Co-nutrient limitation of diatom growth under nitrogen or silicon limitation. A reply to the paper of Flynn and Martin-Jezequel

Flynn and Martin-Jézéquel (J. Plankton Res., 22,447–472, 2000) derived a mechanistic model for nitrogenand silicon physiology of diatoms. During their analysis, theycompared the output of this model with that of the co-nutrientmodel of Davidson and Gurney (J. Plankton Res., 21, 839–858,1999). They highlighted some discrepancies between the predictionsof the two models, which occurred subsequent to exhaustion ofthe yield-limiting nutrient, and suggested that the co-nutrientmodel contained technical inaccuracies in its output. Here itis shown that by simply modifying the numerical values of twoof the parameters of the co-nutrient model, while retainingexactly the same model structure, it is possible to producesimilar dynamics to those exhibited by the model of Flynn andMartin-Jézéquel.     

Influence of the 3'-UTR-length of mKIAA cDNAs and their Sequence Features to the mRNA Expression Level in the Brain

We have previously described the sequence features of 1500 mouseKIAA (mKIAA) genes in comparison with those of human KIAA genes(Okazaki, N., Kikuno, R., Inamoto, S., Hara, Y., Nagase, T.,Ohara, O., and Koga, H. 2002, DNA Res., 9, 179–188; Okazaki,N., Kikuno, R., Ohara, R., Inamoto, S., Aizawa, H., Yuasa, S.,Nakajima, D., Nagase, T., Ohara, O., and Koga, H. 2003, DNARes., 10, 35–48; Okazaki, N., Kikuno, R., Ohara, R., Inamoto,S., Koseki, H., Hiraoka, S., Saga, Y., Nagase, T., Ohara, O.,and Koga, H. 2003, DNA Res., 10, 167–180; and Okazaki,N., F-Kikuno, R., Ohara, R., Inamoto, S., Koseki, H., Hiraoka,S., Saga, Y., Seino, S., Nishimura, M., Kaisho, T., Hoshino,K., Kitamura, H., Nagase, T., Ohara, O., and Koga, H. 2004,DNA Res., 11, 205–218). To validate the orthologous relationshipbetween mKIAA and KIAA genes in detail, we examined their chromosomalpositions and evolutionary rate of synonymous substitutionsand confirmed that >93% of the mKIAA/KIAA gene pairs areorthologous. During the sequence analysis of mKIAA genes, wefound that 3'-untranslated region (3'-UTR) lengths of mKIAAand KIAA genes are extremely long. In the meanwhile, we havealso examined the tissue-specific expression of 1700 mKIAA genesusing cDNA microarray and verified predominantly their expressionin adult brain (Koga, H., Yuasa, S., Nagase, T., Shimada, K.,Nagano, M., Imai, K., Ohara, R., Nakajima, D., Murakami, M.,Kawai, M., Miki, F., Magae, J., Inamoto, S., Okazaki, N., Ohara,O. 2004, DNA Res., 11, 293–304). To connect these twoevidences, we statistically analysed the relationship betweenthem by using the mKIAA genes. Consequently, a positive correlationwas observed between the 3'-UTR lengths and the relative expressionintensities in adult brain. Furthermore, we searched sequenceelements in the 3'-UTR possibly related with their expressionand found some candidates regarding the brain-specific expression.     

ERRATUM

R. MANLY. The larval development of Tricolia pullus (L.)J. moll.Stud. (1976) 42,361–369. The legends of Figs 2 and 3 shouldbe transposed.     

The role of higher predation in plankton population models

Zooplankton mortality in plankton population models is oftenrepresented by the so-called closure term. Recently, much attentionhas been paid to the choice of functional form used for theclosure term, primarily due to the influential paper by Steeleand Henderson (J. Plankton Res., 14, 157–172, 1992). Herewe reveal an inconsistency in the normalization of Steele andHenderson's models, and show that unforced short-term oscillations(limit cycles) can occur when a quadratic closure term is used.Furthermore, we contradict the hypothesis regarding the relationshipbetween nutrient steady-state values and the choice of closureterm: using the seven-component plankton model of Fasham (TheGlobal Carbon Cycle, Heimann,M. (ed.), pp. 457–504, 1993)with four alternative closure terms, we find the nutrient valueto depend more upon the choice of parameter values than on thechoice of closure term. However, our results agree with andstrengthen the general conclusion of Steele and Henderson'swork: that the choice of closure term can strongly influencethe dynamics of models.     

