Freeze-fracture observations on membranes of dry and hydrated pollen from Collomia,Phoenix and Zea

Pollen from Collomia grandiflora Dougl. ex Lindl., Phoenix dactylifera L. and Zea mays L. was examined by freeze-fracture electron microscopy. Particular attention was paid to the organization of the cell membranes in the naturally dehydrated, as compared to the fully hydrated, state. All membranes examined had a normal bilayer organization similar to that seen in the hydrated cells of these and other plants. This organization of dry pollen membranes is discussed as it relates to physiological studies (e.g., leakage of ions during hydration), and to biophysical properties of biological and model membranes under various conditions of hydration and dehydration.Abbreviations EF, PF exoplasmic and protoplasmic fracture, respectively - H_II hexagonal II - IMPs intramembranous particles     

Callus formation and plant regeneration through direct culture of isolated pollen of Hordeum vulgare cv. ‘Sabarlis’

Summary Pollen calli and plantlets of Hordeum vulgare cv. Sabarlis were obtained through direct pollen culture without pretreatment of spikes or preculture of anthers. Isolated immature pollen grains were cultured first in a 0.3 M mannitol solution or a C1 basal medium (Chen et al. 1979) supplemented with 0.3 M mannitol but without sucrose for 5–7 days, then transferred into a C1 medium containing 6% sucrose, 3 mM glutamine and 5 mM m-inositol. After a 3 week culture period small pollen calli derived from the pollen grains were transferred into a growth medium comprising C1 basal medium supplemented with 250 mg/1 lactalbumin hydrolysate and 0.5 mg/1 kinetin. For shoot regeneration, vigorously growing calli were transferred onto agarsolidified MS medium (Murashige and Skoog 1962) containing 3% sucrose, 2 mg/1 benzyladenine and 0.5 mg/1 indole-3-acetic acid. The ratio of green plants to albino was approximately 12.2.     

Sphaeroceridae (Diptera) caught in light traps at Rothamsted Experimental Station, Herts., 1980–83

ABSTRACT.

• 1 A total of 7063 specimens of Sphaeroceridae representing forty species were caught in four light traps, two in woodland and two in the open, at Rothamsted Experimental Station between December 1980 and December 1983.
• 2 A complete list of species and the numbers of individuals of each is provided.
• 3 The catches in the two traps in woodland were less diverse than the catches in the two traps in the open.
• 4 Two-way analysis of variance demonstrated a significant difference in catch from trap to trap.
• 5 When their similarities were compared, the four light trap catches formed two groups, corresponding with habitat type.
• 6 The majority of the catch were Copromyza similis (Collin) (5555 specimens or 78.64% of the total). The species was most abundant in winter from mid-December to early February, although there were slight differences in times of maximum abundance between open and woodland habitats.

     

Paleolimnological reflections of fiber-plant retting in the sediment of a small clear-water lake

Likolampi is a small groundwater kettle-hole lake in Ilomantsi, Eastern Finland. At 11 m water depth the uppermost 51 cm of sediment contains about 390 varves. A thin layer of chrysophyte statospores is the main structural unit in these; in some varves it is followed by a layer of cf. Drepanocladus fluitans moss spores. Below the laminated sequence, two layers of moss detritus (110–87 cm, 81–51 cm) alternate with greyish brown fine detritus. Pollen analysis reveals that the start of the deposition of varved sediment coincides with the beginning of intensive fiber plant retting with large quantities of Cannabis/Humulus -type pollen and even regular occurrence of the insect-pollinated Linum usitatissimum. The cf. Drepanocladus spores are almost absent during the retting period (c. 1590–1900 by the varves), but very common before and after it. Drepanocladus fluitans is capable of assimilating dissolved CO₂ in water, so it thrives at low pH and is typical for oligotrophic clear-water lakes. We conclude that the stratigraphy of Drepanocladus fragments and spores is a true negative indicator of cultural influence in Likolampi.     

Some observations onStrongwellsea castrans [Zygomycetes: Entomophthorales], a parasite of root flies [Delia spp.], in the south of Scotland

Root flies,Delia radicum (L.) andD. floralis (Fallén) (Diptera: Anthomyiidae), trapped in swede crops in the south of Scotland, were infected withStrongwellsea castrans Batko and Weiser (Zygomycetes: Entomophthorales). The pathogen was associated mainly with females of the 1st and 2nd generations ofD. radicum and of the single generation ofD. floralis. Disease incidence showed time-lagged density dependence. Greatest sustained infection levels were recorded in the coolest wettest season. Higher proportions ofD. radicum were infected in the headland than in the crop. Unbaited yellow water traps caught greater proportions of infected flies than traps baited with mustard oil (allyl isothiocyanate). The reasons for high levels of infection in Scotland are discussed.

