Hematocrit and hemoglobin levels in some peruvian rodents from high and low altitude

Hematocrit levels in highland (3900–4500 m) AKODON (4 species) showed no change following a month at sea level, but showed a reduction of about 50 ml/1 after an additional 1–2 months. Feral MUS established at 4500 m had more cells(570 vs.470 ml/l) than those from sea level; about half this advantage was lost after a week at sea level. Highland species or races showed no consistent advantage in erythrocyte level over lowland species. The lowland PHYLLOTIS DARWINII LIMATUS actually had a higher hematocrit than any of the highland PHYLLOTIS. Mean cell hemoglobin concentrations ranged from 28 to 33 g/100 ml in rodents, and to 42 g/100 ml in the alpaca.Mean cell volumes ranged from 44 to 65 3 in rodents, and were 25–263 for the alpaca and vicna. The cell hemoglobin mass varied from 13 to 18 g in rodents and was 11.5g in the alpaca and vicuña. None of these values for rodents appear remarkable.

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Zusammenfassung Die HÄmatokrit-Werte von 4 Arten Hochland-AKODON (3900–4500 m) zeigten nach einem Monat Aufenthalt der Tiere auf Meereshöhe keine VerÄnderung; nach 2–3 Monaten waren die Werte 50 ml/l niedriger als der Vorwert. Wilde MUS in 4500 m Höhe hatten 570 ml und wilde MUS auf Meereshöhe 470 ml Erythrozyten/1 Blut. Wurden die Tiere aus der Höhe ins Tal gebracht, verschwand die HÄlfte des Unterschiedes innerhalb einer Woche. Die Erythrozyten-Werte von Hochland-Arten und -Rassen zeigten keine übereinstimmende überlegenheit über die von Tiefland-Arten. Tiefland PHYLLOTIS DARWINII LIMATUS hatten sogar einen höheren HÄmatokrit als Hochland PHYLLOTIS. In Hochland-Nagern betrug der mittlere Zell-HÄmoglobingehalt 28 bis 33 g/100 ml, in Alpaca bis 42 g/100 ml. Das mittlere Zellvolumen war bei Nagern 44–653 und beim Alpaca und Vivuna 25–263. Die Menge HÄmoglobin pro Zelle betrug 13–18g bei Nagern und 11-5g beim Alpaca und Vicuna. Die Werte bei Nagern im Hochland sind in keiner Weise bemerkenswert.

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Résumé Les valeurs hématocrites de 4 sortes d'AKODON de hautes terres (3000 – 4500 m) ne montraient pas de changement après un mois de séjour des animaux au niveau de la mer; après 2–3 mois, les valeurs étaient 50 ml/l plus basses que la valeur précédante. A 4500 m d'altitude les MUS sauvages avaient 570 ml érythrocytes/l sang et au niveau de la mer 470 ml. Les animaux transportés de l'altitude dans la vallée, la moitié de la différence disparut au bout d'une semaine.Les valeurs d'erythrocytes de sortes et rasses de hautes terres ne montraient point de supériorité concordante aux sortes de basses terres. PHYLLOTIS DARWINI LIMATUS de basses terres avaient mÊme un hématocrit plus haut que le PHYLLOTIS de hautes terres. Le contenu moyen de l'hémoglobine cellulaire des rongeurs de hautes terres était de 28 à 33/100 ml,chez Alpaca jusqu'à 429/100 ml. Aux rongeurs, la volume cellulaire moyenne,était 44–653et Alpaca et Vicuna avaient 25–263. Les rongeurs avaient une quantité d'hémoglobine par cellule de 13–18g, les Alpaca et Vicuna avaient 11,5g. Les valeurs aux rongeurs ne sont remarquable en aucun égard.

