Genetic variation and structural diversity in major seed proteins among and within Camelina species

Genetic variation in seed protein composition, seed protein gene expression and predictions of seed protein physiochemical properties were documented in C. sativa and other Camelina species. Seed protein diversity was examined in six Camelina species (C. hispida, C. laxa, C. microcarpa, C. neglecta, C. rumelica and C. sativa). Differences were observed in seed protein electrophoretic profiles, total seed protein content and amino acid composition between the species. Genes encoding major seed proteins (cruciferins, napins, oleosins and vicilins) were catalogued for C. sativa and RNA-Seq analysis established the expression patterns of these and other genes in developing seed from anthesis through to maturation. Examination of 187 C. sativa accessions revealed limited variation in seed protein electrophoretic profiles, though sufficient to group the majority into classes based on high MW protein profiles corresponding to the cruciferin region. C. sativa possessed four distinct types of cruciferins, named CsCRA, CsCRB, CsCRC and CsCRD, which corresponded to orthologues in Arabidopsis thaliana with members of each type encoded by homeologous genes on the three C. sativa sub-genomes. Total protein content and amino acid composition varied only slightly; however, RNA-Seq analysis revealed that CsCRA and CsCRB genes contributed > 95% of the cruciferin transcripts in most lines, whereas CsCRC genes were the most highly expressed cruciferin genes in others, including the type cultivar DH55. This was confirmed by proteomics analyses. Cruciferin is the most abundant seed protein and contributes the most to functionality. Modelling of the C. sativa cruciferins indicated that each type possesses different physiochemical attributes that were predicted to impart unique functional properties. As such, opportunities exist to create C. sativa cultivars with seed protein profiles tailored to specific technical applications.

A journey into the world of insect lipid metabolism

Lipid metabolism is fundamental to life. In insects, it is critical, during reproduction, flight, starvation, and diapause. The coordination center for insect lipid metabolism is the fat body, which is analogous to the vertebrate adipose tissue and liver. Fat body contains various different cell types; however, adipocytes and oenocytes are the primary cells related to lipid metabolism. Lipid metabolism starts with the hydrolysis of dietary lipids, absorption of lipid monomers, followed by lipid transport from midgut to the fat body, lipogenesis or lipolysis in the fat body, and lipid transport from fat body to other sites demanding energy. Lipid metabolism is under the control of hormones, transcription factors, secondary messengers and posttranscriptional modifications. Primarily, lipogenesis is under the control of insulin-like peptides that activate lipogenic transcription factors, such as sterol regulatory element-binding proteins, whereas lipolysis is coordinated by the adipokinetic hormone that activates lipolytic transcription factors, such as forkhead box class O and cAMP-response element-binding protein. Calcium is the primary-secondary messenger affecting lipid metabolism and has different outcomes depending on the site of lipogenesis or lipolysis. Phosphorylation is central to lipid metabolism and multiple phosphorylases are involved in lipid accumulation or hydrolysis. Although most of the knowledge of insect lipid metabolism comes from the studies on the model Drosophila; other insects, in particular those with obligatory or facultative diapause, also have great potential to study lipid metabolism. The use of these models would significantly improve our knowledge of insect lipid metabolism.

The complete genome sequence of the phytopathogenic fungus Sclerotinia sclerotiorum reveals insights into the genome architecture of broad host range pathogens

Sclerotinia sclerotiorum is a phytopathogenic fungus with over 400 hosts including numerous economically important cultivated species. This contrasts many economically destructive pathogens that only exhibit a single or very few hosts. Many plant pathogens exhibit a “two-speed” genome. So described because their genomes contain alternating gene rich, repeat sparse and gene poor, repeat-rich regions. In fungi, the repeat-rich regions may be subjected to a process termed repeat-induced point mutation (RIP). Both repeat activity and RIP are thought to play a significant role in evolution of secreted virulence proteins, termed effectors. We present a complete genome sequence of S. sclerotiorum generated using Single Molecule Real-Time Sequencing technology with highly accurate annotations produced using an extensive RNA sequencing data set. We identified 70 effector candidates and have highlighted their in planta expression profiles. Furthermore, we characterized the genome architecture of S. sclerotiorum in comparison to plant pathogens that exhibit “two-speed” genomes. We show that there is a significant association between positions of secreted proteins and regions with a high RIP index in S. sclerotiorum but we did not detect a correlation between secreted protein proportion and GC content. Neither did we detect a negative correlation between CDS content and secreted protein proportion across the S. sclerotiorum genome. We conclude that S. sclerotiorum exhibits subtle signatures of enhanced mutation of secreted proteins in specific genomic compartments as a result of transposition and RIP activity. However, these signatures are not observable at the whole-genome scale.

