Schistosoma mansoni: fine structure of cercarial acetabular glands

Emerged cercariae of Schistosoma mansoni were studied with the electron microscope for the purpose of describing the acetabular (penetration) glands and their cellular investment. The two pre- and three postacetabular unicellular glands consist of enlarged aboral areas (funduses) and their oral extensions as ducts. The glands were morphologically similar except for their shape and secretory globules. In the funduses of the postacetabular glands the globules were of a single type, spheroidal to irregular in shape, with numerous electron-dense areas. Preacetabular secretory globules appeared to be of several types, varying in size, shape, and homogeneity. Some were of uniform density; others showed electron-lucid areas. The fine structure of both pre- and postacetabular globules changed as they were compared in the funduses, in progressively oral areas of the ducts and after extrusion. These changes were thought to be transitional. Microtubules and close cellular investiture of the glands by muscle, nerve, and unclassified cells with extended interwoven processes appeared to provide structural support.     

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.     

ABA content and sensitivity during the development of dormancy in lily bulblets regenerated in vitro

We measured ABA content and sensitivity in bulblels of Lilium speciosum Thunb , regenerating from scale explants in vitro at temperatures (15, 20 or 25°C) that allowed the development of various levels of dormancy (very low, intermediate or high, respectively). The one-step purification and the accuracy of the immunoassay were confirmed by HPLC and by liquid chromatography/mass spectrometry. ABA content was not correlated with dormancy development. Sensitivity to ABA was determined as the difference in sprouting performance of excised bulblets on medium with and without ABA. In bulblets regenerating at 20 or 25°C. ABA sensitivity was high during the period of dormancy establishment and decreased thereafter. Dormant hulblets were almost completely insensitive to ABA. The changes in sensitivity to ABA were confirmed by measuring the level of ABA in bulblets at the time of sprouting. This level was, as expected, highest in bulhlels with low ABA-sensitivity. Briefly cold-treated bulblets, in which dormancy may he re-established by culture at 20°C, again became sensitive to ABA. ABA sensitivity decreased with increasing temperature bulblets that regenerated at I5°C and hardly developed any dormancy, were very sensitive to ABA. It was concluded that in addition to ABA sensitivity another, still unknown, factor played a key role in dormancy development.     

Effect of morphactin on stem growth in relation to auxin in precooled rooted tulip bulbs

Effect of morphactin IT 3456, an auxin transport inhibitor, on tulip stem elongation induced by indole-3-acetic acid (IAA) was investigated. Tulip stem growth induced by IAA 0.1 % in lanolin paste applied on the top internode after excision of flower bud and removal of all leaves was greatly inhibited by 0.2 % morphactin IT 3456 applied on the 4th, 3rd, 2nd and 1st internode. The inhibitory effect of the morphactin on tulips stem growth promoted by IAA was restored by additional application of IAA below the morphactin treatment place. Morphactin inhibited also the growth of all internodes induced by flower bud in the absence of leaves. These results suggest a crucial role of auxin in the control growth of all internodes in tulip stem.     

Soluble and insoluble invertase activity in elongating Tulipa gesneriana flower stalks

Previously 'frozen' Tulipa gesneriana L. bulbs cv. Apeldoorn, were planted and grown at higher temperatures to study the role of invertase (EC 3.2.1.26) in the cold-induced elongation of the flower stalk internodes. After planting, flower stalks were left intact, or, the leaves and flower bud were both removed to inhibit internode elongation. In intact flower stalks, elongation of the internodes was accompanied by an accumulation of glucose and an initial decrease in the sucrose content g,⁻¹ dry weight. Insoluble invertase activity g,⁻¹ dry weight hardly changed, but soluble invertase activity showed a peak pattern, that was related, at least for the greater part, to the changes in the sugar contents. Peak activities of soluble invertase were found during (lower- and uppermost internodes) or around the onset of the rapid phase of internode elongation (middle internodes). Internode elongation and glucose accumulation immediately ceased when the leaves and flower bud were removed. Insoluble invertase activity g,⁻¹ dry weight remained at its initial level (lowermost internode) or increased more towards the upper internodes. Soluble invertase activity did not further increase (uppermost internode) or decreased abruptly to a low level. It is concluded that soluble invertase may be one of the factors contributing to glucose accumulation and internode elongation in the tulip flower stalk.     