     

The effect of sulfide on the blue-green algae of hot springs II. Yellowstone National Park

In the Mammoth Springs (Yellowstone National Park) waters with near neutral pH and soluble sulfide (H₂S, HS^–, S^2–) of over 1–2 mg/liter (30–60M) are characterized by substrate covers of phototrophic bacteria (Chloroflexus and aChlorobium-like unicell) above 50C and by a blue-green alga (Spirulina labyrinthiformis) below this temperature.Synechococcus. Mastigocladus, and other blue-green algae typical of most hot springs of western North America are excluded, apparently by sulfide. The sulfide-adaptedSpirulina photosynthesized at maximum rates at 45C and at approximately 300 to 700Ein/m²/sec of visible radiation. Sulfide (0.6–1.2 mM) severely poisoned photosynthesis of nonadapted populations, but those continuously exposed to over 30M tolerated at least 1 mM without inhibition. A normal¹⁴C-HCO₃ photoincorporation rate was sustained with 0.6–1 mM sulfide in the presence of DCMU (7M) or NH₂OH (0.2 mM), although both of these photosystem II inhibitors prevented photoincorporation without sulfide. Other sulfur-containing compounds (S₂O₃ ^2– SO₃ ^2–, S₂O₄ ^2– thioglycolic acid cysteine) were unable to relieve DCMU inhibition. The lowering of the photoincorporation rate by preferentially irradiating photosystem I was also relieved by sulfide. The most tenable explanation of these results is that sulfide is used as a photo-reductant of CO₂, at least when photosystem II is inhibited. It is suggested that in some blue-green algae photosystem II is poisoned by a low sulfide concentration, thus making these algae sulfidedependent if they are to continue photosynthesizing in a sulfide environment. Presumably a sulfidecytochrome reductase enzyme system must be synthesized for sulfide to be used as a photo-reductant.     

The native F0F1-inhibitor protein complex from beef heart mitochondria and its reconstitution in liposomes

A functional F₀F₁ ATP synthase that contains the endogenous inhibitor protein (F₀F₁I) was isolated by the use of two combined techniques [Adolfsen, R., McClung, J.A., and Moudrianakis, E. N. (1975).Biochemistry 14, 1727–1735; Dreyfus, G., Celis, H., and Ramirez, J. (1984).Anal. Biochem. 142, 215–220]. The preparation is composed of 18 subunits as judged by SDS-PAGE. A steady-state kinetic analysis of the latent ATP synthase complex at various concentrations of ATP showed aV _max of 1.28mol min^–1 mg^–1, whereas theV _max of the complex without the inhibitor was 8.3mol min^–1 mg^–1. In contrast, theK _m for Mg-ATP of F₀F₁ I was 148M, comparable to theK _m value of 142M of the F₀F₁ complex devoid of IF₁. The hydrolytic activity of the F₀F₁I increased severalfold by incubation at 60C at pH 6.8, reaching a maximal ATPase activity of 9.5mol min^–1 mg^–1; at pH 9.0 a rapid increase in the specific activity of hydrolysis was followed by a sharp drop in activity. The latent ATP synthase was reconstituted into liposomes by means of a column filtration method. The proteoliposomes showed ATP-Pi exchange activity which responded to phosphate concentration and was sensitive to energy transfer inhibitors like oligomycin and the uncouplerp-trifluoromethoxyphenylhydrazone.     

Cytochromes in Thiobacillus tepidarius and the respiratory chain involved in the oxidation of thiosulphate and tetrathionate

Thiobacillus tepidarius was shown to contain cytochrome(s) c with absorption maxima at 421, 522 and 552 nm in room temperature reduced minus oxidized difference spectra, present at 1.1–1.2 nmol per mg dry wt and present in both membrane and soluble fractions of the cell. The membrane-bound cytochrome c (1.75 nmol per mg membrane protein) had a midpoint potential (E_m, pH 7.0) of 337 mV, while the soluble fractions appeared to contain cytochrome(s) c with E_m (pH 7.0) values of about 270 and 360 mV. The organism also contained three distinct membrane-bound b-type cytochromes (totalling 0.33 nmol per mg membrane protein), each with absorption maxima in reduced minus oxidized difference spectra at about 428, 532 and 561 nm. The E_m (pH 7.0) values for the three cytochromes b were 8 mV (47.8% of total), 182 mV (13.7%) and 322 mV (38.5%). No a- or d-type cytochromes were detectable spectrophotometrically in the intact organism or its membrane and soluble fractions. Evidence is presented for both CO-binding and CO-unreactive cytochromes b or o, and CO-binding cytochrome(s) c. From redox effects observed with CO it is proposed that a cytochrome c donates electrons to a cytochrome b, and that a high potential cytochrome b or o may be acting as the terminal oxidase in substrate oxidation. This may be the 445 nm pigment, a photodissociable CO-binding membrane haemoprotein. Substrate oxidation was relatively insensitive to CO-inhibition, but strongly inhibited by cyanide and azide. Thiosulphate oxidation couples directly to cytochrome c reduction, but tetrathionate oxidation is linked (probably via ubiquinone Q-8) to reduction of a cytochrome b of lower potential than the cytochrome c. The nature of possible electron transport pathways in Thiobacillus tepidarius is discussed. One speculative sequence is: c^– b₈ b₁₈₂ c₂₇₀ c₃₃₇ b₃₂₂/c₃₆₀ O₂ Abbreviations E_m midpoint electrode potential - E _inf0 ^sup pH 7, standard electrode potential at pH 7.0 - Q-8 coenzyme Q-8 (ubiquinone-40)     

