• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 47
  • 14
  • 2
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • Tagged with
  • 80
  • 17
  • 12
  • 11
  • 10
  • 9
  • 9
  • 9
  • 7
  • 6
  • 6
  • 5
  • 4
  • 4
  • 4
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
51

Chromosome banding of German cockroach spermatocytes

Keil, Clifford B. 13 March 2009 (has links)
A chromosome banding protocol for <u>Blattella germanica</u> speramtocytes was developed to reveal locations of constitutive heterochromatin (C-bands). Normality of the acid treatment used to denature basic (histone) proteins, temperature of the salt solution used to extract DNA from unhanded regions, and the components of the Romanowsky-type stain proved to be critical components in the C-banding process. The thiazine component of a standard Gieasa stain had an absorbance maximum altered from that of methylene blue, the putative major thiazine in this stain and was ineffective in producing C-bands. Two samples of Leishman's stain were examined chromatographically, spectrophotometrically, and for their C-bandinq ability as they aged. Banding failure was accompanied by a rounding of the thiazine spectral peak and the appearance of unknowns with cbromatographic mobility intermediate to azures A and B, and an apparent increase in azure C content. Experimental thermal and photo-degradation of Leishman's stain shoved similar alterations of the thiazine components. c-banded prop base II and diplotene kacyotypes revealed a hiqhly heteroaorphic pattern of C-band distribution. Blocks of constitutive heterochromatin were not soley associated with centroaeres bat occurred interstitially and terminally also. One chromosome was C-band negative, number 8, while two others. 9 and the X, were almost completely heterochromatic. Differential rates of condensation from prophase I to prophase II for euchromatic and heterochromatic regions were documented. The karyotype of <u> B. germanica</u> contained many gray bands that may indicate euchroaatin interspersed with heterochromatin. Translocation heterozygote stocks were used to correlate the banded karyotype with linkage groups. Translocation multivalents frequently contained C-bands Dot resolved in wild type chromosomes. A C-banded prophase II karyotype of a closely related species, <u>Blattella vaga</u>, was prepared to assess the variability of heterochromatin distribution. The basic banding pattern was preserved in four of the twelve chromosomes although the bands were larger in this species. Tvo chromosomes, 11 and 8, had a single additional C-band in each. The basic banding pattern was preserved in four of the twelve chromosomes although the bands larger in this species. Two chromosomes, 11 and 89, had a single additional C-band in each. The <u>B. vaga X</u> chromosome was about twice as large as that in <u>B. germanica</u>. The mid-sized chromosomes were extensively repatterned. Overall, <u>B. vaga</u> chromosomes were longer than those of <u>B. germanica</u>. Increased heterochromatin content appeared to be the cause of the greater length. / Ph. D.
52

Application of insecticides to control the German cockroach, Blattella germania (L.)

Zhai, Jing 10 June 2009 (has links)
Control strategies for the German cockroach, Blattella germanica (L.), are usually based on the application of liquid insecticides in or near infested harborages. Cockroach mortality occurs when they are exposed to insecticide residue by walking on insecticide-treated surfaces. Cockroach walking depends on the three pairs of legs. Only tarsal pads and arolium on each leg are involved in traveling and picking up insecticide residue. The total contact area at each step was 0.1879 mm² and 0.1771 mm² for laboratory susceptible (VPI) and field-collected (RHA) cockroach strains, respectively. There were no significant differences (P > 0.05) in the walking distance in two steps among three legs, or between the two strains. However, the walking movement rate greatly influences the amount of insecticide accumulated on tarsal pads in a distinct time period. RHA-strain cockroach walked a significantly (P < 0.05) greater distance than VPI-strain on untreated and 10 ug/cm² of cypermethrin treated glass plates. RHA-strain cockroaches picked up significantly (P < 0.05) more cypermethrin than VPI-strain in 5 min, but there was no difference when exposed for 30 movement units. Knockdown time was significantly correlated (P < 0.05) to estimated dose transfer in 0.025 μg/cm² and 0.049 μg/cm² treatments for the VPI-strain, and in 0.245 μg/cm² and 0.392 μg/cm² for the RHA strain. Cockroach knockdown time and mortality were determined by cockroaches walking on different numbers of cypermethrin droplets on treated glass plates. Insecticide dose could be reduced from 10 μg/cm² to 0.025 μg/cm², but resulted in increasing the KT₅₀ from 5.4 min to 15.9 min in VPI-strain cockroaches. To achieve 50% cockroach knockdown, a VPI-strain cockroach must walk on at least 33 droplets (130 μm in diameter) of 0.1% cypermethrin; an RHA-strain cockroach must walk on at least 3174 droplets. High insecticide dosage increased the amount of antennal grooming in VPI-strain cockroaches and stimulated leg grooming in RHA-strain. Walking movement activities decreased in response to increased antennal and leg grooming. / Master of Science
53

A morphological study of first-stage nymphs of five Periplaneta species (Dictyoptera: Blattidae)

