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One purpose of teacher education is to help future teachers develop the necessary knowledge, abilities, and skill for good teaching. A second purpose is to develop the commitment to use this knowledge, ability, and skill when trainees graduate from the training program and begin their teaching careers. There is evidence to suggest that teacher education programs can successfully achieve the first purpose, but success in the development of commitment to good teaching has not yet been demonstrated. By applying Becker's conception of commitment, a two-step plan for developing commitment in teacher education is proposed. The first step is to identify and assess commitment, the second step is to record behavioral indicators of commitment and to use these records to help future teachers develop commitment. In physical education, the improvement of teaching is vital to the future of the field; thus it is critical that teacher education programs help their students develop commitment to good teaching as well as d...

A microscope-based flow cytometer, which is based on a new flow system, has been extended to include light scatter detection, dual parameter fluorescence analysis, and a device which compensates for variations in excitation light intensity. A dichroic mirror splits the fluorescence into two spectral components that are further purified by additional filters situated in front of the photomultiplier tube detectors (PMT). Light scatter detection is obtained by a dark field configuration. An objective focuses the scattered light emitted within the dark field onto an adjustable slit in front of a PMT. Resolution of light scatter histograms of 1.5-micrometer latex spheres is about CV = 2.5%. Dual parameter analysis revealed a linear correlation between the light scatter signal and fluorescence of cells stained with fluorescein isothiocyanate, indicating that the light scatter signal is closely proportional to cell dry mass. The instrumental light scatter, which is proportional to the excitation light intensity, gives rise to a DC signal. This signal regulates the fluorescence signal amplifiers so that these signals are compensated for fluctuations in the excitation light intensity.

Fluorescence spectra of Hoechst 33258 bound to rat thymocytes were measured by flow cytometry. At low dye concentrations (less than or equal to 2 micrograms/ml) the fluorescence maximum was situated at 460 nm irrespective of solvent composition. With higher dye concentrations the fluorescence maximum was shifted upwards, the intensity decreased and the width of the fluorescence peak increased. Linear combinations of a spectrum obtained at a low dye concentration (0.5 microgram/ml, type 1 binding) and one obtained at a high dye concentration (42.4 micrograms/ml, type 2 binding) failed to reproduce spectra measured at intermediate dye concentrations (0.15 M NaCl). Hence, Hoechst 33258 forms at least three different fluorescing complexes with DNA in chromatin. The shift in the fluorescence maximum of the Hoechst 33258/chromatin complex towards higher wavelengths decreased with ionic strength. 25% ethanol in the 0.15 M NaCl staining buffer reduced the wavelength shift at high dye concentrations, indicating that the strength of type 2 binding depends on DNA conformation in addition to ionic strength. The fluorescence spectrum was independent of whether DNA in chromatin was complexed with histones or not. However, histone-depleted thymocytes fluoresced more intensely than cells in which DNA was complexed with histones, the difference being greater at low concentrations of Hoechst 33258. Hence, type 2 binding to DNA in chromatin appears to be less restricted by histones than type 1 binding.

Direct measurements of transcapillary exchange during steady-state conditions have been performed in the rete mirabile of the eel. The capillaries were found to be more than 30 times as permeable to THO (PTHO = 33.2 times 10(-5) cm sec-1), ethanol and antipyrine than to K+. The mutual relationship of the permeabilities for K+, Na+, urea and sucrose were similar to that between the corresponding free diffusion coefficients in water. The permeability characteristics did not change when the perfusate contained metabolic inhibitors. Additional of 1 mM/l of albumin lead to a significant transcapillary osmotic flow. NaCl, urea and sucrose, however, did not cause osmotic flow. Based on the quantitative values for permeability and volume flow the capillary pores should be about 1300 A and have a frequency of 1.3 times 10(6) per cm2 of the capillary surface, occupying an area of about 0.1% of the total area. The results obtained in the present investigation raise questions as to the validity of the Pappenheimer single-pore theory for transcapillary transport as well as to the fine structure of the capillary pores. As an alternative to Pappenheimer's theory a multi-pathway model is proposed in order to explain transcapillary transport.

O2 consumption, electromyographic activity (EMG), heart rate (HR), cloacal temperature (Tb) and broodpatch temperature (Tsb) were measured in bantam hens incubating eggs of different temperatures (Te). For comparison, the metabolic response to low ambient temperature (Ta) was measured in non-incubating hens.

