Torsional eye movements during psychophysical testing with rotating patterns.

Torsional eye movements were measured while subjects viewed a large, high contrast windmill pattern rotating at 53 degrees /s or a small (5 degrees diameter) dot pattern rotating at 115 degrees /s. Both stimuli generated rotational eye movements consisting of torsional optokinetic nystagmus (tOKN) superimposed on a slow torsional drift in the direction of pattern rotation. With the wide-field windmill stimulus, torsional drifts of up to 7 degrees over 20 s were found.

A platypus' eye view of the mammalian genome.

The genome of monotremes, like the animals themselves, is unique and strange. The importance of monotremes to genomics depends on their position as the earliest offshoot of the mammalian lineage. Although there has been controversy in the literature over the phylogenetic position of monotremes, this traditional interpretation is now confirmed by recent sequence comparisons.

The flightless I protein and the gelsolin family in nuclear hormone receptor-mediated signalling.

The Drosophila melanogaster flightless I protein and its homologues in higher eukaryotes (FliI) are conserved members of the gelsolin family of actin-binding proteins. Members of the gelsolin family generally contain three or six copies of a 125-amino-acid residue gelsolin-related repeating unit, and may contain additional domains including the C-terminal villin-related 'headpiece' or N-terminal extensions such as the leucine-rich repeat of the FliI protein. Numerous studies including work done with mouse knockouts for gelsolin, villin and CapG support a role for the family in cytoskeletal actin dynamics.

In the platypus a meiotic chain of ten sex chromosomes shares genes with the bird Z and mammal X chromosomes.

Two centuries after the duck-billed platypus was discovered, monotreme chromosome systems remain deeply puzzling. Karyotypes of males, or of both sexes, were claimed to contain several unpaired chromosomes (including the X chromosome) that form a multi-chromosomal chain at meiosis. Such meiotic chains exist in plants and insects but are rare in vertebrates.

Slowly reversible de-epoxidation of lutein-epoxide in deep shade leaves of a tropical tree legume may 'lock-in' lutein-based photoprotection during acclimation to strong light.

The kinetics of response to strong light have been examined in deeply shaded leaves of the tropical tree legume (Inga sp.) which have extraordinarily high levels of the alpha-xanthophyll lutein-epoxide that are co-located in pigment-protein complexes of the photosynthetic apparatus with the beta-xanthophyll violaxanthin. As in other species, rapidly reversible photoprotection (measured as non-photochemical chlorophyll fluorescence quenching) is initiated within the time frame of sun-flecks (minutes), before detectable conversion of violaxanthin to antheraxanthin or zeaxanthin.

Auxin transport inhibition precedes root nodule formation in white clover roots and is regulated by flavonoids and derivatives of chitin oligosaccharides.

The expression of the auxin responsive reporter construct, GH3:gusA, was examined in transgenic white clover plants to assess changes in the auxin balance during the earliest stages of root nodule formation. Reporter gene expression was monitored at marked locations after the application of bacteria or signal molecules using two precise inoculation techniques: spot-inoculation and a novel method for ballistic microtargeting. Changes in GH3:gusA expression were monitored after the inoculation of Rhizobium leguminosarum biovar trifolii, non-host rhizobia, lipo-chitin oligosaccharides (LCOs), chitin oligosaccharides, a synthetic auxin transport inhibitor (naphthylphthalamic acid; NPA), auxin, the ENOD40-1 peptide or different flavonoids.

Hearing: travelling wave or resonance?

A fresh look at classic work of Thomas Gold on how the inner ear processes sound

Gas chromatography-mass spectrometry analysis of indoleacetic acid and tryptophan following aqueous chloroformate derivatisation of Rhizobium exudates.

A new method for preparing alkyl esters of indole-3-acetic acid (IAA) in aqueous solution is adapted from the chloroformate method originally described by Husek for the analysis of amino acids. This method has the significant advantage of avoiding the generation and use of diazomethane, and is done in aqueous solution without the need to dry the sample with concomitant non-specific losses of IAA. The effectiveness of this method is demonstrated by its use in an isotope dilution gas chromatography-mass spectrometry (GC-MS) assay of IAA and L-tryptophan (Trp) in the culture supernatant of a series of Sinorhizobium meliloti and Rhizobium leguminosarum bv.

Theoretical considerations about carbon isotope distribution in glucose of C plants.

The origin of the non-statistical intramolecular distribution of C in glucose of C plants is examined, including the role of the aldolisation of triose phosphates as proposed by Gleixner and Schmidt (1997). A modelling approach is taken in order to investigate the relationships between the intramolecular distribution of C in hexoses and the reactions of primary carbon metabolism. The model takes into account C-C bond-breaking reactions of the Calvin cycle and leads to a mathematical expression for the isotope ratios in hexoses in the steady state.

Low temperature effects on grapevine photosynthesis: the role of inorganic phosphate.

The photosynthetic response of grapevine leaves (Vitis vinifera L. cv. Riesling) to low temperature was studied to determine the role of end-product limitation and orthophosphate (P) recycling to the chloroplast under these conditions.

