RESUMEN

The last 50 years of research into infections in Australia and New Zealand caused by larvae of the sheep blowfly, Lucilia cuprina, have significantly advanced our understanding of this blowfly and its primary host, the sheep. However, apart from some highly effective drugs it could be argued that no new control methodologies have resulted. This review addresses the major areas of sheep blowfly research over this period describing the significant outcomes and analyses, and what is still required to produce new commercial control technologies. The use of drugs against this fly species has been very successful but resistance has developed to almost all current compounds. Integrated pest management is becoming basic to control, especially in the absence of mulesing, and has clearly benefited from computer-aided technologies. Biological control has more challenges but natural and perhaps transformed biopesticides offer possibilities for the future. Experimental vaccines have been developed but require further analysis of antigens and formulations to boost protection. Genetic technologies may provide potential for long-term control through more rapid indirect selection of sheep less prone to flystrike. Finally in the future, genetic analysis of the fly may allow suppression and perhaps eradication of blowfly populations or identification of new and more viable targets for drug and vaccine intervention. Clearly all these areas of research offer potential new controls but commercial development is perhaps inhibited by the success of current chemical insecticides and certainly requires a significant additional injection of resources.

Asunto(s)

Dípteros , Control de Insectos , Miasis/veterinaria , Enfermedades de las Ovejas/prevención & control , Animales , Australia , Dípteros/genética , Dípteros/inmunología , Dípteros/fisiología , Control de Insectos/métodos , Control de Insectos/tendencias , Resistencia a los Insecticidas , Insecticidas , Larva , Miasis/inmunología , Miasis/prevención & control , Nueva Zelanda , Control Biológico de Vectores , Ovinos , Enfermedades de las Ovejas/inmunología , Vacunas

RESUMEN

Despite the availability of effective treatments, Sarcoptes scabiei remains a major health problem in the pig industry. Unsuccessful control of the disease is often due to the lack of reliable detection methods, with current tests relying on skin scrapings and crude antigen ELISAs. A previous analysis of antigens in pig skin scrapings reported that anti-transferrin antibodies were present in S. scabiei infected animals and that this finding might be considered as a useful diagnostic tool. This paper confirms IgG autoantibodies against transferrin, including the first report of IgM autoantibodies, in both naturally and experimentally infected pigs using ELISA and dot blot assays. Autoantibodies were also detected in pigs to ferritin and to a lesser extent lactoferrin. Immunoblotting confirmed the presence of IgG and IgM autoantibodies in mange positive pigs, as well as IgM antibodies to transferrin and albumin in mange negative pigs. These findings suggest the presence of natural autoantibodies to transferrin and albumin in pigs. The development of the IgG autoimmune response may either be a host mechanism for limiting iron to the mite via antibody mediated clearance, the result of host exposure to mite iron-binding homologues or because of a mite-induced antigenic change to host transferrin. Further investigation into the formation of these autoantibodies may provide insights into the importance of iron in scabies infections and the development and perseverance of S. scabiei infections in pigs. The specificity and sensitivity of the anti-transferrin response reinforces its potential in the diagnosis of scabies in pigs.

Asunto(s)

Autoanticuerpos/sangre , Proteínas de Unión a Hierro/inmunología , Sarcoptes scabiei/inmunología , Escabiosis/veterinaria , Enfermedades de los Porcinos/parasitología , Animales , Ensayo de Inmunoadsorción Enzimática/veterinaria , Escabiosis/diagnóstico , Escabiosis/inmunología , Porcinos , Enfermedades de los Porcinos/diagnóstico , Enfermedades de los Porcinos/inmunología

RESUMEN

The current state of myiasis vaccine technologies are reviewed mainly in the primary research genera of Lucilia and Hypoderma. The importance of myiasis flies as primary causes of morbidity and mortality in agricultural species and man has not diminished despite the existence of good control strategies. However, the development of vaccines against myiasis infections has been relatively quiescent for more than 10 years despite the rapid development of genomic and proteomic analysis and of skills in data interpretation. The value of vaccine research in an era of chemical primacy is analysed. In fact, recent findings of drug resistance and the impact of animal welfare concerns should mean a renewed interest in alternative controls. The reasons that this has not been true to date are explored and new possibilities discussed.

