An alternative propagation method ofAnanas through nodule culture

A micropropagation scheme forAnanas comosus Merr. was developed using nodule culture. Nodules were induced from leaf-base or chopped shoot-base explants on modified half-strength MS medium supplemented with 2.69-5.37 M NAA and 4.44 M BA and could be maintained long-term as nodules. The nodules proliferated into more nodules when chopped into pieces of 1–3 mm and placed onto the same medium. They regenerated shoots when transferred to medium supplemented with 0.54–10.74 M NAA and 0.44–8.88 M BA. The regeneration capacity of nodules is higher than that of direct regeneration or callus. Maximum regeneration was obtained from culture medium containing 0.54 M NAA and 0.44 M BA, where shoots could be observed as early as within 2 weeks. Many shoots formed roots in the same medium in which they were regenerated after 10 subcultures, but the best rooting occurred in medium containing 0.54 M NAA and 0.44 M BA. Rooted plantlets ofA. comosus Merr. could be routinely produced at 6-week intervals.Abbreviations NAA naphthaleneacetic acid - BA 6-benzylaminopurine     

A novel technique for the study of bacterial cell mechanical properties

A micromanipulation method is described for measuring the bursting forces of bacteria and relating them to cell size. At a compression speed of 6.2 m s^–1, bursting forces of three samples of rapidly growing Staphylococcus epidermis from a batch culture varied from 3 to 34 N with an average value of 13.8 N (standard error 0.8 N). Escherichia coli grown in continuous culture at a specific growth rate of 0.5 h^–1 had bursting forces varying from 1 to 9 N with an average value of 3.6 N (standard error 0.4 N). In squeeze-hold experiments, force relaxation was observed, which was attributed to water loss from the cells, or viscoelasticity, or both. At high compression speed, such as 6.2 m s^–1, this relaxation could be neglected. Micromanipulation strength measurements might be used in studies of cell mechanical disruption and of the dependence of cell strength on cell physiology.     

Der praecorneale Glykosaminoglykan-Film beim Haushuhn

Summary The anterior cornea epithelium of the house-hen consists of 5 layers. The outermost layer has a villus border. The 0.2 long microvilli are 0.04–0.05 thick and are not more than 0.1 apart. A film of ruthenium red stainable glycosamine Glycans of 0.26–0.3 thickness lies on the free surface. The microvilli protrude into this film. This film is responsible for the reflecting shine of the cornea. The tear secretion can be kept at a low level as a part of the fluid is bound to the acid mucopolysaccharides. The molecules for this film are probably synthesized in the outermost cell layer.

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Der praecorneale Glykosaminoglykan-Film beim Haushuhn

Zusammenfassung Das vordere Corneaepithel des Haushuhnes besteht aus 5 Schichten. Die oberflächlichste Lage hat einen Zottenbesatz. Die 0,2 langen Mikrovilli haben eine Dicke von 0,04–0,05 und einen Abstand von höchstens 0,1 voneinander. Auf der freien Oberfläche liegt ein mit Rutheniumrot anfärbbarer Film von Glykosaminoglykanen von 0,26–0,3 Dicke. Die Mikrovilli ragen in diesen Film hinein. Dieser Film ist für den spiegelnden Glanz der Cornea verantwortlich. Die Tränensekretion kann sehr gering sein, weil ein Teil der Flüssigkeit an die sauren Mukopolysaccharide gebunden ist. Die Moleküle dieses Films werden wahrscheinlich in der oberen Zellage synthetisiert.

     

Regeneration of plants from callus and embryos of ‘Royal’ apricot

Immature embryos of apricot (Prunus armeniaca L.) cv. Royal with a PF index of 25–100 were used to regenerate plants in vitro using two methods. In the first case, callus was initiated on MS medium with 4.5 M 2, 4-D plus 0.44 M BA and regeneration of shoots from the callus occurred on MS medium with 4.4 M BA plus 1.0 M 2, 4-D. In the second case, adventitious buds were directly regenerated from the cotyledons on MS medium with 4.4 M BA plus 1.0 M 2, 4-D.Abbreviations BA 6-benzyladenine - IBA dole-3-butyric acid - NAA -naphthylacetic acid - 2, 4-D 2, 4-dichlorophenoxyacetic acid - PF (embryo length/seed length) x 100     

