Screening of turfgrass species and cultivars for NaCl tolerance

Summary Information regarding the relative levels of salt tolerance between cultivars of Kentucky bluegrass (Poa pratensis L.) is lacking. The objectives of this study were to 1) develop a simple, quick and sensitive method of screening turfgrass species for NaCl tolerance and 2) to compare the relative salt tolerance of five cultivars of Kentucky bluegrass (Ram I, Adelphi, Baron, Bensun, and Nassau) to other known salt tolerant turfgrass species such as alkalaigrass (Puccinellia distans (L.) Parl. cv. Fults) and two cultivars of red fescue (Festuca rubra L. Dawson, and Checker).Alkalaigrass and both cultivars of red fescue retained a high level of salt tolerance compared to the Kentucky bluegrass cultivars. Significant variability in salt tolerance was apparent among the Kentucky bluegrass cultivars with Adelphi and Ram I exhibiting the best overall tolerance.     

Acetylcholinesterase molecular forms from rat and human erythrocyte membrane

Summary Inhibition of growth of PY815 mouse mastocytoma cells in vitro by N⁶, O²-dibutyryladenosine 3,5 cyclic monophosphate (DB cyclic AMP) was accompanied by increases in intracellular cyclic AMP and histamine and minor changes in cytosolic cyclic AMP-dependent histone kinase activity. However, DEAE-cellulose chromatography revealed substantial changes in the relative proportions of the principal cyclic AMP-dependent protein kinases and in free cyclic AMP-binding protein after DB cyclic AMP treatment. The activity of cytosolic cyclic AMP-dependent protein kinase type I (PK_I) decreased relative to cyclic AMP-dependent protein kinase type II (PK_II) and there was an increase in a cytosol cyclic AMP-binding protein with little associated protein kinase activity. The relative changes in activity of PK_I, PK_II and cyclic AMP binding protein after DB cyclic AMP treatment may reflect events important in the regulation of growth and differentiation of mast cells.Abbreviations DB cyclic AMP N⁶,O²-dibutyryladenosine-3, 5-cyclic monophosphate - cyclic AMP adenosine 3,5-cyclic monophosphate - PK_I type I cyclic AMP-dependent protein kinase - PK_II type II cyclic AMP-dependent protein kinase     

Carotenoid pigments of Sorangium compositum (Myxobacterales) including two new carotenoid glucoside esters and two new carotenoid rhamnosides

Summary The carotenoid pigments of the myxobacterium Sorangium compositum were analyzed by chromatographical and chemical techniques and by visible, infra red, and mass spectroscopy. Besides -carotene, neurosporene, torulene, lycopene, and 1,2-dihydro-1-hydroxy--carotene, four new carotenoid glycosides were found. These pigments were identified as 1,2-dihydro-1-hydroxy-torulene glucoside ester (I), 1,2-dihydro-3,1-dihydroxy-torulene glucoside ester (III), 1,2-dihydro-1-hydroxy-torulene rhamnoside (II), and 1,2-dihydro-3,1-dihydroxytorulene rhamnoside (IV).Fifth communication on the carotenoids of myxobacteria. Fourth communication see Arch. Mikrobiol. 76, 364–380 (1971).     

Contribution of L. Ya. Balonov and V. L. Deglin to Study of Verbal-Thinking Activity from the Viewpoint of Functional Brain Asymmetry

This paper summarized experimental data on the role of the right and left brain hemispheres in performance of the verbal and thinking activity, which were obtained by Lev Yakovlevich Balonov and Vadim L'vovich Deglin and published in numerous articles and monographs. The interpretation of these results, the concepts of Balonov and Deglin on regularities underlying division of functions between two hemispheres and on mechanisms of the hemispheric interaction are presented. The original concept is exposed, which consists in that the functional brain asymmetry is based on different relation of the right and left hemispheres to the language sign, its different vision and perception by each hemisphere. The data of study on the functional brain asymmetry also helped the authors to find answers to the questions concerning general scientific and general human problems dealing with the conscious and the unconscious, speech development in child, evolution of psychic activity. The authors understood clearly that the answers to these questions ...by no means will be exhaustive... and that ...this is merely one of possible points of view.     

