• Age-related shifts in bacterial diversity in a reef coral

      Williams, Alex D.; Putchim, Lalita; Brown, Barbara E.; Sweet, Michael J.; University of Derby (Public Library of Science, 2015-12-23)
      This study investigated the relationship between microbial communities in differently sized colonies of the massive coral Coelastrea aspera at Phuket, Thailand where colony size could be used as a proxy for age. Results indicated significant differences between the bacterial diversity (ANOSIM, R = 0.76, p = 0.001) of differently sized colonies from the same intertidal reef habitat. Juvenile and small colonies (28 cm mean diam). Bacterial diversity increased in a step-wise pattern from juvenilessmallmedium colonies, which was then followed by a slight decrease in the two largest size classes. These changes appear to resemble a successional process which occurs over time, similar to that observed in the ageing human gut. Furthermore, the dominant bacterial ribotypes present in the tissues of medium and large sized colonies of C. aspera, (such as Halomicronema, an Oscillospira and an unidentified cyanobacterium) were also the dominant ribotypes found within the endolithic algal band of the coral skeleton; a result providing some support for the hypothesis that the endolithic algae of corals may directly influence the bacterial community present in coral tissues.
    • The antibacterial potency of the medicinal maggot, Lucilia sericata (Meigen): Variation in laboratory evaluation

      Barnes, Kate M.; Dixon, Ron A.; Gennard, Dorothy E.; University of Lincoln (Elsevier, 2010-09)
      Research to quantify the potency of larval excretion/secretion from Lucilia sericata using liquid culture assays has produced contradictory results. In this study, viable counting was used to investigate the effectiveness of excretion/secretion against three marker bacterial species (Pseudomonas aeruginosa, Staphylococcus aureus, and Escherichia coli) and the effects of varying growing conditions in assays. Results demonstrate that factors such as number of larvae, species of bacteria and addition of nutrient influence its antibacterial potency. Therefore a standardised method should be employed for liquid culture assays when investigating the antibacterial activity of larval excretion/secretion from L. sericata.
    • Apis mellifera (Linnaeus, 1761) (Hymenoptera: Apidae) on carrion, a note of the behaviour and a review of the literature.

      Chick, Andrew I. R.; Dye, Alex; University of Derby; Rothamsted Research (Andrew Smith Print Ltd., 2017-11-25)
      The Honeybee Apis mellifera (Linnaeus, 1761) traditionally feeds on the nectar of flowers (Núñez, 1977). A number of workers of A. mellifera were observed on whole pig carrion in woodland in Riseholme Lincoln (Grid reference SK978754) on 10 of October 2017. This paper aims to look at this odd behaviour in context of the literature.
    • Arthropod-microbe interactions on vertebrate remains: Potential applications in the forensic sciences.

      Tomberlin, Jeffery K.; Benbow, M. Eric; Barnes, Kate M.; Jordan, Heather R.; Texas A&M University; Michigan State University; University of Derby; Mississippi State University (John Wiley and Sons, 2017-04-08)
      Understanding the process of insect colonization of human remains is a core area of research by forensic entomologists, with several recent studies suggesting that microbial communities influence the process and timing of colonization. Such information is crucial for determining when colonization occurred as related to the postmortem interval (PMI). This chapter reviews the basic field of forensic entomology; the phases of insect behavior associated with their detection, location, and utilization of the remains as postulated by Matuszewski (Matuszewski, S. (2011) Estimating the pre-appearance interval from temperature in Necrodes littoralis L. (Coleoptera: Silphidae). Forensic Science International, 212, 180–188) and Tomberlin et al. (Tomberlin, J. K., R. Mohr, M. E. Benbow, et al. 2011. A roadmap for bridging basic and applied research in forensic entomology. Annual Review of Entomology, 56, 401–421.); and how microbes play a key role mediating this process. The chapter concludes with a discussion of potential future directions related to microbe–insect interactions in association with vertebrate remains decomposition, and this is potentially important to forensics.
    • An assessment of the antibacterial activity in larval excretion/secretion of four species of insects recorded in association with corpses, using Lucilia sericata Meigen as the marker species

