Showing papers in "Journal of Parasitology in 1977"

Plasmodium falciparum in culture: use of outdated erthrocytes and description of the candle jar method.

Abstract: Plasmodium falciparum has been cultured continuously in a simplified technique using plastic petri dishes in a candle jar. This method has the advantage of being readily adaptable to many experiments, especially those requiring numerous replicates. Experiments using this method have allowed examination of some factors responsible for variations in parasite multiplication rates. Generally, fetal calf serum is not comparable to human serum, modifications to the RPMI 1640 medium are usually deleterious, and erythrocytes aged in citrated plasma are better for malarial cultures than freshly obtained cells; thus, erythrocytes outdated by blood-bank standards could provide a readily available supply of cells for large-scale production of malarial antigens. Continuous culture of Plasmodium falciparum in vitro was first obtained by a method providing for a slow flow of medium over a thin settled layer of human erythrocytes (Trager and Jensen, 1976; Trager, 1976). This method lends itself to partial automation and provides for continuous production of parasite material. It is not convenient, however, for the study of the many different factors that might affect growth of the parasites. For this purpose we developed a simplified method using plastic petri dishes in a candle jar. The essentials of this petri dish method have already been briefly described (Trager and Jensen, 1976). Here we present full details of the method and its application in demonstrating the feasibility of using outdated erythrocytes and for testing certain other modifications of the culture conditions. MATERIALS AND METHODS

Transovarially-transmitted intracellular microorganisms in adult and larval stages of Brugia malayi.

Abstract: Observation of intracellular organisms in the lateral chords of Brugia malayi adults initiated further studies to determine the prevalence of these organisms within the tissues of adult worms and of larvae. The organisms were found in the lateral chords of adult males and females, microfilariae, first-, second-, third-, and fourth-stage larvae. In the females, they were present in the oogonia, oocytes, and developing eggs, suggesting transovarial transmission within the life cycle of the filarid. The organisms may have a developmental cycle consisting of more than one stage, including a small spheroidal stage up to 0.6 micrometer in size and a larger form up to 1.5 micrometer in length, all of which occur in the cytoplasm within a vesicle formed of host membrane. Each stage lacks a definite cell wall, being bound by 2 trilaminate membranes. The bacterial entities in B. malayi resemble both in morphology and development the organisms found in other filarids, but whether they affect the vertebrate host in any way remains to be determined. Their presence within certain cells of the developing eggs could be exploited as intracellular markers for the organogenesis of the lateral chords and the ovary.

Keys to the genera of chiggers of the western hemisphere (acarina: trombiculidae).

Abstract: Synotpic keys to the 87 genera of chiggers in the Western Hemisphere (Nearctic and Neotropical regions) as well as illustrations to the terminology employed, are presented.

Decreased binding of cytotoxic antibody by developing Schistosoma mansoni. Evidence for a surface change independent of host antigen adsorption and membrane turnover.

Abstract: Schistosoma mansoni schistosomula maintained in chemically defined culture media became increasingly resistant to the cytotoxic effects of infected guinea pig serum. Two- and 6-day-old schistosomula recovered from mice showed no uptake of IgG antibody from infected guinea pig serum, as revealed by the indirect fluorescent antibody test. Results from this test remained negative when the schistosomula were tested at 0 C, after exposure to drugs which inhibit synthetic and secretory processes, or after being killed by heat or formalin. In contrast, new schistosomula collected within 3 hr after skin penetration bound IgG from infection serum under all test conditions, and showed increased susceptibility to cytotoxicity after exposure to various drugs. It thus appears that soon after skin penetration schistosomula undergo surface changes which prevent binding of antibody from infection serum. These changes can apparently take place in the absence of host antigens, and once they have occurred, do not depend on worm physiological processes for their function.

Glochidiosis of salmonid fishes. I. Comparative susceptibility to experimental infection with Margaritifera margaritifera (L.) (Pelecypoda: Margaritanidae).

