ERRATA

Page 806, Preparation of Mitochondrial Fraction, line 4: The following should be inserted between ‘centrifugedat’ and ‘20 000 g for’: 3000 for 10 mm. Thesupernatant was centrifuged at The following corrections are required: Page 104, line 20: ‘2-hydroxylation’ should read ‘2-ß3-hydroxylation’ Page 106, line 11: ‘of Ga₈’ should read ‘to GA₈’ Page 113, last line:‘length 50 µm’ shouldread ‘length 150 µm’ Formula 15 should read: Formula 17 should read: y(0)– y^* = ß₁V₁+ß₂V₂ page 118: Formula 18 should read: Formula 23 should read: Formula 24 should read:      

The Effects of Salinity upon Galactosyl-Glycerol Content and Concentration of the Marine Red Alga Porphyra purpurea (Roth) C.Ag.

Changes in the major alcohol-soluble, low molecular weight carbohydratesof P. purpurea, O--D-galactopyranosyl-(1-2)-glycerol (‘floridoside’)and O--D-galactopyranosyl-(1-1)-glycerol (‘isofloridoside’),have been examined in response to salinity variation. ‘Floridoside’is shown to vary in absolute amount, increasing in hypersalineand decreasing in hyposaline media. ‘Isofloridoside’content per cell does not change in a similar manner. Responsesare almost identical under light or dark conditions, ‘floridoside’changes being complete within 24 h. Decreasing the externalwater potential using ionic and non-ionic solutes has the sameeffect upon galactosyl-glycerol content. The amount of ‘floridoside’synthesized, and degraded under hypersaline and hyposaline conditionsrespectively is shown to be insufficient to restore cell volumeto its original value. It is therefore suggested that the primaryfunction of ‘floridoside’ increases in concentratedsea-waters is that of a compatible solute, serving to protectthe cell during periods when the external salt content is increaseddramatically.     

Plant biotechnology: the genetic manipulation of plants. * Slater A, Scott N, Fowler M. 2003 Oxford: Oxford University Press. {pound}19.99 (softback). 346 pp.

Few areas of science have progressed as rapidly, or have hadsuch an impact on public consciousness and governments, as recentadvances in plant biotechnology. These exciting scientific discoveriesand their increasing application are continuing to generateconsiderable economic, social and ethical considerations. Particularconcerns have been expressed, however, about potential ‘foodsafety’ and ‘environmental impact’ implications,in particular, of this ‘revolution in biology’ inagriculture and the food     

The plant cytoskeleton in cell differentiation and development. Annual Plant Reviews, volume 10. * Hussey PJ, ed. 2004. * Oxford: Blackwell Publishing/Boca Raton: CRC Press. * {pound}99{middle dot}50 (hardback). 325 pp

Over 40 years ago, in what is surelyone of the most famous ‘throw-away lines’ in botany,Ledbetter and Porter (1963) suggested that the similar orientationsof cytoplasmic microtubules and structures considered to becellulose microfibrils in the cell wall was not coincidental.This notion led almost single-handedly to the present and enduringinterest amongst certain plant cell biologists in understandingthe role of microtubules in wall formation. And as a resultof this intense interest in such matters, it has become clearthat microtubules are not only ‘just one’ componentamongst an ever-expanding array of     

Margaret Mee's Amazon. Diaries of an artist explorer. * Margaret Mee. 2003. * Woodbridge Suffolk, UK: Antique Collectors' Club. * {pound}29{middle dot}50 (hardback). 320 pp, 400 colour illustrations

‘Delight’ said CharlesDarwin in his diaries in 1832, ‘is a weak term to expressthe feelings of a naturalist who, for the first time, has wanderedby himself in a Brazilian forest’. These feelings musthave been those which drove Margaret Mee to explore the Brazilianjungles on numerous expeditions between 1958 and 1964, creatingwonderful pictures despite all kinds of difficulties encounteredin this hostile world. And these feelings were also those Ihad when I read this book: delight about her precise drawingsand life-like paintings, which are extremely expressive from     

Molecular ecotoxicology of plants. Ecological Studies Vol. 170. * Sandermann H. ed. 2004. * Berlin: Springer. $89{middle dot}95 (hard cover). 241 pp.

