The ‘chicken or the egg’: which comes first,forest tree decline or loss of mycorrhizae?

Forest trees are experiencing massive declines globally caused by a multitude of stressors, both abiotic (pollution, fragmentation and climate change) and biotic (fungi, bacteria, viruses and insects). Mycorrhizal fungi aid plants in the requisition of nutrients through their mutualistic relationship with plant roots and are integral to tree health. Stresses affecting tree health will also influence mycorrhizal fungi directly or indirectly, and thus alter the pathways responsible for nutrient absorption. Such an intimate association is a true chicken or egg quandary; do external stressors cause a loss of mycorrhizae which leads to tree decline, does tree decline result in a loss of mycorrhizae, or is it a combination of both? A review of literature has identified six stressors known to contribute to tree decline and to impact directly on mycorrhizae; global climate change, pesticides, heavy metals, excess fertilizer, pathogens and habitat fragmentation. A few review papers have highlighted the link; however, what is missing is irrefutable empirical research. This review documents the known direct impacts of the six stressors on mycorrhizal communities and places this in the context of decline syndromes in long-lived forest trees. We also discuss methodologies available to identify fungi and future research needed to unravel the complex relationships between forest tree declines and their associated mycorrhizal fungi.     

Latino racial choices: the effects of skin colour and discrimination on Latinos’ and Latinas’ racial self-identifications

Abstract

Are predictions that Hispanics will make up 25 per cent of the US population in 2050 reliable? The authors of this paper argue that these and other predictions are problematic insofar as they do not account for the volatile nature of Latino racial and ethnic identifications. In this light, the authors propose a theoretical framework that can be used to predict Latinos’ and Latinas’ racial choices. This framework is tested using two distinct datasets – the 1989 Latino National Political Survey and the 2002 National Survey of Latinos. The results from the analyses of both of these surveys lend credence to the authors’ claims that Latinas’ and Latinos’ skin colour and experiences of discrimination affect whether people from Latin America and their descendants who live in the US will choose to identify racially as black, white or Latina/o.     

Endemism,palaeoendemism and migration: the case for the ‘European endemic’, Mallomonas intermedia

The Synurophyceae is a well-supported clade of ecologically important heterokont algae found largely in freshwater planktonic habitats worldwide, whose members have cell coverings consisting of species-specific siliceous scales overlapped in a highly organized manner. Many synurophytes have been described as endemic and are found only in specific regions of the world. A thriving population of the European endemic, Mallomonas intermedia, was discovered in a remote desert pond situated in the Virgin Valley, Nevada, USA and in a stratigraphic sequence from the middle Eocene fossil locality known as Horsefly in British Columbia, Canada. Both North American finds were closely compared with populations from Europe, confirming the identifications. Before these discoveries, this species was recorded from numerous waterbodies exclusively in Europe, but was lacking from hundreds of sites examined from other continents. Its presence in western North America during the warm middle Eocene confirms that historically this species had a significantly wider distribution and may be best classified as a palaeoendemic. Additional species uncovered from a second fossil locality that are closely related to M. intermedia further support the presence of this lineage in North America during the Eocene. The living population in northern Nevada presents an enigma. Does this remote desert population represent a remnant population that has gone undetected until now, or is it a recent arrival from an unknown region by an unknown vector?     

Structural and Narrative Reconstruction of Rural Residents’ Representations of ‘Nature’, ‘Wildlife’, and ‘Landscape’

The objective of this paper is the structural and narrative reconstruction of representations of ‘nature’, ‘wildlife’ and ‘landscape’, held by rural residents of the Dadia Forest Reserve. Data collection involved in-depth interviews. Employing a social representations’ approach, we recovered representational elements that are expected in the case of rural belief systems, such as negative dispositions towards wolves and foxes, as well as elements of an urban adherence, such as nature’s independence. Representational elements refer to visual aspects of the countryside, which seem compatible with the figurative nucleus of the rural idyll. Concerning ‘wildlife’, residents focused on vultures, which comprise the main tourist attraction of the reserve. Scientific knowledge adds to the complexity of the narrative schema, which corresponds to the representation of ‘wildlife’. Interviewees perceived the rural landscape as an interface between the natural and the human-conditioned environment. Our study shows that interviewees make no reference to environmental conservation or quality of life issues, as it could be expected according to relatively wide definitions of the term ‘environmentalism’. Environmental messages reinforced by ecotourism development seem to be recalled primarily in terms of their compatibility with the perceived economic benefit of local people. Despite ecotourism development, representational elements that diverge from a tourist version of ‘nature’, ‘wildlife’ and ‘landscape’ were not pronounced within rural belief-systems. Further interventions within the study area are needed, in order to address a variety of topics under the environmental conservation discourse and raise the environmental awareness of rural residents.     

