Characterization of an entomopoxvirus of the lesser cornstalk borer (Elasmopalpus lignosellus)

A biochemical and limited morphological characterization of an entomopoxvirus infecting the lesser cornstalk borer, Elasmopalpus lignosellus, was made. The oval virions measure 270 × 200 nm and the spheroids average 1.5 μm in diameter. Sodium dodecyl sulfate polyacrylamide gel electrophoresis elucidated 32 structural polypeptides with molecular weights ranging from 13,000 to 145,000. The viral genome was examined with the restriction endonuclease EcoRI. Gel electrophoresis of the digested DNA yielded 26 bands and a total molecular weight of 140.8 × 10⁶.     

Effect of crowding, food deprivation, and diet on flight initiation and lipid reserves of the lesser grain borer, Rhyzopertha dominica

Effects of crowding, food deprivation, and type of cereal diet upon flight initiation, development, body weight, lipid content, and fatty acid composition of the lesser grain borer, Rhyzopertha dominica (F.), were studied in two field strains and one laboratory strain. Beetles of all strains reared under crowded conditions had significantly higher flight initiation than beetles reared on isolated kernels (uncrowded). Regardless of degree of crowding, flight initiation increased with the period of food deprivation up to a maximum at 24 h, after which flight initiation declined. Body weight and lipid content decreased as the food deprivation period increased, whereas fatty acid composition was not significantly affected by food deprivation. Beetles from a field strain collected in 1995 had higher flight initiation and increased lipid content compared with beetles from the laboratory strain. However, beetles from the laboratory strain were larger, developed faster, and were more fecund than beetles from this field strain. The cereal diet on which beetles were reared also had a significant effect on flight initiation, lipid content, and fatty acid composition. Beetles reared on whole rice and wheat produced adults with higher flight initiation, higher lipid content, and higher oleic acid concentration than beetles reared on whole corn and sorghum.     

谷蠹生态学特性的研究

谷蠹Rhyzoperthadominica（F．）生态学特性的试验结果表明,温度、湿度、粮食含水量对其各发育历期影响非常显著;食物影响不显著。     

Effects of harvest residue and tillage on lesser cornstalk borer (Lepidoptera: Pyralidae) damage to sugarcane

Lesser cornstalk borer, Elasmopalpus lignosellus (Zeller) (Lepidoptera: Pyralidae) is an important pest of sugarcane (a complex hybrid of Saccharum spp.) in southern Florida. Cultural controls for E. lignosellus were evaluated in preparation for the potential loss of effective insecticides. Field studies conducted in 2006 compared the effects of harvest residues from green-harvested sugarcane (no preharvest burning to remove leaf matter) on E. lignosellus stalk damage and yield. Damage by E. lignosellus was significantly lower in plant cane plots that were covered with harvest residues collected from a green-harvested field before shoot emergence compared with plots without harvest residue. There were no yield differences between plots with and without harvest residues in plant or ratoon sugarcane fields in the 2006 study. The effects of three postharvest tillage levels (conventional, intermediate, and no tillage) were evaluated in preharvest burned and green-harvested fields in 2008 and 2009. Significantly less E. lignosellus damage was observed in the green- versus preharvest burned fields in both years. Intermediate and no-tillage plots had very little damage in green-harvested field. Conventional tillage plots had the greatest damage in the green-harvested field and the lowest damage in the preharvest burned field. In 2008, biomass yield was greater in the intermediate than conventional tillage in the green-harvested field, but it was greater in the conventional than in other tillage levels in the preharvest burned field. These studies demonstrated that cultural controls could greatly reduce E. lignosellus damage in sugarcane without the use of insecticides.     

Transient gut retention and persistence of Salmonella through metamorphosis in the lesser mealworm, Alphitobius diaperinus (Coleoptera: Tenebrionidae)

Aims: This study was undertaken to determine the retention of Salmonella through Alphitobius diaperinus metamorphosis and its contribution, through defecation, to external contamination. Methods and Results: Insects were exposed to a tagged Salmonella enterica and evaluated for external elimination. (i) Each day for 3 weeks, a filter collected frass from a restrained insect for analysis. (ii) Exposed larvae in a closed container were followed through pupation, and newly emerged adults were examined for their retention of marker bacteria. Conclusions: Exposed adults and larvae produced Salmonella‐positive frass for an average of 8 days, ranging from 6 to 11 days and 6 to 12 days, respectively. Nineteen per cent of the larvae carried Salmonella through metamorphosis and eclosion, with 5% of the pupal exuviae being positive as well. Significance and Impact of the Study: Many sources of foodborne pathogens within the poultry production facilities, including reservoir populations, currently go unrecognized. This diminishes the ability of producers to mitigate the transfer of pathogens between animals, humans and the environment. Poultry management standards accept the reutilization of litter. Alphitobius diaperinus survive between flock rotations on the reutilized litter, and it was demonstrated in this study that the Salmonella they carry can survive with them.     