Googling the term‘molecular ecotoxicology’ results in less than 1000hits compared to more than 8·5 million for ‘moleculargenetics’. Hence, we are dealing with a rather new orless well-defined and less propagated field of science. Springer'sbook Molecular ecotoxicology of plants edited by H. Sandermannmay therefore fill a gap and it is unique in focusing on plants.A first introductory chapter sets the stage and tries to definethe term for a broad     

Factors Affecting the Abscission of Reproductive Organs in Yellow Lupins (Lupinus luteus L.): III. ENDOGENOUS GROWTH SUBSTANCES IN VIRUS-INFECTED AND HEALTHY PLANTS AND THEIR EFFECT ON ABSCISSION

Extracts of small and mature-size lupin pods yielded four substancesaffecting the growth of wheat-coleoptile sections: one acidpromotor (A), two acid inhibitors(B and X), and one neutralinhibitor(Y). Inhibitor B was extremely active, however, coleoptile sectionsshowed no signs of toxic effects; they resumed growth at a rapidrate after rinsing them and adding ß-indolylaceticand (IAA) to the medium. 1 µg of IAA was required to counteractthe effect of ‘B’ extracted from 230 mg. Of tissue.On an equal fresh weight basis the inhibiting action of ‘B’in lupin pods was 500–1,500 times more potent than thatof ‘inhibitor ß’ in etiolated pea seedlings. Small pods of plants infected with pea-mosaic virus yielded3 times the amount of ‘A’ of healthy plants (equivalentto 1 µg. IAA 0.3 µg. IAA per 25 g. of tissue respectively),and approximately the amount of ‘B’. Mature podsof virus-infected plants again yielded more‘A’,but also 2? times more ‘B’ than pods of healthyplants. Healthy pods yielded more ‘A’ than virus-infectedpods, and there was no difference in ‘X’. A lupin abscission test was developed and the effects of proximaland distal application of -naphthyl acetic acid (NAA) are presented,and discussed with respect to results of other abscission tests. ‘A’ accelerated abscission when applied proximally,and delayed or prevented it when applied distally. ‘B’strongly accelerated abscission when applied in either way.A possible mechanism explaining the abscission-inducing effectof developing pods on later flowers is discussed in terms ofthe substances ‘A’ and ‘B’. The partlyprevented abscission observed on virus-infected plants was foundto agree well with the proposed mechanism.     

Instant notes in plant biology, 2nd edn. * Lack A, Evans D. 2005. * Oxford: Taylor and Francis. {pound}18.99 (paperback). 351 pp.

The ‘InstantNotes’ series from Bios will probably be familiar to manyreaders. The series' success is evident in the second editionsthat are appearing, e.g. the current volume—albeit nowunder the Taylor and Francis label. Content This book does what it says on the label; it provides noteson (probably) all of the topics within the compass of present-day‘plant biology’. Primarily, it deals with anatomy,growth and development, physiology, reproduction, and economicuses and ecology of flowering plants (angiosperms). However,it does cover other phyla of the Kingdom Plantae (principallyin two ‘taxonomy/evolution’ sections), and algae(along     

Plant roots. Growth, activity and interaction with soils

It is (or should be) self-evident that life on Earth dependsmainly on life in earth, and in this respect soil–plantinteractions are of key importance. This book brings togetherareas that are still often compartmented into fields such aschemical and physical aspects of soil science (where plantsare still sometimes regarded as a ‘black box’ ofuncertain relevance), plant physiology (now sometimes re-badgedas plant functional biology), and soil microbial ecology. Agriculturalscientists have, of course, rarely been guilty of ignoring soilfactors in relation to plant growth and productivity. Plantecologists sometimes have, and to some of them it's the soilthat is the ‘black box’ when it comes to understandingplant population and community ecology. Models of the     

Plant ecology. * Schulze ED, Beck E, Muller-Hohenstein K. 2005. Berlin/Heidelberg: Springer. $89{middle dot}95 (hardback). 702 pp.

