196,071 research outputs found
Development of the larval parasitoid fly, Exorista larvarum (Diptera: Tachinidae) with emphasis in its movements and attachment strategy to the host tissue
No full textExorista larvarum (L.) is a polyphagous gregarious larval endoparasitoid of Lepidoptera. Female flies deposit macrotype eggs on the host surface. The newly-hatched larva penetrates the host integument, induces the formation of a primary integumental respiratory funnel and develops through three larval instars. Pupation generally occurs outside the host larval remains.
The morphology of larval E. larvarum was studied in its factitious host Galleria mellonella (L.) (Lepidoptera: Pyralidae). Last instar host larvae were exposed for parasitization to female flies and removed when the 3 - 5 eggs had been laid on their body. Parasitized larvae were dissected and fixed every day of the parasitoid development, which lasts 3 - 4 days from egg hatching to pupal stage at 26°C. Specimens were embedded in Histoplast II and sections 5 - 7 μm thick were stained with hematoxylin - eosin and Masson΄s trichrome stain. To obtain sections of better quality, the cryosection and rapid microscopic analysis were also used. Frozen sections were stained with azan or hematoxylin - eosin.
Here, we focus on the integument and related structures participating in the movements and attachment process of E. larvarum larva to the host tissue. The tachinid larva penetrates the host using the robust cephalopharyngeal skeleton that undergoes changes during larval development. Using mouthhooks, it feeds on host hemolymph and subsequently on fat body and other host tissues. During larval development the digestive tract gradually becomes more extensive and denotes a great increase in the third instar, which abandons the funnel and migrates in the host body cavity. The tracheal system with prominent respiratory plates is well developed in all larval instars. The larvae are equipped with a thick anal hook and numerous cuticular spines supporting the larva in their attachment to the respiratory funnel. The external morphology of E. larvarum larvae of all instars was studied by electron microscopy. The behaviour of E. larvarum larvae in the host tissues and the escape of the advanced-third instar larvae from the host carcass were documented in vivo using the light microscope
Penetration and encapsulation of the larval parasitoid, Exorista larvarum (Diptera: Tachinidae) in the factitious host Galleria mellonella (Lepidoptera: Pyralidae)
No full textThe tachinid fly, E. larvarum is a polyphagous larval endoparasitoid which deposit macrotype eggs on the host exoskeleton. The newly-hatched larvae burrow through the host integument, leaving a dark spot in the point of their penetration as a result of cuticle melanisation. The attachment of E. larvarum larvae to the host tissues and formation of the hemocyte capsule surrounding the tachinid larva were studied in the last larval instar of the wax moth, Galleria mellonella (L). Parasitization was carried out according to the standard laboratory procedure. The parasitized larvae were examined, dissected and fixed every day of the parasitoid development, which lasts 3 - 4 days from egg hatching to pupal stage at 26°C. Standard histological techniques were used. The material was embedded in Histoplast II and sections 5 - 7 μm thick were stained with hematoxylin - eosin and Masson΄s trichrome stain. As the parasitoid first and second instar larvae are more difficult to be sectioned, the cryosection and rapid microscopic analysis were used to obtain sections of better quality. Frozen sections were stained with azan or hematoxylin - eosin. Our histological examination showed that the endoparasitoid penetration induces the host cellular defence resulting into the formation of a hemocyte capsule consisting of a multi-cellular sheath. This enveloping capsule later undergoes melanisation, which is more evident towards the abdominal part of the parasitoid larval body. The tachinid larva uses this encapsulation response, as well as the integument reaction to wounding, to build the respiratory funnel. The encapsulated larva is attached to the respiratory funnel via an anal hook and cuticular spines and remains in contact with the outside air with its posterior spiracles until the third instar (when the funnel is abandoned). The respiratory funnel was also studied by scanning electron microscopy
Penetration and encapsulation of the larval endoparasitoid Exorista larvarum (Diptera: Tachinidae) in the factitious host Galleria mellonella (Lepidoptera: Pyralidae)
No full textThe tachinid fly Exorista larvarum (L.) (Diptera: Tachinidae) is a polyphagous
larval endoparasitoid that deposits its eggs on the host exoskeleton of lepidopteran
and tenthredinid larvae. The attachment of larval E. larvarum and the formation of the
respiratory funnel were studied during infestation in the last larval instar of the wax
moth, Galleria mellonella (L.) (Lepidoptera: Pyralidae). The tachinid larvae burrow
through the host integument after hatching, using their robust cephalopharyngeal
skeleton, leaving a dark spot at the point of their penetration as a result of host
cuticle melanization. Endoparasitoid penetration induces the host cellular defence,
resulting in the formation of a haemocyte capsule consisting of multi-cellular sheaths.
This enveloping capsule later undergoes melanization, which is mostly obvious
towards the posterior part of the endoparasitoid. The endoparasitoid uses the
host encapsulation response to build a respiratory funnel from the modified host
integument, leading to the host surface. The encapsulated larva remains attached
to the respiratory funnel via an anal hook and cuticular spines until fully developed.
