Targeting Homologous Recombination in Notch-Driven C. elegans Stem Cell and Human Tumors

Mammalian NOTCH1-4 receptors are all associated with human malignancy, although exact roles remain enigmatic. Here we employ glp-1(ar202), a temperature-sensitive gain-of-function C. elegans NOTCH mutant, to delineate NOTCH-driven tumor responses to radiotherapy. At ≤20°C, glp-1(ar202) is wild-type, whereas at 25°C it forms a germline stem cell⁄progenitor cell tumor reminiscent of human cancer. We identify a NOTCH tumor phenotype in which all tumor cells traffic rapidly to G2⁄M post-irradiation, attempt to repair DNA strand breaks exclusively via homology-driven repair, and when this fails die by mitotic death. Homology-driven repair inactivation is dramatically radiosensitizing. We show that these concepts translate directly to human cancer models.     

Unsaturated oligogalacturonic acids are generated by in vitro treatment of pectin with human faecal flora.

Pectins with a degree of esterification (DE) of 95, 66, 34 and 0%, respectively, were incubated in vitro with human faecal flora (pH 7.8). The concentration and composition of oligogalacturonic acids (oligoGalA) generated were determined using high-performance thin-layer chromatography (HPTLC) with UV and colorimetric detection. In the first period of the anaerobic degradation, the pectin macromolecules were fragmented into unsaturated oligoGalA as intermediate products by the action of bacterial pectate lyases. Depending on the incubation time and the DE of pectin, the amount of unsaturated oligoGalA having different degrees of polymerization changed continuously. These oligoGalA were present in the cultures for some hours. Mixtures of unsaturated di-, tri- and tetraGalA were the end products of a pectate lyase action. Later, the oligoGalA disappear as a result of their further fermentation by the gastrointestinal microflora under formation of short-chain fatty acids (SCFA). Low-esterified pectins were depolymerized and fermented faster than the highly esterified by the human faecal flora in vitro. Furthermore, a mixture of unsaturated oligoGalA prepared from pectic acid by the action of pectate lyase from Erwinia carotovora was completely fermented by human faecal flora.     

Structural analysis of 5S rRNA, 5S rRNA-protein complexes and ribosomes employing RNase H and d(GTTCGG)

The hybridization of d(GTTCGG) to eubacterial 5S rRNAs, 5S rRNA-protein complexes, 70S ribosomes and 50S and 30S ribosomal subunits was investigated. This oligonucleotide, which may be considered to be an analogue of the T psi CG loop of tRNAs, was chosen in order to investigate a possible interaction between tRNAs with ribosomal components during protein synthesis. The hybridization was analysed by RNase H hydrolysis studies and, in the case of the ribosomes and ribosomal subunits, in addition with the radioactively labelled oligodeoxyribonucleotide in binding studies. The results obtained lead to the conclusion that nucleotides in loop c, i.e. positions 42-47, are available for oligonucleotide interaction in free Escherichia coli and Bacillus stearothermophilus 5S rRNAs and not available in the corresponding 5S rRNA-protein complexes. The 70S ribosomes and ribosomal subunits did not interact with the oligonucleotide. Under the assumption that d(GTTCGG) is an analogue of the T psi CG loop of tRNAs and in view of the results obtained, we conclude that in the unprogrammed ribosomes the T psi CG loop of tRNAs does not interact via standard Watson-Crick base pairs with the ribosomal 5S, 16S or 23S RNAs.     

Uranium mobilization from low-grade ore by cyanobacteria

Summary Three cyanobacterial isolates (two LPP-B forms and one Anabaena or Nostoc species) from different environments could mobilize uranium from low-grade ores. After 80 days, up to 18% uranium had been extracted from coal and 51% from carbonate rock by the filamentous cyanobacterium OL3, a LPP-B form. Low growth requirements with regard to light and temperature optima make this strain a possible candidate for leaching neutral and alkaline low-grade uranium ores.     

