RESUMO
Background: It has been shown that dietary protein supplementation during lactation boosts immunity in Nippostrongylus brasiliensis-infected periparturient rats. It is not known whether body protein reserves accumulated during gestation have a similar effect during lactation. Objective: This study aimed to quantify the impact of body protein reserves and dietary protein supplementation on maternal performance and immune responses to N. brasiliensis during lactation. Methods: Multiparous female Sprague-Dawley rats were administered a primary infection of N. brasiliensis before mating and were restriction-fed either 60 g [low-protein diet gestation (Lge)] or 210 g [high-protein diet gestation (Hge)] crude protein (CP) per kilogram of dry matter (DM) until parturition. From parturition onward, dams were restriction-fed either 100 g [low-protein diet lactation (Lla)] or 300 g [high-protein diet lactation (Hla)] CP per kilogram of DM, generating 4 different dietary treatments. A subset of rats was sampled before parturition; postparturition, dams were secondarily infected with N. brasiliensis and samples were collected at days 5 and 11 postparturition. Results: Maternal performance until parturition, as measured by pup weight, was better in Hge rats than in Lge rats [Lge: 4.84 g; Hge: 6.15 g; standard error of the difference (SED): 0.19]. On day 11, pup weights of dams with reduced protein reserves fed protein during lactation (Lge-Hla; 20.28 g) were higher than their counterparts from Hge-Lla dams (17.88 g; SED: 0.92). Worm counts were significantly different between Lge-Lla-fed (253; 95% CI: 124, 382) and Hge-Hla-fed (87; 95% CI: 22, 104) dams on day 11 (P = 0.024). The expression of splenic interleukin 13 (Il13) and arachidonate 15-lipoxygenase (Alox15) was significantly higher (P < 0.05) in Hge-Hla dams compared with Lge-Lla dams on day 5. Conclusions: Although protein reserves were adequate to maintain maternal performance in the early stage of lactation in dams infected with N. brasiliensis, they were not adequate to maintain maternal performance and effective immune responses at later stages. Dietary protein supplementation was required to achieve this.
Assuntos
Animais Recém-Nascidos/crescimento & desenvolvimento , Proteínas Alimentares/metabolismo , Imunidade , Lactação , Fenômenos Fisiológicos da Nutrição Materna , Nippostrongylus/crescimento & desenvolvimento , Infecções por Strongylida/metabolismo , Fenômenos Fisiológicos da Nutrição Animal , Animais , Araquidonato 15-Lipoxigenase/metabolismo , Peso Corporal/efeitos dos fármacos , Dieta com Restrição de Proteínas , Proteínas Alimentares/administração & dosagem , Proteínas Alimentares/farmacologia , Suplementos Nutricionais , Feminino , Interleucina-13/metabolismo , Fenômenos Fisiológicos da Nutrição Materna/imunologia , Gravidez , Ratos Sprague-Dawley , Baço/efeitos dos fármacos , Baço/metabolismoRESUMO
As part of on-going efforts to control hookworm infection, the "human hookworm vaccine initiative" has recognised blood feeding as a feasible therapeutic target for inducing immunity against hookworm infection. To this end, molecular approaches have been used to identify candidate targets, such as Necator americanus (Na) haemoglobinase aspartic protease-1 (APR-1), with immunogenicity profiled in canine and hamster models. We sought to accelerate the immune analysis of these identified therapeutic targets by developing an appropriate mouse model. Here we demonstrate that Nippostrongylus brasiliensis (Nb), a phylogenetically distant strongylid nematode of rodents, begins blood feeding early in its development and that immunisation with Na-APR-1 can block its growth and completion of its life cycle. Furthermore, we identify a new haem detoxification pathway in Nb required for blood feeding that can be blocked by drugs of the quinolone family, reducing both infection burden and the associated anaemia in rodents. Collectively, our findings show that haem metabolism has potential as a checkpoint for interrupting hookworm development in early stages of the hookworm life cycle and that the Nippostrongylus brasiliensis rodent model is relevant for identifying novel therapeutic targets against human hookworm.
