Biomedical subjects

Sukumar Chakraborty

Publications and source records attributed to Sukumar Chakraborty.

3 recordsLinked to original sources

PubMed2007

Passage through alternative hosts changes the fitness of Fusarium graminearum and Fusarium pseudograminearum.

Species of the necrotrophic fungal pathogen Fusarium that cause head blight and crown rot of cereals including wheat also infect a number of alternative host plants. This raises the prospect of more damaging pathogen strains originating and persisting as highly successful saprophytes on hosts other than wheat. The immediate impact on pathogenic (aggressiveness) and saprophytic (growth rate and fecundity) behaviour of six isolates with low, moderate or high initial aggressiveness was examined in two species of Fusarium after their passage through 10 alternative plant hosts. One passage through alternative hosts significantly reduced the pathogenic fitness of most isolates, but this change was not associated with a concomitant change in their overall saprophytic behaviour. The overall weak association between aggressiveness, fecundity and growth rate both before and after passage through the alternative hosts indicate that pathogenic and saprophytic fitness traits may be independently controlled in both Fusarium species. Thus, there was no trade-off between pathogenic and saprophytic fitness in these necrotrophic plant pathogens.

Edible Grain↗

PubMed2006

Multilocus sequence analysis of Fusarium pseudograminearum reveals a single phylogenetic species.

Fusarium pseudograminearum causes crown rot of wheat in Australia and most other wheat growing regions, but its evolutionary history is largely unknown. We demonstrate for the first time that F. pseudograminearum is a single phylogenetic species without consistent lineage development across genes. Isolates of F. pseudograminearum, F. graminearum sensu lato, and F. cerealis, were collected from four countries and four single copy, nuclear genes were partially sequenced, aligned with previously published sequences of these and related species, and analysed by maximum parsimony and Bayesian inference. Evolutionary divergence varied between genes, with high phylogenetic incongruence occurring between the gene genealogies. The absence of geographic differentiation between isolates indicates that the introduction of new fungal strains to a region has the potential to introduce new pathogenic and toxigenic genes into the native population through sexual recombination.

Base Sequence↗

PubMed2002

A neuro-fuzzy framework for inferencing.

Earlier we proposed a connectionist implementation of compositional rule of inference (COI) for rules with antecedents having a single clause. We first review this net, then generalize it so that it can deal with rules with antecedent having multiple clauses. We call it COIN, the compositional rule of inferencing network. Given a relational representation of a set of rules, the proposed architecture can realize the COI. The outcome of COI depends on the choice of both the implication function and the inferencing scheme. The problem of choosing an appropriate implication function is avoided through neural learning. COIN can automatically find a 'good' relation to represent a set of fuzzy rules. We model the connection weights so as to ensure learned weights lie in [0,1]. We demonstrate through extensive numerical examples that the proposed neural realization can find a much better representation of the rules than that by usual implication and hence results in much better conclusions than the usual COI.

Fuzzy Logic↗