Unusual antiproliferative effects of transforming growth factors-β 1 andβ 2 against primary cells from human tumors

Transforming growth factors 1 and2 (TGF-1 and2), tested in a clonogenic assay against primary cells from human tumors, suppress proliferation to different extents. In nineteen of twenty-six cell cultures, proliferation was < 50% of control with factor at 0.04 or 0.4 nM. Of these, TGF- 2 was more active than TGF-1 in fourteen; and TGF-1 was more active than TGF-2 in five. In seven of the nineteen, proliferation was 0% with one or the other factor. In contrast, cisplatin was much less effective in inhibiting proliferation of some of the same cells even at 1,000 or more times the molar concentration of the factors. Surprisingly, when TGF- 1 and TGF-2 were combined at equal concentrations, the antiproliferative effect of one was cancelled or markedly inhibited by the other.     

Production of a novel syrup containing neofructo-oligosaccharides by the cells of Penicillium citrinum

A novel syrup containing neofructo-oligosaccharides was produced from sucrose (Brix 70) by whole cells of Penicillium citrinum. The efficiency of fructo-oligosaccharides production was more than 55% and those of the main carbohydrate components, 1-kestose (Fruf 21Fruf 21 Glc), nystose (Fruf 21Fruf 21 Fruf 21 Glc) and neokestose (Fruf 26 Glc12 Fruf), were 22, 14 and 11%, respectively.     

Reactivity pattern of 15 HLA-Dw1 homozygous typing cells in primary mixed lymphocyte culture

Summary The Dwl specificity was highly correlated with the serologically determined HLA-DR1 antigen in the Eighth International Histocompatibility Workshop 1980. By testing a large number of HLA-Dwl, DR1 defined homozygous typing cells (HTC) in a checkerboard primary mixed lymphocyte reaction, on a panel of about 30 HLA-DR1 heterozygous individuals, and in family segregation, three Dwl subtypes could be defined in association with certain HLA-A, -B, and -C-antigens. HTC TA, FRI, and FRA carrying the HLA haplotypes A11, B35, Cw4 or A3, B35, Cw4 in the homozygous state gave positive typing results with most HLA-DR1 positive panel members and stimulated only four other Dw1 HTCs (SRR35%). In contrast to this operationally broad specificity, Dw1-HTC-HEN (HLA-A2, B44, C-, homozygous) was non-stimulatory to all HTCs except one, but gave high responses against these, leading to the definition of a narrow specificity included in the broad one. Another such narrow specificity was represented by HTC FEE (HLA-A2, B27, Cw2 homozygous). Typing patterns with FEE were mostly different from those defined with other HTC. In family studies a specific typing pattern for this HTC could be shown to segregate with HLA. However, within some of these responses a contribution of the HLA haplotype in the trans position must be assumed.Supported in part by DFG grant Ri 164/14     

Evolution of the variable gene segments and recombination signal sequences of the human T-cell receptor α/δ locus

The T-cell receptor (TCR) and loci are particularly interesting because of their unique genomic structure, in that the gene segments for each locus are interspersed. The origin of this remarkable gene segment arrangement is obscure. In this report, we investigated the evolution of the TCR and variable loci and their respective recombination signal sequences (RSSs). Our phylogenetic analyses divided the and variable gene segments into two major groups each with distinguishing motifs in both the framework and complementarity determining regions (CDRs). Sequence analyses revealed that TCR variable segments share similar CDR2 sequences with immunoglobulin light chain variable segments, possibly revealing similar evolutionary histories. Maximum likelihood analysis of the region on Chromosome 14q11.2 containing the loci revealed two possible ancestral TCR / variable segments, TRDV2 and TRAV1-1/1-2, respectively. Maximum parsimony revealed different evolutionary patterns between the variable segment and RSS of the same variable gene arguing for dissimilar evolutionary origins. Two models could account for this difference: a V(D)J recombination activity involving embedded heptamer-like motifs in the germline genome, or, more plausibly, an unequal sister chromatid crossing-over. Either mechanism would have resulted in increased diversity for the adaptive immune system.     

Oxidation of 17α,20β- and 17α,20α-Dihydroxypregn-4-en-3-ones,Side Products of Progesterone Biotransformation with Recombinant Microorganisms Expressing Cytochrome P-45017α

Progesterone biotransformation with recombinant yeasts Yarrowia lipolytica E129A15 and Saccharomyces cerevisiae GRF18/YEp5117 expressing bovine adrenocortical cytochrome P-45017 yielded 17-hydroxyprogesterone and two diols, 17,20- and 17,20-dihydroxypregn-4-en-3-ones. The oxidation of mixtures of the three steroids with chromic acid resulted in the cleavage of 17–20 bonds in the diols with the formation of androst-4-ene-3,17-dione. The biotransformation of pregn-4-ene-20-ol-3-one by means of Y. lipolytica E129A15 was accompanied by the following reactions: the primary oxidation of these compounds to progesterone and the subsequent successive reactions of 17-hydroxylation and 20- and 20-reduction. The results widen the possibilities of enzymatic and chemical modifications of steroids.     

