Biomedical subjects

R Panitz

Publications and source records attributed to R Panitz.

18 recordsLinked to original sources

PubMed2001

Identification of genes specifically expressed in maternal and filial tissues of barley caryopses: a cDNA array analysis.

Developing seeds consist of genetically distinct maternal and filial tissues, whose interactions during development are largely unknown. To better understand the molecular physiology of developing seed tissues in barley, we created a high-density cDNA macroarray bearing 711 cDNA fragments from 691 clones representing at least 620 unique genes mainly derived from a cDNA library constructed with mRNA from the early stages of caryopsis development. This array has been used to compare gene expression patterns in maternal pericarp and filial embryo sac tissues of caryopses sampled 1-7 days after flowering (DAF). The profiles obtained for both tissues revealed that at least 26 genes in pericarp and 12 genes in embryo sac tissues were up-regulated by more than a factor of two during this period. RNAs expressed at high levels in the pericarp mainly encode enzymes involved in carbohydrate and lipid metabolism, but also include mRNA for a transcription factor related to FILAMENTOUS FLOWER (FIL). Genes preferentially expressed in the embryo sac are mainly related to degradation and/or processing of proteins or are involved in the process of starch accumulation, which begins in the seed at this time. Some of the most conspicuously regulated genes were studied in more detail by Northern analysis and in situ hybridization. The mRNA with the highest apparent signal intensity encodes a methionine synthase (MSY). MSY is highly expressed throughout the pericarp and to a lower extent in the transfer cell layer of the endosperm. Of special interest is a gene of unknown function because its high-level expression is restricted to the nucellar projection, the maternal transfer tissue of the caryopsis. This gene, represented by clone HY09L21, may play a central role in transport processes and thus in embryo growth.

5-Methyltetrahydrofolate-Homocysteine S-Methyltran↗

PubMed2000

Sucrose transport into barley seeds: molecular characterization of two transporters and implications for seed development and starch accumulation.

In order to understand sucrose transport in developing seeds of cereals at the molecular level, we cloned from a caryopses library two cDNAs encoding sucrose transporters, designated HvSUT1 and HvSUT2. Sucrose uptake activity was confirmed by heterologous expression in yeast. Both transporter genes are expressed in maternal as well as filial tissues. In a series of in situ hybridizations we analysed the cell type-specific expression in developing seeds. HvSUT1 is preferentially expressed in caryopses in the cells of the nucellar projection and the endospermal transfer layer, which represent the sites of sucrose exchange between the maternal and the filial generation and are characterized by transfer cell formation. HvSUT2 is expressed in all sink and source tissues analysed and may have a general housekeeping role. The rapid induction of HvSUT1 gene expression in caryopses at approximately 5-6 days after fertilization coincides with increasing levels of sucrose as well as sucrose synthase mRNA and activity, and occurs immediately before the onset of rapid starch accumulation within the endosperm. Starch biosynthesis requires sucrose to be imported into the endosperm, as direct precursor for starch synthesis and to promote storage-associated processes. We discuss the possible role of HvSUT1 as a control element for the endospermal sucrose concentration.

Base Sequence↗

PubMed1994

Tissue-specific expression of an oat 12S seed globulin gene in developing tobacco seeds: differential mRNA and protein accumulation.

We studied the expression of the oat globulin gene asglo5 in developing transgenic tobacco seeds. The asglo5 gene promoter directed transcription in the endosperm as well as in the provascular tissue, the presumptive root tip and the shoot apical meristem of the embryo as revealed by GUS reporter gene constructs and in situ hybridization. However, immunological tissue printing detected the oat protein exclusively in the tobacco endosperm, suggesting that extensive post-transcriptional regulatory processes influence the expression of the monocot transgene in the dicot host.

Allergens↗

PubMed1993

In situ localization of faba bean and oat legumin-type proteins in transgenic tobacco seeds by a highly sensitive immunological tissue print technique.

