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1. Conscious lambs less than 2 days old were exposed to thermoneutral and to cold environments, and the radioactive microsphere technique was used to obtain measurements of blood flow to most tissues of the body. 2. Cold stress was such as to evoke a summit metabolic response. Deep body temperature was within the normal range for thermoneutral conditions, while metabolic rate increased by about 300%, cardiac output by about 30%, and blood pressure by about 25%. 3. Blood flow to the thermogenic tissues increased: perirenal, inguinal, pericardial, prescapular and cervical brown fat depots showed a five- to sixfold increase, while the longissimus dorsi, trapezius, gastrocnemius and biceps femoris muscles showed a five- to ninefold increase. 4. There was an increase in blood flow in the diaphragm, intercostal, panniculus and cardiac muscles, but a decrease in flow in the skin of the leg, ear and midside, the maxillo turbinals, thyroids, spleen, kidneys, liver and gut. There were no significant changes in total or regional blood flow in the brain or spinal cord, or in the adrenals, nasal mucosa or tongue. 5. Results support other evidence that thermogenesis in both brown fat and skeletal muscle is very important in the new-born lamb exposed to cold. Changes in flow in other tissues correlated with known functions in the cold animal. The redistribution of cardiac output during cold stress is a further example of circulatory adjustments which enable animals to cope with stress states. 6. Many differences between blood flow values obtained by the radio-active microsphere and other techniques for measuring blood flow are noted and discussed.

Exponentially growing cells of Escherichia coli, subjected to a simultaneous temperature and osmotic shock are capable of carrying out exchange between inorganic phosphate and ribonucleoside 5′-polyphosphate. The exchange reaction carried out by shocked cells is judged to be catalysed by polynucleotide phosphorylase (polyribonucleotide: orthophosphate nucleotidyltransferase, EC 2.7.7.8) for the following reasons: 1. 1. Exchange occurs with ribonucleoside 5′-diphosphate and leads to labeling of only the β-phosphate residue. 2. 2. Exchange labeling of ribonucleoside 5′-triphosphate requires hydrolysis of the β-γ phosphodiester bond and again results in labeling of only the β-phosphate position. With the exception of ATP no label can be detected in the γ-phosphate position of exchange-labeled ribonucleoside 5′-triphosphate. 3. 3. Known inhibitors of polynucleotide phosphorylase interfere with the exchange reaction in shocked cells. 4. 4. Shocked cells from strains carrying a mutation resulting in low levels of polynucleotide phosphorylase activity show an analogous decrease in exchange activity. Experiments on the existence of possible residual permeability restrictions to nucleotides in shocked cells indicate that restrictions still do exist for certain nucleotides.

The rate of formation of expired 14CO2 from histidine, 14C-labeled in the carboxyl group (C-His) or in the imidazole ring (R-His), and also from 14C-ring labeled urocanic acid (R-Uro) has been measured in rats subjected to restraint and cold stress. The rate of expiration of 14CO2 by restrained rats given C-His was significantly increased over control values; that from R-His was decreased. When restrained rats were also exposed to cold (4 °C), the rate of formation of 14CO2 from C-His decreased; that from R-His now showed an even greater decrease than when the measurements were made at room temperature. The rate of formation of labeled carbon dioxide from R-Uro was not altered significantly by these stressful procedures.Parallel measurements of the enzyme activities of histidine catabolism in rats restrained at room temperature for 2 h revealed no alteration in histidase activity of liver and lungs, but there was a marked increase in the histidine decarboxylase activity of stomach. Exposure of rats to cold over 1 h during the restraint of movement also resulted in enhanced histidine decarboxylase activity but of a lesser degree; 2 h of cold exposure during restraint abolished the difference between the control and stressed animals that had been observed at room temperature.The serum histidine concentration was measured 30 min after the intraperitoneal administration of 500 mg of histidine per kilogram body weight to rats. Both groups of stressed animals (restraint at room temperature, restraint in the cold) had much higher levels than observed in the corresponding controls. These results suggest that the increased histidine decarboxylase activity of stomach that develops under the stress of restraint is associated with a compensatory decrease in the rate of histidine uptake from the blood into the tissues. The data obtained for the rate of formation of expired 14CO2 have been interpreted in this light.

Publisher Summary This chapter discusses the role of cyclic nucleotides in promoting the trans-synaptic induction of tyrosine hydroxylase. An increase of activity at synapses impinging on either sympathetic ganglia or adrenal chromaffin cells results in an induction of tyrosine hydroxylase. This induction is termed trans-synaptic and occurs after time latency from the termination of the stimulus. Such latency implicates intermediate steps in transforming the increase of synaptic activity into a change of protein synthesis. The chapter also discusses the molecular nature of the events that transform stimulation of synaptic receptors located in the membrane of post junctional cells into an intracellular effector stimulus that increases the number of molecules of the inducible TH. The studies have identified three phases in the sequence of intracellular events which cause the induction of TH in adrenal medulla and superior cervical ganglia of demedullated rats after cold exposure. The cAMP/cGMP concentration ratio increases as a result of the extraordinary high rate of transmitter release. This increase persists for about 90 min and during the subsequent 10 to 18 hours a series of biochemical events occur, including de novo synthesis of specific messenger RNA.

Photodissociation of the CO molecule from carbon monoxide complexes of myoglobin and hemoglobin was examined between 4.2 and 80 °K. Experimental results have demonstrated that: 1. (I)|The photodissociated form was stable below 10 °K. 2. (II)|The ratio of the quantum yield of hemoglobin to myoglobin was roughly estimated to be 0.38. 3. (III)|The recombination of dissociated CO occurred by raising the temperature. 4. (IV)|The recombination reaction of photodissociated myoglobin and hemoglobin with CO was biphasic, whereas that of cobalt myoglobin with O2 was monophasic. 5. (V)|Activation energies for fast and slow reactions of myoglobin and hemoglobin, and for monophasic reaction of cobalt myoglobin are listed below: Fast Slow Mb(Fe 2+ ) + CO 124 cal/mole 124 cal/mole Hb(Fe 2+ ) + CO 124 cal/mole 230 cal/mole Mb(Co 2+ + O 2 570 cal/mole 6. (VI)|In the near infrared region the photodissociated forms of myoglobin and hemoglobin gave absorbance peaks at 770 nm, whereas deoxygenated forms of myoglobin and hemoglobin gave absorbance peaks at 758 and 750 nm, respectively, which suggests that the near infrared band is sensitive to the protein structure and may be called the “conformation band”. Several discussions have been held on the nature of the photodissociated form and the biphasic property of the reaction of myoglobin and hemoglobin, compared with those of cobalt myoglobin. It is now concluded that the new species, corresponding to the “rapidly reacting form” of hemoglobin by Gibson, Q. H. (1959) Biochem. J. 71, 293–303, and, more recently, of hemoglobin, single chain proteins and noncooperative aggregated forms by Alpert, B., Banerjee, R., and Lindqvist, L. (1974) Proc. Natl. Acad. Sci. U.S. 71, 558–562, is certainly trapped at 4.2 °K by photodissociating the carbon monoxide and oxygenated myoglobin and hemoglobin as well as the oxygenated cobalt myoglobin and hemoglobin.

Five cases of fat necrosis of the scrotum are presented. All occurred in stout or fat boys before puberty. The condition presents during the late winter or spring months of the year, and there is often a history of cold exposure during a swim a few days prior to the onset of scrotal pain. The lumps in the scrotum are usually bilateral and symmetrical. There is a remarkable lack of constitutional disturbance. Hypothermia is suggested as an important cause of fat necrosis of the scrotum in children. Pathologically the lesion resembles fat necrosis as seen elsewhere in the body.

