Various biological relationships between the myramid egg parasite, Anaphes ovijentatus (Crosby and Leonard), and its hosts were studied. Eggs of the four major species of Lygus that occur on crops were highly parasitized. Other mirid hosts in southern Arizona were collected from weeds in agricultural areas. Small numbers of Nabis alternatus Parshley and N. americoferus Carayon, predators of several insect pests, were parasitized in the laboratory. The membracid Spissistilus festinus (Say) was an infrequent host. Parasitism of L. hesperus was similar (82-88%) for eggs 1-6 days old at 25°C, but parasitism of 7-day-old eggs was significantly reduced (18.9%). Parasitism must occur at least 24 hours prior to host egg hatch to be successful; the period of time required for A. ovijentatus egg development. Anaphes ovijentatus developed from egg to adult in L. hesperus eggs at a constant temperature of 12.8°C and at variable regimes with means of 12.8, 10.6, and 32.8°C. An average of 26 progeny per female were produced at the variable 12.8 and 10.6°C regimes, only a few progeny were produced at a constant 12.8°C and none were produced at the variable 32.8°C regime. Lygus hesperus eggs hatched at all four temperature regimes, but nymphs survived to adulthood only at the variable regimes of 12.8 and 10.6°C. Total egg to egg periods at the variable 12.8°C was approximately 103 days for L. hesperus and about 54 days for A. ovijentatus. The majority of the L. hesperus eggs were deposited in the upper halves of cotton, alfalfa, and the crucifer Sisymbrium irio L. plants. L. hesperus deposited more eggs in alfalfa than in cotton plants, but showed no preference between alfalfa and S. irio. Anaphes ovijentatus did not demonstrate clear preferences for L. hesperus eggs in any plant species or plant section.

Further functional investigation revealed that knockdown of GRP78 expression by RNA interference resulted in a significant increase of both intracellular and extracellular HBV virions in the transient HBV-producing HepG2 cells, concomitant with enhanced levels of hepatitis B surface antigen and e antigen in the culture medium Conversely, overexpression of GRP78 in HepG2 cells led to HBV suppression concomitant with induction of the positive regulatory circuit of GRP78 and interferon-beta 1 (IFN-beta1). In this connection, IFN-beta1-mediated 2', 5'-oligoadenylate synthetase (OAS) and ribonuclease L (RNase L) signaling pathway was noted to be activated in GRP78-overexpressing HepG2 cells. Moreover, GRP78 was significantly down-regulated in the livers of chronic hepatitis B patients after effective anti-HBV treatment (p= 0.019) as compared with their counterpart pre-treatment liver biopsies. / Hepatitis B virus (HBV) infection is a global public health problem, which plays a crucial role in the pathogenesis of chronic hepatitis, cirrhosis and hepatocellular carcinoma. Although considerable progress has been made over the past decade, the pathogenesis of HBV infection and the mechanisms of host-virus interactions are still elusive. / In conclusion, the present study demonstrates for the first time that GRP78 functions as an endogenous anti-HBV factor via IFN-beta1-OAS-RNase L pathway in hepatocytes. Induction of hepatic GRP78 may provide a novel therapeutic approach in treating HBV infection. / In this study, we applied a two-dimensional gel electrophoresis and mass spectrometry-based comparative proteomic approach to globally analyze the host early response to HBV by using an inducible HBV-producing cell line HepAD38. Twenty-three proteins were identified as differentially expressed, with glucose-regulated protein 78 (GRP78) as one of the most significantly up-regulated proteins induced by HBV replication. This induction was further confirmed in both HepAD38 and HepG2 cells transfected with HBV-producing plasmids by real-time reverse transcription-polymerase chain reaction (RT-PCR) and Western blotting, as well as in HBV-infected human liver biopsies by immunohistochemistry. / Ma, Yan. / Adviser: Ming-Liang He. / Source: Dissertation Abstracts International, Volume: 72-01, Section: B, page: . / Thesis (Ph.D.)--Chinese University of Hong Kong, 2010. / Includes bibliographical references (leaves 111-129). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. Ann Arbor, MI : ProQuest Information and Learning Company, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.

