ALBERT

Notes: We have studied the stomatal response in relation to the xylem-derived abscisic acid (ABA) accumulation in sunflower leaves. When ABA was introduced into detached leaves of the sunflower through xylem flux, stomatal conductance was regulated, water flux was changed as a result and at the same time the xylem-derived ABA was metabolised in the leaves. We computed the xylem-derived ABA accumulation in the leaves as a function of time by taking into account the variation of ABA flux into the leaves (the product of water flux and ABA concentration) and a continuing ABA metabolism. We found that ABA accumulation was rapid during an initial lag phase, much slowed down during the decreasing phase of stomatal conductance, but still substantial when stomatal conductance reached a new stable state. The results show a poor link between the kinetics of ABA-induced stomatal closure and the xylem-derived ABA accumulation. Xylem-derived ABA was metabolised rapidly in the leaves. Tetcyclacis, as an inhibitor, substantially inhibited this process. Two hours after ABA was fed into a leaf, about 70% of the fed ABA was metabolised, but when tetcyclacis was added into the feeding solution, less than 30% of ABA was metabolised, even after 24 h of incubation. The inhibition of ABA metabolism by tetcyclacis did not lead to more stomatal closure, which was still concentration-dependent. Since the accumulation of xylem-derived ABA was enhanced substantially by the presence of tetcyclacis, these results strongly indicate that stomata mainly respond to the prevailing ABA concentration in the xylem stream, rather than to the accumulated amount of xylem-derived ABA in the leaves.

Notes: Enzymatic digestion of the cell wall of Brassica napus hypocotyls gave a heterogeneous suspension of protoplasts with the cortical microtubules (CMTs) randomly organised or CMTs organised in parallel. The effect of variable g-influences has been tested on CMT organisation. In contrast to the 1 g-protoplasts, which reorganised the CMTs into parallel arrays during the 96 h test period, the frequency of randomly-oriented CMTs in the protoplasts exposed to simulated weightlessness (0 g) on a 2-D clinostat increased significantly during the same period. The opposite effect was obtained when the protoplasts were exposed to hyper-g (7 or 10 g), where the reorganisation of the CMTs into parallel arrays was accelerated compared to the 1 and 0 g-protoplasts. These results indicate that a unidirectional gravity force is a necessity for the reorganisation of CMTs in protoplasts to parallel arrays and that CMTs act as responding elements that are able to sense different levels of gravity. Besides the inability of the protoplasts to reorganise the CMTs into parallel arrays, the quantity of CMTs in the individual protoplast decreased during 4 days of simulated weightlessness, both compared to the CMTs quantity in the protoplasts immediately after isolation and compared to the 1 g- and hyper-g-protoplasts after 24 and 48 h of g-exposure. The size of the protoplasts was also affected by the g-exposure. Protoplasts exposed to simulated 0 g increased significantly after 24 and 48 h, whereas the 1 g- and 10 g-protoplasts maintained the same size during the 48 h test period.

Notes: The role of mitochondrial respiration in optimizing photosynthesis was assessed in mesophyll protoplasts of pea (Pisum sativum L., cv. Arkel) by using low concentrations of oligomycin (an inhibitor of oxidative phosphorylation), antimycin A (inhibits cytochrome pathway of electron transport) and salicylhydroxamic acid (SHAM, an inhibitor of alternative oxidase). All three compounds decreased the rate of photosynthetic O2 evolution in mesophyll protoplasts, but did not affect chloroplast photosynthesis. The inhibition of photosynthesis by these mitochondrial inhibitors was stronger at optimal CO2 (1.0 mM NaHCO3) than that at limiting CO2 (0.1 mM NaHCO3). We conclude that mitochondrial metabolism through both cytochrome and alternative pathways is essential for optimizing photosynthesis at limiting as well as at optimal CO2. The ratios of ATP to ADP in whole protoplast extracts were hardly affected, despite the marked decrease in their photosynthetic rates by SHAM. Similarly, the decrease in the ATP/ADP ratio by oligomycin or antimycin A was more pronounced at limiting CO2 than at optimal CO2. The mitochondrial oxidative electron transport, through both cytochrome and alternative pathways, therefore akppears to be more important than oxidative phosphorylation in optimizing photosynthesis, particularly at limiting CO2 (when ATP demand is expected to be low). Our results also confirm that the alternative pathway has a significant role in contributing to the cellular ATP, when the cytochrome pathway is limited.

Notes: Recent studies have suggested that Ca2+/calmodulin (CaM) or CaM-like proteins may be involved in blue light (BL)-dependent proton pumping in guard cells. As the increase in cytosolic concentration of Ca2+ is required for the activation of CaM and CaM-like proteins, the origin of the Ca2+ was investigated by measuring BL-dependent proton pumping with various treatments using guard cell protoplasts (GCPs) from Vicia faba. BL-dependent proton pumping was affected neither by Ca2+ channel blockers nor by changes of Ca2+ concentration in the medium used for the GCPs. Addition of Ca2+ ionophores and an agonist to GCPs did not induce proton pumping. However, BL-dependent proton pumping was inhibited by 10 mM caffeine, which releases Ca2+ from the intracellular stores, and by 10 μM 2,5-di-(tert-butyl)-1,4-benzohydroquinone (BHQ) and 10 μM cyclopiazonic acid (CPA), inhibitors of Ca2+-ATPase in the sarcoplasmic and endoplasmic reticulum (ER). By contrast, the inhibitions were not observed by 10 μM thapsigargin, an inhibitor of animal ER-type Ca2+-ATPase. The inhibitions by caffeine and BHQ were reversible. Light-dependent stomatal opening in the epidermis of Vicia was inhibited by caffeine, BHQ, and CPA. From these results, we conclude that the Ca2+ thought to be required for BL-dependent proton pumping may originate from intracellular Ca2+ stores, most likely from ER in guard cells, and that this origin of Ca2+ may generate a stimulus-specific Ca2+ signal for stomatal opening.

Notes: Plant aspartic proteinases have been characterized from seeds, flowers and leaves of a number of different species. The enzymes are generally either monomeric or heterodimeric, containing two peptides processed from the same precursor protein. The plant enzymes, like their mammalian and microbial counterparts, are active at acidic pH and inhibited by a class specific inhibitor pepstatin A. Plant aspartic proteinases are generally either secreted or targeted to the vacuolar/protein storage body compartment. The primary sequences of many of these enzymes have been determined and are very homologous with each other as well as with enzymes from mammalian and microbial origins. Plant aspartic proteinases, however, have a very unique plant specific region, which is not found in mammalian, microbial, or viral aspartic proteinases. The function of this region has not been elucidated. A role for these plant enzymes in protein processing or degradation has been proposed, however, more studies are required to confirm their in vivo functions. Recent intriguing results suggest possible roles for these enzymes in programmed cell-death of tissues and in pathogen resistance.

Notes: In shoots of the garden pea (Pisum sativum L.), the main bioactive gibberellin (GA) is GA1, which is synthesised from GA20 by 3β-hydroxylation. Gibberellin A20 is produced from GA19, as part of the process known as GA 20-oxidation. Because these steps are thought to be negatively regulated by GA1, we compared the metabolism of labelled GA19 and GA20 in mutants deficient in GA1, with that observed in isogenic wild-type (WT) plants. There was a large and specific increase in the 3β-hydroxylation of labelled GA20 in the GA1-deficient (dwarf) mutants, compared with the WT. Metabolism experiments did not provide convincing evidence for feedback regulation of 20-oxidation, possibly because GA19 akppears to be metabolised rapidly, even in WT pea shoots. Both 3β-hydroxylase and 20-oxidase transcript levels were markedly higher in the mutants than in isogenic WT lines. The results sukpport previous suggestions that both biosynthetic steps are feedback-regulated by GA1 in pea.

Notes: An overview is given of electrical events that occur in plant chloroplasts in association with their energization and subsequent photosynthetic performance. Special emphasis is given to the measuring techniques, in particular application of patch-clamp methods, which enable comparison of light-induced photocurrent and -potential kinetics of the thylakoid with kinetics of changes in chlorophyll fluorescence yield.

Notes: Pyrophosphate: d-fructose-6-phosphate 1-phosphotransferase (PFP; EC 2.7.1.90) and ATP: d-fructose-6-phosphate 1-phosphotransferase (PFK; EC 2.7.1.11) activities were determined in sugarcane varieties differing in sucrose content. For this purpose, activities were measured in those internodes where the maximum rate of sucrose accumulation occurs. The specific activity of internodal PFP varied significantly between the sugarcane varieties and was inversely correlated with the sucrose content. There was also a highly significant inverse correlation between PFP and sucrose content in a segregating F1 population. PFK activity was comparable to, or lower than, PFP activity and no relationship was evident between PFK activity and sucrose content. In all tissues investigated, the fructose 2,6-bisphosphate levels were probably sufficient to ensure full activation of PFP. The levels of PFP activity appear to be controlled by the expression of the β-subunit of the protein. The molecular mass of the PFP subunit polypeptide(s) was approximately 63 kDa. There was an inverse correlation between sucrose content and the partitioning of radiolabel into respiration in internodal tissue slices labelled with [U-14C]glucose across 3 sugarcane lines. The estimated flux of carbon into respiration correlated directly with PFP activity.

Notes: Twenty-one durum wheat genotypes originating from different geographic areas were grown during 3 successive years. The trials were characterised by different precipitation regimes. Carbon isotope discrimination (Δ), carbon content (CC) and ash content (ma) were assessed in the flag leaf during anthesis, then in the kernel at full maturity. Differences between the 3 years, due to water availability, were noted for Δ, ma, CC and yield. Genotypic differences were also noted within each year for all the traits studied. Some genotypes from the Middle East exhibited higher flag leaf and kernel Δ than those originating from the West of the Mediterranean basin. The kernel Δ was strongly correlated with grain yield (GY). The leaf Δ correlated with GY only under strong water limitation and with biomass production (BP) in favourable water conditions. For the flag leaf, Δ was correlated with ma and with CC. Silicon content was then assessed in the flag leaf and in the kernel on a subset of 10 genotypes differing in their Δ values. Strong positive correlations were noted between silicon content and Δ and ma for the flag leaf. However, no clear relationship was found between silicon content and GY. The results obtained in this study confirm the validity of kernel Δ as a predictive criterion for GY under water stress and suggest the possible use of kernel ma as an alternative criterion to select genotypes with higher water stress tolerance.

Notes: In order to clarify the effect of abscisic acid (ABA) on anaerobic tolerance in alfalfa (Medicago sativa L.), the seedlings were subjected to anaerobic stress after pretreatment with ABA. At concentrations〉 1 μM, ABA pretreatment increased the root viability of the seedlings to anaerobic stress and the viability increased with increasing ABA doses. At 100 μM ABA, the viability was 2.5-fold greater as compared with that of control seedlings. Roots of the seedlings rapidly lost ATP under the anaerobic stress; however, the decrease in ATP was much slower in the ABA-pretreated seedlings than the control seedlings. At 12 h after onset of the stress, ATP concentrations in the roots of 100 and 10 μM ABA-pretreated seedlings were 2.7- and 2.0-fold that of the control seedlings, respectively. During the period of ABA pretreatment under aerobic condition, ABA increased alcohol dehydrogenase (ADH, EC 1.1.1.1) activity in the roots until 12 h and then leveled off. The maximum ADH activities were 4.3- and 2.8-fold that in the roots of the control seedlings for 100 and 10 μM ABA-pretreated seedlings, respectively. After being subjected to the anaerobic stress, both ADH activities in the roots of the ABA-pretreated and the control seedlings increased but the differences in their activity remained. These results suggest that ABA pretreatment may maintain ATP level due to induction of ADH activity, which may be one of the causes of increasing anaerobic tolerance in the seedlings.

