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Biomedical subjects

M Mohan

Publications and source records attributed to M Mohan.

At least 19 recordsLinked to original sources
PubMed2026

Ultrastructural Insights Into the Reproductive Anatomy and Eggs of Cotton Pink Bollworm, Pectinophora gossypiella Saunders (Lepidoptera: Gelechiidae).

The pink bollworm, Pectinophora gossypiella Saunders is a major pest of cotton, notorious for its high reproductive potential and rapid evolution of resistance to Bacillus thuringiensis (Bt) toxins. Despite its economic significance, detailed knowledge of its reproductive anatomy and egg ultrastructure has remained limited, constraining the development of advanced molecular control strategies such as CRISPR/Cas9-based genome editing. The present study provides the first comprehensive characterization of the reproductive system and egg surface morphology of P. gossypiella using stereomicroscopy and scanning electron microscopy (SEM) techniques. The male reproductive system consists of fused, bean-shaped testes, seminal vesicles, duplex and simplex ejaculatory ducts, and paired accessory glands. The female reproductive system comprises paired ovaries with four polytrophic ovarioles per ovary, lateral and common oviducts, accessory glands, corpus bursae, and spermathecal glands. Eggs are oval, dorsoventrally flattened, exhibit a reticulated chorion with distinct micropylar and aeropylar regions. SEM images revealed 6-9 rosette cells encircling a circular micropylar plate, 14-19 first order and 17-23 s order ribs, and 250-291 polygonal surface cells. The structural features of P. gossypiella eggs reveal key sites for sperm entry, aeropylar respiration, and candidate zones for microinjection in gene editing applications. These findings establish a morphological baseline critical for optimizing embryo manipulation and ribonucleoprotein (RNP) delivery in lepidopteran genome editing. This study represents a pioneering effort to integrate classical egg morphology with molecular entomology, thereby advancing precision genetic interventions aimed at resistance management and population suppression in P. gossypiella.

Animals↗
PubMed2006

Comparison of two hepatitis B vaccines (GeneVac-B and Engerix-B) in healthy infants in India.

Hepatitis B is a major problem in many parts of the world. The WHO has recommended the inclusion of hepatitis B vaccines in routine immunization schedules. We wanted to compare two recombinant hepatitis B vaccines in an infant population for immunogenicity and reactogenicity when given at 6, 10, and 14 weeks of age. One hundred seventy-three infants meeting eligibility criteria were given either GeneVac-B (Serum Institute of India Ltd.) or Engerix-B (GlaxoSmithKline Beecham) in a random fashion. Three 0.5-ml (10-mug) doses of the vaccines were given at 6, 10, and 14 weeks of age along with diphtheria-pertussis (whole cell)-tetanus (DTPw) vaccine. Blood samples were collected at baseline and 1 month after administration of the third dose of the vaccines to measure anti-HBs antibody levels. Seroconversion was defined as a titer of more than 1 x 10(-3) IU/ml, while seroprotection was defined as a titer of more than 10 x 10(-3) IU/ml. Of the GeneVac-B recipients, 98% seroconverted versus 99% of the Engerix-B group. The anti-HBs geometric mean titer was slightly greater for GeneVac-B (229 x 10(-3) IU/ml) than for Engerix-B (167 x 10(-3) IU/ml), but the difference was not significant. The seroprotection rates were similar for both vaccines (96% and 95%, respectively). The most common systemic reaction events were mild to moderate fever, excessive crying, local swelling, rash, and irritability, and the local reactions were redness, induration, and edema, which most probably were caused by the simultaneously administered DTPw vaccine. All events were transient and resolved without sequelae. Reactogenicity was similar for the two vaccines. The present study shows that GeneVac-B is as immunogenic and as well tolerated as Engerix-B when administered with DTPw vaccine at 6, 10, and 14 weeks of age.

Dose-Response Relationship, Immunologic↗
PubMed2006

Cloning and structural analysis of an Indian little millet (Panicum sumatrense) zein-like storage protein: implications for molecular assembly.

