A novel approach to the analysis of the initiation of embryo development in gramineae

An in vivo model system to study the initiation of embryo development is presented. From the so-called Salmon system of wheat (alloplasmic lines with a 1BL-1RS chromosome translocation), three completely isogenic and homozygous lines were produced by selection for uniformity in about 20 selfing/backcross generations as well as between sublines of doubled haploids. The line (aestivum)-Salmon is male fertile and sexual. The lines (caudata)-Salmon and (kotschyi)-Salmon are male sterile and have a parthenogenetic capacity of about 90%. The expression of nuclear-cytoplasmic male sterility is different for the two parthenogenetic lines. The initiation of autonomous embryo development at defined developmental stages of the ovaries and the maximum degree of parthenogenesis are identical in both parthenogenetic lines as proved by the auxin test and progeny analyses. The protein patterns from ovary extracts of the three isogenic lines were identical for more than 200 spots of 2-D polyacrylamide gels, confirming their homogeneity. However, one protein (P 115.1) was found 3 days before and during anthesis only in ovaries of the parthenogenetic lines. It seems to be involved in the initiation of parthenogenesis.     

Nitric oxide mediates interleukin-1 induced inhibition of glycosaminoglycan synthesis in rat articular cartilage

Interleek-1beta (IL-1) is a key mediator of cartilage matrix degradation in osteoarthritis and rheumatoid arthritis. It was found that the IL-1-induced suppression of glycosaminoglycan (GAG) synthesis in rat articular cartilage occurred simultaneously with the accumulation of nitrite (a metabolite of nitric oxide (NO) in aqueous milieu) in the culture medium. NO-synthase inhibitors, L-NMMA and L-NIO, inhibited both these IL-1 effects. Dexamethasone suppressed GAG synthesis additively to IL-1, but did not alter nitrite accumulation. Three NO-donors (GEA 3175, SNAP and SIN-1) also had an inhibitory effect on cartilage GAG synthesis. Therefore, it is concluded that IL-1 induced suppression of GAG synthesis in rat articular cartilage is mediated by the production of NO.     

Human leukemic K562 cells: differential effects of 5-azacytidine on DNA methylation of epsilon-, gamma-globin and 7SL RNA genes

5 Azacytidine ribonucleoside (5 Aza CR), greatly enhances erythroid differentiation of the K562(h) cell line, with a sharp increase of embryonic and fetal globin gene expression. This phenomenon is correlated with the undermethylation of gamma-globin but not of epsilon-globin, as the epsilon-globin gene is already extensively undermethylated before 5AzaCR induction. By contrast no variations in both DNA methylation and expression are observed in 7SL RNA genes.     

Influence of prostaglandins on electrolyte metabolism of human trabecular bone in vitro

A procedure was developed to investigate the electrolyte metabolism of human trabecular bone and its regulation in vitro, in particular the influence of prostaglandins. Trabecular bone was prepared from femoral heads of patients who had undergone hip replacement surgery for coxarthrosis. 500 mg samples were incubated in modified EAGLE's minimal essential medium. Net electrolyte movements between bone and incubation medium were measured. During 6 hours of incubation PGE2 caused an increase in the release of calcium and magnesium from bone into incubation medium as compared to controls. The effect of PGE2 was dose-dependent and comparable to that of human parathyroid hormone 1-34 (hPTH 1-34) whereas hPTH 3-34 had no effect. Human calcitonin (hCT) caused a decrease in the release of calcium and magnesium. PGE2 was found to be the most potent prostaglandin. PGE1 and PGF2 alpha had about 50% and PGF1 alpha about 40% of the potency of PGE2. PGA1 and PGA2 had no effect. The effect of PGE2 could be completely inhibited by hCT and was not further enhanced by hPTH 1-34. Magnesium movement was affected in the same way as calcium movement, while phosphate movement and release of alkaline phosphatase and hydroxyproline from bone into incubation medium were not affected by prostaglandins.     

Electron microscopic demonstration of calcitonin in human medullary carcinoma of thyroid by the immuno gold staining method

In a human medullary carcinoma of thyroid gland containing calcitonin in light microscopic demonstration by the avidin biotin complex (ABC) method characteristic secretory granules were found electron microscopically in the cytoplasm of the tumour cells. They consisted in so-called type I granules (270 +/- 25 nm) and type II granules (135 +/- 17 nm). By the immuno gold staining (IGS) method the content of many secretory granules measuring 85-270 nm (152 +/- 18 nm) in diameter could be identified as calcitonin. These granules seemed to be predominantly of type II because of their nearly corresponding size and feature. The type I granules were less frequent in number and they showed no or little immunoreactivity. The results indicate that the IGS-method is practicable to demonstrate the ultrastructural localization of calcitonin and to identify clearly the nature of intracytoplasmic granules in electron microscopy.     