Powell, Peggy K. January 1979 (has links)
Adults of Periplaneta americana, P. australasiae, P. brunnea, P. fuliginosa, and P. japonica are well known and have been well described. However, little systematic work has been conducted on the immature stages. There are very few descriptions of the nymphs of any Periplaneta species, and those that are available are rather brief and not completely accurate. This paper presents detailed descriptions and keys to the first-stage nymphs of the above species. Five types of setae, including unique mechanoreceptive setae, were found on the thoracic segments. P. australasiae, P. fuliginosa, and P. brunnea have very setose thoracic nota·and a banded color pattern, while thoracic nota of P. americana and P. japonica are less setose and solid in color. Great variability of setal number and color pattern probably exists among all the species in the genus. / Master of Science
54

Reproduction and Metabolic Responses to Acute and Chronic Hypoxia in Ovoviviparous Blaberid Cockroaches, with a Focus on Blaptica dubia

Mallery, Christopher Sean 08 1900 (has links)
The major components of the tracheal system of insects are an extension of the exoskeleton, and the size of the exoskeleton is fixed in the adult stage, so any increase in metabolic demand that may accompany reproduction must be met by a relatively unaltered tracheal system that the female set in place at ecdysis, when entering adulthood. Acute hypoxia tends to elicit an increase in ventilation in insects, and here, I observe increased interburst VCO2 release, and a tendency towards a more continuous gas exchange pattern being preferred over discontinuous gas exchange when Blaptica dubia and Eublaberus posticus are exposed to a descending regime of hypoxia. Additionally, higher temperatures appear to increase sensitivity to hypoxia in these species, an expected result because both species, like most ectothermic animals, display a Q10 effect, increasing metabolic rates as temperature increases. The reproductive mode of B. dubia is considered to be lecithotrophic pseudoviviparity (or type A ovoviviparity), and by the time the embryos are born, they have more than doubles in volume from the time of oviposition. This gain is apparent in the wet mass of the embryo, with no change occurring in dry mass. The egg mass that can be attributed to water begins at 39% at oviposition and increased to nearly 82% at hatching. The metabolic rates of females and embryos increase as embryonic development progresses, but bomb calorimetry reveals that energy content of the embryos does not change. It is possible that these embryos gain some nutrition from the mother during embryonic development, but direct evidence remains to be demonstrated. Blaptica dubia and Eublaberus posticusare both blaberid species that display the same reproductive mode, pseudoviviparity, with incubation occurring in a brood sac. Comparisons between the reproductive traits of B. dubia and E. posticus reveal that the two species have similar reproductive periods, interbirth periods, and clutch sizes to one another, and that both have reproductive cycles and incubation times intermediate to oviparous species and the one species of cockroach that some consider to be truly viviparous (Diploptera punctata). However, whereas adult female E. posticus are larger than female B. dubia (E. posticus non-gravid female mass: 2.91 +/- 0.42 g, 20; B. dubia non-gravid female mass: 2.60 +/- 0.40 g, 20), the offspring of B. dubia are larger than those of E. posticus at the time of birth (B. dubia neonate mass: 24.70 +/- 4.01 mg, 19; E. posticus neonate mass: 22.40 +/- 1.36 mg, 19). Both gravid and non-gravid female B. dubia respond similarly to acute hypoxia exposure, increasing mean total VCO2. However, the reproductive state does not appear to exacerbate, nor dull, the acute response to hypoxia. Gravid and non-gravid female B. dubia were exposed to chronic hypoxia for 30 days and 45 days. Relatively high mortality was observed in nearly all chronic hypoxic treatment groups as compared to controls at 21 kPa O2. Comparing treatment groups to controls maintained at 21 kPa O2, embryo mass was not decreased, nor was embryo VCO2 at day 30. Adult female B. dubia metabolic rates did not show a consistent change in response to chronic hypoxia, but decreased metabolic rate was observed in the non-gravid B. dubia exposed to chronic 4 kPa O2, an observation that is consistent with past studies in insects. Survival rates were lower for both gravid and non-gravid females in 4, 8, and 12 kPa O2, as well as in 15 kPa O2 in gravid females, as compared to 21 kPa O2. Gravid females experiences a decreased survival rate compared with non-gravid females at 12 and 15 kPa O2, but gravid and non-gravid females had similarly low survival rates at 4 and 8 kPa O2. This difference in survival rates suggests there is a cost associated with carrying an ootheca in a brood sac, resulting in an increased sensitivity to hypoxia, at least over a long period of time.
55

Catecholamines in the hemolymph and cuticle of the American cockroach, Periplaneta americana (L.) and the Madeira cockroach, Leucophaea maderae (F.)

Czapla, Thomas H. January 1985 (has links)
Call number: LD2668 .T4 1985 C92 / Master of Science
56

Physical and insecticidal stress effects on the foregut of the cockroaches Leucophaea maderae (Fabr.) and Periplaneta americana (L.)