Assuntos
Anticorpos Anti-Helmínticos/farmacologia , Ácido Aspártico Endopeptidases/antagonistas & inibidores , Eritrócitos/efeitos dos fármacos , Infecções por Uncinaria/prevenção & controle , Necator americanus/enzimologia , Nippostrongylus/crescimento & desenvolvimento , Infecções por Strongylida/prevenção & controle , Ancylostomatoidea/efeitos dos fármacos , Ancylostomatoidea/crescimento & desenvolvimento , Animais , Antígenos de Helmintos/imunologia , Ácido Aspártico Endopeptidases/imunologia , Eritrócitos/parasitologia , Feminino , Infecções por Uncinaria/parasitologia , Estágios do Ciclo de Vida , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Nippostrongylus/efeitos dos fármacos , Infecções por Strongylida/parasitologiaRESUMO
Four unusual terpenylated acylphloroglucinols were isolated from the diethyl ether extract of the scales and rhizomes of the fern Dryopteris wallichiana together with the known compounds albaspidins AA and AB, and filixic acids ABA and ABB. Structures of the isolated compounds were established by extensive spectroscopic analysis and their absolute configuration at C-14â³ was determined by comparing their CD spectra with those simulated for the respective isomers. Pure acylphloroglucinols displayed moderate in vitro nematocidal activity against L4 stage larvae of Nippostrongylus brasiliensis (LD50=22-121 µM).
Assuntos
Antinematódeos/química , Antinematódeos/farmacologia , Dryopteris/química , Terpenos/química , Terpenos/farmacologia , Animais , Antinematódeos/isolamento & purificação , Estágios do Ciclo de Vida/efeitos dos fármacos , Nippostrongylus/efeitos dos fármacos , Nippostrongylus/crescimento & desenvolvimento , Terpenos/isolamento & purificaçãoRESUMO
Heat shock proteins (Hsp) are a family of stress-inducible molecular chaperones that play multiple roles in a wide variety of animals. However, the roles of Hsps in parasitic nematodes remain largely unknown. To elucidate the roles of Hsps in the survival and longevity of nematodes, particularly at the 2 most critical stages in their lifecycle, the infective-L3 stage and adult stage, which is subjected to host-derived immunological pressure, we examined the temporal gene transcription patterns of Hsp12.6, Hsp20, Hsp70, and Hsp90 throughout the developmental course of the nematode Nippostrongylus brasiliensis by reverse transcriptase real-time PCR. Nb-Hsp70 and Nb-Hsp90 expression were observed throughout the nematode's lifecycle, while the expression of Nb-Hsp20 was restricted to adults. Interestingly, Nb-Hsp12.6 showed a biphasic temporal expression pattern; i.e., it was expressed in infective-L3 larvae and in adults during worm expulsion from immunocompetent rats. However, the activation of Nb-Hsp12.6 in adult worms was aborted when they infected permissive athymic-rnu/rnu rats and was only marginal when they infected mast-cell-deficient Ws/Ws rats, which exhibited a low response of rat mast cell protease (RMCP) II and resistin-like molecule (Relm)-ß expression compared to those observed in immunocompetent rats. Moreover, the activation of Nb-Hsp12.6 was reversed when adult worms were transplanted into the naive rat intestine. These features of Nb-Hsp12.6, the expression of which is not only stage-specific in infective-L3, but is also inducible by mucosal immunity in adults, have implications for the survival strategies of parasitic nematodes in deleterious environmental conditions both outside and inside the host.
