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Platypuses are the world's most evolutionarily distinct mammal and have several host-specific ecto- and endoparasites. With platypus populations declining, consideration should also be given to preserving these high conservation priority parasites alongside their charismatic host. A disease risk analysis (DRA) was performed for a platypus conservation translocation, using a modified streamlined methodology that incorporated a parasite conservation framework. DRA frameworks rarely consider parasite conservation. Rather, parasites are typically considered myopically in terms of the potential harm they may cause their host. To address this, a previously proposed parasite conservation framework was incorporated into an existing streamlined DRA methodology. Incorporation of the two frameworks was achieved readily, although there is opportunity for further refinement of this process. This DRA is significant as it is the first performed for any monotreme species, and implements the emerging approach of balancing the health and disease risk of the host with parasite conservation. [Display omitted] • First disease risk analysis (DRA) performed for a monotreme species. • Incorporates a parasite conservation framework and a streamlined DRA methodology. • Real-world example considering both host health and parasite conservation. • Consideration of host-specific platypus parasites as high conservation value. [ABSTRACT FROM AUTHOR]

The busy beaver problem is a well-known example of a non-computable function. In order to determine a particular value of this function, it is necessary to generate and classify a large number of Turing machines. The advent of cloud computing provides unparallelled opportunities to explore this problem, but also to develop infrastructures that support distributed investigations and relevant computational evidence for all results obtained, such as a list of all machines of a given size together with their classifications. This list can then be used for variants of the problem or related ones such as the placid platypus problem. We investigate how to generate classes of machines to be considered for the busy beaver problem, which involves separating the generation of machines from their analysis. We discuss the relationship between quadruple and quintuple variants of Turing machines, and show that the latter are more general than the former. We give some formal results to justify our strategy for minimising the number of machines generated, and define a process reflecting this strategy for generating machines. We describe our implementation, and the results of generating various classes of machines with up to 5 states or up to 5 symbols, all of which (together with our code) are available on the author's website. • Generation of machines to compute the busy beaver function needs careful analysis. • Formal results justifying the soundness of a specific strategy for machine generation. • Devise procedure to generate minimal number of machines. • Provide empirical results and links to code and output data. [ABSTRACT FROM AUTHOR]

The soft epidermis of mammals derives from the accumulation of keratohyaline granules in the granular layer, before maturing into corneocytes. Main proteins accumulated in the granular layer are pro-filaggrin and filaggrin that determine keratin clumping and later moisturization of the stratum corneum that remains flexible. This soft epidermis allows the high sensitivity of mammalian skin. Presence and thickness of the stratum granulosum varies among different species of mammals and even between different body regions of the same animal, from discontinuous to multilayered. These variations are evident using antibodies for filaggrin, a large protein that share common epitopes among placentals. Here we have utilized filaggrin antibodies (8959 and 466) and an acidic keratin antibody (AK2) for labeling placental, marsupial and monotreme epidermis. AK2 labeling appears mainly to detect K24 keratin, and less likely other acidic keratins. Immunoreactivity for filaggrin is absent in platypus, discontinuous in Echidna and in the tested marsupials. In placentals, it is inconstantly or hardly detected in the thin epidermis of bat, rodents, and lagomorphs with a narrow, mono-stratified and/or discontinuous granular layer. In contrast, where the granular layer is continuous or even stratified, both filaggrin and AK2 antibodies decorate granular cells. The ultrastructural analysis using the AK2 antibody on human epidermis reveals that a weak labeling is associated with keratohyalin granules and filamentous keratins of transitional keratinocytes and corneocytes. This observation suggests that basophilic filaggrin interacts with acidic keratins like K24 and determines keratin condensation into corneocytes of the stratum corneum. • Filaggrin and keratin interaction contributes to corneous layer formation in mammalian epidermis. • Filaggrin and keratins distribution in the epidermis has been studied in numerous species. • Immunolabeling detects an acidic type I keratin in the granular-pre corneous layer. • Immunolabeling also detected basic filaggrins in the granular-pre corneous layer. • Initial cornification in mammalian epidermis occurs through acidic-basic interactions. [ABSTRACT FROM AUTHOR]

The use of duckbill valves in submerged outfalls for dense effluents is now prevalent to prevent the intrusion of ambient water into the outfall pipe during periods of low production of the facility. In the present study, an experimental investigation was conducted using the technique of Planar Laser Induced Fluorescence (PLIF) to examine the mixing characteristics of 45° inclined dense jets from a duckbill shape nozzle in co-flowing currents. The measured characteristics included the jet trajectory, concentration decay, centreline peak dilution and cross-sectional concentration distribution. The Froude number ranged from 10 to 25, and the nominal Froude number from 0.2 to 3.0. Two mounting orientations of the duckbill nozzle, namely vertical and horizontal, were also investigated. The experimental results showed that two regimes, namely dense-jet- and co-flow-dominated, can be clearly observed. When the co-flow velocity increases, the centreline peak height and dilution of the inclined dense jet decrease. Comparing to the available results in the literature for inclined circular dense jets, the centreline peak dilution for inclined duckbill dense jets is generally higher. In other words, the installation of the duckbill valve also contributes to the mixing of the dense effluent with surrounding ambient waters, in addition to preventing the ambient intrusion. With respect to the mounting orientation, the horizontal induces a relatively higher dilution but also a larger centreline peak height. Thus, the horizontal orientation would be preferable when the cover water depth is sufficient, while the vertical orientation can be considered in shallow waters for full submergence. [ABSTRACT FROM AUTHOR]

The increased consumption of plastics worldwide, has led to the emergence of nanoplastics as important environmental pollutants. Despite the presence of nanoplastics in aquatic environments, their effects on ecosystems remain largely unexplored due to the analysis complexity. This study investigated the organ accumulation and toxic effects of 50 nm polystyrene nanoplastics (PS-NPs) in Zacco platypus (Z. platypus ; also known as pale chub fish) using pyrolyzer-gas chromatography-mass spectrometry (Pyr-GC/MS). PS-NPs accumulated in Z. platypus ' brain, digestive tract, branchia, and liver, causing changes at cellular level. Over a 14-day exposure, the accumulated PS-NPs led to observable changes in fish behavior (e.g., Total traveled distance and maximum velocity). In addition, the oxidative stress in each organ of Z. platypus increased as the exposure concentration of PS-NPs increased. This study shows that accumulation of nanoplastics in fish, resulting in behavioral changes and biochemical toxicity. As the pattern of change magnifies with exposure time and concentration, from a long-term perspective, the influence of nanoplastics on aquatic ecosystems become evident. This underscores the urgency for continuous research into the potential risks of nanoplastics in aquatic ecosystems. [Display omitted] • Accumulation of Polystyrene nanoplastics (PS-NPs) in Zacco platypus tissue. • Zacco platypus exposed to PS-NPs exhibited histopathological changes. • PS-NPs exposure induced behavioral changes and oxidative stress in Zacco platypus. [ABSTRACT FROM AUTHOR]

