Population modelling and genetics of a critically endangered Madagascan palm Tahina spectabilis

Madagascar is home to 208 indigenous palm species, almost all of them endemic and >80% of which are endangered. We undertook complete population census and sampling for genetic analysis of a relatively recently discovered giant fan palm, the Critically Endangered Tahina spectablis in 2008 and 2016. Our 2016 study included newly discovered populations and added to our genetic study. We incorporated these new populations into species distribution niche model (SDM) and projected these onto maps of the region. We developed population matrix models based on observed demographic data to model population change and predict the species vulnerability to extinction by undertaking population viability analysis (PVA). We investigated the potential conservation value of reintroduced planted populations within the species potential suitable habitat. We found that the population studied in 2008 had grown in size due to seedling regeneration but had declined in the number of reproductively mature plants, and we were able to estimate that the species reproduces and dies after approximately 70 years. Our models suggest that if the habitat where it resides continues to be protected the species is unlikely to go extinct due to inherent population decline and that it will likely experience significant population growth after approximately 80 years due to the reproductive and life cycle attributes of the species. The newly discovered populations contain more genetic diversity than the first discovered southern population which is genetically depauperate. The species appears to demonstrate a pattern of dispersal leading to isolated founder plants which may eventually lead to population development depending on local establishment opportunities. The conservation efforts currently put in place including the reintroduction of plants within the species potential suitable habitat if maintained are thought likely to enable the species to sustain itself but it remains vulnerable to anthropogenic impacts.     

Some conditions apply: Systems for studying Plasmodium falciparum protein function

Malaria, caused by infection with Plasmodium parasites, remains a significant global health concern. For decades, genetic intractability and limited tools hindered our ability to study essential proteins and pathways in Plasmodium falciparum, the parasite associated with the most severe malaria cases. However, recent years have seen major leaps forward in the ability to genetically manipulate P. falciparum parasites and conditionally control protein expression/function. The conditional knockdown systems used in P. falciparum target all 3 components of the central dogma, allowing researchers to conditionally control gene expression, translation, and protein function. Here, we review some of the common knockdown systems that have been adapted or developed for use in P. falciparum. Much of the work done using conditional knockdown approaches has been performed in asexual, blood-stage parasites, but we also highlight their uses in other parts of the life cycle and discuss new ways of applying these systems outside of the intraerythrocytic stages. With the use of these tools, the field’s understanding of parasite biology is ever increasing, and promising new pathways for antimalarial drug development are being discovered.     

Variation in Fine Root Characteristics and Nutrient Dynamics Across Alaskan Ecosystems

Ecosystems - Carbon cycle perturbations in high-latitude ecosystems associated with rapid warming can have implications for the global climate. Belowground biomass is an important component of the...     

Honest signals and sexual conflict: Female lizards carry undesirable indicators of quality

Sex differences in animal coloration often result from sex‐dependent regulatory mechanisms. Still, some species exhibit incomplete sexual dimorphism as females carry a rudimentary version of a costly male trait, leading to intralocus sexual conflict. The underlying physiology and condition dependence of these traits can inform why such conflicts remain unresolved. In eastern fence lizards (Sceloporus undulatus), blue iridophore badges are found in males and females, but melanin pigmentation underneath and surrounding badges is male‐exclusive. We track color saturation and area of badges across sexual maturity, and their relationship to individual quality (body condition and immunocompetence) and relevant hormones (testosterone and corticosterone). Saturation and testosterone were positively correlated in both sexes, but hormone and trait had little overlap between males and females. Saturation was correlated with body condition and immunocompetence in males but not in females. Co‐regulation by androgens may have released females from resource allocation costs of color saturation, even when in high condition. Badge area was independent of testosterone, but associated with low corticosterone in females, indicating that a nonsex hormone underlies incomplete sexual dimorphism. Given the evidence in this species for female reproductive costs associated with ornamentation, this sex‐nonspecific regulation of an honest signal may underlie intralocus sexual conflict.     

