Purification and initial characterization of phycobiliproteins from the endophytic cyanobacterium of Azolla

The endophytic cyanobacterium, Anabaena azollae, isolated from laboratory cultures of Azolla caroliniana Willd., contains three spectroscopically distinct biliproteins. About 70% of the biliprotein is c-phycocyanin (_max 610 nm) and 13% is allophycocyanin (_max 647 nm, shoulder 620 nm). A third pigment corresponds to phycoerythrocyanin (_max 570 nm, shoulder 590 nm). In very dilute solutions of allophycocyanin, at constant pH and buffer strength, the 647 nm maximum disappears and a single _max occurs at 615–620 nm. The 647 nm absorption maximum reappears upon concentrating the dilute solution. Very dilute solutions of phycoerythrocyanin exhibit a broad peak between 570 and 590 nm. Absorption spectra of c-phycocyanin are not significantly altered upon dilution. Fluorescence emission maxima of phycoerythrocyanin, c-phycocyanin, and allophycocyanin occur at 630 nm, 643 nm and 660 nm respectively, using 540 nm excitation. Two subunits, of molecular weight 16,500 () and 20,600 (), are seen in c-phycocyanin upon dissociation with SDS. Dissociation of allophycocyanin and phycoerythrocyanin with SDS yields one sizeclass of subunits, with a molecular weight of about 17,500 for allophycocyanin and 18,000 for phycoerythrocyanin.Contribution No. 684 Offprint requests to: G. A. Peters     

Visual and lenticular pigments in the eyes of demersal deep-sea fishes

We report on the lens pigmentation and visual pigments of 52 species of demersal deep-sea fishes caught at depths ranging from 480 m to 4110 m in the Porcupine Seabight and Goban Spur area of the North-eastern Atlantic. Only one species, caught between 480 and 840 m, had a lens with large amounts of pigment, consistent with the hypothesis that heavily pigmented lenses in deep-sea fish serve to enhance the contrast of bioluminescent signals by removing much of the background radiance, which is only visible to fish living shallower than 1000 m. Low concentrations of lens pigmentation were also observed in a further two species (Rouleina attrita and Micromesisteus poutassou). The retinae of all species except five, contained only a single visual pigment, as determined by microspectrophotometry of individual rods, and/or spectrophotometry of retinal wholemounts and retinal extracts. Those fishes caught between 500 m and 1100 m had wavelengths of peak sensitivity (_max) ranging from 476 nm to 494 nm, while most fish living below 1100 m tended to be more conservative with (_max) values ranging from 475 nm to 485 nm. The only exceptions to this were three deep-living species caught between 1600 m and 2000 m whose retinae contain abnormally short-wave sensitive visual pigments (Cataetyx laticeps — _max 468 nm; Alepocephalus bairdii — _max 467 nm; Narcetes stomias _max 472 nm), suggesting adaptation for the detection of short-wave bioluminescence.     

Microspectrophotometry of the photoreceptors of palaeognathous birds — the emu and the tinamou

Summary With the aid of a microspectrophotometer the visual pigments and oil globules in the retina of the emu (Dromiceius novae-hollandiae), the brushland tinamou (Nothoprocta c. cinerascens) and the Chilean tinamou (Nothoprocta perdicaria sanborni) were characterized. All three of these palaeognathous birds contain in their rods a typical rhodopsin with _max near 500 nm. Each of these birds has cones containing iodopsin-like visual pigments with _max in the 560–570 nm spectral region. No unequivocal evidence was obtained for the presence of cone pigments other than this iodopsin-like pigment, although one cell thought to be a cone, and containing a visual pigment with _max near 498 nm, was observed in the retina of the brushland tinamou. The oil globule systems of the three palaeognathous species are identical to each other and are much simpler than is typical for neognathous birds in that only two different types of globule are present, one with _T50 at 508 nm and another with _T50 at 568 nm. Comparison of the data with observations made on neognathous species indicates (1) that palaeognathous birds probably have poorer color discrimination capabilities than neognathous birds and (2) that the tinamou is more closely related to the ratites than to the galliform species.This study was supported, in part, by NIH Grant No. EY01839 (A.J. Sillman), NIH Grant No. EY00323 (W.N. McFarland) and NSF Grant No. 78-07657 (E.R. Loew). The authors thank E. Clinite, R. Dunford, C. Murphy, R. Riis and D. Weathers for their valuable assistance. Thanks also go to R.E. Burger for his gift of the emus.     

