• Genetic modifications of metallothionein enhance the tolerance and bioaccumulation of heavy metals in Escherichia coli

      Li, Xuefen; Ren, Zhumei; Crabbe, M. James C.; Wang, Lan; Ma, Wenli; Shanxi University; University of Oxford; University of Bedfordshire (Elsevier, 2021-07-13)
      Metallothioneins (MTs) are low molecular weight cysteine-rich proteins that bind to metals. Owing to their high cysteine (Cys) content, MTs are effective mediators of heavy metal detoxification. To enhance the heavy metal binding ability of MT from the freshwater crab Sinopotamon henanense (ShMT), sequence-based multiple sequence alignment (MSA) and structure-based molecular docking simulation (MDS) were conducted in order to identify amino acid residues that could be mutated to bolster such metal-binding activity. Site-directed mutagenesis was then used to modify the primary structure of ShMT, and the recombinant proteins were further enhanced using the SUMO fusion expression system to yield SUMO-ShMT1, SUMO-ShMT2, and SUMO-ShMT3 harboring one-, two-, and three- point mutations, respectively. The resultant modified proteins were primarily expressed in a soluble form and exhibited the ability to readily bind to heavy metals. Importantly, these modified proteins exhibited significantly enhanced heavy metal binding capacities, and they improved Cd2+, Cu2+ and Zn2+ tolerance and bioaccumulation in Escherichia coli (E. coli) in a manner dependent upon the number of introduced point mutations (SUMO-ShMT3 > SUMO-ShMT2 > SUMO-ShMT1 > SUMO-ShMT > control). Indeed, E. coli cells harboring the pET28a-SUMO-ShMT3 expression vector exhibited maximal Cd2+, Cu2+, and Zn2+ bioaccumulation that was increased by 1.86 ± 0.02-, 1.71 ± 0.03-, and 2.13 ± 0.02-fold relative to that in E. coli harboring the pET28a-SUMO-ShMT vector. The present study offers a basis for the preparation of genetically engineered bacteria that are better able to bioaccumulate and tolerate heavy metals, thus providing a foundation for biological heavy metal water pollution treatment.
    • The genome and transcriptome of Trichormus sp NMC-1: insights into adaptation to extreme environments on the Qinghai-Tibet Plateau

      Qiao, Qin; Huang, Yanyan; Qi, Ji.; Qu, Mingzhi; Jiang, Chen; Lin, Pengcheng; Li, Renhui; Song, Lirong; Yonezawa, Takahiro; Hasegawa, Masami; et al. (NATURE PUBLISHING GROUP, 2016-07-06)
      The Qinghai-Tibet Plateau (QTP) has the highest biodiversity for an extreme environment worldwide, and provides an ideal natural laboratory to study adaptive evolution. In this study, we generated a draft genome sequence of cyanobacteria Trichormus sp. NMC-1 in the QTP and performed whole transcriptome sequencing under low temperature to investigate the genetic mechanism by which T. sp. NMC-1 adapted to the specific environment. Its genome sequence was 5.9 Mb with a G+C content of 39.2% and encompassed a total of 5362 CDS. A phylogenomic tree indicated that this strain belongs to the Trichormus and Anabaena cluster. Genome comparison between T. sp. NMC-1 and six relatives showed that functionally unknown genes occupied a much higher proportion (28.12%) of the T. sp. NMC-1 genome. In addition, functions of specific, significant positively selected, expanded orthogroups, and differentially expressed genes involved in signal transduction, cell wall/membrane biogenesis, secondary metabolite biosynthesis, and energy production and conversion were analyzed to elucidate specific adaptation traits. Further analyses showed that the CheY-like genes, extracellular polysaccharide and mycosporine-like amino acids might play major roles in adaptation to harsh environments. Our findings indicate that sophisticated genetic mechanisms are involved in cyanobacterial adaptation to the extreme environment of the QTP.
    • Genome sequence of the biocontrol agent coniothyrium minitans conio (IMI 134523)

