Biomedical subjects

F Bernier

Publications and source records attributed to F Bernier.

9 recordsLinked to original sources

PubMed1992

Germin isoforms are discrete temporal markers of wheat development. Pseudogermin is a uniquely thermostable water-soluble oligomeric protein in ungerminated embryos and like germin in germinated embryos, it is incorporated into cell walls.

Nascent synthesis and accumulation of germin and its mRNA mark the onset of renewed growth when wheat embryos are germinated in water. Germin is a water-soluble, pepsin-resistant protein that is not found in immature embryos, or in mature embryos before their germination. An antiserum was raised by injecting rabbits with germin that was freed of other proteins by pepsinization and gel filtration. The antiserum has been used to detect, in extracts of mature embryos from dry, ungerminated wheat grains, a protein that is antigenically related to germin. The antigenically related protein has been named pseudogermin. Pseudogermin accumulates, maximally, between 20-25-days postanthesis, then declines appreciably in amount by 30-days postanthesis, in soluble extracts of immature embryos from several wheat varieties. The antiserum was also used to identify germin and pseudogermin among the proteins extracted from cell walls and to bind immunogold to cell walls preparatory to visualizing freeze-cleaved embryos by scanning electron microscopy. Wall-associated germin accounts for about 40% of the total germin in germinating wheat embryos. Appearance of germin in the apoplast is the most conspicuous germination-related change in the distribution of cell-wall proteins. It seems that germin may act at the level of the apoplast and that pseudogermin may subsume the role of germin at low water potentials during embryogenesis. The N-terminal eicosapeptide sequences in germin and pseudogermin are very similar but SDS/PAGE analysis detects discrete differences between the mobilities of their constituent monomers as well as gross differences between the stabilities of the parent oligomers. Like germin, pseudogermin is a water-soluble, pepsin-resistant protein, but pseudogermin has unprecedented disulphide-independent thermostability properties that have never been previously reported for a water-soluble oligomeric protein. Polysaccharides that co-purify with otherwise pure specimens of germin (and pseudogermin) have been isolated for analysis and shown to be highly substituted glucuronogalactoarabinoxylans. The possible biological significance of selective and tenacious association between germin and glucuronogalactoarabinoxylans is discussed in relation to cell expansion during embryogenic and germinative development of wheat, as are some peculiarities of amino-acid sequence that suggest a possible relation between germin and a proton-specific ion pump: gastric ATPase.

Amino Acid Sequence↗

PubMed1992

The legumin boxes and the 3' part of a soybean beta-conglycinin promoter are involved in seed gene expression in transgenic tobacco plants.

beta-conglycinin is one of the major seed storage proteins in soybean. It is composed of three subunits, namely alpha, alpha' and beta. The expression of beta-conglycinin is highly regulated, being restricted to the embryo during the mid-maturation phase of embryogeny. Two series of constructs were made with the alpha' subunit promoter and the GUS reporter gene to investigate the cis-acting elements involved in the regulated expression of this promoter. The activity of each construct was tested in transgenic tobacco plants. In the first series of constructs, we checked if the 'legumin box', a sequence found in most legume seed storage protein genes as well as in other seed-specific genes, is involved in the regulated expression of the alpha' subunit of the beta-conglycinin gene in tobacco. To this end, both copies of the alpha' subunit promoter legumin boxes were mutagenized in vitro. The transcriptional activity of the single mutants and the double mutant were compared with that of the wild-type promoter. Our results show that the legumin boxes act together to increase transcription of the beta-conglycinin alpha' subunit gene by about a factor of ten. This is the first demonstration of a function for the legumin box in transcriptional regulation. In the second series of experiments, we wished to determine if the 3' part of the promoter (the CCAAT and TATAA region) contains important regulatory elements. We found that this small fragment (-82 to +13 bp) can confer by itself a low level of seed-specific gene expression. Chimaeric promoters constructed from parts of the alpha' subunit promoter and of the constitutive CaMV 35S promoter were also analysed. These constructs also revealed the importance of the CCAAT and TATAA region of the alpha' subunit promoter in seed-specific gene expression.

Antigens, Plant↗

PubMed1992

Congenital hydrocephalus secondary to Walker-Warburg syndrome identified on the Manitoba Neonatal Screening Programme for Duchenne muscular dystrophy.

This report describes our first experience with a clinically important true false positive neonatal screening test for Duchenne muscular dystrophy (DMD). Neonatal screening for DMD began as a pilot programme in Manitoba on 1 January 1986 by analysis of creatine kinase (CK) activity in dried filter paper blood spots. To date, all except two males with positive initial and follow up neonatal CK screening tests were subsequently diagnosed as having DMD. Of these two, one was a newborn male with congenital hydrocephalus whose positive DMD screening test led to the identification of an associated congenital myopathy and confirmation of the diagnosis of Walker-Warburg syndrome.

Biopsy↗

PubMed1991

Homologies between members of the germin gene family in hexaploid wheat and similarities between these wheat germins and certain Physarum spherulins.

