Isolation of a cDNA clone for chick intestinal apolipoprotein AI (Apo-AI) and its use for detecting apo-AI mRNA expression in several chick tissues

Three cDNA clones for chick apolipoprotein AI (Apo-AI), the major protein component of plasma high-density lipoproteins, have been isolated. The identity of the clones has been established first by screening a cDNA library in the pEX1 expression vector with anti-Apo-AI antibodies, second by Western blot analysis of the proteins expressed by positive clones. The use of the clone containing the largest, presumably full-size, cDNA insert (apo5C12) in molecular hybridization experiments confirms that apo-AI mRNA is expressed mainly in chick small intestine and liver. Furthermore, we provide evidence that brain, heart and skeletal muscle also synthesize significant amounts of apo-AI mRNA. The Southern-blot hybridization pattern of the restriction-enzyme-digested chick DNA with the apo5C12 DNA is consistent with there being a single copy of the apo-AI gene.     

Non-Michaelian kinetics of rabbit muscle uridine diphosphoglucose pyrophosphorylase

The kinetic properties of rabbit muscle uridine diphosphoglucose (UDP-Glc) pyrophosphorylase have been studied, in both directions, with respect to substrate saturation, product inhibition, and cation requirement for activity. The results demonstrate that UDP-Glc pyrophosphorylase is a non-Michaelian enzyme: the synthetic reaction is characterized by a marked inhibition by glucose-1-phosphate (at concentrations higher than 0.3 mM) and by an hyperbolic saturation for UTP. In the reverse reaction, instead, the saturation function for UDP-Glc is hyperbolic and that for inorganic pyrophosphate is sigmoid, with a high Hill coefficient of (nH) 2.5. The study of the metal requirement indicates a distinctive ability of cations to stimulate the reactions of synthesis and degradation of the sugar nucleotide and a different stoichiometry of the metal chelates involved. The reaction mechanism is of the ordered-sequential type and the data of product inhibition allowed the identification of glucose-1-phosphate as the first substrate bound and UDP-Glc as the last product released. The inhibition pattern by UDP-Glc gives evidence for cooperativity also in the binding of this molecule.     

Cloning structural gene sacB, which codes for exoenzyme levansucrase of Bacillus subtilis: expression of the gene in Escherichia coli.

A clone bearing the structural gene sacB, coding for the exoenzyme levansucrase, was isolated from a library of Bacillus subtilis DNA that was cloned in phage lambda charon 4A on the basis of the transforming activity of the chimeric DNA. This lambda clone also was found to contain the sacR and smo loci. Subcloning the sacB-sacR region in plasmid pBR325 resulted in a clone which directed levansucrase synthesis in Escherichia coli. The nucleotide sequence coding for the secreted protein was localized on the physical map of the cloned DNA.     

The Formation of Otoliths in the Frog Rana esculenta. Scanning Electron Microscopic and X-Ray Diffraction Studies

Two crystal forms of calcium carbonate were observed: calcite (utricle) and aragonite (saccule, lagena, endolymphatic sac). The first step in otolith formation is the appearance of organic structures in the macula. The subsequent step is characterized by fast growing primitive crystals with a prismatic habitus that successively transform into adult or mature crystals. With the metamorphosis, the aragonite crystals of the endolymphatic organ show clear signs of erosion that can be related to a process of CaCO₃ mobilization from such deposits.     

Effect of carbon dioxide on differentiation and on the level of a soluble b-type cytochrome in Phycomyces blakesleeanus

A soluble b-type cytochrome has been detected and partly characterized in mycelial extracts of Phycomyces blakesleeanus. As it is already known, CO₂ delays sporangiophorogenesis, but it also lowers the level of this cytochrome. A possible causal relationship between sporangiophorogenesis and the b-type-cytochrome level may exist. There is some correlation between the extent of the delay of sporangiophorogenesis and of the decrease in cytochrome-b level in wild type and mutants that are either resistant or sensitive to CO₂.     

Effects of 3,5-Dihalogenated-4-hydroxybenzonitriles on the Activity of Mitochondria From White Potato Tubers

Effects of the herbicide 3,5-diiodo-4-hydroxybenzonitrile (ioxynil), and its dibromo and dichloro analogs, upon the respiration of mitochondria isolated from white potato tubers (Solanum tuberosum L.) were investigated. Mitochondrial-mediated oxygen uptake was monitored polarographically with a platinum oxygen electrode.     

