ULTRASTRUCTURE OF SELECTIVE CHLOROPLAST DESTRUCTION AFTER SOMATIC CELL FUSION IN GRIFFITHSIA PACIFICA KYLIN (RHODOPHYTA)1,2

Fusion of somatic cells from different geographic isolates of Griffithsia pacifica is followed by a cytoplasmic incompatibility reaction (CIR)⁵ in the cytoplasm donated by only one of the isolates. This CIR is characterized by the aggregation, fusion, and lysis of chloroplasts of the sensitive strain; the cholorplasts of the other strain are unaffected. Within a given cell, chloroplast fusions result in a 50% decrease in chloroplast number in the first 8 h; over the next 3–5 weeks, chloroplast lysis leads to the complete loss of photosynthetic pigments (18). Results of this ultrastructural study indicated that the primary effect of the cytoplasmic incompatibility reaction was a directed destruction of the sensitive strain chloroplasts. No aggregation or abnormalities were seen in organelles other than the chloroplasts. Chloroplast destruction was accompanied by extensive vesiculation of the cytoplasm and a definit change in the physiological state of the cell; the dictyosomes became inactive and there was a reduction in the amount of endoplasmic reticulum, cytoplasmic ribosomes and starch grains. This selective destruction of one chloroplast population in the presence of a second population of unaffected chloroplasts suggests that the incompatibility reaction observed in G. pacifica results from competitive interactions between the two chloroplast types.     

Effect of protons and cations on chloroplast membranes as visualized by the bound ANS fluorescence

Structural changes in the chloroplast membranes caused by acidification and heat-treatment are studied by observing the changes in the fluorescence of ANS bound to thylakoid membranes. On addition of acids to buffered suspension of isolated pea chloroplasts, the fluorescence intensity of bound ANS shows a sigmoidal rise on reaching a pH value of about 4.5. A part of the fluorescence enhancement of bound ANS brought about by protons is not reversible on back titration with alkali. The reversible part of acid induced rise in ANS fluorescence possibly reflects structural changes expected to be associated with photophosphorylation. Divalent cations enhance the fluorescence of ANS bound to chloroplasts between a pH range 4.5–7.0 but diminish it if the pH is below 4.5.Addition of acid to heat-treated chloroplasts shows similar sigmoidal rise in ANS fluorescence intensity on lowering the pH to about 4.5. On addition of acid upto a pH of 3.1, the ANS fluorescence is greater than that of untreated chloroplasts, however, at pH below 3.1, the fluorescence of bound ANS is lower than the control chloroplasts. This observation indicates that heat-treatment caused some alteration of the microstructure of thylakoid membranes of chloroplasts besides the usual loss in the O₂ evolving capacity.This is further confirmed from the studies of Hill-activity and ANS binding to chloroplasts incubated at various temperatures in the absence and presence of aliphatic alcohol. Hill-activity (DCPIP reduction) of chloroplasts incubated at temperatures between 25 C and 55 C first increases reaching a maximum at 45 C and then declines rather sharply, when the chloroplasts are heated beyond 45 C (Tmax). The presence of 200 mM n-butyl alcohol or 40 mM n-amyl alcohol during the warming treatment lowers the temperature by 8 C at which the decline in the Hill-activity is observed. An enhancement in the fluorescence intensity and a blue shift of the emission spectrum of bound ANS are noted if the chloroplasts are heated beyond the Tmax either in absence or presence of alcohol. The changes in the fluorescence of ANS bound to heat-treated chloroplasts plausibly reflect the nature of the structural changes in chloroplasts during the heating upto 55 C.Abbreviations ANS 1-anilino-8-naphthalene sulphonate - DCPIP 2,6-dichlorophenol indophenol     

Growth temperature acclimation byAmoeba proteus: Effects on cytoplasmic organelle morphology

Summary The effects on subcellular morphology of maintaining amoebae at temperatures other than 20 C (the routine culture temperature) were assessed. Estimations of cycling potential at each temperature confirmed that acclimation had affected gross cell functioning. Generation times ranged from no division at 6 C, to an optimal minimum of 2 days at 22 C.Organelle morphology changes were studied after 5 days of growth at the new temperatures; alterations were most evident at the extremes of 6 and 28 C. The main mitochondrial alteration resulted in changes to the ratio of Type I: Type II organelles; with a decrease in Type I forms away from the optimal range of 20–22 C. Extended culturing at 6 C generated mitochondrial matrical inclusions. Ribosomal attachment to the endoplasmic reticulum, a common feature of 20 C-grown cells, decreased at the temperature extremes, where an increase in free ribosomes occurred. Upon extended culture at 6 C helical structures, usually observed in groups only within the nucleus, were also present in the cytoplasm. Golgi complexes were less common in cells maintained at extreme temperatures and often showed differences in shape. These changes were all reversible on a return to culturing at 20 C.The possible functional significance of these findings is discussed.     

