Amino-modified silicate gels prepared by sol-gel processing as metal-ion sorbents

Two series of amino-modified silicate gels prepared by sol-gel processing were used to absorb Cu(II), Ni(II), Co(II), Mn(II) and Cr(III) from aqueous solutions. These easily prepared sorbents with various content of primary amino groups in series (A) or primary and secondary amino groups in series (AA) have reasonable stability. The gel composition, time and concentration dependence of the uptake of the metal ions by these materials were studied systematically. These materials would be further used as supports to disperse catalytically active phases by conventional wet chemical procedures. Apart from this they demonstrate potential for the preconcentration aid for transition metal analysis.     

MHC zygosity in the frog,Rana temporaria

The major histocompatibility complex (MHC) zygosity of the field-collected frogs, Rana temporaria, was detected by progeny testing. Groups of sibling tadpoles were grafted with intrafamilial tail-tip allografts and the ratio of rapidly rejected allografts to slowly rejected ones was estimated. Twenty-five percent of parental frogs appeared to be MHC homozygotes. Thus, MHC homozygosity in natural frog populations seems to be considerably higher than in wild mouse populations.     

Chromatin proteins associated with micrococcal nuclease-sensitive and nuclease-resistant chromatin fractions of Kirkman-Robbins hepatoma and hamster liver

Micrococcal nuclease-sensitive (SP) and nuclease-resistant (PP) chromatin fractions from Kirkman-Robbins hepatoma and hamster liver were obtained. The molecular distribution of three non-histone proteins (NHCP1, NHCP2 and NHCP3), histones, and chromatin-bound protease activity between SP and PP fractions of both tissues was compared. Differences, mainly of quantitative nature, among non-histone proteins of neoplastic and normal tissue were observed. Moreover, it was found that polypeptides with mol. wt 81 000 (NHCP1), 39 000 (NHCP2) and 21 000, 35 000, 37 000 (NHCP1), 70 000, 112 000, 141 000, 157 000 (NHCP2), 30 000–33 000 (NHCP3) were associated only with the nuclease-sensitive part of chromatin of hepatoma and normal tissue, respectively. A major difference in histone compostion of hamster hepatoma and liver concerns histones H2A and H1. Furthermore, an enrichment of high mobility group proteins as well as other soluble non-histone proteins in an acid extract of the SP fraction was observed. Apparently chromatin-bound protease activity can be found in both fractions of chromatin.     

Familial translocation t(1p-;21q+) associated with Down's syndrome

Summary Familial occurrence of 1/21 translocation in connection with trisomy 21 was described. The possibilities of inheritance of further chromosome rearrangements arising during the gametogenesis of persons with this translocation were considered.     

Sterols and frost hardening of winter rape

Winter rape ( Brassica napus L., var. olifera cv. Górczanski) seedlings were exposed to hardening conditions and the content and composition of free sterols as well as the ratio of free sterols to total phospholipids were determined. There was a reduction in free sterol content in the leaves at the most advanced stage of hardening. The ratio of free sterol to total phospholipids was significantly reduced by hardening due to a decrease in the level of the former and an increase in that of the latter compounds. There was a negative correlation between this ratio and the temperature at which half of the seedlings died. Thus, adaptation of membranes to temperature takes place also at the level of sterol-phospholipid interactions. Exposing seedlings already hardened to freezing temperatures caused injury higher than 50%, and brought about a drastic increase in the level of free sterols and an elevation in the ratio of free sterols to phospholipids. The results are discussed in terms of a possible role of the molecular architecture of membranes in surviving at subzero temperatures.     

The effect of some glycolytic intermediates and long-chain acyl-CoA esters on rat skeletal muscle mitochondrial α-glycerophosphate dehydrogenase

Summary -Glycerophosphate dehydrogenase (sn-glycerol-3-phosphate: acceptor oxidoreductase, EC 1.1.99.5) activity in mitochondria isolated from rat skeletal muscle has been studied. The pH optimum of the enzyme activity was about 7.4 and the apparent K_m value for DL--glycerophosphate was approxinately 1.6mm. The activity of this enzyme was found to be inhibited by DL-glyceraldehyde-3-phosphate, phosphoenolpyruvate and 3-phosphoglycerate in a competitive manner: the apparent K_i values at pH 7.4 being 0.3mm, 1.5mm and 4.0mm respectively. The enzyme was found to be more sensitive to phosphoenolpyruvate at pH 7.0 than 7.6.The activity of -glycerophosphate dehydrogenase in rat skeletal muscle was also inhibited by palmitoyl-CoA and stearoyl-CoA in a competitive manner. The K_i values being about 9.0 m for both metabolites. This inhibition was partly reversed by Ca²⁺ and Mg²⁺ ions. Palmitoylcarnitine also exerted inhibitory effect on -glycerophosphate dehydrogenase activity but palmitate, carnitine and CoA added alone was without effect. It is proposed that the activity of -glycerophosphate dehydrogenase in rat skeletal muscle mitochondria may be controlled by changes of the cytosolic levels of some glycolytic intermediates and long-chain acyl-CoA esters. These results are discussed with respect to the regulation of -glycerophosphate shuttle activity in skeletal muscle.     

Binding of opiates and endogenous opioid peptides to neuroleptic receptor sites in the corpus striatum.

Some opiates with morphinan- and benzomorphan-structures possess affinities for neuroleptic receptors as revealed by their abilities to compete with ³H-spiroperidol for common binding sites in rat striatum $\text{in vitro}$ (IC₅₀ in the range between 10^?6 and 10^?5M). The binding of these opiates to neuroleptic receptors appears to be of pharmacological significance, since $\text{in vivo}$ studies in mice revealed a small but significant displacement of spiroperidol by high doses of the opiate antagonist levallorphan from specific binding sites in the striatum. In addition, there exists some correlation between the ability of opiates to bind to neuroleptic receptor sites $\text{in vitro}$ and their potency to evoke “bizarre behavior” in rats $\text{in vivo}$. In contrast, a wide variety of other opiates having morphine-, morphinone- or oripavine-structure showed no affinity for neuroleptic binding sites $\text{in vitro}$ (IC₅₀ greater than 10^?4 M). Of the opioid peptides (methionine-enkephalin, leucine-enkephalin and β-endorphin) none has an affinity for neuroleptic binding sites. A variety of other peptides were also investigated but did not interfere with spiroperidol binding. Only ACTH showed a moderate affinity for neuroleptic binding sites.