New data on clonal anomalies of chromosome 14 in ataxia telangiectasia: tct (14;14) and inv(14)

Summary From a series of 53 patients with ataxia telangiectasia, two large clones with a t tan or tct(14;14) and two with an inv(14) were observed among phytohaemagglutinin (PHA)-stimulated lymphocytes. Smaller clones with the same inv(14) were observed in two other cases. Similar breakpoints may exist, both for t(14;14) and inv(14): q11.1/q11.2 and q32, and it is postulated that the rearrangements are related to a recombination of the -chain of the T-cell receptor and IgH clusters of genes.     

Metabolism of (3-(14)C)tryptophan and (2-(14)C)alanine in cattle tissues

In the experiments involving incubation of the liver, brain cortex, muscle and adipose tissues homogenates with [3-14C] tryptophan for an hour 43.2-89.3% of the label was found in proteins, 7.2-47.2%--in lipids, 2.6-9.4%--in CO2. Following incubation of the above-mentioned tissue homogenates with [2-14C] alanine, proteins, lipids and CO2 contain 28.8-49.3%; 22.6-31.9% and 21.6-49.3% of radioactive label, respectively. Radioactivity of lipids synthesized by the homogenates of the investigated tissues from [3-14C] tryptophan and [2-14C] alanine is 23.5-63.5 and 21.1-56.0%, respectively, the radioactivity of CO2 being 1.4-5.1 and 9.3-11.8% of the above-mentioned compounds synthesized from [1-14C] acetate. The results obtained testify to the considerable contribution of [3-14C] tryptophan and [2-14C] alanine to protein synthesis as well as to their involvement in the substrate supply of lipogenesis and energetic processes in various organs and tissues of cattle.     

Ring chromosome 14. II. A case report of r(14) mosaicism. The r(14) phenotype

Observation of a patient with r(14) mosaicism together along with 18 previously published observations define the syndrome as follows: mental deficiency, seizures, microcephaly (usually), and facial dysmorphism showing a narrow, elongated face, short palpebral fissures, a flat nasal bridge, and retrognathia. A retinal dystrophia which may be specific of the syndrome consists of a hyperpigmentation and, in three patients, yellow-white spots of the macula. The brain shows mild dilation of the lateral ventricles.     

Screening of white-rot fungi on (14C)lignin-labelled and (14C)whole-labelled wheat straw

Summary 74 Basidiomycetes have been tested for ligninolytic capability on (¹⁴C)lignin-labelled wheat straw. Fifteen strains were selected and rested more accurately for ligninolytic activity and the capacity to degrade wheat straw. The asymptote, inflexion point and degradation rate were determined using a model approach. The fungi exhibited very different responses with respect to lignin biodegradation: high asymptote for Pleurotus ostreatus (77%), low inflexion points for Sporotrichum pulverulentum Nov. (6.1 days) and Pycnoporus spp. (2.7 to 4.7 days) with high and slow degradation rates, respectively (0.91% and 0.45% of ¹⁴CO₂ release/day). Degradation values for (¹⁴C)whole-labelled wheat straw exhibited less variation. Finally, the strains Pleurotus ostreatus, Dichomitus squalens and Bjerkandera adusta showed the highest selectivity of lignin removal.     

Elongation of (omega-14C)oleic acid and (omega-14C)nervonic acid.

During feeding experiments with [omega-14C]oleic acid and [omega-14c]nervonic acid to adult rats, 14C-labelled C26, C28 and C30 fatty acids were recovered from the intestinal mucosa, liver, plasma, kidney and stools. The structures of these fatty acids were determined by g.l.c., radio-g.l.c. and mass spectrometry. The Schmidt and Ginger degradation methods indicated that most of the 14C found in these extra-long fatty acids remained in the omega position. These radioactive extra-long fatty acids were found mainly in the polar lipids of rats killed 3 or 15 h after being fed on labelled oleic acid or nervonic acid. Rats killed 63 h later yielded only traces of these extra-long fatty acids. When the rats were given antibiotics or received the same radioactive fatty acids by intravenous injection, the labelled extra-long fatty acids could not be detected in any of the tissues. We conclude that they were probably synthesized by elongation of oleic acid and nervonic acid by intestinal micro-organisms (probably yeasts) and then absorbed by the intestinal mucosa.     

