Morphology and development of anthers and ovules in Croton and Astraea (Euphorbiaceae)

We examined the embryological development of anthers and ovules from Astraea (A. lobata and A. praetervisa) and Croton (C. floribundus, C. fuscescens, C. glandulosus, C. lundianus, C. piptocalyx, C. urucurana and C. triqueter) focusing on features with systematic significance for the group. Some of these features are common in Euphorbiaceae including: a dicotyledonous type of anther wall formation, a secretory tapetum, a mixed origin of the outer ovule integument, an epidermal origin of the inner ovule integument, the occurrence of many archesporial cells inside the ovules and a megagametophyte of the Polygonum‐type. Other features, such as the presence of styloid crystals in the tapetum, an idioblast with a druse in the endothecium, simultaneous and successive microsporogenesis, and a functional micropylar megaspore, have not previously been reported in the family. These characters appear to distinguish Croton and Astraea from other Euphorbiaceae and possibly represents autapomorphies for the tribe Crotoneae.     

Systematics of Serinus canaries and the status of Cape and Yellow-crowned Canaries inferred from mtDNA and morphology

The taxonomy of, and phylogenetic relationships among, African canaries typically assigned to the genus Serinus sensu lato (including the putative genera Alario, Pseudochloroptila, Serinops, Ochrospiza, Dendrospiza and Crithagra) were investigated, based on 823bp of the mitochondrial cytochrome b gene. Two clades emerged: (1) Palaearctic and Afrotropical taxa, including Serinus serinus, S. canaria, A. alario and the S. canicollis complex (S. c. canicollis, thompsonae and flavivertex), and (2) taxa endemic to the Afrotropics comprising Pseudochloroptila, Serinops, Ochrospiza, Poliospiza, Dendrospiza, Poliospiza and Crithagra spp. However, only clade one has jackknife and bootstrap support values above 50. The two clades were separated by Carduelis taxa, suggesting that Serinus sensu lato is not monophyletic. As it stands, the phylogeny does not support the recognition of Alario and Serinops and possibly Ochrospiza, Dendrospiza and Pseudochloroptila (Cape siskins) as distinct genera. Alario is sister to Serinus canicollis whereas the others are intermingled in a clade comprised primarily by Crithagra spp. The use of Serinus is confined to the Palaearctic canaries and allied species, and Crithagra for the strictly Afrotropical clade. Since the cytochrome b sequence divergence between the allopatric Cape (S. [c.] canicollis) and Yellow-crowned (S. [c.] flavivertex) canaries (2.8%) was similar to differences between other closely-related species and there are marked plumage differences between these taxa, we suggest that they be elevated to full species rank.     

Nitrogen-fixation genes and nitrogenase activity in Clostridium acetobutylicum and Clostridium beijerinckii

Several solvent-producing clostridia, including Clostridium acetobutylicum and C. beijerinckii, were previously shown to be nitrogen-fixing organisms based on the incorporation of ¹⁵N₂ into cellular material. The key nitrogen-fixation (nif) genes, including nifH, nifD, and nifK for nitrogenase component proteins as well as nifE, nifN, nifB and nifV for synthesis of the iron–molybdenum cofactor (FeMoco) of nitrogenase, have now been identified in C. acetobutylicum or C. beijerinckii or both. The organization of these genes is similar to the distinctive pattern that was first observed in Clostridium pasteurianum, with the nifN and nifB genes fused into the nifN-B gene and with the nifV gene split into the nifVω and nifVα genes. The corresponding nif genes of these three clostridial species are highly related to each other. However, in the two solvent-producing clostridia, the nifH and nifD genes are interspersed by two glnB-like genes, which are absent in the corresponding region in C. pasteurianum. However, the nifN-B and nifVω genes of C. pasteurianum are interspersed by the putative modA and modB genes (for molybdate transport), which are absent in the corresponding region in C. acetobutylicum. C. acetobutylicum and C. beijerinckii grew well under nitrogen-fixing conditions, and the acetylene-reducing activity of nitrogenase was measured in the two species. Acetone, butanol, and isopropanol production occurred in nitrogen-fixing cultures, but the peak of nitrogen-fixing activity preceded the active solventogenic phase. Journal of Industrial Microbiology & Biotechnology (2001) 27, 281–286. Received 02 September 2000/ Accepted in revised form 22 November 2000     