Notes: To elucidate how plants adapt to overheating followed by water deficiency, experiments with two cotton (Gossypium hirsutum L.) cultivars (Ok-oltin and INEBR-85) were performed. Preliminary heat-shock (HS) treatment (45°C for 1.5 h) increased resistance of both cultivars to subsequent progressive soil drought [40 days without watering, with soil moisture gradually decreasing from 70 to 20% of field moisture capacity (FMC)]. HS induced accumulation of amino acids and amides and increased their contribution to the osmotic pressure (OP) of the leaf cell sap. HS also enhanced resistance to water deficiency and to overheating of the leaves, especially in cv. INEBR-85, the more drought resistant of the two cultivars. The results suggest the existence of common resistance systems to both stress factors, in particular, accumulation of amino acids and amides (mainly arginine, proline and asparagine) – their concentration in the cell sap increased up to 240-, 160- and 150-fold, respectively.

Notes: Messenger RNA translation is a tightly regulated event in maize axes during germination. To obtain a deeper understanding of this process, the present research was centered on the expression regulation of the translation initiation factor eIF-4E within this period. Two maize eIF-4E isoforms were isolated by mGTP-Sepharose affinity chromatography. The eIF-iso4E protein content remained at a constant level in the axes during the first 24 h of maize germination, whereas the eIF-4E level increased after 12 h of germination as indicated by western blot analysis. Fast in vivo eIF-iso4E, but not eIF-4E, de novo synthesis was found within 6–12 h of germination. Northern blot analysis of total RNA from ungerminated axes with cDNAs encoding either -iso4E or -4E indicated that both transcripts were present in the stored mRNA pool of maize axes. Transcription for any of these mRNAs was not detected before 12 h of germination. Northern blots of polysomal RNAs indicated that the eIF-iso4E stored transcript is selectively recruited into polysomes for translation as early as 6 h of germination, whereas this does not occur for the eIF-4E transcript. The above data demonstrate differential 4E isoform expression regulation during maize germination. Expression of the eIF-iso4E protein appears to be translationally controlled, whereas the expression of the eIF-4E protein might be regulated at the transcriptional level.

Notes: Callus derived from the roots of Inmil® cherry rootstock (Prunus incisa×serrula) proliferates in a hormone-free solid medium. When transferred to a hormone-free liquid medium, such callus forms somatic embryos. On the other hand, leaf-derived callus of P. incisa×serrula and leaf- and root-derived calli of P. domestica require exogenous auxin for sustained growth and never form embryos. Levels of free and esterified indole-3-acetic acid (IAA) were similar in both types of calli grown on a solid medium, whereas the amide-conjugated IAA was higher in the root-derived embryogenic one. Transfer to a liquid medium did not affect the level of both free and conjugated IAA in the nonembryogenic callus, but in the embryogenic callus it decreased the level of amide-conjugated IAA. Isotopic dilution of C-IAA taken up from a medium was faster in the embryoegenic than in the nonembryogenic calli, which shows that the rate of IAA metabolism was higher in embryogenic callus. Besides IAA, indole-3-ethanol and indole-3-acetyl-N-aspartate were detected in nonembryogenic calli and in in vitro-grown shoots of P. domestica, whereas in embryogenic callus and in in vitro-grown shoots of P. incisa×serrula indole-3-acetamide was detected.

Notes: The metabolism of the polyamine precursors arginine and ornithine was studied in maturing and vernalised seeds of Picea abies (L.) Karst. (Norway spruce) in feeding experiments. Incorporation of radioactivity from these C-labelled amino acids into liberated CO2, amino acids, polyamines, proteins and cell wall fractions, as well as polyamine levels were determined in embryos and megagametophytes. Ornithine and especially arginine decarboxylation was more active in the embryo than in the megagametophytic cells, and vernalisation increased arginine metabolism more than it increased ornithine metabolism. Both precursors were metabolised to each other, to other amino acids, and to polyamines. The only polyamine in which radioactivity incorporated was free putrescine, showing either a slow synthesis or a high degradation rate of spermidine and spermine in maturing spruce seeds. The putrescine level was approximately 10 times higher in the embryo than in the megagametophytic tissues, whereas spermidine and spermine levels were almost the same in both tissues. The label from arginine and ornithine was also incorporated into proteins as amino acids and post-translationally as polyamines. Higher radioactivity was seen in the small ≤14-kDa polypeptides. Protein hydrolysates of the embryo and the megagametophytic tissues contained spermidine and spermine and their degradation product 1,3-diaminopropane (DAP), suggesting that polyamines may play a role in the accumulation of seed storage protein and in the maturation of spruce seeds.

Notes: Soybean (Glycine max [L.] Merr. cv. Century) seedlings were germinated in vermiculite, sub-irrigated with a complete nutrient solution, without nitrogen or supplemented with 10 mM KNO3, 5 mM (NH4)2SO4, or 5 mM NH4NO3. After 14 days in the light, or 5 days in the dark, tissues from different organs were harvested separately. Similarly, tissues from different organs from 14- or 21-day-old nodulated or non-nodulated soybean seedlings, maintained in the absence of nitrogen, were harvested. Proteins and total RNA were isolated from the different plant organs and used for immunoblot and RNA blot analyses, respectively. Protein or RNA blots were separately incubated with antisera or hybridized with probes specific for either ferredoxin-dependent glutamate synthase (Fd-GOGAT) or NADH-dependent glutamate synthase (NADH-GOGAT). The specific activity and the abundance of the Fd-GOGAT peptide and transcript increased, approximately 3–10 times, in cotyledons and hypocotyls/stems in plants germinated in the light compared with those germinated in the dark. Fd-GOGAT activity, peptide, and transcript were highest in leaves. Except for increases in the specific activity of samples from roots treated with (NH4)2SO4 or NH4NO3, there were minor or no changes in Fd-GOGAT activity, peptide and transcript among organs of seedlings treated with different nitrogen sources or by nodulation. Low levels of NADH-GOGAT transcript were detected in all organs. NADH-GOGAT activity, peptide, and transcript increased in roots of seedlings treated with different nitrogen sources, but these changes were more apparent on RNA blots versus immunoblots. The highest NADH-GOGAT activity and most abundant amounts of the peptide and transcript were observed in nodules. Despite being induced by different environmental factors, both GOGAT activities are controlled, at least in part, by either gene expression or by RNA stability, because in most instances, both isoenzymes exhibited paralleled changes in specific activity and the abundance of their corresponding peptides and transcripts on immunoblot and RNA blots, respectively. However, there were some exceptions to the parallel increases in specific activities, peptides and transcripts which suggest that post-translational modification may also regulate the activties of the two GOGAT isoforms. Collectively, the results presented here suggest that the two GOGAT isoforms have distinct physiological functions in soybean.

Notes: Kiwifruit (Actinidia deliciosa) is a dioecious vine whose staminate and pistillate flowers nonetheless develop non-functional reproductive structures of the ompposite sex. Ubiquitin is a small, highly conserved protein found in all eucaryotes: a covalent ATP-dependent attachment of ubiquitin marks proteins for degradation. In the present paper, we used immunoblotting to investigate the presence of free ubiquitin and ubiquitin conjugates during pollen development in male (androfertile) and in female (androsterile) genotypes of kiwifruit. In the male, several high molecular mass protein conjugates were present throughout development. On the contrary, such a pattern characterized only early stages of pollen from the female genotype, where conjugates progressively disamppeared, until they were detectable only in trace amounts at anthesis. The highest content of conjugates in the male genotype was observed when microspores were ampproaching the first mitosis. Free ubiquitin increased continuously during development of the male microgametophyte so that mature pollen contained considerable amounts of the ubiquitin monomer at the time of its release from the anther. By contrast, only low levels were detectable in the degenerating microspores in the pistillate flowers. In vitro experiments using labeled ubiquitin indicated that early-uninucleate microspores of the female genotype had a much higher conjugation rate than those of the male genotype at the same stage. However, after feeding α-lactalbumin as exogenous substrate, the rate of ubiquitin conjugation strongly increased and was quite similar in both sexes. Nuclear features of pollen development in both genotypes are also described. The nucleus progressively degenerated in the microspores of the pistillate flowers starting from the early-uninucleate stage, in parallel with the progressive decrease in ubiquitin content and activity. At anthesis, the microspores in the pistillate flowers either had no nucleus or showed only traces of chromatin. Thus, the ubiquitin system seems to play an important role in protein turnover occurring during the normal developmental pathway of the kiwifruit microgametophyte, while it was mainly involved in regressive events related to microspore degeneration in the female genotype.

Notes: A growing body of evidence indicates that phenylpropanoid and flavonoid metabolism is catalyzed, not by free-floating ‘soluble’ enzymes, but via one or more membrane-associated multienzyme complexes. This type of macromolecular organization has important implications for the overall efficiency, specificity, and regulation of these pathways. Classical biochemical studies of phenylpropanoid and flavonoid metabolism have laid a solid foundation for this model, providing evidence of the channeling of intermediates between enzyme active sites and co-localization of enzymes in cell membranes. This work is now being extended using transgenic plants to determine how the partitioning of metabolites within these pathways is controlled, as well as applying sensitive methods to define specific interactions among the individual enzymes. Information from these studies promises to provide new insights into the structuring of biosynthetic pathways within cells, which should lead to more effective means for engineering the production of plant metabolites with nutritional and agronomic importance.

Notes: Tomato plants (Lycopersicon esculentum Mill. cv. Pera) were transformed via Agrobacterium tumefaciens with the binary vector pKYLX71 containing a tomato basic peroxidase (EC 1.11.1.7) gene, tpx1, under the control of the cauliflower mosaic virus (CaMV35S) promoter. Transgenic plants showed a 2–5-fold increase in the activity of the peroxidase ionically bound to the cell wall, whereas soluble peroxidase activity remained similar or even lower than wild-type plants. Isoelectric focusing showed the presence of a new isoperoxidase of pI ca 9 in the ionically bound extract. Western blot also showed the presence of a new band at 41 kDa that was absent in the wild-type extract. A 40–220% increment of lignin content of the leaf was found in transgenic plants. Shoot phenotype of transgenic plants was similar to wild type, although under stress, the plants appeared wilted and the new leaves had a reduced area and were thicker than wild-type or older transgenic leaves. The root system was underdeveloped in transgenic plants, but the rooting ability of the stem was not affected by the overexpression of peroxidase. Finally, the morphogenetic response of cotyledon and hypocotyl explants from transgenic plants was evaluated. In the case of cotyledons, the percentage of explants with shoot was not different from wild-type plants. For hypocotyl, one of the transgenic lines showed a 30% reduction in the percentage of shoot organogenesis. The results are discussed in relation to the role of tpx1 in lignin synthesis.

Notes: Levels of three major dehydrins of 65, 60, and 14 kDa have been observed to increase in blueberry (Vaccinium smpp.) floral buds during chill unit accumulation and cold acclimation and decrease during deacclimation and resumption of growth. Indeed, levels of the 65-, 60-, and 14-kDa dehydrins increase such that they become the most predominant proteins visible on sodium dodecyl sulfate (SDS)-polyacrylamide gels. The peptide sequence information from the 65- and 60-kDa dehydrins was used to synthesize degenerate DNA primers for amplification of a part of the gene(s) encoding the dehydrins. One pair of primers amplified a 174-bp fragment. The 174-bp fragment was used to screen a cDNA library (prepared from RNA from cold-acclimated blueberry floral buds) and resulted in the isolation of a clone with a 2.0-kb insert. The cDNA was sequenced and found to be a full-length clone encoding a K5-type dehydrin (5 K boxes). Five high-confidence peptide sequences, ranging from 9 to 25 amino acids long, obtained from the 60-kDa dehydrin exactly matched sequences encoded within the cDNA clone. Furthermore, amino acid composition of the 60-kDa dehydrin agreed well with the expected amino acid composition based on the cDNA sequence. However, the DNA sequence and coupled in vitro transcription/translation reactions of the cDNA clone indicated that it encodes a dehydrin with a native molecular mass of ∼40 kDa instead of 60 kDa. Experiments to determine if the dehydrins undergo post-translational modifications revealed that the 65- and 60-kDa dehydrins are glycosylated. Thus, our results indicate that the 2.0-kb dehydrin cDNA encodes the native version of the 60-kDa dehydrin. The dehydrin cDNA hybridized on RNA blots to two chilling/cold-responsive messages of 2.0 and 0.5 kb. Both the 2.0- and 0.5-kb messages increased to higher levels more quickly in the cold-hardy cultivar Bluecrop than in the less hardy cultivar Tifblue. In addition, the 0.5-kb message remained at a higher level longer in Bluecrop than in Tifblue.

