The distribution of carbohydrate side chains along the polypeptide chain of glucoamylase

Glucoamylase is a starch-hydrolyzing enzyme with a glycoprotein structure, used industrially for the conversion of starch to glucose, citric acid, corn syrups, and high-fructose sweeteners. This enzyme possesses an unusual type of structure in which many carbohydrate side chains are linked O-glycosidically to serine and threonine residues of the polypeptide chain. The carbohydrate side chains may be single monosaccharide residues or oligosaccharides of mannose, glucose, galactose, and in some cases N-acetylglucosamine. New data from experiments on the CNBr fragmentation of glucoamylase followed by chemical and immunological characterization of the fragments show that the carbohydrate side chains are distributed randomly along the polypeptide chain. Such a structure is appropriately termed a random model reprensentation for the glucoamylase molecule.     

The control of chloroplast number in wheat mesophyll cells

Chloroplast number per cell and mesophyll cell plan area were determined in populations of separated cells from the primary leaves of different wheat species representing three levels of ploidy. Mean chloroplast number per cell increases with ploidy level as mean cell size increases. But in addition the analysis of individual cells clearly shows that cells of a similar size but from species of different ploidies have similar numbers of chloroplasts. We conclude that the number of chloroplasts within a cell is closely correlated (P<0.001) with the size of the cell and this relationship is consistent for species of different ploidies over a wide range of cell sizes. These results are discussed in relation to the hypothesis that chloroplast number in leaf mesophyll cells is determined by the size of the cell.     

Rapid Image Analysis Screening Procedure for Identifying Chloroplast Number Mutants in Mesophyll Cells of Arabidopsis thaliana (L.) Heynh

To analyze the genetic control of the process of chloroplast division, a direct image analysis screening procedure has been developed in which mutants of Arabidopsis thaliana (L.) Heynh. var Landsberg erecta are selected on the basis of abnormal chloroplast number. The selection procedure is based on image analysis thresholding after iodine staining, which facilitates the automatic counting of chloroplasts in isolated mesophyll cells. M2 seedlings are screened for significant deviation from the wild type relationship between mesophyll cell size and chloroplast number. Mutants with both abnormally high and abnormally low chloroplast numbers were identified. Of 3500 individual M2 seedlings screened, 18 mutant lines have been isolated and shown to be stably inherited in three subsequent generations. The most extreme phenotypes show an 80% reduction or a 50% increase in chloroplast number per mesophyll cell.     

Glucose Tolerance and Serum Insulin in Identical Twins of Diabetics

Glucose tolerance with serum insulin assay has been carried out in 24 apparently unaffected identical twins of diabetics. Glucose values were significantly higher and insulin values significantly lower than in control subjects, but there was considerable individual variation and in half the cases glucose tolerance was normal. There was no case of increased insulin response. In these twins glucose tolerance and insulin response were not correlated with weight, family history of diabetes, age at diagnosis of diabetes in the affected twin, time since that diagnosis, nor with age at testing the unaffected twin. On retesting 12 of the twins after two years no significant differences were found from the first testing.We conclude that not all these twins are likely to develop diabetes, that the assumption that identical twins of diabetics are necessarily “prediabetic” is probably erroneous, and that factors other than genetic ones are important in the aetiology of diabetes.     

U-21,963, a New Antibiotic: I. Discovery and Biological Activity

A new antibiotic, U-21,963, is produced by a new strain of Trichoderma viride. Antibiotic activity can be demonstrated against both gram-positive and gram-negative bacteria and also against a wide variety of fungi. U-21,963 is not cross-resistant with other commonly used antibiotics. U-21,963 afforded no protection against Klebsiella pneumoniae, Streptococcus pyogenes, or Staphylococcus aureus when it was injected subcutaneously into mice.     

Plasminogen activator inhibitor (type-1) in rat adrenal medulla

Summary Plasminogen activator inhibitor type-1 (PAI-1) was identified in extracts of rat adrenal medulla, and its immunohistochemical localization was studied together with that of tissue-type plasminogen activator (t-PA). By staining of adjacent sections and by doublestaining of the same section we demonstrate that the same cells of the adrenal medulla contain both PAI-1 and t-PA immunoreactivity in the cytoplasm. In addition a few ganglion cells of the adrenal medulla were found to contain PAI-1 but not t-PA. Neither of the components were found in the adrenal cortex. Analysis of extracts from isolated adrenal medulla using reverse zymography showed the presence of a plasminogen activator inhibitor with M _r46000. The inhibitory activity disappeared when the extract was passed through a column with sepharose-coupled anti-PAI-1 IgG, while the run-through from a similar column coupled with preimmune IgG still contained the inhibitor. The present findings suggest that PAI-1 could play a role in the regulation of t-PA activity in the rat adrenal gland medullary cells.     