Stochasticity or the fatal ‘imperfection’ of cloning

The concept of clone is analysed with the aim of exploring the limits to which a phenotype can be said to be determined geneticaly. First of all, mutations that result from the replication, topological manipulation or lesion of DNA introduce a source of heritable variation in an otherwise identical genetic background. But more important, stochastic effects in many biological processes may superimpose a phenotypic variation which is not encoded in the genome. The source of stochasticity ranges from the random selection of alleles or whole chromosomes to be expressed in small cell populations, to fluctuations in processes such as gene expression, due to limiting amounts of the players involved. The picture emerging is that the term clone is a statistical over-simplification representing a series of individuals having essentially the same genome but capable of exhibiting wide phenotypic variation. Finally, to what extent fluctuations in biological processes, usually thought of as noise, are in fact signal is also discussed.     

Forest decline after a 15-year “perfect storm” of invasion by hemlock woolly adelgid,drought, and hurricanes

Invasions by introduced pests can interact with other disturbances to alter forests and their functions, particularly when a dominant tree species declines. To identify changes after invasion by the insect hemlock woolly adelgid (Adelges tsugae; HWA), coinciding with severe droughts and hurricanes, this study compared tree species composition of eastern hemlock (Tsuga canadensis) forests on 11 plots before (2001) and 15 years after (2016) invasion in the southern Appalachian Mountains, USA. Losses of hemlock trees after HWA invasion were among the highest reported, with a 90% decline in density, 86% decline in basal area, and 100% mortality for individuals ≥ 60 cm in diameter. In contrast to predictions of theoretical models, deciduous tree density declined after HWA invasion, while basal area changed little, at least during the initial 15 years after invasion. Overall, forest density declined by 58%, basal area by 25%, and tree species richness by 8%. Factors additional to HWA likely exacerbating forest decline included: droughts before (1999–2001) and after HWA invasion (2006–2008); tree uprooting from hurricane-stimulated winds in 2004; pest-related declines of deciduous tree species otherwise likely benefitting from hemlock’s demise; death of deciduous trees when large hemlocks fell; and competition from aggressive understory plants including doghobble (Leucothoe fontanesiana), rosebay rhododendron (Rhododendron maximum), and Rubus spp. Models of forest change and ecosystem function should not assume that deciduous trees always increase during the first decades after HWA invasion.     

Entangled Matters—Alzheimer’s,Interiority, and the ‘Unflattening’ of the World

When, in the 1980s, Alzheimer's disease became a disease of major public concern, 'personhood' also became an important, related topic of discussion. Those in caring professions (psychology, social work, etc.) and caregiver groups advocated for the 'person within' who was getting lost in a forgetful body and in a reductionist biomedical system. This essay aims to critically approach the dualism of this kind of argument by focusing on the moral positioning of claims such as personhood or biomedical reductionism.     

The language of systematics,and the philosophy of ‘total evidence’

This contribution analyses the primacy of classification over generalization, and the philosophy of total evidence that emerges from the relation of homology to character statements. Primary conjectures of homology are basic character statements, i.e. statements that predicate properties of organisms, properties that are instantiated by those organisms and/or their parts. Secondary conjectures of homology are embedded in a second‐level (metalinguistic) discourse that turns on the coherence or incoherence of those basic character statements relative to a hierarchy. The coherence or incoherence of character statements is a logical relation between statements, not a causal (historical) relation between organisms. The choice of the hypothesis of relationships that is supported by the largest set of coherent basic character statements is based on the empirical presupposition that the properties referred to by the set of coherent character statements are grounded in causally efficacious relations of inheritance and ontogeny, and co‐instantiated because they are inherited through common ancestry (Hennig's auxiliary principle). Unless that empirical presupposition is causally grounded, phylogeny reconstruction is of an inherently probabilistic nature, whether under parsimony or other models of analysis. The causal grounding of a coherent set of character statements typically seeks a link between character statements and causally efficacious generative mechanisms for morphological characters (as is defeasibly indicated by topology and connectivity), or secondary structure information for molecular characters.     

