The structure of insect cuticle has been reviewed briefly and an account given of the processes by which hardening (tanning) occurs after the moult. The sclerotin wall of the cockroach ootheca is formed by the intermingling of the accretions of the left and right colleterial glands. This system, because of its comparative convenience, is studied with a view to shedding light on the sclerotin formation in the cuticle. With reference to their role in sclerotization, the properties of insect blood and cuticle oxidases are reviewed and comparisons made with the animal and plant enzyme grouse they most resemble - tyrosinases and laccases. The function of copper in these oxidases is discussed. A method was developed for determining the protein concentrations, in the presence of phenolic compounds, of the diluted secretion from the left colleterial glands of Periplaneta. This involved digestion (6N-HCl, 6 hours) of the protein followed by estimation with ninhydrin of the total amino acids in the hydrolysate. Investigation of the properties of the copper-containing (0.1-0.2%) phenoloxidase of the left colleterial gland showed that the enzyme is specific towards diphenols (especially ortho-) and is therefore not a tyrosinase. In the majority of its properties the oxidase resembles a laccase, although it is more specific than the plant enzymes. Phenolic substrates bearing an amino group in the side chain are not active - a property which clearly distinguishes the cockroach phenoloxidase from the blood tyrosinase of insects. Towards certain substrates (catechol, hydroquinone, homoprotocatechuic acid) activity is unexpectedly stable to boiling while towards others (protocatechuic acid and its aldehyde) it is destroyed. Possibly non-enzymic, as well as enzymic, activity exists. The effect of some substances (detergents, dopa, catechol, tyrosine, ascorbic acid) on the activity of the phenoloxidase towards protocatechuic acid (3 μmoles) is measured. The stimulation caused by ascorbic acid (0.15 andmu;moles) is related to the possible requirement of cuprous ions for enzyme activity. The phenoloxidase activity which resides in a articulate fraction of the gland secretion, is (unlike other copper oxidases) not inhibited by metal chelating agents, such as phenylthiourea, diethyldithiocarbamate, ethylenediaminetetracetic acid and 4-chlororesorcinol, in the presence of sodium phosphate buffer (0.1M -, pH 6.8). Cyanide and borate are effective inhibitors, however. Varied attempts to purify the participate enzyme and thus to fractionate it from the prosclerotin or structural protein met with little success. The specific activities (Q_O₂'s) of the supernatants obtained after high speed centrifugation (100,000-182,000 andtimes; g) are approximately five to ten times higher than those (3.93±1.15(10)) of untreated enzyme preparations. An examination of this "purification" led to the conclusion that the enzyme activity appeared to be rather dependent on the state of aggregation of the protein particles. Further evidence of this effect was inferred from the stimulating action of anionic (deoxycholate) and neutral ("Tween") detergents (added prior to buffering) upon phenoloxidase activity. Prior to the institution, as a regular procedure, of dialysis (0.01M-NaCl) of the colleterial gland secretion (to remove endogenous phenolic compounds), a long induction period (ca. 20-60 mins.) before commencement of oxygen uptake by enzyme and substrate was frequently observed. This long period was minimized by the addition of right gland homogenate or ascorbic acid. In section II, the phenolic compounds found in insect cuticle and in cockroach colleterial glands were examined with reference to their biosynthesis and to their role in sclerotization. Protocatechuic acid, its 4-o-β-D-glucoside and p-tyrosine were identified (chromatographically and spectrophotometrically) in homogenates of left colleterial gland. After aerobic incubation (37°C) of these homogenates substances strongly resembling catechol and tyramine were separated by paper chromatography and identified by their u.v. spectral properties after elution. Protocatechuic acid and p-tyrosine, when added (with and without right gland preparation) to homogenates of left glands, increased the production of catechol and tyramine respectively. From densitometric measurements of ferric chloride/ferricyanide sprayed paper chromatograms the aerobic conversion by left gland homogenate of p-tyrosine (1 andmu;mole added) into tyramine (0.62 andmu;moles) was demonstrated, The amine was also separated by absorption on Amberlite-IRC (H⁺). The decarboxylase systems responsible for catechol and tyramine production, whether induced or not, were heat labile. There is some manometric evidence that the former enzyme is located in right gland cells while the latter is present in the larger gland tissue. These findings are made uncertain by the retardation of the reactions in presence of inorganic buffers (and an anaerobic atmosphere) and by extraneous gas evolution particularly during incubation of mixed homogenates of both glands. In the light of some evidence, the possibility that tyramine might be enzymically oxidized by homogenates of left gland is weighed. The significance of such a reaction, together with the decarboxylation of p-tyrosine and protocatechuic acid, is discussed with regard to the biosynthesis of tanning quinones from the p-tyrosine of the insect blood.