Using a phytoplankton growth model to predict the fractionation of stable carbon isotopes

In the preceding paper in this issue, a phytoplankton growthmodel based on an analogy with chemical kinetics (the CR model)was re-derived, and a comparison made with the growth rate ofcultured phytoplankton assemblages extracted from temperatelakes. In this paper, further derivation of the CR model leadsto the same model of carbon isotope fractionation used by Rauet al. (Mar. Ecol. Prog. Ser., 133, 275–285, 1996). Boththe CR and Rau et al. models are compatible with the observationthat isotope fractionation during phytoplankton growth,     

Development of Acartia bifilosa (Copepoda: Calanoida) eggs in the northern Baltic Sea with specialreference to dormancy

Development of eggs produced by Acartia bifilosa in summer andautumn was studied in the northern Baltic Sea. Resting eggsof the species have previously been found in sediments, andthe aim of this study was to reveal the type of dormancy inthe eggs. Eggs were incubated at temperatures ranging from 1.5to 18°C. The effect of continuous darkness on hatching wasalso tested. Hatching success in the experiments varied between56 and 97%. Egg development was similar in summer and autumn,indicating that A. bifilosa does not produce diapause eggs inthe area. Furthermore, dormancy was not induced at any of thetemperatures tested, nor by darkness. Results are compared withthose of Castro-Longoria and Williams (Castro-Longoria and Williams,1999b, J. Plankton Res., 21, 65–84) who studied A. bifilosain the English Channel, where both production of diapause eggsand arrest of development in the subitaneous eggs at low temperaturesoccurred. The possible causes of the difference in dormancystrategies in the two areas are discussed.     

Modelling the interacting effects of nutrient uptake, light capture and temperature on phytoplankton growth

A model of phytoplankton growth developed by analogy with chemicalkinetics (CR model) in Baird and Emsley (J. Plankton Res., 21,85–126, 1999) is explored further. The CR model parameterizesall biochemical reactions involved in phytoplankton growth byone parameter: the maximum growth rate. Phytoplankton growthrate is then calculated from an interaction of the maximum growthrate, and the physical limit to extracellular nutrient uptakerates and light capture. In this paper, the CR model was re-derived,with two corrections and a number of modifications to increaseits generality. During derivation, the model's behaviour wascompared with chemostat cultures at a variety of dilution rates,nutrient inputs and temperatures. Model output was then plottedagainst observations of a semi-continuous culture of Isochrysisgalbana. Finally, the CR model was used to predict the growthrate of phytoplankton communities extracted from two temperatelakes under varying nutrient, light and temperature regimes.The CR model explained 37% of the variability of phytoplanktongrowth rate in cultures at environmental conditions similarto those of the lakes, compared with 25% explained by a non-linearbest fit to 324 growth experiments. The following paper in thisissue develops the CR model further, using it to predict stablecarbon isotope fractionation.     

Effect of photoinhibition on algal photosynthesis: a dynamic model

Recent evidence from algal physiology and molecular biologyconfirms that photoinhibition is directly related to D1 proteindamage and recovery, and D1 protein damage leads to a decreasein electron transfer or an increase in turnover time of theelectron transfer chain. In this study, the turnover time ofthe electron transfer chain is defined as a function of therelative concentration of D1 protein in reaction centre II andthe photoinhibition processes due to D1 protein degradationare incorporated into a model of photosynthesis, initiated byDubinsky et al. (Plant Cell Physiol., 27, 1335–1349, 1986)and developed by Sakshaug et al. (Limnol. Oceanogr., 34, 198–205,1989). D1 protein damage is assumed to be both light and D1protein concentration dependent, and to be proportional to thecross-section of PSII (     

Climate-induced variability in Calanus marshallae populations

Calanus marshallae is the dominant mesozooplankton copepod speciesover the south-eastern Bering Sea middle shelf. Climate-inducedchanges in the magnitude and timing of production by C. marshallaemay affect the living marine resources of the Bering Sea shelfecosystem. We examined springtime abundance, gonadal maturityand stage distributions of C. marshallae copepodites duringfive consecutive years (1995–1999) that spanned the rangeof variability observed over the past 34 years in terms of watertemperature and ice cover. We compared our results with previouswork conducted during cool (1980) and warm (1981) years [ Smith,S. L. and Vidal, J. (1986) Cont. Shelf Res., 5, 215–239].The spring phytoplankton bloom began relatively early in associationwith ice (1995, 1997, 1999), but began late when ice was absentor retreated early (1996, 1998). Egg production began well beforethe bloom and continued over a long duration. Copepodites, however,were recruited during a relatively short period, coincidentwith the spring phytoplankton bloom. The relationship betweenbrood stock and spring-generation copepodite abundances wasweak. Copepodite concentrations during May were greatest inyears of most southerly ice extent. Copepodite populations werehighly variable among years, reflecting interannual variabilityin the atmosphere–ice–ocean system.     

