Iris Bulbs Research Articles

New technique of laparoscopic colectomy with the LAP DISC and a 5-mm flexible scope

We devised a new method for the safe introduction of the first trocar and induction of pneumoperitoneum for laparoscopic excision of the large intestine. With this method, a small laparotomy is first conducted according to the size of the exposed affected intestinal tract or tumor size, prior to the application of a LAP DISC (LD) to the wound and introduction of a 12-mm trocar for the establishment of pneumoperitoneum. The method is advantageous in that organ injury and vessel injury are avoided when the small laparotomy is conducted first, and prompt transition to a conventional laparotomy is possible. The diaphragm of the iris bulb can be controlled in a non-stepwise manner. In addition, trocars, the stapler, and other instruments, can be inserted under the pneumoperitoneum. Furthermore, the use of a 5-mm flexible scope allows surgical maneuvers, except for application of LD, to be conducted via 5-mm trocars. In addition, the 5-mm scope can be inserted through any trocar, allowing multidirectional avoidance of dead space and intraperitoneal observation. When only 5-mm trocars are used, it is not necessary for the sites of trocar puncture to be closed by sutures, and this minimizes the risk of adhesions and port-site herniation. The method is also considered to be excellent from the point of view of esthetics. We employed this surgical approach in 50 patients with colorectal cancer at our hospital. None of the patients developed any traumatic complications associated with the insertion of trocars, and none of the patients, even those with a past history of abdominal operation, required conversion to conventional laparotomy. Based on these results, this method involving a small laparotomy prior to the application of an LD and introduction of a 12-mm trocar for establishing pneumoperitoneum, with the efficient use of a 5-mm flexible camera, is considered to be safe and useful for laparoscopic excision of the large intestine.

Non-systemic delivery of topical brimonidine to the brain: A neuro-ocular tissue distribution study

To date, the risks of central nervous system (CNS) side effects of topically administered ophthalmic therapeutic agents are thought to be the consequence of systemic absorption of these drugs. This paper envisions the possibility of drug delivery to the CNS following ocular application through non-systemic routes. After single instillation of 50 μl of 3H-radiolabeled Alphagan® solution (0.2%) in the cul de sac of the right eye, three male albino rabbits (2–2.5 kg) were sacrificed at each time point (5, 15, 30 and 60 min). Both sides (eyes) specimens of aqueous humor, cornea, iris, lens, vitreous, conjunctiva, sclera, ciliary body, choroid, retina, optic nerve, optic tract and olfactory bulb were weighed, and blood samples were measured, before combustion in tissue oxidizer and radioactive liquid scintillation counting. Significant 3H-brimonidine levels were found in right and left optic nerves and tracts with extremely low corresponding drug levels in blood. Uveal tract (ciliary body, iris and choroid tissues) brimonidine levels were relatively high in the treated eye, and the highest among contralateral eye tissues. Our data provide the first case of good CNS availability after ocular application of conventional ophthalmic therapeutic agent, through non-systemic routes. Similar neuro-ocular pharmacokinetic studies should be adopted as a routine ocular therapeutics evaluation study.

EFFICACY OF FUNGICIDES IN CONTROLLING LEAF SPOT ON BULBOUS IRIS

Annually, about 130 ha of field-grown bulbous iris (Iris x hollandica) are produced in western Washington. The production of iris bulbs and cut flowers has an estimated value of $3.4 to 5.6 million. Leaf spot or “fire”, caused by Mycosphaerella macrospora, is the most important foliar disease on this crop. Two trials were conducted to compare the efficacy of several standard and newer “reduced risk” fungicides for their ability to control leaf spot on two-year-old plantings of ‘Saturnus’ and ‘Apollo’ iris. Applications of Compass 50W (trifloxystrobin), Daconil Ultrex 82.5WP (chlorothalonil), Decree 50WDG (fenhexamid), Heritage 50WG (azoxystrobin), Insignia 20WP (pyraclostrobin), Medallion 50WP (fludioxonil), Phyton-27 (copper sulfate), Switch 62.5WG (cyprodinil + fludioxonil), and 26GT 23.3 (iprodione) were applied to plants at approximately 14 day intervals from 12 February through 21 May, 2003. The plot design was a randomized complete block with three blocks per cultivar. Treatments were applied to 1.5 m of row in each block. Disease pressure was high during late May and early June. On ‘Apollo’ iris, applications of Insignia, Heritage and 26GT provided excellent disease control and reduced the percentage of foliage that was killed. Insignia and Heritage also provided excellent disease control on ‘Saturnus’ iris. Applications of Medallion, Daconil Ultrex, and 26GT also reduced the level of disease compared to the unsprayed check. The results of these trials indicate that Insignia and Heritage have the potential to provide control of iris leaf spot that is equal to or better than that achieved by the standard materials used by growers.