Zeins are prolamin storage proteins that accumulate in kernel endosperm of several cereals. For cloning of genes coding for zein-like proteins that accumulate in enhanced quantities in the filling stages of little millet (Panicum sumatrense Roth.) developing grains, RT-PCR was performed using specific primers. A 750-bp cDNA was directly sequenced and in silico analysis showed high identity degree to alpha-prolamins. This family is composed of zeins from Zea mays, coixins from Coix lachryma-jobi, and alpha-kafirins from Sorghum bicolor. The putative conserved domain of zein-like proteins was identified by primary structure comparisons. Furthermore, threading analyses indicated that the millet zein-like protein forms an anti-parallel alpha-helical hairpin with two opposite surfaces: one hydrophobic and the other hydrophilic that probably could be involved in protein storage assembly. Knowledge about zein-like alpha-prolamins in little millet will lead to cloning and transfer of this gene to other major food crops, such as cereals and legumes, with inferior nutritional quality for monogastric animals.

Amino Acid Sequence↗
PubMed2005

Screening and purification of a novel trypsin inhibitor from Prosopis juliflora seeds with activity toward pest digestive enzymes.

Several pests are capable of decreasing crop production causing severe economical and social losses. Aiming to find novel molecules that could impede the digestion process of different pests, a screening of alpha-amylase and trypsin-like proteinase inhibitors was carried out in Prosopis juliflora, showing the presence of both in dry seeds. Furthermore, a novel trypsin inhibitor, with molecular mass of 13,292 Da, was purified showing remarkable in vitro activity against T. castaneum and C. maculatus.

Chromatography, Affinity↗
PubMed2005

Adhesive small bowel obstruction (ASBO) in children--role of conservative management.

Adhesive small bowel obstruction (ASBO) is an annoying postoperative complication. Though the diagnosis can be made easily, the role of conservative management in children is controversial. Hence a study was conducted to determine the role of conservative management, and to identify the factors that can predict / influence the outcome of conservative treatment in children with ASBO. Children admitted with ASBO from 1980 to 2002 (22 year period) formed the material for this study. The data was analyzed with respect to the influence of age at the time of presentation, primary disease for which original laparotomy was done, time interval between the primary surgery and the development of ASBO and the number of laparotomies prior to the development of ASBO on the outcome of conservative management. There were 74 episodes of ASBO in 69 children (Five children had two episodes). Out of 74 episodes, 5 episodes (6.75%) needed immediate laparotomy for suspected gangrene. All others were managed conservatively. Of the 69 episodes managed conservatively, 36 responded to conservative treatment (2-5 days) while 33 required subsequent surgical intervention, with 11 of them requiring bowel resection (two for gangrene and 9 for bowel damage during adhesiolysis) and in the rest 22 cases adhesiolysis. A substantial number of children with ASBO respond well to conservative treatment. Majority of the children developed ASBO within three months after the primary laparotomy. Children below the age of one year (at the time of presentation with ASBO) responded poorly to the conservative management. Children who had primary surgery for Hirschsprung's disease and intussusception also appeared to have responded poorly to conservative management, but statistically not significant. Time interval between the primary surgery and the number of laparotomies before the child developed ASBO did not influence the outcome of conservative management.

Adolescent↗
PubMed2004

Tagging and mapping of a rice gall midge resistance gene, Gm8, and development of SCARs for use in marker-aided selection and gene pyramiding.

Using amplified fragment length polymorphisms (AFLPs) and random amplified polymorphic DNAs (RAPDs), we have tagged and mapped Gm8, a gene conferring resistance to the rice gall midge (Orseolia oryzae), a major insect pest of rice, onto rice chromosome 8. Using AFLPs, two fragments, AR257 and AS168, were identified that were linked to the resistant and susceptible phenotypes, respectively. Another resistant phenotype-specific marker, AP19(587), was also identified using RAPDs. SCAR primers based on the sequence of the fragments AR257 and AS168 failed to reveal polymorphism between the resistant and the susceptible parents. However, PCR using primers based on the regions flanking AR257 revealed polymorphism that was phenotype-specific. In contrast, PCR carried out using primers flanking the susceptible phenotype-associated fragment AS168 produced a monomorphic fragment. Restriction digestion of these monomorphic fragments revealed polymorphism between the susceptible and resistant parents. Nucleotide BLAST searches revealed that the three fragments show strong homology to rice PAC and BAC clones that formed a contig representing the short arm of chromosome 8. PCR amplification using the above-mentioned primers on a larger population, derived from a cross between two indica rice varieties, Jhitpiti (resistant parent) and TN1 (susceptible parent), showed that there is a tight linkage between the markers and the Gm8 locus. These markers, therefore, have potential for use in marker-aided selection and pyramiding of Gm8 along with other previously tagged gall midge resistance genes [ Gm2, Gm4(t), and Gm7].

