Renu Kumari

New insight-guided approaches to detect, cure, prevent and eliminate malaria

New challenges posed by the development of resistance against artemisinin-based combination therapies (ACTs) as well as previous first-line therapies, and the continuing absence of vaccine, have given impetus to research in all areas of malaria control. This review portrays the ongoing progress in several directions of malaria research. The variants of RTS,S and apical membrane antigen 1 (AMA1) are being developed and test adapted as multicomponent and multistage malaria control vaccines, while many other vaccine candidates and methodologies to produce antigens are under experimentation. To track and prevent the spread of artemisinin resistance from Southeast Asia to other parts of the world, rolling circle-enhanced enzyme activity detection (REEAD), a time- and cost-effective malaria diagnosis in field conditions, and a DNA marker associated with artemisinin resistance have become available. Novel mosquito repellents and mosquito trapping and killing techniques much more effective than the prevalent ones are undergoing field testing. Mosquito lines stably infected with their symbiotic wild-type or genetically engineered bacteria that kill sympatric malaria parasites are being constructed and field tested for stopping malaria transmission. A complementary approach being pursued is the addition of ivermectin-like drug molecules to ACTs to cure malaria and kill mosquitoes. Experiments are in progress to eradicate malaria mosquito by making it genetically male sterile. High-throughput screening procedures are being developed and used to discover molecules that possess long in vivo half life and are active against liver and blood stages for the fast cure of malaria symptoms caused by simple or relapsing and drug-sensitive and drug-resistant types of varied malaria parasites, can stop gametocytogenesis and sporogony and could be given in one dose. Target-based antimalarial drug designing has begun. Some of the putative next-generation antimalarials that possess in their scaffold structure several of the desired properties of malaria cure and control are exemplified by OZ439, NITD609, ELQ300 and tafenoquine that are already undergoing clinical trials, and decoquinate, usnic acid, torin-2, ferroquine, WEHI-916, MMV396749 and benzothiophene-type N-myristoyltransferase (NMT) inhibitors, which are candidates for future clinical usage. Among these, NITD609, ELQ300, decoquinate, usnic acid, torin-2 and NMT inhibitors not only cure simple malaria and are prophylactic against simple malaria, but they also cure relapsing malaria.

Interaction between COCHLEATA and UNIFOLIATA genes enables normal flower morphogenesis in the garden pea, Pisum sativum

2009).Some important regulatory steps in the pathways of stipuleand leaf development have been defined. Each vegetative andflower bearing node produces two stipules, one on each sideof the leaf. Formation of a stipule at a node is autonomousof that of the leaf and other stipule at that node. Stipuleprimordium is initiated by the function of

Genetic control of leaf-blade morphogenesis by the INSECATUS gene in Pisum sativum

To understand the role of INSECATUS (INS) gene in pea, the leaf blades of wild-type, ins mutant and seven other genotypes, constructed by recombining ins with uni-tac, af, tl and mfp gene mutations, were quantitatively compared. The ins was inherited as a recessive mutant allele and expressed its phenotype in proximal leaflets of full size leaf blades. In ins leaflets, the midvein development was arrested in distal domain and a cleft was formed in lamina above this point. There was change in the identity of ins leaflets such that the intercalary interrupted midvein bore a leaf blade. Such adventitious blades in ins, ins tl and ins tl mfp were like the distal segment of respective main leaf blade. The ins phenotype was not seen in ins af and ins af uni-tac genotypes. There was epistasis of uni-tac over ins. The ins, tl and mfp mutations interacted synergistically to produce highly pronounced ins phenotype in the ins tl mfp triple mutant. The role(s) of INS in leaf-blade organogenesis are: positive regulation of vascular patterning in leaflets, repression of UNI activity in leaflet primordia for ectopic growth and in leaf-blade primordium for indeterminate growth of rachis, delimitation of proximal leaflet domain and together with TL and MFP homeostasis for meristematic activity in leaflet primordia. The variant apically bifid shape of the affected ins leaflets demonstrated that the leaflet shape is dependent on the venation pattern.