Various infection status and molecular evidence for horizontal transmission and recombination of Wolbachia and Cardinium among rice planthoppers and related species

Wolbachia and Cardinium are widely distributed and are considered important for their ability to disturb reproduction and affect other fitness‐related traits of their hosts. By using multilocus sequence typing (MLST), RFLP (restriction fragment length polymorphism) and 16S ribosomal DNA gene sequencing methods, we extensively surveyed Wolbachia and Cardinium infection status of four predominant rice planthoppers and one kind of leafhopper in different rice fields. The results demonstrated that Sogatella furcifera (Horváth) and Laodelphax striatellus (Fallén) were infected with the same Wolbachia strain (wStri), while Nilaparvata lugens (Stål) and its closely related species Nilaparvata muiri China were infected with two phylogeneticlly distant strains, wLug and wMui, respectively. Three new Wolbachia strains (provisionally named wMfas1, wMfas2 and wMfas3) were detected in the leafhopper Macrosteles fascifrons (Stål). Only S. furcifera was co‐infected with Cardinium, which indicated that the distribution of Cardinium in these rice planthoppers was narrower than that of Wolbachia. Unambiguous intragenic recombination events among these Wolbachia strains and incongruent phylogenetic relationships show that the connections between different Wolbachia strains and hosts were more complex than we expected. These results suggest that horizontal transmission and host associated specialization are two factors affecting Wolbachia and Cardinium infections among planthoppers and their related species.     

Assessment of genomic and species relationships in Triticum and Aegilops by PAGE and by differential staining of seed albumins and globulins

Summary Endosperm protein components from common bread wheats (Triticum aestivum L.) and related species were extracted with aluminum lactate, pH 3.2, and examined by electrophoresis in the same buffer. Electrophoretic patterns of the albumins and globulins were compared to evaluate the possibility that a particular species might have contributed its genome to tetraploid or hexaploid wheat. Together with protein component mobilities, differential band staining with Coomassie Brilliant Blue R250 was employed to test the identity or non-identity of bands. Eight species and 63 accessions, representative of Triticum and Aegilops were tested. Considerable intraspecific variation was observed for patterns of diploid but not for tetraploid or hexaploid species. Patterns of some accessions of Triticum urartu agreed closely with major parts of the patterns of Triticum dicoccoides and T. aestivum. A fast-moving, green band was found in all accessions of T. urartu and of Triticum boeoticum, however, that was not found in those of T. dicoccoides or T. aestivum. This band was present in all accessions of Triticum araraticum and Triticum zhukovskyi. Patterns of Aegilops longissima, which has been suggested as the donor of the B genome, differed substantially from those of T. dicoccoides and T. aestivum. Finally, two marker proteins of intermediate mobility were also observed and may be used to discriminate between accessions of T. araraticum/T. zhukovskyi and those of T. dicoccoides/T. aestivum.     

Toxicity and accumulation of thallium in bacteria and yeast

Thallium sulphate inhibited microbial growth, withBacillus megaterium KM, more sensitive to the metal thanSaccharomyces cerevisiae andEscherichia coli. Inhibition ofB. megaterium KM andS. cerevisiae, but not ofE. coli, was alleviated by increasing the potassium concentration of the medium; inhibition of respiration ofS. cerevisiae, but not ofE. coli, was similarly alleviated. Thallium was rapidly bound, presumably to cell surfaces, byS. cerevisiae andE. coli, and was progressively accumulated by energy-dependent transport systems (probably concerned primarily with potassium uptake) with both organisms. Thallium uptake kinetics suggested more than one transport system operated in yeast, possibly reflecting a multiplicity of potassium transport systems. ApparentK _m andK _i values for competitive inhibition of thallium uptake by potassium indicatedS. cerevisiae to have a higher affinity for thallium uptake than for potassium, whileE. coli had a transport system with a higher affinity for potassium than for thallium. The likely systems for thallium transport are discussed. A mutant ofE. coli with tenfold decreased sensitivity to thallium was isolated and apparently effected surface binding of thallium in amounts equivalent to the wild type organism, but showed no subsequent uptake and accumulation of the metal from buffer, even though it was able to accumulate potassium to normal intracellular concentrations during growth. Abbreviations: Metal are referred to by their recognised atomic symbols (e.g. TI = Thallium; K = potassium; Co = cobalt)     

