Origin of a cryptic lineage in a threatened reptile through isolation and historical hybridization.

Identifying phylogenetically distinct lineages and understanding the evolutionary processes by which they have arisen are important goals of phylogeography. This information can also help define conservation units in endangered species. Such analyses are being transformed by the availability of genomic-scale data sets and novel analytical approaches for statistically comparing different historical scenarios as causes of phylogeographic patterns. Here, we use genomic-scale restriction-site-associated DNA sequencing (RADseq) data to test for distinct lineages in the endangered Eastern Massasauga Rattlesnake (Sistrurus catenatus). We then use coalescent-based modeling techniques to identify the evolutionary mechanisms responsible for the origin of the lineages in this species. We find equivocal evidence for distinct phylogenetic lineages within S. catenatus east of the Mississippi River, but strong support for a previously unrecognized lineage on the western edge of the range of this snake, represented by populations from Iowa, USA. Snakes from these populations show patterns of genetic admixture with a nearby non-threatened sister species (Sistrurus tergeminus). Tests of historical demographic models support the hypothesis that the genetic distinctiveness of Iowa snakes is due to a combination of isolation and historical introgression between S. catenatus and S. tergeminus. Our work provides an example of how model-based analysis of genomic-scale data can help identify conservation units in rare species.

Simultaneous estimation of multiple quantitative trait loci and growth curve parameters through hierarchical Bayesian modeling.

A novel hierarchical quantitative trait locus (QTL) mapping method using a polynomial growth function and a multiple-QTL model (with no dependence in time) in a multitrait framework is presented. The method considers a population-based sample where individuals have been phenotyped (over time) with respect to some dynamic trait and genotyped at a given set of loci. A specific feature of the proposed approach is that, instead of an average functional curve, each individual has its own functional curve. Moreover, each QTL can modify the dynamic characteristics of the trait value of an individual through its influence on one or more growth curve parameters. Apparent advantages of the approach include: (1) assumption of time-independent QTL and environmental effects, (2) alleviating the necessity for an autoregressive covariance structure for residuals and (3) the flexibility to use variable selection methods. As a by-product of the method, heritabilities and genetic correlations can also be estimated for individual growth curve parameters, which are considered as latent traits. For selecting trait-associated loci in the model, we use a modified version of the well-known Bayesian adaptive shrinkage technique. We illustrate our approach by analysing a sub sample of 500 individuals from the simulated QTLMAS 2009 data set, as well as simulation replicates and a real Scots pine (Pinus sylvestris) data set, using temporal measurements of height as dynamic trait of interest.

Aerodynamic characteristics and genesis of aggregates at Sakurajima Volcano, Japan.

Aggregation of volcanic ash is known to significantly impact sedimentation from volcanic plumes. The study of particle aggregates during tephra fallout is crucial to increase our understanding of both ash aggregation and sedimentation. In this work, we describe key features of ash aggregates and ash sedimentation associated with eleven Vulcanian explosions at Sakurajima Volcano (Japan) based on state-of-the-art sampling techniques. We identified five types of aggregates of both Particle Cluster (PC) and Accretionary Pellet (AP) categories. In particular, we found that PCs and the first and third type of APs can coexist within the same eruption in rainy conditions. We also found that the aerodynamic properties of aggregates (e.g., terminal velocity and density) depend on their type. In addition, grainsize analysis revealed that characteristics of the grainsize distributions (GSDs) of tephra samples correlate with the typology of the aggregates identified. In fact, bimodal GSDs correlate with the presence of cored clusters (PC3) and liquid pellets (AP3), while unimodal GSDs correlate either with the occurrence of ash clusters (PC1) or with the large particles (coarse ash) coated by fine ash (PC2).

Intercellular bridges coordinate the transition from pluripotency to meiosis in mouse fetal oocytes.

Meiosis is critical to generating oocytes and ensuring female fertility; however, the mechanisms regulating the switch from mitotic primordial germ cells to meiotic germ cells are poorly understood. Here, we implicate intercellular bridges (ICBs) in this state transition. We used three-dimensional in toto imaging to map meiotic initiation in the mouse fetal ovary and revealed a radial geometry of this transition that precedes the established anterior-posterior wave. Our studies reveal that appropriate timing of meiotic entry across the ovary and coordination of mitotic-meiotic transition within a cyst depend on the ICB component Tex14, which we show is required for functional cytoplasmic sharing. We find that Tex14 mutants more rapidly attenuate the pluripotency transcript Dppa3 upon meiotic initiation, and Dppa3 mutants undergo premature meiosis similar to Tex14 Together, these results lead to a model that ICBs coordinate and buffer the transition from pluripotency to meiosis through dilution of regulatory factors.

Polymorphism at the avpr1a locus in male prairie voles correlated with genetic but not social monogamy in field populations.