Hairy Canola (Brasssica napus) re-visited: Down-regulating TTG1 in an AtGL3-enhanced hairy leaf background improves growth, leaf trichome coverage, and metabolite gene expression diversity

BACKGROUND

Through evolution, some plants have developed natural resistance to insects by having hairs (trichomes) on leaves and other tissues. The hairy trait has been neglected in Brassica breeding programs, which mainly focus on disease resistance, yield, and overall crop productivity. In Arabidopsis, a network of three classes of proteins consisting of TTG1 (a WD40 repeat protein), GL3 (a bHLH factor) and GL1 (a MYB transcription factor), activates trichome initiation and patterning. Introduction of a trichome regulatory gene AtGL3 from Arabidopsis into semi-glabrous Brassica napus resulted in hairy canola plants which showed tolerance to flea beetles and diamondback moths; however plant growth was negatively affected. In addition, the role of BnTTG1 transcription in the new germplasm was not understood.

RESULTS

Here, we show that two ultra-hairy lines (K-5-8 and K-6-3) with BnTTG1 knock-down in the hairy AtGL3+ B. napus background showed stable enhancement of trichome coverage, density, and length and restored wild type growth similar to growth of the semi-glabrous Westar plant. In contrast, over-expression of BnTTG1 in the hairy AtGL3+ B. napus background gave consistently glabrous plants of very low fertility and poor stability, with only one glabrous plant (O-3-7) surviving to the T3 generation. Q-PCR trichome gene expression data in leaf samples combining several leaf stages for these lines suggested that BnGL2 controlled B. napus trichome length and out-growth and that strong BnTTG1 transcription together with strong GL3 expression inhibited this process. Weak expression of BnTRY in both glabrous and trichome-bearing leaves of B. napus in the latter Q-PCR experiment suggested that TRY may have functions other than as an inhibitor of trichome initiation in the Brassicas. A role for BnTTG1 in the lateral inhibition of trichome formation in neighbouring cells was also proposed for B. napus. RNA sequencing of first leaves identified a much larger array of genes with altered expression patterns in the K-5-8 line compared to the hairy AtGL3(+) B. napus background (relative to the Westar control plant). These genes particularly included transcription factors, protein degradation and modification genes, but also included pathways that coded for anthocyanins, flavonols, terpenes, glucosinolates, alkaloids, shikimates, cell wall biosynthesis, and hormones. A 2nd Q-PCR experiment was conducted on redox, cell wall carbohydrate, lignin, and trichome genes using young first leaves, including T4 O-3-7-5 plants that had partially reverted to yield two linked growth and trichome phenotypes. Most of the trichome genes tested showed to be consistant with leaf trichome phenotypes and with RNA sequencing data in three of the lines. Two redox genes showed highest overall expression in K-5-8 leaves and lowest in O-3-7-5 leaves, while one redox gene and three cell wall genes were consistently higher in the two less robust lines compared with the two robust lines.

CONCLUSION

The data support the strong impact of BnTTG1 knockdown (in the presence of strong AtGL3 expression) at restoring growth, enhancing trichome coverage and length, and enhancing expression and diversity of growth, metabolic, and anti-oxidant genes important for stress tolerance and plant health in B. napus. Our data also suggests that the combination of strong (up-regulated) BnTTG1 expression in concert with strong AtGL3 expression is unstable and lethal to the plant.

