Brominated diphenyl ethers from a marine bacterium associated with the spongeDysidea sp.

Summary BacteriaVibro sp. isolated from the spongeDysidea sp. were shown to biosynthesize brominated diphenyl ethers. We identified one of the bacterial brominated metabolites using gas liquid chromatography and mass spectrometry to compare this product with standard 3,5-dibromo-2-(3,5-dibromo-2-methoxyphenoxy)phenol. The latter has been isolated from ethanol extracts of the spongeDysidea sp.     

Novel substrates for the kinetic assay of esterases associated with insecticide resistance

Naphthalene thioesters were synthesized as substrates for a continuous, non- disruptive kinetic assay of general carboxylesterase activity. The continuous nature of the assay is based on the production of a soluble dianion chromophore from the reaction of naphthalene thio with 5,5-dithiobis (2-nitrobenzoic acid). Applications with 1- and 2-naphthalene thioacetates demonstrated their use in a fast accurate kinetic microassay of esterase activity, using porcine carboxylesterase as a model. These novel esters proved to be useful as substrates for the spectrophotometric assay of insecticide-resistance in two aphid species and may be applicable to other esterasebased diagnostic procedures.     

Negative phototaxis inDrosophila associated with a morphological change in the compound eye

Summary The ultrastructure of the compound eyes of several photonegative selection lines and their unselected photopositive controls of five species of themelanogaster subgroup was analyzed. A qualitative phenotypic change concerning the rhabdomeres in one of the photonegative selection lines ofD. mauritiana could be detected. It was proved that this structural aberration of the rhabdomeres is caused by a parallel mutation of the mutantora (outer rhabdomeres absent) ofD. melanogaster.     

Okadaxanthin,a novel C50-carotenoid from a bacterium,Pseudomonas sp. KK10206C associated with marine sponge,Halichondria okadai

To study the origins of biologically active substances in marine sponges, a carotenoid produced by a marine bacterium,Pseudomonas sp. strain number KK10206C, which was associated with a marine sponge,Halichondra okadai, was investigated. A visible absorption spectrum-guided isolation procedure led to the isolation of a novel C₅₀-carotenoid, okadaxanthin. Its structure, 2,2-bis(4-hydroxy-2-methyl-2-butenyl)-,-carotene, was elucidated mainly by spectroscopic methods. Okadaxanthin turned out to be a potent singlet oxygen quencher, approximately 10 times as strong as -tocopherol.     

In vitro inhibition by dopamine of 5-hydroxytryptamine-stimulated ovarian maturation in the red swamp crayfish,Procambarus clarkii

Dopamine inhibits 5-hydroxytryptamine-stimulated maturation of the ovaries of the red swamp crayfish,Procambarus clarkii, in vitro just as it does in vivo. This in vitro inhibition appears to be due to inhibition of release of the gonad-stimulating hormone from the brain and thoracic ganglia. However, it is possible that in vivo dopamine also triggers release of the gonad-inhibiting hormone.     

In vivo inhibition by dopamine of 5-hydroxytryptamine-stimulated ovarian maturation in the red swamp crayfish,Procambarus clarkii

In vivo dopamine antagonizes the ovary-stimulating action of 5-hydroxytryptamine in the red swamp crayfish,Procambarus clarkii.     

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.     

Insect tissues,not microorganisms,produce linoleic acid in the house cricket and the American cockroach

Summary Biosynthesis of linoleic acid, 182(n–6), was unambiguously demonstrated to occur in the cockroach,Periplaneta americana, and the cricket,Acheta domesticus. Axenic tissue from both of these insect species was demonstrated by radio-gas-liquid chromatography (radio-GLC) and radio-high-performance liquid chromatography (radio-HPLC) to incorporate [1-¹⁴C]acetate and [1-¹⁴C]oleate into this essential fatty acid.This work was supported by the National Science Foundation under grant DCB-8914417. We would like to thank Coby Schal for his generous gift of American cockroaches and Tania Kellermeyer for her excellent technical assistance.     

Mitochondrial DNA variation in geographic populations of Colorado potato beetle,Leptinotarsa decemlineata (Coleoptera; Chrysomelidae)

Summary This study demonstrates variability in restriction enzyme cleavage sites of mitochondrial DNA (mtDNA) among four popalations of Colorado potato beetle (CPB). A suite of three enzymes (EcoRI,HpaI,PstI) was sufficient to discriminate among the populations tested. Individuals heteroplasmic for restriction enzyme patterns were found in some populations. Variability in CPB mtDNA should prove useful in efforts to trace the origin and dispersal of the species in North America.     

Enzyme polymorphism in the Sicilian honeybee

Summary In Sicily we can identify two genetically differentiated groups of local honeybee populations, on the basis of the only two polymorphic loci,Mdh-1 andEst; the western one, whose genetic characteristics are probably those of the native honeybee (Apis mellifera sicula) and the eastern one affected by recent large-scale importation of Italian bees from northern Italy.This research was supported by a grant of the Ministero della Pubblica Istruzione.     

