Hybridization of Gossypium species through in ovulo embryo culture

An interspecific hybrid of the sexually incompatible species G. hirsutum cv. Laxmi and G. arboreum cv. Jyoti was obtained through in ovulo embryo culture. Eightto twelve-day-old ovules were excised and cultured on Beasley and Ting's medium supplemented with Indol-3 acetic acid (5×10^-6 to 7×10^-6 M), Kinetin (5×10^-6 to 5×10^-8 M), Gibberellic acid (5×10^-7 to 5×10^-9M), Ammonium chloride (5 to 15mM) and Casein hydrolysate (50 to 200mg/l) added individually and in various combinations along with sucrose. No single medium was adequate to ensure complete development of the fertilized ovules to plantlets, thus necessitating a sequential five step transfer to different media. Cytological studies confirmed the hybrid nature of the plants.Abbreviation IAA Indol-3 acetic acid - Kn Kinetin - GA₃ Gibberellic acid - CH Casein hydrolysate - NAA -Naphthalene-acetic acid - BT Beasley and Ting's basal medium - MS Murashige and Skoog's basal medium - W White's basal medium NCL Communication number 3823.     

Anther culture in Helianthus annuus L., influence of genotype and culture conditions on embryo induction and plant regeneration

Summary Production of microspore-derived embryos from cultured anthers is now a well established technique for the isolation of homozygous lines in many crop plants. We describe here a culture method for embryo induction and plant regeneration from anthers of four sunflower genotypes. For preliminary experiments, anthers of uninucleate microspores were cultured on four types of basal media viz., Murashige and Skoog's MS, Gamborg's B5, Nitsch and Nitsch, and White's W, supplemented with 1.0 mg/l 2,4 dichlorophenoxy acetic acid and 0.5 mg/l 6-benzylaminopurine and 40 g/l sucrose. MS basal medium, being more responsive for embryo induction, was used for further experimentation. To optimise the culture requirement MS basal medium was supplemented with 0.2–2.0 mg/l 2,4 dichlorophenoxy acetic acid and 0.5 and 1.0 mg/l 6-benzylaminopurine. The effect of cold pretreatment, hormone regime and sucrose concentration were tested for embryogenic efficiency. Genotype had a significant effect on the capacity of embryo induction. Addition of silver nitrate (2.5 mg/l), an ethylene inhibitor, stimulated embryo germination. Plantlets were obtained (10–15%) from embryos of only one genotype.Abbreviations 2,4-D 2,4 dichlorophenoxy acetic acid - NAA -naphthalene acetic acid - IAA indole-3-aceticacid - BAP 6-benzylaminopurine - KN Kinetin - ABA abscisic acid - GA₃ gibberellic acid     

Complete genomic characterization of a pathogenic A.II strain of Francisella tularensis subspecies tularensis

Francisella tularensis is the causative agent of tularemia, which is a highly lethal disease from nature and potentially from a biological weapon. This species contains four recognized subspecies including the North American endemic F. tularensis subsp. tularensis (type A), whose genetic diversity is correlated with its geographic distribution including a major population subdivision referred to as A.I and A.II. The biological significance of the A.I - A.II genetic differentiation is unknown, though there are suggestive ecological and epidemiological correlations. In order to understand the differentiation at the genomic level, we have determined the complete sequence of an A.II strain (WY96-3418) and compared it to the genome of Schu S4 from the A.I population. We find that this A.II genome is 1,898,476 bp in size with 1,820 genes, 1,303 of which code for proteins. While extensive genomic variation exists between "WY96" and Schu S4, there is only one whole gene difference. This one gene difference is a hypothetical protein of unknown function. In contrast, there are numerous SNPs (3,367), small indels (1,015), IS element differences (7) and large chromosomal rearrangements (31), including both inversions and translocations. The rearrangement borders are frequently associated with IS elements, which would facilitate intragenomic recombination events. The pathogenicity island duplicated regions (DR1 and DR2) are essentially identical in WY96 but vary relative to Schu S4 at 60 nucleotide positions. Other potential virulence-associated genes (231) varied at 559 nucleotide positions, including 357 non-synonymous changes. Molecular clock estimates for the divergence time between A.I and A.II genomes for different chromosomal regions ranged from 866 to 2131 years before present. This paper is the first complete genomic characterization of a member of the A.II clade of Francisella tularensis subsp. tularensis.     