Notes: Winter annual and perennial crop species grown in the northern boreal ecosystem must survive periods of protracted snow cover and low temperatures during the winter. In deep snow regions, plants are susceptible to winter stresses caused by both snow molds and low temperatures. Therefore, high levels of tolerance to freezing and snow molds are requisite for crops adapted to these regions. Accumulation of soluble carbohydrates in winter wheat during the autumn is linked to both hardening and resistance to attack by snow molds. Snow mold-resistant cultivars accumulate higher levels of carbohydrate and metabolize them at slower rates than susceptible cultivars. The quantity and quality of carbohydrates, particularly fructans, remaining in the spring after snow mold attack appear important for survival of winter wheat. However, the total accumulation of carbohydrates is dependent on the stage of development of the winter cereal plant at the beginning of the winter. Recent research findings have shown that sugars are pivotal metabolic activators of the sugar-sensing enzyme, hexokinase, which initiates signal transduction and activation of numerous metabolic genes including host defense genes. Thus, an understanding of the metabolism of soluble carbohydrates, particularly fructans, during plant growth, hardening, and snow mold infection, is essential to the elucidation of survival mechanisms in plants subjected to these winter stresses.

Notes: The involvement of the ascorbate-glutathione cycle in the defence against Cu-induced oxidative stress was studied in the roots of Phaseolus vulgaris L. cv. Limburgse vroege. All the enzymes of this cycle [ascorbate peroxidase (APOD), EC 1.11.1.11; monodehydroascorbate reductase (MDHAR), EC 1.6.5.4; dehydroascorbate reductase (DHAR), EC 1.8.5.1; glutathione reductase (GR), EC 1.6.4.2] were increased, and the total ascorbate and glutathione pools rose after a 15 μM root Cu treatment. In the first hours after the start of the experiment, the accumulation of dehydroascorbate (DHA), formed as a result of a Cu-mediated direct oxidation of ascorbate (AA), was limited by a non-enzymatic reduction using glutathione (GSH) as the reductant. At 24 h, the enzyme capacities of both DHAR and GR were increased to maintain the redox status of the AA and GSH pools. After 72 h of Cu application, the DHAR capacity was inhibited and MDHAR was responsible for maintaining the AA pool in its reduced form. Although the GR capacity was enhanced after 72 h in the treated plants, the GSSG/GSH ratio was increased. This could be due to direct participation of GSH in the detoxification of Cu through reduction and complexation.

Notes: In an effort to study regulation of starch synthesis in the source and sink tissues, a cDNA clone for starch granule-bound starch synthase (GBSSI), which encodes a 67-kDa protein, was isolated from a cDNA library prepared from tuberous roots of sweet potato (Ipomoea batatas Lam. cv. Tainong 62). This GBSSI protein contains a signal peptide of 77 amino acids, and the mature protein has a molecular mass of about 59 kDa. The mature protein shares 75–85% sequence identity with GBSSIs of dicotyledonous plants and about 70% identity with those of monocotyledons. The sequence of the signal peptide, on the other hand, differs substantially from those of the dicotyledons and monocotyledons studied, although their hydropathic profiles are all similar. This GBSSI gene was well expressed in tuberous roots, leaves, and stems, but not in roots. However, mechanisms involved in regulating the expression of this gene were different between tuberous roots and leaves. In tuberous roots, the synthesis of GBSSI transcript increased coordinately with tuberous root expansion; nevertheless, accumulation rates of GBSSI protein in starch granules remained constant regardless of tuberous root sizes, suggesting an involvement of post-transcriptional regulation for the synthesis of this protein. The levels of GBSSI transcript were investigated in photosynthetic tissues during diurnal cycles, and the results suggest that the transcription of the GBSSI gene in leaves is controlled by the endogenous circadian rhythm.

Notes: The early cellular events in leaf explants of Medicago sativa L. cultured on somatic embryogenesis- and callogenesis-inducing media (EIM and CIM, respectively) were correlated with the endogenous contents of polyamines (PAs) and aromatic monoamines (AMs). On the second day of culture, replication of DNA occurred in epidermal and subepidermal cells on the edges of explants on EIM and was a prerequisite for proembryonal mass and, later, globular proembryo formation. In explants cultured on CIM, replication occurred at least one day later and in fewer cells, which were randomly spread all over the explant. Transition of leaf explant cells to rapidly dividing meristematic-like cells on EIM or to enlarged, highly vacuolated cells on CIM was observed. The increase in total PA levels in cultured explants was primarily a consequence of increases in putrescine (Put) and spermidine (Spd) contents and was much more pronounced on EIM than on CIM. High Spd levels were characteristic of meristematic cells and might be essential for the development of globular structures. The higher amount of insoluble PA conjugates was determined in explant cells on EIM, as compared with CIM. Proembryogenic cell mass formation was positively correlated with free tyramine and negatively correlated with free phenylethylamine contents.

Notes: Immunofluorescent and immunogold labeling was used to study the localization of cytokinins in developing somatic and zygotic embryos of Tilia cordata Miller. Broad-specificity polyclonal antibodies active against dihydrozeatin riboside (DHZR)/zeatin riboside (ZR)-type and isopentenyladenosine (iPR)-type cytokinins were used for immunolabeling. Immunofluorescent microscopy showed that these cytokinins were concentrated in highly cytoplasmic cells showing meristematic character. Cotyledon initials and primary meristems of heart-stage somatic embryos, as well as heart-stage zygotic embryos, were labeled. During elongation of embryos, cytokinin immunoreactive material was concentrated to areas having meristematic character. Root apex, shoot meristem, and cotyledon cells of somatic and zygotic cotyledonary embryos, as well as epidermal and subepidermal cell layers of the hypocotyl, showed the strongest immunoreaction. The nucleoli, especially, had a very strong signal. Results at the ultrastructural level with gold-conjugated protein A supported these conclusions. Gold particles were distributed in the nuclei, especially in the nucleoli and throughout the ground cytoplasm. They were occasionally associated with plastids and mitochondria, but seldom with other organelles.

Notes: Leaf discs of Capsicum annuum L. were illuminated in air enriched with 1% CO2 in the absence or presence of lincomycin, an inhibitor of chloroplast-encoded protein synthesis. The loss of functional photosystem (PS) II complexes with increase in cumulative light dose (photon exposure), assessed by the O2 yield per single-turnover flash, was greater in leaves of plants grown in low light than those in high light; it was also exacerbated in the presence of lincomycin. A single exponential decay can describe the relationship between the loss of functional PSII and increase in cumulative photon exposure. From this relationship we obtained both the maximum quantum yield of photoinactivation of PSII at limiting photon exposures and the coefficient k, interpreted as the probability of photoinactivation of PSII per unit photon exposure. Parallel measurements of chlorophyll fluorescence after light treatment showed that 1/Fo−1/Fm was linearly correlated with the functionality of PSII, where Fo and Fm are the chlorophyll fluorescence yields corresponding to open and closed PSII reaction centers, respectively. Using 1/Fo−1/Fm as a convenient indicator of PSII functionality, it was found that PSII is present in excess; only after the loss of about 40% functional PSII complexes did PSII begin to limit photosynthetic capacity in capsicum leaves.

Notes: Characteristics of the cell cycle in cortical regions (0–0.6 mm from the root-cap junction) of the primary root of lentil (Lens culinaris L.) during germination in the vertical position on earth were determined by iododeoxyuridine labelling and image analysis. All cells were in the G1 phase at the beginning of germination and the duration of the first cell cycle was about 25 h. At 29 h, around 14% of the cortical nuclei were still in the G2 or M phases of the first cell cycle, whereas 53 and 33% of the nuclei were respectively in the G1 or S phase of the second cell cycle. In parallel, the cell cycle was analysed in root tips of lentil seedlings grown in space during the IML 2 mission (1994), (1) on the 1-g centrifuge for 29 h, (2) on the 1-g centrifuge for 25 h and placed in microgravity for 4 h, (3) in microgravity for 29 h, (4) in microgravity for 25 h and placed on the 1-g centrifuge for 4 h. The densitometric analysis of nuclear DNA content showed that in microgravity there were less cells in DNA synthesis and more cells in G1 than in the controls on the 1-g centrifuge (flight and ground). The comparison of the sample grown continuously on the 1-g centrifuge in space and of the sample grown first in 1-g and then in microgravity indicated that 4 h of microgravity modified cell cycle, increasing the percentage of cells in the G1 phase. On the contrary, the transfer from microgravity to the 1-g centrifuge (for 4 h) did not provoke any significant change in the distribution of the nuclear DNA content. Thus the effect of microgravity could not be reversed by a 4 h centrifugation. As the duration of the first cell cycle in the lentil root meristem is about 25 h, the results obtained are in agreement with the hypothesis that the first cell cycle and/or the second G1 phase was lengthened in absence of gravity. The difference observed in the distribution of the nuclear DNA content in the two controls could be due to the fact that the 1g control on board was subjected to a period of 15 min of microgravity for photography 25 h after the hydration of the seeds, which indicated an effect of short exposure to weightlessness. The mitotic index of cortical cells was greater on the 1-g centrifuge in space than in any other sample (flight and ground) which could show an effect of the centrifugation on the mitosis.

Notes: Olive trees are often subjected to low temperatures during winter. To quantify the effects of low temperatures on the water relations of olive trees, we studied the responses to low soil temperatures on winter days of variable evaporative demand (ET0) in 1-year-old potted olive (Oleo europaea L. cv. Picual) trees in 1996 and 1997. Low night (2.5 and 5.2°C) but ambient day soil temperatures (above 10°C) did not affect stomatal conductance (gs), leaf (Ψleaf) and stem (Ψstem) water potentials. Soil temperature levels inducing water stress in olive trees were determined for winter days with ET0 typical for southern Spain (ET0= 1.5 ± 0.3 mm day−1). Leaf and stem water potential decreased and root hydraulic resistance (rroot) increased when trees were exposed to night and day soil temperatures below 10°C. Stomatal conductance was not affected at soil temperatures between 6.4 and 10°C, but decreased at temperatures below 6.4°C. The soil temperature levels affecting the water uptake of olive trees remained relatively constant over the range of ET0 of 1-2 mm day−1 during winter and early spring months. However, the soil temperature influencing gs appeared to be more variable and was affected by ET0. Olive tree recovery from low soil temperature stress depended on stress duration and severity and interacted with ET0. Recovery of ψ started already during the stress period, probably induced by stomatal closure and high rroot, thus allowing tree rehydration overnight. Root hydraulic resistance contributed the major part of whole-tree hydraulic resistance in response to cold stress, accounting for 76 and 89% at 6.4 and 4.6°C, respectively; which indicates that rroot is the primary control of the water status in olive trees under low temperatures.

Notes: The effects of the ratio of Rubisco activase to Rubisco (activase/Rubisco ratio) on light dependent activation of CO2 assimilation were investigated during leaf aging of rice. Changes of photosynthetic CO2 gas exchange rates in relation to step increases of light intensity from two photon flux densities of 60 µmol m−2 s−1 (low initial PFD) and 500 µmol m−2 s−1 (high initial PFD) to saturated PFD of 1 800 µmol m−2 s−1 were measured. These photosynthetic activation processes were considered to be limited by the Rubisco activation rate when analyzed by the relaxation method. The relaxation time of low initial PFD gradually declined from 3 to 33 days after leaf emergence and showed high and negative correlation to the activase/Rubisco ratio. The initial rate of Rubisco activation under low initial PFD linearly correlated to the amounts of Rubisco activase, whereas these were almost constant from 3 to 23 days after leaf emergence. But these correlations could not be recognized in the case of high initial PFD. Moreover, the relaxation times were more sensitive to intercellular CO2 concentration (Ci) under high initial PFD than under low initial PFD, especially, at Ci below 300 µl l−1. These results suggest the involvement of the activase/Rubisco ratio in the photosynthetic activation under relatively low initial PFD, and the limitation of photosynthetic activation under relatively high initial PFD by Rubisco carbamylation during leaf aging of rice.