Brassica villosa, a system for studying non-glandular trichomes and genes in the Brassicas

Brassica villosa is a wild Brassica C genome species with very dense trichome coverage and strong resistance to many insect pests of Brassica oilseeds and vegetables. Transcriptome analysis of hairy B. villosa leaves indicated higher expression of several important trichome initiation genes compared with glabrous B. napus leaves and consistent with the Arabidopsis model of trichome development. However, transcripts of the TRY inhibitory gene in hairy B. villosa were surprisingly high relative to B. napus and relative transcript levels of SAD2, EGL3, and several XIX genes were low, suggesting potential ancillary or less important trichome-related roles for these genes in Brassica species compared with Arabidopsis. Several antioxidant, calcium, non-calcium metal and secondary metabolite genes also showed differential expression between these two species. These coincided with accumulation of two alkaloid-like compounds, high levels of calcium, and other metals in B. villosa trichomes that are correlated with the known tolerance of B. villosa to high salt and the calcium-rich natural habitat of this wild species. This first time report on the isolation of large amounts of pure B. villosa trichomes, on trichome content, and on relative gene expression differences in an exceptionally hairy Brassica species compared with a glabrous species opens doors for the scientific community to understand trichome gene function in the Brassicas and highlights the potential of B. villosa as a trichome research platform.

Analysis of expressed sequence tags in Brassica napus cotyledons damaged by crucifer flea beetle feeding

The molecular basis of canola ( Brassica napus L.) susceptibility to the crucifer flea beetle (FB, Phyllotreta cruciferae Goeze) was investigated by comparing transcript representation in FB-damaged and undamaged cotyledons. The B. napus cotyledon transcriptome increased and diversified substantially after FB feeding damage. Twenty-two genes encoding proteins with unknown function, six encoding proteins involved in signaling, and a gene encoding a B-box zinc finger transcription factor were moderately or strongly changed in representation with FB feeding damage. Zinc finger and calcium-dependent genes formed the largest portion of transcription factors and signaling factors with changes in representation. Six genes with unknown function, one transcription factor, and one signaling gene specific to the FB-damaged library were co-represented in a FB-damaged leaf library. Out of 188 transcription factor and signaling gene families screened for "early" expression changes, 16 showed changes in expression within 8 h. Four of these early factors were zinc finger genes with representation only in the FB-damaged cotyledon. These genes are now available to test their potential at initiating or specifying cotyledon responses to crucifer FB feeding.

De novo sequence assembly of Albugo candida reveals a small genome relative to other biotrophic oomycetes

Background

Albugo candida is a biotrophic oomycete that parasitizes various species of Brassicaceae, causing a disease (white blister rust) with remarkable convergence in behaviour to unrelated rusts of basidiomycete fungi.

Results

A recent genome analysis of the oomycete Hyaloperonospora arabidopsidis suggests that a reduction in the number of genes encoding secreted pathogenicity proteins, enzymes for assimilation of inorganic nitrogen and sulphur represent a genomic signature for the evolution of obligate biotrophy. Here, we report a draft reference genome of a major crop pathogen Albugo candida (another obligate biotrophic oomycete) with an estimated genome of 45.3 Mb. This is very similar to the genome size of a necrotrophic oomycete Pythium ultimum (43 Mb) but less than half that of H. arabidopsidis (99 Mb). Sequencing of A. candida transcripts from infected host tissue and zoosporangia combined with genome-wide annotation revealed 15,824 predicted genes. Most of the predicted genes lack significant similarity with sequences from other oomycetes. Most intriguingly, A. candida appears to have a much smaller repertoire of pathogenicity-related proteins than H. arabidopsidis including genes that encode RXLR effector proteins, CRINKLER-like genes, and elicitins. Necrosis and Ethylene inducing Peptides were not detected in the genome of A. candida. Putative orthologs of tat-C, a component of the twin arginine translocase system, were identified from multiple oomycete genera along with proteins containing putative tat-secretion signal peptides.

Conclusion

Albugo candida has a comparatively small genome amongst oomycetes, retains motility of sporangial inoculum, and harbours a much smaller repertoire of candidate effectors than was recently reported for H. arabidopsidis. This minimal gene repertoire could indicate a lack of expansion, rather than a reduction, in the number of genes that signify the evolution of biotrophy in oomycetes.