Antibacterial and Antifugal Mono- and Di-substituted Symmetrical and Unsymmetrical Triazine-derived Schiff-bases and their Transition Metal Complexes

A new series of antibacterial and antifungal triazine-derived mono- and di-substituted (symmetrical and unsymmetrical) Schiff-bases and their cobalt(II), copper(II), nickel(II) and zinc(II) metal complexes have been synthesized and characterized by their elemental analyses, molar conductances, magnetic moments and IR and electronic spectral measurements. IR spectra indicated the ligands to act as tridentate towards divalent metal ions via a trazine-N, the azomethine-N and, indole-NH and deprotonated-O of salicylaldehyde. The magnetic moments and electronic spectral data suggest octahedral geometry for the Co(II), Ni(II) and Zn(II)complexes and square-pyramid for Cu(II) complexes. NMR spectral data of the ligands and their diamagnetic zinc(II) complexes well-define their proposed structures/geometries. Elemental analyses data of the ligands and metal complexes agree with their proposed structures/geometries. The synthesized ligands, along with their metal complexes were screened for their antibacterial activity against Escherichia coli, Bacillus subtillis, Shigella flexneri, Staphylococcus aureus, Pseudomonas aeruginosa and Salmonella typhi and for antifungal activity against Trichophyton longifusus, Candida albicans, Aspergillus flavus, Microsporum canis, Fusarium solani and Candida glaberata. The results of these studies show the metal complexes to be more antibacterial/antifungal against two or more species as compared to the uncomplexed Schiff-base ligands.     

A kinetic model and simulation of starch saccharification and simultaneous ethanol fermentation by amyloglucosidase and Zymomonas mobilis

A mathematical model is described for the simultaneous saccharification and ethanol fermentation (SSF) of sago starch using amyloglucosidase (AMG) and Zymomonas mobilis. By introducing the degree of polymerization (DP) of oligosaccharides produced from sago starch treated with -amylase, a series of Michaelis-Menten equations were obtained. After determining kinetic parameters from the results of simple experiments carried out at various substrate and enzyme concentrations and from the subsite mapping theory, this model was adapted to simulate the SSF process. The results of simulation for SSF are in good agreement with experimental results.List of Symbols g/g rate coefficient of production - _max 1/h maximum specific growth rate - E %, v/w AMG concentration - G ₁ mmol/l glucose concentration - G _c mmol/l glucose concentration consumed - G _f mmol/l glucose concentration formed - G _n mmol/l n-mer maltooligosaccharide concentration - K _i g/l ethanol inhibition constant for ethanol production - K _g mmol/l glucose inhibition constant for glucose production - K _p mmol/l glucose limitation constant for ethanol production - K _x mmol/l glucose limitation constant for cell growth - K _m,n mmol/l Michaelis-Menten constant for n-mer oligosaccharide - k _e %, v/w enzyme limitation constant - k _es proportional constant - k _{max, n} 1/s maximal velocity for n-mer digestion - k _s g/l substrate limitation constant - m _s g/g maintenance energy - MW _n g/mol molecular weight of n-mer oligosaccharide - P g/l ethanol concentration - P ₀ g/l initial ethanol concentration - P _m g/l maximal ethanol concentration - Q _pm g/(g · h) maximum specific ethanol production rate - S _n mmol/h branched n-mer oligosaccharide concentration - S ₀ g/l initial starch concentration - S _sta g/l starch concentration - S _tot g/l total sugar concentration - V _{max, n} 1/h maximum digestion rate of n-mer oligosaccharide - V ₀ g/(l · h) initial glucose formation rate - X g/l cell mass - X ₀ g/l initial cell mass - Y _p/s g/g ethanol yield - Y _x/s g/g cell mass yield     