Changes in free polyamines in Tulipa gesneriana flower stalks during dry-storage and after planting of bulbs

Tulip bulbs cv. Apeldoorn are dry-stored at 5°C for 12 weeks to ensure sufficient elongation of the flower stalk, when subsequently planted at higher temperatures (17–20°C). To investigate whether free polyamines are involved in this process, flower stalk internodes were analyzed during dry-storage and after planting of the bulbs.During dry-storage for 12 weeks at 5°C (cooled) and 17°C (non-cooled), the free putrescine, spermidine and spermine amounts per flower stalk increased. The putrescine amount increased at 5°C significantly more than at 17°C, whereas the opposite was found for the spermine amount. These differences developed early during dry-storage and disappeared rapidly at subsequent higher temperatures.After planting, the lower- and uppermost flower stalk internodes of the pre-cooled bulbs elongated much faster than those of the non-cooled ones. In the pre-cooled bulbs, the free polyamine amounts per internode increased with time after planting, but the time course of these changes was different. In the non-cooled bulbs, the free polyamine amounts increased to a much lesser extent or remained more or less constant.It is argued that the observed changes in the free polyamine contents are probably not required for the cold-induced extension growth of tulips cv. Apeldoorn.Abbreviations PA polyamine - Put putrescine - Spd spermidine - Spm spermine     

Protection of DAergic neurons mediates treadmill running attenuated olfactory deficits and olfactory neurogenesis promotion in depression model

In this study, we aimed to test the effects of treadmill running on depression induced olfactory functions and OB neurogenesis in depression model. Depression model was created with chronic unpredictable mild stress (CUMS) and treadmill running was performed as the antidepressant treatment. Behavioral results showed that treadmill running not only attenuated the depression mood but also improved the olfactory discrimination and sensitivity in CUMS depression model. Immune-staining further indicates treadmill running promoted neurogenesis in hippocampal OB region. Moreover, treadmill running prevented the loss of DAergic neurons in glomerular layer of OB region, indicating the critical role of DAergic neuronal functions in regulating treadmill running mediated olfactory functions. In depression model, inhibiting DAergic neurons by intra-OB injection of 6-OHDA resulted in the compromised improving effects of treadmill running olfactory discrimination. In conclusion, treadmill running could attenuate depression associated olfactory deficits by promoting olfactory neurogenesis and improve DAergic neural functions.     

Abscisic acid controls dormancy development and bulb formation in lily plantlets regenerated in vitro

Plantlets of lily regenerated in vitro from scale explants consist of scales and leaves from which the base of the petiole has swollen to a scale. Fluridone, an inhibitor of ABA-synthesis, applied during culture in vitro, inhibited the swelling of the petioles and promoted leaf formation. At high fluridone concentrations (10 or 33μ M ), swelling was completely blocked, and plantlets consisted of leaves only. Addition of ABA during the regeneration in vitro had the opposite effect and resulted in plantlets with scales only. When applied simultaneously with fluridone, ABA nullified the effect of fluridone. This demonstrates that bulb formation in lily is under the control of ABA. Lily plantlets regenerated in vitro on scale explants at 20 or 25°C were harvested after 11 weeks, and the leaves were removed from the bulblets. The bulblets were dormant and required a cold treatment to achieve rapid emergence after planting in soil. Fluridone added during the culture in vitro prevented the development of dormancy, and the bulblets did not require a cold treatment. The effect of fluridone was nullified by simultaneous addition of ABA. Bulblets harvested after 6 weeks of culture at 20°C had not yet developed dormancy. Bulblets regenerated at 15°C were only slightly dormant. In both types of bulblets, it is unlikely that the lack of dormancy was due to low ABA-levels since addition of ABA did not affect the dormancy status. These data indicate that the level of endogenous ABA and an unknown additional factor play major roles in the development of dormancy.     

The development of dormancy in bulblets of Lilium speciosum generated in vitro

We have studied the effect of various in-vitro conditions on dormancy of bulblets generated on scale explants of Lilium speciosum Thunb. cv. Rubrum nr. 10. The bulblets were harvested after 11 weeks of culture. Dormancy was measured by determining the percent emergence in soil of viable, non-cold-treated bulblets. A study of the physical conditions showed that temperature had a strong effect on the induction of dormancy (15°C induced hardly any dormancy; 25°C induced a high level of dormancy), whereas short or long day and light or dark had no effect. Of the medium components, a low concentration of sucrose (1 gl^–1 or less) or a high concentration of gibberellic acid (1 mg 1^–1) reduced the level of dormancy. Application of various concentrations of abscisic acid, 6-benzylaminopurine, -naphthaleneacetic acid, indole-3-acetic acid, 2,3,5-triiodobenzoic acid or a Murashige and Skoog macro- and microelement mixture did not affect the dormancy status.Abbreviations ABA abscisic acid - BAP 6-benzylaminopurine - GA₃ gibberellic acid - IAA indole-3-acetic acid - MS Murashige & Skoog macro- and microelements - NAA -naphthalene-acetic acid - TIBA 2,3,5-triiodobenzoic acid