Der einfluß der temperatur auf eidiapause und entwicklung von Weichwanzen (Heteroptera,Miridae)

Zusammenfassung Leptopterna dolobrata (L.) (Holarktis) und Calocoris roseomaculatus (De Geer) (Paläarktis) bringen in ihrem gesamten Verbreitungsgebiet stets nur eine Generation im Jahr hervor und überwintern als Ei. Die aktiven Stadien sind nur 21/2 Monate im Jahr anzutreffen. Über 9 Monate entfallen auf das Eistadium.Als Hauptnahrungspflanzen von Leptopterna wurden Dactylis glomerata und Alopecurus pratensis festgestellt. Während die Larven I–III ausschließlich auf junge Ähren angewiesen sind können sich die späteren Stadien, sowie die Imagines durch Saugen an Stengeln und Blättern ernähren. Im Freiland wechseln die Wanzen auf andere Gräser über, sobald die Ähren einer Art aufgeblüht sind bzw. zu trocknen beginnen. Wegen der besonderen Befestigungsart der abgelegten Eier im Innern der Grashalme muß die Serosa-Kutikula eine Verlängerung erfahren, um den Schlupfprozess zu ermöglichen.Die Photoperiode hat keinen Einfluß auf den gesamten Entwicklungsverlauf.Die Ruheperiode in der Embryogenese von Leptopterna setzt stets vor der Ausrollung des Embryos ein. Im Freiland ist dieses Stadium bereits Ende Juli erreicht. Die Ruheperiode tritt unabhängig von den Umweltbedingungen in jeder Generation auf und muß deshalb als eine Form der obligatorischen Diapause bezeichnet werden. Die Gesamtentwicklung im Ei läßt sich in vier Phasen gliedern: Prä-, Meso-, Meta-und Postdiapause. Nur während der Meso-und Metadiapause sistiert die Entwicklung. Temperaturen zwischen-1° und +16°C hatten keinen Einfluß auf die Dauer der Mesodiapause. Diese Phase ist demnach temperaturunabhängig und dauert etwa 6 Monate. Die sich anschließende Metadiapause stellt eine Übergangsperiode von der eigentlichen Diapause zur Postdiapause dar. Ihr Ablauf wird durch Temperaturen unter +10°C begünstigt, während höhere Temperaturen schädigend wirken. Wegen der unterschiedlichen, Temperaturreaktion der vier Phasen kann die Gesamtentwicklung im Ei bei konstanten Temperaturen nur in dem engen Bereich von +10° bis +16°C ablaufen. Die langandauernde Eidiapause führt zu einer Synchronisation, der Erscheinungszeit von Larven und Imagines mit ihren Nahrungspflanzen.Für die Dauer der Larvalentwicklung bei verschiedenen konstanten Temperaturen gilt in dem untersuchten Bereich von +10° bis +28°C die Temperatursummenregel, wobei der Entwicklungsnullpunkt bei +5°C liegt. Eine Wechseltemperatur (14 Std: 20°C, 10 Std: 10,4°C) bewirkte, im Vergleich mit der entsprechenden konstanten Temperatur (+16°C) eine Beschleunigung der Larvalentwicklung. In +10°C erreichte zwar ein geringer Anteil der Larven das Imaginalstadium; eine Eireifung erfolgte jedoch nicht mehr.Auch Calocoris verweilt über 9 Monate als Ei. Es handelt sich grundsätzlich um denselben Diapausetyp wie bei Leptopterna. Beide Arten unterscheiden sich lediglich durch die Dauer der temperaturunabhängigen Mesodiapause (Leptopterna: 180 Tage, Calocoris: 84 Tage).Es wird ein System der Dormanzformen gegeben, in dem die bisherigen, unterschiedlichen Klassifikationen berücksichtigt sind.