Type-1 ribosome-inactivating protein from iris bulbs: a useful agronomic tool to engineer virus resistance?

To study the in planta antiviral activity of a type-1 ribosome-inactivating protein from iris bulbs, called IRIP, Nicotiana tabacum cv. Samsun NN was transformed with the IRIP sequence expressed under the control of the 35S cauliflower mosaic virus promoter. Molecular analysis of the transgenic plants and characterization of the purified protein revealed that the recombinant IRIP from tobacco leaves has the same molecular structure and RNA N-glycosidase activity as the native protein from iris bulbs. The tobacco transformants show no apparent phenotypic side effects indicating that ectopically expressed IRIP is not cytotoxic for tobacco cells. No induction of PR-1 could be demonstrated in the transgenic plants expressing IRIP. The in planta antiviral activity of rIRIP was assessed using a bioassay with tobacco mosaic virus. All transformed lines showed a statistically significant lower number of lesions compared to the control plants. The fortunate combination of in planta antiviral activity and lack of cytotoxicity of the ectopically expressed IRIP in transgenic tobacco renders the iris RIP an interesting and useful model for the study and exploitation of the antiviral activity of type-1 RIPs.

Iris bulbs express type 1 and type 2 ribosome-inactivating proteins with unusual properties.

Two closely related lectins from bulbs of the Dutch iris (Iris hollandica var. Professor Blaauw) have been isolated and cloned. Both lectins, called Iris agglutinin b and Iris agglutinin r, possess N-glycosidase activity and share a high sequence similarity with previously described type 2 ribosome-inactivating proteins (RIP). However, these lectins show only 57% to 59% sequence identity to a previously characterized type 1 RIP from iris, called IRIP. The identification of the iris lectins as type 2 RIP provides unequivocal evidence for the simultaneous occurrence of type 1 and type 2 RIP in iris bulbs and allowed a detailed comparison of type 1 and type 2 RIP from a single plant, which provides further insight into the molecular evolution of RIP. Binding studies and docking experiments revealed that the lectins exhibit binding activity not only toward Gal/N-acetylgalactosamine, but also toward mannose, demonstrating for the first time that RIP-binding sites can accommodate mannose.

Possible mechanisms influencing the dynamics of rhizoctonia disease of tulips

looseness-1In two observation fields, where six sites were artificially infested with Rhizoctonia solani AG 2-t, bare patches developed. These patches did not re-occur at the site of infestation in three successive years. In fields with and without artificial infestation, natural infection of tulip bulbs by Rhizoctonia spp. occurred. The spatial distribution of infected tulip bulbs was visualised in maps after kriging. The influence of sampling intensity was evaluated by stepwise reduction obtained in the observed data set of the first year. Omnidirectional semivariogram characteristics did not change when sampling intensity was reduced down to 10%. The average maximum prediction error was minimised at sampling intensities varying from 7% to 25%. Naturally occurring bare patches slowly vanished during successive cropping of flower bulbs and did not re-appear in the fourth growing season. A high frequency of isolation of R. solani AG 2-t in one field (Lisse-2) in the fourth consecutive crop did not result in bare patches in that year. It is hypothesised that a reduction in aggressiveness may account for this observation. In contrast, bulb rot due to Rhizoctonia spp. increased during the observation period. R. solani AG 5 isolates were seldom isolated before the bulbs flowered, but were the dominant isolate from bulbs at harvest. In a growth chamber experiment, it was demonstrated that AG 5 did not account for replacement of AG 2-t. However, it was demonstrated that competition may partially explain replacement of AG 2-t isolates during the growing season. At 18 °C, but not at 9 °C, an AG 4 isolate prevented AG 2-t colonising and infecting iris bulbs when both isolates were introduced together to soil. Rhizoctonia populations develop in relation to soil temperature and plant development. It is hypothesised that a ‘temporal niche differentiation’ may be one of the mechanisms affecting the dynamics of rhizoctonia bare patch of tulips.

Disease development of Pythium root rot in bulbous Iris and Crocus

Summary Iris bulbs and Crocus corms were planted at two planting dates in sandy soil infested with Pythium spp. At monthly intervals during the growing season root rot infection was assessed over 3 consecutive years and disease development curves were predicted for both crops. The disease development was remarkably different for Iris and Crocus and the curve shape was determined by the crop rather than by the Pythium species. Planting date had a significant effect on disease development in both crops. No correlation was found between disease development and soil temperature.