The yield of luminescence from indole in an equivolume mixture of glycol and water observed during irradiation with 60 Co γ-rays is found to be considerably larger than that obtained during exposure to 220 kV X-rays. The difference is attributed to the γ-induced Cerenkov light which is absorbed by the solute and thereby causes additional luminescence. Thus, about 80 percent of the singlet excitation in a 10 −2 mol dm −3 indole solution is due to this effect. The yields of the fluorescence and phosphorescence induced by Cerenkov light are determined as a function of solute concentration. The yield of Cerenkov light in water is calculated as a function of the radiation energy for various sample sizes. The results indicate that because of this effect radiations having sufficient energy to produce Cerenkov light are not suited for studies of radiation-induced solute excitation in systems where energy transfer from the solvent does not contribute to the luminescence yield.

Electron scavenging efficiencies have been measured at 77 and 4 K in ethylene glycol-water glass for the following scavengers which span a 250-fold range of scavenger efficiencies at 77 K: HCl, NaNO3 and K2CrO4. The range of scavenging efficiencies decreases to 62 at 4 K with the largest relative change occurring for the less efficient scavengers. These results are suggested to be most consistent with a model in which scavenging occurs by tunneling from shallowly and deeply trapped electrons at 4 and 77 K, respectively.

The luminescence emitted during x‐ray irradiation of H2O and D2O ice at 77 K exhibits an identical emission band peaked at 373 nm. D2O also exhibits a band peaked at 534 nm which is not seen for H2O. The 373 nm band appears to have a decay time in the range 10−4–10−3 sec, whereas the 534 nm band decays completely in less than 10−4 sec. The emission yield is G∼2×10−2 and G∼2×10−3 for D2O and H2O, respectively. The yield of the peak at 373 nm is significantly increased by NaCl, NaBr, NaI, and HCl in concentrations above 10−3M, whereas the 534 nm band in D2O is not affected by any of these additives. AgNO3, H2O2, and NaNO3 reduce the emission yield whereas other efficient electron and OH scavengers like CCl3COONa and acrylamide do not affect the luminescence even in concentrations of 1M. The identity of the luminescent species is obscure. The scavenger effects indicate that it has a mobile precursor which is not electrons or OH and probably not H atoms. The emission yields, as well as the decay time of the 3...

1. The poikilothermic state of house martin nestlings has been studied by measuring body temperature (Tb), oxygen uptake (VO2), heart rate (HR), breathing rate (BR), and shivering at different ambient temperatures (Ta). 2. TheTb of nestlings less than 4 days old followedTa within 0.5°C, and the nestlings survived at least 6 h atTb about 10°C. 3. There was no difference in either cooling or warming rate between living and dead 3-day-old nestlings. 4. The Q10 of VO2 and HR was 2.1–2.5 atTb above 35°C but increased progressively as theTb was lowered. 5. When the nestlings were cooled, breathing stopped atTb=10°C; upon rewarming it was resumed at 15°–25°C. 6. We conclude that the cold tolerance of nestlings less than 1 week old is an important part of their survival strategy. Metabolically, they behave like true poikilotherms with the exception that their metabolic function decreases more sharply at low temperatures and that they stop breathing and die at prolonged exposure atTb below 10°C.

The fluorescence characteristics of intracellular fluorescein, formed by the hydrolysis of fluorescein diacetate in peripheral human lymphocytes, were studied by fluorometry on cell suspensions and compared to those of albumin bound and free fluorescein in solution. The absorption and fluorescence spectra of both intracellular fluorescein and fluorescein in aqueous solutions of albumin and glycerol were red shifted by 2-10 nm as compared to the spectra of fluorescein in phosphate buffered saline. The fluorescence polarization (P) of both intracellular fluorescein and a mixture of albumin-bound and free fluorescein showed a decrease towards low emission wavelengths and an increase toward high excitation wavelengths. The results were found to be consistent with a simple model assuming that part of the intracellular fluorescein is dissolved in the aqueous phase of the cytoplasm, giving P less than 0.1, while the rest is bound to macromolecules, giving P = 0.33. The fraction of bound intracellular fluorescein was estimated to be about 70%. Fluorescein was found to bind with high affinity and more rigidly (P = 0.43) to albumin than to intracellular macromolecules in general.

Four types of mouse embryo fibroblast cells of different oncogenic potential were investigated with respect to uptake of the tumor localizing agent hematoporphyrin derivative (Hpd) and sensitized photoinactivation. Cell size and cellular content of Hpd were measured simultaneously for single cells by means of flow cytofluorimetry. The more malignant cell types had a slightly higher porphyrin uptake per unit cellular volume than the untransformed type, while the photosensitivity of cells incubated with Hpd was equal for all the cell types. Since Hpd seems to concentrate in membranes, this may be related to the fact that the membrane areas of malignant cells are relatively larger than that of untransformed cells, due to the presence of more microvilli. The present study indicates that the preferential localization of Hpd in tumors, as well as the high efficiency of phototherapy reported in the literature, are due to extracellular differences between the tumors and normal tissue.

