Sodium voltage-gated channel alpha subunit 9 mutation in epilepsy

In humans, gene mutations in voltage-gated sodium channels can cause a range of epileptic symptoms, including genetic (generalized) epilepsy with febrile seizures plus (GEFS+) and Dravet syndrome (DS). The SCN9A is a member of the SCN9 gene family that encodes sodium transporter proteins. In the current case report, we delineate a 12-year-old patient who was referred to a pediatric neurology clinic for infantile-onset generalized epileptic seizures and progressive neurodevelopmental delay. Novel heterozygous mutations c.4702A>C (p.Asn1568His) in the SCN9A gene, and c.65G>A (p.Arg22Gln) in the MLC1 gene were detected using targeted next-generation gene sequencing. The replacement of Histidine (His) with Asparagine (Asn) at position 1568 in the topological domain of SCN9A channel protein provides new insights into the impaired excitation and inactivation patterns of sodium channels. The case report adds this new patient with genetic link of SCN9A variants with progressive myoclonic epilepsy and cognitive difficulties.

Cry genes profiling and the toxicity of isolates of Bacillus thuringiensis from soil samples against American bollworm, Helicoverpa armigera

AIMS

 The aim of this study was to search for Bacillus thuringiensis (Bt) harbouring cry1A gene which could effectively control cotton pest, American bollworm, Helicoverpa armigera.

METHODS AND RESULTS

 cry gene profiling of 50 Bt isolates showed the presence of cry1, cry2, cry3, cry4, cry7, cry8 and cry9 genes. None of the isolates harboured cry1 gene alone. It was always found in combination with cry3. There was no isolate positive for cry10 gene. Considering isolates with single cry genes, the frequency of cry4 was predominant (22%) followed cry2 (6%), cry3 (4%) and cry8 (2%). Isolates having two cry genes in combination had 14% incidence for cry2 + cry4, 12% for cry3 + cry4 and 10% for cry1 + cry3. The most dominant three gene linkage was cry1 + cry3 + cry4. Further profiling of cry1 gene showed that cry1K gene was abundantly present in all combinations such as cry1A, cry1D, cry1F and cry1I. However, cry1C existed independent of other subtypes. Finally, the Bt isolates with cry1A were analyzed for 16S rRNA gene, which showed two distinct groups of isolates on the basis of sequence homology. Bioassays of spore-crystal mixtures of SBS-Bt4, 8, 17, 21 and 26 harbouring cry1 against neonate larvae of H. armigera showed LC(50) 1288, 1202, 467·7, 524·8 and 108·5 μg ml(-1) . The SBS-Bt26 showed fourfold higher toxicity than the cry 1Ac harbouring positive control, HD-73.

CONCLUSIONS

  None of the isolates harboured single cry 1 gene. They were always in combination of two or three genes. A Bt isolate (Bt26) had fourfold higher toxicity against H. armigera larvae compared with the positive control HD 73 and hence can be commercially exploited to control insect pest.

SIGNIFICANCE AND IMPACT OF THE STUDY

  The inter relationship between the cry genes content and the toxicity may allow better understanding of Bt ecology.