Asunto(s)

Enfermedades de los Bovinos/inmunología , Dípteros/fisiología , Miasis/veterinaria , Enfermedades de las Ovejas/inmunología , Vacunas/administración & dosificación , Animales , Bovinos , Enfermedades de los Bovinos/parasitología , Enfermedades de los Bovinos/prevención & control , Dípteros/crecimiento & desarrollo , Miasis/inmunología , Ovinos , Enfermedades de las Ovejas/parasitología , Enfermedades de las Ovejas/prevención & control

RESUMEN

BACKGROUND: The aims of the present study were to identify the common gastrointestinal nematodes, to assess the prevalence of infestation with gastrointestinal nematodes, and to assess some potential indirect determinants of nematode parasitism in Victorian Pony Club horses. METHODS: A total of 106 horses from five Pony Clubs from outer Melbourne and Geelong, Victoria, Australia, were enrolled in a cross-sectional study. Fresh faecal samples were collected and faecal egg counts (FECs) performed on site within 2 h of collection. Potential determinants of the FEC were analysed using logistic and negative binomial regression. RESULTS: FECs ranged from 0 to 3750 eggs per gram (epg), with an average of 422 epg. Eggs were detected in the faeces of 52% of horses (55/106) and the average count was 813 epg. Counts were 500 epg or greater in 27% (29/106) of horses. Pony Club, season and sex of the horse were not associated with the FEC. Among horses treated with anthelmintics 8 weeks or less prior to sampling, FECs were commonly ≥50 epg, and high FECs were relatively common. CONCLUSIONS: The results indicate that treatment efficacy is commonly low and/or rapid re-infection after treatment is common, and show that management practices for internal parasite control are often inadequate for preventing high FECs among Pony Club horses in Victoria.

Asunto(s)

Enfermedades Gastrointestinales/veterinaria , Enfermedades de los Caballos/epidemiología , Enfermedades de los Caballos/parasitología , Nematodos/aislamiento & purificación , Infecciones por Nematodos/veterinaria , Animales , Estudios Transversales , Heces/parasitología , Femenino , Enfermedades Gastrointestinales/epidemiología , Enfermedades Gastrointestinales/parasitología , Caballos , Modelos Logísticos , Masculino , Infecciones por Nematodos/epidemiología , Infecciones por Nematodos/parasitología , Recuento de Huevos de Parásitos/veterinaria , Prevalencia , Estaciones del Año , Victoria/epidemiología

RESUMEN

Helicoverpa species present problems worldwide as pests on a variety of agricultural crops. In Australia, the costs of controlling H. armigera (Hübn.) and H. punctigera (Wall.) are a major burden on the cotton industry, and novel mechanisms are continually sought to combat these pests. Potential new targets for insecticides are the digestive proteases of the insect, including the aminopeptidases (APs). A variety of compounds, designed to be similar in structure to known AP inhibitors, were synthesized and screened for activity in inhibiting H. armigera larval growth and AP activity. The most effective compounds in both assays proved to be hydroxamic acids and methylphosphonic acids. Compounds that incorporated both of these groups were also found to have significant potential as control agents. The most inhibitory compounds included valine methylphosphonic acid and a leucine methylphosphonic acid/hydroxamic acid derivative. The valine methylphosphonic acid compound was tested further in vitro, with the aim of producing a new active capable of restricting the viability of Helicoverpa populations on commercial crops.

Asunto(s)

Aminopeptidasas/antagonistas & inhibidores , Insecticidas/análisis , Larva , Mariposas Nocturnas , Animales , Ácidos Hidroxámicos/química , Organofosfonatos/química , Compuestos Organofosforados/química , Ftalimidas/química , Tetralonas/química , Valina/análogos & derivados , Valina/química

