Leptospirosis in the Platypus () in Australia: Who Is Infecting Whom?

The platypus () is an amphibious, egg-laying mammal of high conservation value that is found only in Australia. The zoonotic bacterium serovar Hardjo was discovered in platypuses in prior studies, but little is known about its epidemiology. Samples in the Platypus Serum Bank were tested in 2023 and the results were combined with historical records.

Lack of hydroxyurea-associated mutagenesis in pediatric sickle cell disease patients.

Hydroxyurea is approved for treating children and adults with sickle cell anemia (SCA). Despite its proven efficacy, concerns remain about its mutagenic and carcinogenic potential that hamper its widespread use. Cell culture- and animal-based investigations indicate that hydroxyurea's genotoxic effects are due to indirect clastogenicity in select cell types when high dose and time thresholds are exceeded (reviewed by Ware & Dertinger, 2021).

A review of mammalian genotoxicity of hexavalent chromium: implications for oral carcinogenicity risk assessment.

Assessment of genotoxicity is a critical component of mode of action (MOA) analysis and carcinogen risk assessment due to its influence on quantitative risk extrapolation approaches. To date, clear guidance and expert consensus on the determination of a mutagenic MOA remains elusive, resulting in different estimates of carcinogenic risk for the same chemical among different stakeholders. Oral toxicity criteria for hexavalent chromium [Cr(VI)], for example, differ by orders of magnitude due largely to the interpretation of genotoxicity data.

Collaborating With Parks and Recreation Departments to Address Youth Health.

Adolescence is an important time for addressing health, including mental health, obesity, substance use, and food insecurity. As the myriad health and wellness needs of community members expands, it becomes increasingly difficult for one profession alone to address these needs. The park and recreation field was founded to address the health and wellness needs of people, and much of their programming is focused on youth.

Bruce Nathan Ames - Paradigm shifts inside the cancer research revolution.

Dr. Bruce Ames turned 92 on December 16, 2020. He considers his most recent work linking adequate consumption of 30 known vitamins and minerals with successful aging to be his most important contribution.

Assessment of systemic genetic damage in pediatric inflammatory bowel disease.

The etiology of distal site cancers in inflammatory bowel disease (IBD) is not well understood and requires further study. We investigated whether pediatric IBD patients' blood cells exhibit elevated levels of genomic damage by measuring the frequency of mutant phenotype (CD59-/CD55-) reticulocytes (MUT RET) as a reporter of PIG-A mutation, and the frequency of micronucleated reticulocytes (MN-RET) as an indicator of chromosomal damage. IBD patients (n = 18 new-onset disease, 46 established disease) were compared to age-matched controls (constipation or irritable bowel syndrome patients from the same clinic, n = 30) and young healthy adults age 19-24 (n = 25).

Human blood PIG-A mutation and micronucleated reticulocyte flow cytometric assays: Method optimization and evaluation of intra- and inter-subject variation.

We previously described flow cytometry-based methods for scoring the incidence of micronucleated reticulocytes (MN-RET) and PIG-A mutant phenotype reticulocytes (MUT RET) in rodent and human blood samples. The current report describes important methodological improvements for human blood analyses, including immunomagnetic enrichment of CD71-positive reticulocytes prior to MN-RET scoring, and procedures for storing frozen blood for later PIG-A analysis. Technical replicate variability in MN-RET and MUT RET frequencies based on blood specimens from 14 subjects, intra-subject variability based on serial blood draws from 6 subjects, and inter-subject variation based on up to 344 subjects age 0 to 73 years were quantified.

3Rs friendly study designs facilitate rat liver and blood micronucleus assays and Pig-a gene mutation assessments: Proof-of-concept with 13 reference chemicals.

Regulatory guidance documents stress the value of assessing the most appropriate endpoints in multiple tissues when evaluating the in vivo genotoxic potential of chemicals. However, conducting several independent studies to evaluate multiple endpoints and/or tissue compartments is resource intensive. Furthermore, when dependent on visual detection, conventional approaches for scoring genotoxicity endpoints can be slow, tedious, and less objective than the ideal.

A novel Ehrlichia species in blood and Ixodes ornithorhynchi ticks from platypuses (Ornithorhynchus anatinus) in Queensland and Tasmania, Australia.

Worldwide, Ehrlichia spp. are emerging infectious organisms of domestic animals and people, however, most Ehrlichia spp. naturally infect wildlife reservoirs causing mainly asymptomatic infections.

Enabling spontaneous analogy through heuristic change.