Inhibitory modulation of photoreceptor melatonin synthesis via a nitric oxide-mediated mechanism.

Nitric oxide (NO) has been suggested to have many physiological functions in the vertebrate retina, including a role in light-adaptive processes. The aim of this study was to examine the influence of the NO-donor sodium nitroprusside (SNP) on the activity of arylalkylamine-N-acetyltransferase (AA-NAT; EC. 2.

Measurement and interpretation of the oxygen isotope composition of carbon dioxide respired by leaves in the dark.

We measured the oxygen isotope composition (delta(18)O) of CO(2) respired by Ricinus communis leaves in the dark. Experiments were conducted at low CO(2) partial pressure and at normal atmospheric CO(2) partial pressure. Across both experiments, the delta(18)O of dark-respired CO(2) (delta(R)) ranged from 44 per thousand to 324 per thousand (Vienna Standard Mean Ocean Water scale).

The cochlear amplifier as a standing wave: "squirting" waves between rows of outer hair cells?

This paper draws attention to symmetric Lloyd-Redwood (SLR) waves-known in ultrasonics as "squirting" waves-and points out that their distinctive properties make them well-suited for carrying positive feedback between rows of outer hair cells. This could result in standing-wave resonance-in essence a narrow-band cochlear amplifier. Based on known physical properties of the cochlea, such an amplifier can be readily tuned to match the full 10-octave range of human hearing.

The degenerate Y chromosome--can conversion save it?

The human Y chromosome is running out of time. In the last 300 million years, it has lost 1393 of its original 1438 genes, and at this rate it will lose the last 45 in a mere 10 million years. But there has been a proposal that perhaps rescue is at hand in the form of recently discovered gene conversion within palindromes.

Grouping of visual objects by honeybees.

Recent work has revealed that monkeys as well as pigeons are able to categorise complex visual objects. We show here that the ability to group similar, natural, visual images together extends to an invertebrate - the honeybee. Bees can be trained to distinguish between different types of naturally occurring scenes in a rather general way, and to group them into four distinct categories: landscapes, plant stems and two different kinds of flowers.

Brain-derived neurotrophic factor is expressed in a gradient in the superior colliculus during development of the retinocollicular projection.

Abstract Theoretical models of topographic map formation have postulated a gradient of attractant in addition to a gradient of repulsion in the target. In species where many axons grow past their correct positions initially, it has also been argued that a parallel gradient of attractant or branching signal is required to ensure collateral formation at the correct position (O'Leary et al., 1999).

11th International Congress on Molecular Plant-Microbe Interactions held at St. Petersburg--a report.

The report is a short summary of the most interesting presentations at the 11th International Congress on Molecular Plant-Microbe Interactions held during July 18-27, 2003 at St. Petersburg, Russia. The key elements from several sessions on the legume-Rhizobium interactions have been discussed.

Gene expression in germinated cysts of Phytophthora nicotianae.

SUMMARY The life cycle of Phytophthora species contains several distinct asexual developmental stages that are important for plant infection and disease development. These include vegetative growth of filamentous hyphae, production of multinucleate sporangia, motile, uninucleate zoospores and germinated cysts, the stage at which plant colonization is initiated. To understand mechanisms regulating molecular and cellular processes in germinated cysts, differential hybridization analysis of a cDNA library was used to identify genes up-regulated after cyst germination in P.

Proteome reference maps of Medicago truncatula embryogenic cell cultures generated from single protoplasts.

Using a combination of two-dimensional gel electrophoresis (2-DE) protein mapping and mass spectrometry (MS) analysis, we have established proteome reference maps of Medicago truncatula embryogenic tissue culture cells. The cultures were generated from single protoplasts, which provided a relatively homogeneous cell population. We used these to analyze protein expression at the globular stages of somatic embryogenesis, which is the earliest morphogenetic embryonic stage.

Effect of early cold stress on the maturation of rice anthers.

Male reproductive development in rice (Oryza sativa Linnaeus is very sensitive to various forms of environmental stresses including low temperature. Here, we present our findings on the proteomic analysis of the later developmental consequences of low temperature treatment on rice anthers. Anther proteins at the trinucleate stage, with or without cold treatment for four days at 12 degrees C at the young microspore stage, were extracted, separated by two-dimensional gel electrophoresis (2-DE) and compared.

Sinorhizobium meliloti metabolism in the root nodule: a proteomic perspective.

The proteome of the model symbiotic bacterium, Sinorhizobium meliloti was examined to determine the enzymatic reactions and cell processes that occur when S. meliloti occupies the root nodules of Medicago truncatula and Melilotus alba. The proteomes of the nodule bacteria were compared to that of S.

Production of monoclonal antibodies against peripheral-vesicle proteins in zoospores of Phytophthora nicotianae.

A coimmunisation protocol using microsomal fractions from Phytophthora nicotianae cells has enhanced the production of monoclonal antibodies directed towards proteins produced during asexual sporulation. Over 40% of the antibodies targeted three categories of zoospore peripheral vesicles. Five antibodies label the contents of dorsal vesicles, with three of these reacting with two P.