Thesis (M.S.)--Virginia Polytechnic Institute and State University. / Vita. Abstract. Includes bibliographical references (leaves 55-60). Also available via the Internet.

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Strains of the German cockroach resistant to lindane, chlordane, and DDT were compared with a normal strain as to incubation period of eggs, developmental period of nymphs, and longevity of adults. The resistant strains were more heterogeneous than the normal, with the exceptions of the chlordane-resistant males and females of the nymphal developmental study and all the resistant males in the longevity study. The incubation period of the DDT-resistant strain was shorter than that of the normal and the other two resistant strains. The DDT- and lindane-resistant strains had longer nymphal developmental periods than the other two strains. The resistant females lived significantly longer than the normal females. The sex ratio approached unity in all strains. Correlation of resistance with differences found in this study gave variable results. The field-originated strain (chlordane-resistant) was similar to the normal strain in average length of incubation and nymphal developmental periods, but similar to the other resistant strains in longevity. On the other hand, rather consistent differences were found between the normal strain and those with laboratory-induced resistance (DDT and lindane strains). / Master of Science

Changes in metabolic substrate utilization patterns resulting from exposure to varying humidity and dietary regimens were examined in the adult, male American cockroach. A series of respirometric experiments were conducted to monitor changes in respiratory quotient (RQ), oxygen quotient (QO₂), food and water consumption and body weight. Also, a series of radiolabel experiments, utilizing injected ¹⁴C-glucose and ¹⁴C-palmitic acid, were conducted to determine radiolabel content (after exposure to varying humidity and dietary regimens) in whole body, feces, ¹⁴CO₂, hemolymph, fat body tissue and cuticle. The results of these two series of experiments were compared to determine the overall effects of humidity and diet on catabolic substrate utilization pattern changes in the American cockroach. In these experiments, variation in dietary regimens appeared to play a more significant role than humidity variations with respect to significant differences observed in insect RQ, QO₂, body weight and radiolabel incorporation in whole body, ¹⁴CO₂ , hemolymph, and fat body tissue. However, humidity significantly affected radiolabel incorporation in fat body tissue in the glucose experiments and ¹⁴CO₂ in the palmitic acid experiments. RQ and QO₂ data from the respirometric experiments and ¹⁴CO₂ data from the radiolabel experiments suggested that cockroaches deprived of food, but provided water to drink, change their metabolic substrate utilization pattern from initial catabolic substrates such as carbohydrates to lipid-based substrates. Also, cockroaches deprived of either water (FO) or food and water (OO) appeared to change metabolic substrate utilization patterns toward carbohydrates, but the final carbohydrate metabolic substrates are still unknown. Cockroaches provided water, but no food, showed a change from initial RQ values (low humidity OW = 0.92 and medium humidity OW = 0.86) to terminal RQ values (low humidity OW = 0.71 and medium humidity OW = 0.68) representative of lipid-based substrate metabolism. There was also an unexplained decrease in QO₂ (initial low humidity OW = 0.45 ul/mg/hr and terminal low humidity OW = 0.28 ul/mg/hr; initial medium humidity OW = 0.35 ul/mg/hr and terminal medium humidity OW = 0. 30 ul/mg/hr). Also, cockroaches deprived of water (FO) or food and water (OO) showed an overall experimental rise in RQ values (initial low humidity FO = 0.87; and terminal low humidity FO = 0.87; initial medium humidity FO = 0.82 and terminal medium humidity FO = 0.85: initial low humidity OO = 0.79 and terminal low humidity OO = 0.88; initial medium humidity OO = 0. 75 and terminal medium humidity OO = 0.87). In addition, these same insects showed an overall experimental increase in QO₂ (initial low humidity FO = 0. 34 ul/mg/hr and terminal low humidity FO = 0.43 ul/mg/hr; initial medium humidity FO = 0.45 ul/mg/hr and terminal medium humidity FO = 0.49 ul/mg/hr: initial low humidity OO = 0.37 ul/mg/hr and terminal low humidity OO = 0.53 ul/mg/hr; initial medium humidity OO = 0.32 ul/mg/hr and terminal medium humidity OO = 0.45 ul/mg/hr), and in the radiolabelled glucose study OO insects showed an almost complete cessation of ¹⁴CO₂ release at 2 days (d). Terminal body weights differed significantly among cockroaches provided with both food and water (controls = FW), only water (OW), only food (FO) and no food or water (OO). Insects deprived of either water (FO) or food and water (OO) had significantly lower terminal body weights than those insects provided either water or food and water. Whole body water content increased and dry weight decreased in insects provided only water to drink. / Ph. D.

