Toxoplasma gondii: Congenital transmission in a hamster model

The objective of the research was to test the hamster for a model of transmission of congenital toxoplasmosis. A non-invasive method for the diagnosis of pregnancy in hamsters was designed, with a specificity and a sensitivity of 70.2 and 94.7%, respectively (n = 168). Of 32 females with a chronic toxoplasma infection, 3 transmitted Toxoplasma congenitally during their first pregnancy, but not during the subsequent pregnancy. Congenital transmission rates of infections initiated during pregnancy with 2 stages of 2 strains of Toxoplasma were in the range of 33 to 100% of the 76 females inoculated. Only 1 of 17 females transmitted the parasite exclusively via milk. It was concluded that the hamster is a promising species for a model of transmission of congenital toxoplasmosis.     

Application of the survey protocol for chytridiomycosis to Queensland, Australia

Spread of the amphibian chytrid fungus Batrachochytrium dendrobatidis (Bd), which causes chytridiomycosis, has resulted in the extinction of frogs, but the distribution of Bd is incompletely known. We trialled the survey protocol for Bd by attempting to systematically map its distribution in Queensland, Australia. Bd was easily detected in known infected areas, such as the Wet Tropics and South East Queensland. It was not detected in bioregions adjacent to, but inland from or to the north of, infected regions: Einasleigh Uplands and Cape York adjacent to the infected Wet Tropics; and Brigalow Belt South adjacent to the infected South East Queensland bioregion. These regions where Bd was not detected have bordered infected regions for between 15 yr (in northern Queensland) and 30 yr (in southern Queensland), and so they define the geographical limits of Bd with regard to the long-term environmental conditions in Queensland. The Gulf Plains, a bioregion distant from infected bioregions, was also negative. Bd was confined to rainforest and bordering habitats, such as wet eucalypt forests. Infections were largely confined to permanent water-associated species, consistent with this being an important cause of this group having the greatest declines. Our data supports biogeographic climatic models that show much of inland and northern Australia to be too hot and dry to support Bd. As there is limited opportunity for Bd to spread further in Queensland, the priority for management is reducing the impact of Bd in affected populations and assisting frogs to disperse into their former distributions. Given that the survey protocol has been applied successfully in Australia it may be useful for mapping the distribution of Bd in other parts of the world.     

Effect of extraction condition on protein recovery and phenolic interference in Pacific dulse (Devaleraea mollis)

Pacific dulse (Devaleraea mollis), a type of red macroalgae, is of particular interest in the context of plant-based protein given its high protein content. One challenge in utilizing seaweed-derived protein is the poor protein recovery/yield and high cost that limits wider adaptation. In this study we aimed to evaluate methods for protein extraction from Pacific dulse to achieve a higher protein recovery rate. We evaluated the effect of cellulase treatment, under two extraction approaches, on the protein recovery and phenolic interference in Pacific dulse extracts. Commercial cellulases Viscozyme and Celluclast (2%, v/v) improved crude protein recoveries in both aqueous-alkaline and sequential protein fractionation approaches. The use of Osborne method to sequentially recover water-, saline-, alkaline-, and ethanol-soluble protein fractions resulted in more than a threefold increase in yield even at low-temperature conditions, mainly with the recovery of more protein in both albumin and globulin fractions. Without cellulase treatment, extending extraction time provides no improvement in protein yield but rather favors an increase in phenolic interference. Collectively, these results show that cellulase-aided sequential protein extraction can be used for improved protein recovery from Pacific dulse.

     

Dissociation of histone and DNA synthesis in x-irradiated HeLa cells

Although histone synthesis and DNA synthesis are normally very well coordinated in HeLa cells, their histone synthesis proved relatively resistant to inhibition by ionizing radiation. During the first 24 h after 1 000 R the rate of cellular DNA synthesis progressively fell to small fractions of control values while histone synthesis continued with much less relative reduction. Acrylamide gel electropherograms of the acid soluble nuclear histones synthesized by irradiated HeLa cells were qualitatively normal.     

Association of metallothionein expression and lack of apoptosis with progression of carcinogenesis in Barrett's esophagus

Barrett's esophagus is the transformation of normal esophageal squamous epithelium to specialized intestinal metaplasia (SIM). Among the Barrett's specialized cells, those that can develop protective mechanisms against apoptosis may have potential to become malignant. Studies have shown that overexpression of metallothionein (MT), low molecular protein that protects cells from apoptotic stimuli, appears to be associated with more advanced, highly malignant tumors. We thus investigated the relationship between MT expression and apoptosis in different stages of Barrett's carcinogenesis. Terminal deoxyribonucleotidyl transferase-mediated dUTP-digoxigenin nick end labeling and immunohistochemical dual-staining assay were performed in human biopsy samples of normal, SIM, dysplasia, and adenocarcinoma. Apoptotic index and MT expression were quantified by using an image system to analyze the converted digital data. A negative correlation between MT expression and apoptotic index was found. MT expression was significantly increased along with the histologic progression towards adenocarcinoma. This study thus suggests that MT may contribute to cytoprotection, thereby inhibiting apoptosis and leading to carcinogenesis of Barrett's esophageal cells.