Ethylene Induction of Flowering and Gel Analysis of Apex Proteins in Dutch Iris 'Telstar'

Nonflowering-sized Dutch iris bulbs 'Telstar' were treated at 20 °C in a flow-through system with ethylene-free air or air containing 10 μL.L-1 of ethylene (C2H4) for 1 or 24 hours. Following the treatment, bulbs were placed in a 10 °C cooler for 5 weeks before planting and subsequently forced in a 20 °C day/18 °C night glasshouse. Results demonstrated that a 24-hour C2H4 treatment induced earlier flowering as well as percent flowering. Flowering responses of bulbs treated with C2H4 for 1 hour were the same as those treated with air. The 24-hour ethylene treatment did not affect the combined fresh weight of the daughter bulb and bulblets but reduced the number of bulblets produced by each. The effects of ethylene on the protein changes in the apex were examined at two time periods: immediately after the treatment and after the cold treatment. Each sample consisted of proteins extracted from three apices. There are significant changes in one-dimensional SDS PAGE protein patterns of bulbs apices after treatment with ethylene. However, the differences are apparent after only 1 hour of ethylene treatment. The cold treatment resulted in minimal further changes in protein patterns.

Effect of octanoic acid on ethylene-mediated flower induction in Dutch iris

Treatment of Dutch iris (Iris × hollandica Hoog. cv. ‘Sapphire Beauty’) bulbs with ethylene prior to precooling stimulated flowering in bulbs of various sizes. In large sized bulbs exposure to ethylene followed by precooling resulted in 100% flowering over a five months period after planting. Flowering in control bulbs which were not treated with ethylene prior to precooling was limited to 67% during the same five months period. In medium sized bulbs flowering in the ethylene treatment was 90% compared to 75% in the control. However, the biggest stimulation of flowering by ethylene was found in small sized bulbs (from 16 to 56%). Application of octanoic acid for a short time period prior to exposure to ethylene stimulated flowering in all bulb sizes. After five months the final percentage flowering in large and medium sized bulbs of the octanoic acid plus ethylene treatment did not differ from that of the ethylene only treatment. However, the initial rate of flowering was higher in the former treatment. In small bulbs the percentage flowering was much higher in the octanoic acid plus ethylene treatment than in the ethylene only treatment. The results of this study indicate that, just as in certain flowers, fruit and seeds, treatment with octanoic acid stimulates ethylene sensitivity in Dutch iris bulbs. The sensitivity of untreated bulbs to ethylene was highest in large bulbs and lowest in small bulbs. This correlated well with the endogenous octanoic acid content of the bulbs. Octanoic acid levels were highest in large bulbs and lowest in small Bulbs. It appears that the endogenous levels of octanoic acid in the bulbs is determined prior to the onset of dormancy.

Type 1 ribosome-inactivating proteins are the most abundant proteins in iris (Iris hollandica var. Professor Blaauw) bulbs: characterization and molecular cloning.

The most abundant protein of Iris bulbs has been identified as a type 1 ribosome-inactivating protein (RIP). Analysis of the purified proteins and molecular cloning of the corresponding cDNAs demonstrated that this type 1 RIP is a mixture of three isoforms that exhibit a high degree of sequence identity and have similar, though not identical, ribosome-inactivating and polynucleotide:adenosine glycosidase activities. The accumulation of large quantities of type 1 RIP in a vegetative storage organ suggests that this presumed defence-related protein also plays a role in the nitrogen-storage metabolism of the bulb.

Isolation and characterization of an N-acetyl-D-galactosamine-binding lectin from Dutch Iris bulbs which recognizes the blood group A disaccharide (GalNAc alpha 1-3Gal).