Integrative studies of genetics, neurobiology and behaviour indicate that polymorphism in specific genes contributes to variation observed in some complex social behaviours. The neuropeptide arginine vasopressin plays an important role in the regulation of a variety of social behaviours, including social attachment of males to females, through its action on the vasopressin 1a receptor (V1aR). In socially monogamous prairie voles (Microtus ochrogaster), polymorphism in the length of microsatellite DNA within the regulatory region of the gene (avpr1a) encoding the V1aR predicts differences among males in neural expression of V1aRs and partner preference under laboratory conditions. However, understanding the extent to which V1aR mediates variation in prairie vole social and reproductive behaviour observed in nature requires investigating the consequences of avpr1a polymorphism and environmental influences under ecologically relevant conditions. We examined the relationship between avpr1a length polymorphism and monogamy among male prairie voles living in 0.1 ha enclosures during a time similar to their natural lifespan. We found no evidence that avpr1a genotype of males predicts variation in social monogamy measured in the field but some indices of social monogamy were affected by population density. Parentage data indicated that a male's avpr1a genotype significantly influenced the number of females with which he sired offspring and the total number of offspring sired. Total brain concentrations of V1aR mRNA were not associated with either male behaviour or avpr1a genotype. These data show that melding ecological field studies with neurogenetics can substantially augment our understanding of the effects of genes and environment on social behaviours.

"Hitting the nail on the head".

Subungual malignant melanoma is a rare form of malignancy that can present at an advanced stage. We describe a case that was diagnosed after a presentation to the emergency department for a traumatic injury of the affected area. Initial presentations of malignant disease and its complications form a relatively low proportion of the caseload of emergency doctors. In this case, a patient presented after a minor injury that had failed to recover; subsequent investigation of this injury led to the diagnosis of subungual malignant melanoma in an otherwise asymptomatic patient. This is a rare case which presented in an atypical fashion, with a confounding history of minor trauma. It is presented to highlight the differential diagnosis of destructive bone lesions.

Perceptual asymmetries reflect developmental changes in the neuropsychological mechanisms of emotion recognition.

To study how perceptual asymmetries in the recognition of emotion reflect developmental changes in processing affective information, a fused rhyming dichotic word test with positive, negative, and neutral stimuli was administered to adults and children. Results suggested that the hemisphere in which affective information is initially processed affects the strength of perceptual asymmetry and that children's perceptual processing of emotional information is constrained by limited computational resources. Another experiment ruled out effects of volitional shifting of attention to emotional stimuli. These data further confirm that emotional processing involves integration of neural systems across brain regions, including distributed systems that support arousal and recognition. General developmental factors, such as processing capacity, contribute to the coordination of multiple systems responsible for processing emotional information.

Effects of prenatal exposure to xylene on postnatal development and behavior in rats.

The effects of prenatal exposure to the organic solvent xylene (dimethylbenzene, CAS-no 1330-20-7) on postnatal development and behavior in rats were studied. Pregnant rats (Mol:WIST) were exposed to 500 ppm technical xylene 6 h per day on gestation days 7-20. The dose level was selected so as not to induce maternal toxicity or decrease the viability of offspring. In the exposed offspring, a delay in the ontogeny of the air righting reflex, a lower absolute brain weight, and impaired performance in behavioral tests for neuromotor abilities (Rotarod) and for learning and memory (Morris water maze) were found. Generally, the effects were most marked in the female offspring.

[Animal experiment results with a new vena cava filter]. / Tierexperimentelle Ergebnisse mit einem neuen Kavafilter.

A new cava filter has been tried in 23 dogs weighing between 16 and 23 kg. The filter consists of a stainless steel basket which can be introduced either antegrade or retrograde through a 10F teflon catheter and which can be removed again within the first four days. The filter was effective in holding back embolising thrombus. In the early stages, even without artificial embolisation, two out of five animals showed clot formation in the basket. After three or four months, all the filters were permeable and on only two occasions was a small amount of thrombus found.

Studies on Tyzzer's disease: a long-term study of the humoral antibody response in mice, rats and rabbits.

Mice treated with an antigen prepared from livers infected with Bacillus piliformis developed antibodies to the microorganism which reached a peak on the 7th day and disappeared within 40 days: antibody titres in experimentally-infected mice remained at a high level throughout life. The antibody titres in naturally-infected mice, rats and rabbits ramined positive throughout life and followed the same pattern as that of the experimentally-infected mice.

Studies on Tyzzer's disease: transplacental transmission of Bacillus piliformis in rats.

Clinically healthy rats with antibodies to Bacillus piliformis were given prednisolone in the last week of pregnancy. B. piliformis was demonstrated in the livers of their offspring. None of the dams or the young rats showed clinical signs of disease. Antibodies to B. piliformis were found in the young rats at birth, and presisted for several months. The importance of potential transplacental infections when attempting to establish colonies free from B. piliformis in discussed.

Studies on Tyzzer's disease: comparison between Bacillus piliformis strains from mouse, rat and rabbit.

The pathogenicity of Bacillus piliformis strains isolated from mouse, rat and rabbit, compared by inoculation into mice, appeared to be identical. The antibody titre obtained for the individual sera from spontaneously infected mice, rats, rabbits, dogs and humans was the same whether the antigen employed was from organisms isolated from mouse, rat or rabbit.

Demonstration of antibodies to Bacillus piliformis in SPF colonies and experimental transplacental infection by Bacillus piliformis in mice.