Upper limit on translational diffusion of visual pigment in intact unfixed barnacle photoreceptors

Translational diffusion of pigment molecules in the disc membranes of amphibian rod outer segments is in the range of 10 /10 s. Recently, Goldsmith and Wehner set an upper limit of 10 /20 min to the diffusion in isolated formaldehyde-fixed rhabdoms of crayfish. We have now used the early receptor potential (ERP) to study the diffusion in intact, unfixed barnacle photoreceptors. The ERP from a cell fully adapted to blue light (most of the pigment in the rhodopsin state) was changed by 8–22% of its maximum change when the pigment in a 30 m spot was (almost) completely shifted to the metarhodopsin state by red laser adaptation. Further red illumination of the same spot 30 min later produced only a limited further change in the ERP (attributable to light scatter), showing that R had not migrated into the spot. It is concluded that the visual pigment diffuses by less than 30 /30 min.Based on material presented at the European Neurosciences Meeting, Florence, September 1978     

On the question of the identity of cytochrome b-560 in thylakoid stromal membranes

Stromal membranes enriched in PS I contain a low potential cytochrome with a reduced -band peak close to 560 nm. The identity of this cytochrome component has been ascribed either to a low potential form of the Photosystem II cytochrome b-559 or to a different cytochrome with a reduced -band of 560 nm. The half-bandwidth of the 560 nm component in stromal membranes is identical to that of purified cytochrome b-559. Western blots show that the stromal membranes contain an amount of PS II cytochrome b-559 -subunit that is more than sufficient to account for the cytochrome b-560 detected spectrophotometrically in these membranes. These immunochemical data and the similarity of (i) the spectral peaks, and (ii) the redox properties of low potential PS II cytochrome b-559 and the b-560 component, suggest that the simplest inference is that the cytochrome b-560 protein in stromal membranes is identical to the PS II cytochrome b-559.Abbreviations: A absorbance - cyt cytochrome - DCBQ 2,5-dichloro-p-benzoquinone - E_mx midpoint potential at pH x - hbw half-bandwidth - LP low potential - MD menadiol - MES 2-(N-morpholino)ethanesulfonic acid - MHQ methylhydroquinone - PS I-PS II photosystems I, II - SDS-PAGE sodium dodecylsulfate polyacrylamide gel electrophoresis     

Mechanisms for controlling balance between light input and utilisation in the salt tolerant alga Dunaliella C9AA

The yield of photosynthetic O₂ evolution was measured in cultures of Dunaliella C9AA over a range of light intensities, and a range of low temperatures at constant light intensity. Changes in the rate of charge separation at Photosystem I (PS I) and Photosystem II (PS II) were estimated by the parameters _{PS I} and _{PS II} . _{PS I} is calculated on the basis of the proportion of centres in the correct redox state for charge separation to occur, as measured spectrophotometrically. _{PS II} is calculated using chlorophyll fluorescence to estimate the proportion of centres in the correct redox state, and also to estimate limitations in excitation delivery to reaction centres. With both increasing light intensity and decreasing temperature it was found that O₂ evolution decreased more than predicted by either _{PS I} or _{PS II}. The results are interpreted as evidence of non-assimilatory electron flow; either linear whole chain, or cyclic around each photosystem.Abbreviations F₀ dark level of chlorophyll fluorescence yield (PS II centres open) - F_m maximum level of chlorophyll fluorescence yield (PS II centres closed) - F_v variable fluorescence (F_m-F₀) - PS I Photosystem I - PS II Photosystem II - P₇₀₀ reaction centre chlorophyll(s) of PS I - q_N coefficient of non-photochemical quenching of chlorophyll fluorescence - q_P coefficient of photochemical quenching of fluorescence yield - q_E high-energy-state quenching coefficient - _{PS I} yield of PS I - _{PS II} yield of PS II - _S yield of photosynthetic O₂ evolution - _P intrinsic yield of open PS II centres     