A blood group type A disaccharide (GalNAc alpha 1-3Gal)-binding lectin has been purified from Dutch Iris (Iris x hollandica) bulbs to electrophoretic homogeneity by consecutive affinity chromatography on columns of immobilized asialofetuin-Sepharose 4B and Synsorb A disaccharide (GalNAc alpha 1-3Gal beta-O-(CH2)8CONH-Synsorb). This lectin agglutinates both native and trypsin-treated rabbit erythrocytes, but not human erythrocytes, irrespective of blood group type. Gel filtration chromatography on Sephacryl S-200 HR column and SDS-polyacrylamide gel electrophoresis revealed the lectin to be a heterodimer consisting of two peptide chains (27 and 34 kDa) linked by disulfide bonds. The carbohydrate binding specificity of the lectin was investigated by quantitative precipitation, hemagglutination inhibition, and precipitation inhibition assays. It is a Gal/GalNAc-specific lectin, with an extended carbohydrate combining site, which appears to be most complementary to GalNAc linked to the C-3 or C-6 hydroxyl group of galactose. As inhibitors, these disaccharides are approximately 30-60 times more potent than galactose and 4-8-fold more active than N-acetyl-D-galactosamine, whereas both the blood type A trisaccharide (GalNAc alpha 1-3[L-Fuc alpha 1-2]Gal) and the Forssman disaccharide (GalNAc alpha 1-3GalNAc) are noninhibitory, suggesting the importance of a free equatorial hydroxyl group at the C-2 position of the penultimate galactose for lectin binding; either an acetamido group or a fucosyl group at this position appears to cause steric hindrance, thus abolishing binding to the lectin.

Multiplication and distribution of iris severe mosaic virus in secondarily‐infected iris bulbs after stress induced by heat and wounding

SUMMARYIn freshly‐lifted iris bulbs infected with iris severe mosaic virus (ISMV), virus was not always detected in the basal plate and rarely in bulb scale tissue. After exposing the bulbs to stress (wounding or high‐temperature treatment) the sensitivity of virus detection was enhanced. The improved detection of viral antigen after local stress (wounding) coincided with an increase of viral RNA synthesis. When general stress (high‐temperature treatment) was applied, the virus could be reliably detected in the basal plate, and usually in vascular bundles and surrounding tissue. Virus was detected in the upper part of the bulb scale when such tissues were detached from the basal plate. Thus, virus must have been present in the scales in localised spots, albeit at a very low concentration, and multiplication is likely to be the main factor involved in the improved sensitivity of viral detection. The distribution of ISMV in the bulb after local or general stress treatment is discussed.

Improved detection of iris severe mosaic virus in secondarily‐infected iris bulbs

SummaryThe influence of wounding and high‐temperature treatment on the detection of iris severe mosaic virus (ISMV) in secondarily ISMV‐infected iris bulbs was studied. Wounding of the bulbs just after lifting, followed by storage for 3 wk at 17°C or 20°C, increased the detectability of ISMV to 100% reliability. High‐temperature treatment and consecutive storage at 17°C induced a similar improvement of detection. It is concluded that a certain degree of stress, such as wounding or high‐temperature treatment, ultimately leads to an increase in viral antigens and thus to improvement of detection. It is hypothesised that the virus titre increases by the altered metabolism during the repair reactions as a response to stress applied to the bulbs.

Effects of anaerobiosis on ethylene production, respiration and flowering in iris bulbs

Ethylene production of iris bulbs (Iris hollandica cv. Ideal) was very low. When stored at 30°C, production was 12–20 pmol C2H4 (kg fresh weight)−1 h−1. Higher temperatures (35°C, 40°C) enhanced the ethylene production; a treatment with 40°C for ca 7 days caused a 3 times higher ethylene production than at 30°.During anaerobic storage (in 100% N2) ethylene production was equal to that of control bulbs. When after a 7 day period of anaerobiosis the N2 was replaced by air, a burstlike ethylene production was observed. Twenty‐four h after the replacement, ethylene production was equal to control values again.The effects of this production of ethylene on mitochondrial respiration and flowering were investigated. When mitochondria were isolated immediately after the anaerobic treatment (before the enhanced ethylene production) alternative pathway capacity was not detectable, a situation also occurring in control bulbs. When mitochondria were isolated 24 h after the end of the anaerobiosis (after the ethylene burst) uninhibited respiration did not change significantly, but a capacity of the alternative pathway was observed. The increase in alternative pathway capacity after anaerobiosis was partly inhibited by 2,5‐norbornadiene (NBD), an ethylene antagonist.Fermentation occurred during anaerobiosis: ethanol concentrations increased during the treatment and decreased when air was supplied. When bulbs were exposed to ethanol vapour the alternative pathway was induced but only when very high ethanol levels in the bulbs were reached. The amount of ethanol accumulated in the bulbs during a 7 day anaerobic treatment was far too low to explain the observed induction of alternative pathway capacity.Flowering percentages were enhanced after a 24 h treatment with ethylene and after a 7 day anaerobic treatment. NBD significantly inhibited the effect of exogenous ethylene and of anaerobiosis on flowering. Ethanol was not able to induce flowering. The burst‐like production of ethylene after anaerobiosis probably is responsible for the effects on respiration and flowering.