Lack of anion effect on volume expansion natriuresis in the developing canine kidney

The renal response to volume expansion with sodium chloride or sodium bicarbonate was studied in 15 newborn and 13 adult dogs. Proximal and distal nephron function were estimated using the technique of distal nephron blockade. Fractional sodium reabsorption was 99.0 +/- 0.3% in newborn and 96.6 +/- 0.06% in adult during the NaCl expansion (P less than 0.01) and 98.1 +/- 0.7% in the newborn and 93.2 +/- 0.7% in the adult during NaHCO3 expansion (P less than 0.001). With either anion the higher fractional sodium reabsorption in the newborn was due to reabsorption of a greater fraction of the load presented to the distal nephron segment. The percent of the distal sodium load that was reabsorbed was 98.0 +/- 0.6% in the newborn and 92.2 +/- 1.0% in the adult during NaCl expansion, and 96.1 +/- 1.3% in the newborn and 81.5 +/- 2.4% in the adult during NaHCO3 expansion. Differences in distal nephron chloride, potassium and bicarbonate reabsorption among the groups support the hypothesis that the enhanced distal sodium reabsorption in the newborn occurred largely in the ascending loop of Henle with NaCl expansion, while it occurred in the late distal and cortical collecting tubules with NaHCO3 expansion. There was no difference between the natriuretic responses to NaCl or NaHCO3 in the newborn (P greater than 0.20); however, the natriuretic response to NaCl was less than that to NaHCO3 in the adult (P less than 0.001). This suggests that the bulk of the sodium that escaped reabsorption in Henle's loop during NaHCO3 expansion was reabsorbed in the late distal tubule in the newborn, but not in the adult.     

Elucidation of the antigenic determinant in lipotropin for two monoclonal antibodies

Two monoclonal antibodies were found to give enhanced affinity for β-lipotropin when mixed, as evidenced by competitive radioimmunoassay. Both monoclonals were found to react with a pentapeptide Ala-Glu-Leu-Glu-Tyr, which is a sequence of high local hydrophilicity within the N-terminal section of β-lipotropin.     

Funktionelle Morphologie des Geruchsorgans und Histologie der Kopfanhänge der NasenmuräneRhinomuraena ambonensis (Teleostei,Anguilliformes)

Zusammenfassung 1. An drei, wahrscheinlich adulten Exemplaren der Nasenmuräne,Rhinomuraena ambonensis Barbour, wurden die funktionelle Morphologie des Geruchsorgans sowie dessen Histologie und die der bartelartigen Kopfanhänge untersucht.2. Die Ränder der vorderen Riechöffnungen sind zu trichterförmigen Hautlappen ausgewachsen. Die in ihrer Ausrichtung und Form durch Körperbewegungen kaum beeinflußbaren Trichter leiten auch im Ruhezustand des Tieres Wasser in die Riechhöhle, da ihre weite Öffnung im Strömungsbereich des Atemwassers liegt. Auf diese Weise erfolgt eine effektive Ventilation der Riechhöhle.3. Im mehrschichtigen Epithel der Trichter liegen Sekretzellen und vereinzelt Sinnesknospen; unmittelbar über den Epithelbildungszellen verlaufen Nervenfasern. Im Bindegewebe, das beidseitig von Epithel bedeckt ist, liegen Gefäße, Nervenbündel (Nervus trigeminus) und Pigmentzellen. Muskelgewebe fehlt. Neben dem Bindegewebe gibt es kein anderes Stützgewebe.4. Die beiden Riechhöhlen sind von extremer Ausdehnung. Die Zahl der lamellenartigen Riechfalten, die in zwei Doppelreihen nach dem 90°-Typ liegen, beträgt ca. 200. Zwischen den Innenrändern der Falten einer Doppelreihe, dorsal von der Mittelraphe, erstreckt sich eine zylindrische Rinne, die der Duftwasserpassage dient.5. Die Riechfalten sind bis auf die lateralen, dorsalen Teile und Teile der ventralen Faltenansätze kontinuierlich mit Riechepithel bedeckt. Der histologische Aufbau des Riechepithels entspricht dem des Aals. Die Rezeptorendichte schwankt zwischen 2–3×10⁴ pro mm². Im Verhältnis zur Riechhöhlenausdehnung ist die Riechfeldgröße erheblich.6. Tuscheexperimente zeigten, daß — ausgelöst durch die in die Längsrinne der Riechhöhle ragenden fingerförmigen Innenränder der Riechfalten — Mikroturbulenzen entstehen, die neben der Flimmerbewegung durch Kinocilien für die Mikroventilation des Faltensystems sorgen.7. Das auf der Symphyse des Oberkiefers zwischen den Trichterbasen sitzende Rostrum ist eine Hautprojektion, deren bindegewebiger Zentralteil ein mehrschichtiges Epithel trägt. Im Bindegewebe sind Gefäße, feine Nerven und Pigmentzellen eingebettet. Im Epithel finden sich geschmacksknospenähnliche Sinnesorgane. Prinzipiell haben die drei Mandibularbarteln den gleichen histologischen Aufbau wie das Rostrum. Auch ihr Epithel weist Sinnesknospen auf, die wie jene des Rostrums und der Trichter vielleicht als chemische Sinnesorgane beim Nahrungstest fungieren.8. Nach dem Ergebnis vorliegender Untersuchungen wirdRhinomuraena ambonensis in die Gruppe der makrosmatischen Knochenfische eingereiht.