Interspecific variation in the visual pigments of deep-sea fishes

Summary Visual pigments in the rods of 38 species of deep-sea fish were examined by microspectrophotometry. 33 species were found to have a single rhodopsin with a wavelength of maximum absorbance ( _max) in the range 470–495 nm. Such visual pigments have absorbance maxima close to the wavelengths of maximum spectral transmission of oceanic water. 5 species, however, did not conform to this pattern and visual pigments were found with _max values ranging from 451 nm to 539 nm. In 4 of these species two visual pigments were found located in two types of rod. Some 2-pigment species which have unusual red sensitivity, also have red-emitting photophores. These species have both rhodopsin and porphyropsin pigments in their retinae, which was confirmed by HPLC, and the two pigments are apparently located in separate rods in the same retinal area. In deep-sea fishes the occurrence of unusual visual pigments seems to be correlated with aspects of the species' depth ranges. In addition to ecological influences we present evidence, in the form of _max spectral clustering, that indicates the degree of molecular constraint imposed on the evolution of visual pigments in the deep-sea.     

Inheritance of mitochondrial DNA in lentil (Lens culinaris Medik.)

Restriction fragment analysis was used to examine the inheritance of lentil mitochondrial DNA (mtDNA) in F₁ and F₅ progeny from intrasubspecific (Lens culinaris ssp. culinaris) crosses and in F₁ progeny from intersubspecific (Lens culinaris ssp. orientalis x L. culinaris ssp. culinaris) crosses. Southern blots of digested parental and progeny DNA were hybridized to heterologous maize mtDNA probes specific to coxI and atp6 genes. Two restriction fragment polymorphisms separated L.c. ssp. culinaris Laird and Eston from L.c. ssp. culinaris ILL5588, and one restriction fragment polymorphism distinguished L.c. ssp. culinaris Laird and Eston from L.c. ssp. orientalis LO4. Twelve of 13 f₁ progeny and all F₅ progeny from the intrasubspecific crosses, and all F₁ progeny from intersubspecific crosses had only maternal mtDNA restriction fragments. One f₁ plant from an Eston x ILL5588 cross inherited mtDNA fragments from both parents. Nuclear DNA inheritance was biparental in all F₁ progeny.NRCC No. 38451     

Synthetic substrate analogues for UDP-GlcNAc: Manα1-6R β(1-2)-N-acetylglucosaminyltransferase II. Substrate specificity and inhibitors for the enzyme

