Clone history shapes Populus drought responses.

Just as animal monozygotic twins can experience different environmental conditions by being reared apart, individual genetically identical trees of the genus Populus can also be exposed to contrasting environmental conditions by being grown in different locations. As such, clonally propagated Populus trees provide an opportunity to interrogate the impact of individual environmental history on current response to environmental stimuli. To test the hypothesis that current responses to an environmental stimulus, drought, are contingent on environmental history, the transcriptome- level drought responses of three economically important hybrid genotypes-DN34 (Populus deltoides × Populus nigra), Walker [P. deltoides var. occidentalis × (Populus laurifolia × P. nigra)], and Okanese [Walker × (P. laurifolia × P. nigra)]-derived from two different locations were compared. Strikingly, differences in transcript abundance patterns in response to drought were based on differences in geographic origin of clones for two of the three genotypes. This observation was most pronounced for the genotypes with the longest time since establishment and last common propagation. Differences in genome-wide DNA methylation paralleled the transcriptome level trends, whereby the clones with the most divergent transcriptomes and clone history had the most marked differences in the extent of total DNA methylation, suggesting an epigenomic basis for the clone history-dependent transcriptome divergence. The data provide insights into the interplay between genotype and environment in the ecologically and economically important Populus genus, with implications for the industrial application of Populus trees and the evolution and persistence of these important tree species and their associated hybrids.

Intraspecific variation in the Populus balsamifera drought transcriptome.

Drought is a major limitation to the growth and productivity of trees in the ecologically and economically important genus Populus. The ability of Populus trees to contend with drought is a function of genome responsiveness to this environmental insult, involving reconfiguration of the transcriptome to appropriately remodel growth, development and metabolism. Here we test hypotheses aimed at examining the extent of intraspecific variation in the drought transcriptome using six different Populus balsamifera L. genotypes and Affymetrix GeneChip technology. Within a given genotype there was a positive correlation between the magnitude of water-deficit induced changes in transcript abundance across the transcriptome, and the capacity of that genotype to maintain growth following water deficit. Genotypes that had more similar drought-responsive transcriptomes also had fewer genotypic differences, as determined by microarray-derived single feature polymorphism (SFP) analysis, suggesting that responses may be conserved across individuals that share a greater degree of genotypic similarity. This work highlights the fact that a core species-level response can be defined; however, the underpinning genotype-derived complexities of the drought response in Populus must be taken into consideration when defining both species- and genus-level responses.

Wound-induced terpene synthase gene expression in Sitka spruce that exhibit resistance or susceptibility to attack by the white pine weevil.

We analyzed the expression pattern of various terpene synthase (TPS) genes in response to a wounding injury applied to the apical leader of Sitka spruce (Picea sitchensis Bong. Carr.) genotypes known to be resistant (R) or susceptible (S) to white pine weevil (Pissodes strobi Peck.) attack. The purpose was to test if differences in constitutive or wound-induced TPS expression can be associated with established weevil resistance. All wounding treatments were conducted on 9-year-old R and S trees growing under natural field conditions within the range of variation for weevil R and S genotypes. Representative cDNAs of the monoterpene synthase (mono-TPS), sesquiterpene synthase (sesqui-TPS), and diterpene synthase (di-TPS) classes were isolated from Sitka spruce to assess TPS transcript levels. Based on amino acid sequence similarity, the cDNAs resemble Norway spruce (Picea abies) (-)-linalool synthase (mono-TPS; PsTPS-Linl) and levopimaradiene/abietadiene synthase (di-TPS; PsTPS-LASl), and grand fir (Abies grandis) delta-selinene synthase (sesqui-TPS; PsTPS-Sell). One other mono-TPS was functionally identified as (-)-limonene synthase (PsTPS-Lim). No significant difference in constitutive expression levels for these TPSs was detected between R and S trees. However, over a postwounding period of 16 d, only R trees exhibited significant transcript accumulation for the mono- and sesqui-TPS tested. Both R and S trees exhibited a significant accumulation of PsTPS-LASl transcripts. An assessment of traumatic resin duct formation in wounded leaders showed that both R and S trees responded by forming traumatic resin ducts; however, the magnitude of this response was significantly greater in R trees. Collectively, our data imply that the induced resinosis response is an important aspect of defense in weevil R Sitka spruce trees growing under natural conditions.

Stress-responsive alpha-dioxygenase expression in tomato roots.

