Relative sensitivity of various spectral forms of photosynthetic pigments to leaf senescence in wheat (Triticum aestivum L.)

The change in the characteristics of the absorption spectrum of chloroplasts which were isolated from the mature and senescing primary wheat leaves, was examined at various wavelengths in which the photosynthetic pigments mostly absorb. Chlorophyll (Chl) a was observed to be relatively more sensitive to leaf senescence than Chl b and carotenoids. Furthermore, the various spectral in vivo forms of Chl a, did not degrade to a similar extent; the far red absorbing forms of Chl a including species that absorb maximally at 692 nm (Chl a-692), 700 nm (Chl a-700) and 708 nm (Chl a 708) were found to be extremely sensitive to senescence induced losses. Both attached and detached senscing primary wheat leaves exhibited nearly similar pattern in the loss of photosynthetic pigments which suggests that the loss in long wavelength absorbing forms of Chl a is a selective indicator of leaf senescence.     

Spectrophotometric titrations of ferricytochrome C with ferrohexacyanide in the pH range 5 to 7

Spectrophotometric titrations were conducted on the system horse heart ferricytochromec plus ferrohexacyanide in the pH range 5 to 7 and at temperatures 8, 18, 22 and 28°C. A difference extinction coefficient for reducedvs. oxidized cytochromec at 550 nm of 21 mmol^–1cm^–1 was used in part of the evaluations. On the assumption that only one electron-transferlinked proton dissociation is effective for both ferro- and ferricytochromec in this pH range, various possible models are developed with only three conforming with the experimental pH dependence of the spectrophotometric equilibrium constant. The data conform best to a model with protonic dissociation constants between pH 5 and 7 such that the reduced cytochromec species is at least a factor of 3 more acidic than the one for oxidized cytochromec (with pK_H 6). This interpretation holds least for the data at 22°C, which points to a structural rearrangement at about this temperature (Czerlinski and Bracokova, 1973; Zabinski and Czerlinski, 1974; Zabinski, et al., 1974). While the extinction coefficient of ferrocytochromec shows no significant change with pH and temperature, the one for ferricytochromec does: it is about 5% larger at pH 5 than at pH 7 (550 nm). Graphs for the absorption change of ferricytochromec (pH 7 as reference) document the details over the wavelength range 500 to 750 nm.     

Blue light-induced synthesis of ribulosebisphosphate carboxylase in cultured plant cells

Upon illumination with blue light (350–550 nm) of suspension cultured cells (Nicotiana tabacum var. Samsun) the transition of leucoplasts to functional chloroplasts is induced. During the subsequent greening period chlorophylls as well as membrane and enzyme proteins are synthesized. Thus the amount of ribulosebisphosphate carboxylase (EC. 4.1.1.39) being small in leucoplasts increases dramatically due to de novo synthesis. This change is also reflected in the level of translatable messenger RNA specific for the small subunit of ribulosebisphosphate carboxylase which accumulates only in blue-irradiated cells; its in vitro translation product isolated by immunoprecipitation corresponds mainly to the precursor protein (Mr 20 000) of the small subunit. In contrast, red light (600–700 nm) does not induce synthesis of ribulosebisphosphate carboxylase. According to these findings it is proposed that blue light exerts its influence on ribulosebisphosphate carboxylase in cultured tobacco cells at a level below translation.     

The effect of temperature on the ethanol tolerance of the yeast,Saccharomyces uvarum

The optimum temperature for fermentation by Saccharomyces uvarum was found to be higher than that for its growth. Fermentation continued at temperatures above the growth maximum (40°C). S.uvarum was most resistant to growth inhibition by ethanol at temperatures 5°C and 10°C below its growth optimum (35°C). Fermentation became more resistant to ethanol inhibition with increasing temperature.     

The effect of the H2 partial pressure on the metabolite pattern ofLactobacillus casei,Escherichia coli andClostridium butyricum

Summary The metabolite pattern of batch cultures ofLactobacillus casei LMG 6400,Clostridium butyricum LMG 1213t1 andEscherichia coli LMG 2093 was effected only for the latter organism when the H₂ partial pressure was below 1 atmosphere: high hydrogen partial pressures increased the formate formation, low pressures gave rise to increased acetate production and higher cell yields.     