Animals↗
PubMed2004

Independent downstream gene expression profiles in the presence of estrogen receptor alpha or beta.

The two known forms of estrogen receptor (ER), alpha and beta, exhibit differences in structure, affinity for certain ligands, and tissue distribution, suggesting differential roles. It is of interest from several perspectives to determine whether the two receptors elicit similar or differing responses within the same cell type in the presence of the same ligand. To evaluate roles of ER, we have examined responses to estrogen in a rat embryonic fibroblast cell line model, normally naive to ER, engineered to stably express ERalpha or ERbeta. Rat1+ERalpha, Rat1+ERbeta, and precursor Rat1 cell lines were treated with estradiol-17beta (E(2); 1 nM) or an ethanol vehicle for 24 h. Total RNA was extracted, and cDNA generated and subjected to suppression subtractive hybridization (SSH), followed by differential screening using dot blot hybridization. In the presence of ERalpha, products were identified that represent classic responses to E(2), including markers for cell proliferation. In the presence of ERbeta, an alternate transcription profile was observed, including upregulation of pro-alpha-2(I) collagen. These data support a model in which ERalpha and ERbeta regulate unique subsets of downstream genes within a given cell type.

Animals↗
PubMed2004

Global gene expression analysis comparing bovine blastocysts flushed on day 7 or produced in vitro.

In vitro produced (IVP) bovine embryos have darker cytoplasm, reduced buoyant density, fragile zonae pellucidae, chromosomal abnormalities, higher pregnancy failure rates, and altered gene expression compared to embryos produced in vivo. Characterization of early deviations in gene expression would enable us to better understand the biology of early embryo development and improve in vitro culture systems. Here we compared gene expression between Day 7 blastocysts generated in TCM199 with 5% FBS and Day 7 in vivo derived blastocysts and using suppression-subtractive hybridization (SSH). Pools of 25 embryos for both driver and tester were used in the RNA extraction process. The subtracted products were cloned and subjected to differential hybridization screening analysis. cDNAs were isolated, single-pass sequenced, and subjected to BLAST search. Of 32 in vivo ESTs (expressed sequence tags) that provided sequence information, 30 matched homologous sequences in GenBank. Of 32 in vitro ESTs, 22 provided specific matches while the remaining ten represented novel transcripts. Two in vivo ESTs, galectin-1 and fibronectin, and one in vitro EST, filamin A, were further characterized using real-time quantitative PCR. To further examine the reproducibility of the SSH data, three different pools of embryos with each pool containing ten embryos produced from each of the following production systems, namely, in vivo, IVP in TCM199 with 5% FBS and CR1aa with 5% FBS were used for real-time reverse transcription-polymerase chain reaction (RT-PCR) confirmation studies. Significant increases in the expression level of galectin-1 and fibronectin were observed in the in vivo derived blastocysts compared to blastocysts produced in TCM199 with 5% FBS and CR1aa cultures. No significant difference in filamin A expression was found between blastocysts produced in vivo and those derived from either of the in vitro production systems. We conclude that these techniques are useful to characterize the transcriptome of the early preattachment embryo and observed deviations in mRNA expression may partially explain the differences in quality between in vivo and IVP embryos.

Animals↗
PubMed2004

Antimutagenicity of herbal detoxification formula Smoke Shield against environmental mutagens.