Metabolism of L-(U-14C)valine, L-(U-14C)leucine, L-(U-14C)histidine and L-(U-14C) phenylalanine by the isolated perfused lactating guinea-pig mammary gland.

1. The incorporation of L-[U-14C]leucine, L[U-14C]histidine and L-[U-14C]phenylalanine into casein secreted during perfusion of isolated guinea-pig mammary glands was demonstrated. 2. The extent of incorporation of label into casein residues was consistent with their being derived from free amino acids of the perfusate plasma. 3. The mean transit time of the amino acids from perfusate into secreted casein was approx. 100 min. 4. Whereas radioactive histidine and phenylalanine were incorporated solely into milk protein, radioactivity from [U-14C]valine was also transferred to CO2 and to an unidentified plasma component, and from [U-14C]leucine to plasma glutamic acid. 5. Evidence from experiments with [U-14C]phenylalanine suggests that, as in rats, but in contrast with ruminant species, guinea-pig mammary tissue does not possess phenyl alanine hydroxylase activity. 6. The results are discussed in relation to the possible role of essential amino acid catabolism in the control of milk-protein synthesis.     

Aberrations of the synaptonemal complexes in a male 46,XY,-14,+der(14)t(Y;14)

An unbalanced translocation 46,XY,-14,+der(14)t(Y;14)(q11;p11) was observed in an azoospermic male, with reduced spermatogenesis and absent spermiogenesis. At the pachytene stage of spermatocyte 1, the segments of the 2 Y chromosomes, fluorescent with quinacrine mustard, were always found close together. This proximity was also demonstrated by the study of synaptonemal complexes, which showed, in addition, an unusual hypercondensation of the proximal segment of bivalent 14, adjacent to the translocated Y chromosome. This allows us to propose that this hypercondensation might correspond to an inactivation of the translocated autosome, which could be responsible of the degeneration of the germ cells.     

Inhibition of matrix metalloproteinase 14 (MMP-14)-mediated cancer cell migration

Matrix metalloproteinases (MMPs) have been shown to be key players in both extracellular matrix remodeling and cell migration during cancer metastasis. MMP-14, a membrane-anchored MMP, in particular, is closely associated with these processes. The hemopexin (PEX) domain of MMP-14 has been proposed as the modulating region involved in the molecular cross-talk that initiates cell migration through homodimerization of MMP-14 as well as heterodimerization with the cell surface adhesion molecule CD44. In this study, minimal regions required for function within the PEX domain were investigated through a series of substitution mutations. Blades I and IV were found to be involved in cell migration. We found that blade IV is necessary for MMP-14 homodimerization and that blade I is required for CD44 MMP-14 heterodimerization. Cross-talk between MMP-14 and CD44 results in phosphorylation of EGF receptor and downstream activation of the MAPK and PI3K signaling pathways involved in cell migration. Based on these mutagenesis analyses, peptides mimicking the essential outermost strand motifs within the PEX domain of MMP-14 were designed. These synthetic peptides inhibit MMP-14-enhanced cell migration in a dose-dependent manner but have no effect on the function of other MMPs. Furthermore, these peptides interfere with cancer metastasis without affecting primary tumor growth. Thus, targeting the MMP-14 hemopexin domain represents a novel approach to inhibit MMP-14-mediated cancer dissemination.     

Variable self-absorption of (C14)glycogen

With this paper we hope to warn other investigators of the difficulty in counting [C¹⁴]glycogen in liquid scintillators. The pulse height shift encountered makes it impossible to determine the counting efficiency in the C¹⁴-channel by use of external or internal standards. The efficiency is variable from one isolate of glycogen to another and the use of standards to determine efficiencies can give errors up to 50% of the value found with hydrolyzed glycogen. Hydrolysis of glycogen obviates this problem.     

P14相关信号通路

p14^ARF是新近发现的一种具有细胞周期调节功能的抑癌基因,P14^ARF主要定位于核仁,但也有少部分位于核质。p14^ARF在部分人类肿瘤中频发失活,其表达异常导致肿瘤的发生机制及以P14^ARF为靶点进行的肿瘤治疗越来越受到重视。现对于Pl4^ARF相关信号通路的研究进展进行了综述。