Piezoelectric harvesting of mechanical energy for redox chemistry.

Much work has been done in the utilization of mechanical force to enable chemical processes. However, this process is limited to thermal- and deformation-driven reactions. In fact, the transfer of energy in mechanical reactors can be quite inefficient, with energy lost to heat and mechanical deformation. Although these losses diminish at larger scales, small-scale reactions (from a few milligrams to a kilogram) can suffer from unfavorable energy demands. Recent work has sought to harvest unused energy in mechanical reactors by converting it to a flow of electrons through the use of piezoelectric materials, as many economically important reactions rely on the transfer of electrons to enact chemical change. Recent work has shown that the addition of piezoelectric powders to mechanochemical reactions results in enhanced yields for reductive and oxidative chemistry. However, these materials ultimately contaminate the end product and must be removed. Additionally, impacts on a piezoelectric material produce an AC output; limiting this approach's usefulness to irreversible reactions. We have developed a cleaner approach using an external piezoelectric element to either supply or sink electrons during milling. Methylene blue was reduced to leucomethylene blue using our approach. Mechanochemical reaction rates for this reduction were determined with respect to media quantities and sizes with a maximum rate of 7.76 µM s-1. It was found that the conversion rate is linearly dependent on the number of media and geometrically dependent on the size of the media. Our approach allows selective reduction and eliminates contamination of the products with piezoelectric material. Shuttling electrons in a mechanochemical reaction will enable difficult chemistry, such as the reduction of CO2 or the production of low oxidation state inorganic compounds, to be achieved more easily.

Necropsy protocol for newborn mice.

Neonatal mortality is high in laboratory mouse breeding, and causes are poorly understood. Post-mortem analysis of pups is an often overlooked source of information and insight. We present a necropsy protocol for neonatal mice designed for easy practical application by animal technicians.

All the Pups We Cannot See: Cannibalism Masks Perinatal Death in Laboratory Mouse Breeding but Infanticide Is Rare.

Perinatal mortality is a major issue in laboratory mouse breeding. We compared a counting method using daily checks (DAILY_CHECK) with a method combining daily checks with detailed video analyses to detect cannibalisms (VIDEO_TRACK) for estimating the number of C57BL/6 pups that were born, that died and that were weaned in 193 litters from trios with (TRIO-OVERLAP) or without (TRIO-NO_OVERLAP) the presence of another litter. Linear mixed models were used at litter level. To understand whether cannibalism was associated with active killing (infanticide), we analysed VIDEO_TRACK recordings of 109 litters from TRIO-OVERLAP, TRIO-NO_OVERLAP or SOLO (single dams). We used Kaplan-Meier method and logistic regression at pup level. For DAILY_CHECK, the mean litter size was 35% smaller than for VIDEO_TRACK (p < 0.0001) and the number of dead pups was twice lower (p < 0.0001). The risk of pup loss was higher for TRIO-OVERLAP than TRIO-NO_OVERLAP (p < 0.0001). A high number of pup losses occurred between birth and the first cage check. Analyses of VIDEO_TRACK data indicated that pups were clearly dead at the start of most of the cannibalism events and infanticide was rare. As most pups die and disappear before the first cage check, many breeding facilities are likely to be unaware of their real rates of mouse pup mortality.

Progressing the care, husbandry and management of ageing mice used in scientific studies.

Driven by the longer lifespans of humans, particularly in Westernised societies, and the need to know more about 'healthy ageing', ageing mice are being used increasingly in scientific research. Many departments and institutes involved with ageing research have developed their own systems to determine intervention points for potential refinements and to identify humane end points. Several good systems are in use, but variations between them could contribute to poor reproducibility of the science achieved. Working with scientific and regulatory communities in the UK, we have reviewed the clinical signs observed in ageing mice and developed recommendations for enhanced monitoring, behaviour assessment, husbandry and veterinary interventions. We advocate that the default time point for enhanced monitoring should be 15 months of age, unless prior information is available. Importantly, the enhanced monitoring should cause no additional harms to the animals. Where a mouse strain is well characterised, the onset of age-related enhanced monitoring may be modified based on knowledge of the onset of an expected age-related clinical sign. In progeroid models where ageing is accelerated, enhanced monitoring may need to be brought forward. Information on the background strain must be considered, as it influences the onset of age-related clinical signs. The range of ageing models currently used means that there will be no 'one-size fits all' solution. Increased awareness of the issues will lead to more refined and consistent husbandry of ageing mice, and application of humane end points will help to reduce the numbers of animals maintained for longer than is scientifically justified.

High laboratory mouse pre-weaning mortality associated with litter overlap, advanced dam age, small and large litters.

High and variable pre-weaning mortality is a persistent problem in laboratory mouse breeding. Assuming a modest 15% mortality rate across mouse strains, means that approximately 1 million more pups are produced yearly in the EU to compensate for those which die. This paper presents the first large study under practical husbandry conditions to determine the risk factors associated with mouse pre-weaning mortality. We analysed historical records from 219,975 pups from two breeding facilities, collected as part of their management routine and including information on number of pups born and weaned per litter, parents' age and identification, and dates of birth and death of all animals. Pups were counted once in their first week of life and at weaning, and once every one or two weeks, depending on the need for cage cleaning. Dead pups were recorded as soon as these were found during the daily cage screening (without opening the cage). It was hypothesized that litter overlap (i.e. the presence of older siblings in the cage when new pups are born), a recurrent social configuration in trio-housed mice, is associated with increased newborn mortality, along with advanced dam age, large litter size, and a high number and age of older siblings in the cage. The estimated probability of pup death was two to seven percentage points higher in cages with litter overlap compared to those without. Litter overlap was associated with an increase in death of the entire litter of five and six percentage points, which represent an increase of 19% and 103% compared to non-overlapped litters in the two breeding facilities, respectively. Increased number and age of older siblings, advanced dam age, small litter size (less than four pups born) and large litter size (over 11 pups born) were associated with increased probability of pup death.

