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W Kunz

Publications and source records attributed to W Kunz.

At least 37 records · Page 2Linked to original sources
PubMed1997

Female-specific gene expression in Schistosoma mansoni is regulated by pairing.

Gene expression studies in adult females of Schistosoma mansoni cultured in vitro revealed that the transcription of female-specifically expressed genes is influenced by pairing. In contrast, the activity of genes that are expressed in both genders was not affected by contact with the male. The transcription of genes was monitored in paired, separated and remated females. The transcript level of female-specifically expressed genes decreases within a few days following separation from males. Remating of uncoupled females with males leads to the reinitiation of transcription. These results provide strong evidence for the influence of the male on gene transcription in the female and contribute a molecular basis for the classical histological observation that the maturation of females is male dependent. The data also show that the culture system is suitable to monitor gene expression and, furthermore, they indicate de novo RNA synthesis in vitro.

Animals↗
PubMed1997

Identification of Ras, MAP kinases, and a GAP protein in Schistosoma mansoni by immunoblotting and their putative involvement in male-female interaction.

The maturation of female Schistosoma mansoni depends on pairing with a male which induces mitotic activities in the reproductive organs of the female worm. Since in other organisms cell proliferation is regulated by well-conserved signal transducing molecules, we looked for such molecules on immunoblots of schistosomes, using antibodies against conserved epitopes of Ras, GAP and MAP kinases. We identified all 3 molecules in schistosomes and found that they are developmentally regulated. Furthermore, there is evidence for their involvement in the male-directed maturation of the female.

Amino Acid Sequence↗
PubMed1996

Direct PCR on fruitflies and blood flukes without prior DNA isolation.

DNA is the essential substrate for the polymerase chain reaction (PCR). Standard protocols include a DNA purification step, but this is laborious if a large number of DNA preparations have to be performed, although a variety of simple methods exist for the isolation of crude DNA for PCR. For microorganisms, PCR protocols exist that allow the amplification of sequences directly from the organism without DNA purification. The results introduced in this paper demonstrate that a direct PCR approach also works with fruitflies and blood flukes as examples for intact multicellular organisms.

Animals↗
PubMed1996

Ferritin mRNAs in Schistosoma mansoni do not have iron-responsive elements for post-transcriptional regulation.

Schistosoma mansoni possesses two isoforms of ferritin, soma and yolk ferritin. The soma ferritin occurs at a low level in most cells of both genders, whereas the yolk ferritin is a female-specific gene product that is expressed at high level in the vitellarium. In higher animals, ferritin mRNA is regulated by iron via the interaction of cytoplasmic binding proteins (IRPs) with a specific sequence element in the 5' untranslated region (UTR) referred to as the iron-responsive element (IRE). Sequence studies of the 5' UTRs, gel retardation assays, and hybridization experiments show that neither ferritin mRNAs of S. mansoni is regulated by an IRE/IRP mechanism. It is suggested that ferritins in schistosomes are controlled only at the transcriptional level.

Animals↗
PubMed1996

Paramyosin isoforms of Schistosoma mansoni are phosphorylated and localized in a large variety of muscle types.

Paramyosin, although a widely distributed muscle component among invertebrates, has hitherto not clearly been shown to occur in the muscles of schistosomes. Instead, it has been reported to occur in the tegument. In the present study, a specific antibody reacting with each of 10 isoforms of paramyosin was used for light microscopical immunolocalization in sections of Schistosoma mansoni. Specimens were fixed by a new method to immobilize antigens with uranyl acetate-trehalose-methanol. In cercariae, schistosomula, and adults, the circular and longitudinal muscles of the body wall, the dorsoventral muscles and those surrounding the gut and the pharynx as well as the fast moving cross-striated muscles of the tail of cercariae intensely reacted with the antibody. However, neither immunohistologically nor on Western blots of isolated tegument, were indications found for the presence of paramyosin in the tegument. In vivo phosphorylation and binding of anti-phospho-tyrosine and anti-phospho-serine antibodies show phosphorylation of paramyosin which probably is responsible for the generation of the isoforms.