---

Résumé Les mouches des racines,Delia radicum (L.) etD. floralis (Fallén) [Diptera: Anthomyiidae] attrapées dans la culture du rutabaga dans le sud de l'écosse, étaient contaminées parStrongwellsea castrans Batko & Weiser [Zygomycetes: entomophthorales]. Le pathogène était surtout associé aux fe nelles de la lère et de la 2ème générations deD. radicum et de la seule génération deD. floralis. Les cas de maladie montraient avec retard leur dépendance avec la densité des mouches. Les niveaux d'infection les plus grands étaient enregistrés pendant la saison la plus froide et la plus humide. Les bordures en friche des parcelles hébergeaient de plus grandes proportions deD. radicum infectés que les cultures. Des pièges jaunes sans appat ont attrapé de plus grandes proportions de mouches que lorsqu'ils étaient appatés avec de l'huile de moutarde (allyl-isothiocyanate). Les raisons qui expliquent pourquoi les niveaux d'infection en écosse sont plus élevés qu'ailleurs sont discutées.

     

Effects of dose and attractant on interactions between pheromone traps for the pea moth, Cydia nigricana

The effects of different doses of two attractants on the interactions between pheromone traps for the pea moth, Cydia nigricana (F.) were investigated. In lines of three traps along the wind, each containing 10³ g (E)-10-dodecen-1-yl acetate (E10-12: Ac), interactions were evident at spacings of 15 m and 50 m; the centre trap catch was suppressed (cf. an isolated trap) but, unlike interacting traps containing 10² g (E,E)-8, 10-dodecadien-1-yl acetate (E, E8, 10–12: Ac), the upwind trap did not catch more moths than the other traps.Changing the dose of E10-12: Ac in lines of traps with a spacing of 50 m did not affect the profile of catches, but reducing the dose of E, E8, 10–12: Ac to 1 g per trap resulted in a profile similar to that obtained with all doses of E10-12: Ac.The efficiency with which traps caught moths approaching within 1 m was affected by the attractant rather than the dose. Traps containing E, E8, 10–12: Ac were almost twice as efficient as those containing E10-12: Ac, suggesting that the former is a better close-range attractant.

---

Zusammenfassung Die Wirkung verschiedener Mengen zweier Attraktivstoffe auf die gegenseitige Beeinflussung von Pheromonfallen für den Erbsenwickler, Cydia nigricana F., wurde untersucht. Drei Fallen mit je 10³ g des Pheromonanalogs (E)-10-dodecen-1-yl Acetat (E10-12: Ac), wurden in einer Reihe in der Hauptwindrichtung aufgehängt. Bei Fallenabständen von 15 m und 50 m war die gegenseitige Beeinflussung offensichtlich. Im vergleich mit isolierten Fallen wurde der Fang der zentralen Falle reduziert. Die Aufwindfalle fing nicht mehr als die andern Fallen und zwar im Gegensatz zu Versuchen, in denen die Fallen je 10² g des natürlichen Pheromons (E,E) 8, 10-dodecadien-1-yl Acetat (E, E8, 10–12: Ac) enthielten.Wenn die Menge von E10-12: Ac in Fallenreihen mit 50 m Abstand geändert wurde (z.B. 10⁴ g), wurde das Fangprofil nicht geändert. Wurde die Menge von E, E8, 10–12: Ac auf 1 g pro Falle vermindert, ergab sich ein Profil, das allen Kombinationen von E10-12: Ac entsprach.Die Fängigkeit der Fallen im Nahbereich von 1 m wurde mehr durch den Lockstoff als durch die Menge beeinflusst. Fallen mit E, E8, 10–12: Ac waren fast zweimal fängiger als Fallen mit E10-12: Ac (37% und 22%). Demnach scheint die erste Substanz der bessere Nahdistanzlockstoff zu sein.

     

Pollenkitt is lacking inGnetum gnemon (Gnetaceae)

The anther tapetum of the gymnospermGnetum gnemon produces no lipid osmiophilous droplets as pollenkitt forerunners. Thus—in contrast to entomophilous and anemophilous angiosperms—no pollenkitt is produced at all. From lack of pollenkitt in other gymnosperms, it appears to be restricted to angiosperms. This can be considered as new and additional proof for the hypothesis that the angiosperms are one coherent phylogenetic group, and that the development of pollenkitt in their ancestors was one of the main prerequisites for the adaptive switch to entomophily.     

Selection of embryogenic pollen from cold-treated buds ofNicotiana tabacum var. badischer burley and their development into embryos in cultures

Summary By using density gradient centrifugation, employing 55% percoll and 4% sucrose as suspension medium, it is possible to select embryogenic pollen from buds after cold treatment at 10 °C for 8 or more days. These buds at the uninucleate stage of pollen were collected from plants grown in 8 hours photocycles at 18 °C and supplied with mineral salts. The embryogenic pollen are small, starch-free with a clear cytoplasm whereas large starch-filled ones are nonembryogenic. The embryogenic pollen regularly form embryos at a frequency of 2% on a mineral medium supplemented with glutamine, asparagine and sucrose at pH 6.5.These results demonstrate, for the first time, that it is possible to have embryos in appreciable frequencies in ab initio pollen cultures raised from cold treated anthers.On leave from University of Delhi.