RESUMEN

Sarcoptes scabiei continues to cause major health and economic problems in a large range of animals and humans. Although the inflammatory response to the mite and its antigens is known to cause the main pathology, little work has been carried out on this response at the site of infection. This report presents an initial analysis of the proteins found in skin scrapings and their antigenic responsiveness in pigs. Skin scrapings and mite extracts were isolated from chronically infected sows while infected and uninfected sera were isolated from pigs with confirmed infections or mange-free pigs, respectively. Electrophoresis and sequencing confirmed the main components of both the skin and mite extracts to be serum proteins. Immunoblotting then suggested that transferrin was the major antigen recognised by pooled infected sera in the skin and the mite extracts. Immunoassays confirmed that a majority of infected pigs produced antibodies to transferrin while mange-free pigs did not. A pool of IgG from infected dogs was then used to isolate another antigen from pig skin scrapings which was shown to be haptoglobin. This was also found to induce high titres of antibody in infected pigs as compared with mange-free pigs. The use of albumin as a control antigen showed no reactivity in either group of sera. The finding of two iron-binding molecules as strong auto-antigens in pig scabies has implications for the importance of iron during this infection and may help to explain the persistence and magnitude of the host inflammatory response.

Asunto(s)

Autoantígenos/análisis , Sarcoptes scabiei/inmunología , Escabiosis/inmunología , Escabiosis/veterinaria , Piel/parasitología , Porcinos/inmunología , Animales , Western Blotting , Ensayo de Inmunoadsorción Enzimática , Haptoglobinas/análisis , Haptoglobinas/inmunología , Immunoblotting , Inmunoglobulina E/análisis , Inflamación , Piel/inmunología , Transferrina/análisis , Transferrina/inmunología

RESUMEN

This study sets out to provide a systematic analysis of the development of the primordial central nervous system (CNS) in embryos of two decapod crustaceans, the Australian crayfish Cherax destructor (Malacostraca, Decapoda, Astacida) and the parthenogenetic Marbled crayfish (Marmorkrebs, Malacostraca, Decapoda, Astacida) by histochemical labelling with phalloidin, a general marker for actin. One goal of our study was to examine the neurogenesis in these two organisms with a higher temporal resolution than previous studies did. The second goal was to explore if there are any developmental differences between the parthenogenetic Marmorkrebs and the sexually reproducing Australian crayfish. We found that in the embryos of both species the sequence of neurogenetic events and the architecture of the embryonic CNS are identical. The naupliar neuromeres proto-, deuto-, tritocerebrum, and the mandibular neuromeres emerge simultaneously. After this "naupliar brain" has formed, there is a certain time lag before the maxilla one primordium develops and before the more caudal neuromeres follow sequentially in the characteristic anterior-posterior gradient. Because the malacostracan egg-nauplius represents a re-capitulation of a conserved ancestral information, which is expressed during development, we speculate that the naupliar brain also conserves an ancestral piece of information on how the brain architecture of an early crustacean or even arthropod ancestor may have looked like. Furthermore, we compare the architecture of the embryonic crayfish CNS to that of the brain and thoracic neuromeres in insects and discuss the similarities and differences that we found against an evolutionary background.

Asunto(s)

Sistema Nervioso Central/embriología , Sistema Nervioso Central/crecimiento & desarrollo , Decápodos/embriología , Decápodos/crecimiento & desarrollo , Animales , Axones/ultraestructura , Sistema Nervioso Central/ultraestructura , Embrión no Mamífero , Desarrollo Embrionario , Femenino , Ganglios/ultraestructura , Neuronas/ultraestructura , Factores de Tiempo

RESUMEN

The management of myiasis in livestock has been an example of the success of modern chemical approaches for parasite control, yet in some cases remains extremely intractable, requiring the development of novel strategies. In addition, the growing and urgent need to develop integrated strategies that enhance the sustainability of livestock production systems drives the search for new techniques [see Int. J. Parasitol. 29 (1999) 7].The following summary represents a synthesis of a symposium presented at the 19th International Conference of the World Association for the Advancement of Veterinary Parasitology, New Orleans,USA, 10­14 August 2003. The coverage began with a review of the need for more subtle economic analysis of the impact of myiasis based on the use of the sterile insect technique (SIT) for control of bovine hypodermosis in North America. This was followed by a review of the status of chemical control with particular emphasis on the macrocyclic lactones. The outcome of the use of these compounds in a regulated control program for eradication of bovine hypodermosis in EU was surveyed. Similarly, the success of the screwworm eradication program, using the sterile insect technique has shown how effective this approach can be given the appropriate target. Several aspects of the development of newer approaches were surveyed in discussion of newer chemical control products, development of vaccines, use of host genetics, use of predictive simulation modelling and trapping for monitoring and control and the development of new diagnostic approaches for occult infestations. Finally, use of the latest molecular tools for identification of larvae causing myiasis and their use for the identification of species coming from different and distant geographical areas to colonize regions where they have been eradicated was reviewed.

