Christopher Jagge - Academia.edu (original) (raw)

Uploads

Papers by Christopher Jagge

Fly, 2015

Arthropods employ a large family of up to 100 putative taste or gustatory receptors (Grs) for the... more Arthropods employ a large family of up to 100 putative taste or gustatory receptors (Grs) for the recognition of a wide range of non-volatile chemicals. In Drosophila melanogaster, a small subfamily of 8 Gr genes is thought to mediate the detection of sugars, the fly's major nutritional source. However, the specific roles for most sugar Gr genes are not known. Here, we report the generation of a series of mutant sugar Gr knock-in alleles and several composite sugar Gr mutant strains, including a sugar blind strain, which will facilitate the characterization of this gene family. Using Ca 2C imaging experiments, we show that most gustatory receptor neurons (GRNs) of sugar blind flies (lacking all 8 sugar Gr genes) fail to respond to any sugar tested. Moreover, expression of single sugar Gr genes in most sweet GRNs of sugarblind flies does not restore sugar responses. However, when pair-wise combinations of sugar Gr genes are introduced to sweet GRNs, responses to select sugars are restored. We also examined the cellular phenotype of flies homozygous mutant for Gr64a, a Gr gene previously reported to be a major contributor for the detection of many sugars. In contrast to these claims, we find that sweet GRNs of Gr64a homozygous mutant flies show normal responses to most sugars, and only modestly reduced responses to maltose and maltotriose. Thus, the precisely engineered genetic mutations of single Gr genes and construction of a sugar-blind strain provide powerful analytical tools for examining the roles of Drosophila and other insect sugar Gr genes in sweet taste.

Current biology : CB, Jan 2, 2015

Identification of nutritious compounds is dependent on expression of specific taste receptors in ... more Identification of nutritious compounds is dependent on expression of specific taste receptors in appropriate taste-cell types [1]. In contrast to mammals, which rely on a single, broadly tuned heterodimeric sugar receptor [2], the Drosophila genome harbors a small subfamily of eight, closely related gustatory receptor (Gr) genes, Gr5a, Gr61a, and Gr64a-Gr64f, of which three have been proposed to mediate sweet taste [3-6]. However, expression and function of several of these putative sugar Gr genes are not known. Here, we present a comprehensive expression and functional analysis using Gr(LEXA/GAL4) alleles that were generated through homologous recombination. We show that sugar Gr genes are expressed in a combinatorial manner to yield at least eight sets of sweet-sensing neurons. Behavioral investigations show that most sugar Gr mutations affect taste responses to only a small number of sugars and that effective detection of most sugars is dependent on more than one Gr gene. Surpris...

Phytoparasitica, 2008

An extensive survey of Bemisia tabaci populations covering the southern half of the island of Cyp... more An extensive survey of Bemisia tabaci populations covering the southern half of the island of Cyprus was conducted in 2006 and 2007 in order to define the biotype status of the pest. Sampling was done both on protected and outdoor cultivations of vegetables and ornamental plants. Biotype identification was performed using molecular diagnostics based on the mitochondrial cytochrome oxydase I gene. Our results indicated the presence of only the biotype B in all 25 collections.

Insect Molecular Biology, 2008

In the mosquito Aedes aegypti (L.), the molecular endocrine mechanisms underlying rapid water eli... more In the mosquito Aedes aegypti (L.), the molecular endocrine mechanisms underlying rapid water elimination upon eclosion and blood feeding are not fully understood. The genome contains a single predicted diuretic hormone 44 (DH 44 ) gene, but two DH 44 receptor genes. The identity of the DH 44 receptor(s) in the Malpighian tubule is unknown in any mosquito species. We show that VectorBase gene ID AAEL008292 encodes the DH 44 receptor (GPRDIH1) most highly expressed in Malpighian tubules. Sequence analysis and transcript localization indicate that AaegGPRDIH1 is the coorthologue of the Drosophila melanogaster DH 44 receptor (CG12370-PA). Time-course quantitative PCR analysis of Malpighian tubule cDNA revealed AaegGPRDIH1 expression changes paralleling periods of excretion. This suggests that target tissue receptor biology is linked to the known periods of release of diuretic hormones from the nervous system pointing to a common up-stream regulatory mechanism. Figure 2. (A) Open reading frame (ORF) alignment of dipteran DH 44 receptors: Aedes aegypti GPRDIH1 (EU273351) and GPRDIH2 (EU273352); Culex quinquefasciatus GPRDIH1 (BK006347) and GPRDIH2 (BK006348); Anopheles gambiae GPRDIH1 (AGAP005464-PA) and GPRDIH2 (AGAP005465-PA); Drosophila melanogaster CG12370-PA and CG8422-PA. Sequence identifiers are to the left (longer taxon abbreviations are for clarity) and ORF residue positions are to the right of the alignment. Regions of amino acid identity among the sequences are shaded in black. BLAST analysis shows Ae. aegypti GPRDIH1 is 70.2% identical to C. quinquefasciatus GPRDIH1, 69.1% identical to An. gambiae GPRDIH1, 54.8% identical to the D. melanogaster CG12370 receptor and 63.2% identical to the CG8422 receptor. Culex and Anopheles GPRDIH2 sequence predictions are missing ~26 amino acid residues corresponding to portions of transmembrane region IV and extracellular loop III, indicated by 'X' residues in the Culex GPRDIH2 sequence at positions 237 and 238. (B) Alignment of C-terminal sequences from predicted and cloned Diptera DH 44 receptors. Three motifs are indicated (I, II, III). These motifs suggest Ae. aegypti GPRDIH1 and the Drosophila DH 44 receptor (CG12370-PA) are co-orthologues.

