Fatal perinatal sarcocystosis in a lamb

A 3-wk-old lamb died because of neurological disease. The predominant microscopic lesions were in the brain and spinal cord and consisted of nonsuppurative encephalomyelitis with severe gliosis throughout the gray and white matter. Immature and mature schizonts, 15.7 x 10.6 microns (8-30 x 6-18 microns), occurred in capillaries and were structurally similar to those of Sarcocystis tenella.     

T Cell Factor-1 Controls the Lifetime of CD4+ CD8+ Thymocytes In Vivo and Distal T Cell Receptor α-Chain Rearrangement Required for NKT Cell Development

Natural killer T (NKT) cells are a component of innate and adaptive immune systems implicated in immune, autoimmune responses and in the control of obesity and cancer. NKT cells develop from common CD4+ CD8+ double positive (DP) thymocyte precursors after the rearrangement and expression of T cell receptor (TCR) Vα14-Jα18 gene. Temporal regulation and late appearance of Vα14-Jα18 rearrangement in immature DP thymocytes has been demonstrated. However, the precise control of lifetime of DP thymocytes in vivo that enables distal rearrangements remains incompletely defined. Here we demonstrate that T cell factor (TCF)-1, encoded by the Tcf7 gene, is critical for the extended lifetime of DP thymocytes. TCF-1-deficient DP thymocytes fail to undergo TCR Vα14-Jα18 rearrangement and produce significantly fewer NKT cells. Ectopic expression of Bcl-x_L permits Vα14-Jα18 rearrangement and rescues NKT cell development. We report that TCF-1 regulates expression of RORγt, which regulates DP thymocyte survival by controlling expression of Bcl-x_L. We posit that TCF-1 along with its cofactors controls the lifetime of DP thymocytes in vivo.     

The ossification centers in the lower end of tibiotarsus in domestic fowl.

The morphogenesis of lower end of tibia in chick is studied commonly but the process of ossification of the same has received very little attention so far. The present study is directed to throw some light on the appearance of ossification centers in the lower end of tibiotarsus of chick. The histology of lower end of tibiotarsus was studied by procuring developing tibiotarsi from chick embryos (20) of 6th day incubation till hatching and 3 post hatched chicks. The transparancies of chick embryos at different incubation periods and post hatched chicks were prepared by Dawson's Alizarin staining method. Three cartilage center (tibial, fibulare and intermedium) appeared in 6...9 days of incubation period in the tarsal region. These gradually fused with the lower end of tibia. Three ossification centres developed in the lower end of tibiotarsus. One for intermedium appeared on 16th day and two fotibial and fibulare on 20th day. All these three centres could be located in the transparancies of the chick embryos in tarsal region. The present study proves that the three cartilages centres maintain their individuality during the ossification process even though those fuse completely with the lower end of tibia in chick. The centers for tibial and fibulare are similar to epiphyseal centres of mammals in histological details.     

An unusual structure in the primary cyst wall of Sarcocystis hemionilatrantis

Disc-shaped plaques were found in the primary cyst wall of sarcocysts of Sarcocystis hemionilatrantis in mule deer in Montana. Ultrastructurally, the plaques were 190.5 nm in diameter, 161.6 nm thick and consisted of six distinct layers with microfilaments arising from the innermost layer. These unusual plaques have not been reported previously for any species of Sarcocystis.     

Bimodal oxygen uptake in a freshwater air-breathing fish,Notopterus chitala

Measurements of bimodal oxygen uptake have been made in a freshwater air-breathing fish,Notopterus chitala at 29.0±1(S.D.)°C. xhe mean oxygen uptake from continuously flowing water without any access to air, was found to be 3.58±0.37 (S.E.) ml O₂ · h^?1 and 56.84+4.29 (S.E.) ml O₂ · kg^?1 · h^?1 for a fish weighing 66.92 + 11.27 (S.E.) g body weight. In still water with access to air, the mean oxygen uptake through the gills were recorded to be 2.49 ± 0.31 (S.E.) ml O₂ · h^?1 and 38.78 ± 1.92 (S.E.) ml O₂ · kg^?1 · h^?1 and through the accessory respiratory organs (swim-bladder) 6.04±0.87 (S.E.) ml O₂ · h^?1 and 92.32±2.91 (S.E.) ml O₂ · kg^?1 · h^?1 for a fish averaging 66.92±11.27 (S.E.) g. Out of the total oxygen uptake (131.10 ml O₂ · kg^?1 · h^?1), about 70% was obtained through the aerial route and the remainder 30% through the gills.     

