The fusicoccin-stimulated phosphorylation of a 33 KDa polypeptide in cells of Acer pseudoplatanus as influenced by extracellular and intracellular pH

Abstract In a previous study, it was shown that the fungal toxin fusicoccin (FC) is able to stimulate the in vivo phosphorylation of a 33 KDalton polypeptide (33 KP) independently of protein synthesis. Here we show that the stimulation by FC of both proton efflux and 33 KP phosphorylation are strongly enhanced when the external medium contains K⁺ or Na⁺, suggesting that the two phenomena are related. The stimulatory effect of FC is higher in unbuffered than in buffered media; moreover, in the absence of FC, 33 KP is more phosphorylated at an acidic than at a basic pH of the medium, suggesting that the effect of FC may depend, to a certain extent, on the acidification of the free space caused by FC-promoted proton efflux. Treatments reported to alter the intracellular pH influence 33 KP phosphorylation even more strongly than the external pH does. The acidifying agents isobutyric acid and trimethylacetic acid decrease 33 KP phosphorylation, while the alkalinizing agents, ammonia and procaine, increase it. FC partially counteracts the inhibition by the weak acids, whereas the stimulatory effect of FC is not additive with that of the weak bases. The results indicate that 33 KP phosphorylation senses both the external and internal pH. The stimulatory effect of cytoplasm-alkalinizing treatments, which mimics that of FC, agrees with the reported capacity of FC to cause cytoplasmic alkalinization, following activation of the plasmalemma proton pump.     

IMPORTANCE OF REFERENCE STANDARDS IN TRAINING PANELISTS

When training a sensory evaluation panel, reference standards play an important role in developing appropriate terminology, establishing intensity ranges and showing the action of an ingredient. In addition, use of reference standards reduces the amount of training time while providing documentation for terminology. Product characteristics can be demonstrated through reference standards for application in plant quality assurance programs as well as for project planning in new product development, product maintenance (i.e., shelf-life), product improvement and cost reduction programs.     

Distinction between Two Types of Beta-Thalassaemia by Inducibility of the Cell-free Synthesis of Beta-Chains by Nonthalassaemic Soluble Fraction

β-THALASSAEMIA is a hereditary anaemia in which the β-chains of haemoglobin, though structurally normal, are synthesized abnormally slowly. The β-thalassaemia of the Ferrara region of Italy is distinguished in the homozygote by β-chain synthesis which is not merely reduced but completely absent. It has recently been reported that, in a cell-free system, ribosomes from such subjects do not make β-chains in the presence of their own supernatant but do when nonthalassaemic supernatant is substituted¹. It was shown that this effect was due to a factor other than mRNA.     

Different colonization patterns of two closely related stream insects (Austrosimulium spp.) following disturbance

SUMMARY.

• 1 In many streams, blackfly larvae rapidly colonize scoured surfaces, then decline in numbers as other species are still increasing. Such a colonization pattern may be generated by species that seek disturbed substrata because they prefer scoured surfaces having low epilithon cover (i.e. they are opportunists) or because of lowered faunal densities (i.e. they are fugitives), but this has rarely been tested.
• 2 In the Acheron River, south-eastern Australia, the larvae of the blackfly Austrosimulium torrentium show the typical pattern of increase and decline whereas A. victoriae shows a different pattern of more gradual increase.
• 3 An experiment showed that A. torrentium, consistent with its colonization pattern, responded strongly to treatments that mimicked the effects of disturbance; it colonized bricks with few other animals present regardless of epilithon cover and therefore is potentially a fugitive species. A. victoriae did not respond convincingly to treatments, which is also consistent with its colonization pattern.
• 4 Blackfly larvae of both species preferentially colonized bricks that were in fast-moving water. Hence, A. torrentium only responded to the densities of other fauna when bricks occurred in currents greater than approximately 30 cm s^?1.
• 5 Whilst epilithon cover did not affect abundance of blackfly larvae, it did affect attachment positions. In one experimental treatment, epilithon was reduced on one half of the top surfaces of bricks. More than 50% of larvae on these bricks were attached to the epilithon-reduced halves.
• 6 Our results show that functional feeding or taxonomic groups do not necessarily contain ecologically equivalent taxa; colonization patterns may provide a more useful way of categorizing species for the purposes of modelling these assemblages.