Antler blood flow was studied in a 2 year old male reindeer during the last half of the antler growth period using an electromagnetic flow probe chronically implanted around the superficial temporal artery. Arteriovenous (a-v) differences of calcium were measured on antler blood. The blood flow increased from 60--90 ml/min when the antler was half-grown to 100--120 ml/min when fully developed. Subsequently a reduction was observed towards shedding. Positive a-v plasma calcium differences (on average 0.2 mM) were recorded during the period of active growth. Two bulls maintained positive a-v calcium differences after a 48 hour starvation period, in spite of reduced arterial calcium concentrations. Exercise to near exhaustion caused a 2 degrees C rise in the rectal temperature. Antler blood flow was decreased immediately after exercise and returned to pre-exercise values usually within 5--10 min. Since no overshoot in antler blood flow was recorded during the hyperthermia it is concluded that variations in blood perfusion of the antlers are without importance in the defence against hyperthermia during and after exercise.

Emission samples were obtained from two medium-sized power plants, one fired with oil and the other with pulverized coal. Particles obtained by a miniscale plume stack gas sampler (MIPSGAS), simulating the dilution process in the plume, were subjected to detailed physical, chemical and biological characterization. Studies by scanning electron microscopy and by Coulter counter demonstrated that the particles from the oil-fired boiler were considerably larger than the particles from the coal-fired boiler. Chemical analyses revealed more organic substances and more S, Ni, V, in the oil than in the coal particles. The latter contained a larger proportion of Al, Si, Cl, K, Ca, Ti, Mn, Fe, Se, Rb, Y, Zr, Ba and Pb. Biological testing revealed a greater acute and subacute toxicity by the intratracheal route in the hamster, a greater toxicity to alveolar macrophages and a greater lung retention of BaP coated on the particles from oil combustion than on those from coal combustion. In another sampling line, employed simultaneously with the MIPSGAS-particulate sampler, the total emissions were collected, i.e., both particle and gas phase. These samples were used for chemical analyses and Ames mutagenicity test. Analyses of specific PAHs in emissions from both plants demonstrated that concentrations were below the detection limit (less than 4 ng/m3 of benzo(a)pyrene), which is in accord with an efficient combustion of the fuel. The mutagenicity of the samples were below the detection limit of the mutagenicity assay. Images FIGURE 4. FIGURE 5.

The luminescence of indole and tryptophan in EG/H2O glass at 77 K during irradiation with x rays and uv light has been studied with various concentrations of two electron scavengers (acrylamide and trichloroacetate). The two types of radiation gave identical emission spectra except for a considerable enhancement of the phosphorescence to fluorescence ratio with x irradiation. The effect of the scavengers on the yields of x‐ray‐induced singlet (S) and triplet (T) levels were calculated from the results. It was found that the yield versus scavenger concentration curves could be decomposed into two components, one being independent of the scavenger, the other one decreasing exponentially with increasing scavenger concentration. Associating the former component with excitation directly from the ground state and the latter with excitation resulting from recombination between solute cations and electrons, it was found that about 80% of the solute excitation is due to recombination. In the case of indole the ratio of triplets to singlets T/S formed by direct excitation was T/S=0.2, whereas for the recombination T/S=1.2. The latter value was attributed primarily to spin relaxation of the recombining ion pairs, whereas intersystem crossing between highly excited levels and recombination in spurs appeared to be of minor importance in this respect. The spin relaxation of the recombining ions, the large scavenger concentrations needed to quench recombination, and the observation that T/S was independent of the LET of the radiation indicated that the recombining ions are closely associated so that the ion pair may be comparable to the CTTS states involved in photoionization of solutes rather than to pairs of free separate ions.

Flow cytometric determination of the DNA and protein content of E. coli has been carried out by means of a microscope-based flow cytophotometer with a high pressure arc lamp excitation ligh source. Fluorescence (DNA)/light scatter (total cell protein) dual parameter histograms with a resolution cv of 5% were obtained for cells labeled with a combination of mithramycin and ethidium bromide. Histograms of E. coli in rapid and slow exponential growth are presented to exemplify how the cell cycle kinetics of bacteria can be studied in much more detail than has been possible by other methods. Significant effects of chloramphenicol and penicillin on the cell cycle distribution and cell numbers of E. coli cultures were evident after one hour of culture. The data provided information on which parts of the cell cycle and what types of processes were affected by the drug. It appears that flow cytometry may become a valuable tool in studies of the cell cycle of bacteria as well as in clinical drug testing.