Despite analogy playing a central role in theories of problem solving, learning and education, demonstrations of spontaneous analogical transfer are rare. Here, we present a theory of heuristic change for spontaneous analogical transfer, tested in four experiments that manipulated the experience of failure to solve a source problem prior to attempting a target problem. In Experiment 1, participants solved more source problems that contained an additional financial constraint designed to signal the inappropriateness of moves that maximized progress towards the goal.

In vivo pig-a and micronucleus study of the prototypical aneugen vinblastine sulfate.

The Pig-a assay is being used in regulatory studies to evaluate the potential of agents to induce somatic cell gene mutations and an OECD test guideline is under development. A working group involved with establishing the guideline recently noted that representative aneugenic agents had not been evaluated, and to help fill this data gap Pig-a mutant phenotype and micronucleated reticulocyte frequencies were measured in an integrated study design to assess the mutagenic and cytogenetic damage responses to vinblastine sulfate exposure. Male Sprague Dawley rats were treated for twenty-eight consecutive days with vinblastine dose levels from 0.

A NEED FOR DYNAMIC HEMATOLOGY AND SERUM BIOCHEMISTRY REFERENCE TOOLS: NOVEL USE OF SINE WAVE FUNCTIONS TO PRODUCE SEASONALLY VARYING REFERENCE CURVES IN PLATYPUSES (ORNITHORHYNCHUS ANATINUS).

Seasonal changes in hematology and serum biochemistry results, described by separate reference intervals for different seasons, have been reported in many animals. We developed a novel method to investigate seasonal variation in values and a reference tool (the reference curve) based on sine wave functions that, for suitable variables, represents data more appropriately than a fixed reference interval. We applied these techniques to values observed in blood samples from 126 adult wild platypuses ( Ornithorhynchus anatinus ; 58 females and 68 males).

INVESTIGATION INTO INDIVIDUAL HEALTH AND EXPOSURE TO INFECTIOUS AGENTS OF PLATYPUSES (ORNITHORHYNCHUS ANATINUS) IN TWO RIVER CATCHMENTS IN NORTHWEST TASMANIA.

Changes in the health of individuals within wildlife populations can be a cause or effect of population declines in wildlife species. Aspects of individual platypus ( Ornithorhynchus anatinus ) health have been reported. However, holistic studies investigating potential synergistic effects of both pathogens and environmental factors are needed to expand understanding of platypus individual health.

Dermatophilus congolensis Infection in Platypus ( Ornithorhynchus anatinus ), Tasmania, Australia, 2015.

We report disease due to Dermatophilus congolensis infection in three of 13 (23%) platypuses ( Ornithorhynchus anatinus ) from a catchment in Tasmania, Australia. This pathogen has not previously been reported in platypuses. Two of the three infected platypuses had extensive scab formations, but no substantial hair loss was apparent.

First Molecular Characterization of Theileria ornithorhynchi Mackerras, 1959: yet Another Challenge to the Systematics of the Piroplasms.

Piroplasms, tick-transmitted Apicomplexa of the genera Theileria, Babesia and Cytauxzoon, are blood-borne parasites of clinical and veterinary importance. The order Piroplasmida shows a puzzling systematics characterized by multiple clades, soft polytomies and paraphyletic/polyphyletic genera. In the present study, screening of platypuses (Ornithorhynchus anatinus), was performed to infer the parasite molecular phylogeny.

Mouse Pig-a and micronucleus assays respond to N-ethyl-N-nitrosourea, benzo[a]pyrene, and ethyl carbamate, but not pyrene or methyl carbamate.

This laboratory previously described a method for scoring the incidence of peripheral blood Pig-a mutant phenotype rat erythrocytes using immunomagnetic separation in conjunction with flow cytometric analysis (In Vivo MutaFlow®). The current work extends the method to mouse blood, using the frequency of CD24-negative reticulocytes (RET(CD24-)) and erythrocytes (RBC(CD24-)) as phenotypic reporters of Pig-a gene mutation. Following assay optimization, reconstruction experiments demonstrated the ability of the methodology to return expected values.

Effects of cluster location and cluster distribution on performance on the traveling salesman problem.

Research on human performance in solving traveling salesman problems typically uses point sets as stimuli, and most models have proposed a processing stage at which stimulus dots are clustered. However, few empirical studies have investigated the effects of clustering on performance. In one recent study, researchers compared the effects of clustered, random, and regular stimuli, and concluded that clustering facilitates performance (Dry, Preiss, & Wagemans, 2012).

IWGT report on quantitative approaches to genotoxicity risk assessment II. Use of point-of-departure (PoD) metrics in defining acceptable exposure limits and assessing human risk.

