N-carboxymethylchitosan: Algistatic and algicidal properties

Summary A water soluble agent made from waste crustacean shells that controls the growth of algal cells was identified. Growth of an Anabaena sp. was inhibited in the presence of varied concentrations of a chitosan-derivative, N-carboxymethylchitosan (NCMC). Application of a dilute water solutions of NCMC prevented algae from multiplication and enhanced aggregation of cells and assured clearing of algal suspension by filtration.     

Three distinct H-2Ks molecules differing at the carboxy terminus are expressed on a tumor from SJL/J mice

A dimethylbenzanthracene-induced leukemia of H-2s origin expressed at least two class I molecules on the cell surface that were precipitated by anti-H-2.19, an alloantiserum prepared against the private H-2Ks specificity. Mapping studies in recombinant inbred strains along with comparisons of tryptic peptide maps and N-terminal sequences indicated that the proteins were virtually identical and probably encoded by the same class I gene. When cells were labeled in the presence of tunicamycin, the proteins precipitated by anti-H-2.19 were further resolved into three distinct peptides. Experiments were performed to determine which of these various proteins were phosphorylated and which were recognized by an anti-synthetic peptide serum directed against the ultimate C-terminus of H-2K class I molecules. The results indicate that a single class I gene from the H-2Ks region may encode three class I molecules that differ only at the C-terminus due to alternative splicing of pre-mRNA.     

Genetic factors controlling the susceptibility to experimental autoimmune thyroiditis in inbred rat strains

CDF (high responder) rats were crossed with SHR (low responder) rats to study genetic factors influencing susceptibility to experimental autoimmune thyroiditis (EAT). F1 hybrid rats showed intermediate susceptibility to thyroiditis. Gene segregation patterns of F2 and backcross rats demonstrated that the immune response to rat thyroglobulin (RaTg) is under polygenic control. A main factor controlling immune response to RaTg is associated with the X chromosome. Females of CDF and SHR rats produced higher levels of antibody, suggesting that antibody production to RaTg is a sex-influenced trait. Different genetic control mechanisms are evident in autoantibody production and thyroid lesions. No evidence of linkage of an immune response gene to RaTg to the major histocompatibility complex of the rat (RT1) was observed.     

Genetic regulation of MUC1 expression by Helicobacter pylori in gastric cancer cells

Helicobacter pylori infection of the stomach is associated with the development of gastritis, peptic ulcers, and gastric adenocarcinomas, but the mechanisms are unknown. MUC1 is aberrantly overexpressed by more than 50% of stomach cancers, but its role in carcinogenesis remains to be defined. The current studies were undertaken to identify the genetic mechanisms regulating H. pylori-dependent MUC1 expression by gastric epithelial cells. Treatment of AGS cells with H. pylori increased MUC1 mRNA and protein levels, and augmented MUC1 gene promoter activity, compared with untreated cells. H. pylori increased binding of STAT3 and MUC1 itself to the MUC1 gene promoter within a region containing a STAT3 binding site, and decreased CpG methylation of the MUC1 promoter proximal to the STAT3 binding site, compared with untreated cells. These results suggest that H. pylori upregulates MUC1 expression in gastric cancer cells through STAT3 and CpG hypomethylation.     

Eimeria tenella and E. acervulina: lymphokines secreted by an avian T cell lymphoma or by sporozoite-stimulated immune T lymphocytes protect chickens against avian coccidiosis

The role of avian lymphokines as nonspecific immunomodulators of host immunity against the intracellular parasite Eimeria was investigated. Prophylactic treatment of normal chickens with crude cell-free supernatants obtained from JMV-1 culture, concanavalin A (Con A)-stimulated normal spleen cells, or sporozoite-stimulated immune T cells prior to inoculation with E. tenella or E. acervulina conferred significant protection. These crude cell-free culture supernatants also inhibited intracellular development of eimerian parasites in vitro. Avian macrophages pretreated with these supernatant preparations showed inhibitory activity against Eimeria. This inhibitory activity could not be ascribed to anti-Eimeria antibody, complement, or cell-free Marek's disease virus and was therefore considered to be due to immunomodulating lymphokines present in the culture supernatants. These results suggest that JMV-1-transformed T lymphoblastoid cells, immune T lymphocytes, and Con A-stimulated normal spleen cells secrete lymphokines that can enhance host immunity in a nonspecific manner and implicate cell-mediated immunity as a major mechanism of the protective host immune response against eimerian infections.     

Mapping and genotypic analysis of the NK-lysin gene in chicken

Background

Antimicrobial peptides (AMP) are important elements of the first line of defence against pathogens in animals. NK-lysin is a cationic AMP that plays a critical role in innate immunity. The chicken NK-lysin gene has been cloned and its antimicrobial and anticancer activity has been described but its location in the chicken genome remains unknown. Here, we mapped the NK-lysin gene and examined the distribution of a functionally significant single nucleotide polymorphism (SNP) among different chicken inbred lines and heritage breeds.

