Identification of an S-locus glycoprotein allele introgressed from B. napus ssp. rapifera to B. napus ssp. oleifera.

We have previously described a developmentally regulated mRNA in maize that accumulates in mature embryos and is involved in a variety of stress responses in the plant. The sequence of the encoded 16 kDa protein (MA16) predicts that it is an RNA-binding protein, since it possesses a ribonucleoprotein consensus sequence-type RNA-binding domain (CS-RBD). To assess the predicted RNA binding property of the protein and as a starting point to characterize its function we have used ribohomopolymer-binding assays. Here we show that the MA16-encoded protein binds preferentially to uridine- and guanosine-rich RNAs. In light of these results a likely role for this protein in RNA metabolism during late embryogenesis and in the stress response is discussed.     

Expression of Krox Proteins During Differentiation of the O-2A Progenitor Cell Line CG-4

Abstract: Krox proteins are important regulators of development and terminal differentiation. Using the rat glial progenitor cell line CG-4 as a model system for oligodendrocyte differentiation, we show that on the RNA level Krox-24 is the predominant member of the Krox family in these cells. Similar results were also obtained on the protein level as the major Krox protein from CG-4 cell extracts reacted specifically with an antibody against Krox-24. Whereas Krox-24 RNA and protein were abundant in undifferentiated CG-4 cells, a dramatic decrease in expression was detected after a 3–5-day period of differentiation during which we observed a reciprocal increase in the levels of myelin basic protein expression. Importantly, regulation of Krox-24 expression was very similar in CG-4 cells and primary oligodendrocyte cultures. When expression of Krox-24 in differentiating CG-4 cells was followed on a closer time scale, we observed a sharp and transient increase in Krox-24 RNA, protein, and DNA binding activity immediately after the onset of differentiation followed by an equally rapid decrease. This expression pattern implicates Krox-24 both in maintenance of the undifferentiated state and in the immediate early phase of differentiation of CG-4 cells and possibly oligodendrocytes.     

Changes in lectin binding of lumbar dorsal root ganglia neurons and peripheral axons after sciatic and spinal nerve injury in the rat

Summary The effects of chronic lesions of rat lumbar spinal or sciatic nerves on the binding of Glycine max (soybean) agglutinin to galacto-conjugates, in small-and medium-size primary sensory neurons of the L₄ and L₅ dorsal root ganglia, were examined over a 580-day period. Spinal nerve section resulted in a marked decrease in the population of stained neurons within 7 days. However, despite some retrograde morphological changes triggered by axonal injury, the proportion of stained nerve cells was normalized 180 days postoperatively. This temporary decrease in perikaryal lectin reactivity was initially associated with a marked accumulation of stained material in the nerve, proximal and distal to the site of section, with similar accumulations also being noticeable at each level of injury in sciatic nerves subjected to double ligature. This may reflect the presence of glycocompounds linked to the autolysis of nerve fibers during the phase of retrograde dying-back and Wallerian degeneration. At later stages, stained deposits could be seen scattered along central and peripheral axonal processes of the dorsal root ganglion neurons in the vicinity of the cell body. They may indicate a disturbance in the peripheral turnover of glycoproteins in chronically-transected nerves, with piling up of neuronal products. Sciatic nerve injury caused similar but less severe effects which, except for the L₄ ganglion cells, were rapidly reversible.     

Evidence for new forms of cardiac myosin heavy chains in mechanical heart overloading and in ageing

Heavy chains of myosin rods and subfragment 1 were isolated from normal hearts and from mechanically overloaded hearts of young and older rats. These myosin heavy-chain fragments were cleaved by cyanogen bromide or partially proteolysed by pronase and by chymotrypsin after denaturation with sodium dodecyl sulfate. The peptides, analyzed by electrophoresis on a one-dimensional polyacrylamide slab gel, varied depending on the origin of the cardiac myosin heavy chains. Some bands present in the peptide patterns of the normal heart of young rats were missing from the pattern of greatly hypertrophied hearts and vice versa. We conclude that mechanical overloading of the heart stimulates the synthesis of cardiac myosin 'isozyme' with a heavy-chain primary structure which is different from that observed in the normal heart of young rat. The patterns from myosin heavy-chain peptides from the hearts of older rats were different from those for peptides from young rat hearts; these results also indicate the presence of a new myosin heavy chain specific to ageing. No difference was detected between the peptide patterns of heavy chains isolated from hypertrophied hearts of young and older rats, and those isolated from normal hearts of older rats.     

Absence of phosphates from the myosin heavy chains of striated muscles

This work aimed to determine whether the heavy chains of myosin from different striated muscle were phosphorylated. Myosin and its heavy chains were prepared from cardiac and skeletal muscles of rats injected in vivo with radioactive phosphates.The results for radioactive phosphate localization indicate the absence of phosphate from pure heavy chains and from any of their purified fragments, whatever the striated muscle used. In addition, phosphates are present in the myosin phosphorylated light chain and in a contaminating protein closely associated to the myosin heavy chain.     

