Presence Of ACC Research Articles

Genome-wide association analysis unveils candidate genes and loci associated with aplasia cutis congenita in pigs

BackgroundAplasia cutis congenita (ACC) is a rare genetic disorder characterized by the localized or widespread absence of skin in humans and animals. Individuals with ACC may experience developmental abnormalities in the skeletal and muscular systems, as well as potential complications. Localized and isolated cases of ACC can be treated through surgical and medical interventions, while extensive cases of ACC may result in neonatal mortality. The presence of ACC in pigs has implications for animal welfare. It contributes to an elevated mortality rate among piglets at birth, leading to substantial economic losses in the pig farming industry. In order to elucidate candidate genetic loci associated with ACC, we performed a Genome-Wide Association Study analysis on 216 Duroc pigs. The primary goal of this study was to identify candidate genes that associated with ACC.ResultsThis study identified nine significant SNPs associated with ACC. Further analysis revealed the presence of two quantitative trait loci, 483 kb (5:18,196,971–18,680,098) on SSC 5 and 159 kb (13:20,713,440–207294431 bp) on SSC13. By annotating candidate genes within a 1 Mb region surrounding the significant SNPs, a total of 11 candidate genes were identified on SSC5 and SSC13, including KRT71, KRT1, KRT4, ITGB7, CSAD, RARG, SP7, PFKL, TRPM2, SUMO3, and TSPEAR.ConclusionsThe results of this study further elucidate the potential mechanisms underlying and genetic architecture of ACC and identify reliable candidate genes. These results lay the foundation for treating and understanding ACC in humans.

Sequences of Acretocins, Peptaibiotics Containing the Rare 1-Aminocyclopropanecarboxylic Acid, from Acremonium crotocinigenum CBS 217.70.

Sequences of Acretocins, Peptaibiotics Containing the Rare 1-Aminocyclopropanecarboxylic Acid, from Acremonium crotocinigenum CBS 217.70.

One Pot Synthesis of Biscoumarins and Pyranocoumarins by Coconut Juice as a Natural Catalyst

Background: The conception of ‘Green chemistry’ is the much inventive chemistry which is potent and more environmentally benign. It is notable that many organic reactions take place in conventional organic solvents, known as volatile organic compounds. Being concerned about the environmental impact, we report a promoting medium, coconut juice (ACC) for one-pot synthesis of biscoumarins and pyranocoumarins which is safe, harmless, green and environmentally benign. Methods and Results: Substituted biscoumarins have been achieved by the reaction of biscoumarin and substituted aromatic aldehydes in presence of ACC which acts as a green catalyst cum solvent. Each reaction showed good to excellent yield in presence of both electron donating as well as electron withdrawing group on aromatic aldehyde without formation of any by-products. Similarly, pyranocoumarins have been achieved by the reaction of biscoumarin, substituted aromatic aldehydes, active methylene nitrile in presence of ACC. All the reactions proceed smoothly and gave higher yields in case of malononitrile in comparison of ethyl-2-cyanoacetate. Conclusion: A simple, eco-friendly and novel procedure was demonstrated for the synthesis of biscoumarins and pyranocoumarins using natural feedstock coconut juice. The major importance of using ACC juice is higher yields, no work-up and no column chromatography.

Abscisic acid inhibits germination and indirectly delays ethylene biosynthesis of Beta vulgaris

Ethylene and abscisic acid (ABA) are known to interact during the germination of several species. However, ethylene is not involved during the germination of Beta vulgaris, questioning a possible interaction with ABA. Our results have shown that ABA delays the germination of B. vulgaris in a concentration-dependent manner. By analysing the ethylene biosynthesis pathway, the ethylene release rate was shown to be delayed when ABA is supplemented, most probably due to the slower germination rate. The inverse interaction in which 1-aminocyclopropane-1-carboxylic acid (ACC) affects ABA levels does not seem to occur in B. vulgaris as no changes in ABA content were observed during germination in the presence of ACC at different concentrations. Levels of certain plant growth regulators (ABA, ACC and auxin) were also shown to be much higher in the fruit pericarp compared with the true seed. Presumably the pericarp plays an important role during the germination process of B. vulgaris because it is a physiochemical boundary with drastic differences in hormone levels. Our results clearly show demonstrate that ethylene is not involved during the actual germination of B. vulgaris, and that there is no effect of ethylene on ABA during germination of B. vulgaris.

