.25 to 5189.89, with sample uniformity ranging from 82.5 to 97.5%. A total of 98.9% of the amplicons were successfully genotyped (≥ 30 reads). Genetic background analysis revealed that all 38 experimental rats from the 5 inbred strains were successfully identified (without a heterozygous allele). For the 2 in-house closed colonies, the average heterozygosity (0.162 and 0.169) deviated from the typical range of 0.5–0.7, indicating a departure from the ideal heterozygosity level. Additionally, we employed multiplex PCR-CE to validate the NGS-based method, which yielded consistent results for all the rat strains. These results demonstrated that this approach significantly improves efficiency, saves time, reduces costs and ensures accuracy. Conclusion By utilizing NGS technology, our developed method leverages SNP genotyping for genetic background identification in laboratory rats, demonstrating advantages in terms of labour efficiency and cost-effectiveness, thereby rendering it well suited for projects involving extensive sample cohorts.

This article investigates the effects of licorice root (Glycyrrhiza L.) syrup on laboratory rats exposed to ionizing gamma radiation, focusing on its potential radioprotective properties. Ionizing gamma radiation induces oxidative stress, characterized by an increase in free radicals and subsequent tissue damage, which can contribute to the development of various diseases such as neurodegenerative, cardiovascular, diabetes and kidney diseases. The body’s antioxidant defense mechanisms, including superoxide dismutase (SOD), catalase (CAT) and malondialdehyde (MDA), play crucial roles in combating oxidative stress. Historically recognized for its medicinal properties, licorice root may mitigate the harmful effects of radiation. The research employed Electron Paramagnetic Resonance (EPR) spectroscopy to analyze structural and functional changes in various biological systems under the influence of radiation and other stressors. This investigation aims to provide insights into the protective effects of licorice syrup, contributing to the understanding of potential therapeutic strategies against radiation-induced oxidative damage. As a continuation of the experiments, the levels of antioxidant enzymes in the rat’s erythrocytes were measured using various methods. Biochemical analyses conducted on the erythrocytes of the rats indicated positive effects of licorice syrup on the levels of SOD, CAT and MDA. [ABSTRACT FROM AUTHOR]

Among various mammals, the laboratory rat (Rattus norvegicus) is widely used for experimental purposes and belongs to the order Rodentia, family Muridae, and genus Rattus. The lack of comprehensive studies on the topography and CT anatomy of thoracic structures in this species necessitates further investigation. This study aims to accurately describe the topography of the lungs, trachea, and heart in rats based on CT scan findings compared with anatomical observations. CT scan images were obtained from 10 adult male rats at 1 mm intervals using a Siemens Somatom Spirit CT Scanner, followed by anatomical studies through autopsy. Morphometric measurements were taken from the CT images, and the thorax, lungs, heart, and intrathoracic trachea, along with the spatial relationships of the organs, were meticulously examined during the anatomical studies. Detailed descriptions were compiled from both the CT scan images and autopsy findings. The tracheal bifurcation was consistently located between the fourth and fifth ribs in all samples. The right lung was larger and more voluminous than the left lung. The heart was oriented toward the left, and the right bronchus was shorter than the left. The results confirmed that the right lung was more voluminous than the left lung in R. norvegicus, as evidenced by precise measurements. It was also found to be longer than the left lung, although both lungs exhibited similar width and height. Notably, the use of CT scans enables anatomical examination of living and active body structures, which can be practically beneficial. In general, the lungs extend from the second rib to the last rib, with the right lung occupying slightly more space both anteriorly and dorsally. Regarding lobulation, the left lung consists of one lobe, while the right lung has four lobes. This study underscores the value of CT imaging in facilitating anatomical assessments in vivo, enhancing its practical applicability. [ABSTRACT FROM AUTHOR]

