An Animal Able To Tolerate D2 O.

It is possible to gain a deeper insight into the role of water in biology by using physicochemical variant molecules, such as deuterium oxide (D2 O); however, D2 O is toxic to multicellular organisms in high concentrations. By using a unique desiccation-rehydration process, we demonstrate that the anhydrobiotic nematode Panagrolaimus superbus is able to tolerate and proliferate in 99 % D2 O. Moreover, we analysed P. superbus' water-channel protein (aquaporin; AQP), which is associated with dehydration/rehydration, by comparing its primary structure and modelling its tertiary structure in silico. Our data evidence that P. superbus' AQP is an aquaglyceroporin, a class of water channel known to display a wider pore; this helps to explain the rapid and successful organismal influx of D2 O into this species. This is the first demonstration of an animal able to withstand high D2 O levels, thus paving a way for the investigation of the effects D2 O on higher levels of biological organization.

Abundancia, diversidad y huella metabólica de comunidades de nematodos en diferentes zonas de vida en la Región Huetar Norte de Costa Rica / Abundance, diversity and metabolic footprint of nematode communities in different life zones in the Region Huetar Norte from Costa Rica

Resumen El estudio de las comunidades bióticas que habitan el suelo y que representan un 25 % de la diversidad existente, es importante para su conservación y aprovechamiento sostenible. Entre la biota edáfica los nematodos se consideran de importancia ecológica como indicadores ambientales. Herramientas como los índices de madurez, los índices de la red trófica y las huellas metabólicas, basadas en la comunidad de nematodos, son utilizadas para evaluar la condición del ecosistema con relación al impacto de contaminantes y otros factores estresantes en los ecosistemas. Los cambios en la estructura y funcionamiento de las redes tróficas del suelo y más recientemente el efecto de los factores climáticos, también tienen impacto en la comunidad nematológica. Costa Rica es un país tropical donde se pueden encontrar gran variedad de microclimas en un área pequeña, esta característica se ve reflejada en las diferentes zonas de vida descritas por Holdridge para el territorio nacional, las cuales difieren en sus patrones de precipitación, temperatura y evapotranspiración. En esta investigación, se aprovechó la diversidad de climas para contribuir con el conocimiento de las comunidades de nematodos de varios ecosistemas en diferentes zonas de vida. Para esto se recolectaron muestras en distintas zonas de vida en la Región Huetar Norte de Costa Rica. Los nematodos presentes en las muestras fueron extraídos e identificados a nivel de familia o género, y con los datos obtenidos se calcularon índices de diversidad, de madurez, de la red trófica y huellas metabólicas. Se obtuvo una gran variación en la abundancia de taxa entre los diferentes tipos de manejo dentro de los ecosistemas; sin embargo, la baja disponibilidad de repeticiones para analizar estadísticamente de manera precisa, hizo que las estimaciones de una media fueran indemostrables numéricamente. No fue posible establecer diferencias significativas entre los ecosistemas con diferentes tipos de manejo respecto a las variables calculadas, lo que se atribuye a la variabilidad de los datos. En cuanto a las zonas de vida, los índices de madurez y de la red trófica no mostraron diferencias entre las mismas, mientras que las huellas metabólicas, así como la biomasa de nematodos se correlacionaron positivamente con éstas. En el bosque húmedo montano bajo, la zona con menor temperatura media anual, la huella metabólica fue mayor, luego la huella metabólica disminuyó en las diferentes zonas de vida en correspondencia con el aumento de la temperatura media anual reportada para cada una. Las huellas metabólicas relacionadas con la descomposición de la materia orgánica del suelo (fungívoros, bacterívoros y enriquecimiento) manifestaron correlaciones altamente significativas. Se plantea que el aumento de las huellas metabólicas conforme disminuye la temperatura evidencia un cambio en la dinámica de la descomposición química y biológica de la materia orgánica del suelo y en el flujo de energía de la red trófica. En otros estudios también se ha concluido que la temperatura es un factor determinante en la distribución de las especies en ecosistemas edáficos, y por lo tanto debería ser objeto de mayor investigación.(AU)