Fire plays an important role in many ecosystems, but megafires are increasing the area burnt in forested regions globally. The 2019–2020 megafires in south-eastern Australia were unprecedented with respect to area burnt and the spatial extent of high-severity fire. Yet, there is limited knowledge regarding the impact of these megafires on biodiversity, especially aquatic fauna. Here we investigate the impact of the 2019–2020 megafires on the distribution of a semi-aquatic monotreme thought to be in decline: the platypus, Ornithorhynchus anatinus. We leveraged extensive pre-fire environmental DNA (eDNA) sampling and coupled this with additional sampling at two timepoints post-fire, to conduct a Before-After-Control-Impact (BACI) study. We used site occupancy-detection modelling to estimate platypus occupancy across fire affected and non-fire affected sites over time as well as the interaction between occupancy, high rainfall, and fire severity. We detected a negative effect of fire presence on platypus occupancy in both post-fire time periods. Platypus occupancy was also predicted to be lower at sites that experienced high rainfall post-fire and were situated within watersheds that had a large proportion burnt at high-severity. With area burnt and the extent of high-severity fire increasing globally, and predictions of more extreme rainfall events in south-eastern Australia in the future, the impact of fire on aquatic fauna requires greater consideration in post-fire assessments and biodiversity management more generally. The use of eDNA sampling and detection methods in a BACI framework provides a promising means to fill these knowledge gaps but does require pre-emptive sampling. [ABSTRACT FROM AUTHOR]

• Monotremes have a lower cortical white matter volume compared to therians. • This suggests fewer cortical association fibres in monotremes compared to therians. • Cortical white matter is shifted caudally in the platypus and long-beaked echidna. • Forebrain structure in monotremes suggests convergence with myrmecophagous xenarthrans. We have made quantitative volumetric analyses of cerebral cortical (pallial) structures in the brains of three species of monotreme (Ornithorhynchus anatinus , Tachyglossus aculeatus , Zaglossus bruijni) and compared the findings with similar measurements in a range of therian mammals (6 marsupials and 50 placentals). We have found that although the iso- and periallocortical grey matter volume of the monotremes is about what would be expected for their brain size, the proportion of iso- and periallocortical white matter in monotremes is substantially lower than that in the forebrains of therians. This suggests that the forebrains of the three monotremes have fewer association, commissural and/or projection connections than those of similarly sized forebrains of therian mammals. We also found that the iso- and periallocortex of the platypus is relatively smooth-surfaced compared to similarly sized brains of therian mammals, with a distinct caudal shift in the positioning of cortical white matter in the forebrain, consistent with expansion of the posterior thalamic radiation. Central laminated olfactory structures (anterior olfactory nucleus and piriform cortex) are large in the tachyglossid monotremes (Tachyglossus aculeatus and Zaglossus bruijni) and large in xenarthran placental mammals, suggesting convergence of the forebrain structure of monotreme formivores with that of similarly specialized therians like the xenarthrans Myrmecophaga tridactyla and Dasypus novemcinctus. [ABSTRACT FROM AUTHOR]

Environmental DNA (eDNA) sampling—the detection of intra- or extra-cellular DNA in environmental samples—is a rapid and sensitive survey method for detecting aquatic species. Single-species detection methods (typically based on PCR or LAMP) have been shown to be more sensitive for detecting target species than multi-species detection methods, such as metabarcoding. However, previous studies have generally only compared these two eDNA detection approaches for a single target species and have used different methodological and statistical approaches. Here we present a comparison of single- and multi-species eDNA detection methods, drawing on two published case studies (one fish, one amphibian) and two new extensive datasets on a freshwater mammal (the platypus). To ensure consistent conclusions regarding the sensitivity of each eDNA method, we use the same hierarchical site occupancy-detection model for each dataset, incorporating uncertainty at the site, water sample, and technical replicate level. Overall, qPCR achieved higher detection probabilities than metabarcoding across species and datasets. However, differences in sensitivity between detection methods varied depending on methodological decisions concerning what constitutes a true positive detection (i.e., qPCR and metabarcoding thresholds). The decision as to which eDNA detection method to use should always be influenced by the study aims, but our results suggest that single-species detection methods based on qPCR may be preferable when the aim is to achieve a high detection probability for target species. • A hierarchical Bayesian approach to consistently compare eDNA detection methods. • Detection probability was compared between qPCR and metabarcoding. • qPCR was more sensitive compared to metabarcoding across 3 species and 4 study designs. • Methodological decisions such as thresholds impacted detection probability. • There are trade-offs between the need for multi-species information and sensitivity. [ABSTRACT FROM AUTHOR]

Worldwide, Ehrlichia spp. are emerging infectious organisms of domestic animals and people, however, most Ehrlichia spp. naturally infect wildlife reservoirs causing mainly asymptomatic infections. Australian ecosystems have been under-explored for these potentially pathogenic organisms, and recent studies have identified a range of novel Ehrlichia , and their sister genera, Anaplasma and ‘Candidatus Neoehrlichia’ species, from native Australian ticks. We used bacterial 16S rRNA (16S) next-generation sequencing and genus-specific PCR to profile the bacterial communities in platypus ( Ornithorhynchus anatinus ) blood samples and platypus ticks ( Ixodes ornithorhynchi ), and identified a high prevalence of Ehrlichia sequences. We also observed Ehrlichia -like intra-neutrophilic inclusions (morulae) in PCR-positive stained platypus blood films that were consistent in morphology with other Ehrlichia spp. Bayesian phylogenetic analysis of 16S (1343 bp), gltA (1004 bp), and g roEL (1074 bp) gene sequences group the platypus Ehrlichia with ‘ Candidatus Ehrlichia khabarensis’ from far-eastern Russia, and demonstrate that the platypus Ehrlichia is clearly distinct from all other Ehrlichia spp. Enough genetic divergence exists to delineate this platypus Ehrlichia as a separate species that we propose to designate ‘ Candidatus Ehrlichia ornithorhynchi’. There is no evidence that ‘ Candidatus Ehrlichia ornithorhynchi’ causes disease in wild platypuses, however, the organism does seem to be widespread in Australia, being found in both Queensland and Tasmania. ‘ Candidatus Ehrlichia ornithorhynchi’ is the second native Australian Ehrlichia described and adds to the rapidly growing diversity of recently described native Australian tick-borne bacteria. [ABSTRACT FROM AUTHOR]

Every year, more and more discoveries of photoluminescence in different mammal species are made. The more recent cases thus far have been in duck-billed platypus (Ornithorhyncus anatinus), New World squirrels (Glaucomys spp.) and springhare (Pedetidae). Now we can add another species to the list: the garden dormouse (Eliomys quercinus), an endemic rodent to Europe, currently categorized as Near Threatened (NT) by the IUCN. The fluorescence was described and compared qualitatively in museum specimens, deceased and hibernating animals. The feet and nose of the hibernating dormouse displayed greenish-blue photoluminescence under UV light through a yellow filter, whereas the fur was bright red. The live animal had more vivid red colouring than the museum specimen. The fading and changing of the colour and brightness of photoluminescence was observed in a recently deceased animal and even more strongly in museum specimens. [Display omitted] • Photoluminescence found in garden dormouse. • Red and greenish-blue fluorescence in garden dormouse museum specimens, deceased and live animals. • Hibernating garden dormouse has the brightest red fluorescence. • Over time, fluorescence fades in garden dormouse. [ABSTRACT FROM AUTHOR]

