Molecular genetics of cell death in the nematode Caenorhabditis elegans

In C. elegans, cell death can be readily studied at the cellular, genetic, and molecular levels. Two types of death have been characterized in this nematode: (1) programmed cell death, which occurs as a normal component in development; and (2) pathological cell death which occurs aberrantly as a consequence of mutation. Analysis of mutations that disrupt programmed cell death in various ways has defined a genetic pathway for programmed cell death which includes genes that perform such functions as the determination of which cells die, the execution of cell death, the engulfment of cell corpses, and the digestion of DNA from dead cells. Molecular analysis is providing insightinto the nature of the molecules that function in these aspects of programmed cell death. Characterization of some genes that mutate to induce abnormal cell death has defined a novel gene family called degenerins that encode putative membrane proteins. Dominant alleles of at least two degenerin genes, mec-4 and deg-1, can cause cellular swelling and late onset neurodegeneration of specific groups of cells. © 1992 John Wiley & Sons, Inc.     

Biological activity of Burkholderia (Pseudomonas) cepacia lipopolysaccharide

Abstract Burkholderia cepacia has emerged as an important multiresistant pathogen in cystic fibrosis (CF), associated in 20% of colonised patients with a rapid and fatal decline in lung function. Although knowledge of B. cepacia epidemiology has improved, the mechanisms involved in pathogenesis remain obscure. In this study, B. cepacia lipopolysaccharide (LPS) was assessed for endotoxic potential and the capacity to induce tumour necrosis factor (TNF). LPS preparations from clinical and environmental isolates of B. cepacia and from the closely related species Burkholderia gladioli exhibited a higher endotoxic activity and more pronounced cytokine response in vitro compared to preparations from the major CF pathogen Pseudomonas aeruginosa . This study may help to explain the vicious host immune response observed during pulmonary exacerbations in CF patients colonised by B. cepacia and lead to therapeutic advances in clinical management.     

The Administration of an α-MSH Analogue Reduces the Serum Release of IL-1α and TNFα Induced by the Injection of a Sublethal Dose of Lipopolysaccharides in the BALB/c Mouse

The injection of α-MSH or of one of its analogues ([Nle₄-D.Phe₇] α-MSH_4–10) reduced, in vivo, the release of two cytokines (IL-1α and TNFα) involved in inflammation. The inflammatory state was induced in BALB/c mice by intraperitoneal injection of a sublethal dose of lipopolysaccharides (LPS). The assay of these cytokines by ELISA showed a reduction of 20% with α-MSH and between 30 and 60% with the α-MSH analogue. The α-MSH or the analogue was administered in one of two ways: intravenously or subcutaneously. The most efficient method seemed to be the subcutaneous one because it improved the activity 10,000 times more than the intravenous method. Moreover, the analogue induced a regression of mortality in the animals treated by the intravenous method. Our results show that α-MSH and one of its analogues inhibit IL-1α and TNFα, and can be used as anti-inflammatory molecules.     

Interleukin-1-β and Tumor Necrosis Factor-α Increase Peripheral-Type Benzodiazepine Binding Sites in Cultured Polygonal Astrocytes

Peripheral-type benzodiazepine binding sites (PTBBS) are markedly increased in the injured CNS. Astrocytes appear to be the primary cell type which express increased PTBBS. Because certain cytokines within the injured CNS are potent mitogens for astrocytes, we examined the effects of two such cytokines, interleukin (IL)-1 beta and tumor necrosis factor (TNF), on PTBBS in cultured astrocytes using [3H]Ro 5-4864 as the specific ligand. Purified cultures of either polygonal or process-bearing astrocytes were prepared from neonatal rat cerebral hemispheres. At a concentration of 1.8 nM, specific binding of the radioactive ligand to polygonal astrocytes reached equilibrium within 60 min and was half-maximal by 5-10 min. By contrast, specific binding to process-bearing astrocytes barely exceeded background levels. IL-1 and TNF increased PTBBS within polygonal astrocytes in both dose- and time-dependent manners. At 10-50 ng/ml, IL-1 beta and TNF-alpha elevated [3H]Ro 5-4864 binding in polygonal astrocyte cultures 65 and 87%, respectively, above the level in control cultures. However, no changes in PTBBS were seen within polygonal astrocytes after IL-2 treatment. Scatchard analysis of saturation binding experiments suggested that the increase in PTBBS promoted by TNF was due to an increased number of binding sites present in polygonal astrocytes and not due to an increase in receptor affinity. Binding data suggested that PTBBS within cultures of process-bearing astrocytes were virtually absent irrespective of the treatment. These in vitro data suggest that certain cytokines found in the injured brain may be involved in up-regulating PTBBS within a particular subtype of astrocyte.     

Smooth muscle and myofibroblast-like cells in the perimedullary stromal basket of kidneys from ringed seals (Phoca hispida)

Summary The medullary pyramid of renculi in kidneys of ringed seals (Phoca hispida) is enclosed by a basket composed of ribbons of stromal tissue continuous with the wall of the calyx. Branched smooth muscle cells with well-developed Golgi complexes and rough endoplasmic reticulum and only an incomplete external lamina are the principal cells in sites near the origin of the ribbons from the calycal wall. Deeper in the corticomedullary junctional region, smooth muscle is progressively replaced with stellate or spindle-shaped cells exhibiting structural characteristics intermediate between those of fibroblasts and smooth muscle fibers. These myofibroblast-like cells contain arrays of parallel microfilaments 6–8 nm thick with associated focal densities and subplasmalemmal dense plaques, caveolae, elongate, often deeply wrinkled nuclei, and well-developed Golgi complexes and rough endoplasmic reticulum. Material resembling external lamina is associated with parts of the surfaces of most myofibroblast-like cells and intermediate junctions are present. Fibroblasts lacking arrays of parallel microfilaments are a minority at any level in the stromal ribbons. Interstitial cells in the vicinity of the corticomedullary junction show similar myofibroblast-like characteristics. The smooth muscle and myofibroblast-like cells presumably assist expression of urine from the papilla and calyx, and possibly participate as pacemakers for the urinary tract.     