Notes: Peroxidase (EC 1.11.1.7) activity from homogenized tissue or in apoplastic fluid was analyzed along the developmental gradient of expanding B73 maize (Zea mays L.) leaf blades. Soluble plus ionically bound peroxidase activity from homogenized tissue was present in high levels at the leaf base, which includes the region of cell division, and decreased as tissue was displaced away from the base by growth. A different pattern of change in peroxidase activity was seen in apoplastic fluid extracted from segments of intact tissue, where an increase in peroxidase activity preceded a rapid decrease in leaf elongation rate. Similar patterns in peroxidase activity from homogenized and intact tissue have been found in leaf blades of tall fescue (Festuca arundinacea Schreb.), suggesting a common phenomenon. At the location within the elongation zone where the increase in apoplastic peroxidase activity occurred, the activities of neutral and acidic (pl 4.6) peroxidase isoforms were also elevated in both the homogenate and in apoplastic fluid. The coincidence of these isoforms with the decline in leaf elongation rate suggests they may contribute to cessation of growth. At the distal end of the elongation zone, the activities of other acidic peroxidases (pI 5.6 and 5.7) increased in the homogenate and in apoplastic fluid, and remained elevated as tissue was displaced into the maturation region. The location of their appearance and their relatively high activity in the maturation region suggest the involvement of these isoforms in lignification.

Notes: Hexanal and cis-3-hexenal are principal flavor volatiles in ripe tomato fruit, but whether they accumulate during ripening or are formed upon maceration of the tissue has not been clarified. This has been addressed by measuring levels of these aldehydes in green and ripe fruit with discrimination between intrinsic aldehyde content and aldehyde generation following tissue disruption. Volatile sampling of tomato fruit homogenates was accomplished by purge/trapping, followed by thermal desorption on a gas chromatograph equipped with a mass selective detector. Incubation of some samples with alcohol dehydrogenase to convert the aldehydes to their respective alcohols permitted positive identification of the isomeric form of hexenal as cis-3-hexenal. Red and green tomato fruit homogenized in buffer with saturated CaCl2 contained low (0.1-0.8 µg g−1 fresh weight) levels of hexanal and cis-3-hexenal; thus there is minimal endogenous volatile content in intact fruit. Volatile levels increased rapidly, up to 10-fold, following homogenization of ripe tomato fruit in the absence of CaCl2, and more modestly in corresponding green tomato fruit homogenates. Incubation with the appropriate lipoxygenase/hydroperoxide lyase substrate (linoleic acid for hexanal, linolenic acid for cis-3-hexenal) doubled the amount of volatile compound produced. Hexanal generation was suppressed in the presence of linolenic acid, suggesting that the enzyme complex has greater affinity for this substrate. As well, levels of cis-3-hexenal, but not hexanal, tended to decline within 30 min of homogenization, possibly reflecting a specific degradative process. The results collectively indicate that the contribution of six-carbon aldehydes to tomato fruit flavor is attributable to metabolism invoked following tissue disruption rather than within the intact fruit.

Notes: A protein kinase (PK-II), phosphorylating casein, was purified from ripening mango, Mangifera indica L., fruit tissue. The purification procedure consisted of ammonium sulphate fractionation and sequential anion exchange-, dye-ligand, and gel filtration chromatography. The enzyme was purified over 500-fold to near homogeneity with a recovery of 4%. The purified enzyme had a specific activity of ca 1 µmol mg−1 protein min−1 with ATP as phosphoryl donor. SDS-PAGE results indicated a monomeric enzyme with molecular mass of 35 kDa. The protein kinase phosphorylated the acidic substrates casein and phosvitin, but had a very low activity with histones and protamine sulphate. The optimum pH and temperature for catalysis were determined to be 9.6 and 35°C, respectively. Mn2+ could not substitute for the Mg2+ needed for activity and Ca2+ had a slight stimulatory effect. Phospholipids, cAMP, calmodulin and the calmodulin inhibitor, calmidazolium, did not have any significant effect on activity, but the enzyme was inhibited by heparin and the specific inhibitor, CKI-7, (N-[2-aminoethyl]-5-chloroisoquinoline-8-sulphonamide). Autoradiographic studies revealed the ability of the protein kinase to autophosphorylate as well as the presence of endogenous protein substrates in the crude extract. Initial velocity studies with casein as substrate and product inhibition studies with ADP indicated a Km (ATP) and Km (casein) of 14 µ M and 0.18 mg ml−1, respectively, with a Ki (ADP) of 3.2 µM. The enzyme can be classified as a casein kinase I type of protein kinase (EC 2.7.10).

Notes: Stem elongation can be suppressed by a temperature drop at the onset of the photoperiod (DROP) or with a cooler day than night temperature (DT and NT, respectively), commonly described as DIF (DT - NT). To test our hypothesis that phytochrome A (phyA) mediated the reduction of stem elongation caused by −DIF and DROP, we conducted experiments with photomorphogenic mutants of tomato (Solarium lycopersicon L.) and transgenic potato (Solarium tuberosum L.). The plants studied were tomato mutants fri1 (deficient in phyA) and tri3 (deficient in phytochrome B1 [phyBl]) and their isogenic wild-type (WT) cv. Moneymaker, nontransformed potato, and two lines each of antisense phyA (15-9 and 15-11) and overexpressed phyA (PS-2 and PS-4). Plants were placed in three temperature regimens with a daily mean of 20°C: a constant 20°C (0 DIF), an 8°C DROP for 3 h, and a - 8°C DIF. For all tomato genotypes, −DIF and DROP reduced intemode length by ≥ 21% and stem elongation by 30% compared to that of plants at 0 DIF. Interactions between temperature treatment and genotype were nonsignificant. For potato, −DIF, but not DROP, significantly reduced intemode length of WT (by 39%) and both antisense lines (by 36 or 48%) but only one of the two lines of overexpressed phyA plants (by 18%). The −DIF significantly reduced stem length for only antisense phyA (by 36 or 48%) and WT (by 35%) plants. Thus, at least for tomato and potato, it appears that phyA does not control stem extension in relation to cool-temperature treatments.

Notes: Purified preparations of NAD(H)-glutamate dehydrogenase (GDH, EC 1.4.1.2.) were assayed to determine the effects of mono- and divalent cations, nucleotides and select carbon compounds on NAD(H)-dependent GDH activity. The amination reaction was stimulated 2- to 17-fold by divalent cations (Ca2+ 〉 Cd2+ 〉 Co2+ 〉 Mg2+ 〉 Mn2+ 〉 Zn2+ between 1 and 1000 µM), but the reaction was unaffected by monovalent cations (Na + and K +). The amination reaction was most responsive to changes in Ca2+ in a NADH-dependent manner. The addition of EDTA or EGTA nullified the stimulatory effects of Ca2+. Calmodulin alone or in combination with calmodulin antagonists did not affect the amination reaction. Divalent cations (at 1 mM) inhibited the rate of the deamination reaction by 15 to 25%, while monovalent cations had no effect. ATP inhibited the amination reaction by 10 to 60%, while ADP had little or no effect. ATP or ADP decreased the rate of the deamination reaction 23 to 60 or 20 to 38%, respectively. Many tricarboxylic acid cycle intermediates inhibited the amination reaction, 20 to 50% of the inhibition could be attributed to the chelating capacity of intermediates. Conversely, most of the carbon sources tested did not affect the deamination reaction, the only appreciable differences were increases in activity with sucrose (21%) and glucose (41%) and a decrease in activity with pyruvate (34%). Inhibitors of sulfhydryl groups were used to examine the importance of reduced thiol groups in the amination or deamination reactions. The amination was not dependent on reduced thiol groups, whereas the deamination reaction was dependent on reduced thiol groups.

Notes: The mechanism of cobalt uptake was investigated using cells of the giant alga Chara corallina in which it is possible to resolve separately uptake by the cell wall and actual influx across the cell membrane. The absorption of 60Co by Chara cells appeared to saturate within 2 h, but this was mainly due to rapid uptake into the cell wall which accounted for 87–92% of the total activity. Even after prolonged desorption most of the cell-associated 60Co was found on the cell wall. The intracellular distribution of absorbed 60Co was investigated by fractionating the cell into cytoplasm and vacuole. It was shown that 60Co influx to the vacuole occurs simultaneously with influx to the cytoplasm. The transported species appears to be Co2+ rather than the less charged Co(OH)+ or Co(OH)2. 60Co influx is pH dependent (optimum pH 7–9), and is sensitive to some other divalent metals. Influx from solutions containing 1 µM60Co was inhibited by 5 µM Cd2+, Cu2+, and Zn2+, but Mn2+ and Ni2+ had no significant effect. The sensitivity of Co uptake to N-ethyl maleimide (NEM) and cysteine suggests that the transport system involves direct binding of CO2+ to -SH groups.

Notes: Experiments were carried out to evaluate the effects of exposure to nitric oxide on the ability by NADPH-dependent microsomal electron transfer to generate oxygen radicals. Such interactions could play a role in the potential antioxidant action of nitric oxide (NO). Isolated microsomes from soybean (Glycine max [L.] Merr. cv. Hood) embryonic axes were exposed to an exogenously added source of nitric oxide (NO) (S-nitrosoglutathione + dithiothreitol). The O2− generation rate by microsomes exposed to NO decreased significantly as compared to the rate measured in microsomes incubated in the absence of NO. The exposure of the microsomes to the NO donor did not alter the microsomal rate of hydroxyl radical generation. Preincubation of the microsomes with the NO donor affected neither iron reduction rate nor activity of cytochrome c reductase. However, cytochrome P450 activity was significantly inhibited after exposure to NO. This inhibition was completely prevented by hemoglobin. The data are consistent with the hypothesis that NO exhibits a potential antioxidant role in the plant cell by decreasing the rate of generation of superoxide anion. Since endogenous NO was detected in homogenates of soybean embryonic axes by EPR studies, this interaction between NO and cytochrome P450 in soybean embryonic axes could be a factor of relevance for the control of oxidative stress in vivo.

Notes: Three soluble invertase (EC 3.2.1.26) isoforms from Easter lily (Lilium longiflorum Thunb. cv. Nellie White) flower buds were purified to apparent homogeneity. Non-denaturing PAGE showed one band for all three invertases that corresponded to the invertase activity. SDS-PAGE of purified invertase I gave a single band at 78 kDa, whereas invertases II and III gave three bands at 54, 52 and 24 kDa. Antibodies against tomato fruit acid invertase and Urtica dioica leaf acid invertase recognized all three invertase isoforms, whereas antibodies against wheat coleoptile acid invertase recognized only 56- and 54-kDa bands of invertases II and III. Antibodies against wheat coleoptile invertase recognized the 54- and 52-kDa proteins from crude extracts of all flower organs, and a 72-kDa protein in both leaf and bulb scale extracts. All three invertases bound to Con-A peroxidase. Deglycosylation of invertase I with glycopeptidase F was complete and resulted in a peptide of 75 kDa. Invertases II and III were deglycosylated partially by glycopeptidase F and resulted in proteins of 53, 51, 50 and 22 kDa. Invertase I was localized only in anther and filament, whereas the other two isoforms were present in all flower organs.

Notes: Starch represents the major component of virtually all plant-derived foods consumed by man and animal. Hence, a thorough understanding of the starch biosynthetic pathway is critically important not only in understanding the biosynthesis of a major plant storage product, but also in allowing the genetic manipulation of both starch quality and quantity for human benefit. A major goal in these studies has been the identification of key steps in controlling starch levels. Evidence from a number of independent approaches clearly points to the enzyme adenosine diphosphate glucose pyrophosphorylase (AGPase) as a key regulatory step in starch synthesis. Here we highlight and summarize our understanding of this important enzyme.

