Identification of male- and female-specific olfaction genes in antennae of the oriental fruit fly (Bactrocera dorsalis)

The oriental fruit fly (Bactrocera dorsalis) is a species of tephritid fruit fly, endemic to Southeast Asia but also introduced to many regions of the US, and it is one of the major pest species with a broad host range of cultivated and wild fruits. Although males of B. dorsalis respond strongly to methyl eugenol and this is used for monitoring and estimating populations, the molecular mechanism of the oriental fruit fly olfaction has not been elucidated yet. Therefore, in this project, using next generation sequencing technologies, we sequenced the transcriptome of the antennae of male and female adults of B. dorsalis. We identified a total of 20 candidate odorant binding proteins (OBPs), 5 candidate chemosensory proteins (CSPs), 35 candidate odorant receptors (ORs), 12 candidate ionotropic receptors (IRs) and 4 candidate sensory neuron membrane proteins (SNMPs). The sex-specific expression of these genes was determined and a subset of 9 OR genes was further characterized by qPCR with male and female antenna, head, thorax, abdomen, leg and wing samples. In the male antennae, 595 genes showed a higher expression, while 128 genes demonstrated a higher expression in the female antennae. Interestingly, 2 ORs (BdorOR13 and BdorOR14) were highly and specifically expressed in the antennae of males, and 4 ORs (BdorOR13, BdorOR16, BdorOR18 and BdorOR35) clustered with DmOR677, suggesting pheromone reception. We believe this study with these antennae-enriched OBPs, CSPs, ORs, IRs and SNMPs can play an important role in the detection of pheromones and general odorants, and so in turn our data improve our current understanding of insect olfaction at the molecular level and provide important information for disrupting the behavior of the oriental fruit fly using chemical communication methods

Inversions in the third chromosome of wild races of Drosophila pseudoobscura, and their use in the study of the history of the species

Genetic studies showed several years ago that the third chromosomes of wild strains of Drosophila pseudoobscura often carry suppressors of crossing-over. The salivary gland chromosome technique has made it possible to demonstrate not only that these are inverted sections, but also that there are many different inversions present in wild populations inhabiting different geographical regions. So far we have found at least fourteen different gene-sequences in wild stocks, and have found that in most geographical regions several sequences are present, though no single sequence appears to occur throughout the range of the species. There are a number of problems raised by these facts, most of which need further study; the present account is to be regarded only as a preliminary note

Parametric Alignment of Drosophila Genomes

The classic algorithms of Needleman--Wunsch and Smith--Waterman find a maximum a posteriori probability alignment for a pair hidden Markov model (PHMM). In order to process large genomes that have undergone complex genome rearrangements, almost all existing whole genome alignment methods apply fast heuristics to divide genomes into small pieces which are suitable for Needleman--Wunsch alignment. In these alignment methods, it is standard practice to fix the parameters and to produce a single alignment for subsequent analysis by biologists. Our main result is the construction of a whole genome parametric alignment of Drosophila melanogaster and Drosophila pseudoobscura. Parametric alignment resolves the issue of robustness to changes in parameters by finding all optimal alignments for all possible parameters in a PHMM. Our alignment draws on existing heuristics for dividing whole genomes into small pieces for alignment, and it relies on advances we have made in computing convex polytopes that allow us to parametrically align non-coding regions using biologically realistic models. We demonstrate the utility of our parametric alignment for biological inference by showing that cis-regulatory elements are more conserved between Drosophila melanogaster and Drosophila pseudoobscura than previously thought. We also show how whole genome parametric alignment can be used to quantitatively assess the dependence of branch length estimates on alignment parameters. The alignment polytopes, software, and supplementary material can be downloaded at http://bio.math.berkeley.edu/parametric/.Comment: 19 pages, 3 figure

Female remating in Drosophila ananassae: effect of density on female remating frequency

Drosophila ananassae, a cosmopolitan and domestic species, is largely cir-cumtropicalin distribution and belongs to the ananassae species complex of the ananassae subgroup of the melanogaster species group. In the present study, experiments were conducted to investigate the effect of density on fe-male remating frequency by employing different wild-type and mutant strains of D. ananassae. Two experimental designs, i.e., 2-h daily observation and continuous confinement, were used. The results show that there is significant dependence of remating frequency on density in all strains tested under both experimental designs except in a wild-type strain (Bhutan), which shows no dependence of remating frequency on density under 2-h daily observation de-sign. This finding provides evidence that density may increase the frequency of female remating in D. ananassae

Geographical changes in relative frequency of inversions in chromosome III of Drosophila pseudoobscura among natural populations from Mexico

