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J A Napier

Publications and source records attributed to J A Napier.

At least 19 recordsLinked to original sources
PubMed1995

Isolation and characterisation of cDNA clones representing the genes encoding the major tuber storage protein (dioscorin) of yam (Dioscorea cayenensis Lam.).

cDNA clones encoding dioscorins, the major tuber storage proteins (M(r) 32,000) of yam (Dioscorea cayenesis) have been isolated. Two classes of clone (A and B, based on hybrid release translation product sizes and nucleotide sequence differences) which are 84.1% similar in their protein coding regions, were identified. The protein encoded by the open reading frame of the class A cDNA insert is of M(r) 30,015. The difference in observed and calculated molecular mass might be attributed to glycosylation. Nucleotide sequencing and in vitro transcription/translation suggest that the class A dioscorin proteins are synthesised with signal peptides of 18 amino acid residues which are cleaved from the mature peptide. The class A and class B proteins are 69.6% similar with respect to each other, but show no sequence identity with other plant proteins or with the major tuber storage proteins of potato (patatin) or sweet potato (sporamin). Storage protein gene expression was restricted to developing tubers and was not induced by growth conditions known to induce expression of tuber storage protein genes in other plant species. The codon usage of the dioscorin genes suggests that the Dioscoreaceae are more closely related to dicotyledonous than to monocotyledonous plants.

Amino Acid Sequence↗
PubMed1995

Expression and in vitro targeting of a sunflower oleosin.

Two distinct cDNAs encoding oleosins (oil body proteins) have been identified by degenerate PCR as transcripts present in the developing seeds of sunflower (Helianthus annuus L. cv. Dwarf Sunbred). One (pSOM) of these is closely related to a reported sunflower oleosin, whilst the other (pSO5) has not been previously described. Different expression patterns were observed for the two cDNAs, pSO5 being expressed earlier than pSOM in seed maturation and oil deposition. The results support the contention that oleosin proteins are synthesised either during or closely after the formation of the oil body. Translation in vitro of synthetic oleosin transcripts was enhanced by the addition of microsomes but suppressed by the addition of purified signal recognition particle (SRP) complex. Deletion of 62 amino acid residues at the C-terminus of the oleosin did not alter the in vitro targeting of the protein to the microsomal membrane. Taken together these data support the idea that oleosins are targeted to the ER membrane as part of oil body biogenesis.

Amino Acid Sequence↗
PubMed1995

Isolation of a cDNA encoding a cytochrome b5 specifically expressed in developing tobacco seeds.

Polymerase chain reaction (PCR) was used to amplify transcripts encoding cytochrome b5 from cDNA synthesised from RNA isolated from developing seeds of tobacco (Nicotiana tabacum L.). The sequence of the amplified products indicated that the clones encoded a second form of tobacco cytochrome b5, different from that previously characterised (Smith et al. 1994, Plant Mol Biol 25:527-537). Rapid amplification of cDNA ends (RACE)-PCR was used to amplify the 5' and 3' ends of the transcript. Northern blotting and RNAse protection assays of RNA samples isolated from different tobacco tissues indicated that this second cytochrome b5 form was expressed only in developing seeds. Therefore, it seems likely that this message is the product of a tobacco cytochrome b5 gene specifically expressed in seeds.

Amino Acid Sequence↗
PubMed1992

Import and processing of the precursor of the Rieske FeS protein of tobacco chloroplasts.

cDNA clones encoding the precursor of the Rieske FeS protein of tobacco chloroplasts have been characterised and shown to derive from two different genes. The 5' ends of the corresponding transcripts have been cloned using primer extension and PCR. The nucleotide sequences of the cDNAs (and their 5' extensions) predict precursors for the tobacco proteins which differ in 4 amino acid residues out of a total of 228 residues and show high homology with the pea and spinach precursors. The tobacco precursor proteins contain N-terminal presequences of 49 amino acid residues which lack 17 amino acid residues present at the N-terminus of the spinach presequence. The 26 kDa precursor obtained by transcription and translation of one of these cDNAs in vitro was efficiently imported and correctly processed to the mature 20 kDa protein by isolated pea or tobacco chloroplasts. The precursor was also processed to its mature size by a peptidase present in the stroma of chloroplasts.