Duplications of additively acting genes in the evolution of a plant (Microseris pygmaea)

Summary Crosses betweenMicroseris pygmaea (10 pappus parts per fruit) andM. bigelovii (5 pappus parts) have revealed 10-determining genes that additively determine the average number of pappus parts in the hybrids. One or two such genes are found in different populations. Two independent duplications of the original 10-determining gene seem to have occurred.     

Detection of protease inhibitors in the hemolymph of resistantAnticarsia gemmatalis which are inhibitory to the entomopathogenic fungus,Nomuraea rileyi

Summary A complex of protease inhibitor activities has been detected in the hemolymph of the 6th instarAnticarsia gemmatalis larvae that are resistant to infection by the fungusNomuraea rileyi. A site-specific serine protease inhibitor extracted fromA. gemmatalis hemolymph inhibits both the germination ofN. rileyi conidia and subsequent germ tube development.     

Queen success is correlated with worker-brood genetic relatedness in a primitively eusocial wasp (Ropalidia marginata)

Ropalidia marginata is a primitively eusocial polistine wasp in which, although there is only one queen at any given time, frequent queen replacements lead to a system of serial polygyny. One of the most striking features of this system, is the enormous variation in the success of different queens. Measuring queen success as queen tenure, total number of offspring produced, number of offspring produced per day of tenure, and proportion of eggs laid that develop into adults, we show here that each measure of queen success is correlated with worker-brood genetic relatedness and not correlated with worker: brood ratio or the age of the queen at takeover. We interpret these results as meaning that queens are better able to obtain the cooperation of workers when worker-brood genetic relatedness is high.     

Methyllycaconitine,a naturally occurring insecticide with a high affinity for the insect cholinergic receptor

Summary Studies of extracts ofDelphinium seeds, long known to be insecticidal, revealed that a principal insecticidal toxin was methyllycaconitine, which is shown to be a potent inhibitor of -bungarotoxin binding to housefly heads (K_inh=2.5×10^–10±0.5×10^–10M).Calgary for gifts of MLA, citrate and lycoctonine, and Dr W. Bowers of the University of Arizona for the original extract ofDelphinium seeds. We would also like to acknowledge the able technical support of Ms C. Dushin, Mr E.L. Bowman, Dr C. C. Gagne, Mr R. F. Borysewicz and Dr P. Mowery for his assistance in obtaining and interpreting the carbon-13 NMR spectra.     

Possible origin of zeaxanthin in the marine sponge,Reniera japonica

As part of a study to clarify the origins of biologically active substances in marine sponges, the carotenoids produced by two species of marine bacteria,Flexibacter sp. strain number DK30213 and DK30223, associated with the marine sponge,Reniera japonica, were investigated. Both bacteria were found to produce zeaxanthin [(3R, 3R)-dihydroxy-,-carotene] which is widely distributed in marine organisms. This carotenoid was also detected in the host sponge, suggesting the transport of zeaxanthin from the microorganisms to the host. As zeaxanthin plays the role of a quencher and scavenger for active species of oxygen, it is presumed that the sponge accumulates the bacterial product as a defense substance against the active oxygen species produced under irradiation by strong sunlight. It is thought that the bacteria are symbionts of the host sponge and act by obtaining the solid substrate and medium needed for settlement and growth from the host, and by producing and transmitting the biologically active substance to the host. Zeaxanthin-producing bacteria are also considered to have potential for practical uses by the aquacultural, pharmaceutical and food industries.     

Differences in the stimulation by calcium ionophore of juvenile hormone III release from corpora allata of solitarious and gregariousLocusta migratoria

Summary Incubation of the calcium ionophore A23187 resulted in an increase in the median rate of juvenile hormone III release by corpora allata (CA) of both gregarious and solitarious adultLocusta migratoria females at 3, 5 and 8 days after fledging. At all 3 datapoints, the enhancement of release rates was highly significant for CA from gregarious females but not significant for CA from solitarious females.     

A testis-specific lactate dehydrogenase in the pipid frog,Hymenochirus boettgeri

Summary Lactate dehydrogenase zymograms of mature testes ofHymenochirus boettgeri show in addition to the five isozymes composed of LDH-A and LDH-B subunits, a second 5-band system which is due to isozymes formed between LDH-A and a third subunit, LDH-C. These testis-specific LDH-C isozymes appear around 6 months after metamorphosis indicating that their expression is correlated with sexual maturity as is generally the case in mammals. This is the first report of a testis-specific LDH isozyme in a lower tetrapod; such isozymes have hitherto only been reported in mammals and in the pigeon.This study was supported by a grant from the Fond National Suisse de la Recherche Scientifique to H.R.K. We thank M. Sateur and F. Bourquin for their technical help.