Carbon balance assessment of a Belgian winter wheat crop (Triticum aestivum L.)

The carbon balance of a winter wheat crop in Lonzée, Belgium, was assessed from measurements carried out at different spatial and temporal scales between November 2004 and August 2005. From eddy covariance measurements, the net ecosystem exchange was found to be ?0.63 kg C m^?2 and resulted from the difference between gross primary productivity (GPP) (?1.58 kg C m^?2) and total ecosystem respiration (TER) (0.95 kg C m^?2). The impact of the u_* threshold value on these fluxes was assessed and found to be very small. GPP assessment was partially validated by comparison with an estimation scaled up from leaf scale assimilation measurements. Soil respiration (SR), extrapolated from chamber measurements, was 0.52 kg C m^?2. Net primary productivity, assessed from crop sampling, was ?0.83 kg C m^?2. By combining these fluxes, the autotrophic and heterotrophic components of respiration were deduced. Autotrophic respiration dominated both TER and SR. The evolution of these fluxes was analysed in relation to wheat development.     

The tobacco Ntann12 gene, encoding an annexin, is induced upon Rhodoccocus fascians infection and during leafy gall development

Annexins are calcium-binding proteins that have been associated in plants with different biological processes such as responses to abiotic stress and early nodulation stages. Until now, the implication of annexins during plant–pathogen interactions has not been reported. Here, a novel plant annexin gene induced in tobacco BY-2 cell suspension cultures infected with the phytopathogenic bacterium Rhodococcus fascians (strain D188) has been identified . Expression of this gene, called Ntann12 , is also induced, but to a lower extent, by a strain (D188-5) that is unable to induce leafy gall formation. This gene was also induced in BY-2 cells infected with Pseudomonas syringae but not in cells infected with Agrobacterium tumefaciens or Escherichia coli. Ntann12 expression was also found to be stimulated by abiotic stress, including NaCl and abscissic acid, confirming a putative role in stress signal transduction pathways. In addition, promoter- GUS analyses using homozygous transgenic tobacco seedlings showed that the developmentally controlled expression of Ntann12 is altered upon R. fascians infection. Finally, up-regulation of Ntann12 during leafy gall ontogenesis was confirmed by RT-qPCR. Discussion is focused on the potential role of Ntann12 in biotic and abiotic stress responses and in plant development, both processes that may involve Ca²⁺-dependent signalling.     

Seed caching by woylies Bettongia penicillata can increase sandalwood Santalum spicatum regeneration in Western Australia

Abstract The role a small marsupial, the woylie Bettongia penicillata, might play in the recruitment and regeneration of Western Australian sandalwood Santalum spicatum through its seed caching behaviour was investigated in this study. To determine the fate of the seeds, cotton thread was attached to the seeds and the trail followed. A total of 25 seed caches were located. All of the seeds were found in separate caches, which was consistent with scatter‐hoarding behaviour. The average distance from the source of the seeds to the cache was 43.1 m ± 5.8 m at Dryandra woodland and 29.1 m ± 3.8 m at Karakamia sanctuary. The mean cache depth was 4.3 cm ± 0.2 cm at Dryandra woodland compared with 4.6 cm ± 0.3 cm at Karakamia sanctuary. Significantly more seedlings and saplings grew away from sandalwood trees at sites where woylies were present than at sites with no woylies. In contrast, significantly more seedlings and saplings grew under adult sandalwood trees at the site without woylies than where they were present, although there were significantly lower rates of recruitment and sandalwood regeneration at these sites. In addition, significantly more whole, undisturbed sandalwood seeds were found under the parent trees at the woylie‐free site than at the site with woylies. These findings strongly suggest that little seed dispersal or regeneration of sandalwood occurs in the absence of woylies. Through scatter‐hoarding, woylies have the potential to disperse and cache sandalwood seeds away from the source and significantly alter the subsequent regeneration of sandalwood. Furthermore, by caching seeds large distances away from a source, woylies could modify the distribution of sandalwood in an area.     

Ultrastructural Effects of Lactoferrin Binding on Giardia lamblia Trophozoites

ABSTRACT. Lactoferrin and its derived N-terminal peptide may be important host defenses against Giardia lamblia . We showed earlier that lactoferrin and the derived peptides have potent giardicidal activity in vitro. Using indirect immunofluorescence, we now demonstrate binding of lactoferrin and the peptides to the live trophozoite surface. Iron strongly inhibited binding of lactoferrin, and decreased binding of the peptides, while certain divalent metal ions decreased binding of all forms by about half. Lactoferrin and the peptedes caused striking and complex morphologic changes in the trophozoite plasmalemma, endomembranes and cytoskeleton, and increases the electron density of the lysosome-like peripheral vacuoles.     

