Cell and tissue cultures ofCatharanthus roseus (L.) G. Don: a literature survey

The literature concerning the formation of secondary metabolites in cell and tissue cultures ofCatharanthus roseus has been reviewed. Several aspects involved in the formation of secondary metabolites are discussed; e.g. regulation of secondary metabolism, environmental factors influencing secondary metabolism, biosynthesis and enzymology of the products, analysis of product formation, immobilization of cultured cells and stability of cell lines. Some economical aspects of production processes are discussed.     

Hybridization of Euglena RNA to the heavy and the light chloroplast DNA components separated in alkaline CsC1 gradients

It has been suggested that increases in cyclic GMP levels are responsible for the negative inotropic effects of acetylcholine in the heart. This hypothesis was tested by monitoring the effects of acetylcholine and sodium nitroprusside on tension and cyclic nucleotide levels in strips of cat atrial appendage. Sodium nitroprusside markedly increased atrial cyclic GMP levels but did not decrease the twitch tension developed by the atrial strips. Low concentrations of acetylcholine, on the other hand, decreased twitch tension without increasing myocardial cyclic GMP levels. No significant change in cyclic AMP levels was observed in any of these experiments. These results are not consistent with the proposed role for cyclic GMP as the mediator of the negative inotropic effects of acetylcholine.     

Sequence variations in the Fanconi anaemia gene,FAC: pathogenicity of 1806insA and R548X and recognition of D195V as a polymorphic variant

Fanconi anaemia (FA) is a rare autosomal recessive disorder associated with diverse clinical symptoms, increased chromosomal instability and a marked hypersensitivity to crosslinking agents. At least five complementation groups have been defined, the gene for group C (FAC) being the only FA gene cloned thus far. Several sequence variations have been detected in FA patients, whose assignment to group C, however, had not been ascertained by complementation studies. Using a functional assay, in which we tested the capacity of a variant sequence to correct the defect in FA-C lymphoblasts, we provide evidence for the pathogenic status of 1806insA and R548X and for non-pathogenicity of D195V. Received: 23 April 1996     

Atomic coordinates for T4 phage lysozyme.

Atomic coordinates are presented for the lysozyme from T4 bacteriophage. The coordinates were derived from a 2.4 Å resolution electron density map based on two isomorphous heavy-atom derivatives, interpreted in terms of the known amino acid sequence, and adjusted to have stereochemically acceptable bond lengths and angles.     

AIDS and Glycosylation

The authors regret that in this Mini Review a paper by Massariet al. (1990) (J. Immunol., 144, 4628-4632) was cited out ofcontext. In this paper isolates of HIV-1 from peripheral bloodmononuclear cells of seropositive individuals (and not molecularclones as cited) were investigated for their macrophage tropismin vitro.     

Ectophosphatase activity in the triple-negative breast cancer cell line MDA-MB-231

Breast cancer is one of the most common cancers in the female population worldwide, and its development is thought to be associated with genetic mutations that lead to uncontrolled and accelerated growth of breast cells. This abnormal behavior requires extra energy, and indeed, tumor cells display a rewired energy metabolism compared to normal breast cells. Inorganic phosphate (Pi) is a glycolytic substrate of glyceraldehyde-3-phosphate dehydrogenase and has an important role in cancer cell proliferation. For cells to obtain Pi, ectoenzymes in the plasma membrane with their catalytic site facing the extracellular environment can hydrolyze phosphorylated molecules, and this is an initial and possibly limiting step for the uptake of Pi by carriers that behave as adjuvants in the process of energy harvesting and thus partially contributes to tumor energy requirements. In this study, the activity of an ectophosphatase in MDA-MB-231 cells was biochemically characterized, and the results showed that the activity of this enzyme was higher in the acidic pH range and that the enzyme had a K_m = 4.5 ± 0.5 mM para-nitrophenylphosphate and a V_max = 2280 ± 158 nM × h⁻¹ × mg protein⁻¹. In addition, classical acid phosphatase inhibitors, including sodium orthovanadate, decreased enzymatic activity. Sodium orthovanadate was able to inhibit ectophosphatase activity while also inhibiting cell proliferation, adhesion, and migration, which are important processes in tumor progression, especially in metastatic breast cancer MDA-MB-231 cells that have higher ectophosphatase activity than MCF-7 and MCF-10 breast cells.     