Abstract Soil biotic communities represent 25 % of the existing global diversity, therefore their study is important for their conservation and sustainable use. Among edaphic biota, nematodes are considered ecologically important as environmental indicators. Tools like the maturity indexes, food web diagnostics and metabolic footprints are used in assessing the ecosystem in relation to the impact contaminants and other stressors, as well as monitoring and measuring changes in the structure and dynamics of the food webs and, more recently, to study the impact of climate factors on the nematode community. Costa Rica is a tropical country with a variety of miroclimates in a small area; this attribute is reflected in the different life zones described by Holdridge for Costa Rica, which differ in their patterns of precipitation, temperature and evapotranspiration. In this research, the diversity of climates was exploited in order to contribute with the knowledge of the nematode communities of several ecosystems within different life zones. For this purpose, samples were taken in several ecosystems located in different life zones in the Region Huetar Norte from Costa Rica. High variation in taxa abundance between different management types within ecosystems was obtained. However, the low availability of replicates for proper statistical analyzes made the mean estimations numerically unprovable. The maturity indexes and the food web diagnosis did not show statistical differences between the studied zones, while, the metabolic footprints were positively correlated to life zones. The metabolic footprint decreased in the different life zones in correspondence with the increase of the average annual temperature reported for each one. The metabolic footprints associated with the decomposition of organic matter (fungivores, bacterivores, and enrichment) had the strongest correlations. The proposition is that the increase in metabolic footprints while the temperature decreases, reflects a change in the dynamics of chemical and biological decomposition of organic matter and in the energy flow in the food networks. This research supports finding in other studies, suggesting that the temperature is a key factor in the species distribution in edaphic ecosystems, and therefore it should be subject to further investigation.(AU)

Earthworms and root-knot nematodes: effect on soil biological activity and tomato growth / Minhocas e nematoides das galhas: efeitos na atividade biológica do solo e crescimento do tomate

Earthworms are a representative soil invertebrate, and their living habits are known to influence a large diversity of organisms. The objective of this study was to evaluate the ability of Amynthas spp. to change the biological attributes of soil, and its potential to reduce infection by root-knot nematodes on tomato crop. The study was conducted in the greenhouse of the Diagnostic Center Marcos Enrietti, Federal University of Paraná, Brazil. The treatments earthworms at the following densities: control (absence of earthworms), two, four, six, and eight, which were inoculated into different pots, with five replicates per group. In each pot, a single tomato plant (Solanum lycopersicum) was used, and a suspension of Meloidogyne javanica containing 3000 eggs and/or juveniles was added 14 days after seeding. During the experiment, edaphic respiration was evaluated at 96-h intervals. After 91 days, soil microbial biomass carbon (MBC), microbial soil respiration (MSR), the metabolic quotient (qCO2), dry mass of roots (DMR), dry mass of plants (DMP), and the number of root galls were determined per plant. We observed that inoculation with higher earthworm densities increased the MBC. Furthermore, the lowest earthworm density (two animals) resulted in a MBC that was 75% higher than that of the control treatment (earthworms absent). There was a positive correlation between MBC and DMP, anda negative correlation between MBC and qCO2. The DMR was not influenced by inoculation withearthworms. A linear increase in DMP was observed with earthworms; however, gall formations on thetomato root were not suppressed.(AU)

As minhocas são um dos mais representativos invertebrados do solo e sabe-se que seus hábitos de vida influenciam uma grande diversidade de outros organismos. O objetivo deste estudo foi avaliar a capacidade de Amynthas spp. em alterar alguns atributos biológicos do solo e seu potencial em reduzir a infecção de nematoides formadores de galhas na cultura do tomate. O estudo foi conduzido em casa de vegetação no Centro Diagnóstico Marcos Enrietti, Universidade Federal do Paraná, Brasil. Os tratamentos foram diferentes densidades de minhocas: Controle (ausência de minhocas), dois, quatro, seis e oito indivíduos inoculados por vaso, com cinco repetições. Em cada vaso foi utilizada uma única plântula de tomate (Solanum lycopersicum), onde, aos 14 dias após a semeadura foi adicionada uma suspensão contendo 3000 ovos e/ou juvenis de Meloidogyne javanica. Durante o experimento, a respiração edáfica foi avaliada em intervalos de 96 horas. Após 91 dias, o carbono da biomassa microbiana (MBC), respiração microbiana (MSR), quociente metabólico (qCO2), massa seca das raízes (DMR), massa seca da planta (DMP) e o número de galhas por planta foram determinados. Como resultados, observou-se que a inoculação de altas densidades de minhocas aumentou o MBC. Além disso, baixas densidades de minhocas (dois indivíduos) mostraram valores de MBC 75% maiores, comparados ao tratamento controle (ausência de minhocas). Houve uma correlação positiva entre MBCe DMP, negativa entre MBC e qCO2. A DMR não foi influenciada pela inoculação de minhocas. Umaumento linear da DMP foi observado com o aumento da densidade de minhocas, sem ocorrer supressãoda formação de galhas nas raízes.(AU)