A newly recorded entomopoxvirus B in Anacridium aegyptium (Orthoptera: Acrididae)

An entomopoxvirus infecting fat body cells of Anacridium aegyptium is reported. Spheroid virus occlusion bodies, ranging in size from 3 to 8 μm, contain virions 336–356 nm long and 210–217 nm wide. The virion ultrastructure indicates that the newly discovered virus belongs to the genus Entomopoxvirus B known to infect Lepidoptera and Orthoptera.     

Expression of a Bacillus thuringiensis cryIA(c) gene in transgenic peanut plants and its efficacy against lesser cornstalk borer

The invasion of peanut (Arachis hypogaea L.) pods and seeds by aflatoxin-forming species of Aspergillus is linked to injury by the lesser cornstalk borer and frequently causes a severe reduction in crop quality. The lesser cornstalk borer is susceptible to the lepidopteran-active Bacillus thuringiensis insecticidal crystal protein. We have introduced a codon-modified Bacillus thuringiensis cryIA(c) gene into peanut using microprojectile bombardment. The toxin-coding region of a Bt cryIA(c) gene was reconstructed for expression in plants and the resulting 3.4 kb gene cassette (promoter: 1.8 kb coding: 3) was directly cloned into the BglII site of plant transformation vectors. The vectors contained the hph gene, conferring resistance to the antibiotic hygromycin. Somatic embryos initiated from immature peanut cotyledons of two cultivars were used as the target for bombardment. DNA from hygromycin-resistant embryogenic cell lines, regenerated plants, and a progeny plant showed the presence and integration of hph and Bt genes by PCR and/or Southern blot analyses. ELISA immunoassay of the CryIA(c) protein from the hygromycin-selected plants showed the expression of CryIA(c) protein up to 0.18% of total soluble protein. Insect feeding bioassay of transformed plants indicated various levels of resistance to the lesser cornstalk borer, from complete larval mortality to a 66% reduction in larval weight. A negative correlation between percent survival or larval weight and the amount of Bt CryIA(c) protein was recorded indicating in general that the higher the protein level the lower the survival or larval weight of the insect. Based on leaf bioassay, transformation of peanut with vectors containing the Bt cryIA(c) gene may be effective in protecting the peanut plants from damage by lepidopteran insect larvae of lesser cornstalk borer     

Characterization of midgut trypsin-like enzymes and three trypsinogen cDNAs from the lesser grain borer, Rhyzopertha dominica (Coleoptera: Bostrichidae)

Protein digestion in the lesser grain borer, Rhyzopertha dominica (F.) (Coleoptera: Bostrichidae), results from the action of a complex of serine proteinases present in the midgut. In this study we partially characterized trypsin-like enzyme activity against N-alpha-benzoyl-L-arginine p-nitroanilide (BApNA) in midgut preparations and cloned and sequenced three cDNAs for trypsinogen-like proteins. BApNAase activity in R. dominica midgut was significantly reduced by serine proteinase inhibitors and specific inhibitors of trypsin, whereas BApNAase activity was not sensitive to specific inhibitors of chymotrypsin or aspartic proteinases. However, trans-epoxysuccinyl-L-leucylamido-(4-guanidino) butane (E-64) inhibited BApNAase activity by about 30%. BApNAase was most active in a broad pH range from about pH 7 to 9.5. The gut of R. dominica is a tubular tract approximately 2.5 mm in length. BApNAase activity was primarily located in the midgut region with about 1.5-fold more BApNAase activity in the anterior region compared to that in the posterior region. Proteinases with apparent molecular masses of 23-24 kDa that were visualized on casein zymograms following electrophoresis were inhibited by TLCK. Three cDNAs for trypsinogen-like proteins were cloned and sequenced from mRNA of R. dominica midgut. The full cDNA sequences consisted of open reading frames encoding 249, 293, and 255 amino acid residues for RdoT1, RdoT2, and RdoT3, respectively. cDNAs RdoT1, RdoT2, and RdoT3 shared 77-81% sequence identity. The three encoded trypsinogens shared 54-62% identity in their amino acid sequences and had 16-18 residues of signal peptides and 12-15 residues of activation peptides. The three predicted mature trypsin-like enzymes had molecular masses of 23.1, 28, and 23.8 kDa for RdoT1, RdoT2, and RdoT3, respectively. Typical features of these trypsin-like enzymes included the conserved N-terminal residues IVGG62-65, the catalytic amino acid triad of serine proteinase active sites (His109, Asp156, Ser257), three pairs of conserved cysteine residues for disulfide bridges, and the three residues (Asp251, Gly274, Gly284) that determine specificity in trypsin-like enzymes. In addition, RdoT2 has both a PEST-like sequence at the C-terminus and a free Cys158 near the active site, suggesting instability of this enzyme and/or sensitivity to thiol reagents. The sequences have been deposited in GenBank database (accession numbers AF130840 for RdoT1, AF130841 for RdoT2, and AF130842 for RdoT3).     

