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Biomedical subjects

M Berchtold

Publications and source records attributed to M Berchtold.

At least 19 recordsLinked to original sources
PubMed2002

Aerobic and facultatively anaerobic cellulolytic bacteria from the gut of the termite Zootermopsis angusticollis.

AIMS: To demonstrate the occurrence of cellulolytic bacteria in the termite Zootermopsis angusticollis. METHODS AND RESULTS: Applying aerobic cultivation conditions we isolated 119 cellulolytic strains from the gut of Z. angusticollis, which were assigned to 23 groups of aerobic, facultatively anaerobic or microaerophilic cellulolytic bacteria. 16S rDNA restriction fragment pattern and partial 16S rDNA sequence analysis, as well as numerical taxonomy, were used for the assignment of the isolates. The Gram-positive bacteria of the actinomycetes branch could be assigned to the order Actinomycetales including the genera Cellulomonas/Oerskovia, Microbacterium and Kocuria. The Gram-positive bacteria from the order Bacillales belonged to the genera Bacillus, Brevibacillus and Paenibacillus. Isolates related to the genera Afipia, Agrobacterium/Rhizobium, Brucella/Ochrobactrum, Pseudomonas and Sphingomonas/Zymomonas from the alpha-proteobacteria and Spirosoma-like from the "Flexibacteriaceae" represented the Gram-negative bacteria. CONCLUSIONS: A cell titre of up to 10(7) cellulolytic bacteria per ml, determined for some isolates, indicated that they may play a role in cellulose digestion in the termite gut in addition to the cellulolytic flagellates and termite's own cellulases. SIGNIFICANCE AND IMPACT OF THE STUDY: The impact of bacteria on cellulose degradation in the termite gut has always been a matter of debate. In the present survey we investigated the aerobic and facultatively anaerobic cellulolytic bacteria in the termite gut.

Aerobiosis↗
PubMed2001

Structure of apoptosis-linked protein ALG-2: insights into Ca2+-induced changes in penta-EF-hand proteins.

BACKGROUND: The Ca2+ binding apoptosis-linked gene-2 (ALG-2) protein acts as a proapoptotic factor in a variety of cell lines and is required either downstream or independently of caspases for apoptosis to occur. ALG-2 belongs to the penta-EF-hand (PEF) protein family and has two high-affinity and one low-affinity Ca2+ binding sites. Like other PEF proteins, its N terminus contains a Gly/Pro-rich segment. Ca2+ binding is required for the interaction with the target protein, ALG-2 interacting protein 1 (AIP1). RESULTS: We present the 2.3 A resolution crystal structure of Ca2+-Ioaded des1-20ALG-2 (aa 21-191), which was obtained by limited proteolysis of recombinant ALG-2 with elastase. The molecule contains eight alpha helices that fold into five EF-hands, and, similar to other members of this protein family, the molecule forms dimers. Ca2+ ions bind to EF1, EF3, and, surprisingly, to EF5. In the related proteins calpain and grancalcin, the EF5 does not bind Ca2+ and is thought to primarily facilitate dimerization. Most importantly, the conformation of des1-20ALG-2 is significantly different from that of calpain and grancalcin. This difference can be described as a rigid body rotation of EF1-2 relative to EF4-5 and the dimer interface, with a hinge within the EF3 loop. An electron density, which is interpreted as a hydrophobic Gly/Pro-rich decapeptide that is possibly derived from the cleaved N terminus, was found in a hydrophobic cleft between these two halves of the molecule. CONCLUSIONS: A different relative orientation of the N- and C-terminal halves of des1-20ALG-2 in the presence of Ca2+ and the peptide as compared to other Ca2+loaded PEF proteins changes substantially the shape of the molecule, exposing a hydrophobic patch on the surface for peptide binding and a large cleft near the dimer interface. We postulate that the binding of a Gly/ Pro-rich peptide in the presence of Ca2+ induces a conformational rearrangement in ALG-2, and that this mechanism is common to other PEF proteins.

Animals↗
PubMed1999

Differential enumeration and in situ localization of microorganisms in the hindgut of the lower termite mastotermes darwiniensis by hybridization with rRNA-targeted probes