Abstract: The comparative susceptibility of 4 species of salmonid fishes, 30.5 to 87.0 mm in fork length, to the glochidia of the freshwater mussel (Margaritifera margaritifera) was determined by ex- amination of 594 caged and 178 uncaged (native) fish for infection. Of the caged fish, 99% of the chinook salmon (Oncorhynchus tshawytscha), 75% of the coho salmon (Oncorhynchus kisutch), 88% of the cutthroat trout (Salmo clarki), and 95% of the steelhead trout (Salmo gairdneri) were infected. There was a similar relationship in infection incidence in the native fish species. Mean infection in- tensities in the caged and native fish were: 446 and 399 for chinook salmon, 8 and 24 for coho salmon, and 72 and 88 for steelhead trout, respectively, and 212 for caged cutthroat trout (native juvenile trout were not captured). Glochidia completed development in mussels in the Siletz River, Oregon, in 13 days at an average water temperature of 12.8 C. They were released by these mussels from 13 May to 15 June 1971. During development in fish, the parasites increased in length by 500% from an initial size of 70 to 75 tum. Encysted parasites occurred in the gill filaments, arches, rakers, and occa- sionally in the pseudobranchs of all fish species; but most were in the lamellae of the filaments. Initially, the cyst walls were approximately 15 tLm in thickness, but as the parasites increased in size the ex- posed part of the wall became thinner. Up to 15 lamellae may be fused to the wall. Except for lamellae "grasped" by the parasites, blood apparently continued to flow through capillaries of the fused lamellae, but these lamellae, except the outermost ones, probably no longer functioned in respiration. Parasites encysted on the sides of gill filaments restricted blood flow by "pinching" the arterioles. Large en- cysted parasites on the lamellae increased the physiological dead space in the water flow. Clubbing of the filaments resulted when large parasites were located distally. These pathological changes in heavy infections may result in early death of fish by asphyxiation. In less heavy infections, the invading or exiting parasites may provide portals of entry for fungi, and delayed mortality may occur from sec- ondary infection.

Experimental infection of bovines with oocysts of Toxoplasma gondii.

Abstract: Calves aged 3 months were readily infected with oocysts and cysts of Toxoplasma gondii administered by oral route. Fever, respiratory distress, nasal discharge and hyperemia of the conjunctivas were the most significant clinical signs noted in the infected animals. Parasitemia was demonstrated in all infected calves. It occurred on different days and up to 62 days after the infection. Toxoplasma was demonstrated in tissues of all infected calves, and the organ most frequently parasitized was the lymph node. Parasitism of the retina was demonstrated in two calves. All infected animals had antibody against T. gondii in their serum. The Sabin-Feldman dye test and the indirect immunofluorescent test were both useful in detecting antitoxoplasma antibody.

Nomenclature of Sarcocystis in the ox and sheep and of fecal Coccidia of the dog and cat.

Abstract: The nomenclature of Sarcocystis and related protozoan genera is reviewed, and modern diagnoses of the genera Isospora, Toxoplasma, Besnoitia, Sarcocystis, and Frenkelia in the coccidian family Eimeriidae are given. S cruzi (Hasselmann 1926) comb. n., S. hirsuta Moule 1888, and S. hominis (Railliet and Lucet 1891) comb. n. are recognized in the muscles of the ox Bos taurus; S. ovicanis Heydorn, Gestrich, Melhorn, and Rommel 1975, and S. tenella Railliet 1886 are recognized in the muscles of the sheep Ovis aries; S. bigemina (Stiles 1891) comb. n., S. cruzi, S. ovicanis, S. bertrami Doflein 1901, S. miescheriana (Kuhn 1865) Lankester 1882, I. ohioensis Dubey 1975, I. canis Nemeseri 1959, Isospora sp. n. Dubey, and Isospora sp. n. Trayser and Todd are recognized in dog (Canis familiaris) feces; and S. hirsuta, S. tenella, S. muris (Blanchard 1885) Labbe 1899, B. besnoiti (Marotel 1912) Henry 1913, Besnoitia sp. n. Frenkel, T. gondii (Nicolle and Manceaus 1908) Nicolle and Manceaux 1909, T. hammondi (Frenkel 1974) Levine and Nye 1976, I. rivolta (Grassi 1879) Wenyon 1923, and I. felis Wenyon 1923 are recognized in cat (Felis catus) feces. Hoareosporidium Pande, Bhatia, and Chauhan 1972 is considered a synonym of Sarcocystis.

Toxoplasmosis in nude mice.

