Genetic and photoperiodic control of an avian reproductive cycle

European blackcaps,Sylvia atricapilla, with one breeding season per year, have a single-peaked annual testes cycle. However, African conspecifics from the Cape Verde Islands with two breeding seasons per annum demonstrate a two-peaked cycle. Both population-specific cycles reflect differences in the respective endogenous circannual rhythms. Experimental hybridization of birds of the two populations resulted in an intermediate pattern of testes cycle, thus demonstrating that there are genetic components for some temporal aspects in an avian reproductive cycle. Another characteristic of the African birds, their extremely rapid juvenile development and early sexual maturity (at an age of 5–6 months) proved largely to be a photoperiodic (short-day) effect in birds hatched in autumn. The same effect could also be induced in European conspecifics exposed to correspondingly short day-lengths.     

Experimential evidence for endogenously programmed differential migration in the blackcap (Sylvia atricapilla)

Female hand-raised blackcaps (Sylvia atricapilla) held in constant conditions (except for simulated seasonal changes in photoperiod) showed significantly more, and significantly longer, autumnal migratory activity as well as significantly later initiation of spring migratory activity than males from the same population (including siblings) held under identical conditions.This research was supported by the Alexander von Humboldt Foundation (Terrill) and the Deutsche Forschungsgemeinschaft (Berthold).     

A magnetic pulse leads to a temporary deflection in the orientation of migratory birds

Migratory Australian Silvereyes were treated with a strong magnetic pulse designed to alter the magnetization of the small magnetite particles that are found in birds' heads. Prior to the treatment, the birds preferred the northeasterly migratory direction. The pulse initially resulted in a 90° clockwise shift of orientation; however, within about a week, the birds seemed to return to their original headings. These findings, which seem to suggest an involvement of magnetite in migratory orientation, are in contrast with previous findings which indicated that it is a light-dependent process. They are discussed in view of the current concepts on magnetoreception and on the role of magnetic information in avian orientation.     

Magnetic inclination compass: A basis for the migratory orientation of birds in the Northern and Southern Hemisphere

We conducted orientation experiments with Silvereyes,Zosterops lateralis, Australian passerine migrants, to see whether birds living in the Southern Hemisphere in a magnetic field with an upward inclination orient in the same way as birds in the Northern Hemisphere that experience a downward inclination of the magnetic field. Tested indoors in the local geomagnetic field, the birds preferred southerly directions corresponding to their migratory direction in spring. In a magnetic field with a reversed vertical component, they reversed their directional tendencies. This shows that the magnetic compass of Silvereyes also functions as an inclination compass based on the inclination of the field lines instead of the polarity.     

Breaking biological symmetry in membrane proteins: The asymmetrical orientation of PsaC on the pseudo-C2 symmetric Photosystem I core

The elucidation of assembly pathways of multi-subunit membrane proteins is of growing interest in structural biology. In this study, we provide an analysis of the assembly of the asymmetrically oriented PsaC subunit on the pseudo C₂-symmetric Photosystem I core. Based on a comparison of the differences in the NMR solution structure of unbound PsaC with that of the X-ray crystal structure of bound PsaC, and on a detailed analysis of the PsaC binding site surrounding the F_X iron-sulfur cluster, two models can be envisioned for what are likely the last steps in the assembly of Photosystem I. Here, we dissect both models and attempt to address heretofore unrecognized issues by proposing a mechanism that includes a thermodynamic perspective. Experimental strategies to verify the models are proposed. In closing, the evolutionary aspects of the assembly process will be considered, with special reference to the structural arrangement of the PsaC binding surface. Received 22 October 2008; received after revision 17 November 2008; accepted 05 December 2008     

Photoperiodic induction of diapause in an insect is vitamin A dependent

Summary A photoperiodic response was found to be absent in larvae of the parasitoid waspApanteles glomeratus when its host (caterpillars ofPieris brassicae) was reared on a low-carotenoid artificial diet. Addition of vitamin A to the host's diet restored the response to short-day photoperiods in the wasp larvae, thus showing that vitamin A is essential for photoperiodic induction of diapause. Possibly vitamin A or a derivative of vitamin A functions as the photoreceptor pigment for the photoperiodic reaction in this species of insect.     