Assessing toxicity of Lake Diefenbaker (Saskatchewan,Canada) sediments using algal and nematode bioassays

Lake Diefenbaker, on the South Saskatchewan River, Saskatchewan, Canada, receives, on average, 90% of its inflow from snowmelt and rainfall in the Rocky Mountains. The inflowing rivers also receive irrigation return flows and municipal and industrial effluents which may result in the contamination of lake sediments. The sediments were assessed by nematode and algal bioassays.The toxicity of five chemical fractions of the sediment was determined using the nematode Panagrellus redivivus as the test organisms. The results suggest that the sediment chemical fractions frequently inhibit growth and maturation, while lethality was observed at 4 of 12 sites.Samples from 3 of these sites were further evaluated using conventional elutriate Algal Fractionation Bioassays (AFB) with both natural Lake Diefenbaker phytoplankton and a mixed laboratory grown algal culture. The natural phytoplankton showed inhibition at sediment: water ratios of 10: 1; whereas the algal cultures showed both enhancement and inhibition. Evidently, the sediments are frequently toxic to the species tested except for the algal culture. The AFB assesses the mitigative and synergistic effects of contaminants and nutrients and being a conventional elutriate, is more realistic and potentially more acceptable than the chemical fractionation/nematode bioassay technique which essentially considers potential trace organic contaminant effects.     

Expression of the maize proteinase inhibitor (mpi) gene in rice plants enhances resistance against the striped stem borer (Chilo suppressalis): effects on larval growth and insect gut proteinases

The maize proteinase inhibitor (mpi) gene was introduced into two elite japonica rice varieties. Both constitutive expression of the mpi gene driven by the maize ubiquitin 1 promoter and wound-inducible expression of the mpi gene driven by its own promoter resulted in the accumulation of MPI protein in the transgenic plants. No effect on plant phenotype was observed in mpi-expressing lines. The stability of transgene expression through successive generations of mpi rice lines (up to the T(4) generation) and the production of functional MPI protein were confirmed. Expression of the mpi gene in rice enhanced resistance to the striped stem borer (Chilo suppressalis), one of the most important pests of rice. In addition, transgenic mpi plants were evaluated in terms of their effects on the growth of C. suppressalis larvae and the insect digestive proteolytic system. An important dose-dependent reduction of larval weight of C. suppressalis larvae fed on mpi rice, compared with larvae fed on untransformed rice plants, was observed. Analysis of the digestive proteolytic activity from the gut of C. suppressalis demonstrated that larvae adapted to mpi transgene expression by increasing the complement of digestive proteolytic activity: the serine and cysteine endoproteinases as well as the exopeptidases leucine aminopeptidase and carboxypeptidases A and B. However, the induction of such proteolytic activity did not prevent the deleterious effects of MPI on larval growth. The introduction of the mpi gene into rice plants can thus be considered as a promising strategy to protect rice plants against striped stem borer.     