Abstract: Immunity to the intracellular protozoan, Toxoplasma gondii, in mice is of the premunition type. Chemoprophylaxis with sulfadiazine normally permits mice to develop immunity to virulent organisms. However, nude (nu/nu) mice, which lack the thymus, failed to develop immunity to toxoplasma during 3 weeks of drug therapy while their hirsute littermates developed immunity during this period. When nude mice were injected intraperitoneally with thymus cells from hirsute littermates, they became able to develop immunity to toxoplasma during drug prophylaxis. The injection of bone marrow cells or high-titered specific antibody did not prolong survival after sulfadiazine was discontinued. Therefore, it appears that immunity to toxoplasma in mice is dependent upon active cellular immunity while the role of antibody is uncertain.

Changes in the virulence of Naegleria fowleri maintained in vitro.

Abstract: After a prolonged period of maintenance in Nelson's axenic medium, the HB-1 and C-66 strains of pathogenic Naegleria fowleri were observed to have lost their original virulence for mice. Cloned low virulence substrains were established and compared to cloned high virulence substrains that were maintained on monkey kidney cell (MKC) cultures. Some differences in physiology between the low virulence and high virulence substrains were shown by their growth in Nelson's medium and MKC cultures, cytopathic effects, catalase production, as well as in pathogenicity for mice inoculated intranasally. The importance of the identification of the factors which may contribute to the loss or acquisition of virulence of these "free-living" amebae is stressed. In the decade since primary amebic meningoencephalitis (PAM) caused by Naegleria spp. was first recognized, over 60 human cases have been reported and over 20 isolations of amebae have been made (Chang, 1974). A salient feature of these isolates is the almost uniform lack of reports of loss of virulence in culture. However, Chang (1971) reported the loss of cytopathic effects (CPE) caused by the WM (Virginia, USA) isolate of N. fowleri in tissue culture. More recently, Visvesvara and Callaway (1974) observed a decrease in the virulence for mice of the HB-1 (Florida, USA) and C-66 (or Carter 66, Australia) strains after intranasal inoculation. In a series of experiments in our own laboratories on the susceptibility of nonhuman primates to N. fowleri, variation in the virulence of axenically maintained HB-1 and C-66 strains was noted (Wong et al., 1975). In order to study some of the factors which might affect the virulence of these two strains, amebae were grown in axenic medium or tissue culture over a period of time and tested for animal virulence. This report summarizes the result of these experiments. MATERIALS AND METHODS The isolation and cultural history of the HB-1 and C-66 strains of N. fowleri used in this study have been reviewed elsewhere (Wong et al., 1975). Received for publication 18 February 1977. * Supported by Research Grant RR00169 from the NIH. t California Primate Research Center, University of California, Davis, California 95616. S Present address: Department of Nutrition and Food Science, University of Kentucky, Lexington, Kentucky 40506. Maintenance of cultures Cultures of the 2 strains of ameba were either m intained by continued passages in Nelson's axenic medium (NM) or in monkey kidney cell (MKC) monolayer cultures. The MKC were maintained in Leibowitz's L-15 medium with 2% v/v of fetal calf serum added. The L-15 was changed every 3 to 4 days. Subcultures in NM were carried out once a week and those in MKC every third day. At the beginning of this experiment, NM subcultures had been passaged about 50 times and those in MKC had been transferred over 170 times. Enhancement of strain virulence Two methods were employed to enhance virulence of uncloned populations of the HB-1 or C-66 amebae which had been maintained in NM: (1) by repeated transfers in MKC which selected out the high virulence population; and (2) by passages through mouse tissues via intranasal or intracerebral inoculation. E tablishment of clones Clones of amebae of HB-1 and C-66 strains were established by spreading dilute suspensions of trophozoites onto nonnutrient agar plates and picking the individual amebae from the surface with a pasteur pipette and the aid of a stereomicroscope. Each of the 10 amebae thus obtained was grown either in NM or MKC cultures and tested for CPE capability in MKC and pathogenicity in mice. Selected clones showing definite high or low virulence were designated as high virulence (HV) or low virulence (LV) substrains of the two strains of amebae.

Agitated mass cultivation of Naegleria fowleri.