This book (a translation fromSchulze et al., 2002) is one of the most comprehensive textbooksof plant ecology so far. The authors aim to ‘for the firsttime bring together and clearly organize the large subdisciplinesof plant ecology’ and, to a large extent they have succeeded.The book is well written, and its more than 500 illustrationsare beautifully laid out and well chosen to help the readerunderstand the theory. It is clearly suitable not only     

Homeostasis in Nitrogenous Uptake/Assimilation by the Green Alga Platymonas (Tetraselmis) striata (Prasinophyceae)

When nitrate, ammonium, or urea were the sole nitrogen sourcesfor the growth of Platymonas striata there was a short initiallag period, after which uptake/assimilation occurred at a constantrate. Glycine ‘uptake’ was however non-linear withtime. Addition of ammonium or urea markedly inhibited nitrate‘uptake’ whereas although glycine was initiallytotally inhibitory, nitrate ‘uptake’ recommencedabout 1 h after addition, but at a greatly reduced rate. Ammoniumtotally inhibited urea ‘uptake’, but did not inhibitglycine ‘uptake’. When ammonium, urea, or glycinewere present at the same time as nitrate the total rate of nitrogen'uptake/assimilation was within 40% (or closer) of that of nitratenitrogen ‘uptake’ alone. In the first two casesthis reflected a total switching off of nitrate ‘uptake’whilst the new substrate was assimilated at a rate similar tothe initial nitrate rate, whereas in the case of glycine, bothsubstrates were used simultaneously. Once the concentrationof any of the inhibitory nitrogen sources had been reduced toa low level the ‘uptake’/assimilation of nitraterecommenced. It is suggested that the ability of P. striatato maintain a more or less constant rate total nitrogen ‘uptake’/assimilationirrespective of the mixture of utilizable nitrogen sources presentedto it, is not due to controls at the level of the entry of substrateinto the cell, but to intracellular actions at the enzyme level.The relative constancy of, and high rate of ‘uptake’,irrespective of nitrogen source and over a wide range of extracellularconcentrations, is tentatively considered to be due to saturationof the assimilatory mechanisms under the conditions employed;all the sources lead, either directly or indirectly, to theproduction of amino groupings for entry into nitrogenous metabolism.This homeostasis of nitrogen ‘uptake’/assimilationwould clearly be of considerable benefit to the alga in nature,enabling it to maximize growth in changing environmental conditions. Platymonas striata, nitrogen update, nitrogen assimilation     

Confronting complexity: reply to Le Quere and Flynn

Complexity pervades ecology. The search for unifying laws thereforeentails that ‘biologists work very close to the frontierbetween bewilderment and understanding’ (Medawar, 1969).One approach to developing ecological theory is to abandon simplicityat the outset and operate at the highest appropriate organizationallevel (Dunbar, 1980). On this basis, Le Quéré(Le Quéré, 2006) issues a plea for inclusion ofplankton functional types (PFTs) in plankton models because‘we will not understand ecology until we     

Occurrence of mycosporine-like amino acids in the red-tide dinoflagellate Alexandrium excavatum: UV-photoprotective compounds?

Water extracts of the red-tide dinoflagellate Alexandrium excavatumgrown at ‘high’ light intensity (200 µE m^–2s^–1) show a broad absorbance maximum in the UV regionof the spectrum (310–360 nm). Using TLC and reverse-phaseHPLC a series of mycosporine-like amino acids have been characterized:mycosporine-glycine (_max = 310 nm), palythine (_max = 320 nm),asterina-330 (_max = 330 nm), shinorine (_max = 334 nm), porphyra-334(_max= 334 nm), palythenic acid (_max = 337 nm) and the isomericmixture of usujirene and palythene (_max = 359 nm). From theobserved spectral changes during transference from ‘low’(20 µE m^–2 s^–1) to ‘high’ (200µE m^–2 s^–1) light intensities and vice versa,the series of compounds are supposed to be biogenically relatedto one another. The presence of these compounds in A.excavatumis discussed in relation to their possible role in the photoprotectionto deleterious UV radiation.     

