Brominated flame retardants and biomagnification factors in marine species in the North-East Atlantic

BACKGROUND: Concentrations of brominated flame retardants (BFRs) are reported to increase in marine ecosystems. OBJECTIVES: Characterize exposure to BFRs in animals from different trophic levels in North-East Atlantic coastal marine ecosystems along a latitudinal gradient from southern Norway to Spitsbergen, Svalbard, in the Arctic. Calanoid species were collected from the Oslofjord (59°N), Froan (64°N), and Spitsbergen (> 78°N); Atlantic cod (Gadus morhua) from the Oslofjord and Froan; polar cod (Boreogadus saida) from Bear Island (74°N) and Spitsbergen; harbor seal (Phoca vitulina) from the Oslofjord, Froan, and Spitsbergen; and ringed seal (Phoca vitulina) from Spitsbergen. Eggs of common tern (Sterna hirundo) were collected from the Oslofjord, and eggs of arctic terns (Sterna paradisaea) from Froan and Spitsbergen. RESULTS: Levels of polybrominated diphenylethers (PBDEs) and hexabromocyclododecane (HBCD) generally decreased as a function of increasing latitude, reflecting distance from release sources. The clear latitudinal decrease in levels of BFRs was not pronounced in the two tern species, most likely because they are exposed during migration. The decabrominated compound BDE-209 was detected in animals from all three ecosystems, and the highest levels were found in arctic tern eggs from Spitsbergen. HBCD was found in animals from all trophic levels, except for in calanoids at Froan and Spitsbergen. CONCLUSIONS: Even though the levels of PBDEs and HBCD are generally low in North-East Atlantic coastal marine ecosystems, there are concerns about the relatively high presence of BDE-209 and HBCD.

Seawater carbonate chemistry and trace element accumulation during experiments with common cuttlefish, Sepia officinalis, 2009

Cephalopods play a key role in many marine trophic networks and constitute alternative fisheries resources, especially given the ongoing decline in finfish stocks. Along the European coast, the eggs of the cuttlefish Sepia officinalis are characterized by an increasing permeability of the eggshell during development, which leads to selective accumulation of essential and non-essential elements in the embryo. Temperature and pH are two critical factors that affect the metabolism of marine organisms in the coastal shallow waters. In this study, we investigated the effects of pH and temperature through a crossed (3?2; pH 8.1 (pCO2, 400 ppm), 7.85 (900 ppm) and 7.6 (1400 ppm) at 16 and 19°C, respectively) laboratory experiment. Seawater pH showed a strong effect on the egg weight and non-significant impact on the weight of hatchlings at the end of development implying an egg swelling process and embryo growth disturbances. The lower the seawater pH, the more 110 mAg was accumulated in the tissues of hatchlings. The 109Cd concentration factor (CF) decreased with decreasing pH and 65Zn CF reached maximal values pH 7.85, independently of temperature. Our results suggest that pH and temperature affected both the permeability properties of the eggshell and embryonic metabolism. To the best of our knowledge, this is one of the first studies on the consequences of ocean acidification and ocean warming on metal uptake in marine organisms, and our results indicate the need to further evaluate the likely ecotoxicological impact of the global change on the early-life stages of the cuttlefish.