Assuntos
Envelhecimento/metabolismo , Proteínas de Choque Térmico/metabolismo , Proteínas de Helminto/metabolismo , Interações Hospedeiro-Parasita/imunologia , Imunidade/imunologia , Nippostrongylus/genética , Parasitos/genética , Actinas , Animais , Feminino , Regulação da Expressão Gênica , Proteínas de Choque Térmico/genética , Proteínas de Helminto/genética , Interações Hospedeiro-Parasita/genética , Mucosa Intestinal/parasitologia , Larva/metabolismo , Estágios do Ciclo de Vida , Masculino , Mastócitos/metabolismo , Nippostrongylus/crescimento & desenvolvimento , Ratos , Homologia de Sequência de Aminoácidos , Caracteres Sexuais , Fatores de TempoRESUMO
Developmentally arrested infective larvae of strongylid nematodes are activated to resume growth by host-derived cues encountered during invasion of the mammalian host. Exposure of Nippostrongylus brasiliensis infective larvae to elevated temperature (37°C) is sufficient to activate signalling pathways which result in resumption of feeding and protein secretion. This occurs independently of exposure to serum or glutathione, in contrast to the hookworm Ancylostoma caninum, and is not initiated by chemical exsheathment. No qualitative differences in protein secretion were induced by host serum as visualised by two-dimensional SDS-PAGE, although exposure of larvae to an aqueous extract of rat skin did stimulate secretion of a small pre-synthesised bolus of proteins. Infective larvae began feeding after a lag period of 3-4 h at 37°C, reaching a maximum of 90% of the population feeding by 48 h. Neither a membrane permeant analogue of cyclic GMP nor muscarinic acetylcholine receptor agonists stimulated feeding at 20°C, and high concentrations of both compounds inhibited temperature-induced activation. LY294002, an inhibitor of phosphatidylinositol 3-kinase, Akt inhibitor IV, an inhibitor of Akt protein kinase, and ketoconazole, an inhibitor of cytochrome P450, all blocked resumption of feeding and protein secretion at 37°C. Serotonin increased the rate of feeding assessed by uptake of radiolabelled BSA, but could not initiate feeding independently of elevated temperature. Collectively, the data suggest that the early signalling events for larval activation in N. brasiliensis differ substantially from A. caninum, but that they may converge at pathways downstream of phosphatidylinositol 3-kinase involving steroid hormone synthesis.
Assuntos
Ancylostoma/metabolismo , Ancilostomíase/parasitologia , Nippostrongylus/metabolismo , Transdução de Sinais , Infecções por Strongylida/parasitologia , Ancylostoma/genética , Ancylostoma/crescimento & desenvolvimento , Animais , Sistema Enzimático do Citocromo P-450/genética , Sistema Enzimático do Citocromo P-450/metabolismo , Proteínas de Helminto/genética , Proteínas de Helminto/metabolismo , Humanos , Masculino , Nippostrongylus/genética , Nippostrongylus/crescimento & desenvolvimento , Fosfatidilinositol 3-Quinase/genética , Fosfatidilinositol 3-Quinase/metabolismo , Proteínas Proto-Oncogênicas c-akt/genética , Proteínas Proto-Oncogênicas c-akt/metabolismo , Ratos , Ratos Sprague-DawleyRESUMO
The C-type lectin superfamily is highly represented in all metazoan phyla so far studied. Many members of this superfamily are important in innate immune defences against infection, while others serve key developmental and structural roles. Within the superfamily, many proteins contain multiple canonical carbohydrate-recognition domains (CRDs), together with additional non-lectin domains. In this report, we have studied two gastrointestinal nematode parasites which are widely used in experimental rodent systems, Heligmosomoides polygyrus and Nippostrongylus brasiliensis. From cDNA libraries, we have isolated 3 new C-type lectins from these species; all are single-CRD proteins with short additional N-terminal domains. The predicted Hp-CTL-1 protein contains 156 aa, Nb-CTL-1 191 aa and Nb-CTL-2 183 aa; all encode predicted signal peptides, as well as key conserved sequence motifs characteristic of the CTL superfamily. These lectins are most similar to C. elegans CLEC-48, 49 and 50, as well as to the lectin domains of mammalian immune system proteins CD23 and CD206. RT-PCR showed that these H. polygyrus and N. brasiliensis genes are primarily expressed in the gut-dwelling adult stages, although Nb-CTL-2 transcripts are also prominent in the free-living infective larval (L3) stage. Polyclonal antibodies raised to Hp-CTL-1 and Nb-CTL-1 reacted to both proteins by ELISA, and in Western blot analysis recognised a 15-kDa band in secreted proteins of adult N. brasiliensis (NES) and a 19-kDa band in H. polygyrus ES (HES). Anti-CTL-1 antibody also bound strongly to the cuticle of adult H. polygyrus. Hence, live parasites release C-type lectins homologous to some key receptors of the mammalian host immune system, raising the possibility that these products interfere in some manner with immunological recognition or effector function.
