A human lymphoid cell line secreting immunoglobulin G and retaining immunoglobulin M in the plasma membrane

A selected clone, LA 85.2, of a human lymphoid cell line produces μ, γ, and light chains. The cells secrete IgG but not IgM. Assembly of μ chains and light chains produces 8S IgM which is retained in the plasma membrane. IgM is produced at a slow rate and in lesser amounts than IgG. LA 85.2 cells produce a plasma membrane protein which can bind to antibody-antigen precipitates. It is suggested that this protein plays a role in holding the surface IgM in the plasma membrane.     

Study of the mitotic and meiotic chromosomes of sotol (<i>Dasylirion cedrosanum</i> Trel.)

The genus Dasylirion is a group of plants typically present in the Chihuahuan Desert, perennial, with a dioecious sexual behavior and commonly called sotoles. This genus has been little studied from the biological point of view, and the bases of its reproductive response remain unknown. In this work we studied the chromosome number and meiotic response of Dasylirion cedrosanum in the county of Saltillo, Coahuila, located at the North East of Mexico. For the preparation of mitotic chromosomes, we used a technique based on enzymatic treatment with pectolyase and cellulase, as well as staining with acetocarmin dye. For the study of meiosis, male flower buds were collected, fixed and stained for analysis with the same dye. As a result, the gametic (n = x = 19) and somatic chromosome (2n = 38) numbers of D. cedrosanum are reported for the first time, being consistent with previous findings in other Dasylirion species, which points to a constant ploidy level across the genus. Variation was observed in the morphology and size of the somatic chromosomes, with types ranging from submetacentric to subtelocentric, and sizes oscillating in a range of 4.43 µm, with an average total length of 112.38 µm for the diploid chromosome complement. This shows that the chromosome complement of D. cedrosanom would belong to a 3B classification of Stebins, with a medium variation between chromosome lengths and low chromosome asymmetry. This variation indicates the feasibility of constructing a chromosome ideotype for this species. The meiotic chromosome pairing showed a chromosome behavior consistent with a disomic inheritance characteristic of a diploid species, with prevalence of ring and chain bivalents, typically without pairing abnormalities. Bivalent configurations in all cases were symmetrical.The normal and symmetrical meiotic pairing indicates a balanced production of gametes, and suggests the absence of heteromorphic sex determination.     

Comparative structural analyses of the alpha-glucan and glycogen from Mycobacterium bovis

Pathogenic mycobacteria such as Mycobacterium tuberculosis, the causative agent of tuberculosis, are surrounded by a noncovalently bound capsule, whose major carbohydrate constituent is a glycogen-like alpha-glucan. In the present study we compared the structures of the extracellular polysaccharide to that of the ubiquitous intracellular glycogen. The alpha-glucan was isolated from the culture medium of Mycobacterium bovis Bacille Calmette Guérin, the vaccine strain, in which it is released whereas the intracellular glycogen was obtained after the disruption of cells. The two purified polysaccharides were eluted from permeation gel at a similar position but glycogen was less soluble and gave a more opalescent solution in water than alpha-glucan. Combination of gas chromatography-mass spectrometry analysis of partially O-methylated, partially O-acetylated alditols and NMR analysis confirmed that both polysaccharides were composed of -->4-alpha-D-Glcp-1--> core, substituted at some six positions with short chains. Degradation of polysaccharides with pullulanase, followed by mass spectrometry analysis of the resulting products, also showed that the two polysaccharides do not differ in terms of lengths of branching. Interestingly, application of analytical ultracentrifugation and dynamic light scattering to the mycobacterial alpha-glucan and glycogen and their enzymatic degradative products indicated that the alpha-glucan possessed a higher molecular mass and was more compact than the glycogen from the same species, allowing the formulation of working structural models for the two polysaccharides. Consistent with the models, the alpha-glucan was found to be less accessible to pullulanase, a debranching enzyme, than glycogen.     

Inducible cytochrome P450 activities in renal glomerular mesangial cells: biochemical basis for antagonistic interactions among nephrocarcinogenic polycyclic aromatic hydrocarbons