Amino Acid Sequence↗
PubMed1992

Import and processing of the precursor form of the gamma subunit of the chloroplast ATP synthase from tobacco.

A cDNA clone encoding the complete precursor of the gamma subunit of chloroplast ATP synthase has been isolated from a tobacco (Nicotiana tabacum) leaf cDNA library in lambda gt11. The 1.4 kb insert encodes a polypeptide of 377 amino acid residues, of which 55 residues constitute an N-terminal presequence and 322 residues make up the mature gamma subunit. Hybridisation of the cDNA to Southern blots of tobacco genomic DNA indicates the presence of two genes in the haploid genome. Transcription and translation of the cDNA in vitro produced a protein of 41 kDa which was imported by isolated pea chloroplasts and processed to the mature 36 kDa subunit. The gamma subunit precursor was processed to the mature size by a processing peptidase of 180 kDa present in pea stromal extracts.

Amino Acid Sequence↗
PubMed1992

Import and processing of the precursor of the delta subunit of tobacco chloroplast ATP synthase.

A cDNA clone encoding the complete precursor of the delta subunit of chloroplast ATP synthase has been isolated from a tobacco (Nicotiana tabacum) leaf cDNA library in lambda gt11. The 880 bp insert encodes a polypeptide of 248 amino acid residues, of which 61 residues constitute an N-terminal presequence and 187 residues make up the mature delta subunit. Transcription and translation of the cDNA in vitro produced a protein of 29 kDa which was imported by isolated pea chloroplasts and processed to the mature 20 kDa subunit. The delta subunit precursor was processed to the mature size by a processing peptidase present in pea stromal extracts. Hybridisation of the cDNA to Southern blots of tobacco genomic DNA suggests the presence of two genes in the haploid genome.

Amino Acid Sequence↗
PubMed1992

Import of the precursor of the chloroplast Rieske iron-sulphur protein by pea chloroplasts.

cDNA clones encoding the precursor of the Rieske FeS protein of the chloroplast thylakoid membrane have been isolated from a pea leaf cDNA library in lambda gt 11, following screening with antibodies to purified pea chloroplast Rieske FeS protein. The longest cDNA insert of 880 bp encodes a polypeptide of 230 amino acid residues, of which 50 residues constitute an N-terminal cleavable presequence and 180 residues make up the mature protein. Transcription and translation of the cDNA in vitro produced a polypeptide of 26 kDa which was efficiently imported by isolated pea chloroplasts and processed to the mature 20 kDa protein. Southern hybridisation to pea genomic DNA indicated the presence of a single gene encoding the Rieske FeS protein in the haploid genome.

Amino Acid Sequence↗
PubMed1992

Chloroplast import of the precursor of the gamma subunit of pea chloroplast ATP synthase.

A cDNA clone encoding the complete precursor of the gamma subunit of the pea chloroplast ATP synthase has been isolated from a pea leaf cDNA library in lambda gt 11 following detection with antibodies to the purified gamma subunit. The cDNA insert of 1.4 kbp is smaller than transcripts of about 1.6 kb detected by northern hybridisation of RNA from both light- and darkgrown pea leaves. The cDNA encodes a polypeptide of 376 amino acid residues, of which 52 residues constitute an N-terminal presequence and 324 residues make up the mature protein. Transcription and translation of the cDNA in vitro produced a protein of 42 kDa, which was imported by isolated pea chloroplasts and processed to the mature 36 kDa subunit.

Adenosine Triphosphatases↗
PubMed1992

Guidelines for the use of fresh frozen plasma. British Committee for Standards in Haematology, Working Party of the Blood Transfusion Task Force.