Ionic relations of aeroponically-grown olive genotypes,during salt stress

Two olive (Olea europaea L.) genotypes, Frantoio and Leccino, were exposed to increasing concentrations of NaCl (0-30-60-120 mM) in an aeroponic cultivation system for 60 days. Dry weights and sodium and potassium contents of apical and basal leaves, new and old wood, and roots were measured to determine Na uptake rate, Na translocation rate and K-Na selectivity ratio (S_K,Na). Frantoio showed a higher salt resistance than Leccino. Frantoio and Leccino had a similar Na uptake rate, but largely differed for Na translocation to the shoot. Furthermore Frantoio exhibited a higher K-Na selectivity than Leccino at both whole plant level and above all at the level of shoot system. Resistance mechanism of Frantoio is probably related to Na esclusion by roots and to the ability to maintain an appropriate K/Na ratio in actively growing tissues.Research supported by National Research Council of Italy, Special project RAISA.     

Cytological characterization,powdery mildew resistance and storage protein composition of tetraploid and hexaploid 1BL/1RS wheat-rye translocation lines

Summary Progenies of a tetraploid 1BL/1RS wheat-rye translocation line, CV 256, selected from the cross Cando x Veery, were analyzed by means of Giemsa C-banding. CV 256 is cytologically stable for the presence of the 1BL/1RS translocation but still segregating for A- and B-genome chromosomes of Cando and Veery. In CV 256, nucleolar activity of the 1RS NOR locus is suppressed, as judged by the absence of a secondary constriction in that rye segment and the capability of organizing nucleoli. PAGE analysis of prolamins confirmed the presence of two 1RS secalins in all single seeds analyzed. SDS-PAGE analysis of reduced glutenins of single seeds indicated that some seeds contained the Cando Glu-B1 locus (subunits 6+8), some contained the Veery Glu-B1 locus (subunits 7+9) while others contained all four subunits, indicating that the material was heterozygous. Pm8 resistance is expressed in the tetraploid 1BL/1RS translocation line based on the reactions of six well-defined powdery mildew isolates. However, Pm8 resistance is not expressed in the hexaploid wheat cultivars Olymp, Heinrich and Florida, which also contain the 1BL/1RS translocation. Obviously, the existence of the 1BL/1RS translocation is not a proof for the expression of the associated genes. PAGE results did not show a clear linkage between powdery mildew resistance and the presence of 1RS secalins.     

Factors that effect leaf regeneration efficiency in apple,and effect of antibiotics in morphogenesis

Several factors that affect the frequency of organogenesis in apple leaf explants were examined for the scion cultivars Empire, Freedom, Golden Delicious, Liberty, McIntosh, and Mutsu and for the rootstocks Malling 7A and Malling 26. The main factors affecting morphogenesis were BA concentration, basal medium, leaf explant origin and maturity, explant orientation, and photosynthetic photon flux. Depending on the genotype, optimal regeneration was obtained using either 22.2 or 31.1 M BA and the N6 basal medium, with the exception of Golden Delicious which regenerated better on MS medium. After 6 weeks, the average number of shoots per segment varied from 5 to 16, and the percentage of regeneration between 70 and 100%, depending on the genotype tested and the maturity of the explant. Regeneration capacity increased dramatically from the tip towards the base of the leaf, and was higher from the middle to the proximal end.Cefotaxime and carbenicillin, two antibiotics commonly used during transformation studies to eliminate Agrobacterium tumefaciens from plant tissue, were tested to determine their effect on morphogenesis. Cefotaxime at a dose of 250 mg 1^-1 enhanced regeneration and shoot development, whereas carbenicillin at a dose of 500 mg l^-1 induced abundant callus formation and inhibited regeneration. Kanamycin, a widely used selection agent for plant transformation, strongly inhibited regeneration even at very low doses. Schemes for selection and recovery of transgenic apple plants when kanamycin is used as the selection agent are discussed.Abbreviations BA benzyladenine - Cef cefotaxime - Crb carbenicillin - IBA indolebutyric acid - Kan kanamycin - LS Linsmaier and Skoog (1965) medium - M Malling - MS Murashige and Skoog (1962) medium - NAA naphthaleneacetic acid - N6 medium (Chu et al. 1975) as modified by Welander (1988) - PPF photosynthetic photon flux     