BACKGROUND: Benzo(a)pyrene (BaP), anthracene (ANTH) and chrysene (CHRY) are polynuclear aromatic hydrocarbons (PAHs) implicated in renal toxicity and carcinogenesis. These PAHs elicit cell type-specific effects that help predict toxicity outcomes in vitro and in vivo. While BaP and ANTH selectively injure glomerular mesangial cells, and CHRY targets cortico-tubular epithelial cells, binary or ternary mixtures of these hydrocarbons markedly reduce the overall cytotoxic potential of individual hydrocarbons. METHODS: To study the biochemical basis of these antagonistic interactions, renal glomerular mesangial cells were challenged with BaP alone (0.03 - 30 microM) or in the presence of ANTH (3 microM) or CHRY (3 microM) for 24 hr. Total RNA and protein will be harvested for Northern analysis and measurements of aryl hydrocarbon hydroxylase (AHH) and ethoxyresorufin-O-deethylase (EROD) activity, respectively, to evaluate cytochrome P450 mRNA and protein inducibility. Cellular hydrocarbon uptake and metabolic profiles of PAHs were analyzed by high performance liquid chromatography (HPLC). RESULTS: Combined hydrocarbon treatments did not influence the cellular uptake of individual hydrocarbons. ANTH or CHRY strongly repressed BaP-inducible cytochrome P450 mRNA and protein expression, and markedly inhibited oxidative BaP metabolism. CONCLUSION: These findings indicate that antagonistic interactions among nephrocarcinogenic PAHs involve altered expression of cytochrome P450s that modulate bioactivation profiles and nephrotoxic/ nephrocarcinogenic potential.     

Synthesis of new coumarin 3-(N-aryl) sulfonamides and their anticancer activity

Synthesis of coumarin 3-(N-aryl) sulfonamides was accomplished either by Knoevenagel condensation of anilinosulfonylacetic acids with suitable salicylaldehydes or by the reaction of methyl anilinosulfonylacetates with substituted salicylaldehydes in presence of a catalytic amount of a base. All the compounds tested for antiproliferative activity in different cancer cell lines have shown GI(50) values less than 100 microM.     

Novel thieno oxazine analogues as antihyperglycemic and lipid modulating agents

A series of phenyl acetic acid and alpha-hydroxy propionic acid derivatives were synthesized. In vivo studies of the compounds indicated compound 2c as the most potent in one of the series, which has both glucose and lipid lowering properties. The syntheses and biological studies have been discussed.     

Germ Line Transmission of the Cdk4R24C Mutation Facilitates Tumorigenesis and Escape from Cellular Senescence

Mutations in CDK4 and its key kinase inhibitor p16(INK4a) have been implicated in the genesis and progression of familial human melanoma. The importance of the CDK4 locus in human cancer first became evident following the identification of a germ line CDK4-Arg24Cys (R24C) mutation, which abolishes the ability of CDK4 to bind to p16(INK4a). To determine the role of the Cdk4(R24C) germ line mutation in the genesis of other cancer types, we introduced the R24C mutation in the Cdk4 locus of mice by using Cre-loxP-mediated "knock-in" technology. Cdk4(R24C/R24C) mouse embryo fibroblasts (MEFs) displayed increased Cdk4 kinase activity resulting in hyperphosphorylation of all three members of the Rb family, pRb, p107, and p130. MEFs derived from Cdk4(R24C/R24C) mice displayed decreased doubling times, escape from replicative senescence, and escape sensitivity to contact-induced growth arrest. These MEFs also exhibited a high degree of susceptibility to oncogene-induced transformation, suggesting that the Cdk4(R24C) mutation can serve as a primary event in the progression towards a fully transformed phenotype. In agreement with the in vitro data, homozygous Cdk4(R24C/R24C) mice developed tumors of various etiology within 8 to 10 months of their life span. The majority of these tumors were found in the pancreas, pituitary, brain, mammary tissue, and skin. In addition, Cdk4(R24C/R24C) mice showed extraordinary susceptibility to carcinogens and developed papillomas within the first 8 to 10 weeks following cutaneous application of the carcinogens 9,10-di-methyl-1,2-benz[a]anthracene (DMBA) and 12-O-tetradecanoylphorbol-13-acetate (TPA). This report formally establishes that the activation of Cdk4 is sufficient to promote cancer in many tissues. The observation that a wide variety of tumors develop in mice harboring the Cdk4(R24C) mutation offers a genetic proof that Cdk4 activation may constitute a central event in the genesis of many types of cancers in addition to melanoma.     

Synthesis and cytotoxic activity of novel quinazolino-beta-carboline-5-one derivatives

A novel series of quinazolino-beta-carbolinone derivatives was synthesized and evaluated for their in vitro and in vivo anticancer activity. Many compounds have shown good in vitro activity in the range 1-8 microM concentration. Three of the compounds were further tested in nude mice bearing HT-29 colon cancer xenografts.     

Isolation and characterization of microsatellite loci in the two‐spotted spider mite,Tetranychus urticae (Acari: Tetranychidae)

Sixteen microsatellite loci are described for the two‐spotted spider mite Tetranychus urticae, which is an agricultural pest. The microsatellite loci were obtained through the construction of an enriched library; these loci exhibited polymorphisms (2–5 alleles per locus) and high levels of observed (0.033–0.667, average 0.415) and expected (0.033–0.602, average 0.336) heterozygosities. The isolated microsatellite markers are expected to be useful for the construction of a linkage map of this species.