Fish hypnosis: Induction of an atonic immobility reflex

An immobility reflex may be induced in fish by a vigorous flow of water through the branchial chamber. The reflex was observed in 22 species representing bony and cartilaginous fishes from diverse habitats, and was invariably characterised by loss of caudal muscle tone and limp posture. The immobilised state may be maintained for many hours, and revival is instantaneous. The critical flow rate for induction increases with increasing body size in the snapper, Pagrus auratus, and heart rate falls below the resting rate. In addition, haematological parameters, and plasma lactate after 6?h were typical of resting fish. Although the mechanism is unclear, and the selective advantage for the fish unknown, pressure-sensitive receptors in the branchial chamber are likely to be involved. Application in live fish transport, and recovery from handling and exercise stressors is suggested.     

Factors Affecting Penetrating Captive Bolt Gun Performance

Captive bolt stunning is used for rendering livestock insensible at slaughter. The mechanical factors relating to performance of 6 penetrating captive bolt gun (CBG) models were examined. The Matador Super Sécurit 3000 and the .25 Cash Euro Stunner had the highest kinetic energy values (443 J and 412 J, respectively) of the CBGs tested. Ninety percent (27/30) of CBGs held at a government gun repository (United Kingdom) were found to have performed at a normal standard for the model, while 53% (10/19) of commercial contractor CBGs tested were found to underperform for the gun model. When the .22 Cash Special was fired 500 times at 4 shots per min, the gun reached a peak temperature of 88.8°C after 2.05 hr. Repeat firing during extended periods significantly reduced the performance of the CBG. When deciding on the appropriate CBG/cartridge combination, the kinetic energy delivered to the head of the nonhuman animal, bolt penetration depth, and species/animal type must be considered. It is recommended that CBGs are routinely checked for wear to the bolt and barrel if they are repeatedly fired in a session.     

Is Maternal Marriage Beneficial for Low-Income Adolescents?

The present study investigated the association of mothers' marriage and changes in young adolescents' cognitive and socioemotional development and changes in family processes. Analyses employed longitudinal data from the Three-City Study to track maternal partnerships for 860 low-income adolescents (10–14 years-old in Wave 1) across a 16 month period. No short-term benefits or risks emerged for youth when mothers entered marriage, with few changes in family or maternal functioning linked with marriage formation as well. In contrast, adolescents in stably married families experienced improved academic, behavioral, and psychological well-being compared to youth in stable cohabiting or single-parent families. Stable marriage was similarly linked to improvements across multiple domains of home and mothers' functioning. These patterns were not moderated by the male partner's identity (biological father or stepfather). Results support the benefits of stable marriage on youth development, but suggest that policies supporting movements into new marriages may not result in improved adolescent or family functioning, at least in the short term.     

Inter- and intra-individual variation in plasma and red blood cell vitamin E after supplementation

To establish the range of individual blood responses to supplemental vitamin E, 30 healthy subjects ingested 75 mg of deuterium-labelled α-tocopherol with a standard breakfast. Blood was collected at 6, 9, 12, 27 and 51 h post ingestion and deuterated (d₆) and non-deuterated (d₀) α-tocopherol concentrations were determined in plasma and red blood cells (RBC) by GC-MS. To examine intra-individual responses, 6 of these subjects were re-examined at 6-month intervals over a 30-month period. Post ingestion, the amount of d₆-α-tocopherol in blood increased rapidly with time with maximal concentrations seen at 12 h (plasma) and 27 h (RBC) in most subjects. At these times, d₆-α-tocopherol concentration ranged from 0.3–12.4 μmol/l in plasma and 0.6–4.09 μmol/l packed cell in RBC. Area under the curve calculations indicated inter-individual differences of α-tocopherol uptake to be 40-fold for plasma (12.9–493.3 μmol h/l) and 6-fold for RBC (24.4–146.1 μmol h/l packed RBC). Intra-individual variation in α-tocopherol uptake was small in comparison and remained relatively constant over the 30-month period. We conclude that vitamin E uptake varies widely in the normal population, although it is comparatively stable for an individual over time. These differences likely arise from variations in the regulation of vitamin E uptake and metabolism between subjects. Factors regulating this process must be better understood before the optimal intake of vitamin E can be ascertained.