Microspectrophotometric analysis of respiratory pigments using a novel fibre optic dip probe in microsamples.

A microspectrophotometer system to monitor the reduction of mitochondrial respiratory pigments in cell extracts and permeabilized cells has been developed. The novel optical fibre set-up uses visible spectrophotometry to measure the reduction of mitochondrial electron carriers. The basis of the system is an Ocean Optics S1000 spectrometer, a broadband tungsten based light source, input and output coupling fibre optics and a fibre optic dip-probe which requires less than 20 microl of sample for analysis.

A matrix-located processing peptidase of plant mitochondria.

Nuclear-encoded mitochondrial precursor proteins are proteolytically processed inside the mitochondrion after import. The general mitochondrial processing activity in plant mitochondria has been shown to be integrated into the cytochrome bc1 complex of the respiratory chain. Here we investigate the occurrence of an additional, matrix-located processing activity by incubation of the precursors of the soybean mitochondrial proteins, alternative oxidase, the FAd subunit of the ATP synthetase and the tobacco F1 beta subunit of the ATP synthase, with the membrane and soluble components of mitochondria isolated from soybean cotyledons and spinach leaves.

The occurrence of hsp70 in the outer membrane of plant mitochondria.

Hsp70 was localized to the mitochondrial outer membranes of bean and cauliflower mitochondria. Western blotting showed that the outer membrane hsp70 was antigenically distinct from the mitochondrial-matrix hsp70, but was similar to the cytosolic form. The protein was resistant to solubilization with 200 mM sodium carbonate which showed the hsp70 was tightly bound to the outer membrane.

Identification of a 42-kDa plant mitochondrial outer membrane protein, MOM42, involved in the import of precursor proteins into plant mitochondria.

A 42-kDa plant outer mitochondrial membrane protein, MOM42, has been identified as an essential component of the plant mitochondrial precursor protein translocation apparatus. Immunological cross-reactivity has been detected between antibodies raised against both Neurospora and yeast mitochondrial outer membrane proteins and plant mitochondrial outer membrane proteins. Immunocompetition studies showed that import of precursors to Rieske FeS protein, ATPase su9-DHFR, and the adenine nucleotide transporter was inhibited in the presence of antibody to MOM42.

DNA profiling of Bursaphelenchus species.

A 1190-bp DNA fragment, designated X14, was isolated from a Bursaphelenchus xylophilus (isolate J10) genomic library. Used as a probe for DNA profiling, this fragment identifies the pinewood nematode (Bursaphelenchus spp.) at both the species and isolate level.