Summary Seventy patients with intractable pain underwent hypothermic saline spinal subarachnoid injection. Thirty-three patients had pain due to benign conditions and thirty-seven to neoplastic diseases. In all patients, pain was relieved for several days after saline injection. In the thirty-three patients with benign conditions, pain was relieved for one to three months in 50 per cent and for seven months in less than 20 per cent. In twenty-eight of the thirty-seven patients with neoplasm who were dead at the time of this evaluation, 75 per cent of the twenty-eight patients had excellent to fair pain relief after hypothermic saline injection until the time of death. The mechanism of pain relief by hypothermic subarachnoid saline injection is not clear; nevertheless, the low morbidity warrants its consideration for pain relief in patients with neoplastic diseases.

Day-old domestic chicks previously exposed to a constant light approached a flashing rotating light more rapidly than chicks previously kept in darkness. The speed of approach was inversely related to the length of exposure, and effects were apparent after 18 min of exposure. Responsiveness was not affected by a prior reduction in air temperature of 4°C for 60 min. After exposure in the dark to the sound of a chick loudly calling for 60 min, chicks were less responsive to the flashing light than those previously kept in relative silence.

Ribosome crystals observed in hypothermically treated chick embryos exist as large dense aggregates and, for this reason, could be purified from a post-nuclear supernatant by centrifugation through a high-density discontinuous sucrose gradient. A ribosome crystal fraction isolated in this way was observed, by electron microscopy, to contain intact crystals, resembling those seen in sectioned whole cells, with only minor contamination from morphologically indistinct particles. The ribonucleic acid (RNA) content of this fraction was found to be the same as ribosomal RNA from mature chickens. However, their resistance to mild RNase treatment, lack of transfer RNA and endogenous messenger RNA activity indicate that such ribosome crystals are not a specific type of polysome. The intertetramer bonds (i.e. bonds between tetramers in a crystal array) are much more susceptible to mild protease treatment than to treatment with ribonuclease (RNase), indicating a dependence on protein-protein interactions for their formation.

(1) The aim of this investigation was to examine if and how proprioceptive information can be encoded in order to locate cues for ballistic reaching in the absence of corrective feedback of exteroceptive origin. Systematic errors in locating the position of the fingertip of the target hand by the reaching hand were observed, according to experimental conditions; but the subjects were unable to make a perceptual evaluation of them. (2) The first set of experiments was designed to determine how different localizing cues (proprioceptive, tactile or visual or combinations thereof) may contribute to the accuracy of ‘open loop’ manual reaching. Five different types of constant error were identified. This led to a search for 5 different kinds of sensory cues about finger target location, which may be encoded to program the reaching movement of the other hand. Such cues are respectively associated with active positioning, passive positioning, stabilized position, vision of the stabilized hand and tactile stimulation during movement of the target hand. The most striking observation was that some proprioceptive information, brought into play by movement and absent during stabilized position of the limb, may contribute to the spatial encoding of sensory cues. In this respect, some specific signal associated with self-induced movement seems to play a role in calibrating the exact location of the final position of the moved limb in external space. (3) The second set of investigations was undertaken in order to assess the nature and origin of the calibrating information produced by active movement. Convergent results were obtained, either by changing the speed of movement of the target hand or by cooling, or ever vibrating, the working muscles; and these results support the hypothesis that a velocity signal incorporated in the dynamic discharge of muscle spindle receptors may be involved in calibrating the final location of an actively-moved segment.

1. Attempts were made to induce emotional sweating in normal subjects by subjecting them to painful stimuli such as compression of pins on the forearm skin, immersion of the fingers in iced water, compression of the thoracic cage by rib calipers and ischaemic exercise of the forearm muscles.2. Changes in sweating were estimated by continuously monitoring the rate of total body weight loss.3. Of the painful stimuli used, only ischaemic forearm exercise significantly increased the rate of sweat secretion.4. Tasks in mental arithmetic caused much greater increases in sweat secretion than any of the pain stimuli except ischaemic pain.5. It is concluded that many varieties of pain, even when severe, do not induce sweating under laboratory conditions.

