RESUMO
Vasoactive intestinal polypeptide (VIP)-like protein was detected by dot blot analysis in the excretions/secretions (E/S) of Nematodirus battus and Ascaridia galli and was confirmed in the E/S of Nippostrongylus brasiliensis. ELISA analysis showed that N. brasiliensis E/S contained the highest proportion of VIP-like protein (28.04 pmoles/mg of total E/S protein) and A. galli E/S contained the lowest (10.89 pmoles/mg of total E/S protein). Peptide histidine isoleucine (PHI)-like protein was detected by dot blot analysis in the E/S products of N. brasiliensis, N. battus and A. galli. ELISA analysis suggested that A. galli E/S contained the highest proportion of PHI (20.77 nmoles/mg of total E/S protein) and N. battus E/S contained the lowest (0.67 nmoles/mg of total E/S protein). The possible significance of VIP-like and PHI-like substances in the E/S of gastrointestinal nematodes is discussed.
Assuntos
Ascaridia/metabolismo , Nematoides/metabolismo , Nippostrongylus/metabolismo , Peptídeo PHI/metabolismo , Peptídeo Intestinal Vasoativo/metabolismo , Animais , Galinhas , Masculino , OvinosRESUMO
The 50-30 kDa fraction isolated from the excretory/secretory products (E/S) of the nematode Nippostrongylus brasiliensis significantly decreased the amplitude of contraction of segments of uninfected rat intestine when injected into the lumen of the segments maintained in an organ bath. Dot blot analysis of the fraction suggested that it was similar in immunoreactivity to porcine vasoactive intestinal polypeptide (VIP). When antiserum to porcine VIP was mixed with N. brasiliensis E/S and the mixtures were injected into the lumen of segments of rat intestine, the inhibitory effect of the E/S on amplitude of contraction decreased. When physiological concentrations of porcine VIP (12.9 pmol/ml) were injected into the lumen of segments of uninfected rat intestine the amplitude of contraction decreased significantly. Western blot analysis of the E/S, using antiserum to porcine VIP, recognized a 30 kDa protein in the E/S and also in whole worm homogenate suggesting that synthesis of the peptide occurs inside the nematode. Peptide histidine isoleucine (PHI)-like immunoreactivity was detected in a 68 kDa fraction of the E/S and the homogenate but this fraction did not affect the amplitude of contractions of the intestine.
Assuntos
Proteínas de Helminto/fisiologia , Intestinos , Nippostrongylus/fisiologia , Peptídeo Intestinal Vasoativo/química , Animais , Proteínas de Helminto/química , Proteínas de Helminto/metabolismo , Técnicas In Vitro , Ratos , SuínosRESUMO
Whole worm homogenates and excretory/secretory (E/S) products of adult Nippostrongylus brasiliensis significantly decreased the amplitude of contractions of segments of uninfected rat intestine maintained in an organ bath, with significantly larger volumes of E/S products being required to bring about a similar decrease to that caused by the whole worm homogenate. Boiled samples of homogenate and E/S products significantly decreased the amplitude of contractions of uninfected rat intestine, but larger volumes were needed than with unboiled samples. Frequency of contraction was unaltered by homogenates or E/S products. When electric eel AChE was injected into the lumen of segments of uninfected rat intestine maintained in an organ bath there was no significant decrease in the amplitude of contractions. These results suggest that substances present in the E/S products of N. brasiliensis significantly reduce the amplitude of contractions of uninfected rat intestine in vitro and that the biochemical holdfast responsible for this phenomenon may not be AChE.
Assuntos
Acetilcolinesterase/farmacologia , Proteínas de Helminto/farmacologia , Intestinos/efeitos dos fármacos , Nippostrongylus/metabolismo , Animais , Electrophorus , Feminino , Intestinos/fisiologia , Contração Muscular/efeitos dos fármacos , Concentração Osmolar , Ratos , Ratos WistarRESUMO
The surface of the cuticle of adult Nippostrongylus brasiliensis has been studied by means of the freeze-fracture technique and by transmission electron microscopy. Some of the surface coat appears to have been shed from the surface of the cuticle of adults fixed in situ in the intestine of its host and from the surface of individuals removed from the intestine and freeze-fractured. Freeze-fracturing the cuticle of individuals removed from the host has shown that this surface coat varies in thickness from 30 to 90 nm. The epicuticle is about 20 nm thick and cleaves readily to expose E- and P-faces. The P-face of the epicuticle possesses a small number of particles, similar to intra-membranous particles, whilst the E-face possesses a few, widely scattered depressions. Despite the presence of these particles the epicuticle is not considered to be a true membrane. Freeze-fracturing the remainder of the cuticle has confirmed its structure as described by conventional transmission electron microscopy. Clusters of particles on the P-face of the outer epidermal (hypodermal) membrane and corresponding depressions on the E-face of the membrane are though to be associated with points of attachment of the cuticle to the epidermis (hypodermis). No differences in appearance of the cuticle and its surface layers were observed in individuals taken from 7-, 10-, 13- and 15-day infections.