PROGNOSTIC FACTORS PREDICTING FUNCTIONAL OUTCOME AT FOUR MONTHS FOLLOWING ACUTE ANKLE SPRAIN

PROGNOSTIC FACTORS PREDICTING FUNCTIONAL OUTCOME AT FOUR MONTHS FOLLOWING ACUTE ANKLE SPRAINBleakley C.M.1, O'Connor S.R.1, Tully M.A.2, Rocke L.G.3, MacAuley D.C.1, Bradbury I.4, Keegan S.4, McDonough S.M.11University of Ulster, Health & Rehabilitation Sciences Research Institute, Newtownabbey, United Kingdom, 2Queen's University, UKCRC Centre of Excellence for Public Health (NI), Belfast, United Kingdom, 3Royal Victoria Hospital, Department of Emergency Medicine, Belfast, United Kingdom, 4Frontier Science (Scotland), Kincraig, Inverness-shire, United KingdomPurpose: To identify clinically relevant factors assessed following acute ankle sprain that predict functional recovery at four months post-injury.Relevance: Ankle sprains are one of the most common musculoskeletal injuries with an estimated 5000 new cases occurring each day in the United Kingdom. In the acute phase, ankle sprains may be associated with pain and loss of function. In the longer-term there is a risk of residual problems including chronic pain or reinjury. Few studies have sought to examine factors associated with a poor long-term prognosis.Participants: 101 patients (Age: Mean (SD) 25.9 (7.9) years; Body Mass Index (BMI): 25.3 (3.5) kg/m2) with an acute grade 1 or 2 ankle sprain attending an accident and emergency department or sports injury clinic. Exclusion criteria included complete (grade 3) rupture of the ankle ligament complex, bony ankle injury or multiple injuries.Methods: Participants were allocated as part of a randomised controlled trial to an accelerated intervention incorporating intermittent ice and early therapeutic exercise or a standard protection, rest, ice, compression, and elevation intervention for one week. Treatment was then standardised in both groups and consisted of ankle rehabilitation exercises focusing on muscle strengthening, neuromuscular training, and sports specific functional exercises for a period of approximately four to six weeks. On initial assessment age, gender, mechanism of injury, presence of an audible pop or snap and the presence of contact during the injury were recorded. The following factors were also recorded at baseline and at one and four weeks post-injury: weight-bearing dorsi-flexion test, lateral hop test, presence of medial pain on palpation and a positive impingement sign. Functional status was assessed using the Karlsson score at baseline, at week four and at four months. Reinjury rates were recorded throughout the intervention phase and at four months.Analysis: A mixed between-within subjects analysis of variance (ANOVA) was used to determine the effect of each factor on functional status at week four and at four months. Significance was set at a Bonferroni adjusted level of 0.0125 (0.05/4).Results: Eighty-five participants (84%) were available at final follow-up assessment. Pain on weight-bearing dorsi-flexion and lateral hop tests at week four were both associated with a lower functional score at four months post-injury (P = 0.011 and P = 0.001). No other significant interactions were observed at any other timepoint (baseline or week one). There were only two reinjuries within the four month follow-up period with a further two reported at approximately six months post-injury. We were therefore unable to determine whether any factors were associated with an increased risk of reinjury.Conclusions: Potential prognostic factors on initial or early examination after acute ankle sprain did not help predict functional recovery at four months post-injury. However, pain on weight-bearing dorsi-flexion and lateral hop tests observed at four weeks were associated with a slower rate of recovery.Implications: Some clinical tests may help identify patients at risk of poor functional recovery after acute ankle sprain. However, further work is required to examine factors which may be predictive on initial assessment.Key-words: 1. Prognostic factors 2. Recovery 3. Ankle sprainFunding acknowledgements: Physiotherapy Research Foundation, Chartered Society of Physiotherapy, Strategic Priority Fund; Department of Employment and Learning, Northern Ireland.Ethics approval: Office for Research Ethics Committee (UK).