Introduction Non-surgical treatment of osteoarthritis is aimed at managing joint degeneration and inflammation to prolong the life of the original joint and delay total joint replacement. The objective was to pathomorphologically substantiate preclinical effectiveness of PRP in OA using comparative analysis of depleted plasma and serum. Material and methods The experiment was performed in 120 Wistar rats, divided into 4 groups. Osteoarthritis was simulated using an original method. Knee joint injection given to the animals after skin dissection under inhalation anesthesia and visual control two weeks later contained 0.05 ml PRP in group 1, 0.05 ml plasma in groups 2 and 0.05 ml blood serum in groups 3. The same volume of physiological saline solution was used for the injections produced for control animals. Injections were administered three times at 2-week intervals. Animals were sacrificed in groups of 10 at 2 weeks of each injection. Results The median MANKIN value scored 2.0 (1.0; 2.0) in group 1, 6.0 (5.0; 7.0) in group 2 and 7.0 (6.0; 7.0) in group 3 at 6 weeks. The median MANKIN value scored 7.5 (7.0, 8.0) in the control group. Statistically significant differences were determined between the groups at p < 0.001. Discussion Literature data on preclinical evaluation of the effectiveness of PRP therapy in biological models of OA are controversial. An original, low-traumatic functional method was used for simulating knee OA to reproduce major pathogenetic mechanisms in rats. Conclusion The findings suggested a pronounced therapeutic effect with improved morphofunctional features of the hyaline cartilage and MANKIN score of 2 at 6 days of intra-articular administration of modified PRP as compared with plasma and serum.

Simple Summary: Carbamazepine is an active compound in commonly used drugs for the treatment of epilepsy and other diseases. It is a very stable substance that remains in the environment, especially in waste water, but also in surface water. Because of this, it can pose a potential risk to both animals and humans. Although its effect in therapeutic doses has been described, the effects of low doses on the environment are unknown. We were interested in whether the consumption of food contaminated with carbamazepine can cause certain changes in behaviour and whether it simultaneously affects gene expression in higher vertebrates. The laboratory rats served as model organisms. The animals were divided into three groups, where one group orally received a high therapeutic dose of carbamazepine, the second received a low environmental dose, and the third control group received a solution without carbamazepine. The results of behavioural testing, which focused on cognitive abilities, anxiety-like behaviour, and social behaviour, did not reveal any changes; however, the expression of a certain gene on the brain of rats was affected by carbamazepine. Carbamazepine (CBZ), an effective drug for epilepsy and other neurological diseases, and its metabolites are one of the most frequently detected substances in the aquatic environment. Although these are doses of very low concentrations, chronic exposure to them can affect the physiological processes of living organisms. This experiment may clarify if carbamazepine, under an environmental and a therapeutic concentration, can affect the behaviour of higher vertebrates, especially mammals, and gene expressions of Ugt1a6 and Ugt1a7 in the brain compared to the control group without exposure to CBZ. Three groups of thirteen rats were randomly formed, and each group was treated either with carbamazepine 12 mg/kg (therapeutic), carbamazepine 0.1 mg/kg (environmental), or by 10% DMSO solution (control). The memory, anxiety, and social behaviour of the rats were assessed by the test Elevated Plus Maze, the novel object recognition test, and the social chamber paradigm. After testing, they were euthanised and brain tissue samples were collected and analysed for mRNA expression of Ugt1a6 and Ugt1a7 genes. The tests did not show significant differences in the behaviour of the rats between the groups. However, there were significant changes at the gene expression level of Ugt1a7. [ABSTRACT FROM AUTHOR]

The prevalence and societal impact of neurodevelopmental disorders (NDDs) continue to increase despite years of research in both patient populations and animal models. There remains an urgent need for translational efforts between clinical and preclinical research to (i) identify and evaluate putative causes of NDD, (ii) determine their underlying neurobiological mechanisms, (iii) develop and test novel therapeutic approaches, and (iv) translate basic research into safe and effective clinical practices. Given the complexity behind potential causes and behaviors affected by NDDs, modeling these uniquely human brain disorders in animals will require that we capitalize on unique advantages of a diverse array of species. While much NDD research has been conducted in more traditional animal models such as the mouse, ultimately, we may benefit from creating animal models with species that have a more sophisticated social behavior repertoire such as the rat (Rattus norvegicus) or species that more closely related to humans, such as the rhesus macaque (Macaca mulatta). Here, we highlight the rat and rhesus macaque models for their role in previous psychological research discoveries, current efforts to understand the neurobiology of NDDs, and focus on the convergence of behavior outcome measures that parallel features of human NDDs.

