Induction of zygospores at high temperatures in the thermophilic,speciesMucor miehei with aspartic acid and phenylalanine

Summary The importance of amino acids in the induction of zygospores in mucors has been realized for the first time. It was found that in the thermophilic, speciesMucor miehei zygospores at high temperatures (40–50°C), can be induced by addition of phenylalanine and aspartic acid.     

On the synthesis of poliovirus RNA at supraoptimal temperatures

Riassunto La scarsa incorporazione di precursori dello ARN in cellule infette da poliovirus ed incubate a 41,5°C è dovuta ad una inibizione della sintesi dello ARN virale più che non ad una sua digestione ad opera di nucleasi.

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Work supported by a Grant of Consiglio Nazionale delle Ricerche, Rome.     

Effects of low temperatures on survival of frozen-thawed mouse embryos

Summary Almost no damage to mouse morulae was observed between 0 and –40°C, and freezing damage to embryos in DMSO, glycerol or ethylene glycol occurred after exposure to –60, –50 or –50°C, respectively. Cooling embryos in DMSO or glycerol to temperatures below –50 to –60°C increased freezing damage. To the contrary, in the presence of ethylene, glycol, no more damage occurred after exposure to temperatures below –50°C.     

Biomolecular stability and life at high temperatures

It is not clear what the upper temperature limit for life is, or what specific factors will set this limit, but it is generally assumed that the limit will be dictated by molecular instability. In this review, we examine the thermal stability of two key groups of biological molecules: the intracellular small molecules/metabolites and the major classes of macromolecules. Certain small molecules/metabolites are unstable in vitro at the growth temperatures of the hyperthermophiles in which they are found. This instability appears to be dealt with in vivo by a range of mechanisms including rapid turnover, metabolic channelling and local stabilisation. Evidence to date suggests that proteins have the potential to be stable at substantially higher temperatures than those known to support life, but evidence concerning degradative reactions above 100 degrees C is slight. DNA duplex stability is apparently achieved at high temperature by elevated salt concentrations, polyamines, cationic proteins, and supercoiling rather than manipulation of C-G ratios. RNA stability seems dependent upon covalent modification, although secondary structure is probably also critical. The diether-linked lipids, which make up the monolayer membrane of most organisms growing above 85 degrees C are chemically very stable and seem potentially capable of maintaining membrane integrity at much higher temperatures. However, the in vivo implications of the in vitro instability of biomolecules are difficult to assess, and in vivo data are rare.     

Crystal structure of barium titanium oxide at different temperatures

Résumé L'auteur a étudié aux rayons X la transition du titanate de barium autour de 120° C. Dans un intervalle de quelques degrés, il y a coexistence des deux formes cristallines (tétragonale et cubique). Il semble probable qu'il y a une nouvelle transition près de — 183° C. Il est intéressant de noter que ces points ne peuvent pas être attribués à une mise en rotation de molécules.     

Effects of DL-propranolol on the thermoregulatory responses of rats at different ambient temperatures

Summary Direct administration of propranolol (100–400 g) into the lateral cerebral ventricle of rats produced a dose-dependent hypothermia at ambient temperatures (T_a) of 8 and 22°C. The hypothermia was due to decreased metabolism and cutaneous vasodilation. The hypothermia induced by propranolol was antagonized by pretreatment with isoproterenol (50 g).This work was supported by the grants from the National Science Council (Republic of China) and the Pjing-Ling Neurological Foundation (Veterans General Hospital). The authors are grateful to Mr C.C. Wei for generous support.     

A crystalline molybdophosphoric complex of folic acid

Résumé Un nouveau produit crystallin de l'acide folique avec l'acide molybdophosphorique est décrit. Ce produit a été soumis aux examens microscopique, électrophorétique et analyse élémentaire. Ce produit provoque une leucopénie chez les rats albines, ce qui indique une ressemblance probable aux antidotes de l'acide folique. D'autre part, l'observation a montré que ce produit a un effet inhibitif sur la croissance desStreptococcus faecalis R. dans des cultures renfermant de l'acide folique à des degrés différents.     

The bugs that came in from the cold: molecular adaptations to low temperatures in insects

The widespread distribution of insects over many ecological niches is a testimony to their evolutionary success. The colonization of environments at high latitudes or altitudes required the evolution of biochemical strategies that reduced the impact of cold or freezing stress. This review focuses on our current interests in some of the genes and proteins involved in low temperature survival in insects. Although the most widespread form of protection is the synthesis of low molecular weight polyol cryoprotectants, proteins with intrinsic protective properties, such as the thermal hysteresis or antifreeze proteins are also important. These have been cloned and characterized in certain moths and beetles. Molecular techniques allowing the isolation of genes differentially regulated by low temperatures have revealed that heat shock proteins, cold stress proteins, membrane protectants, as well as ice nucleators and other less well characterized proteins likely also play a role in cold hardiness. Received 10 June 2008; received after revision 17 November 2008; accepted 18 November 2008     

Paradoxical effect of quinidine upon coronary flow of the isolated heart at different temperatures

Zusammenfassung Nach Langendorff wird am isolierten Kaninchenherzen gezeigt, dass die Temperatur der Durchströmungsflüssigkeit sowohl an spontan schlagenden wie auch an elektrisch gereizten Herzen bei Kammerflimmern die Koronarienwirkung des Chinidins grundsätzlich abzuändern vermag. Bei 26°C Temperatur wird der Koronardurchfluss durch Chinidin ständig erhöht, während bei 38°C Chinidin die Herzkranzgefässe verengert.     

Polarographic behaviour of polycytidylic acid and its double-stranded complex with polyinosinic acid

Zusammenfassung Es ergibt sich, dass die Polyzytidylsäure unter dem neutralen pH eine polarographische Reduktionswelle ähnlich der Welle der denaturierten Desoxyribonukleinsäure gewährt. Zur Bestimmung der Polyzytidylsäure mit der «ersten Kurve» genügt bereits 1/10g des Stoffes. Im Komplex der Polyzytidylsäure mit Polyinosinsäure ist die Reduzierbarkeit der Polyzytidylsäure eliminiert.     

Effect of tween 80 on protein-tannic acid complex

Riassunto L'acido tannico a basse concentrazioni forma complessi solubili con il citocromo C e la metamioglobina, modificandone i relativi spettri di assorbimento nel visibile. Il Tween 80 aggiunto alle soluzioni contenenti i suddetti complessi determina la rottura del legame proteina-acido tannico e la ricomparsa dello spettro caratteristico delle proteine in esame.

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This work was supported by a grant from the « Impresa Enzimologia » of the Italian Consiglio Nazionale delle Ricerche and by Grant No. FG-It-128 from the U.S. Department of Agriculture.     

In situ Feulgen reaction with Schiff reagent at different temperatures

Zusammenfassung Mit Feulgenfärbung wurden auf Rattenleber bei Temperaturen von 40 und 60 C die besten Färberesultate erzielt.