Induction imposex of gastropod snails by organotins has been reported worldwide. However, the relationship between imposex and detoxification capability is not well studied in molluscs. In the present study, the relationship between the mixed function oxidase (MFO) system and the degree of imposex in drills Thais spp. was investigated. Thais clavigera, T. rufotincta and T. sp. were collected from the west coast of Taiwan. The degree of imposex was determined by percent imposex, relative penis size (RPS) and vas defenes sequence (VDS). Enzymes of cytochrome P450, NADPH-cytochrome c reductase, EROD¡]7-ethoxyresorufin-O-deethylation¡^ and cytochrome P420 (an inactive form of cytochrome P450) in the MFO system were examined. In the three Thais species, the degrees of imposex expressed as percent imposex, RPS and VDS were 71-100%, 8.8-62.5% and 0.7-2.5, respectively. Contents of cytochrome P450 and cytochrome P420 were 0.043-0.097 nmol/mg protein and 0.129-0.296 nmol/mg protein, respectively. The activity of NADPH-cytochrome c reductase was in the range of 1.52-6.73 nmol/min/mg protein. The activity of EROD was not detected. Negative trends between the degree of imposex and the contents of cytochrome P450 and cytochrome P420 were found in all the Thais species. And, a positive trend betweed the degree of imposex and the activity of NADPH-cytochrome c reductase was also observed. Based on the results, it is suggested that the induction of imposex was possibly due to the imbalance of steroid hormone metabolism caused by the inhibition of cytochrome P450 activity.

<p> The relationship between the mixed-function oxidase (MFO) system and resistance of Drosophila melanoqaster to phosmet (ImidanR) an organophosphorus insecticide has been studied. The MFO activity was assayed by 7-ethoxycoumarin-O-deethylase (7-ECD) activity and resistance levels were determined by either adult LC- 50 or percent adult survival at 150 uM of Imidan. Two groups of isofemale lines sampled from Vineland, Ontario and a laboratory selected population were used to study variability of the MFO system and its relationship to variability in resistance. </p> <p> A significant positive correlation was found between 7-ECD specific activity and an antigenic determinant assayed by western blotting. The antiserum used to detect this determinant was prepared against a cytochrome P-450-enriched fraction from a malathion-resistant Drosophila melanoqaster strain by J. Pursey (1989). The antigenic determinant was contained on polypeptide P2, believed to be a cytochrome P-450 by its molecular weight and heme content. </p> <p> Laboratory selection on Imidan resulted in over 2 .1-fold increase in resistance. Two MFO activity groups were identified among isofemale lines established from nature. A siqnificant positive correlation was found between 7-ECD specific activity and resistance to Imidan among the Isofemale lines. The minimum number of genes controlling the difference in 7-ECD specific activity between two isofemale lines was estimated to be about 1. </p> <p> It was concluded that this natural Drosophila melanoqaster population has a major or few .genes on chromosome 3 affecting MFO activity and resistance but as well other factors on chromosomes 1 and 2 also contribute to variability in resistance. </p> / Thesis / Master of Science (MSc)

There has been a huge surge in the Internet of Things (IoT) applications in recent years. The sensor nodes in the IoT network generate data continuously that directly affects the longevity of the network. Even though the potential of IoT applications are immense, there are numerous challenges like security, privacy, load balancing, storage, heterogeneity of devices, and energy optimization that have to be addressed. Of those, the energy utilization of the network is of importance and has to be optimized. Several factors like residual energy, temperature, the load of Cluster Head (CH), number of alive nodes, and cost function affect the energy consumption of sensor nodes. In this paper, a hybrid Whale Optimization Algorithm-Moth Flame Optimization (MFO) is designed to select optimal CH, which in turn optimizes the aforementioned factors. The performance of the proposed work is then evaluated with existing algorithms with respect to the energy-specific factors. The results obtained prove that the proposed method outperforms existing approaches.