Chlorine (Cl 2) is a disinfectant often used in swimming pools and water treatment facilities. However, it is released into aquatic ecosystems, where it may harm non-targeted organisms. Here, we performed a mesocosm experiment exposing Zacco platypus (Z. platypus) to biocide Cl 2 for 30 days (30 d) at two days' time points 15 days (15 d) and 30 d samples were collected. Here, Z. platypus was exposed to a sublethal concentration (0.1 mg/L) of Cl 2 , and comparative transcriptomics analyses were performed to determine their response mechanisms at the molecular level. According to RNA sequencing of the whole-body transcriptome, 860 and 1189 differentially expressed genes (DEGs) were identified from the 15 d and 30 d responses to Cl 2 , respectively. After enrichment analysis of GO (Gene Ontology) functions and KEGG (Kyoto Encyclopedia of Genes and Genomes) pathways, identified DEGs were demonstrated to be associated with a variety of functions, including "ion binding and transmembrane transporters". Cl 2 also induced oxidative stress in Z. platypus by increasing the levels of reactive oxygen species (ROS) while decreasing the catalase (CAT) content and the levels of solute carrier family 22 member 11 (slc22a11), Caspase-8 (casp-8), inducible nitric oxide synthase (NOS2), cytosolic phospholipase A2 gamma (PLA2G4). However, Z. platypus still allows recovery during stress suspension by increasing the expression levels of solute carrier family proteins. The GO and KEGG annotation results revealed that the expression of DEGs were related to the detoxification process, immune response, and antioxidant mechanism. Additionally, protein-protein interaction networks (PPI) and cytoHubba analyses identified sixteen hub genes and their interaction. These findings elucidate the regulation of various DEGs and signaling pathways in response to Cl 2 exposure, which will improve our knowledge and laid foundation for further investigation of the toxicity of Cl 2 to Z. platypus. [Display omitted] • Mesocosm exposure of Zacco platypus to chlorine triggered the induction of ROS. • Antioxidant enzyme activities were adversely affected by the exposure. • Toxicity of chlorine was evaluated by transcriptomics analysis. • Majority of transcriptomic responses included detoxification process, immune response, and antioxidant mechanism. • 16 hub genes were identified through CytoHubba analysis. [ABSTRACT FROM AUTHOR]

Many astronomers seem to believe that we have discovered that Pluto is not a planet. I contest this assessment. Recent discoveries of trans-Neptunian Pluto-sized objects do not militate for Pluto's expulsion from the planets unless we have prior reason for not simply counting these newly-discovered objects among the planets. I argue that this classificatory controversy — which I compare to the controversy about the classification of the platypus — illustrates how our classificatory practices are laden with normative commitments of a distinctive kind. I conclude with a discussion of the relevance of such “norm-ladenness” to other controversies in the metaphysics of classification, such as the monism/pluralism debate. [ABSTRACT FROM AUTHOR]

• We analyze the distribution and variation of P-SSR in 81 mammals of 13 orders. • Our results explain the contribution of SSR to mammalian evolution to some extent. • The number of SSRs decreased with the increase of repetition times. • The proportion and dominant repeat units of different P-SSRs varied among mammals. • Signal transduction played an important role in mammalian life activities. As a classical molecular marker, microsatellite (simple sequence repeat, SSR) has been widely used in the study of genetics and evolution of mammals. However, there are widespread problems about lack of comparative analysis and low quality of genomic data. Based on high-quality chromosome-level genomes, we compared the SSR distribution patterns of 81 mammals species belonging to 13 orders in evolution landscape. In this study, the number of SSRs decreased with the increase of repetition times, and the terminal of exon/intron were enrichment areas of SSRs. We also found that the proportion and dominant repeat units of each type of P-SSR varied among mammalian branches, which could become the evolutionary dynamics for them to adapt to diverse environmental pressures. In particular, the phylogenetic PCA results demonstrated the particularity of some mammals (Tachyglossus aculeatus and Ornithorhynchus anatinus) in evolutionary status, which was consistent with morphological cognition. Meanwhile, there were significant differences in the GC content of each category of P-SSR across mammalian taxa. Besides, the CVs (coefficient of variations) of the RCNs of trinucleotide and hexanucleotide P-SSRs were at a low level in the exon regions, while the dinucleotide or tetranucleotide P-SSRs were at a high level. Furthermore, the results of functional annotation showed that signal transduction played a pivotal role in mammalian biological activities. In conclusion, our research will help to improve the characteristic information of mammalian SSRs and explore their evolutionary background. [ABSTRACT FROM AUTHOR]

The platypus ( Ornithorhynchus anatinus ) is known to be vulnerable to drowning in enclosed traps used to capture freshwater crayfish such as yabbies ( Cherax spp.). To help quantify the degree of risk posed by such traps, we carried out 113 trials in Victorian streams and larger New South Wales rivers to assess the platypus’s ability to escape from standard opera house traps (OH), a second commercially available enclosed trap design (closed-top pyramid traps, CTP), and opera house traps that had been modified by adding an opening in the roof (MOH). All 10 of the animals tested in OH failed to find an exit in the period allowed. In contrast, 82% of subjects tested in CTP ( n = 45) and 83% of those tested in MOH ( n = 58) escaped from traps within 2 min. Victorian animals took significantly less time to escape from traps (CTP, mean = 31 s; MOH, 33 s) than those tested in New South Wales (CTP, mean = 55 s; MOH, 53 s). In addition, juveniles were less likely than adults to escape from CTP and MOH in a timely manner. The results of trials comparing the number and size of yabbies captured in Victorian farm ponds indicate that MOH should at least equal and potentially exceed the performance of OH when used to harvest yabbies for human consumption. [ABSTRACT FROM AUTHOR]

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. DNA was extracted from blood, ectoparasites and tick eggs and the 18S rRNA– hsp 70–genes were used for the phylogenetic reconstructions. Microscopic analyses detected pleomorphic intra-erythrocytic organisms and tetrads consistent with previous descriptions of Theileria ornithorhynchi Mackerras, 1959, but observation of possible schizonts could not be confirmed. DNA sequences obtained from blood and ticks allowed resolving the systematics of the first piroplasm infecting a monotreme host. Molecularly, T. ornithorhynchi formed a novel monophyletic group, basal to most known piroplasms’ clades. The ancestral position of this clade, isolated from an ancient lineage of mammalian host appears particularly fascinating. The present paper discusses the inadequacies of the current molecular systematics for the Piroplasmida and the consequences of incomplete sampling, morphology-based classification and ambiguous microscopic identifications. Likely when the current sampling bias is rectified and more sequence data is made available, the phylogenetic position of T. ornithorhynchi will be further contextualized without ambiguity. [ABSTRACT FROM AUTHOR]

Platypus ( Ornithorhynchus anatinus ) holds a unique phylogenetic position at the base of the mammalian lineage due to an amalgamation of mammalian and sauropsid-like features. Here we describe the set of four lamin genes for platypus. Lamins are major components of the nuclear lamina, which constitutes a main component of the nucleoskeleton and is involved in a wide range of nuclear functions. Vertebrate evolution was accompanied by an increase in the number of lamin genes from a single gene in their closest relatives, the tunicates and cephalochordates, to four genes in the vertebrate lineage. Of the four genes the LIII gene is characterized by the presence of two alternatively spliced CaaX-encoding exons. In amphibians and fish LIII is the major lamin protein in oocytes and early embryos. The LIII gene is conserved throughout the vertebrate lineage, with the notable exception of marsupials and placental mammals, which have lost the LIII gene. Here we show that platypus has retained an LIII gene, albeit with a significantly altered structure and with a radically different expression pattern. The platypus LIII gene contains only a single CaaX-encoding exon and the head domain together with coil 1a and part of coil1b of the platypus LIII protein is replaced by a novel short non-helical N-terminus. It is expressed exclusively in the testis. These features resemble those of male germ cell-specific lamins in placental mammals, in particular those of lamin C2. Our data suggest (i) that the specific functions of LIII, which it fulfills in all other vertebrates, is no longer required in mammals and (ii) once it had been freed from these functions has undergone structural alterations and has adopted a new functionality in monotremes. [ABSTRACT FROM AUTHOR]

