Thesis (Master, Biology) -- Queen's University, 2009-09-24 14:35:26.369 / A major challenge in neurobiology is to understand the control of behaviour at the molecular level. Neuropeptides and their receptors offer promising candidates for the regulation of various behaviours and changes in physiology. Neuropeptides act as important signaling molecules in the central and peripheral nervous system; they are involved in development, reproduction and metabolism. Most of the neuropeptides and hormone protein receptors belong to the large super family of G-protein coupled receptors. NPR-14 is one of the GPCRs in C. elegans, similar in sequence to the mammalian orexin and cholecystokinin receptors which have a primary involvement in food stimulation, locomotion and local search behaviour on food, egg laying and stimulation of wakefulness and energy expenditure. In this study we determined the expression pattern of npr-14 and characterized the behavioural phenotypes associated with NPR-14 receptor in C. elegans included. We showed that the NPR-14 receptor exhibits the regulation of roaming behaviour and fat in the presence of food in a manner resembling that of a similar receptor NPR-9. Additionally, the NPR-14 receptor is involved in the control of some other behaviours such as: egg-laying, crawling and thrashing but not in the regulation of mechanosensation responses and defecation. In our neuronal expression studies the npr-14 promoter fused to reporter mCherry was found to be expressed in ASH or ASI sensory neurons and DD and VD motor neurons and also VC motor neurons that extend to the vulva region to modulate reproduction and egg-laying. Moreover, based on our studies of NLP-5 and NLP-6 neuropeptides we speculated that these neuropeptides and especially NLP-6 could be the putative ligand for NPR-14 receptor. We also compared the phenotypes associated with the receptor NPR-15. NPR-15 is more similar to the Drosophila tachykinin receptor which has no known function in Drosophila. NPR-15 is unrelated in sequence to NPR-9 and NPR-14 and was thus used as a control. Indeed, we were able to show that NPR-15 appears to regulate responses to posterior mechanical stimulation and rhythmic defecation behaviour in C. elegans. These are phenotypes not associated with NPR-9 or NPR-14. / Master

Myokinins are invertebrate neuropeptides with myotropic and diuretic activity. The lymnokinin receptor from the snail Lymnaea stagnalis was the only previously identified myokinin receptor. A cDNA encoding a neuropeptide receptor was cloned from the southern cattle tick, Boophilus microplus. The deduced amino acid sequence was 40 % identical to the lymnokinin receptor. The receptor transcript is present in all tick life stages as determined by semiquantitative RT-PCR. When expressed in mammalian CHO-K1 cells, myokinins at nanomolar concentrations induced increases in intracellular calcium as measured by fluorescent cytometry. The rank order of potency for peptides tested was FFFSWS-NH2≥FFFSWG-NH2≥FFSWG-NH2>FYSWG-NH2>muscakinin>lymnokinin>>APTGFFGVR-NH2. The receptor coupled to a pertussis toxin insensitive G protein. Absence of extracellular calcium did not inhibit the calcium response, indicating the release of Ca2+ from intracellular stores. Receptor transcript was detected by RT-PCR in the dissected synganglia, ovaries, salivary glands, guts and Malpighian tubules of partially engorged adult female ticks. It is concluded that the B. microplus receptor is the first myokinin receptor cloned from an arthropod, and the first neuropeptide receptor known from the Acari. The presence of this receptor transcript in multiple tissues and all life stages suggests a multifunctional role in ticks.

Myokinins are invertebrate neuropeptides with myotropic and diuretic activity. The lymnokinin receptor from the snail Lymnaea stagnalis was the only previously identified myokinin receptor. A cDNA encoding a neuropeptide receptor was cloned from the southern cattle tick, Boophilus microplus. The deduced amino acid sequence was 40 % identical to the lymnokinin receptor. The receptor transcript is present in all tick life stages as determined by semiquantitative RT-PCR. When expressed in mammalian CHO-K1 cells, myokinins at nanomolar concentrations induced increases in intracellular calcium as measured by fluorescent cytometry. The rank order of potency for peptides tested was FFFSWS-NH2≥FFFSWG-NH2≥FFSWG-NH2>FYSWG-NH2>muscakinin>lymnokinin>>APTGFFGVR-NH2. The receptor coupled to a pertussis toxin insensitive G protein. Absence of extracellular calcium did not inhibit the calcium response, indicating the release of Ca2+ from intracellular stores. Receptor transcript was detected by RT-PCR in the dissected synganglia, ovaries, salivary glands, guts and Malpighian tubules of partially engorged adult female ticks. It is concluded that the B. microplus receptor is the first myokinin receptor cloned from an arthropod, and the first neuropeptide receptor known from the Acari. The presence of this receptor transcript in multiple tissues and all life stages suggests a multifunctional role in ticks.

Diss. (sammanfattning) Stockholm : Karol. inst., 2005. / Härtill 8 uppsatser.

Despite a high proportion of the population experiencing traumatic events within their lifetime, the number of individuals who go on to develop posttraumatic stress disorder (PTSD) is comparatively small; herein highlighting the importance of individual differences in imparting risk and resilience towards the development and maintenance of PTSD. Existing literature illustrates that biological and ecological factors are important in predicting PTSD development, with pathological vulnerabilities excepting their effects at pre- peri- and post trauma stages. Whilst cognitive and emotion based models of PTSD account for the role of a minority of known pre-trauma risk factors, individual differences in peri- and post trauma processes are held as critical to the development of PTSD. The broad range of risk factors implicated in the empirical literature, and necessity of traumatic exposure to PTSD, implicates the utility of a diathesis-stress conceptualisation of PTSD development. The current thesis employed an analogue VR-trauma paradigm to investigate the respective importance of vulnerability factors at each stage, in the prediction of analogue PTSD symptoms (memory problems, startle responses, re-exposure fear habituation), whilst measuring affective and electrophysiological concomitance. Findings supported the importance of peri-traumatic responses in the prediction of PTSD, where present, showing increased predictive capacities over pre- and post-trauma factors. Biological and ecological factors also illustrated important predictive associations, with genetic SNPs implicated in reflex startle and cardiac responses towards intrusive memories. Moreover, peri-traumatic HR decelerations and accelerations mediated the association between pre-trauma factors and cued recall inaccuracy and intrusion severity respectively. Results support existing cognitive and emotional models in their emphasis on peri-traumatic processes but suggest the added utility of a diathesis stress conceptualisation of the development of PTSD, in highlighting the importance of pre-trauma biological and ecological risk and resilience factors.