Animals↗
PubMed1995

An isoform of ferritin as a component of protein yolk platelets in Schistosoma mansoni.

Schistosoma mansoni possesses two isoforms of the iron storage protein ferritin, Fer1 and Fer2. At the mRNA level as well as at the protein level, Fer1 is much more abundant than Fer2; females contain an about 15-fold excess of Fer1 compared with males. In contrast, nearly equal amounts of Fer2 occur in both sexes. By electron microscopy we identified ferritin as a component of electron dense membrane-bound bodies in cells of the vitellarium. The mode of formation of these inclusions (as inferred from electron microscopy) and the abundance of phospholipid multilayered membranes suggest that these bodies are of a lysosomal nature. Here we interpret these ferritin-containing inclusions as protein yolk platelets. To date, most of the literature does not contain any hints of the existence of protein yolk in trematodes. The possible function of ferritin in embryonic development is discussed.

Animals↗
PubMed1995

Sequence, characterization and localization of a cysteine proteinase cathepsin L in Schistosoma mansoni.

A cDNA encoding Schistosoma mansoni cathepsin L was isolated from a cDNA library and sequenced. Alignment of the proposed amino-acid sequence with known members of cathepsin L shows highest homologies with sequences from mouse and rat. An expression plasmid was constructed in Escherichia coli to produce recombinant schistosome cathepsin L with an extension of six histidines at its N terminus. Using antibodies raised against the purified fusion protein, two polypeptide bands with approx. molecular masses of 38 and 31 kDa were identified in a schistosome extract. By use of specific radioiodinated inhibitors, a radioactively labeled protein could be detected at 31 kDa, suggesting that this is the active mature enzyme. The larger protein of 38 kDa did not react with the inhibitor, indicating that it represents the inactive precursor molecule. Immunohistological experiments revealed that the proteinase is localized in structures associated with the reproductive system of females and with the subtegumental region of the gynecophoric canal of males. However, Northern blot hybridization demonstrates that more transcripts are present in female parasites than in males. Genomic Southern blotting suggests that schistosome cathepsin L is expressed from a single-copy gene.

Amino Acid Sequence↗
PubMed1995

A female-specific cDNA sequence of Schistosoma mansoni encoding a mucin-like protein that is expressed in the epithelial cells of the reproductive duct.

Seven cDNA clones of Schistosoma mansoni containing the C-terminal part of the deduced sequence of a mucin-like protein have been identified. The protein contains 28% threonines, 20% serines, and has a pI of 3.4. On Northern blots of RNA of adult worms, the cDNA clones detect 2 transcripts of 1.65 and 4.2 kb which are expressed only in female worms. The tissue of gene expression, as revealed by in situ hybridization, is the epithelium surrounding the female reproduction duct proximal to its entrance into the ootype. Accumulation of N-glycosylation sites suggests that the protein, like other mucins, might form a protective layer, coating the lining of the duct. Regarding its acidic pI, we hypothesize a role in preventing premature egg-shell formation. This is the first female-specifically transcribed sequence, hitherto known in S. mansoni that is not expressed in the vitellaria.

Amino Acid Sequence↗
PubMed1995

[Laparoscopic ligamentum teres-plasty].

Report on 40 patients suffering from a therapy resistant gastroesophageal reflux disease. Conventional ligamentum-teres-plastic was performed on 18 patients, while 22 patients were treated laparoscopically as minimal invasive procedure. Both techniques are described and the advantages of the laparoscopy versus the conventional laparotomy are explained. As a result the ligamentum-teres-plastic is an efficient treatment for gastroesophageal reflux disease and distinguishes itself because of its relative simplicity and a low complication rate.

Adult↗
PubMed1994

Contribution to control of mitochondrial oxidative phosphorylation by supplement of reducing equivalents.

