The physiological stress response to amputation in the eleven-armed sea star (Coscinasterias muricata) : a thesis presented in partial fulfilment of the requirements for the degree of Masters of Science in Zoology, Massey University, Palmerston North, New Zealand

The eleven-armed sea star, Coscinasterias muricata, is subject to human-induced stressors, such as invasive fishing activities, that can cause limb loss (amputation), and heavy metal discharge into their habitat. The well-being and survival of a keystone predator such as C. muricata has important ecological implications as their presence influences community structure in the marine environment. Understanding the stress physiology of an animal can provide insight into their overall health and survival. While the stress physiology of northern asteroid species (such as Asterias rubens) has been well documented, this has not been well studied with C. muricata. In this thesis, I was able to identify time-dependent changes in two physiological parameters (total coelomocyte count and dopamine levels in the coelomic fluid) in C. muricata subjected to amputation. There was a synchronous increase in both of these parameters 24 hours post amputation. Dopamine in the coelomic fluid was measured by using high performance liquid chromatography (HPLC). I adapted a pre-existing method involving pre-column derivatisation and fluorescent detection, which was initially developed for the detection of dopamine in porcine muscle. However, this method requires further development as it could not detect dopamine to the same sensitivity as previously reported HPLC methods using electrochemical detection. Lastly, the initial attempts at developing an in vitro cytotoxicity bioassay using C. muricata coelomocytes is described in detail. The initial aim of this experiment was to understand the effect of heavy metals on cellular parameters. However the experiment was hampered by unusually low cell counts in this species, which has not been previously reported. The knowledge gleaned from this study may provide the groundwork for future studies that use C. muricata coelomocytes for cytotoxicity testing or as a biomarker

Organizational Learning from Extreme Performance Experience: The Impact of Success and Recovery Experience

This paper argues that two different types of a firm’s own extreme performance experiences—success and recovery—and their interactions can generate survival-enhancing learning. Although these types of experience often represent valuable sources of useful learning, several important learning challenges arise when a firm has extremely limited prior experience of the same type. Thus, we theorize that a certain threshold of a given type of experience is required before each type of experience becomes valuable, with low levels of experience harming the organization. Furthermore, we propose that success and recovery experience will interact to enhance each other’s value. These conditions can help overcome learning challenges such as superstitious learning or learning from small samples. We investigate our ideas using a sample of the U.S. commercial banks founded between 1984 and 1998. Our results indicate that both success and recovery experience of a firm generate survival-enhancing learning, but only after a certain level of experience is reached. Furthermore, success and recovery experience enhance each other’s learning value, consistent with the theories that emphasize the importance of richer and contrasting experience in providing useful knowledge. Our framework advances organizational learning theory by presenting a contingent model of the impact of success and recovery experience and their interaction

Highly diverse nirK genes comprise two major clades that harbour ammonium-producing denitrifiers

Background: Copper dependent nitrite reductase, NirK, catalyses the key step in denitrification, i.e. nitrite reduction to nitric oxide. Distinct structural NirK classes and phylogenetic clades of NirK-type denitrifiers have previously been observed based on a limited set of NirK sequences, however, their environmental distribution or ecological strategies are currently unknown. In addition, environmental nirK-type denitrifiers are currently underestimated in PCR-dependent surveys due to primer coverage limitations that can be attributed to their broad taxonomic diversity and enormous nirK sequence divergence. Therefore, we revisited reported analyses on partial NirK sequences using a taxonomically diverse, full-length NirK sequence dataset. Results: Division of NirK sequences into two phylogenetically distinct clades was confirmed, with Clade I mainly comprising Alphaproteobacteria (plus some Gamma- and Betaproteobacteria) and Clade II harbouring more diverse taxonomic groups like Archaea, Bacteroidetes, Chloroflexi, Gemmatimonadetes, Nitrospirae, Firmicutes, Actinobacteria, Planctomycetes and Proteobacteria (mainly Beta and Gamma). Failure of currently available primer sets to target diverse NirK-type denitrifiers in environmental surveys could be attributed to mismatches over the whole length of the primer binding regions including the 3' site, with Clade II sequences containing higher sequence divergence than Clade I sequences. Simultaneous presence of both the denitrification and DNRA pathway could be observed in 67 % of all NirK-type denitrifiers. Conclusion: The previously reported division of NirK into two distinct phylogenetic clades was confirmed using a taxonomically diverse set of full-length NirK sequences. Enormous sequence divergence of nirK gene sequences, probably due to variable nirK evolutionary trajectories, will remain an issue for covering diverse NirK-type denitrifiers in amplicon-based environmental surveys. The potential of a single organism to partition nitrate to either denitrification or dissimilatory nitrate reduction to ammonium appeared to be more widespread than originally anticipated as more than half of all NirK-type denitrifiers were shown to contain both pathways in their genome