Assuntos
Duodeno/parasitologia , Lectinas Tipo C/metabolismo , Nematospiroides dubius/crescimento & desenvolvimento , Nippostrongylus/crescimento & desenvolvimento , Animais , Biblioteca Gênica , Interações Hospedeiro-Parasita , Larva/metabolismo , Lectinas Tipo C/genética , Estágios do Ciclo de Vida , Camundongos , Dados de Sequência Molecular , Nematospiroides dubius/genética , Nematospiroides dubius/metabolismo , Nippostrongylus/genética , Nippostrongylus/metabolismo , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Análise de Sequência de DNARESUMO
Reduced paraoxonase-1 (PON1) activity has been observed in a number of pathological conditions; however, little is known about the effects of intestinal nematode infections, such as Nippostrongylus brasiliensis, on paraoxonase activity. We observed a significant reduction in serum paraoxonase and arylesterase activity after N. brasiliensis infection in Wistar rats from Day 6 until Day 12 post-infection (p.i.) for serum paraoxonase and from Day 3 until Day 24 p.i. for arylesterase. In addition, N. brasiliensis infection increased serum concentrations of pro-inflammatory cytokines (interleukin-1, interleukin-6, and tumor necrosis factor-alpha), with maximum concentrations observed on Day 9 p.i. These cytokines are known to inhibit the synthesis of hepatic PON1 mRNA. Thus, the observed reduction in PON1 activity during N. brasiliensis infection is likely associated with inflammatory reactions mounted against the parasites.
Assuntos
Arildialquilfosfatase/sangue , Infecções por Strongylida/sangue , Animais , Hidrolases de Éster Carboxílico/sangue , Citocinas/sangue , Fezes/parasitologia , Feminino , Inflamação/sangue , Inflamação/parasitologia , Larva , Masculino , Nippostrongylus/crescimento & desenvolvimento , Oviposição , Ratos , Ratos WistarRESUMO
Female and male worms of Nippostrongylus brasiliensis exhibited sexual dimorphism based on the number of coelomocytes present. A surprising multiplicity of diverse morphological types of coelomocytes developed in both female and male worms during the parasitic cycle. Cytoplasmic processes began to appear on the surface membrane of coelomocytes in the late third-stage larvae (L3s) in the lungs, and they increased greatly in type, size, and morphology during the fourth and fifth stages. These structures were characterized primarily as complex filopodia, pseudopodia, and cytoplasmic pearls, which resulted in the formation of highly pleomorphic cells. Pearls, starting as small protuberances, progressively increased in size and number with larval growth and development. In the adult worms, a novel process of autocannibalism was initiated in many of the very large coelomocytes. The pearls grew enormously in size at the expense of the cytoplasm, forming a peripheral garland in 1 plane surrounding a residual, small, flat, cytoplasmic core containing the nucleus. The underlying "strategy" was to increase the surface-to-volume ratio of these huge cells to overcome the restriction imposed by eutely; the coelomocytes do not undergo cell division. This morphological innovation makes possible a more efficient uptake of nutrients and exocytosis of waste matter. Vesicles (presumably lysosomes) in the coelomocytes of the infective L3 store an extraordinarily high concentration of vitamin B12 (cobalamin, Cbl). At present, the only physiological function that can be assigned to coelomocytes of N. brasiliensis is the uptake, concentration, and storage of Cbl in the free-living stages, with the subsequent release of the molecule from the vesicles in the early phase of parasitism. Thus, stored Cbl in the infective L3 is made available for biochemical processes during the critical period of larval growth and differentiation initiated in the lung. A model of a hypothetical coelomocyte is presented relative to the processing and use of Cbl. Based on many criteria, it is possible that functional differences exist between different morphological types of coelomocytes in the parasitic stages of N. brasiliensis and that future studies will have to address this matter.
