Behavioural and physiological stress responses to handling in wild guanacos

Both ethology and physiology can provide insights about stress conditions in wild animals during handling. Lama guanicoe (guanaco) is the major large herbivore inhabiting arid zones in Argentina. Since 2005, the Payún Matrú Cooperative, a business established and run by native people, has captured and handled guanacos for shearing at Payunia Reserve, Mendoza Province, Argentina, to market the species’ fibre for clothing and other products. The aim of our study was to evaluate the behavioural and physiological stress responses to handling of wild guanacos during these shearing activities. We evaluated stress conditions in guanacos by monitoring the frequency of agonistic behaviour in the holding corrals, following capture, the rate of vocalisation and agonistic behaviour during handling, and by estimating cortisol levels in handled animals. Crowding increased agonistic behaviour; this appeared to be related to dominance conflicts between males in the corrals. Time of corralling increased rate of agonistic behaviour and vocalisations during handling. The rate of behavioural stress responses was negatively related to cortisol levels in males; which may be due to animal fatigue or because behavioural stress responses may help mitigate physiological stress responses. Incorporating our results into animal welfare practices could help reduce stress conditions in wild guanacos. Our results suggest that both behavioural and physiological responses are important measures of stress in handled animals, and that behavioural stress responses cannot be used as a simple surrogate for glucocorticoid levels.     

All hematopoietic cells develop from hematopoietic stem cells through Flk2/Flt3-positive progenitor cells

While it is clear that a single hematopoietic stem cell?(HSC) is capable of giving rise to all other hematopoietic cell types, the differentiation paths beyond HSC remain controversial. Contradictory reports on?the lineage potential of progenitor populations have questioned their physiological contribution of progenitor populations to multilineage differentiation. Here, we established a lineage tracing mouse model that enabled direct assessment of differentiation pathways in?vivo. We provide definitive evidence that differentiation into all hematopoietic lineages, including megakaryocyte/erythroid cell types, involves Flk2-expressing non-self-renewing progenitors. A Flk2+ stage was used during steady-state hematopoiesis, after irradiation-induced stress and upon HSC transplantation. In contrast, HSC origin and maintenance do not include a Flk2+ stage. These data demonstrate that HSC specification and maintenance are Flk2 independent, and that hematopoietic lineage separation occurs downstream of Flk2 upregulation.     

Mechanism of Infrared Detection and Transduction by Beetle Melanophila Acuminata In memory of Jerry Wolken

The Melanophila acuminata beetle is attracted to forest fires via a pair of infrared sensory organs composed of sensilla. Our histological work showed that each sensillum contains lipid layers surrounding a protein layer and a unique polysaccharide base that is associated with a neuron to each sensillum. Infrared microscopy showed that the protein region maximally absorbs infrared radiation at 3 μm wavelength and at 10 μm, which corresponds to the known radiation produced by forest fires at 3 μm.Mathematical calculations showed that the physical properties of the sensilla are such that the expected temperature rise is insufficient for transduction of the infrared signal through mechanical means or as a thermal receptor as previously thought;hence the protein plays the pivotal role in perception of single photons and transmission of the signal within the sensilla.     

Artificial cilia of magnetically tagged polymer nanowires for biomimetic mechanosensing

Polymeric nanowires of polypyrrole have been implemented as artificial cilia on giant-magneto-resistive multilayer sensors for a biomimetic sensing approach. The arrays were tagged with a magnetic material, the stray field of which changes relative to the underlying sensor as a consequence of mechanical stimuli which are delivered by a piezoactuator. The principle resembles balance sensing in mammals. Measurements of the sensor output voltage suggest a proof of concept at frequencies of around 190 kHz and a tag thickness of ～300 nm. Characterization was performed by scanning electron microscopy and magnetic force microscopy. Micromagnetic and finite-element simulations were conducted to assess basic sensing aspects.     

Using an adherent cell culture of the mouse subependymal zone to study the behavior of adult neural stem cells on a single-cell level

A comprehensive understanding of the cell biology of adult neural stem cells (aNSCs) requires direct observation of aNSC division and lineage progression in the absence of niche-dependent signals. Here we describe a culture preparation of the adult mouse subependymal zone (SEZ), which allows for continuous single-cell tracking of aNSC behavior. The protocol involves the isolation (approximately 3 h) and culture of cells from the adult SEZ at low density in the absence of mitogenic growth factors in chemically defined medium and subsequent live imaging using time-lapse video microscopy (5-7 d); these steps are followed by postimaging immunocytochemistry to identify progeny (approximately 7 h). This protocol enables the observation of the progression from slow-dividing aNSCs of radial/astroglial identity up to the neuroblast stage, involving asymmetric and symmetric cell divisions of distinct fast-dividing precursors. This culture provides an experimental system for studying instructive or permissive effects of signal molecules on aNSC modes of cell division and lineage progression.     