Study of aminoglycoside resistance genes in enterococcus and salmonella strains isolated from ilam and milad hospitals, iran.

Background:Aminoglycosides are a group of antibiotics that have been widely used in the treatment of life-threatening infections of Gram-negative bacteria.Objectives:This study aimed to evaluate the frequency of aminoglycoside resistance genes in Enterococcus and Salmonella strains isolated from clinical samples by PCR.Materials and Methods:In this study, 140 and 79 isolates of Enterococcus and Salmonella were collected, respectively. After phenotypic biochemical confirmation, 117 and 77 isolates were identified as Enterococcus and Salmonella, respectively. After the biochemical identification of the isolates, antibiotic susceptibility for screening of resistance was done using the Kirby-Bauer method for gentamicin, amikacin, kanamycin, tobramycin and netilmycin. DNA was extracted from resistant strains and the presence of acc (3)-Ia, aac (3′)-Ib, acc (6)-IIa ,16SrRNA methylase genes (armA and rat) was detected by PCR amplification using special primers and positive controls.Results:Enterococcus isolates have the highest prevalence of resistance to both kanamycin and amikacin (68.4%), and Salmonella isolates have the highest prevalence of resistance against kanamycin (6.9%). Ninety-three and 26 isolates of Enterococcus and Salmonella at least were resistant against one of the aminoglycosides, respectively. Moreover, 72.04%, 66.7%, and 36.6% of the resistant strains of Enterococcus had the aac (3′)-Ia, aac (3′)-IIa, and acc (6′)-Ib genes, respectively. None of the Salmonella isolates have the studied aminoglycoside genes.Conclusions:Our results indicate that acetylation genes have an important role in aminoglycoside resistance of the Enterococcus isolates from clinical samples. Moreover, Salmonella strains indicate very low level of aminoglycoside resistance, and aminoglycoside resistance genes were not found in Salmonella isolates. These results indicate that other resistance mechanisms, including efflux pumps have an important role in aminoglycoside resistance of Salmonella.

Study of Aminoglycoside Resistance Genes in Enterococcus and Salmonella Strains Isolated From Ilam and Milad Hospitals, Iran

Background: Aminoglycosides are a group of antibiotics that have been widely used in the treatment of life-threatening infections of Gram-negative bacteria. Objectives: This study aimed to evaluate the frequency of aminoglycoside resistance genes in Enterococcus and Salmonella strains isolated from clinical samples by PCR. Materials and Methods: In this study, 140 and 79 isolates of Enterococcus and Salmonella were collected, respectively. After phenotypic biochemical confirmation, 117 and 77 isolates were identified as Enterococcus and Salmonella, respectively. After the biochemical identification of the isolates, antibiotic susceptibility for screening of resistance was done using the Kirby-Bauer method for gentamicin, amikacin, kanamycin, tobramycin and netilmycin. DNA was extracted from resistant strains and the presence of acc (3)-Ia, aac (3′)-Ib, acc (6)-IIa ,16SrRNA methylase genes (armA and rat) was detected by PCR amplification using special primers and positive controls. Results: Enterococcus isolates have the highest prevalence of resistance to both kanamycin and amikacin (68.4%), and Salmonella isolates have the highest prevalence of resistance against kanamycin (6.9%). Ninety-three and 26 isolates of Enterococcus and Salmonella at least were resistant against one of the aminoglycosides, respectively. Moreover, 72.04%, 66.7%, and 36.6% of the resistant strains of Enterococcus had the aac (3′)-Ia, aac (3′)-IIa, and acc (6′)-Ib genes, respectively. None of the Salmonella isolates have the studied aminoglycoside genes. Conclusions: Our results indicate that acetylation genes have an important role in aminoglycoside resistance of the Enterococcus isolates from clinical samples. Moreover, Salmonella strains indicate very low level of aminoglycoside resistance, and aminoglycoside resistance genes were not found in Salmonella isolates. These results indicate that other resistance mechanisms, including efflux pumps have an important role in aminoglycoside resistance of Salmonella.