Insect Molecular Biology, 2005

A cDNA cloned from Aedes aegypti (L.) (Aedae) female Malpighian tubule (AY596453) encodes a 584 a... more A cDNA cloned from Aedes aegypti (L.) (Aedae) female Malpighian tubule (AY596453) encodes a 584 amino acid residue protein (65.2 kDa) predicted as a G proteincoupled receptor and orthologue of the drosokinin receptor from Drosophila melanogaster and highly similar to the tick Boophilus microplus myokinin receptor (AF228521). Based on the similarity to this Aedes sequence, we also propose a correction for the Anopheles gambiae protein sequence EAA05450. When expressed in CHO-K1 cells, the Aedes receptor behaved as a multiligand receptor and functionally responded to concentrations ≥ ≥ ≥ ≥ 1 n M of Aedae kinins 1-3, respectively, as determined by a calcium bioluminescence plate assay and single cell intracellular calcium measurements by confocal fluorescence cytometry. Estimates of EC 50 values by the plate assay were 16.04 n M for Aedae-K-3, 26.6 n M for Aedae-K-2 and 48.8 n M for Aedae-K-1 and were statistically significantly different. These results suggest that the observed differences in physiological responses to the three Aedes kinins in the Aedes isolated Malpighian tubule reported elsewhere could now be explained by differences in intracellular signalling events triggered by the different peptides on the same receptor and not necessarily due to the existence of various receptors for the three Aedes kinins.

Insect Molecular Biology, 2001

In the mosquito Aedes aegypti , 5-HT changes the endogenous rhythm of contractions in the female ... more In the mosquito Aedes aegypti , 5-HT changes the endogenous rhythm of contractions in the female hindgut and increases fluid secretion in the larval Malpighian tubule. The role of 5-HT as a diuretic hormone in adults has been questioned. We cloned a cDNA encoding a serotonin receptor from a female A. aegypti Malpighian tubule library that is similar to the 5-HT7 receptor from Drosophila melanogaster . The transcript was localized in the tracheolar cells associated with the female Malpighian tubules but no signal was detectable in the tubule epithelium. Immunohistochemistry with specific antibodies confirmed the receptor expression in tracheolar cells and hindgut, and western blots of these tissues showed the expected 50 kDa band. The results suggest a role for serotonin in respiration and that this receptor may coordinate the tubule-hindgut response to serotonin during diuresis.

Insect Molecular Biology, 2000

A cDNA encoding a putative water channel protein, aquaporin, was cloned from a cDNA library of Ae... more A cDNA encoding a putative water channel protein, aquaporin, was cloned from a cDNA library of Aedes aegypti Malpighian tubules. The cDNA encodes a 26.11 kDa protein similar to insect aquaporins from Haematobia irritans exigua (Diptera) and Cicadella viridis (Homoptera), and to mammalian aquaporin 4. Localization of the messenger RNA (mRNA) was performed by in situ hybridization of Malpighian tubules and analysed by fluorescence and confocal microscopy. The mRNA was localized in tracheolar cells associated with the Malpighian tubules. No signal was detected in the Malpighian tubule epithelium. The molecular mechanisms for water movement between tissues and tracheoles are not yet elucidated in insects. Our results suggest a model to explain fluid movements in tracheoles during insect respiration.