Assuntos
Nippostrongylus/ultraestrutura , Animais , Técnica de Fratura por Congelamento/métodos , Intestinos/parasitologia , Larva , Microscopia Eletrônica/métodos , Nippostrongylus/crescimento & desenvolvimento , Especificidade de Órgãos , Ratos , Ratos WistarRESUMO
Investigations into the enumeration, distribution and viability of nematode eggs in the sludge from a primary facultative waste stabilization pond showed that pond sludges are not nematologically safe for immediate land application. Up to 12% of Ascaris lumbricoides eggs were viable after the pond had been in operation for 2.5 years. Eggs were recovered from the sludge along the full length of the pond, although there were significant decreases in egg concentration and viability with increasing distance from the inlet.
Assuntos
Ascaris lumbricoides , Contagem de Ovos de Parasitas , Esgotos , Trichuris , Animais , Ascaris lumbricoides/fisiologia , Brasil , Trichuris/fisiologiaRESUMO
Locomotion of adult Nippostrongylus brasiliensis has been studied in saline, in 0.6% agar, in sodium alginate of different viscosities and amongst sand grains in these media. In saline the nematode formed two-dimensional waves but there was little forward progression. Amongst sand grains in saline the nematode moved forwards by thrusting against sand grains, but thigmokinetic behaviour later resulted in quiescence. In 0.6% agar and in alginates of weak viscosity the nematode produced two-dimensional waves and sometimes a three-dimensional helical wave which resulted in forward movement. The formation of three-dimensional waves and the distance travelled increased with increasing viscosity up to 4% sodium alginate and also amongst sand gains in these media. In 8% sodium alginate the nematode became coiled like a spring but remained almost stationary. The three-dimensional wave is formed with torsion and obtains thrust from the viscous medium. In the intestine of the host thrust will be obtained from the mucus and villi of the intestinal mucosa. The ability of this nematode to move by two- and three-dimensional undulatory propulsion is probably related to its complex ridged cuticle. Attention is drawn to the role that increased viscosity of mucus may play in entrapping nematodes during their immune rejection.
Assuntos
Nippostrongylus/fisiologia , Animais , Feminino , Locomoção , Microscopia Eletrônica de Varredura , Nippostrongylus/ultraestruturaRESUMO
Plasma etching has been used to strip away the cortical layers of the cuticle of adult Nippostrongylus brasiliensis to reveal the struts, with their supporting fibres, which are found in the fluid-filled middle layer of the cuticle, and the basal fibre layers. The etched specimens were studied by means of scanning electron microscopy. The results support earlier work, obtained by transmission electron microscopy, on the cuticle of this nematode. Plasma etching has been shown to have potential in studying the structure of nematodes.
Assuntos
Nippostrongylus/ultraestrutura , Animais , Feminino , Locomoção , Masculino , Microscopia Eletrônica de Varredura , Nippostrongylus/fisiologia , RatosRESUMO
Treatment of rats infected with Nippostrongylus brasiliensis with a single, oral therapeutic dose of the anthelmintic benzimidazole carbamates oxfendazole or mebendazole resulted, 24 hr later, in a marked reduction (60-90%) in the secretion of a low molecular weight acetylcholinesterase from the parasites when they were incubated in vitro. This effect coincided with the expulsion of parasites from the host as a result of the therapy. When parasites were incubated in vitro with 0.1 mM oxfendazole, mebendazole, flubendazole, parbendazole, cambendazole or thiabendazole a similar effect was observed; with oxfendazole and mebendazole the effect was apparent within 1 hr and lasted for at least 4 hr after removal to fresh, drug-free medium. Whether treated in the host or in vitro the reduction in secretion was balanced by an equivalent rise in acetylcholinesterase activity within the parasites. It is suggested that the inhibition of protein secretion may be a specific manifestation of a general effect of these compounds on microtubule function.
