Charadrius morinellus in der Provinz Posen

Ohne Zusammenfassung     

Unusual incubation rhythms the Spotted Barbtail, Premnoplex brunnescens

The Spotted Barbtail (Premnoplex brunnescens) inhabits the understory of humid montane forests in Central and South America. Apart from basic information on eggs and nest form, little has been published on its breeding ecology. Using temperature sensors in nest cups, I have collected data on the diurnal patterns of egg-coverage from three nests in eastern Ecuador and reveal a remarkable incubation rhythm. After providing near-constant coverage during the morning, adults leave the eggs unattended for most of the afternoon, returning to the nest only in the late afternoon. The mean duration (±standard deviation) of this period of absence, across the entire incubation period at three nests, was 6.4 ± 1.9 h. These results are discussed in relation to their physiological and ecological significance.     

Breeding Population of the Ringed Plover in Britain

A census of Ringed Plovers in Britain in 1973–74 revealed a total of over 5,700 pairs, with the best concentrations in eastern England (particularly in Norfolk and Essex), the Outer Hebrides, Orkney and Shetland. Some interesting recent changes in habitat are chronicled.     

Influence of incubation temperature on productivity and quality of Spodoptera litura nucleopolyhedrovirus

Mass production of baculoviruses by in vivo methods is influenced by several factors like larval age at virus treatment, virus concentration and the incubation temperature. The larval age at virus treatment and virus concentration should be synchronized to result in insect death at a fully grown larval stage to maximize the productivity. Since temperature influences both the growth of the larvae and replication of the virus, we evaluated the influence of incubation temperature on mass production of Spodoptera litura nucleopolyhedrovirus (SpltNPV) at four different temperature regimes viz., 25, 30, and 35 °C and room temperature by diet-surface contamination method. Incubation of early fifth instar larvae dosed with 3932.4 polyhedral inclusion bodies (PIB)/mm² at 25 °C enhanced the virus productivity to 6.623 × 10¹¹ PIB yield/100 inoculated larvae, while it was only 1.779 × 10¹¹ at 35 °C. The disease progression in the virus treated larvae was slow with median lethal time (LT₅₀) of 208 h at 25 °C as compared to 136 h at 35 °C. In spite of the slow death which means lower production cycles/year, the productivity/year was higher at 25 °C than at other temperatures. The SpltNPV produced at 25 °C was also found to be of superior quality in terms of low bacterial contaminants than at 35 °C. Neonate larval bioassay conducted with viruses produced at different temperature treatments revealed that they were similar in their activity and virulence. Hence our results indicate that maintenance of the SpltNPV production facility at 25 °C would enhance both the virus productivity and quality.     

Foot-trembling and feeding behaviour in the Ringed Plover Charadrius hiaticula

The Merlin population in Orkney has undergone a marked decline during the 1980s. Site occupancy fell from 42% to 14% between 1981 and 86, while mean breeding success fell from 48% during 1975–81 to 29% during 1982–86. Mean brood size of successful nests declined from 3.3 during 1975–80 to 2.5 during 1981–87. Most breeding failures occurred during incubation. Loss and degradation of habitat, disturbance, weather, predation, organo-chlorine contamination and mercury contamination were examined as possible causes.     

Growth characteristics of flagellated cells of Phaeocystis pouchetii revealed by diel changes in cellular DNA content

The present study reports on effects of different light:dark periods, light intensities, N:P ratios and temperature on the specific growth rate of flagellated cells of Phaeocystis pouchetii in culture. The specific growth rate was estimated by diel changes in cellular DNA content. The cellular DNA content and cell cycle of flagellated cells of P. pouchetii are shown, and the importance of light:dark period in cell division is demonstrated. Diel patterns of the cellular DNA content showed that cell division was confined to the dark period. The cells dealt with more than one division per day by rapid divisions shortly after each other.The specific growth rates (μ_DNA) based on the DNA cell cycle model were in close agreement with specific growth rates (μ_Cell) determined from cell counts. The temperature affected the specific growth rates (multiple regression, p < 0.01) and were higher at 5 °C (μ ≤ 2.2 d⁻¹) than at 10 °C (μ ≤1.6 d⁻¹). Increasing the light:dark period from 12:12 h to 20:4 h affected the specific growth rate of P. pouchetii at the lower temperature tested (5 °C) (multiple regression, p < 0.01), resulting in higher specific growth rates than at 10 °C. At 10 °C, the effect of light:dark period was severely reduced. Neither light nor nutrients could compensate the reduction in specific growth rates caused by elevated temperature. The specific growth rates was not affected by the N:P ratios tested (multiple regression, p = 0.21). The experiments strongly suggest that the flagellated cells have a great growth potential and could play a dominating role in northern areas at increased day length.     