A structurally informed autotransporter platform for efficient heterologous protein secretion and display

ABSTRACT: BACKGROUND: The self-sufficient Autotransporter (AT) pathway, ubiquitous in Gram-negative bacteria, combines a relatively simple protein secretion mechanism with a high transport capacity. ATs consist of a secreted passenger domain and a beta-domain that facilitates transfer of the passenger across the cell-envelope. They have a great potential for the extracellular expression of recombinant proteins but their exploitation has suffered from the limited structural knowledge of carrier ATs. Capitalizing on its crystal structure, we have engineered the Escherichia coli AT Hemoglobin protease (Hbp) into a platform for the secretion and surface display of heterologous proteins, using the Mycobacterium tuberculosis vaccine target ESAT6 as a model protein. RESULTS: Based on the Hbp crystal structure, five passenger side domains were selected and one by one replaced by ESAT6, whereas a beta-helical core structure (beta-stem) was left intact. The resulting Hbp-ESAT6 chimeras were efficiently and stably secreted into the culture medium of E. coli. On the other hand, Hbp-ESAT6 fusions containing a truncated beta-stem appeared unstable after translocation, demonstrating the importance of an intact beta-stem. By interrupting the cleavage site between passenger and beta-domain, Hbp-ESAT6 display variants were constructed that remain cell associated and facilitate efficient surface exposure of ESAT6 as judged by proteinase K accessibility and whole cell immuno-EM analysis. Upon replacement of the passenger side domain of an alternative AT, EspC, ESAT6 was also efficiently secreted, showing the approach is more generally applicable to ATs. Furthermore, Hbp-ESAT6 was efficiently displayed in an attenuated Salmonella typhimurium strain upon chromosomal integration of a single encoding gene copy, demonstrating the potential of the Hbp platform for live vaccine development. CONCLUSIONS: We developed the first structurally informed AT platform for efficient secretion and surface display of heterologous proteins. The platform has potential with regard to the development of recombinant live vaccines and may be useful for other biotechnological applications that require high-level secretion or display of recombinant proteins by bacteria.     

Prevalence of human papillomavirus infection,distribution of viral types and risk factors in cervical samples from human immunodeficiency virus-positive women attending three human immunodeficiency virus-acquired immune deficiency syndrome reference centres in northeastern Brazil

Human immunodeficiency virus (HIV)-positive patients have a greater prevalence of coinfection with human papillomavirus (HPV) is of high oncogenic risk. Indeed, the presence of the virus favours intraepithelial squamous cell lesion progression and may induce cancer. The aim of this study was to evaluate the prevalence of HPV infection, distribution of HPV types and risk factors among HIV-positive patients. Cervical samples from 450 HIV-positive patients were analysed with regard to oncotic cytology, colposcopy and HPV presence and type by means of polymerase chain reaction and sequencing. The results were analysed by comparing demographic data and data relating to HPV and HIV infection. The prevalence of HPV was 47.5%. Among the HPV-positive samples, 59% included viral types of high oncogenic risk. Multivariate analysis showed an association between HPV infection and the presence of cytological alterations (p = 0.003), age greater than or equal to 35 years (p = 0.002), number of partners greater than three (p = 0.002), CD4⁺ lymphocyte count < 200/mm³ (p = 0.041) and alcohol abuse (p = 0.004). Although high-risk HPV was present in the majority of the lesions studied, the low frequency of HPV 16 (3.3%), low occurrence of cervical lesions and preserved immunological state in most of the HIV-positive patients were factors that may explain the low occurrence of precancerous cervical lesions in this population.     

Coexistence between native and nonnative species: the invasion process and adjustments in distribution through time for congeneric piranhas in a Neotropical floodplain

Hydrobiologia - Our goal was to report the progress of Serrasalmus marginatus invasion process in the upper Paraná River floodplain by exploring its mechanisms and coexistence with its native...