Effects of continuous illumination on the rhizome of Caulerpa prolifera

Caulerpa plants were grown under a 12-hr light and 12-hr dark(12L-12D) regime for 8 days followed by 8 days of continuouslight (24L-0D). Under both light regimes the elongation of therhizome was by means of "tip growth". However, the rate of rhizomeelongation in 24L-0D regime (10.9 mm/day) was higher than thatof 12L-12D regime (7.9 mm/day). Jn the region of 1.5 mm fromthe tip, the RERE (relative elemental rate of elongation) under24L-0D and 12L-12D regimes were respectively 4% and 3% elongationper hr. Under 12L-12D photoperiod the subapical part of therhizome exhibited distinctive oscillation: bending upward duringthe light period or at the time of rhizoid cluster initiation,and in the dark becoming relatively straight except at the timeof cluster initiation. No such distinctive oscillation was observedin continuous light. ¹ Report of work supported by research grant GB-7885 from theNational Science Foundation, and in part by Research Councilof Rutgers University. (Received June 8, 1971; )     

Effects of Gibberellic Acid on the Rhizome and Rhizoids of the Algal Coenocyte, Caulerpa prolifera, in Culture

Treatment of the large coenocyte Caulerpa prolifera with a hormonallevel of GA₂ resulted in increased elongation of the rhizomeand more frequent initiation of rhizoids when the hormone wasadded to the Erdschreiber culture medium. No effect of GA₂ wasfound on the rate of initiation or elongation of blades. Theseresults suggest that the recently discovered gravimorphogeneticeffect on rhizoid development is mediated by endogenous gibberellin. Caulerpa prolifera, coenocyte, green alga, gibberellic acid     

Interference between the macroalga Caulerpa prolifera and the seagrass Halodule wrightii

A field experiment was conducted to examine interactions between the seagrass Halodule wrightii and the macroalga Caulerpa prolifera in the Indian River Lagoon, FL, USA, and further if the outcome of the interactions between the two species was influenced by water depth. The experiment involved the manipulation of neighbor presence in plots established at the shallowest (50 cm) and deepest (80 cm) depths at which the two species co-existed at adequate densities to perform removal experiments. Shoot and frond densities were measured at the beginning (April), middle (July) and end (October) of the 6-month growing season, and above- and below-ground biomass values were determined at the end of the experiment (October). In the middle of the growing season H. wrightii had higher shoot densities and greater biomass in plots where C. prolifera had been removed at both water depths. This same pattern in shoot density and biomass for H. wrightii also occurred at the end of the growing season at the 80 cm depth. C. prolifera occurred at higher densities and greater biomass in the 80 cm depth range, but was generally unaffected by the presence of H. wrightii at either depth.     

Culture studies on some Florida species of Caulerpa: Morphological responses to reduced illumination

The morphological development of three species of Caulerpa, C. sertularioides, C. paspaloides and C. racemosa has been studied in low light culture. The resulting morphologies are described and contrasted with the typical morphologies. Culture forms in all cases were unlike the field forms but each had affinities with other taxa described in the literature. The most important generalized response was a change in the symmetry of the assimilators from radial to bilateral. This response supports an earlier morphologically based theory on the evolutionary relationships among the species of Caulerpa.     

Identification of two putative adhesive polypeptides in Caulerpa prolifera rhizoids using an adhesion model system