Intracellular responses from the photosensitive pineal organ of the teleost,Phoxinus phoxinus

Summary Intracellular potentials from the isolated dark-adapted pineal organ ofPhoxinus phoxinus were recorded by using glass microelectrodes. The majority of cells had resting potentials of 20 to 35 mV and responded to light with intensitygraded hyperpolarizations. Voltage intensity curves of responses to brief flashes followed the hyperbolic tangent functionV/V _max=Iⁿ/(I ⁿ + ⁿ ).The latency of onset for responses to light stimuli near threshold was 400 ms and decreased with saturating flashes to about 50 ms. The membrane resistance decreased during the hyperpolarization. Spectral sensitivity measurements for these cells exhibited curves with _max=530 nm. Intracellular dye injection unequivocally identified this cell type as a photoreceptor cell.A second cell type with resting potentials between 30 to 40 mV exhibited a biphasic response pattern to light stimulation. The cell depolarized with dim light flashes and hyperpolarized with bright flashes. The amplitude of the hyperpolarizing component showed no saturation over an intensity range of 5 log units. Latencies and rise times were comparable to those of photoreceptor potentials. Spectral sensitivity curves peaked at longer wavelengths ( _max=550 nm) than the action spectra of photoreceptors ( _max=530 nm). It is assumed that this rare cell type represents a small class of pineal interneurons.     

Action spectra for changes in the “high irradiance reaction” in hypocotyls of Sinapis alba L.

Detailed action spectra are presented for the inhibition of hypocotyl extension in dark-grown Sinapis alba L. seedlings by continuous (24 h) narrow waveband monochromatic light between 336 nm and 783 nm. The results show four distinct wavebands of major inhibitory action; these are centred in the ultra-violet (_max=367 nm), blue (_max=446 nm), red (_max=653 nm) and far-red (_max=712 nm) wavebands. Previous irradiation of the plants with red light (which also decreases Ptot) causes decreased inhibitory action by all wavelengths except those responsible for the red light inhibitory response. Pre-irradiation did not alter the wavelength of the action maxima. It is concluded that ultra-violet and blue light act mainly on a photoreceptor which is different from phytochrome.Abbreviations B blue - D dark - FR far-red - HIR high irradiance reaction - HW half power bandwith - Pr R absorbing form of phytochrome - Pfr FR absorbing form of phytochrome - Ptot total phytochrome=Pr+Pfr - R red - UV ultra violet     

Optimal control of continuous fermentation processes

Three layer control structure is proposed for optimal control of continuous fermentation processes. The start-up optimization problems are solved as a first step for optimization layer building. A steady state optimization problem is solved by a decomposition method using prediction principle. A discrete minimum time optimal control problem with state delay is formulated and a decomposition method, based on an augmented Lagrange's function is proposed to solve it. The problem is decomposed in time domain by a new coordinating vector. The obtained algorithms are used for minimum time optimal control calculation of Baker's Yeast fermentation process.List of Symbols x(t) g/l biomass concentration - s(t) g/l limiting substrate concentration - x ⁰ g/l inlet biomass concentration - s ⁰(t) g/l inlet substrate concentration - D(t) h^–1 dilution rate - (t) h^–1 specific growth rate - Y g/g yield coefficient - (t) h^–1 specific limiting substrate consumption rate - k _D h^–1 disappearing constant - w ₁, w ₂ known constant or piece-wise disturbances - _m h^–1 maximum specific growth rate - k _s g/l Michaelis-Menten's parameter - h time delay - x ₀, s ₀ g/l initial concentrations - ¯x, ¯s, ¯D optimal steady state value - V _min , V _max , v=x,s,d,t bounds of variables - t h sampling period - K number of steps in the optimization horison - Js, J _d performance indexes - L _s Lagrange's function - L _d Lagrange's functional - ₀ weighting coefficient for the amount of the limiting substrate throwing out of the fermentor - ₁, ₂ dual variables of Lagrange's function - steps in steady state coordination procedure - errors values for steady state coordination process - _v , v=x, s conjugate variables of Lagrange's functional - _v , v=x,s penalty coefficients of augmented Lagrange's functional - _v , v=x, s interconnections of the time - e _v , v=x,s, D, _x , _s gradients of Lagrange's functional - j, l indexes of calculation procedures - values of errors in calculations The researches was supported by National Scientific Research Foundation under grants No NITN428/94 and No NITN440/94     