Concentration-dependent changes of perceived odor quality

In order to assess the dependence of perceived odor qualityon odorant concentration, we studied 21 subjects. For eightsubjects all possible pairs from a pool of six odorants at threedecimal dilutions were presented, and subjects were requestedto state whether members of the pair were qualitatively ‘similar’or ‘different’ It was found that while pairs withthe same odorant at identical concentrations were judged ‘similar’in >90% of the cases by all subjects, scores went down to10% ‘similar’ judgements in some cases when thesame odorant was presented at a 100-fold concentration difference.Large time-invariable differences were found among subjectsand among odorants. For the additional 13 subjects, all possiblepairs from a pool of four odorants at three decimal dilutionswere presented. Subjects were instructed to state whether membersof the pair were qualitatively ‘same’ or ‘different’,and were also requested to rank the degree of difference ona visual analogue scale. Results for this group were, in general,similar to the results of the former group of subjects and goodagreement between the two tasks was found. The results suggestthat variations in olfactory stimulus magnitude may be perceivedas quality differences, as previously shown for vision and audition.     

Effect of Temperature on the Radial Exchange of Labelled Water in Maize Roots

The temperature dependence of the efflux kinetics of labelledwater in isolated maize roots has been studied. The purposeof these experiments was to obtain the energy of activation,E (kcal/mole), of the rate-limiting step in this radial exchangeprocess under various experimental conditions. Estimates ofE were obtained from linear relations between ln{D'_w} and thereciprocal of the absolute temperature; values of the apparentdiffusion coefficient, D'_w, of labelled water in the root werefound from an analytical treatment of the efflux data in termsof a cylindrical diffusion model. The energy of activation forlabelled-water exchange in normal roots was 14.9 kcal/mole.The corresponding value for ‘dead’ (boiled) rootswas 3.9 kcal/mole. These values of E substantiate the view thatin normal roots the penetration of water across the membranesof the root cells constitutes the rate-determining step in theefflux whereas in ‘dead’ roots extracellular diffusionof water is the source of rate-control. Similar temperature dependence studies were performed on theefflux kinetics from normal and ‘dead’ roots treatedwith 10^–5 M phenylmercuric acetate (PMA). The energiesof activation for labelled-water exchange in normal and ‘dead’roots under these conditions were respectively 15.5 and 5.3kcal/mole. Moreover, the results of the efflux experiments onPMA-treated roots were considered to indicate that this inhibitorproduces an alteration in some structural aspect of the rate-controlling‘membranes’.     

Impedance Spectroscopy in Frost Hardiness Evaluation of Rhododendron Leaves

Impedance spectroscopy was used in studying frost hardinessof leaves of two diploid rhododendron cultivars, RhododendronL. ‘PJM’ and R. ‘Cunningham's White’,and their tetraploid derivatives, R. ‘Northern Starburst’(NSB) and CW4. After the growing season and initial hardeningin a greenhouse, plants were subjected to an acclimation regimein a phytotron: 3 consecutive weeks at +5, +1 and -2°C each.Hardiness was studied with controlled freezing tests beforeeach decrease in temperature and at the end of the experiment,based on data of extracellular resistance r_eand relaxation time of the frost-exposed leaves. The correlation of the two estimateswas 0.92. Generally, the diploid clones had better frost hardinessthan the tetraploid clones. At the end of the experiment, frosthardiness of the diploid ‘PJM’ was -28.7°C andthat of the tetraploid NSB -20.6°C. Leaves of the diploid‘Cunningham's White’ and of the tetraploid CW4 hardenedto -32.0°C and -20.9°C, respectively. Frost hardinessestimated by impedance spectroscopy correlated well with earlierresults based on visual scoring (r = 0.81–0.86) and electrolyteleakage tests (r = 0.84–0.90), but results from impedancespectroscopy indicated weaker hardiness than the other tests.The difference between the results from impedance spectroscopyand the other tests was smaller and more coherent within the‘Cunningham's White’ clones than within ‘PJM’and NSB. Changes in extracellular and intracellular resistanceof non-frozen leaves during the acclimation correlated withthe changes in frost hardiness of ‘Cunningham's White’clones, but not with those of ‘PJM’ and NSB, whichbelong to another subspecies.Copyright 2000 Annals of BotanyCompany Cold resistance, evergreen, frost hardiness, impedance spectroscopy, polyploid, Rhododendron, tetraploid     