      Patel, Denise; Shittu, Taiwo Adewale; Baroncelli, Riccardo; Muthumeenakshi, Sreenivasaprasad; Osborne, Thomas H.; Janganan, Thamarai K.; Sreenivasaprasad, Surapareddy; University of Bedfordshire (American Phytopathological Society, 2021-02-16)
      Coniothyrium minitans (synonym, Paraphaeosphaeria minitans) is a highly specific mycoparasite of the wide host range crop pathogen Sclerotinia sclerotiorum. The capability of C. minitans to destroy the sclerotia of S. sclerotiorum has been well recognized and it is available as a widely used biocontrol product Contans WG. We present the draft genome sequence of C. minitans Conio (IMI 134523), which has previously been used in extensive studies that formed part of a registration package of the commercial product. This work provides a distinctive resource for further research into the molecular basis of mycoparasitism to harness the biocontrol potential of C. minitans.
    • Genome sequence of the mycotoxigenic crop pathogen Fusarium proliferatum strain ITEM 2341 from date palm

      Almiman, Bandar F.; Shittu, Taiwo Adewale; Muthumeenakshi, Sreenivasaprasad; Baroncelli, Riccardo; Sreenivasaprasad, Surapareddy; University of Bedfordshire; University of Salamanca (American Society for Microbiology, 2018-09-06)
      Fusarium proliferatum is a widely distributed fungal pathogen associated with more than 26 crop species important in global food security. Its strong mycotoxigenic capability with potential impacts on human and animal health is well recognized. In this work, we report the draft genome sequence of F. proliferatum strain ITEM 2341, originally isolated from date palm, providing a platform for further comparative and functional genomic investigations.
    • Genome size diversity and its impact on the evolution of land plants

      Pellicer, Jaume; Hidalgo, Oriane; Dodsworth, Steven; Leitch, Ilia J.; Royal Botanic Gardens, Kew (MDPI AG, 2018-02-14)
      Genome size is a biodiversity trait that shows staggering diversity across eukaryotes, varying over 64,000-fold. Of all major taxonomic groups, land plants stand out due to their staggering genome size diversity, ranging ca. 2400-fold. As our understanding of the implications and significance of this remarkable genome size diversity in land plants grows, it is becoming increasingly evident that this trait plays not only an important role in shaping the evolution of plant genomes, but also in influencing plant community assemblages at the ecosystem level. Recent advances and improvements in novel sequencing technologies, as well as analytical tools, make it possible to gain critical insights into the genomic and epigenetic mechanisms underpinning genome size changes. In this review we provide an overview of our current understanding of genome size diversity across the different land plant groups, its implications on the biology of the genome and what future directions need to be addressed to fill key knowledge gaps.
    • Genome size diversity in angiosperms and its influence on gene space

      Dodsworth, Steven; Leitch, Andrew R.; Leitch, Ilia J.; Queen Mary University of London; Royal Botanic Gardens, Kew (Elsevier Ltd, 2015-11-21)
      Genome size varies c. 2400-fold in angiosperms (flowering plants), although the range of genome size is skewed towards small genomes, with a mean genome size of 1C = 5.7 Gb. One of the most crucial factors governing genome size in angiosperms is the relative amount and activity of repetitive elements. Recently, there have been new insights into how these repeats, previously discarded as ‘junk’ DNA, can have a significant impact on gene space (i.e. the part of the genome comprising all the genes and gene-related DNA). Here we review these new findings and explore in what ways genome size itself plays a role in influencing how repeats impact genome dynamics and gene space, including gene expression.
    • Genome skimming for next-generation biodiversity analysis

      Dodsworth, Steven; Queen Mary University of London; Royal Botanic Gardens, Kew (Elsevier Ltd, 2015-07-20)
    • Genome-wide repeat dynamics reflect phylogenetic distance in closely related allotetraploid Nicotiana (Solanaceae)