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Summary Leptopterna dolobrata (L.) (Holarctis) and Calocoris roseomaculatus (De Geer) (Palaearctis) are single-brooded in the whole range of their distribution and hibernate in the egg stage. Both species are active only for 21/2 months, while the egg stage lasts over 9 months.The main food plants of Leptopterna are Dactylis glomerata and Alopecurus pratensis. Whereas the instars I–III feed on the ears of the grasses only, the later stages, including the adults, may change to the stems and leaves. In the field the bugs settle on other grass species when the blossoms of Dactylis and Alopecurus are exhausted. Because of the position of the eggs in the interior of the grass stem the serosal cuticle must lengthen to permit the process of hatching.The course of development is not influenced by the photoperiod.Dormancy during embryogenesis of Leptopterna always occurs before unfolding of the embryo. In the field this stage is already reached at the end of July. The initiation of dormancy does not depend on external factors and therefore belongs to the obligatory type of diapause. Four phases of diapause can be distinghished: prae-, meso-, meta-and postdiapause. Only during the meso-and metadiapause is development arrested. It could be shown that in mesodiapause temperatures between-1° and +16° C on the deviation of this stage, which lasts about 6 months, had no influence. The metadiapause is an interphase before the normal development of the postdiapause: it is favoured by temperatures below +10°C whereas higher temperatures are injurious. At constant temperatures complete development of the egg stage is only possible in the small range from +10° to 16° C owing to the different temperature reactions of the 4 phases of diapause. The protracted egg diapause synchronizes the appearance of larvae and adults with their food plants.At different constant temperatures in the range of +10° to 28° C larval development follows the formula of the time-temperature hyperbola with the threshold of development at +5° C. Alternating temperatures accelerate larval development as compared with corresponding constant temperatures. At +10° C only a few larvae reach the adult stage, but their gonads do not ripen.The egg diapause of Calocoris, too, lasts more than 9 months. The species differ only in the length of their temperature independent mesodiapause (Leptopterna: 180 days, Calocoris: 84 days).A new system of the main types of insect dormancy is given.

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Herrn Prof. Dr. W. Tischler danke ich für die Anregung zu dieser Arbeit und für manchen Rat während ihrer Durchführung. Herrn Dr. E. Wagner (Hamburg) möchte ich an dieser Stelle meinen Dank für die mir zur Verfügung gestellten Angaben über die Verbreitungsgebiete beider Arten aussprechen.     

Functional changes in human leukemic cell line HL-60. A model for myeloid differentiation

Polar solvents induce terminal differentiation in the human promyelocytic leukemia cell line HL-60. The present studies describe the functional changes that accompany the morphologic progression from promyelocytes to bands and poly-morphonuclear leukocytes (PMN) over 9 d of culture in 1.3 percent dimethylsulfoxide (DMSO). As the HL-60 cells mature, the rate of O(2-) production increase 18-fold, with a progressive shortening of the lag time required for activation. Hexosemonophosphate shunt activity rises concomitantly. Ingestin of paraffin oil droplets opsonized with complement or Ig increases 10-fold over 9 d in DMSO. Latex ingestion per cell by each morphologic type does not change significantly, but total latex ingestion by groups of cells increases with the rise in the proportion of mature cells with greater ingestion capacities. Degranulation, as measured by release of β-glucuronidase, lysozyme, and peroxidase, reaches maximum after 3-6 d in DMSO, then declines. HL-60 cells contain no detectable lactoferrin, suggesting that their secondary granules are absent or defective. However, they kill staphylococci by day 6 in DMSO. Morphologically immature cells (days 1-3 in DMSO) are capable of O(2-) generation, hexosemonophosphate shunt activity, ingestion, degranulation, and bacterial killing. Maximal performance of each function by cells incubated in DMSO for longer periods of time is 50-100 percent that of normal PMN. DMSO- induced differentiation of HL-60 cells is a promising model for myeloid development.     

Evaluation of inter‐individual differences in gut bacterial isoflavone bioactivation in humans by PCR‐based targeting of genes involved in equol formation

Aim

To identify human subjects harbouring intestinal bacteria that bioactivate daidzein to equol using a targeted PCR‐based approach.

Methods and Results

In a pilot study including 17 human subjects, equol formation was determined in faecal slurries. In parallel, faecal DNA was amplified by PCR using degenerate primers that target highly conserved regions of dihydrodaidzein reductase and tetrahydrodaidzein reductase genes. PCR products of the expected size were observed for six of the eight subjects identified as equol producers. Analysis of clone libraries revealed the amplification of sequences exclusively related to Adlercreutzia equolifaciens in four of the subjects tested positive for equol formation, whereas in three of the equol producers, only sequences related to Slackia isoflavoniconvertens were observed. No amplicons were obtained for one equol‐forming subject, thus suggesting the presence of nontargeted alternative genes. Amplicons were only sporadically observed in the nonequol producers.