This is the second of two reports from the International Workshops on Genotoxicity Testing (IWGT) Working Group on Quantitative Approaches to Genetic Toxicology Risk Assessment (the QWG). The first report summarized the discussions and recommendations of the QWG related to the need for quantitative dose-response analysis of genetic toxicology data, the existence and appropriate evaluation of threshold responses, and methods to analyze exposure-response relationships and derive points of departure (PoDs) from which acceptable exposure levels could be determined. This report summarizes the QWG discussions and recommendations regarding appropriate approaches to evaluate exposure-related risks of genotoxic damage, including extrapolation below identified PoDs and across test systems and species.

IWGT report on quantitative approaches to genotoxicity risk assessment I. Methods and metrics for defining exposure-response relationships and points of departure (PoDs).

This report summarizes the discussion, conclusions, and points of consensus of the IWGT Working Group on Quantitative Approaches to Genetic Toxicology Risk Assessment (QWG) based on a meeting in Foz do Iguaçu, Brazil October 31-November 2, 2013. Topics addressed included (1) the need for quantitative dose-response analysis, (2) methods to analyze exposure-response relationships & derive point of departure (PoD) metrics, (3) points of departure (PoD) and mechanistic threshold considerations, (4) approaches to define exposure-related risks, (5) empirical relationships between genetic damage (mutation) and cancer, and (6) extrapolations across test systems and species. This report discusses the first three of these topics and a companion report discusses the latter three.

Induction of Pig-a mutant erythrocytes in male and female rats exposed to 1,3-propane sultone, ethyl carbamate, or thiotepa.

Validation of the Pig-a gene mutation assay has been based mainly on studies in male rodents. To determine if the mutagen-induced responses of the X-linked Pig-a gene differ in females compared to males, groups of five male and female Sprague Dawley rats were exposed to the mutagens 1,3-propane sultone (80mg/kg/day), ethyl carbamate (600mg/kg/day), or thiotepa (7.5mg/kg/day) for three consecutive days (study days 1-3).

Rat Pig-a mutation assay responds to the genotoxic carcinogen ethyl carbamate but not the non-genotoxic carcinogen methyl carbamate.

Determination of the mode of action of carcinogenic agents is an important factor in risk assessment and regulatory practice. To assess the ability of the erythrocyte-based Pig-a mutation assay to discriminate between genotoxic and non-genotoxic modes of action, the mutagenic response of Sprague Dawley rats exposed to methyl carbamate (MC) or ethyl carbamate (EC) was investigated. EC, a potent carcinogen, is believed to induce DNA damage through the formation of a DNA-reactive epoxide group, whereas the closely structurally related compound, MC, cannot form this epoxide and its weaker carcinogenic activity is thought to be secondary to inflammation and promotion of cell proliferation.

Comparison of male versus female responses in the Pig-a mutation assay.

Validation of the Pig-a gene mutation assay has been based mainly on studies in male rodents. To determine if the mutagen-induced responses of the X-linked Pig-a gene differ in females compared to males, 7- or 14-week old male and female Sprague Dawley rats were exposed to N-ethyl-N-nitrosourea (ENU). In the study with the 7-week old rats, exposure was to 0, 1, 5 or 25mg ENU/kg/day for three consecutive days (study Days 1-3).

Human erythrocyte PIG-A assay: an easily monitored index of gene mutation requiring low volume blood samples.

This laboratory has previously described a method for scoring the incidence of rodent blood Pig-a mutant phenotype erythrocytes using immunomagnetic separation in conjunction with flow cytometric analysis (In Vivo MutaFlow®). The current work extends this approach to human blood. The frequencies of CD59- and CD55-negative reticulocytes (RET(CD59-/CD55-)) and erythrocytes (RBC(CD59-/CD55-)) serve as phenotypic reporters of PIG-A gene mutation.

Novel genotypes of Trypanosoma binneyi from wild platypuses (Ornithorhynchus anatinus) and identification of a leech as a potential vector.

Little is known about the prevalence and pathogenesis of trypanosomes in Australian monotremes, and few genetic characterisation studies have been conducted with these haemoparasites. During the present investigation, molecular and microscopic methods were used to screen peripheral blood (n=28) and ectoparasites (n=10 adult ticks; n=5 tick nymphs; n=1 leech; and n>500 tick eggs) collected from wild Tasmanian platypuses (Ornithorhynchus anatinus), for the presence of trypanosomatid-specific DNA and/or trypomastigotes. The genes for the small ribosomal subunit RNA (18S rDNA) and glycosomal glyceraldehyde phosphate dehydrogenase (gGAPDH) were amplified and sequenced, prior to conducting phylogenetic analyses.