Carbamazepine (CBZ), an effective drug for epilepsy and other neurological diseases, and its metabolites are one of the most frequently detected substances in the aquatic environment. Although these are doses of very low concentrations, chronic exposure to them can affect the physiological processes of living organisms. This experiment may clarify if carbamazepine, under an environmental and a therapeutic concentration, can affect the behaviour of higher vertebrates, especially mammals, and gene expressions of Ugt1a6 and Ugt1a7 in the brain compared to the control group without exposure to CBZ. Three groups of thirteen rats were randomly formed, and each group was treated either with carbamazepine 12 mg/kg (therapeutic), carbamazepine 0.1 mg/kg (environmental), or by 10% DMSO solution (control). The memory, anxiety, and social behaviour of the rats were assessed by the test Elevated Plus Maze, the novel object recognition test, and the social chamber paradigm. After testing, they were euthanised and brain tissue samples were collected and analysed for mRNA expression of Ugt1a6 and Ugt1a7 genes. The tests did not show significant differences in the behaviour of the rats between the groups. However, there were significant changes at the gene expression level of Ugt1a7.

Introduction: Busulfan-related oxidative stress reduces fertility; therefore, this study aimed to investigate the protective role of crocin on ovarian histological changes. Materials & Methods: This study was conducted on 30 adult NMRI rats weighing 22-25 g in 6 equal groups in a 21-day period. The control group received a single dose (0.1 ml) of busulfan solvent (DMSO+PBS) intraperitoneally (IP) and the sham control group were subjected to a single dose of IP busulfan (10 mg/kg). Moreover, the experimental groups of 1, 2, and 3 received crocin intraperitoneally with doses of 100, 200, 400 mg/kg/day, respectively along with a single dose of busulfan (10 mg/kg). The positive control group received only crocin intraperitoneally at a dose of 400 mg/kg/day. After the end of the treatment period, animals were euthanized with a high-dose of ketamine. Left ovaries were used for the histomorphometric study. The data were analyzed using SPSS software (version19) through a one-way ANOVA and Bonferroni test. A P-value less than 0.05 were considered statistically significant. Ethics code: AECVU-192-2019 Findings: This study showed that the antioxidant properties of crocin could neutralize the busulfan-related oxidative stress which resulted in the growth of more healthy ovarian follicles and reduced the mean number of Atretic follicles, compared to the group received busulfan. Moreover, this study revealed dose-depended effects of crocin which indicated a significant benefit on the majority of parameters with a dose of 200 mg/kg. Discussion & Conclusions: The present study showed the remarkable ability of crocin in reducing the adverse effects of busulfan on the growth of ovarian follicles.

The laboratory rat was the first mammal domesticated for research purposes. It is descended from wild Norway rats, Rattus norvegicus, which despite their name likely originated in Asia. Exceptionally adaptable, these rodents now inhabit almost all environments on Earth, especially near human settlements where they are often seen as pests. The laboratory rat thrives in captivity, and its domestication has produced many inbred and outbred lines that are used for different purposes, including medical trials and behavioral studies. Differences between wild Norway rats and their laboratory counterparts were first noted in the early 20th century and led some researchers to later question its value as a model organism. While these views are probably unjustified, the advanced domestication of the laboratory rat does suggest that resuming studies of wild rats could benefit the wider research community.