Effect of alpha-isopropylmalate on the synthesis of RNA and protein in Neurospora

Summary The leu-3/-IPM (-isopropylmalate) regulatory system, previously shown to control several genes of leucine, isoleucine, valine, and histidine biosynthesis, appears likely to be involved also in the regulation of overall RNA and protein synthesis in Neurospora. Upon addition of -IPM the synthesis of all major species of stable RNA was found to be transiently inhibited by approximately 50%. A similar reduction was observed in overall protein synthesis. The inhibition was dependent in both cases on a functional leu-3 gene product, in conformance with previously established patterns of -IPM dependent gene regulation. The overt resemblance of the phenomenon described here to the stringent response of bacteria is noted but neither the mechanism of inhibition nor the precise role of -IPM in the process has been established.     

Zur Feinstruktur von Cuticula und Epidermis beim Flußkrebs Orconectes limosus während eines Häutungszyklus

Zusammenfassung Die Cuticula an der Innen- und Außenseite der Branchiostegite des Flußkrebses besteht wie für Arthropoden üblich aus Epi- und Procuticula. Sowohl die Epicuticula als auch die Procuticula von Innen- und Außenseite unterscheiden sich im Feinbau wesentlich voneinander. An der Innenseite ist die Epicuticula einfach gebaut; Die Procuticula ist lamelliert und zeigt meist die bogenförmigen Muster von Mikrofibrillen. Die Epicuticula an der Außenseite weist in den in dieser Arbeit untersuchten Entwicklungsstadien einen sehr viel komplizierteren Feinbau auf, der in der Entwicklung gewissen Änderungen unterliegt. In der wiederum lamellierten Procuticula an der Außenseite sind die Mikrofibrillen zu Balken gebündelt. Die Ausrichtung der Mikrofibrillen dreht sich innerhalb einer Lamelle um 180°. Durch die Procuticula ziehen Fortsätze der Epidermiszellen, außerdem Stäbe der sog. Verbindungsstrukturen.Die Bildung der Cuticula an der Innenseite konnte weitgehend vollständig verfolgt werden; sie ist gut mit der Bildung der Cuticula bei verschiedenen Insekten vergleichbar.Die Bildung der Cuticula an der Außenseite konnte dagegen nur von Beginn der Abscheidung der Proouticula bis zur Häutung verfolgt werden. Kurz vor Beginn der Cuticulaabscheidung kommt es in den Epidermiszellen zu einer stärkeren Entwicklung des rauhen ER. Während der gesamten von uns verfolgten Bildungsstadien sieht man Vesikel mit dichtem Inhalt besonders in der Nähe des Zellapex. Sie geben anscheinend hier ihren Inhalt, Cuticulamaterial, nach außen ab. Sie stammen wohl aus Golgibereichen. Auch Stachelsaumbläschen (coated vesicles) kommen regelmäßig vor, deren genetischer Zusammenhang mit multivesikulären Körpern diskutiert wird. Bei der Abscheidung der fibrillären Cuticulasubstanzen spielen besondere Differenzierungen der Zell oberfläche, — kappenartige Verdichtungen der Zelloberfläche, meist an der Spitze kleiner Mikrovilli — eine wesentliche Rolle.

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The ultrastructure of cuticle and epidermis in the crayfish Crconectes limosus during a moulting cycle

Summary The cuticle of the inside and outside of the branchiostegites of the crayfish consists of an epicuticle and a procuticle — as common in arthropods. Concerning their ultrastructure epicuticle and procuticle differ essentially from each other on both the inside as well as the outside. On the inside the epicuticle is built plainly; the procuticle is laminated, and, mostly it shows the arched patterns of microfibrils. In those developmental stages investigated in this project the epicuticle of the outside shows a much more intricated ultrastructure, since during formation it is subject to certain changes. On the outside the procuticle is also laminated; the microfibrils are bundled up to bars. The alignment of those microfibrils within one lamella is twisted for 180°. The procuticle is penetrated by processes of epidermal cells and by rods of the so-called connecting structures.The formation of the cuticle on the inside was observed completely; it is comparable to the forming of the cuticle in several insects. However, the formation of the cuticle on the outside was only observed from the beginning of the procuticular development up to the moulting.Shortly before formation of the cuticle the development of rough ER in the epidermal cells seems to be intensified. In all of developmental stages observed there appear vesicles with dense contents mainly situated nearby the cell apex. At this site they evidently deliver their contents — cuticular materials — to the outside of the cell; they probably originate in the Golgi areas. There occur coated vesicles regularity, too; their genetic relation to multivesicular bodies is discussed. Special differentiation on the cell surface i.e. dome-like consolidations of the cell surface mainly placed at the tip of small microvilli are of great importance for the secretion of the cuticle substances.