There have been several reports on the distribution of DNA in premalignant and malignant liver cells after carcinogen treatment in rodents. The most striking result so far is that ploidy distributions seems to depend more on experimental protocols and less on carcinogenesis per se. The present study demonstrates that an evaluation by means of flow cytometry and stereological image analysis yields results showing similar ploidy distributions throughout the known sequence of tissue changes seen during liver cancer development. Furthermore, our results demonstrate inter-individual differences between the lesions in each of the steps in these tissue changes, (foci, nodules and hepatocarcinomas). The present study gives no reason to conclude that changes in ploidy distribution are essential in liver carcinogenesis.

The feasibility of flow cytometry for measurements on bacteria has been demonstrated by measurements of DNA-associated fluorescence of Escherichia coli K-12 in various phases of cell growth. Bacteria were stained with a combination of ethidium bromide and mithramycin after fixation in 70% ethanol. Cultures grown to stationary phase accumulated in two peaks representing cells with two and four chromosomes. Qualitatively similar histograms were obtained with cells grown in the presence of chloramphenicol, whereas cells of the temperature sensitive strain E 177 (dnaA) ended up with only one chromosome per cell at the restrictive temperature. The fluorescence intensity of cells with one chromosome was about 10(3) times smaller than that of human diploid cells. Instrumental resolution at this level of intensity was CV = 5%, whereas peak widths corresponded to CV = 7-8%. Dyes bound to RNA did not appear to contribute significantly to the fluorescence.

Eels (Anguilla anguilla) which were exposed to copper-contaminated fresh water (30–60 ρg Cu/I) died with signs of vibriosis (Vibrio anguillarum). Eels kept in non-contaminated fresh water (

Escherichia coli rnh mutants lacking RNase H activity are capable of recA+-dependent DNA replication in the absence of concomitant protein synthesis (stable DNA replication). In rnh dnaA::Tn10 and rnh delta oriC double mutants in which the dnaA+-dependent initiation of DNA replication at oriC is completely blocked, the recA200 mutation encoding a thermolabile RecA protein renders both colony formation and DNA synthesis of these mutants temperature sensitive. To determine which stage of DNA replication (initiation, elongation, or termination) was blocked, we analyzed populations of these mutant cells incubated at 30 or 42 degrees C in the presence or absence of chloramphenicol (CM) by dual-parameter (DNA-light scatter) flow cytometry. Incubation at 30 degrees C in the presence of CM resulted in cells with a continuum of DNA content up to seven or more chromosome equivalents per cell. The cultures which had been incubated at 42 degrees C in the absence or presence of CM consisted of cells with integral numbers of chromosomes per cell. It is concluded that active RecA protein is required specifically for the initiation of stable DNA replication.

The effect of colchicine and colcemid (1 × 10−6 M) on the blastogenic response of human lymphocytes to concanavalin A was studied in vitro by three different methods. (a) Measurement of [3H]thymidine ([3H]dThd) incorporation which was strongly suppressed by the drugs. (b) Volume spectroscopy showing that the growth of cellular and nuclear volume was only moderately affected by the drugs during the first two days of culture: in drug-treated cultures, 25% of the cells responded by measureable growth of their nuclear volume as compared to 30% in untreated cultures. After two days, however, growth stagnated in drug-treated cultures, and cell division never occurred. (c) Flow cytofluorometry, showing that in drug-treated cultures the number of cells measurably increasing their DNA content, i.e. entering S-phase, was about 60% of that in untreated cultures. However, the drugs caused a majority of the responding cells to stop DNA synthesis before completing S-phase. This effect could not fully account for the strong suppression of the [3H]dThd incorporation indicating that colchicine and colcemid caused a malfunction of the [3H]dThd assay. It is concluded that colchicine and colcemid do not significantly inhibit initiation of a blastogenic response indicating that microtubuli, which are known to be affected by these drugs, are not essential for the triggering of blastogenesis.

The change in fluorescence quantum yield for indole as a function of excitation wavelength between 250 and 220 nm is found to vary with the static dielectric constant of various alcohol—water mixtures at 296 K. The supports the intermediacy of a CTTS state in the photoionization process.