The effect of monoterpenes on astaxanthin production by a mutant ofPhaffia rhodozyma

Summary The total pigment and astaxanthin content ofPhaffia rhodozyma increased with increasing concentrations -pinene up to 500 l -pinene/l. Above this concentration the total pigment and astaxanthin content as well as the biomass production decreased. The addition of 500 l -pinene/l increased the total pigment content from 1652 g/g to 2201 g/g and the astaxanthin content from 1554 g/g to 1883 g/g. A sharp decrease in maximum specific growth rate occurred above 150 l -pinene/l.     

Der Entwicklungscyclus mit Sexualphase bei der marinen Diatomee Coscinodiscus asteromphalus

Zusammenfassung Die Kultur der großen marinen Diatomee Coscinodiscus asteromphalus wird beschrieben. Die Synchronisation der vegetativen Stadien aus dem Entwicklungscyclus mit Sexualphase wird durch Messung der Valvendurchmesser charakterisiert. Die Art entwickelt sich von Stadien mit 200 m Valvendurchmesser (V.-D.), die nicht sexuell induzierbar sind, zu Stadien mit 80–90 m V.-D. mit einem Optimum der Induzierbarkeit und weiter zu Stadien mit 55–60 m V.-D. Bei dieser Größe ist keine weitere mitotische Zellteilung mehr möglich. Entwicklungsstadien mit 200–190 m, 140–130 m und 100–90 m. V.-D. zeigen bei 24°C und bei 18°C die gleiche Generationszeit im mitotischen Entwicklungscyclus von 1 bzw. 0,6 Zellteilungen pro Tag. Der Valvendurchmesser verringert sich bei dieser Art um 1,5 m bei 24°C und 1,4 m bei 18°C während einer Zellteilung.

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The life cycle with sexual phase in the marine diatom Coscinodiscus asteromphalus I. Culture and synchronisation of developmental stages

Summary Culture-conditions for the large marine centric diatom Coscinodiscus asteromphalus are described. The cells grow in a defined medium in a light-dark regime of 14: 10 h. Synchronization of different stages of the sexual life cycle is characterized by measuring the valve diameter (v.d.) of the cells. The cells develop from stages with 200 m v. d. (not sexually inducible) to stages with 80–90 m v. d. (optimum for sexual induction), and further to stages with 55–60 m v. d., where no following mitotic cell division is possible. The length of the pervalvar axis does not change during this development. Different stages (200–190m, 140–130 m and 100–90 m v. d.) grow with the same doubling time during their mitotic life cycle: 1 cell division per day at 24° C and 0.6 cell divisions per day at 18°C. During one cell division the valve diameter of this species decreases by about 1.5m at 24°C and by 1.4 m at 18°C. Therefore, the development from stages with 200 m v.d. to stages with 60 m v. d. takes between 90 days at 24°C and 165 days at 18°C.

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Teile einer Habilitationsschrift der Naturwissenschaftlichen Fakultät der Universität Marburg (Lahn).     

Fractionation of phosphate in sediments of four representative mangrove stages (French Guiana)

Phosphate was fractionated in Guianese mangrove sediments. Fe(OOH)P was extracted using a Ca-EDTA + Na-dithionite solution buffered at pH 8. CaCO₃P was extracted using Na₂-EDTA solution at pH 4.5. Next, Acid Soluble Organic Phosphate (ASOP) was extracted by H₂SO₄ 0.5 N. Finally, Residual Organic Phosphate (ROP) was digested with H₂SO₄ + H₂O₂. Four representative mangrove stages have been studied: sea edge pioneer mangroves, mature coastal mangroves, mixed riverine mangroves, and declining to dead mangroves. The sum of the P-fractions varied between 638 to 804 g g^-1 in pioneer and mixed mangroves respectively. In all the stages, the percentage of inorganic phosphate was larger than 50% of the total P. Fe(OOH)P varied between 221 (pioneer mangrove) to 426 g g^-1 (dead mangrove). CaCO₃P varied between 75 to 102 g g^-1 in mixed, dead or mature mangroves and attained 125 g g^-1 in pioneer mangrove. The sum of the concentrations of organic phosphate (ASOP + ROP) increased markedly from the dead mangrove (189 g g^-1) to the mixed mangrove (380 g g^-1). Guianese mangroves, are relatively rich in total phosphate, possibly because they are narrowly related to the 'Amazon dispersal system. Each mangrove stage can be characterised by a prevailing form of phosphate. The concentrations of these different forms were ascribed to the marked relations with the seawater which controls import or export of suspended matters and to the wave action which controls the resuspension of the sediments and subsequently exchange of phosphate between the suspended matter and the water column.     