CsPDR8 and CsPDR12, two of the 16 pleiotropic drug resistance genes in cucumber, are transcriptionally regulated by phytohormones and auxin herbicide in roots

There are 15 and 23 members of the pleiotropic drug resistance (PDR) proteins, a subfamily of ATP-binding cassette (ABC) transporters, in Arabidopsis thaliana and Oryza sativa, respectively. Until recently, only a few members of Arabidopsis thaliana PDRs (AtPDRs) had been characterized in detail but growing reports indicate that proteins of this family may participate in growth regulator-mediated signaling and phytohormone transport. The profile of Oryza sativa PDRs (OsPDRs) expression in response to different stimuli also suggests that some rice PDRs are associated with a phytohormone-mediated response to environmental changes. Due to the lack of full genome resources, only individual members of PDRs in other plants (Nicotiana, Oryza, Glycine or Spirodela) have been studied. We have previously cloned two full cDNA sequences encoding for cucumber homologs of Arabidopsis PDR8 and PDR12. Here, we present the genomic organization of 16 cucumber PDRs and the phylogeny of the predicted Cucumis sativus PDR (CsPDR) proteins. Further analysis of CsPDR8 and CsPDR12 reveal that these cucumber genes are constitutively expressed mainly in roots of young seedlings and flowering plants (CsPDR8 and CsPDR12), and in flowers (CsPDR12). In roots, the transcript of CsPDR8 decreased in response to ABA and markedly raised in the presence of ACC, salicylic acid or jasmonic acid. In comparison, the expression of CsPDR12 was not affected by ACC and significantly increased upon the addition of jasmonic acid, salicylic acid, 2,4-D, kinetin or ABA to the growth media. These data suggest that CsPDR8 and CsPDR12 may be involved in a phytohormone-mediated response of plants to different stimuli by sharing different signaling pathways.

Liver test patterns in patients with acute calculous cholecystitis and/or choledocholithiasis

Liver tests are utilized to determine the presence of biliary obstruction. To examine our hypothesis that liver tests aid in elucidating whether patients have simple calculous cholecystitis (ACC) or choledocholithiasis (CDL). We performed a retrospective study of patients admitted to two University of Texas Southwestern teaching hospitals with a clinical picture consistent with 'acute gallstone disease', i.e. cholecystitis +/- choledocolithiasis. The presence of ACC and CDL was based on defined clinical criteria. The cohort consisted of 154 patients meeting specific entry criteria, primarily with right upper quadrant pain; 62 ACC, 79 both ACC and CDL and 13 CDL alone. Approximately 30% of patients with ACC had abnormal alkaline phosphatase (ALP) and/or bilirubin level and approximately 50% had abnormal aminotransferase levels. Among patients with ACC/CDL, 77% had abnormal ALP, 60% had abnormal bilirubin and 90% had abnormal aminotransferase levels. By multivariate analysis, increasing common bile duct size and an abnormal ALP and alanine aminotransferase (ALT) were excellent predictors of having ACC with CDL. Liver test patterns can aid in elucidating CDL, including in ACC patients. Fundamentally, patients with CDL were more likely to have more abnormal liver tests, whether they had CDL only, or CDL and ACC. A dilated CBD, and abnormal ALP and ALT had modest sensitivity and high specificity for identification of patients with ACC and CDL.

Arabidopsis 피토크롬 돌연변이체(phyAB)의 뿌리 굴중성 반응

Phytochrome double mutant (phyAB) showed the delayed root gravitropic response compared to the wild type (WT) in Arabidopsis. After 8 hr of gravistimulation, the gravitropic response of mutant showed 48% of the WT. The delayed response started at 1.5 hr after gravistimulation. And we measured the ethylene production in the root segments of WT and mutant for 12 hr. Ethylene production of mutant decreased about 40% of the WT at 12 hr. This result suggested that the phytochrome might be linked with ethylene production in some way. Generally, ethylene inhibits the growth of plant organs including roots. We measured the root growth rate in the presence of ACC (1-aminocyclopropane-1-carboxylic acid), a precursor of ethylene. And WT showed the inhibition of root growth with ACC, but mutant did not show the inhibition as WT did. To confirm the relationship between the ethylene and gravitropic response, we measured the gravitropic response with ACC. In the presence of 10-6 M ACC, WT showed the 37.4% inhibition compared to the control (no ACC), whereas mutant showed the only 6.6% inhibition of control (no ACC). This research suggested the relationship between phytochrome and gravitropic response through an ethylene production.