Interaction of maturation delay and nonlinear birth in population and epidemic models

 A population with birth rate function B(N) N and linear death rate for the adult stage is assumed to have a maturation delay T>0. Thus the growth equation N′(t)=B(N(t−T)) N(t−T) e⁻ d ₁ T−dN(t) governs the adult population, with the death rate in previous life stages d ₁≧0. Standard assumptions are made on B(N) so that a unique equilibrium N _e exists. When B(N) N is not monotone, the delay T can qualitatively change the dynamics. For some fixed values of the parameters with d ₁>0, as T increases the equilibrium N _e can switch from being stable to unstable (with numerically observed periodic solutions) and then back to stable. When disease that does not cause death is introduced into the population, a threshold parameter R ₀ is identified. When R ₀<1, the disease dies out; when R ₀>1, the disease remains endemic, either tending to an equilibrium value or oscillating about this value. Numerical simulations indicate that oscillations can also be induced by disease related death in a model with maturation delay. Received: 2 November 1998 / Revised version: 26 February 1999     

Interrelationships and diversification of Argynnis Fabricius and Speyeria Scudder butterflies

Diverse radiations of insects are often associated with adaptations to host plants, and well‐resolved phylogenetic relationships are required to fully understand them. Palearctic Argynnis and related subgenera, together with North American Speyeria butterflies make up a radiation whose species hypotheses are confounded by shared wing colour patterns between sympatric populations of closely related recognized species. Previous studies of this group indicate that Speyeria is a lineage within Argynnis, but sampling in these studies has either involved too few Speyeria species or incomplete sampling of Argynnis species. Thus, no comprehensive phylogenetic analysis exists for all members that answers the question of monophyly of Speyeria, or other subgeneric taxa, and their relationship to Argynnis species. We completed a phylogenetic analysis of all North American Speyeria species and all but one species within Argynnis, using one mitochondrial (cytochrome c oxidase I, COI) and four nuclear genes [elongation factor 1 alpha (EF1α), wingless (WG), glyceraldehyde‐3‐phosphate dehydrogenase (GAPDH), and ribosomal protein S5 (RPS5)]. The results indicate three major lineages within Argynnis s.l.: two Palearctic and one containing both Palearctic and Nearctic species. In summary, the phylogenetic analyses suggest the need for reorganization into three natural groups: Argynnis, Fabriciana and Speyeria. Within each of these genera the phylogenetic hypothesis indicates an evolutionary history marked by rapid diversification and potential extinction, followed by ongoing lineage sorting. The position of North American Speyeria is nested within the Palearctic lineages, which indicates that the radiation began in Asia and was fuelled by existing Viola diversity in North America. Dating analyses of Viola and Speyeria corroborate this hypothesis. The current North American Speyeria species are mixed on the tree, indicating a recent and ongoing radiation. These results provide needed clarity on the evolution of this group, which contains species of conservation concern.     

Morphological and molecular examination of relationships and epitype establishment of Phacus pleuronectes,Phacus orbicularis,and Phacus hamelii1

