Artificial diet bioassays were carried out to investigate the impact of GNA and Con A upon the development of L. oleracea larvae. GNA, at 2 % of total dietary protein, exerted a significantly detrimental effect upon larval development, growth and consumption, with little effect upon survival. Con A was shown to be the more toxic of the 2 lectins. When tested at concentrations of 2.0 %, 0.2 % and 0.02 %, Con A caused a significant decrease in survival and larval development, and caused greater reductions in larval growth and consumption compared to GNA. The potential for GNA and Con A to exert insecticidal effects via binding to the brush border membrane (BBM) and peritrophic membrane (PM) of L. oleracea larvae was investigated. Con A, which specifically binds a-D-mannopyranoside and a-D- glucopyranoside residues, was shown to bind in vitro to the majority of BBM and PM proteins. In contrast GNA, which exhibits strict specificity for a(l,3) and a(l,6)-linked D-mannose residues, bound to only 5 BBMV and 2 PM proteins. In agreement, higher levels of Con A, compared to GNA, were shown to accumulate in larval gut tissue after feeding the proteins in vivo. Despite this both lectins were shown to have a similar ability to disrupt the digestive capacity of the larval midgut. GNA and Con A stimulated similar short term elevations in BBM enzyme and soluble trypsin activities and a long-term reduction in a-glucosidase activity. Increases in levels of trypsin activity in faecal material collected from lectin-fed larvae suggested that the proteins may act by disrupting mechanisms of enzyme recycling. Aminopeptidase, an abundant and avidly binding BBM protein (120 kDa), was identified as a major Con A binding species in L. oleracea. A 98 kDa GNA-binding BBM protein was purified and amino acid sequence data was obtained from digest polypeptides allowing oligonucleotide primers to be designed. Subsequent attempts to amplify (by PCR and RT-PCR) fragments containing coding sequence corresponding to the 98 kDa protein were unsuccessful. This was attributed to oligonucleotide degeneracy together with the low abundance and relatively large size of the protein. The potential for GNA and Con A to exert systemic effects upon I. oleracea was demonstrated by the detection of both lectins in the haemolymph of larvae exposed to experimental diets. GNA was detected in haemolymph of larvae exposed to experimental diet for just 2 hours. In contrast, no Con A was detectable in haemolymph extracted from larvae fed for 24 hours, although it was present in the haemolymph after 5 days of exposure to the diet. That GNA and Con A may act directly upon organs other than the insect gut was indicated by the detection of lectins in vivo in malpighian tubule and fat body tissue extracts. A significant reduction in haemocyte abundance in haemolymph samples extracted from lectin-fed larvae suggested that both GNA and Con A may also act by disrupting the immune system of L. oleracea.

Intracellular microelectrodes have been used in conjunction with ion substitution, and agonists and inhibitors of known transport processes to investigate the mechanisms whereby ions cross the basal and apical cell membranes of the Malpighian tubules of Locusta. Values for basal, apical and transepithelial potentials in 'Normal' saline were -71.6 ± 0.3 mV, -82.6 ± 0.8 mV and +5.7 ± 1.0 mV (lumen positive) respectively. Ion substitution experiments, involving Na(^+),K(^+) and C1(^-) in the bathing media, indicated that the basal membrane was more permeable to K(^+) than Na(^+) and C1(^-). Two different electrical responses to high [K(^+)](_o) saline (the Type A and Type B response) were noted and these probably reflect distinct physiological states of basal membrane permeability. Experiments with ouabain and vanadate suggested that whilst Na(^+)+K(^+) ATPase activity, which has been demonstrated in microsomal preparations, was not significantly electrogenic, asymmetric ionic distribution across the basal membrane was partly maintained by thisenzyme Furthermore, 3-H ouabain-binding studies indicated that Na(^+)+K(^+) exchange 'pump' turnover was adequate to account for substantial entry and Na^ exit across the basal membrane. The electrochemicalgradient across the apical membrane suggests that exit from the cell must involve an active process with CI following passively. Data from ion substitution experiments and treatment with furosemide and bumetanide suggest that CI entry across the basalmembrane may be via cotransport with Na^ and/or K^. However, the+ —differential electrical responses to Na(^+) free and C1(^-) free salines question the role of Na(^+) in this process. The effects of c AMP, Ca(^2+) substitution and various inhibitors on basal and apical membrane potentials, taken in conjunction with the results referred to above, are discussed and a hypothetical model proposed whereby changes in intracellular Ca(^2+) and c AMP effect control of ion movements across the two cell surfaces.