The blastogenic response of human lymphocytes in vitro to hyperoptimal concentrations of concanavalin A (Con A) has been studied by means of volume spectroscopy (measuring cellular and nuclear volume), flow cytofluorometry (measuring cellular DNA content) and incorporation of [3H]thymidine ([3H]dThd). The optimal Con A dose with respect to [3H]dThd incorporation was about 30 micrograms/ml. In cultures given hyperoptimal doses, e.g. 100 micrograms/ml, [3H]dThd incorporation was strongly inhibited, whereas the number of cells entering S-phase and significantly increasing their cellular and nuclear volume was considerably larger than with 30 micrograms/ml. With 200 micrograms/ml Con A, which induced negligible [3H]dThd incorporation, the percentage of responding cells was even larger. Hence, doses of Con A, which were hyperoptimal with regard to [3H]dThd incorporation, induced blastogenic response, including DNA synthesis, in a larger percentage of the cells than did the optimal dose. However, in cultures with hyperoptimal Con A doses, the progression of the cell cycle stagnated mainly during S- and G2-phase and few cells completed mitosis. Thus, the blocking effect of hyperoptimal doses was not confined to any particular point of the cell cycle. The reduced [3H]dTd incorporation, seen with hyperoptimal doses, is attributed partly to a failure of this assay under such conditions.

Willow ptarmigan chicks raised on a diet containing 265 mg ascorbic acid/kg develop scury-like symptoms and die by 4 weeks of age. If blueberry plants are given as an ad libitum supplement to this diet, the malady is prevented. We have described the clinical, pathological and histological changes which accompany this malnutrition and conclude that they are in accord with the description of scurvy in guinea pig and man. Biochemical determination of ascorbic acid synthesis in the kidney of ptarmigan chicks indicated a rate of synthesis five times that found in livers of growing white rats. Blueberry plants and many other plants found in the natural diet of ptarmigan chicks contain 2,000 to 5,000 mg ascorbic acid/kg dry weight. Feeding experiments showed that the pathological signs were avoided and that already afflicted chicks recovered if the vitamin C content of the diet was raised to 750 mg/kg dry weight of food. Since the food intake of the chicks was 5 to 8 g/day the daily requirement of external vitamin C is about 150 mg/kg body weight. To our knowledge this is the first example of an animal which, while producing vitamin C itself, requires substantial amounts of external vitamin C to survive.

1. 1. The O 2 and CO 2 permeability of the eel swimbladder is about one-tenth of values reported for connective tissue. 2. 2. The impermeability resides principally in the silvery outer layer of the swimbladder. 3. 3. The silvery layer contains many needle-shaped crystals. 4. 4. Guanine accounts for about 13 per cent of the dry weight of the silvery layer.

Studies of the X-ray- and UV-induced luminescence of tryptophan and tyrosine in solution between 77°K and 300°K are reviewed. The fluorescence and phosphorescence spectra observed during X-irradiation are identical to those induced by UV light, but the phosphorescence to fluorescence ratios obtained with X-rays are much larger than those found with UV light. The experiments seem to show that charge recombination is the dominating mode of the X-ray-induced excitation at low temperatures, giving rise to roughly 85% of the X-ray-induced luminescence at 77°K. The fraction of the X-ray-induced excitation which results from charge recombination decreases with increasing temperature and becomes negligible above 220°K. This causes the yield of X-ray-induced excitation of the radiative levels of tryptophan to decrease from G = 5 excited molecules/100 eV absorbed in solute, at 77°K, to G = 0.4 at room temperature. The mechanisms for quenching of charge recombination are discussed.

Hemoglobin of the eel, Anguilla anguilla , was found to be a mixture of two fractions separable by ion-exchange chromatography, one anionic, the other cationic at pH 8.5. The anionic fraction showed a large Root-shift as well as Bohr-shift, but the cationic fraction lacked both.

— The lumincscence arising from L-tryptophane and L-tyrosine in aqueous solutions at 77dK during irradiation with u.v.-light and with X-rays has been studied. The spectra obtained with the two types of radiation were largely similar, differing only in that the yields of phosphorescence relative to fluorescence were considerably enhanced in the case of X-irradiation. The decay times observed for the exponentially decaying phosphorescence, being 6.6 sec and 2.7 sec for tryptophane and tyrosine respectively, were the same for both kinds of irradiation. The G-value of the X-ray induced luminescence was about 10 for both tryptophane and tyrosine. Thus, about 30 per cent of the total energy absorbed from X-rays in these compounds was re-emitted as light. It was concluded that the X-ray induced fluorescence and phosphorescence originate from the same levels as does the luminescence caused by u.v.-light, i.e. the lowest excited singlet and the lowest triplet level of the aromatic structure of these compounds. In the case of X-irradiation the enhanced ratios between the yields of phosphorescence and fluorescence indicated that some process other than excitation directly from the ground state contributed considerably to the luminescence yields. Assuming this process to be a recombination between the ionized molecule and its electron, it was calculated that the contribution to the luminescence yield from excitations directly from the ground state relative to that from ionizations, was negligible for both compounds.