Smoke Shield is a formulation designed to reduce smoke related mutagenicity and toxicity in the population. Smoke Shield contains a dual extract of turmeric (Curcuma longa) obtained by supercritical CO2 gas extraction and post-supercritical hydroethanolic extraction together with extracts of green tea and other spices, whose presence synergistically increases the activity of turmeric. In the present study we have shown its antimutagenic activity to various environmental mutagens in vitro and in vivo. Smoke Shield was found to produce significant inhibition of mutagenicity to Salmonella typhimurium induced by sodium azide and 4-nitro-0-phenylenediamine (NPD) at a concentration of 2 mg/plate while inhibition to N-methyl-N-nitro N'nitrosoguanidine was less significant. Inhibition was also found to depend upon the strain which was used. Smoke Shield was found to be more effective against mutagens needing metabolic activation such as 2-Acetamidofluorene (2-AAF) and benzo[a]pyrene. Smoke Shield was also found to significantly inhibit the mutagenicity induced by tobacco extract to Salmonella typhimurium TA102. Smoke Shield was also found to inhibit the urinary mutagenicity of rats treated with the benzo[a]pyrene and tobacco extract. Moreover, Smoke Shield administration was found to inhibit the urinary mutagenicity in smokers. These results indicate that Smoke Shield could inhibit mutagenic response in vitro and in vivo produced by several kinds of mutagens present in our atmosphere.

Animals↗
PubMed2003

Characterization and comparison of midgut proteases of Bacillus thuringiensis susceptible and resistant diamondback moth (Plutellidae: Lepidoptera).

The midgut proteases of the Bacillus thuringiensis resistant and susceptible populations of the diamondback moth, Plutella xylostella L. were characterized by using protease specific substrates and inhibitors. The midgut contained trypsin-like proteases of molecular weights of 97, 32, 29.5, 27.5, and 25 kDa. Of these five proteases, 29.5 kDa trypsin-like protease was the most predominant in activation of protoxins of Cry1Aa and Cry1Ab. The activation of Cry1Ab protoxin by midgut protease was fast (T(1/2) of 23-24 min) even at a protoxin:protease ratio of 250:1. The protoxin activation appeared to be multi-step process, and at least seven intermediates were observed before formation of a stable toxin of about 57.4 kDa from protoxin of about 133 kDa. Activation of Cry1Aa was faster than that of Cry1Ab on incubation of protoxins with midgut proteases and bovine trypsin. The protoxin and toxin forms of Cry proteins did not differ in toxicity towards larvae of P. xylostella. The differences in susceptibility of two populations to B. thuringiensis Cry1Ab were not due to midgut proteolytic activity. Further, the proteolytic patterns of Cry1A protoxins were similar in the resistant as well as susceptible populations of P. xylostella.

Animals↗
PubMed2002

Grasses and gall midges: plant defense and insect adaptation.

The interactions of two economically important gall midge species, the rice gall midge and the Hessian fly, with their host plants, rice and wheat, respectively, are characterized by plant defense via R genes and insect adaptation via avr genes. The interaction of a third gall midge species, the orange wheat blossom midge, with wheat defense R genes has not yet exhibited insect adaptation. Because of the simple genetics underlying important aspects of these gall midge-grass interactions, a unique opportunity exists for integrating plant and insect molecular genetics with coevolutionary ecology. We present an overview of some genetic, physiological, behavioral, and ecological studies that will contribute to this integration and point to areas in need of study.

Adaptation, Physiological↗
PubMed2002

Expression patterns of retinoid X receptors, retinaldehyde dehydrogenase, and peroxisome proliferator activated receptor gamma in bovine preattachment embryos.

In cattle, administration of retinol at the time of superovulation has been indirectly associated with enhanced developmental potential of the embryo. Vitamin A and its metabolites influence several developmental processes by interacting with 2 different types of nuclear receptors, retinoic acid receptors and retinoid X receptors (RXRs). Given the limited information available concerning the RXR-mediated retinoid signaling system, particularly in species other than rodents, this study was performed to gain insight into the potential role of retinoid signaling during preattachment embryo development in the cow. Bovine embryos were produced in vitro from oocytes harvested from abattoir ovaries and frozen in liquid nitrogen at the oocyte, 2-, 4-, 8-, and 16- to 20-cell, morula, blastocyst, and hatched blastocyst stages. Reverse transcription polymerase chain reaction (PCR) and whole mount in situ hybridization were utilized to investigate mRNA expression for RXR alpha, RXR beta, RXR gamma, alcohol dehydrogenase I (ADH-I), retinaldehyde dehydrogenase 2 (RALDH2), peroxisome proliferator activated receptor gamma (PPAR gamma), and glyceraldehyde-3-phosphate dehydrogenase. Transcripts for RXR alpha, RXR beta, RALDH2, and PPAR gamma were detected in all stages beginning from the oocyte through to the hatched blastocyst. Whole mount in situ hybridization performed using digoxigenin-labeled antisense probes detected all 4 transcripts in both the inner cell mass and the trophectoderm of hatched blastocysts. PCR products obtained for ADH-I exhibited very low homology to known human and mouse sequences. Immunohistochemistry was performed using polyclonal anti-rabbit antibodies against RXR beta and PPAR gamma to investigate whether these embryonic mRNAs were translated to the mature protein. Strong immunostaining was observed for both RXR beta and PPAR gamma in the trophectoderm and inner cell mass cells of intact and hatched blastocysts. Messenger RNA was not detected at any stage for RXR gamma. Expression of mRNA for RXR alpha, RXR beta, RALDH2, and PPAR gamma suggests that the early embryo may be competent to synthesize retinoic acid and regulate gene expression during preattachment development in vitro.