      Barnes, Kate M.; Gennard, Dorothy E.; Dixon, Ron A.; University of Lincoln (Cambridge University Press, 2010-03-22)
      The relative antibacterial activities of excretion/secretion (ES) from two carrion-feeding insects, Calliphora vicina Robineau-Desvoidy and Dermestes maculatus DeGeer, and a detritivore, Tenebrio molitor Linnaeus, were compared to that of Lucilia sericata Meigen, a species with ES of known antibacterial capacity, in order to explore the antimicrobial potential of other carrion and detritivore species. Viable counts were used to assess time-kill of ES against five bacterial species, Staphylococcus aureus, Escherichia coli, Bacillus cereus, Pseudomonas aeruginosa and Proteus mirabilis. Antibacterial activity was recorded in all four insect species although T. molitor and D. maculatus were the most effective in controlling growth of P. mirabilis. The blowflies were more effective in controlling a wider range of both Gram-positive and Gram-negative bacteria. The larval ES from all species was shown to reduce bacterial growth rate although differences in antibacterial spectrum were noted and the degree of potency varied between the four species. These differences may be explained ecologically by the different colonisation times of each insect species on the corpse. Overall, this study demonstrates that research into other carrion-feeding insect species has potential to provide an increased source of antimicrobial chemicals to broaden the range of bacterial species beyond that currently controlled using L. sericata.
    • Bacterial and fungal communities in a degraded ombrotrophic peatland undergoing natural and managed re-vegetation

      Elliott, David R.; Caporn, Simon; Nwaishi, Felix; Nilsson, R. Henrik; Sen, Robin; Manchester Metropolitan University (Public Library of Science, 2015-05-13)
      The UK hosts 15–19% of global upland ombrotrophic (rain fed) peatlands that are estimated to store 3.2 billion tonnes of carbon and represent a critical upland habitat with regard to biodiversity and ecosystem services provision. Net production is dependent on an imbalance between growth of peat-forming Sphagnum mosses and microbial decomposition by microorganisms that are limited by cold, acidic, and anaerobic conditions. In the Southern Pennines, land-use change, drainage, and over 200 years of anthropogenic N and heavy metal deposition have contributed to severe peatland degradation manifested as a loss of vegetation leaving bare peat susceptible to erosion and deep gullying. A restoration programme designed to regain peat hydrology, stability and functionality has involved re-vegetation through nurse grass, dwarf shrub and Sphagnum re-introduction. Our aim was to characterise bacterial and fungal communities, via high-throughput rRNA gene sequencing, in the surface acrotelm/mesotelm of degraded bare peat, long-term stable vegetated peat, and natural and managed restorations. Compared to long-term vegetated areas the bare peat microbiome had significantly higher levels of oligotrophic marker phyla (Acidobacteria, Verrucomicrobia, TM6) and lower Bacteroidetes and Actinobacteria, together with much higher ligninolytic Basidiomycota. Fewer distinct microbial sequences and significantly fewer cultivable microbes were detected in bare peat compared to other areas. Microbial community structure was linked to restoration activity and correlated with soil edaphic variables (e.g. moisture and heavy metals). Although rapid community changes were evident following restoration activity, restored bare peat did not approach a similar microbial community structure to non-eroded areas even after 25 years, which may be related to the stabilisation of historic deposited heavy metals pollution in long-term stable areas. These primary findings are discussed in relation to bare peat oligotrophy, re-vegetation recalcitrance, rhizosphere-microbe-soil interactions, C, N and P cycling, trajectory of restoration, and ecosystem service implications for peatland restoration.
    • Basaltic maar-diatreme volcanism in the Lower carboniferous of the Limerick Basin (SW Ireland)