Effects of carrier, sterilisation method, and incubation on survival of Bradyrhizobium japonicum in soybean (Glycine max L.) inoculants

The production and quality of rhizobial inoculants in many developing countries is limited by the availability of suitable carriers or technological limitations. Experiments were conducted to evaluate the potential of various inexpensive and widely available carrier materials. The carriers, evaluated, were: perlite with pH adjusted with calcium carbonate or charcoal, 1:4 mixtures of perlite and malt residue, sugarcane bagasse, coal, and rice husk. We also contrasted sterilisation procedures (autoclaving or gamma irradiation) and incubation after injection (with or without initial two weeks incubation at 28 °C) for these various carriers. Survival of Bradyrhizobium japonicum strain CB1809 was monitored over a period of 6 months upon storage at 4 °C. Most carriers evaluated, were able to maintain rhizobial populations of more than 1 × 10⁹ rhizobia per gram of inoculant over that time period, with mixtures of perlite with either sugarcane bagasse or malt residue supporting the largest rhizobial populations and a mixture of perlite and rice husk the lowest. All carriers supported rhizobial growth over the 6 months period. Initially, rhizobial populations were greater with gamma irradiation than autoclaving, however after 6 months, this response was significant only with the perlite and sugarcane bagasse mixture. The incubation of the inoculant after injection also ultimately did not benefit rhizobial levels for any of the carriers, tested. Using simple sterilisation procedures and without incubating after injection, perlite based carriers can produce high quality inexpensive inoculants, maintaining bacterial populations of more than 1 × 10⁹/g rhizobia for at least 6 months.     

Comparison of the breeding habitats of Little Ringed Plover Charadrius dubius and Kentish Plover Charadrius alexandrinus on a shingle bed

The breeding habitat preferences of Kentish Plover and Little Ringed Plover were studied on a shingle bed. The location of each nest was measured as the distance to the sea wall, nearest pond and nearest path. The habitat surrounding nests was measured at radii of 0.15 m and 15 m as the proportional cover of shingle, gravel, sand, live and dead vegetation. When all variables were considered simultaneously, the differences between the habitats used by the species were related to the cover of shingle within 15 m of the nest and the distance to the sea wall. Nest sites located close to the sea wall and with high shingle cover almost always belonged to Kentish Plover, while those more distant and with low shingle cover almost always belonged to Little Ringed Plover. Kentish Plover nested in areas of newly exposed shingle, while Little Ringed Plovers used areas which had been stable for longer and hence were colonized by vegetation. This study suggests that management which maintains a high proportion of exposed substrate on shingle beds will increase their suitability for Kentish Plover.     

Extra-pair young despite strong pair bonds in the European Nuthatch (Sitta europaea)

We choose the European Nuthatch (Sitta europaea), an extremely socially monogamous passerine species, to investigate the breeding biology and frequency of extra-pair activities of females. Breeding individuals live in strong pair bonds for their total life and defend their territory all year round. As a consequence of these narrow social bonds, nuthatches have to date been considered extremely sexually monogamous. Our genetic study, however, reveals a minimum of 10% of extra-pair young in 188 chicks from 32 broods in populations of southwestern Germany. Independently of the habitat type (high via low quality), most of extra-pair sires are identified as neighbouring territory holders.     

Multiple invasions of Gypsy and Micropia retroelements in genus Zaprionus and melanogaster subgroup of the genus Drosophila

Background  

The Zaprionus genus shares evolutionary features with the melanogaster subgroup, such as space and time of origin. Although little information about the transposable element content in the Zaprionus genus had been accumulated, some of their elements appear to be more closely related with those of the melanogaster subgroup, indicating that these two groups of species were involved in horizontal transfer events during their evolution. Among these elements, the Gypsy and the Micropia retroelements were chosen for screening in seven species of the two Zaprionus subgenera, Anaprionus and Zaprionus.     

The calcium,chlorinity and alkalinity relationships in Plover Cove

Summary The relationships of calcium, chlorinity and alkalinity were determined in a unique environment, in which the water mass was built up by the introduction of freshwater from a variety of sources onto an existing sea bed. Calcium precipitation was not expected because the continual inflow of large volumes of water kept the lake in a thoroughly mixed condition. Despite the abrupt chemical and physical changes which occured, a rough constant between non-carbonate calcium and chlorinity was derived, with an average value of 1.331, and a deviation of 0.165.

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Zusammenfassung Die Beziehungen zwischen Kalzium, Chloranteil und Alkalingehalt wurden in einer besonderen Umgebung bestimmt, bei der die Wassermasse durch Einführung von Süßwasser aus verschiedenen Quellen auf ein vorhandenes Seebett gebracht wurde. Der Niederschlag von Kalzium wurde nicht erwartet, weil das unafhörliche Einströmen groß Wassermassen den See in einem gründlich durchmischten Zustand erhielt. Trotz der jähen chemischen und physikalischen Veränderungen die sich ereigneten, wurde eine ungefähre Konstante erzielt zwischen nicht kohlensaurem kalzium und dem Chloranteil. Diese Konstante zeigte einen Durchschnittswert von 1.331, bei einer Abweichung von 0.165.

