Records of non-sporozoan Protozoa occurring in the hind-gut of cockroaches are summarized.

The Protozoa studied were the three flagellates Lophomonas striata, L. blattarum, Monocercomonoides orthopterorum; the rhizopod Endamoeba blattae, and the ciliate Nyctotherus ovalis, in the cockroaches Periplaneta americana, P. australasiae, Blatta orientalis, Blattella germanica and Blaberus giganteus.

Specimens of Blatta and Periplaneta americana were maintained at 37° and 25°C. under extreme conditions of humidity. Maximum humidity enabled the host, and the Nyctotherus which it harboured to survive for a longer time. The results of the experiments indicated that the well-being of the protozoan parasites is closely linked to that of the host.

Periplaneta americana, Blatta, Blatella and Blaberus were subjected to pure oxygen at 3½ atmospheres pressure and the effect on the Protozoa observed. The flagellates were killed first, then Endamoeba and lastly Nyctotherus. They survived in Blatta for a longer time than in Periplaneta; and Nyctotherus in Blaberus and Blattella sometimes survived the hosts. The hosts appeared to act as a barrier against poisoning by oxygen, and the strength of the barrier varied in the different species of cockroaches.

Nymphal Periplaneta or Blatta which were about to moult underwent a period of self-starvation which lasted for up to 10 days. The period was terminated by the moult: at this time, the little food that was in the gut was very dry. All species of Protozoa could survive these conditions, but Nyctotherus seemed to be the most hardy. The main mass of ciliates seemed to be nearer to the anus than in the non-moulting cockroach. Many of the ciliates were often clumped together into a ‘raspberry’. The bodies of the individual ciliates were more spherical than usual, but those in the ‘raspberry’ were moulded into polygonal shapes. The macronucleus underwent a change in form which revealed that its basic structure is that of a folded sheet.

The changes were reversed within 24 hr. They could not be induced by experimentally imposed conditions of starvation or dehydration of the hind-gut. The changes in Nyctotherus ovalis are contrasted with the sexual stages occurring in N. cordiformis and in the Protozoa of Cryptocercus.

This work was done during the tenure of a Research Studentship awarded by the Agricultural Research Council. I am deeply indebted to Dr P. Tate for his encouragement and counsel at all stages of the work. I wish to thank Drs J. Barker and E. R. Turner, of the Cambridge University Botany School, for the loan of the apparatus used in subjecting cockroaches to oxygen under pressure, and Mr A. C. Bloy, of the Zoology Department, for gifts of cockroaches. I am most grateful to Mrs E. F. M. Hawkins and Mr B. H. Baker for technical assistance.

Eimeria tenella is recognized worldwide as a significant pathogen in the poultry industry. However, a lack of methods for isolating developing schizonts has hindered the use of transcriptome analyses to discover novel and developmentally regulated genes. In the present study, we characterized the long-term successive development of E. tenella in infected chicken caeca and assessed the utility of laser microdissection (LMD) for the isolation of schizont RNA. Developmental stages, including those of the first, second, and third-generation schizonts and gametocytes, were synchronous. Using LMD, only the mature second-generation schizonts were successfully excised from the lamina propria, and non-degraded RNA was purified from the schizonts. E. tenella-specific genes were amplified by reverse transcription polymerase chain reaction (RT-PCR). These results augment our understanding of the E. tenella life cycle, and reveal LMD as a potentially useful tool for gene expression analyses of the intracellular stages of E. tenella.

The following observations were made in September, 1908, during a short residence at Aberdeen where, through the kindness of Prof. J. Arthur Thomson, I was able to deal with a considerable number of fishes in the very limited time at my disposal1. The investigation was intended as a continuation of that already carried out at St Andrews, the object being to examine a number of fishes which could not readily be obtained at the latter place. There the fishes dealt with were mostly littoral forms, but at Aberdeen attention was mainly paid to the larger deep-water fish; of these a plentiful supply could be easily obtained. A few species were re-examined here.

There was no difference between the worm burdens or the lengths of the worms recovered from sexually immature male and female mice infected with Amplicaecum robertsi.