      Dodsworth, Steven; Jang, Tae-Soo; Struebig, Monika; Chase, Mark W.; Weiss-Schneeweiss, Hanna; Leitch, Andrew R.; Queen Mary University of London; Royal Botanic Gardens, Kew; University of Vienna; University of Western Australia (Springer-Verlag Wien, 2016-11-01)
      Nicotiana sect. Repandae is a group of four allotetraploid species originating from a single allopolyploidisation event approximately 5 million years ago. Previous phylogenetic analyses support the hypothesis of N. nudicaulis as sister to the other three species. This is concordant with changes in genome size, separating those with genome downsizing (N. nudicaulis) from those with genome upsizing (N. repanda, N. nesophila, N. stocktonii). However, a recent analysis reflecting genome dynamics of different transposable element families reconstructed greater similarity between N. nudicaulis and the Revillagigedo Island taxa (N. nesophila and N. stocktonii), thereby placing N. repanda as sister to the rest of the group. This could reflect a different phylogenetic hypothesis or the unique evolutionary history of these particular elements. Here we re-examine relationships in this group and investigate genome-wide patterns in repetitive DNA, utilising high-throughput sequencing and a genome skimming approach. Repetitive DNA clusters provide support for N. nudicaulis as sister to the rest of the section, with N. repanda sister to the two Revillagigedo Island species. Clade-specific patterns in the occurrence and abundance of particular repeats confirm the original (N. nudicaulis (N. repanda (N. nesophila ? N. stocktonii))) hypothesis. Furthermore, overall repeat dynamics in the island species N. nesophila and N. stocktonii confirm their similarity to N. repanda and the distinctive patterns between these three species and N. nudicaulis. Together these results suggest that broad-scale repeat dynamics do in fact reflect evolutionary history and could be predicted based on phylogenetic distance.
    • Genomic analysis of field pennycress (Thlaspi arvense) provides insights into mechanisms of adaptation to high elevation

      Geng, Yu-peng; Guan, Yabin; Qiong, La; Lu, Shugang; An, Miao; Crabbe, M. James C.; Qi, Ji.; Zhao, Fangqing; Qiao, Qin; Zhang, Ti-Cao; et al. (Springer Nature, 2021-07-22)
      Background: Understanding how organisms evolve and adapt to extreme habitats is of crucial importance in evolutionary ecology. Altitude gradients are an important determinant of the distribution pattern and range of organisms due to distinct climate conditions at different altitudes. High-altitude regions often provide extreme environments including low temperature and oxygen concentration, poor soil, and strong levels of ultraviolet radiation, leading to very few plant species being able to populate elevation ranges greater than 4000 m. Field pennycress (Thlaspi arvense) is a valuable oilseed crop and emerging model plant distributed across an elevation range of nearly 4500 m. Here, we generate an improved genome assembly to understand how this species adapts to such different environments. Results: We sequenced and assembled de novo the chromosome-level pennycress genome of 527.3 Mb encoding 31,596 genes. Phylogenomic analyses based on 2495 single-copy genes revealed that pennycress is closely related to Eutrema salsugineum (estimated divergence 14.32–18.58 Mya), and both species form a sister clade to Schrenkiella parvula and genus Brassica. Field pennycress contains the highest percentage (70.19%) of transposable elements in all reported genomes of Brassicaceae, with the retrotransposon proliferation in the Middle Pleistocene being likely responsible for the expansion of genome size. Moreover, our analysis of 40 field pennycress samples in two highand two low-elevation populations detected 1,256,971 high-quality single nucleotide polymorphisms. Using three complementary selection tests, we detected 130 candidate naturally selected genes in the Qinghai-Tibet Plateau (QTP) populations, some of which are involved in DNA repair and the ubiquitin system and potential candidates involved in high-altitude adaptation. Notably, we detected a single base mutation causing loss-of-function of the FLOWERING LOCUS C protein, responsible for the transition to early flowering in high-elevation populations. Conclusions: Our results provide a genome-wide perspective of how plants adapt to distinct environmental conditions across extreme elevation differences and the potential for further follow-up research with extensive data from additional populations and species.
    • Genomic repeat abundances contain phylogenetic signal