     

Voltage transients elicited by sudden step-up of auxin

Abstract It is hypothesized (i) that the molecular mechanism for the reception of friction and flexure and the mechanism by which auxin enhances ethylene production have in common a release of free calcium into the cytosol, (ii) that elevated cytosolic calcium initiates vesicle exocytosis, and (iii) that the vesicles release a factor or set of factors which depolarizes the plasmalemma and promotes ethylene synthesis. One consequence of such exocytosis should be small, extracellularly observable voltage transients. Transients, ranging in size up to 600 μV and possessing risetimes (10–90%) of approximately 200 ms, are known to be elicited in etiolated stems of Pisum sativum L. by friction and are here shown to be elicited by sudden increase of auxin concentration and also by a Ca²⁺ ionophore.     

Cryptic species within the freshwater isopod Mesamphisopus capensis (Phreatoicidea: Amphisopodidae) in the Western Cape, South Africa: allozyme and 12S rRNA sequence data and morphometric evidence

The freshwater phreatoicidean isopod Mesamphisopus capensis has been regarded as the most widespread of the four Mesamphisopus species occurring in the Western Cape, South Africa. To determine whether this species was monotypic across its distribution over two mountainous regions, separated by a low-lying coastal plain remnant, genetic differentiation among populations from 11 localities was studied through allozyme electrophoresis of 12 loci and sequencing of a 338-bp 12S rRNA mtDNA fragment from representative individuals. Populations of the two regions were separated by a mean identity value of 0.477. Fixed allele differences at two loci distinguished these regions. Estimates of θ indicated substantial differentiation among populations across the entire sample, as well as within each of the regions. Topologies derived through parsimony and neighbour joining supported the monophyly of the two regions. On the basis of these topologies, allele frequencies and an allozyme dendrogram, five groups were identified. Discriminant function analyses, performed on body and pereopod variables independently, revealed these groups to be well differentiated with a high rate of correct a posteriori reclassification. Using genetic distance criteria these five distinct forms may be considered to be putative species. From a conservation perspective, the two regions can be seen to represent two evolutionarily significant units, while the five groups should be regarded as management units.  © 2004 The Linnean Society of London, Biological Journal of the Linnean Society , 2004, 81 , 235–253.     

Domesticating Imperialism: Sexual Politics and the Archaeology of Empire

ABSTRACT  The archaeology of empire is permeated by sexual narratives. This has been especially true of archaeological research on the Spanish Americas, where the material remains of colonial settlements have often been interpreted as products of a literal and figurative marriage between two cultures. However, investigating colonization as a consensual domestic arrangement has masked the ways in which imperial projects relied on the exercise of power, including sexual regulations and sexual coercion. Recent archaeological and ethnohistoric research at the Spanish-colonial military settlement of El Presidio de San Francisco affords a different perspective, one in which the public and institutional exercise of sexual control was central to the imperial project.     

First pairing in Snow Geese Anser caerulescens: at what age and at what time of year does it occur?

In migratory birds, the place and time of pair formation are important parameters for population structure and dynamics. Geese are not only migratory but also exhibit long-term monogamy, and therefore the first pairing event in a bird's lifetime is of particular importance. Through behavioural observations of young, known-age, marked birds conducted on the wintering grounds during three winter seasons we investigated two aspects of the timing of first pair formation in the Wrangel Island population of Snow Geese Anser caerulescens : (1) the age at which birds first form pair bonds, and (2) the seasonal pattern of first pair formation. Wrangel Island Snow Geese paired considerably later in life than Snow Geese from a low-Arctic population: almost none of the birds formed pairs in their second winter, and many were still in sibling groups for at least part of that season. The proportion of birds in pairs continued to increase until at least 5 years of age. Most pairing took place during the observation periods, and in general the proportion of birds in pair bonds increased gradually throughout the winter season. The amount of pairing during spring migration or summer varied annually and among cohorts, indicating that even very young birds may be able to form pair bonds quickly if conditions on the breeding grounds are unusually favourable. Pairing later and remaining in family groups longer may be a response to breeding conditions in this high-Arctic colony. Here, productivity is typically low due to harsh weather and predation, whereas Snow Geese breeding in the low Arctic are less restricted and form pairs and start to breed when younger. The fact that most, but not all, pairing takes place on the wintering grounds helps explain why a previous study found a certain amount of gene flow between the two Wrangel Island subpopulations with separate wintering grounds.