Verification of morphological diagnostic features and the establishment of three epitypes for three species of Phacus Dujardin—Phacus pleuronectes (O. F. Müll.) Dujardin, Phacus orbicularis Hübner, and Phacus hamelii Allorge et Lefèvre—was performed based on literature studies and analysis of morphological (cell shape, cell size, and periplast ornamentation) as well as molecular (18S rDNA) characters. Periplast ornamentation was recognized as a main diagnostic character, distinguishing P. orbicularis from P. pleuronectes and P. hamelii. Phacus orbicularis has struts running perpendicular to the longitudinal axis of the strips, while P. pleuronectes and P. hamelii do not. On the SSU rDNA tree, obtained by the Bayesian method, P. orbicularis, P. pleuronectes, and P. hamelii belong to three distinct clades. Some of the phylogenetic relationships are not resolved, but there are at least three Phacus species (P. hamatus, P. platyaulax, P. longicauda; for taxonomic authors, see Introduction) that are more closely related to P. orbicularis than is P. pleuronectes. Phacus hamelii is more closely related to P. ranula and the assemblage of several species of Phacus, which have small cells, than to P. orbicularis or P. pleuronectes.     

Intermolecular and intramolecular transposition and transposition immunity in Tn3 and Tn2660

Summary Intermolecular transposition of Tn2660 into pCR1 was measured at 30°C in recA ^– and recA ⁺ hosts as between 2.6 and 5.5x10^–3, a similar value to that previously found for Tn3. No cointegrate structures were found under conditions where 10⁴ transposition events occurred. Immunity to intermolecular transposition of Tn2660, similar to that found for Tn3 was demonstrated by showing that the above transposition frequency was reduced by a factor of between 10^–3 and 10^–4 when a mutant Tn2660 (resulting in the synthesis of a temperaturesensitive -lactamase) was present in the recipient plasmid. Intramolecular transposition of Tn3 was found to occur under the same conditions as previously demonstrated for Tn2660 giving rise to similar end products, in which the newly introduced Tn3 is oriented inversely to the resident Tn3 and the DNA sequence between the two transposons has been inverted. Thus, in all respects functional identity of the transposition activities of Tn3 and Tn2660 is shown, thereby identifying characteristics of intramolecular transposition that are not readily accommodated by current models of transposition.     

Experimental uptake and retention of pathogenic and nonpathogenic Vibrio parahaemolyticus in two species of clams: Ruditapes decussatus and Ruditapes philippinarum

Aims: To describe uptake and retention of pathogenic and nonpathogenic Vibrio parahaemolyticus in Ruditapes decussatus and Ruditapes philippinarum. Methods and Results: Ruditapes decussatus accumulated greater concentrations of pathogenic and nonpathogenic V. parahaemolyticus than R. philippinarum. These concentrations decreased earlier in R. decussatus. Nonpathogenic V. parahaemolyticus reached higher concentrations (approx. 1 log CFU g^?1 in tissues of R. decussatus and more than 1 log CFU g^?1 in R. philippinarum) than pathogenic V. parahaemolyticus at similar times. It also persisted longer in both species of clams (72 h in R. decussatus and 96 h in R. philippinarum), while pathogenic V. parahaemolyticus persisted 48 h in R. decussatus and 72 h in R. philippinarum. Conclusions: Ruditapes decussatus incorporated both isolates of V. parahaemolyticus faster than R. philippinarum and it eliminated both isolates earlier than R. philippinarum. Under same conditions, nonpathogenic V. parahaemolyticus might survive better than pathogenic V. parahaemolyticus within both species of clam. Significance and Impact of the Study: Pathogenic V. parahaemolyticus is an important cause of foodborne illnesses. This study shows it may be possible to use nonpathogenic V. parahaemolyticus to perform experimentation to evaluate bacterial evolution in clams, developing an in vivo model useful for risk analysis.     

Interconversions of Chlorophylls a and b Synthesized from Exogenous Chlorophyllides a and b in Etiolated and Post-Etiolated Rye Seedlings