Ethnicity and race as ‘symbolic’: the use of ethnic and racial symbols in asserting a biracial identity

Contemporary research indicates that religious institutions can play bonding and bridging roles in the lives of immigrants, strengthening the bonds within immigrant groups while simultaneously connecting immigrants to the wider society. The majority of this research focuses on religious institutions in US cities with long histories of immigration and sizable immigrant populations. This article examines the role of religious institutions in the lives of refugees living in a city with a small, but rapidly growing immigrant population. Evidence from interviews with Catholic and Muslim refugees and participant observation at two houses of worship suggests that the functions of religious institutions differ for refugees from majority and minority religious traditions. Catholic refugees use their church for bonding and bridging purposes, while Muslim refugees use their mosque primarily for bonding purposes.     

Relationship between dough-raising activity of baker's yeast and the fraction of ‘vital’ cells as determined by methylene blue staining or by dielectrophoresis

Three methods of comparing the vitility of baker's yeast (Saccharomyces cerevisiae) were examined, and found to correlated well. The rate of dough-raising, the degree of visible staining by a reducible dye (methylene blue), and the rate of dielectrophoretic collection as the cells were subject to a nonuniform ac field all appear to agree well as indices of cell viability. The simplicity of the dielectrophoretic technique suggests its further use in cellular assays.     

‘So you are a mestiza’: Exploring the consequences of ethnic and racial clumping in the US academy

This paper intends to open a dialogue about the use of two specific labels in the US (i.e. ‘Chicanas’ and ‘Latinas’), with a special emphasis on how they are used in the US academy as both markers and identities. More specifically, this paper explores recent trends in the US academy by which women of Latin American descent are lumped together under the rubric Latinas, and in many cases assumed to be equivalent to Chicanas. Arguing that academia must learn to be more thoughtful when creating, defining and adopting categories, the article warns against recreating the very power dynamics we find in mainstream US society by way of these specific labels. Finally, ‘So you are a mestiza’ reminds its readers that, as a practice, social justice asks for a fundamental recognition of a culturally pluralist, democratic society. In this kind of society, histories must endure and multiple realities must be acknowledged.     

Regulation of coenzyme A levels by degradation: the ‘Ins and Outs’

Coenzyme A (CoA) is the predominant acyl carrier in mammalian cells and a cofactor that plays a key role in energy and lipid metabolism. CoA and its thioesters (acyl-CoAs) regulate a multitude of metabolic processes at different levels: as substrates, allosteric modulators, and via post-translational modification of histones and other non-histone proteins. Evidence is emerging that synthesis and degradation of CoA are regulated in a manner that enables metabolic flexibility in different subcellular compartments. Degradation of CoA occurs through distinct intra- and extracellular pathways that rely on the activity of specific hydrolases. The pantetheinase enzymes specifically hydrolyze pantetheine to cysteamine and pantothenate, the last step in the extracellular degradation pathway for CoA. This reaction releases pantothenate in the bloodstream, making this CoA precursor available for cellular uptake and de novo CoA synthesis. Intracellular degradation of CoA depends on specific mitochondrial and peroxisomal Nudix hydrolases. These enzymes are also active against a subset of acyl-CoAs and play a key role in the regulation of subcellular (acyl-)CoA pools and CoA-dependent metabolic reactions. The evidence currently available indicates that the extracellular and intracellular (acyl-)CoA degradation pathways are regulated in a coordinated and opposite manner by the nutritional state and maximize the changes in the total intracellular CoA levels that support the metabolic switch between fed and fasted states in organs like the liver.The objective of this review is to update the contribution of these pathways to the regulation of metabolism, physiology and pathology and to highlight the many questions that remain open.     

Active invasion and/or encapsulation? A reappraisal of host-cell parasitism by Cryptosporidium

Host-cell invasion by Cryptosporidium is a complex process that requires many different factors derived from both the parasite and the host cell. However, the exact natures of the processes have yet to be resolved. Here, research on different components of the invasion process is put in context, and the sequence of events and pathways associated with the establishment of Cryptosporidium in its unique niche is clarified. In addition, initial parasite-host contact, host-cell invasion and host-cell responses are described. The roles of parasite and host-cell-derived components in the invasion process are examined, as is the question of whether Cryptosporidium actively invades cells and to what extent host-cell responses are involved.     