      Gernon, T. M.; Roberts, S.; Hewson, C.; Elliott, Holly; University of Southampton (Springer, 2015-04-16)
      Lead-zinc exploration drilling within the Limerick Basin (SW Ireland) has revealed the deep internal architecture and extra-crater deposits of five alkali-basaltic maar-diatremes. These were emplaced as part of a regional north-east south-west tectonomagmatic trend during the Lower Carboniferous Period. Field relationships and textural observations suggest that the diatremes erupted into a shallow submarine environment. Limerick trace element data indicates a genetic relationship between the diatremes and extra-crater successions of the Knockroe Formation, which records multiple diatreme filling and emptying cycles. Deposition was controlled largely by bathymetry defined by the surrounding Waulsortian carbonate mounds. An initial non-diatreme forming eruption stage occurred at the water-sediment interface, with magma-water interaction prevented by high magma ascent rates. This was followed by seawater incursion and the onset of phreatomagmatic activity. Magma-water interaction generated poorly vesicular blocky clasts, although the co-occurrence of plastically deformed and highly vesicular clasts indicate that phreatomagmatic and magmatic processes were not mutually exclusive. At a later stage, the diatreme filled with a slurry of juvenile lapilli and country rock lithic clasts, homogenised by the action of debris jets. The resulting extra-crater deposits eventually emerged above sea level, so that water ingress significantly declined, and late-stage magmatic processes became dominant. These deposits, largely confined to the deep vents, incorporate high concentrations of partially sintered globular and large ‘raggy’ lapilli showing evidence for heat retention. Our study provides new insights into the dynamics and evolution of basaltic diatremes erupting into a shallow water (20–120 m) submarine environment.
    • Can MOOCs meet your learning needs?

      Bryson, David; University of Derby (Taylor and Francis, 2017-09-19)
      This paper looks at the role of Massive Open Online Courses (MOOCs) in fulfilling your learning needs; from looking at what MOOCs are through to examples of courses from different Universities and advice for completing a course. The sequence of activities takes you from looking at your learning needs, to finding a course, thinking about how to plan and prepare for learning using a MOOC then writing a review or reflecting on the impact of your learning.
    • Characterization and social correlates of fecal testosterone and cortisol excretion in wild male Saguinus mystax

      Huck, Maren; Löttker, Petra; Heymann, Eckhard W.; Heistermann, Michael; Abteilung Soziobiologie, Deutsches Primatenzentrum, Göttingen, Germany; Lehrstuhl für Verhaltensforschung, Universität Bielefeld, Germany; Institut für Neuro- & Verhaltensbiologie, Abt. Verhaltensbiologie, Westfälische Wilhelms-Universität Münster, Germany; Abteilung für Reproduktionsbiology, Deutsches Primatenzentrum, Göttingen, Germany (2005)
      Reproductive success in male primates can be influenced by testosterone (T) and cortisol (C). We examined them in wild Saguinus mystax via fecal hormone analysis. Firstly, we wanted to characterize male hormonal status over the course of the year. Further we tested the influence of the reproductive status of the breeding female, social instability, and intergroup encounter rates on T levels, comparing the results with predictions of the challenge hypothesis (Wingfield et al., 1990). We also tested for interindividual differences in hormonal levels, possibly related to social or breeding status. We collected data during a 12-mo study on 2 groups of moustached tamarins at the Estación Biológica Quebrada Blanco in northeastern Peru. We found fairly similar T and C levels over the course of the year for all males. Yet an elevation of T shortly after the birth of infants, during the phase of ovarian inactivity of the group’s breeding female, was evident. Hormonal levels were not significantly elevated during a phase of social instability, did not correlate with intergroup encounter rates, and did not differ between breeding and nonbreeding males. Our results confirm the challenge hypothesis (Wingfield et al., 1990). The data suggest that reproductive competition inmoustached tamarins is not based on endocrinological, but instead on behavioral mechanisms, possibly combined with sperm competition.
    • Comparative Assessment of Copper, Iron, and Zinc Contents in Selected Indian (Assam) and South African (Thohoyandou) Tea (Camellia sinensis L.) Samples and Their Infusion: A Quest for Health Risks to Consumer

