-
[
Ann Parasitol Hum Comp
]
In lactating females of many animal species infested by Nematoda, the self-cure is, if not suppressed, at least very distinctly delayed. It does not appear that an immunological deficiency is the cause of this. We show that this phenomenon also exists in lactating female rats with Strongyloides ratti parasites. In fact, for Strongyloides ratti, the maintenance of the worms is not the only notable modification determined by lactation; much more important is the decrease in the intensity of the parasitism. This aspect is not mentioned by writers who have only studied the different parasitic states in their final phase. Parallel to these alterations in the parasitism, the evolution of the corticosteronemy differs, from two points of view, from that described in infested virgin rats: --Suppression of the hypercorticosteronemy which normally appears 48 hours after infestation; --Attenuation of the hypocorticosteronemy which usually sets in from the tenth day of infestation. This opposition of lactation to the variations in the corticosteronemy induced by the worms is explained by the effect of lactation on the secretion of gluco-cortico-steroids, described under the term of "buffer effect of lactation". The decrease in the intensity of the parasitism may be explained by the fact that lactation, by preventing the hypercorticosteronemy normally caused by larval migration, permits the intervention of aspecific defences. As for the prolongation of the parasitism, it would seem to result on one hand, from a reduced solicitation of the means of defence owing to a smaller number of worms and, on another hand, from the slowing down of the hypocorticosteronemy through the buffer effect of lactation with all the consequences flowing from this at the level of the specific and aspecific defence reactions.
-
[
Ann Parasitol Hum Comp,
1985]
The plasma corticosterone induced in the rat by the development of Strongyloides ratti or Trichinella spiralis reaches a sufficient level of intensity to determine reticulocytopenia. The latter is linked chronologically to the inhibition of parasitemia in Plasmodium berghei, which occurs when this protozoa develops at the same time as the Nematodes, and seems to be the causal factor. This hypothesis may be verified by replacing the helminths with the corticotropic action of A.C.T.H. which causes a decrease in the number of reticulocytes.
-
[
Ann Parasitol Hum Comp
]
Repeated injections of corticosterone acetate, physiological hormone of the Rat, in rats carrying Strongyloides ratti, oppose the deparasiting which normally takes place spontaneously. The secretion induced by this hormone by impregnating the organism through the corticotropic factor administered in the form of tetracosactide-zinc, achieves the same result. During all these treatments, an important hypercorticosteronemy is established. Stopping the injections is quickly followed by the worms-being rejected and the corticosteronemy returning to normal. The relations between the corticosteronemy and the parasitism are analysed and lead to the conclusion that the parasite induces an aspecific hypocorticosteronemiant reaction which, through its aspecific and specific repercussions, participates in the self-cure phenomenon.
-
Pennington PR, Heistad RM, Nyarko JNK, Barnes JR, Bolanos MAC, Parsons MP, Knudsen KJ, De Carvalho CE, Leary SC, Mousseau DD, Buttigieg J, Maley JM, Quartey MO
[
Sci Rep,
2021]
The pool of -Amyloid (A) length variants detected in preclinical and clinical Alzheimer disease (AD) samples suggests a diversity of roles for A peptides. We examined how a naturally occurring variant, e.g. A(1-38), interacts with the AD-related variant, A(1-42), and the predominant physiological variant, A(1-40). Atomic force microscopy, Thioflavin T fluorescence, circular dichroism, dynamic light scattering, and surface plasmon resonance reveal that A(1-38) interacts differently with A(1-40) and A(1-42) and, in general, A(1-38) interferes with the conversion of A(1-42) to a -sheet-rich aggregate. Functionally, A(1-38) reverses the negative impact of A(1-42) on long-term potentiation in acute hippocampal slices and on membrane conductance in primary neurons, and mitigates an A(1-42) phenotype in Caenorhabditis elegans. A(1-38) also reverses any loss of MTT conversion induced by A(1-40) and A(1-42) in HT-22 hippocampal neurons and APOE 4-positive human fibroblasts, although the combination of A(1-38) and A(1-42) inhibits MTT conversion in APOE 4-negative fibroblasts. A greater ratio of soluble A(1-42)/A(1-38) [and A(1-42)/A(1-40)] in autopsied brain extracts correlates with an earlier age-at-death in males (but not females) with a diagnosis of AD. These results suggest that A(1-38) is capable of physically counteracting, potentially in a sex-dependent manner, the neuropathological effects of the AD-relevant A(1-42).
-
[
Worm Breeder's Gazette,
2003]
Wormgenes is a new resource for C.elegans offering a detailed summary about each gene and a powerful query system.
-
[
Front Pharmacol,
2020]
Oligomeric assembly of Amyloid- (A) is the main toxic species that contribute to early cognitive impairment in Alzheimer's patients. Therefore, drugs that reduce the formation of A oligomers could halt the disease progression. In this study, by using transgenic <i>Caenorhabditis elegans</i> model of Alzheimer's disease, we investigated the effects of frondoside A, a well-known sea cucumber <i>Cucumaria frondosa</i> saponin with anti-cancer activity, on A aggregation and proteotoxicity. The results showed that frondoside A at a low concentration of 1 M significantly delayed the worm paralysis caused by A aggregation as compared with control group. In addition, the number of A plaque deposits in transgenic worm tissues was significantly decreased. Frondoside A was more effective in these activities than ginsenoside-Rg3, a comparable ginseng saponin. Immunoblot analysis revealed that the level of small oligomers as well as various high molecular weights of A species in the transgenic <i>C. elegans</i> were significantly reduced upon treatment with frondoside A, whereas the level of A monomers was not altered. This suggested that frondoside A may primarily reduce the level of small oligomeric forms, the most toxic species of A. Frondoside A also protected the worms from oxidative stress and rescued chemotaxis dysfunction in a transgenic strain whose neurons express A. Taken together, these data suggested that low dose of frondoside A could protect against A-induced toxicity by primarily suppressing the formation of A oligomers. Thus, the molecular mechanism of how frondoside A exerts its anti-A aggregation should be studied and elucidated in the future.
-
[
International Journal of Developmental Biology,
1998]
Pleiotropy , a situation in which a single gene influences multiple phenotypic tra its, can arise in a variety of ways. This paper discusses possible underlying mechanisms and proposes a classification of the various phenomena involved.
-
[
Curr Biol,
2011]
Recent work on a Caenorhabditis elegans transmembrane ATPase reveals a central role for the aminophospholipid phosphatidylethanolamine in the production of a class of extracellular vesicles.
-
[
Naturwissenschaften,
2004]
Animals respond to signals and cues in their environment. The difference between a signal (e.g. a pheromone) and a cue (e.g. a waste product) is that the information content of a signal is subject to natural selection, whereas that of a cue is not. The model free-living nematode Caenorhabditis elegans forms an alternative developmental morph (the dauer larva) in response to a so-called 'dauer pheromone', produced by all worms. We suggest that the production of 'dauer pheromone' has no fitness advantage for an individual worm and therefore we propose that 'dauer pheromone' is not a signal, but a cue. Thus, it should not be called a pheromone.
-
[
J Antibiot (Tokyo),
1990]
Cochlioquinone A, isolated from the fungus Helminthosporium sativum, was found to have nematocidal activity. Cochlioquinone A is a competitive inhibitor of specific [3H]ivermectin binding suggesting that cochlioquinone A and ivermectin interact with the same membrane receptor.