The rhizoid section of the green alga Caulerpa prolifera (Cp) is active in attaching the developing plant to the substratum. A model system for the study of the adhesion of Cp rhizoids has been developed and identification of two putative adhesive polypeptides of Caulerpa (Vn-Cp) was revealed by immunodetection. A method for fast induction of new rhizoids was established using blade-base cutting followed by a few days of incubation. The new rhizoids were gently enclosed between two cover glasses and incubated until firm attachment developed. While analyzing protein extracts, two ∼60–70 kDa polypeptides (Vn-Cp I and Vn-Cp II) were identified by immunodetection with monoclonal antibodies to human vitronectin (Vn). The relative concentration values of the Vn-Cp proteins increased significantly in the ‘cell-wall’ fraction of the attached rhizoids during the incubation period. However, Vn-Cp proteins were not detected in non-attached rhizoids. Furthermore, the Vn-Cp proteins were also detectable on glass substratum subsequent to attached rhizoid removal. The induction and accumulation of Vn-Cp proteins on the ‘cell-wall’ of Caulerpa rhizoids and the firm attachment of the rhizoids to the glass substratum during the incubation period suggest that Vn-Cp proteins play a significant role in adhesion, which may be similar to the function of vitronectin in other adhesion systems. Furthermore, the high accumulation of Vn-Cp proteins on the glass substratum during attachment of new rhizoids suggests that the Vn-Cp proteins are secreted to the extracellular matrix and directly connect rhizoids to the glass substratum as an intermediate compound. These unique properties of Cp make it an excellent model system for the establishment of high amounts of adhesive material for future research. This revised version was published online in August 2006 with corrections to the Cover Date.     

The effects of continuous illumination on southern and northern Micrasterias strains

Different strains of Micrasterias (Chlorophyta, Conjugatophyceae); M. rotata (Grev.) Ralfs ex. Ralfs and M. denticulata Breb. ex. Ralfs var. angulosa (Hantzsch) W. & G. S. West from northern and southern Finland were treated with continuous illumination in order to study the cellular effects of the treatment and whether the tolerance to continuous light of the northern Finnish strains is related to the different daylenght conditions in northern and southern areas. During the growing season the Finnish strains normally live in long-day conditions or even in continuous light (between 60 and 70°N), and they also tolerated continuous illumination in the laboratory. Ultrastructural changes were found especially in the chloroplasts, where formation of calcium precipitates of different forms and sizes and also formation of plastoglobuli containing lipids appeared. However, even in 4-week treatments the ultrastructure of cells of these northern strains was not totally disrupted, contrary to what was found in southern M. torreyi , studied earlier. Southern and northern strains tolerated continuous illumination in different ways. They seem to differ from each other physiologically, and the differences are possibly located in their ionic metabolism and regulation. The injuries sustained during continuous illumination of Micrasterias may largely be caused by the accumulation of Ca²⁺ in cytoplasm and organelles, especially in the chloroplasts.     

Effects of microscope illumination on bacterial development

Summary Microscope illumination can cause retardation of growth, morphological alterations, and death of bacteria on nutrient agar in microscope growth chambers, even if the radiation is limited to the visible range of the spectrum. Various bacteria differ from one another in their sensitivity to microscope illumination. Not only photoinactivation but also a rise in temperature may contribute to these effects, as shown by the melting of benzalacetone in the illuminated field of an aqueous mount at an ambient temperature at least 15 degrees below its M. P. Recommendations are presented for reducing the effects of microscope illumination in developmental studies.

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Zusammenfassung Die Beleuchtung im Mikroskop kann bei Bakterien, welche auf Nährbouillonagar in ihrer Entwicklung beobachtet werden, Wachstumshemmung, morphologische Veränderungen und Abtötung verursachen, auch wenn der Spektralbereich auf das Sichtbare begrenzt ist. Verschiedene Bakterien unterscheiden sich in ihrer Empfindlichkeit. Nicht nur Photoinaktivierung, sondern auch Erwärmung infolge absorbierter Strahlungsenergie kann zu den Folgen beitragen; Benzalaceton in Wasser schmilzt unter Beleuchtung im Mikroskop bei einer Umgebungstemperatur, welche 15°C unter derjenigen des Schmelzpunktes liegt. Maßnahmen zur Verringerung der Beleuchtungseinflüsse werden besprochen.