Genomics and virulence factors of Fusobacterium necrophorum

Fusobacterium necrophorum, a Gram negative, anaerobic bacterium, is a common cause of acute pharyngitis and tonsillitis and a rare cause of more severe infections of the head and neck. At the beginning of the project, there was no available genome sequence for F. necrophorum. The aim of this project was to sequence the F. necrophorum genome and identify and study its putative virulence factors contained using in silico and in vitro analysis. Type strains JCM 3718 and JCM 3724,F. necrophorum subspecies necrophorum (Fnn) and funduliforme (Fnf), respectively, and strain ARU 01 (Fnf), isolated from a patient with LS, were commercially sequenced by Roche 454 GS-FLX+ next generation sequencing and assembled into contigs using Roche GS Assembler. Sequence data was annotated semi-automatically, using the xBASE pipeline, BLASTp and Pfam. The F. necrophorum genome was determined to be approximately 2.1 – 2.3 Mb in size, with an estimated 1,950 ORFs and includes genes for a leukotoxin, ecotin, haemolysin, haemagglutinin, haemin receptor, adhesin and type Vb and Vc secretion systems. The prevalence of the leukotoxin gene was investigated in strains JCM 3718, JCM 3724 and ARU 01, as well as a clinical collection of 25 Fnf strains, identified using biochemical and molecular tests. The leukotoxin operon was found to be universal within the strain collection by PCR. HL-60 cells subjected to aliquots of concentrated high molecular weight culture supernatant, predicted to contain the secreted leukotoxins of strains JCM 3718, JCM 3724 and ARU 01, were killed in a dose-dependent manner. The cytotoxic effect of the leukotoxin against human donor white blood cells was also tested to validate the HL-60 assay. The differences in the results between the two assays were not statistically significant. Ecotin, a serine protease inhibitor, was found to be present in 100 % of the strain collection and had a highly conserved sequence with primary and secondary binding sites exposed on opposing sides of the protein. During enzyme inhibition studies, a purified recombinant F. necrophorum ecotin protein inhibited human neutrophil elastase, a protease that degrades bacteria at inflammation sites, and human plasma kallikrein, a component of the host clotting cascade. The recombinant ecotin also prolonged human plasma clotting times by up to 7-fold for the extrinsic pathway, and up to 40-fold for the intrinsic pathway. The genome sequence data provides important information about F. necrophorum type strains and enables comparative study between strains and subspecies. Results from the leukotoxin and ecotin assays can be used to build up an understanding of how the organism behaves during infection.

Organisational and systems factors impacting on patient safety in acute care organisations: lessons from four multi-site research studies

Background Patient safety is concerned with preventable harm in healthcare, a subject that became a focus for study in the UK in the late 1990s. How to improve patient safety, presented both a practical and a research challenge in the early 2000s, leading to the eleven publications presented in this thesis. Research question The overarching research question was: What are the key organisational and systems factors that impact on patient safety, and how can these best be researched? Methods Research was conducted in over 40 acute care organisations in the UK and Europe between 2006 and 2013. The approaches included surveys, interviews, documentary analysis and non-participant observation. Two studies were longitudinal. Results The findings reveal the nature and extent of poor systems reliability and its effect on patient safety; the factors underpinning cases of patient harm; the cultural issues impacting on safety and quality; and the importance of a common language for quality and safety across an organisation. Across the publications, nine key organisational and systems factors emerged as important for patient safety improvement. These include leadership stability; data infrastructure; measurement capability; standardisation of clinical systems; and creating an open and fair collective culture where poor safety is challenged. Conclusions and contribution to knowledge The research presented in the publications has provided a more complete understanding of the organisation and systems factors underpinning safer healthcare. Lessons are drawn to inform methods for future research, including: how to define success in patient safety improvement studies; how to take into account external influences during longitudinal studies; and how to confirm meaning in multi-language research. Finally, recommendations for future research include assessing the support required to maintain a patient safety focus during periods of major change or austerity; the skills needed by healthcare leaders; and the implications of poor data infrastructure.

Arabidopsis MYC transcription factors are the target of hormonal salicylic acid/jasmonic acid cross talk in response to Pieris brassicae egg extract.

Arabidopsis (Arabidopsis thaliana) plants recognize insect eggs and activate the salicylic acid (SA) pathway. As a consequence, expression of defense genes regulated by the jasmonic acid (JA) pathway is suppressed and larval performance is enhanced. Cross talk between defense signaling pathways is common in plant-pathogen interactions, but the molecular mechanism mediating this phenomenon is poorly understood. Here, we demonstrate that egg-induced SA/JA antagonism works independently of the APETALA2/ETHYLENE RESPONSE FACTOR (AP2/ERF) transcription factor ORA59, which controls the ERF branch of the JA pathway. In addition, treatment with egg extract did not enhance expression or stability of JASMONATE ZIM-domain transcriptional repressors, and SA/JA cross talk did not involve JASMONATE ASSOCIATED MYC2-LIKEs, which are negative regulators of the JA pathway. Investigating the stability of MYC2, MYC3, and MYC4, three basic helix-loop-helix transcription factors that additively control jasmonate-related defense responses, we found that egg extract treatment strongly diminished MYC protein levels in an SA-dependent manner. Furthermore, we identified WRKY75 as a novel and essential factor controlling SA/JA cross talk. These data indicate that insect eggs target the MYC branch of the JA pathway and uncover an unexpected modulation of SA/JA antagonism depending on the biological context in which the SA pathway is activated.