Chromosomal polymorphism in natural populations of Drosophila pseudoobscura have been broadly studied in the USA but scarcely in Mexico where only about 60 localities have been analyzed. Differences among both regions are notorious with respect to their chromosomal constitution. Northern populations, those of USA, have as representative inversions the sequences ST, AR and CH contrasting with those in Southern populations (Mexico) in which prevail the gene arrangements TL, CU and SC. Assuming as a probable mechanism that has allowed these substitutions the flow generated by the presence of a North - South clines, we took as a goal find out if such clines really exist. With that objective in mind we studied 29 populations of this species distributed along four North - South transects. Specimens of D. pseudoobscura caught by attracting them with fermenting bananas were carried to the laboratory where from each female an isofemale line was established. When their offspring appeared a single larva from each isofemale was taken, its salivary glands extracted and stained with a solution of lacto-aceto- orcein, by these means the polytene chromosomes were obtained. On these chromosomes we identified, for each larva, the inversion (s) carried in the third chromosome, in such a way 3439 third chromosomes were analyzed. Among the 29 localities we identified 17 different inversions but the number of them varied from population to population from three to eleven. Relative frequencies of each inversion at every location were calculated and with them for each transect the presence or absence of clines was determined. Among each transect the existence of clines was observed only between two or three near by populations, but we were not able to find a clear manifestation of the presence of clines along a complete transect. Our results at this respect are similar to those previously reported for USA populations. A mechanism that explains North - South substitutions of predominant inversions remains as open question

Temporalchanges in relative frequencies of third chromosome inversions of Drosophila pseudoobscura in Mexican populations

Variations in relative frequencies of third chromosome inversions during 1974-2000 in three populations of D. pseudoobscura from Mexico were analyzed. The general constitution of these populations is formed from ten up to 15 different inversions, been prevalent, as data shows, the gene arrangements CU, TL, SC, OA, EP, and OL as main components of the studied populations. In Amecameca and Tulancingo we observed that they were constituted by a dominant pair in both cases represented by such partners as CU-TL inside each pair, in Amecameca the superior partner was CU and in Tulancingo TL. In Zirahuén two dominant pairs form the constitution they are SC-OA and CU-TL been the former superior. In all cases sporadic increases of some of inversions were observed. No directional changes were observed. The cyclic pattern is show within periods of 4-5 years

Inversion clines in natural populations of Drosophila pseudoobscura from Mexico

Chromosomal polymorphism in natural populations of Drosophila pseudoobscura have been broadly studied in the USA but scarcely in Mexico where only about 60 localities have been analyzed. Differences among both regions are notorious with respect to their chromosomal constitution. Northern populations, those of USA, have as representative inversions the sequences ST, AR and CH contrasting with those in Southern populations (Mexico) in which prevail the gene arrangements TL, CU and SC. Assuming as a probable mechanism that has allowed these substitutions the flow generated by the presence of a North - South clines, we took as a goal find out if such clines really exist. With that objective in mind we studied 29 populations of this species distributed along four North - South transects. Specimens of D. pseudoobscura caught by attracting them with fermenting bananas were carried to the laboratory where from each female an isofemale line was established. When their offspring appeared a single larva from each isofemale was taken, its salivary glands extracted and stained with a solution of lacto- aceto- orcein, by these means the polytene chromosomes were obtained. On these chromosomes we identified, for each larva, the inversion (s) carried in the third chromosome, in such a way 3439 third chromosomes were analyzed. Among the 29 localities we identified 17 different inversions but the number of them varied from population to population from three to eleven. Relative frequencies of each inversion at every location were calculated and with them for each transect the presence or absence of clines was determined. Among each transect the existence of clines was observed only between two or three near by populations, but we were not able to find a clear manifestation of the presence of clines along a complete transect. Our results at this respect are similar to those previously reported for USA populations. A mechanism that explains North - South substitutions of predominant inversions remains as open question

Can patterns of chromosome inversions in Drosophila pseudoobscura predict polyandry across a geographical cline?

Journal ArticleFemale multiple mating, known as polyandry, is ubiquitous and occurs in a wide variety of taxa. Polyandry varies greatly from species in which females mate with one or two males in their lifetime to species in which females may mate with several different males on the same day. As multiple mating by females is associated with costs, numerous hypotheses attempt to explain this phenomenon. One hypothesis not extensively explored is the possibility that polyandrous behavior is captured and "fixed" in populations via genetic processes that preserve the behavior independently of any adaptive benefit of polyandry. Here, we use female isolines derived from populations of Drosophila pseudoobscura from three locations in North America to examine whether different female remating levels are associated with patterns of chromosome inversions, which may explain patterns of polyandry across the geographic range. Populations differed with respect to the frequency of polyandry and the presence of inversion polymorphisms on the third chromosome. The population with the lowest level of female remating was the only one that was entirely comprised of homokaryotypic lines, but the small number of populations prevented us investigating this relationship further at a population level. However, we found no strong relationship between female remating levels and specific karyotypes of the various isolines.NER

Chromatographic separation and identification of some peptides in partial hydroylsates of gelatin

Recently we have been engaged in a study of the chemical structure of collagen and gelatin with the object of determining the sequence of the amino acid residues in the polypeptide chains of these proteins. In the course of this study we have made considerable progress in the chromatographic analysis of complex mixtures of peptides and we have isolated and identified several simple peptides which occur in partial hydrolysates of gelatin. The initial separation of the mixture into zones of one or more peptides has been made on a column of ion exchange resin; further separation of the peptides in each zone has been achieved by chromatographing in the form of dinitrophenyl (DNP) peptides on columns of silicic acid-Celite. It is to be hoped that the particular combination of chromatographic methods which has been successfully used in the present study will be helpful in the resolution of the complex mixtures which result from the partial hydrolysis of other proteins