Steen, J. B. The physiology of the swimbladder in the eel Anguilla vulgaris. II. The reabsorption of gases. Acta physiol. scand. 1963. 58. 138–149. — Gas reabsorption from the reabsorbent swimbladder has been investigated with the micro-blood analyzer and gas analyzer of Scholander and coworkers. It was shown that O2 moves both from blood to gas and vice versa. The rate of O2 reabsorption depends upon blood flow and the O2 gradient between gas and blood. All the observations support the view that O2 is reabsorbed by diffusion. Blood flow is much increased by anoxia. The reabsorbed O2 is hardly of any respiratory use during O2 shortage of the water, but may be important when the eel is in the air. The increased O2 reabsorption during O2 shortage may also guide the eel to a more O2 rich environment. Fishes have less hydrostatic problems the deeper they live. The reabsorbent bladder of the eel seems to have about the same diffusion characteristics as has the human lung, the functional superiority of the latter beeing due primarily to its favourable surface to volume ratio.

Respiration of the sea urchin Strong ylocentrolus droebakiensis has been studied with measurements of oxygen uptake at different ambient temperatures and with parts of the surface organs selectively covered with wax. It was confirmed that the tube feet serve as the main respiratory organ. At 16°C the oxygen uptake is reduced if a small proportion of the tube feet surface area is covered or if the external oxygen tension is reduced. At 6°C a much larger decrease of podial area or tension is needed to reduce the oxygen uptake. The calculated oxygen uptake, based on podial dimensions and measured oxygen tension differences, is about ten times larger than the measured oxygen uptake. The inability of the sea urchin to utilize its theoretical respiratory capacity is tentatively explained as a consequence of its poorly developed circulatory system with the lack of a respiratory pigment. Comparison of the respiratory data from sea urchins with similar data from the eel reveal some trends in the evolution of respiratory mechanisms.

Steen J. B. The effect of juvenile hormone on the respiratory metabolism of silkworm pupae, as recorded with a new semi-micro device. The respiration of Polyphemus pupae during normal pupal-adult development has been compared to that during abnormal development as induced by juvenile hormone. Respiration was measured as oxygen-uptake with a new semi-micro recording spirometer. Striking differences were found and it is suggested that the respiratory response may be used as a sensitive assay for the juvenile hormone.

Steen, J.B. The physiology of the swimbladder of the eel, Anguilla vulgaris. I. The solubility of gases and the buffer capacity of the blood. Acta physiol. scand. 1963. 58. 124–137. — Some physiological properties of eel blood which may have importance in gas exchange in the swimbladder have been investigated. Using the Scholander and Roughton syringe analyzer for blood gases and micromethods for determination of lactic acid and pH the solubility of the gases of air has been measured at various temperatures and pH levels at pressures up to 1 atm. The buffer capacity of eel blood has also been studied in some detail. The O2- and CO2-solubility followed the same general pattern as is known to obtain in blood of other species. The O2-content of blood at a pO2 of I atm is reduced by about 40% when the pH is lowered from arterial values to 7.0. The N2 and Ar solubility is approximately 10% reduced when the pH of eel blood is lowered from about 7.8 to 7.5. Using the same experimental technique no such effect was found on eel plasma, blood from man, trout or cod.

This article reviews a study of the radiation-induced luminescence of tryptophan, tyrosine, and trypsin, with the intention of elucidating the possible importance of molecular excitations for the radiation damage of proteins. In all these substances, the spectrum of the X-ray induced emission, as obtained at 77°K, was similar to that excited by uv light, except that a considerable enhancement of the phosphorescence to fluorescence ratio occurred with X-irradiation. This could be accounted for by assuming that about 90 per cent of the emission resulted from electron-ion recombination, subsequently giving rise to excitation of the radiative levels. The G-value for the emission of light was 5 for both tryptophan and tyrosine, leading to the conclusion that at least 40 per cent of the total number of ionizations resulted in recombination and subsequent emission of light. The emission from trypsin appeared to originate almost exclusively from the tryptophan residues. The emission yield (G = 0.17) indicated tha...