Assuntos
Estágios do Ciclo de Vida , Nippostrongylus/citologia , Nippostrongylus/crescimento & desenvolvimento , Infecções por Strongylida/parasitologia , Animais , Feminino , Intestinos/parasitologia , Larva/citologia , Larva/fisiologia , Estágios do Ciclo de Vida/fisiologia , Pulmão/parasitologia , Masculino , Nippostrongylus/fisiologia , Ratos , Ratos Sprague-Dawley , Caracteres Sexuais , Maturidade Sexual , Fatores de TempoRESUMO
Spigelia anthelmia Linn is used as a herb and is a common annual weed of cultivation in open re-growths, on unused land in towns as well as on road sides. The plant can grow to approximately 30 cm in height. The aim of this study was to screen extracts of Spigelia anthelmia for their anthelmintic activity against an experimental Nippostrongylus braziliensis infection in rats. Acute oral toxicity occurred at a dose of 1,140 mg/kg, while anthelmintic trials against Nippostrongylus braziliensis in rats using the aqueous fraction showed a progressive decrease in worm count with increasing dose (10, 13, 16, 20 and 25 mg per kg body weight) (p < 0.05). At 25 mg per kg body weight, the worm count was significantly lower than that at 10 mg per kg body weight (p < 0.05).
Assuntos
Anti-Helmínticos/farmacologia , Loganiaceae/química , Nippostrongylus/crescimento & desenvolvimento , Fitoterapia/métodos , Extratos Vegetais/farmacologia , Infecções por Strongylida/tratamento farmacológico , Animais , Anti-Helmínticos/toxicidade , Avaliação Pré-Clínica de Medicamentos , Dose Letal Mediana , Medicinas Tradicionais Africanas , Nigéria , Extratos Vegetais/toxicidade , Ratos , Ratos Wistar , Infecções por Strongylida/parasitologiaRESUMO
It has been reported that excretory-secretory (ES) material from the parasitic nematode Nippostrongylus brasiliensis has potential modulatory effects on the host's immune system. We observed that intratracheal instillation of ES from the L3 stage of the parasite reduced neutrophil numbers in LPS-induced inflammation as assessed by bronchoalveolar lavage.
Assuntos
Neutrófilos/imunologia , Nippostrongylus/imunologia , Nippostrongylus/patogenicidade , Animais , Antígenos de Helmintos/administração & dosagem , Feminino , Interações Hospedeiro-Parasita/imunologia , Inflamação/etiologia , Inflamação/prevenção & controle , Lipopolissacarídeos/administração & dosagem , Pulmão/imunologia , Nippostrongylus/crescimento & desenvolvimento , Ratos , Ratos Wistar , Infecções por Strongylida/imunologiaRESUMO
The interleukin (IL)-13-mediated goblet cell response is the major host effector system involved in the expulsion of Nippostrongylus brasiliensis. Lactic dehydrogenase virus (LDV) induced higher levels of N. brasiliensis egg production compared with controls, but the effect of LDV infection on worm expulsion of, and goblet cell and IL-13 responses to, N. brasiliensis have not been studied. In this study, the effects of LDV infection on these host responses against N. brasiliensis were examined. Mice with chronic LDV infection showed significantly lower worm expulsion rates than non-LDV-infected mice after N. brasiliensis infection, and there were no significant differences in the ratio of female versus male adult worms between control and LDV-infected mice. The number of goblet cells in LDV-infected mice was significantly lower than that in controls. In addition, the levels of IL-13 gene expression in lymph nodes were significantly lower in LDV-infected mice compared with controls. These results suggest that LDV infection reduces the protective immune responses against N. brasiliensis infection by the suppression of IL-13 production.
