Intrinsic multiple antibiotic resistance markers for competitive and effectiveness studies with various strains of mung bean rhizobia

Ten strains ofRhizobium sp. with multiple antibiotic resistance markers were used for competitive and ef ficiency studies with mung bean var. ML 5. All the strains showed significant increase in grain yield and so also for nitrogenase activity except MO 5. Nitrogenase activity correlated very well with grain yeild. The compatibility of strains varied from 17 to 50%. The intrinsic multiple antibiotic markers for strain identification were found to be stable after passing through soil and host conditions and could be used for ecological studies. It was further revealed that the overall efficiency of a strain is the combined effect of characters like compatability, competitiveness and inherent capacity to fix nitrogen.     

Novel nucleotide insertions in two unrelated Indian patients with 5α reductase 2 deficiency leading to premature termination of SRD5A2 enzyme

T is converted to a more potent androgen, DHT by the action of microsomal membrane enzyme 5α reductase 2. Defects in 5α reductase 2 isozyme results in incomplete virilisation of external male genitalia. Mutations in SRD5A2 gene leads to diminished enzyme activity, thus hampering DHT synthesis from T. We describe two unrelated patients from India with 5αRD2 due to novel insertion of nucleotides in the exon 1 of SRD5A2 gene that lead to premature termination of protein. Master S (case 1; III.8) was 3 years old at initial evaluation, had perineoscrotal hypospadias, microphallus and both testes were palpable in the inguinal region. Master P (case 2; III.9) was born as normal full term baby. He had primary complaint of microphallus, penoscrotal hypospadias and gonads in the inguinal region. Diagnosis of 5αRD2 was made, as T/DHT ratio in the two cases was 41 and 131.2 respectively. Sequence analysis of SRD5A2 gene showed an insertion of nucleotides TA in exon 1 (c.188_189). This resulted in premature termination of the protein due to stop codon at amino acid position 7. The protein formed is drastically truncated and inadequate protein synthesized explains the phenotypic characteristics of our patients.     

Regeneration via somatic embryogenesis from leaf basal segments and genetic transformation of bread and emmer wheat by particle bombardment

Direct gene transformation methods such as microprojectile bombardment have been successfully employed for obtaining transgenics in cereals in general and wheat in particular. As success of any transformation strategy depends largely upon the regeneration capability of the target explant, the present investigation employs leaf basal segments to achieve high regeneration response via somatic embryogenesis. Basal segments of 5-day-old seedlings of T. aestivum var. CPAN1676 and T. dicoccum var. DDK1001 were cultured on callusing medium for 3 weeks at 26 ± 1 °C, discontinuous light followed by a culture period of 15 days at 21 ± 1 °C in continuous light. The calli were then transferred to auxin-free medium for regeneration in discontinuous light at 26 ± 1 °C. Regeneration via somatic embryogenesis was observed within 2 weeks in T. aestivum var. CPAN1676 and T. dicoccum var. DDK1001 (68 and 82%, respectively). This embryogenic calli were employed further to obtain hygromycin resistance by particle bombardment in T. aestivum and T. dicoccum. A transformation efficiency of 8.6, 7.5 and 4.9% was obtained in T. aestivum var. CPAN1676, PBW343 and T. dicoccum DDK1001, respectively. Presence of the transgene hptII (hygromycin) in T ₀ plants was confirmed by Southern hybridization.