Toxigenic fungi associated with stored corn

A total of 246 fungal isolates were obtained from 25 moldy corn samples collected in central Iowa. Either water or ether extracts of all corn samples except one exhibited some degree of toxicity in mice and/or ducklings. At least one toxigenic isolate was obtained from each corn sample. Extracts of cultures of 99 of the fungal isolates, involving 13 genera, produced death in one or more of the assay animals. The majority of the toxigenic isolates belonged to the generaAspergillus andPenicillium. Three isolates ofTrichothecium roseum were highly toxic to ducklings and mice. The ducklings exhibited a flaccid paralysis shortly after receiving an oral dose of extracts of these three isolates. Death frequently occurred following a second oral dose given 24 hr later. Mice given intraperitoneal injections of extracts ofT. roseum first exhibited lethargy and intermittent tremors, then hyperemotivity, roughening of the hair coat, abdominal respirations, incoordination, dyspnea and clonic convulsions with death occurring usually within 10 to 20 min.

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Zusammenfassung Insgesamt sind 246 Pilzisolierungen von 25 verschimmelten Getreideproben, die in Zentral-Iowa gesammelt worden sind, erhalten worden. Sowohol Wasser- wie Aether-Extrakte von allen Getreideproben zeigten eine gewisse Toxizität in Mäusen als auch in Entchen außer einer einzigen Probe. Kulturextrakte von 99 der Pilzisolierungen, die 13 Gattungen umfaßten, verursachten den Tod in einem oder in mehreren Versuchstieren. Die Mehrheit der toxischen Isolierungen gehörte den GattungenAspergillus undPenicillium an. Drei Isolierungen vonTrichothecium roseum waren hoch toxisch für Entchen und Mäuse. Die Entchen zeigten eine schlaffe Paralyse kurz nachdem sie eine orale Dosis der Auszüge dieser drei Isolierungen erhalten hatten. Tod erfolgte häufig nach der zweiten oralen Dosis innerhalb 24 Stunden. Mäuse, die eine intraperitoneale Injektion der Auszüge vonT. roseum erhielten, zeigten erst eine Lethargie und einen intermittierenden Tremor, dann eine Hyperemotivität, aufgerauhte Haarbedeckung, abdominale Atmung, Inkoordination, Dyspnoe, klonische Zuckungen und Tod gewöhnlich innerhalb 10 bis 20 Minuten.

     

Biological effects of toxic products from Trichothecium roseum link

Extracts of rice cultures of 8 of 16 isolates ofTrichothecium roseum killed one or more ducklings or mice or both. One of the isolates (MC-156) obtained from shelled corn was the most toxigenic; extracts of this isolate killed all treated ducklings and mice.Doses of purified toxic fraction TR-1 of 166 mg/kg body weight given intraperitoneally killed all test mice but none of the mice given 100 mg/kg doses died. However, a partially purified fraction (Fraction VII), from which toxic fraction TR-1 was derived, killed two of three mice given 78 mg/kg doses.Crude ether extracts of rice cultures ofT. roseum (MC-156) produced death when injected intraperitoneally in rabbits and a 19-day-old pig and also produced dermal necrosis when applied to the skin of rabbits. The latter phenomenon was not observed when 5 mg of toxic fraction TR-1 was applied to the skin of rabbits.The greatest production of toxin occurred in rice cultures when incubated at 28° C and with 20 % (ml/g) water added to the rice. Incubation of rice cultures ofT. roseum (MC-156) under CO₂ tension suppressed toxin production.

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Zusammenfassung Auszüge von Reiskulturen von acht der 16 Stämme vonTrichothecium roseum haben mehrere Entchen und/oder Mäuse getötet. Einer der Auszüge (MC-156) von abgeschälten Mais war das toxischste; Auszüge dieses Isolates hat alle Entchen und Mäuse getötet. Dosen der gereinigten toxischen Fraktion TR-1, 166 mg/Kg Körpergewicht, intraperitonial verabreicht, haben alle Mäuse getötet, aber keine der Mäuse starb mit der Dose von 100 mg/Kg. Jedoch hat eine teilweise gereinigte Fraktion (Fraktion VII), von welcher die toxische Fraktion TR-1 gewonnen war, zwei von drei Mäusen mit 78 mg/Kg Dose getötet. Ungereinigte Ätherauszüge vonT. roseum (MC-156) waren tödlich, wenn sie in Kaninchen, in ein 19 Tage altes Schweinchen intraperitonel injiziert worden sind. Sie haben auch eine Hautnekrose hervorgerufen, wenn sie auf die Haut von Kaninchen gebracht worden sind. Das letztere Phänomen war nicht beobachtet, wenn 5 mg der toxischen Fraktion TR-1 an Kaninchenhaut gebracht worden ist. Die größte Produktion des Toxins fand in Reiskulturen statt, wenn sie bei 28° C und mit 20 Perzent (ml/g) Wasser bebrütet worden sind. Inkubation von Reiskulturen vonT. roseum (MC-156) unter CO₂-Druck hat die Toxinproduktion unterdrückt.