Alpha-dioxygenase (alpha-DOX) enzymes catalyse the oxygenation of fatty acids to yield a newly identified group of oxylipins that play a role in protecting tissues from oxidative damage and cell death. In tomato (Lycopersicon esculentum Mill.) alpha-DOX was identified as salt-regulated by differential display of mRNA, and is represented by a small gene family comprising at least three members: LEalpha-DOX1, -2, and -3 of which only LEalpha-DOX1 was salt-responsive. The enhancement of LEalpha-DOX1 expression in roots by salt, wounding and challenge with Pythium aphanidermatum (Edson) Fitzp. suggests that alpha-DOX-generated oxylipins may mediate the response of roots to these environmental stresses. In roots, LEalpha-DOX1 was abscisic acid (ABA)-responsive. However, in the ABA-deficient mutant flacca salt-responsive expression was equivalent to that in the wild type. Similarly, in roots exposed to fluridone (FLU) salt up-regulated expression; however, in this case salt-responsive LEalpha-DOX1 expression was greater than that in roots that were not exposed to FLU. A possible explanation for this is provided by the role of ABA in suppressing ethylene accumulation in osmotically stressed roots. The ethylene-generating agent ethephon and precursor 1-aminocyclopropane-1-carboxylic acid markedly elevated LEalpha-DOX1 expression, and this enhanced expression was suppressed by ABA. LEalpha-DOX1 expression in salt-stressed roots was not markedly affected by AVG indicating that ABA may be responsible for enhanced alpha-DOX expression in salt-treated roots.

Oral findings in coeliac disease and Sjögren's syndrome.

OBJECTIVE: Both coeliac disease (CD) and Sjogren's syndrome (SS) have an autoimmune background and increased risk of oral mucosal and dental abnormalities. Individuals suffering concomitantly from CD and SS could even be at a higher risk. STUDY DESIGN: Oral mucosal and dental abnormalities were examined in 20 patients with CD + SS (mean age 61 years) and compared with age- and sex-matched controls with either CD or SS. RESULTS: Oral mucosal changes were most common in SS (80%), followed by CD + SS (65%) and CD (40%). Coeliac-type dental enamel defects were found in 89% in CD + SS and in 88% in CD compared with only 25% in SS (P < 0.001). The median number of teeth was six in the CD + SS, 24 in the CD and 22 in the SS group. The DMF index was higher (P < 0.005) in the CD + SS than in the CD group. CD + SS was characterized by higher salivary flow rate (P < 0.001) and lower inflammatory focus score in the salivary glands (P < 0.01) than SS. CONCLUSIONS: The co-occurrence of CD and SS should be recognized because of its effects on dental and oral mucosal health. A lower salivary gland inflammatory focus score and higher salivary flow rate in CD + SS than in SS suggests that a gluten-free diet treatment may alleviate autoimmune inflammation.

Insect attack and wounding induce traumatic resin duct development and gene expression of (-)-pinene synthase in Sitka spruce.

Conifers possess inducible terpenoid defense systems. These systems are associated with the formation of traumatic resin ducts (TRD) and are underpinned by enhanced gene expression and activity of terpene synthases (TPS), enzymes responsible for oleoresin formation. We first determined that Sitka spruce (Picea sitchensis [Bong.] Carriere) had the capacity for TRD formation by mechanically wounding representative trees. We then proceeded to investigate whether the white pine weevil (Pissodes strobi Peck.), a stem-boring insect, can influence the expression of genes encoding monoterpene synthases (mono-tps) in Sitka spruce. We went on to compare this response with the effects of a simulated insect attack by drill wounding. A significant increase in mono-tps transcript level was observed in the leaders of lateral branches of weevil-attacked and mechanically wounded trees. In this study, weevils induced a more rapid enhancement of mono-tps gene expression. A full-length Sitka spruce mono-tps cDNA (PsTPS2) was isolated, expressed in Escherichia coli, and functionally identified as (-)-pinene synthase. The recombinant (-)-pinene synthase catalyzes the formation of (-)-alpha-pinene and (-)-beta-pinene, both of which are known constituents of stem oleoresin in Sitka spruce and increase in abundance after weevil attack. These data suggest that increased (-)-pinene synthase gene expression is an important element of the direct defense system deployed in Sitka spruce after insect attack.

Enamel defects in primary and permanent teeth of children born prematurely.

The objective of this study was to determine the prevalence of enamel defects in both primary and permanent dentitions of the same preterm children, and to elucidate the role of early dietary mineral and vitamin D intake in the etiology of the enamel defects. The status of the primary and permanent teeth was evaluated in 32 preterm children and in 64 control children. The prevalence of enamel defects in children born preterm was clearly higher as compared with controls in both the primary (78% vs 20%, P<0.001) and permanent (83% vs 36%, P<0.001) dentitions. Neither the mineral supplementation used nor a vitamin D dose of 1000 IU/day, as compared with a lower dose of 500 IU/day, reduced the prevalence of enamel defects in the primary or permanent dentitions. Further studies are needed to clarify whether achieving near optimum intra-uterine mineral retention would lower the prevalence of subsequent enamel defects in infants born prematurely.