Notes: In a chilling-sensitive plant, cucumber, chilling of leaves in the light results in irreversible damage to PSI. Recent in vitro studies suggested that hydroxyl radicals, which are formed in the presence of H2O2 and reduced Fe-S centers, are involved in the PSI inhibition. We therefore examined this possibility in vivo. Chilling of leaves at 5°C in the light caused a temporary increase in H2O2 concentration, which was probably due to the net H2O2 production in vivo. The activity, measured at 5°C, of the thylakoid ascorbate peroxidase (APX), a key enzyme of the H2O2-scavenging system, was about 20% of that measured at 25°C. The isolated thylakoids retaining high thylakoid APX activity did not show light-dependent net H2O2 production at 25°C. However, at 5°C, net production of H2O2 was observed. Since the rate of electron flow to molecular oxygen in the isolated thylakoids was ca 5 mmol e− mol−1 Chl s−1 at 5°C, the H2O2-scavenging capacity was below this level. When intact leaves were illuminated at 5°C at an irradiance of 100 µmol m−2 s−1, the rate of electron transport through PSII was ca 20 mmol e− mol−1 Chl s−1 and more than 80% of QA was in the reduced state. Since thylakoids are uncoupled in cucumber leaves at 5°C in the light. ATP is not formed and energy dissipation in the form of heat is suppressed. Therefore, the electron flow to molecular oxygen would be greater than 5 mmol e− mol−1 Chl s−1. Moreover, under such conditions, components in the electron transport chain, including Fe-S centers in PSI, were probably reduced. These features indicate that, when cucumber leaves are chilled in the light, hydroxyl radicals can be produced by the Fenton reaction and cause damage to PSI.

Notes: Prior work demonstrated that Heuchera americana, an evergreen herb inhabiting the deciduous forest understory in the southeastern United States, has a 3-4-fold greater photosynthetic capacity under the low-temperature, strong-light, open canopies of winter compared to the high-temperature, weak-light, closed canopies of summer. Moreover, despite the reductions in soil nitrogen, the chilling temperatures, and the increased quantum flux associated with winter, chronic photoinhibition was not observed in this species at this time of the year. We were interested in the photosynthetic acclimation and photoinhibition characteristics of this species when grown under contrasting light and nitrogen regimes. Newly expanded shade-acclimated leaves of forest-grown plants exposed to strong light varying in intensity and duration at 25°C showed a reduction in Fv/Fm (the ratio of variable to maximum room temperature chlorophyll fluorescence measured after dark adaptation), which was correlated with a decline in øa (the intrinsic quantum yield of CO2-saturated O2 evolution on an absorbed light basis). Plants grown in the glasshouse under contrasting light (high and low light; HL and LL, respectively) and nitrogen supply (high and low nitrogen; HN and LN, respectively) regimes showed that photosynthetic acclimation to HL was impaired in LN regimes. The HL-LN plants also had the lowest values of Fv/Fm and of ø on both incident and absorbed light bases and had 50% less chlorophyll (per unit area) compared to plants from other growth regimes. Controlled exposure to bright light at low temperatures (2-3°C) for 3 h resulted in a sharp decrease in Fv/Fm (and rise in Fo, the minimum fluorescence yield) in all plants. Shade-grown plants from both N regimes were highly susceptible to chronic photoinhibition, as indicated by a greater reduction in Fv/Fm and incomplete recovery after 18 h in weak light at 25°C. The HL-HN plants were the least susceptible to chronic photoinhibition, having the smallest decrease in Fv/Fm with near full recovery within 6 h. The decline in Fv/Fm in HL-LN plants was comparable to that of shade-acclimated plants, but recovered fully within 6 h. Low-N plants from both light regimes displayed greater increases in Fo which did not return to pretreatment levels after 18 h of recovery. These studies indicate that HL-LN plants were sensitive to chronic photoinhibition and, at the same time, had a high capacity for dynamic photoinhibition. Experimental garden studies showed that H. americana grown in an open field in summer were photoinhibited and did not fully recover overnight or during extended periods of weak light. These results are discussed in relation to the photosynthetic acclimation of H. americana under natural conditions.

Notes: Protoplasts isolated from pear fruit at the end of the cell-division stage, 30 days after flowering (DAF), had already formed a large central vacuole and the vacuole occupied most of the protoplast. The changes in protein composition and density of the tonoplast (vacuolar membrane) were investigated during fruit development. After a linear sucrose density gradient centrifugation, the distribution of tonoplasts at 30 and 48 DAF was broad and began to narrow with further fruit development. This suggests that the tonoplast of young fruit is heterogeneous and becomes homogeneous with fruit development. The apparent density of the tonoplast at 30 DAF was approximately 1.12 g ml−1; it decreased with fruit development and was finally 1.09 g ml−1 in mature fruit. The phospholipid amount on the basis of tonoplast protein was 0.80 mg mg−1 at 30 DAF. It increased with fruit development, and finally reached 7.49 mg mg−1. This result indicates that the decrease in the density of the tonoplast was caused by the increase in the ratio of phospholipid to membrane protein. The protein composition of the tonoplast at each stage was quite different. The level of polypeptides of 94, 70, 61, 52, 48 and 41 kDa was low in young fruit and high in the middle or later stages of fruit development. In contrast, the level of a 76-kDa polypeptide was high in young fruit and decreased with fruit development. Although their functions are still unclear, these tonoplast proteins may play important roles in fruit development.

Notes: Abstract In laboratory experiments, we investigated two task/ambient conditioning systems with air supplied from desk-mounted air outlets to efficiently ventilate the breathing zone of heated manikins seated at desks. In most experiments, the task conditioning systems provided outside air while a conventional ventilation system provided additional space cooling but no outside air. Air change effectiveness (i.e., exhaust air age divided by age of air at the manikin's face) was measured with a tracer gas step-up procedure. Other tracer gases simulated the release of pollutants from nearby occupants and from the floor covering, and the associated pollutant removal efficiencies (i.e., exhaust air concentrations divided by concentrations at manikin's face) were calculated. High values of air change effectiveness (∼1.3 to 1.9) and high values of pollutant removal efficiency (∼1.2 to 1.6) were measured when these task conditioning systems supplied 100% outdoor air at a flow rate of 7 to 9 L s-1 per occupant. Air change effectiveness was reasonably well correlated with the pollutant removal efficiency. Overall, the experimental data suggest that these task/ambient conditioning systems can be used to improve ventilation and air quality or to save energy while maintaining a typical level of IAQ at the breathing zone.

Notes: Abstract Sixteen flights had been investigated for indoor air quality (IAQ) on Cathay Pacific aircraft from June 1996 to August 1997. In general, the air quality on Cathay Pacific aircraft was within relevant air quality standards because the average age of aircraft was less than 2 years. Carbon dioxide (CO2) levels on all flights measured were below the Federal Aviation Administration (FAA) standard (30,000 ppm). The CO2 level was substantially higher during boarding and de-boarding than cruise due to low fresh air supply. Humidity on the aircraft was low, especially for long-haul flights. Minimum humidity during cruise was below the American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE) minimum humidity standard (20%). The average temperature was within a comfortable temperature range of 23±2°C. The vertical temperature profile on aircraft was uniform and below the International Standard Organization (ISO) standard. Carbon monoxide levels were below the FAA standard (50 ppm). Trace amount of ozone detected ranged from undetectable to 90 ppb, which was below the FAA standard. Particulate level was low for most non-smoking flights, but peaks were observed during boarding and de-boarding. The average particulate level in smoking flights (138 (ig/m3) was higher than non-smoking flights (7.6 μg/m3). The impact on IAQ by switching from low-mode to high-mode ventilation showed a reduction in CO2 levels, temperature, and relative humidity.

Notes: Abstract The chemical and sensory emissions from five building materials (carpet, polyvinyl chloride (PVC) flooring, sealant, floor varnish and wall paint) were tested under different combinations of temperature and relative humidity in the ranges 18–28°C and 30–70% relative humidity (RH). The experiment was performed in a climate chamber where a specially designed test system was built to study emissions from the five materials. The test system could provide different temperatures and humidities of air around the materials, while the air, after being polluted by the emissions from the materials, could be reconditioned to 23°C and 50% RH for sensory assessments. The experiment was designed to separate the direct impact of temperature and humidity on perception from the impact on sensory emission. The study found little influence of temperature on the emissions from the five materials whether expressed in chemical or sensory terms. The effect of humidity was found to be significant only for the waterborne materials – floor varnish and wall paint. Compared with the direct impact of temperature and humidity on the perception of air quality, the impact of temperature and humidity on sensory emissions from the building materials has a secondary influence on perceived air quality.

Notes: Abstract Volatile organic emissions from particleboard, medium density fibreboard (MDF) and office furniture have been measured in dynamic environmental chambers, both small and room-sized. Characterisation of product emission properties in small chambers was possible when inter- and intra-sheet variations were considered. Formaldehyde emission factors for all products were approximately double European low-emission specifications and did not decay to the latter for several months. Long-term emission behaviour could not be predicted from short-term measurements. Volatile organic compounds (VOC) emissions were low for the MDF product, higher for particleboard, and highest for laminated office furniture. The compounds emitted differed from those reported in other countries. VOC emissions from the sheet products decreased more quickly than formaldehyde, reaching low levels within two weeks, except for MDF which was found to become a low-level source of hexanal after several months.

Notes: Abstract Birch and grass pollen grains as well as pollen-derived small particles appear as potent allergens in the outdoor air during spring and summer. The occurrence of pollen allergens in indoor air, however, has not been studied in depth due to lack of suitable sampling and analytical methods. Herein, a recently reported “direct on sampling filter estimation” (DOSAFE) technique (Acevedo et al., 1998) has been validated for quantification of pollen allergens in indoor air using two school rooms and two office rooms as experimental models. Using DOSAFE and polyclonal antibodies against water extracts of pollen from Betula pendula and Phleum pratense L, we found that indoor air of school and office rooms carried substantial amounts of pollen allergens, expressed as SQ units, predominantly occurring as particles with smaller diameters than the pollen grains. In one school room the indoor air birch pollen allergen concentrations increased from 242 to 403 SQ units/m3 over the sampling period although the corresponding outdoor air concentrations decreased from 350 to 90 SQ units/m3. Electrostatic air cleaning in one office room reduced its grass pollen allergen concentrations by more than 95% to 0.02–0.34 SQ units/m3 as compared to the control room.

Notes: Abstract Polyurethane products were subjected to chamber testing to determine their emission rates of 2,4- and 2,6-toluene diisocyanate (TDI). The polyurethane (PU) products included carpet padding, furniture cushions, sheet foam, varnishes, and sealants, as well as a commercially-applied water sealant product for concrete that contained up to 4 percent TDI by weight. The PU products were screened in a 9-L glass chamber, under elevated temperature and chamber loading conditions, using both a time-integrated sampling and analysis method specific for TDI and a continuous but non-specific real-time monitor for isocyanates. None of the products normally found in residences showed a positive response in the screening tests, indicating that TDI emissions and consequently toxic effects from such products are negligible. However, the commercially-applied water sealant gave a positive response in the screening test. Further testing of that product at realistic temperatures showed initial TDI emission rates of about 300,000 μg/m2/hr, with emissions lasting only one hour or less. At 21 and 27°C, about 1 percent and 5 percent, respectively, of the TDI content of the product was released to the air. The emitted TDI was predominantly the 2,6-isomer, although the TDI originally present in the product was predominantly the 2,4-isomer.

Notes: Abstract A simple test chamber method to quantify adsorption and desorption of organic compounds on material surfaces is described. Important environmental parameters such as temperature, relative humidity and air velocity were varied and controlled independently around typical indoor values. Experiments were performed with α-pinene and toluene in concentrations of 160-300 μg/m3. The measurements show adsorption on and desorption from wool carpet, nylon carpet, polyvinyl chloride (PVC) floor coverings, cotton curtain material and the empty chamber. The ranking of the materials, with respect to their sorption capacity, is as mentioned above. The adsorption of α-pinene was higher than the adsorption of toluene for all the materials. Air velocity was not found to influence the sorption of α-pinene and toluene on wool carpet, tested with air velocities at 0, 10 and 20 cm/s. The experiments were carried out during both the adsorption and the desorption phase. The uncertainty of the experiments was lowest during the desorption phase. Based on the results obtained, it can be recommended that sorption experiments should be performed as desorption phase experiments. A one-sink model, based on the Langmuir adsorption isotherm, appears adequate to describe the results.