Parasitic Wasps Learn and Report Diverse Chemicals with Unique Conditionable Behaviors

Chemical Senses, 28, 545–549 Regrettably, an error occurred in Figure 3 of this     

Predator-prey interactions between Isochrysis galbana and Oxyrrhis marina. III. Mathematical modelling of predation and nutrient regeneration

A mathematical model was derived to simulate ingestion, growthand nitrogen (N) regeneration for the phagotrophic dinoflagellateOxyrrhis marina. Two types of experimental study were undertaken:prey-deplete O.marina were supplied with lsochrysis galbanain continuous darkness (thus preventing growth of the prey),and predator-prey interactions were also followed in culturesmaintained in a light-dark cycle (allowing growth of the prey).During light-dark cycles, Oxyrrhis volume increased more inthe light phase than in the dark. Digestion of isochrysis lasted{small tilde}0.3 days. with an average maximum ingestion rateof 55 prey predator–1 day–1 During active predation,30% of Oxyrrhis-carbon (C) was lost from the particulate phase:per day, with this loss falling to 10%: per day at the cessationof herbivory when cannibalism became noticeable. Ingestion wasmodelled as a function of prey density, C-loss and divisionas functions of cellular predator C. with cannibalism by Oxyrrhisalso included. Two N-regeneration expressions were investigated:one proposed by D.A.Caron and J.C.Goldman (Journal of Protozoology.35, 247–249, 1988) and an alternative function which relatedN regeneration to intracellular carbon and N based on the conceptof an optimal Oxyrrhis C:N ratio. The latter was more successfulin simulating batch culture data and did not require a priorcalculation of Oxyrrhis gross growth efficiency. The model ofOxyrrhis numbers, C and N contained only nine parameters whosevalues were fully obtainable from batch culture experiments.By using this model, we were able to use a single parameterset to simulate the transient dynamics of Oxyrrhis ingestingN-replete and N-stressed prey. Further experiments in whichOxyrrhis grew on Isochrysis in light-dark cycles were simulatedby combining the Oxyrrhis model with the nutrient-processingmodel for Isochrysis of K.Davidson et al. (Journal of PlanktonResearch, 15, 351–359, 1993). The dynamics of the fullpredator-prey model were found to be sensitive to the levelof sophistication of the prey model; the Quota model was foundto be less successful than the nutrient-processing prey model.Theoretical model runs indicated the importance of being ableto simulate changes in both prey numbers and biomass, and alsoin including realistic equations for nutrient regeneration frompredators in microbial predator-prey models.     

Effects of Blue Light Pretreatments on Internode Extension Growth in Mustard Seedlings after the Transition to Darkness: Analysis of the Interaction with Phytochrome

The effects of blue light (B) pretreatments on internode extensiongrowth and their possible interaction with phytochrome mediatedresponses were examined in Sinapis alba seedlings grown for11 d under 280 µmol m^–2 s^–1 of continuousblue-deficient light from low pressure sodium lamps (SOX). SupplementaryB (16 µmol m^–2 s^–1) caused no detectable inhibitionof the first internode growth rate under continuous SOX, butgrowth rate was inhibited after transfer to darkness. This effect,and the growth promotion caused by far-red bend-of-day' lightpulses were additive. The addition of B at 16 µmol m^–2s^–1 during 11 d, or only during the first 9 or 10 d orthe latest 0.75, 1 or 2 d of the SOX pretreatment caused approximatelythe same extent of inhibition after the transition to darkness.A single hour of supplementary B before darkness caused morethan 50% of the maximum inhibition. However, 24 h of lower fluencerates of B (4 or 7 µmol m^–2 s^–1) were ineffective.Covering the internode during the supplementary B period didnot prevent the response to B after the transition to darkness.Far-red light given simultaneously with B (instead of the SOXbackground) reduced the inhibitory effect of B. Above a given threshold fluence rate, B perceived mainly inthe leaves inhibits extension growth in subsequent darkness,provided that high phytochrome photo-equilibria are presentduring the irradiation with B. Once triggered, this effect doesnot interact significantly with the ‘end-of-day’phytochrome effect. Key words: Blue light, extension growth, phytochrome     

PETALIFERA HABEI, A NEW SPECIES FROM JAPAN ADDENDUM

Since Petalifera habei was described in the Proceedings, 34,1, 12–18, April 1960, I have received from Dr. K. Babaa short account of the same species in Publ. Seto. mar. biol.Lab. 7, 3, 337–338. December, 1959, under the title "Thegenus Petalifera and a new species, P. ramosa, from Japan".I was unaware that Dr. Baba intended to describe it. As hispaper antedates mine, his name, Petalifera ramosa, must replaceP. Habei.     