The platypus and echidna are the only extant species belonging to the clade of monotremata, the most basal mammalian lineage. The platypus is particularly well known for its mix of mammalian and reptilian characteristics and work in recent years has revealed this also extends to the genetic level. Amongst the monotreme specific features is the unique multiple sex chromosome system (5X4Y in the echidna and 5X5Y in the platypus), which forms a chain in meiosis. This raises questions about sex chromosome organisation at meiosis, including whether there has been changes in genes coding for synaptonemal complex proteins which are involved in homologous synapsis. Here we investigate the key structural components of the synaptonemal complex in platypus and echidna, synaptonemal complex proteins 1, 2 and 3 ( SYCP1 , SYCP2 and SYCP3 ). SYCP1 and SYCP2 orthologues are present, conserved and expressed in platypus testis. SYCP3 in contrast is highly diverged, but key residues required for self-association are conserved, while those required for tetramer stabilisation and DNA binding are missing. We also discovered a second SYCP3- like gene ( SYCP3 -like) in the same region. Comparison with the recently published Y-borne SYCP3 amino acid sequences revealed that SYCP3Y is more similar to SYCP3 in other mammals than the monotreme autosomal SYCP3. It is currently unclear if these changes in the SYCP3 gene repertoire are related to meiotic organisation of the extraordinary monotreme sex chromosome system. [ABSTRACT FROM AUTHOR]

Previously I demonstrated that the slow wave sleep (SWS) functioned to adjust the emotional balance disrupted by emotional memories randomly accumulated during waking, while the rapid eye movement (REM) sleep played the opposite role. Many experimental results have unambiguously shown that various emotional memories are processed during REM sleep. In this article, it is attempted to combine this confirmed function of REM sleep with the atonic state unique to REM sleep, and to integrate a new theory suggesting that improvement of muscular efficiency be a new function of REM sleep. This new function of REM sleep is more advantageous than the function of REM sleep in emotional memories and disinhibited drives to account for the phylogenetic variations of REM sleep, especially the absence of REM sleep in dolphins and short duration of REM sleep in birds in contrary to that in humans and rodents, the absence of penile erections in REM sleep in armadillo, as well as the higher voltage in EEG during REM sleep in platypus and ostrich. Besides, this new function of REM sleep is also advantageous to explain the association of REM sleep with the atonic episodes in SWS, the absence of drastic menopausal change in duration of REM sleep, and the effects of ambient temperature on the duration of REM sleep. These comparative and experimental evidences support the improvement of muscular efficiency as a new and major function of REM sleep. [ABSTRACT FROM AUTHOR]

Background Dynamics in haemoglobin from platypus ( Ornithorhynchus anatinus ), chicken ( Gallus gallus domesticus ) and saltwater crocodile ( Crocodylus porosus ) were measured to investigate response of conformational motions on the picosecond time scale to naturally occurring variations in the amino acid sequence of structurally identical proteins. Methods Protein dynamics was measured using incoherent quasielastic neutron scattering. The quasielastic broadening was interpreted first with a simple single Lorentzian approach and then by using the Kneller–Volino Brownian dynamics model. Results Mean square displacements of conformational motions, diffusion coefficients of internal dynamics and residence times for jump-diffusion between sites and corresponding effective force constants (resilience) and activation energies were determined from the data. Conclusions Modifications of the physicochemical properties caused by mutations of the amino acids were found to have a significant impact on protein dynamics. Activation energies of local side chain dynamics were found to be similar between the different proteins being close to the energy, which is required for the rupture of single hydrogen bond in a protein. General significance The measured dynamic quantities showed significant and systematic variations between the investigated species, suggesting that they are the signature of an evolutionary adaptation process stimulated by the different physiological environments of the respective protein. [ABSTRACT FROM AUTHOR]

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.ydbio.2009.10.017 Byline: Stephen Frankenberg, Andrew Pask, Marilyn B. Renfree Keywords: POU5F1; POU2; Pluripotency; Tammar wallaby; Platypus; Germ cells Abstract: POU5F1 (OCT4) encodes a master regulator of pluripotency that is present in all mammals. A paralogue, POU2, is also present in the genomes of marsupials and monotremes and is an orthologue of zebrafish pou2 and chicken POUV. We explored the evolution of class V POU domain transcription factors and show that POU5F1 arose by gene duplication of pou2 early in the evolution of tetrapods and is not mammal-specific, as previously thought. Instead, either POU5F1 or POU2/POUV has become extinct independently in various lineages, although all gnathostomes appear to possess at least one or the other. In the tammar wallaby, POU5F1 expression is limited to pluripotent cell types (embryonic tissues and germ cells). POU2 is similarly expressed in pluripotent tissues but is also expressed in a broad range of adult tissues. Thus, unlike POU5F1, the role of POU2 may not be restricted to pluripotent cell types but could have a related function such as maintaining multipotency in adult stem cells. Author Affiliation: Department of Zoology, University of Melbourne, 3010, Victoria, Australia Article History: Received 31 May 2009; Revised 7 October 2009; Accepted 8 October 2009

Abstract: Examination of preserved skin from a duckbill dinosaur revealed disruption of the normal scale pattern and replacement by granulation tissue. Wrinkles radiating outward from the scar document wound contraction similar to that seen in modern injuries. This is the first unequivocal report of dinosaur tissue response to dermal pathology and evidences behavior – escape from a predator. [Copyright &y& Elsevier]

Abstract: Oak pinhole borer, Platypus cylindrus is seen in recent years as one of the biggest enemies directly involved in the observed decline of cork oak in Mediterranean forests with all the economic implications. As an ambrosia beetle, it has developed its effective drilling mouthpart enough to make tunnels in hardwood of the tree. The fine structural aspects of the mouthpart using the field emission scanning electron microscopy are analyzed about 23 adults collected in galleries of infested cork oak trees (Quercus suber) in a littoral forest of northwest Algeria. These adults are preserved in alcohol 70%, cleaned and coated with gold. The mouthparts of this beetle consist commonly of a labrum, a pair of mandibles, a pair of maxillae and the labium but with adapted structure to excavate galleries in the hardwood. In this role is also involved the first pair of legs. The function that present the different structures related to the construction of the tunnels is discussed. Both of maxillary and labial palpi direct the food to the mouth and hold it while the mandibles chew the food. The distal ends of these palpi are flattened and have shovel-like setae. Females have larger maxillary palpi than males and this is related to the particular biology of each sex. [Copyright &y& Elsevier]

Abstract: Toll-like receptors (TLRs) that initiate an innate immune response contain an extracellular leucine rich repeat (LRR) domain and an intracellular Toll IL-receptor (TIR) domain. There are fifteen different TLRs in vertebrates. The LRR domains, which adopt a solenoid structure, usually have higher rates of evolution than do the TIR globular domains. It is important to understand the molecular evolution and functional roles of TLRs from this standpoint. Both pairwise genetic distances and Ka/Ks''s (the ratios between non synonymous and synonymous substitution rates) were compared between the LRR domain and the TIR domain of 366 vertebrate TLRs from 96 species (from fish to primates). In fourteen members (TLRs 1, 2, 3, 4, 5, 6, 7, 8, 9, 11/12, 13, 14, 21, and 22/23) the LRR domains evolved significantly more rapidly than did the corresponding TIR domains. The evolutionary rates of the LRR domains are significantly different among these members; LRR domains from TLR3 and TLR7 from primates to fishes have the lowest rate of evolution. In contrast, the fifteenth member, TLR10, shows no significant differences; its TIR domain is not highly conserved. The present results suggest that TLR10 may have a different function in signaling from those other members and that a higher conservation of TLR3 and TLR7 may reflect a more ancient mechanism and/or structure in the innate immune response system. Gene conversions are suggested to have occurred in platypus TLR6 and TLR10. This study provides new insight about structural and functional diversification of vertebrate TLRs. [Copyright &y& Elsevier]