Indole butyric acid induces regeneration of phenotypically normal apricot (Prunus armeniaca L.) plants from immature embryos

A prerequisite for most transformation systems is an efficient and reliable method to regenerate phenotypically normal plants. Immature embryos or cotyledons were cultured at three developmental stages (stage 1, 2 and 3, PF=3, 30–60, and 100, respectively) from two unrelated apricot genotypes, Zard and NJA82. Explants were cultured on MS media supplemented with either BA or TDZ at four concentrations (0, 0.5, 5.0 or 20 M) and 2,4-D at 0 or 1 M. Stage 1 embryos cultured on MS medium without growth regulators formed embryoid-like structures. Shoot primordia induction was greatest with stage 2 cotyledons on media containing 5–20 M TDZ and 1 M 2,4-D, although shoot morphology was abnormal, especially with the highest level of TDZ. In another factorial experiment, stage 2 cotyledons were cultured on media containing TDZ (0, 5, 7.5, 10, 15 or 20 M) in combination with either no auxin, 1 M 2,4-D, 1 M IBA, or 5 MIBA. Regeneration percentages of 80% or more were observed on media containing 1–5 M IBA and 5–10 M TDZ. The medium containing 5 M IBA and no TDZ exhibited the highest frequency of phenotypically normal plantlet regeneration.Abbreviations BA 6-benzylaminopurine - IBA indole-3-butyric acid - 2,4-D 2,4 dichlorophenoxyacetic acid - 2iP 2-isopentenyladenine - MS Murashige and Skoog basal medium - NAA 1-naphthaleneacetic acid - PF percent fill [(embryo length/seed length) × 100] - TDZ thidiazuron [N-phenyl-N(1,2,3,-thidiazol-5-yl)-urea] - WPM McCown's woody plant medium     

Somatic embryogenesis in callus cultures of Rosa hybrida L. cv. Landora

Callus was initiated from immature leaf and stem segments of rose (Rosa hybrida cv. Landora) and subcultured every four weeks on a basal medium of half-strength Murashige & Skoog (1962) salts plus 30 g l^-1 sucrose (1/2 MS) and supplemented with 2.2 M BA, 5.4 M NAA and 2.2–9.0 M 2,4-D. Embryogenic callus and subsequently somatic embryos were obtained from 8-week-old callus culture on 1/2 MS+2.2 M BA+0.05 M NAA+0.3 M GA₃+200–800 mg l^-1 L-proline. Long-term cultures were established and maintained for up to 16 months by repeated subculture of embryogenic callus on L-proline deficient medium. About 12% of cotyledonary stage embryos taken from cultures cold-stored at 8±1°C for 4 days germinated on 1/2 MS+2.2 M BA+0.3 M GA₃+24.7 M adenine sulphate.Abbreviations BA benzyladenine - NAA -naphthaleneacetic acid - 2,4-D 2,4-dichlorophenoxyacetic acid - GA₃ gibberellic acid     

Calpain-PKC Inter-Relations in Mouse Hippocampus: A Biochemical Approach

In previous studies, we isolated and identified a -calpain/PKC complex from rabbit skeletal muscle. Here, we have used specific purification procedures in order to study the interactions between -calpain and PKC in mouse hippocampus, a brain structure implicated in memory processes. We observed that -calpain and conventional PKCs (, II and ) are co-eluted after anion exchange chromatography. In contrast to our previous results obtained on skeletal muscle, -calpain and PKC isoenzymes were dissociated after gel filtration chromatography. Furthermore, -calpain induced the proteolytic conversion of PKC, II, and into PKM, II, and with a preferential hydrolysis of PKC, a specific isoenzyme of the nervous system. Although the -calpain/PKC interactions in the hippocampus are quite different from skeletal muscle, our results however, point out the functional importance of these inter-relations. Moreover, as PKC has been involved in the biochemical events underlying learning and memory, the preferential relationship between -calpain and PKC promotes the importance of the role that -calpain could play in the cellular mechanisms of memory formation.     

