Observations on crystals found in the intestine of Nematodirus battus during the development of immunity to this nematode in lambs.

Lambs which were given 60000 infective larvae of Nematodirus battus progressively threw off adult nematodes from day 20 onwards. Large, hexagonal crystals appeared in the intestine of the adult nematode at about this time and caused blockage of the intestinal-rectal or -cloacal junction. Lambs which were given 1000-2000 infective larvae did not throw off the infection, and adult nematodes from lambs which had been infected for up to 74 days did not contain these crystals. Chemical, histochemical and x-ray microanalysis tests on the crystals indicated that they are lipoprotein in composition. The crystals arise within the lumen of the nematode and appear to be associated with the development of immunity to this nematode in lambs.     

Carboxypeptidase-like activity during development and aging of Nippostrongylus brasiliensis

An acid carboxypeptidase whose activity, based on several biochemical parameters, was determined to be similar to mammalian lysosomal carboxypeptidase was maximal at pH 5.0 during the early parasitic stages of development of the nematode Nippostrongylus brasiliensis. No such enzyme activity could be detected in the early free-living larval stages of this nematode. Carboxypeptidase activity declined as the age of the parasitic adult increased. Timing of maximum activity corresponds to the shift from free-living to parasitic stages of the life cycle.     

Changes in the structure of Nippostrongylus brasiliensis intestinal cells during development from the free-living to the parasitic stages

The ultrastructure of Nippostrongylus brasiliensis intestinal cells was examined in free-living, feeding second-stage larvae, infective, nonfeeding third-stage larvae, and parasitic, feeding third-stage larvae. The intestinal cells of second-stage larvae were characterized by a well-developed microvillar border, large numbers of ribosomes, Golgi complexes, rough endoplasmic reticulum, and nuclei with prominent nucleoli. The intestinal cells of infective, third-stage larvae had very few microvilli and the cells were extremely narrow. Few ribosomes, Golgi complexes, and little rough endoplasmic reticulum were present. Nuclei did not contain nucleoli. When worms were introduced into an in vitro culture system, development of intestinal cells began. By 36 hr, microvilli were well differentiated and the cysoplasm contained numerous ribosomes and Golgi complexes, and rough endoplasmic reticulum, mitochondria, and nucleoli were prominent. These morphological changes were related to changes in the physiology of Nippostrongylus brasiliensis which occur during development from a free-living to parasitic form.     

Bile and bile salts and exsheathment of the intestinal nematodes Trichostrongylus colubriformis and Nematodirus battus

1972. Bile and bile salts and exsheathment of the intestinal nematodes Trichostrongylus colubriformis and Nematodirus battus. International Journal for Parasitology, 2: 433–438. Exsheathment of T. colubriformis was potentiated at physiological levels of CO₂ by bile and bile salts. Lamb bile and crude sodium taurocholate preparations produced the greatest increase in exsheathment while rabbit bile, sodium glycocholate and deoxycholate had less pronounced effects. Exsheathment in bile and taurocholate occurred at a pH above 4 and it is therefore suggested that infective larvae which fail to exsheath in the abomasum could well do so in the proximal part of the small intestine. Pure sodium taurocholate was found to greatly potentiate exsheathment of N. battus in vitro but this occurred at a pH below 3 and thus the action of this bile salt could not affect exsheathment in the host.     

Moulting in nematodes: The formation of the adult cuticle during the final moult of Nippostrongylus brasiliensis

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.     

Intestinal distribution of worms and host ingesta in Nippostrongylus brasiliensis.

The gastrointestinal nematode Nippostrongylus brasiliensis is thought to feed on host ingesta, and it is generally thought that the presence of ingesta determines the distribution of this parasite within the host intestine. However, these assertions have not been supported by direct evidence. The purpose of this study was to test the hypothesis that N. brasiliensis worms are preferentially found in regions of the host small intestine containing ingesta. The relationship between worm and ingesta distribution was investigated using mice infected with N. brasiliensis and killed on day 8 postinfection at 0130, 0730, 1330, or 1930 hr. There was an inverse relationship between worm and ingesta distributions, and the worms were distributed significantly more anteriad in the intestine than host ingesta, at all times during the 24 hr. To determine what the worms fed on, host ingesta, tissue, and blood were differentially labeled with the fluorescent dyes rhodamine B and Fluoresbrite. The results of this study suggest that N. brasiliensis feeds on the host's intestinal wall, and that habitat distribution of this parasite within the small intestine is not directly related to the presence of luminal ingesta.     

Changes in the adenylate energy charge and the induction of sporulation in Saccharomyces diastaticus

The induction of sporulation in yeast is generally accompanied by a sharp increase in energy metabolism which is evidenced by a rise of the adenylate energy charge by that time. The energy charge can be held at a low level by limitation of the phosphate supply in the growth medium. Ascus formation remains unaffected by this treatment. This suggests that the rise in ATP production normally encountered during early sporulation is not essential for the initiation of sporulation.     

Response of nucleoside diphosphate kinase to the adenylate energy charge

The reaction catalyzed by nucleoside diphosphate kinase responds to the energy charge of the adenylate pool. The velocity is maximal at a charge of 1.0, and decreases sharply with a decrease in the charge. This response may control the flow of phosphate from ATP into the other nucleotide pools and thus participate in the regulation of macromolecular synthesis by the energy level of the cell, as reflected in the charge of the adenylate pool.     

Adoptive transfer of immunity against Nippostrongylus brasiliensis in mice. In vitro restimulation of immune cells before their transfer

When mesenteric lymph node cells from infected mice were stimulated during an in vitro culture with exoantigens or with a purified protective antigen of Nippostrongylus brasiliensis, a drop was noted in the number of cells required to transfer protection to new mice. A maximal effect was already obtained after 4 hrs. of culture, but irradiated cells or cells from another mouse strain were unable to mediate this transfer. T cells were more effective than B cells in transferring the protection.     

Nippostrongylus brasiliensis: effects of immunity on the pre-intestinal and intestinal larval stages of the parasite

Nippostrongylus brasiliensis: effects of immunity on the pre-intestinal and intestinal larval stages of the parasite. International journal for Parasitology4: 183–191. Migration of the pre-intestinal larval stages of N. brasiliensis was studied in rats undergoing either primary or challenge infections. In rats undergoing a primary infection, more than 67 percent of larvae successfully migrated from the skin to the oesophagus by 70 h after infection, and subsequently over 90 per cent of these larvae became established in the small intestine as sexually mature adults. In immune rats undergoing a second infection, 46 per cent of larvae completed migration to the oesophagus by 70 h and of these, only 1·6 per cent became established in the intestine to produce eggs. These inhibitory effects on the pre-intestinal and intestinal larval stages were even more pronounced in immune rats undergoing a third or fourth infection and in addition, there was a prolonged sojourn and substantial retention of larvae in their lungs. There was no evidence that the immune response had an adverse effect on oesophageal fourth stags larvae as these organisms (obtained from immune donors) were able to establish and develop to maturity when transferred per os to normal animals.Syngeneic transfer of immune mesenteric lymph node cells to normal recipients, caused expulsion of parasites from the intestine but failed to effect migration of pre-intestinal larval stages. The implications of these findings are discussed in the context of current knowledge of the mechanisms of immunity to helminths.