A Genetic Analysis of Chloroplast Division and Expansion in Arabidopsis thaliana

A nuclear recessive mutant of Arabidopsis thaliana, arc5, has been isolated in which there is no significant increase in chloroplast number during leaf mesophyll cell expansion and in which there are only 13 chloroplasts per mesophyll cell compared with 121 in wild-type cells. Mature arc5 chloroplasts in fully expanded mesophyll cells are 6-fold larger than in wild-type cells. A large proportion of arc5 chloroplasts also show some degree of central constriction, suggesting that the mutation has prevented the completion of the chloroplast division process. To examine the interaction of arc loci, a double mutant was constructed between arc1, a mutant possessing many small chloroplasts, and arc5. A second double mutant was also constructed between arc3, a previously discovered mutant also possessing few large chloroplasts per cell, and arc1. Analysis of these double mutants shows that chloroplast number per mesophyll cell is greater when arc5 and arc3 mutations are expressed in the arc1 background than when expressed alone. The cell-specific nature of arc mutants was also analyzed. The phenotypic traits characteristic of arc3 and arc5 are a reduction in chloroplast number and an increase in chloroplast size in mesophyll cells: these changes are also observed in reduced form in the epidermal and guard cell chloroplasts of arc3 and arc5 plants. Analysis of parenchyma sheath cell chloroplasts suggests that in leaves of arc1 plants the normal developmental distinction between mesophyll and parenchyma sheath chloroplasts is perturbed. The relevance of these findings to the analysis of the control of chloroplast division in mesophyll cells is discussed.     

Seed transmission of turnip yellow mosaic virus in winter turnip and winter oilseed rapes

This is the first record of seed transmission of turnip yellow mosaic virus (TYMV) in oilseed and turnip rapes. The seed transmission of TYMV in a naturally infected winter turnip rape (Brassica napus var. silvestris) cultivar Perko PVH was investigated. By ELISA 1.6%, 3.2% and 8.3% seed transmission of the virus was found in seed of plants from three localities. The proportion of infected seeds produced by artificially infected plants of winter oilseed rape (Brassica napus ssp. oleifera) and winter turnip rape cultivars was determined. The virus transmission rate, expressed as the proportion of virus-infected plants which germinated from the seed was for the oilseed rape cvs Jet Neuf 0.1%, Solida 0.4%, Silesia 0.8%, Darmor 1.2%, SL-507 0.2%, SL-509 0.0% and for the winter turnip rape cv. Perko 1.5%. ELISA cannot be used in direct tests on bulk seed lots to estimate proportion of infected seed, but must be used on germinated seedlings.     

Costs and cost effectiveness of cardiovascular screening and intervention: the British family heart study.

OBJECTIVE--To measure costs and cost effectiveness of the British family heart study cardiovascular screening and intervention programme. DESIGN--Cost effectiveness analysis of randomised controlled trial. Clinical and resource use data taken from trial and unit cost data from external estimates. SETTING--13 general practices across Britain. SUBJECTS--4185 men aged 40-59 and their 2827 partners. INTERVENTION--Nurse led programme using a family centered approach, with follow up according to degree of risk. MAIN OUTCOME MEASURES--Cost of the programme it self; overall short term cost to NHS; cost per 1% reduction in coronary risk at one year. RESULTS--Estimated cost of putting the programme into practice for one year was 63 pounds per person (95% confidence interval 60 pounds to 65 pounds). The overall short term cost to the health service was 77 pounds per man (29 pounds to 124 pounds) but only 13 pounds per woman (-48 pounds to 74 pounds), owing to differences in utilisation of other health service resources. The cost per 1% reduction in risk was 5.08 pounds per man (5.92 pounds including broader health service costs) and 5.78 pounds per woman (1.28 pounds taking into account wider health service savings). CONCLUSIONS--The direct cost of the programme to a four partner practice of 7500 patients would be approximately 58,000 pounds. Annually, 8300 pounds would currently be paid to a practice of this size working to the maximum target on the health promotion bands, plus any additional reimbursement of practice staff salaries for which the practice qualified. The broader short term costs to the NHS may augment these costs for men but offset them considerably for women.