Inbreeding effects on competition inTribolium

When replicate cultures ofT. confusum andT. castaneum are husbanded together under identical treatment conditions, sometimesT. confusum eliminatesT. castaneum, and other times,T. castaneum wins (i.e., competitive indeterminacy occurs). While several plausible explanations were advanced, the results of Mertz et al. (1976) implicated demographic stochasticity and not classical genetic founder effect as the predominant factor influencing the identity of the winning species. They also observed, however, that the size of the founding population had an influence on the competitive strength ofT. castaneum. The present study shows that the decline in competitive strength that accompanied decreasing founder size inT. castaneum can be amply explained by simple inbreeding depression. The eggs of inbred adults showed an approximate 15% reduction in hatchability when compared to outbred adults. No evidence was found that the decrease in competitive strength was due either to prior history differences or reduced genetic heterogeneity of the founding adults.     

<Emphasis Type="Italic">OsMADS22</Emphasis>, an <Emphasis Type="Italic">STMADS11</Emphasis>-like MADS-box gene of rice,is expressed in non-vegetative tissues and its ectopic expression induces spikelet meristem indeterminacy

We report the cDNA sequence and gene expression patterns of OsMADS22, a novel member of the STMADS11-like family of MADS-box genes, from rice. In contrast to previously reported STMADS11-like genes, whose expression is detected in vegetative tissues, OsMADS22 is mainly expressed during embryogenesis and flower development. In situ hybridization analysis revealed that OsMADS22 expression is localized in the L1 layer of embryos and in developing stamen primordia. Ectopic expression of OsMADS22 in transgenic rice plants resulted in aberrant floral morphogenesis, characterized by a disorganized palea, an elongated glume, and a two-floret spikelet. The results are discussed in terms of rice spikelet development and a novel non-vegetative role for a STMADS11-like gene.     

Fundamental issues, recent advances, and future directions in myodynamics

A state-of-the-art report is presented on recent progress in selected areas of myodynamics, but also on problems that severely hamper the further development of the discipline. Significant advances have been made in elucidating the force-producing interaction between actin and the myosin-S1-subunit, including the localization of the most probable molecular site of power stroke initiation. Concerning the architecture of the myostructures, strong experimental evidence has accumulated for numerous intra-, inter-, and extramuscular pathways for lateral force transmission in addition to the serial sarcomere-to-sarcomere myotendinous path.

It is shown that contemporary muscle models are inadequate in most respects and lag far behind the requirements an appropriate myodynamic model should fulfil. A similar comment applies to the current approaches designed to solve the myoskeletal indeterminacy problem. These formulations neglect myodynamic properties and do not allow for the implementation of biologically realistic objective functions. The solutions currently obtained are highly unsatisfactory. New research directions to rectify these situations are suggested, also with regard to the identification of subject-specific myodynamic parameters.     

A KNOX-Cytokinin Regulatory Module Predates the Origin of Indeterminate Vascular Plants

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