      Dodsworth, Steven; Chase, Mark W.; Kelly, Laura J.; Leitch, Ilia J.; Macas, Jiří; Novak, Petr; Piednoel, Mathieu; Weiss-Schneeweiss, Hanna; Leitch, Andrew R. (Oxford University Press, 2014-09-25)
      A large proportion of genomic information, particularly repetitive elements, is usually ignored when researchers are using next-generation sequencing. Here we demonstrate the usefulness of this repetitive fraction in phylogenetic analyses, utilizing comparative graph-based clustering of next-generation sequence reads, which results in abundance estimates of different classes of genomic repeats. Phylogenetic trees are then inferred based on the genome-wide abundance of different repeat types treated as continuously varying characters; such repeats are scattered across chromosomes and in angiosperms can constitute a majority of nuclear genomic DNA. In six diverse examples, five angiosperms and one insect, this method provides generally well-supported relationships at interspecific and intergeneric levels that agree with results from more standard phylogenetic analyses of commonly used markers. We propose that this methodology may prove especially useful in groups where there is little genetic differentiation in standard phylogenetic markers. At the same time as providing data for phylogenetic inference, this method additionally yields a wealth of data for comparative studies of genome evolution.
    • Genomics evolutionary history and diagnostics of the Alternaria alternata species group including apple and Asian pear pathotypes

      Armitage, Andrew D.; Cockerton, Helen M.; Sreenivasaprasad, Surapareddy; Woodhall, James; Lane, Charles R.; Harrison, Richard; Clarkson, John P. (Frontiers, 2020-01-23)
      The Alternaria section alternaria (Alternaria alternata species group) represents a diverse group of saprotroph, human allergens, and plant pathogens. Alternaria taxonomy has benefited from recent phylogenetic revision but the basis of differentiation between major phylogenetic clades within the group is not yet understood. Furthermore, genomic resources have been limited for the study of host-specific pathotypes. We report near complete genomes of the apple and Asian pear pathotypes as well as draft assemblies for a further 10 isolates representing Alternaria tenuissima and Alternaria arborescens lineages. These assemblies provide the first insights into differentiation of these taxa as well as allowing the description of effector and non-effector profiles of apple and pear conditionally dispensable chromosomes (CDCs). We define the phylogenetic relationship between the isolates sequenced in this study and a further 23 Alternaria spp. based on available genomes. We determine which of these genomes represent MAT1-1-1 or MAT1-2-1 idiomorphs and designate host-specific pathotypes. We show for the first time that the apple pathotype is polyphyletic, present in both the A. arborescens and A. tenuissima lineages. Furthermore, we profile a wider set of 89 isolates for both mating type idiomorphs and toxin gene markers. Mating-type distribution indicated that gene flow has occurred since the formation of A. tenuissima and A. arborescens lineages. We also developed primers designed to AMT14, a gene from the apple pathotype toxin gene cluster with homologs in all tested pathotypes. These primers allow identification and differentiation of apple, pear, and strawberry pathotypes, providing new tools for pathogen diagnostics.
    • The genotoxic potential of mixed nitrosamines in drinking water involves oxidative stress and Nrf2 activation

      Dong, Lei; Jiang, Zhiqiang; Yang, Lili; Hu, Fen; Zheng, Weiwei; Xue, Peng; Jiang, Songhui; Andersen, Melvin E.; Crabbe, M. James C.; Qu, Weidong; et al. (Elsevier, 2021-12-07)
      Nitrosamine by-products in drinking water are designated as probable human carcinogens by the IARC, but the health effects of simultaneous exposure to multiple nitrosamines in drinking water remain unknown. Genotoxicity assays were used to assess the effects of both individual and mixed nitrosamines in finished drinking water produced by a large water treatment plant in Shanghai, China. Cytotoxicity and genotoxicity were measured at 1, 10-, 100- and 1000-fold actual concentrations by the Ames test, Comet assay, γ-H2AX assay, and the cytokinesisblock micronuclei assay; oxidative stress and the Nrf2 pathway were also assessed. Nitrosamines detected in drinking water included NDMA (36.45 ng/L), NDPA (44.68 ng/L), and NEMA (37.27 ng/L). Treatment with a mixture of the three nitrosamines at 1000-fold actual drinking-water concentration induced a doubling of revertants in Salmonella typhimurium strain TA100, DNA and chromosome damage in HepG2 cells, while 1–1000-fold concentrations of compounds applied singly lacked these effects. Treatment with 100- and 1000-fold concentrations increased ROS, GSH, and MDA and decreased SOD activity. Thus, nitrosamine mixtures showed greater genotoxic potential than that of the individual compounds. N-Acetylcysteine protected against the nitrosamine-induced chromosome damage, and Nrf2 pathway activation suggested that oxidative stress played pivotal roles in the genotoxic property of the nitrosamine mixtures.
    • The geography of employment change in the hotel and catering industry of Great Britain in the 1980s: a subregional perspective