By serological investigation of various groups of patients, a correlation was found between rise in titre of antibodies to cytomegalovirus (CMV) and rise in cold agglutinin (CA) titre. This correlation was most marked, and significant, in a group of renal graft recipients where 16 of 27 had roughly parallel rises in CA and CMV antibody titre. It is suggested that in most patients showing this correlation the production of CA was related to infection with CMV, and it is possible that this immunological feature is more common in patients with CMV pneumonia.

A method for the determination of mercury in soils and related materials, by the cold-vapour, reduction-aeration absorption technique, is described. The mercury in the reduced sample solution is partitioned, by agitation, between the liquid phase and a fixed volume of air which is then blown through an absorption cell for measurement. Three preparative methods were developed, two of which use acid digestion and wet oxidation and the other direct oxidation in an oxygenflask combustion technique. Comparative analysis of natural samples by the three methods was used to validate the techniques developed, since no authenticated reference samples were available. For 1-g samples, the analytical range was 0.01–0.5 p.p.m.

Two hundred and thirty-five cryoprecipitates were sampled and assayed for Factor VIII activity. Two hundred and twenty-five of these were given to 11 patients with hemophilia on 53 occasions. The patients' Factor VIII levels were measured just before and 15 minutes after infusion. The rise in Factor VIII activity averaged 97 per cent of the expected rise calculated from the cryoprecipitate assays and plasma volume estimates. The mean Factor VIII content per bag of cryoprecipitate was 61 units. There is a highly significant probability that the smallest volume cryoprecipitates had significantly less Factor VIII than average and that the largest volume cryoprecipitates had significantly more Factor VIII than the average.

Cold sensitive (cs) mutants of E. coli unable to grow at 26° C were isolated. Three of about 200 mutants tested have RNA polymerase which is about 5 times less active at low temperatures than the wild type RNA polymerase. One of such mutants cs 1 was studied in more detail. The mutation affects core enzyme and is closely linked to rif-r mutations. By transduction analysis the following order of markers was established: argH — rif-r — cs 1.

Correlation between cyclic AMP and glycerol and free fatty acid release was studied in brown fat of normal rats and of rats exposed to cold for different periods, varying from 20 days to 6 months. Comparison with white epididymal fat was always made at the same time. Cyclic AMP synthesis and final triglyceride hydrolysis, are strictly related in brown fat of normal rats, both under basal conditions and under stimulation (in the presence of noradrenaline and/or theophylline). Such a correlation was maintained in brown fat of rats exposed to 4° for 6 months, but only under basal conditions. In contrast, when brown fat of cold-acclimated rats was incubated in the presence of noradrenaline and theophylline, cyclic AMP accumulation was still increased, but this increase was not associated with a stimulation of lipolysis. An analogous dissociation was found in epidymal fat incubated under anaerobic conditions. Results obtained in the presence of propranolol and phenoxybenzamine indicate that in brown, as well as in white fat, the interaction of catecholamines with the beta receptor is associated with the activation of adenylate cyclase. The alpha effect seems to be associated with the inhibition of adenylate cyclase and reduced cyclic AMP accumulation.

1. 1.|Adenylate kinase (EC 2.7.4.3) activity of the liver and hindleg muscle has been compared in normal and dystrophic mice. 2. 2.|The total activity and specific activity of the muscle enzyme was greatly reduced in the dystrophic animals but the properties of the enzyme as estimated by its sensitivity to pH, temperature and dithiol reagents were unaffected by the disease. The dystrophic enzyme was slightly less stable on storage probably due to changes in the dystrophic muscle. 3. 3.|The properties of the liver enzyme were very different from the muscle enzyme with respect to these criteria. 4. 4.|Electrophoresis on starch and polyacrylamide gels showed tissue specific isoenzyme patterns which remained unchanged in the dystrophic samples. 5. 5.|It is concluded that, unlike the human enzyme, mouse muscle enzyme remains qualitatively unchanged in the dystrophic animals. 6. 6.|The differences between mouse adenylate kinases and those of other species are discussed.

