INTRASPECIFIC VARIATION IN DEHYDRATION TOLERANCE: INSIGHTS FROM THE TROPICAL PLANT \u3cem\u3eMARCHANTIA INFLEXA\u3c/em\u3e

Plants are threatened by global change, increasing variability in weather patterns, and associated abiotic stress. Consequently, there is an urgent need to enhance our ability to predict plant community dynamics, shifts in species distributions, and physiological responses to environmental challenges. By building a fundamental understanding of plant stress tolerance, it may be possibly to protect the ecological services, economic industries, and communities that depend on plants. Dehydration tolerance (DhT) is an important mechanism of water stress tolerance with promising translational applications. Here, I take advantage natural variation in DhT to gain a deeper insight into this complex trait. In addition, I address questions related to the causes and consequences of sexual dimorphisms in DhT. Understanding sexual dimorphisms in stress tolerance is critical because these dimorphisms can drive spatial segregation of the sexes, biased sex ratios, and may ultimately reduce sexual reproduction and population persistence. This work takes an integrated approach, addressing DhT on multiple scales from ecology, to physiology, to genomics in the tropical liverwort Marchantia inflexa. Initially, I tested for correlations between DhT and environmental dryness, sex differences in DhT, and genetic vs. plastic contributions to DhT variability. I found that patterns of variation in DhT are associated with environmental variability, including complex sexual dimorphisms, and derive from a combination of plasticity and genetic differences in DhT. Subsequently, I leveraged the variability in DhT to identify candidate DhT enhancing genes. In M. inflexa intraspecific differences in DhT are impacted by baseline variability among plants, as well as unique gene expression responses initiated during drying. In parallel, I assembled a draft genome assembly for M. inflexa, which was employed to investigate questions of sex chromosome evolution and sexual dimorphism in DhT. Finally, the bacteriome of M. inflexa was characterized and found to be extremely diverse and variable. Collectively, this work adds to a growing understanding of DhT and highlights the importance of sampling approaches that seek to comprehensively describe variability in DhT. I detected complex patterns of variability in DhT among populations and the sexes of M. inflexa, which were used to gain insight into the genetic intricacies of DhT

First results of a Middle Stone Age survey in the Kerma region, northern Sudan

Sudan is a vitally important region for understanding the migrations of Anatomically Modern Humans from the African continent. Here, the authors present the results of a preliminary survey in the Kerma region, during which, 16 new Middle Stone Age sites were discovered.FCT: UID/ARQ/04211/2019-ICArEHBinfo:eu-repo/semantics/publishedVersio

Two Decades of Desiccation Biology: A Systematic Review of the Best Studied Angiosperm Resurrection Plants

Resurrection plants have an extraordinary ability to survive extreme water loss but still revive full metabolic activity when rehydrated. These plants are useful models to understand the complex biology of vegetative desiccation tolerance. Despite extensive studies of resurrection plants, many details underlying the mechanisms of desiccation tolerance remain unexplored. To summarize the progress in resurrection plant research and identify unexplored questions, we conducted a systematic review of 15 model angiosperm resurrection plants. This systematic review provides an overview of publication trends on resurrection plants, the geographical distribution of species and studies, and the methodology used. Using the Preferred Reporting Items for Systematic reviews and Meta–Analyses protocol we surveyed all publications on resurrection plants from 2000 and 2020. This yielded 185 empirical articles that matched our selection criteria. The most investigated plants were Craterostigma plantagineum (17.5%), Haberlea rhodopensis (13.7%), Xerophyta viscosa (reclassified as X. schlechteri) (11.9%), Myrothamnus flabellifolia (8.5%), and Boea hygrometrica (8.1%), with all other species accounting for less than 8% of publications. The majority of studies have been conducted in South Africa, Bulgaria, Germany, and China, but there are contributions from across the globe. Most studies were led by researchers working within the native range of the focal species, but some international and collaborative studies were also identified. The number of annual publications fluctuated, with a large but temporary increase in 2008. Many studies have employed physiological and transcriptomic methodologies to investigate the leaves of resurrection plants, but there was a paucity of studies on roots and only one metagenomic study was recovered. Based on these findings we suggest that future research focuses on resurrection plant roots and microbiome interactions to explore microbial communities associated with these plants, and their role in vegetative desiccation tolerance

Domain-based perceptions of risk:a case study of lay and technical community attitudes towards managed aquifer recharge