Abstract: The occurrence of venom in mammals has long been considered of minor importance, but recent fossil discoveries and advances in experimental techniques have cast new light into this subject. Mammalian venoms form a heterogeneous group having different compositions and modes of action and are present in three classes of mammals, Insectivora, Monotremata, and Chiroptera. A fourth order, Primates, is proposed to have venomous representatives. In this review we highlight recent advances in the field while summarizing biochemical characteristics of these secretions and their effects upon humans and other animals. Historical aspects of venom discovery and evolutionary hypothesis regarding their origin are also discussed. [Copyright &y& Elsevier]

Abstract: In February 1943, in the midst of the Second World War, Prime Minister Winston Churchill demanded that a live duck-billed platypus be sent from Australia to Britain. A vigorous male was shipped off but died shortly before arrival in Britain. This request can only be understood if placed in the context of Churchill’s passion for exotic pets as well as the rich history of aristocratic menageries and live diplomatic gifts. Obtaining an animal hitherto unseen alive in Europe would have been a great zoological achievement for London Zoo and secured British authority in heated historical taxonomical debates. This zoological triumph, coupled with accomplishing an extravagant enterprise in the middle of war-time austerity would have boosted public morale. Most importantly, despite its death, the platypus, served as a token for mediating the soured relations between Australia and Britain. Churchill’s platypus provides a unique case of animal collecting that incorporates effects on international diplomacy and public relations along with a great private eccentricity and passion. [Copyright &y& Elsevier]

Abstract: MicroRNA (miRNA) is the negative regulator of gene expression, also known as guide strand of transient miRNA:miRNA* duplex. It is critical in maintaining the normal physiological processes such as development, differentiation, and apoptosis in many organisms. With increasing miRNA data, it is desirable to design methods to identify guide strand based on machine learning algorithms. In this study, the random forest models based on local sequence–structure features were proposed to identify miRNA in four species. The accuracies achieved were 86.51% for Homo sapiens, 81.66% for Ornithorhynchus anatinus, 82.33% for Mus musculus and 85.71% for Schmidtea mediterranea, respectively. Furthermore, the important analysis of feature elements was carried out by using the conditional feature importance strategy. The analysis results revealed that most of the significant elements were related to guanine–cytosine (GC) base pair. We believed that our method could be beneficial to annotate the function of miRNA and help the further understanding of the RNA interference mechanism. [Copyright &y& Elsevier]

Abstract: Gongneung Weir-2 was built in the 1970s to supply water for irrigation. For a long time, the weir was left untended due to the land-use changes that were made to a nearby area. This weir was removed completely on April 4, 2006. The present study investigated the effect of the resultant flow-regime changes on river morphology and fish habitat. Observed changes in the grain size distribution, bed elevation, and cross-section pre- and post-weir removal are provided and discussed in this paper. Various bed zones such as a sand island and a vegetated marshy zone, which can diversify an aquatic habitat, formed after the removal. In fact, changes in the number of observed fish species post-removal also were investigated. Finally, specific changes to the physical habitat of Zacco platypus were numerically simulated using the River2D model. The results indicated that habitat suitability post-removal was enhanced for all flow discharges. The WUA values increased 32.3–53.4% for all life stages in the flow discharge of 1.5m3 s−1. The numerical results also showed that after the removal of the weir, the distribution of the physical habitat changed to reflect continuity near the weir. [Copyright &y& Elsevier]

Abstract: In this manuscript we describe the major components of the Platypus time-of-flight neutron reflectometer at the 20MW OPAL reactor in Sydney, Australia. Platypus is a multipurpose spectrometer for the characterisation of solid thin films, materials adsorbed at the solid–liquid interface and free-liquid surfaces. It also has the capacity to study magnetic thin films using spin-polarised neutrons. Platypus utilises a white neutron beam (λ=2–20Å) that is pulsed using boron-coated disc chopper pairs; thus providing the capacity to tailor the wavelength resolution of the pulses to suit the system under investigation. Supermirror optical components are used to focus, deflect or spin-polarise the broad bandwidth neutron beams, and typical incident spectra are presented for each configuration. A series of neutron reflectivity datasets are presented, indicating the quality and flexibility of this spectrometer. Minimum reflectivity values of <10−7 are observed; while maximum thickness values of 325nm have been measured for single-component films and 483nm for a multilayer system. Off-specular measurements have also been made to investigate in-plane features as opposed to those normal to the sample surface. Finally, the first published studies conducted using the Platypus time-of-flight neutron reflectometer are presented. [Copyright &y& Elsevier]

Abstract: LINE-1 (L1) retrotransposons represent the most abundant family of non-LTR retrotransposons in virtually all mammals. The only currently known exception is Platypus, where it is found only in low copy numbers. Autonomous L1s encode two proteins, ORF1p and ORF2p, both of which are required for the transposition of L1s. L1 replicative machinery is also involved in the trans-mobilization of non-autonomous retrotransposons, such as diverse short interspersed repetitive elements (SINEs) and processed pseudogenes. Here, we focus on a unique category of “half -L1” elements (HAL1s), which encode ORF1p but not ORF2p. HAL1s are present both in placental mammals and marsupials. We demonstrate that HAL1s originated independently several times during the evolution of mammals. The youngest mammalian HAL1 elements analyzed in this paper were identified in the guinea pig genome. Our analysis strongly suggests that HAL1-encoded ORF1p is essential for the transposition of HAL1s and indicates that the evolution of ORF1p in HAL1s is faster than in L1s. The implications of HAL1 for the evolution of L1 elements and the host genomes are discussed. [ABSTRACT FROM AUTHOR]

Abstract: To trace the emergence of modern IgA isotypes during vertebrate evolution we have studied the immunoglobulin repertoire of a model monotreme, the platypus. Two highly divergent IgA-like isotypes (IgA1 and IgA2) were identified and their primary structures were determined from full-length cDNAs. A comparative analysis of the amino acid sequences for IgA from various animal species showed that the two platypus IgA isotypes form a branch clearly separated from their eutherian (placental) counterparts. However, they still conform to the general structure of eutherian IgA, with a hinge region and three constant domains. This indicates that the deletion of the second domain and the formation of a hinge region in IgA did occur very early during mammalian evolution, more than 166 million years ago. The two IgA isotypes in platypus differ in primary structure and appear to have arisen from a very early gene duplication, possibly preceding the metatherian eutherian split. Interestingly, one of these isotypes, IgA1, appears to be expressed in only the platypus, but is present in the echidna based on Southern blot analysis. The platypus may require a more effective mucosal immunity, with two highly divergent IgA forms, than the terrestrial echidna, due to its lifestyle, where it is exposed to pathogens both on land and in the water. [Copyright &y& Elsevier]