Broiler chicks were reared to 7 weeks of age at 7.2, 20.0 and 32.2°C. Heart ventricle weight, plasma volume, and blood volume were inversely related to environmental temperature. Allometric equations were determined for heart weight for chicks at 7.2 and 32.2°C. The results obtained demonstrate the need to specify environmental conditions when reporting allometric equations. Right ventricle weight as a percentage of total ventricle weight was not always significantly affected by environmental temperature, but there was a trend to greater right ventricular weight at lower temperatures.

Rabbit aortic strips stored 4 days at 6°C in Ringer solution had potentiated responses to 10 −9 −10 −8 M norepinephrine. After 24 hr, or 4 days at 6°C in a high calcium Ringer (4.8 mM) responses to all concentrations of norepinephrine were potentiated. Responses of fresh and cold stored aortae were depressed in calcium-free Ringer and by 10 −3 M LaCl 3 . Maximum tension in a 60 mM potassium, calcium-free Ringer was maintained longer by cold stored aortie than by fresh aortae. Rate of tension decline in this solution was the same for both groups of aortae. The ED 50 for calcium-induced responses was increased in the cold-stored aortic strips. Calcium required for norepinephrine responses was greater in the cold-stored aortae. In normal Ringer at 37°C fresh aortae did not respond to increases in calcium. After cold storage, 7 out of 12 aortae developed tension in response to calcium in normal Ringer. After 24 hr or 4 days at 6°C sodium and calcium contents of aortae were increased, potassium decreased. After 2 hr incubation at 37°C of cold-stored aortae, sodium contents were same as that of fresh aortae; calcium was still increased and potassium decreased. These data suggest potentiation after cold storage is due to a depolarization of the muscle membrane and not to an increase in effectiveness of calcium.

A new model is proposed on the origin of crystallizable ribosomes and the kinetics of ribosome crystallization. The model assumes that ribosome crystallizability is a property the ribosomes have only in a well-defined period of their life cycle and implies a close relationship between cellular differentiation and structural rearrangements at the ribosome level. The model is used to interpret a variety of cases in which ribosome crystallization occurs, such as chick embryo tissues during development, tissue cultures treated with different antibiotics, chick adult tissues infected by viruses, lizard oocytes, degenerating cells and dedifferentiated cellular systems.

At the mycological examination of eleven nest-boxes of the Tree-Sparrow (Passer montanus L.) after the winter season a significant increase of the total number of fungi was ascertained in comparison with the investigation of the same boxes in the previous summer; especially the cellulolytic fungi increased (generaPenicillium, Scopulariopsis, Chrysosporium et al.) but also the potentially zoopathogenic (ascertainedAspergillus fumigatus, Candida albicans, Mucor pusillus et al.) and toxinogenic fungi (e.g.Asp. flavus); a moderate-statistically insignificant-decrease in the number of isolates and species of keratinolytic fungi took place (in spring foundArthroderma ciferrii, A. quadrifidum andAphanoascus fulvescens). In some fungi not only survival but also colonization of the substrate in the winter and early-spring period were proved. As main factors conditioning the survival of fungi in the nest-boxes over the winter were ascertained the composition of the substrate, its temperature and humidity. The limiting abiotic factor is before all the low temperature, inhibiting the development of nonpsychorphilic fungi. On the base of various changes of the physical and chemical conditions of the environment an attempt of explaining the dynamics of some ascertained fungi in accordance with literary statements is presented. The proved overwintering of some potentially pathogenic fungi in the microhabitat supplies to the studies of this kind an epidemiologic and epizootologic importance.

Exposure of rabbits to cold or fasting results in marked increases in the number and size of liver lysosomes, associated with increases in the total and “free” proteolytic activity. Changes in lysosomal morphology also indicate increased activity and fragility. These effects of cold and fasting are correlated with decreases in the levels of liver fructose bisphosphatase (EC 3.1.3.11) activity and changes in the molecular properties of the purified enzyme, including the loss of a small peptide containing the only tryptophan residue in the peptide chain.