In vitro propagation of Glehnia littoralis from shoot-tips

Shoot cultures of Glehnia littoralis F. Schmidt ex Miq. (Umbelliferae) were established by placing shoot tip explants on Linsmaier and Skoog medium with 1 M NAA and 10 M BAP. Shoots were multiplied on the basal medium supplemented with 0.3 M NAA and 3 M BAP and rooted on medium containing either 1 M IBA or 3–10 M IAA. Plantlets survived in pots without any covering. This unique characteristic of the plantlets was ascribed partly to a well-developed cuticle on the surface of the leaf and the small ratio of surface area to fresh weight of a leaf blade in comparison with those of other species whose plantlets needed coverings after potting. The regenerated plantlets were finally transferred to soil.Abbreviations IAA potassium indole-3-acetate - IBA indole-3-butyric acid - IPA indole-3-propionic acid - NAA potassium 1-naphthaleneacetate - 2,4-D sodium 2,4-dichlorophenoxyacetate - BAP 6-benzylaminopurine - 2-iP N⁶-(2-isopentenyl)adenine     

The effect of antibiotics on the inhibition of callus induction and plant regeneration from cotyledons of sugarbeet (Beta vulgaris L.)

Callus induction and plantlet regeneration from cotyledonary expiants of sugarbeet was observed utilizing two media formulations, MS and a modified MS termed RVIM both supplemented with 1.0 g/ml BAP as the sole growth regulator. Callus induction was genotype dependent The USDA line 8787 produced the highest response for callus induction followed by Betaseed 4587 and the USDA line C600. This order was conserved on both media formulations. Shoot induction was consistently higher averaging 32% from the RVIM formulation over the 3 genotypes compared to 25% from MS. The antibiotics geneticin, gentamycin, hygromycin, kanamycin and phleomycin were screened with the modified RV system utilizing Betaseed 4587. Callus growth was inhibited by levels of 50 g/ml geneticin, 150 g/ml gentamycin, 10 g/ml hygromycin, 150 g/ml kanamycin and 20 g/ml phleomycin. The results indicate that the concentrations of antibiotics used to inhibit callus induction will be sufficient for use as selectable markers in transformation experiments with Beta vulgaris.Abbreviations B₅ basal medium (Gamborg et al, 1968) - BAP N⁶-Benzylaminopurine - IBA Indole-3-butanoic acid - MS basal medium (Murashige and Skoog 1968) - RVIM modified MS basal medium (Freytag et al, 1988) - MES (2[N-Morpholino] ethanesulfonic acid     

Micropropagation of Hemidesmus indicus (L.) R. Br. through axillary bud culture

A procedure for rapid in vitro propagation of the aromatic and medicinal plant Hemidesmus indicus (L.) R.Br. (Family Asclepiadaceae) from nodal explants is described. The highest shoot multiplication rate of 8.2 ± 0.4 shoots/explant with a 95% frequency was achieved in S weeks culture period on Murashige and Skoog medium supplemented with 1.15 M kinetin and 0.054 M -naphthaleneacetic acid. Excised shoots were rooted on the same basal medium supplemented with 1.15 M kinetin and 7.35 M indole-3-butyric acid. Shoots derived from subcultures exhibited better rooting response than those from primary cultures. After a hardening phase of 2 weeks, there was a 70% transplantation success in the field.Abbreviations MS Murashige and Skoog (1962) medium - BA N⁶ benzyladenine; KN kinetin - NAA a-naphthaleneacetic acid - IBA indole-3-butyric acid - IAA indole-3-acetic acid     

Zur Feinstruktur der Elektrozeptorepidermis der Mormyridae (Teleostei,Pisces)

