Regulation of enzymatic activity involved in sex pheromone production in the housefly, Musca domestica

Ovarian produced ecdysteroids regulate sex pheromone production in the female housefly, inducing the synthesis of (Z)-9-tricosene (Z9-23:Hy), cis-9,10-epoxytricosane, (Z)-14-tricosen-10-one and methylalkanes. Experiments were performed to gain a detailed understanding of the processes affected by 20-hydroxyecdysone (20-HE) that result in sex pheromone production as the female becomes reproductively mature. A novel microsomal fatty acid synthetase (FAS) is present in the epidermal tissue and plays a role in producing the methyl-branched fatty acid precursors to the methylalkanes. This FAS is released from the microsomes in the presence of 3 M KCl. A major enzyme activity influenced by 20-HE is the fatty acyl-CoA elongation system. A shift in the chain length specificity of the products of the elongation system causes the change in the chain lengths of the alkenes produced to switch from C27 and longer in the previtellogenic female to C23 in the mature female. Data is presented indicating that it is the condensation activity of the elongation system that is affected. Z9-23:Hy arises from a 24 carbon acyl group which is reduced to an aldehyde, and then converted to the hydrocarbon. Data is presented demonstrating that it is the fatty acyl-CoA derivative and not the free fatty acid that is the substrate. There does not appear to be a chain length specificity which regulates the conversion of fatty acyl-CoAs to hydrocarbons as both 24 and 28 carbon fatty acyl-CoAs are converted to hydrocarbon by both males and females of all ages.     

Fine structure and x-ray microanalysis of mineralized concretions in the malpighian tubules of the housefly, Musca domestica

The epithelium and the lumen of the Malpighian tubules of the housefly contains mineralized dense bodies called concretions. The morphological characteristics, mode of origin, nature of the sequestered elements and the age-associated changes in the distribution of concretions are reported. There are three types of concretions in the cytoplasm, which have been designated as type A, type B, and type C. Type A concretions are membrane-bound spherical structures which may arise by the gradual intravacuolar accumulation of dense material. Type B concretions appear to be related to multivesicular bodies. Type C concretions are heteromorphic and morphologically resemble the residual bodies. They show a positive localization of acid phosphatase reaction product. X-ray microanalysis of intracytoplasmic and intraluminal concretions revealed the presence of phosphorus, sulphur, chlorine, calcium, iron, zinc and copper. There was no evidence suggesting the extrusion of the intracytoplasmic concretions into the lumen of the Malpighian tubules. There is an age-associated increase in the distribution of type C concretions. It is hypothesized that the sequestration of metal ions within the concretions may provide a means for the effective excretion of these elements.     

Characterization of a novel microsomal fatty acid synthetase (FAS) compared to a cytosolic FAS in the housefly, Musca domestica

A novel membrane-bound fatty acid synthetase (FAS) associated with the microsomal fraction from the housefly, Musca domestica, was solubilized and purified to homogeneity. The microsomal FAS was solubilized by 0.75 M KCl in phosphate buffer and was purified to homogeneity by the sequential use of ammonium sulfate precipitation followed by Sepharose CL-6B, DEAE Sephacel and Red Agarose (dye ligand affinity) chromatography. The specific activity of the microsomal FAS was increased 1,440-fold to 6,522 U/mg during purification. The cytosolic FAS from the housefly was also purified by similar methods and the specific activity increased 183-fold to 7,533 U/mg. The relative molecular mass of the microsomal and cytosolic FAS are 419 +/- 22 kDa and 405 +/- 18 kDa, respectively, for the dimers as determined by gel permeation chromatography. The microsomal and the cytosolic FAS yield different tryptic digestion maps and have slightly different amino acid compositions, which demonstrate structural differences between the two FASs. In addition, there are differences between the two FASs in their kinetic characteristics and their ability to incorporate methylmalonylCoA into the growing fatty acyl chain.     

Resistance to fenitrothion in Danish houseflies, Musca domestica

Resistance to fenitrothion was investigated in housefly populations in Danish farms 1964--72 in connection with trials of fenitrothion, dimethoate and other organophosphorus compounds for fly control. Resistance was tested by topical application and expressed as resistance ratios, R/S, relative to normal susceptible strains. In 1964--70 fly populations on farms sprayed with fenitrothion (one year each) only developed mode-rate fenitrothion-resistance, R/S at LD 95 below 21 and fly control was generally satisfactory. However, in 1972 high fenitrothion-resistance, R/S 100--400 at LD 95, was found in several fly populations, both on farms treated with fenitrothion and on farms treated with dimethoate, fenitrothion, or bromophos. In all cases the high fenitrothion-resistance was associated with high resistance to dimethoate. Some characteristics of this, apparently complex, resistance are discussed including the effect of certain synergists. Resistance to fenitrothion in Danish flies is only partly reduced by pretreatment with high dosages of sesamex, which inhibits microsomal detoxication, and very little by TBTP (S, S, S tributyl phosphorotrithioate), which inhibits other types of break-down of organophosphorus compounds, e.g. by ali-esterases. The occurrence of fenitrothion- resistance in field populations of houseflies in other regions is briefly reviewed. Widespread, partly very high, resistance has recently been reported from Japan.     

Ecdysteroidostatin from the house fly, Musca domestica

Ovaries from house flies maintained on sucrose secrete large amounts of ecdysteroid when they are cultured with ovarian ecdysteroidogenic hormone, OEH. However, ovarian ecdysteroid secretion is reduced by incubation with both OEH and the ovarian ecdysteroidostatin (OES). A partially purified OES fraction from a semi-preparative reverse phase HPLC C18 column caused a 98% inhibition of ovarian ecdysteroid secretion in vitro at a concentration of 0.8 equivalents per microliter. Ovaries can be activated to produce ecdysteroid in vivo by feeding diet containing protein to flies maintained on sucrose. Ecdysteroid secretion was inhibited when the in vivo stimulated ovaries were cultured with OES. This suggests that OES does not interfere with the OEH activation mechanism, but blocks ovarian ecdysteroid synthesis or release. Furthermore, OES inhibition is reversible and ecdysteroid secretion resumes when OES is removed. Musca OES could explain the decrease in ecdysteroid levels found in flies after mid-vitellogenesis. Both adult male and female abdomens contain OES, but OES was not transferred to females during mating. Evidence is presented that OES is not a trypsin modulating oostatic factor.     

Effects of luminance, contrast, and blur on visual acuity

Although previous investigations have reported that changes in background luminance, stimulus contrast, and dioptric blur can each affect visual acuity independently, it has not been shown how these three variables interact to influence visual acuity. This is a particularly important issue if one is interested in predicting how individuals with different refractive characteristics will be able to perform acuity-based tasks in degraded visual environments with low background lighting and contrast levels. To investigate these relations, we conducted a series of experiments in which measurements of visual acuity were obtained for four subjects using Landolt C targets of varying contrast at several background luminances for levels of blur between 0 and 8 diopters (D). Our results show that visual acuity is significantly affected by all three factors, and that their effects are essentially additive. At all luminance and contrast levels, the reduction in visual acuity is greatest for dioptric blur up to 2.0 D, with a more gradual reduction in visual acuity for dioptric blur of greater than 2.0 D. At all blur and luminance levels, visual acuity decreases gradually for contrast levels down to 20%, and decreases sharply for lower contrast levels. Over the range of background luminances we tested (75.0 to 0.075 cd/m2), visual acuity decreases linearly with reductions in luminance. The additive effects of dioptric blur, contrast, and luminance provide a basis for predicting visual acuity-related task performance for individuals in different visual environments. For example, an individual with 6/6 (20/20) visual acuity under high luminance-high contrast conditions will fall to 6/18 (20/60) acuity for low luminance conditions and 6/30 (20/100) for low luminance-low contrast conditions. Similarly, an individual with an uncorrected visual acuity of 6/30 (20/100) under optimal conditions will fall to approximately 6/120 (20/400) under low luminance conditions and 6/240 (20/800) under low luminance-low contrast conditions.     