1. 1. Histological methods revealed that blood entering the gill filament may reach the efferent artery (1) through the lamellae, (2) through a central, lymphatic compartment and (3) directly from the afferent to efferent artery at the tip of the filament. 2. 2. In gill filaments immersed in saline, blood was shown to pass through the lamellae in the presence of adrenaline, and through the other vascular paths in the presence of acetylcholine. 3. 3. Inravascular injection of adrenaline caused a marked increase in the degree of blood oxygenation in the eel. 4. 4. The arterial oxygen tension was much higher in active than in resting eels, whereas the oxygen tension of efferent water was higher in resting than in active eels. The average difference in oxygen tension between blood and water was the same in resting and active eels. 5. 5. The expected oxygen uptake, as calculated from the anatomical dimensions of the gills and the measured blood-to-water oxygen tension difference, corresponded to the oxygen uptake which has been measured for active eels. 6. 6. It is concluded that the vascular arrangement of the gills of the eel permits variations in blood oxygenation, and thereby in oxygen uptake, by directing a varying proportion of the blood to circulate the respiratory lamellae while the rest is shunted through the alternate non-respiratory path of the central cavity. 7. 7. A double, intercommunicating vascular system, more or less similar to that of the eel, was demonstrated in all the other ten teleost species investigated, and we suggestthat it is common to all teleosts.

1. The P(O2) of venous blood from the active swim-bladder of the eel was shown to decrease with distance from the exit of the rete. This systematic change did not occur in non-secreting bladders, nor during conditions where exchange in the rete had been abolished.2. The observed change in post-rete venous P(O2) has the same rate constant as the Root-on shift.3. These findings modify the accepted model for counter-current multiplication of O(2) in the swim-bladder system by introducing rate constants for diffusion and action of acid in the rete.4. The part played by the assumed impermeability to acid of the arteriovenous partition of the rete is in the modified model replaced by the slow Root-on shift.5. The modified model contradicts the Kuhn model in that extraction of O(2) from blood is decreased at low flow and that at normal flow conditions part of the lactic acid produced can be re-used.6. Similar modifications are indicated in the model for concentration of inert gases.

— The light emitted by adenine and thymine and the related nucleosides and nucleotides in ethylene glycol/water glass during irradiation at 77°K with X-rays and 270 nm U.V. light has been studied. It was found that the same radiative levels were excited by both types of radiation. However, the phosphorescence to fluorescence ratios observed with X-rays were considerably enhanced relative to those obtained with U.V. light. This observation was taken to mean that a major fraction of the excitation results from ion recombination, although direct excitation of the triplet manifold as well as intersystem crossing between upper excited levels may have contributed to the enhancement as well. The yields of the X-ray-induced excitation of radiative levels. which were calculated by combining the yields of X-ray-induced emission and the quantum yields observed with u.v.-excitation, corresponded to: G≥ 4.0 excitations per 100 eV of dose absorbed in the solute for adenine and G≥ 1.8 for thymine. The excitation yields obtained for the nucleosides and nucleotides were somewhat smaller than those observed for the corresponding bases. It was inferred from the yields that a substantial fraction of the dose absorbed in the ribose of the nucleosides was transferred to the radiative levels of the constituent bases.

— The luminescence from tryptophan in the dry state and in aqueous glass. induced by u.v.-light and X-rays at 77°K, has been studied. The spectra of the luminescence from the dry material, which were identical for the two types of irradiation, were attributed to the same excited singlet level as that giving rise to the fluorescence from the aqueous sample. The strong phosphorescence exhibited by the latter. could not be detected for the dry material with either type of irradiation. This was attributed to a strong quenching of the radiative triplet level occurring upon crystallization of the substance. The yield of X-ray induced fluorescence of tryptophan in aqueous glass was found to be similar to that observed in the dry state. It was concluded that there is no extensive transfer of energy between the solvent and the solute molecules contributing to the fluorescence yield of tryptophan in aqueous glass.

1. 1. The ventilatory responses have been studied in eels in which gills and skin were separately exposed to gas mixtures with varying concentrations of carbon dioxide and oxygen. 2. 2. In air at 20°C the breathing frequency was about 45 per hr. The frequency increased on reducing the oxygen tensions in the surrounding gas. When the eel was surrounded by pure oxygen the ventilation tended to stop, whereas in pure nitrogen the respiration frequency was about four times as high as in air. Intermediate breathing frequencies were observed if either the gills or the skin only were exposed to the various gas mixtures. 3. 3. Neither breathing frequency nor depth of breathing was affected by carbon dioxide content in the inspired gas lower than 5 per cent. Higher content of carbon dioxide than 5 per cent invariably had an inhibitory effect on respiration when administered to the gill region, but had no such effect when administered only to the skin. 4. 4. Respiratory regulation in air and in water has the important feature in common that hypoxia is acting as a respiratory stimulus in both situations. Carbon dioxide does not seem to play any role in regulation of the animals' arterial ventilation.