Earthworms and root-knot nematodes: effect on soil biological activity and tomato growth / Minhocas e nematoides das galhas: efeitos na atividade biológica do solo e crescimento do tomate

Earthworms are a representative soil invertebrate, and their living habits are known to influence a large diversity of organisms. The objective of this study was to evaluate the ability of Amynthas spp. to change the biological attributes of soil, and its potential to reduce infection by root-knot nematodes on tomato crop. The study was conducted in the greenhouse of the Diagnostic Center Marcos Enrietti, Federal University of Paraná, Brazil. The treatments earthworms at the following densities: control (absence of earthworms), two, four, six, and eight, which were inoculated into different pots, with five replicates per group. In each pot, a single tomato plant (Solanum lycopersicum) was used, and a suspension of Meloidogyne javanica containing 3000 eggs and/or juveniles was added 14 days after seeding. During the experiment, edaphic respiration was evaluated at 96-h intervals. After 91 days, soil microbial biomass carbon (MBC), microbial soil respiration (MSR), the metabolic quotient (qCO2), dry mass of roots (DMR), dry mass of plants (DMP), and the number of root galls were determined per plant. We observed that inoculation with higher earthworm densities increased the MBC. Furthermore, the lowest earthworm density (two animals) resulted in a MBC that was 75% higher than that of the control treatment (earthworms absent). There was a positive correlation between MBC and DMP, anda negative correlation between MBC and qCO2. The DMR was not influenced by inoculation withearthworms. A linear increase in DMP was observed with earthworms; however, gall formations on thetomato root were not suppressed.

As minhocas são um dos mais representativos invertebrados do solo e sabe-se que seus hábitos de vida influenciam uma grande diversidade de outros organismos. O objetivo deste estudo foi avaliar a capacidade de Amynthas spp. em alterar alguns atributos biológicos do solo e seu potencial em reduzir a infecção de nematoides formadores de galhas na cultura do tomate. O estudo foi conduzido em casa de vegetação no Centro Diagnóstico Marcos Enrietti, Universidade Federal do Paraná, Brasil. Os tratamentos foram diferentes densidades de minhocas: Controle (ausência de minhocas), dois, quatro, seis e oito indivíduos inoculados por vaso, com cinco repetições. Em cada vaso foi utilizada uma única plântula de tomate (Solanum lycopersicum), onde, aos 14 dias após a semeadura foi adicionada uma suspensão contendo 3000 ovos e/ou juvenis de Meloidogyne javanica. Durante o experimento, a respiração edáfica foi avaliada em intervalos de 96 horas. Após 91 dias, o carbono da biomassa microbiana (MBC), respiração microbiana (MSR), quociente metabólico (qCO2), massa seca das raízes (DMR), massa seca da planta (DMP) e o número de galhas por planta foram determinados. Como resultados, observou-se que a inoculação de altas densidades de minhocas aumentou o MBC. Além disso, baixas densidades de minhocas (dois indivíduos) mostraram valores de MBC 75% maiores, comparados ao tratamento controle (ausência de minhocas). Houve uma correlação positiva entre MBCe DMP, negativa entre MBC e qCO2. A DMR não foi influenciada pela inoculação de minhocas. Umaumento linear da DMP foi observado com o aumento da densidade de minhocas, sem ocorrer supressãoda formação de galhas nas raízes.

Proteolytic action of the crude extract of Duddingtonia flagrans on cyathostomins (Nematoda: Cyathostominae) in coprocultures.

The objective of this study was to examine the action of the crude extract of Duddingtonia flagrans (isolates AC001 and CG722) on infective larvae (L3) of cyathostomins in coprocultures and to confirm its proteolytic activity by means of a zymogram. The following groups were formed in coprocultures: Group 1: 10 mL of crude extract of D. flagrans (AC001); group 2: 10 mL of crude extract of AC001 with 10 mM of Ca2+; group 3: 10 mL of crude extract of D. flagrans (CG722); group 4: 10 mL of crude extract of CG722 with 10 mM of Ca2+; and group 5: control group (distilled water). The third-stage larvae (L3) were obtained after eight days. The crude extract of D. flagrans was effective in reducing the number of L3, with the following percentage reductions: group 1, 49.5%; group 2, 52.5%; group 3, 36.8%; and group 4, 57.7%; in relation to the control group (p > 0.05). The proteolytic activity of the crude extract was confirmed through the zymogram. The results from this study confirmed that the crude extract of the fungus D. flagrans could be used for controlling cyathostomin L3, and suggested that at least one protease of approximately 38 kDa was present.