Processing of procathepsin from Musca domestica eggs

The major source of amino acids for insect embryos are yolk proteins which accumulate in developing oocytes and are hydrolyzed during embryogenesis. Studies on Musca domestica embryogenesis indicated that a cathepsin B-like proteinase is responsible for yolk protein degradation (Ribolla et al., 1993). In this study, we report the purification of mature cathepsin and show that it is made up of a single 41 kDa polypeptide chain. The Musca domestica cathepsin NH2-terminal 11-residue sequence was determined (Ala-Pro-Lys-Tyr-Val-Asp-Tyr-Gly-Glu-Asn-Glu) and reveals homology with other cathepsins of the papain family. Experiments using serum anti-cathepsin show that the enzyme is stored in oocytes as a 55 kDa zymogen. The activation of the zymogen occurs in vitro only at low pH. In vitro activation in the presence of cysteine protease inhibitors is blocked at an intermediary polypeptide of 48 kDa. Kinetic studies of this activation process at pH 3.5 and 4.6 show that the zymogen is processed in a manner similar to that of pepsin (Foltmann, 1986) and papain (Vernet et al., 1991). We propose that Musca domestica cathepsin zymogen activation occurs in two steps. First, an intramolecular cleavage of the procathepsin polypeptide chain (55,000), induced by low pH gives rise to an intermediary polypeptide (48,000) which then undergoes autolysis to produce the mature enzyme (41,000).     

Effects of contrast and generalization on the attitude similarity–attraction relationship.

36 undergraduates read about the attitudes of 2 strangers (A and B) whom they had met and who had both initially agreed with the Ss on 50% of a number of topics. After a brief period of time, each S again met the 2 strangers. During this 2nd meeting, Stranger A continued to agree with the S at a 50% rate, whereas Stranger B agreed with the S at a 100% rate. In the 1st condition, the 2 strangers were depicted as members of the same group, and in a 2nd condition, the 2 strangers were depicted as members of different groups. Results indicate that after the 2nd meeting, there was less of a difference between the attractiveness of Strangers A and B in the same-group condition compared to the different-group condition. In addition, within the different-group condition, Stranger A was liked less after the 2nd meeting than after the 1st meeting, whereas within the same-group condition, Stranger A was liked more after the 2nd meeting than after the 1st meeting. Results support the notion that the effects of contrast are accentuated when 2 individuals being rated are distinct entities (members of different groups), whereas generalization is accentuated when the 2 individuals are not distinct entities (members of the same group). (14 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Sex-lethal, the master sex-determining gene in Drosophila, is not sex-specifically regulated in Musca domestica

BACKGROUND: Previously, the authors reported that 82% of cases of pancreatic carcinoma were positive for p53 in cytologic specimens obtained by selective endoscopic pancreatic duct brushing (SEPB). However, there was an extreme discrepancy between the authors' data of p53 overexpression using cytologic specimens and other reports using surgically resected specimens. In this study, the authors demonstrate that p53 positive cells precisely reflect its gene mutations, and also establish systematic procedures for the preoperative diagnosis of patients with pancreatic carcinoma. METHODS: The authors examined 44 cases of pancreatic carcinoma, 30 cases of chronic pancreatitis, and 9 cases of papillary adenoma. In all cases, pathologic diagnosis was made by surgery or autopsy. The conventional cytology and p53 immunocytology were performed simultaneously in the cell specimens obtained by SEPB. In the cases immunostained for p53, DNA was extracted selectively from p53 immunostained cells using a light microscope. p53 mutations in exons 5 to 8 were examined by direct sequencing. RESULTS: Forty of 44 pancreatic carcinomas (91%) were diagnosed correctly by the methods of conventional cytology associated with p53 immunocytology. p53 mutations were detected in 12 of 14 cases that were positive for p53 (86%). Four of six cases that were inoperable due to massive metastasis or invasion had the mutation at codon 273 (CGT to CAT) in exon 8. CONCLUSIONS: These results suggest that p53 immunocytology reflects its gene mutations precisely, and that the point mutation at codon 273 (CGT to CAT) of p53 may play an important role in the invasive potential and metastasis of pancreatic carcinoma.     