Abstract: Large quantities (3 X 109 amebae/liter) of Naegleria fowleri were obtained in agitated cultures using a complex medium. Logarithmic growth occurred during the initial 36 hr and the mean generation time was 5.5 hr. The maximum cell yield was 3 X 108 amebae/ml. The pH of the medium increased during logarithmic and stationary growth and the pH optimum for growth initiation in agitated cultures was 5.5, and 6.5 in unagitated cultures. Oxygen tension decreased from 100% to 78% of saturation and amebae did not grow in a 90% N2, 10% CO2, oxygen-free atmosphere. Assays of the culture medium showed little utilization of glucose or other carbohydrates. These data suggest that N. fowleri has a predominantly aerobic metabolism and that it utilizes noncarbohydrate substrates as carbon and energy sources. Naegleria fowleri is an ameboflagellate which may undergo spontaneous cellular differentiation during stationary growth phase (Carter, 1970). It causes fatal amebic meningoencephalitis in humans (Carter, 1972; Duma et al., 1971). To date no definitive studies have been reported concerning its axenic cultural characteristics or physiology although such studies deal with related amebae (Fulton, 1970; O'Dell and Brent, 1974). However, several axenic media have been reported (Cerva, 1969; Chang, 1974; Wong et al., 1975). Naegleria fowleri has been difficult to obtain in sufficient quantities for biochemical analyses. In this study we describe growth conditions which support consistent and maximum yields of N. fowleri during agitated axenic mass cultivation. MATERIALS AND METHODS

Studies on the ecology of the tick Amblyomma hebraeum Koch in the Eastern Cape Province of South Africa. II. Survival and development.

Abstract: Quantitative data are given on the survival and rate of development of Amblyomma hebraeum Koch in relation to temperature and humidity, in laboratory and field conditions. By comparison with other ixodid species the developmental periods of A. hebraeum are extremely long. Development is most rapid at 30 C, and the duration of the developmental periods increases exponentially with decreasing temperature. Oviposition occurs successfully at 15 and 30 C, egg incubation at 20 to 30 C, and larval and nymphal molting at 15 to 35 C. The ability of the developing stages to survive in dry conditions increases with increasing size, i.e. from egg to engorged larva. Mortality in the developing stages increases at low humidities as temperature decreases, due to the longer periods over which water is lost. The conversion efficiency of ovipositing females is influenced by both temperature and atmospheric humidity. Longevity of unfed larvae is correlated directly with saturation deficit. Longevity of unfed nymphs and adults is dependent on both temperature and saturation deficit.

Characterization and isolation of concanavalin A binding sites from the epidermis of S. mansoni.

Abstract: Using concanavalin A labeled with tritium and fluorescein isothiocyanate we studied the binding properties of this plant lectin to adult paired schistosomes. Using concanavalin A coupled to a sepharose column we attempted to isolate and characterize concanavalin A binding molecules from the epidermis of adult schistosomes. Our results indicate the presence of specific concanavalin A binding sites on the surface of adult Schistosoma mansoni. A significant percentage of the concanavalin A was specifically bound and showed characteristics similar to that identical in other concanavalin A binding tissues. The parasite's concanavalin A binding sites appear to be 2 or 3 high molecular weight glycoproteins. There is some indication that glycoproteins associated with the worm's epidermis function as enzyme(s). The immunological significance of these glycoproteins has not been determined.

Lectin and human blood group determinants of Schistosoma mansoni: alteration following in vitro transformation of miracidium to mother sporocyst.

Abstract: A mixed agglutination assay method was employed to detect the presence of surface determinants for various lectins and human blood group antibodies on Schistosoma mansoni miracidia and cultured mother sporocysts. Miracidia were found to possess surface receptors for the lectins Con A (concanavalin A), anti-Heel (eel serum agglutinin), and anti-ADb (Dolichos seed extract), as well as human anti-A antibodies. Following in vitro transformation of the miracidium to mother sporocyst, anti-Heel and human anti-A receptors were no longer detectable on the sporocyst surface, while determinants for Con A and anti-ADb remained essentially unaltered. It is concluded that transition of the miracidium to the sporocyst results in the alteration of surface molecular structures on schistosome larve. Furthermore, since determinants for Con A, anti-Heel, anti ADb, and human anti-A have been found associated with macromolecules in the hemolymph of the snail Biomphalaria glabrata (Stnislawski et al., 1976), there is now evidence that miracidia and mother sporocysts of S. mansoni and their snail host share molecules with common lectin and human blood group determinants.

The Organization of nematodes

Abstract: THE ORGANIZATION OF NEMATODES , THE ORGANIZATION OF NEMATODES , کتابخانه مرکزی دانشگاه علوم پزشکی ایران

Ecology of the tick Amblyomma hebraeum Koch in the Eastern Cape Province of South Africa. I. Distribution and seasonal activity.