Staphylococci from the Staphylococcus intermedius-Staphylococcus hyicus species group include numerous animal pathogens and are an important reservoir of virulence and antimicrobial resistance determinants. Due to their pathogenic potential, they are possible causative agents of zoonoses in humans; therefore, it is important to address the properties of these strains. Here we used a polyphasic taxonomic approach to characterize the coagulase-negative staphylococcal strain NRL/St 03/464T, isolated from the nostrils of a healthy laboratory rat during a microbiological screening of laboratory animals. The 16S rRNA sequence, MALDI-TOF mass spectrometry and positive urea hydrolysis and beta-glucuronidase tests clearly distinguished it from closely related Staphylococcus spp. All analyses have consistently shown that the closest relative is Staphylococcus chromogenes; however, values of digital DNA-DNA hybridization Staphylococcus species. Whole-genome sequencing and expert annotation of the genome revealed the presence of novel variable genetic elements, including two plasmids named pSR9025A and pSR9025B, prophages, genomic islands and a composite transposon that may confer selective advantages to other bacteria and enhance their survival. Based on phenotypic, phylogenetic and genomic data obtained in this study, the strain NRL/St 03/464T (= CCM 9025T = LMG 31873T = DSM 111348T) represents a novel species with the suggested name Staphylococcus ratti sp. nov.

Phthalates are chemicals interfering with the function of testosterone and are suspected to play a role in the emergence of neurodevelopmental diseases. This could be due to interference with brain development for which optimal testosterone levels are essential. We investigated the effect of prenatal and early postnatal exposure to a phthalate mixture on the anogenital distance (AGD), plasma testosterone levels and social behavior in rats. Pregnant rats were exposed to a mixture of diethylhexyl, diisononyl and dibutyl phthalate, each at a dose of 4.5 mg/kg/day, from gestational day 15 to postnatal day 4. A social interaction test was performed to assess sociability in the three ontogenetic stages (weaning, puberty, adulthood). AGD was measured in adulthood to assess changes in prenatal testosterone levels. Plasma testosterone levels were measured in adults by a radioimmunoassay. The total frequency and time of socio-cohesive interactions were decreased in phthalate exposed females in weaning, puberty and adulthood. Phthalate exposed males showed a decrease in the frequency of social interactions in weaning only. Shorter anogenital distance was observed in adult males exposed to phthalates. Decreased testosterone levels were observed in the exposed group in both sexes. Our results suggest that early developmental phthalate exposure may play an important role in the hormonal and behavioral changes associated with several neurodevelopmental diseases. [ABSTRACT FROM AUTHOR]

High rates of cardiovascular mortality have long been a serious problem in all European countries. Despite advancements in health care the situation is not improving fast enough. In the last decades, no new ultra-short-acting β-blockers have been registered in the European Union except for esmolol and landionol. In this study, eight newly-synthesised ultra-short-acting β-blockers were tested. These β-blockers contain an ester functional group which can be easily cleaved by plasma or cytoplasmic esterases. The substances were prepared in the Department of Chemical Drugs, Faculty of Pharmacy, University of Veterinary and Pharmaceutical Sciences, Brno. Systolic blood pressure, heart rate and the interval of the QRS complex were evaluated using normotensive laboratory Wistar rats. The tested compounds were administered intravenously into the vena jugularis during general anaesthesia. The arteria carotis was exposed and cannulated to a Universal Perfusion System Basic Unit (UPSBU) of type Uniper UP-100. The universal perfusion system for isolated organs was capable of measuring and transducing actual values of blood pressure. ECG records were made using the ECG SEIVA - Praktik Veterinary. A series of substances named 2FC2a, 2FC2b, 2FC2c, 2FC2d, and another series with substances named 2FT2a, 2FT2b, 2FT2c, 2FT2d were tested at a dose of 3 mg/kg. Results were statistically compared to placebo. The best results were obtained for propyl and butyl derivatives with the highest lipophilicity. These acted as the best blood pressure reducers immediately after their administration. None of the compounds notably affected the heart rate. Statistical data show that carbamate substitution considerably prolongated the duration of the QRS complex as compared to placebo or etheric substitution. The carbamate substitution caused a pronounced arrhythmogenic effect. Thus, we could confirm the short-term hypotensive effect of the compounds. We observed an effect on the electrical conduction system of the heart while no effects were observed on heart rate. Our study contributes to better describing potential new ultra-short-acting β-blockers and facilitates selection for further testing.