Zusammenfassung Die schwachelektrischen Mormyridae haben eine dreischichtige Epidermis, deren innere Schicht aus nur etwa 0,22 m dicken sechseckigen Zellen von ca. 60 m Durchmesser besteht. Die etwa 2 m dicken, linsenförmigen Kerne von 7,6 m Durchmesser liegen am Zellrand. Die Zellen sind zu Säulen aufgeschichtet. Ihr Rand ist ausgezackt und dort, wo er die Säulengrenze erreicht, auf etwa 0,34 m verdickt. In der Nähe der Säulengrenzen sind die Zellen über Desmosomen mit den Nachbarn in der eigenen und in der angrenzenden Säule verbunden. Diese Epidermisschicht ist auf die Körperpartien beschränkt, in denen auch Elektrorezeptoren ausgebildet sind.Die beiden anderen Epidermisschichten haben den üblichen Aufbau einer Fischepidermis, abgesehen vom Fehlen der Becherzellen.

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Ultrastructure of the electroceptor epidermis of the Mormyridae (Teleostei, Pisces)

Summary The weakly electric fish of the family Mormyridae have a three layered epidermis, with a medium layer consisting of hexagonal cells of only 0.22 m in thickness and about 60 m in diameter. The lens-shaped nuclei are about 2 m thick and 7.6 m in diameter and are situated near the border of the cells. The cells are piled up to hexagonal columns. Their margin is serrate and where it reaches the boundary of the column, it has a thickness of about 0.34 m. Close to the boundaries of the columns, the cells are linked to their neighbours within the column and of the adjoining column by desmosomes. This layer of the epidermis is confined to those regions of the body surface which also contain electroreceptors.The other layers of the epidermis have a structure as usual in fish, except for the lack of goblet cells.

     

Die Länge der Internodien der Markfasern im Bereich der Sehrinde der erwachsenen Katze

Zusammenfassung Die Internodienlänge der Markfasern und ihre Abhängigkeit vom Durchmesser wird durch indirekte Messungen an elektronenmikroskopischen Bildern bestimmt. Der Ranviersche Schnürring wird für die Messung in einen nackten und zwei lamellierte Teile unterteilt (Abb. 1). Die Summenlänge der Markfasern und der Nodien besitzen die in Abb. 4 sichtbare Beziehung zum Durchmesser. Die Internodienlänge beträgt für Markfasern mit einem Durchmesser von 0,4 etwa 40 für solche mit einem Durchmesser von 2,5 etwa 500 . Es wurde eine mittlere Internodienlänge von 90 gefunden. Die Länge aller Markfasern pro mm³ beträgt 590 m; daraus kann eine Anzahl von 6 bis 7 Millionen Ranvierscher Schnürringe pro mm³ errechnet werden. Die Internodienlänge und der Durchmesser stehen wahrscheinlich in einer logarithmischen Beziehung (Abb. 8). In diese logarithmische Beziehung fügen sich die Ergebnisse anderer Autoren gut ein.

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Summary In electron micrographs the internodal length of myelinated fibers and its relation to the diameter has been measured. In this investigation the node of Ranvier is subdivided in three parts, i. e. one non-myelinated and two lamellated parts (Fig. 1). The relationship between the length of the nodes of Ranvier and its diameter is determined (Fig. 4). The internodal length is about 40 for fibers with a diameter of 0.4 and 500 for those with a diameter of 2.5 . The average internodal length is about 90 . The myelinated fibers have a total length of 590 m per mm³; in one mm³ there are therefore 6 to 7 million nodes. The relation between length of internodium and diameter of fiber is probably logarithmic (Fig. 8). The results are compared with similar measurements on peripheral nerves carried out by other authors.

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Mit dankenswerter Unterstützung durch die Deutsche Forschungsgemeinschaft.     