Species specific shoot regeneration response of cotyledonary explants of Brassicas

A study of shoot regeneration from cotyledons of three basic diploid species of Brassica, B. campestris (AA), B. nigra (BB), B. oleracea (CC) and their amphidiploids B. juncea (AABB), B. napus (AACC) and B. carinata (BBCC) showed species-specific responses for in vitro shoot regeneration. Analysis of the species mean shoot regeneration response over a range of growth regulator combinations revealed that i) B. campestris is the lowest regenerating species, ii) B. nigra and B. oleracea regenerate with high frequencies, iii) In amphidiploids, the presence of B. campestris component brings down shoot regeneration frequency below the value of B. oleracea in B. napus combination and is additive of the combining genomes in B. juncea combination. In B. carinata regeneration frequencies are less than the parental diploid species, iv) Significant intraspecific genotypic differences were observed for B. nigra and B. oleracea among diploids and B. juncea and B. carinata among amphidiploids, when cotyledons of eighteen genotypes were tested in one growth regulator combination.Abbreviations MS Murashige and Skoog (1962) - NAA -naphthalene acetic acid - IAA Indole 3-acetic acid - BA 6-Benzyl aminopurine     

A nuclear polyhedrosis virus ofHyphantria cunea replicatesin vitro

Summary A nuclear polyhedrosis virus ofHyphantria cunea replicated successfully in theTrichoplusia ni cell line. Restriction endonuclease analysis of the viral DNA obtained from infected cell culture showed the same general homogeneity as that from virus isolated from diseased host larvae. Electron microscopic observations showed that the occluded virus from cell culture consists of rod-like nucleocapsids (31×320 nm) enveloped in aggregates and embedded in polyhedral inclusion bodies from 0.6 to 2.5 m in diameter.     

<Emphasis Type="Italic">Yersinia enterocolitica</Emphasis> type III secretion: Evidence for the ability to transport proteins that are folded prior to secretion

Background  

Pathogenic Yersinia species (Y. enterocolitica, Y. pestis, Y. pseudotuberculosis) share a type three secretion system (TTSS) which allows translocation of effector proteins (called Yops) into host cells. It is believed that proteins are delivered through a hollow needle with an inner diameter of 2–3 nm. Thus transport seems to require substrates which are essentially unfolded. Recent work from different groups suggests that the Yersinia TTSS cannot accommodate substrates which are folded prior to secretion. It was suggested that folding is prevented either by co-translational secretion or by the assistance of specific Yop chaperones (called Sycs).     

Radiationless transitions as a protection mechanism against photoinhibition in higher plants and a red alga

Exposure of the red alga Porphyra perforata or leaves of Phytolacca americana and Echinodorus sp. to white light equivalent to full sunlight for short periods induced large decreases of variable fluorescence measured at 695 nm at 77K. This change was not produced by photoinhibition but rather appeared to result from an inorease in the rate constant of radiationless transition in the reaction centers of photosystem II. It is proposed that this increase is related to the formation of the high energy state which serves as a photoprotective mechanism in plants.     

Ferritin readings in young adult,female university student recreational runners

BackgroundElite female athletes have shown vulnerability to various degrees of iron deficiency. Less is known about recreational fitness exercisers. A study was done to examine plasma ferritin, an assessor of iron status, in young adult, university student fitness runners.MethodsThe present study examined serum ferritin concentrations, an indicator of iron status, in 39 female university students (age 18–25) who ran for fitness, but ran less than competition runners. Selected subjects all reported themselves as not anemic.ResultsMean + SD for 3 mile run time was 26.25 + 3.0 min. The mean ferritin reading was low: 12.4 + 12.3 ng/mL (+ SD). Out of the 39 women, 29 had readings that fell below 15 ng/mL, which some consider the cutoff for iron deficiency. In addition, all but 2 subjects had values below 35, which has been proposed as Stage 1 iron deficiency for athletes. Ferritin levels did not correlate with 3 mile run times (Pearson correlation coefficient, P > 0.05). A 1 mo intervention with 3 minerals that included iron (36 mg/day) significantly raised ferritin values when the iron was bisglycinate (p < 0.05), but not when it was ferrous sulfate (p > 0.05).ConclusionIn this study, a degree of iron deficiency was seen in most of a group of female fitness runners (each of whom had self reported as not being anemic).     

Cadmium adsorption by bacterial capsular polysaccharide coatings

Conclusions Excretion of a polysaccharide capsular coating byP.putida provided enhanced cadmium uptake when compared to the noncapsularP.cruciviae. As this advantage is most significant for cadmium concentrations below 2.5 mg/l, levels which are commonly found in waste discharges, it does suggest a potential role for extracellular polysaccharide producers as biosorbents. These encouraging results have led to further work to determine the desorption characteristics, by pH adjustment, ofP.putida along with long term viability after successive cycles of adsorption and desorption.     

Chemical modification of lipase with ferromagnetic modifier — A ferromagnetic-modified lipase

Summary A ferromagnetic modifier was prepared by reacting ferrous(Fe²⁺)- and ferric(Fe³⁺)-ions with polyethylene glycol having two carboxyl groups (MW:2000) at pH 8.0–8.5. Lipase fromPseudomonas fragi 22–39B was coupled with the modifier using water-soluble carbodiimide. The modified lipase, which was dispersed into buffered solutions in the size range of 30–70 nm, exerted the hydrolytic activity of 8.0 U/mg. In a magnetic field of 250 Oe, the ferromagnetic-modified lipase was readily recovered from the colloidal solution.     

Dichroism of chlorophyll aI absorption change at 700 nm using chloroplastsoriented in a magnetic field.

Using spinach chloroplasts oriented in a magnetic field we have measured the dichroism of the photo-induced absorption change associated with chlorophyll a_I at 700 nm. The greatest absorption change was detected when the electric vector of the measuring beam was polarized parallel to the plane of the photosynthetic membranes. The large dichroic ratio (2.3 ± .1) measured at 700 nm indicates that the transition oscillator involved at this wavelength is nearly parallel to the plane of the photosynthetic membrane. This result is consistent with an earlier study by Junge and Eckhof.     

Inducibility of benzoate oxidizing cell activities in Acinetobacter calcoaceticus strain Bs 5 by chlorobenzoates as influenced by the position of chlorine atoms and the inducer concentration

Summary Among four chlorobenzoates tested, only 3-chlorobenzoate and 4-chlorobenzoate were capable of inducing benzoate oxidizing cell activities in Acinetobacter calcoaceticus strain Bs 5, whereas 2-chlorobenzoate and 2,6-dichlorobenzoate were not. With the monochlorobenzoates, this inducing capability decreased with increasing proximity of the chlorine atom to the carboxyl group, i.e. in the order: 4-chlorobenzoate > 3-chlorobenzoate > 2-chlorobenzoate. It is therefore supposed that the induction of benzoate oxidizing cell activities is inhibited primarily be sterical influences of the chlorine substituents of the various chlorobenzoates.With decreasing concentration of 3-chlorobenzoate and 4-chlorobenzoate, the induction of benzoate oxidizing cell activities decreased. Below a critical concentration of 1 M, these activities were no longer detectable in the cells of Acinetobacter calcoaceticus, with the consequence that below this concentration limit, the degradation of 3-chlorobenzoate and 4-chlorobenzoate was no longer possible.     

The structural periodicity ofE. coli ribosomal proteins

It is established that the sequences of all different proteins fromE. coli ribosome as well as two protein biosynthesis initiation factors, two ribosome-associated DNA-binding proteins, and the elongation factor EF-Tu from the same source possess a periodicity expressed more weakly and different from that found earlier for a number of proteins representatives of 18 superfamilies. The statistical significance of the periodicity observed was checked by comparing the area below the periodicity curve of every protein examined with that of computer generated sequences having the same amino acid composition and length. The results concerning the proteins from small and large ribosomal subunit are compared. The conclusions support and supplement the concept about the presence of a trend in protein molecular evolution from universal (Gly, Ala) to specialized (Phe, Tyr, Trp, Cys) amino acids.     

An improved method for electroporation in plant protoplasts: infection of tobacco protoplasts by tobacco mosaic virus particles

Conditions of electroporation were optimized for introduction of tobacco mosaic virus (TMV) particles into tobacco mesophyll protoplasts (Nicotiana tabacum L. cv. Petit Havana SR1). Compared with conditions for TMV-RNA uptake, a longer electric pulse was necessary at the same voltage to induce TMV particle entry. Up to 80–90% of the protoplasts were infected with TMV particles after exposure to a 10 msec pulse at 200 V (0.67 KV/cm) in a 0.5 M mannitol solution. Protoplast viability was slightly lower than for controls which did not undergo electroporation. The presence of buffer in the mannitol solution reduced the net voltage in the solution which resulted in a significant decrease of the level of infection. These results suggest that the membrane pores resulting from an electrical pulse were wide enough for TMV particles (300 × 18 nm) to enter protoplasts.     

