Methodology is described for the creation of a molecular assembly consisting of the enzyme alkaline phosphatase immobilized onto a glass surface using a biotinylated conjugated copolymer, poly(3-undecylthiophene-co-3-thiophenecarboxaldehyde) 6-biotinamidohexanohydrazone. The biotinylated polymer is attached to the inside walls of a silanized glass capillary via hydrophobic interactions, and a streptavidin-conjugated alkaline phosphatase is interfaced with the polymer through the classical biotin-streptavidin interaction. Utilizing a simple optical setup, we can detect the activity of as little as approximately 0.1 fmol of alkaline phosphatase with this molecular assembly. The assembly is mechanically robust and retains the majority of bound enzyme activity for up to 30 days. We have utilized this molecular assembly for the detection of organophosphorus-based pesticides. Both paraoxon and methyl parathion inhibit the enzyme-mediated generation of chemiluminescence signal. We are able to detect paraoxon and methyl parathion concentrations down to 500-700 ppb.

Alkaline Phosphatase↗

PubMedDate not supplied

Chemiluminescence-based inhibition kinetics of alkaline phosphatase in the development of a pesticide biosensor.

The use and application of the enzyme alkaline phosphatase in a chemiluminescence assay are discussed. The enzyme catalyzes the hydrolysis of a macrocyclic phosphate compound generating a chemiluminescence signal. On the basis of inhibition of this signal, a methodology for the detection and quantitation of organophosphorus-based pesticides has been developed. The methodology is studied with alkaline phosphatase in the bulk aqueous phase, and detection of the signal is accomplished by a simple optical setup. Parts per billion level detection of paraoxon and methyl parathion in bulk solutions is achieved. The technique is rapid and sensitive and is applicable to the detection of most organophosphorus-based pesticides. The results from kinetic studies indicate a mixed type of inhibition of the enzyme by paraoxon and methyl parathion. The detection methodology forms an integral part of a biosensor under development and is adaptable to incorporating optical fibers for remote detection of pesticides.

Adamantane↗

PubMedDate not supplied

Dyschromatosis universalis hereditaria: a unique disorder.

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Child↗

PubMedDate not supplied

Isolation of drug-resistant tubercle bacilli in cutaneous tuberculosis.

Cutaneous tuberculosis in a teenage boy that did not respond to conventional antitubercular therapy is described. Mycobacterium tuberculosis was recovered on culture and found to be resistant to rifampicin and isoniazid. Gradual regression of the lesions was observed after the addition of streptomycin and ethambutol. Later streptomycin was stopped and the boy was advised to continue ethambutol along with ofloxacin and thioacetazone until complete regression was achieved.

Adolescent↗

PubMedDate not supplied

A major gene for time of flowering in chickpea.

A major gene for the number of days from sowing to appearance of the first flower (time of flowering) was identified in a cross between an extrashort duration chickpea (Cicer arietinum L.) variety, ICCV 2, and a medium duration variety, JG 62. The F2 population was advanced through the single-seed-descent method to develop random recombinant inbred lines (RILs). Time of flowering was recorded for the parents and 66 F(6) RILs from this cross that were grown in a Vertisol field in the post-rainy season of 1996-1997. Similarly the parents, F(1) and F(10) RILs were evaluated in 1997-1998. The F(1) flowered along with JG 62. The time of flowering for the two sets of RILs showed bimodal distributions with nearly equal peaks. One peak corresponded with ICCV 2 and the other with JG 62. This suggests that a single gene controls the difference for the time of flowering between ICCV 2 and JG 62 and the allele carried by the latter parent is dominant. To our knowledge no gene has been identified for the time of flowering in chickpea. Therefore the allele carried by JG 62 is designated as Efl-1 and that by ICCV 2 as efl-1. The proposed genotype for ICCV 2 is efl-1 efl-1 and for JG 62 is Efl-1 Efl-1. The genotype efl-1 efl-1 reduces the time of flowering at ICRISAT by nearly 3 weeks. The significance of this gene for breeding for early maturity and genome mapping has been discussed.

Crosses, Genetic↗

PubMedDate not supplied

Penetrance and expressivity of the gene for double podding in chickpea.

The double-pod per peduncle trait is known to contribute to increased seed yield in chickpea (Cicer arietinum L.). A cross was made between the single-podded variety ICCV 2 and the double-podded variety JG 62 in 1993. Penetrance and expressivity of the gene for double podding was studied in an F2 population and F10 recombinant inbred lines (RILs) of this cross. Homozygous recessive allele of this gene (ss) governs the production of double flowers and pods per peduncle. Results indicated that the s allele has unstable penetrance and variable expressivity. The penetrance of this allele was 53% for the F2 and 84.5% for the RILs. The ranges for the expression of this trait among the penetrant F2 individuals and the penetrant RILs were 1.1-14.8% and 0.1-33.0%. These were 8.3-30.8% for early sown and 17.1-68.7% for the late sown double-podded parent JG 62. Thus it appears that the allele shows greater penetrance and enhanced expressivity under soil moisture stress. In the F2 the seed yield advantage of the double-podded over the single-podded plants was 18%, whereas among the RILs it was 7%. The increased number of pods and seeds contributed to the higher yield. However, there was a slight decrease in seed size of the double-podded genotypes. An increase in the size of seed may have a role in the decreased penetrance and expressivity of this allele among the double-podded segregants of the ICCV 2 x JG 62 chickpea cross.

Alleles↗

PubMedDate not supplied

Inheritance of flower color in chickpea.

Flower color is a useful morphological marker in chickpea (Cicer arietinum L.). Inheritance of this trait was studied using two white-flowered chickpea genotypes, P 9623 and RS 11, and one blue-flowered genotype, T 39-1. The genetic constitutions of the white flower colors of P 9623 and RS 11 were different, for in an earlier study their F1 produced pink flowers. The two F1s of the crosses P 9623 x T 39-1 and RS 11 x T 39-1 also produced pink flowers. Each of the two F2 populations segregated in 9 pink:3 blue:4 white-flowered plants. These results can be explained by a three-gene model. These three independently segregating genes are probably the same as C, B, and P reported in the literature earlier. Allelic tests could not be undertaken, as the genetic stocks used in the earlier studies are not available. The genetic constitutions of the three parents and their F1s are proposed. These accessions should be useful for conducting allelic tests for determining flower color loci in chickpea and for comparative studies with field pea. The seeds of these genetic stocks are maintained at the Genetic Resources and Enhancement Program at ICRISAT and are available for research purposes on request.

Alleles↗