Recent reports from Europe and the USA described Seoul orthohantavirus infection in pet rats and their breeders/owners, suggesting the potential emergence of a “new” public health problem. Wild and laboratory rat-induced Seoul infections have, however, been described since the early eighties, due to the omnipresence of the rodent reservoir, the brown rat Rattus norvegicus. Recent studies showed no fundamental differences between the pathogenicity and phylogeny of pet rat-induced Seoul orthohantaviruses and their formerly described wild or laboratory rat counterparts. The paucity of diagnosed Seoul virus-induced disease in the West is in striking contrast to the thousands of cases recorded since the 1980s in the Far East, particularly in China. This review of four continents (Asia, Europe, America, and Africa) puts this “emerging infection” into a historical perspective, concluding there is an urgent need for greater medical awareness of Seoul virus-induced human pathology in many parts of the world. Given the mostly milder and atypical clinical presentation, sometimes even with preserved normal kidney function, the importance of simple but repeated urine examination is stressed, since initial but transient proteinuria and microhematuria are rarely lacking.

The laboratory rat, widely used in biomedical research, is domesticated from wild brown rat. The origin and genetic mechanism underlying domestication of the laboratory rat remain largely elusive. In the present study, large scale genomes supported a single origin for the laboratory rat, possibly from a sister group to wild rats from Europe/ Africa/Middle East. Genomic and transcriptomic analyses uncovered many artificially selected genes (e.g., FOXP2, B3GAT1, and CLOCK) involved in the nervous system. These genes associate with learning ability and regulation of circadian rhythm, which likely enabled the successful domestication of the laboratory rat. Particularly, many genes, including mitochondrial genes responsible for energy metabolism, displayed a substantially increased expression in the brain of laboratory rats compared with wild rats. Our findings demystify the origin and evolution of this model animal, and provide insight into the process of its domestication. [ABSTRACT FROM AUTHOR]

High rates of cardiovascular mortality have long been a serious problem in all European countries. Despite advancements in health care the situation is not improving fast enough. In the last decades, no new ultra-short-acting β-blockers have been registered in the European Union except for esmolol and landionol. In this study, eight newly-synthesised ultra-short-acting β-blockers were tested. These β-blockers contain an ester functional group which can be easily cleaved by plasma or cytoplasmic esterases. The substances were prepared in the Department of Chemical Drugs, Faculty of Pharmacy, University of Veterinary and Pharmaceutical Sciences, Brno. Systolic blood pressure, heart rate and the interval of the QRS complex were evaluated using normotensive laboratory Wistar rats. The tested compounds were administered intravenously into the vena jugularis during general anaesthesia. The arteria carotis was exposed and cannulated to a Universal Perfusion System Basic Unit (UPSBU) of type Uniper UP-100. The universal perfusion system for isolated organs was capable of measuring and transducing actual values of blood pressure. ECG records were made using the ECG SEIVA - Praktik Veterinary. A series of substances named 2FC2a, 2FC2b, 2FC2c, 2FC2d, and another series with substances named 2FT2a, 2FT2b, 2FT2c, 2FT2d were tested at a dose of 3 mg/kg. Results were statistically compared to placebo. The best results were obtained for propyl and butyl derivatives with the highest lipophilicity. These acted as the best blood pressure reducers immediately after their administration. None of the compounds notably affected the heart rate. Statistical data show that carbamate substitution considerably prolongated the duration of the QRS complex as compared to placebo or etheric substitution. The carbamate substitution caused a pronounced arrhythmogenic effect. Thus, we could confirm the short-term hypotensive effect of the compounds. We observed an effect on the electrical conduction system of the heart while no effects were observed on heart rate. Our study contributes to better describing potential new ultra-short-acting β-blockers and facilitates selection for further testing. [ABSTRACT FROM AUTHOR]