Abstract: Computational methods were used to predict the amino acid sequences and gene locations for mammalian lactate dehydrogenase (LDH) genes and proteins using genome sequence databanks. Human LDHA, LDHC and LDH6A genes were located in tandem on chromosome 11, while LDH6B and LDH6C genes were on chromosomes 15 and 12, respectively. Opossum LDHC and LDH6B genes were located in tandem with the opossum LDHA gene on chromosome 5 and contained 7 (LDHA and LDHC) or 8 (LDH6B) exons. An amino acid sequence prediction for the opossum LDH6B subunit gave an extended N-terminal sequence, similar to the human and mouse LDH6B sequences, which may support the export of this enzyme into mitochondria. The platypus genome contained at least 3 LDH genes encoding LDHA, LDHB and LDH6B subunits. Phylogenetic studies and sequence analyses indicated that LDHA, LDHB and LDH6B genes are present in all mammalian genomes examined, including a monotreme species (platypus), whereas the LDHC gene may have arisen more recently in marsupial mammals. [Copyright &y& Elsevier]

Abstract: A concise diastereoselective and enantiopure route to the (1S,4R)- and (1S, 4S)-isomers of 4-isopropyl-1-methyl-2-cyclohexen-1-ol via a palladium-catalysed deoxygenation of the enol triflate derived from limonene glycol. [Copyright &y& Elsevier]

Abstract: The end product of purine catabolism varies amongst vertebrates and is a consequence of independent gene inactivation events that have truncated the purine catabolic pathway. Mammals have traditionally been grouped into two classes based on their end product of purine catabolism: most mammals, whose end product is allantoin due to an ancient loss of allantoinase (ALLN), and the hominoids, whose end product is uric acid due to recent inactivations of urate oxidase (UOX). However little is known about purine catabolism in marsupials and monotremes. Here we report the results of a comparative genomics study designed to characterize the purine catabolic pathway in a marsupial, the South American opossum (Monodelphis domestica), and a monotreme, the platypus (Ornithorhynchus anatinus). We found that both genomes encode a more complete set of genes for purine catabolism than do eutherians and conclude that a near complete purine catabolic pathway was present in the common ancestor of all mammals, and that the loss of ALLN is specific to placental mammals. Our results therefore provide a revised history for gene loss in the purine catabolic pathway and suggest that marsupials and monotremes represent a third class of mammals with respect to their end products of purine catabolism. [Copyright &y& Elsevier]

Abstract: The sialic acids of the platypus, birds, and reptiles were investigated with regard to the occurrence of N-glycolylneuraminic (Neu5Gc) acid. They were released from tissues, eggs, or salivary mucin samples by acid hydrolysis, and purified and analyzed by thin-layer chromatography, high-performance liquid chromatography, and mass spectrometry. In muscle and liver of the platypus only N-acetylneuraminic (Neu5Ac) acid was found. The nine bird species studied also did not express N-glycolylneuraminic acid with the exception of an egg, but not tissues, from the budgerigar and traces in poultry. Among nine reptiles, including one turtle, N-glycolylneuraminic acid was only found in the egg and an adult basilisk, but not in a freshly hatched animal. BLAST analysis of the genomes of the platypus, the chicken, and zebra finch against the CMP-N-acetylneuraminic acid hydroxylase did not reveal the existence of a similar protein structure. Apparently monotremes (platypus) and sauropsids (birds and reptiles) cannot synthesize Neu5Gc. The few animals where Neu5Gc was found, especially in eggs, may have acquired this from the diet or by an alternative pathway. Since Neu5Gc is antigenic to man, the observation that this monosaccharide does not or at least only rarely occur in birds and reptiles, may be of nutritional and clinical significance. [Copyright &y& Elsevier]

Abstract: Immunoglobulins loci in mammals are well known to be organized within a translocon, however their origin remains unresolved. Four of the five classes of immunoglobulins described in humans and rodents (immunoglobulins M, G, E and A—IgM, IgG, IgE and IgA) were found in marsupials and monotremes (immunoglobulin D—IgD was not found) thus showing that the genomic structure of antibodies in mammals has remained constant since its origin. We have recently described the genomic organization of the immunoglobulin heavy chain locus in reptiles (IGHM, IGHD and IGHY). These data and the characterization of the IGH locus in platypus (Ornithorhynchus anatinus), allow us to elucidate the changes that took place in this genomic region during evolution from reptile to mammal. Thus, by using available genome data, we were able to detect that platypus IGH locus contains reptilian and mammalian genes. Besides having an IGHD that is very similar to the one in reptiles and an IGHY, they also present the mammal specific antibody genes IGHG and IGHE, in addition to IGHA. We also detected a pseudogene that originated by recombination between the IGHD and the IGHM (similar to the IGHD2 found in Eublepharis macularius). The analysis of the IGH locus in platypus shows that IGHY was duplicated, firstly by evolving into IGHE and then into IGHG. The IGHA of the platypus has a complex origin, and probably arose by a process of recombination between the IGHM and the IGHY. We detected about 44 VH genes (25 were already described), most of which comprise a single group. When we compared these VH genes with those described in Anolis carolinensis, we find that there is an evolutionary relationship between the VH genes of platypus and the reptilian Group III genes. These results suggest that a fast VH turnover took place in platypus and this gave rise to a family with a high VH gene number and the disappearance of the earlier VH families. [Copyright &y& Elsevier]

Abstract: Despite the importance of blue king crab (BKC) to the Bering Sea fishery, there has been no detailed study of juvenile habitat preferences. Such information is critical for understanding life history and for development of stock enhancement programs. The aims of this study were to determine the natural substrata that glaucothoe prefer to settle on, and whether they or subsequent crab 1 stage (C1) redistribute to different habitats over time. A laboratory experiment was performed in 24 round containers divided in four equal quadrants each filled with one of the following natural substrata: beach sand, gravel, shells and cobble. Containers were assigned to 8 groups of 3 replicates each and were kept at ~6–8 °C. Twenty five glaucothoe were released in each container on day 0, and one group of three replicates was removed for examination at each of the following intervals: 24 h, 7, 14, 21, 28, 35, 42 and 49 days. Numbers of swimming and settled specimens on each substrate and period were recorded. Glaucothoe began to settle immediately after being released since no swimming larvae were found during any sampling periods. Substrata complexity was important for the habitat selection and distribution of blue king crab glaucothoe and crab 1 stage. During the glaucothoe stage, beach sand was rejected and cobble, shell and gravel were chosen equally. After glaucothoe molted to crab 1 stage and became bigger, animals preferred cobble and shell instead of gravel and beach sand. Understanding habitat selection is useful not only for management of crab populations, but also for assessing the potential of various habitats for stock enhancement of blue king crabs. [Copyright &y& Elsevier]

Abstract: Only five mammalian species are known to be venomous, and while a large amount of research has been carried out on reptile venom, mammalian venom has been poorly studied to date. Here we describe the status of current research into the venom of the platypus, a semi-aquatic egg-laying Australian mammal, and discuss our approach to platypus venom transcriptomics. We propose that such construction and analysis of mammalian venom transcriptomes from small samples of venom gland, in tandem with proteomics studies, will allow the identification of the full range of mammalian venom components. Functional studies and pharmacological evaluation of the identified toxins will then lay the foundations for the future development of novel biomedical substances. A large range of useful molecules have already been identified in snake venom, and many of these are currently in use in human medicine. It is therefore hoped that this basic research to identify the constituents of platypus venom will eventually yield novel drugs and new targets for painkillers. [Copyright &y& Elsevier]

Abstract: The platypus, as an egg-laying mammal, displays an unusual mixture of reptilian and mammalian characteristics. It is also venomous, and further investigations into its little-studied venom may lead to the development of novel pharmaceuticals and drug targets and provide insights into the origins of mammalian venom. Here we investigate the expression patterns of antimicrobial genes called defensins, and also the venom peptides called defensin-like peptides (OvDLPs). We show, in the first expression study on any platypus venom gene, that the OvDLPs are expressed in a greater range of tissues than would be expected for genes with specific venom function, and thus that they may have a wider role than previously suspected. [Copyright &y& Elsevier]