Genetics of dioecy and causal sex chromosomes in plants

Dioecy (separate male and female individuals) ensures outcrossing and is more prevalent in animals than in plants. Although it is common in bryophytes and gymnosperms, only 5% of angiosperms are dioecious. In dioecious higher plants, flowers borne on male and female individuals are, respectively deficient in functional gynoecium and roecium. Dioecy is inherited via three sex chromosome systems: XX/XY, XX/X0 and WZ/ZZ, such that XX or WZ is female and XY, X0 or ZZ are males. The XX/XY system generates the rarer XX/X0 and WZ/ZZ systems. An autosome pair begets XY chromosomes. A recessive loss-of-androecium mutation (ana) creates X chromosome and a dominant gynoecium-suppressing (GYS) mutation creates Y chromosome. The ana/ANA and gys/GYS loci are in the sex-determining region (SDR) of the XY pair. Accumulation of inversions, deleterious mutations and repeat elements, especially transposons, in the SDR of Y suppresses recombination between X and Y in SDR, making Y labile and increasingly degenerate and heteromorphic from X. Continued recombination between X and Y in their pseudoautosomal region located at the ends of chromosomal arms allows survival of the degenerated Y and of the species. Dioecy is presumably a component of the evolutionary cycle for the origin of new species. Inbred hermaphrodite species assume dioecy. Later they suffer degenerate-Y-led population regression. Cross-hybridization between such extinguishing species and heterologous species, followed by genome duplication of segregants from hybrids, give rise to new species.

Novel mutations in typical and atypical genetic loci through exome sequencing in autosomal recessive cerebellar ataxia families.

Nearly a thousand mutations mapping to 60 different loci have been identified in cerebellar ataxias. However, almost 50% of the cases remain genetically uncharacterized and there is a difference in prevalence as well as in the phenotypic spectrum of ataxia among various geographical regions. This poses a challenge for setting up a genetic panel for screening ataxia. In our ataxic cohort of 1014 families, 61% are genetically uncharacterized (UC). We investigated the potential of whole exome sequencing in conjunction with homozygosity mapping (HM) to delineate the genetic defects in three uncharacterized families with recessive inheritance each manifesting some unusual phenotype: (i) infantile onset ataxia with hearing loss (IOAH), (ii) Juvenile onset cerebellar ataxia with seizures (JCS) and (iii) Friedreich ataxia‐like (FA‐like). We identified a novel missense mutation in c10orf2 in the family with IOAH, compound heterozygous mutations in CLN6 in the family with JCS and a homozygous frame‐shift mutation in SACS in the FA‐like patient. Phenotypes observed in our families were concordant with reported phenotypes of known mutations in the same genes thus obviating the need for functional validation. Our study revealed novel variations in three genes, c10orf2, CLN6, and SACS, that have so far not been reported in India. This study also demonstrates the utility of whole exome screening in clinics for early diagnosis.

Development of Improved Horticultural Genotypes Characterized by Novel Over-Flowering Inflorescence Trait in Periwinkle Catharanthus roseus

Floricultural genotypes with new plant architecture were developed in the seasonal/perennial garden plant Catharanthus roseus. The new genotypes were developed by crossing the double mutant line lli egd of C. roseus with two horticultural lines of C. roseus and a line of Catharanthus trichophyllus. As compared to the normal LLI inflorescence architecture in which racemose inflorescence had pairs of flowers subtended by one of the two leaves per node, the lli inflorescence of the new lines was excessively branched and each branch had two flowers per node which were bereft of subtending leaves. The new lines are novel in displaying several fold increased number of flowers on inflorescence unhindered by leaves. In the new floricultural lines the over-flowering lli trait was combined with variation in plant height, petal and eye colors and tolerance to the common fungal diseases.

Exome sequencing reveals a novel mutation, p.L325H, in the KRT5 gene associated with autosomal dominant Epidermolysis Bullosa Simplex Koebner type in a large family from western India.

We report a large, non-consanguineous family comprising five generations of individuals residing in Gujarat, India affected with localized Epidermolysis Bullosa Simplex (EBS) Koebner type. We analyzed 14 individuals including 9 affected individuals from this family. Exome sequencing in two cases suggested a novel non-synonymous variation, p.L325H, in the KRT5 gene. The present analysis also reports the first causative mutation of EBS Koebner type from India.