Patterns of differential gene expression in Brassica napus cultivars infected with Sclerotinia sclerotiorum

SUMMARY The fungal pathogen Sclerotinia sclerotiorum infects a broad range of dicotyledonous plant species and causes stem rot in Brassica napus. To elucidate the mechanisms underlying the defence response, the patterns of gene expression in the partially resistant B. napus cultivar ZhongYou 821 (ZY821) and the susceptible cultivar Westar were studied using a B. napus oligonucleotide microarray. Although maximum differential gene expression was observed at 48 h post-inoculation (hpi) in both cultivars, increased transcript levels were detected in cv. ZY821 at the earlier stages of infection (6-12 hpi) for many genes, including those encoding defence-associated proteins, such as chitinases, glucanases, osmotins and lectins, as well as genes encoding transcription factors belonging to the zinc finger, WRKY, APETALA2 (AP2) and MYB classes. In both cultivars, genes encoding enzymes involved in jasmonic acid, ethylene and auxin synthesis were induced, as were those for gibberellin degradation. In addition, changes in the expression of genes encoding enzymes involved in carbohydrate and energy metabolism appeared to be directed towards shuttling carbon reserves to the tricarboxylic acid cycle and generating reactive oxygen species. Transcripts from genes encoding enzymes involved in glucosinolate and phenylpropanoid biosynthesis were highly elevated in both cultivars, suggesting that secondary metabolites are also components of the response to S. sclerotiorum in B. napus.

Differential expression of duplicated peroxidase genes in the allotetraploid Brassica napus

Gene redundancy due to polyploidization provides a selective advantage for plant adaptation. We examined the expression patterns of two peroxidase genes (BnPOX1 and BnPOX2) in the natural allotetraploid Brassica napus and the model diploid progenitors Brassica rapa (Br) and Brassica oleracea (Bo) in response to the fungal pathogen Sclerotinia sclerotiorum. We demonstrated that the Bo homeolog of BnPOX1 was up-regulated after infection, while both BnPOX2 homeologs were down-regulated. A bias toward reciprocal expression of the homeologs of BnPOX1 in different organs in the natural allotetraploid of B. napus was also observed. These results suggest that subfunctionalization of the duplicated BnPOX genes after B. napus polyploidization as well as subneofunctionalization of the homeologs in response to this specific biotic stress has occurred. Retention of expression patterns in the diploid progenitors and the natural allotetraploid in some organs indicates that the function of peroxidase genes has been conserved during evolution.

New insights into peritrophic matrix synthesis, architecture, and function

The peritrophic matrix (PM) is a chitin and glycoprotein layer that lines the invertebrate midgut. Although structurally different, it is functionally similar to the mucous secretions of the vertebrate digestive tract. The PM is a physical barrier, protecting the midgut epithelium from abrasive food particles, digestive enzymes, and pathogens infectious per os. It is also a biochemical barrier, sequestering and, in some cases, inactivating ingested toxins. Finally, the PM compartmentalizes digestive processes, allowing for efficient nutrient acquisition and reuse of hydrolytic enzymes. The PM consists of an organized lattice of chitin fibrils held together by chitin binding proteins. Glycans fill the interstitial spaces, creating a molecular sieve, the properties of which are dependent on the immediate ion content and pH. In this review, we have integrated recent structural and functional information to create a holistic model for the PM. We also show how this information may generate novel technologies for use in insect pest management.

First Report of "Candidatus Phytoplasma asteris"-Related Strains in Brassica rapa in Saskatchewan, Canada