A comparative study of reciprocal conversions of chlorophylls a and b (Chl aand Chl b) in etiolated and post-etiolated rye seedlings (Secale cereale L.) was performed. The production of these pigments was initiated by infiltration of exogenous chlorophyllides a and b (Chlide a and b). It was shown that Chlide b, when infiltrated into etiolated rye seedlings, was esterified, producing Chl b. A major portion of Chl b (more than 80%) was transformed into Chl aduring long-term seedling dark exposure. The high rate of Chl b conversion into Chl a in the pool of pigments of exogenous origin was also observed during the lag-phase when there was no chlorophyll formation from endogenous precursors. The infiltration of Chlide a resulted in Chl a formation. The efficiency of its conversion into Chl b was low (about 1%) in the etiolated seedlings but increased during their greening. In the post-etiolated seedlings infiltrated with Chlide b, which were preliminary illuminated for 6–12 h, the Chl /Chl a ratio was almost similar in the pools of pigments synthesized from both exogenous and endogenous precursors. The rates of direct and reverse reactions responsible for the interconversion of Chl aand Chl b depended on the stage of the formation of the photosynthetic apparatus during greening of etiolated seedlings, when the particular structural components are formed in a definite sequence.     

Interaction between pathogenic and saprobic fungi isolated from soybean roots and seeds

A variety of interactions was recorded in culture between 11 saprobic fungi isolated from soybean (Glycine max) roots and seeds and the soybean pathogens Cercospora sojina, Colletotrichum truncatum, Macrophomina phaseolina, Phomopsis sojae, and Septoria glycines. The most active saprobes were Aspergillus terreus, Chaetomium cupreum, Epicoccum nigrum, Gliocladium roseum, Myrothecium roridum, Penicillium thomii, and Trichothecium roseum. Hyphal lysis of several fungal pathogens by Acremonium sp., C. cupreum and P. thomii was recorded perhaps because of parasitism by G. roseum and T. roseum. In greenhouse studies, seeds coated with G. roseum, P. thomii, and T. harzianum emerged significantly (P=0.05) more than those coated with A. terreus and the control. In field studies, seeds coated with a conidial suspension of A. terreus, G. roseum, P. thomii or Trichoderma harzianum produced a significantly greater stand than the control. The area of cotyledons covered with lesions caused by C. truncatum was significantly less on seeds coated with G. roseum, P. thomii and T. harzianum than the control.     

Experimental and Calculated CPL Spectra and Related Spectroscopic Data of Camphor and Other Simple Chiral Bicyclic Ketones

UV, circular dichroism (CD), fluorescence and circularly polarized luminescence (CPL) spectra were recorded for a set of four related [2.2.1] bicyclic compounds ((1S,4S)‐and (1R,4R)‐1,7,7‐trimethylbicyclo[2.2.1]heptan‐2‐one, namely (1S)‐ and (1R)‐camphor ( 1 ), (1S,4R)‐4,7,7‐trimethylbicyclo[2.2.1]hept‐5‐en‐2‐one, (1S)‐dehydro‐epicamphor ( 2 ), (1S,4S)‐1,7,7‐trimethylbicyclo[2.2.1]heptane‐2,5‐dione, (1S)‐5‐oxocamphor ( 3 ), (1S,4R)‐ and (1R,4S)‐1,7,7‐trimethylbicyclo[2.2.1]heptane‐2,3‐dione, (1S)‐ and (1R)‐camphorquinone ( 4 )) and a set of three related [2.2.2] bicyclic compounds (1S,4S)‐bicyclo[2.2.2]octan‐2,5‐dione (saturated diketone ( 5 )), (1R,4R)‐bicyclo[2.2.2]oct‐7‐en‐2,5‐dione (unsaturated diketone ( 6 )), ((1S,4S)‐bicyclo[2.2.2]oct‐7‐en‐5(S)‐ol‐2‐one (which we refer to as unsaturated hydroxy‐ketone ( 7 )). For the latter three compounds also mid‐IR vibrational circular dichroism (VCD) spectra were recorded and are presented. Time‐Dependent Density Functional (TD‐DFT) calculations provide a satisfactory interpretation of both absorption and emission chiroptical spectra and permit insight into ground and excited state electronic properties. We discuss the applicability of the octant rule or of other approximated models to rationalize the observed sign of the CPL. Chirality 25:589–599, 2013. © 2013 Wiley Periodicals, Inc.     