Notes: Abstract Walk through questionnaires may be feasible tools to obtain data on the indoor environment in community studies. However, limited information is available regarding the reproducibility of the data obtained through these questionnaires. In this pilot study, two construction engineering students inspected ten dwellings twice by means of a standardized walk through questionnaire. The two engineering students inspected the dwellings independent of each other within two months. Time between the two visits varied between 14 and 40 days. The variables presented were based on information from the residents and inspection. The continuous variables recorded included number of rooms in the dwellings, room volume, length of filled shelves and textile area. The inter- and intra-observed variabilities were poorer for number of rooms and shelf factor than for the other variables. For the 3 of the 9 categorical variables based on inspection, the inter-observer comparison showed complete agreement with a kappa statistics of 1.0, these variables being condition of the window frames and construction of outside walls and roof. One of the categorical variables showed a kappa statistics of 〈0.5, these variables being presence of basement and presence of condensation at windows. This study indicates a wide variation in observer variability between various items of a walk through questionnaire. Clear definitions of all the parts of the questionnaire are needed, as well as thorough training of observers.

Notes: Abstract Data of chemical emissions from flooring materials have been collected and investigated in a database known as METS. The emission tests are performed using the Field and Laboratory Emission Cell (FLEC). The emission rates of total volatile organic compounds (TVOC) in the boiling point range of hexane to octa-decane varies from around 4,000 μg/(m2· h) to less than 10 μg/ (m2· h). Results obtained 1994/95 are presented and compared with the results obtained in 1992 for similar materials. The tests are performed 4 weeks and 26 weeks after the manufacturing of the material. The emission rates of TVOC decrease on the average approximately 60% from 4 to 26 weeks. The differences and trends in emission rates of individual chemicals and their use are discussed. For many VOCs emission rates decrease rapidly and become near to or below 2 μg/(m2· h) (the detection limit) after 26 weeks. For a small number of individual compounds the emission rate decrease little over 26 weeks. A small number of chemicals are singled out for particular interest in a health and comfort evaluation based on the emission results.

Notes: Abstract Various studies on indoor and outdoor particulate matter in the urban environment in the vicinity of busy arterial roads in the centre of the subtropical city of Brisbane have indicated that the revised United States Environmental Protection Agency National Ambient Air Quality Standards (US EPA NAAQS) for Particulate matter PM2.5 could be exceeded not only outdoors but also indoors. The aim of this work was to investigate outdoor exposure to submicrometer particles and their relationship with indoor exposure in a hypothetical office building located in the vicinity of a busy arterial road. The outdoor exposure values and trends were measured in terms of particle number in the submicrometer size range and were then recalculated to represent mass concentration trends. The results of this study indicate that exposure to PM0.7 particles in ambient air close to a busy road often exceeds the levels of the annual and 24-hour US EPA NAAQS PM2.5 standards. It is likely that exposure to PM2.5 is even higher, and may significantly exceed these standards.

Notes: Abstract Eighteen laboratories from 10 European countries participated in a comparison organized as part of the VOCEM project, a 2.5-year research collaboration among 4 research institutes and 4 industrial companies. The scope of the project was to improve the procedure used to measure volatile organic compounds (VOC) emitted from building materials and products in small test chambers. The interlaboratory comparison included the GC-MS determination of 5 target compounds from carpet, 8 from polyvinyl chloride (PVC) cushion vinyl and 2 from paint; for the first time, chamber recovery (sinks), homogeneity of solid materials and possible contamination during transport were tested. The results show that the intralaboratory variance (random errors) is much smaller than the interlaboratory variance (systematic errors). Causes of the largest interlaboratory discrepancies were: (i) analytical errors; (ii) losses of the heaviest compounds due to sorption on the chamber walls; and (iii) non homogeneity of the materials. The output of this work concerns both the objective of labelling materials with regard to their VOC emissions and the pre-standard drafted by the European Commitee for Standardization (CEN) for this type of determination.

Notes: Abstract To ensure prompt response by real-time air monitors to an accidental release of toxic aerosols in a workplace, safety professionals should understand airflow patterns. This understanding can be achieved with validated computational fluid dynamics (CFD) computer simulations, or with experimental techniques, such as measurements with smoke, neutrally buoyant markers, trace gases, or trace aerosol particles. As a supplementary technique to quantify airflows, the use of a state-of-the art, three-dimensional sonic anemometer was explored. This instrument allows for the precise measurements of the air-velocity vector components in the range of a few centimeters per second, which is common in many indoor work environments. Measurements of air velocities and directions at selected locations were made for the purpose of providing data for characterizing fundamental aspects of indoor air movement in two ventilated rooms and for comparison to CFD model predictions. One room was a mockup of a plutonium workroom, and the other was an actual functioning plutonium workroom. In the mockup room, air-velocity vector components were measured at 19 locations at three heights (60, 120 and 180 cm) with average velocities varying from 1.4 cm s−1 to 9.7 cm s−1. There were complex flow patterns observed with turbulence intensities from 39% up to 108%. In the plutonium workroom, measurements were made at the breathing-zone height, recording average velocities ranging from 9.9 cm s−1 to 35.5 cm s−1 with turbulence intensities from 33% to 108%.

Notes: Abstract The age of the air in a room is normally determined either from a pulse response or from a step change response (up or down). There are a certain number of problems involved in applying these two theoretical models, especially those associated with the duration of the injection, which must either be infinitely short or infinitely long. A hybrid method that consists of injecting a known quantity of tracer for a given time offers the advantages of both methods. The equation for calculating age is exact, regardless of the type of flow considered, and is derived from the expressions already established for a pulse response to which a correction is included to account for the tracer generation function. If a rectangular pulse is used for the injection, the solution is particularly simple.

Notes: Abstract The aim of the study was to describe how allergies and non-allergies perceive the same environment. All high school students in a town in southern Sweden were invited to answer a questionnaire concerning allergy, subjective symptoms, annoyance reactions and perception of the environment (response rate: 81%). The results show that only 45% of the students were non-allergic (n = 1,715). Since the symptom frequency among non-allergic students was normal, the schools were classified as healthy. However, compared to the non-allergic students, a higher percentage among the allergies suffered from symptoms every week, a lower percentage was satisfied with the air quality and the cleaning, and a higher percentage was bothered every week by temperature, stuffy/stale air, bad odor, passive smoke, bad lighting, noise, dust and dirt (ANOVA, P 〈 0.05). The findings could indicate that allergies note discomfort earlier than non-allergies by being more critical in general and especially critical to factors that could effect their health. The findings could also indicate that awareness of ones own sensitivity could lead to attention to different risk factors, which in turn could lead to stress/anxiety, which could make symptoms worse. The conclusion is that it is important to take allergy into consideration when the environment is assessed.

Notes: Abstract Five classrooms, air-conditioned or naturally ventilated, at five different schools were chosen for comparison of indoor and outdoor air quality. Temperature, relative humidity (RH), carbon dioxide (CO2), sulphur dioxide (SO2), nitric oxide (NO), nitrogen dioxide (NO2), particulate matter with diameter less than 10 mm (PM10), formaldehyde (HCHO), and total bacteria counts were monitored at indoor and outdoor locations simultaneously. Respirable particulate matter was found to be the worst among parameters measured in this study. The indoor and outdoor average PM10 concentrations exceeded the Hong Kong standards, and the maximum indoor PM10 level was even at 472 μ;g/m3. Air cleaners could be used in classrooms to reduce the high PM10 concentration. Indoor CO2 concentrations often exceeded 1,000 μl/l indicating inadequate ventilation. Lowering the occupancy and increasing breaks between classes could alleviate the high CO2 concentrations. Though the maximum indoor CO2 level reached 5,900 μl/l during class at one of the sites, CO2 concentrations were still at levels that pose no health threats.

Notes: Abstract The influence of a thermal heterogeneity boundary conditions on the air change efficiency (ACE) of a mechanical ventilation system in a test room was experimentally evaluated by means of the “step-down” tracer gas technique in 24 different experimental conditions. The experiments were performed under isothermal condition, varying the air supply temperature with respect to the walls and varying the surface temperature of a wall with respect to the other walls and the supply air, simulating both heating and cooling situations. Changing the position of the outlet grid two different configurations of the ventilation system were tested. The nominal supply air velocity varied between 0.04 and 0.11 m/s, corresponding to a range from 1 to 3 ach, and the temperature differences varied from 0 to 5°C. Results are reported in terms of air change efficiency indexes, both local and global. The global air change efficiency (ACE), values are presented as a function of the Archimedes number (Ar), whose values were in the range 0 to 181. The reported results suggest that the Ar number may be used to organize the ACE values when in the presence of thermal heterogeneity, both in the external envelope and in the supplied air. The obtained results show that there is a logarithmic relation between Ar and ACE. In particular, for both ventilation strategies tested, the increase of the absolute value of Ar leads to an increase of ACE when the supply air is warmer than the walls, and to a decrease of ACE when the supply air is colder than the walls. Under isothermal conditions the Reynolds number (Re) fairly correlates the experimental results.

Notes: Abstract Emission models developed using small chamber data were combined with an Indoor Air Quality (IAQ) model to analyze the impact of volatile organic compound (VOC) emissions from latex paint on indoor environments. Test house experiments were conducted to verify the IAQ model's predictions. The agreement between model predictions and experimental measurements met the American Society for Testing and Materials criteria for model verification in the room with the source and met most of the requirements in other rooms. The major cause of disagreement between the model predictions and the experimental data in the test house appears to be an inadequate sink model.

Notes: Abstract Aerosol particles in municipal atmospheres are of increasing public health concern; however, since most of our time is spent indoors, indoor aerosols must be researched in counterpart. Compact High-Efficiency Particulate Air (HEPA) filter systems are commonly employed in residences to alleviate airborne dust concentrations. In this study, a detailed and original methodology was used to determine concentrations and types of submicrometer aerosols, as well as of large (〉4 μm) dust particles. Scanning electron microscopy was used to quantify and characterize ambient aerosols collected from filtered and non-filtered rooms. Particle concentrations were significantly lower in samples collected in the presence of the filter system (mean 23 to 8 coarse particles liter−1, 63% reduction; 13 to 3 inorganic submicron particles cm−3, 76% reduction; 85 to 33 total submicron particles cm−3, 62% reduction; all P 〈 0.05). This study provides a new methodology for analysis of indoor aerosols and new data on their physico-chemical characteristics. Since the filter systems are effective at reducing submicron aerosol concentrations, they may improve the health of individuals such as asthmatics, who experience health problems caused by anthropogenic fine particles.

Notes: Abstract This paper reports the development of methods for calculating a ventilation performance metric that is a measure of the airflow pattern in a room or zone of a multi-zone ventilation system. Temporal mixing theory is used as the basis for these methods. The methods are applicable to all ventilated systems that can be modeled as a set of interconnected chambers. Relations between the ventilation performance metric defined in this paper and those defined previously are derived. The theoretical results of this paper are consistent with published experimental findings. They also illustrate that the conclusions in some experimental studies about the airflow patterns in working buildings may be incorrect. Re-analysis of previously published data illustrates how common features of mechanically ventilated buildings, such as recirculation of return air and multiple chambers, confound information about airflow patterns in tracer gas data. The calculation methods developed in this paper can be used to undo this confounding.

Notes: Abstract The exposure-response relationship between the concentration of air pollutants and perceived air quality was studied for eight materials often found indoors and for a mixture of three of the materials. Samples of the materials were placed in a ventilated test chamber. The exhaust air from the test chamber was diluted with different rates of unpolluted air to obtain five different concentrations of polluted air. A sensory panel assessed the perceived quality of the five concentrations of polluted air. The exposure-response relationship differed between the materials and also from the corresponding relationship for human bioeffluents. The exposure-response relationships can be described by straight lines in a log-probit plot and be defined by two constants characteristic for each material. Determination of the two constants characterizing each material requires sensory assessments at least at two pollution concentrations. The sensory pollution load for a material may change with the pollution concentration in the air. The use of a simple measurement method based on a dilution system connected to a ventilated small-scale test chamber is proposed to characterize the emissions from materials in sensory and chemical terms.

Notes: Abstract Fifty-nine houses in the small Canadian community of Wallaceburg, 39 with high levels of biologically active contaminants and 20 with low levels, were subjected to detailed field inspections: testing to determine house-operating parameters; monitoring of indoor environmental conditions; and simulating to predict the condensation formation potential under winter conditions. It was found that low air leakage and natural ventilation were not associated with higher levels of mold growth, as measured by ergosterol concentrations and airborne viable particulates. Analyses showed that moisture sources in the houses were a more significant factor in mold levels and dust mite antigen levels than relative humidity. Mold areas visible during inspection were not a good predictor of ergosterol concentrations in dust, indicating that much of the mold growth was in hidden locations.

