Positive selection at reproductive ADAM genes with potential intercellular binding activity

Many genes with a role in reproduction, including those implicated in fertilization and spermatogenesis, have been shown to evolve at a faster rate relative to genes associated with other functions and tissues. These survey studies usually group a wide variety of genes with different characteristics and evolutionary histories as reproductive genes based on their site of expression or function. We have examined the molecular evolution of the ADAM (a disintegrin and metalloprotease) gene family, a structurally and functionally diverse group of genes expressed in reproductive and somatic tissue to test whether a variety of protein characteristics such as phylogenetic clusters, tissue of expression, and proteolytic and adhesive function can group fast evolving ADAM genes. We found that all genes were evolving under purifying selection (d(N)/d(S) < 1), although reproductive ADAMs, including those implicated in fertilization and spermatogenesis, evolved at the fastest rate. Genes with a role in binding to cell receptors in endogenous tissue appear to be evolving under purifying selection, regardless of the tissue of expression. In contrast, positive selection of codon sites in the disintegrin/cysteine-rich adhesion domains was detected exclusively in ADAMs 2 and 32, two genes expressed in the testis with a potential role in sperm-egg adhesion. Positive selection was detected in the transmembrane/cytosolic tail region of ADAM genes expressed in a variety of tissues.     

GDNF augments survival and differentiation of TH-positive neurons in neural progenitor cells

GDNF plays an important role in the survival and differentiation of primary dopaminergic neurons, but it requires multiple factors for its entire range of activities. This study investigated the effects of GDNF and its cofactors on the development of bFGF-responsive neural progenitor cells (NPCs), mesencephalic and cortical progenitor cells (MP and CP). Various factors were found to have significant inductive effects on the survival and maintenance of these cells in late developmental stages. MP had greater potential than CP to differentiate into dopaminergic neurons. Treatment of NPCs with GDNF and its cofactors enhanced MAP-2 and TH expression, particularly the latter. These findings suggest that NPCs, particularly MP, could develop into more specific neurons if the appropriate factors were applied during the final cell fate specification. They might thus become beneficial sources of donor cells in the treatment of neurological disorders.     

Discovering lactic acid bacteria by genomics

This review summarizes a collection of lactic acid bacteria that are now undergoing genomic sequencing and analysis. Summaries are presented on twenty different species, with each overview discussing the organisms fundamental and practical significance, nvironmental habitat, and its role in fermentation, bioprocessing, or probiotics. For those projects where genome sequence data were available by March 2002, summaries include a listing of key statistics and interesting genomic features. These efforts will revolutionize our molecular view of Gram–positive bacteria, as up to 15 genomes from the low GC content lactic acid bacteria are expected to be available in the public domain by the end of 2003. Our collective view of the lactic acid bacteria will be fundamentally changed as we rediscover the relationships and capabilities of these organisms through genomics.     

Positive selectable marker genes for routine plant transformation

Summary Plant genetic transformation technologies rely upon the selection and recovery of transformed cells. Selectable marker genes used so far have been either antibiotic resistance genes or herbicide tolerance genes. There is a need to apply alternative principles of selection, as more transgenic traits have to be incorporated into a transgenic crop and because of concern that the use of conventional marker genes may pose a threat to humans and the environment. New classes of marker genes are now available, conferring metabolic advantage of the transgenic cells over the non-transformed cells. The new selection systems, as described in this review, are being used with success and superior performance over the traditional marker systems.     

Dual abnormal effects of mutant MITF encoded by Mi(wh) allele on mouse mast cells: decreased but recognizable transactivation and inhibition of transactivation

Structural localization of a peptide region, KRQPRNPKTDKLVNE, in the catalytic subunit of (Na(+) + K(+))-ATPase was investigated using a specific antibody directed against this peptide in cultured African green monkey kidney CV-1 cells. Immunofluorescence staining of frozen cell sections shows that an anti-KRQPRNPKTDKLVNE antibody (SSA95) interacts with its antigenic site and binds to the extracellular side of the cell membrane. Indirect immunofluorescence and flow cytometric analyses confirmed the presence of this epitope on intact cell surfaces. These results suggest that the KRQPRNPKTDKLVNE region of the (Na(+) + K(+))-ATPase is expressed on the cellular membrane surface.     

Redistribution and unmasking of Annexin V binding sites in apoptotic Raji cells

The complement receptor type 2 (CR2) associates with other surface antigens and proteins and its redistribution and/or unmasking occurs through still unknown mechanism(s). The data presented demonstrate that high-density cultured CR2-positive cells undergo apoptosis and that the redistribution and unmasking of Annexin V binding sites occurs in a fashion similar to the redistribution and unmasking of CR2. Therefore, apoptotic and non apoptotic cells from the same lineage may share a similar mechanism for the exposition of neo-surface markers     

CR2 units of CR2 complexes are possibly associated with nucleophilic agents through reactive covalent links

The human complement receptor type 2 (CR2/CD21), a transmembrane glycoprotein, associates with a variety of surface antigens and proteins in the cell membrane. We examined the possibilities that the CR2 units of CR2 complexes are associated through internal covalent links reactive with nucleophilic agents, e.g. H(2)O or methylamine, and that CR2-positive cells process anti-CR2 monoclonal antibodies (MoAbs). Data from immunoblotting and cytofluorimetry with CR2-binding site-specific MoAbs show that: (i) CR2-positive Raji cells release soluble CR2 isoforms into the medium when incubated in phosphate buffered saline; (ii) despite affecting the detection of one soluble CR2 isoform, methylamine treatment of soluble CR2 allows the detection of another of its isoforms; (iii) limited pre-treatment of cells with methylamine reveals a more heterogeneous CR2-positive cell population or enhances the detection of CR2; (iv) cell treatment with CR2-binding site-specific MoAbs enhances the detection of CR2 isoform(s). The data suggest that CR2 is shed mainly as a soluble CR2 complex, in which the CR2 units link covalently and react with nucleophilic agents. Raji cells may process bound fragments (145 kDa) that are recognised by and become bound by anti-CR2 MoAb.     

Neoadjuvant tamoxifen and aromatase inhibitors: comparisons and clinical outcomes

Neoadjuvant hormonal therapy for oestrogen receptor (ER) and/or progesterone receptor (PgR) positive large operable or locally advanced breast cancer is effective and a safe alternative to chemotherapy in postmenopausal women. A randomised trial has demonstrated that the response rate and the incidence and degree of downstaging with the aromatase inhibitor letrozole is significantly greater than with tamoxifen [J. Clin. Oncol. 19 (2001) 3808]. Tumours at all levels of ER appear to respond better to letrozole than tamoxifen but at low levels of ER responses are seen only with letrozole and not with tamoxifen. Patients most likely to benefit from neoadjuvant therapy and those who achieve the greatest reduction in tumour volume are those patients with tumours that express very high levels of ER (ALLRED category score 8). Both letrozole and anastrozole appear effective in both erbB2 positive and negative breast cancers. Three months of treatment is adequate to determine if a tumour will respond. Following breast-conserving surgery and radiotherapy, local recurrence rates appear satisfactory.