Genetic interaction and mapping studies on the leaflet development (lld) mutant in Pisum sativum

In Pisum sativum, the completely penetrant leaflet development (lld) mutation is known to sporadically abort pinnae suborgans in the unipinnate compound leaf. Here, the frequency and morphology of abortion was studied in each of the leaf suborgans in 36 genotypes and in presence of auxin and gibberellin, and their antagonists. Various lld genotypes were constructed by multifariously recombining lld with a coch homeotic stipule mutation and with af, ins, mare, mfp, tl and uni-tac leaf morphology mutations. It was observed that the suborgans at all levels of pinna subdivisions underwent lld-led abortion events at different stages of development. As in leafblades, lld aborted the pinnae in leaf-like compound coch stipules. The lld mutation interacted with mfp synergistically and with other leaf mutations additively. The rod-shaped and trumpet-shaped aborted pea leaf suborgans mimicked the phenotype of aborted leaves in HD-ZIP-III-deficient Arabidopsis thaliana mutants. Suborganwise aborted morphologies in lld gnotypes were in agreement with basipetal differentiation of leaflets and acropetal differentiation in tendrils. Altogether, the observations suggested that LLD was the master regulator of pinna development. On the basis of molecular markers found linked to lld, its locus was positioned on the linkage group III of the P. sativum genetic map.

Ancestral Variations of the PCDHG Gene Cluster Predispose to Dyslexia in a Multiplex Family

Dyslexia is a heritable neurodevelopmental disorder characterized by difficulties in reading and writing. In this study, we describe the identification of a set of 17 polymorphisms located across 1.9 Mb region on chromosome 5q31.3, encompassing genes of the PCDHG cluster, TAF7, PCDH1 and ARHGAP26, dominantly inherited with dyslexia in a multi-incident family. Strikingly, the non-risk form of seven variations of the PCDHG cluster, are preponderant in the human lineage, while risk alleles are ancestral and conserved across Neanderthals to non-human primates. Four of these seven ancestral variations (c.460A > C [p.Ile154Leu], c.541G > A [p.Ala181Thr], c.2036G > C [p.Arg679Pro] and c.2059A > G [p.Lys687Glu]) result in amino acid alterations. p.Ile154Leu and p.Ala181Thr are present at EC2: EC3 interacting interface of γA3-PCDH and γA4-PCDH respectively might affect trans-homophilic interaction and hence neuronal connectivity. p.Arg679Pro and p.Lys687Glu are present within the linker region connecting trans-membrane to extracellular domain. Sequence analysis indicated the importance of p.Ile154, p.Arg679 and p.Lys687 in maintaining class specificity. Thus the observed association of PCDHG genes encoding neural adhesion proteins reinforces the hypothesis of aberrant neuronal connectivity in the pathophysiology of dyslexia. Additionally, the striking conservation of the identified variants indicates a role of PCDHG in the evolution of highly specialized cognitive skills critical to reading.

Lychee-Associated Hypoglycaemic Encephalopathy: A New Disease of Children Described in India

Fruits of lychee tree ( Litchi sinensis ), extensively horticultured in India, China and many other countries, are delicious and possess many nutritious and medicinal properties. In India and other Asian countries, in lychee harvest season, outbreaks have been occurring of rapidly developing hypoglycaemia, encephalopathy, seizures and cerebral oedema in young children when they ingest lychee fruit arils in large numbers on empty stomach. It has been shown that the acute neurological illness is hypoglycaemic encephalopathy, caused by the actions of hypoglycin A (HGA) and methylenecyclopropylglycine (MCPG), the non-protein l -amino acids present in the edible arils of lychee fruits. Both HGA and MCPG phytotoxins are known to disrupt the pathways of β-fatty acid oxidation and gluconeogenesis in human body cells, result in accumulation of many undesirable metabolites of the blocked energy generating pathways, and altogether produced the often fatal hypoglycaemic illness. Here, the related work is summarized and commented upon and prospective genetical interventions in Litchi sinensis to eradicate the problem are outlined. Toxin-deficient lychee genotypes need to be developed by screening of germplasm accessions, and use of conventional and new site-directed mutagenesis technique of plant breeding. Lychee trees that produce super-toxin-rich (× 10 average toxin concentration) fruits are required to be identified and tagged to stop consumption of their fruits. New plantings must use toxin-deficient (low-toxin) lychee genotypes.