Proteolytic susceptibility of the central domain in chicken gizzard and skeletal muscle dystrophins.

We investigated proteolytic susceptibility of the central domain in dystrophin molecules from chicken smooth and skeletal muscles. Dystrophin-enriched preparations from both muscles were made as described in Pons et al. (Proc. Natl. Acad. Sci. USA (1990) 87, 7851-7855). These preparations contained other protein components in addition to dystrophin. Three enzymes (Staphylococcus aureus proteinase, chymotrypsin and trypsin) having different proteolytic specificities were used. Time-courses of proteinase degradation were examined by the Western immunoblot technique using a specific polyclonal serum directed against a fragment (residues 1173-1728) of the dystrophin central domain. We observed accumulation of some major proteinase-resistant fragments, in the 110-160 kDa range originating from that central region of the molecule. Cleavage patterns of the smooth and skeletal muscle preparations were quite similar, but molecular weights of the breakdown products differed slightly. Interpretation of the results was based on two predictive structural models of the dystrophin central domain (Koenig and Kunkel (1990) J. Biol. Chem. 265, 4560-4566 and Cross et al. (1990) FEBS Lett. 262, 87-90). Skip residues at the end of repeat 13 (around the 1740th residue of the dystrophin amino acid sequence), as hypothesized in the Cross model, constitute probably the most sensitive site within the dystrophin central domain for any exogenous (or even endogenous) proteinase. Variations observed between dystrophins from skeletal and smooth muscles also suggest that the structures of both dystrophins differ slightly even within the dystrophin central domain. This precise identification of proteinase-resistant dystrophin fragments of variable lengths is a first step towards further physicochemical studies on the very large and rare dystrophin molecule.     

Response by women aged 65-79 to invitation for screening for breast cancer by mammography: a pilot study.

OBJECTIVE--To determine whether there is sufficient benefit to be gained by offering screening for breast cancer with mammography to women aged 65-79, who are not normally invited for screening. DESIGN--Pilot study of women eligible for screening but not for personal invitation. The results of this study were compared with the results of routinely screened younger women (aged 50-64) from the same general practice. SETTING--One group general practice in south Manchester. PATIENTS--The 631 women aged 65-79 on the practice list. A total of 42 (7%) were excluded by the general practitioner, and 22 (4%) invitation letters were returned by the post office. MAIN OUTCOME MEASURES--Response rates to invitation for screening assessed by three indices: crude population coverage ratio, crude invited population coverage ratio, and corrected invited population coverage ratio. RESULTS--344 Patients aged 65-79 (61% of those invited, excluding those who could not be traced) were screened compared with 77% of women aged 50-64. The three response indices were higher for younger women than older: crude population coverage ratio = 66.5%, crude invited population coverage ratio = 69.3%, corrected invited population coverage ratio = 76.8% for women aged 50-64, compared with 54.5%, 58.4%, and 60.7% respectively for women aged 65-79. All four biopsies done in the older women gave positive results, giving a cancer detection rate of 11.6/1000 compared with 4.1/1000 among younger women. CONCLUSIONS--These results show that there is a potential for high attendance at routine screening by older women if they are invited in the same way as younger women. If these results are found elsewhere the costs and benefits of screening older women should be reassessed.     

Discovery of SAR184841, a potent and long-lasting inhibitor of 11β-hydroxysteroid dehydrogenase type 1, active in a physiopathological animal model of T2D

Starting from 11β-HSD1 inhibitors that were active ex vivo but with Cyp 3A4 liability, we obtained a new series of adamantane ureas displaying potent inhibition of both human and rodent 11β-HSD1 enzymes, devoid of Cyp 3A4 interactions, and rationally designed to provide long-lasting inhibition in target tissues. Final optimizations lead to SAR184841 with good oral pharmacokinetic properties showing in vivo activity and improvement of metabolic parameters in a physiopathological model of type 2 diabetes.     

Chromatographic analysis of the enkephalin immunoreactivity in the nucleus locus coeruleus of the cat after local colchicine administration

Cell bodies immunoreactive for methionine- and leucine-enkephalin are found in the area of the locus coeruleus (dorsolateral pons) of the cat after injection of colchicine in the ascending projections of the nucleus. Using radioimmunoassay procedures, it is shown that colchicine induces a significant increase in methionine- and leucine-enkephalin-immunoreactive material in this area of the brain. High pressure liquid chromatography analysis demonstrated that the immunoreactive materials were authentic methionine- and leucine-enkephalin. The methionine- and leucine-enkephalin patterns were identical in the colchicine injected and non-injected sides of the dorsolateral pons. It is suggested that, in this area of the brain, colchicine (i) does not significantly modify the processing of proenkephalin to form the pentapeptides methionine- and leucine-enkephalin, and (ii) does not induce the appearance of new substances reactive to the enkephalin antisera employed.