An introduction to plant structure and development * Beck CB. 2005. * Cambridge, UK: Cambridge University Press. {pound}30.00 (hardback). 464 pp.

This book has beenwritten primarily as a text for a senior plant anatomy course.The initial phrase ‘An introduction to’ is somewhatmisleading as a student would need to have some elementary knowledgeof botany as well as cell structure and physiology to followthe information and the ideas without difficulty. The authordoes     

Studies in Stomatal Behaviour: VII. EFFECTS OF ANAEROBIC CONDITIONS UPON STOMATAL MOVEMENT--A TEST OF WILLIAMS'S HYPOTHESIS OF STOMATAL MECHANISM

An experiment was carried out to investigate stomatal responsesin wheat to four ‘closing treatments’, viz. highcarbon dioxide concentration, darkness, dry air and nil, eachgiven under both aerobic and anaerobic conditions. Thus theeffect of lack of oxygen on the closing (or opening) tendencywas estimated. Changes in calculated from resistance porometer readings were used as data and reasonsare given for thinking this is the best available measure forinvestigating stomatal dynamics in wheat. Williams's hypothesisdemands that lack of oxygen should cause stomatal opening orprevent closure; the present experiment shows that anaerobicconditions significantly increase the closing tendency when‘closing treatments’ are first applied. There isalso some suggestion that oxygen-lack itself tends to causeclosure in the absence of any other ‘closing treatment’.Williams's hypothesis in its original form is thus disproved(for wheat) but the present results would be consistent withan ‘active’ uptake of water by the guard cells contributingto stomatal opening. A nearly significant interaction betweencarbon dioxide and oxygen suggests that under anaerobic conditionsa ‘closing substance’ may perhaps be formed, forexample, by the union of some intermediate in glycolysis withcarbon dioxide.     

Changes in the Pollen Grain Wall of Linum grandiflorum following Compatible and Incompatible Intraspecific Pollinations

The exine surrounding the colpal furrows in the pollen grainsof Linum grandiflorum is rapidly degraded following the twocompatible pollinations between ‘pin’ and ‘thrum’types of flower and also following the incompatible pollinationbetween ‘thrum’ and ‘thrum’. In allthese pollinations the pollen germinates normally. Exine isnot degraded in the incompatible pollination between ‘pin’and ‘pin’. In this pollination the pollen does notswell or germinate. The exine degradation is restricted to thecolpal regions. Hydration of the pollen grain by buffer solutionwithout contact with the stigma also stimulates the degradationof the exine. The erosion of the exine reveals a fibrous, PAS-positivematrix which follows the original contours of the exine. Vesicles are discharged into the intinc following pollination;these appear to contribute their contents to the intine-likewall which eventually invests the pollen tube. The observations are interpreted by assuming:

1. 1. an enzyme situatedwithin the pollen and localized underthe colpi; this enzymeis active after hydration;
2. 2. the degradation is a means bywhich colpal furrows are enlargedto permit the emergence ofthe pollen tube;
3. 3. the degradation process both by bufferand on the stigmais purely the consequence of hydration andis only secondarilyrelated to incompatibility through the ‘pin’by‘pin’ pollination not permitting hydration ofthepollen.