Fly, 2015

Arthropods employ a large family of up to 100 putative taste or gustatory receptors (Grs) for the... more Arthropods employ a large family of up to 100 putative taste or gustatory receptors (Grs) for the recognition of a wide range of non-volatile chemicals. In Drosophila melanogaster, a small subfamily of 8 Gr genes is thought to mediate the detection of sugars, the fly's major nutritional source. However, the specific roles for most sugar Gr genes are not known. Here, we report the generation of a series of mutant sugar Gr knock-in alleles and several composite sugar Gr mutant strains, including a sugar blind strain, which will facilitate the characterization of this gene family. Using Ca 2C imaging experiments, we show that most gustatory receptor neurons (GRNs) of sugar blind flies (lacking all 8 sugar Gr genes) fail to respond to any sugar tested. Moreover, expression of single sugar Gr genes in most sweet GRNs of sugarblind flies does not restore sugar responses. However, when pair-wise combinations of sugar Gr genes are introduced to sweet GRNs, responses to select sugars are restored. We also examined the cellular phenotype of flies homozygous mutant for Gr64a, a Gr gene previously reported to be a major contributor for the detection of many sugars. In contrast to these claims, we find that sweet GRNs of Gr64a homozygous mutant flies show normal responses to most sugars, and only modestly reduced responses to maltose and maltotriose. Thus, the precisely engineered genetic mutations of single Gr genes and construction of a sugar-blind strain provide powerful analytical tools for examining the roles of Drosophila and other insect sugar Gr genes in sweet taste.

Current biology : CB, Jan 2, 2015

Identification of nutritious compounds is dependent on expression of specific taste receptors in ... more Identification of nutritious compounds is dependent on expression of specific taste receptors in appropriate taste-cell types [1]. In contrast to mammals, which rely on a single, broadly tuned heterodimeric sugar receptor [2], the Drosophila genome harbors a small subfamily of eight, closely related gustatory receptor (Gr) genes, Gr5a, Gr61a, and Gr64a-Gr64f, of which three have been proposed to mediate sweet taste [3-6]. However, expression and function of several of these putative sugar Gr genes are not known. Here, we present a comprehensive expression and functional analysis using Gr(LEXA/GAL4) alleles that were generated through homologous recombination. We show that sugar Gr genes are expressed in a combinatorial manner to yield at least eight sets of sweet-sensing neurons. Behavioral investigations show that most sugar Gr mutations affect taste responses to only a small number of sugars and that effective detection of most sugars is dependent on more than one Gr gene. Surpris...

Phytoparasitica, 2008

An extensive survey of Bemisia tabaci populations covering the southern half of the island of Cyp... more An extensive survey of Bemisia tabaci populations covering the southern half of the island of Cyprus was conducted in 2006 and 2007 in order to define the biotype status of the pest. Sampling was done both on protected and outdoor cultivations of vegetables and ornamental plants. Biotype identification was performed using molecular diagnostics based on the mitochondrial cytochrome oxydase I gene. Our results indicated the presence of only the biotype B in all 25 collections.

Insect Molecular Biology, 2008

In the mosquito Aedes aegypti (L.), the molecular endocrine mechanisms underlying rapid water eli... more In the mosquito Aedes aegypti (L.), the molecular endocrine mechanisms underlying rapid water elimination upon eclosion and blood feeding are not fully understood. The genome contains a single predicted diuretic hormone 44 (DH 44 ) gene, but two DH 44 receptor genes. The identity of the DH 44 receptor(s) in the Malpighian tubule is unknown in any mosquito species. We show that VectorBase gene ID AAEL008292 encodes the DH 44 receptor (GPRDIH1) most highly expressed in Malpighian tubules. Sequence analysis and transcript localization indicate that AaegGPRDIH1 is the coorthologue of the Drosophila melanogaster DH 44 receptor (CG12370-PA). Time-course quantitative PCR analysis of Malpighian tubule cDNA revealed AaegGPRDIH1 expression changes paralleling periods of excretion. This suggests that target tissue receptor biology is linked to the known periods of release of diuretic hormones from the nervous system pointing to a common up-stream regulatory mechanism. Figure 2. (A) Open reading frame (ORF) alignment of dipteran DH 44 receptors: Aedes aegypti GPRDIH1 (EU273351) and GPRDIH2 (EU273352); Culex quinquefasciatus GPRDIH1 (BK006347) and GPRDIH2 (BK006348); Anopheles gambiae GPRDIH1 (AGAP005464-PA) and GPRDIH2 (AGAP005465-PA); Drosophila melanogaster CG12370-PA and CG8422-PA. Sequence identifiers are to the left (longer taxon abbreviations are for clarity) and ORF residue positions are to the right of the alignment. Regions of amino acid identity among the sequences are shaded in black. BLAST analysis shows Ae. aegypti GPRDIH1 is 70.2% identical to C. quinquefasciatus GPRDIH1, 69.1% identical to An. gambiae GPRDIH1, 54.8% identical to the D. melanogaster CG12370 receptor and 63.2% identical to the CG8422 receptor. Culex and Anopheles GPRDIH2 sequence predictions are missing ~26 amino acid residues corresponding to portions of transmembrane region IV and extracellular loop III, indicated by 'X' residues in the Culex GPRDIH2 sequence at positions 237 and 238. (B) Alignment of C-terminal sequences from predicted and cloned Diptera DH 44 receptors. Three motifs are indicated (I, II, III). These motifs suggest Ae. aegypti GPRDIH1 and the Drosophila DH 44 receptor (CG12370-PA) are co-orthologues.