Aflatoxin influences on seed germination and root elongation by two cultivars of Glycine max and uptake of 65 Zn-ZnCl2 by the cultivars

Maximum inhibition of Glycine max, cv. Essex seed germination occurred at 10 g/ml following 72 hr imbibition in constant light. Seeds imbided 108 hr in constant darkness at this concentration showed a 20% rise in germination over that of the control. Imbibition of G. max, cv. Williams seeds in either light or dark for 96 hr did not suppress germination. Imbibition of Essex seeds in either light or dark at 2.5 through 10 g/ml stimulated root elongation except for 10 g/ml at 96 hr (light). Maximum inhibition of Williams root elongation under constant light was at 48 and 72 hr with 10 g/ml. Statistically significant differences in cotyledon, leaf and stem lengths between non-treated (NT) and treated (T) seedlings were not found except for Williams stem length at 2.5 / ml. Root elongation was stimulated 1.2- and 1.1-folds, respectively, at 5.0 (Essex) and 2.5 (Williams) g/ml. Toxin at 2.5 through 10.0 g/ml did not markedly alter either cotyledon or leaf widths with the exception of Williams leaf width at 2.5 g/ml. Medium supplementation with 2.5 through 10.0 g/ml resulted in cotyledon, leaf and root weight enhancements for Essex seedlings. Stem weight was not markedly affected. An 18% rise in Williams cotyledon weight above that of the control was seen at 2.5 g/ml. Williams leaf weights were increased 1.75- and 1.25-folds, respectively, at 2.5 and 10.0 g/ml. Aflatoxin B₁, at 2.5 g/ml promoted Williams stem and root elongation 1.20- and 1.09-folds, respectively. Most of the radioactivity from ⁶⁵Zn-ZnCl₂ recovered within organs was found within Essex roots for both T and NT seedlings. A higher amount of radioactivity was recovered within roots at each toxin concentration than was without toxin. However, this was not statistically significant. Significant differences in the distribution of radioactivity within roots between NT and T Williams seedlings were not observed. Generally, AFB₁ failed to affect significantly these two varieties of soybeans based on the tests relating to germination, growth and radiolabel uptake.     

Transformation of Atriplex gmelini plants from callus lines using Agrobacterium tumefaciens

Atriplex gmelini plants were regenerated via organogensis from hypocotyl explants. Callus lines were induced from the hypocotyl explants on Linsmaier and Skoog (LS) medium supplemented with 1 M benzyladenine and 5 M -naphthaleneacetic acid in the dark. Shoots were regenerated from the callus lines on LS medium supplemented with 20 M thidiazuron and 0.1 M -naphthaleneacetic acid under a high-intensity light condition (450 mol m^–2 s^–1). The regenerated shoots were rooted on LS medium without growth regulators to obtain fully developed plants. We succeeded in transforming Atriplex gmelini from callus lines using Agrobacterium tumefaciens.     

Genes of the constant regions of functional immunoglobulin heavy chain of Japanese flounder,<Emphasis Type="Italic"> Paralichthys olivaceus</Emphasis>

IgM and IgD genes of the Japanese flounder were cloned and characterized from a genomic bacterial artificial chromosome (BAC) library. The gene contained four constant region exons (C1–C4), and two transmembrane exons (TM1 and TM2), which conforms to the organizational pattern of all other vertebrate -chain genes examined so far. In the same BAC clone, the gene, which is homologous to the IgD gene in mammals and teleost fish, was found immediately (0.9 kb) downstream of the IgM gene. This gene encoded seven exons (C1–C7) and two TM exons (TM1 and TM2) and had no duplication of C1-C2, as found in Atlantic cod, or C2-C3-C4, as found in Atlantic salmon and channel catfish. Phylogenetic and sequence analyses strongly suggest that teleost is more closely related to non-IgM isotypes than IgM isotypes. The heavy chain (IgH) locus of Japanese flounder, which encodes m, s and m, was found to be fully functional.     

Micropropagation of the rare species Stylidium coroniforme and other Stylidium species

The number of plants in the gazetted rare species Stylidium coroniforme was increased through micropropagation. A method was first developed using the common species S. brunonianum. It was found that for both species, rapid propagation could be obtained by excising shoots from sterile seedlings and inducing shoot proliferation on Murashige and Skoog medium supplemented with 1 M BAP. Rooting was achieved using 1 M IBA and over 100 plants of each species were successfully established in soil. Leaf pieces could also be used to initiate cultures. In media with 20–25 M BAP and 1–5 M IBA, leaf pieces of S. brunonianum, S. piliferum, S. caricifolium and S. crassifolium produced adventitious buds, thus providing another method of micropropagation.     

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