In mice older than 70 days there were fewer larvae recovered from the female than the male host. The larvae were also longer in the male than in the female mouse.

The suckling mouse harboured fewer larvae than the weanling; the susceptibility of the mouse continued to increase with increasing age until the one-hundredth day in the males and the seventy-fifth day in the females. In animals older than this an age resistance was apparent. It is suggested that the much lower susceptibility of the suckling mouse is due to the small gut and villi size reducing the establishment of the larvae.

Worm growth also varied with host age, the longest larvae being recovered from the suckling mice and successively smaller worms from each older age group up to the seventy-fifth day, beyond which there was no significant change in worm growth with age of the host. There was no difference between the worm burdens and the lengths of the worms recovered from 90-day-old mice. The injection of testosterone had little or no effect on the host–parasite relationship of gonad-ectomized animals. Larvae from gonadectomized mice were significantly shorter than those from the intact hosts.

The effect of gastrointestinal helminths on Pb accumulation in the host body is ambiguous. A laboratory experiment with Rattus norvegicus/Hymenolepis diminuta model was conducted to determine Pb toxicokinetics in a terrestrial host-parasite system. The ET-AAS or ICP–OES techniques were used to determine Pb concentrations (CPb) in both tapeworms and host tissues (kidney, liver, bone, testes, muscle and intestinal wall). Concerning the entire host-parasite system, the highest CPb were detected in H. diminuta. Rat kidneys and bone were the only two tissues whose mean Pb levels were lower in parasitized animals than they were in non-infected subjects after both levels of exposure. At low Pb exposure, parasitization slightly changed the Pb toxicokinetics in the host body. However, with respect to tissue at the same exposure level, no significant differences were detected between the parasitized and non-parasitized animals and no significant correlations were found between CPb in tapeworms and those of host tissues. The results of this study indicate that H. diminuta does not protect rat from elevated Pb exposure even if tapeworm accumulates a higher portion of ingested Pb dose compared with that of the most Pb-loaded host soft tissue. The portion of Pb dose accumulated in H. diminuta correlates positively with parasite biomass.

The potato cyst nematode (PCN) Globodera rostochiensis, like other parasitic nematodes, needs to synchronize its life-cycle with that of its host. This synchrony is achieved by the invasive-stage juvenile remaining dormant within its egg until stimulated to hatch by the presence of root diffusates of its host. Root diffusates may induce changes in gene expression in PCN, some of which may be important in the transition to a parasitic mode of existence. We have used a range of techniques including differential display to examine gene expression during stimulation and hatching of PCN. We find that few changes in gene expression appear to be induced directly by root diffusates. Instead, changes in gene expression seem to occur during or immediately after the hatching process. These results are discussed in the context of the host–parasite relationship.

Antibiotics have been widely used to identify ribosomal activity in Trypanosoma brucei mitochondria. The validity of some of the results has been questioned because the permeability of the trypanosome cell membrane for some antibiotics was not adequately addressed. Here we describe translation inhibition experiments with digitonin-permeabilized trypanosomes to exclude diffusion barriers through the cell membrane. Using this system we were able to confirm, next to the eukaryotic and thus cycloheximide-sensitive translation system, the existence of a prokaryotic-type translational activity being cycloheximide resistant, chloramphenicol sensitive and streptomycin dependent. We interpret this observation analogous to what has been found for other eukarya as the independent protein synthesis activity of the mitochondrial organelle. We further examined the putative translational apparatus by using isokinetic density-gradient analysis of mitochondrial extracts. The 2 mitochondrially encoded rRNAs, the 9S and 12S rRNAs, were found to co-fractionate in a single RNP complex, approximately 80S in size. This complex disassembled at reduced MgCl2 concentrations into 2 unusually small complexes of 17·5S, containing the 9S rRNA, and 20S containing the 12S rRNA. A preliminary stoichiometry determination suggested a multicopy assembly of these putative subunits in a 2[ratio ]3 ratio (20S[ratio ]17·5S).

A 120 kDa antigen produced by juvenile female Litomosoides sigmodontis (Juv-p120) was isolated and purified. The amino acid composition of the molecule was determined. Juv-p120 was shown to be highly modified with N,N-dimethyl-aminoethanol (28·4 mol%). Treatment of Juv-p120 with potassium hydroxide (β-elimination) or with sodium m-periodate leads to the destruction of epitopes recognized by antibodies immune affinity-purified with isolated Juv-p120. Juvenile L. sigmodontis were shown to release Juv-p120 into the pleural cavity of infected Mastomys coucha before the onset of patency.

Phylogeography of parasites and microbes is a recent field. Phylogeographic studies have been performed mostly to test three major hypotheses that are not mutually exclusive on the origins and distributions of human parasites and microbes: (1) the “out of Africa” pattern where parasites are supposed to have followed the dispersal and expansion of modern humans in and out of Africa, (2) the “domestication” pattern where parasites were captured in the domestication centres and dispersed through them and (3) the “globalization” pattern, in relation to historical and more recent trade routes. With some exceptions, such studies of human protozoans, helminths and ectoparasites are quite limited. The conclusion emphasizes the need to acquire more phylogeographic data in non-Occidental countries, and particularly in Asia where all the animal domestications took place.

Male unknown.

Female (Fig. 1): Scutum (2·2 x 1·8 mm.) much longer than broad, with well-marked lateral folds on the anterior half; cervical grooves rather far apart at origin, then faint and divergent; some very fine punctations on the lateral folds and in the area between them and the cervical grooves, the posterior region very glossy and almost devoid of punctations. Emargination very slight. Venter: vulva between coxae IV. Genital grooves only slightly divergent, not extending beyond the anus. Anal groove horseshoe-shaped, then shallow and divergent. Spiracles nearly circular and very large (larger than coxa IV). Capitulum long; basis triangular, without cornua or auriculae, its ventral surface divided by a transverse line. Porose areas large, sub-rectangular, with narrow interval. Palps fairly stout; hypostome lanceolate, dentition 2/2, about twelve teeth per file, the outer the stronger. Legs: coxa I deeply cleft into two equal flat teeth, recalling that of Rhipicephalus, and very unusual in Ixodes; coxae II–IV with an external tooth, diminishing in size. Tarsi long (especially tarsus I) and tapering, the pad nearly as long as the rather weak claws.

The DNA coding for parts of the repetitive amino acid sequence of the Plasmodium falciparum circumsporozoite protein has been spliced to a sequence encoding part of the precursor to the major merozoite surface antigens, to produce a hybrid gene. Expression in Escherichia coli produces a protein with antigenic determinants from both malaria proteins. Antibodies raised against the expressed material react with both a peptide derived from the circumsporozoite repeat sequence, and the merozoite surface molecule. Hybrid molecules of this type may be the basis of a malaria vaccine.

Continual low-level exposure of sheep to the helminth Teladorsagia circumcincta elicits a temporary protective immunity, where factors in the immune abomasal mucosa prevent penetration of infective larvae, but which is essentially lost within 6 weeks of cessation of parasite challenge. Here, a proteomic approach was used to identify proteins that are differentially regulated in immune compared to naïve sheep, as potential key mediators of immunity. Six naïve sheep and 12 sheep trickle-infected with T. circumcincta were treated with anthelmintic, and the naïve (control) and 6 immune sheep were killed 7 days later. The remaining 6 sheep (immune waning) were killed 42 days after anthelmintic treatment. Abomasal tissue samples were subjected to 2D-gel electrophoresis and densitometric analysis. Selected spots (n=73) were identified by peptide mass fingerprinting and confirmatory Western blotting was carried out for 10 proteins. Spots selectively up-regulated in immune versus control, but not immune waning versus control sheep, included galectin-15 and thioredoxin, which were confirmed by Western blotting. In immune sheep, serum albumin was significantly down-regulated and albumin proteolytic cleavage fragments were increased compared to controls. Unexpectedly, albumin mRNA was relatively highly expressed in control mucosa, down-regulated in immune, and was immunolocalized to mucus-producing epithelial cells. Thus we have identified differential expression of a number of proteins following T. circumcincta trickle infection that may play a role in host protection and inhibition of parasite establishment.