Insect Molecular Biology, 2005

A cDNA cloned from Aedes aegypti (L.) (Aedae) female Malpighian tubule (AY596453) encodes a 584 a... more A cDNA cloned from Aedes aegypti (L.) (Aedae) female Malpighian tubule (AY596453) encodes a 584 amino acid residue protein (65.2 kDa) predicted as a G proteincoupled receptor and orthologue of the drosokinin receptor from Drosophila melanogaster and highly similar to the tick Boophilus microplus myokinin receptor (AF228521). Based on the similarity to this Aedes sequence, we also propose a correction for the Anopheles gambiae protein sequence EAA05450. When expressed in CHO-K1 cells, the Aedes receptor behaved as a multiligand receptor and functionally responded to concentrations ≥ ≥ ≥ ≥ 1 n M of Aedae kinins 1-3, respectively, as determined by a calcium bioluminescence plate assay and single cell intracellular calcium measurements by confocal fluorescence cytometry. Estimates of EC 50 values by the plate assay were 16.04 n M for Aedae-K-3, 26.6 n M for Aedae-K-2 and 48.8 n M for Aedae-K-1 and were statistically significantly different. These results suggest that the observed differences in physiological responses to the three Aedes kinins in the Aedes isolated Malpighian tubule reported elsewhere could now be explained by differences in intracellular signalling events triggered by the different peptides on the same receptor and not necessarily due to the existence of various receptors for the three Aedes kinins.

Insect Molecular Biology, 2001

In the mosquito Aedes aegypti , 5-HT changes the endogenous rhythm of contractions in the female ... more In the mosquito Aedes aegypti , 5-HT changes the endogenous rhythm of contractions in the female hindgut and increases fluid secretion in the larval Malpighian tubule. The role of 5-HT as a diuretic hormone in adults has been questioned. We cloned a cDNA encoding a serotonin receptor from a female A. aegypti Malpighian tubule library that is similar to the 5-HT7 receptor from Drosophila melanogaster . The transcript was localized in the tracheolar cells associated with the female Malpighian tubules but no signal was detectable in the tubule epithelium. Immunohistochemistry with specific antibodies confirmed the receptor expression in tracheolar cells and hindgut, and western blots of these tissues showed the expected 50 kDa band. The results suggest a role for serotonin in respiration and that this receptor may coordinate the tubule-hindgut response to serotonin during diuresis.

Insect Molecular Biology, 2000

A cDNA encoding a putative water channel protein, aquaporin, was cloned from a cDNA library of Ae... more A cDNA encoding a putative water channel protein, aquaporin, was cloned from a cDNA library of Aedes aegypti Malpighian tubules. The cDNA encodes a 26.11 kDa protein similar to insect aquaporins from Haematobia irritans exigua (Diptera) and Cicadella viridis (Homoptera), and to mammalian aquaporin 4. Localization of the messenger RNA (mRNA) was performed by in situ hybridization of Malpighian tubules and analysed by fluorescence and confocal microscopy. The mRNA was localized in tracheolar cells associated with the Malpighian tubules. No signal was detected in the Malpighian tubule epithelium. The molecular mechanisms for water movement between tissues and tracheoles are not yet elucidated in insects. Our results suggest a model to explain fluid movements in tracheoles during insect respiration.