Erects of anaerobiosis on ethylene production, respiration and flowering in iris bulbs

Erects of anaerobiosis on ethylene production, respiration and flowering in iris bulbs

Temperature and development inIrisXhollandicaduring pre-planting storage. II. Floral initiation

Floral initiation was studied in Dutch iris bulbs during storage at different temperatures in the dark. Between 2 and 20°C, 90% of bulbs initiated flowers within 54 days but only 10% did so after 105 days at 25°C. Cardinal temperatures for floral initiation were derived from regressions of rates of floral initiation (1/t) on temperature. The basal temperature was found to be ca. -3°C, the optimum was ca. 13°C and the maximum was ca. 27°C. Under constant temperatures, the uniformity of floral initiation was greatest at 9 and 13°C. Transfer of bulbs from 5 to 13°C resulted in floral initiation at a rate similar to that of bulbs held continuously at 13°C, whereas it was delayed in the other transfer treatments. Uniformity of initiation was markedly increased by 14 days at 5°C prior to 13°C. Thermal times of between 291 and 354°Cd were required for floral initiation in 90% of the bulbs, between 186 and 218°Cd for the first 50% to initiate, and 82°Cd for the first 10%. While regression analysis showed these requirements not to differ significantly between bulbs in constant-temperature and in transfer-temperature treatments, only 64% of the variance was accounted for.

Formation of zeatin allylic phosphate by the microsomal fractions of bulb disks of Iris × hollandica Tub. and tubers of Helianthus tuberosus L.

It is shown that in bulbous Iris zeatin originates from a nucleotide. This nucleotide is probably zeatin-allylic-phosphate, in which a phosphate group is attached to the isoprenoid side-chain of zeatin. The formation of zeatin-allylic-phosphate from t-zeatin and 8-[14C]-zeatin by the microsomal fractions of Iris bulb disks and Helianthus tubers was demonstrated. The responsible enzyme was partially purified. 5′-AMP was found to be a phosphate group delivering substrate. Adenosine and adenine inhibited the enzyme reaction. The significance of the results is discussed in relation to cytokinin biosynthesis and the occurrence of bud blast in Iris.

The influence of infection with Penicillium corymbiferum on the forcing performance of wounded or unwounded bulbs of iris cultivars ‘Ideal’ and ‘Blue Star’ treated with ethylene or ethephon

The incidence of infection with Penicillium corymbiferum Westling of bulbs of the Dutch iris ( Iris hollandica Hoog) cultivars ‘Ideal’ and ‘Blue Star’ was greatly increased by wounding. Nevertheless, wounding and the subsequent development of blue mold had no effect on the forcing performance of bulbs treated with ethylene or ethephon, as compared with untreated bulbs. With ‘Ideal’, ethylene or ethephon treatment did not influence incidence of infection. With ‘Blue Star’ an ethephon treatment resulted in an increased infection rate with wounded bulbs. Results presented here suggest that ethylene or ethephon treatment does not predispose iris bulbs to P. corymbiferum infections severe enough to influence early forcing performance.

TOWARDS A RAPID AND RELIABLE DETECTION METHOD FOR IRIS SEVERE MOSAIC VIRUS IN IRIS BULBS

Detection of iris severe mosaic virus (ISMV) in ISMV-infected iris bulbs during storage, by either ELISA or electron microscopy has been problematic. We have applied different storage-temperature treatments and a cutting method as possible procedures to enhance ISMV detection in stored iris bulbs cv. Professor Blaauw. While at lifting ISMV could not be detected in the bulbs, gradually the virus became detectable in time when bulbs were stored at about 17°C. Better results were obtained when the cutting method was employed. Using ELISA, a 100 ␜core was obtained for infected bulbs that were cut 1 month prior to testing. The virus could be detected only in tissue adjacent to the cut surface. These results offer good prospects for the development of a reliable detection method for ISMV in iris bulbs.

Temperature and development inIris×hollandicaduring preplanting storage. I. Leaf initiation

SummaryLeaf initiation was examined in Dutch iris bulbs during pre-planting storage temperature treatments in the dark. The number of leaves initiated before inflorescence evocation increased with increasing temperature. The base, optimum and maximum temperature for leaf initiation were established as –0.4, 13.1 and 26.7°C respectively. The rate of leaf initiation was shown to be linearly related to temperature. The average thermal-time required for each leaf to be initiated under constant temperatures was 79°Cd but leaves initiated during the transfer temperature treatments required an average of 92°Cd. Rates of leaf initiation predicted from thermal-time equations were similar to those observed in bulbs stored at the lower temperatures (2–13°C) but rates observed at warmer temperature (17–25°C) never reached the predicted high value.