Maturation of primary and permanent teeth in preterm infants.

AIMS: To elucidate the development of primary and permanent teeth and to interpret the effect of different calcium, phosphorus, and vitamin D supplementation in the neonatal period on dental maturation in preterm children. METHODS: Preterm infants were randomised to four groups to receive a vitamin D dose of 500 or 1000 IU/day and calcium and phosphorus supplemented or unsupplemented breast milk. The maturity of the primary and permanent teeth was recorded in 30 preterm children. Sixty children aged 2 years and 60 children aged 9-11 years served as controls. Bone mineral content/density was assessed in the preterm infants. RESULTS: The median (range) corrected teething age was 7 (2-16) months in preterm infants and 6 (2-12) months in controls (p = 0.43). The median (range) number of erupted teeth at 2 years of age was 16 (11-19) in preterm infants and 16 (12-20) in controls (p = 0.16). Maturation of the permanent teeth in the preterm infants was not delayed compared with the controls (mean Demirjian SDS 0.16 v 0.49, p = 0.14). Early dietary intake of either mineral or vitamin D did not affect maturation of the primary dentition in preterm children. Children receiving the higher vitamin D dose in the neonatal period had more mature permanent dentition than those receiving the lower dose, but mineral intake did not affect maturation of the permanent teeth. Dental maturation did not correlate with bone mineral status. CONCLUSIONS: This is the first longitudinal study to follow primary and permanent tooth maturation in the same preterm children. Premature birth has no appreciable late sequelae in tooth maturation.

Dental maturity in Finns and the problem of missing teeth.

Development of teeth was studied from 2483 dental panoramic tomograms of 1651 healthy Finns ranging in age from 2 to 25 years. Dental maturity was assessed using a method based on developmental stages of 7 left mandibular teeth. We give sex-specific tables of maturity scores as a function of ages and of ages as a function of maturity scores. Also generated are percentile graphs for visual evaluations of dental maturity in children and adolescents. Since maturity scales do not tolerate any missing data, a great limitation for their use, we have developed linear regression models for predicting the formation stages of each of the 7 mandibular teeth. It was easiest to predict the formation stage of the mandibular first molars (correct in 87% within the study material) and most difficult to predict second molars and second premolars (correct in 69% and 70%, respectively). We expect the data and formulae presented in this study to prove useful in research and in clinical and forensic dentistry.

Mutans streptococcal serotypes in children with gastroesophageal reflux disease.

It has been suggested that vomiting acid gastric contents in bulimia might favor oral growth of Streptococcus sobrinus. We studied the colonization of Streptococcus sobrinus (serotypes g and d) and Streptococcus mutans (serotypes c, e and f) in sixteen children, ages five to fifteen years, who had suffered for four to eleven years from gastroesophageal reflux, another condition with recurrent acid regurgitation. Our aim was to find out if the prevalence of Streptococcus sobrinus would be higher also in this patient group. Mutants streptococci were detected in twelve out of sixteen (75 percent) study patients of the saliva samples cultured on MSB agar. For the Mutans streptococci positive children healthy controls were matched by salivary levels of mutans streptococci and age as closely as possible. From each child three to six isolates representing both Streptococcus mutans and Streptococcus sobrinus (n = 103) were serotyped by immunodiffusion method. The distribution of serotypes in the study/control group was: c: 7/10; e: 4/2; f: 0/1; g:3/2; d:0/0. One strain in the study group remained untypable. All patients infected with Streptococcus sobrinus were also infected with Streptococcus mutans. Our results indicate the great similarity in the distribution of ms serotypes in the gastroesophageal reflux children and their healthy controls. The data do not suggest that the acid regurgitation would have an influence on the prevalence of Streptococcus sobrinus.

Coeliac-type permanent-tooth enamel defects.

Systematic and chronologically distributed permanent-tooth so-called coeliac-type enamel defects are highly prevalent both in children and adults with coeliac disease (gluten-sensitive enteropathy) and dermatitis herpetiformis. Coeliac-type enamel defects were also found in healthy first-degree family members of coeliac disease patients. Our family study showed that these persons with the typical defected enamel were genetically similar to coeliac disease patients (A1;B8;DR3). As coeliac disease patients are often clinically silent with no gastrointestinal symptoms, or they complain only of minimal abdominal discomfort, both dentists and physicians could select patients with coeliac-type enamel defects for gastroenterological and dermatological consultations, including serological screening tests and later jejunal mucosal biopsy.

Permanent tooth dental enamel defects leading to the diagnosis of coeliac disease.

The case of an 8-year-old otherwise healthy boy whose permanent tooth enamel lesions led to the diagnosis of coeliac disease is reported. The importance of gluten-induced permanent tooth enamel defects is discussed.

Coeliac-type dental enamel defects in patients with dermatitis herpetiformis.

The teeth of 30 adult patients with dermatitis herpetiformis and 66 sex- and age-matched healthy controls were examined for dental enamel defects. Sixteen of the patients (53%) with dermatitis herpetiformis, opposed to only one (2%) of the healthy controls (p less than 0.001), were found to have coeliactype permanent-tooth enamel defects. The grades of these defects were milder than those described for severe coeliac disease. There was no correlation between the degree of enamel defects and jejunal villous atrophy. The present finding of frequent coeliactype dental enamel defects in adults with dermatitis herpetiformis suggests that these patients were already suffering from subclinical gluteninduced enteropathy in early childhood, at the time when the crowns of permanent teeth develop.

Dental enamel defects in first-degree relatives of coeliac disease patients.

To find out whether dental changes can be used to screen for coeliac disease among apparently healthy relatives of patients with the disorder, 56 healthy first-degree relatives of such patients were subjected to dental examination and small bowel biopsy. 25 had coeliac-type general permanent-tooth enamel lesions. All 7 who had histological evidence of coeliac disease also had enamel lesions. The finding that enamel defects may occur without small bowel changes must be borne in mind in screening. The coeliac-type enamel changes were strongly associated with HLA-DR3, and most of the DR3 alleles belonged to the extended haplotype A1; B8; DR3 group.

Familial medullary thyroid carcinoma and multiple endocrine neoplasia type 2B map to the same region of chromosome 10 as multiple endocrine neoplasia type 2A.

Medullary thyroid carcinoma (MTC) occurs as a component of three well-described autosomal dominant familial cancer syndromes. Multiple endocrine neoplasia type 2A (MEN 2A) is characterized by MTC, pheochromocytomas, and parathyroid hyperplasia. Patients with the rarer multiple endocrine neoplasia type 2B (MEN 2B) syndrome develop MTC and pheochromocytomas, as well as mucosal neuromas, ganglioneuromatosis of the gastrointestinal tract, and a characteristic "marfanoid" habitus. Finally, MTC is transmitted in an autosomal dominant pattern in some families without associated pheochromocytomas or parathyroid hyperplasia (familial medullary thyroid carcinoma, MTC1(2). Sixty-one members of two well-characterized kindreds segregating MTC1 and 34 [corrected] members of six families segregating MEN2B were genotyped using a panel of RFLP probes from the pericentromeric region of chromosome 10 near a locus for MEN 2A. Statistically significant linkage was observed between the chromosome 10 centromere-specific marker D10Z1 and MTC1 (maximum pairwise lod score 5.88 with 0% recombination) and D10Z1 and MEN2B (maximum pairwise lod score 3.58 with 0% recombination). A maximum multipoint lod score of 4.08 was obtained for MEN2B at the position of D10Z1. In addition, 92 members of a previously unreported large MEN2A kindred were genotyped, and linkage to the pericentromeric region of chromosome 10 is reported (maximum pairwise lod score of 11.33 with 0% recombination between MEN2A and RBP3). These results demonstrate that both a locus for familial MTC and a locus for MEN 2B map to the pericentromeric region of chromosome 10, in the same region as a locus for MEN 2A. The finding that each of these three clinically distinct familial cancer syndromes maps to the same chromosomal region suggests that all are allelic mutations at the same locus or represent a cluster of genes involved in the regulation of neuroendocrine tissue development.

Dental enamel defects in celiac disease.

The teeth of 40 adults aged 19 to 67 yr with celiac disease (CD) were examined for dental enamel defects (ED). A total of 33 of the 40 adults with CD (83%) had systematic ED in contrast to only 5 of the 112 clinical controls (4%). Unspecific enamel lesions were found in both groups, but they were more common in the control group (80% vs. 18%). Altogether 69% of the permanent teeth in adults with CD were found to be defected, in clinical controls only 19%. In adults with CD the ED were in contrast to those in controls symmetrically and chronologically distributed in all four sections of dentition. The present study clearly shows that symmetrically and chronologically distributed enamel defects are strongly associated with CD. Therefore in the absence of symptoms and signs of malabsorption dentists could easily select the right patients possibly suffering from CD for gastroenterologic consultations.