Micropropagation of licorice (Glycyrrhiza glabra L.) through shoot tip and nodal cultures

Summary Apical and axillary buds ofGlycyrrhiza glabra commonly known as licorice, a plant of repute in the Indian system of medicine, were used for induction of adventitious shoots. For induction of multiple shoots, Murashige and Skoog’s (MS) medium with N⁶-benzyladenine (BA, 0.88–8.87 μM) was used. Reduction in major salts of MS medium enhanced the multiplication ratio up to 1∶10. Plants transferred to the greenhouse showed 90% survival. The present work describes a stepwise protocol for production ofGlycyrrhiza glabra plants on simple minimal media, where very high multiplication rates with healthy root systems were obtained. Roots being the organ of commercial importance, the protocol has tremendous potential.     

PathSys: integrating molecular interaction graphs for systems biology

Background  

The goal of information integration in systems biology is to combine information from a number of databases and data sets, which are obtained from both high and low throughput experiments, under one data management scheme such that the cumulative information provides greater biological insight than is possible with individual information sources considered separately.     

Outcome of challenge with Coxsackievirus B4 in young mice after maternal infection with the same virus during gestation

Enteroviral infections go usually unnoticed, even during pregnancy, yet some case histories and mouse experiments indicate that these viruses may be transmitted vertically. More frequently, however, transmission occurs by (fecal) contamination during and shortly after birth. The aim of this study was to investigate the effect of maternal infection in mice (1) on gravidity outcome and (2) on subsequent challenge of the offspring with the same virus. CD1 outbred female mice were infected by the oral route with coxsackievirus B4 strain E2 or mock-infected at days 4, 10, or 17 of gestation. Weight and signs of sickness were noted daily. Pups were infected at day 25 after birth (4 days postweaning). Organs (brain, pancreas, and heart) were analyzed for viral RNA and histopathology. We observed that maternal infection at day 4 or day 17 of gestation had little effect on pregnancy outcome, whereas infection at day 10 affected dams and/or offspring. Infection of pups resulted in severe inflammation of the pancreas, but only when dams were previously infected, especially at day 17. The blood glucose levels were elevated. Because no trace of infection was found at the time of challenge, a role for immunopathology is suggested.     

Influence of medium composition on callus induction and camptothecin(s) accumulation in Nothapodytes foetida

Camptothecin(s) production was examined in callus cultures derived from cotyledons of Nothapodytes foetida (Weigh) Sleumer. The calluses were grown on various combinations of Murashige and Skoog's basal media supplemented with auxins 2,4-dichlorophenoxyacetic acid (2,4-D), 2,4,5-trichlorophenoxyacetic acid (2,4,5-T), a-napthalene acetic acid (NAA) and indole-3-acetic acid (IAA) with 6-benzyl aminopurine (BA)/kinetin in different concentrations. The presence of camptothecin (CPT) and 9-methoxycamptothecin (9-OMeCPT) were analyzed by HPLC in relation to the media composition. Hyper production of CPT(1.306% on dry wt. basis) was observed with a combination of 2,4-D with BA and 2,4,5-T and NAA in 1-month-old callus.     

Synthesis and bioactivity of a side chain bridged paclitaxel: A test of the T-Taxol conformation

A knowledge of the bioactive tubulin-binding conformation of paclitaxel (Taxol^?) is crucial to a full understanding of the bioactivity of this important anticancer drug, and potentially also to the design of simplified analogs. The bioactive conformation has been shown to be best approximated by the T-Taxol conformation. As a further test of this conclusion, the paclitaxel analog 4 was designed as a compound which has all the chemical functionality necessary for activity, but which cannot adopt the T-Taxol conformation. The synthesis and bioassay of 4 confirmed its lack of activity, and thus provided further support for the T-Taxol conformation as the bioactive tubulin-binding conformation.