Toxoplasma gondii: Microassay to differentiate toxoplasma inhibiting factor and interleukin 2

Using a sensitive, economical, and reproducible microassay, the relationship of toxoplasma inhibiting factor to interleukin 2 has been examined. The assay developed took advantage of the observation that (1) Toxoplasma gondii tachyzoites replicated efficiently in the murine monocytic cell line, RAW 264; (2) treatment of RAW 264 cells with toxoplasma inhibiting factor prevented intracellular replication of the parasite to an extent similar to that observed with identical treatment of freshly isolated murine peritoneal exudate cells; and (3) [³H]uracil incorporation was an efficacious means to quantify replication (or inhibition of replication) of tachyzoites within the cell line. Although toxoplasma inhibiting factor and interleukin 2 were both present in the same lectin -and antigen-stimulated splenocyte supernatant fluids, results from microassays strongly suggested that the molecules were two distinct entities.     

Effect of high temperature on infectivity of Toxoplasma gondii tissue cysts in pork

To study the effect of high temperature on infectivity of Toxoplasma gondii tissue cysts, pork from infected pigs was mixed with infected mouse brains and homogenized thoroughly. Twenty-gram samples of infected homogenized meat were sealed in plastic pouches, pressed to a uniform thickness of 2 mm, and subjected to water-bath temperatures of 49, 52, 55, 58, 61, 64, and 67 C for 0.01, 3, 6, 9, 12, 24, 48, and 96 min. Treated samples were digested in HCl-pepsin solution and bioassayed in mice. Toxoplasma gondii tissue cysts remained viable at 52 C for 9.5 min but not for 9.5 min at 58 C; tissue cysts were generally rendered nonviable by heating to 61 C or higher temperature for 3.6 min. Tissue cysts survived once at 64 C for 3 min. These data demonstrate that T. gondii tissue cysts are less heat resistant than encysted Trichinella spiralis larvae.     

Neospora caninum (Apicomplexa) in an aborted equine fetus

Tachyzoites of Neospora caninum were found in sections of lung of an equine fetus aborted 2 mo before term. Individual tachyzoites were approximately 3-5 x 2-3 microns, divided by endodyogeny, and stained positively with anti-N. caninum serum but not with anti-Toxoplasma gondii serum. Toxoplasma gondii antibody was not found in the mare's serum. This is the first report of N. caninum in a horse and indicates that N. caninum can be transmitted transplacentally in equids.     

Enzootic toxoplasmosis in sheep in north-central United States

Of 1,564 serum samples from adult ewes from 33 farms in Iowa, Minnesota, South Dakota, Kansas, and Nebraska where toxoplasmosis-induced ovine abortions had been diagnosed, 65.5% were found positive for Toxoplasma gondii antibodies using the modified agglutination test. Toxoplasma gondii antibody titers of ewes were: less than 64 (34.5%), 64 (14.9%), 256 (22.0%), 1,024 (14.5%), and greater than 4,096 (13.8%). Thus, 28.3% of sheep had high titers (greater than 1,024) indicating recently acquired T. gondii infection. On certain farms, up to 95% of ewes were seropositive. Prevalence of T. gondii antibodies increased with age of the ewe. Of 665 ewes, 53.6% of 1-yr-old ewes were seropositive (titers greater than 64) versus 75% of 5-yr-old ewes. Results indicate that T. gondii infection in sheep in the United States is widespread.