A fluorimetric assay for succinic semialdehyde dehydrogenase activity suitable for prenatal diagnosis of the enzyme deficiency

Phytosulfokine α (PSKα) delays senescence and reinforces SUMO1/SUMO E3 ligase SIZ1 signaling pathway in cut rose flowers (Rosa hybrida cv. Angelina)

Roses are widely used as cut flowers worldwide. Petal senescence confines the decorative quality of cut rose flowers, an impressively considerable economic loss. Herein, we investigated the SUMO1/SUMO E3 ligase SIZ1 signaling pathway during bud opening, and petal senescence of cut rose flowers. Our results exhibited that the higher expression of SUMO1 and SUMO E3 ligase SIZ1 during bud opening was accompanied by lower endogenous H2O2 accumulation arising from higher expression and activities of SOD, CAT, APX, and GR, promoting proline accumulation by increasing P5CS expression and activity and enhancing GABA accumulation by increasing GAD expression and activity. In harvested flowers, lower expressions of SUMO1 and SUMO E3 ligase SIZ1 during petal senescence were associated with higher endogenous H2O2 accumulation due to lower expression and activities of SOD, CAT, APX, and GR. Therefore, promoting the activity of the GABA shunt pathway as realized by higher expression and activities of GABA-T and SSADH accompanied by increasing OAT expression and activity for sufficiently supply proline in rose flowers during petal senescence might serve as an endogenous antisenescence mechanism for slowing down petals senescence by avoiding endogenous H2O2 accumulation. Following phytosulfokine α (PSKα) application, postponing petal senescence in cut rose flowers could be ascribed to higher expression of SUMO1 and SUMO E3 ligase SIZ1 accompanied by higher expression and activities of SOD, CAT, APX, and GR, higher activity of GABA shunt pathway as realized by higher expression and activities of GAD, GABA-T, and SSADH, higher expression and activities of P5CS and OAT for supplying proline and higher expression of HSP70 and HSP90. Therefore, our results highlight the potential of the PSKα as a promising antisenescence signaling peptide in the floriculture industry for postponing senescence and extending the vase life of cut rose flowers.

Succinic semialdehyde dehydrogenase deficiency (SSADH) (4-hydroxybutyric aciduria, gamma-hydroxybutyric aciduria)

Succinic semialdehyde dehydrogenase deficiency is one of the disorders of GABA metabolism, so it is not surprising that seizures occur as one of the symptoms in affected patients. Other features that are described include delayed development, hypotonia, myopathy with ragged red fibres, abnormal behaviour, and ocular abnormalities. Neonatal problems include prematurity, respiratory difficulties, and hypoglycaemia. The responsible gene has been identified on the short arm of chromosome 6. There are many mutations, and there is poor genotype-phenotype correlation resulting in difficulties in diagnosis. The pathogenesis of the condition is discussed, especially the results of the disturbed GABA catabolism, and the production of the gamma-hydroxybutyric acid. The many properties of this substance suggest it may act as a neurotransmitter or neuromodulator in the brain. The diagnosis may be difficult as the clinical picture is not really suggestive, but the MRI examination can help if it shows abnormalities in the globus pallidus. It will be confirmed by finding an excess of 4-hydroxybutyric acid in the body fluids; and the methods of estimation are discussed. Prenatal diagnosis is possible using a combination of methods. Treatment possibilities are limited. Vigabatrin should be of value as it is an inhibitor of GABA transaminase, but results have been disappointing. Symptomatic treatment may well be needed for control of seizures, abnormal behaviour and other disorders; and special educational needs must be served.

Prenatal diagnosis of succinic semialdehyde dehydrogenase deficiency: increased accuracy employing DNA, enzyme, and metabolite analyses

Inherited succinic semialdehyde dehydrogenase (SSADH; EC1.2.1.24; McKusick 271980) deficiency is a defect of GABA degradation which leads to accumulation of 4-hydroxybutyric acid (gamma-hydroxybutyric acid; GHB) in physiologic fluids of patients. Prenatal diagnosis (PND) was performed in three at-risk pregnancies employing combinations of: (1) reverse-transcription-polymerase chain reaction (RT-PCR) and genomic DNA amplification followed by sequencing using isolated leukocytes or cultured human lymphoblasts; (2) GHB quantitation in amniotic fluid; or (3) SSADH enzyme assay in chorionic villus (CV) and/or amniocytes. In two pregnancies, all analyses were concordant for prediction of disease status in the fetus. In the third case, enzyme activity in CV (deficient) and metabolite analysis in amniotic fluid (normal) were discordant. For clarification, mutation analysis was undertaken in CV, confirming heterozygosity for the mutation previously identified in the proband. We hypothesize that delayed transit time for shipment of CV between Greece and the United States (8 days) led to enhanced degradation of heterozygous SSADH enzyme activity. Our data demonstrate the importance of combined metabolite, enzyme, and DNA analysis for increased accuracy in the PND of SSADH deficiency.

Succinic semialdehyde dehydrogenase deficiency: low excretion of metabolites in a neonate

A neonate at risk for succinic semialdehyde dehydrogenase deficiency was investigated on day 1. The urine level of 4-hydroxybutyrate was only slightly elevated (23 mumol/mmol of creatinine; controls 1.6-14, n = 18). This value was considerably less than those found for older children with succinic semialdehyde dehydrogenase deficiency and made interpretation of the result uncertain. The diagnosis of succinic semialdehyde dehydrogenase deficiency was confirmed by enzyme assay, and repeat urine testing showed a steady increase in the level of 4-hydroxybutyrate to 359 mumol/mmol at 6 months.

Pre- and postnatal diagnosis of succinic semialdehyde dehydrogenase deficiency using enzyme and metabolite assays

We report our cumulative experience for the prenatal diagnosis of succinic semialdehyde dehydrogenase (SSADH) deficiency in seven 'at-risk' pregnancies from four unrelated families. Prenatal diagnosis was performed by determination of 4-hydroxybutyric acid (4-HBA) concentration in amniotic fluid using isotope-dilution gas chromatography-mass spectrometry in conjunction with assay of SSADH activity in biopsied chorionic villus and/or cultured amniocytes. In three of four pregnancies predicted as affected, confirmation was obtained by demonstration of deficient SSADH activity in fetal tissues. Our results suggest that determination of 4-HBA concentration in amniotic fluid combined with enzyme determination in cultured or biopsied tissue represents a reliable method for the prenatal diagnosis of SSADH deficiency.,