UDP-GlcNAc: Man1-6R (1-2)-N-acetylglucosaminyltransferase II (GlcNAc-T II; EC 2.4.1.143) is a key enzyme in the synthesis of complexN-glycans. We have tested a series of synthetic analogues of the substrate Man1-6(GlcNAc1-2Man1-3)Man-O-octyl as substrates and inhibitors for rat liver GlcNAc-T II. The enzyme attachesN-acetylglucosamine in 1-2 linkage to the 2-OH of the Man1-6 residue. The 2-deoxy analogue is a competitive inhibitor (K _i=0.13mm). The 2-O-methyl compound does not bind to the enzyme presumably due to steric hindrance. The 3-, 4- and 6-OH groups are not essential for binding or catalysis since the 3-, 4- and 6-deoxy and -O-methyl derivatives are all good substrates. Increasing the size of the substituent at the 3-position to pentyl and substituted pentyl groups causes competitive inhibition (K _i=1.0–2.5mm). We have taken advantage of this effect to synthesize two potentially irreversible GlcNAc-T II inhibitors containing a photolabile 3-O-(4,4-azo)pentyl group and a 3-O-(5-iodoacetamido)pentyl group respectively. The data indicate that none of the hydroxyls of the Man1-6 residue are essential for binding although the 2- and 3-OH face the catalytic site of the enzyme. The 4-OH group of the Man-O-octyl residue is not essential for binding or catalysis since the 4-deoxy derivative is a good substrate; the 4-O-methyl derivative does not bind. This contrasts with GlcNAc-T I which cannot bind to the 4-deoxy-Man- substrate analogue. The data are compatible with our previous observations that a bisectingN-acetylglucosamine at the 4-OH position prevents both GlcNAc-T I and GlcNAc-T II catalysis. However, in the case of GlcNAc-T II, the bisectingN-acetylglucosamine prevents binding due to steric hindrance rather than to removal of an essential OH group. The 3-OH of the Man1-3 is an essential group for GlcNAc-T II since the 3-deoxy derivative does not bind to the enzyme. The trisaccharide GlcNAc1-2Man1-3Man-O-octyl is a good inhibitor (K _i=0.9mm). The above data together with previous studies indicate that binding of the GlcNAc1-2Man1-3Man- arm of the branched substrate to the enzyme is essential for catalysis. Abbreviations: GlcNAc-T I, UDP-GlcNAc:Man1-3R (1-2)-N-acetylglucosaminyltransferase I (EC 2.4.1.101); GlcNAc-T II, UDP-GlcNAc:Man1-6R (1-2)-N-acetylglucosaminyltransferase II (EC 2.4.1.143); MES, 2-(N-morpholino)ethane sulfonic acid monohydrate.     

Initial characterization of autoprocessing and active-center mutants of CMV proteinase

Human cytomegalovirus (CMV) encodes a unique serine proteinase that is required in the maturation of the viral capsid. The CMV proteinase can undergo autocatalytic activation and is subject to proteolytic self-inactivation. Mutant enzyme forms were prepared to eliminate the initial autoprocessing site and thus form an active single-chain protein for structure-function studies. Two mutants of CMV proteinase were cloned and expressed inEscherichia coli. The A143V mutant was a conservative substitution at the first internal cleavage site. The S132A mutant modified one of the triad of residues responsible for catalytic activity. Through the use of computer-controlled high-cell-density fermentations the mutant proteins were expressed inE. coli at 170mg/L as both soluble (40% of total) and inclusion-body forms (60% of total). The soluble enzyme was purified by standard methods; inclusion-body protein was isolated by standard methods after refolding and solubilization in guanidine or urea. Sedimentation equilibrium and sedimentation velocity analyses reveal that the enzyme undergoes concentration-dependent aggregation. It exhibits a monomerdimer equilibrium (K _d =1M) at low concentrations and remains dimeric at high concentrations (28 mg/ml). Differential scanning calorimetry data for protein thermal unfolding fit best to a non-two-state model with two components (T _m =52.3 and 55.3c) which subsequently aggregate upon unfolding. Analysis of the short-UV circular dichroism spectra of protein forms resulting from expression as soluble molecules (not refolded) reveals that the two mutants have very similar secondary structures which comprise a mixed structural motif of 20%-helix, 26%-sheet, and 53% random coil. Though soluble and active (A143V mutant only), CD analysis revealed that protein refolded from inclusion bodies did not exhibit spectra identical to that of protein expressed only in soluble form.     

Histological localization of citrus infectious variegation virus (CVV) inPhaseolus vulgaris

Summary Ultrathin sections ofPhaseolus vulgaris leaves were studied in the electron microscope. The leaves were taken from plants, both healthy and experimentally infected with CVV. The sieve tubes and companion cells of all samples contained a slime-like substance, more or less organized into compact systems. In the mature sieve elements of virus-infected plants systems of parallel membranes were seen along which spherical particles, of about 30 m diameter, were aligned in simple rows.Pubbl No. 117 of Gruppo di Ricerca per le Virosi, del C. N. R.     