Alcohol Dehydrogenase↗
PubMed2002

Analysis of gene expression in the bovine blastocyst produced in vitro using suppression-subtractive hybridization.

Successful embryonic development is dependent on time and location-specific expression of appropriate genes. Unfortunately, information on stage-specific gene expression during early embryonic development in the bovine is lacking. In the present study, we compared gene expression between in vitro-produced Day 7-8 intact blastocysts (driver) and Day 9-10 hatched blastocysts (tester) using suppression-subtractive hybridization. Pools of 30 embryos for both driver and tester were used in the RNA extraction process. From limited amounts of starting material ( approximately 400 ng of total RNA), a reverse transcription-polymerase chain reaction (PCR) procedure was used to amplify the mRNA and generate sufficient cDNA to conduct suppression-subtractive hybridization. The subtracted cDNA products were cloned, and 126 cDNAs representing expressed mRNAs were isolated, sized, single-pass sequenced, and compared to known sequences in GenBank. Ninety-two clones provided sequence information for further analysis. Among these, 31 exhibited high homology to known genes. Three, 26S proteasomal ATPase (PSMC3), casein kinase 2 alpha subunit (CK2), and phosphoglycerate kinase (PGK) were selected and further characterized using real-time quantitative PCR to assess their differential expression in hatched blastocysts. Overall, a 1.3-, 1.6-, and 1.5-fold increase in expression level was observed in hatched blastocysts compared with intact blastocyst for PSMC3, CK2, and PGK, respectively. These results show that construction of subtracted cDNA libraries from small numbers of embryos is feasible and can provide information on gene expression patterns during preattachment embryogenesis.

Adenosine Triphosphatases↗
PubMed2001

Expression of retinol-binding protein messenger RNA and retinoic acid receptors in preattachment bovine embryos.

In cattle, retinoic acid (RA) has been indirectly associated with developmental potential of the embryo. RA is transported by retinol-binding protein (RBP) and actions of RA are mediated by several subtypes of nuclear retinoic acid receptors (RAR). Bovine embryos, produced in vitro from oocytes harvested from ovaries collected at a local abattoir, were frozen in liquid nitrogen at the oocyte, 2-, 4-, 8-, 16 to 20-cell, morula, blastocyst, and hatched blastocyst stages. Employing reverse transcription polymerase chain reaction (RT-PCR) we investigated mRNA expression for RBP, RARalpha, RARbeta, RARgamma, and glyceraldehyde-3-phosphate dehydrogenase (GAPDH). Total RNA was extracted from 25 pooled embryos at each stage and RT-PCR analysis was repeated thrice. GAPDH transcript was detected in all stages. Transcripts for RBP, RARalpha, and RARgamma were also detected in all stages from the oocyte through to the hatched blastocyst. Expression of RARbeta was not detected at any stage. Whole-mount immunohistochemistry was performed with intact and hatched blastocysts using polyclonal antibodies against RARalpha and RARgamma2 to investigate if these embryonic mRNAs were translated to the mature protein. Strong immunostaining was observed for both RARalpha and RARgamma2 in the inner cell mass and trophectoderm of intact and hatched blastocysts. Expression of mRNA for RBP, RARalpha, RARgamma, and of the RARalpha and RARgamma2 receptor proteins in the bovine embryo suggests that RA is likely to directly regulate gene expression during preimplantation development in that species.

