T. Von Brand

Chemical and histological observations on the influence of schistosoma mansoni infection on Australorbis glabratus.

Very little is known about the influence of parasites on the chemical composition and metabolism of invertebrate hosts. The only thoroughly studied cases concern parasites of decapod crustaceans. These investigations have revealed disturbances in the fat and carbohydrate storage in the body of the host, as well as changes in the ratios between inorganic substances and proteins in the latters blood (Robson, 1911 ; Smith, 1913; Drilhon, 1936, 1937; Reinhard and von Brand, 1944). It appeared desirable, therefore, to undertake a comparable investigation on snails parasitized by the developmental stages of trematodes since such snails may have changed chemical composition and metabolism and therefore may react differently than non-parasitized specimens to chemical substances used as molluscacides in control measures. In the present paper the question will be examined as to whether the fat and polysaccharide content, and the oxygen consumption, of Australorbis glabratus parasitized by Schistosoma mansoni differ from those of non-parasitized specimens.

Further observations upon the composition of Acanthocephala.

Through the courtesy of Swift and Co., Chicago, it was possible to get long pieces of infected pig intestines a very short time after slaughtering. These pieces had been in contact with water for only a few minutes. The figures found for glycogen and other substances in the worms thus obtained were somewhat higher than those previously reported, probably because this time the contact of the worms with water was practically eliminated. As an additional precaution, only females and males attached at nearby places of the intestine were used for the comparative chemical determinations. I am indebted to Dr. M. S. Ferguson for specimens of Leptorhynchoides thecatus from the sunfish, Eupomotis gibbosus, fixed with Carnoys solution. Echinorhynchus coregoni was collected from infected perches, Perca flavescens, of Lake Michigan.

Chemical and morphological observations upon the composition of Macracamhorhynchus hirudinaceus (Acanthocephala).

Data on the chemical composition of a few nematodes, cestodes and trematodes have been published by several investigators, but so far practically nothing is known about the biochemistry of acanthocephala. Weinland and Rudolph (1910) performed one glycogen analysis on freshly taken Macracanthorhynchus. Schwartz (1920) published a note on enzymes and hemotoxins in their body fluid and Mueller (1928/29) reported a nitrogen and sulfur analysis of the cuticle of the same worm. The lack of more complete information concerning the physiology of this group is regrettable since these worms are highly specialized in their body structure and show a remarkable adaptation to parasitic life. The following investigation was undertaken in order to secure some information concerning the composition of one of the most readily available of these forms, Macracanthorhynchus hirudinaceus.

Physiological observations upon a larval Eustrongylides. VII. Studies upon survival and metabolism in sterile surroundings.

In a previous paper of this series (von Brand and Simpson, 1942) it was shown that larval Eustrongylides occurring normally in cysts of Fundulus can be kept alive a long time in vitro in various media, provided that conditions remain sterile throughout the whole course of the experiments. A continuation and amplification of these studies seemed indicated, since, with the exception of Glaser and Stolls (1938) and Stolls (1940) work on Haemonchus larvae, no data are known on the behavior of parasitic nematodes kept in vitro under sterile conditions. It becomes more evident, however, from year to year that the development of sterile media for the maintenance of parasitic worms will represent a starting point from which the physiology of these organisms can be studied with a much greater degree of reliability than was hitherto possible. In the present paper the following points have been investigated: influence of pH, various carbohydrates and lowering of the temperature from 37? to 20? C on the survival. Also studied were the rates of consumption of oxygen, sugar, and glycogen under various conditions.

Influence of some Potential Molluscacides on the Oxygen Consumption of Australorbis glabratus.

The killing mechanisms of chemical compounds used in the control of harmful or obnoxious invertebrates are quite variable. The problem has been investigated to some extent for the case of insects, but no data whatever seem available for snails in general and the trematode-transmitting species specifically. The urgent need for new molluscacides, more potent than the much applied copper sulfate or similar substances, has led to a survey of the snail-killing properties of a variety of chemical compounds, the results of which will be reported elsewhere by Nolan and Mann. During this work a number of potential molluscacides was uncovered. These, as well as some inactive compounds, were studied by us in respect to their inhibitory effect on the oxygen consumption of Australorbis glabratus, the intermediate host of Schistosoma mansoni in the West Indies and South America.1

Physiological observations upon a larval Eustrongylides. VIII. Influence of respiratory poisons upon the aerobic gaseous metabolism.

The larva of Eustrongylides ignotus which lives in cysts inside various fishes is a parasitic nematode that, contrary to many other endoparasites, leads normally a predominantly aerobic life. Two observations point in this direction. The first is that the blood-red color of the worms is due to haemoglobin dissolved in the body fluid (von Brand, 1937); the presence of such a concentration of this respiratory pigment could hardly be understood unless it were used to gather significant amounts of oxygen. The second observation represents an even more convincing argument. It was shown (von Brand, 1942) that a Eustrongylides exposed to an experimental anaerobic period accumulates an oxygen debt which is repaid over a period of several hours as soon as oxygen becomes again available. However, worms isolated from their cysts immediately prior to the determinations give very little evidence of having contracted there an oxygen debt; only during the first half hour is their oxygen consumption somewhat higher than the steady level reached after that time. In view of this situation it seemed of interest to characterize the aerobic respiration of this organism further, and this was done by studying both the influence of respiratory inhibitors and stimulants. Some data were also gathered concerning the question whether anaerobic processes can supplement the failing aerobic respiration when the latter is inhibited by poisons. A study along these lines appeared the more desirable as so far very little is known about the nature of the aerobic respiration of parasitic nematodes. The only comparable investigation is that by Stannard, McCoy and Latchford (1938) who used the larvae of Trichinella spiralis.