苦杏仁精油对家蝇的触杀活性研究

[目的]研究含HCN和去HCN的苦杏仁精油对家蝇的触杀活性,为苦杏仁精油作为卫生害虫杀虫剂提供依据.[方法]采用"点滴法"测定含HCN和去HCN的苦杏仁精油对家蝇的触杀活性.[结果]2种苦杏仁精油对家蝇具有很强的触杀活性,触杀活性随着处理时间的延长而增强,且去HCN的苦杏仁精油的杀虫活性高于含HCN的苦杏仁精油.[结论]苦杏仁精油对家绳具有很强的触杀活性,可作为卫生害虫杀虫剂加以开发利用.     

The effect of dimethoate selection on trichlorfon and dimethoate sensitivity in Musca domestica

Selecting of strain a Musca domestica resistant to trichlorphon with Bi 58 (active ingredient: dimethoate) resulted in an only slight (1.33-fold) increase of the resistance to dimethoate between 1974 and 1975. In the same time the resistance to trichlorphon rose to 5.28 times the original degree. The resistance extends to some other organophosphates, especially malathion, dichlorvos and bromophos, but not to diazinon. Among the insecticides registered for control of flies in pig-sties Bi 58 has the greatest chance, though there exists neither a certainty for the decrease of the resistance to trichlorphon nor for the non-appearance of a resistance to dimethoate. To overcome the problem of flies in stables and sties, particularly in plants of industrial cattle-breeding, complex measures must be taken.     

Distribution of heterochromatin on the mitotic chromosomes of Musca domestica L. in relation to the activity of male-determining factors

Nitric oxide (NO) is a pluripotent regulatory molecule, yet the molecular mechanisms by which it exerts its effects are largely unknown. Few physiologic target molecules of NO have been identified, and even for these, the modifications caused by NO remain uncharacterized. Human glutathione reductase (hGR), a central enzyme of cellular antioxidant defense, is inhibited by S-nitrosoglutathione (GSNO) and by diglutathionyl-dinitroso-iron (DNIC-[GSH]2), two in vivo transport forms of NO. Here, crystal structures of hGR inactivated by GSNO and DNIC-[GSH]2 at 1.7 A resolution provide the first picture of enzyme inactivation by NO-carriers: in GSNO-modified hGR, the active site residue Cys 63 is oxidized to an unusually stable cysteine sulfenic acid (R-SOH), whereas modification with DNIC-[GSH]2 oxidizes Cys 63 to a cysteine sulfinic acid (R-SO2H). Our results illustrate that various forms of NO can mediate distinct chemistry, and that sulfhydryl oxidation must be considered as a major mechanism of NO action.     

Vector potential of houseflies (Musca domestica) for Helicobacter pylori

The mode of transmission of Helicobacter pylori is unknown. Since viable bacteria have been shown to be excreted in feces from infected individuals and houseflies habitually develop and feed on excrement, we hypothesized that flies ingest and harbor H. pylori and, in turn, contaminate the human environment. This study examined the possible vector potential of houseflies (Musca domestica) for H. pylori. Caged houseflies were exposed to freshly grown H. pylori on agar plates. After a 6-h feeding period, the plates were removed and were replaced with sterile petri dishes containing a droplet of sterile brucella broth. At regular intervals, small numbers of houseflies were removed for microbiological and histological analysis, and the petri dishes were replaced with fresh sterile plates with fresh drops of brucella broth. The flies' bodies, the flies' dissected alimentary tracts, and excreta on the petri dishes were cultured for H. pylori, whose identity was confirmed by the urease, catalase, and oxidase reactions and Gram staining. In contrast to control flies, viable H. pylori could be isolated from external surfaces for up to 12 h and from gut and excreta for as long as 30 h after the initial feeding period. After 30 h other gram-negative bacteria overgrew the cultures of samples from all locations tested, rendering the selective culture of H. pylori colonies impossible. Histological analysis revealed Helicobacter-like organisms in the gut lumen and attached to intestinal epithelial cells. We conclude that houseflies can harbor viable H. pylori on their bodies and in their intestinal tracts. They are also able to disseminate viable H. pylori in excreta, and they may therefore present a significant reservoir and be a vector in the transmission of H. pylori.     