Genetic load and effective size of natural populations ofDrosophila melanogaster in Korea

Summary The effect of 750 second chromosomes ofDrosophila melanogaster on viability was studied. 19.3% of them proved letal or semilethal (=drastics) in homozygous condition. Compared to data obtained in previous years at the same sampling site, a significant frequency decrease of drastics during the past decade could be observed. The dynamic processes taking place in the Korean wild populations ofD. melanogaster are discussed.Acknowledgment. This work was supported by a research grant from the Korean Science and Engineering Foundation.     

Synergism of a natural insect growth inhibitor is mediated by bioactivation

Summary Toxic plant allelochemicals are widespread in nature, but their mechanisms of action are largely unexplored. We report an example of bioactivation of a natural product, -asarone, that is mediated via insect mixed-function oxidases (MFO's), enzymes usually involved in detoxication processes. Bioactivity of -asarone is synergised by menthol, a MFO inducer, and antagonized by the MFO inhibitor piperonyl butoxide. Formation of a bioactive epoxide was confirmed by the identification of asarone epoxide and asarone diol in the insect excreta. These experiments represent the first demonstration of synergism between two natural products (-asarone and menthol) where the mechanism involves induction of enzymes usually involved in detoxication.     

Loss of FrmA leads to increased cell-cell adhesion and impaired multi-cellular development of Dictyostelium cells

Cell-cell adhesion is a critical property of all multi-cellular organisms and its correct regulation is critical during development, differentiation, tissue building and maintenance, and many immune responses. The multi-talin-like FERM domain containing protein, FrmA, is required during starvation-induced multi-cellular development of Dictyostelium cells. Loss of FrmA leads to increased cell-cell adhesion and results in impaired multi-cellular development, slug migration and fruiting bodies. Further, mixing experiments show that FrmA null cells are excluded from the apex of wild-type mounds, to which cells that normally form the organising centre known as the tip sort. These data suggest a critical role for FrmA in regulating cell-cell adhesion, multi-cellular development and, in particular, the formation of the organising centre known as the tip. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users. Received 28 August 2008; received after revision 10 October 2008; accepted 21 October 2008     

The ear-shell (Sulculus diversicolor aquatilis) myoglobin is composed of an unusual 39 kDA polypeptide chain

Summary An unusual myoglobin was isolated from the buccal mass of the ear-shellSulculus diversicolor aquatilis. The myoglobin consists of a 39 kDa polypeptide chain which is about double the size of the usual myoglobin subunit, contains one heme per molecule, and has an unusual spectral property in the oxy-form. On the basis of these properties and partial amino acid sequencing, we propose thatSulculus myoglobin has a didomain structure, and that one of the two domains does not function as an oxygen-binding domain. So far, a myoglobin of this type has not been described in mollusos.     

Gel-electrophoretic description of European populations ofTerellia virens (Loew) (Diptera,Tephritidae); implications for its use as an agent for the biological control ofCentaurea spp. (Asteraceae) in North America

Allozyme frequencies of 15 enzyme loci, 14 of which were polymorphic, were used to characterize sevenTerellia virens populations originating from three allopatrically distributedCentaurea species. The two populations whose origins were geographically furthest apart, from Israel (onC. iberica) and from Switzerland (onC. vallesiaca), showed relatively high values of genetic distance from the 5 populations sampled in Austria and Hungary (onC. maculosa) (Nei's D>0.07). The latter five displayed a high degree of genetic similarity. No diagnostic (fixed) allelic differences were observed between these three groups ofT. virens populations, but they could be well characterized by significant differences in allelic frequencies at 9 enzyme loci. Independently of this study, the populations from Switzerland (C. vallesiaca) and eastern Austria (C. maculosa) were selected as potential source populations for future introductions into North America for the biological control of introducedC. maculosa andC. diffusa. Based on the observed genetic differences and results from field experiments on the host specificity of these two potential source populations, it is argued that host specificity screening tests should be conducted separately for local (host plant) populations, as such populations might accept a different set of hosts. Biotype mismatch and the risk of spill-overs to native species could thus possibly be reduced.     