Should I stay or should I go – Factors associated with hospitalization risk among older persons in Sweden

An increasingly older population will most likely lead to greater demands on the health care system, as older age is associated with an increased risk of having acute and chronic conditions. The number of diseases or disabilities is not the only marker of the amount of health care utilized, as persons may seek hospitalization without a disease and/or illness that requires hospital healthcare. Hospitalization may pose a severe risk to older persons, as exposure to the hospital environment may lead to increased risks of iatrogenic disorders, confusion, falls and nosocomial infections, i.e., disorders that may involve unnecessary suffering and lead to serious consequences. Aims: The overall aim of this thesis was to describe and explore individual trajectories of cognitive development in relation to hospitalization and risk factors for hospitalization among older persons living in different accommodations in Sweden and to explore older persons' reasons for being transferred to a hospital. Methods: The study designs were longitudinal, prospective and descriptive, and both quantitative and qualitative methods were used. Specifically, latent growth curve modelling was used to assess the association of cognitive development with hospitalization. The Cox proportional hazards regression model was used to analyse factors associated with hospitalization risk overtime. In addition, an explorative descriptive design was used to explore how home health care patients experienced and perceived their decision to seek hospital care. Results: The most common reasons for hospitalization were cardiovascular diseases, which caused more than one-quarter of first hospitalizations among the persons living in ordinary housing and nursing home residents (NHRs). The persons who had been hospitalized had a lower mean level of cognitive performance in general cognition, verbal, spatial/fluid, memory and processing speed abilities compared to those who had not been hospitalized. Significantly steeper declines in general cognition, spatial/fluid and processing speed abilities were observed among the persons who had been hospitalized. Cox proportional hazards regression analysis showed that the number of diseases, number of drugs used, having experienced a fall and being assessed as malnourished according to the Mini Nutritional Assessment scale were related to an increased hospitalization risk among the NHRs. Among the older persons living in ordinary housing, the risk factors for hospitalization were related to marital status, i.e., unmarried persons and widows/widowers had a decreased hospitalization risk. In addition, among social factors, receipt of support from relatives was related to an increased hospitalization risk, while receipt of support from friends was related to a decreased risk. The number of illnesses was not associated with the hospitalization risk for older persons in any age group or for those of either sex, when controlling for other variables. The older persons who received home health care described different reasons for their decisions to seek hospital care. The underlying theme of the home health care patients’ perceptions of their transfer to a hospital involved trust in hospitals. This trust was shared by the home health care patients, their relatives and the home health care staff, according to the patients. Conclusions: This thesis revealed that middle-aged and older persons who had been hospitalized exhibited a steeper decline in cognition. Specifically, spatial/fluid, processing speed, and general cognitive abilities were affected. The steeper decline in cognition among those who had been hospitalized remained even after controlling for comorbidities. The most common causes of hospitalization among the older persons living in ordinary housing and in nursing homes were cardiovascular diseases, tumours and falls. Not only health-related factors, such as the number of diseases, number of drugs used, and being assessed as malnourished, but also social factors and marital status were related to the hospitalization risk among the older persons living in ordinary housing and in nursing homes. Some risk factors associated with hospitalization differed not only between the men and women but also among the different age groups. The information provided in this thesis could be applied in care settings by professionals who interact with older persons before they decide to seek hospital care. To meet the needs of an older population, health care systems need to offer the proper health care at the most appropriate level, and they need to increase integration and coordination among health care delivered by different care services.

