Effects of cage contamination with coccidia and salmonella on acute salmonellosis in young chickens

The effects of concurrent cage contamination with Salmonella typhimurium and Eimeria tenella on the establishment of salmonella infection in day-old chickens were investigated. Chickens were divided into five groups: uninfected recipient birds placed in a cage contaminated by donor birds infected with E. tenella and S. typhimurium; E. tenella-infected recipients placed in a cage contaminated by S. typhimurium-infected donors; uninfected recipients placed in a cage contaminated by S. typhimurium-infected donors; E. tenella-infected recipients placed in a cage contaminated by uninfected donors; and uninfected recipients placed in a cage contaminated by uninfected donors. Three identical trials were conducted. Recipient birds were necropsied 4, 7, and 11 days after caging. In the cage where donor birds infected with both organisms had been reared, S. typhimurium counts in feces and number of feces positive for S. typhimurium were significantly (P less than 0.05) greater than those in the other cages on days 0, 4, and 7 after caging. Moreover, in this cage, more chicks died, counts of S. typhimurium in cecal contents were greater, and more birds were positive for S. typhimurium than in the other groups. This suggests that S. typhimurium infection in day-old chickens is enhanced in cages contaminated with E. tenella and S. typhimurium compared with infection in cages contaminated with S. typhimurium alone.     

Neurotoxins in a toxic red tide of Heterosigma akashiwo (Raphidophyceae) in Kagoshima Bay, Japan

In April 1995, an unusual large-scale red tide of Heterosigma akashiwo (Hada) Hada occurred, causing massive fish kills in Kagoshima Bay, Japan. Four neurotoxic components, HaTx-i , HaTx-ii a, HaTx-ii b and HaTx-iii , which corresponded to brevetoxin components. PbTx-2. PbTx-9, PbTx-3 and oxidized PbTx-2, were inferred from analysis of Heterosigma red tide toxins on TLC and HPLC.     

Therapeutic effect of Berenil and Samorin in mice infected with four trypanosome populations isolated from Zambian cattle

Four populations of Trypanosoma congolense and Trypanosoma brucei brucei were isolated from cattle under different management practices and environments in Zambia. All four isolates had varied responses to both diminazene aceturate (Berenil) and isometamidium chloride (Samorin) as curative drugs in infected mice. Trypanosomes from a traditionally managed herd in a high-tsetse-challenge area had the strains most resistant to Berenil, with maximum curative dose of 45 mg kg-1 body weight. Another isolate from a high-tsetse-challenge area was evidently resistant both to Berenil at 40 mg kg-1 and to Samorin at 4 mg kg-1. The strains most susceptible to both Berenil and Samorin were from a commercially managed herd of cattle under medium tsetse challenge. They responded to recommended cattle standard doses of 3.5 mg kg-1 or 7 mg kg-1 Berenil and to as little as 0.25 mg kg-1 Samorin. It is evident that trypanosome strains resistant to Berenil and/or partially resistant to Samorin exist, and that both T. congolense and T. b. brucei are implicated.     

Requirement of the activation-induced deaminase (AID) gene for immunoglobulin gene conversion

Three phenotypically distinct processes-somatic hypermutation, gene conversion, and switch recombination-remodel the functionally rearranged immunoglobulin (Ig) loci in B cells. Somatic hypermutation and switch recombination have recently been shown to depend on the activation-induced deaminase (AID) gene product. Here, we show that the disruption of the AID gene in the chicken B cell line DT40 completely blocks Ig gene conversion and that this block can be complemented by reintroduction of the AID complementary DNA. This demonstrates that the AID master gene controls all B cell-specific modifications of vertebrate Ig genes.     

Organ culture of chicken colon: physiological observations after 24 and 48 hours of culture

Colon from chickens, four weeks old, can best be maintained for 24 hours in a serum-free organ culture system using Trowell T8 medium-agar sheet at 25 degrees C. From physiological observations of DNA and protein synthesis it was found that the protein content of colonic explants did not change in up to 48 hours of culture while the DNA content did not change in up to 24 hours but decreased significantly to two thirds of the controls in 48 hours of culture. The organ culture system can be maintained satisfactorily for 24 hours.     

Expression and subcellular localization of GSE protein in germ cells and preimplantation embryos

We previously identified a novel gonad-specific expression gene (Gse) and investigated its expression during gametogenesis in the mouse testis and ovary. In this study, we generated a polyclonal antibody to GSE protein and determined the profiles of the protein's expression in germ cells and preimplantation embryos in detail using immunocytochemical and immunofluorescence staining. In a Western blot analysis, the anti-GSE antibody recognized long and short isoforms (approximately 27.6 kDa and 23.1 kDa) of the protein in the mouse testis and the long isoform in the ovary. In the mouse testis, GSE protein was expressed in spermatocytes I in the pachytene stage, round spermatids, and elongated spermatids. In the mouse ovary, the protein was located in the cytoplasm and nucleus of all oocytes regardless of the stage of the ovarian follicles. In preimplantation embryos from the pronuclear to blastocyst stage, however, GSE protein was mainly detected in the nuclei of cells. At the blastocyst stage, the protein was confirmed to have accumulated in the inner cell mass (ICM), whereas it had mostly disappeared from the trophectoderm (TE). These findings suggest that GSE protein may play a role in the establishment of nuclear totipotency and may be associated with early lineage specification.     

Molecular markers for genotyping anastomosis groups and understanding the population biology of Rhizoctonia species

Soil-borne Rhizoctonia fungi cause serious diseases in several plant species. For the classification of these fungi, the number of nuclei in a hyphal cell and the anastomosis reaction are important criteria. Although Rhizoctonia spp. has a wide host range, the causal agents have been reported to be selective for host plant families or species and lead to severe disease. Reports of new diseases, particularly in new host plants, and severe damage in agricultural fields incurred by subdivided or newly found groups of Ceratobasidium and Waitea circinata (a varied teleomorph of Rhizoctonia) have been increasing in recent years. The food production environment is altering because of climate change, introduction of potential new host plants, and heavy use of chemicals that reduce microbial diversity. These changes favor the occurrence of new diseases incurred by undefined anastomosis groups (AGs) or subgroups of Rhizoctonia spp. On the basis of the phylogenetic relationships of AGs and subgroups in Rhizoctonia spp., molecular markers for discriminating the groups of the Rhizoctonia species complex have been developed. The application of genetic markers, in the form of microsatellites or simple sequence repeats (SSR), has become increasingly important in fungal genetics. The analyses of population genetics for Rhizoctonia spp. using SSR markers elucidated the modes of sexual and asexual reproduction, phylogeographical distributions, and global migrations associated with adaptation to agroecosystems.