The effects on Arbutus unedo L. of long-term exposure to elevated CO2

Arbutus unedo is a sclerophyllous evergreen, characteristic of Mediterranean coastal scrub vegetation. In Italy, trees of A. unedo have been found close to natural CO₂ vents where the mean atmospheric carbon dioxide concentration is about 2200 μmol mol^?1. Comparisons were made between trees growing in elevated and ambient CO₂ concentrations to test for evidence of adaptation to long-term exposure to elevated CO₂. Leaves formed at elevated CO₂ have a lower stomatal density and stomatal index and higher specific leaf area than those formed at ambient CO₂, but there was no change in carbon to nitrogen ratios of the leaf tissue. Stomatal conductance was lower at elevated CO₂ during rapid growth in the spring. In mid-summer, under drought stress, stomatal closure of all leaves occurred and in the autumn, when stress was relieved, the conductance of leaves at both elevated and ambient CO₂ increased. In the spring, the stomatal conductance of the new flush of leaves at ambient CO₂ was higher than the leaves at elevated CO₂, increasing instantaneous water use efficiency at elevated CO₂. Chlorophyll fluorescence measurements suggested that elevated CO₂ provided some protection against photoinhibition in mid-summer. Analysis of A/C_i curves showed that there was no evidence of either upward or downward regulation of photosynthesis at elevated CO₂. It is therefore anticipated that A. unedo will have higher growth rates as the ambient CO₂ concentrations increase.     

Natural CO2 springs in Italy: a resource for examining long-term response of vegetation to rising atmospheric CO2 concentrations

It is estimated that more than 100 geothermal CO₂ springs exist in central-western Italy. Eight springs were selected in which the atmospheric CO₂ concentrations were consistently observed to be above the current atmospheric average of 354μmol mol^-1. CO₂ concentration measurements at some of the springs are reported. The springs are described, and their major topographic and vegetational features are reported. Preliminary observations made on natural vegetation growing around the gas vents are then illustrated. An azonal pattern of vegetation distribution occurs around every CO₂ spring regardless of soil type and phytoclimatic areas. This is composed of pioneer populations of a Northern Eurasiatic species (Agrostis canina L.) which is often associated with Scirpus lacustris L. The potential of these sites for studying the long-term response of vegetation to rising atmospheric CO₂ concentrations is discussed.     

Chamber growth in ammonites inferred from colour markings and naturally etched surfaces of Cretaceous vascoceratids from Nigeria

Cretaceous Vascoceras and Jurassic Lytoceras show colour markings and etched surfaces representing original organic membranes between the septa. The main difference between the formation of ammonite and Nautilus chambers involved the continuous secretion of a gelatinous cameral liquid to support the ammonite mantle when it moved forward. The gel containing cyclically secreted membranes. here named pseudosepta, resembled the intra-cameral structures of the cuttlebone in Sepia. Pseudoscpta are attached to the shell wall in pseudosutures (Pseudoloben) which are particularly visible in the saddles of the septal suture and tend to mimic them. Their shape suggests reconstruction of posterior mantle shape during translocation. Drag-bands (Schleppstreifen) are spiral markings formed by the overlapping pseudosepta along the axial traces of the foliole folds. The chamber of ammonites was formed by a locally muscular mantle in a tripartite cycle: (1) the mantle initially remained attached to the saddles of the completed septal suture while muscular tissue within the umbilical lobes was contracted and rapidly reattached to the side of the lateral saddles; (2) the whole mantle subsequently crept forward by secreting a gelatinous matrix which contained telescoped membranes, with an adhesive function on pseudolobc flanks; (3) the mantle almost ceased to move within the sites of future lobules, but expanded and crept on before forming the mural and 'gutter' ridges of the septum. □ Ammonites, chamber growth, vascoceratids, LYTOCERAS, Nigeria.     

WHEN SPEED TRULY MATTERS, OPENNESS IS THE ANSWER

In this paper I analyse the ethical implications of the two main competing methodologies in genomic research. I do not aim to provide another contribution from the mainstream legal and public policy perspective; rather I offer a novel approach in which I analyse and describe the patent-and-publish regime (the proprietary regime) led by biologist J. Craig Venter and the 'open-source' methodologies led by biotechnology Nobel laureate John Sulston. The 'open-source methodologies' arose in biotechnology as an alternative to the patent-and-publish regime in the wake of the explosion in computer technology. Indeed, the tremendous increase in computer technology has generated a corresponding increase in the pace of genomics research. I conclude this paper by arguing that while the patent-and-publish method is a transactional method based on the exchange of extrinsic goods (patents in exchange for research funds), the free and open-source methodology (FLOSS) ¹ is a transformational method based on a visionary ideal of science, which leads to prioritizing intrinsic goods in scientific research over extrinsic goods.     