     

Influence of long-term continuous illumination on the nuclear volume of hypothalamic neurons in female rats

A light microscopic quantitative analysis was performed for studying the effects of long-term exposure to continuous illumination on hypothalamic morphology in female rats. Nuclear volumes of neurons in the suprachiasmatic nucleus, paraventricular nucleus, ventromedial nucleus and preoptic area were measured in 16-18 month-old Long-Evans female rats which had been exposed to continuous light for 11 months. Significant nuclear volume shrinkage could be observed in all investigated regions except for the preoptic area in these animals when compared to that of control rats kept under a photoperiod of 14h light and 10h dark. The relationship between morphological changes of hypothalamic neurons and the marked alteration of melatonin and estrogen levels induced by long-term exposure to continuous light is discussed.     

Effects of color temperature of illumination on physiological functions

This article presents our recent studies on the effects of color temperature on the taste sense and the influence of color temperature on bright light exposure during night rest period. Ten male Japanese and ten male Chinese were exposed to four illumination conditions (200, 1500 lx x 3000, 7500 K). Their taste threshold of four common tastes and amount of saliva were measured. It was found in both Japanese and Chinese subjects that sensitivities to sweet and bitter taste were decreased under the lower illuminance condition. Under the lower color temperature condition, sensitivity to bitter taste in Japanese and sweet taste in Chinese were decreased. Secretion of saliva increased under the lower illuminance condition in both Japanese and Chinese. Only in Chinese subjects, secretion of saliva increased under the lower color temperature condition. In a separate experiment, six male Japanese students were subjected to bright light exposure during a night rest period. They performed a mental task from 23:00 h till 02:00 h, and took a rest from 00:00 h to 01:00 h. During the rest period they were exposed to bright light (3000 lx) of three different color temperatures: 3000 K, 5000 K, and 7000 K. After exposure to bright light of 3000 K but not at other color temperatures, the EEG alpha1 band ratio and the beta band ratio at 02:00 h were higher and lower, respectively, than that at 01:00 h. These findings indicated that lower color temperature bright light exposure during a night rest break led to a reduction of subjects' arousal level during the subsequent work. Herein, we discuss these results from the viewpoint of physiological anthropology.     

Strain dependent response of circadian rhythms during exposure to continuous illumination

Enzymes activities were measured, at three hours intervals, during 30 hours, in various tissues of C57BL/6J and A/J male mice. The measurements, were carried out on mice which were exposed for two, five and twenty one days to continuous illumination. Identical measurements were performed also on mice which were kept in alternating 14 hours light: 10 hours dark. Activity patterns of each group were analysed to test the presence, or absence, of rhythm characteristics. The results of the experiments with C57BL/6J have been previously reported. The comparison of the results, which were obtained from the two strains revealed that under exposure to alternating light: dark conditions all activity patterns exhibited a significant circadian rhythm. Except for one enzyme (thymus GAPD), the times of peak activity (acrophase) were identical for all other examined enzymes, in both strains. On the other hand when the two strains were exposed to continuous illumination they differed in their response to the effect of continuous light. The activity of the same enzyme exhibited different periodicity and/or different acrophase in each of the two strains. This variability reflects the existence of genetic differences, between the strains in the free running behavior of these enzymes' activity rhythms.     

光照对蛇足石杉某些生理生化指标的影响

蛇足石杉[Huperzia serrata (Thunb.ex Murray) Trev.]是石杉科(Huperziaceae)石杉属(Huperzia Bernh.)植物,其含有的药用成分石杉碱甲是一种高效胆碱酯酶抑制剂,可用于治疗老年人记忆减退、早老性痴呆症及重症肌无力症等[1],目前,已有学者将石杉碱甲开发成治疗早老性痴呆症的一类新药.     