1. The life histories of Lechriorchis primus Stafford, L. tygarti n.sp. and Caudorchis eurinus n.gen. et sp. have been experimentally completed in three hosts, the first complete life histories to be worked out for species of the subfamily Reniferinae.

2. The definitive hosts of the three forms were found to be two species of garter snakes, Thamnophis sauritus and T. sirtalis.

3. Three species of snails, Physella gyrina, P. parkeri, and P. ancillaria, have been found to serve as the first intermediate host in the life cycles of Lechriorchis primus and Caudorchis eurinus n.gen. et sp., and two species of snails, Physella gyrina and P. heterostropha, in the life cycle of Lechriorchis tygarti n.sp.

4. The tadpoles of two species of frogs, Rana clamitans and R. pipiens, were found to serve as the second intermediate hosts in the life cycles of all three trematodes. The cercariae penetrate larvae of Triturus and small fish, but live only a short time in these animals.

5. Every stage in the life history of Lechriorchis primus, including egg, miracidium, mother sporocyst, daughter sporocyst, cercaria, metacercaria, and developmental stages in the definitive host, has been described in detail.

6. The mother sporocyst of forms having a stylet cercaria is described for the first time.

7. The flame cell pattern of the cercariae of L. primus, L. tygarti n.sp., and Caudorchis eurinus n.gen. et sp. has been determined to be of the “2 × 6 × 3’ type. Also the adult stage of C. eurinus was determined to have the same type.

8. It has been pointed out that the life histories of the members of the subfamily are uniform in that their life history stages display a remarkable similarity.

9. It has been suggested that this uniform type of life cycle and remarkable similarity of larval stages offer the most logical basis for establishing the subfamily Reniferinae as a natural group.

The material examined in the present investigation was given to the writer by Mr W. Ross Cockrill, F.R.C.V.S., Veterinary Officer, Ministry of Agriculture and Fisheries, Carmarthen. The specimens were collected by Mr Ross Cockrill on the whale factory ship Balaena when he accompanied the Antarctic Whaling Expedition in the winter of 1951–2 for the purpose of making investigations into the pathology of whales. The whales were caught in the Ross Sea area roughly between 67° 51′ S. and 71° 13′ S., and the parasitic worms recovered from them include cestodes, nematodes and Acanthocephala. The worms were fixed at the time of collecting, the cestodes in 5% formalin and the nematodes and Acanthocephala in hot 70% alcohol. When only one or a few specimens were found they were all fixed, but if the infestation was heavy a sample was collected. In addition, portions of infested kidney and lesions from other parts of the body thought to be associated with parasitic infestation were included in the collection. The writer is greatly indebted to Mr Ross Cockrill for the gift of this material.

The swimbladder functions as a hydrostatic organ in most bony fishes, including the European eel, Anguilla anguilla. Infection by the nematode Anguillicoloides crassus impairs swimbladder function, significantly compromising the success of the eel spawning migration. Swimbladders from 32 yellow eels taken from Lake Trasimeno (Central Italy) were analysed by histopathology- and electron microscopy-based techniques. Sixteen eels (50%) harboured A. crassus in their swimbladders and intensity of infection ranged from 2 to 17 adult nematodes per organ (6.9 ± 1.6, mean ± s.e.). Gross observations of heavily infected swimbladders showed opacity and histological analysis found a papillose aspect to the mucosa and hyperplasia of the lamina propria, muscularis mucosae and submucosa. Inflammation, haemorrhages, dilation of blood vessels and epithelial erosion were common in infected swimbladders. In the epithelium of parasitized swimbladders, many empty spaces and lack of apical junctional complexes were frequent among the gas gland cells. In heavily infected swimbladders, we observed hyperplasia, cellular swelling and abundant vacuolization in the apical portion of the gas gland cells. Numerous mast cells and several macrophage aggregates were noticed in the mucosal layer of infected swimbladders. We found more nervous and endocrine elements immunoreactive to a panel of six rabbit polyclonal antibodies in infected swimbladders compared to uninfected.