‘Gender’ and the Concerns of Carnal Self-Consumption

This article analyses the co-occurrence of two concerns often expressed by indigenous leaders involved with reparations for victims of paramilitaries in Colombia. These concerns revolve around discomfort with the intense use of hegemonic ‘gender’ discourses in the context of the reparations, and a feeling that leaders' involvement in the latter brings about a betrayal of the family and of themselves. By engaging with the local category of eirruku (flesh), I argue that ways of engaging women in reparations entail the commoditisation of caring relationships. This article, based on 13 months of fieldwork with an indigenous organisation and the communities integrated into it between 2007 and 2008, contributes to the understanding of the articulation of gender and ethnic/racial identification in the context of contemporary forms of governance of indigenous peoples, while delving into ‘carnality’ as a concept to understand gendered forms of reproduction, reparation and selfhood.     

Phylogeny and taxonomy of the ‘manna lichens’

We present ataxonomic revision of the ‘manna lichens’ based on morphological, chemical, ecological and molecular data. A large number of herbarium specimens and fresh collections were examined. Phylogenetic analyses were performed using nuclear ribosomal (nrITS, nrLSU) and mitochondrial small subunit (mtSSU) sequences. Some notable phenotypic characters were plotted on the phylogenetic tree, and the analysis reveals that some of these characters are useful for genus and species level distinction of certain ‘manna lichens.’ Phylogeny of the Megasporaceae was revised using a combined data set of nrLSU and mtSSU and performing parsimony and Bayesian analyses. Five genera (Aspicilia, Circinaria, Lobothallia, Megaspora and Sagedia) are recognized. Further, the relationships of five presumably closely related genera of ‘manna lichens’, namely Agrestia (vagrant), Aspicilia (crustose) Circinaria (crustose), Chlorangium (vagrant) and Sphaerothallia (vagrant) with different growth forms were analysed. The analyses revealed that ‘manna lichens’ do not form a monophyletic group but occur in different clades within the genus Circinaria. The genera Agrestia, Chlorangium and Sphaerothallia are assigned as new synonyms under the genus Circinaria and no vagrant or erratic species remain in the genus Aspicilia. The analyses also show that five new erratic, vagrant and crustose species can be recognized. In this study two ‘manna lichens’, viz. Circinaria rostamii sp. nov. (Azerbaijan, Iran and Turkey), and Circinaria gyrosa sp. nov. (Armenia, Azerbaijan, Iran, Turkey, Turkmenistan and Spain) are described as new to science. Three potentially new species with crustose and erratic forms need additional study. Aspicilia fruticolosofoliacea is reduced to synonymy under C. alpicola, and a lectotype is designated for C. aspera. Thirteen new combinations in Circinaria are presented. The phenomenon of vagrancy is briefly discussed, and the biogeography of the ‘manna lichens’ is outlined. Illustrations, distribution maps, and an identification key to the species are provided.     

‘Placebos’ and the logic of placebo comparison

Robin Nunn has argued that we should stop using the terms ‘placebo’ and ‘placebo effect’. I argue in support of Nunn’s position by considering the logic of why we perform placebo comparisons. Like all comparisons, placebo comparison is just a case of comparing one thing with another, but it is a mistake, I argue, to think of placebo comparison as a case where something is compared to ‘a placebo’. Rather, placebo comparison should be understood as a situation which sets-up the treatment and control groups in a particular way; not as a case involving objects or procedures called ‘placebos’ employed in order to control for ‘placebo effects’.     

Making sense of ‘mixture’: states and the classification of ‘mixed’ people

Caribbean diaspora intellectuals have contributed significantly to African-American political struggles over the years, despite arguments by some African-American intellectuals about what they discern as West Indian negativism, extremism, and divisiveness in American political life. This essay examines the legacy of a representative sample of diasporic Caribbean intellectuals since the time of the Harlem Renaissance in the 1920s and culminating in the 1970s, notably, Garvey, members of the African Blood Brotherhood [ABB], C.L.R. James, and Walter Rodney, to demonstrate the phenomenal ideological vision, organizational capability, and political activism they have brought into fostering solidarity with African Americans in the struggle for fundamental change. The focus here is on their respective contributions to the debate on the relationship between class and race in America and the black diaspora generally, which has helped to shape the form, and orient the direction of African-American and Caribbean diasporic struggles for the better part of the twentieth century.