We examined the abundance and spatial distribution of major phylogenetic groups of the domain Bacteria in hindguts of the Australian lower termite Mastotermes darwiniensis by using in situ hybridization with group-specific, fluorescently labeled, rRNA-targeted oligonucleotide probes. Between 32.0 +/- 7.2% and 52.3 +/- 8.2% of the DAPI-stained cells in different hindgut fractions were detected with probe EUB338, specific for members of the domain Bacteria. About 85% of the prokaryotic cells were associated with the flagellates of the thin-walled anterior region (P3a) and the thick wall of the posterior region (P3b/P4) of the hindgut, as shown by DAPI staining. At most, half of the EUB338-detected cells hybridized with one of the other probes that targeted a smaller assemblage within the bacterial domain. In most fractions, cells were found in varying numbers with probe ALF1b, which targeted members of the alpha-Proteobacteria, whereas substantial amounts of sulfate-reducing bacteria, gram-positive bacteria with a high DNA G+C content and members of the Cytophaga-Flavobacterium cluster of the Cytophaga-Flavobacterium-Bacteroides (CFB) phylum could be detected only in the wall fraction of P3b/P4. This clearly indicates that the hindgut microhabitats differ in the composition of their microbial community. In situ hybridization of cryosections through the hindgut showed only low numbers of bacteria attached to the P3a wall. In contrast, the wall of P3b was densely colonized by rod- and coccus-shaped bacteria, which could be assigned to the Cytophaga-Flavobacterium cluster of the CFB phylum and to the group of gram-positive bacteria with a high DNA G+C content, respectively. Oxygen concentration profiles determined with microelectrodes revealed steep oxygen gradients both in P3a and P3b. Oxygen was consumed within 100 &mgr;m below the gut surface, and anoxic conditions prevailed in the central portions of both gut regions, indicating that oxygen consumption in the hindgut does not depend on the presence of a biofilm on the hindgut wall.

Journal Article↗
PubMed1998

Psychrotolerant sulfate-reducing bacteria from an oxic freshwater sediment, description of Desulfovibrio cuneatus sp. nov. and Desulfovibrio litoralis sp. nov.

The most abundant culturable sulfate-reducing bacteria were isolated from the littoral sediment of the oligotrophic Lake Stechlin. The strains STL1 and STL4 were obtained from the oxic uppermost layer, while strain STL6 was isolated from the anoxic zone in 20 to 30 mm depth. The isolates showed a striking morphological feature in tapering off at one end of the cell. Physiological characteristics related them to the genus Desulfovibrio. They contained desulfoviridin. H2, formate, pyruvate, lactate, and fumarate were utilized with sulfate, sulfite, thiosulfate, or elemental sulfur as electron acceptors. All isolates were able to reduce oxygen and survived 120 h of aeration. However, aerobic growth was not observed. The isolates were psychrotolerant, and grew with rates of up to 0.29 d-1 at 4 degrees C. Analysis of the 16S rDNA confirmed that the strains belong to the genus Desulfovibrio. However, they were not closely related to any known member of this genus and formed a new cluster with at least two new species. Strain STL1 and STL4, exhibiting 99.7% sequence similarity in 16S rRNA, are proposed as the new species Desulfovibrio cuneatus sp. nov., while strain STL6 is assigned to the new species Desulfovibrio litoralis sp. nov.

Base Sequence↗
PubMed1996

Detection of calmodulin-binding proteins using a 32P-labeled GST-calmodulin fusion protein and a novel renaturation protocol.

To identify calmodulin-binding proteins in cellular extracts and tissue homogenates and to analyze purified calmodulin target proteins, overlay procedures using 125I-calmodulin or, more recently, nonradioactive biotinylated calmodulin have been widely used. Here we describe a rapid, alternative method for detecting calmodulin-binding proteins with a 32P-labeled calmodulin probe generated as a glutathione-S-transferase (GST)-fusion protein. We used a modified pGEX-2TK vector, which contains the flag epitope and the consensus sequence R-R-A-S, that can be phosphorylated by the cAMP-dependent protein kinase A. The fusion protein is easily purified from bacterial bysates by affinity chromatography using glutathione-Sepharose 4B beads. Phosphorylation of GST-calmodulin is performed directly on the beads and, after elution with reduced glutathione, the labeled calmodulin probe can be used for overlay experiments. We also describe a rapid renaturation protocol that enhances the signal for some but not all calmodulin-binding proteins and is used after the proteins have been transferred to nitrocellulose filters. Furthermore, we have compared the specificity and sensitivity of the 32P-labeled GST-calmodulin overlay with those of 125I-calmodulin and biotinylated calmodulin, clearly indicating that our newly developed protocol is a suitable alternative to conventionally used calmodulin overlay procedures.

Animals↗
PubMed1995

Parvalbumin expression during developmental differentiation of the rat ovary.

Parvalbumin (PV) is a high-affinity Ca(2+)-binding protein which is expressed in a limited number of vertebrates tissues and restricted to a few distinct cell types. It has been shown by biochemical methods to be present in the adult rat ovary, but cellular localizations or developmental appearance have not been described until now. This study describes the presence of PV and its transcripts, analyzed by immunohistochemistry and in situ hybridization, respectively, during the postnatal development of the rat ovary: 13 developmental stages between day 1 and day 83 were examined. In ovaries 1-16 days old, neither PV mRNA nor PV was observed in any caaaaaaaaaaaaaay. By contrast, starting from day 18 postpartum, both PV mRNA and PV were detected in low amounts, simultaneously with the onset of differentiation of secondary intestitial gland cells in the ovarian interfollicular stroma. PV and its transcripts were primarily detected in conspicuous patches of interstitial gland tissue and in the differentiated thecal cells around the large follicles, and PV appeared to be fully expressed 33 days after birth. The parallel time courses of PV mRNA and PV accumulation during developmental differentiation, and the appearance of a steroid-producing cellular phenotype as well as the strict cellular colocalization of these two features, strongly suggest involvement of PV in the steroid metabolism of these cells, as earlier proposed for the Leydig cells of the testis. According to this hypothesis, we also show that suppression of gonadotrophic hormone production by hypophysectomy of adult rats totally suppresses PV production in parallel with the disappearance of the morphological features typical of steroid-producing cells in the remaining interstitial tissue of the ovary.