      Karak, Tanmoy; Paul, Ranjit Kumar; Kutu, Funso Raphael; Mehra, Aradhana; Khare, Puja; Dutta, Amrit Kumar; Bora, Krishnamoni; Boruah, Romesh Kumar; University of Derby (Springer, 2016-06-23)
      Abstract: The current study aims to assess the infusion pattern of three important micronutrients namely copper (Cu), iron (Fe) and zinc (Zn) contents from black tea samples produced in Assam (India) and Thohoyandou (South Africa). Average daily intakes and hazardous quotient were reported for these micronutrients. Total content for Cu, Fe and Zn varied from 2.25 to 48.82 mg kg-1, 14.75 to 148.18 mg kg-1 and 28.48 to 106.68 mg kg-1 respectively. The average contents of each of the three micronutrients were higher in tea leaves samples collected from South Africa than those from India while the contents s in tea infusions in Indian samples were higher than in South African tea samples. Results of this study revealed that the consumption of not more than 600 mL tea infusion produced from 24 g of made tea per day may be beneficial to human in terms of these micronutrients content. Application of nonparametric tests revealed that most of the data sets do not satisfy the normality assumptions. Hence, Powered by Editorial Manager® and ProduXion Manager® from Aries Systems Corporation the use of both parametric and nonparametric statistical analysis that subsequently revealed significant differences in elemental contents among Indian and South African tea.
    • Complex subvolcanic magma plumbing system of an alkali basaltic maar-diatreme volcano (Elie Ness, Fife, Scotland)

      Upton, B.G.J.; Ugra, R.; Yücel, C.; Taylor, R.N.; Elliott, Holly; University of Southampton (Elsevier, 2016-08-17)
      Alkali basaltic diatremes such as Elie Ness (Fife, Scotland) expose a range of volcanic lithofacies that points to a complex, multi-stage emplacement history. Here, basanites contain phenocrysts including pyrope garnet and sub-calcic augites from depths of ~60km. Volcanic rocks from all units, pyroclastic and hypabyssal, are characterised by rare earth element (REE) patterns that show continuous enrichment from heavy REE (HREE) to light REE (LREE), and high Zr/Y that are consistent with retention of garnet in the mantle source during melting of peridotite in a garnet lherzolite facies. Erupted garnets are euhedral and unresorbed, signifying rapid ascent through the lithosphere. The magmas also transported abundant pyroxenitic clasts, cognate with the basanite host, from shallower depths (~35–40km). These clasts exhibit wide variation in texture, mode and mineralogy, consistent with growth from a range of compositionally diverse melts. Further, clinopyroxene phenocrysts from both the hypabyssal and pyroclastic units exhibit a very wide compositional range, indicative of polybaric fractionation and magma mixing. This is attributed to stalling of earlier magmas in the lower crust — principally from ~22 to 28km — as indicated by pyroxene thermobarometry. Many clinopyroxenes display chemical zoning profiles, occasionally with mantles and rims of higher magnesium number (Mg#) suggesting the magmas were mobilised by juvenile basanite magma. The tuffs also contain alkali feldspar megacrysts together with Fe-clinopyroxene, zircon and related salic xenoliths, of the ‘anorthoclasite suite’ — inferred to have crystallised at upper mantle to lower crustal depths from salic magma in advance of the mafic host magmas. Despite evidence for entrainment of heterogeneous crystal mushes, the rapidly ascending melts experienced negligible crustal contamination. The complex association of phenocrysts, megacrysts and autoliths at Elie Ness indicates thorough mixing in a dynamic system immediately prior to explosive diatreme-forming eruptions.
    • Creating three dimensional, orientable, temporary invertebrate slides for photomicrography.

      Chick, Andrew I. R.; University of Derby (The Amateur Entomologists' Society, 2017-09)
    • Current issues: patient perception of clinical photography.

      Bryson, David; University of Derby; College of Life and Natural Sciences, University of Derby, Derby, UK (Taylor and Francis, 2018-01-30)
    • Detecting macroecological patterns in bacterial communities across independent studies of global soils.