Ameel, John Jules. January 1965 (has links)
Call number: LD2668 .T4 1965 A51 / Master of Science
57

Intraspecific Gene Flow and Vector Competence among Periplaneta americana Cockroaches (Blattodea: Blattidae) in Central Texas

Pechal, Jennifer 16 January 2010 (has links)
One of the most overlooked areas in forensic entomology is urban, which applies to insects and their arthropod relatives that have interactions with humans, their associated structures, and companion animals. American cockroaches, Periplaneta americana (L.), are common pests of urban environments. Analyzing spatial distribution of P. americana populations in an artificial, outdoor environment provided insight of gene flow among populations collected in central Texas. This information provides for a better understanding of how and if populations were segregated, or if there was a single unified population. Populations can be genetically differentiated through determining variation of specific gene regions within populations. This study revealed a ubiquitous distribution of cockroach populations, and their ability to indiscriminately inhabit areas within an urban environment. Overall, cockroaches were identified from a large interbreeding population with no discernable relationship between genetic variation of P. americana and spatial distribution. Identifying cockroach populations is relative to understanding the ability of surrogate species indirectly affecting man by their ability to transfer disease-causing organisms including bacteria. This may have potentially deleterious health consequences on animal and/or human populations. There are several pathogens associated with cockroaches which are overlooked during diagnosis of sudden ailments with symptoms being similar to food-borne illnesses, including abdominal cramping, diarrhea, nausea, and fever. Analyzing spatial distributions of Escherichia coli and Campylobacter spp. in relationship to collected cockroaches allowed for prevalence of bacteria species to be identified among populations. The prevalence of bacteria isolated from total populations collected indicated a high prevalence (92.3%) of bacteria carried by the exoskeleton of P. americana. Gram-negative bacteria acquisition and dissemination of organisms such as E. coli was prevalent on campus. Screening for E. coli 1057:H7 and Campylobacter spp. resulted in no positive colony growth. The lack of Campylobacter spp. growth from cuticular surfaces may have resulted from undesirable conditions required to sustain colony growth. Data from this study corroborates the potential ability of cockroaches to mechanically transmit pathogens.
58

Predictors of indoor dust mite and cockroach levels

Brooks, J. Mark. January 2007 (has links) (PDF)
Thesis (Ph. D.)--University of Alabama at Birmingham, 2007. / Title from first page of PDF file (viewed June 30, 2007). Includes bibliographical references (p. 94-101).
59

USING MADAGASCAR HISSING COCKROACHES AS RESEARCH SUBJECTS IN BEHAVIOR ANALYSIS

Gunnarsson, Karl Fannar 01 August 2013 (has links)
The current study investigated the effects of environmental cues on foraging behavior of Madagascar hissing cockroaches using a maze. By placing the subjects in the maze and have them freely roam around; familiarizing themselves with the maze they gradually spent more time where reinforcement was available. As a mean of measurement, the reinforcers were then removed and the maze was flipped 180 degrees. The results were that the subjects allocated majority of their time in the area of the maze where reinforcers were previously available, and when reinforcers had a different spatial location they went to the location where it had been previously. Implications and limitations are discussed.
60

The metabolism of adenosine nucleotides in thoracic muscle mitochondria from the American cockroach

Mills, Richard Randolph January 1964 (has links)
Myokinase and three inorganic pyrophosphatases with pH optima of 6.4, 7.2 and 8.4 have been isolated and purified from the thoracic muscle mitochondria of the American cockroach. Myokinase was purified over 100-fold by heat and acid treatment, ammonium sulfate fractionation and column chromatography on G-75 sephadex. Some properties of the enzyme were determined. These include: a pH optimum of 5.8, an optimum Mg concentration of 3 x 10⁻³ M, a substrate specificity for ADP, and an equilibrium constant of 0.44. In addition, Km and Ki values were determined for each adenosine nucleotide, inhibition studies were conducted, and the enzyme was found to have the greatest stability against heat denaturation at a neutral pH. From the results obtained here it appears that the enzyme apyrase is not responsible for the rapid dephosphorylation of ATP. In addition, this study indicates that a specific triphosphatase coupled with myokinase produces the products AMP and P<sub>i</sub> which are found when crude homogenates are used as the enzyme. The three inorganic pyrophosphatases were purified by sonication, ultracentrifugation, ammonium sulfate fractionation, and column chromatography on G-75 sephadex, DEAE cellulose, and CM cellulose. The three enzymes were found to have distinct pH optima: one acid, one neutral and one alkaline. The enzyme activated at a neutral pH needed only one-half as much Mg as substrate. The optimum ratio for the other two enzymes was one to one. Substrate specificity studies indicated that the enzymes may be important in the breakdown of polyphosphates and GTP. No other high energy phosphate bonds were acted on. The physiological significance remains obscure although data from this study indicate that an important function of the enzymes may be to remove undesirable pyrophosphate from the mitochondria. / Ph. D.

Page generated in 0.0271 seconds