The L-to-D-peptide isomerase from the venom of the platypus (Ornithorhyncus anatinus) is the first such enzyme to be reported for a mammal. In delineating its catalytic mechanism and broader roles in the animal, its substrate specificity was explored. We used N-terminal segments of defensin-like peptides DLP-2 and DLP-4 and natriuretic peptide OvCNP from the venom as substrates. The DLP analogues IMFsrs and ImFsrs (srs is a solubilizing chain; lowercase letters denote D-amino acid) were effective substrates for the isomerase; it appears to recognize the N-terminal tripeptide sequence Ile-Xaa-Phe-. A suite of 26 mutants of these hexapeptides was synthesized by replacing the second residue (Met) with another amino acid, viz. Ala, α-aminobutyric acid, Ile, Leu, Lys, norleucine, Phe, Tyr, and Val. It was shown that mutant peptides incorporating norleucine and Phe are substrates and exhibit L- or D-amino acid isomerization, but mutant peptides that contain residues with shorter, β-branched or long side chains with polar terminal groups, viz. Ala, α-aminobutyric acid, Ile, Val, Leu, Lys, and Tyr, respectively, are not substrates. It was demonstrated that at least three N-terminal amino acid residues are absolutely essential for L- to D-isomerization; furthermore, the third amino acid must be a Phe residue. None of the hexapeptides based on LLH, the first three residues of OvCNP, were substrates. A consistent 2-base mechanism is proposed for the isomerization; abstraction of a proton by 1 base is concomitant with delivery of a proton by the conjugate acid of a second base. [ABSTRACT FROM AUTHOR]

Abstract: We have examined the cyto- and chemoarchitecture of the trigeminal nuclei of two monotremes using Nissl staining, enzyme reactivity for cytochrome oxidase, immunoreactivity for calcium binding proteins and non-phosphorylated neurofilament (SMI-32 antibody) and lectin histochemistry (Griffonia simplicifolia isolectin B4). The principal trigeminal nucleus and the oralis and interpolaris spinal trigeminal nuclei were substantially larger in the platypus than in either the echidna or rat, but the caudalis subnucleus was similar in size in both monotremes and the rat. The numerical density of Nissl stained neurons was higher in the principal, oralis and interpolaris nuclei of the platypus relative to the echidna, but similar to that in the rat. Neuropil immunoreactivity for parvalbumin was particularly intense in the principal trigeminal, oralis and interpolaris subnuclei of the platypus, but the numerical density of parvalbumin immunoreactive neurons was not particularly high in these nuclei of the platypus. Neuropil immunoreactivity for calbindin and calretinin was relatively weak in both monotremes, although calretinin immunoreactive somata made up a large proportion of neurons in the principal, oralis and interpolaris subnuclei of the echidna. Distribution of calretinin immunoreactivity and Griffonia simplicifolia B4 isolectin reactivity suggested that the caudalis subnucleus of the echidna does not have a clearly defined gelatinosus region. Our findings indicate that the trigeminal nuclei of the echidna do not appear to be highly specialized, but that the principal, oralis and interpolaris subnuclei of the platypus trigeminal complex are highly differentiated, presumably for processing of tactile and electrosensory information from the bill. [Copyright &y& Elsevier]

Bi-sensory striped arrays are described in owl and platypus that share some similarities with the other variant of bi-sensory striped array found in primate and carnivore striate cortex: ocular dominance columns. Like ocular dominance columns, the owl and platypus striped systems each involve two different topographic arrays that are cut into parallel stripes, and interdigitated, so that higher-order neurons can integrate across both arrays. Unlike ocular dominance stripes, which have a separate array for each eye, the striped array in the middle third of the owl tectum has a separate array for each cerebral hemisphere. Binocular neurons send outputs from both hemispheres to the striped array where they are segregated into parallel stripes according to hemisphere of origin. In platypus primary somatosensory cortex (S1), the two arrays of interdigitated stripes are derived from separate sensory systems in the bill, 40,000 electroreceptors and 60,000 mechanoreceptors. The stripes in platypus S1 cortex produce bimodal electrosensory–mechanosensory neurons with specificity for the time-of-arrival difference between the two systems. This “thunder-and-lightning” system would allow the platypus to estimate the distance of the prey using time disparities generated at the bill between the earlier electrical wave and the later mechanical wave caused by the motion of benthic prey. The functional significance of parallel, striped arrays is not clear, even for the highly-studied ocular dominance system, but a general strategy is proposed here that is based on the detection of temporal disparities between the two arrays that can be used to estimate distance. [Copyright &y& Elsevier]

Energy demands in the platypus are likely to increase in the breeding season, which occurs from winter to early spring. Glucocorticoids, which play a major role in energy mobilisation, were measured in consecutive blood samples from free-ranging adults at approximately monthly intervals throughout the year. Glucose and free fatty acids were also measured in some samples. Plasma concentrations of glucocorticoids rose significantly during the first 30 min after capture, accompanied by a rise in free fatty acids, but no corresponding increase in glucose concentrations. We observed a strong pattern in plasma glucocorticoids in samples collected within 15 min of capture (indicative of pre-disturbance concentrations) in different phases of the annual reproductive cycle, with significantly higher levels in both males and females in the breeding season compared to the non-breeding season. These data, and the decline in tail fat stores that occur towards the end of the mating period (around October), suggest that platypus experience high-energy demands during this phase of reproduction. Plasma glucocorticoid concentrations in females sampled during the lactation period (October–February) were relatively low, and similar to those in females sampled in the non-breeding, non-lactation period (March–June). The latter requires further investigation as results may have been influenced by sampling limitations. [Copyright &y& Elsevier]

The platypus (Ornithorhyncus anatinus) is characterized by a rate of oxygen consumption V˙o2 that is higher than that reported for other similar sized monotremes, similar to marsupials and somewhat lower than eutherians. The platypus is also characterized by a breathing pattern, more typical of a diving mammal, with a high ‘inspiratory drive’ and a post-inspiratory pause. Further, the platypus reveals an attenuated hyperventilatory response to hypoxia and a reduced hyperpnoea to hypercapnia; such a response to these chemical stimuli is commonly observed in semi-fossorial and diving mammals. Nevertheless, under conditions of normoxia, ventilation V˙E is matched to V˙o2 such that the convection requirement V˙EV˙o2 is similar to that reported for other mammals (approx. 37). The apparent consistency of the convection requirement in mammals suggests the blueprint for the design of the mammalian respiratory system has remained an interspecies constant in the three divergent extant sub-classes of mammals. [Copyright &y& Elsevier]

There is limited information regarding the kinetics of antibody responses exhibited by the platypus and the echidna in response to a T cell dependent antigen. In this preliminary study a platypus, an echidna and a rabbit were inoculated with sheep red blood cells to compare their antibody responses and kinetics. The antibody titres, produced by the platypus and echidna, were less than those elicited in the rabbit. Furthermore, the echidna and platypus exhibited a weak secondary response. This was most likely due to a failure of the platypus and echidna to undergo the characteristic IgM to IgG isotype switch following second antigen exposure. The conformational structure of these antibodies may differ from eutherian antibodies. This was further supported by a heat sensitivity experiment that indicated that these antibodies are more labile than rabbit immunoglobulins and therefore structurally less stable. [Copyright &y& Elsevier]