      Bull, Paul; Church, Andrew (Routledge, 1994-01-01)
      BULL P. J. and CHURCH A. P. (1994) The geography of employment change in the hotel and catering industry of Great Britain in the 1980s: a subregional perspective, Reg. Studies 28, 13-25. The hotel and catering industry was an important employment growth sector in the British economy in the 1970s and 1980s. The spatial outcomes of this growth have received virtually no research attention. Studies of this important service industry have often been encompassed by tourism research. This paper argues for a specific analysis of hotel and catering using unpublished data which outlines the subregional pattern of employment change between 1981 and 1989. A demand-side explanation examines the role of hotel and catering as a local consumer service, as a producer service and as a response to tourist demand. BULL P. J. et CHURCH A. P. (1994) La géographie de l'evolution de l'emploi dans l'hôtellerie et dans la restauration en Grande-Bretagne au cours des années 80: une perspective sous-régionale, Reg. Studies 28, 13-25. Aux années 70 et 80 l'hôtellerie et la restauration étaient des secteurs porteurs importants de l'economie britannique. Dans le domaine de la recherche on n'a guère tenu compte des impacts géographiques de cette croissance. En effet c'est la recherche du tourisme qui a souvent incorporé des études au sujet de cette industrie de services importante. Cet article propose une analyse particulière de l'hôtellerie et de la restauration à partir des données officieuses et qui esquisse la répartition sous-régionale de l'evolution de l'emploi entre 1981 et 1989. Une explication par la demande examine le rôle de l'hôtellerie et de la restauration en tant qu'un service aux consommateurs local, un service aux producte-urs et une réponse à la demande des touristes. BULL P. J. und CHURCH A. P. (1994) Die Geographie der Veränderungen in der Erwerbstätigkeit im Hotel- und Gaststättengewerbe Groβbritanniens in den achtziger Jahren: eine subregionale Analyse, Reg. Studies 28, 13-25. In den siebziger und achtiger Jahren dieses Jahrhunderts stellte die Zunahme der Erwerbstätigkeit im Hotel- und Gaststättengewerbe einen wichtigen Wachstumssektor der britischen Wirtschaft dar. Den räumlichen Resultaten dieses Wachstums hat die Forschung fast gar keine Auf-merksamkeit geschenkt. Studien dieser wichtigen Dienstlei-stungsindustrie sind oft in die Erforschung des Tourismus einbezogen worden. Dieser Aufsatz tritt fur eine spezifische Analyse des Hotel- und Gaststättengewerbes ein, wobei bisher unveröffentlichte Daten benutzt werden, in der das subregionale Muster des Beschäftigungswandels im Zeitraum 1981-1989 umrissen wird. Eine Erläuterung der Nachfrageseite untersucht die Rolle von Hotels und Gaststätten als eines Verbraucherdienstes am Orte, als eines Herstellerdienstes und als Antwort auf Nachfrage seitens des Touristen.
    • Geopolitics of tourism and academia in the Holy Land

      Ram, Yael; Isaac, Rami K.; Shamir, Omri; Burns, Peter (Routledge, 2016-10-21)
      The premise for this paper is that tourism scholars researching in Israel and Palestine are, in effect, actors in the geopolitical landscape of the Holy Land. Political tourism is a significant factor in how the Israel–Palestine geopolitical conflict is represented. The current paper provides an analysis of how tourism academics address the situation. A research team of Israeli, Palestinian and a third country origins collaborated to produce a narrative synthesis by systematically reviewing 35 academic papers selected through defined criteria. This approach minimized bias and aimed for analytical robustness and validity. Two main conclusions are derived from the analysis. First, papers tend to focus on the social, touristic and religious aspects of tourism not on the core issues of the geopolitical conflict. Second, the works did not contribute to dialogue between parties but reinforced separateness thus reflecting the political conflict.
    • Gestational diabetes mellitus (GDM) and adverse pregnancy outcome in South Asia: a systematic review