Transcriptional regulation of ACC deaminase gene expression inPseudomonas putidaUW4

One of the major mechanisms that plant growth-promoting bacteria use to facilitate plant growth is through the lowering of plant ethylene levels by the bacterial enzyme 1-aminocyclopropane-1-carboxylate (ACC) deaminase. Many of the bacterial ACC deaminase genes (acdS) that have been examined to date are under the transcriptional control of a leucine-responsive regulatory protein, Lrp, encoded by acdR and referred to here as AcdR. The work presented here is focused on how AcdR and the newly discovered AcdB protein from Pseudomonas putida UW4 are involved in the regulation of acdS expression. First, the results of gel retardation experiments showed that AcdR binds to the acdS regulatory region, and this binding activity in vitro is not affected by the addition of 2 mmol x L-1 ACC but can be eliminated by addition of 20 microg x mL-1 leucine. Second, a potential regulatory protein, AcdB, involved in the regulation of acdS expression, was identified through both yeast 2-hybrid screen and coimmunoprecipitation based on its ability to bind to AcdR; subsequently, its binding to the acdS regulatory region in the presence of ACC was shown by gel retardation experiments. The data are interpreted in terms of a model in which AcdR and AcdB co-regulate the expression of the acdS gene.

(205) Germination of Echinacea Species Is Enhanced by ACC

Echinacea are North American members of the Asteraceae, and all can show some degree of endogenous physiological seed dormancy that is alleviated by chilling stratification. In some species, ethephon has been shown to substitute for chilling stratification to relieve dormancy. The objective of this research was to investigate the effect of ACC on dormancy and germination in five Echinacea species. Germination for each species was 90%, 59%, 99%, 81%, and 21%, respectively. Germination on 5 mM ACC improved germination in E. tennesseensis, E. paradoxa, and E. simulata to 82%, 99%, and 82%, respectively, but there was no change for E. purpurea and E. angustifolia. Germination rate was dramatically accelerated in all species in the presence of ACC. On average, there were 57% more seeds germinated on ACC after 3 days compared to untreated seeds. Exposing E. purpurea and E. tennesseensis seeds to 1 or 2 days of 5 mM ACC before drying and subsequently re-hydrating the seeds did not have the same effect as continual exposure to ACC. Similarly, there was no clear enhancement of adding ACC during stratification over the improvement gained by chilling stratification alone. Seeds produced more ethylene upon germination following both stratification and ACC treatment. However, significantly more ethylene is produced during germination in ACC-treated seeds. It was clear that ACC-treated seeds showed improvement for enhanced germination speed and in some cases germination percentage. Unfortunately, this enhanced germination was not retained in seeds treated with ACC and dried prior to germination. Additional work is required to develop a commercially viable method of loading ACC into seeds for germination enhancement.

Inhibitory effect of methyl jasmonate on development of phytopathogen Alternaria alternata (Fr.) Keissl. and its reversal by ethephon and ACC

Methyl jasmonate (MeJA) was found to reduce spore germination, hyphal and mycelial growth in Alternaria alternata (Fr.) Keissl. The addition of ethephon or 1-aminocyclopropane-1-carboxylic acid (ACC), ethylene precursor, together with MeJA to the culture medium resulted in a promotion of all developmental stages of the fungus; these compounds partially or completely reversed the inhibition due to MeJA depending on the concentrations applied. MeJA alone had no effect on ethylene production by mycelium, but after 6 days of incubation in the presence of ACC, emanation of this gas increased significantly. Ethylene is involved in reversing the inhibition of A. alternata due to MeJA.

Contribution of AGC to ACC and other mutations at codon 315 of the katG gene in isoniazid-resistant Mycobacterium tuberculosis isolates from the Middle East

The presence of ACC and other mutations at codon 315 in the katG gene was detected by PCR amplification followed by restriction fragment length polymorphism (PCR-RFLP) generated with restriction enzymes Msp I and MspA1 I in 37 isoniazid-resistant and 22-susceptible Mycobacterium tuberculosis isolates from Kuwait obtained in 2001. The mutation AGC to ACC was detected in 22 (60%) isolates while any mutation at codon 315 of the katG gene was present in 24 (65%) of 37 isoniazid-resistant isolates. The typing studies showed that majority of the isolates carrying mutations at codon 315 exhibited unique DNA banding patterns. The results were extended by additional analysis of 67, 28 and 17 isoniazid-resistant and 18, seven and six-susceptible M. tuberculosis isolates from Kuwait, Dubai and Beirut, respectively, that were analyzed previously for ACC mutation alone. These studies showed that one of 21, one of 10 and two of 11 isolates (all recovered from patients of Middle Eastern origin) with no AGC to ACC mutation from Kuwait, Dubai and Beirut, respectively, contained other mutations at codon 315 of the katG gene. None of the susceptible strains contained any mutation at codon 315. The PCR-RFLP with MspA1 I that detects all mutations at codon 315, compared with Msp I that detects only ACC mutation, identified more isoniazid-resistant strains with mutations at codon 315 in the katG gene. The data also showed that mutations other than AGC to ACC at codon 315 in the katG gene occur frequently in M. tuberculosis isolates recovered from Middle Eastern patients and should be incorporated in a rapid screen for the detection of mutations for isoniazid-resistance in the katG gene from this ethnic group.