Assuntos
Infecções por Arterivirus/complicações , Vírus Elevador do Lactato Desidrogenase , Nippostrongylus , Infecções por Strongylida/imunologia , Animais , Feminino , Células Caliciformes/citologia , Interleucina-13/análise , Intestino Delgado/parasitologia , Pulmão/parasitologia , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Nippostrongylus/genética , Nippostrongylus/crescimento & desenvolvimento , Nippostrongylus/isolamento & purificação , Ratos , Ratos Sprague-Dawley , Infecções por Strongylida/complicações , Infecções por Strongylida/parasitologiaRESUMO
Migration of L3 larvae of Nippostrongylus brasiliensis through the lungs of the rat, during primary infection, was studied at 24 h, 72 h and 8 days. At 24 h p.i., there was evidence of damage to lung epithelial cells and microvasculature, with increased protein and gamma-glutamyl transpeptidase in the bronchoalveolar lavage (BAL) fluid. However, there was little evidence of inflammatory cell recruitment. At 24 h p.i., there was a significant reduction in the inflammatory cytokine tumour necrosis factor alpha. Superoxide (O2-*) production was also reduced, accompanied by an increase in superoxide dismutase activity. Lipid peroxidation was reduced at 24 h p.i. and L3 larvae were shown to possess high levels of glutathione compared to host lung tissue. Nitric oxide, detected as nitrite, was produced in BAL fluid, and inducible nitric oxide synthase protein was increased by 72 h p.i. There was evidence of peroxynitrite production throughout the infection period with specific protein bands nitrosylated at 75, 30 and 25 kDa. It appears that despite early evidence of lung damage, the inflammation was reduced in response to L3 larvae of N. brasiliensis.
Assuntos
Nippostrongylus/patogenicidade , Óxido Nítrico/metabolismo , Estresse Oxidativo , Pneumonia/fisiopatologia , Infecções por Strongylida/fisiopatologia , Animais , Líquido da Lavagem Broncoalveolar/citologia , Líquido da Lavagem Broncoalveolar/imunologia , Feminino , Pulmão/parasitologia , Pulmão/patologia , Masculino , Nippostrongylus/crescimento & desenvolvimento , Nippostrongylus/fisiologia , Pneumonia/imunologia , Pneumonia/parasitologia , Pneumonia/patologia , Ratos , Ratos Wistar , Infecções por Strongylida/imunologia , Infecções por Strongylida/parasitologia , Infecções por Strongylida/patologiaRESUMO
By using IL-5 transgenic mice, it has been shown that eosinophils might play a key role in elimination of larval stages of nematode infections. The present study was carried out to clarify molecular mechanisms involved in the eosinophil-mediated killing of Nippostrongylus brasiliensis larvae. The larvicidal activity was observed in the presence of normal serum in vitro. Electron microscopic observations revealed firm attachment of eosinophils to the cuticular surface of larvae, which was damaged by electron-dense materials released from eosinophils. The larvicidal activity was abrogated by heat- or zymosan-treatment of the serum, whereas depletion of IgG or IgM from the serum did not interfere with eosinophil adhesion and killing. Moreover, pretreatment of eosinophils with monoclonal antibodies against CD11b or VLA-4 inhibited the eosinophil-mediated killing of larvae. Immunofluorescent staining demonstrated the deposition of C3c and plasma fibronectin on the cuticle of the larvae. These results indicate that interactions between CD11b and VLA-4 and their respective counter-ligands deposited on the cuticle are essential in eosinophil-mediated adhesion and damage to larvae of N. brasiliensis.
Assuntos
Proteínas do Sistema Complemento/fisiologia , Eosinófilos/imunologia , Fibronectinas/metabolismo , Nippostrongylus/imunologia , Infecções por Strongylida/imunologia , Animais , Adesão Celular , Integrina alfa4beta1 , Integrinas/metabolismo , Interleucina-5/genética , Larva/imunologia , Antígeno de Macrófago 1/metabolismo , Camundongos , Camundongos Endogâmicos C3H , Camundongos Transgênicos , Nippostrongylus/crescimento & desenvolvimento , Receptores de Retorno de Linfócitos/metabolismo , Infecções por Strongylida/parasitologiaRESUMO
Rats were immunized through an initial infection with 1,000 filariform larvae (L3) of Nippostrongylus brasiliensis and after complete expulsion of worms they were challenged with 1,000 L3 of Strongyloides venezuelensis to investigate whether cross-resistance developed against a heterologous parasite. Nippostrongylus brasiliensis-immunized rats developed a partial cross-resistance against S. venezuelensis migrating larvae (MSL3) in the lungs and adult worms in the small intestine. The population of MSL3 in the lungs were significantly lower (P < 0.05) in immunized rats (22.0 +/- 7.4) compared with controls (105.0 +/- 27.6). The populations of adult worms, egg output and fecundity were initially decreased but from day 14 post-challenge they did not show any significant difference between immunized and control rats. However, the length of worm in immunized rat was revealed as retardation. Peripheral blood eosinophilia was significantly decreased (P < 0.05) on day 7 post-challenge and then gradually increased, which peaked on day 42 post-challenge when most of the worms were expelled. These results suggest that peripheral blood eosinophilia is strongly involved in the worm establishment and expulsion mechanisms.