A mathematical model of sialylation of N-linked oligosaccharides in the trans-Golgi network

A mathematical model is developed of the compartmentalized sialylationof N-linked oligosaccharides in order to understand and predictthe outcome of sialylation reactions. A set of assumptions arepresented, including Michaelis-Menten-type dependency of reactionrate on the concentration of the glycoprotein substrate. Theresulting model predicts the heterogeneous outcome of a posttranslationaloligosaccharide biosynthesis step, a critical aspect that isnot accounted for in the modeling of the cotranslational attachmentof oligosaccharides to glycosylation sites (Shelikoff et al.,Biotech. Bioeng., 50, 73–90, 1996) or general models ofthe secretion process (Noe and Delenick, J. Cell Sci, 92, 449–459,1989). In the steady-state for the likely case where the concentrationof substrate is much less than the K_m of the sialyltransferase,the model predicts that the extent of sialylation, x, will dependupon the enzyme concentration, enzyme kinetic parameters andsubstrate residence time in the reaction compartment. The valueof x predicted by the model using available literature datais consistent with the values of x that have been recently determinedfor the glycoproteins CD4 (Spellman et al, Biochemistry, 30,2395–2406, 1991) and t-PA (Spellman et al, J. Biol Chem.,264, 14100–14111, 1989) secreted by Chinese hamster ovarycells. For the unsaturated case, the model also predicts thatx is independent of the concentration of secreted glycoproteinin the Golgi. The general modeling approach outlined in thisarticle may be applicable to other glycosylation reactions andposttranslational modifications. model sialylation N-linked glycosylation     

Loss of Olfactory Function Leads to a Decrease of Trigeminal Sensitivity

Healthy controls were compared to patients with decreased olfactorysensitivity (n = 32) to investigate interactions between theolfactory and trigeminal systems. Amplitudes of chemo-somatosensoryevent-related potentials in response to suprathreshold trigeminalstimuli (CO₂) were found to be smaller in patients (P<0.05)indicating a decrease of trigeminally mediated sensations. Chem.Senses 21: 75–79, 1996.     

ERRATA

WARBURG, M. R., 1965. On the water economy of some Australianland snails. Proc. malac. Soc. Lond. 36, 297–305. Page 298: second line from bottom, should read ‘within± 1 µg for Themapupa’. Page 300: Fig. 2 legend, should read ‘Evaporative waterloss from Sinumelon remissum (a), Pleuroxia sp. (b) and Themapupaadelaidae (c)’. Page 300: section 4 heading, should read ‘Continuous curvesfor water loss’. Page 301: second line, for ‘Fig. 9’ read ‘Fig.3’. Page 301: Table 1, last line, for ‘0.120024’ read‘0.12024’. Present address: Israel Institute for Biological Research, Ness-Ziona,Israel.     

Distribution pattern of decapod larvae off the north-western Iberian Peninsula coast (NE Atlantic)

In October 1977 the model of general circulation of the watermasses off the coast of Galicia, and the presence of a coastalupwelling, led to a high primary productivity. This high productivityin turn favoured the development of a rich population of decapodlarvae. The abundance and distribution pattern of these organismswere closely linked (i) to the abundant presence of the correspondingadult species in the area, (ii) with the spatial distributionof phytoplanktonic populations concurrently studied by Estrada[J. Plankton Res ., 6, 417–434 (1984)] and (iii) withthe hydrodynamic pattern in the area. Fifty-two decapod larvaetaxa were identified and Solenocera membranacea, Pisidia longicornis,Pilumnushirtellus and Goneplax rhomboides were the most representativespecies It was observed that the greatest concentrations oflarvae (3387 larvae 10^–2 m^–3) were to be found nearthe mouth of the Rfas Baixas (situated in the south-west ofthe coastal area) and in some zones further out to sea (863larvae 10^–2 m^–3) (due to a process of hydrodynamictransport)     

CORRIGENDA

M. I. BAXTER and R. H. NISBET. Features of the nervous systemand heart of Archachatina revealed by the electron microscopeand by electrophysiological recording. Proc. malac. Soc. Lond.35, 167–177. p. 169, line 3. For (Amoroso et al., 1953) read (Amoroso etal., 1963). p. 176, References 1 and 2. For (In press) read (In preparation). Plates 18 to 31. Read magnification of Plate 18 as x 4200, andthat of remaining plates to nearest 1000.     

Tintinnids and other microzooplankton--seasonal distributions and relationships to resources and hydrography in a Maine estuary

Journal of Plankton Research, 9, 65–77, 1987. In Table II on page 70 the number of Tintinnopsis minuta foundat 0 m depth on 15 September 1981 should be 1200.     

ERRATUM

The publishers apologize for the following errors, which appearedin Plant Geosensors by L. J. Audus (pp. 1051–1073): Page 1058, line 9: the expression should read P = (L²/D)/(l/q) Page 1068, paragraph (c) line 11: should read ‘reticulum, which was fairly uniformly peripheralin vertical roots, aggregated on the’