Role of fibroblast growth factors and their receptors in prostate cancer

Prostate cancer (PCa) is the most common non-cutaneous malignant disease among males in the developed countries. Radical prostatectomy (RP) is an effective therapy for most PCa patients with localized or locally invaded tumors but in some cases the cancer recurs after RP. PCa is a heterogeneous disease, which is regulated by many factors, such as androgen receptor (AR), estrogen receptors and  (ER and ER), fibroblast growth factors (FGFs) and their receptors (FGFRs). In this study, the role of ERβ, FGF8, FGF13 and FGFRL1 was investigated in PCa. Previous studies have suggested that ER is protective against PCa whereas FGF8 has been shown to induce PCa in transgenic mice. FGF13 and FGFRL1 are poorly understood members of the FGF and FGFR families, respectively. Transgenic mouse models were used to investigate the ability of inactivated ERβ to facilitate FGF8-induced prostate tumorigenesis. Human PCa tissue microarrays (TMAs) were used to study the expression pattern of FGF13 and FGFRL1 in PCa and the results were correlated to corresponding patient data. The targets and biological functions of FGF13 and FGFRL1 were characterized using experimental in vivo and in vitro models. The results show that deficiency of ERβ, which had been expected to have tumor suppressing capacity, seemed to influence epithelial differentiation but did not affect FGF8-induced prostate tumorigenesis. Analysis of the TMAs showed increased expression of FGF13 in PCa. The level of cytoplasmic FGF13 was associated with the PCa biochemical recurrence (BCR), demonstrated by increasing serum PSA value, and was able to act as an independent prognostic biomarker for PCa patients after RP. Expression of FGFRL1, the most recently identified FGFR, was also elevated in PCa. Cytoplasmic and nuclear FGFRL1 was associated with high Gleason score and Ki67 level whereas the opposite was true for the cell membrane FGFRL1. Silencing of FGFRL1 in PC-3M cells led to a strongly decreased growth rate of these cells as xenografts in nude mice and the experiments with PCa cell lines showed that FGFRL1 is able to modulate the FGF2- and FGF8-induced signaling pathways. The next generation sequencing (NGS) experiments with FGFRL1-silenced PC-3M cells revealed candidates for FGFRL1 target genes. In summary, these studies provide new data on the FGF/FGFR signaling pathways in normal and malignant prostate and suggest a potential role for FGF13 and FGFRL1 as novel prognostic markers for PCa patients. Keywords: FGF8, FGF13, FGFRL1, ERβ, prostate cancer, prognostic marker

Postoperative Bowel Function and Related Factors in Enhanced Recovery Protocol with Patients Undergoing Hepatectomy

Patients’ bowel dysfunction is a major factor that weakens the results of surgical care as it can cause pain and weaken patients’ rehabilitation. Bowel dysfunction is a common postoperative problem, yet most incidents remain undocumented. The nursing profession has a significant role in enhancing the bowel function postoperatively. However, studies of postoperative bowel function after hepatectomy are scarce and somewhat incongruous. Enhanced recovery protocols are innovative models of care aiming for better outcomes of surgical care. Enhanced recovery protocols can improve gastrointestinal function after surgery, yet patients are also known to be satisfied with their care. The aim was to investigate if postoperative bowel function day varies between patients in terms of age, gender, ASA score, type of surgery, histology, patients’ experienced pain and experienced satisfaction three days after discharge and three months after operation in patients undergoing hepatectomy. The goal was to produce information for basis of scientific research, to give nurses in clinical setting more tools to work with hepatectomy patients undergoing enhanced recovery protocol and to produce information to nurse managers to use in process management of patients undergoing enhanced recovery protocol. The design of this study is descriptive. Data was collected retrospectively from hepatectomy patients (n = 134) undergoing enhanced recovery protocol within the first year of enhanced recovery protocol implementation. The data was based on registers and analyzed statistically. Mean age of patients was 62 years and mean day of discharge was 4. Main (n = 72) histology of the patients was colorectal liver metastases. Mean bowel function day was 3. Most of the patients were very satisfied or satisfied with the care three days after discharge (99%) and three months (90%) after operation. Most of the patients (72%) experienced moderate pain three days after discharge, but three months after operation 47% of the patients did not experience pain and 48% experienced moderate pain. There were no statistically significant differences in bowel function between different age groups, genders, ASA score groups or histologies. Neither were there statistically significant differences in postoperative bowel function in terms of experienced satisfaction or pain. There were statistically significant differences in postoperative bowel function between different types of surgery (p < 0.01). Nurses should take into consideration hepatectomy patients’ type of surgery and pay special attention in supporting major open hepatectomy patients’ postoperative bowel function. Nurses should educate patients undergoing major open hepatectomy about prolonged postoperative bowel function.