The photic environment and scotopic visual pigments of the creek chub,Semotilus atromaculatus and white sucker,Catostomus commersoni

Summary Scotopic visual pigments measured in the creek chub and the white sucker are porphyropsins with mean _max values located at 538.3 and 536.5 nm, respectively. There is a shift of the _max towards shorter wavelengths during the winter in both of these species coinciding with similar changes in the quality of downwelling light. _max is significantly correlated to the P₅₀ and spectrum width of the downwelling light and dissolved oxygen. An analysis of variance shows that there are significant differences between the _max values of: fish in the two lakes, fish at different times, the two species at different times and fish in different lakes at different seasons. The offset visual pigments of both species appear to be well adapted to their photic environment in terms of the contrast hypothesis. This improvement of contrast detection is discussed in relation to their feeding habits.Abbreviations _max wavelength at which absorbance is maximum - P₅₀ wavelength which halves the total number of photons between 400 and 700 nm, a measure of spectral quality - PAR photosynthetically active radiation - MSP microspectrophotometric - SE standard error     

Studies on the E. coli groNB (nusB) gene which affects bacteriophage lambda N gene function

Summary Escherichia coli mutants, called groNB, which block the growth of bacteriophage at the level of action of the gene N product, have been isolated as survivors at 42°C of bacteria carrying a) the defective prophage bio1 1 i cI857 H1 or b) the pcR1 plasmid containing the EcoRI immunity fragment of phage cI857. In addition, groNB bacterial mutants have been isolated at 37° C, as large colony formers in the presence of i cI h ⁴³⁴, i cI h , and i cI h ⁸⁰ phage. The groNB locus is located at 9 minute of the E. coli genetic map with the order of the neighboring loci being proC tsx groNB purE. Most groNB mutations isolated at 42° C were found to interfere in addition with bacterial growth at low temperatures, since (a) the GroNB phenotypes of growth inhibition and bacterial cold sensitivity cannot be separated by P1 transduction, and (b) some cold resistant revertants simultaneously become Gro⁺ for growth. Lambda transducing phages carrying the groNB ⁺ bacterial gene have been isolated. GroNB mutant bacterial lysogenized by the transducing phage acquire the Gro⁺ phenotype and simultaneously the cold resistant phenotype, suggesting that the groNB mutations are recessive to the wild-type gene.     

The spectral input systems of hymenopteran insects and their receptor-based colour vision