Monotremes have traditionally been considered a remnant group of mammals descended from archaic Mesozoic stock, surviving to the present day on the relatively isolated Australian continent. Challenges to this orthodoxy have been spurred by discoveries of ‘advanced’ Cretaceous monotremes (Steropodon galmani, Archer, M., et al., 1985. First Mesozoic mammal from Australia—an Early Cretaceous monotreme, Nature. 318, 363–366) as well as by results from molecular data linking monotremes to therian mammals (specifically to marsupials in some studies). This paper reviews the monotreme fossil record and briefly discusses significant new information from additional Cretaceous Australian material. Mesozoic monotremes (including S. galmani) were a diverse group as evidenced by new material from the Early Cretaceous of New South Wales and Victoria currently under study. Although most of these new finds are edentulous jaws (limiting dental comparisons and determination of dietary niches), a range of sizes and forms has been determined. Some of these Cretaceous jaws exhibit archaic features—in particular evidence for the presence of a splenial bone in S. galmani—not seen in therian mammals or in post-Mesozoic (Tertiary and Quaternary) monotreme taxa. Tertiary monotremes were either archaic ornithorhynchids (toothed platypuses in the genera Monotrematum and Obdurodon) or tachyglossids (large echidnas in the genera Megalibgwilia and Zaglossus). Quaternary ornithorhynchid material is referable to the sole living platypus species Ornithorhynchus anatinus. Quaternary echidnas, however, were moderately diverse and several forms are known (Megalibgwilia species; ‘Zaglossus’ hacketti; Zaglossus species and Tachyglossus aculeatus). [Copyright &y& Elsevier]

Monotremes, perhaps more than any other order of mammals, display an enormous behavioural reliance upon the tactile senses. In the platypus, Ornithorhynchus anatinus, this is manifest most strikingly in the special importance of the bill as a peripheral sensory organ, an importance confirmed by electrophysiological mapping that reveals a vast area of the cerebral cortex allocated to the processing of tactile inputs from the bill. Although behavioural evidence in the echidna, Tachyglossus aculeatus, suggests a similar prominence for tactile inputs from the snout, there is also a great reliance upon the distal limbs for digging and burrowing activity, pointing to the importance of tactile information from these regions for the echidna. In recent studies, we have investigated the peripheral tactile neural mechanisms in the forepaw of the echidna to establish the extent of correspondence or divergence that has emerged over the widely different evolutionary paths taken by monotreme and placental mammals. Electrophysiological recordings were made from single tactile sensory nerve fibres isolated in fine strands of the median or ulnar nerves of the forearm. Controlled tactile stimuli applied to the forepaw glabrous skin permitted an initial classification of tactile sensory fibres into two broad divisions, according to their responses to static skin displacement. One displayed slowly adapting (SA) response properties, while the other showed a selective sensitivity to the dynamic components of the skin displacement. These purely dynamically-sensitive tactile fibres could be subdivided according to vibrotactile sensitivity and receptive field characteristics into a rapidly adapting (RA) class, sensitive to low frequency (≤50 Hz) vibration and another class, sensitive to a broader range of vibrotactile frequencies (approx. 50–300 Hz). The differential tactile sensitivity of the three principal fibre classes and their individual coding characteristics, determined by quantitative stimulus–response analysis, indicate first, that this triad of fibre classes can subserve high-acuity tactile signalling from the echidna footpad and second, that peripheral tactile sensory mechanisms are highly conserved across evolutionarily-divergent mammalian orders. [Copyright &y& Elsevier]

The first specimen of platypus (Ornithorhynchus anatinus) that reached Britain in the late 18th century was regarded a scientific hoax. Over decades the anatomical characteristics of these unique mammals, such as egg laying and the existence of mammary glands, were hotly debated before they were accepted. Within the last 40 years, more and more details of monotreme physiology, histology, reproduction and genetics have been revealed. Some show similarities with birds or reptiles, some with therian mammals, but many are very specific to monotremes. The genome is no exception to monotreme uniqueness. An early opinion was that the karyotype, composed of a few large chromosomes and many small ones, resembled bird and reptile macro- and micro-chromosomes. However, the platypus genome also features characteristics that are not present in other mammals, such as a complex translocation system. The sex chromosome system is still not resolved. Nothing is known about dosage compensation and, unlike in therian mammals, there seems to be no genomic imprinting. In this article we will recount the mysteries of the monotreme genome and describe how we are using recently developed technology to identify chromosomes in mitosis, meiosis and sperm, to map genes to chromosomes, to unravel the sex chromosome system and the translocation chain and investigate X inactivation and genomic imprinting in monotremes. [Copyright &y& Elsevier]

In the platypus, electroreceptors are located in rostro-caudal rows in skin of the bill, while mechanoreceptors are uniformly distributed across the bill. The electrosensory area of the cerebral cortex is contained within the tactile somatosensory area, and some cortical cells receive input from both electroreceptors and mechanoreceptors, suggesting a close association between the tactile and electric senses. Platypus can determine the direction of an electric source, perhaps by comparing differences in signal strength across the sheet of electroreceptors as the animal characteristically moves its head from side to side while hunting. The cortical convergence of electrosensory and tactile inputs suggests a mechanism for determining the distance of prey items which, when they move, emit both electrical signals and mechanical pressure pulses. Distance could be computed from the difference in time of arrival of the two signals. Much of the platypus’ feeding is done by digging in the bottom of streams with the bill. Perhaps the electroreceptors could also be used to distinguish animate and inanimate objects in this situation where the mechanoreceptors would be continuously stimulated. Much of this is speculation, and there is still much to be learned about electroreception in the platypus and its fellow monotreme, the echidna. [Copyright &y& Elsevier]

We investigated the diving behaviour, the time allocation of the dive cycle and the behavioural aerobic dive limit (ADL) of platypuses (Ornithorhynchus anatinus) living at a sub-alpine Tasmanian lake. Individual platypuses were equipped with combined data logger–transmitter packages measuring dive depth. Mean dive duration was 31.3 s with 72% of all dives lasting between 18 and 40 s. Mean surface duration was 10.1 s. Mean dive depth was 1.28 m with a maximum of 8.77 m. Platypuses performed up to 1600 dives per foraging trip with a mean of 75 dives per hour. ADL was estimated by consideration of post-dive surface intervals vs. dive durations. Only 15% of all dives were found to exceed the estimated ADL of 40 s, indicating mainly aerobic diving in the species. Foraging platypuses followed a model of optimised recovery time, the optimal breathing theory. Total bottom duration or total foraging duration per day is proposed as a useful indicator of foraging efficiency and hence habitat quality in the species. [Copyright &y& Elsevier]

In this paper, we review data on the monotreme immune system focusing on the characterisation of lymphoid tissue and of antibody responses, as well the recent cloning of immunoglobulin genes. It is now known that monotremes utilise immunoglobulin isotypes that are structurally identical to those found in marsupials and eutherians, but which differ to those found in birds and reptiles. Monotremes utilise IgM, IgG, IgA and IgE. They do not use IgY. Their IgG and IgA constant regions contain three domains plus a hinge region. Preliminary analysis of monotreme heavy chain variable region diversity suggests that the platypus primarily uses a single VH clan, while the short-beaked echidna utilises at least 4 distinct VH families which segregate into all three mammalian VH clans. Phylogenetic analysis of the immunoglobulin heavy chain constant region gene sequences provides strong support for the Theria hypothesis. The constant region of IgM has proven to be a useful marker for estimating the time of divergence of mammalian lineages. [Copyright &y& Elsevier]