      Mistry, Sabuj Kanti; Das Gupta, Rajat; Alam, Sabiha; Kaur, Kuljeet; Shamim, Abu Ahmed; Puthussery, Shuby; BRAC University, Dhaka; University of New South Wales; University of Dhaka; University of Bedfordshire (Wiley, 2021-07-03)
      Introduction The prevalence of gestational diabetes mellitus (GDM) is increasing in developing countries including the South Asian Nations. The current study aimed to examine the association of GDM with adverse pregnancy outcomes from foetal and maternal perspectives in South Asia. Methods A systematic review was conducted including primary studies published since January 2020 from South Asian countries. Following electronic databases were searched to locate the articles: MEDLINE, EMBASE and EMCARE. Data were extracted using a customized extraction tool and methodological quality of the included studies was assessed using modified Effective Public Health Practice Project (EPHPP) quality assessment tool. Narrative synthesis was performed as statistical pooling was not possible due to the heterogeneous nature of the studies. Results Eight studies were included in the review. Overall, the review found a positive correlation between GDM and adverse foetal outcomes such as macrosomia, neonatal hyperglycaemia, intrauterine growth retardation (IUGR), stillbirths and low birthweight (LBW), but the findings were not conclusive. GDM was also positively associated with preeclampsia but the association between GDM and C-section delivery was not conclusive. Conclusion Policymakers, public health practitioners and researchers in South Asia should take in to account the link between GDM and adverse pregnancy outcomes while designing interventions to promote maternal health in South Asia. Researchers should focus on conducting longitudinal studies in future to clearly understand the epidemiology and pathobiology of this issue.
    • Getting our country back : the UK press on the eve of the EU referendum

      Rowinski, Paul (Political Studies Association, 2017-11-27)
      This paper investigates a critical discourse analysis the author has conducted of UK mainstream newspaper coverage on the eve of the EU referendum. Immigration became a key issue in the closing days. The paper will explore the possibility that the discourse moved from persuasion to prejudice and xenophobia. The paper will also argue that in the age of populist post-truth politics, some of the newspapers also employed such emotive rhetoric, designed to influence and compel the audience to draw certain conclusions – to get their country back. In so doing, it is argued some of the UK media also pose a serious threat to democracy and journalism – rather than holding those in power to account and maintaining high journalistic standards. The notion that that some of the UK media played on public perceptions and a collective memory that has created, propagated and embedded many myths about the EU for decades, is explored. The possibility this swayed many – despite limited or a lack of substantiation, is explored, a discourse of ellipsis, if you will.
    • Girls’ active identities: navigating othering discourses of femininity, bodies and physical education

      Hill, Joanne (Taylor & Francis, 2015-09-01)
      Within physical education and sport, girls must navigate discourses of valued athletic and gendered bodies that marginalise or ‘other’ non-normative performances through systems of surveillance and punishment. The purpose of this paper is to share girls’ perspectives on how these discourses affected their gender performances and activity engagement. Students aged 13-14 in one ethnically diverse UK secondary school were invited to create a photo diary of the physical activities they engaged in. Photo elicitation interviews in small groups followed. The girls positioned themselves as physically active but had to carefully manage their activity choices and gender performances in a single-sex physical education environment that regulated deviation from the fit, slender, girly girl. Although the girls demonstrate the difficulty of resisting, they indicate moments of positioning themselves against norms that suggest the possibilities of shifting gendering processes. The paper points out the importance of listening to ‘other’ girls’ narratives in building positive physical education engagements.
    • ‘Give ‘em the old razzle dazzle’: surviving the lesson observation process in further education

      Thompson, Carol; Wolstencroft, Peter; University of Bedfordshire (Routledge, 2014-07-07)
      This paper examines the key role that graded lesson observations have within the measurement of quality in the post-compulsory education sector. Using semi-structured interviews, it looks at their impact on participants and also their execution in light of their stated purpose to ‘improve teaching and learning’. The sample selected included teachers, quality managers and initial teacher educators and covers a geographical spread from the north Midlands to London. The findings suggest that the lessons observed bore scant resemblance to the day-to-day teaching of participants. Instead teachers talked of the need to ‘put on a show’ and how they treated the annual observation with a mixture of trepidation and cynicism. The realisation that observations failed to measure what they were designed to measure was shared by other participants with quality managers, ostensibly the people who were employed to raise standards, also acknowledging the limitations of the process. The observation process was designed to reward outstanding practitioners, however, teachers talked about their reluctance to strive for outstanding grades due to the perceived onerous duties associated with achieving a top grade. Instead teachers talked about the way in which they aimed for a grade two in order to maintain a low profile. Despite the widespread cynicism amongst all participants, there was a universal belief that some form of measurement was needed to ensure that standards were maintained.
    • The Gli3 transcription factor expressed in the thymus stroma controls thymocyte negative selection via Hedgehog-dependent and -independent mechanisms

