A rapid method for the large scale purification of the intermediate filament protein vimentin by single-stranded DNA-cellulose affinity chromatography

A new method is described for the purification of the intermediate filament protein vimentin from Ehrlich ascites tumor cells using single-stranded DNA-cellulose affinity chromatography. The procedure is rapid and allows the large scale isolation of the protein. Partial characterization of vimentin shows that it has a molecular weight of 58000 and an apparent pI of 5.3. It can be degraded by the vimentin-specific, Ca²⁺-activated proteinase which results in the production of a characteristic set of degradation products. The vimentin also cross-reacts with the intermediate filament protein monoclonal antibody, α-IFA.     

Cytogenetics of the chinese giant salamander,Andrias davidianus (Blanchard): the evolutionary significance of cryptobranchoid karyotypes

Cytogenetic aspects of the cryptobranchid salamander Andrias davidianus of western China have been studied, including chromosome number and morphology, C-band patterns, meiosis, and the chromosomal localization of ribosomal 5S RNA genes. Our data regarding chromosome number (2n=60) and general chromosome morphology largely confirm the results of Morescalchi et al. (1977). The karyotype consists of 16 pairs of macrochromosomes that decrease gradually in relative length to 14 pairs of microchromosomes. Telocentric chromosomes are a conspicuous feature of the karyotype, representing more than half the genome. Differential staining reveals that all of the chromosomes, except four pairs of microchromosomes, have C-band heterochromatin in their centromeric regions, the amount varying irrespective of chromosome size. Faint bands of interstitial and telomeric C-band heterochromatin are found in mitotic chromosomes but are not seen in meiotic preparations. In C-banded mitotic preparations from a female, one of the smallest macrochromosome pairs is heteromorphic in respect to C-band heterochromatin and centromere position. In situ hybridization of an iodinated 5S RNA probe to meiotic chromosome preparations reveals that this repeated gene is clustered near the telomeric region of chromosome 7, a medium size telocentric, a location corresponding to a band of heterochromatin. Studies of spermatocytes indicate that the process of meiosis in A. davidianus closely resembles that of more advanced salamanders, and that the microchromosomes are meiotically stable. The significance of microchromosomes and chromosome morphology in the reorganization of salamander genomes during evolution is discussed on the basis of cytogenetic data available for A. davidianus and various other primitive and advanced salamanders.     

Monocyte-produced prostaglandin induces Fcγ receptor expression on human T cells

Incubation of human T cells for 18 hr with prostaglandin E₂ (PGE₂ 3 × 10^?6M) causes a slight but significant increase in the percentage of Tγ cells and a reduction in Tμ cells. When PGE was added to “non-Tγ” cells, the increase in the percentage of Tγ cells was more marked (from 1.5% Tγ without PGE to 11% Tγ with PGE₂, P < 0.001). Supernates from cultures of human monocytes also caused an increase in Tγ cells (10% Tγ without supernate to 18% with supernate, P < 0.01), and this increase was blocked if the monocytes were cultured with indomethacin, a prostaglandin synthetase inhibitor (9% Tγ cells). Thus, monocytes may regulate Fcγ receptors on T cells via PGE₂ production.     

Mutants of Pachysolen tannophilus that produce enhanced amounts of acetic acid from D-xylose and other sugars

Summary Two mutants of Pachysolen tannophilus were isolated which produced considerably more acetic acid from several sugars than a wild type strain. Such mutants are of potential interest for the production of acetic acid rather than ethanol from lignocellulosic hydrolysates.Issued as NRCC No. 20810.     

Activation by calcium of membrane channels for potassium in exocrine gland cells

In the rat parotid salivary gland, fluid secretion is regulated by alterations in fluxes of monovalent ions. , stimulation of muscarinic, α-adrenergic or substance P receptors provokes a biphasic increase in membrane permeability to K⁺ which can be conveniently assayed as efflux of ⁸⁶Rb. The increased ⁸⁶Rb flux is thought to arise in response to a receptor mediated elevation in [Ca²⁺]_i which activates Ca²⁺-activated K⁺-channels. The biphasic nature of the response is presumably due to a biphasic mode of Ca²⁺ mobilization by secretagogues; a transient response reflects release of a finite pool of Ca from an intracellular store while a more sustained phase results from Ca entry through receptor operated Ca channels or gates. Calcium also mediates an increased Na⁺ entry which in turn activates the Na⁺, K⁺-pump. The mechanism involved in the regulation of monovalent ion channels by Ca²⁺ is not understood.     

Effects of manganese and other divalent cations on calcium uptake and catecholamine secretion by primary cultures of bovine adrenal medulla cells

Primary cultures of bovine adrenal medullary chromaffin cells were used to examine the effect of replacing divalent cations in the extracellular media on secretion. When calcium was replaced by manganese, nicotine-stimulated secretion was delayed in onset for 3 to 5 minutes, but continued for approximately 60 minutes. In contrast, calcium-supported secretion began immediately on stimulation and plateaued by 10 minutes. ⁵⁴Mn²⁺ uptake occurred on stimulation but at a lower rate than ⁴⁵Ca²⁺ uptake. There was no delay of ⁵⁴Mn²⁺ uptake upon stimulation and ⁵⁴Mn²⁺ uptake was considerably prolonged compared to ⁴⁵Ca²⁺ uptake. Replacement of calcium with strontium gave results similar to those with calcium, and, in addition, strontium was able to bring about secretion by itself in a manner similar to barium. Inhibition experiments showed that the potency for inhibiting calcium uptake was Cd²⁺>Mn²⁺>Ca²⁺>Sr²⁺.