An apparatus is described by which the X-ray- and U.V.-induced emission and absorption of solutions and solid materials can be studied during, as well as after, irradiation at any temperature between 77 and 330 K. Fluorescence and phosphorescence spectra can be obtained separately and simultaneously. The emission spectra of phenanthrene observed during irradiation with X-rays and U.C. light at 77 K are compared, and the kinetics of the formation and decay of trapped electrons in a glycol + water glass, as observed during and after irradiation with X-rays and intense U.V. light, are demonstrated.

Summary. The daily food intake has been measured in five pigeons while they were kept for 2-4 weeks at -10° C, +18° C, and -24° C. At the end of each period the oxygen consumption was measured at various temperatures between -35° C and +20C. It was found that the food intake was closely correlated with the oxygen consumption, both of them indicating nearly the same critical temperature. Below this temperature both oxygen consumption and food intake increased linearly with the body-to-air gradient.

The proportion of the total heat production of herons and gulls which at ambient temperatures ranging from—10° C to 35° C is dissipated to cold water or air surrounding their legs has been measured. At low ambient temperatures less than 10 % of the metabolic heat is lost from the legs. At higher ambient temperatures an increasing proportion of the metabolic heat is lost from the legs and at 35° C almost the entire heat production is dissipated through the legs. Heat loss to water was found to be about four times higher than to air of the same temperature. The degree of heat loss from the legs was shown to react within seconds to changes in ambient temperature. Likewise, panting stopped immediately when the legs were irregated by cold water. It is concluded that the naked legs of these birds serve as controlled heat conduits of great importance in thermoregulation.

MITOGENS induce blastogenesis and mitosis in lymphocytes after reacting with specifie receptors on the cell surface. In contrast to antigen receptors, the receptors for mitogens may be common to large fractions of the lymphocyte population. For example, the lectin concanavalin A (con A) causes mitosis in most T cells. The specificity of the receptors is believed to depend on constituent carbohydrate residues, and the effect of mitogens can be modified strongly by enzymes which govern the removal of carbohydrates from the cell surface1. Thus these enzymes resemble mitogens in that there are specific reacting sites for them on the cell surface. We report here an enzyme which seems to be mitogenic in itself: α-mannosidase produces blastogenesis and mitosis in lymphocyte cultures with an efficiency comparable with that of con A. As α-mannosidase is found in various tissues and cells, including lymphocytes, as well as in blood plasma2–4, our observation may have interesting immunological implications. Another enzyme, galactose oxidase, has been reported to be mitogenic although less strongly than our enzyme5.

The spectra of the radiofluorescence RF, afterglow AG and the thermoluminescence TL of H 2 O and D 2 O ice are reported. The RF spectrum of D 2 O exhibits two bands, whereas for H 2 O only one of these is seen. The spectrum of TL is different from that of RF and AG. It is argued that if any of these spectra are due to de-excitation of the triplet state of water it is that of the TL. This spectrum is peaked at 335 ± 3 nm and has a width of 46 nm.

Although heart rate in most species reflects the metabolic state of the animal, emotional stimuli may act as strong modifying agents. This has been experienced by arctic explorers challenged by polar bears (Nansen 1898) and by TV-watchers during exciting shows. It is also noticed in animals under a variety of experimental conditions (Folkow and Neil 1971). Thus, in some animals, cortico-hypothalamic activity may strongly influence the cardiovascular response pattern in certain situations. Inexperienced parachuters, for instance, may more than double their heart rate, without any increase in metabolism, prior to a jump (Ursin, Baade and Levine 1977). Oppossums and deerkids, on the other hand, display pronounced cardiac retardation, much reduced breathing rate and temporary Joss of consciousness (“playing dead”-reaction) when exposed to danger (Folkow and Neil 1971). In this context it is noteworthy that the cardiac response to danger in arctic explorers does not involve loss of consciousness. This was well demonstrated when H. Johansen from his supine position underneath a hungry bear exclaimed to his companion, F. Nansen: “You must look sharp it you want to be in time” (Nansen 1898).

The decay of x‐ray‐induced et− in glycol‐water glass and the reduction of G(et−) by various scavengers have been studied as functions of the temperature. The decay of et− was independent of temperature from 77 to 113 K as expected if the reaction occurs primarily by electron tunneling. The reduction of G(et−), however, decreased significantly with increasing temperature in the same region, the temperature dependence being larger for less efficient scavengers. The results are qualitatively accounted for by the assumption that a significant fraction of the electrons react prior to formation of stable traps, viz. from shallow, transient traps.