1. Cooling caused axonal depolarization in desheathed and urea-treated connectives, but induced hyperpolarizing responses (measured with micro-electrodes and with the sucrose-gap) in intact preparations. Hyperpolarizing responses were also recorded with extracellularly-located microelectrodes in intact connectives. 2. Strophanthidin (0.2 mM/l) caused axonal depolarization in desheathed preparations, ethacrynic acid being without appreciable effect. Ethacrynic acid (0.2 mM/1) induced apparent hyperpolarizations in intact connectives and abolished or reduced the effects of cooling. 3. It is concluded that the axonal sodium pump is pharmacologically separable from that associated with the perineurial and/or the glial membranes: the former being inhibited by cardiac glycosides, the latter by ethacrynic acid. 4. The results are discussed in relation to extra-axonal sodium regulation and the possible involvement of an electrogenic sodium pump associated with the perineurial or glial membranes.

Ehrlich ascites cells show a decreasing rate of incorporation of labeled amino acids into the cold acid insoluble material when they are incubated in HBSS. This decreasing rate of incorporation is partly due to a dilution of the labeled amino acid by unlabeled amino acids escaping from the cells. It is demonstrated that also the net rate of protein synthesis is reduced under these conditions and this reduction occurs on a step following aminoacylation of transfer-RNA. When the medium is changed after 3–5 hr of incubation, the cells regain their original high rate of amino acid incorporation and the medium harvested after incubation with ascites cells reduces the rate of protein synthesis in freshly harvested cells. It is hypothesized that ascites cells under the incubation conditions release a factor into the medium which reversibly inhibits protein synthesis. The possible role of this factor in regulating the transformation of growing ascites cells into non-growing cells is discussed.

The case of a patient with a 3 year long illness characterized by episodic localized lymphadenitis and concurrent acute autoimmune hemolytic anemia is reported. Histopathologically the lymphoid disease was granulomatous necrotizing vasculitis of the Wegener type. The acute hemolysis occurring with these episodes was associated with extreme erythrophagocytosis in the peripheral blood without hemoglobinuria. The unique autoantibody resembled the cold agglutinins of lymphoproliferative diseases in that it was an immunoglobulin M (IgM) with only kappa light chains and had anti-I specificity. However, the antibody had no agglutinating ability, demonstrated biphasic thermal requirements for in vitro hemolysis (cold, then warm, incubation) and was of approximately 7S size. Despite the requirement for incubation at less than 10 °C to produce in vitro hemolysis, clinical episodes of severe hemolytic anemia were unassociated with cold exposure. An excellent response to cortico-steroids contrasted with the typical experience with cold-reacting red cell autoantibodies.

Experiments were carried out to determine whether water content-induced airway resistance increase could be potentiated by facial cold or increased by subsequent exposure to increased inspired water c

We report experiments on two species (sheep and squirrel monkeys) in which the temperatures of the left and right preoptic areas were independently controlled. Autonomic thermoregulatory responses in one sheep and behavioral thermoregulatory responses in two monkeys changed similarly under comparable patterns of preoptic thermal stimulation. The response to unilateral heating or cooling was augmented by simultaneous or successive stimulation of the contralateral side to the same temperature level. Simultaneous heating of one side and cooling of the other could result in no change in thermoregulatory effector response, provided the two local preoptic temperatures were properly chosen. Similarly, a response initiated by unilateral heating (or cooling) could be abolished by subsequent contralateral cooling (or heating). An analysis of thermal conduction through the neural tissues indicated that the effect was not due to an overlap of thermal gradients from the thermodes at some intermediate thermosensitive site. The results imply that the magnitude of the effector response to preoptic thermal stimulation depends upon the volume of neural substrate stimulated as well as upon the local temperature imposed.

The effect of a standardized exercise procedure on plasma dopamine-β-hydroxylase (DBH) activity has been assessed in five normal human subjects. The activity of the enzyme was measured using a sensitive, nonradioactive assay based on the conversion of tyramine to octopamine. Each subject was tested at an ambient temperature of 40 °C and on a subsequent day at a temperature of 10 °C. The resting levels of DBH activity were significantly higher in the cold. A small increase in enzyme activity occurred with exercise at 40 °C, but there was no change in this parameter with exercise in the cold. It is suggested that the rise in plasma DBH activity seen in the cold and with exercise results from increased sympathetic activity. However, the failure of DBH activity to increase with exercise in the cold is poorly understood.