By late 18 th or early 19 th century, albino rats became the most commonly used experimental animals in numerous biomedical researches, as they have been recognized as the preeminent model mammalian system. But, the precise correlation between age of laboratory rats and human is still a subject of debate. A number of studies have tried to detect these correlations in various ways, But, have not successfully provided any proper association. Thus, the current review attempts to compare rat and human age at different phases of their life. The overall findings indicate that rats grow rapidly during their childhood and become sexually mature at about the sixth week, but attain social maturity 5-6 months later. In adulthood, every day of the animal is approximately equivalent to 34.8 human days (i.e., one rat month is comparable to three human years). Numerous researchers performed experimental investigations in albino rats and estimated, in general, while considering their entire life span, that a human month resembles every-day life of a laboratory rat. These differences signify the variations in their anatomy, physiology and developmental processes, which must be taken into consideration while analyzing the results or selecting the dose of any research in rats when age is a crucial factor.

The effect of fluoride on the calcium level in serum was analyzed in the laboratory rat Rattus norvegicus. The control group consisted of 10, and the experimental group of 15 animals. In the experimental group, fluoride at a concentration of 3 mg/100 g body weight of rats was intramuscularly injected into the musculus gluteus maximus. The concentration of calcium was measured by the CPC method. The average serum calcium concentration was 2.46 mmol/l, with female rats having higher values of serum calcium than male rats. Fluoride caused the reduction of calcium concentration in serum (p

The Sox3 gene is considered to be one of the earliest neural markers in vertebrates, playing a role in specifying neuronal fate. Despite the completion of a rat genome sequencing project, only a partial sequence of the rat Sox3 gene has been available in the public database. Using PCR, sequencing, and bioinformatics tools, in this study we have determined the complete coding sequence of the rat Sox3 gene encoding 449 amino acids. Comparative analysis of rat and human SOX3 proteins revealed a high degree of conservation. Identification of the rat Sox3 gene sequence would help in understanding the biological roles of this gene and provide insight into evolutionary relationships with vertebrate orthologs.

Though recent studies have shown that rodents express emotions with their face, whether emotional expression in rodents has a communicative function between conspecifics is still unclear. Here, we demonstrate the ability of visual recognition of emotional expressions in laboratory rats. We found that Long-Evans rats avoid images of pain expressions of conspecifics but not those of neutral expressions. The results indicate that rats use visual emotional signals from conspecifics to adjust their behaviour in an environment to avoid a potentially dangerous place. Therefore, emotional expression in rodents, rather than just a mere ‘expression’ of emotional states, might have a communicative function.

Murine mycoplasmosis is an infection that still represents a challenge to animal testing throughout the world. Mycoplasma pulmonis is the agent of murine respiratory mycoplasmosis, a chronic course disease, slow and persistent throughout the animal's life. The objective of this paper was to give an overview on biological characteristics, disease, diagnostic methods and difficulties for prevention and control of this microorganism. Rats and mice are used worldwide in biological research, and when under sanitary and genetic standardization, provide the researcher important models for understanding of various biological mechanisms. However, these species can be infected by pathogens that, when introduced in the colony, affect production and experimental results. Among the major infections that affect rodents, mycoplasmosis is one of the most important because it produces severe respiratory and reproductive problems, affecting the colony and hindering the obtaining of pathogen-free animals. Even with the advent of equipment such as racks of individually ventilated cages, the occurrence of infection is still 100% in conventional colonies and 3.2% to 20% in colonies maintained under barriers. [ABSTRACT FROM AUTHOR]

This study was carried out to investigate how pinworm infection in rats affects nutrient digestibility in the hosts. Twenty-four male outbred Wistar rats were randomly divided into two groups of 12 rats each. The rats from the first group (GI) were kept in cages with bedding containing pinworm eggs, and the second (control) group (GII) were kept in a separate room in clean, uncontaminated filter-top cages. The animals were put into individual metabolic cages later. Metabolic trials lasted five days and records of animal weight, food ingestion, and faecal weight were taken daily. Based on laboratory analysis of the feed and faecal nutrient content, digestibility values were determined. On day 15 of the experiment, the animals were euthanized. Although Syphacia muris were found in all rats from the GI group, animals exhibited no clinical signs. In our experiment, S. muris infection reduced the overall digestibility of all measured nutrients (P < 0.01). The most significant differences in digestibility were observed in the case of crude fibre and mineral matter (P < 0.01). [ABSTRACT FROM AUTHOR]