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Functional morphology of the olfactory organ and histology of the head appendages of the moray eelRhinomuraena ambonensis (Teleostei, Anguilliformes)

In three individuals of the moray eelRhinomuraena ambonensis (Barbour), the functional morphology and histology of the olfactory organ as well as the histology of the different head appendages were investigated. The edges of the anterior nares are extremely extended, forming a funnel-like wide opening through which the odour water passes. Even when the fish does not move, an effective ventilation of the olfactory chambers is maintained by a permanent water current towards the funnel opening induced by the peristaltic movements of the musculature of the gill chamber (principle ofBernoulli). The histological structure of the head appendages (funnels, rostrum and mandibulary barbels, which are all skin projections) is described. The epithelia of all these appendages bear sensory organs which are similar to taste buds. The two olfactory organs are of extremely large size. Each chamber contains about 100 olfactory lamellae which are arranged in two lines (90°-type;Holl 1965). A cylindrical cavity extends between the inner edges of the olfactory lamellae through which the water runs to the posterior nare. Interlamellar microventilation is produced by numerous turbulences which are caused by the edges of the olfactory lamellae and by the kinocilia of the olfactory epithelium. The histological structure of the olfactory epithelium is similar to that ofAnguilla anguilla. The different results demonstrate thatRhinomuraena ambonensis is probably a macrosmatic fish.

     

Survival of micro-organisms in space

Dried suspensions ofPenicillium roqueforti Thom, Coliphage T-1,Bacillus subtilis and tobacco mosaic virus were exposed to space on board the Gemini-IX-A and XII earth satellites and the Agena-VIII space rocket. All micro-organisms tested survived the direct exposure during the Gemini-IX-A experiment. In the Gemini-XII experiment only the T-1 phage survived the direct exposure. The survival was influenced by the suspending medium and depended on the species of the microorganism. After four months of space flight on the Agena-VIII space rocket surviving fractions between 2×10^–3 and 1.0 were found in the unopened flight container. However, micro-organisms exposed on the cover of the container during this period were completely inactivated. Shielding against solar ultraviolet radiation during flight resulted in survival of micro-organisms exceeding to that of the transport controls, and the survival was considered complete.Sterile methylcellulose collection surfaces were exposed to space on board the Gemini-IX-A and XII satellites in an attempt to collect viable micro-organisms in space. None of the collection surfaces yielded viable micro-organisms.