Conclusion

The majority of human subjects who produced equol were also detected with the developed PCR‐based approach.

Significance and Impact of the Study

The obtained results shed light on the distribution and the diversity of known equol‐forming bacterial species in the study group and indicate the presence of as yet unknown equol‐forming bacteria.     

Degradation of quercetin and luteolin by Eubacterium ramulus.

The degradation of the flavonol quercetin and the flavone luteolin by Eubacterium ramulus, a strict anaerobe of the human intestinal tract, was studied. Resting cells converted these flavonoids to 3,4-dihydroxyphenylacetic acid and 3-(3,4-dihydroxyphenyl)propionic acid, respectively. The conversion of quercetin was accompanied by the transient formation of two intermediates, one of which was identified as taxifolin based on its specific retention time and UV and mass spectra. The structure of the second intermediate, alphitonin, was additionally elucidated by (1)H and (13)C nuclear magnetic resonance analysis. In resting-cell experiments, taxifolin in turn was converted via alphitonin to 3,4-dihydroxyphenylacetic acid. Alphitonin, which was prepared by enzymatic conversion of taxifolin and subsequent purification, was also transformed to 3,4-dihydroxyphenylacetic acid. The coenzyme-independent isomerization of taxifolin to alphitonin was catalyzed by cell extract or a partially purified enzyme preparation of E. ramulus. The degradation of luteolin by resting cells of E. ramulus resulted in the formation of the intermediate eriodictyol, which was identified by high-performance liquid chromatography and mass spectrometry analysis. The observed intermediates of quercetin and luteolin conversion suggest that the degradation pathways in E. ramulus start with an analogous reduction step followed by different enzymatic reactions depending on the additional 3-hydroxyl group present in the flavonol structure.     

Reversible lowering of modulated chlorophyll fluorescence after saturating flashes in Haematococcus lacustris (Volvocales) at room temperature

During modulated Chl fluorescence kinetics in zoospores of the green alga Haemutococcus lacustris Rostafinski, sudden reversible drops in fluorescence intensity immediately following each saturating light flash occur. In order to characterize the cause of these low-waves several treatments were applied to modify their expression: (I) inhibition of non-photochemical quenching by application of uncouplers: (2) application of effectors to the photosynthetic electron transport system: (3) brief chilling treatment and UV-B irradiation. The results indicate that the phenomenon is not related to oscillations of the trans-thylakoid pH gradient. The reversible short-term decrease in fluorescence after a saturating light pulse seems to originate from an imbalance between charge separation capacity of the photosystems and the electron buffering capacity of the intersystem electron transport pool.     

Computing approximate standard errors for genetic parameters derived from random regression models fitted by average information REML

Approximate standard errors (ASE) of variance components for random regression coefficients are calculated from the average information matrix obtained in a residual maximum likelihood procedure. Linear combinations of those coefficients define variance components for the additive genetic variance at given points of the trajectory. Therefore, ASE of these components and heritabilities derived from them can be calculated. In our example, the ASE were larger near the ends of the trajectory.     

ArrayIDer: automated structural re-annotation pipeline for DNA microarrays

Background  

Systems biology modeling from microarray data requires the most contemporary structural and functional array annotation. However, microarray annotations, especially for non-commercial, non-traditional biomedical model organisms, are often dated. In addition, most microarray analysis tools do not readily accept EST clone names, which are abundantly represented on arrays. Manual re-annotation of microarrays is impracticable and so we developed a computational re-annotation tool (ArrayIDer) to retrieve the most recent accession mapping files from public databases based on EST clone names or accessions and rapidly generate database accessions for entire microarrays.     

Accelerating the reconstruction of genome-scale metabolic networks

Background  

The genomic information of a species allows for the genome-scale reconstruction of its metabolic capacity. Such a metabolic reconstruction gives support to metabolic engineering, but also to integrative bioinformatics and visualization. Sequence-based automatic reconstructions require extensive manual curation, which can be very time-consuming. Therefore, we present a method to accelerate the time-consuming process of network reconstruction for a query species. The method exploits the availability of well-curated metabolic networks and uses high-resolution predictions of gene equivalency between species, allowing the transfer of gene-reaction associations from curated networks.