Inclusion of Ethylene Precursor into Priming Solution Improves Germination and Emergence of Narrow-leafed Purple Coneflower Seeds

The effects of stratification and priming on germination and emergence performance of narrowleafed purple coneflower (Echinacea angustifolia) seeds were investigated. Seeds were pre-chilled for 3 weeks at 4 ± 0.5 °C (39.2 ± 0.9 °F) in light or primed for 3 days at 20 ± 0.5 °C (68.0 ± 0.9 °F) in darkness in Nas and Read medium (NRM) or in 2% potassium nitrate (KNO3) supplemented with 3 or 5 μm 1-aminocyclopropane carboxylic acid (ACC) or 500 mg·L-1 (ppm) or 1000 mg·L-1 gibberellic acid (GA3). Following stratification and priming, seeds were subjected to germination and emergence tests at 25 ± 0.5 °C (77.0 ± 0.9 °F). Priming the seeds in NRM or KNO3 containing 3 μm ACC gave the highest germination percentages with 78% and 80%, respectively. Stratification alone increased germination to 69% compared to nontreated seeds, which had the lowest germination percentage of 57%. Emergence was enhanced by priming seeds in the presence of 3 μm ACC (75%) compared to stratified seeds (62%), while nontreated seeds had the lowest emergence percentage of 26%. These results indicate that priming in the presence of ACC might be an alternative to lengthy stratification treatments to break the dormancy and improve the germination and emergence of narrow-leafed purple coneflower seeds.

Root and hypocotyl growth in transgenic tomatoes that express the bacterial enzyme ACC deaminase

The seeds of tomatoes transformed with a bacterial ACC deaminase gene under the transcriptional control of either the cauliflower mosiac virus 355 promoter, the ro/D (root specific) promoter or the prb-1b (pathogenesis related) promoter, dand the seeds of nontransformed (NT) tomato plants were germinated in the presence or absence of ACC in the dark, in the light, or in the presence of UV-B light for 12 days. Roots grew to a greater length under UV-B than in the light or dark, in the absence of ACC for all of the plant lines tested. In contrast, root growth was inhibited by ACC under all conditions tested. The 35S/ACC deaminase transgenic seedlings had the longest hypocotyl, the ro/D/ACC deaminase had intermediate sized hypocotyls and the NT and the prb-1b/ACC deaminase had the shortest hypocotyl in the presence of ACC in the dark. Hypocotyl growth was inhibited by both light and UV-B in both the absence and presence of ACC in NT and transformed plants. Taken together these results indicate that root growth is more sensitive to applied ACC (the precursor of ethylene) than is hypocotyl growth under all of the light regimes tested.

Antepartum computerized CTG and neonatal acid-base status at birth

Objective: To assess the correlation between individual computerized cardiotocography (cCTG) variables and acid-base status at birth before the first breathing in uncomplicated term pregnancy delivered by cesarean section. Study design: A retrospective cohort study. Subjects and methods: Seventy singleton normal pregnancies delivered by elective cesarean section. The last antepartum cCTG performed within 4 h from delivery by the System 8002 (Oxford Sonicaid, UK) was correlated to umbilical blood gas analysis (UBGA) values (AVL compact 2 analyser). Considering blood gas analysis values as dependent and individual cCTG parameters as independent variables the best regression subsets followed by a backward stepwise linear regression was used. Results: There was no significant correlation of cCTG parameters with any of the values of blood gas analysis. However, when neonatal conditions, as expressed by arterial pH>7.20, Becf>−4.0 mmol/l and Apgar score at 5 min >7, were taken as an end-point, they could be predicted by Acc15 and FM/hour (sensitivity: 35%, positive predictive value: 92%, cut-off>7 and 67%, 92%, >21, respectively). Conclusion: In uncomplicated pregnancies, the prospect of a vigorous newborn seems particularly associated with the presence of Acc>15 and FM/hour>21.