Production and partial characterization of monoclonal antibodies for detection of entomopoxvirus from Melanoplus sanguinipes

Entomopoxviruses (EPV) are currently being considered as candidate grasshopper (Orthoptera: Acrididae) microbial control agents. Classical techniques for diagnosing infections in grasshoppers are laborious, time consuming, and sometimes inaccurate. Specific murine monoclonal antibodies were developed against an EPV from Melanoplus sanguinipes (Fab) for use in a nitrocellulose-based enzyme-linked immunoassay (dot-blot). An IgG_2b monoclonal antibody was used to diagnose infections in grasshoppers 13 days following injection with virions. Of 25 grasshoppers that had patent infections microscopically, 22 produced positive results on the dot-blot. In a second test, 39 patently infected grasshoppers all produced positive results. Seven additional grasshoppers in the first test and 2 in the second test gave positive reactions in the dot-blot method but virus was not detected upon microscopic examination. The monoclonal antibody did not cross-react with other commonly occurring grasshopper pathogens. The dot-blot method detected as few as 2.5×10⁶ purified EPV virions. The improvement over existing detection techniques should facilitate evaluation of EPV for field use.

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Prodution et caractérisation partielle d'anticorps monoclonaux pour la détection d'entomopoxyvirus de Melanoplus sanguinipes

Résumé Les criquets sont très nuisibles aux pâturages de l'Ouest des USA et du Canada. Les méthodes classiques de protection sont basées sur les traitements chimiques lors des pullulations. Un entomopoxvirus (EPV) extrait de M. sanguinipes est généralement considéré comme un outil, pour le contrôle des populations sur une longue période, en vue de la suppression des criquets. Les méthodes actuelles d'isolement de EPV sont longues, pénibles et peu fiables. Les tests d'adsorption des antigènes sur l'anticorps fixé et le dosage per l'anticorps enzymatiquement marqué sont efficaces, sûrs et donnent à temps des résultats pour déceler des entomopathogènes. Nous avons produit des anticorps monoclonaux de souris contre EPV de M. sanguinipes, et les avons utilisés dans des dosages immunoenzymatiques d'extraits protéiques adsorbés sur nitrocellulose. Les EPV sont recherchés sur des criquets injectés de virions 13 jours avant. Sur 25 criquets qui présentaient des infections nettes lors d'examens microscopiques, 22 ont donné des résultats positifs par sérologie. Dans un second test, sur 38 criquets nettement contaminés, tous ont donné des résultats positifs; 7 criquets suppl'ementaires mentaires dans le premier test et 2 dans le second test ont donné des résultats positifs en sérologie alors que l'examen microsopique n]avait pas test ont donné des résultats positifs en sérologie alors que l'examen microsopique n'avait pas révélé de virus. Ceci montre que ce type de détection est plus sûr que la méthode ordinaire. Les anticorps monoclonaux ne donnent pas de réactions avec les autres pathogènes courants des criquets. La méthode sérologique a permis de détecter même une concentration de 2,5×10⁶ virions EPV.

     

Calcium silicate enhances resistance of sugarcane to the African stalk borer Eldana saccharina Walker (Lepidoptera: Pyralidae)

Abstract

• 1 The stalk borer Eldana saccharina is the most destructive pest in sugarcane in South Africa. This study investigated: (1) the potential of applied silicon in enhancing plant resistance of sugarcane to E. saccharina, using calcium silicate as a carrier; (2) whether there was any interaction between cane variety (and stalk borer resistance) and silicon treatment.
• 2 Six commercial varieties of sugarcane were treated in a pot‐plant trial with two levels (5000 and 10 000 kg/ha) of calcium silicate. After artificial infestation with E. saccharina, response to the treatments was assessed in terms of borer numbers and mass, and stalk damage.
• 3 Calcium silicate significantly enhanced resistance at the higher rate compared with the control. Borer mass was reduced by 19.8% and stalk length bored by 24.4%. Lower treatment values were intermediate between those of the higher treatment and the control.
• 4 The interaction between variety and Si treatment was not significant when varieties were examined individually in the analysis. However, the interaction was significant for borer mass when varieties were grouped according to their resistance characteristics. Susceptible varieties might benefit more from treatment with silicon than resistant ones, as resistant varieties showed no significant effect of silicon.
• 5 All varieties had increased silicon content due to the treatments, but differed appreciably in stalk silicon content at the different treatment levels. Similarly, within varieties, stalk silicon content did not correspond consistently with borer response patterns and silicate application rates.