"Candidatus phytoplasma asteris" and related strains (i.e., aster yellows group 16SrI) have been associated with diseases of numerous plant species worldwide. Symptoms of aster yellows (AY) have been reported on rapeseed/canola (Brassica napus and B. rapa) crops in Saskatchewan (SK) and Manitoba, Canada since 1953 (2). Symptoms generally include stunting, virescence, leaf yellowing or purpling, phyllody, and formation of bladder-like siliques. A total of 120 mature B. rapa cv. AC Sunbeam plants exhibiting AY symptoms were collected in commercial fields near Medstead, SK during 2003 and 2004 (one field per year). As described previously (4), total genomic DNA was extracted from leaf, stem, roots, and seeds collected from the 120 plants, from seeds from the seed lots sown in 2003 and 2004, and from leaf and stem tissue of 20 greenhouse-grown plants from each seed lot. The latter DNA samples were assayed for phytoplasma DNA by a nested polymerase chain reaction (PCR) assay incorporating phytoplasma universal 16S rRNA primer pairs P1/P6 (1) followed by R16R2/R16F2 (4). Seed samples analyzed from the 2003 and 2004 seed lots and tissues of the 40 greenhouse-grown plants all tested negative for phytoplasma DNA using this assay. Leaf, stem, and/or root tissues of all plants collected in the field in 2003 (60 plants) and 2004 (60 plants) and 71.1% (315 of 443) of seed samples (five seeds per sample) tested positive for the presence of phytoplasma DNA, as evidenced by the presence of an expected band of 1.2 kb on the gels after the second amplification with primers R16R2/R16F2. Nested PCR products from plant samples collected in 2003 were cloned, sequenced, and compared with phytoplasma sequences archived in the GenBank nucleotide database. On this basis, phytoplasmas detected in plants or their seeds collected in 2003 were found to be most similar (98.8%) to CHRY (Accession No. AY180956), a 16SrI-A subgroup strain, or were most similar (98.9%) to isolate 99UW89 (Accession no. AF268407), a known 16SrI-B subgroup strain. Sequences of phytoplasmas detected in plants or their seeds in 2004 were obtained by direct sequencing of rRNA products amplified from samples using PCR incorporating primer pairs P1/P6 and P4/P7 (3). Analysis of sequence data revealed that phytoplasmas in these plants were all most similar (99.5%) to AY-WB (Accession no. AY389828), a 16SrI-A subgroup member. The nucleotide sequences have been deposited with GenBank under Accession nos. DQ404346, DQ404347, and DQ411470. To our knowledge, this is the first report of 16SrI-A and 16SrI-B subgroup phytoplasmas infecting plants and seed of B. rapa in Saskatchewan. References: (1) I.-M. Lee et al. Phytopathology, 83:834, 1993. (2) W. E. Sackston. Can. Plant Dis. Surv. 33:41, 1953. (3) L. B. Sharmila et al. J. Plant Biochem. Biotech. 13:1, 2004. (4) E. Tanne et al. Phytopathology, 91:741, 2001.

Characterization of the anti-fungal activity of a Bacillus spp. associated with sclerotia from Sclerotinia sclerotiorum

Sclerotinia sclerotiorum fruiting bodies (sclerotia) were found to harbour bacteria that possess anti-fungal activity. Among 1,140 bacterial isolates collected, 32 were found to inhibit the growth of four common fungal pathogens of canola, S. sclerotiorum, Rhizoctonia solani, Alternaria brassicae and Leptosphaeria maculans. One of these broad-spectrum isolates, LEV-006, was found to be closely related to Bacillus subtilis based on 16S rRNA analysis. The anti-fungal activities were purified and found to be associated with a low molecular weight peptide complex consisting mostly of the cyclic lipopeptide fengycin A and B, as revealed by matrix-assisted laser desorption/ionization time-of-flight and post-source decay analysis, as well as two proteins of 20 and 55 kDa. Peptide mass fingerprinting revealed that the 55-kDa protein was similar to vegetative catalase 1; however, when the enzyme was expressed in Escherichia coli, it exhibited catalase but not anti-fungal activity. The sequences of several peptides from the 20-kDa protein were obtained and indicated that it was a unique anti-fungal protein.

A method for the solvent extraction of low-boiling-point plant volatiles

A new method has been developed for the extraction of volatiles from plant materials and tested on seedling tissue and mature leaves of Arabidopsis thaliana, pine needles and commercial mixtures of plant volatiles. Volatiles were extracted with n-pentane and then subjected to quick distillation at a moderate temperature. Under these conditions, compounds such as pigments, waxes and non-volatile compounds remained undistilled, while short-chain volatile compounds were distilled into a receiving flask using a high-efficiency condenser. Removal of the n-pentane and concentration of the volatiles in the receiving flask was carried out using a Vigreux column condenser prior to GC-MS. The method is ideal for the rapid extraction of low-boiling-point volatiles from small amounts of plant material, such as is required when conducting metabolic profiling or defining biological properties of volatile components from large numbers of mutant lines.