The influence of enhancing the supply of hydrogen donors on respiratory rates, NAD(P)H fluorescence, and membrane potential was investigated. Addition of 5 mM malate to mitochondria during oxidation of 10 mM isocitrate, oxoglutarate, succinate, proline, or glycerol-3-phosphate under steady-state conditions resulted in an inhibition of respiration, coincident with a decrease in both transmembrane electrical potential and percentage reduction of NAD(P). Half-maximum inhibition of NAD(P) reduction in the resting state of 10 mM isocitrate respiration was reached at 10 mM malate. This inhibition was concluded to be due to oxaloacetate formed immediately from malate by succinate dehydrogenase. Addition of 5 mM isocitrate caused higher respiratory rates, accompanied by an increase in both delta psi and percentage of NAD(P) reduction, in mitochondria oxidizing 10 mM oxoglutarate, glutamate, proline, hydroxybutyrate, glycerol-3-phosphate, or 0.025 mM palmitoyl carnitine. The half-maximum increase in percentage NAD(P) reduction with 10 mM 2-oxoglutarate as primary substrate was found at 0.24 mM isocitrate. Within the citric acid cycle, succinate dehydrogenase and NAD-isocitrate dehydrogenase play an important role in changes in the rate of NADH formation. Therefore, they participate in flux control. Furthermore, mitochondrial aspartate aminotransferase and oxidoreductases of the beta-oxidation pathway of fatty acids are additionally involved in adjusting the rate of NADH formation.

Animals↗
PubMed1994

Unusual properties of mitochondria from the human term placenta are caused by alkaline phosphatase.

Human placental mitochondria prepared by a new isolation procedure exhibit low but well coupled rates of state 3 respiration with different substrates (succinate: 32.3 nmol O2/mg/min, RCI = 4.4; pyruvate: 12.6 nmol O2/mg/min, RCI R = 4.2; palmitoylcarnitine: 16.6 nmol O2/mg/min, RCI R = 4.9). The addition of the uncoupler FCCP increased the respiratory rates (succinate: 40.7 nmol O2/mg/min; pyruvate: 21.2 nmol O2/mg/min: palmitoylcarnitine: 25.4 nmol O2/mg/min). The low respiratory rates correlate well with a low capacity of the respiratory chain as shown by the specific contents of cytochrome c (0.15 nmol/mg), cytochrome b (0.19 nmol/mg) and cytochrome oxidase (0.14 nmol/mg) as well as with the low content of adenine nucleotides (2.71 nmol/mg). These data together with the finding of high activities of alkaline phosphatase (2.2 U/mg) support the view that human placental mitochondria are contaminated with nonmitochondrial membranes. Since it was not possible to obtain functionally intact mitochondria with negligible activities of alkaline phosphatase the influence of this enzyme on the extramitochondrial adenine nucleotide turnover was investigated. Alkaline phosphatase splits phosphate from ATP, ADP and AMP with different rates resulting in an intermediate accumulation of AMP. Mitochondrial adenylate kinase (0.16 U/mg) regenerated ADP from AMP and ATP resulting in drastically decreased ADP/O ratios and prolonged state 3 respirations. Inhibiting the adenylate kinase with diadenosine pentaphosphate the ADP regeneration from AMP and ATP was suppressed which, in turn, enhanced the ADP/O ratios. In the absence of magnesium ions, if both the alkaline phosphatase and the adenylate kinase are inhibited normal ADP/O ratios and state 3-state 4 transitions can be observed. Under these conditions, human placental mitochondria showed normal properties comparable to those of mitochondria from other tissues with the only exception of low specific activities.

Adenylate Kinase↗
PubMed1994

Characterization of the complete protein disulfide isomerase gene of Schistosoma mansoni and identification of the tissues of its expression.

cDNA and genomic clones of Schistosoma mansoni containing the complete sequence of a homolog of protein disulfide isomerase have been identified. The protein disulfide isomerase gene in schistosomes is a single copy gene having a genomic structure that is very similar to that of man. The C-terminus of the deduced protein is KDEL which in mammals functions as a signal sequence for retention of luminal proteins in the endoplasmic reticulum. Immunohistology and in situ hybridization identify the gastrodermis of the gut, the wall cells of the protonephridia, and the sustentacular cells of the testes to be the major tissues of protein disulfide isomerase gene expression. The protein disulfide isomerase of schistosomes, produced in an expression vector in Escherichia coli, catalyzes disulfide/sulfhydryl isomerization in vitro.

Amino Acid Sequence↗