     

Effects of mine drainage on the river hayle,cornwall a) factors affecting concentrations of copper,zinc and iron in water,sediments and dominant invertebrate fauna

Concentrations of copper, zinc and iron were measured in waters, sediments and invertebrates collected from the River Hayle. In river water at least 70% of copper and iron was associated with the particulate fraction whereas 80% of zinc was in the soluble form. Although total concentrations of zinc in water exceeded those of copper approximately ten fold, copper predominated over zinc in the sediments by a factor of approximately three. Iron was the most abundant metal recorded in both water and sediments.Seasonal differences in total metal content of waters suggested that concentrations of copper, zinc and iron increased during. periods of high flow and decreased during lower flows. Copper concentrations in the sediment, unlike zinc and iron, showed markedly higher values during the summer sampling period when flows were minimal.In the free-living Trichoptera larvae, concentrations of copper and zinc in the tissue appeared to follow copper and zinc levels in the water. Similar relationships in Odonata and Plecoptera larvae were not obtained. Factors affecting animal/metal relationships are discussed with particular reference to adaptation shown by organisms exposed to high concentrations of heavy metals in their environment.Department of Applied Biology, Cambridge     

A neural coding model for sensory intensity discrimination,to be applied to gustation

Summary This paper presents a model of the neural coding and discrimination of sensory intensity. The model consists of five stages: (1) the coding of stimulus intensity in peripheral receptors or neurons by a rate code. The relevance of comparing different analysis intervals for the response is pointed out; (2) neural processing, according to either labeled-line or across-fiber pattern theory. In addition, two possible non-linearities in the processing are considered: a threshold mechanism, and contrast enhancement by reciprocal inhibition; (3) a neural discriminator, based on signal-detection theory; (4) a memory stage; (5) an effector organ providing a behavioral output. Emphasis is put on stages 2 and 3.The model produces predictions of the differential threshold, which should be directly testable in a behavioral two-alternative forced-choice paradigm. The model will be applied to gustatory intensity discrimination in rat in a subsequent study (Maes and Erickson 1984). The Discussion pays attention to the relative contributions of peripheral and central noise sources. It also compares the present model with Beidler's (1958) approach through just noticeable differences (JND's). The model presented here seems more adequate in providing an understanding of sensory information processing.Abbreviations AFP across fiber pattern - DA discrimination acuity - DT differential threshold - JND just noticeable difference - LL labeled line - NTS nucleus tractus solitarius     

Consequences of harvesting for genetic diversity in American ginseng (<Emphasis Type="Italic">Panax quinquefolius</Emphasis> L.): a simulation study

American ginseng, Panax quinquefolius L., is one of the most heavily traded medicinal plants in North America. The effect of harvest on genetic diversity in ginseng was measured with a single generation culling simulation program. Culling scenarios included random harvest at varying levels, legal limit random harvest and legal limit mature plant harvest. The legal limit was determined by the proportion of legally harvestable plants per population (% mature plants per population). Random harvest at varying levels resulted in significant loss of genetic diversity, especially allelic richness. Relative to initial levels, average within-population genetic diversity (H _e) was significantly lower when plants were culled randomly at the legal limit (Mann–Whitney U=430, p<0.001) or when only mature plants were culled (Mann–Whitney U=394, p<0.01). Within-population genetic diversity was significantly higher with legal limit mature plant harvest (H _e=0.068) than when plants were culled randomly at the legal limit (H _e=0.064; U=202, p<0.01). Based on these simulations of harvest over one generation, we recommend that harvesting fewer than the proportion of mature plants could reduce the negative genetic effects of harvest on ginseng populations.     