Additional immunohistochemical analyses were used to study host–parasitoid
interactions. Indirect immunofluorescence showed no labelling of potential tachinid
antigens and confirmed no effect on the surrounding host tissues. A simulated
parasitization with coated polybead microspheres revealed the mortal impact
of tachinid antigens to the host. Hosts injected with antigen-coated polybeads died as a consequence of an acute and extensive immunological response to
the tachinid antigens and not due to the trauma caused by foreign objects inside their
body.
Dr. Duane M. Jackson, Morehouse College, July 2011
No full textThis video is a conversation with Dr. Duane M. Jackson. Dr. Jackson talks about his paper, "Recall and the Serial Position Effect: The Role of Primacy and Recency on Accounting Students' Performance." Jackie Daniel, AUC Woodruff Library, is the interviewer
"Reflections on the subject of Emigration from Europe with a view to Settlement in the United States" By M. Carey.
No full text"Reflections on the subject of Emigration from Europe with a view to Settlement in the United States: containing bried sketches of the moral and political character of those states.
By M. Carey, member of the American philosophical, and of the American Antiquarian Society, and author of The Olive Branch, Cindiciae Hibernicae, essays on banking, on political economy, and on internal improvement.
To which are now added the English editor's comments on the subject; together with Important Advice to Emigrants, and Cautions Against Impositions Practiced in the Outports
Community ecology of parasites of chub fry (Leuciscus cephalus L.)
No full textThe formation and development of metazoan parasite community of chub fry (Leuciscus cephalus L.) was followed in the period from July 2000 to May 2001. Chub fry (N=190) were sampled monthly from the River Morava. Altogether 27 parasite species have been recorded. The most common parasites in the investigated locality were representatives of the class Monogenea, especially viviparous gyrodactylids. First, juvenile fish 29 mm in size were found to be infected with ectoparasites and metacercariae. On the opposite, host fish larger then 50 mm were colonised with intestinal parasites
Dispelling the Myths Behind First-author Citation Counts
No full textWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Dr. Glendon Swarthout
No full textHosted by Roger M. Busfield, MSU Assistant Professor of Speech and Theater, Meet the Author is designed to introduce a general audience to a contemporary author and their work through in-depth interviews. This episode features a conversation between Dr. Glendon Swarthout, prolific author and English professor at MSU, and assistant professors Sam S. Baskett and Theodore B. Strandness
Simulation of thermal plant optimization and hydraulic aspects of thermal distribution loops for large campuses
No full textFollowing an introduction, the author describes Texas A&M University and its utilities system. After that, the author presents how to construct simulation models for chilled water and heating hot water distribution systems. The simulation model was used in a $2.3 million Ross Street chilled water pipe replacement project at Texas A&M University. A second project conducted at the University of Texas at San Antonio was used as an example to demonstrate how to identify and design an optimal distribution system by using a simulation model. The author found that the minor losses of these closed loop thermal distribution systems are significantly higher than potable water distribution systems. In the second part of the report, the author presents the latest development of software called the Plant Optimization Program, which can simulate cogeneration plant operation, estimate its operation cost and provide optimized operation suggestions. The author also developed detailed simulation models for a gas turbine and heat recovery steam generator and identified significant potential savings. Finally, the author also used a steam turbine as an example to present a multi-regression method on constructing simulation models by using basic statistics and optimization algorithms. This report presents a survey of the author??s working experience at the Energy Systems Laboratory (ESL) at Texas A&M University during the period of January 2002 through March 2004. The purpose of the above work was to allow the author to become familiar with the practice of engineering. The result is that the author knows how to complete a project from start to finish and understands how both technical and nontechnical aspects of a project need to be considered in order to ensure a quality deliverable and bring a project to successful completion. This report concludes that the objectives of the internship were successfully accomplished and that the requirements for the degree of Degree of Engineering have been satisfied
Intern experience at CH���M Hill, Inc.: an internship report
No full textIncludes author's vita"Submitted to the College of Engineering of Texas A&M University in partial
fulfillment of the requirement for the degree of Doctor of Engineering."Includes bibliographical referencesA review of the author's internship experience with CH���M HILL, Inc.
during the period September 1975 through May 1976 is presented. During this nine month
internship the author worked as an Engineer II in the Industrial Processes discipline of this
large consulting engineering firm... The author's prime responsibility was as one of three
lead design engineers on the design of a large wastewater treatment facility for a pulp mill
in Hoquiam, Washington owned by ITT Rayonier Inc. The work generally consisted of the design
of individual treatment units and associated piping and pumping. The purpose of the project
was to provide wastewater treatment capabilities that would satisfy the effluent limitations
(standards) imposed upon the mill by the State of Washington Department of Ecology and the
U.S. Environmental Protection Agency. The author's assignment also entailed necessary
interaction with the project manager and other CH���M HILL design engineers and support staff
members, the client's representatives, and representatives of two other consulting engineering
firms working on the project. Thus, the internship position at CH���M HILL provided considerable
experience coordinating the author's work with the work of other engineers, guiding the design
and administrative efforts of a support staff, and interacting regularly with the client and
other consulting firms. This broad exposure to a variety of engineering and organizational
problems provided a valuable educational experience
- …