Abstract: In the Eastern Cape Province of South Africa larvae of Amblyomma hebraeum Koch occur in well-drained, shaded habitats, with a ground cover of grass. The life cycle is normally of 3 years duration. Peak larval activity occurs in the summer of the 1st year, peak nymphal activity in the spring of the 2nd year, and peak adult activity in the summer of the 3rd year. Larval activity shows no direct correlation with macroclimate. Adult activity is correlated with, in the following order of signficance, daylength, temperature, and rainfall. Nymphal activity appears to be regulated by the same factors.

Ultrastructure of Pharyngostomoides procyonis Harkema 1942 (Diplostomatidae). II. The female reproductive system.

Abstract: Several components of the female reproductive system of Pharyngostomoides procyonis, including the vitellaria and vitelline duct, ovary and oviduct, Laurer's canal, and Mehlis' gland and associated ducts, were observed with the electron microscope. Vitelline follicles contain cells in various stages of development. Mature vitelline cells contain membrane-delimited clusters of vitelline globules near the plasma membrane. Cilia are present in the vitelline duct. The ovary contains germ cells in various stages of maturation. Oogonia are found in the peripheral region. Mature oocytes contain numerous dense bodies near the plasmalemma. Also included in the cytoplasm of mature oocytes are "nucleolus-like bodies," myelin-like bodies, and mitochondria containing dense granules and few cristae. The epithelium of the oviduct is ciliated. Sperm are present in the oviduct and in Laurer's canal. Two types of secretory cells found in Mehlis' gland are described.

Sheep experimentally infected with sarcocystis from dogs. I. Disease in young lambs.

Abstract: Eight Polled Dorset lambs were orally inoculated with Sarcocystis ovicanis sporocysts. Two lambs that received 100,000 or 200,000 sporocysts became clinically ill, recovered, and were killed 67 and 88 days after inoculation (DAI). Numerous intramuscular cysts were found in their skeletal and cardiac muscles. Three lambs received 100,000 sporocysts, three lambs received 1 million sporocysts, and three lambs received no sporocysts. After an acute clinical illness characterized by anemia, inappetence, weight loss, fever, and reduced serum protein, all lambs that received 100,000 sporocysts died 27 to 29 DAI and all that received 1 million sporocysts died 24 or 25 DAI. Hemorrhage involving the striated muscle and visceral organs was the most apparent gross lesion. The heart appeared most severely affected. Schizonts were found in vascular endothelial cells of all six inoculated lambs. Uninoculated lambs remained healthy, and neither lesions nor parasites were found in any tissues. Dogs fed tissues containing S. ovicanis cysts produced sporocytes 11 to 37 days after feeding; cats fed similar stages produced no sporocysts. Dogs fed tissues containing schizonts produced no sporocysts.

Besnoitia darlingi (Protozoa: Toxoplasmatinae): cyclic transmission by cats.

Abstract: Two of five opossums examined from the Kansas City area were found to be infected with Besnoitia darlingi. Inoculation of cysts resulted in acute lethal infections in mice and hamsters. Chronic infections with development of tissue cysts were obtained in mice by prophylaxis with sulfadiazine. Cysts were fed to cats and a dog which resulted in the shedding of isosporoid oocysts by cats. The prepatent period was 11 to 14 days. Unsporulated oocysts averaged 11.9 by 12.3 micrometer and sporulated in 48 to 72 hr. Mouse-to-mouse tramsmission was achieved by injecting triturated tissue containing cysts. This is the third species of Besonitia to be cyclically transmitted by cats.

Sarcocystis fayeri sp. n. from the horse.

Abstract: Hearts, diaphragms, esophagi, and spinal cords from 266 horses were obtained at slaughter in Creston, Ohio. Tissues were examined microscopically for Sarcocystis in sections, digested in trypsin to obtain bradyzoites, and fed to 10 dogs and 10 cats. Intramuscular cysts were found in selections of two hearts from 57 horses and four esophagi from 107 horses. The cysts were up to 900 micron long and up to 70 micron wide. The cyst wall was 1 to 2 micron thick and cross-striated. The enclosed bradyzoites were banana-shaped, 15 to 20 by 20 to 3 micron, and contained several PAS-positive granules. Bradyzoites were found in trypsin digests of seven of 57 (13%) equine tissues (heart, diaphragm, esophagus but not spinal cord) in one experiment and 10 of 47 (21%) esophagi, eight of 47 (17%) diaphragms but none of 47 hearts and spinal cords in another experiment. All of 10 dogs shed sporulated sporocysts or oocysts in feces 12 to 15 days (12 in one, 13 in eight, and 15 days in one) after digesting tissues from 169 horses. The sporocysts were 11 to 13 (12.0 +/- 0.5) by 7 to 8.5 (7.9 +/- 0.5) micron. In histologic sections of canine small intestine the sporocysts were located in the lamina propria near the tips of the villi. The 10 cats fed tissues from 266 horses did not shed Sarcocystis. A new name, S. fayeri, is proposed for this organism. Sarcocystis fayeri sporocysts (12 by 8 micron) are shorter than those of S. betrami (15 by 10 micron), the other species of Sarcocystis from the horse. The prepatent period is 12 to 15 days for S. fayeri and 8 days for S. bertrami (synonym S. equicanis Rommel and Geisel 1975).