Assuntos
Nippostrongylus/imunologia , Infecções por Strongylida/imunologia , Strongyloides/imunologia , Estrongiloidíase/imunologia , Animais , Eosinófilos/imunologia , Larva/imunologia , Contagem de Leucócitos , Masculino , Nippostrongylus/crescimento & desenvolvimento , Ratos , Ratos Endogâmicos F344 , Strongyloides/crescimento & desenvolvimentoRESUMO
With the use of observations on living and fixed and stained larvae of Nippostrongylus brasiliensis reared in charcoal-feces cultures, an integrated view is presented on the morphology and differentiation of the coelomocytes present in the body cavity of the 2 rhabditiform stages and the exsheathed third stage. Four coelomocytes are present in the newly hatched larva arranged linearly from the base of the esophagus to the genital primordium. They lie subventrally, the anterior 2 on the right side of the ventral nerve cord, the posterior 2 on the left side. Data on the growth of these cells and analysis of their fixed site location in the coelom are presented. The coelomocytes are firmly attached to the inner surface of the body wall by filopodia. However, aberrantly positioned coelomocytes suggest the possibility that detachment and migration may occur. A few minute cytoplasmic inclusions are present in the coelomocytes in living newly hatched larvae and may reach approximately 100 or more in each coelomocyte in the third stage. These inclusions exhibit 2 phases of a pigmentation process. They are colorless in the rhabditiform stages, but simultaneous with the initiation of the second molt to form the infective larva, the inclusions rapidly turn a pink to rose hue. A variety of previous experimental data strongly support the interpretation that the pigment represents an extraordinary concentration of vitamin B12 in the coelomocytes obtained by larval feeding on bacterial B12 synthesizers present in the charcoal-feces cultures.
Assuntos
Nippostrongylus/citologia , Animais , Diferenciação Celular , Larva/citologia , Nippostrongylus/crescimento & desenvolvimento , Pigmentação/fisiologiaRESUMO
Norepinephrine, 5-hydroxytryptophan, octopamine, dihydroxyphenylacetic acid, N-acetyldopamine, dopamine, 5-hydroxyindoleacetic acid, N-acetylserotonin, tyramine, tryptophan and serotonin in larvae (third free stage and parasitic stages) and adult males and females (at defined ages during the intestinal phase) of the parasitic nematode Nippostrongylus brasiliensis were quantified simultaneously by high-performance liquid chromatography with electrochemical detection. Biogenic amine levels depended on the stage, the age and the sex of parasites and on environmental conditions. Their physiological roles in reproductively competent adults of this nematode are discussed in relation to exuviation and egg laying. Parallel fluctuations in free ecdysteroids and norepinephrine were observed in females from the same worm populations.
Assuntos
Monoaminas Biogênicas/metabolismo , Nippostrongylus/metabolismo , Ácido 3,4-Di-Hidroxifenilacético/metabolismo , 5-Hidroxitriptofano/metabolismo , Animais , Dopamina/análogos & derivados , Dopamina/metabolismo , Ecdisteroides , Feminino , Ácido Hidroxi-Indolacético/metabolismo , Hormônios de Inseto/metabolismo , Larva/metabolismo , Masculino , Nippostrongylus/crescimento & desenvolvimento , Nippostrongylus/patogenicidade , Norepinefrina/metabolismo , Octopamina/metabolismo , Ratos , Ratos Wistar , Serotonina/análogos & derivados , Serotonina/metabolismo , Caracteres Sexuais , Esteroides/metabolismo , Triptofano/metabolismo , Tiramina/metabolismoRESUMO
The synthesis of a series of 2-amino-4-hydroxy-delta-valerolactam derivatives is described (compounds 4 to 10). These compounds showed a high anthelmintic in vitro activity against the Nippostrongylus brasiliensis model.