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Résumé Les rapports entre le calcium, la teneur en chlore et l'alcalinité furent déterminés dans un milieu exceptionnel, oú la masse d'eau fut créée par l'introduction sur un fond de mer déjá existant, d'eau douce provenat de plusieurs sources. Une précipitation de calcium n'était pas prévue, parce que l'entrée continuelle de grandes masses d'eau conservait la condition mélangée du lac. Malgré des transformations chimiques entre le calcium non-carbonate et la teneur en chlore s'est manifestée, d'une valeur moyenne de 1.331 et avec un écart de 0.165.

     

Why do Both Parents Incubate in the Kentish Plover?

Incubation by both parents is a common parental behaviour in many avian species. Biparental incubation is expected if the survival prospects of offspring are greatly raised by shared care, relative to the costs incurred by each parent. We investigated this proposition in the Kentish plover Charadrius alexandrinus, in which both parents incubate the clutch, but one parent (either the male or the female) usually deserts after hatching of the eggs. We carried out a mate‐removal and food supplementation experiment to reveal both the role of the sexes and food abundance in maintaining biparental incubation by removing either the male or the female from the nest for a short period of time. In some nests we provided supplementary food for the parent that remained at the nest to reduce the costs of incubation, whereas other nests were left unsupplemented. Although males spent more time on incubation after their mate had been removed, females’ incubation did not change. Notwithstanding the increased male incubation, total nest attentiveness was lower at uniparental nests than at biparental controls. However, incubation behaviour was not influenced by food supplementation. We conclude that offspring desertion during incubation is apparently costly in the Kentish plover, and this cost cannot be ameliorated with supplementary food.     

Ester production in E. coli and C. acetobutylicum

Genetic engineering has improved the product yield of a variety of compounds by overexpressing, inactivating, or introducing new genes in microbial systems. The production of flavor-enhancing ester compounds is an emerging area of heterologous gene expression for desired product yield in Escherichia coli. Isoamyl acetate, butyl acetate, ethyl acetate, and butyl butyrate are reported here to be produced by expressing Saccharomyces cerevisiae genes ATF1 or ATF2 and the strawberry gene SAAT in E. coli when the appropriate substrates are provided. Increasing the concentration of alcohol added to the reaction generally resulted in increased ester production. ATF1 expression was found to produce more isoamyl acetate and butyl acetate than ATF2 expression or SAAT expression in the strains and culture conditions examined. Additionally, SAAT expression resulted in greater isoamyl acetate and butyl acetate production than ATF2 expression. Butyl butyrate is produced by cell-free extracts of E. coli harboring SAAT but not ATF1 or ATF2.     

The relation of the genes envA and ftsA in Escherichia coli

Summary The sequence of three genes involved in cell division in E. coli has been determined to be ftsA-envA-azi by three-point transduction experiments. An ftsA envA double mutant strain forms filaments at the restrictive temperature of 42° C, and not chains, but, like the chain forming envA parent strain, is hypersensitive to rifampicin.     

Relationships between geotaxis/phototaxis and diel vertical migration in autotrophic dinoflagellates

Marine dinoflagellate diel vertical migrations are often conceptuallyexplained by a species' geotactic and phototactic preferences,but actual simultaneous measurements are rare. Newly collectedsimultaneous measurements on Heterocapsa (Cachonina) illdefina(Herman and Sweeney) and Gymnodinium breve (Davis) are combinedwith similar literature information on Amphidinium carterae(Hulbert), Peridinium faeroense (Paulsen) and Prorocentrum micans(Ehrenberg) to explore several examples of the actual relationshipsbetween diel vertical migration and geotaxis/phototaxis. Amphidiniumcarterae does not migrate, but it exhibits a negative geotaxisthat may counter a small sinking velocity. The four other speciesall exhibit diel vertical migrations that yield surface aggregationsduring daylight, but the associated combinations of geotaxisand phototaxis precision (which is strongest when every cellin a population exhibits the same response to a stimulus andweakest when the response is random) and sign [which is positive(negative) when motion is toward (away from) the stimulus] aredifferent in each case. These different taxis combinations maybe related to species-specific sensor structure and/or placement.Furthermore, variations in the different biochemical pools overa species' cell cycle may contribute to structural/mechanicalchanges that influence how a given sensory array functions ata given time. If so, this coupling may be an important linkin the growth optimization mechanisms and occasional bloom successesof different autotrophic dinoflagellate species under varyingenvironmental conditions.