Ecology of Capillaria hepatica (Bancroft 1893) (Nematoda). 1; Dynamics of infection among Norway rat populations of the Baltimore Zoo, Baltimore, Maryland.

Abstract: Seventy-five per cent of 845 Norway rats examined in the Baltimore Zoo for Capillaria hepatica were infected. Nearly all adult rats and 65% of juveniles were infected. Only 8% of 299 infected rats were heavily infected. The prevalence and intensity of infection increased with the size of the host. There were no seasonal differences in infection rates among adults, but juveniles collected during spring had higher infection rates than those collected during winter. Prevalence of C. hepatica infection varied from one place to another. No correlation between infection rate, vegetative cover, soil type, monthly rainfall, mean daily temperature, or food habits of rats was found. The dynamics of rat populations are perhaps the most important factors in the maintenance and dynamics of C. hepatica infections. Rapid population turnover contributes to the rapid release of a great number of eggs into the environment and high recruitment rates provide sufficient numbers of susceptible hosts for the parasite to complete its cycle.

Lipids of Plasmodium lophurae, and of erythrocytes and plasma of normal and P. lophurae-infected Pekin ducklings.

Abstract: A lipid analysis was performed on the avian malaria parasite Plasmodium lophurae, freed from duckling erythrocytes by immune hemolysis, and on the erythrocytes and plasmas of normal and P. lophurae-infected ducklings. Major lipids of normal erythrocytes were: phosphatidylcholine (40% of total lipids), phosphatidylethanolamine (20%), cholesterol (20%), sphingomyelin (11%), and glycosphingolipids (5%). Major fatty acids of erythrocyte total phospholipids (74% of total lipids) were 16:0 (22%), 18:2 (n-6) (21%), 18.1 (n-7, n-9) (18%), 18:0 (9%), 20:4 (n-6) (9%), 22:6 (n-3) (5%). Erythrocyte phosphatidylcholine was greater than 90% the diacyl form, while phosphatidylethanolamine was approximately 44% alkoxy forms and phosphatidylinositol approximately 11% alkoxy forms. Major fatty aldehydes of phosphatidylethanolamine were 16:0 (47%), 18:1 (23%), 18:0 (14%), and 14:0 (12%). The lipid composition of P. lophurae (plus the parasitophorous vacuole membrane) was qualitatively and quantitatively different from that of the duckling erythrocyte in a number of respects. Major lipids were phosphatidylcholine (40%), phosphatidylethanolamine (36%), cholesterol (8%), phosphatidylinostol (4%), 1,2-diacylglycerols (3%), sphingomyelin (2%), and glycosphingolipids (2%). Diphosphatidylglycerol (approximately 1%) was also detected. The major fatty acids of parasite total phospholipids (86% of total lipids) were more saturated than those of the erythrocyte, and octadecenoic acids were notably elevated: 18:1 (33%), 16:0 (26%), 18:0 (16%), 18:2 (12%), 20:4 (3%), and 22:6 (3%). Parasite phosphatidylcholine and phosphatidylethanolamine were greater than 93% the diacyl form and phosphatidylinositol was approximately 25% alkoxy forms. Major fatty aldehydes of the phosphatidylethanolamine were 14:0 (62%), unidentified long chain forms (24%), 16:0 (7%), 18:0 (4%), 18:1 (3%). The lipid composition of the infected erythrocyte reflected the separate contributions of the erythrocyte and parasite. The major lipids of normal duckling plasma were phosphatidylcholine (33%), triacylglycerols (22%), cholesterol esters (20%), cholesterol (12%), phosphatidylethanolamine (5%), and sphingomyelin (2%). The fatty acids of plasma total lipids were 18:1 (26%), 16:0 (26%), 18:2 (12%), 20:4 (12%), 18:0 (9%), 22:6 (3%). Plasma phosphoglycerides were remarkably lower in C18 unsaturated fatty acids and higher in 20:4 than the erythrocyte phosphoglycerides. Infection of ducklings with P. lophurae caused increases in plasma unesterified fatty acids, triacylglycerols and cholesterol esters, and a notable rise in the 18:1 content of all fatty acid-containing plasma neutral lipids. These findings are compared with those reported for other species of Plasmodium infecting other avian and mammalian hosts.