High-resolution autoradiography of nuclear modifications during and after heat treatment ofNeurospora crassa

Summary The appearance of perinucleolar electron-dense spots in the nuclei of macroconidia ofNeurospora crassa incubated at 46C and their disaggregation after shift-down to 25 C have been investigated by high-resolution autoradiography after (5-³H) uridine pulses with or without chase periods. The RNA of these ribonucleoprotein-rich dense spots has been found to originate mainly from the heatsensitive nucleolus; after return to 25 C, the nucleolar activity was recovered and the RNA material stored either in an unprocessed or a mature rRNA form in the dense spots was found to be progressively extruded into the cytoplasm.     

Supraoptimal growth-temperature reduces the heat-shock sensitivity of the chrysophycean flagellatePoterioochromonas malhamensis

Summary The chrysophycean flagellatePoterioochromonas malhamensis shows some characteristic alterations after a sublethal heat-shock (42 C, 16 minutes). Most cells round up and retract their cytoplasmic tail. The lorica formation is affected and, in nearly all cells, flagellar activity. Most membrane systems, especially the dictyosome, are severely damaged. In contrast the flagellar root apparatus and the cortical microtubules seem to be unaffected.After growth at a supraoptimal temperature of 33 C and a subsequent heat-shock (42 C, 16 minutes) the cells do not show the heat injuries reported above. The ability to form the lorica becomes also adapted to higher temperatures.Possible adaptation mechanisms are discussed.     

Temperature dependent structural changes of intraphage T7 DNA

The phenomena connected with the first phase transition step of the native T7 phage at 40C–65 C have been studied using various methods. In this temperature range a) the optical melting curve shows an absorption decrease, b) the maximum of the small-angle X-ray scattering characteristic for DNA packing disappears, c) there is a drop of biological activity and d) there are changes in the structure of the difference absorption spectra of native phages versus isolated DNA. All data are interpreted assuming a structural change of the DNA due to the release of its protein coat towards the end of the first phase transition step (at 60–65 C in the case of M9 buffer). Above this temperature the intraphage DNA packing appears to be destroyed and the DNA structure seems to be similar to that in DNA solution.     

Effect of light and temperature on the bleaching of the yellow mutant y-1 ofEuglena gracilis

Summary The yellow mutant y-1 ofEuglena gracilis, whose plastids are chlorophyll-deficient, is stable only in the dark and at suboptimal growth temperatures (below 26 C).At growth temperature of 30 C (in darkness) this strain is unstable and undergoes permanent bleaching. The process is enhanced by light so that bleaching may be increased up to 100 per cent. The degree of bleaching is proportional to light intensity.Bleaching is possible only during the active cell division. In the resting medium there is no bleaching, but total carotenoid synthesis is stimulated by illumination. At suboptimal growth temperature (26 C) the mutant is bleached only in the light, if light intensity exceeds 2,000 Lux. The results indicate that the process of bleaching in the yellow mutant is much more sensitive to temperature and light than in wild typeEuglena.     

Behavior of organelles and their nucleoids in the shoot apical meristem during leaf development in Arabidopsis thaliana L.