     

Efficacy of two entomopathogenic nematodes Heterorhabditis bacteriophora and Steinernema carpocapsae for control of the leopard moth borer Zeuzera pyrina (Lepidoptera: Cossidae) larvae under laboratory conditions

The biological traits of the entomopathogenic nematodes (EPNs), Steinernema carpocapsae and Heterorhabditis bacteriophora, against the larvae of the leopard moth, Zeuzera pyrina were evaluated in the laboratory. The traits included pathogenicity, penetration potential as well as foraging behaviour. Plate assays were performed using a range of EPN concentrations (5, 10, 20, 50 and 100 infective juveniles (IJs) per larva). The LC₅₀ values for S. carpocapsae and H. bacteriophora were 6.4 and 8.4 IJs larva^?1 after 72 h. Both EPN species caused high mortality in branch experiments. Significantly higher mortality rates occurred in the larger larvae after exposure to S. carpocapsae. Both EPN species successfully penetrated the Z. pyrina larvae as well as larvae of Galleria mellonella L. (Lepidoptera: Galleridae).The proportional response of H. bacteriophora to host-associated cues was strongly higher than S. carpocapsae in Petri dishes containing agar 1, 12 and 24 h after EPN application. These results highlight the efficiency of EPNs for the control of Z. pyrina larvae. However, due to the cryptic habitat of Z. pyrina larvae in their galleries in the trees, field trails need to be conducted to further evaluate this potential.     

Age-specific dose-mortality effects of Beauveria bassiana (Deuteromycotina: Hyphomycetes) on the European corn borer,Ostrinia nubilalis (Lepidoptera: Pyralidae)

Three isolates of Beauveria bassiana were evaluated under laboratory conditions for pathogenicity against the European corn borer, Ostrinia nubilalis. Dose-mortality regressions and nonparametric statistical analyses revealed significant differences in pathogenicity between isolates and across O. nubilalis instars. First instars were found to be the most susceptible of the five larval stages. Little difference was noted for instars 2, 3, and 5 within any of the three B. bassiana isolates. Fourth instar larvae were found to be the most tolerant in all cases.     

Genetic variation within and among fragmented populations of lesser prairie-chickens (Tympanuchus pallidicinctus)

As a result of recurrent droughts and anthropogenic factors, the range of the lesser prairie-chicken (Tympanuchus pallidicinctus) has contracted by 92% and the population has been reduced by approximately 97% in the past century, resulting in the smallest population size and most restricted geographical distribution of any North American grouse. We examined genetic variation through DNA sequence analysis of 478 base pairs of the mitochondrial genome and by assaying allelic variation at five microsatellite loci from lesser prairie-chickens collected on 20 leks in western Oklahoma and east-central New Mexico. Traditional population genetic analyses indicate that lesser prairie-chickens maintain high levels of genetic variation at both nuclear and mitochondrial loci. Although some genetic structuring among lesser prairie-chicken leks was detected within Oklahoma and New Mexico for both nuclear and mitochondrial loci, high levels of differentiation were detected between Oklahoma and New Mexico populations. Nested-clade analysis of mitochondrial haplotypes revealed that both historic and contemporary processes have influenced patterns of haplotype distributions and that historic processes have most likely led to the level of differentiation found between the Oklahoma and New Mexico populations.     

Female reproductive tract of the lesser anteater (Tamandua tetradactyla,myrmecophagidae, Xenarthra). Anatomy and histology

The morphological and histological features of the unusual reproductive tract of the female lesser anteater, Tamandua tetradactyla (Myrmecophagidae, Xenarthra), are described for the first time. The present study aimed to establish the main similarities and differences between this species and other xenarthrans. The populations of this species are declining rapidly for a number of reasons and our study is relevant to diverse programs related to its conservation. Studies were carried out on five female genital tracts of adult specimens. Ovaries were ovoid, presenting a medulla completely surrounded by the cortex, differently from that described in other xenarthans. Like in Dasypus but different from all other armadillos studied, single oocyte follicles were observed and a simple the uterus. The uterovaginal canal connects the uterus with the urogenital sinus. The simple columnar epithelium of the uterovaginal canal ends abruptly at a septum which resembles a hymen, where the transitional epithelium of the urogenital sinus appears. This ancestral feature is shared with that of other armadillos, except Tolypeutes matacus, which has a true vagina. Characteristics of the reproductive tract and sperm morphology of other Xenarthra are comparatively discussed. These observations suggest that important reproductive features are shared between the family Myrmecophagidae and the genus Dasypus, a basal group in the phylogeny of Xenarthra. J. Morphol. 2011. © 2011 Wiley‐Liss, Inc.     