Despite growing water scarcity, communities in many parts of the developed world often reject technically and economically sound options for water augmentation. This paper reports findings from a study investigating risk perceptions associated with a proposed Managed Aquifer Recharge scheme in Australia. Q-Methodology was used to compare decision-making frameworks of lay community and „technical expert‟ participants. Technical expert participants were also asked to approximate the decision-making framework of a „typical‟ community member. The emerging contrasts between lay community frameworks and those approximated by technical experts suggest that there are prevailing yet errant assumptions about lay community attitudes towards new technologies. The findings challenge the characterisation of the lay community and technical experts as being in entrenched opposition with one another

Measures of viability in isolated cells

Various methods were compared for estimation of cell viability. Cell count, uptake of trypan blue, release of cellular LDH, as well as cell contents of K+ and Na+ were determined in leukocytes, spleen cells, and Ehrlich cells exposed to adverse conditions. After incubation of these cells with NaF, the cell count remained essentially constant; the extent of cell staining and release of LDH increased to a limited level in suspensions of leukocytes and spleen cells and was virtually unchanged in experiments with Ehrlich cells. On the other hand, pretreatment with NaF induced rapid and marked changes in contents of K+ and Na+ in all three cell types. Exposure of the cells to hypertonic conditions caused more pronounced, but similar overall effects. As a consequence of increased tonicity, the cell count decreased and considerable leakage of LDH occurred in all the cells investigated. Whereas the contents of K+ and Na+ in all pretreated cells changed markedly, the cellular uptake of trypan blue was again the least responsive index of cell permeability. The results showed cell staining by trypan blue to be a relatively poor measure of cell viability and suggest use of the ratio cellular K+/Na+ or, even more efficiently, the cell content of K+ as sensitive indicators of plasma membrane integrity.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/22041/1/0000459.pd

No direct evidence for the presence of Nubian Levallois technology and its association with Neanderthals at Shukbah Cave

Blinkhorn et al.present a reanalysis of fossil and lithic material from Garrod’s 1928 excavation at Shukbah Cave, identifying the presence of Nubian Levallois cores and points in direct association with a Neanderthal molar. Te authors argue that this demonstrates the Nubian reduction strategy forms a part of the wider Middle Palaeolithic lithic repertoire, therefore its role as a cultural marker for Homo sapiens population movements is invalid. We raise the following four major concerns: (1) we question the assumptions made by the authors about the integrity and homogeneity of the Layer D assemblage and (2) the implications of this for the association of the Neanderthal tooth with any specifc component of the assemblage, (3) we challenge the authors’ attribution of lithic material to Nubian Levallois technology according to its strict defnition, and (4) we argue that the comparative data presented derive from a biased sample of sites. Tese points critically undermine the article’s conclusion that Shukbah’s Neanderthals made Nubian cores and thus the argument that Neanderthals might have made Nubian technology elsewhere is unsubstantiated.info:eu-repo/semantics/publishedVersio

Rethinking democracy promotion

Despite the fact that democracy promotion is a major part of liberal foreign policies, the discipline of International Relations has not paid much systematic attention to it. Conversely, the study of democracy promotion is dominated by comparative politics and pays hardly any attention to the international system. This mutual neglect signifies a core weakness in the theory and practice of democracy promotion: its failure to comprehend the development of liberal democracy as an international process. This article argues that a thorough engagement with John Locke explains the failures of democracy promotion policies and provides a more comprehensive understanding of the development of liberal democrac

Nubian Complex reduction strategies in Dhofar, southern Oman

AbstractBetween 2010 and 2012, the Dhofar Archaeological Project has located and mapped 260 Nubian Complex occurrences across Dhofar, southern Oman. Many of these lithic assemblages are technologically homologous to the Late Nubian Industry found in Africa, while others may represent a local industry derived from classic Nubian Levallois technology. The purpose of this paper is to describe the various reduction strategies encountered at a sample of Nubian Complex sites from Dhofar, to explore inter-assemblage variability, and, ultimately, to begin to articulate technological units within the “Dhofar Nubian Tradition.” To achieve this aim, we have developed an analytical scheme with which to describe variability among Nubian Levallois reduction strategies. From our analysis, we are able to discern at least two distinct industries within a regional lithic tradition. Demographic implications of the enduring Dhofar Nubian Tradition are considered in light of new evidence found throughout the Arabian Peninsula