Fresh frozen plasma should only be used to treat bleeding episodes or prepare patients for surgery in certain defined situations. Definite indications for the use of FFP: 1. Replacement of single coagulation factor deficiencies, where a specific or combined factor concentrate is unavailable. 2. Immediate reversal or warfarin effect. 3. Acute disseminated intravascular coagulation (DIC). 4. Thrombotic thrombocytopenic purpura (TTP). Conditional uses: FFP only indicated in the presence of bleeding and disturbed coagulation: 1. Massive transfusion. 2. Liver disease. 3. cardiopulmonary bypass surgery. 4. Special paediatric indications. No justification for the use of FFP: 1. Hypovolaemia. 2. Plasma exchange procedures. 3. 'Formula' replacement. 4. Nutritional support. 5. Treatment of immunodeficiency states.

Adult↗
PubMed1991

The crossmatch.

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Blood Grouping and Crossmatching↗
PubMed1988

Massive feto-maternal haemorrhage: effect of passively administered anti-D in the prevention of Rh sensitization and haemolytic disease of the newborn.

Fourteen mothers carrying ABO compatible but Rh D incompatible pregnancies experienced large feto-maternal haemorrhages (estimated 188 ml, range 50-400 ml red cells). These were all treated with infusions of fresh frozen plasma containing anti-D at a mean immunoglobulin to fetal cell ratio of 129 i.u. (25.8 micrograms)/ml of fetal cells. At 48 h after the infusion 95% of fetal cells had been removed but 3 to 4 days were required for complete removal. The passively administered anti-D was detectable for up to 6-9 months but not after that time. Four of the 14 women had successful pregnancies subsequently although in two of these anti-C + D was present. Of these, one resulted in a clinically affected baby who survived exchange transfusion.

Erythroblastosis, Fetal↗
PubMed1987

Transfusion significance of LWa allo-antibodies.

An example of anti-LWa, arising as a complication during a RhD immunization programme, has been studied for evidence of its likely in vivo haemolytic properties. In vitro testing of the anti-LWa showed it to be largely IgG1 acting by the antiglobulin technique. Results of antibody-dependent cellular cytotoxicity and macrophage phagocytic assays were both negative. However, 99mTc-labelled Lw(a+) donor cells showed a slight reduction in t1/2 (18 h) compared with the normal survival of autologous cells. Despite this observation, and bearing in mind the difficulties of interpreting apparently accelerated destruction of small serologically incompatible red cells, it was concluded that the presence of this example of anti-LWa should not be a bar to urgent transfusion.

Aged↗
PubMed1987

Oral administration of erythrocyte membrane antigen does not suppress anti-Rh(D) antibody responses in humans.

The effects of prior oral administration of erythrocyte membrane preparations (Oral Rh antigen) on the serum anti-Rh(D) antibody response has been evaluated in non-sensitized Rh(D)-negative male volunteers, and in female volunteers sensitized previously by Rh(D)-positive fetal blood during pregnancy. Sixty-one percent (11/18) of males who received oral Rh antigen (either D-positive or D-negative) before intravenous challenge with Rh(D)-positive cells produced detectable antibodies; of these 11, six received oral Rh(D)-negative antigen and five received oral Rh(D)-positive antigen. Seventy-two percent (13/18) of control males, who had received no prior oral Rh antigen, produced antibodies following challenge with Rh(D)-positive cells. Three out of six pre-sensitized females who received oral D-positive or D-negative Rh antigen for 4 weeks, but without intravenous challenge, increased their anti-Rh(D) antibody levels which peaked after 11-18 weeks: two had received Rh(D)-positive antigen, and one Rh(D)-negative antigen. These data indicate that administration of oral Rh antigen before parenteral immunization does not significantly suppress the anti-Rh(D) antibody response. Indeed, oral administration of either Rh(D)-positive or Rh(D)-negative antigen can boost systemic antibody in pre-sensitized females. These results do not support the rationale of treating Rh-sensitized pregnant women with oral Rh antigen.

Administration, Oral↗