Animals↗
PubMed1995

Development and prevention of skeletal muscle structural alterations after experimental myocardial infarction.

The present study was designed to assess whether structural alterations develop within skeletal muscle 1 yr after myocardial infarction (MI) and failure and, if so, whether these structural alterations can be prevented by angiotensin-converting enzyme (ACE) inhibition. Infarcted rats were randomized and treated for 1 yr with either placebo (MI-IP, n = 9), a low dose of lisinopril (MI-LL, 0.5 mg.kg-1.day-1, n = 12), or a high dose of lisinopril (MI-LH, 5 mg.kg-1.day-1, n = 9). Sham-operated animals served as controls (SH, n = 14). One year after MI, in situ fixation of rat hindlimb was performed to investigate interstitial collagen volume fraction (CVF), capillary density, and media thickness of resistance vessels (80-200 microns) of musculus quadriceps femoris muscle. Infarct size was similar in all infarct groups and averaged 26 +/- 4%. Right ventricular weight was increased in MI-IP compared with SH, MI-LL, and MI-LH. Both left ventricular (LV) CVF and skeletal muscle CVF were increased in MI-IP. LV CVF and skeletal muscle CVF were closely related to each other (n = 44, r = 0.5377, P < 0.002). In infarcted rats, high-dose ACE inhibition significantly reduced skeletal muscle and LV CVF. Skeletal muscle capillary density and capillary-to-muscle fiber ratio were significantly decreased in infarcted rats but were restored by low- and high-dose ACE inhibition. Media thickness of intramuscular resistance vessels was increased in the MI-IP group and significantly reduced by high-dose ACE inhibition.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

16S rDNA sequence and phylogenetic position of an uncultivated spirochete from the hindgut of the termite Mastotermes darwiniensis Froggatt.

We have analyzed the 16S rDNA sequence and the phylogenetic position of an uncultivated spirochete from the hindgut contents of the Australian termite Mastotermes darwiniensis Froggatt. The 16S rRNA genes of bacteria from the hindgut contents of Mastotermes darwiniensis were amplified by polymerase chain reaction. The amplification products were cloned and sequenced. The sequences were compared to known homologous primary structures. Two of the clones (MDS1 and MDS3) had an insert of 1498 nucleotides showing typical signatures of spirochete 16S rRNA sequences. The sequences of the two clones were most similar to the 16S rRNA sequence of Spirochaeta stenostrepta (89.8%) and Treponema sp. strain H1 (90.7%). Phylogenetical analysis positioned the hindgut spirochete sequence with that of the free-living anaerobic Spirochaeta stenostrepta and Treponema sp. strain H1 as its nearest relatives within the cluster of the spirochetes. We conclude that analyzed SSU rDNA sequences originate from a spirochete related to the genus Treponema. It is possibly one of the uncultivated unique spirochetes symbiotic in termite hindguts.

Animals↗
PubMed1994

The phylogenetic position of Dimastigella trypaniformis within the parasitic kinetoplastids.

The nuclear 16S-like rRNA coding regions of two strains of the kinetoplastid flagellate Dimastigella trypaniformis Sandon (strain Ulm and strain Glasgow) were sequenced and phylogenetically analyzed. Strain Ulm was isolated from the hindgut contents of the Australian termite Mastotermes darwiniensis Frogatt, whereas strain Glasgow originates from a soil sample in Scotland. After preparation of genomic DNA the 16S-like rRNA coding regions were amplified using polymerase chain reaction (PCR) technology. The amplification products were cloned in a plasmid vector and sequenced according to standard methods. The sequence of the 16S-like rRNA coding region of strain Ulm differs less than 2% from the sequence of strain Glasgow, indicating that the two strains are most probably members of one species. Phylogenetic analysis of the sequence data positioned D. trypaniformis Sandon as a deep branching lineage near the root of the kinetoplastid group of flagellates.

Animals↗
PubMed1990

[Effects of partial drying of an udder quarter in cows with teat injuries].

In cows with teat lesions, partial drying-off of the affected mammary quarter is recommended for a period of 3 to 10 days. The other three quarters are normally milked. Partial drying-off reduces the risks of complications due to the daily milking. The slight reduction of milk production, connected with the temporary drying-off a single quarter, is nearly compensated within 4 weeks.

Animals↗