A unified approach to the serologic evaluation of autoimmune hemolytic anemia (AIHA) using a panel of tests is described. The “hemolytic panel” includes direct antiglobulin tests followed by study of eluates, classification and identification of autoantibodies at 37 and 4 C. with untreated and pretreated papainized cells, identification of associated isoantibodies, and screening tests for paroxysmal nocturnal hemoglobinuria (PNH) and paroxysmal cold hemoglobinuria (PCH). Three hundred fifty-four patients with unexplained anemia and/or positive direct Coombs tests were studied. Eighty-eight cases of autoimmune hemolytic anemia were found: 57 warm-antibody, 25 coldantibody, and two cases each of PCH, PNH, and T-activation. Eighteen of the warm-antibody hemolytic anemias were associated with alpha-methyldopa therapy. Serologic characterization of autoantibodies was used as a guide to transfusion in 24 cases. Clinicopathologic features of the cases are reviewed.

In leech ganglia, an individual sensory cell that responds specifically to noxious mechanical stimulation of the skin (N cell) excites two different motoneurones. One raises the annuli of the skin into ridges (the AE cell), while the other innervates logitudinal muscles and thereby shortens the body segment (L cell). A comparison has been made of the way in which these two synapses behave when their common presynaptic cell is stimulated in various conditions. 1. Using previously described criteria, N sensory cells have been shown to make monosynaptic chemical connexions with both the AE and L motoneurones (Nicholls & Purves, 1972). Following a single stimulus, the excitatory synaptic potential recorded in the AE motoneurone was only about one tenth the size of that in the L cell (approximately 0·5 mV compared to 5 mV). Trains of impulses in the same N sensory cell gave rise to synaptic potentials in the AE and the L motoneurones that underwent phases of facilitation and depression; the facilitation, however, was characteristically greater and longer lasting at synapses upon the AE motoneurone. 2. The differences between the two synapses were accentuated in Ringer fluid containing increased concentrations of Ca and also in the cold. Under both of these conditions repetitive firing by the N sensory cell could give rise to synaptic potentials in the AE motoneurone which progressively increased in amplitude, while those in the L motoneurone became smaller. 3. The results suggest that the differences in synaptic transmission can be accounted for by variations in the amount of transmitter released at the presynaptic N cell terminals, rather than by differences in the post-synaptic cells. The animal's behaviour corresponds to expectations from the physiology of the synapses.

The attachment of cells to culture dishes has been investigated by replica techniques and scanning electron microscopy. Cells were removed from their substratum either in a stream of medium or by micromanipulation. In the most usual case of interphase cells one finds many small points of attachment uniformly distributed over the whole cell underside. Attachment sites are also found under the lamellipodia and at the trailing edge of the cells. A large portion of the cell underside is sometimes left behind. This is probably because the sole plate is reinforced by cytoskeletal elements, and does not necessarily indicate the presence of large adhesion points. The distal ends of the retraction fibers formed as the cells round-up in trypsin, or in the cold, represent the attachment points of the cell to the substratum. Agents which tend to stabilize microtubules greatly slow cell detachment by proteolytic agents. The primary effect of trypsin is not on the glue which holds the cells to the substratum but rather on the cell shape itself, affecting the rigidity of cytoskeletal elements.

