Ultrastructure of Volvox carteri

Summary Somatic cells of mature asexual colonies of Volvox carteri do not possess a true cell wall, but are otherwise similar in ultrastructure to Chlamydomonas. Somatic cells are embedded in multilayered fibrillar material of the colonial matrix. The reproductive cells (gonidia) of Volvox carteri lie internal to the somatic cell layer of the colony matrix in an apparently structureless portion of the colony matrix. Mature gonidia are large vacuolate cells with a central nucleus and parietal chloroplasts and mitochondria. They are non-flagellated at maturity, but each contains a pair of kinetosomes.     

New simplified procedures for the extraction and simultaneous high-performance liquid chromatographic analysis of retinol, tocopherols and carotenoids in human serum

A short, simple extraction procedure and a sensitive reversed-phase high-performance liquid chromatographic assay, which utilizes isocratic elution and detection either by a photodiode-array detector or by two detectors set at 300 and 450 nm, have been developed to measure retinol, tocopherols and several carotenoids in human serum simultaneously. By relying on characteristic UV—visible spectra, seventeen carotenoids, retinol and α- and γ-tocopherols were identified in concentrated serum extracts by use of the three-dimensional data mode of a photodiode-array detector. The presence of some recently reported carotenoids in human serum has been confirmed.     

Arginine utilization by Mycoplasma fermentans is not regulated by glucose metabolism: A 13C-NMR study

Abstract Electrofusion of protoplasts of two mutant strains of Hansenula polymorpha resulted in high fusion and hybrid yields when the calcium ions present in the conventional fusion medium replaced by zinc ions. The optimal fusion conditions were an alignment field of 0.4 kV cm⁻¹ strength and 2 MHz frequency for 30 s, followed by two consecutive pulses of 12 kV cm⁻¹ strength and 15 μs duration. With 0.05–0.1 mM zinc ions in the fusion medium an average clone number of 10⁴–10⁵ clones per 10⁸ input cells was reached. The presence of about 0.6 mM magnesium ions in the zinc fusion medium was essential.