The behavior of organelle nucleoids and cell nuclei was studied in the shoot apical meristem and developing first foliage leaves of Arabidopsis thaliana. Samples were embedded in Technovit 7100 resin, cut into thin sections and stained with 4-6-diamidino-2-phenylindole to observe DNA. Fluorimetry was performed using a video-intensified microscope photon-counting system. The DNA content of individual mitochondria was more than 1 Mbp in the shoot apical meristem and the young leaf primordium, and decreased to approximately 170 kbp in the mature foliage leaf. In contrast, the DNA content of individual plastids was low in the shoot apical meristem and increased until day 7 after sowing. Application of 5-bromo-2-deoxyuridine, an analogue of thymidine, was usesd to investigate DNA synthesis in situ. The activities of DNA synthesis in the mitochondria and plastids changed according to the stage of development. Mitochondrial DNA was actively synthesized in the shoot apical meristem and young leaf primordia. This strongly suggests that the amount of mitochondrial DNA per mitochondrion, which has been synthesized in the shoot apical meristem and young leaf primordium, is gradually reduced due to continual divisions of the mitochondria during low levels of mitochondrial DNA synthesis. Synthesis of DNA in the plastid became active in the leaf primordia following DNA synthesis in the mitochondria, and the small plastids were filled with large plastid nucleotids. This enlargement of the plastid nucleoids occurred before the synthesis of ribulose-1,5-bisphosphate carboxylase/oxygenase and the development of thylakoids.Abbreviations BrdU 5-bromo-2-deoxyuridine - DAPI 4-6-diamidino-2-phenylindole - DiOC₆a 3,3-dihexyloxacarbocyanine - mtDNA mitochondrial DNA - mt-nucleoid mitochondrial nucleoid - ptDNA plastid DNA - pt-nucleoid plastid nucleoid - Rubisco ribulose-1,5-bisphosphate carboxylase/oxygenase This work was supported by grant No. 2553 to M.F. and Nos. 04454019, 03304005 and 06262204 to T.K. from the Ministry of Education, Science and Culture of Japan, and by a grant for a pioneering research project in biotechnology from the Ministry of Agriculture, Forestry and Fisheries of Japan.     

Interaction of cytochrome c L with methanol dehydrogenase from Methylophaga marina 42:

The reaction of methanol dehydrogenase with cytochrome c _L from Methylophaga marina and the reactions of the non-physiological substrates, Wurster's blue and ascorbic acid, with both proteins were studied as a function of temperature (4–32 °C), pressure (1–2000 bar) and ionic strength using the optical high pressure stopped-flow method. The thermodynamic parameters H, S and V were determined for all reactions where electron transfers are involved. These data allowed the determination of the Maxwell relationships which proved the internal thermodynamic consistency of the system under study. A conformational change on the cytochrome c _L level was deduced from both breaks in the Arrhenius plots and the variation of the V with temperature.Abbreviations MOPS 4-morpholinepropanesulfonic acid - CHES 2-(cyclohexylamino)ethanesulfonic acid - MDH methanol dehydrogenase - EDTA ethylenedinitrilotetraacetic acid disodium salt - BTB bromothymol blue (3,3-dibromothymolsulfoneph-thalein) - PQQ 2,7,9-tricarboxy-lH-pyrrolo-[2,3f]quinoline-4,5-dione - cytochrome c _HH mammalian horse heart cytochrome c     

Rhodopsin phosphorylation occurs at metarhodopsin II level

Photolyzed rhodopsin was phosphorylated in bovine rod outer segments incubated at –10 C. In the experiment in which urea-treated outer segments and rhodopsin kinase were incubated with ATP in the presence of 30% glycerol, the extent of phosphate incorporation at –10 C was about 30% of that at 37 C. Separation of phosphorylated rhodopsin by isoelectric focusing indicated that a limited number of sites were phosphorylated at –10 C. The partially phosphorylated pigment incorporated more phosphates when the temperatures was raised to 37 C. This was partly due to decreased inhibition of phosphorylation by glycerol at higher temperature. Since the maximum phosphorylation at –10 C (at which metarhodopsin II is stable) occurred at a pH value (6.0) lower than the pKa for metarhodopsin I-metarhodopsin II transition, metarhodopsin II was suggested to be the preferred substrate for rhodopsin kinase at –10 C. Limited proteolysis with thermolysin of rhodopsin phosphorylated at 37 C released peptides containing about 50% of the total phosphate incorporated. In contrast, proteolytic digestion of rhodopsin phosphorylated at –10 C released negligible amounts of phosphate-containing peptides. The results were taken to suggest that the incorporation of phosphates at metarhodopsin II level under the present condition occurred in the residues other than those removed by thermolysin digestion.Based on material presented at the Fifth International Congress of Eye Research, Eindhoven, October 1982     

Variations in mental performance under moderate cold stress

Effects of moderate cold stress on reasoning ability, associative learning and critical flicker frequncy of Indian subjects were studied by exposing them to 25C,. 20C, 15C and 10C for three hours. A second set of experiments was also conducted to confirm the conclusions of the first by using the same temperatures and duration of exposure. However, not only the sample used in the second case was larger and different but also the mental functions tested were numerical ability, running memory and mental alertness. It has been concluded that there is a significant impairment of simple cognitive functions at 15C which is 10C lower than their most comfortable temperature of 25C.     