      Ramirez, Kelly S.; Knight, Christopher G.; de Hollander, Mattias; Brearley, Francis Q.; Constantinides, Bede; Cotton, Anne; Creer, Si; Crowther, Thomas W.; Davison, John; Delgado-Baquerizo, Manuel; et al. (Nature, 2017-11-20)
      The emergence of high-throughput DNA sequencing methods provides unprecedented opportunities to further unravel bacterial biodiversity and its worldwide role from human health to ecosystem functioning. However, despite the abundance of sequencing studies, combining data from multiple individual studies to address macroecological questions of bacterial diversity remains methodically challenging and plagued with biases. Here, using a machine-learning approach that accounts for differences among studies and complex interactions among taxa, we merge 30 independent bacterial data sets comprising 1,998 soil samples from 21 countries. Whereas previous meta-analysis efforts have focused on bacterial diversity measures or abundances of major taxa, we show that disparate amplicon sequence data can be combined at the taxonomy-based level to assess bacterial community structure. We find that rarer taxa are more important for structuring soil communities than abundant taxa, and that these rarer taxa are better predictors of community structure than environmental factors, which are often confounded across studies. We conclude that combining data from independent studies can be used to explore bacterial community dynamics, identify potential ‘indicator’ taxa with an important role in structuring communities, and propose hypotheses on the factors that shape bacterial biogeography that have been overlooked in the past.
    • Developing badge eco-systems to support engagement in class-based and online learning

      Bryson, David; Hadi, Munib; Petronzi, Dominic; University of Derby (International Academy of Technology, Education and Development, 2016-11)
      Abstract Background Badges enable academic and non-academic learners to collect and display their achievements and to enhance their training and qualification repertoire. To support engagement in class-based and online modules we have introduced badge ecosystems backed up by University quality assurance procedures. This paper presents two case studies which exemplify the application of badges at the University of Derby and the possibilities for future developments of badge ecosystems. Class-based: Forensic anthropology/Osteology A sequence of badges in the Forensic Anthropology module was implemented to support students as they develop their understanding of osteology and anatomy. In this context, the implementation of badges relies on the use of learning outcomes that support learning and the assessment of practical knowledge as well as student’s ability to observe key features in the subject. Online MOOCs The University of Derby (UoD) have incorporated badges in a series of MOOCs that include: “Bridging the Dementia Divide: Supporting People Living with Dementia (2015); Digital.Me: Managing your Digital Self (2015); Operations Management (2016); a re-run of Supporting People Living with Dementia (2016) and Autism, Asperger’s and ADHD (2016). Throughout these, badges were used to reward degrees of completion and have an association with a favourable average completion rate across four of the MOOCs. The use of badges at the University has been led by academics staff and the Innovation Hub as part of a Badges Working Group. The innovative approaches to badges and badge ecosystems have been supported by the development of a University infrastructure for badge development including: • Schema to back-up micro-credentialing • Quality assurance processes and • University badge server The UoD Working Badges Group and Quality Assurance The use of digital badges supported by the University’s quality framework means that we are rewarding meaningful learning, have increased badge credibility with our own badge server for issuing badges. In this way we have assured the integrity of the badges not just being University of Derby by branding but through the University as the issuing organization. Conclusion The UoD has incorporated badges to provide recognition for the learning, achievements and contributions of our class-based and MOOC learners, and the credibility of our badges will increase further as we move towards further implementation by academics and departments through the use of the badge framework. This could allow our digital credentials to be used by partners and other educational institutions and will act as an incentive for the UoD to continue its focus on badge development, quality and credibility.
    • Diatremes act as fluid conduits for Zn-Pb mineralization in the SW Irish Ore field