Heterochronic faecal transplantation boosts gut germinal centres in aged mice.

Ageing is a complex multifactorial process associated with a plethora of disorders, which contribute significantly to morbidity worldwide. One of the organs significantly affected by age is the gut. Age-dependent changes of the gut-associated microbiome have been linked to increased frailty and systemic inflammation. This change in microbial composition with age occurs in parallel with a decline in function of the gut immune system; however, it is not clear whether there is a causal link between the two. Here we report that the defective germinal centre reaction in Peyer's patches of aged mice can be rescued by faecal transfers from younger adults into aged mice and by immunisations with cholera toxin, without affecting germinal centre reactions in peripheral lymph nodes. This demonstrates that the poor germinal centre reaction in aged animals is not irreversible, and that it is possible to improve this response in older individuals by providing appropriate stimuli.

Gene expression profiling in porcine maternal infanticide: a model for puerperal psychosis.

The etiology of mental disorders remains largely unclear. Complex interactions between genetic and environmental factors are key to the development of such disorders. Puerperal psychosis is the most extreme form of postnatal mood disorder in women. Similarly, parturition in the pig can trigger extreme behavioral disturbances, including maternal infanticide. In this study, we have used a targeted cDNA microarray approach using the pig as a model to understand the genes and genetic pathways that are involved in these processes. Two subtracted cDNA libraries from porcine hypothalamus were constructed, which were enriched for genes that were over-expressed and under-expressed in the aberrant behavioral phenotype, compared to the matched control. In addition to this, a normalized library was constructed from hypothalamus and pituitary samples taken from pigs in a variety of reproductive states. The libraries were partially sequenced and combined represented approximately 5,159 different genes. Microarray analysis determined differences in gene expression between hypothalamus samples from nine matched pairs of infanticidal versus control animals, using a common reference design. Microarray analysis of variance (MAANOVA) identified 52 clones as being differentially expressed (P

Porcine maternal infanticide as a model for puerperal psychosis.

Childbirth is a period of substantial rapid biological and psychological change and a wide range of psychotic disorders can occur ranging from mild 'baby blues' to severe episodes of psychotic illnesses. Puerperal psychosis is the most extreme form of postnatal psychosis, occurring in 1 in 1,000 births. In this study, we have used the pig as an animal model for human postnatal psychiatric illness. Our aim was to identify quantitative trait loci (QTL) associated with maternal (infanticide) sow aggression. This is defined by sows attacking and killing their own newborn offspring, within 24 hr of birth. An affected sib pair whole genome linkage analysis was carried out with 80 microsatellite markers covering the 18 porcine autosomes and the X chromosome, with the aim of identifying chromosomal regions responsible for this abnormal behavior. Analysis was carried out using the non-parametric linkage test of Whittemore and Halpern, as implemented in the Merlin software. The results identified 4 QTL mapping on Sus scrofa chromosomes 2 (SSC2), 10 (SSC10), and X (SSCX). The peak regions of these QTL are syntenic to HSA 5q14.3-15, 1q32, Xpter-Xp2.1, and Xq2.4-Xqter, respectively. Several potential candidate genes lie in these regions in addition to relevant abnormal behavioral QTL, found in humans and rodents.

Prepartum plasma estradiol and postpartum cortisol, but not oxytocin, are associated with interindividual and breed differences in the expression of maternal behaviour in sheep.

Consistent, individual differences in the expression of maternal behaviour have been described in several species including the sheep. The neuroendocrine mechanisms underlying the onset of maternal behaviour in the sheep have been described, although the relationship between hormonal events and individual differences in behaviour has yet to be determined. In this study, we examined whether the individual differences in plasma estradiol, progesterone, oxytocin and cortisol concentrations were related to observed individual and breed differences in maternal behaviours in two breeds of sheep (Scottish Blackface and Suffolk) known to differ in maternal behavioural expression. Maternal estradiol concentration increased rapidly before parturition and was higher in Blackface ewes than Suffolk ewes. Plasma progesterone declined before parturition and was higher in Suffolk than Blackface ewes. Prepartum estradiol, but not progesterone, was related to individual differences in maternal grooming of the lamb. Plasma oxytocin did not differ between breeds in late gestation. There was a tendency for oxytocin to be higher in Blackface than Suffolk ewes immediately after birth. However, there were no significant relationships between prepartum or postpartum oxytocin and any maternal behaviours. Plasma cortisol was higher in Blackface than Suffolk ewes in the last days of pregnancy but rose in both breeds over the last 24 h before parturition and did not differ at delivery. Cortisol peripartum was negatively related to individual differences in maternal affiliative behaviours. These data suggest that estradiol, and potentially cortisol, may mediate individual differences in maternal behaviour in sheep.