Vertical migration by infective larvae (L3) of 3 species of nematodes was investigated. Upright truncated agarose cones were used to test upward migration, and comparable truncated cone-shaped agarose hollows were used to test downward migration. Flat agarose plates were control surfaces. When placed at the bases of upright cones, 74% of Ancylostoma caninum L3 migrated up, whereas only 16·5% migrated down the indented cones; this latter value was not significantly different from larval migration on flat plates. Strongyloides stercoralis L3 also migrated upward in significant numbers (80%). These larvae also failed to migrate downward under normal conditions. However, when the bottoms of the indented cones were 3–5 °C warmer than the tops, 75·5% of S. stercoralis L3 migrated down. In contrast, Haemonchus contortus L3 showed no tendency to crawl up or down cones, when compared with normal crawling behaviour on flat plates. Thus, L3 of A. caninum and S. stercoralis exhibited negative geotaxis, crawling against the pull of gravity, while H. contortus did not. The biology of these parasites may explain these behavioural differences.

The effects of prednisolone were investigated in C57B1/6 mice infected with Strongyloides ratti. In primary infections, the numbers of adult worms in the small intestine and larvae in the stools were increased and there was a slight delay in the spontaneous expulsion of worms. In secondary infections, there was an initial suppression of acquired resistance, with larvae appearing normally in the stools on the 5th day after infection. This was followed, however, by a rapid development of resistance and expulsion of worms over the next few days. Prednisolone treatment did not alter fecundity in primary or secondary infections. There was no evidence of autoinfection in control or corticosteroid-treated animals. Prednisolone abrogated innate resistance to infection in C3H mice. It is concluded that prednisolone probably facilitated infection by non-specific mechanisms as well as by suppressing specific acquired immunity.

Various dosages of the microsporidian parasite, Nosema fumiferanae were fed to 12-day-old larvae of Choristoneura fumiferana using a previously undescribed bioassay capsule. A spore dose of 3 × 104 resulted in 92% infection and a significant reduction in pupal weights, adult female longevity and a mean spore concentration of 1·5 × 107/living adult. Significant mortality (68%, combined larvae and pupae) did not occur until larvae ingested 3 × 107 spores; this dose produced a mean of 1·8 × 107 spores in dead larvae and 3·6 × 107 and 4·6 × 107 spores in dead male and female pupae respectively.

Sporozoites of Plasmodium yoelii yoelii were incubated for 40 min with BALB/c peritoneal macrophages in the presence of nitro-blue tetrazolium (NBT). While immature oocyst sporozoites triggered the macrophage respiratory burst, as visualized microscopically by the localized reduction of NBT to insoluble formazan, 97·6% of mature salivary gland sporozoites did not induce such a response. The macrophage oxidative response was also induced by 82·7% of heat-inactivated and 95·7% of trypsin-treated salivary gland sporozoites. The relationship of these results to the infectivity and immunogenicity of malarial sporozoites is discussed.

Anaplasmosis is caused by a group of obligate intracellular bacteria in the genus Anaplasma, which are transmitted by ticks and infect humans, domestic animals and wildlife. This study was conducted to determine the prevalence and molecular characterization of Anaplasma spp. in semi-wild white yaks sampled in Tianzhu Tibetan Autonomous County, northwest China. Out of 332 samples tested, 35 (10·9%) were positive for Anaplasma spp. The positive rates were 6·2% (20/322) and 5·3% (17/322) for Anaplasma bovis and Anaplasma phagocytophilum in white yaks, respectively. None of the sample was positive for Anaplasma marginale. Two (0·6%) samples were simultaneously positive to A. bovis and A. phagocytophilum. Sequence analysis of the 16S rRNA gene revealed two genotypes (ApG1 and ApG2) of A. phagocytophilum and two sequence types (ST1 and ST2) of A. bovis in white yaks. This study is the first to document the presence of Anaplasma in white yaks. Our findings extend the host range for Anaplasma species and provide more valuable information for the control and management of anaplasmosis in white yaks.