We have used a highly sensitive immunological tissue print technique to study cell- and tissue-specific expression of heterologous genes in transgenic plants. Primary polyclonal antibodies, raised against legumin of faba bean (Vicia faba L.) and 12S globulin of oat (Avena sativa L.) were used to localize these proteins in transgenic tobacco seeds in a streptavidin-alkaline phosphatase assay in combination with biotinylated secondary antibodies producing a higher sensitivity (by several amplification steps) of the assay. Both storage protein genes were found to be expressed in a specific pattern. While legumin is preferentially accumulated in certain parts of the embryo, the oat legumin-type globulin is restricted to the endosperm. The applied technique is highly sensitive with a resolution power down to the single-cell level and allows rapid screening of large numbers of samples.

Edible Grain↗

PubMed1991

Upstream sequences regulating legumin gene expression in heterologous transgenic plants.

We have previously isolated a legumin gene LeB4 from Vicia faba and shown that a 4.7 kb DNA fragment containing the gene leads to seed-specific expression in transgenic tobacco plants. Here we report that the 2.4 kb upstream sequence alone, when fused to either the neomycin phosphotransferase II (nptII) gene or the beta-glucuronidase (uidA) gene, leads to high enzyme levels in transgenic seeds of both tobacco and Arabidopsis. beta-Glucuronidase (GUS) activity is especially intense in the cotyledons fading out towards the embryonal root tip, a result confirmed by in situ hybridization. Staining of endosperm cells is consistent in both species. Analysis of a series of promoter deletion mutants fused to the nptII gene and introduced into tobacco plants revealed that about 1 kb of 5'-flanking sequence is sufficient for high-level expression but indirect evidence suggests the presence of weak positive regulatory elements further upstream. Deletions leaving only 0.2 kb of upstream sequence reduce enzyme levels to less than 10%. A deletion which destroys the legumin box with its seed protein gene-specific CATGCATG motif has no obvious effects on expression levels.

Blotting, Southern↗

PubMed1990

A new transposable element in Chironomus thummi.

A 1.7 kb long transposable element called TECth1 was found in the 3' flanking region of a Chironomus thummi Balbiani ring gene. As shown by sequence comparison with a second copy, TECth1 is characterized by a perfect terminal inverted repeat of 17 bp flanked by a duplicated target site of 8 bp, four internal imperfect inverted repeats of 17 to 26 bp and terminal regions of about 0.25 kb with a high number of short direct repeats of the consensus sequence ACTTT or permutated and mutated forms such as TTTAC or ACTAT. The terminal inverted repeats and the 8 bp target site duplication are reminiscent of Drosophila P and hobo elements but no long open reading frame starting with ATG is present, suggesting that the two TECth1 copies studied represent deletion derivatives of a longer element coding for its own transposase. In situ hybridization revealed about 75 labelled sites distributed over all chromosomes with the Balbiani ring locus most strongly labelled. Fifty percent of the sites are specific for a given individual, and these variable sites are often heterozygous for the element.

Animals↗

PubMed1984

Self-complementary DNA sequences within the BRc gene of Chironomus thummi.

The Balbiani ring c (BRc) DNA of Chironomus thummi consists of tandemly arranged 249-base pair (bp) repeats, which represent the major part of the gene (Bäumlein et al. 1982a) and are transcribed and translated in a periodic polypeptide of unusual size. To obtain further information on the DNA sequence organization of that gene a recombinant phage (lambda CthBRc-1) with a relatively long insert (containing predominantly 249-bp repeats) was studied by electron microscopy (EM). lambda CthBRc-1 was found to undergo specific sequence elimination of BRc DNA resulting in heterogeneous size distribution of insert length within the limits of the cloning capacity of the phage with a maximum around 15 kilobase pairs (kb). The EM analysis of R loops formed between recombinant molecules and poly(A)+RNA (containing the transcripts of BRc and BRb) revealed the existence of self-complementary inverted and direct repeats as further sequence elements of BRc DNA scattered throughout a long portion of the BRc transcription unit. Different intrastrand structures (stems, hairpins, complex loops) originate from the renaturation of several sets of self-complementary repeats. Most double-stranded regions fell into one main-size class with an average length of 0.1 kb. The overall data suggest that self-complementary repeats belong to the same DNA sequence family and are able to cooperate in the formation of loops of different size and complexity. The results are discussed in relation to the functional significance of self-complementary inverted repeats (palindromes) for BRc expression.