The relative influence of urban climates on outdoor human energy budgets and skin temperature II. Man in an urban environment

Four typical urban neighborhoods or street canyon settings (including street parks) were simulated. These urban morphologies were exposed to typical summer and winter climatic scenarios for latitudes 10, 34, and 50N. The changes induced in the components of the human energy budget were examined. Resultant skin temperatures were compared with non-urban, unobstructed environments.     

Comparison of somatic and sexual incompatibility between Datura innoxia and Atropa belladonna

After protoplast fusion somatic hybrid calli were obtained by complementation selection between an albino mutant of Datura innoxia and the wildtype of Atropa belladonna (Krumbiegel and Schieder, 1979. Planta 145, 371–375). In the present study experiments are described concerning leaf and shoot induction on several media supplemented with different combinations and concentrations of hormones. Except for fleshy leaves and embryos, no well-formed shoot could be obtained. However, under standard culture conditions after one and a half years, one line produced numerous green shoots, showing a reduced number of chromosomes from Atropa belladonna. The loss of some chromosomes decreased the degree of somatic incompatibility. The additional appearance of shoots with albino sectors, of total albino shoots, and of green shoots showing a different phenotype, demonstrated that the elimination of the chromosomes occurred not only once, but several times. At least one shoot nearly stable in chromosome content and green subline could be obtained possessing only 6 chromosomes of Atropa belladonna and the original chromosome number of Datura innoxia. Experiments were carried out to test the feasibility of producing sexual hybrids through in vivo and in vitro methods by cross pollination. However, no embryos, seeds, or plantlets were obtained, thus demonstrating that protoplast fusion is the only possibility for obtaining hybrids between these two species.Abbreviations BAP 6-benzylaminopurine - 2,4-D 2,4-dichlor-phenoxyacetic acid - IAA indoleacetic acid - NAA -naphtaleneacetic acid - SDS sodiumdodecylsulfate     

Transport of rRNA into cytoplasm required for initiation of S phase in root meristem cells inHelianthus annuus L.

Summary Cold treatment (10C) of root meristem during a period longer than duration of the cell cycle in 20C causes a blocking of most cells in G₁. One of the causes of cell cycle blockade is the decrease of rRNA synthesis and inhibition of rRNA transport into cytoplasm. Transfer of seedlings to 20C results in increase of rRNA synthesis and its transport to cytoplasm as well as transition of almost all cells from G₁ to S during 3 hours. Synchronization of DNA replication, comprising cells within rows of cells, is preceded by similar transport patter of rRNA to cytoplasm.This work was supported by the Polish Academy of Sciences within the project 09.7.1.4.4.     

Effects of hyperthermia on enzymes and electrolytes in blood and cerebrospinal fluid in dogs

The effects of exposure to various degrees of heat stress on serum glutamate—oxaloacetate transaminase (SGOT), serum glutamate-pyruvate transaminase (SGPT), alkaline phosphatase (ALK-P-ase), calcium and chlorides have been studied on 75 dogs. Rectal temperature (T_re) was recorded before and after exposure to heat stress. These dogs were divided into 5 groups, according to the T_re level attained after exposure to heat stress. Rectal temperature was raised from normal to 39.45±0.47C in the first group, to 40.93±0.17C in the second group, to 41.87±0.22C in the third group, to 42.90 ± 0.21C in the fourth group and to 43.93±0.19C in the fifth group. The concentration of enzymes SGOT, SGPT and ALK-P-ase in blood and cerebrospinal fluid (CSF) increased significantly with hyperthermia. Calcium and chlorides concentrations in blood and in CSF tended to increase in hyperthermia. The integrity of the blood brain barrier for these enzymes and calcium is maintained under mild hyperthermia but it breaks down partially under influence of more severe hyperthermia. Core temperature above 41C results in damage to tissues and consequential rise of plasma enzymes. This degree of hyperthermia also seems to mark the beginning of injury to blood brain barrier. Critical core temperature tolerated by 50% of animals was 44C.     