Creating Common Ground: Architecture For Tactical Learning and Creative Convergence

Certain environments can inhibit learning and stifle enthusiasm, while others enhance learning or stimulate curiosity. Furthermore, in a world where technological change is accelerating we could ask how might architecture connect resource abundant and resource scarce innovation environments? Innovation environments developed out of necessity within urban villages and those developed with high intention and expectation within more institutionalized settings share a framework of opportunity for addressing change through learning and education. This thesis investigates formal and informal learning environments and how architecture can stimulate curiosity, enrich learning, create common ground, and expand access to education. The reason for this thesis exploration is to better understand how architects might design inclusive environments that bring people together to build sustainable infrastructure encouraging innovation and adaptation to change for years to come. The context of this thesis is largely based on Colin McFarlane’s theory that the “city is an assemblage for learning” The socio-spatial perspective in urbanism, considers how built infrastructure and society interact. Through the urban realm, inhabitants learn to negotiate people, space, politics, and resources affecting their daily lives. The city is therefore a dynamic field of emergent possibility. This thesis uses the city as a lens through which the boundaries between informal and formal logics as well as the public and private might be blurred. Through analytical processes I have examined the environmental devices and assemblage of factors that consistently provide conditions through which learning may thrive. These parameters that make a creative space significant can help suggest the design of common ground environments through which innovation is catalyzed.

The bioaccumulation of persistent contaminants by zebra mussels and their effects on state-endangered common terns

Common terns currently are listed as endangered or threatened in many states, including Illinois, Vermont, Pennsylvania, Ohio, Wisconsin, Michigan, and New York, and a species of special concern by the U.S. Fish and Wildlife Service (USFWS, 2002). The sole remaining nesting colony in Illinois is located at the Naval Station Great Lakes (NSGL) in Lake County where intensive management by the Illinois Department of Natural Resources has reduced nest predation and increased the number of eggs that hatch. However, the overall reproductive success (the number of young successfully reaching independence) has not improved. Observations of gross deformities in hatchlings (i.e. compromised feather development and cross-bill), lethargic behavior of young birds, and lesions, suggested the influence of environmental contaminants (Jablonski et al., 2005). I investigated if there were significant levels of environmental contaminants in eggs and nestlings of common terns. While there were minimal concentration of selenium, mercury, lead, and cadmium, there were large concentration of polychlorinated biphenyls (PCBs) in both the eggs and nestlings. The greater amounts of PCBs in older chicks than younger chicks suggest local contamination. In order to potentially manage the factors responsible for exposing the terns to PCBs I investigated the pathway by which PCBs were exposed to terns. The two most likely biological pathways as determined by research on Great Lake fishes were investigated. The first pathway is through atmospheric deposition of PCBs and resuspension of PCB-ladel sediment which are subsequently acquired by filter-feeding fish (e.g. alewives, Alosa pseudoharengus) and then pelagic fish (e.g. lake trout, Salvelinus namaychus) or in this case terns. The second pathway explored was via the biodeposits of zebra mussels which are consumed by round gobies (Neogobius melanostromus) and ultimately littoral fish (e.g. small-mouthed bass, Micropterus dolomieui) or terns. Because common terns breed in near-shore sites where concentrations of zebra mussels are found, as well as forage in more pelagic environments it is possible that either or both pathways may be contributing to their PCB exposure. Field experiments and stable isotope analyses demonstrated that the most likely pathway by which terns are exposed to PCBs is via alewives, similar to how apex predators such as lake trout acquire PCBs. Biodeposits from zebra mussels do not appear to be a significant factor in PCB accumulation in terns. The impact of PCB exposure on birds can vary widely, however in this situation we choise to investigate one specific behavior often affected by PCB exposure, parental attentiveness. PCBs are known to cause endocrine disruption which ultimately results in reduced brooding of young and incubation of eggs. I used temperature sensors to quantify nest temperatures and parental attentiveness during incubation. High concentrations of PCBs in our study population appear to be leading to poor parental attentiveness, and extended periods of absence during incubation and brooding, ultimately leading to poor reproductive success. Common terns are perilously close to being extirpated in Illinois and management of PCB exposure will be difficult. I propose that additional testing should be conducted to locate a site with less PCB contamination and then to move the tern colony to this location, possibly using social cues as has been done with other tern species in Illinois. PCBs are having a profound impact on common tern populations in Illinois and without moving the colony it is likely that the population will continue to decline.