Notes: Abstract Complaints about unpleasant odour from wall, ceiling and floor coverings made of composite cork, induced chamber tests to study the emissions of volatile organic compounds (VOC) from composite cork products for indoor use. Emissions of phenol and furfural were found to be high, particularly those from cork parquet. Emission factors after 1 week ranged from 150 to 650 μg m−2 h−1 and from 15 to 350 μg m−2 h−1 for phenol and furfural, respectively, and decreased only slowly over time, by a factor of approx. 10 for a 6-month period. The ranges of emission factors were found to be similar for some solvents such as cyclohexanone or toluene which are constituents of varnishes used to protect cork surfaces. The emission of furfural may result from chemical reactions in the cork during the production process or may be caused by additives such as binders.

Notes: Abstract This paper describes the measured and calculated results of airflow rates and pollutant concentration profiles in an airtight test house, the aim being to evaluate the calculation model COMIS for multizone air infiltration and pollutant transport. Firstly, the leakage areas of internal doors, exterior walls and windows were measured by the fan pressurization method. Secondly, two measurements were carried out, assuming that the test house consisted of ten zones. The concentrations and injection rate of SF6 were measured in order to determine the airflow rates by a system identification method. The boundary conditions, such as indoor and outdoor temperatures, wind speed and direction, and wind pressures were also recorded in situ and saved simultaneously on diskettes, using a computerized data acquisition system. Thirdly, the measured boundary data and leakage characteristics were used as input in the simulation of airflow using COMIS; initial concentrations, injection rate, along with the previous data were used for simulating pollutant transport, assuming tracer gas SF6 as a pollutant. Lastly, the comparisons between measurement and simulation results of airflow rates and pollutant concentrations were carried out by linear regression analysis. The correlation coefficient between the measured and calculated air change rates was 0.72, and that for pollutant concentration was 0.94.

Notes: Abstract Experiments were conducted to evaluate the survival time of randomly selected female D. farinae exposed to temperatures from 40 to 80°C and relative humidities (RHs) between 10 and 90%. Significant temperature effects were found on the length of time mites can survive under those conditions. The time needed to induce 100% mortality for female D. farinae held at 40°C varied between 39 and 84 h. At 70 and 80°C, all mites died within 5 minutes. At 50°C and above, RH had little influence and temperature alone was the determining factor for mite survival. The length of survival time decreased precipitously between 40 and 50°C, suggesting that a loss of physiological integrity of female D. farinae probably occurred in this range. The results of this study indicated that the technique of raising temperatures to above 40°C for a short duration can be used to reduce living house dust mite populations in homes significantly.

Notes: Abstract The effects of two substrates - a stainless steel plate and a gypsum board - on the volatile organic compound (VOC) emissions from a latex paint were evaluated by environmental chamber tests. It was found that the amount of VOCs emitted from the painted stainless steel was 2 to 10 times more than that from the painted gypsum board during the 2-week test period. The dominant chemical species emitted were also different between the two substrates. Data analysis indicated that most VOC emissions from the painted stainless steel occurred in the first 100 h via a fast, evaporation-like process. On the other hand, the majority of the gypsum board VOCs were emitted in a later stage via a slow, diffusion-controlled process. There were measurable emissions of VOCs 11 months after paint application on the gypsum board. It is suggested that, instead of the routinely used substrates such as stainless steel plates, real substrates such as wood or gypsum board should be used for the evaluation of emissions in indoor environments.

Notes: Abstract The existing literature contains strong evidence that characteristics of buildings and indoor environments significantly influence rates of respiratory disease, allergy and asthma symptoms, sick building symptoms, and worker performance. Theoretical considerations, and limited empirical data, suggest that existing technologies and procedures can improve indoor environments in a manner that significantly increases health and productivity. At present, we can develop only crude estimates of the magnitude of productivity gains that may be obtained by providing better indoor environments; however, the projected gains are very large. For the U.S., we estimate potential annual savings and productivity gains of $6 billion to $19 billion from reduced respiratory disease; $1 billion to $4 billion from reduced allergies and asthma, $10 billion to $20 billion from reduced sick building syndrome symptoms, and $12 billion to $125 billion from direct improvements in worker performance that are unrelated to health. Sample calculations indicate that the potential financial benefits of improving indoor environments exceed costs by a factor of 18 to 47. The policy implications of the findings are discussed and include a recommendation for additional research.

Notes: Personal exposure in a displacement ventilated room is examined. The stratified flow and the considerable concentration gradients necessitate an improvement of the widely used fully mixing compartmental approach. The exposure of a seated and a standing person in proportion to the stratification height is examined by means of full-scale measurements. A breathing thermal manikin is used to simulate a person. It is found that the flow in the boundary layer around a person is able to a great extent to entrain and transport air from below the breathing zone. In the case of non-passive, heated contaminant sources, this entrainment improves the indoor air quality. Measurements of exposure due to a passive contaminant source show a significant dependence on the flow field as well as on the contaminant source location. Poor system performance is found in the case of a passive contaminant released in the lower part of the room close to the occupant. A personal exposure model for displacement ventilated rooms is proposed. The model takes the influence of gradients and the human thermal boundary layer into account. Two new quantities describing the interaction between a person and the ventilation are defined.

Notes: Abstract Mechanical ventilation of workrooms was formerly based mainly on the dilution principle. In recent years, however, 50% of new investments in industrial ventilation in Scandinavia have been spent on displacement ventilation. Very little data exist from industrial settings on the relative performance of displacement ventilation versus dilution ventilation as regards air quality and thermal comfort. The present study collected data on the indoor climate in a sewing plant before and after the ventilation was changed from dilution to displacement. The indoor climate was evaluated by hygienic measurements of air pollution, temperature, air velocity, etc., and 40 employees were interviewed about perceived thermal comfort, air quality, and irritative symptoms.Changing the ventilation from dilution to displacement induced a slightly higher air change in the occupied zone of the plant and entailed higher temperature gradients. In spite of these findings, complaints of draught decreased significantly, and temperature was perceived to be more pleasant after the change. The air was perceived as less heavy and less dry, especially when humidification was added to the supply air. The improvements in the workers’ reports on the environment could not be attributed to placebo effects. Generally, the hygienic measurements were improved or unchanged after the change in ventilation system. Thus, displacement ventilation improved environmental conditions in this study. When adding humidification, this improvement was further sustained.

Notes: Abstract The air change effectiveness (ACE), an indicator of the indoor airflow pattern, was measured in twenty-six laboratory experiments. Ventilation air was supplied through induction-type diffusers located in the ceiling and removed through a ceiling mounted return grille. The tracer-gas step-up measurement procedure was employed. In five of the experiments, pollutant removal efficiencies were also measured for simulated pollutant emissions from the floor covering and for simulated emissions from occupants. In experiments with heated supply air, supply airflow rates typical of the minimum supply flow rates of VAV ventilation systems, and 100% outside air, the ACE ranged from 0.69 to 0.89. These results indicate that significant short-circuiting of ventilation air between the supply air diffuser and return air grille does occur under these adverse conditions. Mechanical recirculation of air, so that the supply air contained approximately 50% outside air, increased the ACE by about 0.05. When the supply air was cooled, the ACE ranged from 0.99 to 1.15, adding to existing evidence that short-circuiting is rarely a problem when the building is being cooled. The pollutant removal efficiency for simulated pollutant emissions from the floor covering (PREfloor) was strongly correlated with ACE (R2= 0.98) and the values of PREfloor were within approximately 0.1 of the values of ACE. The pollutant removal efficiency for simulated pollutant emissions by occupants varied between workstations and was not as well correlated with the ACE.

Notes: Abstract A simple method for quantifying dust on indoor non-textile surfaces has been developed and evaluated. The method uses gelatine foils to sample particles from surfaces, applying a constant pressure. The foils possess unique properties, making them particularly suitable for evaluation by light extinction. The amount of particles collected as measured by laser light extinction is expressed as the area percentage covered by particles. Foil sampling effectiveness has been estimated to range from 87% to 97%. A simple method for calibrating the instrument has been developed. The relation between the total projected particle area excluding overlap can be determined from the measured projected area including overlap from a simple equation. An overall uncertainty is given, including effects of positioning foils in the detector, sampling from rough surfaces, and the natural variability due to the discrete nature of particles. The lower level of detection for dust on an object is less than 0.5% surface area covered by dust. The method has formed the basis for suggesting a sampling strategy and surface dust limits in relation to cleaning and the quality of the indoor environment.

Notes: Abstract Adjustment of ventilation rates in buildings is widely practised, both to provide good air quality on a proactive basis and to mitigate air quality problems associated with occupant complaints. However, both cross-sectional and experimental epidemiological studies have reported mixed results and have for the most part failed to establish definitive relationships between ventilation rates and symptom prevalence or dissatisfaction with air quality. The difficulties involved in establishing such relationships may be due to a variety of confounding factors which include limitations in study design and interaction effects; difficulties in controlling ventilation rates in experimental studies; inadequate mixing of supply air in occupied spaces; high source strengths for some contaminants; dynamic interactions between sources and ventilation rates that result in increased contaminant emissions; contaminant dose-response sensory effects which are log-linear; potential contaminant generation within ventilation systems themselves; and multifactorial genesis of sick building symptoms.There is limited evidence to suggest that ventilation rate increases up to 10 L/s person may be effective in reducing symptom prevalence and occupant dissatisfaction with air quality and that higher ventilation rates are not effective. Because of complex relationships between ventilation rates, contaminant levels, and building-related health complaints/dissatisfaction with air quality, the use of ventilation as a mitigation measure for air quality problems should be tempered with an understanding of factors which may limit its effectiveness.

Notes: Abstract Humidifiers, used in approximately 25% of Canadian homes, may potentially aggravate asthma by increasing the airborne concentrations of fine particles and microbials. A randomized controlled study was carried out to investigate the acute effects of humidifier use on asthma control. Daily peak flows, asthma symptoms and need for medication were assessed during 2 weeks (period 1) when 110 subjects were using humidifiers and during the following 3 weeks (period 2) when half of the subjects were randomized to stopping the humidifier and the other half to continuing its use. In the intervention group, mean morning peak flows were 357 L/min (SEM 17) during humidifier use (period 1) and 352 L/min (SEM 16) when humidifiers were not used, a difference of - 4.4 L/min (95%CI - 11.2 to 2.3) (period 2). Respective values in the control group were 403 L/min (SEM 16) during period 1 and 405 L/min (SEM 16) during period 2. No significant differences were found when analyses were restricted to portable humidifiers, allergies to mites and/or molds, and infrequently cleaned humidifiers. Humidifiers cause no short-term adverse health effects in the majority of those with asthma. Future studies should address the broader question concerning the chronic effects of increased home humidity on microflora and health.

Notes: Abstract A study was undertaken to investigate the use of mass balance modeling techniques to predict air pollution concentrations in residential settings where the source is evaporative emissions of alternative fuels emitted in the attached garage. Field study measurements of the spatial and temporal distribution of evaporative emissions in an attached garage were used to conduct this investigation. In this field study, known quantities of methanol were allowed to evaporate in the garage. Methanol concentrations were then measured and simulated in the garage. Because chemical and physical properties of this contaminant are clearly understood, it was possible to simulate the concentrations inside the remainder of the house.A multi-zonal mass balance model (CONTAM88) was used to predict the across-residence spatial and temporal distribution of concentrations of evaporative emissions from a methanol source inside the attached garage. The model's input data include physical characteristics of the house; parameters characterizing the leakiness of the house; heat, ventilation and air-conditioning system characteristics; fixed airflow data from vent registers; on-site meteorological measurements; and information on the contaminant source.Before using the model to simulate methanol dispersions, the model's performance was tested. Sulfur hexafluoride (SF6) measurements were taken throughout the residence and garage. The model was used to predict interzonal airflow rates and SF6 concentration distributions within the garage and the house, as well as to investigate the well-mixed zone assumption for the garage. Modeling results show that predicted garage SF6 concentrations agreed reasonably well with the measured concentrations under mixed conditions, but the model underpredicted the SF6 concentrations within rooms of the house where mixing was probably incomplete. Methanol simulation results showed that the model underpredicted by approximately 15 percent the garage methanol concentration after methanol emissions stopped.This study found that evaporative emissions in an attached garage have a tendency to infiltrate the house, with rooms adjacent to the garage showing the highest levels of methanol concentrations. Thus automotive evaporative emissions may represent a source of indoor pollution and human exposure in a residential attached garage and also in other critical locations of the residence.