Results

A 6000 rad radiation hybrid panel (ChickRH6) was used to map the NK-lysin gene to the distal end of chromosome 22. Two additional genes, the adipocyte enhancer-binding protein 1-like gene (AEBP1) and the DNA polymerase delta subunit 2-like (POLD2) gene, are located in the same {"type":"entrez-nucleotide","attrs":{"text":"NW_003779909","term_id":"358468969","term_text":"NW_003779909"}}NW_003779909 contig as NK-lysin, and were thus indirectly mapped to chromosome 22 as well. Previously, we reported a functionally significant SNP at position 271 of the NK-lysin coding sequence in two different chicken breeds. Here, we examined this SNP and found that the A allele appears to be more common than the G allele in these heritage breeds and inbred lines.

Conclusions

The chicken NK-lysin gene mapped to the distal end of chromosome 22. Two additional genes, AEBP1 and POLD2, were indirectly mapped to chromosome 22 also. SNP analyses revealed that the A allele, which encodes a peptide with a higher antimicrobial activity, is more common than the G allele in our tested inbred lines and heritage breeds.     

Evolutionary basis and ecological role of toxic microbial secondary metabolites

This presentation develops a theory of the evolutionary origin and ecological implications of toxic microbial secondary metabolites. The theory is based on a model system that outlines cause—effect associations between pertinent biotypes in the aflatoxin contamination of developing maize kernels. The model suggests that the aflatoxin-producing fungi are natural digestive tract inhabitants of a number of insect species that feed on developing kernels. During feeding, the insect larvae introduce fungal propagules and provide infection sites on damaged kernels. The fungal association with insects exhibits extraordinary variability, ranging from symbiotic to pathogenic. Elaboration of aflatoxin by the fungus facilitates the pathogenic process in host insects. The theory contends that genetic information for secondary microbial metabolites evolved during ecosystem disequilibria. During periods of ecological stability, mechanisms evolved for repression of toxic secondary metabolite biosynthesis. The theory broadly suggests that contemporary agricultural activities presents the requisite milieu for production or toxic microbial secondary metabolites.     

The conduction of protons in different stereoisomers of dioxolane-linked gramicidin A channels

Two different stereoisomers of the dioxolane-linked gramicidin A (gA) channels were individually synthesized (the SS and RR dimers;. Science. 244:813-817). The structural differences between these dimers arise from different chiralities within the dioxolane linker. The SS dimer mimics the helicity and the inter- and intramolecular hydrogen bonding of the monomer-monomer association of gA's. In contrast, there is a significant disruption of the helicity and hydrogen bonding pattern of the ion channel in the RR dimer. Single ion channels formed by the SS and RR dimers in planar lipid bilayers have different proton transport properties. The lipid environment in which the different dimers are reconstituted also has significant effects on single-channel proton conductance (g(H)). g(H) in the SS dimer is about 2-4 times as large as in the RR. In phospholipid bilayers with 1 M [H(+)](bulk), the current-voltage (I-V) relationship of the SS dimer is sublinear. Under identical experimental conditions, the I-V plot of the RR dimer is supralinear (S-shaped). In glycerylmonooleate bilayers with 1 M [H(+)](bulk), both the SS and RR dimers have a supralinear I-V plot. Consistent with results previously published (. Biophys. J. 73:2489-2502), the SS dimer is stable in lipid bilayers and has fast closures. In contrast, the open state of the RR channel has closed states that can last a few seconds, and the channel eventually inactivates into a closed state in either phospholipid or glycerylmonooleate bilayers. It is concluded that the water dynamics inside the pore as related to proton wire transfer is significantly different in the RR and SS dimers. Different physical mechanisms that could account for this hypothesis are discussed. The gating of the synthetic gA dimers seems to depend on the conformation of the dioxolane link between gA's. The experimental results provide an important framework for a detailed investigation at the atomic level of proton conduction in different and relatively simple ion channel structures.     

Protocol of a prospective study on the diagnostic value of transcranial duplex scanning of the substantia nigra in patients with parkinsonian symptoms

Background  

Parkinson's disease (PD) is the second most common neurodegenerative disorder. As there is no definitive diagnostic test, its diagnosis is based on clinical criteria. Recently transcranial duplex scanning (TCD) of the substantia nigra in the brainstem has been proposed as an instrument to diagnose PD. We and others have found that TCD scanning of substantia nigra duplex is a relatively accurate diagnostic instrument in patients with parkinsonian symptoms. However, all studies on TCD so far have involved well-defined, later-stage PD patients, which will obviously lead to an overestimate of the diagnostic accuracy of TCD.