Molecular characterization of Brassica napus NAC domain transcriptional activators induced in response to biotic and abiotic stress

Subtractive expressed sequence tag analysis and screening of cDNA libraries derived from Brassica napus leaves subjected to mechanical wounding, flea beetle feeding or cold temperatures revealed eight genes encoding NAC-domain transcription factors. The genes were found to be differentially regulated in response to biotic and abiotic stresses including wounding, insect feeding, Sclerotinia sclerotiorum infection, cold shock and dehydration. Five BnNAC proteins were orthologous to Arabidopsis thaliana ATAF1 or ATAF2 and gave rise to developmental abnormalities similar to the A. thaliana nam and cuc mutants when expressed ectopically in A. thaliana. Transgenic lines expressing BnNAC14, exhibited large leaves, thickened stems and hyper-developed lateral root systems similar to that observed with A. thaliana NAC1, but also were delayed in bolting and lacked an apical dominant tap root. Several of the BnNAC proteins were capable of activating gene expression in yeast and recognized an element within the CaMV35S promoter. A yeast two-hybrid screen revealed that BnNAC14 interacted with other select BnNAC proteins in vitro and identified an additional BnNAC gene, BnNAC485. The protein interaction and transcriptional activation domains were mapped by deletion analysis.

Characterization of an intestinal mucin from the peritrophic matrix of the diamondback moth, Plutella xylostella

The peritrophic matrix (PM) of Plutella xylostella larvae was found to contain twelve integral and eighteen loosely associated proteins. An antiserum against Mamestra configurata integral PM proteins cross-reacted with several P. xylostella PM proteins and was used to isolate a partial cDNA encoding an insect intestinal mucin (PxIIM). PxIIM was expressed primarily in the larval midgut. The deduced protein sequence of the partial cDNA contained three potentially glycosylated, mucin-like domains and six cysteine-rich chitin-binding domains (CBDs). An additional chitin-binding domain was proposed to reside at the amino terminus of the protein based on comparison with other IIM. The organization of mucin domains and CBDs exhibited features, including an internal triplet of regularly spaced CBDs and a carboxyl terminal CBD with two additional conserved cysteine residues, that were found to be common to other lepidopteran IIMs.

Midgut proteases from Mamestra configurata (Lepidoptera: Noctuidae) larvae: characterization, cDNA cloning, and expressed sequence tag analysis

The activities of digestive protease within the midgut of Mamestra configurata (bertha armyworm) larvae were examined using specific substrates and protease inhibitors. The bulk of the activity was associated with serine proteases comprising trypsin-, chymotrypsin-, and elastase-like enzymes. At least 10-15 serine protease isozymes were detected using one-dimension gelatin gel electrophoresis. Cysteine or aspartic protease activities were not present; however, amino- and carboxypeptidase activities were associated with the midgut extract. Midgut proteases were active in the pH range of 5.0-12.0 with peaks at pH 7.5 and 11.0. In general, the middle region of the midgut exhibited a higher pH (approximately 8.0) than either the posterior or anterior regions (approximately 7.3-7.7). Moulting larvae possessed a neutral gut pH that was 0.5-1.5 units below that of feeding larvae. Degenerate PCR and expressed sequence tag (EST)-based approaches were used to isolate 30 distinct serine protease encoding cDNAs from a midgut-specific cDNA library including 8 putative trypsins, 9 chymotrypsins, 1 elastase, and 12 whose potential activities could not be determined. cDNAs encoding three amino- and two carboxypeptidases were also identified. Larvae feeding upon artificial diet containing 0.2% soybean trypsin inhibitor experienced a significant delay in development.

Optimal conditions for the expression of a single-chain antibody (scFv) gene in Pichia pastoris

A Pichia pastoris system was used to express a single-chain antibody (scFv) targeted against Mamestra configurata (bertha armyworm) serpins. To improve scFv production we examined parameters such as proteinase activity, temperature, cell density, osmotic stress, medium composition, pH, and reiterative induction. P. pastoris was found to express several proteases; however, adjustment of medium pH to limit their activity did not correlate with increased scFv recovery. Induction medium pH values of 6.5-8.0 were most conducive to scFv production, despite significant differences in cell growth rates. Increasing inoculum density limited growth potential but gave rise to higher levels of scFv production. Three factors, medium composition, pre-induction osmotic stress, and temperature, had the greatest effects on protein production. Supplementation of the induction medium with arganine, casamino acids, or EDTA increased scFv production several fold, as did cultivation under osmotic stress conditions during pre-induction biomass accumulation. Incubation at 15 versus 30 degrees C extended the period whereby cells were capable of producing scFv from 1 to 7 days. Under optimal conditions, yeast cultures yielded 25 mg/L of functional scFv and could be subject to five reiterative inductions.