Morphological study of the reproductive system and ovarian growth of the univoltine bamboo borer,Omphisa fuscidentalis (Hampson, 1896) (Lepidoptera: Crambidae)

ABSTRACT

The female reproductive system and protein deposition in the ovaries during development have never been examined in the bamboo borer Omphisa fuscidentalis Hampson. The aim of this study was thus to study the morphology of the female reproductive system of each stage of development. The female reproductive system of the borer consists of a pair of ovary, oviduct and accessory glands. Each ovary is composed of four polytrophic ovarioles that connect to lateral oviducts, fused with a common oviduct. The size of the ovary in diapausing larvae for 9 months was determined. The length and width of the ovaries were the smallest in September larvae (0.343 ± 0.03 and 0.071 ± 0.01 mm, respectively). The ovaries were the largest during ovarian development in May (0.752 ± 0.08 mm long and 0.084 ± 0.01 wide). Additionally, ovarian size was significantly larger in adults than in pupae. The ovarian protein concentration of larvae in May was 0.59 ± 0.06 mg/ml and increased to 16.61 ± 7.5 and 37.42 ± 5.5 mg/ml in pupae (June) and adults (July), respectively. The results showed ovarian development in all life stages of this holometabolous insect, which has a longer life cycle than other lepidopterans.

Abbreviation: TEM: transmission electron microscope     

Characterization of midgut trypsin-like enzymes and three trypsinogen cDNAs from the lesser grain borer, Rhyzopertha dominica (Coleoptera: Bostrichidae)

Protein digestion in the lesser grain borer, Rhyzopertha dominica (F.) (Coleoptera: Bostrichidae), results from the action of a complex of serine proteinases present in the midgut. In this study we partially characterized trypsin-like enzyme activity against N-α-benzoyl- -arginine p-nitroanilide (BApNA) in midgut preparations and cloned and sequenced three cDNAs for trypsinogen-like proteins. BApNAase activity in R. dominica midgut was significantly reduced by serine proteinase inhibitors and specific inhibitors of trypsin, whereas BApNAase activity was not sensitive to specific inhibitors of chymotrypsin or aspartic proteinases. However, trans-epoxysuccinyl- -leucylamido-(4-guanidino) butane (E-64) inhibited BApNAase activity by about 30%. BApNAase was most active in a broad pH range from about pH 7 to 9.5. The gut of R. dominica is a tubular tract approximately 2.5 mm in length. BApNAase activity was primarily located in the midgut region with about 1.5-fold more BApNAase activity in the anterior region compared to that in the posterior region. Proteinases with apparent molecular masses of 23–24 kDa that were visualized on casein zymograms following electrophoresis were inhibited by TLCK.Three cDNAs for trypsinogen-like proteins were cloned and sequenced from mRNA of R. dominica midgut. The full cDNA sequences consisted of open reading frames encoding 249, 293, and 255 amino acid residues for RdoT1, RdoT2, and RdoT3, respectively. cDNAs RdoT1, RdoT2, and RdoT3 shared 77–81% sequence identity. The three encoded trypsinogens shared 54–62% identity in their amino acid sequences and had 16–18 residues of signal peptides and 12–15 residues of activation peptides. The three predicted mature trypsin-like enzymes had molecular masses of 23.1, 28, and 23.8 kDa for RdoT1, RdoT2, and RdoT3, respectively. Typical features of these trypsin-like enzymes included the conserved N-terminal residues IVGG^62–65, the catalytic amino acid triad of serine proteinase active sites (His¹⁰⁹, Asp¹⁵⁶, Ser²⁵⁷), three pairs of conserved cysteine residues for disulfide bridges, and the three residues (Asp²⁵¹, Gly²⁷⁴, Gly²⁸⁴) that determine specificity in trypsin-like enzymes. In addition, RdoT2 has both a PEST-like sequence at the C-terminus and a free Cys¹⁵⁸ near the active site, suggesting instability of this enzyme and/or sensitivity to thiol reagents. The sequences have been deposited in GenBank database (accession numbers AF130840 for RdoT1, AF130841 for RdoT2, and AF130842 for RdoT3).