Summary Spectral sensitivity functions S() of single photoreceptor cells in 43 different hymenopteran species were measured intracellularly with the fast spectral scan method. The distribution of maximal sensitivity values (_max) shows 3 major peaks at 340 nm, 430 nm and 535 nm and a small peak at 600 nm. Predictions about the colour vision systems of the different hymenopteran species are derived from the spectral sensitivities by application of a receptor model of colour vision and a model of two colour opponent channels. Most of the species have a trichromatic colour vision system. Although the S() functions are quite similar, the predicted colour discriminability curves differ in their relative height of best discriminability in the UV-blue or bluegreen area of the spectrum, indicating that relatively small differences in the S() functions may have considerable effects on colour discriminability. Four of the hymenopteran insects tested contain an additional R-receptor with maximal sensitivity around 600 nm. The R-receptor of the solitary bee Callonychium petuniae is based on a pigment (P596) with a long _max, whereas in the sawfly Tenthredo campestris the G-receptor appears to act as filter to a pigment (P570), shifting its _max value to a longer wavelength and narrowing its bandwidth. Evolutionary and life history constraints (e.g. phylogenetic relatedness, social or solitary life, general or specialized feeding behaviour) appear to have no effect on the S() functions. The only effect is found in UV receptors, for which _max values at longer wavelengths are found in bees flying predominantly within the forest.     

Normal expression of the viral gene N interferes with growth of bacteriophage lambda in Escherichia coli 15T-.

Summary Growth of and of some lambdoid phages is considerably inhibited on strain 3057 derived from E. coli 15T^-. Mutants of which overcome this inhibition map in gene N. Some of these hty mutants are temperature sensitive for growth on E. coli K12. Thus plating of on strain 3057 allows one to isolate temperature sensitive N mutants. The hty mutants produce less than normal N activity as judged by their low efficiency of plating on a nus ^- host and by the extended latent period of some of them on normal hosts. The inability of strain 3057 to propagate can be at least partially reversed by addition of thymidine to the medium and the growth difference between hty and in 3057 increases with decreasing thymidine concentration. The amount of DNA produced by in 3057 at low thymidine concentration is lower than that produced by hty under the same conditions. Only a small percentage of the DNA produced by in 3057 is packaged into viable phage particles. This suggests that not only produces less DNA in 3057 than hty but that an important part of the DNA in 3057 is in a form which can not be packaged or which is noninfective for other reasons. A hypothesis is discussed that hty mutations enable to grow on E. coli 15T^- at low thymidine concentration because they lead to reduction in the number of single strand nicks in the DNA by reducing the intracellular endonuclease activity. Under permissive conditions conditional lethal N mutants are favored for growth on 3057 over N ⁺ which confirms the idea that N activity or the activity of a gene under N control interferes with growth in 3057 at low thymidine concentration.     

Intraspecific variation of spectral sensitivity in threespine stickleback (Gasterosteus aculeatus) from different photic regimes

To examine the influence of the spectral characteristics of underwater light on spectral sensitivity of the ON and OFF visual pathways, compound action potential recordings were made from retinal ganglion cells of threespine stickleback from different photic regimes. In fish from a red-shifted photic regime (P₅₀ 680 nm for downwelling light at 1m), peak sensitivity of both the ON and OFF pathways was limited to long wavelength light (_max 600–620). In contrast, the ON pathway of fish from a comparatively blue-shifted (P₅₀ 566 nm) photic regime exhibited sensitivity to medium (_max 540–560) and long (_max 600 nm) wavelengths, while the OFF pathway exhibited peak sensitivity to only medium (_max 540 nm) wavelength light. In a third population, where the the ambient light is moderately red-shifted (P₅₀ 629 nm), the ON pathway once again exhibited only a long wavelength sensitivity peak at 620 nm, while the OFF pathway exhibited sensitivity to both medium (_max 560 nm) and long (_max 600–620 nm) wavelength light. These findings suggest that the photic environment plays an integral role in shaping spectral sensitivity of the ON and OFF pathways.     

Increment-threshold spectral sensitivity in the rabbit

Summary Increment threshold measurements in wild rabbits give rise to spectral sensitivity curves that are unimodal or bimodal in nature, depending on the background luminance. We propose a model that explains the shape of these curves on the basis of synergistic and antagonistic interaction of blue cones (_max = 425 nm), green cones (_max = 523 nm) and rods (_max = 498 nm).     