      Gernon, Thomas M.; Roberts, Stephen; Boyce, Adrian J.; Hewson, Chad; Elliott, Holly; University of Southampton (GeoScienceWorld, 2019-02-28)
      Irish-type mineralization is commonly attributed to fault-controlled mixing of a seawater-derived, sulfur-rich fluid and basement-derived, metal-rich fluid. However, maar-diatreme volcanoes discovered in close spatial and temporal association with Zn-Pb mineralization at Stonepark in the Limerick basin (southwest Ireland) bring a new dimension to established geologic models and may increase the deposit-scale prospectivity in one of the world’s greatest Zn-Pb districts. Stonepark exhibits many incidences of dolomitic black matrix breccias with associated Zn-Pb mineralization, the latter typically occurring within 150 m of the diatremes. Highly negative δ34S pyrite values within country rock-dominated black matrix breccias (–12 to –34‰) are consistent with sulfide precipitation from bacteriogenic sulfur reduction in seawater-derived brines. However, δ34S values of Zn-Pb sulfides replacing black matrix breccias (–10 to 1‰) reflect multiple sulfur sources. Diatreme emplacement both greatly enhanced country rock fracture permeability and produced conduits that are filled with porous volcaniclastic material and extend down to basement rock types. Our δ34S data suggest that diatremes provide more efficient fluid pathways for basement-derived fluids. The diatremes introduce another potential sulfur source and facilitate a greater input of metal-rich basement-derived hydrothermal fluid into the system compared to other Irish-type deposits such as Navan and Lisheen, evidenced by Stonepark’s more positive modal δ34S value of –4‰. Irish-type deposits are traditionally thought to form in association with extensional basement faults and are considered unrelated to extensive Carboniferous magmatism. Our results indicate that a direct link exists between diatreme volcanism and Zn-Pb mineralization at Limerick, prompting a reevaluation of the traditional Irish-type ore formation model, in regions where mineralization is spatially associated with volcanic pipes.
    • Differential effects of short-term β agonist and growth hormone treatments on expression of myosin heavy chain IIB and associated metabolic genes in sheep muscle

      Hemmings, Krystal M.; Daniel, Zoe; Buttery, Peter; Parr, Tim; Brameld, John M.; University of Derby; University of Nottingham (Cambridge University Press, 2014-09-12)
      Growth hormone (GH) and β agonists increase muscle mass, but the mechanisms for this response are unclear and the magnitude of response is thought to vary with age of animal. To investigate the mechanisms driving the muscle response to these agents, we examined the effects of short-term (6 day) administration of GH or cimaterol (a β 2-adrenergic agonist, BA) on skeletal muscle phenotype in both young (day 60) and mature (day 120) lambs. Expression of myosin heavy chain (MyHC) isoforms were measured in Longissimus dorsi (LD), Semitendinosus (ST) and Supraspinatus (SS) muscles as markers of fibre type and metabolic enzyme activities were measured in LD. To investigate potential mechanisms regulating the changes in fibre type/metabolism, expression or activity of a number of signalling molecules were examined in LD. There were no effects of GH administration on MyHC isoform expression at either the mRNA or protein level in any of the muscles. However, BA treatment induced a proportional change in MyHC mRNA expression at both ages, with the %MyHCI and/or IIA mRNA being significantly decreased in all three muscles and %MyHCIIX/IIB mRNA significantly increased in the LD and ST. BA treatment induced de novo expression of MyHCIIB mRNA in LD, the fastest isoform not normally expressed in sheep LD, as well as increasing expression in the other two muscles. In the LD, the increased expression of the fastest MyHC isoforms (IIX and IIB) was associated with a decrease in isocitrate dehydrogenase activity, but no change in lactate dehydrogenase activity, indicating a reduced capacity for oxidative metabolism. In both young and mature lambs, changes in expression of metabolic regulatory factors were observed that might induce these changes in muscle metabolism/fibre type. In particular, BA treatment decreased PPAR- γ coactivator-1 β mRNA and increased receptor-interacting protein 140 mRNA. The results suggest that the two agents work via different mechanisms or over different timescales, with only BA inducing changes in muscle mass and transitions to a faster, less oxidative fibre type after a 6-day treatment.
    • The eastern French Pyrenees: from mountain belt to foreland basin