Proteolytic action of the crude extract of Duddingtonia flagrans on cyathostomins (Nematoda: Cyathostominae) in coprocultures / Ação proteolítica do extrato bruto de Duddingtonia flagrans sobre ciatostomíneos (Nematoda: Cyathostominae) em coproculturas

The objective of this study was to examine the action of the crude extract of Duddingtonia flagrans (isolates AC001 and CG722) on infective larvae (L3) of cyathostomins in coprocultures and to confirm its proteolytic activity by means of a zymogram. The following groups were formed in coprocultures: Group 1: 10 mL of crude extract of D. flagrans (AC001); group 2: 10 mL of crude extract of AC001 with 10 mM of Ca2+; group 3: 10 mL of crude extract of D. flagrans (CG722); group 4: 10 mL of crude extract of CG722 with 10 mM of Ca2+; and group 5: control group (distilled water). The third-stage larvae (L3) were obtained after eight days. The crude extract of D. flagrans was effective in reducing the number of L3, with the following percentage reductions: group 1, 49.5%; group 2, 52.5%; group 3, 36.8%; and group 4, 57.7%; in relation to the control group (p > 0.05). The proteolytic activity of the crude extract was confirmed through the zymogram. The results from this study confirmed that the crude extract of the fungus D. flagrans could be used for controlling cyathostomin L3, and suggested that at least one protease of approximately 38 kDa was present.

O objetivo deste trabalho foi estudar a ação do extrato bruto de Duddingtonia flagrans (isolados AC001 e CG722) sobre larvas infectantes (L3) de ciatostomíneos em coproculturas e confirmar a sua atividade proteolítica por meio de um zimograma. Foram formados os seguintes grupos em coproculturas: grupo 1: 10 mL de extrato bruto de D. flagrans (AC001); grupo 2: 10 mL de extrato bruto de AC001 com íons Ca2+ 10 Mm; grupo 3: 10 mL de extrato bruto de D. flagrans (CG722); grupo 4: 10 mL de extrato bruto de CG722 com íons Ca2+ 10 Mm; e grupo 5 como controle (água destilada), obtendo-se as L3 ao final de 8 dias. O extrato bruto de D. flagrans foi eficiente na redução do número de L3 com os seguintes percentuais de redução: grupo 1 (49,5%); grupo 2 (52,5%); grupo 3 (36,8%) e grupo 4 (57,7%) em relação ao grupo controle (p > 0,05). Confirmou-se a atividade proteolítica por meio do zimograma. Os resultados do presente trabalho confirmam a utilização do extrato bruto do fungo D. flagrans no controle de L3 de ciatostomíneos e sugere a presença de pelo menos uma protease de aproximadamente 38 kDa.

Gastrointestinal parasites presence during the peripartum decreases total milk production in grazing dairy Holstein cows.

Parasitism in cattle is known to impair growth and development. Recent findings suggest that productivity of adult animals is also affected, but little is known about the physiological mechanisms involved. Furthermore, development of nematode resistance to drugs makes imperative the search of management practices that avoid whole herd treatment. We undertook an epidemiological and endocrine study in a grass based dairy farm in Argentina to study the effect of parasites on milk production and the underlying mechanisms involved, and identify individual animals that would benefit from antiparasitic treatment. All the cows in the dairy were followed monthly for egg parasite output in feces. Samples were cultured for genera determination. Milk production and reproductive results were recorded and periodical bleedings for hormone determination were performed. Nematode egg output (EPG) was maximal in late Summer and Autumn and minimal in Spring in coincidence with the Ostertagia inhibition-disinhibition cycle as this genus had the highest prevalence in all the study. The highest proportion of positive samples was found in the high producing herd and maximal counts were found in the peripartal period. Milk production did not correlate with EPG mean values but, when cows were grouped by EPG positivity around parturition, a significant difference in total milk production between EPG null and positive cows was observed. Positive cows produced 7%, 12% or 15% less milk than null EPG cows, depending on the sampling month/s chosen for classification. The highest difference was seen when both prepartum and postpartum samples were taken into account. No difference in lactation length and a marginal effect on partum to first service interval were encountered. Endocrine studies revealed a decrease in serum growth hormone (GH), type I insulin-like growth factor (IGF-I) and prolactin during lactation in cows with positive EPG in the first postpartum sample with respect to null EPG cows at that time. GH levels decreased and prolactin and IGF-I levels increased in both groups of cows from month 0 to 6 in milk. Serum insulin levels remained stable throughout lactation and were similar in both groups of cows. In conclusion, EPG around parturition may be a useful tool for identifying cows that will have a decrease in productivity due to parasite effects and would possibly benefit from an antiparasitic treatment. Besides, our results suggest that detrimental effect of parasites on milk production may be mediated by GH, IGF-I and prolactin serum levels.