Fluorescence behavior of tryptophan residues of bovine and human serum albumins in ionic surfactant solutions: A comparative study of the two and one tryptophan(s) of bovine and human albumins

The fluorescence behavior of two tryptophans (Trp-134, Trp-213) in bovine serum albumin (BSA) and a single tryptophan (Trp-214) in human serum albumin (HSA) was examined. The maximum emission wavelength (_max) was 340.0 nm for both proteins. In a solution of sodium dodecyl sulfate (SDS), the _max of BSA abruptly shifted to 332 nm at 1 mM SDS and then reversed to 334 nm at 3 mM SDS. The _max of HSA gradually shifted to 330 nm below 3 mM SDS, although it returned to 338 nm at 10 mM SDS. In contrast to this, in a solution of dodecyltrimethylammonium bromide, the _max positions of BSA and HSA gradually shifted to 334.0 and 331.5 nm, respectively. Differences in the fluorescence behavior of the proteins are attributed to the fact that Trp-134 exists only in BSA, with the assumption that Trp-213 of BSA behaves the same as Trp-214 of HSA. The Trp-134 behavior appears to relate to the disruption of the helical structure in the SDS solution.     

Bacteriophage lambda replication proteins: formation of a mixed oligomer and binding to the origin of lambda DNA

Summary The purified bacteriophage replication proteins O and P sediment separately in metrizamide gradients of low ionic strength as dimers. Together they interact with each other forming an oligomer, composed of two molecules of O and one molecule of P. The O-P oligomer is active in the in vitro replication of ori-containing DNA.Equilibrium sedimentation in preformed metrizamide density gradients under conditions that separate DNA-protein complexes from free proteins was employed in order to study possible interactions among the replication proteins and ori DNA. It was found that the P protein binds specifically to ori-containing plasmid DNA only in the presence of O protein. About 100 molecules of O and 10 molecules of P form a complex with the ori DNA. The DNA-O-P complex was shown to be active in an in vitro replication system.Since the physical interactions between ori and O and between P and the Escherichia coli dnaB replication protein are well documented, the evidence for a O-P interaction presented in this paper provides the missing link in the molecular mechanism that enables to direct the host replication machinery to the replication of its own DNA.     

A point mutation in the Nul gene of bacteriophage lambda facilitates phage growth in Escherichia coli with himA and gyrB mutations

Summary A mutant of was isolated that grows in the Escherichia coli himA/gyrB-him320(Ts) double mutant at 42°C; conditions which are non-permissive for wild-type growth. The responsible mutation, ohm1, alters the 40th codon of the Nul reading frame. The Nul and A gene products comprise the terminase protein which cleaves concatameric DNA into unit-length phage genomes during DNA packaging. The Nul-ohm1 gene product acts in trans to support growth in the double himA/gyrB mutant, and cos154 growth in the single himA mutant. The observation that an alteration in Nul suppresses the inhibition of growth in the double himA/gyrB mutant implicates DNA gyrase, as well as integration host factor, in the DNA: protein interactions that occur at the initiation of packaging.     

Investigation of C-phycoerythrin from the cyanobacterium Pseudanabaena W 1174

A cyanobacterium which produces high amounts of C-phycoerythrin was classified as a new Pseudanabaena strain. This strain (number W 1173 of our collection) has been cultivated for 6 years without changing its properties. It resembles Pseudanabaena catenata (strain B 1464-1) morphologically but differs in the pigmentation. Contrary to strain B 1464-1, no chromatic adaptation was observed with strain W 1173. It was found that phycoerythrins from both strains differ in the following properties: isoelectric points, number of bilin chromophores, and immunochemical properties. Besides native C-phycoerythrin (PEI, _max = 558 nm), a degradation product (PEII, _max = 544 nm and 562nm) has been found in crude extracts from strain W 1173. Criteria for integrity of C-phycoerythrin were discussed which are essential if this biliprotein is used as taxonomic character.Abbreviations PE C-Phycoerythrin - SDS sodiumdodecylsulfate Dedicated to Professor Dr. O. Kandler on the occasion of his 60th birthday     