In vitro growth and ripening of strawberry fruit in the presence of ACC, STS or propylene

SummaryStrawberry (Fragaria ananassa Duch.) fruit exhibit limited capacity for continued development following harvest. This problem can be circumvented by maintaining harvested strawberry fruit in solutions containing sucrose and a bactericide. In this study, we investigated the respiratory and ethylene production kinetics and ethylene responsiveness in strawberry fruit harvested immature and ripened in vitro in the presence of propylene. The effects of 1‐amino‐cyclopropane‐1‐carboxylic acid (ACC) and silver thiosulfate (STS) alone and in combination were also examined. Respiration and ethylene patterns of fruit harvested green and developed in vitro declined with maturation and ripening, as did those of field‐grown fruit harvested at different stages of ripeness. Exposure of detached green strawberry fruit to 5000 μl litre‐1 propylene failed to stimulate respiration or ethylene production, but advanced pigmentation changes and fresh‐weight gain significantly. Excised fruit provided with 1 mol‐3 ACC exhibited increased ethylene production, enhanced fresh‐weight gain, and accelerated anthocyanin accumulation, but showed no change in respiration. The developmental response of harvested strawberry fruit to propylene or ACC was dependent on fruit maturity at harvest, with white fruit exhibiting greater insensitivity compared with green fruit. Silver thiosulfate (0.5 mol‐3) applied alone or in combination with ACC failed to delay ripening in excised strawberry fruit. These experiments demonstrate that ripening in detached strawberry fruit can be modified by ethylene only in green fruit that are provided with a carbohydrate source. Ethylene, when applied exogenously as ACC or propylene to green fruit, can slightly increase fruit growth and the rate of colour development.

Wound induced ethylene production from excised muskmelon fruit tissue

SummaryPrevious studies indicate that physical damage or wounding increases the preclimacteric production of ethylene in muskmelon fruit (Cucumis melo L., var. reticulatus Naud.) by inducing 1-aminocylopropane-l-carboxylic acid (ACC) synthase and ACC oxidase. In our experiments, ethylene production increased in the cylinders of preclimacteric fruit tissue from an undetectable level to 125 nl g−1 h−1 within 24 h after excision but declined to less than 50 nl g−1 at 48 h. Tissues subsampled from the inner portion of the original cylinder never exceeded 50 nl g−1 h−1 unless incubated for an additional 24 to 48 h after removal from the original cylinder. In contrast to ethylene production, ACC increased throughout all tissues in the original cylinder during the initial 48 h incubation. Wound induced increases in ACC were unaffected by inhibiting endogenous ethylene production with cobalt. The temporal and spatial patterns of wound induced ethylene production in preclimacteric muskmelon fruits are apparently determined by changes in the tissue’s ability to convert ACC to ethylene rather than the presence of ACC.

Manipulation of the polyamine content and senescence of apical buds of G2 peas

The effect of various treatments on the apical senescence and polyamine content of apical buds of G2 peas was analysed. Defruiting prevented senescence and increased bud size and polyamine content. Exogenous applications of GA20 enhanced bud size and spermidine concentration. Applied spermidine had a slight effect on spermidine level but did not delay senescence. ACC strongly induced adecrease in bud size and, at 10mM, apical senescence. This was accompanied by a steady decline in the level of all polyamines though their concentration remained constant until 10 mM ACC, where a drop was noted. Spermidine in the presence of ACC modulated the effect of ACC on the bud size white returning the internal polyamine content to control levels. AVG, an inhibitor of ACC synthesis produced pronounced increases in putrescine though no apparent effect on apical bud growth. Polyamine synthesis inhibitors were without effect on growth or internal polyamine content. The internal polyamine content appeared to correlate with apical bud size and vigor but did not show any consistent relationship to apical bud senescence.

Calcium stimulation of ethylene production induced by 1-aminocyclopropane-1-carboxylic acid and indole-3-acetic acid

Ca2+ stimulates 1-aminocyclopropane-1-carboxylic acid (ACC)- and indole-3-acetic acid (IAA)-dependent ethylene production in mung bean hypocotyls and senescing cucumber cotyledons. This stimulation is much greater in the presence of ACC than IAA. ACC content of hypocotyls also increases markedly with increasing Ca2+ concentration. Ca2+ stimulation with IAA occurs only after 4 h and may be dependent on new ACC being produced following auxin activation. Stimulation by Ca2+ with both ACC and IAA increases with temperature from 20° to 35°C, and also occurs with high internal levels of Ca2+.