Development and function of Pisolithus and Scleroderma ectomycorrhizas formed in vivo with Allocasuarina,Casuarina and Eucalyptus

The effect of inoculating seedlings of Eucalyptus grandis, Allocasuarina littoralis and Casuarina equisetifolia with two isolates of Pisolithus and two isolates of Scleroderma from under eucalypts was examined in a glasshouse trial. Ectomycorrhizas formed extensively on Eucalyptus (23–46% fine roots ectomycorrhizal) and Allocasuarina (18–51% fine roots ectomycorrhizal). On Casuarina, the fungi were either unable to colonize the rhizosphere (one isolate of Pisolithus), or sheathed roots, resembling ectomycorrhizas, formed on 1–2% of the fine roots. Colonization of roots by one isolate of Scleroderma resulted in the death of Casuarina seedlings. Inoculation with fungi increased shoot dry weight by up to a factor of 32 (Eucalyptus), 4 (Allocasuarina) and 3 (Casuarina). Ectomycorrhizas formed in associations with Eucalyptus and Allocasuarina had fully differentiated mantles and Hartig nets in which the host and fungal cells were linked by an extensive fibrillar matrix. Sheathed roots in Casuarina lacked a Hartig net, and the epidermis showed a hypersensitive reaction resulting in wall thickening and cell death. The sheaths are described as mantles since the density and arrangement of the hyphae in the sheaths was similar to that in mantles of the eucalypt ectomycorrhizas. The intercellular carbohydrate matrix was not produced in the Casuarina mantle in association with Pisolithus, hence the mantle was not cemented to the root. These structures differ from poorly compatible associations described previously for Pisolithus and Eucalyptus. The anatomical data indicate that ectomycorrhizal assessment based on surface morphological features may be misleading in ecological studies because compatible and incompatible associations may not be distinguishable.     

Effects of instantaneous and growth CO2 levels and abscisic acid on stomatal and mesophyll conductances

C₃ photosynthesis is often limited by CO₂ diffusivity or stomatal (g_s) and mesophyll (g_m) conductances. To characterize effects of stomatal closure induced by either high CO₂ or abscisic acid (ABA) application on g_m, we examined g_s and g_m in the wild type (Col‐0) and ost1 and slac1‐2 mutants of Arabidopsis thaliana grown at 390 or 780 μmol mol^?1 CO₂. Stomata of these mutants were reported to be insensitive to both high CO₂ and ABA. When the ambient CO₂ increased instantaneously, g_m decreased in all these plants, whereas g_s in ost1 and slac1‐2 was unchanged. Therefore, the decrease in g_m in response to high CO₂ occurred irrespective of the responses of g_s. g_m was mainly determined by the instantaneous CO₂ concentration during the measurement and not markedly by the CO₂ concentration during the growth. Exogenous application of ABA to Col‐0 caused the decrease in the intercellular CO₂ concentration (C_i). With the decrease in C_i, g_m did not increase but decreased, indicating that the response of g_m to CO₂ and that to ABA are differently regulated and that ABA content in the leaves plays an important role in the regulation of g_m.     

Ovule and seed anatomy ofCistaceae and relatedMalvanae

Ovule and especially seed anatomy of eight species ofCochlospermaceae, Bixaceae, Cistaceae, Monotoideae, Pakaraimaeoideae (two subfamilies ofDipterocarpaceae), andSarcolaenaceae were investigated. All representatives show a bixoid chalazal region in the seed as probable exclusive synapomorphy among angiosperms. The palisade layer of the exotegmen is curved inwards at its proximal end and forms a dome-shaped structure. A plug of hypostase tissue with an annulus/core structure fits into this dome. Moreover, two additional tissue types in the hypostase can be found in some representatives of the group. These and other micromorphological, wood anatomical, and floral morphological characters, indicate that the taxa form a monophyletic group close toMalvales s. str. The form of the starch grains in the endosperm is compared and is described for the first time forPakaraimaea (Dipterocarpaceae) andLeptolaena (Sarcolaenaceae). The position ofDiegodendron close toBixa and the presumably more distant positions ofMuntingia andNeuradaceae are discussed.