Fluorescence studies on interaction between phospho-LHC II and subchloroplast Photosystem 1 preparations

Chloroplast proteins were phosphorylated under two test conditions: white light irradiance alone and white light irradiance with the addition of glucose and glucose oxidase, used to produce an anaerobic medium. The interaction of phospho-LHC II with Photosystem 1 (PS 1) was studied for two types of PS I preparation. Changes in the chlorophyll a/b ratio and the ratio of 650 and 680 nm band intensities (E650/E680) in fluorescence excitation spectra were used in calculating the phospho-LHC II portion which became associated with PS 1. It is shown that the associated portion of phospho-LHC II varies for each of the PS 1 preparations and phosphorylation procedures. Possible conclusions as regards the transfer of various sets of LHC II subpopulations under different phosphorylation procedures and the differences of interaction with PS 1 are discussed.Abbreviations PS 1 Photosystem 1 - PS 2 Photosystem 2 - LHC II light-harvesting chlorophyll a/b protein complex II - Chl chlorophyll - fluorescence quantum yield - _f life time of fluorescence at =685 nm - F735 fluorescence band with a maximum at 735 nm - F685 fluorescence band with a maximum at 685 nm - E650/E680 ratio of amplitudes in excitation fluorescence spectrum at 650 and 680 nm     

Identification of two RAPD markers tightly linked with the Nicotiana debneyi gene for resistance to black root rot of tobacco

Linkage of randomly amplified polymorphic DNA (RAPD) markers with a single dominant gene for resistance to black root rot (Chalara elegans Nag Raj and Kendrick; Syn. Thielaviopsis basicola [Berk. and Broome] Ferraris) of tobacco (Nicotiana tabacum L.), which was transferred from N. debneyi Domin, was investigated in this study. There were 2594 repeatable RAPD fragments generated by 441 primers on DNAs of Delgold tobacco, a BC₅F₈ near isogenic line (NIL) carrying the resistance gene in a Delgold background, and PB19, the donor parent of the resistance gene. Only 7 of these primers produced eight RAPD markers polymorphic between Delgold and PB19, indicating there are few RAPD polymorphisms between them despite relatively dissimilar pedigrees. Five of the eight RAPD markers were not polymorphic between Delgold and the NIL. All of these markers proved to be unlinked with the resistance gene in F₂ linkage tests. Of the remaining three RAPD markers polymorphic between Delgold and the NIL, two were shown to be strongly linked with the resistance gene; one in coupling and the other in repulsion. Application of the two RAPDs in the elimination of linkage drag associated with the N. debneyi resistance gene and marker-assisted selection for the breeding of new tobacco cultivars with the resistance gene is discussed.     

Inhibition by trifluoperazine of ATP synthesis and hydrolysis by particulate and soluble mitochondrial F1: Competition with H2PO 4 −

The effect of trifluoperazine (TFP) on the ATPase activity of soluble and paniculate F₁ATPase and on ATP synthesis driven by succinate oxidation in submitochondrial particles from bovine heart was studied at pH 7.4 and 8.8. At the two pH. TFP inhibited ATP hydrolysis. Inorganic phosphate protected against the inhibiting action of TFP. The results on the effect of various concentrations of phosphate in the reversal of the action of TFP on hydrolysis at pH 7.4 and 8.8 showed that H₂PO ₄ ^– is the species that competes with TFP. The effect of TFP on oxidative phosphorylation was studied at concentrations that do not produce uncoupling or affect the aerobic oxidation of succinate (<15M). TFP inhibited oxidative phosphorylation to a higher extent at pH 8.8 than at pH 7.4; this was through a diminution in theV _max, and an increase in theK _m for phosphate. Data on phosphate uptake during oxidative phosphorylation at several pH showed that H₂PO ₄ ^– is the true substrate for oxidative phosphorylation. Thus, in both synthesis and hydrolysis of ATP, TFP and H₂PO ₄ ^– interact with a common site. However, there is a difference in the sensitivity to TFP of ATP synthesis and hydrolysis; this is more noticeable at pH 8.8, i.e. ATPase activity of soluble F₁ remains at about 40% of the activity of the control in a concentration range of TFP of 40–100M, whereas in oxidative phosphorylation 14M TFP produces a 60% inhibition of phosphate uptake.     

The effect of humidity and light on cellular water relations and diffusion conductance of leaves ofTradescantia virginiana L.