Exhaustive physical exercise and acid hydrolase activity in mouse skeletal muscle

Summary Adult, untrained NMRI mice were exhausted on a motor-driven treadmill by an intermittent-type running programme. Serial cryostate sections for the staining of NADH-tetrazolium reductase, -glucuronidase, -N-acetylglucosaminidase, and -glycerophosphatase activities and for making hematoxylin-eosin staining were cut from m. quadriceps femoris 1, 2, 3, 5, 7, and 15 days after physical exhaustion. A strong increase in the activities of -glucuronidase and -N-acetylglucosaminidase, was observed 7 days after exhaustion and the activity changes, which were similar for the both glycosidases, were more prominent in the highly oxidative red compared to less oxidative white fibres. Activity granules were more numerous in the perinuclear than the interfibrillar area of red fibres. Spots were arranged like longitudinal chains between myofibrils. Activity in connective tissue was usually observed only in animals exhausted 3–7 days earlier. Simultaneous activity in fibres exceeded that in connective tissue -Glycerophosphatase activity was not, by the method used, seen in histologically healthy or normal-looking fibres. in samples taken 2–5 days after exhaustion some degenerating and necrotic fibres were observed. Inflammatory reaction was also observed being at its strongest five days after loading when mononuclear cells were seen inside necrotic fibres. The number of regenerating muscle cells was most abundant 7 days after exhaustion. It is suggested that temporary hypoxia, which accompanies exhaustive physical exercise in skeletal muscle, upsets the energy metabolism and homeostasis of fibres and causes the observed histological and histochemical alterations, which posses features typical of both lethal and sublethal acute cell injury.     

N-banding in polytene chromosomes of Chironomus and Drosophila

The N-banding patterns of the polytene chromosomes of Drosophila melanogaster, Chironomus melanotus, Ch. th. thummi and Ch. th. thummi x Ch. th. piger were studied. In Chironomus the polytene N-banding patterns correspond to the polytene puffing patterns. This is revealed by comparison of the puffing and N-banding patterns of identical chromosomes. Size and staining intensity of the N-bands reflect the size of the puffs as shown by puff induction. There is no evidence that the N-bands are also located in Chironomus heterochromatin or are restricted to the nucleolar organizer regions. In Drosophila the -heterochromatin is strongly N-positive, whereas the -heterochromatin, as well as the Chironomus heterochromatin is not N-banded. Contrary to Chironomus, the puffs in Drosophila polytene chromosomes do not give rise selectively to well stained N-bands. — The N-banding method is interpreted to stain specifically non-histone protein which is (1) accumulated in genetically active chromosome regions and (2) present in a specific type of heterochromatin (-heterochromatin of Drosophila).     

Studies on the (pro) insulin biosynthesis of islets of Langerhans of sand rats (Psammomys obesus).

By feeding a regular laboratory chow, sand rats (Psammomys obesus) from our breeding colony gained different body weights, though they received approximately the same quantity of calories. Sand rats, reaching a body weight above 160 g (group B) showed significantly increased blood glucose values in contrast to the animals with a body weight under 160 g (group A). Isolated pancreatic islets of these two groups of sand rats were incubated with [3H]-leucine to study the incorporation of this amino acid into proinsulin and insulin. The incorporation into proteins of pancreatic islets of sand rats of group B was stimulated by 0.45 mg and 3.0 mg/ml glucose. In group A there was no further stimulation from 0.45 mg to 3.0 mg/ml glucose. Insulin secretion could be stimulated by glucose in both groups, but the stimulation was stronger in group B than in group A.     

A peroxisomal glycolate oxidase in the algaMougeotia

Microbodies of the algaMougeotia were isolated in a linear sucrose gradient. The organelles, which moved to the density 1.24 g cm^–3, contained about 70% of the glycolate oxidase (EC 1.1.3.1) found in this alga. The enzyme oxidized glycolate, utilizing either oxygen or 2,6-dichlorophenolindophenol (DCPIP) as the electron acceptor. L-Lactate was an alternate substrate; almost no D-lactate was utilized. In the presence of O₂, a K_m of 415 M was determined for glycolate, whereas the K_m for L-lactate was about 5,000 M. In the presence of DCPIP, lower concentrations of glycolate and L-lactate were sufficient to obtain the highest rates of enzyme activity.Abbreviations DCPIP 2,6-dichlorophenolindophenol Supported by the Deutsche Forschungsgemeinschaft     

An automatic method for determination of urinary 3-methylhistidine: normal values.

A system for automatic analysis of urinary 3-methylhistidine is described, applying ion-exchange chromatography and using an automatic sample injector, a motoric selector valve, and a diode programmer, which controls the analytical system. The method permits a sampling rate of 22 samples/day. 3-Methylhistidine was completely separated from histidine in 37 min whereas 1-methylhistidine was eluted together with ammonia. The 3-methylhistidine concentration was linear up to 150 nmol/ml and no appreciable sample interaction was found at automatic sequential runs. The error, in a single determination based on duplicate samples, was 4.61% and, in duplicated determinations, 3.26%. The mean urinary 3-methylhistidine output was 299.4 ± 23.8 μmol/day in 12 healthy females and 545.5 ± 35.2 μmol/day in 12 healthy males. The 3-methylhistidine excretion was significantly higher in males than in females, when expressed as the absolute daily output or as the estimated ratio to body weight, body surface area, or creatinine.