Assuntos
Acetilcolinesterase/metabolismo , Anti-Helmínticos/farmacologia , Benzimidazóis/farmacologia , Nippostrongylus/enzimologia , Animais , Cromatografia em Gel , Infecções por Uncinaria/enzimologia , Mebendazol/farmacologia , Nippostrongylus/efeitos dos fármacos , RatosRESUMO
Acetylcholinesterase (acetylcholine hydrolase, EC 3.1.1.7) activities of Nippostrongylus brasiliensis were measured following treatment of the hosts with oxfendazole and mebendazole. Drug treatment of N. Brasiliensis caused large, sustained increases in enzyme activity in male and female worms which coincided with the expulsion of the nematodes from the small intestine of the host. It is suggested that the increases in acetylcholinesterase activity may be due to an inhibition by the benzimidazole carbamates of the secretion of enzyme to the exterior of the worms which, in turn, leads to expulsion through failure of the so-called "chemical holdfast".
Assuntos
Acetilcolinesterase/metabolismo , Benzimidazóis/farmacologia , Carbamatos/farmacologia , Mebendazol/farmacologia , Nippostrongylus/enzimologia , Animais , Benzimidazóis/uso terapêutico , Carbamatos/uso terapêutico , Feminino , Infecções por Uncinaria/tratamento farmacológico , Masculino , Mebendazol/uso terapêutico , Nippostrongylus/efeitos dos fármacos , RatosAssuntos
Infecções por Nematoides/parasitologia , Nippostrongylus/fisiologia , Trichostrongyloidea/fisiologia , Tricostrongiloidíase/parasitologia , Animais , Feminino , Masculino , Infecções por Nematoides/imunologia , Nippostrongylus/anatomia & histologia , Fatores Sexuais , Ovinos , Fatores de Tempo , Trichostrongyloidea/anatomia & histologia , Tricostrongiloidíase/imunologiaRESUMO
Infection of rats with 2000 infective juveniles of Nippostrongylus brasiliensis and of lambs with 60 000 infective juveniles of Nematodirus battus results in a well-marked immunity to these nematodes in their respective host. There is a fall in the adenylate energy charge value of these nematodes during the course of these infections, reaching values of 0.37 in males and 0.27 in females of N. brasiliensis, and 0.31 in males and 0.23 in females of N. battus towards the end of the infections. In hosts given relatively small numbers of infective juveniles, the values for the nematodes removed from the hosts late in the infection remain at a relatively high level. These results indicate that the immune response of the host may affect the energy status of these nematodes, and this could help to explain their subsequent expulsion from the immune host.
Assuntos
Nucleotídeos de Adenina/metabolismo , Ancylostomatoidea/metabolismo , Infecções por Nematoides/imunologia , Nippostrongylus/metabolismo , Trichostrongyloidea/metabolismo , Tricostrongiloidíase/imunologia , Animais , Metabolismo Energético , Feminino , Masculino , Infecções por Nematoides/parasitologia , Ratos , OvinosAssuntos
Pele , Trichostrongyloidea/fisiologia , Animais , Esterases/análise , Histocitoquímica , Humanos , Larva/citologia , Larva/fisiologia , Lipídeos , Locomoção , Camundongos , Microscopia Eletrônica , Ratos , Pele/análise , Pele/patologia , Coloração e Rotulagem , Temperatura , Fatores de Tempo , Trichostrongyloidea/citologia , Tricostrongiloidíase/etiologia , ÁguaAssuntos
Ancylostomatoidea/análise , Infecções por Uncinaria/imunologia , Lipídeos/análise , Fatores Etários , Animais , Colesterol/análise , Cromatografia em Camada Fina , Ácidos Graxos não Esterificados/análise , Feminino , Intestinos , Masculino , Métodos , Ratos , Fatores de Tempo , Triglicerídeos/análiseRESUMO
The process of moulting and the formation of the new cuticle during the final moult of the nematode Nippostrongylus brasiliensis have been described. After separation of the hypodermis from the old cuticle, the new cuticle is secreted by the hypodermis. The first layers to be formed are the outer trilaminate membrane and the fibre layers. The struts of the cuticle separate out from the fibrillar and granular components of the outer cuticle. There is no reabsorption of the old cuticle.
RESUMO
The ultrastructure of the excretory system, including the subventral glands, of the nematode Nippostrongylus brasiliensis has been described. The walls of the lateral excretory canals contain canaliculi which open into the lumen of the canal. It is suggested that these canals play a role in osmoregulation and excretion. The sub-ventral glands contain two types of secretory granule and contain non-specific esterase, cholinesterase and aminopeptidase. It is suggested that these glands are not excretory but play an important role in feeding.