Antibodies to Bacillus piliformis were demonstrated by the immunofluorescence antibody technique in sera from mice and rabbits from SPF breeding colonies. Mice in various stages of pregnancy were experimentally infected with Bacillus piliformis and killed 2 to 3 days later. The organism was demonstrated in the uterus, foetal membranes and in the liver of the foetuses. Infection was not limited to any particular stage of pregnancy.

Studies on Tyzzer's disease: isolation and propagation of Bacillus piliformia.

Mice from a colony with subclinical Tyzzer's disease were treated with prednisolone in order to activate a Bacillus piliformis infection. From the livers of these mice the organism was isolated and serially passaged in embryonated eggs. It resisted heating at 75 degrees C for 20 minutes and was still infective after storage at -80 degree C for 24 days, but not for 52 days or more. Infectively was maintained for more than a year by storing infectious liver tissue at -190 degrees C. B. piliformis was also isolated from the liver of a mouse with naturally-occurring Tyzzer's disease and maintained for more than 300 passages. Mice inoculated with different egg passages developed fatal Tyzzer's disease and B. piliformis was reisolated from their livers.

Studies on Tyzzer's disease: acquired immunity against infection and activation of infection by immunosuppressive treatment.

The correlation between serum antibody titre and resistance to challenge infection with Bacillus piliformis was studied in naturally infected mice, in experimentally infected but recovered mice, and in mice treated with antigen prepared from infected livers. Irrespective of the way in which the antibodies were acquired resistance to infection was found to be related to the immunofluorescence antibody titre found. Experimentally infected but recovered mice, as well as rats with persistent antibodies to Bacillus piliformis, were given prednisolone in order to activate a possible persistent infection. Bacillus piliformis was detected in the rats, but not in the mice.

Studies on Tyzzer's disease: application of immunofluorescence for detection of Bacillus piliformis and for demonstration and determination of antibodies to it in sera from mice and rabbits.

Bacillus piliformis antigens were demonstrated in smear preparations from infected mouse livers by direct immunofluorescence technique. Mouse serum antibodies against B. piliformis were demonstrated by indirect immunofluorescence technique. The test was employed quantitatively both on sera from experimentally infected mice and on sera from clinically healthy mice from colonies infected with B. piliformis, and could be used for the quantitative demonstration of antibodies in sera from a stock of rabbits with Tyzzer's disease. It was found very useful for the detection of subclinical infection.

Studies on Tyzzer's disease in rats.

An outbreak of an epidemic disease occurred in a specified-pathogen-free (SPF) breeding colony of rats. The clinical signs and the post-mortem findings were characteristic for Tyzzer's disease. The causative agent, Bacillus piliformis, was demonstrated microscopically in ileum, liver and myocardium, and transmitted to mice where its pathogenicity appeared to be similar to that of another strain isolated from mice. B. piliformis from spontaneously-infected rats was demonstrated by indirect immunofluorescence technique. By means of the same technique it was found that the fluorescence antibody titre obtained of the individual sera from spontaneously-infected mice, rats and rabbits was the same, whether the antigen employed was organisms isolated from rats or mice. By testing sera from healthy rats in 3 different colonies by use of immunofluorescence technique, antibodies were found in several sera.

The influence of Bacillus piliformis (Tyzzer) infections on the reliability of pharmacokinetic experiments in mice.

The half-lives of warfarin and trimethoprim were significantly longer in mice acutely infected with Bacillus piloformis and in mice which ad clinically recovered from previous experimental infection with the organism. The volume of distribution of trimethoprim but not of warfarin was significantly greater in infected mice than in controls. Body clearances of warfarin was significantly reduced in both disease states. For trimethoprim this parameter was only reduced in the acute state of the disease. The importance of careful control of Tyzzer's disease in laboratory animals for use in pharmacological research is stressed.

Sensory and pulmonary irritation of inhaled n-butylamine in CF-1 and NMRI mice.

Sensory and pulmonary irritation of butylamine was investigated in CF-1 and NMRI mice according to the American standard test method (ASTM E981-84). The method is based on the reflexively induced reduction of the respiratory rate of mice, when exposed to chemical irritants. Sensory irritation was investigated in normal mice, yielding RD50 values (concentration which reduces the respiratory rate by 50%) of 121 and 246 ppm for CF-1 and NMRI mice, respectively. The concentration-effect curves were parallel, but had significantly different elevations, indicating a lower sensitivity of NMRI mice. Pulmonary irritation was investigated in mice, inhaling through a tracheal cannula, yielding RD50 values of 300 and 362 ppm for CF-1 and NMRI mice, respectively. No statistically significant difference between either the slopes or the elevations of the concentration-effect curves was found, indicating the same level of sensitivity of CF-1 and NMRI mice regarding pulmonary irritation. It can be concluded that the 2 mice stocks gave qualitatively comparable responses, but regarding sensory irritation they responded differently quantitatively. Thus for sensory irritation investigations the RD50 values obtained with NMRI mice should be multiplied by 0.49 to obtain comparable values to those, expected in the recommended stock given by E981-84.