Arceuthobium americanum is a vascular plant which is parasitic upon Pinus contorta var murrayana. Its documented effects include reductions in host growth, vigor and wood quality. The specific physiological changes that occur in the host are, for the most part, unknown.

Abstract not available

Most organisms are rarely infected with just a single species of parasite and are usually simultaneously infected with a range of species. Thus, the parasite fauna of a host represents an entire community composed of multiple individuals from many different species. In nature, it is within the host that parasites can encounter conspecifics and individuals from other species. As in any ecosystem, while such interactions between parasites can be antagonistic due to competition or conflicting interests, association between different species can also be beneficial. In this thesis, I investigated patterns of associations between parasites in the New Zealand cockle Austrovenus stutchburyi through a combination of descriptive and experimental studies employing both standard ecological field techniques and molecular biology methods. It was found that the presence and infection intensity of various parasites species are not independent of each other. Among cockles, an association was found between two trematode taxa, i.e. between the infection intensity by foot-encysting echinostomes and the metacercariae of Gymnophallus sp. It was also found that the presence of the parasitic copepod Pseudomyicola spinosus was associated with greater infection intensity by the echinostomes but not Gymnophallus sp. While it was postulated that the positive association between the echinostomes and Gymnophallus sp. was due to the latter�s preference to infect cockles that are stranded on the sediment surface as a result of heavy echinostome metacercariae burden in their foot, a field experiment found that Gymnophallus cercariae did not preferentially infect cockles that have been forced to remain above the sediment surface as opposed to those that were forced to remain buried. Meanwhile, the two species of echinostomes known to encyst in the cockle�s foot, Acanthoparyphium sp. and Curtuteria australis, were found to represent cryptic species complexes. The presence of such cryptic species means that it is possible that some potential interspecific interactions are overlooked. A study of the population structure of Gymnophallus sp. found that each cockle contains multiple genetically distinct individuals and that clonal individuals rarely co-occur in the same cockle. This adds to the growing body of evidence suggesting that in addition to acting as a means of reaching the definitive host, the second intermediate host also acts to promote genetic diversity by accumulating cercariae shed by multiple first intermediate hosts in the environment. An experimental infection study conducted with Curtuteria australis cercariae deriving from singly-infected first intermediate hosts revealed that different clonal lineages varied with respect to their contribution to host manipulation. It was found that while certain lineages have a preference for host manipulation, others tend to adopt a "hitch-hiker"-type life history strategy. However, this genetic predisposition was also found to be a phenotypically plastic trait, as the presence of a higher number of manipulators seems to encourage newly-arrived cercariae to become manipulators, regardless of clonal lineage. This thesis provides evidence that patterns of interactions can affect various aspects of parasite life history. Apart from host condition, parasites can also be affected by other parasites. Studying the dynamics of mixed infections can provide informative insights for evolutionary and ecological research.

Includes bibliography / ii, 84 leaves, [7] leaves of plates : ill. (some col.) ; 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 Plant Pathology, 1987

Bibliography: leaves 113-128 / xii, 128, [63] leaves, [6] 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 Microbiology and Immunology, 1984

Bibliography: leaves 218-251.

Bibliography: leaves 111-137.

Bibliography: leaves 82-111. This thesis analyses the molecular composition of the surface components of the Endoparasitoid "Venturia canescens" using serological methods and specific sugar-binding lectins as diagnostic tools. The data reveals that the protective layer consists of at least two parts: a mucin-like glycoprotein and additional components from the wasp calyx fluid and the host hemolymph. The study suggests that the wasp larval cuticle is protected in a similar fashion to the egg chorion, except that the calyx-specific VLPs are probably replaced on the larval cuticle by host hemolymph proteins. The findings suggest that the mechanism of passive immune evasion could emerge during the evolution of the wasp-host interactions. The implication is that structurally conserved components may have similar functions in the parasitic and non parasitic species and could constitute a useful pre-adaptations for an endoparasitoid lifestyle.