The prevalence and factors associated with knee pain in Great Britain's Olympians aged 40 years and older.

Purpose: affecting approximately one in four adults over the age of 40 years in the UK, knee pain is the most common presenting feature of osteoarthritis (OA). Despite the plethora of studies that have investigated the factors associated with the onset of knee pain in the sedentary population, relatively little is known about the prevalence and occupational factors associated with knee pain in an athletic sporting population. This study aimed to determine in Great Britain’s (GB) Olympians, aged 40 years and older, (1) the individual factors.

Physiological and molecular analysis of the interaction between aluminium toxicity and drought stress in common bean (Phaseolus vulgaris)

Aluminium (Al) toxicity and drought are two major factors limiting common bean (Phaseolus vulgaris) production in the tropics. Short-term effects of Al toxicity and drought stress on root growth in acid, Al-toxic soil were studied, with special emphasis on Al-drought interaction in the root apex. Root elongation was inhibited by both Al and drought. Combined stresses resulted in a more severe inhibition of root elongation than either stress alone. This result was different from the alleviation of Al toxicity by osmotic stress (-0.60 MPa polyethylene glycol) in hydroponics. However, drought reduced the impact of Al on the root tip, as indicated by the reduction of Al-induced callose formation and MATE expression. Combined Al and drought stress enhanced up-regulation of ACCO expression and synthesis of zeatin riboside, reduced drought-enhanced abscisic acid (ABA) concentration, and expression of NCED involved in ABA biosynthesis and the transcription factors bZIP and MYB, thus affecting the regulation of ABA-dependent genes (SUS, PvLEA18, KS-DHN, and LTP) in root tips. The results provide circumstantial evidence that in soil, drought alleviates Al injury, but Al renders the root apex more drought-sensitive, particularly by impacting the gene regulatory network involved in ABA signal transduction and cross-talk with other phytohormones necessary for maintaining root growth under drought.

Alteration of cell-wall porosity is involved in osmotic stress-induced enhancement of aluminium resistance in common bean (Phaseolus vulgaris L.)

Aluminium (Al) toxicity and drought are the two major abiotic stress factors limiting common bean production in the tropics. Using hydroponics, the short-term effects of combined Al toxicity and drought stress on root growth and Al uptake into the root apex were investigated. In the presence of Al stress, PEG 6000 (polyethylene glycol)-induced osmotic (drought) stress led to the amelioration of Al-induced inhibition of root elongation in the Al-sensitive genotype VAX 1. PEG 6000 (>> PEG 1000) treatment greatly decreased Al accumulation in the 1 cm root apices even when the roots were physically separated from the PEG solution using dialysis membrane tubes. Upon removal of PEG from the treatment solution, the root tips recovered from osmotic stress and the Al accumulation capacity was quickly restored. The PEG-induced reduction of Al accumulation was not due to a lower phytotoxic Al concentration in the treatment solution, reduced negativity of the root apoplast, or to enhanced citrate exudation. Also cell-wall (CW) material isolated from PEG-treated roots showed a low Al-binding capacity which, however, was restored after destroying the physical structure of the CW. The comparison of the Al(3+), La(3+), Sr(2+), and Rb(+) binding capacity of the intact root tips and the isolated CW revealed the specificity of the PEG 6000 effect for Al. This could be due to the higher hydrated ionic radius of Al(3+) compared with other cations (Al(3+) >> La(3+) > Sr(2+) > Rb(+)). In conclusion, the results provide circumstantial evidence that the osmotic stress-inhibited Al accumulation in root apices and thus reduced Al-induced inhibition of root elongation in the Al-sensitive genotype VAX 1 is related to the alteration of CW porosity resulting from PEG 6000-induced dehydration of the root apoplast.