Turgor (_p) and osmotic potential (_s) in epidermal and mesophyll cells, in-situ xylem water potential (-xyl) and gas exchange were measured during changes of air humidity and light in leaves ofTradescantia virginiana L., Turgor of single cells was determined using the pressure probe. Sap of individual cells was collected with the probe for measuring the freezing-point depression in a nanoliter osmometer. Turgor pressure was by 0.2 to 0.4 MPa larger in mesophyll cells than in epidermal cells. A water-potential gradient, which was dependent on the rate of transpiration, was found between epidermis and mesophyll and between tip and base of the test leaf. Step changes of humidity or light resulted in changes of epidermal and mesophyll turgor (_p-epi, _p-mes) and could be correlated with the transpiration rate. Osmotic potential was not affected by a step change of humidity or light. For the humidity-step experiments, stomatal conductance (g) increased with increasing epidermal turgor.g/_p-epi appeared to be constant over a wide range of epidermal turgor pressures. In light-step experiments this type of response was not found and stomatal conductance could increase while epidermal turgor decreased.Symbols E transpiration - g leaf conductance - w leaf/air vapour concentration difference - -epi water potential of epidermal cells - -mes water potential of mesophyll cells - -xyl water potential of xylem - _p-epi turgor pressure of epidermal cells - _p-mes turgor pressure of mesophyll cells - _s-epi osmotic potential of epidermal cells - _s-mes osmotic potential of mesophyll cells     

Polytene chromosomes of Simulium craigi (Diptera: Simuliidae)

Simulium craigi Adler and Currie is a polymorphic species based on polytene chromosome banding patterns in the long arm of chromosome III (IIIL). Three cytotypes are described based on the predominant IIIL sequences. These correspond to three broad geographic areas: cytotype CC from Pennsylvania; cytotype AF from Ontario and Manitoba; and cytotype ACF/BCF from New Hampshire. In the absence of sympatric populations, these cytotype differences are best explained by clinal variation within a single species. The relationship of S. craigi to other described members of the S. vernum group is discussed.     

A comparative study of the responsivity of Sinapis alba L. seedlings to pulsed and continuous irradiation

Anthocyanin formation in 36h dark grown Sinapis alba L. seedlings and inhibition of hypocotyl elongation in 36h and 54h dark grown and 54h and 7 day light grown seedlings in response to continuous red light could be substituted for by hourly 5 min light pulses where the total fluence over the irradiation period is the same. These pulses are partially (36h) or almost totally (54h and 7 day) reversible by subsequent far-red (RG 9) light pulses. In contrast to 654 nm light, hourly light pulses with 552 nm, 449 nm and 715 nm can at best only partially substitute for continuous irradiation. These data are discussed with respect to the commonly used models for the phytochrome high irradiance response.Abbreviations P_tr tar-red absorbing form of phytochrome - SAN 9789 4-chloro-5-(methyl-amino)-2-(,,-trifluoro-m-tolyl)-3(2H)-pyridazinone=Norflurazon - HIR High irradiance response     

Cytochromes of the non-thiosulfate-utilizing green sulfur bacterium Chlorobium limicola

Flavocytochrome c-553 of the non-thiosulfateutilizing green sulfur bacterium Chlorobium limicola strain 6330 was partially purified by ion exchange column chromatography and ammonium sulfate fractionation (highest purity index obtained: A ₂₈₀/A _{417 red}=0.96). It is autoxidizable and located in the soluble fraction. This hemoprotein contains a flavin component and one heme per molecule. The dithionite reduced spectrum reveals the typical maxima of a c-type cytochrome: =553,5 nm; =523 nm; =417 nm, while the oxidized form shows a -band at 410 nm and two shoulders at 440 nm and 480 nm indicating the flavin component. The flavocytochrome is a basic protein with an isoelectric point at pH 9.0 (± 0.5), a redox potential of 65 mV, a molecular weight of 56,000. It participates in sulfide oxidation and shows neither adenylylsulfate reductase nor sulfite reductase activity. C. limicola further contains a soluble cytochrome c-555 (highest purity index obtained: A ₂₈₀/A _{412 ox}=0.13; isoelectric point between pH 9.5 and 10) and the non-heme iron-containing proteins rubredoxin and ferredoxin, but lacks cytochrome c-551. Besides these soluble electron transfer proteins a membrane-bound c-type cytochrome (=554,5 nm) can be detected spectrophotometrically.Non-common abbreviations HIPIP high-potential iron sulfur protein - APS adenylylsulfate