Animals↗
PubMed2001

Wolbachia in the Asian rice gall midge, Orseolia oryzae (Wood-Mason): correlation between host mitotypes and infection status.

Using a PCR-based method, we detected Wolbachia in the Asian rice gall midge. Furthermore, results showed that all females across all biotypes are infected with Wolbachia. However, all male flies are not infected and show different infection frequency in different biotypes. We have also identified three mitotypes, in the rice gall midge, based on DraI restriction pattern of a portion of the 12S rRNA gene that was PCR amplified using primers specific to this gene. All the females and infected male flies had type 1 mtDNA while uninfected males showed only type 2 or 3 mtDNA. Inheritance patterns of mtDNA revealed the existence of a correlation between mtDNA type and Wolbachia infection in the Asian rice gall midge. Evidence for paternal inheritance of mtDNA in Wolbachia-free gall midge is also presented.

Animals↗
PubMed2001

Polymorphisms flanking the mariner integration sites in the rice gall midge (Orseolia oryzae Wood-Mason) genome are biotype-specific.

In an effort to study genome diversity within and between the Indian biotypes of the Asian rice gall midge, Orseolia oryzae, a major insect pest of rice, we made use of mariner transposable element integration site polymorphisms. Using degenerate primers, the design of which is based on mariner sequences, we amplified a ca. 450 bp mariner sequence from the rice gall midge. The mariner sequence showed homology with that of a mariner element isolated from the Hessian fly, Mayetiola destructor, a major dipteran pest of wheat. Southern hybridization, using this mariner fragment as a probe, revealed that the mariner elements are moderately to highly repetitive in the rice gall midge genome. Based on the sequence information of this 450-bp PCR-amplified fragment, outward-directed primers were designed and used in an inverse PCR (iPCR) to amplify the DNA flanking the conserved regions. To study the regions flanking the mariner integration sites, we employed a novel PCR-based approach: a combination of sequence specific amplification polymorphism (SSAP) and amplified fragment length polymorphism (AFLP). The outward-directed mariner-specific primer was used in combination with adapter-specific primers with 1-3 selective nucleotides at their 3' ends. The amplification products were resolved on an agarose gel, Southern-transferred onto nylon membranes, and probed with the iPCR fragment. Results revealed biotype-specific polymorphisms in the regions flanking the mariner integration sites, suggesting that mariner elements in the rice gall midge may be fixed in a biotype-specific manner. The implications of these results are discussed in the context of biotype differentiation.

Amino Acid Sequence↗
PubMed2001

Modulation of feeding and drinking behaviour by catecholamines injected into nucleus caudatus in rats.

Lesions of nucleus caudatus have been documented to produce adipsia and aphasia in rats. Injection of dopamine into this nucleus has been shown to facilitate water intake in rats. But, reports are not available on the effects of intracerebral injection of epinephrine and norepinephrine on feeding and drinking behaviour in animal models. Therefore, in the present study the effect of adrenaline and noradrenaline injected into nucleus caudatus on food and water intake in rats was assessed. 24 h basal food and water intakes were recorded in Wistar rats and were found to be 12.37 +/- 0.20 g and 22.04 +/- 0.27 ml respectively. Stainless steel cannulae were implanted stereotaxically into the nucleus caudatus. Four different doses (0.1 microgram, 0.5 microgram, 1 microgram, and 2 micrograms) of adrenaline and noradrenaline were injected into the nucleus caudatus through the implanted cannulae in separate groups of animals and their 24 h food and water intakes were recorded following these injections. No change in food and water intake was observed following the administration of different doses of adrenaline. A significant increase in 24 h food intake reaching a maximum of 16.03 +/- 0.15 g at 2 micrograms dose, without change in water intake was observed following administration of different doses of noradrenaline. The noradrenaline-facilitated food intake was blocked when noradrenaline was injected following injection of phentolamine, an alpha-receptor blocker. The bilateral lesions of nucleus caudatus resulted in a significant and sustained inhibition of food (8.98 +/- 0.17 g) and water intake (19.12 +/- 0.16 ml). These observations suggest that nucleus caudatus is involved in regulation of food and water intakes in rats. Noradrenaline-facilitated food intake is mediated by alpha-receptors. Adrenaline does not affect these ingestive behaviours when injected into the nucleus caudatus in rats.

Animals↗