The control of shoot tip necrosis in Pistacia vera L. in vitro

The effect of increased concentrations of calcium (Ca) (3–24 mM) and boron (B) (100–800 M) in the medium was studied on the occurrence of shoot tip necrosis (STN) in cultures of Pistacia vera L. STN was significantly reduced by application of Ca or B, however media with more than 200 M boron had reduced shoot multiplication. Ca (12–24 mM) supplied as calcium chloride reduced STN without any adverse effect on shoot multiplication or elongation, whereas calcium acetate reduced elongation. It is concluded that STN is a physiological mineral disorder associated with Ca and/or B deficiency in the meristematic regions of actively growing shoots. Application of Ca (up to 24 mM) as calcium chloride to the medium was the best treatment for the control of STN. Reduction of humidity or increased aeration in the culture jars did not have any significant effect on the occurrence of STN.Abbreviations MS Murashige and Skoog medium - STN Shoot tip necrosis     

Rubus host range of rubus yellow net virus and its involvement with other aphid-borne latent viruses in inducing raspberry veinbanding mosaic disease

After graft inoculation with rubus yellow net virus (RYNV), 12 of 34 Rubus species and cultivars developed noticeable symptoms. R. macraei developed the most conspicuous symptoms and is recommended as an improved indicator plant. In attempts to determine the cause of raspberry veinbanding mosaic, a disease in which RYNV is involved, several European and North American red raspberry cvs were graft-inoculated with RYNV and three other aphid-borne viruses, black raspberry necrosis (BRNV), raspberry leaf mottle (RLMV) and raspberry leaf spot, singly and in all combinations. In periods of up to 4 yr, classical veinbanding mosaic symptoms developed in sensitive cvs only when they contained both RYNV and RLMV. These symptoms were intensified in plants co-infected with additional viruses. Veinbanding mosaic disease did not develop in any of 11 cvs infected with RYNV + BRNV, the combination of viruses previously assumed to be responsible for this disease in Britain and North America.     

Morphogenesis of the renal juxtaglomerular apparatus and peripolar cells in the sheep

Summary The morphogenesis of the juxtaglomerular apparatus and peripolar cells was studied in the metanephros of fetal sheep (from 24 to 147 days of gestation) using light and electron microscopy. The first juxtaglomerular apparatus was detected at 45 days of gestation, following constriction of the edges of Bowman's capsule and formation of the vascular pole of the renal corpuscle. Mesenchymal cells gave rise to lacis cells and to smooth muscle and epithelioid cells of the juxtaglomerular arterioles. Epithelioid cells developed only sparse cytoplasmic granulation, first detectable at 92 days. The macula densa developed from tubular cells at the junction of the middle and upper limbs of the S-shaped body of the developing nephron. Peripolar cells arose from epithelial cells in the lower limb of the S-shaped body, at the constricting edges of Bowman's capsule, and formed a cuff around the origin of the glomerular tuft. Cytoplasmic granules were first detected in peripolar cells at 53 days, and remained more prominent than epithelioid cell granulation throughout gestation.     

Biotechnological challenges of bioartificial kidney engineering

With the world-wide increase of patients with renal failure, the development of functional renal replacement therapies have gained significant interest and novel technologies are rapidly evolving. Currently used renal replacement therapies insufficiently remove accumulating waste products, resulting in the uremic syndrome. A more preferred treatment option is kidney transplantation, but the shortage of donor organs and the increasing number of patients waiting for a transplant warrant the development of novel technologies. The bioartificial kidney (BAK) is such promising biotechnological approach to replace essential renal functions together with the active secretion of waste products. The development of the BAK requires a multidisciplinary approach and evolves at the intersection of regenerative medicine and renal replacement therapy. Here we provide a concise review embracing a compact historical overview of bioartificial kidney development and highlighting the current state-of-the-art, including implementation of living-membranes and the relevance of extracellular matrices. We focus further on the choice of relevant renal epithelial cell lines versus the use of stem cells and co-cultures that need to be implemented in a suitable device. Moreover, the future of the BAK in regenerative nephrology is discussed.     

The Association of Phytoplasma with Stunting, Leaf Necrosis and Witches' Broom Symptoms in Magnolia Plants

In 1999–2000 a severe disease was observed on plants of four Magnolia spp. cultivated in a commercial nursery in Poland. Affected plants showed a progressive loss of vigour, were stunted, and had severely malformed leaves, leaf necrosis and witches' broom. Phytoplasma was detected in magnolias with severe symptoms and in dodder-inoculated Catharanthus roseus seedlings by nested polymerase chain reaction (PCR) assay with primer pair R16F1/R0 followed by universal (rA/fA) and group specific (R16(I)F1/R1) primer pairs which amplified a fragment of phytoplasma 16S rDNA. The PCR products (560 bp or 1.1 kb) of all samples used for restriction fragment length polymorphism analysis after digestion with endonuclease enzymes Alu I and Mse I produced the same profile which corresponded to that of an aster yellows phytoplasma reference strain. Phytoplasma DNA was detected throughout the growing season in roots, stems and young but not mature leaves. Electron microscope examination of the ultra-thin sections of the leaf and stem of diseased magnolias showed collapsed and degenerated sieve tube elements with wall thickening. The reduced lumen of these sieve elements contained numerous vesicles and membrane-bound structures, but no typical phytoplasma cells. This is the first report of aster yellows phytoplasma in magnolia identified by molecular assays.