Assuntos
Anti-Helmínticos/síntese química , Nippostrongylus/efeitos dos fármacos , Piperidonas/síntese química , Infecções por Strongylida/parasitologia , Animais , Anti-Helmínticos/farmacologia , Cristalografia por Raios X , Masculino , Conformação Molecular , Nippostrongylus/crescimento & desenvolvimento , Piperidonas/farmacologia , Ratos , Ratos Wistar , Infecções por Strongylida/tratamento farmacológico , Relação Estrutura-AtividadeRESUMO
Bacteria in rat feces cultures that had synthesized vitamin B12 were ingested by the free-living stages of Nippostrongylus brasiliensis and the vitamin was concentrated and stored in the third-stage infective filariform larvae. As assayed with Ochromonas malhamensis, the vitamin B12 content of a single filariform larva as well as the concentration expressed as microgram B12 per g filariform larvae reached extraordinarily high levels, the latter being the highest yet recorded for a metazoan organism. The stored B12 content of the filariforms surviving in fecal culture for as long as 104 days remained constant, whereas the B12 concentration rose due to gradual loss of larval body weight. This storage strategy ensured that a high level of the vitamin would be immediately available to the rapidly growing and differentiating worms following infection of the rat. The changing patterns of B12 content and concentration during the parasitic cycle were followed quantitatively and correlated with B12 turnover, increase in worm weight with growth, and incorporation of B12 into the eggs. The possible sources of B12 and its metabolic functions in nematodes are discussed.
Assuntos
Fezes/parasitologia , Nippostrongylus/metabolismo , Infecções por Strongylida/parasitologia , Vitamina B 12/metabolismo , Animais , Feminino , Intestino Delgado/parasitologia , Larva/crescimento & desenvolvimento , Larva/metabolismo , Pulmão/parasitologia , Masculino , Nippostrongylus/crescimento & desenvolvimento , Ratos , Ratos Sprague-DawleyRESUMO
The globins of the nematode parasite Nippostrongylus brasiliensis have oxygen affinities 100-fold higher than the rodent host's haemoglobins. Two isoforms are found, one located in the cuticle, and the other in the body of the nematode. Both isoforms have been cloned and analysed for clues as to function and evolution. The body globin isoform is first expressed upon invasion of the mammalian host. The abundant cuticular globin is expressed only by adult nematodes in the gut, and differs significantly from the body globin. Both globins are found as trans-spliced mRNAs: the developmental pattern of expression of the mRNA parallels the protein expression. The pattern of the nematode globin genes is complex. Comparison with other nematode globin sequences suggests that N. brasiliensis is more closely related to Caenorhabditis elegans than to ascarid species. At least two gene duplication events are predicted: gene duplication preceded the radiation of the important vertebrate-parasitic strongylid nematode species. Both N. brasiliensis globins have a central intron the exact position of which suggests that it arose from an independent insertion event in the strongylid-rhabditid line. The globins have been expressed in Escherichia coli as functional holenzymes as a prelude to studies to elucidate the origin of their extraordinary oxygen affinity.
Assuntos
Globinas/genética , Nippostrongylus/genética , Sequência de Aminoácidos , Animais , Sequência de Bases , Evolução Biológica , DNA Complementar/genética , DNA de Helmintos/genética , Escherichia coli/genética , Regulação da Expressão Gênica no Desenvolvimento , Genes de Helmintos , Globinas/química , Globinas/isolamento & purificação , Íntrons , Dados de Sequência Molecular , Nematoides/genética , Nippostrongylus/química , Nippostrongylus/crescimento & desenvolvimento , Oxigênio/química , Conformação Proteica , RNA de Helmintos/genética , RNA de Helmintos/metabolismo , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Homologia de Sequência de AminoácidosRESUMO
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.