      Hager-Theodorides, Ariadne L.; Furmanski, Anna L.; Ross, Susan; Outram, Susan V.; Rowbotham, Nicola J.; Crompton, Tessa (American Association of Immunologists, 2009-08-20)
      The Hedgehog (Hh) responsive transcription factor Gli3 is required for efficient thymocyte development in the fetus. In this study we show that Gli3, not detected in adult thymocytes, is expressed in the murine fetal and adult thymus stroma. PCR array analysis revealed Cxcl9, Rbp1, and Nos2 as novel target genes of Gli3. We show that Gli3 positively regulates the expression of these genes, most likely by suppressing an intermediate repressor. Deletion of autoreactive thymocytes depends on their interactions with the thymus stroma. Repression of the proapoptotic gene Nos2 in Gli3 mutants coincides with reduced apoptosis of double positive thymocytes undergoing negative selection in vitro and in vivo, and the production of autoreactive thymocytes. Taken together these data indicate that Gli3 controls thymocyte apoptosis and negative selection possibly via the regulation of Nos2. Defective Gli3 expression in the thymus stroma also resulted in decreased CD5 expression on mature thymocytes and inappropriate production of MHC class I-selected CD4+ cells, both consistent with reduced TCR signal strength. Overall our data indicate that Gli3 expressed in the thymus stroma regulates negative selection and TCR signal strength via Hh-dependent and -independent mechanisms, with implications for autoimmunity.
    • Global and regional left ventricular circumferential strain during incremental cycling and isometric knee extension exercise

      Beaumont, Alexander; Sculthorpe, Nicholas; Hough, John; Unnithan, Viswanath; Richards, Joanna C. (Wiley, 2018-04-16)
      Background: The objective of this study was to investigate left ventricular (LV) circumferential strain responses to incremental cycling and isometric knee extension exercises. Methods: Twenty-six healthy male participants (age = 30 ± 6 years) were used to study LV global (GCS) and regional circumferential strain at the apex (ACS) and base (BCS) during incremental cycling at 30% and 60% work rate maximum (Wmax) and short-duration (15 seconds contractions) isometric knee extensions at 40% and 75% maximum voluntary contraction (MVC) using two-dimensional speckle tracking echocardiography. Results: During cycling (n = 22), GCS increased progressively from rest to 60% Wmax (−22.85 ± 3.26% to −29.87 ± 2.59%, P < .01). ACS increased from rest to 30% Wmax (−26.29 ± 4.84% to −36.84 ± 6.94%, P < .01) and then remained unchanged to 60% Wmax (−40.72 ± 4.06%, P = .068). BCS decreased from rest to 30% Wmax (−19.41 ± 2.79 to −17.51 ± 4.66%, P = .05) and then remained unchanged to 60% Wmax. During isometric knee extension (n = 23), GCS decreased from rest to 40% MVC (−22.63 ± 3.46 to −20.10 ± 2.78%, P < .05) and then remained unchanged to 75% MVC. Similarly, BCS decreased from rest to 40% MVC (−19.21 ± 2.58% to −13.55 ± 3.45%, P < .01) and then remained unchanged, whereas ACS did not change with exercise intensity (rest, −26.05 ± 5.34%; 40% MVC, −26.64 ± 4.53% and 75% MVC −27.22 ± 5.34%, all P > .05). Conclusion: Global circumferential strain increased stepwise during incremental cycling, mediated by the apex with trivial changes at the base. In contrast, GCS decreased during the isometric knee extension to 40% MVC and then plateaued, due to decreased BCS as ACS was maintained. A novel finding is that the GCS response appears to be exercise modality dependant and is the consequence of region-specific changes.