By screening approximately 10(6) plaques in a wheat DNA library with a "full-length" germin cDNA probe, two genomic clones were detected. When digested with EcoRI, one clone yielded a 2.8-kilobase pair fragment (gf-2.8) and the other yielded a 3.8-kilobase pair fragment (gf-3.8). By nucleotide sequencing, each of gf-2.8 and gf-3.8 was found to encode a complete sequence for germin and germin mRNA, and to contain appreciable amounts of 5'- and 3'-flanking sequences. The "cap" site in gf-2.8 was determined by primer extension and the corresponding site in gf-3.8 was deduced by analogy. The mRNA coding sequences in gf-2.8 and gf-3.8 are intronless and 87% homologous with one another. The 5'-flanking regions in gf-2.8 and gf-3.8 contain recognizable sites of what are probably cis-acting elements but there is otherwise little if any significant similarity between them. In addition to putative TATA and CAAT boxes in the 5'-flanking regions of gf-2.8 and gf-3.8, there are AT-rich inverted-repeats, GC boxes, long purine-rich sequences, two 19-base pair direct-repeat sequences in gf-2.8, and a remarkably long (200-base pair) inverted-repeat sequence (approximately 90% homology) in gf-3.8. An 8% difference between the mature-protein coding regions in gf-2.8 and gf-3.8 is reflected by a corresponding 7% difference between the corresponding 201-residue proteins. Most significantly, the same 8% difference between the mature-protein coding regions in gf-2.8 and gf-3.8 is allied with no change whatever in a central part (61-151) of the encoded polypeptide sequences. It seems likely that this central, strongly conserved core in the germins is of first importance in the biochemical involvements of the proteins. When an equivalence is assumed between like amino acids, the gf-2.8 and gf-3.8 germins show significant (approximately 44%) similarity to spherulins 1a and 1b of Physarum polycephalum, a similarity that increases to approximately 50% in the conserved core of germin. Near the middle (87-96) of the conserved core in the germins is a rare PH(I/T)HPRATEI decapeptide sequence which is shared by spherulins (1a and 1b) and germins (gf-2.8 and gf-3.8). These similarities are discussed in the context of evidence which can be interpreted to suggest that the biochemistry of germins and spherulins is involved with cellular, perhaps cell-wall responses to desiccation, hydration, and osmotic stress.(ABSTRACT TRUNCATED AT 400 WORDS)

Amino Acid Sequence↗

PubMed1991

Multiple nuclear factors interact with upstream sequences of differentially regulated beta-conglycinin genes.

The expression of the alpha' and beta subunit genes of beta-conglycinin is differentially regulated during soybean embryo development. Although both are expressed solely in developing seeds during mid to late stages of embryo development, the alpha' subunit is expressed more highly on a per gene basis, and alpha' subunit mRNA begins to accumulate three to five days earlier than beta subunit mRNA. In cultured cotyledons, beta subunit gene(s) respond to changes in methionine or abscisic acid levels, whereas expression of the alpha' subunit gene(s) is unaffected by these changes. To investigate the mechanisms by which these genes are transcriptionally regulated, we examined the interactions of nuclear proteins with upstream sequences from the alpha' and beta subunit genes. Four distinct DNA binding factors were identified in nuclear extracts from developing soybean seeds. These factors are termed Soybean Embryo Factors (SEF) 1 through 4. SEF binding sites are distributed non-uniformly between the alpha' and beta subunit genes, and the amount of protein binding is modulated over the course of embryo development. DNA footprinting revealed the sequences recognized by three of these factors. Factors which behave in a manner similar to that of SEF3 were also identified in nuclear extracts from developing tobacco and sunflower seeds.

Antigens, Plant↗

PubMed1989

Nuclear factors interact with a soybean beta-conglycinin enhancer.

Upstream sequences of the gene encoding the alpha' subunit of beta-conglycinin were analyzed for interactions with nuclear proteins from immature soybean seeds. Two factors were identified that interact with specific sequence elements within 257 base pairs 5' of the transcription start site. One factor, SEF 3, binds exclusively to a region composed of two elements located at -183 to -169 base pairs and -153 to -134 base pairs relative to the start of transcription. Each of these sites includes the hexanucleotide sequence AACCCA, which may serve as a primary recognition sequence. During seed development, SEF 3 binding activity was found to increase in soybean embryos during the time of beta-conglycinin synthesis and to decrease as seeds neared maturity. The position of the SEF 3 binding sequence corresponds with a previously reported seed-specific enhancer region, and it seems likely that this factor may act as a positive regulator of transcription of the beta-conglycinin, alpha' subunit gene in developing soybean seeds. The second factor, SEF 4, also binds within the -257 to -77 region but also interacts with sites located further upstream.

Antigens, Plant↗

PubMed1989

Lung embolism with liquid silicone.

A lung embolism was reported in a case involving death following repeated injections of liquid silicone for aesthetic reasons. The liquid extracted from the sites of injection was identified as methylsilicone using infrared spectrophotometry, and the presence of silicone in vacuoles in the lung was verified by scanning electron microscopy with energy dispersive X-ray analysis (EDXA). A study has been carried out with rats after intravenous and subcutaneous injections of methylsilicone.

Adult↗

PubMed1987

Gene families encode the major encystment-specific proteins of Physarum polycephalum plasmodia.

The encystment of Physarum polycephalum plasmodia, also called spherulation, involves the synthesis of many specific mRNAs and proteins. Most of these molecules accumulate at the onset of the major morphological and physiological changes typical of this differentiation pathway and are not present during the other two transitions leading to dormancy in Physarum, namely sporulation and encystment of amoebae. The nucleotide sequences of apparently full-length cDNA copies of the four major encystment-specific mRNAs were determined. The four sequences included the entire coding regions and at least 26 nucleotides of the 5'-nontranscribed leaders. The encoded proteins were named spherulins. We found that spherulins 1a and 1b are 81% homologous and are thus members of a gene family. They both possess putative signal peptides and N-glycosylation sites, suggesting that they are cell-wall glycoproteins. Spherulin 2a and spherulin 3a are non-homologous proteins. The absence of signal peptides suggests that they are intracellular structural proteins. Low-stringency Southern hybridizations showed that each also belongs to a two-member gene family.

Amino Acid Sequence↗

PubMed1979

[Ileostomy].

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Activities of Daily Living↗