Asunto(s)

Enfermedades de los Bovinos/prevención & control , Miasis/veterinaria , Animales , Antiparasitarios/uso terapéutico , Bovinos , Enfermedades de los Bovinos/tratamiento farmacológico , Enfermedades de los Bovinos/economía , Enfermedades de los Bovinos/parasitología , Erradicación de la Enfermedad/tendencias , Miasis/tratamiento farmacológico , Miasis/economía , Miasis/prevención & control , Medicina Veterinaria/tendencias

RESUMEN

Passive intraperitoneal transfer of sera from Fasciola hepatica-infected sheep, cattle or rats can protect naive rats from F. hepatica infection, suggesting a parasite killing mechanism within the peritoneal cavity that is dependent on the presence of parasite-specific antibody. We investigated antibody-dependent cell-mediated cytotoxicity by resident peritoneal lavage cell populations, containing large numbers of monocytes/macrophages, as a potential host resistance mechanism by which juvenile flukes could be killed within the peritoneal cavity of naive rats. Comparative studies were conducted using cell populations containing large numbers of monocytes/macrophages from sheep. The results demonstrate that monocyte/macrophage-rich lavage cell populations from rat and sheep differ substantially in their ability to generate nitric oxide. Only resident rat peritoneal lavage cells were able to mediate antibody-dependent cell-mediated cytotoxicity against newly excysted juvenile liver fluke. The mechanism of cytotoxicity was dependent on, and directly proportional to, the production of nitric oxide and required attachment of effector cells to the newly excysted juvenile liver fluke tegument, which occurred following the addition of sera from F. hepatica-infected animals. This is the first report demonstrating a mechanism of cell-mediated cytotoxicity to newly excysted juvenile liver fluke.

Asunto(s)

Citotoxicidad Celular Dependiente de Anticuerpos/inmunología , Fascioliasis/inmunología , Óxido Nítrico/inmunología , Animales , Anticuerpos Antihelmínticos/sangre , Anticuerpos Antihelmínticos/inmunología , Fasciola hepatica/inmunología , Fascioliasis/parasitología , Radicales Libres/metabolismo , Lipopolisacáridos/inmunología , Hígado/inmunología , Hígado/parasitología , Masculino , Nitratos/inmunología , Óxido Nítrico/biosíntesis , Nitritos/inmunología , Nitrógeno , Lavado Peritoneal , Ratas , Ratas Wistar , Ovinos

RESUMEN

Taraxastane, oleanane, ursane, lupane, taraxane, cycloartane, dammarane and tirucallane triterpenoids isolated from flowers of Compositae plants have been previously reported to exhibit anti-inflammatory effects and are variously competitive and non-competitive inhibitors of the serine proteases trypsin and chymotrypsin. The general features of those triterpenoids found to be protease inhibitors are having a hydroxy group and an appropriate side chain in the region of the molecule distal to the 3-hydroxy group. However, fatty acid esterification of the triterpenoid 3-hydroxy group can have a marked effect on inhibitor effectiveness. This suggests a possible means of rapid alteration of the plant defensive complement in vivo and of the bioactivity of these anti-inflammatory compounds.

Asunto(s)

Antiinflamatorios no Esteroideos/farmacología , Asteraceae/química , Quimotripsina/efectos de los fármacos , Triterpenos/farmacología , Inhibidores de Tripsina/farmacología , Tripsina/efectos de los fármacos , Antiinflamatorios no Esteroideos/química , Extractos Vegetales/farmacología , Tallos de la Planta/química , Triterpenos/química , Inhibidores de Tripsina/química

RESUMEN

The science of parasitology is one of the many new disciplines of the twentieth century, as such it is a dynamic and rapidly evolving science which encompasses an increasing number of sub-disciplines and technologies. However, will the fragmentation involved in current methods of scientific enquiry and the competition for funding mean the decline of certain areas of parasitology or perhaps the complete loss of the discipline. This paper attempts to address these questions by considering the development of the discipline of parasitology especially within Australia and by considering the mechanisms of attaining funding for science. Technological change and its impact on parasitology is also considered, and requirements for maintenance of the discipline and its practitioners are suggested.