Impact of competition from wheat and below-ground herbivory on growth and reproduction of scentless chamomile, Tripleurospermum perforatum (Mérat) Laínz

Abstract: This study investigated the effect of competition from wheat and below ground herbivory on the growth and reproduction of scentless chamomile, Tripleurospermum perforatum (Mérat) Laínz (Asteraceae), a target plant for classical biological control. Field cages, in which scentless chamomile was planted, were established in 1994 near Neuenburg (Rhine Valley, Germany), and two weevil species, Diplapion confluens Kirby and Coryssomerus capucinus (Beck), were released alone (40 adults each) or together in a substitutive design (20 adults each). Wheat was sown alone or in combination with both herbivores as an additional stress factor. To test the cage effect on plant growth, an uncaged control was set up. At the end of the experiment, caged control plants were about 20 cm (18%) higher, and allocated more biomass to shoots and less to roots and seeds than uncaged plants. Competition from wheat reduced the number of shoots per T. perforatum plant from 7.6 to 3.2. As a consequence, the biomass of scentless chamomile plants that competed with wheat was reduced by 39% and reproductive output by 49%, compared with plants that were grown without competition. At the end of the experiment, 70–80% of T. perforatum plants had been attacked by an average of two to three D. confluens and 60–70% of plants by one to two C. capucinus . At these densities that were lower than expected, the two herbivores alone or in combination had no significant effect on any of the plant parameters measured. However, in the presence of wheat, herbivory further reduced the number of shoots per plant. We conclude that control of scentless chamomile using insect biocontrol agents will be more likely to be successful if agent densities are high, and agents are released in habitats where scentless chamomile is competing with other plant species.     

Molecular phylogeny of Megaloceros giganteus--the giant deer or just a giant red deer?

Two fragments of mitochondrial DNA (mtDNA) of the cytochrome b gene (137 bp and 167 bp) were successfully isolated and sequenced from antlers and bones of five specimens of the Giant Deer (Megaloceros giganteus) to examine the phylogenetic position of Megaloceros giganteus within the family Cervidae. This is the first report on ancient DNA (aDNA) sequences from Megaloceros giganteus. A phylogenetic analysis based on parameter-rich models describes the evolutionary relationships between five individuals of fossil Megaloceros giganteus and 37 individuals of 11 extant species of the family Cervidae. The results support a "Cervus-Megaloceros" clade. The phylogenetic positions of sympatric Megaloceros and Cervus elaphus specimens in particular indicate either that the Megaloceros mtDNA gene pool did not evolve for a substantial time period as an entity distinct from Cervus elaphus until its extinction, or that Megaloceros contributed mtDNA to Cervus elaphus or vice versa. The results of this study allow the conclusion that the European Megaloceros giganteus is more related to its modern regional counterparts of the species of Cervus elaphus than recent claims have suggested.     

Effect of branched-chain fatty acid on lipid dynamics in mice lacking liver fatty acid binding protein gene

Although a role for liver fatty acid protein (L-FABP) in the metabolism of branched-chain fatty acids has been suggested based on data obtained with cultured cells, the physiological significance of this observation remains to be demonstrated. To address this issue, the lipid phenotype and metabolism of phytanic acid, a branched-chain fatty acid, were determined in L-FABP gene-ablated mice fed a diet with and without 1% phytol (a metabolic precursor to phytanic acid). In response to dietary phytol, L-FABP gene ablation exhibited a gender-dependent lipid phenotype. Livers of phytol-fed female L-FABP–/– mice had significantly more fatty lipid droplets than male L-FABP–/– mice, whereas in phytol-fed wild-type L-FABP+/+ mice differences between males and females were not significant. Thus L-FABP gene ablation exacerbated the accumulation of lipid droplets in phytol-fed female, but not male, mice. These results were reflected in the lipid profile, where hepatic levels of triacylglycerides in phytol-fed female L-FABP–/– mice were significantly higher than in male L-FABP–/– mice. Furthermore, livers of phytol-fed female L-FABP–/– mice exhibited more necrosis than their male counterparts, consistent with the accumulation of higher levels of phytol metabolites (phytanic acid, pristanic acid) in liver and serum, in addition to increased hepatic levels of sterol carrier protein (SCP)-x, the only known peroxisomal enzyme specifically required for branched-chain fatty acid oxidation. In summary, L-FABP gene ablation exerted a significant role, especially in female mice, in branched-chain fatty acid metabolism. These effects were only partially compensated by concomitant upregulation of SCP-x in response to L-FABP gene ablation and dietary phytol. gene targeting; phytanic acid