Physiological parameters involved in formed urate pellet excretion by the wood cockroach, <i>Parcoblatta fulvescens</i> were investigated. Uric acid excretion by last instar juvenile <i>P. fulvescens</i> was studied first. Food consumption, urate and non-urate pellet excretion patterns show a skewed distribution with peak feeding occurring on day six and peak voiding of both pellet types on day seven of a 17.0 ± 2.0 (SD) day ecdysial cycle. The amount of urates excreted is determined by the level of dietary protein (p<0.0001) and is linearly related to protein consumption. Selective feeding on protein, carbohydrate and cellulose diets by reproductive female <i>P. fulvescens</i> was investigated. Separate consumption patterns exist for each diet. These females did not excrete uric acid. Urate pellet consumption by reproductive female <i>P. fulvescens</i> was examined in relation to dietary protein and carbohydrate. Urate pellet consumption increases with decreasing protein and increasing carbohydrate levels. Females that consume urate pellets do not excrete uric acid. These results suggest that urate-containing pellets serve to transfer nitrogen reserves among individuals. Urate spherules were enzymatically and histochemically identified in the middle and proximal regions of the Malpighian tubules of <i>P. fulvescens</i>, <i>Shawella couloniana</i> and <i>Symploce hospes</i>. These spherules are discharged into the hindgut in sufficient quantities to obscure the presence of food residues. The significance of formed urate pellet excretion is discussed in relation to the nitrogen economy of <i>Parcoblatta fulvescens</i>. / Master of Science / incomplete_metadata

Call number: LD2668 .T4 1956 C73 / Master of Science

Call number: LD2668 .T4 1957 B57 / Master of Science

Bibliography: leaves 142-147 / x, 147 leaves, [17] leaves of plates : ill ; 30 cm. / 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 Entomology, 1987

Chronic heart failure is one of the commonest fatal diseases in the world. Much work has been done to reveal its complicated pathogenesis and develop effective therapy. Xinmailong (XML), a compound extracted from Periplaneta americana, has been launched on the market in Mainland China as a proprietary medication for treating patients with chronic heart failure. Although it is highly effective, its mechanism of action is still not completely understood. In this study, the results of calcium (〖Ca〗^(2+)) imaging demonstrated that XML increased electrical impulse-induced intracellular calcium ([〖Ca〗^(2+)]i), in H9c2 cells, an rat embryonic cardiomyocytes cell line. This effect was dependent on extracellular 〖Ca〗^(2+) but not the 〖Ca〗^(2+) store from sarcoplasmic reticulum because XML had no effect on thapsigargin -induced 〖Ca〗^(2+) release. The effect of XML was inhibited by ML218-HCl but not nimodipine, indicating that XML interacted with T-type 〖Ca〗^(2+) channels but not L-type 〖Ca〗^(2+) channels. Unlike KB-R7943, which is a sodium calcium exchanger inhibitor, XML did not affect [〖Ca〗^(2+)]i in the absence of electric stimulation, implying that XML did not work on sodium calcium exchanger. Ouabain, a sodium-potassium ATPase inhibitor, increased the electrical impulse-induced [〖Ca〗^(2+)]i and the effect of ouabain and XML were not additive, suggesting that the site of action of ouabain and XML was overlapped. Biochemical assay on phosphate concentration showed that XML was able to inhibit the activity of sodium-potassium ATPase. Our study also demonstrated that XML reduced the production of reactive oxygen species in H9c2 cells. Western blotting showed that such antioxidant properties mechanism might involve the increased expressions of antioxidant enzymes including superoxide dismutase 1, superoxide dismutase 2 and heme oxygenase 1. In conclusion, our study has provided evidence that XML increases [〖Ca〗^(2+)]i level by activating T-type 〖Ca〗^(2+) channels and inhibiting sodium-potassium ATPase. The antioxidant effect of XML may also contribute to the cardioprotective effect of XML but further investigation is required. / published_or_final_version / Pharmacology and Pharmacy / Master / Master of Philosophy