Asunto(s)

Sociedades Científicas , Australia , Humanos , Parasitología/economía , Parasitología/métodos , Recursos Humanos

RESUMEN

New neurons are added to two bilateral clusters of neurons in crayfish brain throughout their lives. These interneurons are associated with the olfactory and accessory lobes, areas of the brain that receive primary olfactory information and higher order inputs from the visual and tactile receptor systems. The rate of cell proliferation in these four clusters, revealed by BrdU labeling, is sensitive to the living conditions of the animals: individuals isolated in small spaces (impoverished condition) exhibit a lower rate of cell proliferation in comparison to their siblings living together in larger areas (enriched condition), although both groups were fed to satiation. Reduction in the rate of proliferation can be measured 1 to 2 weeks after the animals are subjected to the impoverished condition. Counts of the labeled neurons that survive after 4 weeks of subjection to the two conditions show that fewer new neurons survive in the brains of animals that have lived for 2 weeks in the impoverished condition in comparison to their siblings living in the enriched conditions. Factors such as surface area, depth of water, and social interaction can all play a role in determining both the rate of new neuron production and the incorporation of the new neurons into the brain of freshwater crayfish. The results indicate a high degree of neuronal plasticity in the crayfish brain that is highly sensitive to the conditions under which the animals are kept.

Asunto(s)

Astacoidea/fisiología , Encéfalo/fisiología , División Celular/fisiología , Supervivencia Celular/fisiología , Ambiente Controlado , Plasticidad Neuronal/fisiología , Neuronas/fisiología , Privación Sensorial/fisiología , Animales , Astacoidea/citología , Encéfalo/citología , Bromodesoxiuridina , Recuento de Células/estadística & datos numéricos , Neuronas/citología

RESUMEN

The lupane triterpenoid lupeol, the ursane triterpenoid alpha-amyrin and esters of these compounds are present in the bark of roots of Alstonia boonei (Apocynaceae) and have anti-inflammatory properties. alpha-Amyrin is a competitive inhibitor of bovine trypsin and chymotrypsin (Ki values 29 microM and 18 microM, respectively). Lupeol linoleate, lupeol palmitate and alpha-amyrin linoleate are non-competitive inhibitors of trypsin (Ki values 7 microM, 10 microM and 16 microM, respectively). alpha-Amyrin linoleate is also a non-competitive inhibitor of chymotrypsin (Ki value 28 microM). Lupeol is a competitive inhibitor of both trypsin and chymotrypsin (Ki values 22 and 8 microM, respectively). alpha-Amyrin palmitate is a potent non-competitive inhibitor of chymotrypsin (Ki 6 microM). Lupeol, alpha-amyrin and the palmitic and linoleic acid esters of these compounds are ineffective or very weak as inhibitors of porcine pancreatic elastase and of Lucilia cuprina and Helicoverpa punctigera leucine aminopeptidases. These hydrophobic triterpenoids represent further examples of anti-inflammatory triterpenoids that are PKA inhibitors as well as being selective protease inhibitors.

Asunto(s)

Antiinflamatorios no Esteroideos/farmacología , Inhibidores de Serina Proteinasa/farmacología , Triterpenos/farmacología , Animales , Bovinos , Proteínas Quinasas Dependientes de AMP Cíclico/antagonistas & inhibidores