Rapid effects of insulin on cyclic GMP location in an intact protozoan

We studied rapid changes in location of cyclic GMP inTetrahymena pyriformis. Insulin caused cGMP localization in cilia and near the plasma membrane (0.5–1 min). Later (1–5 min) cGMP localization was diffuse in cytoplasm with perinuclear accentuation. Inactive insulin analogs did not elicit these changes.     

Bioactive marine metabolites. VIII. Isolation of an antimicrobial blue pigment from the bryozoanBugula dentata

Summary An antimicrobial blue pigment, which is identical with a tetrapyrrole from a bacterium, was isolated from the bryozoanBugula dentata.     

Intracellular injection of cAMP and cGMP into snail neurones induces an increase in Na+-conductance

Summary Injection of cAMP and more rarely cGMP into the neurones of the snailHelix pomatia induces an increase in membrane conductance, membrane depolarization and excitation. The effect is theophylline-dependent and has a reversal potential near — 10 mV.     

(E)-3-tridecen-2-one,an antibiotic from the interdigital glands of black-tailed deerOdocoileus hemionus columbianus

(E)-3-tridecen-2-one, the major volatile component of interdigital gland extracts from the black-tailed deer,Odocoileus hemionus columbianus, inhibited the growth of gram-positive bacteria and fungi. The bacteria,Propionibacterium acnes, and the fungi,Trichophyton mentagrophytes had a minimum inhibitory concentration (MIC) of 12.5 g/mL and 25 g/mL, respectively.     

Alteichin: an unusual phytotoxin fromAlternaria eichorniae,a fungal pathogen of water hyacinth

Summary The phytopathogenic fungusAlternaria eichorniae attacks water hyacinth, an economically significant aquatic weed. The novel phytotoxin alteichin was isolated from liquid cultures of this fungus and its structure was deduced by X-ray crystallographic analysis. Altheichin is a doubly hydrated form of 4,9-dihydroxy perylene-3,10-quinone. A single step dehydration of alteichin to anhydroalteichin is catalyzed both by acid and by a crude enzyme preparation from water hyacinth.We thank Dr R. N. Strange for the protoplast assay. Funding was provided by BARD 1-31-79, NIH-CA 24487, Bristol Laboratories, the Montana Agricultural Expt. Station, and NSF.     

Possible involvement of the phloem sealing system in the acceptance of a plant as host by an aphid

Possible reasons for the rejection of some lines ofTriticum monococcum (Tm44 and Tm46) by the aphidSitobion avenae were explored. In allT. monococcum lines studied, whether unfavourable (non-host/resistant plant) or favourable (host/susceptible plant), the concentrations of hydroxamic acids, a family of aphid-resistance factors in cereals, were significantly lower than the levels in the favourable host-plantTriticum aestivum cv. Therefore, hydroxamic acids did not account for the host/non-host patterns observed. Phloem sap was collected by stylectomy from young seedlings of favourable and unfavourable plants. In non-aphid-resistant genotypes, the success in stylectomy, the proportion of amputated stylets resulting in long (>1 min) exudations, the average duration of exudation, and the final volume of sap exuded, were higher than in the aphid-resistant genotypes. It is concluded that aphid interference with the phloem sealing system of the plant is a likely mechanism of rejection ofT. monococcum lines Tm44 and Tm46 as hosts byS. avenae.     

Temperature compensation in an ultradian rhythm of tyrosine aminotransferase activity inEuglena gracilis Klebs

Summary Tyrosine aminotransferase activity ofEuglena oscillates with an ultradian period of approximately 4–5 h. The oscillation frequency in the time series was determined by cosine fitting. Experiments which were performed between 16 and 31.5°C revealed temperature compensation.     

Partial purification of an endogenous elicitor from suspension-cultured cells of red bean,Vigna angularis

Brief irradiation with a germicidal UV lamp of cells of red bean,Vigna angularis, cultured in suspension in a quartz flask caused the release into the culture medium of an endogenous substance with elicitor activity, as well as the accumulation of isoflavone glucoside stress metabolites in the cells. The active compound was fractionated using phenylalanine ammonia lyase (PAL)-inducing activity in fresh cells as a marker. The elicitor active principle appears to be a low molecular weight (<2000 MW) water-soluble acidic oligosaccharide.