Notes: Abstract The objective of this study was to assess the magnitude and balance of mechanical ventilation in the rooms of Helsinki metropolitan office buildings with different types of ventilation systems. A random sample of 50 office buildings was selected from the Building Registry. Of these buildings, the 33 that have a mechanical ventilation system were included in this study. Most office buildings in the Helsinki metropolitan area have a ducted supply and exhaust system and hot water radiator heating. Air recirculation is used in about half of the buildings which have a mechanical supply and exhaust system. The average exhaust airflow was 1.2 L/s, m2 (SD 0.73) or 17.2 L/s per person (SD 11.6). The variation of the airflows was found to be very high among the buildings, and among the rooms within the buildings. Therefore, even though the ventilation rates on average comply with the Finnish building code, it was found that many people were working in offices with airflows which were either too low or unnecessarily high.

Notes: Abstract Analysis of the impact of sources on indoor pollutant concentrations and occupant exposure to indoor pollutants requires knowledge of the emission rates from the sources. Emission rates are often determined by chamber testing and the data from the chamber test are fitted to an empirical model. While the empirical models are useful, they do not provide information necessary to scale the chamber data to buildings nor do they provide information necessary to understand the processes controlling emissions. A mass transfer model for gas-phase-limited mass transfer is developed and described in this paper. Examples of sources with gas-phase-limited emissions are moth cakes, floor wax, stain, and varnish. The mass transfer model expresses the emission rate in terms of a mass transfer coefficient and a driving force. The mass transfer coefficient can be predicted from correlations of the Nusselt number and the Reynolds number. The experiments and data analysis used to develop the correlation are described in the paper. Experiments to verify the assumptions used to describe the driving force are also described. Suggestions for using data from existing empirical emission models to determine parameters for the mass transfer model are provided. The mass transfer model provides a significantly better fit to data from an indoor air quality test house than does the empirical first order decay model.

Notes: There is a growing concern about indoor air quality (IAQ) in schools. We have studied relations between subjective indoor air quality (SIAQ) and measured IAQ among school personnel (N = 97) in six mid-Swedish primary schools. Information on SIAQ and the psychosocial work environment was measured by a self-administered questionnaire, using analogue rating scales. Indoor exposures were quantified by hygienic measurements. Perception of high room temperature was related to a poor climate of cooperation, fleecy wall materials, and the concentration of volatile organic compounds (VOC), including xylene, limonene, and butanols. Perception of air dry-ness was related to atopy, work stress, poor climate of cooperation, high room temperature, low air humidity, and high VOC concentration, including, limonene, and n-alkanes. Perception of dusty air was related to work stress, the role of schoolteacher, and exposure to 2-ethyl-1-hexanol. No relations were found between SIAQ and CO2, building age, or respirable dust. To achieve a good SIAQ, room temperature should be kept at a maximum of 22°C, and exposure to VOCs and fleecy materials should be minimized. Finally, a sound psychosocial work climate is essential for the perception of a good physical indoor climate.

Notes: Tracer gas studies were conducted around four model houses in a wind tunnel, and around one house in the field, to quantify re-entrainment and dispersion of exhaust gases released from residential indoor radon reduction systems. Re-entrainment tests in the field suggest that active soil depressurization systems exhausting at grade level can contribute indoor radon concentrations 3 to 9 times greater than systems exhausting at the eave. With a high exhaust concentration of 37,000 Bq/m3, the indoor contribution from eave exhaust re-entrainment may be only 20% to 70% of the national average ambient level in the U.S. (about 14 Bq/m3), while grade-level exhaust may contribute 1.8 times the ambient average. The grade-level contribution would drop to only 0.18 times ambient if the exhaust were 3,700 Bq/m3. Wind tunnel tests of exhaust dispersion outdoors suggest that grade-level exhaust can contribute mean concentrations beside houses averaging 7 times greater than exhaust at the eave, and 25 to 50 times greater than exhaust midway up the roof slope. With 37,000 Bq/m3 in the exhaust, the highest mean concentrations beside the house could be less than or equal to the ambient background level with eave and mid-roof exhausts, and 2 to 7 times greater than ambient with grade exhausts.

Notes: The objective of this study was to compare measured indoor air concentrations of toluene, from an adhesive used in installing floor tiles, with concentrations estimated from a multi-chamber indoor air quality model. Measurements of toluene emissions from floor adhesive with and without tiles covering the adhesive were made using a small chamber. Emission data from the chamber measurements were used as input to the indoor air quality model. The modeling results were compared with concentrations of toluene measured in a research house when adhesive was applied in a bedroom of the house. Three zones of the house were defined for modeling purposes-the bedroom in which the adhesive was applied, the remainder of the upstairs area, and the downstairs area. Zone-specific volumes and infiltration/exfiltration and interzonal airflows measured during and after adhesive application were also used as model inputs. Relatively good correspondence between measured and model concentrations was obtained, particularly in the bedroom where the adhesive was applied. Modeled concentrations were fairly sensitive to the input matrix of airflow rates.

Notes: 100 drivers aged 23-65, 53 male and 47 female, were recruited to drive an apparently unmodified passenger car for one hour in city traffic. They were randomly assigned either to a control condition, or to ionised air containing 20 000-30 000 negative ions/ml, but were unaware of the presence of an ioniser in the vehicle. A computer initiated unprepared signals to which drivers should normally be alert. Drivers responded by pressing a foot-switch and reporting verbally. Signals were selected at random from 21 possible signals, and were presented for up to 3 minutes, with a random delay of 30-180 seconds after each response or failure to respond. Subjects reported subjective symptom intensity by marking a set of 11 visual-analogue scales. Eye symptoms were alleviated by ionisation for subjects aged 〈 40 years (P〈0.05), but older female subjects experienced more eye discomfort, headache and fatigue in the ionisation condition (P 〈 0.05). Detection of 10 of the 21 signals was better (P 〈 0.05, 2-tail) in the ionisation condition. The effect was more often significant in the second half-hour, for subjects 〈 40 years, and for women. A significant negative effect (P 〈 0.05) was observed for the signal indicating speed below true speed.

Notes: The propensity of various types of home humidifiers to support and disseminate microbial contaminants into indoor air was tested. Reservoir water and air discharged from humidifiers seeded in the laboratory or naturally contaminated in the home were analyzed by standard microbiological methods. Clinically insignificant as well as overt or potentially pathogenic microorganisms were found to colonize the reservoirs of all types of humidifiers, but only cool mist and ultrasonic units readily aerosolized bacteria and endotoxin. Only cool mist units emitted hydrophobic fungal spores. Cool mist units discharged the greatest number of water particles in the inhalabk size range (4–16 μm) while ultrasonic units were more likely to emit respirable-sized water particles (〈 0.2–4 μm). Overt pathogens isolated from humidifiers in homes included Legionella and a pathogenic Acanthamoeba. Aerosolizing humidifiers should thus be avoided if frequent, thorough cleaning of the units is not practical.

Notes: The role of ventilation in the housing stock is to provide fresh air and to dilute internally generated pollutants in order to assure adequate indoor air quality. Blower doors are used to measure the air tightness and air leakage of building envelopes. As existing dwellings in the United States are ventilated primarily through leaks in the building shell (i.e., infiltration) rather than by whole-house mechanical ventilation systems, accurate understanding of the uses of blower-door data is critical Blower doors can be used to answer the following questions:〈list xml:id="l1" style="custom"〉•What is the Construction Quality of the Building Envelope?•Where are the Air Leakage Pathways?•How Tight is the Building?•How Much Ventilation Does the Air Leakage Supply?•How Much Energy Does the Air Leakage Lose?•Is this Building Too Tight?•Is this. Building Too Loose?•When Should Mechanical Ventilation be Considered?Various ASHRAE Standards (e.g., 62, 119, and 136) are used to determine acceptable ventilation levels and energy requirements.

Notes: The mixing rate of pollutants emitted from indoor sources influences the effectiveness of pollutant removal by building ventilation and the potential variability of exposure for a given release scenario. Quantitative information is scant on the mixing rate and the factors that govern it. We present mixing data for an instantaneously released tracer gas, carbon monoxide, in a sealed, unoccupied room under a range of forced airflow conditions, in which the flow is induced by blowers. The resulting mixing times, from 2 to 42 minutes, are related to the mechanical power of the air jets produced by the blowers. Mixing times are found to correlate well with the inverse of the cube root of power, in accordance with theoretical predictions and experimental observations for mixing in chemical reactors. The exposure index, defined as the time-averaged concentration at a point relative to the time-averaged concentration for the room as a whole, is presented for three experimental conditions, yielding quantitative information on the appropriateness of the well-mixed hypothesis under various flow conditions. In general, the exposure period following instantaneous release of a point-source pollutant must be much greater than the mixing time for the assumption of uniform mixing to hold. The correlation between mixing time and power input is used to predict the mixing time from the mixing action of a supply air jet for a typical ventilation scenario. The predicted mixing time, τmix∼7 min, is substantially lower than the time scale for removal by ventilation, τvent∼48 min. Under these conditions, complete mixing of an instantaneous release, point-source pollutant would be approximately attained within the interior space well before the pollutant would be thoroughly removed by ventilation.

Notes: The mean skin temperatures as well as the temperatures of the hands, feet and forehead of small children were measured in nurseries at air temperatures of 20°C and 22°C. Differences were studied between babies remaining still, babies crawling on tiling, wooden floors or rubber foam groundsheets, and older walking children. The results suggest that an air temperature of 22°C leads to skin temperatures comparable to those observed for resting adults in comfort, while 20°C seems to induce a slight but overall cooling of the body and considerable cooling of the extremities for the babies remaining still. The material of floor coverings should be considered carefully and preference given to low conductivity materials. Assuming that the optimum skin temperatures are the same for children and for adults, it appears that the PMV-PPD approach can be used to predict this particular optimum comfort condition, provided an increase of 20 wm−2 is taken into account for the metabolic rate of the small children.

Notes: Ventilation displacement systems have, during the last ten years, become more and more popular. In these systems cool air is supplied to the room, and the air is heated by heat sources. The rising air above these heat sources is of paramount importance to the behaviour of the ventilation displacement systems. In the present work the turbulent flow in plumes is studied numerically, using finite volume methods. The standard r-ɛ model was found to underpredict the spreading of the plumes, and it was thus modified in two ways so as to predict spreading rates in agreement with experiments. We present a comprehensive comparison between predictions and experiments including spreading rates, velocity and temperature profiles, and turbulent shear stresses. The volume flow rate versus the vertical distance from the plume is also presented. Good agreement between predictions and experiments is obtained.

Notes: The results of measurements of indoor air formaldehyde concentrations in occupational and private residences are presented for the period 1986 to 1993, based on requests of persons who complained about irritations. In many cases, climatic parameters such as the air exchange rate, temperature and relative humidity were also monitored. Calculated mean values for temperature and humidity were 22°C and 45% respectively. The average air exchange rate was 0.36 h−1, which is well below a recommended guideline value of 0.8 h˜' and it was evident that the ventilation is clearly insufficient in many rooms. The average formaldehyde concentration was 119 μg/m −3 (252 data), which is only slightly below the German guideline value of 125 μg/m −3. In 31% of the cases this guideline was exceeded. As expected, a clear relation between formaldehyde concentrations and the air exchange rate was found. The highest levels result at AE≤0.8 h−1, but only a single value exceeds 125 μg/m −3 at AE≥0.8 h−1. The association of law ventilation rates with high formaldehyde levels is also evident from a comparison with theoretical data after normalization to AE=0.8 h−1, using the Hoetjer-equation. It was also observed that the calculated annual mean concentrations decreased from 1986 to 1993.