RESUMEN

A small, medial heterolateral neuropil in the brain of crustaceans has long been regarded as the central body of the crustacean brain. Its simplicity and the absence of clear layers within its neuropil have led to the question of its homology with the more complex central body that occupies an approximately equivalent position in the brain of insects. We have labelled neurons in the central body of the Australian freshwater crayfish Cherax destructor by the extracellular application of dextrans and by treating the brain with antibodies to anti-CCAP, anti-locustatachykinin, anti-perisulfakinin, anti-proctolin, anti-dip-allatostatin AI, anti-PEA-head-peptide, anti-serotonin, and anti-rabbit anti-substance P, all of which label neurons in the insect brain. The dextran and immunocytochemical labelling have revealed a neural complex associated with the crayfish central body that is very similar in overall anatomical architecture to the subset of neuropils that are incorporated in the central complex of the insects, and in particular to that of the locust. Similarities between the crayfish and locust central complexes extend to the number and position of the neuropils, the location of the cell body clusters of the neurons that belong to the central complex, the numbers of tracts that link some of the constituent neuropils together, and the form and immunoreactivity of many of the individual neuron classes. These similarities are taken as evidence to support a possible homology between the crustacean central complex and that of the insects.

Asunto(s)

Astacoidea/anatomía & histología , Evolución Biológica , Encéfalo/anatomía & histología , Insectos/anatomía & histología , Neuritas/fisiología , Neurópilo/fisiología , Animales , Encéfalo/fisiología

RESUMEN

A series of experiments were carried out to investigate the role of proteinase enzymes in the growth of larvae of the sheep blowfly, Lucilia cuprina. First, instar larvae were incubated on an artificial growth media in the presence of various concentrations of inhibitors of all the major proteinase classes. Inhibitors of serine proteinases and aminopeptidases were found to cause significant growth inhibition and in some cases death of the larvae within 24 h, suggesting that these enzymes were the major classes involved in protein digestion in the gut of the insect. A second group of experiments analysed the effects of two inhibitors from the same or different proteinase classes in the growth media. Synergistic inhibition of larval growth was observed with the incorporation of inhibitors of serine proteinases and aminopeptidases. The results suggest that these classes of proteinases are both central to protein digestion in this insect, probably in the gut, and that the inhibition of both types of activity leads to an almost complete blockade of digestion. Testing in vivo gave similar results with infections on sheep skin inhibited by either serine proteinase or aminopeptidase enzyme inhibitors and the combination of both stopped the infection process. The role of aminopeptidases in larval metabolism and as potential targets for blowfly control agents is examined.

Asunto(s)

Aminopeptidasas/antagonistas & inhibidores , Antiparasitarios/farmacología , Dípteros/efectos de los fármacos , Miasis/veterinaria , Inhibidores de Proteasas/farmacología , Inhibidores de Serina Proteinasa/farmacología , Enfermedades de las Ovejas/tratamiento farmacológico , Aminopeptidasas/metabolismo , Animales , Antiparasitarios/uso terapéutico , Dípteros/enzimología , Dípteros/crecimiento & desarrollo , Sinergismo Farmacológico , Larva/efectos de los fármacos , Larva/enzimología , Larva/crecimiento & desarrollo , Miasis/tratamiento farmacológico , Miasis/parasitología , Inhibidores de Proteasas/uso terapéutico , Inhibidores de Serina Proteinasa/uso terapéutico , Ovinos , Enfermedades de las Ovejas/parasitología

RESUMEN

Freshwater crayfish increase in size throughout their lives, and this growth is accompanied by an increase in the length of the appendages and number of mechanoreceptive and chemoreceptive sensilla on them. We find that in the Australian freshwater crayfish Cherax destructor, neuropil volumes of the olfactory centers increase linearly with body size over the entire size range of animals found in their natural habitat. The number of cell somata of two groups of interneurons associated with the olfactory centers (projection neurons and small local neurons) also increases linearly with the size of the animals. In contrast, axon counts of interneurons that represent a nonolfactory input to the olfactory centers show that these reach a total number in the very early adult stages that then remains constant regardless of the size of the animal. Only the axon diameter of these interneurons increases linearly with body size. Amputation of the antennule and olfactory sensilla reduces the number of projection and local interneurons on the amputated side. No change in the size of the olfactory centers occurs on the unamputated side. Amputation of the olfactory receptor neurons in crayfish therefore leads not only to a degeneration of the receptor cell endings in the olfactory lobe but also to a trans-synaptic response in which the number of higher order neurons decreases. Reconstitution of the antennule and olfactory receptor neurons in small adult crayfish is accompanied by the reestablishment of the normal number of interneurons and neuropil volume in the olfactory centers.