Photoaffinity labelling of juvenile hormone binding proteins in the cockroach Leucophaeamaderae

The synthesis and testing of several diazocarbonyl JH analogs (diazo JHA) which act as photoaffinity labels for insect juvenile hormone binding proteins are described. The best competitor, 10,11-epoxyfarnesyl diazoacetate, has been shown to irreversibly reduce [³H]-JH III binding to both ovarian and hemolymph JHBP from Leucophaeamaderae after irradiation at 254 nm for 20 seconds. No loss of activity was observed after incubation of JHBP and diazo JHA without irradiation. Protection from photoinactivation by diazo JHA II was achieved by the presence of an equimolar amount of JH III during the photolysis. Photoaffinity labeled proteins show loss of binding capacity without alteration of the binding affinity. This is the first example of the use of a photoaffinity label in the study of JH action on a molecular level, and may become a valuable tool in the elucidation of JH-receptor-chromatin interactions.     

qTROSY – a novel scheme for recovery of the anti-TROSY magnetisation

In TROSY experiments, spin state selection (S³) retains only the single HSQC sub-spectrum with minimal T₂ relaxation and maximal resolution, yet at the cost of eliminating half of the available polarisation as undesired anti-TROSY component. We here introduce queued TROSY (qTROSY) as a novel scheme to partially recover and exploit this anti-TROSY polarisation in two concatenated scans. After initial orthogonal spin state separation (oS³), anti-TROSY polarisation is explicitly stored while its TROSY counterpart follows the desired coherence pathway recorded in a first scan A. The immediately appended scan B then quantitatively converts the recovered anti-TROSY polarisation into a second TROSY spectrum, skipping the time-limiting long reequilibration delay. Both concatenated qTROSY scans thus ideally exploit the full initial polarisation within almost the same measurement time. In practice, T₂ relaxation losses accruing during the coupling evolution delays reduced anti-TROSY polarisation recovery below 40%, obviating sensitivity enhancement through addition of both qTROSY scans; yet, scan B retained a complete scan A spectrum with up to 75% intensity. We therefore propose to employ qTROSY asymmetrically, compacting two separate conventional into one queued TROSY-type experiment with significantly reduced measurement time, implying primarily the concatenation of different three- or higher-dimensional experiments. Both anti-TROSY polarisation recoveries and possible time savings are largest for deuterated and smaller non-deuterated proteins, extending the rentability limit of the TROSY principle towards smaller molecular weights.Supplementary material to this paper is available in electronic form at http://dx.doi.org/10.1007/s10858-005-5618-z     

High-vacuum optical platform for cryo-CLEM (HOPE): A new solution for non-integrated multiscale correlative light and electron microscopy

Cryo-correlative light and electron microscopy (cryo-CLEM) offers a unique way to analyze the high-resolution structural information of cryo-vitrified specimen by cryo-electron microscopy (cryo-EM) with the guide of the search for unique events by cryo-fluorescence microscopy (cryo-FM). To achieve cryo-FM, a trade-off must be made between the temperature and performance of objective lens. The temperature of specimen should be kept below devitrification while the distance between the objective lens and specimen should be short enough for high resolution imaging. Although special objective lens was designed in many current cryo-FM approaches, the unavoided frosting and ice contamination are still affecting the efficiency of cryo-CLEM. In addition, the correlation accuracy between cryo-FM and cryo-EM would be reduced during the current specimen transfer procedure. Here, we report an improved cryo-CLEM technique (high-vacuum optical platform for cryo-CLEM, HOPE) based on a high-vacuum optical stage and a commercial cryo-EM holder. The HOPE stage comprises of a special adapter to suit the cryo-EM holder and a high-vacuum chamber with an anti-contamination system. It provides a clean and enduring environment for cryo specimen, while the normal dry objective lens in room temperature can be used via the optical windows. The ‘touch-free’ specimen transfer via cryo-EM holder allows least specimen deformation and thus maximizes the correlation accuracy between cryo-FM and cryo-EM. Besides, we developed a software to perform semi-automatic cryo-EM acquisition of the target region localized by cryo-FM. Our work provides a new solution for cryo-CLEM and can be adapted for different commercial fluorescence microscope and electron microscope.     

Growth and differentiation of callus cultures of Pinus

Segments of hypocotyl and cotyledons of aseptically-grown seedlings of Pinus strobus L. (white pine) and P. echinata Mill (shortleaf pine) were used as explants for establishing tissue cultures. Growth and differentiation of callus were studied on a modified Murashige and Skoog's medium containing nutrients and plant growth regulators. Meristems below the surface of callus tissue of P. strobus could be induced on media supplemented with -naphthaleneacetic acid alone or in combination with certain other plant growth regulators. Occasionally, differentiation of shoot buds also occurred on callus cultures. These shoot buds could be grown in vitro but roots did not develop.Abbreviations ABA abscisic acid - BA 6-Benzyl-aminopurine - 2-ip N⁶-(²-isopentanyl)-adenine - GD Gresshoff and Doy's medium - GE Gamborg and Eveleigh's medium - MS Modified Murashige and Skoog's medium - NAA -naphthaleneacetic acid - SC Sommer and Caldas' medium - TIBA 2,3,5-Triiodobenzoic acid