Many species of farmland birds have shown huge declines in numbers and range since the 1970s due to agricultural intensification, and these declines have been worst amongst granivorous species. Recent studies have suggested that low abundance of invertebrate chick food may have been important in driving the declines of a number of granivorous species, however causation has still only been proved for the Grey Partridge, whose decline has been attributed to low chick survival due to the indirect effects of herbicides reducing invertebrate abundance. We investigated invertebrate declines and how they may have affected farmland bird populations in a number of ways. There is little long-term data on abundance of farmland invertebrates. Thus we first looked at how representative data from a long-running suction trap was of invertebrate abundance on local farmland. Suction trap catches reflected abundance of aerial invertebrates on local farmland, and also to abundance of epigeal invertebrates in many cases, particularly abundances in predominant crop types. Secondly, we looked at spatial and temporal distribution of invertebrates on farmland in order to make recommendations about how to increase invertebrate availability to farmland bird populations. Field margins were by far the most invertebrate rich habitats sampled. Most differences in invertebrate abundance between different crop types were found early in the season, at this time spring barley and spring oilseed rape had very low abundances. Winter wheat had relatively high invertebrate abundance compared to spring barley at this time. Winter oilseed rape and set-aside had relatively high abundances of the crop types sampled. We investigated how low invertebrate abundance may have affected populations of granivorous passerines by looking for evidence of reproductive trade-offs in a population of Tree Sparrows, and by supplementary feeding experiments with Tree Sparrow and Yellowhammer chicks. There was no evidence for reproductive trade-offs within years, conversely an effect of individual quality was found. There was some evidence of reproductive trade-offs between years. Supplementary feeding increased the mass of Tree Sparrow first broods early in May but not later in May, and also of chicks with yearling parents, who had a lower provisioning rate. Chicks fledged early in May had a lower survival rate to the following year than chicks fledged later, supplementary feeding and parental age had no effect on chick survival. Supplementary feeding a parent's first brood had no effect on their later reproductive output that season, or on their survival to the next breeding season. Supplementary feeding Yellowhammer chicks early season increased their mass, but had no effect later in the season. This complies with results from a previous study of Yellowhammers in southern England, which showed that a higher proportion of chicks fledge late in the season. Further analysis of this data showed that this was because chicks were more likely to starve early in the season, and also that chick mass was lower early season, even when just looking at chicks which went on to fledge. Thus, it would appear that low invertebrate abundance was affecting the granivorous passerines looked at most in the early season, and through chick mass and survival. Measures to increase invertebrate abundance at this time would be beneficial to populations of granivorous passerines.

The in vitro rate and cationic composition of the fluid secreted by the Malpighian tubules of the African migratory locust, Locusta migratoria migratoroides L, was investigated in this study. The concentrations of the elements Na, K, P, S, CI, Mg and Ca within Locusta Malpighian tubule type 1 cells, and the surrounding basement membrane, were quantified. Inhibitors and stimulators of fluid production were used to perturb the normal secretory state of the tubule cells. The rate of fluid secretion under control conditions was between 1.82 and 1.33. nl min(^-1) The fluid [K(^+)] was approximately 126mM, and [Na(^+)] 51 mM. The basement membrane was characterised by high [Na] and [CI] whilst a gradient of [K](_i) was observed. [K](_i) rose from approximately 193 mmol Kg(^-1) d.w. at the basal infoldings to 481 mmol Kg(^-1) d.w. at the apical microvillar border. The central cytoplasmic [K](_i) was 348 mmol Kg(^-1) d.w., estimated as 116mM. [Na](_i) and [Cl](_i) were generally lower, being 57mM and 29mM respectively in the central cytoplasm. Only K assumed a concentration gradient. Intracellular mass dense concretions were observed. Three types were present, the first rich in P and Ca, the second, rich in S, Na and K, and the third, rich in Mg, K and Na. The fluid production inhibitors furosemide (1mM) and bafilomycin A(_1) (1µM) raised the [N(^+)] in the secreted fluid, and altered [K](_i), [Na](_i) and [CI](_i). Furosemide lowered [K](_i) but increased [Na](_i) and [Cl](_i). Bafilomycin lowered [K(^+)] in the secreted fluid, though [K](_i) increased. Both inhibitors abolished the [K](_i) gradient. Replacing K(^+) with Rb(^+) in the bathing saline slowed fluid secretion and lowered [K](_i) and [Cl](_i), though a gradient of [K](_i) was retained. Rb adopted an intracellular gradient which mirrored that of K. Rate of secretion data suggests Rb enters the cell basolaterally primarily via the Na(^+)-K(^+)-ATPase. The fluid secretion stimulator cAMP (1mM) lowered [K](_i), and raised [Na](_i) and [Cl](_i), but corpora cardiaca extract left these elements' concentrations largely unchanged. Stimulation with both corpora cardiaca extract and cAMP maintained the [K](_i) gradient. These stimulators changed the content and number of mass dense concretions present, in manner which suggested that these structures were important in ion transport. These findings support the current model of ionic transport in these cells, including the basolateral presence of an Na(^+)-K(^+)-2Cr cotransporter, and an apical proton-pumping V-type ATPase / K(^+)/nH(^+) antiport complex.

Thesis (Ph. D.)--University of Hawaii at Manoa, 1996. / Includes bibliographical references (leaves 147-152). / Microfiche. / xx, 297 leaves, bound ill. 29 cm

Typescript / 261 leaves : ill. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Zoology, 1966

Thesis (Ph. D.)--University of Adelaide, 1982. / Includes bibliographical references (leaves A19-A23).

Thesis (Ph.D.) -- Flinders University, School of Medicine, Dept. of Immunology, Allergy and Arthritis. / Typescript (photocopy). Includes bibliographical references. Also available online.

Thesis (Ph.D) -- University of Adelaide, Dept. of Molecular Biosciences, 2002. / Bibliography: leaves 363-381.

Thesis(M.S.)--Auburn University, 2005. / Abstract. Vita. Includes bibliographic references (p.54-61).