ISSN:0932-8629    

DOI:10.1111/j.1438-8677.1994.tb00409.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractDuring an expedition in spring 1992 to Hainandao, an island in the tropical zone of the South China Sea, the daily courses of photoinhibition of different brown algal species and of the seagrassThalassia hemprichiiwere investigated. Experiments were carried out with the new portable chlorophyll fluorometer PAM 2000 (Walz, Germany). As a measure of photoinhibition Fv/Fm was used and as a measure of the photosynthetic yield ΔF/Fm'. Photoinhibition occurred in all algae floating near the water surface and reached its maximum between noon and the early afternoon. In the evening photosynthesis was always fully recovered. The extent of photoinhibition depended on both the depth of the algae and the course of the irradiance during the day. Algae of the sublittoral zone showed only a low degree of photoinhibition at high fluence rates when they were covered by a water column of more than 1 m, even if the water was clear. The seagrassThalassia hemprichiigrew in the middle and upper intertidal zone and showed a significant photoinhibition at low tide only when it was not water‐covered. Apparently, it is able to cope with extreme high light conditions without downregulation of photosynthesis caused by photoinhibiti

ISSN:0932-8629    

DOI:10.1111/j.1438-8677.1994.tb00410.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractPaxillus involutus/Pinus sylvestrismycorrhizae, collected from experimental plots (situated in aPino‐Quercetumforest) treated with cadmium dust, were previously reported to accumulate metals like Cd, P, S, N, Al and Si in vacuolar bodies. The Gomori‐Swift test was applied to the same material to reveal if cysteine‐rich proteins might be involved in element detoxification. Vacuolar deposits of high and low phosphate level were both stained. Higher intensity of the Swift reaction was found in the fungal mycelium from mycorrhizae sampled from polluted plots than in mycorrhizae from unpolluted sites. In both cases a higher intensity of the test was revealed in the host cytoplasm close to the Hartig net than in internal parts of roots. Different intensities of the Gomori‐Swift reaction were also observed when the Hartig net was compared to the fungal mantle. A PATAg test was additionally processed and revealed an accumulation of glycogen in rosettes and net‐like structures when samples from cadmium dust treated plots were

ISSN:0932-8629    

DOI:10.1111/j.1438-8677.1994.tb00411.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractTaking advantage of the sensitivity, the lateral resolution and the ability of secondary ion mass spectrometry (SIMS) for elemental imaging, we have shown that the main alkaline and alkaline‐earth cations exhibited clear‐cut regionalization in flax seeds. Calcium, and even more magnesium were almost exclusively located within the protein bodies (PBs); and they were practically absent from the tissue areas with no PBs, such as the provascular tissue. By contrast, sodium was almost exclusively located outside the PBs; moreover, most of the seed sodium was in the tissues at the seed periphery (chiefly the teguments). Among the studied cations, potassium was the only one with a non‐negligible concentration both in and outside th

ISSN:0932-8629    

DOI:10.1111/j.1438-8677.1994.tb00412.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractInfrared laser traps (optical tweezers) were used to study laser‐induced organelle movements in the marine algaPyrocystis noctiluca(Dinophyta). These cells are highly suitable for optical micromanipulation due to their large size and extensive vacuole. Experiments were done with plastids held by optical tweezers and moved from the nuclear area into the vacuole. The subsequent retraction movement was analysed for speed. The displaced organelles remained connected to their original position by a thin cytoplasmic strand, often less than 1 μm in diameter. When the organelles were released they rapidly returned at an initial rate of 81.7 ± 7.8 μm . s−1(overall displacement 50 μm, measured distance 20 μm, 25 °C ± 1 °C, number of cells 22), slowing down with progressive retraction of the connecting strand. The return movement was reduced to 4.2 ± 0.2 μ .s−1(n = 10) when the organelles were displaced and held for 1 min. Displacement to a longer distance increased the rate of return movement. A change from a high to a low environmental temperature significantly reduced movement from 94.5 ± 9.0 . s−1(30 °C ± 1 °C, n = 22) to 34.5 ± 2.7 μm .s−1(5°C ± 1 °C, n = 22). Nocodazole and N‐ethylmaleimide (NEM), inhibitors of microtubules and acto‐myosin, respectively, did not affect the retraction of the connecting strand, but at high concentrations of NEM it became increasingly difficult to move organelles away from the nuclear area. We suggest that the return movement of organelles within laser‐induced artificial strands mainly depends on the viscoelastic properties of the tonoplast. The quantification of these properties by optical tweezers allows determination of reactions of

ISSN:0932-8629    

DOI:10.1111/j.1438-8677.1994.tb00413.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractIn developingOenothera odorataseedlings, phytochrome‐mediated accumulation of various flavonoids (mainly glycosides of cyanidin and quercetin) is detectable, subsequent to a transient induction of the key enzymes of the general phenylpropanoid metabolism, L‐phenylalanine ammonia lyase (PAL) and of flavonoid biosynthesis, chalcone synthase (CHS). Organ‐ and tissue‐specific distribution of these enzymes and of the flavonoid end products was investigated in seedlings, irradiated with continuous far‐red light.Anthocyanins and quercetin glycosides are mainly localized in both the upper and lower epidermis of the cotyledons and to a lesser extent also in the epidermal cell layer of the hypocotyl. An obvious organ‐specific distribution was observed for the anthocyanins: cyanidin‐3,5‐O‐diglucoside accumulates in the epidermal cells of the cotyledons, whereas cyanidin‐3‐O‐glucoside is restricted to the epidermis of the hypocotyl. By contrast the pattern of quercetin glycosides is the same in the cotyledons and in the hypocotyl. The methylated flavonol aglycone 3‐0‐methylquercetin was found to be localized in the seed coat. According to this organ‐ and tissue‐specific pattern of flavonoids, immunochemical and immunohistochemical detection of PAL and CHS revealed a predominant localization of theenzymes in the epidermal layers of the cotyledons and the hypocotyl but also in the cells surrounding the vascular bundles. The role of compartmentation in regulation of flavonoid biosynthesis and putative functions of fl

ISSN:0932-8629    

DOI:10.1111/j.1438-8677.1994.tb00414.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractThe number of pollen sacs per anther and their position have traditionally been among the most important systematic characters in the Lauraceae. Opinions differ, however, about the evolutionary direction in these characters. This paper is intended to draw attention to little known morphological features of the stamens, in particular to transitions between disporangiate and tetrasporangiate anthers. In addition, the phylogenetic derivation of the stamen appendages is discussed. It is hypothesized that branched androecial structures may be primitive within the Laurales, if not in the angiosperms as a whole.

ISSN:0932-8629    

DOI:10.1111/j.1438-8677.1994.tb00415.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

ISSN:0932-8629    

DOI:10.1111/j.1438-8677.1994.tb00416.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY