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Multiple cytokines, including interleukin 6 (IL-6), IL-11, IL-27, oncostatin M (OSM), and leukemia inhibitory factor (LIF), signal via the common GP130 cytokine receptor subunit. In this study, we describe a patient with a homozygous mutation of IL6ST (encoding GP130 p.N404Y) who presented with recurrent infections, eczema, bronchiectasis, high IgE, eosinophilia, defective B cell memory, and an impaired acute-phase response, as well as skeletal abnormalities including craniosynostosis. The p.N404Y missense substitution is associated with loss of IL-6, IL-11, IL-27, and OSM signaling but a largely intact LIF response. This study identifies a novel immunodeficiency with phenotypic similarities to STAT3 hyper-IgE syndrome caused by loss of function of GP130., (© 2017 Schwerd et al.)

DNA replication precisely duplicates the genome to ensure stable inheritance of genetic information. Impaired licensing of origins of replication during the G1 phase of the cell cycle has been implicated in Meier-Gorlin syndrome (MGS), a disorder defined by the triad of short stature, microtia, and a/hypoplastic patellae. Biallelic partial loss-of-function mutations in multiple components of the pre-replication complex (preRC; ORC1, ORC4, ORC6, CDT1, or CDC6) as well as de novo stabilizing mutations in the licensing inhibitor, GMNN, cause MGS. Here we report the identification of mutations in CDC45 in 15 affected individuals from 12 families with MGS and/or craniosynostosis. CDC45 encodes a component of both the pre-initiation (preIC) and CMG helicase complexes, required for initiation of DNA replication origin firing and ongoing DNA synthesis during S-phase itself, respectively, and hence is functionally distinct from previously identified MGS-associated genes. The phenotypes of affected individuals range from syndromic coronal craniosynostosis to severe growth restriction, fulfilling diagnostic criteria for Meier-Gorlin syndrome. All mutations identified were biallelic and included synonymous mutations altering splicing of physiological CDC45 transcripts, as well as amino acid substitutions expected to result in partial loss of function. Functionally, mutations reduce levels of full-length transcripts and protein in subject cells, consistent with partial loss of CDC45 function and a predicted limited rate of DNA replication and cell proliferation. Our findings therefore implicate the preIC as an additional protein complex involved in the etiology of MGS and connect the core cellular machinery of genome replication with growth, chondrogenesis, and cranial suture homeostasis., (Copyright © 2016 American Society of Human Genetics. Published by Elsevier Inc. All rights reserved.)

Pfeiffer syndrome is an autosomal dominant condition classically combining craniosynostosis with digital anomalies of the hands and feet. The majority of cases are caused by heterozygous mutations in the third immunoglobulin-like domain (IgIII) of FGFR2, whilst a small number of cases can be attributed to mutations outside this region of the protein. A mild form of Pfeiffer syndrome can rarely be caused by a specific mutation in FGFR1. We report on the clinical and genetic findings in a three generation British family with Pfeiffer syndrome caused by a heterozygous missense mutation, p.Ala172Phe, located in the IgII domain of FGFR2. This is the first reported case of this particular mutation since Pfeiffer's index case, originally described in a German family in 1964, on which basis the syndrome was eponymously named. Genetic analysis demonstrated the two families to be unrelated. Similarities in phenotypes between the two families are discussed. Independent genetic origins, but phenotypic similarities in the two families add to the evidence supporting the theory of selfish spermatogonial selective advantage for this rare gain-of-function FGFR2 mutation., (Copyright © 2013 Wiley Periodicals, Inc.)

Background: Congenital limb malformations (CLMs) are common and present to a variety of specialties, notably plastic and orthopaedic surgeons, and clinical geneticists. The authors aimed to characterise causative mutations in an unselected cohort of patients with CLMs requiring reconstructive surgery., Methods: 202 patients presenting with CLM were recruited. The authors obtained G-banded karyotypes and screened EN1, GLI3, HAND2, HOXD13, ROR2, SALL1, SALL4, ZRS of SHH, SPRY4, TBX5, TWIST1 and WNT7A for point mutations using denaturing high performance liquid chromatography (DHPLC) and direct sequencing. Multiplex ligation dependent probe amplification (MLPA) kits were developed and used to measure copy number in GLI3, HOXD13, ROR2, SALL1, SALL4, TBX5 and the ZRS of SHH., Results: Within the cohort, causative genetic alterations were identified in 23 patients (11%): mutations in GLI3 (n = 5), HOXD13 (n = 5), the ZRS of SHH (n = 4), and chromosome abnormalities (n = 4) were the most common lesions found. Clinical features that predicted the discovery of a genetic cause included a bilateral malformation, positive family history, and having increasing numbers of limbs affected (all p<0.01). Additionally, specific patterns of malformation predicted mutations in specific genes., Conclusions: Based on higher mutation prevalence the authors propose that GLI3, HOXD13 and the ZRS of SHH should be prioritised for introduction into molecular genetic testing programmes for CLM. The authors have developed simple criteria that can refine the selection of patients by surgeons for referral to clinical geneticists. The cohort also represents an excellent resource to test for mutations in novel candidate genes.

Genes mutated in congenital malformation syndromes are frequently implicated in oncogenesis, but the causative germline and somatic mutations occur in separate cells at different times of an organism's life. Here we unify these processes to a single cellular event for mutations arising in male germ cells that show a paternal age effect. Screening of 30 spermatocytic seminomas for oncogenic mutations in 17 genes identified 2 mutations in FGFR3 (both 1948A>G, encoding K650E, which causes thanatophoric dysplasia in the germline) and 5 mutations in HRAS. Massively parallel sequencing of sperm DNA showed that levels of the FGFR3 mutation increase with paternal age and that the mutation spectrum at the Lys650 codon is similar to that observed in bladder cancer. Most spermatocytic seminomas show increased immunoreactivity for FGFR3 and/or HRAS. We propose that paternal age-effect mutations activate a common 'selfish' pathway supporting proliferation in the testis, leading to diverse phenotypes in the next generation including fetal lethality, congenital syndromes and cancer predisposition.

Apert syndrome (AS) is a severe disorder, characterized by craniosynostosis and complex syndactyly of the hands and feet. Two heterozygous gain-of-function substitutions (Ser252Trp and Pro253Arg) in exon IIIa of fibroblast growth factor receptor 2 (FGFR2) are responsible for >98% of cases. Here we describe two novel mutations in FGFR2 in the two patients in whom a mutation had not previously been found in our cohort of 227 AS cases. The first is a 1.93-kb deletion, removing exon IIIc and substantial portions of the flanking introns. This is the first large FGFR2 deletion described in any individual with craniosynostosis. The other mutation is a 5' truncated Alu insertion into exon IIIc. This is the third Alu insertion identified in AS; all have occurred within an interval of only 104 bp, representing an enrichment of over a million-fold compared to the background genomic rate. We show that the inserted Alu element belongs to a small subfamily, not previously known to be mobile, which we term Alu Yk13. Both the deletion and insertion are likely to act by a similar gain-of-function mechanism in which disruption of exon IIIc leads to illegitimate mesenchymal expression of an FGFR2 spliceform containing the alternatively spliced exon IIIb. All the AS-associated Alu insertions have arisen in the paternal germline; we propose that their enrichment in FGFR2 is driven by positive selection of the mutant spermatogonial progenitors, a mechanism analogous to that explaining why the canonical AS nucleotide substitutions also reach exceptionally high levels in sperm., ((c) 2008 Wiley-Liss, Inc.)

Root-specific promoters are valuable tools for targeting transgene expression, but many of those already described have limitations to their general applicability. We present the expression characteristics of SlREO, a novel gene isolated from tomato (Solanum lycopersicum L.). This gene was highly expressed in roots but had a very low level of expression in aerial plant organs. A 2.4-kb region representing the SlREO promoter sequence was cloned upstream of the uidA GUS reporter gene and shown to direct expression in the root cortex. In mature, glasshouse-grown plants this strict root specificity was maintained. Furthermore, promoter activity was unaffected by dehydration or wounding stress but was somewhat suppressed by exposure to NaCl, salicylic acid and jasmonic acid. The predicted protein sequence of SlREO contains a domain found in enzymes of the 2-oxoglutarate and Fe(II)-dependent dioxygenase superfamily. The novel SlREO promoter has properties ideal for applications requiring strong and specific gene expression in the bulk of tomato root tissue growing in soil, and is also likely to be useful in other Solanaceous crops.

A locus for triphalangeal thumb, variably associated with pre-axial polydactyly, was previously identified in the zone of polarizing activity regulatory sequence (ZRS), a long range limb-specific enhancer of the Sonic Hedgehog (SHH) gene at human chromosome 7q36.3. Here, we demonstrate that a 295T>C variant in the human ZRS, previously thought to represent a neutral polymorphism, acts as a dominant allele with reduced penetrance. We found this variant in three independently ascertained probands from southern England with triphalangeal thumb, demonstrated significant linkage of the phenotype to the variant (LOD = 4.1), and identified a shared microsatellite haplotype around the ZRS, suggesting that the probands share a common ancestor. An individual homozygous for the 295C allele presented with isolated bilateral triphalangeal thumb resembling the heterozygous phenotype, suggesting that the variant is largely dominant to the wild-type allele. As a functional test of the pathogenicity of the 295C allele, we utilized a mutated ZRS construct to demonstrate that it can drive ectopic anterior expression of a reporter gene in the developing mouse forelimb. We conclude that the 295T>C variant is in fact pathogenic and, in southern England, appears to be the most common cause of triphalangeal thumb. Depending on the dispersal of the founding mutation, it may play a wider role in the aetiology of this disorder.

Previous work where 9-cis-epoxycarotenoid dioxygenase (NCED) was over-expressed using the constitutive Gelvin Superpromoter resulted in mild increases in abscisic acid (ABA) accumulation, accompanied by stomatal closure and increased water-use efficiency (WUE), but with apparently little impact on long-term biomass production. However, one of the negative effects of the over-expression of NCED using constitutive promoters in tomato was increased seed dormancy. Here we report the use of the rbcS3C promoter, from a gene encoding the small subunit of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco), to drive LeNCED1 transgene expression in tomato in a light-responsive and circadian manner. In comparison to the constitutive promoter, the rbcS3C promoter allowed the generation of transgenic plants with much higher levels of ABA accumulation in leaves and sap, but the effect on seed dormancy was diminished. These plants displayed the expected reductions in stomatal conductance and CO(2) assimilation, but they also exhibited a severe set of symptoms that included perturbed cotyledon release from the testa, increased photobleaching in young seedlings, substantially reduced chlorophyll and carotenoid content, interveinal leaf flooding, and greatly reduced growth. These symptoms illustrate adverse consequences of long-term, very high ABA accumulation. Only more moderate increases in ABA biosynthesis are likely to be useful in the context of agriculture. Implications are discussed for the design of transgenic 'high ABA' plants that exhibit increased WUE but have minimal negative phenotypic effects.

A dozen years have passed since the first genetic lesion was identified in a family with craniosynostosis, the premature fusion of the cranial sutures. Subsequently, mutations in the FGFR2, FGFR3, TWIST1, and EFNB1 genes have been shown to account for approximately 25% of craniosynostosis, whilst several additional genes make minor contributions. Using specific examples, we show how these discoveries have enabled refinement of information on diagnosis, recurrence risk, prognosis for mental development, and surgical planning. However, phenotypic variability can present a significant challenge to the clinical interpretation of molecular genetic tests. In particular, the difficulty of analyzing the complex interaction of genetic background and prenatal environment in determining clinical features, limits the value of identifying low penetrance mutations., ((c) 2007 Wiley-Liss, Inc.)

We report an activating fibroblast growth factor receptor 3 (FGFR3) mutation (R248C) occurring in a verrucous epidermal naevus, and not found in other tissues, in a girl with mild facial dysmorphism. We demonstrate the presence of the mutation in keratinocytes cultured from the naevus and we speculate that a low level of the mutation in other tissues may account for her facial dysmorphism. The possibility that the mutation is present in other tissues implies a possible risk to her future offspring.

Overexpression of genes that respond to drought stress is a seemingly attractive approach for improving drought resistance in crops. However, the consequences for both water-use efficiency and productivity must be considered if agronomic utility is sought. Here, we characterize two tomato (Solanum lycopersicum) lines (sp12 and sp5) that overexpress a gene encoding 9-cis-epoxycarotenoid dioxygenase, the enzyme that catalyzes a key rate-limiting step in abscisic acid (ABA) biosynthesis. Both lines contained more ABA than the wild type, with sp5 accumulating more than sp12. Both had higher transpiration efficiency because of their lower stomatal conductance, as demonstrated by increases in delta(13)C and delta(18)O, and also by gravimetric and gas-exchange methods. They also had greater root hydraulic conductivity. Under well-watered glasshouse conditions, mature sp5 plants were found to have a shoot biomass equal to the wild type despite their lower assimilation rate per unit leaf area. These plants also had longer petioles, larger leaf area, increased specific leaf area, and reduced leaf epinasty. When exposed to root-zone water deficits, line sp12 showed an increase in xylem ABA concentration and a reduction in stomatal conductance to the same final levels as the wild type, but from a different basal level. Indeed, the main difference between the high ABA plants and the wild type was their performance under well-watered conditions: the former conserved soil water by limiting maximum stomatal conductance per unit leaf area, but also, at least in the case of sp5, developed a canopy more suited to light interception, maximizing assimilation per plant, possibly due to improved turgor or suppression of epinasty.

Overexpression of 9-cis-epoxycarotenoid dioxygenase (NCED) is known to cause abscisic acid (ABA) accumulation in leaves, seeds and whole plants. Here we investigated the manipulation of ABA biosynthesis in roots. Roots from whole tomato plants that constitutively overexpress LeNCED1 had a higher ABA content than wild-type (WT) roots. This could be explained by enhanced in situ ABA biosynthesis, rather than import of ABA from the shoot, because root cultures also had higher ABA content, and because tetracycline (Tc)-induced LeNCED1 expression caused ABA accumulation in isolated tobacco roots. However, the Tc-induced expression led to greater accumulation of ABA in leaves than in roots. This demonstrates for the first time that NCED is rate-limiting in root tissues, but suggests that other steps were also restrictive to pathway flux, more so in roots than in leaves. Dehydration and NCED overexpression acted synergistically in enhancing ABA accumulation in tomato root cultures. One explanation is that xanthophyll synthesis was increased during root dehydration, and, in support of this, dehydration treatments increased beta-carotene hydroxylase mRNA levels. Whole plants overexpressing LeNCED1 exhibited greatly reduced stomatal conductance and grafting experiments from this study demonstrated that this was predominantly due to increased ABA biosynthesis in leaves rather than in roots. Genetic manipulation of both xanthophyll supply and epoxycarotenoid cleavage may be needed to enhance root ABA biosynthesis sufficiently to signal stomatal closure in the shoot.

A dozen years have passed since the first genetic lesion was identified in a family with craniosynostosis, the premature fusion of the cranial sutures. Subsequently, mutations in the FGFR2, FGFR3, TWIST1, and EFNB1 genes have been shown to account for approximately 25% of craniosynostosis, whilst several additional genes make minor contributions. Using specific examples, we show how these discoveries have enabled refinement of information on diagnosis, recurrence risk, prognosis for mental development, and surgical planning. However, phenotypic variability can present a significant challenge to the clinical interpretation of molecular genetic tests. In particular, the difficulty of analyzing the complex interaction of genetic background and prenatal environment in determining clinical features, limits the value of identifying low penetrance mutations.

Craniofrontonasal syndrome (CFNS) is an X-linked disorder that exhibits a paradoxical sex reversal in phenotypic severity: females characteristically have frontonasal dysplasia, craniosynostosis, and additional minor malformations, but males are usually mildly affected with hypertelorism only. Despite this, males appear underrepresented in CFNS pedigrees, with carrier males encountered infrequently compared with affected females. To investigate these unusual genetic features of CFNS, we exploited the recent discovery of causative mutations in the EFNB1 gene, which encodes ephrin-B1, to survey the molecular alterations in 59 families (39 newly investigated and 20 published elsewhere). We identified the first complete deletions of EFNB1, catalogued 27 novel intragenic mutations, and used Pyrosequencing and analysis of nearby polymorphic alleles to quantify mosaic cases and to determine the parental origin of verified germline mutations. Somatic mosaicism was demonstrated in 6 of 53 informative families, and, of 17 germline mutations in individuals for whom the parental origin of mutation could be demonstrated, 15 arose from the father. We conclude that the major factor accounting for the relative scarcity of carrier males is the bias toward mutations in the paternal germline (which present as affected female offspring) combined with reduced reproductive fitness in affected females. Postzygotic mutations also contribute to the female preponderance, whereas true nonpenetrance in males who are hemizygous for an EFNB1 mutation appears unusual. These results highlight the importance of considering possible origins of mutation in the counseling of families with CFNS and provide a generally applicable approach to the combined analysis of mosaic and germline mutations.

Heterozygous mutations of the homeobox genes ALX4 and MSX2 cause skull defects termed enlarged parietal foramina (PFM) and cranium bifidum (CB); a single MSX2 mutation has been documented in a unique craniosynostosis (CRS) family. However, the relative mutational contribution of these genes to PFM/CB and CRS is not known and information on genotype-phenotype correlations is incomplete. We analysed ALX4 and MSX2 in 11 new unrelated cases or families with PFM/CB, 181 cases of CRS, and a single family segregating a submicroscopic deletion of 11p11.2, including ALX4. We explored the correlations between skull defect size and age, gene, and mutation type, and reviewed additional phenotypic manifestations. Four PFM cases had mutations in either ALX4 or MSX2; including previous families, we have identified six ALX4 and six MSX2 mutations, accounting for 11/13 familial, but only 1/6 sporadic cases. The deletion family confirms the delineation of a mental retardation locus to within 1.1 Mb region of 11p11.2. Overall, no significant size difference was found between ALX4- and MSX2-related skull defects, but the ALX4 mutation p.R218Q tends to result in persistent CB and is associated with anatomical abnormalities of the posterior fossa. We conclude that PFM caused by mutations in ALX4 and MSX2 have a similar prevalence and are usually clinically indistinguishable. Mutation screening has a high pickup rate in PFM, especially in familial cases, but is not indicated in CRS.

We report a family heterozygous for a newly identified mutation in the tyrosine kinase I domain of the FGFR2 gene (1576A > G, encoding the missense substitution Lys526Glu), associated with variable expressivity of Crouzon syndrome, including clinical nonpenetrance. Our observations expand both the clinical and molecular spectrum of this unusual subset of FGFR2 mutations.

Muenke syndrome, also known as FGFR3-associated coronal synostosis, is defined molecularly by the presence of a heterozygous nucleotide transversion, c.749C>G, encoding the amino acid substitution Pro250Arg, in the fibroblast growth factor receptor type 3 gene (FGFR3). This frequently occurs as a new mutation, manifesting one of the highest documented rates for any transversion in the human genome. To understand the biology of this mutation, we have investigated its parental origin, and the ages of the parents, in 19 families with de novo c.749C>G mutations. All ten informative cases originated from the paternal allele (95% confidence interval 74-100% paternal); the average paternal age at birth overall was 34.7 years. An exclusive paternal origin of mutations, and increased paternal age, were previously described for a different mutation (c.1138G>A) of the FGFR3 gene causing achondroplasia, as well as for mutations of the related FGFR2 gene causing Apert, Crouzon and Pfeiffer syndromes. We conclude that similar biological processes are likely to shape the occurrence of this c.749C>G mutation as for other mutations of FGFR3 as well as FGFR2., (Copyright 2004 Springer-Verlag)

In order to make the tomato genome more accessible for molecular analysis and gene cloning, we have produced 405 individual tomato (Lycopersicon esculentum) lines containing a characterized copy of pJasm13, a multifunctional T-DNA/modified Ds transposon element construct. Both the T-DNA and the Ds element in pJasm13 harbor a set of selectable marker genes to monitor excision and reintegration of Ds and additionally, target sequences for rare cutting restriction enzymes (I-PpoI, SfiI, NotI) and for site-specific recombinases (Cre, FLP, R). Blast analysis of flanking genomic sequences of 174 T-DNA inserts revealed homology to transcribed genes in 69 (40%), of which about half are known or putatively identified as genes and ESTs. The map position of 140 individual inserts was determined on the molecular genetic map of tomato. These inserts are distributed over the 12 chromosomes of tomato, allowing targeted and non-targeted transposon tagging, marking of closely linked genes of interest and induction of chromosomal rearrangements including translocations or creation of saturation-deletions or inversions within defined regions linked to the T-DNA insertion site. The different features of pJasm13 were successfully tested in tomato and Arabidopsis thaliana, thus providing a new tool for molecular/genetic dissection studies, including molecular and physical mapping, mutation analysis and cloning strategies in tomato and potentially, in other plants as well.

When plants encounter compacted soil, stomatal closure occurs and shoot growth slows. These responses occur in the absence of detectable changes in foliar water status. The use of genotypes with a reduced capacity to synthesize either ABA or ethylene has provided convincing evidence that ABA is responsible for providing the signal that regulates stomatal aperture, whereas increased ethylene production leads to an inhibition of shoot growth. Compaction results in an elevated export of ABA from the roots while enhanced ethylene synthesis is associated with increased expression of ACC oxidase in the aerial parts of the plant. Future work will explore the mechanisms responsible for regulating these events and the contribution of anaerobiosis to the stresses experienced by roots growing under compacted conditions.

The abscisic acid (ABA) biosynthetic pathway involves the formation of a 9-cis-epoxycarotenoid precursor. Oxidative cleavage then results in the formation of xanthoxin, which is subsequently converted to ABA. A number of steps in the pathway may control ABA synthesis, but particular attention has been given to the enzyme involved in the oxidative cleavage reaction, i.e. 9-cis-epoxycarotenoid dioxygenase (NCED). Cloning of a gene encoding this enzyme in maize was first reported in 1997. Mapping and DNA sequencing studies indicated that a wilty tomato mutant was due to a deletion in the gene encoding an enzyme with a very similar amino acid sequence to this maize NCED. The potential use of this gene in altering ABA content will be discussed together with other genes encoding ABA biosynthetic enzymes.

The tomato mutant notabilis has a wilty phenotype as a result of abscisic acid (ABA) deficiency. The wild-type allele of notabilis, LeNCED1, encodes a putative 9-cis-epoxycarotenoid dioxygenase (NCED) with a potential regulatory role in ABA biosynthesis. We have created transgenic tobacco plants in which expression of the LeNCED1 coding region is under tetracycline-inducible control. When leaf explants from these plants were treated with tetracycline, NCED mRNA was induced and bulk leaf ABA content increased by up to 10-fold. Transgenic tomato plants were also produced containing the LeNCED1 coding region under the control of one of two strong constitutive promoters, either the doubly enhanced CaMV 35S promoter or the chimaeric 'Super-Promoter'. Many of these plants were wilty, suggesting co-suppression of endogenous gene activity; however three transformants displayed a common, heritable phenotype that could be due to enhanced ABA biosynthesis, showing increased guttation and seed dormancy. Progeny from two of these transformants were further characterized, and it was shown that they also exhibited reduced stomatal conductance, increased NCED mRNA and elevated seed ABA content. Progeny of one transformant had significantly higher bulk leaf ABA content compared to the wild type. The increased seed dormancy was reversed by addition of the carotenoid biosynthesis inhibitor norflurazon. These data provide strong evidence that NCED is indeed a key regulatory enzyme in ABA biosynthesis in leaves, and demonstrate for the first time that plant ABA content can be increased through manipulating NCED.

Two genes encoding enzymes in the abscisic acid (ABA) biosynthesis pathway, zeaxanthin epoxidase (ZEP) and 9-cis-epoxycarotenoid dioxygenase (NCED), have previously been cloned by transposon tagging in Nicotiana plumbaginifolia and maize respectively. We demonstrate that antisense down-regulation of the tomato gene LeZEP1 causes accumulation of zeaxanthin in leaves, suggesting that this gene also encodes ZEP. LeNCED1 is known to encode NCED from characterization of a null mutation (notabilis) in tomato. We have used LeZEP1 and LeNCED1 as probes to study gene expression in leaves and roots of whole plants given drought treatments, during light/dark cycles, and during dehydration of detached leaves. During drought stress, NCED mRNA increased in both leaves and roots, whereas ZEP mRNA increased in roots but not leaves. When detached leaves were dehydrated, NCED mRNA responded rapidly to small reductions in water content. Using a detached leaf system with ABA-deficient mutants and ABA feeding, we investigated the possibility that NCED mRNA is regulated by the end product of the pathway, ABA, but found no evidence that this is the case. We also describe strong diurnal expression patterns for both ZEP and NCED, with the two genes displaying distinctly different patterns. ZEP mRNA oscillated with a phase very similar to light-harvesting complex II (LHCII) mRNA, and oscillations continued in a 48 h dark period. NCED mRNA oscillated with a different phase and remained low during a 48 h dark period. Implications for regulation of water stress-induced ABA biosynthesis are discussed.

The role of ethylene in regulating growth in tomato (Lycopersicon esculentum Mill.) during compaction stress was examined using wild-type (cv Ailsa Craig) and transgenic (ACO1(AS)) genotypes; the latter has a reduced capacity to produce ethylene. Ethephon or silver ions were applied to increase ethylene production or block its action. Shoot growth in both genotypes was comparable in uncompacted (1.1 g cm(-3)) and uniformly compacted soil (1.5 g cm(-3)). However, a 1.1/1.5-g cm(-3) split-pot treatment invoked marked genotypic differences: growth was reduced in cv Ailsa Craig but was comparable to uncompacted control plants in ACO1(AS). As xylem sap abscisic acid levels were similar, abscisic acid was not responsible for inhibiting growth in cv Ailsa Craig. These genotypic differences in growth were accompanied by increased ethylene evolution in cv Ailsa Craig, suggesting that the ability of ACO1(AS) to maintain growth in the split-pot treatment reflected its lower ethylene levels, a view supported by the observation that excising the roots in the compacted compartment reduced ethylene evolution and restored shoot growth in cv Ailsa Craig. Treatment with silver restored shoot growth in cv Ailsa Craig, whereas treatment with ethephon reduced growth in ACO1(AS). Thus, ethylene apparently has a key role in determining growth when tomato plants encounter differential soil compaction.

The notabilis (not) mutant of tomato has a wilty phenotype due to a deficiency in the levels of the plant hormone abscisic acid (ABA). The mutant appears to have a defect in a key control step in ABA biosynthesis--the oxidative cleavage of a 9-cis xanthophyll precursor to form the C15 intermediate, xanthoxin. A maize mutant, viviparous 14 (vp14) was recently obtained by transposon mutagenesis. This maize genetic lesion also affects the oxidative cleavage step in ABA synthesis. Degenerate primers for PCR, based on the VP14 predicted amino acid sequence, have been used to provide probes for screening a wilt-related tomato cDNA library. A full-length cDNA clone was identified which is specific to the not gene locus. The ORFs of the tomato cDNA and maize Vp14 are very similar, apart from parts of their N-terminal sequences. The not mutation has been characterized at the DNA level. A specific A/T base pair deletion of the coding sequence has resulted in a frameshift mutation, indicating that not is a null mutant. This observation is discussed in connection with the relatively mild phenotype exhibited by not mutant homozygotes.

The protean manifestations of the clinical presentation of carcinoma of the lung are well known. In the following case report we describe an unusual presentation of such a carcinoma. We further describe this occurrence in Latin as befits what we believe to be a new presentation.

The ABA biosynthetic pathway has been studied in detail and the steps impaired in some ABA-deficient mutants are known. However, little is known of the molecular control mechanisms regulating ABA production in planta. A direct route for improving our understanding of these mechanisms is to transposon tag and clone the wild-type counterparts of the ABA mutant alleles. On the basis of the observation that maize transposons move preferentially to linked sites in both homologous and heterologous systems and in doing so disrupt gene function, a targeted transposon mutagenesis strategy is being developed towards cloning ABA biosynthetic genes from tomato. The possibility of using marker genes to identify T-DNA insertion sites in selected parts of the genome has been examined and compared with an inverse PCR/RFLP approach to mapping T-DNAs.

The metabolism of deuterium-labelled analogues of ABA by normal and flacca mutant tomato plants was investigated. Comparison of the biological activity of ABA, ABA alcohol, ABA aldehyde and their 2-trans isomers was made in both mutant and non-mutant genotypes. While in normal plants ABA alcohol and ABA aldehyde were as effective as ABA in inducing stomatal closure, in the flacca mutants only ABA itself was biologically active. Both ABA alcohol and ABA aldehyde were converted to the inactive compound trans- ABA alcohol instead of ABA when fed to flacca plants. As trans-ABA aldehyde was also readily converted to trans-ABA alcohol by flacca plants, it was not possible to establish whether isomerization precedes reduction or vice versa in the synthesis of trans-ABA alcohol from ABA aldehyde.

Two tomato mutants, Lycopersicon esculentum flacca and lateral suppressor, are assigned to map position 59 of chromosome 7. The tight linkage between these two gene loci was detected as a result of attempts to establish whether they would exhibit phenotypic interaction. The possibility that both mutants result in abnormalities of abscisic acid (ABA) accumulation is considered. ABA analysis supports the suggestion that plants homozygous for flacca have a substantially lower concentration but indicates that lateral suppressor homozygotes do not differ from normal in ABA content. An attempt is made to reconcile the results with those of Tucker (1976, New. Phytol. 77, 561-568) by suggesting that lateral suppressor plants may accumulate high levels of an ABA metabolite which is indistinguishable from ABA using the Commelina epidermal strip bioassay.

A new abscisic acid (ABA) analogue has been isolated from tomato plants. High levels of the compound are found in flacca mutants compared with normal isogenic controls. The analogue also accumulates in response to water stress. Three alternative structures, consistent with the mass spectrum, have been proposed. The possibility that the compound may be a biosynthetic precursor of ABA is considered.

A series of double mutant homozygotes have been produced from three wilty tomato mutants; flacca, sitiens and notabilis. The phenotypic interaction between the mutant genes has been studied. The severity of phenotype in the double mutants does not correspond to that predicted from the single mutant homozygotes. The results are discussed in relation to the probable involvement of the mutants in abscisic acid metabolism.

An attempt has been made to construct a genetic bridge between the cultivated tomato, Lycopersicon esculentum and its wild relatives L. peruvianum and L. chilense. A complex interspecific hybrid genotype SB 2 has been assembled which shows strong sexual compatibility with both L. esculentum and L. chilense, and a rather weaker degree of compatibility with one specific race of L. peruvianum. The crossing relations of a hybrid between SB 2 and L. peruvianum have also been investigated. This hybrid retains a high level of sexual compatibility with L. esculentum and only shows a slight increase in its ability to set seed on the L. peruvianum parent.