Descendants of two Colorado, U.S.A., populations of D. pseudoobscura, Boulder and La Foret, were exposed to +2° and -2°. In third instar larvae from Boulder AR and PP third chromosome gene arrangements survived better than TL and others, while the reverse situation occurred for La Foret. Deleterious dominant effects were observed for AR from La Foret. In adults from Boulder there was a trend towards greater survival for AR and PP than for other gene arrangements, while AR from La Foret showed relatively poor cold resistance. Survival of Boulder and La Foret flies, and their interpopulation hybrid, was determined after exposure to -2° at two humidities. Order of survival of developmental stages was: adults >> third instar larvae > mixture of first and second instar larvae. Adults survived better at low humidity, while larvae survived better at high humidity. Boulder adults and larvae survived better than those from La Foret. Advantage in survival of hybrids over the midparent ranged from 23% to 138%. Hybrid advantage over the higher parent ranged from 5% to 111%. Order of expression of heterosis was: mixture of first and second instar larvae > third instar larvae > adults. Relation of all results to the chromosomal polymorphisms at Boulder (seasonally constant) and La Foret (seasonally cyclic) is discussed.

Exposure of rats to cold increases the content of tyrosine hydroxylase [EC 1.14.16.2; L-tyrosine, tetrahydropteridine:oxygen oxidoreductase (3-hydroxylating)] in adrenal medulla, causing a long-lasting enhancement of the enzymatic activity. We have used an antibody specific to tyrosine hydroxylase to study the molecular mechanisms involved in the trans-synaptic induction of adrenal tyrosine hydroxylase. The rate of [ 3 H]-leucine incorporation into adrenal tyrosine hydroxylase was measured by specific immunoprecipitation at various times after exposure to cold (4 hr). This enhanced rate of incorporation was evident between 11 and 30 hr after the beginning of exposure to cold, but not at 7 and 50 hr. The increase of 3 H incorporation preceded the maximal enhancement of adrenal tyrosine hydroxylase activity, which occurred about 30 hr after stimulation. Neither the activity of tyrosine hydroxylase nor the rate of 3 H incorporation into tyrosine hydroxylase in cervical sympathetic ganglia was changed by 4 hr of exposure to cold. The rate of degradation of tyrosine hydroxylase was estimated at 26 and 50 hr after the beginning of cold stress, as determined by the technique of double-isotope labeling. The data indicate that the tyrosine hydroxylase degradation rate was not reduced by exposure to cold. Thus, the induction of adrenal tyrosine hydroxylase appears to be due to an increased rate of its synthesis.

The aggregation of histone GRK, induced by the addition of salt, is found to be highly dependent on temperature. The rate of this aggregation decreases with decreasing temperature and can be essentially stopped at low temperatures.

Three antiviral isatinisothiosemicarbazones strongly inhibited the incorporation of [ 3 H]uridine into the ribonucleic acid (RNA) of FL cells as a consequence of the inhibition of uridine transport. After prelabeling of cells at a low temperature (1 h at 16 C) with uptake of [ 3 H]uridine into the acid-soluble nucleotide pool, the later addition of the test compounds revealed only a small or negligible influence on host-directed RNA synthesis. The pulse-labeled soluble nucleotide pool of FL cells was sufficient to give a gradual increase in incorporation into RNA over a period of 7 h. With the same method of prelabeling at the beginning of the experiment, it was also possible to detect virus-induced RNA synthesis in the presence of actinomycin D. In this way the specific inhibitory action of the three isatinisothiosemicarbazones on viral RNA synthesis could be demonstrated.

1. 1. Skeletal muscle lactate dehydrogenase (LDH) isozymes of Fundulus heteroclitus sampled 1 day after capture exhibit a typical electrophoretic pattern of five LDH bands. 2. 2. LDH isozymes of fish kept at 20 and 30°C for 8 weeks show increased production of A 4 and A 3 B 1 bands (corresponding to LDH-5 and 4, respectively). 3. 3. LDH patterns of fish kept at 4°C resemble those of the zero time control (fresh caught) group. No increased production of any LDH band is observed at 4°C. 4. 4. The increased production of A 4 and A 3 B 1 isozymes at the higher temperatures suggests increased muscle glycolysis with reduction of (and concomitant oxidation of NADH) the resultant increased pyruvate concentrations which ,may be catalyzed more effectively by LDH-A 4 and LDH-A 3 B 1 than other isozymes. 5. 5. Additional environmental factors (e.g. possible salinity) affect LDH isozyme expression since the zero time control patterns differ from those of the 20°C control group.