      Satterfield, Dorothy; Rollinson, Hugh; Suthren, Roger; University of Derby (Wiley, 2019-12-09)
      The Pyrenees is a young mountain belt formed as part of the larger Alpine collision zone. This excursion explores the development of the Pyrenean Mountain Belt in southern France, from its early extensional phase in the mid‐Cretaceous and subsequent collisional phase, through its uplift and erosion in the Late Cretaceous and again in the Eocene, which led to the development of the Aquitaine‐Languedoc foreland basin. One of the complexities of the Pyrenean Belt is that thrusting, uplift and erosion during the Pyrenean orogeny exposed older Variscan basement rocks in the central core of the mountains, rocks which were metamorphosed during an earlier event in the late Carboniferous. Thus, this orogenic belt also tells the story of an earlier collision between Laurussia in the north and Gondwana in the south at c. 300 Ma, prior to the onset of the Pyrenean events at c. 100 Ma. Here we seek to unravel these two separate orogenic stories.
    • The effect of bacterially-dense environments on the development and immune defences of the blowfly Lucilia sericata

      Barnes, Kate M.; Gennard, Dorothy E.; University of Lincoln (Wiley, 2010-11-01)
      Competitive interactions between insects and microbes and the associated cost of development in bacterially-dense environments are investigated using the blowfly Lucilia sericata (Meigen) (Diptera: Calliphoridae) as a model. The effects of developing in a bacterially-dense environment are measured by assessing the fitness consequences of competition using the pathogen Staphylococcus aureus. Fitness is quantified in terms of larval survival, puparial development and adult emergence.The influence of bacteria on larval immune defences is investigated using optical density to assess whether antibacterial potency of the larval excretion/secretion changes in response to the degree of contamination of the larval environment. The results obtained demonstrate that bacterial presence has no detrimental effect on survival of L. sericata from egg to adult eclosion, or on puparial size. Additionally, the level of microbial contamination of larvae has no effect on the antibacterial potency of the larval excretion/secretion. These findings confirm that larval antibacterial activity is not induced by the presence of environmental bacteria but is produced constitutively.
    • Effects of vegetation on bacterial communities, carbon and nitrogen in dryland soil surfaces: implications for shrub encroachment in the southwest Kalahari

      Thomas, Andrew D.; Tooth, Stephen; Wu, Li; Elliott, David R.; Aberystwyth University, Aberystwyth; Chinese Academy of Sciences, Wuhan; Wuhan University of Technology, Wuhan; University of Derby (Elsevier, 2020-10-09)
      Shrub encroachment is occurring in many of the world's drylands, but its impacts on ecosystem structure and function are still poorly understood. In particular, it remains unclear how shrub encroachment affects dryland soil surfaces, including biological soil crust (biocrust) communities. In this study, soil surfaces (0–1 cm depth) were sampled from areas of Grewia flava shrubs and Eragrostis lehmanniana and Schmidtia kalahariensis grasses in the southwest Kalahari during two different seasons (March and November). Our hypothesis is that the presence of different vegetation cover types (shrubs versus grasses) alters the microbial composition of soil surfaces owing to their contrasting microenvironments. The results showed that more significant differences in microclimate (light, soil surface temperatures) and soil surface microbial communities were observed between shrubs and grasses than between sampling seasons. Based on high-throughput 16S rRNA gene sequencing, our findings showed that approximately one third (33.5%) of the operational taxonomic units (OTUs) occurred exclusively in soil surfaces beneath shrubs. Soil surfaces with biocrusts in grass areas were dominated by the cyanobacteria Microcoleus steenstrupii, whereas the soil surfaces beneath shrubs were dominated by the proteobacteria Microvirga flocculans. Soil surfaces beneath shrubs are associated with reduced cyanobacterial abundance but have higher total carbon and total nitrogen contents compared to biocrusts in grass areas. These findings infer changes in the relative contributions from different sources of carbon and nitrogen (e.g. cyanobacterial and non-cyanobacterial fixation, plant litter, animal activity). The distinctive microbial composition and higher carbon and nitrogen contents in soil surfaces beneath shrubs may provide a positive feedback mechanism promoting shrub encroachment, which helps to explain why the phenomenon is commonly observed to be irreversible.