Effects of Constant and Variable Nitrogen Supply on Sunflower (Helianthus annuus L.) Leaf Cell Number and Size

The effects of nitrogen (N) availability on cell number andcell size, and the contribution of these determinants to thefinal area of fully expanded leaves of sunflower (Helianthusannuus L.) were investigated in glasshouse experiments. Plantswere given a high (N =315 ppm) or low (N=21 ppm) N supply andwere transferred between N levels at different developmentalstages (5 to 60% of final size) of target leaves. The dynamicsof cell number in unemerged (< 0.01 m in length) leaves ofplants growing at high and low levels of N supply were alsofollowed. Maximum leaf area (LA_max) was strongly (up to two-fold)and significantly modified by N availability and the timingof transfer between N supplies, through effects on leaf expansionrate. Rate of cell production was significantly (P<0.05)reduced in unemerged target leaves under N stress, but therewas no evidence of a change in primordium size or in the durationof the leaf differentiation–emergence phase. In fullyexpanded leaves, number of cells per leaf (N_cell), leaf areaper cell (LA_cell) and cell area (A_cell) were significantly reducedby N stress. WhileLA_cell and A_cellresponded to changeover treatmentsirrespective of leaf size, significant (P<0.05) changes inN_cellonly occurred when the changeover occurred before the leafreached approx. 10% of LA_max. There were no differential effectsof N on numbers of epidermal vs. mesophyll cells. The resultsshow that the effects of N on leaf size are largely due to effectson cell production in the unemerged leaf and on both cell productionand expansion during the first phase of expansion of the emergedleaf. During the rest of the expansion period N mainly affectsthe expansion of existing cells. Cell area plasticity permitteda response to changes in N supply even at advanced stages ofleaf expansion. Increased cell expansion can compensate forlow N_cellif N stress is relieved early in the expansion of emergedleaves, but in later phases N_cellsets a limit to this response.Copyright 1999 Annals of Botany Company Helianthus annuus, leaf expansion, leaf cell number, leaf cell size, nitrogen, leaf growth, sunflower.     

Landmark superimposition for taxonomic identification

The identification of organisms is a time-consuming task even for highly specialized researchers. Many ways to accelerate the identification process have been devised – from pictorial keys to automatic, machine identification – with different degrees of success. This paper explores landmark configurations as an aid to taxonomic identification. The basic hypothesis rests on the analogy between human fingerprints and organism landmark configuration. Translated into biological terms, it asks whether individual landmark configurations can be used as diagnostic characteristics for species identification. Water mites of the genus Torrenticola were used as test organisms. The results show that identification can be made simpler through the use of landmark configurations.  © 2004 The Linnean Society of London, Biological Journal of the Linnean Society , 2004, 81 , 267–274.     

Covariation of morphological characters in the Triassic ammonoid Czekanowskites rieberi

The Triassic ammonoid Czekanowskites rieberi displays a covariation of morphological charac ters, which is rather common in ammonoids. Its morphological spectrum ranges from laterally compressed, involute, weakly ribbed forms to depressed, semiinvolute, strongly ribbed forms. In order to study this covariation, fifteen axially cut specimens have been analyzed by means of image analysis, which allows us to obtain the ontogenetic record of radii, area and perimeter of the individual whorl cross-sections. A logarithmic model of growth has been applied. Our data indicate that, owing to the covariation, the radii from the origin to the venter and to the umbil ical seam of a given whorl section vary inversely in order to maintain the relative position of the center of gravity of the whorl cross-section both throughout the ontogeny of single specimens and within the population. This influences hydrostatic parameters, such as the position of the center of mass and the orientation and stability of the shell. Since the ontogenetic record of the angular length of the body chamber is not known, we have calculated those hydrostatic varia bles using two mutually exclusive assumptions: (1) the angular length of the body chamber was constant throughout ontogeny and (2) the volume of the body chamber grew monotonically with the revolution angle. Fluctuations of the three hydrostatic variables were always less important in the first assumption. In any case, the spectrum of, for example, theoretical orien tations is comparable to those observed in the species of present-day Nautilus. The range of adult body-chamber length observed in C. rieberi is much narrower than the theoretical adult body-chamber length calculated under the second assumption which indicates that a certain control over this parameter existed in the natural population, probably in order to maintain a narrow range in orientation and stability. The excess or deficit in soft-body weight was probably compensated by inverse variations in shell-wall weight. The main conclusion is that, despite the extreme morphological variability, hydrostatic and, possibly, hydrodynamic properties of the population remained within narrow limits.