Cattle nematodes resistant to macrocyclic lactones: comparative effects of P-glycoprotein modulation on the efficacy and disposition kinetics of ivermectin and moxidectin.

The role of the drug efflux pump, known as P-glycoprotein, in the pharmacokinetic disposition (host) and resistance mechanisms (target parasites) of the macrocyclic lactone (ML) antiparasitic compounds has been demonstrated. To achieve a deeper comprehension on the relationship between their pharmacokinetic and pharmacodynamic behaviors, the aim of the current work was to assess the comparative effect of loperamide, a well-established P-glycoprotein modulator, on the ivermectin and moxidectin disposition kinetics and efficacy against resistant nematodes in cattle. Fifty (50) Aberdeen Angus male calves were divided into five (5) experimental groups. Group A remained as an untreated control. Animals in the other experimental Groups received ivermectin (Group B) and moxidectin (Group C) (200 microg/kg, subcutaneously) given alone or co-administered with loperamide (0.4 mg/kg, three times every 24 h) (Groups D and E). Blood samples were collected over 30 days post-treatment and drug plasma concentrations were measured by HPLC with fluorescence detection. Estimation of the anthelmintic efficacy for the different drug treatments was performed by the faecal egg count reduction test (FECRT). Nematode larvae were identified by pooled faecal cultures for each experimental group. Cooperia spp. and Ostertagia spp. were the largely predominant nematode larvae in pre-treatment cultures. A low nematodicidal efficacy (measured by the FECRT) was observed for both ivermectin (23%) and moxidectin (69%) in cattle, which agrees with a high degree of resistance to both molecules. Cooperia spp. was the most abundant nematode species recovered after the different drug treatments. The egg output reduction values increased from 23% to 50% (ivermectin) and from 69% to 87% (moxidectin) following their co-administration with loperamide. Enhanced systemic concentrations and an altered disposition of both ML in cattle, which correlates with a tendency to increased anthelmintic efficacy, were observed in the presence of loperamide. Overall, the in vivo modulation of P-glycoprotein activity modified the kinetic behavior and improved the efficacy of the ML against resistant nematodes in cattle. The work provides further evidence on the high degree of resistance to ML in cattle nematodes and, shows for the first time under field conditions, that modulation of P-glycoprotein may be a valid pharmacological approach to improve the activity and extend the lifespan of these antiparasitic molecules.

Rooteomics: the challenge of discovering plant defense-related proteins in roots.

In recent years, a strong emphasis has been given in deciphering the function of genes unraveled by the completion of several genome sequencing projects. In plants, functional genomics has been massively used in order to search for gene products of agronomic relevance. As far as root-pathogen interactions are concerned, several genes are recognized to provide tolerance/resistance against potential invaders. However, very few proteins have been identified by using current proteomic approaches. One of the major drawbacks for the successful analysis of root proteomes is the inherent characteristics of this tissue, which include low volume content and high concentration of interfering substances such as pigments and phenolic compounds. The proteome analysis of plant-pathogen interactions provides important information about the global proteins expressed in roots in response to biotic stresses. Moreover, several pathogenic proteins superimpose the plant proteome and can be identified and used as targets for the control of viruses, bacteria, fungi and nematode pathogens. The present review focuses on advances in different proteomic strategies dedicated to the challenging analysis of plant defense proteins expressed during bacteria-, fungi- and nematode-root interactions. Recent developments, limitations of the current techniques, and technological perspectives for root proteomics aiming at the identification of resistance-related proteins are discussed.

Monoxenic liquid culture of the entomopathogenic nematode Steinernema carpocapsae using a culture medium containing whey kinetics and modeling.