Insecticidal properties of citrus oils against Culex pipiens and Musca domestica

Peel oils of lemon, grapefruit and navel orange were tested for insecticidal activities against larvae and adults of Culex pipiens and Musca domestica. Lemon peel oil was the most effective against larvae and adults of C. pipiens. Grapefruit peel oil was more toxic to adults of M. domestica while lemon oil, was more toxic Musca larvae. On the other hand, the orange peel oil was the least effective against larvae and adults of both species. The toxicity of oils applied to larval stages was extended to pupal and adult stages. C. pipiens adults appeared with paralyzed legs, while M domestica adults appeared normal. The weights of pupae treated as larvae were generally less than that of the control. All oils produced deleterious effects on fecundity of survivors of sublethal doses. The effect was obviously recorded in treated adults. Treatment of Culex & Musca with oils caused serious latent effect.     

Genetic and light intensity effects on the activity and emigratory behavior of the house fly, Musca domestica (L.)

The emigratory behavior and locomotor activity of yellow-eyed (y/y), wild-type (+/+), and heterozygous (+/y) house flies was examined at 8 fc (86 lx) and 1600 fc (17,223 lx) light intensities. At 8 fc, emigration rate and activity of the y/y flies was similar to that of the +/+ and +/y flies. However, at 1600 fc, the y/y flies emigrated at twice the rate and showed an activity of about one-third that of the other genotypes. The behavior of the +/+ and +/y flies remained similar regardless of the experimental design or light intensity. The excessive neural stimulation by high-intensity light resulting from reduced shielding pigments led to behavioral modifications in the visual and tactile responses of the y/y flies.     

Calibrating reach distance to visual targets.

The authors investigated the calibration of reach distance by gradually distorting the haptic feedback obtained when participants grasped visible target objects. The authors found that the modified relationship between visually specified distance and reach distance could be captured by a straight-line mapping function. Thus, the relation could be described using 2 parameters: bias and slope. The authors investigated whether calibration generalized across reach space with respect to changes in bias and slope. In Experiment 1, the authors showed that both bias and slope recalibrate. In Experiment 2, they tested the symmetries of reach space with respect to changes in bias. They discovered that reach space is asymmetric, with the bias shifting inward more readily than outward. The authors measured how rapidly the system calibrated and the stability of calibration once feedback was removed. In Experiment 3, they showed that bias and slope can be calibrated independently of one another. In Experiment 4, the authors showed that these calibration effects are not cognitively penetrable. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The role of the house fly (Musca domestica) in the dissemination of hookworm

The effect of cooling rate, warming rate, and duration of phase transition upon survival of frozen canine kidneys was investigated. In the present study, 11 kidneys out of 14 rapidly cooled (2--4degreesC/min) to --22degreesC and thawed (70--110degreesC/min) were viable following contralateral nephrectomy. The serum creatinine and BUN levels rose to a maximum of 8.4 and 30 mg%, respectively, on the eighth day post-contralateral nephrectomy. Average survival time was 10 days; however, two of the dogs in this group were allowed to survive, one for 3 months and one for over 2 years. Eight kidneys out of 16 slowly cooled (0.25-1.0degreesC/min) and either rapidly or slowly warmed (20-30degreesC/min) had function to produce small amounts of urine; however, they did not survive more than 5 days after contralateral nephrectomy. Cooling rates of 0.1 and 10degreesC/min were too harmful to the kidney to have renal function after reimplantation. The minimum renal cell damage as assessed by LDH and GOT in the post-freeze perfusate was found in the 2-4degreesC/min cooling rate following rapid warming (70degrees-110degreesC/min). Correlation of the duration of phase transition time to renal cell damage was linear for LDH and GOT (r=0.93). This result suggests that the duration of phase transition time also is an important factor during the freezing process, affecting post-thaw survival of canine kidneys.