Thermoregulation in the hippopotamus

Measurements of the sub-lingual temperature and of the skin temperature of the nose, ears, neck, dewlap, sides and back of two hippopotami (HIPPOPOTAMUS AMPHIBIUS L.) in the Zoological Park at Wroclaw have been made. The mean sub-lingual temperature was 36.1C but a diurnal rhythm of sub-lingual temperature was evident, which was not related to changes in the environmental temperature. The skin temperatures varied with the environmental temperature. When the animals were immersed in water at 9C the sub-lingual temperature dropped to 24.5C but it had returned to its pre-immersion value within one hour of leaving the water.

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Zusammenfassung Es wurden Messungen der Sublingualtemperatur und der Temperatur der Haut an Nase, Ohren, Nacken, Wamme, Seiten und Rücken von 2 Hippopotamus (HIPPOPOTAMUS AMPHIBUUS L.) im Zoologischen Garten in Warschau vorgenommen. Die mittl. Sublingualtemperatur war 36.1C. Ein diurnaler Rhythmus ohne Beziehung zu den Änderungen der Umwelttemperatur konnte nachgewiesen werden. Die Hauttemperatur Änderte sichmit der Umwelttemperatur. Wenn die Tiere im Wasserbecken (9C) standen,fiel die Sublingualtemperatur auf 24,5C. Sie stieg nach Verlassen des Wassers innerhalb einer Stunde auf den Ausgangswert.

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Resume La température sublinguale ainsi que les températures cutanées du nez,de l'oreille, de la nuque, du ventre, des flancs et du dos ont été relevées chez deux hippopotamus (HIPPOPOTAMUS AMPHIBIUS L.) du Jardin Zoologique de Varsovie. La température sublinguale moyenne a été de 36,1C. L'existence d'un rythme nycthéméral indépendant des variations de la température ambiante a été observée.La température cutanée varie en fonction de la température ambiante.Quand les animaux se tenaient debout dans leur bassin d'eau froide à 9C, la température sublinguale tombait à 24,5C.Lorsque les animaux quittaient ce bassin, cette température remontait au bout d'environ b heure à sa valeur de départ.

     

Body temperature responses of Savanna Brown goat to the harmattan and hot-dry season

Rectal and vaginal temperature responses of the Savanna Brown goat indigenous to the Nigerian guinea savanna were determined during the harmattan and the hot-dry season. Measurements were made at 06:00h and at 14:00h after 8h exposure to field conditions. At the 06:00h measurements during the harmattan, all animals were observed to shiver. A significant (P<0.01) positive correlation was found between rectal (T_re) and vaginal temperatures. During the harmattan, mean T_re was 38.2C at 06:00h and 39.7C at 14:00h; the mean difference, T_re was 1.5C. During the hot-dry season, T_re at 06:00h was 38.1C, and at 14:00h, 38.7; T_re was 0.6C. It is concluded that the harmattan is thermally more stressful than the hot-dry season and that passive thermolability may not be an important mechanism in the Savanna Brown goat in adaptation to thermal stress.     

Frostbite and the significance of a temperature-sensation scale in field and laboratory conditions

The literature indicates that rapid thawing in water between 42 and 45C provides the best prognosis for frostbitten limbs.A temperature:sensation scale for the normal hand was derived and tested in laboratory and field conditions. The scale permitted the preparation of water suitable for frostbite treatment by the majority of subjects without access to a thermometer. The maximum observed inaccuracy was 1.2C outside the preferred range but was well withing the safe range for treatment.

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Zusammenfassung Die beste Prognose zur Behandlung von Erfrierungen bietet nach den Erfahrungen in der Literatur das schnelle Auftauen von erfrorenen Gliedern bei Wassertemperaturen von 42–45C. Für die gesunde Hand wurde eine Temperatur-Wahrnehmungsskala aufgestellt und unter verschiedenen Bedingungen im Laboratorium und im Freien geprüft. Ohne Zugang zu einem Thermometer gestattete die Skala in der Mehrzahl der FÄlle die ErwÄrmung von Wasser auf Temperaturen, die für die Behandlung von Erfrierungen geeignet sind. Die grösste Ungenauigkeit zwischen SchÄtzwert und Thermometerwert war 1.2C ausserhalb des gewünschten aber noch innerhalb des für die Behandlung zulÄssigen Bereiches.