EPR-detectable magnetically interacting manganese ions in the photosynthetic oxygen-evolving system after continuous illumination

Freezing of spinach or barley chloroplasts during continuous illumination results in the trapping of a paramagnetic state or a mixture of such states characterized by a multiline EPR spectrum. Added Photosystem II electron acceptor enhances the signal intensity considerably. Treatments which abolish the ability of the chloroplasts to evolve oxygen, by extraction of the bound manganese, prevent the formation of the paramagnetic species. Restoration of Photosystem II electron transport in inhibited chloroplasts with an artificial electron donor (1,5-diphenylcarbazide) does not restore the multiline EPR spectrum. The presence of 3-(3,4-dichlorophenyl)-1, 1-dimethylurea (DCMU) results in a modified signal which may represent a second paramagnetic state. The paramagnetic forms appear to originate on the donor side in Photosystem II and are dependent on a functional oxygenevolving site and bound, intact manganese. It is suggested that magnetically interacting manganese ions in the oxygen-evolving site may be responsible for the EPR signals. This suggestion is supported by calculations.     

Rhythms in respiratory metabolism of Lemna gibba G3 under continuous illumination

Changes in chemical constituents and respiratory metabolismof a long-day duck-weed, Lemna gibba G₃ exposed to continuousillumination after short-day cultivation were investigated.The dry weight to fresh weight ratio was constant during thefirst 72 hr of continuous illumination. pH of the crude extractwas constant at 6.6, but pH of the culture medium was raisedwith the Lemna growth. Titratable acidity decreased after about44 hr, whereas malic acid content increased in 18 hr. Therewere no significant changes in total reducing sugar and pentose.Total protein content and lipid showed rhythmical changes withcycles of 48 hr. O₂-Uptake gave a damped oscillation with cycles of 24 hr. Itwas low in the first half day and high in the second half. ¹⁴CO₂-Outputfrom glucose-l-¹⁴C showed a similar damped oscillation. ¹⁴CO₂-Outputfrom glucose-2-14^C or glucose-6-₁₄C was almost constant. TheC₆/C₂ ratio, then, showed damped oscillation in the reverseway to O₂- uptake between 0.3–0.5, and the C₈/C₂ ratiowas constant at 0.9. Accordingly, the diurnal rhythm of O₂-uptakewas thought to be brought about by variation in activity ofthe pentose-phosphate pathway. Reproduction of glucose-6-phosphateby the pentose-phosphate pathway was presumably limited in amount. Glyceraldehyde-3-phosphate dehydrogenase activity varied diurnally.The activities of NADP-linked and NAD-linked enzymes increasedand decreased, respectively, in the first half day. Variationsin these enzymatic activities are discussed in correlation withrhythmical changes in O₂-uptake and in the C₆/C₁ ratio. Acidphosphatase activity also followed a diurnal variation. No activitiesof alcohol and formic dehydrogenases were found. The activitiesof NADP glucose-6-phosphate dehydrogenase, 6-phosphogluconatedehydrogenase, pyruvic kinase and NADP isocitric dehydrogenasewere high, but showed no rhythmical variation. ¹Presented at the Annual Meeting of the Botanical Society ofJapan, 1966 (Proceedings, p. 46). Adapted from a thesis submittedby the first author (H. M.) in 1967 to the Biological Institute,Nagoya University in partial fulfillment of the requirementsfor the degree of M. S. (Received May 8, 1969; )     

Stable concentrations of phytochrome in pisum under continuous illumination with red light

In vivo spectrophotometry showed that the phytochrome concentration in pea epicotyl hooks decreased at a constant rate for 4 hours when the tissue was exposed to continuous red light. Thereafter the rate slowed progressively so that a steady concentration of phytochrome was approached at hour 7. Returning the plants to darkness resulted in an increase in phytochrome due to the apparent synthesis of P_R. A closely similar pattern of changes was found in the amount of phytochrome extracted from the tissue. The establishment of the stable concentration was inhibited by 2,4-dichlorophenoxyacetic acid and did not occur in segments which had been incubated for longer than 24 hours, but was observed when segment growth was inhibited by mannitol. The results may be explained by an equilibrium between P_FR destruction and apparent P_R synthesis.