By late 18th or early 19th century, albino rats became the most commonly used experimental animals in numerous biomedical researches, as they have been recognized as the preeminent model mammalian system. But, the precise correlation between age of laboratory rats and human is still a subject of debate. A number of studies have tried to detect these correlations in various ways, But, have not successfully provided any proper association. Thus, the current review attempts to compare rat and human age at different phases of their life. The overall findings indicate that rats grow rapidly during their childhood and become sexually mature at about the sixth week, but attain social maturity 5 6 months later. In adulthood, every day of the animal is approximately equivalent to 34.8 human days (i.e., one rat month is comparable to three human years). Numerous researchers performed experimental investigations in albino rats and estimated, in general, while considering their entire life span, that a human month resembles every day life of a laboratory rat. These differences signify the variations in their anatomy, physiology and developmental processes, which must be taken into consideration while analyzing the results or selecting the dose of any research in rats when age is a crucial factor. [ABSTRACT FROM AUTHOR]

Staphylococci from the Staphylococcus intermedius-Staphylococcus hyicus species group include numerous animal pathogens and are an important reservoir of virulence and antimicrobial resistance determinants. Due to their pathogenic potential, they are possible causative agents of zoonoses in humans; therefore, it is important to address the properties of these strains. Here we used a polyphasic taxonomic approach to characterize the coagulase-negative staphylococcal strain NRL/St 03/464T, isolated from the nostrils of a healthy laboratory rat during a microbiological screening of laboratory animals. The 16S rRNA sequence, MALDI-TOF mass spectrometry and positive urea hydrolysis and beta-glucuronidase tests clearly distinguished it from closely related Staphylococcus spp. All analyses have consistently shown that the closest relative is Staphylococcus chromogenes; however, values of digital DNA-DNA hybridization <35.3% and an average nucleotide identity <81.4% confirmed that the analyzed strain is a distinct Staphylococcus species. Whole-genome sequencing and expert annotation of the genome revealed the presence of novel variable genetic elements, including two plasmids named pSR9025A and pSR9025B, prophages, genomic islands and a composite transposon that may confer selective advantages to other bacteria and enhance their survival. Based on phenotypic, phylogenetic and genomic data obtained in this study, the strain NRL/St 03/464T (= CCM 9025T = LMG 31873T = DSM 111348T) represents a novel species with the suggested name Staphylococcus ratti sp. nov. [ABSTRACT FROM AUTHOR]

The laboratory rat, a non-photoperiodic rodent, exhibits seasonal fluctuations of melatonin. Melatonin has been found to be readily transferred from the maternal to the fetal circulation. No data exist on the possible influence of maternal pineal gland upon seasonal variations of the offspring. The aim of the present study was to asses the influence of the maternal melatonin rhythm on the offspring postnatal development of the reproductive hormones LH, FSH and prolactin. Male offspring from control, pinealectomized (PIN-X) and PIN-X + melatonin (PIN-X+MEL) mother Wistar rats were studied at 21, 31, and 60 days of age. Seasonal age-dependent variations were found for all hormones studied in control offspring but PIN-X offspring showed a tendency to have reduced duration or altered seasonal variations. Maternal melatonin treatment to PIN-X mothers partially restored the effect of pinealectomy. The chronological study of LH, FSH, and prolactin in PIN-X offspring also showed an altered pattern as compared to control-offspring. Melatonin treatment to the mothers partially restored the developmental pattern of reproductive hormones. Results of this study indicate that maternal pineal gland of the laboratory rat is involved in the seasonal postnatal development variations of reproductive hormones of the offspring. [ABSTRACT FROM AUTHOR]