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Résumé D'après les indications de plusieurs auteurs, le meilleur traitement de membres gelés consiste à les dégeler dans de l'eau à une temperature entre 42 et 45C. Une échelle température-sensation pour la main normale a été mise au point et vérifiée au laboratoire ainsi qu'en plain air.Cette méthode a permis la préparation d'eau en vue d'un traitement de gelures sans faire usage d'un thermomètre dans la plupart des cas. L'erreur maximum observée était de 1,2 C sans que les limites de l'intervalle propice à un traitement ne soient jamais dépassées.

     

The effect of ambient temperature on diurnal rhythm in heat production and activity in pigs kept in groups

The effect of ambient temperature on diurnal rhythm of metabolic rate and activity was studied in group housed pigs in two trials. Two climate controlled respiration chambers were used, one for each trial. Each chamber contained two groups of 8 pigs. During the experiment of 31 days the mean live weight of the animals increased from 28 to 40 kg. Feeding level was kept constant at 93 kg^–0.75. d^–1. Feed contained 12 kJ of metabolizable energy per g. Temperature treatment started with 20C for two days. After that it was lowered in stepwise fashion by 4K to 16, 12 and 8C. Each temperature treatment lasted two days. After that temperature it was increased in steps to 20C in 8 days. The whole procedure was repeated once. Metabolic rate and activity were measured continuously during the 24 hrs of every second day of the temperature treatment.Metabolic rate increased at temperatures below 16C. Activity was associated with ambient temperature. At low temperature, the total activity related heat production was increased, especially during day time. Variation in metabolic rate within a day was not reduced by low ambient temperature. Thermal requirement, calculated as lower critical temperature, was about 14C as averaged over the day, (16.1C during day time and 13.6C during night time). Extra thermal heat production below thermoneutrality was affected by time of day and activity.     

Variations cardio-respiratoires et metaboliques à l'effort sous-maximal (P=40% Pmax) et maximal (Vita Max) en conditions thermiques froide (0‡C) et neutre (20‡C)

Resume Cette étude a pour but d'étudier les variations physiologiques et métaboliques tant au repos, qu'au cours d'efforts physiques de longue durée (2h) à 40% de la puissance maximale et d'efforts exhaustifs dans des conditions d'hypothermie ambiante (0C) en comparaison de valeurs recueillies en conditions thermiques neutres (20C). L'ensemble des épreuves furent exécutées en chambre climatique par: d'une part 11 sujets mâles pour l'effort exhaustif et d'autre part 8 sujets mâles pour l'exercice sous-maximal. Nous avons observé une légère bradycardie à 0C pour nos deux groupes à la fin de l'effort. La VO₂ et la ventilation pulmonaire sont plus élevées à 0C lors de l'effort maximal, nous observons toutefois le phénomène inverse lors de l'exercice sousmaximal. Les concentrations plasmatiques en acide lactique sons moins élevées et les bicarbonates plus élevés en ambiance thermique froide pour les deux conditions expérimentales. Le pH et la température rectale demeurent stables. Le RQ ne présente pas de différences significatives à la fin de chacun des deux efforts à 20C et 0C.

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The purpose of this study is to investigate the responses on cardiorespiratory and metabolic level measured at rest, during a long-term (2 h) submaximal exercise (P=40% Pmax) and during an exhaustive exercise (Vita Max) and recovery time in normal (20C) and in hypothermic (0C) conditions. The ergometric exercises were performed by 11 male subjects (Vita Max) and 8 male subjects (submaximal exercise) in a climatic room. We have observed a slight but mostly not significant (P<.05) bradycardia for both groups at the end of the exercise. VO₂ and pulmonary ventilation are higher at the end of the maximal exercise performed at 0C, this phenomenon is reversed for the submaximal exercise. The lactate concentrations are lower at 0C. For the same temperature the bicarbonates are higher. pH and T rect are not different in both experimental conditions and RQ is not significantly affected by temperature variations.