Comparative study on the chloroplast,mitochondrial and nuclear genome differentiation in two cultivated rice species,Oryza sativa and O. glaberrima,by RFLP analyses

Summary Restriction fragment length polymorphisms of chloroplast (ct), mitochondrial (mt) and nuclear DNA were investigated using eight cultivars of Oryza sativa and two cultivars of O. glaberrima. Relative variability in the nuclear and cytoplasmic genomes was estimated by a common measure, genetic distance. Based on the average genetic distances among ten cultivars for each genome, the evolutionary variabilities of the mitochondrial and nuclear genomes were found to be almost the same, whereas the variability of the chloroplast genome was less than half that of the other two genomes. Cluster analyses on ct and mt DNA variations revealed that chloroplast and mitochondrial genomes were conservative within a taxon and that their differentiations were well-paralleled with respect to each other. For nuclear DNA variation, an array of different degrees of differentiation was observed in O. sativa, in contrast with little variation in O. glaberrima. As a whole, differentiation between O. sativa and O. glaberrima was clearly observed in all three genomes. In O. sativa, no notable difference was found between the cultivars Japonica and Javanica, whereas a large differentiation was noticed between Japonica (including Javanica) and Indica. In all three genomes, the average genetic distances within Indica were much larger than those within Japonica (including Javanica), and almost similar between Japonica (including Javanica) and Indica. These facts indicate that differentiation in O. sativa was due mainly to Indica.     

Analyse des échanges de chromatides dans les cellules somatiques humaines

A new technique (BUdR treatment followed by acridine orange staining) allowing a differentiation of sister chromatids is described. A statistical analysis of 91 human karyotypes gives an estimate of the frequency of exchanges. The mean of sister chromatid exchanges is 27,3 and the minimum number is 11 per cell. — The frequency of these exchanges is proportional to the relative length of each chromosome, and the accumulation of several exchanges in some segments evokes the possibility of a negative interference. — The analysis of endomitoses treated with BUdR during at least two generations is not in disagreement with the model of semi-conservative replication of chromosomal DNA, but the modifications of the chromatids may result from a completely different process. — The frequency of endomitoses is increased by the treatment. These endomitoses allow a very precise analysis of the evolution of the sister chromatid exchanges, during two successive cellular generations.

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Travail de l'E.R.A. N 47 du C.N.R.S. et C.E.A. Contrat N 293.     

Transient state characteristics of adaptation to changes in light conditions for the cyanobacterium Oscillatoria agardhii

Transitions in growth irradiance level from 92 to 7 Em^-2 s^-1 and vice versa caused changes in the pigment contents and photosynthesis of Oscillatoria agardhii. The changes in chlorophyll a and C-phycocyanin contents during the transition from high to low irradiance (HL) were reflected in photosynthetic parameters. In the LH transition light utilization efficiencies of the cells changed faster than pigment contents. This appeared to be related to the lowering of light utilization efficiencies of photosynthesis. As a possible explanation it was hypothesized that excess photosynthate production led to feed back inhibition of photosynthesis. Time-scales of changes in the maximal rate of O₂ evolution were discussed as changes in the number of reaction centers of photosystem II in relation to photosynthetic electron transport. Parameters that were subject to change during irradiance transitions obeyed first order kinetics, but hysteresis occurred when comparing HL with LH transients. Interpretation of first order kinetic analysis was discussed in terms of adaptive response vs changes in growth rate.Non-standard abbreviations Chla chlorophyll a - CPC C-phycocyanin - PS II photosystem II - PS I photosystem I - RC II reaction center of photosystem II - P photosynthetic O₂-evolution - I irradiance, Em^-2 s^-1 - light utilization efficiency of cells, mmol O₂·mg dry wt^-1·h^-1/Em^-2 s^-1 - light utilization efficiency of photosynthetic apparatus, mol O₂·mol Chla ^-1·h^-1/Em^-2 s^-1 - P_max maximal rate of O₂ evolution by cells, mol O₂·mg dry wt^-1·h^-1 - P_max maximal rate of O₂ evolution by photosynthetic apparatus, mol O₂·mol·Chla ^-1·h^-1 - LL low light, E m^-2 s^-1 - HL high light, E m^-2 s^-1 - LH low to high light transition - HL high to low light transition - k specific rate of adaptation, h^-1 - specific growth rate, h^-1 - Q pool size of cell constituent, mol·mg dry wt^-1 - q net synthesis rate of cell constituent, mol·mg dry wt^-1·h^-1