The submerged culture of the entomopathogenic nematode Steinernema carpocapsae and its symbiotic bacterium, Xenorhabdus nematophila, was carried out in orbitally agitated bottles using a culture medium containing whey (in grams per litre: 500 whey, 20 yeast extract, 10 dried egg yolk-food grade, 3 sodium chloride, 37 corn oil-food grade). Maximum total viable nematode concentrations of 198,333ml(-1) were achieved within fermentations of 24 days with 64% of the nematode population within the infective juvenile stage (IJ) (126,666ml(-1)) at the end. The kinetics of the bioprocess was well modelled using the four-parameter Sigmoidal model and the corresponding maximum specific rates of nematode production (0.47 day(-1)), carbohydrates consumption (0.0008g(carbohydrates)g(nematodes)(-1)day(-1)) and nitrogen consumption (4.44g(nitrogen)g(nematodes)(-1)day(-1)) are first proposed. Besides, X. nematophila appears to have the capacity of lactose hydrolysis.

Challenges for mass production of nematodes in submerged culture.

Nematodes of Steinernema and Heterorhabditis genera are used as agents in insect biocontrol programs. They are associated with specific bacteria which are also involved in the mechanism of pathogenicity and which are consumed by nematodes as living food. S. feltiae has various developmental stages in its life cycle, including four juvenile stages, adults and the free living form. During mating, males coil themselves around the female, which is around 1 cm long. Successful commercialization of nematode-bacteria biocontrol products depends on the ability to produce sufficient quantities of these products at competitive prices for a full pest control program. This could be feasible if high cell density submerged cultures are designed and implemented; however, major problems related to nematodes mass production in a bioreactor remain unsolved due to the lack of knowledge about the physiological aspects of the nematode, bacteria and nematode-bacteria association, interaction between the three phases present in the bioreactor (liquid, gas, nematodes-bacteria), possibility of mating under hydrodynamic stress conditions, etc. We have found that the two most important engineering aspects to take into account the mass propagation of nematodes are oxygen transfer rate and hydrodynamics to allow mating and to avoid mechanical damage of juveniles in stage 2. This article focuses on several aspects related to the fermentation system such as kinetics of growth, shear stress, hydrodynamics fields in the bioreactor and oxygen demand. Also, results published by other groups, together with those of our own, will be discussed in relation to the main challenges found during the fermentation process.

Evolution of culture broth rheological properties during propagation of the entomopathogenic nematode Steinernema carpocapsae, in submerged monoxenic culture.

This article presents the evolution of culture broth rheological properties during monoxenic cultures of Steinernema carpocapsae in cylindrical bottles agitated orbitally. Rheological properties were evaluated in simple-shear flow conditions and were well-modeled by the Ostwald-de Waele model. Rheological properties varied from slightly dilatant, n = 1.2 (-), to moderately pseudoplastic flow behavior, n = 0.6 (-). Nematode concentrations increased from 750 +/- 190 to 130 900 +/- 6900 nematodes/mL, and the apparent viscosity (eta(a)) evolved from 4.5 +/- 0.7 to 46.6 +/- 3.2 mPa.s during the fermentations. Rheological behavior did not appear to be strongly influenced by nematode number and/or its stage of development; however, the release of substances from the decomposition of nematode cadavers appeared to be of great importance. Among the different developmental stages of the nematodes, only juveniles of the first stage (J1) were highly susceptible to the shearing conditions tested (shear stress, tau(r)()(theta), from 0.9 to 3.5 Pa during periods of 80-100 min), resulting in the viability loss of 85% of J1 nematodes.

Vasoactive intestinal polypeptide-like and peptide histidine isoleucine-like proteins excreted/secreted by Nippostrongylus brasiliensis, Nematodirus battus and Ascaridia galli.

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.

The effect of anaerobiosis on adenosine triphosphate levels in larval Nippostrongylus brasiliensis and Haemonchus contortus.

The adenosine triphosphate (ATP) content of the pre-parasitic stages of Nippostrongylus brasiliensis, Haemonchus contortus (L1, L2 and L3) and the adults of the free-living nematode, Panagrellus redivivus, have been measured by bioluminescent photometry in aerated or near-anoxic conditions. The ATP content of the L1 and L2 stages of both parasitic species was unaltered by a lack of oxygen over a 90-min period. However, the L3 stage of both species and the adults of P. redivivus showed a significant fall in the level of ATP within 10 min of near-anoxia. This lower level of ATP was maintained during oxygen lack but the initial content was restored on return of the nematodes to aerobic conditions. The results suggest that measurement of ATP by bioluminescent photometry offers a readily measured and sensitive indicator of the capacity of a nematode to cope with transient changes in oxygen supply without undue metabolic stress.