Search for the presence of lectin-binding sites on Toxoplasma gondii.

Abstract: Evidence for the presence of carbohydrate on the surface membrane of Toxoplasma gondii trophozoites and on the cell wall of toxoplasma brain cysts was sought by fluorescent lectin staining. Using FITC-conjugated preparations of Concanavalin A (Con A), wheat germ agglutinin (WGA), or soy bean agglutinin (SBA), we have failed to obtain evidence for the binding of these lectins on the surface of T. gondii trophozoites. In contrast, the three test lectins bound effectively and specifically to the wall of toxoplasma brain cysts. Prefixation of cysts with glutaraldehyde or brief trypsinization of cysts did not affect the intensity of cyst wall fluorescence when stained with FITC-conjugated Con A, SBA, or WGA. The results are interpreted to indicate that whereas exposed Con A, SBA, and WGA binding sites are associated with the wall of toxoplasma brain cysts, such lectin-binding saccharide residues are not present on the surface of trophozoites in exposed or reactive form.

Stereoscan studies of cercariae, metacercariae, and adults of Cryptocotyle lingua (Creplin 1825) Fischoeder 1903 (Trematoda: Heterophyidae).

Abstract: The cercaria of Cryptocotyle lingua has simple pointed spines all over the body. Four pointed modified spines occur dorsally in the mouth, and similar spines surround the openings of the penetration glands. The modified spines are shed shortly after penetration and encystment in the fish host. Less than a week after encystment, cytoplasmic folds develop all over the tegument. After about 4 weeks the cytoplasmic folds have disappeared and the spines are now flattened and serrated. The external surface of adults from herring gulls is very similar to that of mature metacercariae. It is provided with scalelike serrated spines which are especially well developed ventrally on the anterior end.

Studies on the Santa Lucia (El Salvador) strain of Plasmodium falciparum in Aotus trivirgatus monkeys.

Abstract: The Santa Lucia strain of Plasmodium falciparum was isolated from El Salvador, Central America, and established in Aotus trivirgatus monkeys. Transmission from monkey to monkey via the bites of infected Anopheles freeborni, A. maculatus, and A, albimanus mosquitoes was obtained in 20 of 27 attempts. Prepatent periods in the monkeys ranged from 17 to 46 days with a mean of 24.3 days. Parasitemias and mortality were higher following sporozoite inoculation into animals which had been previously infected with P. vivax than in those with no previous malaria experience. Monkeys previously infected with P. vivax and P. cynomolgi had lower maximum parasitemias than those previously infected with P. vivax only.

Cytology, reproduction, and sex determination of Strongyloides ransomi and S. papillosus.

Abstract: Parasitic females of Strongyloides ransomi and Strongyloides papillosus have 4 chromosomes and reproduce exclusively by mitotic (apomictic) parthenogenesis. The free-living generation includes females and males. The females have 2 pairs of chromosomes of unequal size and reproduce by meiotic parthenogenesis following obligatory pseudofertilization (gynogenesis). The males undergo spermatogenesis by the regular meiotic process and have the same chromosomal complement as the females. During prophase I, however, a portion of one homologue of the large bivalent breaks free and subsequently is diminished, as in S. ransomi, or it rejoins the original homologue, as in S. papillosus. This behavior of meiotic chromosomes during spermatogenesis suggests that the karyotype of these species has evolved from a karyotype analogous to that of Strongyloides ratti with 2 pairs of autosomes and a pair of X chromosomes, following fusion of the X chromosome with an autosome and the formation of a Neo-X and a Neo-Y chromosome. The female karyotype of S. ransomi and S. papillosus thus may be 2A + 2 Neo-X. The males are phenotypic males and have the same karyotype as the females, but their functional karyotype may be 2A + Neo-X + Neo-Y.