A novel causal mechanism for grey squirrel bark stripping: The Calcium Hypothesis

AbstractGrey squirrels, Sciurus carolinensis, damage trees in the UK by stripping bark and eating the underlying phloem; squirrel motivation for damage is, however, unknown. Damage can result in deterioration of timber quality and a significant economic toll on the forestry industry. Prediction of severe damage followed by targeted killing of squirrels is the current recommended management option. However, the use of warfarin (an anticoagulant poison) is now restricted in the UK and other more humane methods of killing are labour-intensive, so an alternative solution is needed. A better understanding of what motivates grey squirrels to strip bark may enable a preventive approach to be developed. Whilst the bark stripping literature has explored predictive factors affecting the likelihood of damage, causal understanding is lacking. The aim of this review is to introduce the Calcium Hypothesis as a possible explanation for bark stripping, with a view to informing the prevention of damage. The Calcium Hypothesis states that grey squirrels damage trees to ameliorate a calcium deficiency. The main predictive factors of bark stripping behaviour each inform and lend support to the Calcium Hypothesis. Calcium is stored in tree phloem, and damage increases with phloem width, providing squirrels with more calcium per unit area ingested. Calcium levels increase in trees as active growth resumes after winter dormancy, this occurs immediately prior to the main bark stripping season of May–July, and trees growing most vigorously are at increased risk of damage. It is likely grey squirrels also have a requirement for calcium during the bark stripping season. Adult females will be under post-parturition pressures such as lactation, and juveniles will be going through their main period of bone growth, both of which likely represent a requirement for calcium – which supports an observed positive correlation between juvenile abundance and bark stripping. A high autumnal seed crop increases juvenile recruitment the following spring, and could also induce a requirement for calcium to a population due to the high phosphorus to calcium ratio of seeds. To further investigate the hypothesis, the extent to which grey squirrels can utilise calcium oxalate, as calcium occurs in bark, should be determined, and also the extent to which grey squirrels undergo seasonal periods of calcium deficiency. Increasing our causal understanding of bark stripping could inform the future development of preventive measures to aid forest management

Stories from the field:Women's networking as gender capital in entrepreneurial ecosystems

Women are underrepresented in successful entrepreneurial ecosystems and the creation of women-only entrepreneurial networks has been a widespread policy response. We examine the entrepreneurial ecosystem construct and suggest that it, and the role networks play in entrepreneurial ecosystems, can be analysed in terms of Bourdieu's socio-analysis as field, habitus and capital. Specifically, we develop the notion of gender capital as the skill set associated with femininity or from simply being recognized as feminine. We apply this to the development of women's entrepreneurial networks as a gender capital enhancing initiative. Using data from qualitative interviews with network coordinators and women entrepreneurs we reflect on the extent to which formally established women-only networks generate gender capital for their members and improve their ability to participate in the entrepreneurial ecosystem. The paper concludes by drawing out the implications of our analysis for theory, entrepreneurial practice and economic development policy

Subtle Alterations in PCNA-Partner Interactions Severely Impair DNA Replication and Repair

Dynamic switching of PCNA-partner interactions is essential for normal DNA replication and repair in yeast

Inhalation of rod-like carbon nanotubes causes unconventional allergic airway inflammation

Peer reviewe

Severe Covid-19 vaccine side-effects are rare in older adults yet are linked with depressive symptoms

It is the purpose of this paper to provide an exposition of a cohomological deformation theory for braided monoidal categories, an exposition and proof of a very general theorem of the form “all quantum invariants are Vassiliev invariants, ” and to relate to the existence of the Vassilie

Severe Covid-19 vaccine side-effects are rare in older adults yet are linked with depressive symptoms

COVID-19 vaccine development should have been the “light at the end of the tunnel.” However, antivaccinations attitudes and hesitation are common,1 even among older adults. Such hesitancy has been positively associated with depression, potentially due to concerns about vaccine side-effects.2 We tested the association between depression and vaccine side-effects in older adults, and hypothesized that, like physical illness,3 depression should increase with each additional side-effect. This survey was conducted via iPanel (a probability based panel, see4 for additional details) to obtain good representation of vaccinated Israeli older adults (N = 939, mean age 68.9 ± 3.43 [range 65–85]; 59.9% females, 46.9% academic education; 75% married). At time of study (January 25th-February 4th, 2021), respondents were 28.15 ± 9.47 days after the first Pfizer vaccine [BNT162b2mRNA]. Participants completed web-based questionnaires comprising demographics, self-rated health, COVID-19 vaccination side-effects and depressive symptoms. Respondents provided informed consent to procedures approved by the last author's university institutional review board. The extent of suffering from side-effects (reported by the FDA

Spatiotemporal Expression of MANF in the Developing Rat Brain

Mesencephalic astrocyte-derived neurotrophic factor (MANF) is an evolutionarily conserved neurotrophic factor which exhibited neuroprotective properties. Recent studies suggested that MANF may play a role in the neural development of Drosophila and zebra fishes. In this study, we investigated the spatiotemporal expression of MANF in the brain of postnatal and adult rats. MANF expression appeared wide spread and mainly localized in neurons. In the cerebral cortex, neurons in layer IV and VI displayed particularly strong MANF immunoreactivity. In the hippocampus, intensive MANF expression was observed throughout the subfields of Cornu Amonis (CA1, CA2, and CA3) and the granular layer of the dentate gyrus (DG). In the substantia nigra, high MANF expression was shown in the substantia nigra pars compacta (SNpc). In the thalamus, the anterodorsal thalamic nucleus (ADTN) exhibited the highest MANF immunoreactivity. In the hypothalamus, intensive MANF immunoreactivity was shown in the supraoptic nucleus (SON) and tuberomammillary nucleus (TMN). In the cerebellum, MANF was localized in the external germinal layer (EGL), Purkinje cell layer (PCL), internal granule layer (IGL) and the deep cerebellar nuclei (DCN). We examined the developmental expression of MANF on postnatal day (PD) 3, 5, 7, 9, 15, 21, 30 and adulthood. In general, the levels of MANF were high in the early PDs (PD3 and PD5), and declined gradually as the brain matured; MANF expression in the adult brain was the lowest among all time points examined. However, in some structures, such as PCL, IGL, SON, TMN and locus coeruleus (LC), high expression of MANF sustained throughout the postnatal period and persisted into adulthood. Our results indicated that MANF was developmentally regulated and may play a role in the maturation of the central nervous system (CNS)