Decreased bone density, elevated serum osteoprotegerin, and beta-cross-laps in Wilson disease

Osteopathia has been reported in Wilson disease (WD), but bone density has not been measured; therefore, we performed bone mineral density (BMD), bone mineral content (BMC), and quantitative bone ultrasound (QUS) assessments, as well as measured the serum levels of osteocalcin (OCN), beta-cross-laps (beta-CTx's), and the recently discovered osteoprotegerin (OPG) and its ligand RANKL to investigate the underlying mechanism of osseous disorders. Serum OCN, beta-CTx, OPG, and RANKL levels were measured by ELISA in 21 WD patients and in 20 age- and gender-matched healthy subjects. BMD, BMC, and QUS parameters were also determined. Osteoporosis was present in 9/21 (43%) WD patients. Abnormal QUS parameters were found in 7 (33%) of the patients. Although serum OCN levels were similar in patients and controls (29.93 +/- 24.65 mg/ml vs. 29.84 +/- 6.89 mg/ml), beta-CTx and OPG levels were significantly increased in WD compared with the healthy controls (625.4 +/- 312.3 pg/ml vs. 423.6 +/- 144.3 pg/ml and p = 0.022 and 7.2 +/- 3.4 pM vs. 3.5 +/- 1.0 pM and p < 0.001, respectively). No difference was observed in the RANKL level. There was a positive correlation between OCN and beta-CTx (r = 0.55; p = 0.01). We proved high occurrence of osteoporosis in WD. Negative bone remodeling balance is a consequence of increased bone resorption, which is indicated by elevated beta-CTx. The novel finding of elevated serum OPG may reflect a compensatory reaction to enhanced osteoclast activity, despite the normal OCN level.

Changes in cysteine protease activity and localization during midgut metamorphosis in the crucifer root maggot (Delia radicum)

We show that differential localization and/or activation of two cysteine protease activities occur at the onset of dipteran midgut metamorphosis. A 26 kDa cysteine protease activity was associated specifically with midgut tissues of late third instar larvae. Starvation of mid third instar larvae simulated the onset of prepupation and resulted in loss of the 26 kDa protease activity. A cDNA clone encoding a cysteine protease, termed DrCP1, was isolated and shown to be highly similar to those from Sarcophaga peregrina and Drosophila melanogaster (DmCP1). DrCP1 mRNA was present in all developmental stages including eggs, larvae, pupae and adults, but was highly induced at the onset of the larval-pupal transition and thereafter. The DrCP1 protein is localized to the exterior of the midgut tissues during the onset of the prepupal transition period, possibly in response to ecdysone. Analysis of transcription factor binding sites associated with the DmCP1 promoter indicated that elements exist that allow for both ecdysone-mediated as well as tissue-specific regulation. Based upon these and other studies we propose: (1) that the expression, activity and localization of the DrCP1-like cysteine proteases are highly regulated throughout development; and, (2) that cysteine protease activities are involved in aspects of tissue reconstruction at the onset of and during metamorphosis.

Analysis of an insect neuropeptide, Schistocerca gregaria ion transport peptide (ITP), expressed in insect cell systems

We have produced an active form of Schistocerca gregaria ion transport peptide (ITP) in an insect cell expression system. Transformed Drosophila Kc1 cells secreted a form of ITP into the cell culture medium that was proteolytically cleaved correctly at the amino (N)-terminus. Concentrated culture supernatant from transformed Kc1 and Hi5 cells had high biological activity when tested on isolated locust ilea. Conversely, ITP expressed by baculovirus-infected Sf9 cells was larger in size and had decreased specific activity compared to ITP produced by Kc1 cells due to incorrect cleavage of the peptide at the N-terminus in the baculovirus system. This demonstrates how processing of the secreted foreign protein (ITP) expressed under the late polyhedrin promoter is compromised in a baculovirus-infected cell. Transient transformation of Kc1 cells results in supernatants containing two forms of ITP; one form (A) co-elutes with synthetic ITP and the other form (B) has reduced electrophoretic mobility. In contrast, in stably transformed Kc1 cell supernatant, ITP is expressed in a single form, which has the same electrophoretic mobility and specific biological activity as form A produced by transiently transformed Kc1 cells. Arch.