Cross-Generational Relationships in Kenya: Couples' Motivations, Risk Perception for STIs/HIV and Condom Use

Objectives: To understand women's and men's motivations for entering into cross-generational relationships and to examine how their risk perception for sexually transmitted infections (STIs) and human immunodeficiency virus (HIV) affects sexual decision-making and condom use.Methods: A total of eight focus groups were conducted with women aged 15 -- 19 and 28 indepth interviews were carried out with men aged 30 years and older in Nairobi, Mombasa, Kisumu, and Meru. Participants discussed motivations for entering into non-marital, crossgenerational relationships, perceived risks, relationship dynamics, and circumstances under which older men and younger women meet. Data analysis highlighted common and divergent themes on cross-generational relationships and the risks associated with them. Results: According to study participants, Kenyan men who pursue younger women do not fit a "sugar daddy" stereotype; rather they come from a variety of social and professional backgrounds. Young women actively seek partners who are willing to spend money on them whereas men look for partners who are well mannered, need money and have certain physical attributes. Women's primary incentive for engaging in cross-generational relationships is financial and material gain while men seek younger partners for sexual gratification. Pressure from peers to fit in and some family members to secure financial assistance from older partners can compel women to engage in cross-generational relationships. Although some peer groups support and encourage such relationships, other groups, especially wives, same-aged boyfriends and parents, disapprove of them. As a result, cross-generational couples are often preoccupied by the threat of discovery. Risk perception for STIs/HIV is low and couples rarely use condoms.Conclusions: Most cross-generational couples underestimate their risk for infection from STIs/ HIV. Young women believe that older men are low-risk partners because they are less likely to be promiscuous and more likely to remain faithful to younger partners and wives. Men believe that young partners are innocent and sexually inexperienced. Material gain, emotional factors, sexual gratification, and recognition from peers override the risk for STIs and HIV infection. Condom use is low and young women's ability to negotiate use is compromised by age disparities and economic dependence. Study findings suggest several programmatic strategies for targeting young women and older men. Behavior change communication campaigns should educate women and men about the increased risk of STIs/HIV associated with cross-generational relationships. Programs should also promote safer sexual practices, such as consistent condom use, within relationships. Campaigns could employ positive role models to encourage young women to seek safer alternatives to cross-generational relationships and decrease peer pressure among men to pursue such relationships. Long-term interventions include improving young women's access to educational and career opportunities, and working with communities to determine the best approach for changing social norms and the acceptability of cross-generational relationships

Dissimilatory nitrogen reduction in intertidal sediments of a temperate estuary: small scale heterogeneity and novel nitrate-to-ammonium reducers

The estuarine nitrogen cycle can be substantially altered due to anthropogenic activities resulting in increased amounts of inorganic nitrogen (mainly nitrate). In the past, denitrification was considered to be the main ecosystem process removing reactive nitrogen from the estuarine ecosystem. However, recent reports on the contribution of dissimilatory nitrate reduction to ammonium (DNRA) to nitrogen removal in these systems indicated a similar or higher importance, although the ratio between both processes remains ambiguous. Compared to denitrification, DNRA has been underexplored for the last decades and the key organisms carrying out the process in marine environments are largely unknown. Hence, as a first step to better understand the interplay between denitrification, DNRA and reduction of nitrate to nitrite in estuarine sediments, nitrogen reduction potentials were determined in sediments of the Paulina polder mudflat (Westerschelde estuary). We observed high variability in dominant nitrogen removing processes over a short distance (1.6m) with nitrous oxide, ammonium and nitrite production rates differing significantly between all sampling sites. Denitrification occurred at all sites, DNRA was either the dominant process (two out of five sites) or absent, while nitrate reduction to nitrite was observed in most sites but never dominant. In addition, novel nitrate-to-ammonium reducers assigned to Thalassospira, Celenbacter, and Halomonas, for which DNRA was thus far unreported, were isolated, with DNRA phenotype reconfirmed through nrfA gene amplification. This study demonstrates high small scale heterogeneity among dissimilatory nitrate reduction processes in estuarine sediments and provides novel marine DNRA organisms that represent valuable alternatives to the current model organisms

Injecting equipment schemes for injecting drug users : qualitative evidence review

This review of the qualitative literature about needle and syringe programmes (NSPs) for injecting drug users (IDUs) complements the review of effectiveness and cost-effectiveness. It aims to provide a more situated narrative perspective on the overall guidance questions