Asunto(s)

Astacoidea/embriología , Astacoidea/crecimiento & desarrollo , Vías Olfatorias/embriología , Vías Olfatorias/crecimiento & desarrollo , Órganos de los Sentidos/embriología , Órganos de los Sentidos/crecimiento & desarrollo , Envejecimiento/fisiología , Animales , Encéfalo/citología , Encéfalo/embriología , Encéfalo/crecimiento & desarrollo , Recuento de Células , Muerte Celular/fisiología , División Celular/fisiología , Tamaño de la Célula/fisiología , Embrión no Mamífero/fisiología , Interneuronas/citología , Neurópilo/fisiología , Vías Olfatorias/citología , Regeneración/fisiología , Órganos de los Sentidos/citología

RESUMEN

Proteolytic activity present in the excreted/secreted (ES) material of newly excysted juvenile (NEJ) Fasciola hepatica was biochemically analyzed. By gelatin substrate SDS-PAGE, only one region of activity was observed in the NEJ ES material at a molecular mass of 29 kDa. Both the secreted cathepsin L from adult fluke and the 29-kDa proteolytic activity of NEJ ES show a common pH optimum of 7.5, a cysteine protease inhibition profile, and preference for the N-benzyloxycarbonyl (Z)-Phe-Arg-NHMec fluorogenic substrate over Z-Arg-Arg-NHMec and Z-Arg-NHMec. In vitro analysis revealed that the NEJ protease activity digested sheep immunoglobulin heavy chain and bovine serum albumin but not bovine hemoglobin. Amino-terminal protein sequence analysis of the 29-kDa NEJ protease band revealed two sequences with homology to the cathepsin B family of proteases. Using degenerate oligonucleotides designed from the N-terminal sequence, reverse transcriptase polymerase chain reaction with NEJ RNA amplified a cDNA sequence encoding the first 236 amino acids of mature cathepsin B. Using this cDNA fragment an overlapping cDNA was isolated from a LambadaZAP cDNA library constructed with poly(A)+ RNA from immature 5-week-old liver fluke. Together with the N-terminal sequence, these cDNAs predict a mature cathepsin B sequence of 254 amino acids which shows 48-51% sequence identity to mammalian and Schistosoma mansoni cathepsin B. We conclude that, in contrast to the major proteases released by adult fluke, the major secreted protease of NEJ of F. hepatica is of the cathepsin B class.

Asunto(s)

Catepsina B/química , Endopeptidasas , Fasciola hepatica/enzimología , Secuencia de Aminoácidos , Animales , Catepsina B/genética , Catepsina B/metabolismo , Catepsina L , Catepsinas/metabolismo , Clonación Molecular , Cisteína Endopeptidasas , ADN Complementario/química , ADN Complementario/genética , ADN de Helmintos/química , ADN de Helmintos/genética , Electroforesis en Gel de Poliacrilamida , Fasciola hepatica/genética , Hemoglobinas/metabolismo , Concentración de Iones de Hidrógeno , Inmunoglobulinas/metabolismo , Datos de Secuencia Molecular , Reacción en Cadena de la Polimerasa , Inhibidores de Proteasas/farmacología , ARN de Helminto/genética , Ratas , Homología de Secuencia de Aminoácido , Albúmina Sérica Bovina/metabolismo , Ovinos , Especificidad por Sustrato

RESUMEN

A local field potential, consistent in form and duration, can be recorded from the olfactory lobe of crayfish following electrical stimulation of the outer flagellum of the antennule. The field potential is reversibly blocked by perfusion of the brain with low-[Ca2+] saline or -aminobutyric acid and, to a lesser extent, histamine. Paired shocks to the antennule and antidromic electrical stimulation of olfactory lobe output neurones also partially block the field potential. Comparing the field potential with simultaneously recorded intracellular responses of olfactory interneurones reveals a coincidence between excitatory and inhibitory effects in the interneurones and the appearance of identifiable components of the field potential. We interpret the field potential to reflect the response of neural elements in the olfactory lobe to orthodromic activity in the axons of the olfactory receptor neurones on the antennule. We conclude from the blocking experiments that the greater part of the field potential stems from neurones in the olfactory lobe that are postsynaptic to olfactory receptor neurones. As such, it provides a robust indication of olfactory neurone activity.