Prevalence and associations of Trypanosoma spp. and Sodalis glossinidius with intrinsic factors of tsetse flies

Trypanosomiasis has been identified as a neglected tropical disease in both humans and animals in many regions of sub-Saharan Africa. Whilst assessments of the biology of trypanosomes, vectors, vertebrate hosts and the environment have provided useful information about life cycles, transmission, and pathogenesis of the parasites that could be used for treatment and control, less information is available about the effects of interactions among multiple intrinsic factors on trypanosome presence in tsetse flies from different sites. It is known that multiple species of tsetse flies can transmit trypanosomes but differences in their vector competence has normally been studied in relation to individual factors in isolation, such as: intrinsic factors of the flies (e.g. age, sex); habitat characteristics; presence of endosymbionts (e.g. Wigglesworthia glossinidia, Sodalis glossinidius); feeding pattern; host communities that the flies feed on; and which species of trypanosomes are transmitted. The purpose of this study was to take a more integrated approach to investigate trypanosome prevalence in tsetse flies. In chapter 2, techniques were optimised for using the Polymerase Chain Reaction (PCR) to identify species of trypanosomes (Trypanosoma vivax, T. congolense, T. brucei, T. simiae, and T. godfreyi) present in four species of tsetse flies (Glossina austeni, G. brevipalpis, G. longipennis and G. pallidipes) from two regions of eastern Kenya (the Shimba Hills and Nguruman). Based on universal primers targeting the internal transcribed spacer 1 region (ITS-1), T. vivax was the predominant pathogenic species detected in flies, both singly and in combination with other species of trypanosomes. Using Generalised Linear Models (GLMs) and likelihood ratio tests to choose the best-fitting models, presence of T. vivax was significantly associated with an interaction between subpopulation (a combination between collection sites and species of Glossina) and sex of the flies (X2 = 7.52, df = 21, P-value = 0.0061); prevalence in females overall was higher than in males but this was not consistent across subpopulations. Similarly, T. congolense was significantly associated only with subpopulation (X2 = 18.77, df = 1, P-value = 0.0046); prevalence was higher overall in the Shimba Hills than in Nguruman but this pattern varied by species of tsetse fly. When associations were analysed in individual species of tsetse flies, there were no consistent associations between trypanosome prevalence and any single factor (site, sex, age) and different combinations of interactions were found to be significant for each. The results thus demonstrated complex interactions between vectors and trypanosome prevalence related to both the distribution and intrinsic factors of tsetse flies. The potential influence of the presence of S. glossinidius on trypanosome presence in tsetse flies was studied in chapter 3. A high number of Sodalis positive flies was found in the Shimba Hills, while there were only two positive flies from Nguruman. Presence or absence of Sodalis was significantly associated with subpopulation while trypanosome presence showed a significant association with age (X2 = 4.65, df = 14, P-value = 0.0310) and an interaction between subpopulation and sex (X2 = 18.94, df = 10, P-value = 0.0043). However, the specific associations that were significant varied across species of trypanosomes, with T. congolense and T. brucei but not T. vivax showing significant interactions involving Sodalis. Although it has previously been concluded that presence of Sodalis increases susceptibility to trypanosomes, the results presented here suggest a more complicated relationship, which may be biased by differences in the distribution and intrinsic factors of tsetse flies, as well as which trypanosome species are considered. In chapter 4 trypanosome status was studied in relation to blood meal sources, feeding status and feeding patterns of G. pallidipes (which was the predominant fly species collected for this study) as determined by sequencing the mitochondrial cytochrome B gene using DNA extracted from abdomen samples. African buffalo and African elephants were the main sources of blood meals but antelopes, warthogs, humans, giraffes and hyenas were also identified. Feeding on multiple hosts was common in flies sampled from the Shimba Hills but most flies from Nguruman had fed on single host species. Based on Multiple Correspondence Analysis (MCA), host-feeding patterns showed a correlation with site of sample collection and Sodalis status, while trypanosome status was correlated with sex and age of the flies, suggesting that recent host-feeding patterns from blood meal analysis cannot predict trypanosome status. In conclusion, the complexity of interactions found suggests that strategies of tsetse fly control should be specific to particular epidemic areas. Future studies should include laboratory experiments that use local colonies of tsetse flies, local strains of trypanosomes and local S. glossinidius under controlled environmental conditions to tease out the factors that affect vector competence and the relative influence of external environmental factors on the dynamics of these interactions.