Defining patch contribution in source-sink metapopulations: the importance of including dispersal and its relevance to marine systems

In metapopulations, individual patch contribution (source or sink) is typically calculated as a patch growth rate (the intrinsic lambda, _I) dependent only upon local demographics. We demonstrate that when dispersal is explicitly included in the model, the growth rates for all patches calculated in an analogous manner (the observed lambda, _O) equilibrate to the overall metapopulation growth rate and thus no longer serve as a useful reflection of the demographic and dispersive characteristics of a given patch. In these situations we suggest an alternative method of estimating patch contribution (the contribution lambda, _C) in which a patch is decremented for losses that occur within it and credited for gains that occur anywhere in the metapopulation because of it. We compare values of _I, _O, and _C for individual patches in discrete-time density-independent metapopulation models of two organisms with very different life histories, mayflies with adult dispersal, and reef fish with larval dispersal. Results confirm that when dispersal is included only _C clearly indicates the contribution of a particular patch. _I–_C comparisons indicate that inclusion of dispersal in the mayfly model was only important if connectivity patterns were random or directional. In the reef fish model, however, results were very different when dispersal was included and there were many cases of patches being misidentified (e.g., as a source when it was really a sink) depending upon the metric used (_I or _C). Our results demonstrate the importance of including dispersal in metapopulation models when considering the contribution of individual patches.     

Dependence of phytochrome dark reactions on the initial photostationary state

Summary Under conditions of continuous irradiation, the P _jr destruction rate constants (k _d ) of phytochrome in hooks and cotyledons of squash (Cucurbita pepo L.) seedlings do not depend on the photostationary state and are the same in both organs. On the other hand, the rate constants of the dark reversion and the first destruction step, plotted as a function of ⁰ , show optimum curves with maxima between ⁰ and 0.5. Similar results were obtained for dark reactions of mustard (Sinapis alba L.)-hook phytochrome in vivo. This indicates a cooperative behaviour of these phytochrome dark reactions.Abbreviations P _r red-absorbing form of phytochrome - P _fr far-red-absorbing form of phytochrome - [P _tot] [P _r ]+[P _fr ] - [P _tot] ([P _fr ]/[P _tot]), photostationary state - ⁰ at t=0, immediately after saturating irradiation     

Cloning of the replication gene P of bacteriophage lambda: Effects of increased P-protein synthesis on cellular and phage DNA replication

Summary A restriction fragment of DNA carrying the P gene was cloned in the high copy number plasmid RSF2124. Cells harbouring this new plasmid RSF2124/E complement Pam80 phage. A lac promoter-operator region (lacP), produced by EcoRI digestion of plasmid pKB252, was inserted into RSF2124/glE such that induction of the lac promoter by IPTG or lactose leads to increased production of the P gene product. A high amount of P protein in E. coli cells results in a slow inhibition of bacterial DNA synthesis, suggesting that the initiation reaction is blocked by P protein. Synthesis of DNA proceeds normally under these conditions.Nonsuppressing groPA15 mutant bacteria which are unable to support the replication of wild-type (wt), acquire the ability to replicate Pam80 phage but not wt when they are transformed with a plasmid carrying the P gene. When harbouring a plasmid containing the mutant Pamber 80 gene, groPA15 mutants are able to support the replication of wt phage when infected at a high multiplicity. Pam80 phage does not multiply in these cells.     

In vitro insertion of the lambda attachment site into the plasmid RP4.

Summary The region of the phage lambda chromosome containing the attachment site (P · P) and the genes int and xis, excised by the action of endonuclease R.EcoRI, has been inserted into the unique site for that enzyme on the promiscuous conjugative plasmid, RP4, generating the recombinant plasmid RP4att. Transformants containing the hybrid plasmid were recognised by their ability to allow efficient lysogenization by phage b2 (Weil and Signer, 1968; Echols et al., 1968) containing the mutant attachment site · P. The construction and properties of the hybrid plasmid RP4att are described.