Animals↗

PubMed1980

Periodicities and tandem repeats in a Balbiani ring gene.

The Balbiani ring (BR) DNAs show prominent periodicities of restriction enzyme sites. Studies using a cloned fragment of the BRc gene strongly suggest that these periodicities reflect the existence of tandemly repetitive sequences within BR DNA. Tandem repeats measuring 54-58 bp have been demonstrated by partial sequence analysis of the BRc clone; the restriction site periodicities suggest the existence of additional 175 (= 3 X 58) and 1050 (= 6 X 175) bp repeat units. The short, medium and long repeats (58, 175 and 1050 bp, respectively) show sequence homology. Constrained unequal crossing over (resulting from misalignment of repeat arrays, usually by one repeat) is proposed as the mechanism for evolution of short, medium and long repeats from each other, in a manner analogous to evolution of satellite DNA sequences. Paradoxically, the dominant restriction site periodicities appear to be more conservative than might be expected on the basis of the overall sequence divergence between the sequenced repeats. This may be a consequence of functionally important, long-range amino acid or oligopeptide periodicities (for example, Asp x Ser or Glu x Ser corresponding to Hinf I sites) in the BRc protein product, in conjunction with preferential use of certain synonymous codons.

Animals↗

PubMed1979

Two transcripts of an individual Balbiani ring from the salivary gland cells of Acricotopus lucidus (Diptera, Chironomidae).

The polytene chromosomes in main lobe cells of the Acricotopus salivary gland carry two large Balbiani rings (BR1, BR2), which BR1 exhibits the higher incorporation rate of tritiated nucleosides. The size of BR1 varies in conjunction with a subterminal inversion which includes the BR1 site. BR1 in both the homozygous and heterozygous inverted arrangement (BR1A and BR1B, respectively) is consistently smaller than in the homozygous standard arrangement (BR1C). The RNA content of BR1A and BR1C (3.1 and 6.7 pg, respectively) corresponds well with their relative size.--Using the method of micromanipulation of squashed salivary gland chromosomes the RNA transcripts of BR1A and BR1C have been extracted from microdissected Balbiani rings and fractionated by electrophoresis on 1% agarose gels. In BR1A one RNA fraction with a molecular weight of about 40 x 10(6) D is transcribed. The gel electrophoretic pattern of BR1C is characterized by an additional RNA fraction of 5 x 10(6) D. The main part of BR1 RNA is bound to oligo(dT)-cellulose suggesting the adenylation at the chromosome of Balbiani ring RNA.--In the profile of poly(A)-containing cytoplasmic RNA obtained after in vivo labelling two peaks can be detected which correspond in size to the BR1 RNA. These putative BR1 transcripts accumulate to a high concentration in the cytoplasm and show a relatively low stability during in vivo chase experiments.

Animals↗

PubMed1978

Cell specific effect of ecdysone on RNA synthesis in the differentiated salivary gland of Acricotopus lucidus.

The influence of the steroid hormone ecdysone on the RNA metabolism of 2 cell types (main and anterior lobe) of the Acricotopus salivary gland has been investigated. Ecdysone has been found to increase the synthesis of 4S RNA and poly(A)+ RNA in the main lobe, while the anterior lobe remained unaffected by the same treatement. The stimulated poly(A)+ RNA is characterized by its relatively low cytoplasmic turnover. No evidence has been found for the stimulation of ribosomal RNA synthesis in both cell types. Analysis of the metabolic stability of cytoplasmic poly(A)+ RNA after ecdysone administration revealed a different response of the main and anterior lobe cells. Only in the anterior lobe ecdysone causes a shortening of the lifetime of that part of poly(A)+ RNA which is peculiar in its early appearance and relatively low stability in the cytoplasm.

Animals↗

PubMed1972