RESUMEN

Leukaemia inhibitory factor (LIF), a pleiotropic cytokine, is implicated in blastocyst implantation in mice and maintains the development of ovine embryos in culture. Previously, LIF mRNA and protein were demonstrated in the endometrium throughout the oestrous cycle and early pregnancy in the ewe. In this study pregnant ewes were passively immunised against human recombinant LIF with polyclonal antibodies raised in cows by active immunisation. Ewes were immunised during two stages of early pregnancy: blastocyst development to hatching, and blastocyst elongation to implantation. Only animals passively immunised against LIF showed detectable LIF antibodies in their sera and in uterine lumina flushings by radioimmunoassay and Western blot analysis. Pregnancy was confirmed by ultrasound on day 55 and a 33.5% non-significant decrease in pregnancy rate of anti-LIF treated animals was observed, when compared to animals in control groups (untreated or treated with bovine anti-keyhole limpet hemocyanin). Cows actively immunised with recombinant human LIF and exhibiting high levels of LIF antibodies in their sera at the time of blastocyst implantation also showed a reduced pregnancy rate in comparison to control animals. Although LIF may not be obligatory for implantation in ruminants it does appear to have a role during the establishment of pregnancy.

Asunto(s)

Inhibidores de Crecimiento/inmunología , Inmunización Pasiva/veterinaria , Interleucina-6 , Linfocinas/inmunología , Preñez/inmunología , Ovinos/inmunología , Vacunación/veterinaria , Animales , Bioensayo , Bovinos , Sincronización del Estro , Femenino , Inhibidores de Crecimiento/análisis , Inhibidores de Crecimiento/metabolismo , Humanos , Sueros Inmunes/inmunología , Radioisótopos de Yodo , Factor Inhibidor de Leucemia , Linfocinas/análisis , Linfocinas/metabolismo , Embarazo , Índice de Embarazo , Preñez/sangre , Proteínas Recombinantes/inmunología , Ovinos/sangre , Ovinos/metabolismo , Factores de Tiempo , Útero/metabolismo

RESUMEN

Leukaemia inhibitory factor (LIF), a pleiotropic cytokine, is essential for blastocyst implantation in mice and maintains the development of ovine embryos in culture. The expression of LIF was examined by northern blot analysis in endometrial tissue from cyclic (days 4-16) and pregnant (days 4-20) ewes, and the corresponding protein was immunolocalized. Expression of mRNA encoding LIF remained relatively constant throughout the oestrous cycle and was present during early pregnancy. A decrease in mRNA encoding LIF was observed during early pregnancy (on days 12-14) and expression was highest on days 16-20. Immunoreactive LIF was present in the cellular compartments of the endometrium throughout the oestrous cycle and early pregnancy, with maximal immunostaining in the caruncular and intercaruncular luminal epithelium, and moderate staining in the glandular epithelium and intercaruncular stroma. Immunoreactive LIF was also detected in the trophoblast cells of day 17 blastocysts. Separately cultured endometrial epithelial and stromal cells from pregnant animals both expressed mRNA encoding LIF. Ovariectomized steroid-treated ewes were studied to establish whether steroid hormones had a role in regulating endometrial LIF. Ewes treated with oestradiol alone showed lower concentrations of immunoreactive LIF in the endometrium in comparison to ovariectomized, control animals, while treatment of ovariectomized animals with both oestradiol and progesterone had a greater inhibitory effect on LIF immunolocalization. These studies demonstrate the presence of mRNA encoding LIF and protein throughout the oestrous cycle and early pregnancy and suggest that steroid hormones may be involved in their regulation.

Asunto(s)

Endometrio/inmunología , Estro/inmunología , Inhibidores de Crecimiento/metabolismo , Interleucina-6 , Linfocinas/metabolismo , Preñez/inmunología , Ovinos/fisiología , Animales , Northern Blotting , Estradiol/farmacología , Femenino , Inhibidores de Crecimiento/genética , Inmunohistoquímica , Factor Inhibidor de Leucemia , Linfocinas/genética , Ovariectomía , Embarazo , Progesterona/farmacología , ARN Mensajero/análisis