EVALUATION OF BITTERNESS OF CAFFEINE IN HOT CHOCOLATE DRINK BY CATEGORY, GRAPHIC, AND RATIO SCALING

Perceived intensity of bitterness of caffeine (0.5 - 1.6 g/100 mL) and of quinine HCI (0.5 - 1.6 g/L) added to hot cocoa gave similar response distributions with concentration by category scales (CS) and magnitude estimation (ME). Using caffeine additives, CS and graphic analogue scales (GS) gave similar bitterness response functions. Parabolic functions provided the best fit between concentration and ratings for CS, GS and ME. The data demonstrated no difference for ME of bitterness intensity between free or fixed moduli. Hedonic responses also were not modified by whether the modulus was free or fixed, however, greater ME values were ascribed to lower concentrations in the series when the reference was 4 g/L than when it was 2 g/L caffeine. CS intensity response distributions were similar between a series with a larger number of low levels versus a series with a larger number of high levels across the same concentration range. The results indicate that ME may be inappropriate for scaling of degree of liking, independent of type of modulus.     

Autogamy in Allogromia laticollaris (Foraminifera)

SYNOPSIS. The life cycles of 2 strains of Allogromia laticollaris (CSH and TPA) raised on experimentally restricted diets have been studied. Cloned cultures of the strains differed in nutritional requirements for continuous reproduction. The TPA strain was more fecund. Both strains have a basically apogamic (asexual) life cycle; only occasionally were gamonts (sexually reproducing individuals) produced. They were autogamous (self-fertilizing) and fusion of the gametes took place within the parental test.
We found in CSH clones a regular alternation of vesicularly nucleated and compactly multinucleated diploid generations. The details of the life cycle of either strain are not known well enough to be able to construct life cycle diagrams more meaningful than that of Arnold. The 2 strains studied differ in cytologic and nuclear detail from each other and from the strain studied by Arnold.     

Inter‐specific gene flow dynamics during the Pleistocene‐dated speciation of forest‐dependent mosquitoes in Southeast Asia

Tropical forests have undergone repeated fragmentation and expansion during Pleistocene glacial and interglacial periods, respectively. The effects of this repeated forest fragmentation in driving vicariance in tropical taxa have been well studied. However, relatively little is known about how often this process results in allopatric speciation, since it may be inhibited by recurrent gene flow during repeated secondary contact, or to what extent Pleistocene‐dated speciation results from ecological specialization in the face of gene flow. Here, divergence times and gene flow between three closely‐related mosquito species of the Anopheles dirus species complex endemic to the forests of Southeast Asia, are inferred using coalescent based Bayesian analysis. An Isolation with Migration model is applied to sequences of two mitochondrial and three nuclear genes, and 11 microsatellites. The divergence of An. scanloni has occurred despite unidirectional nuclear gene flow from this species into An. dirus. The inferred asymmetric gene flow may result from the unique evolutionary adaptation of An. scanloni to limestone karst habitat, and therefore the fitness advantage of this species over An. dirus in regions of sympatry. Mitochondrial introgression has led to the complete replacement of An. dirus haplotypes with those of An. baimaii through a recent (～62 kya) selective sweep. Speciation of An. baimaii and An. dirus is inferred to have involved allopatric divergence throughout much of the Pleistocene. Secondary contact and bidirectional gene flow has occurred only within the last 100 000 years, by which time the process of allopatric speciation seems to have been largely completed.     

Molecular and morphological boundaries of the predatory mite Neoseiulus californicus (McGregor) (Acari: Phytoseiidae)

Neoseiulus californicus (McGregor) is a natural enemy of pest mites used worldwide in many crops. Its correct identification is thus essential to ensure biological control success. The present study aimed to characterize molecular and morphological intraspecific variations for assisting in the diagnosis of the species and to build baseline information about expected variations within a commercially important phytoseiid species. Morphological and molecular [12S rRNA, cytochrome b mitochondrial (mt)DNA, and internal transcribed spacer] analyses were carried out on fourteen populations collected worldwide and on one mass‐reared strain. The genetic distances between the specimens of N. californicus and another related species were high and no overlap was observed, sustaining the reliability of such molecular methods for assisting a specific diagnosis. Furthermore, the genetic distances between populations of N. californicus were very low and overlap between intra‐ and interpopulations distances was observed, except for two populations collected in France (Marsillargues and Midi‐Pyrénées). The high mitochondrial differentiation between these two latter populations and the others questions their specific status: do they belong to the species N. californicus or to another cryptic species? However, using nuclear DNA marker analyses, no distinct differences were observed. Furthermore, even if significant morphological differences were observed between the populations, these differences were very small and the standard errors within each population were very low. We thus concluded that all the populations studied belong to the species N. californicus, despite unexpected high mitochondrial variations. The present study thus displays the importance of an integrative taxonomic approach for avoiding misidentifications. A discussion on morphological and mtDNA variations in relation to diagnostic reliability is developped. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 104 , 393–406.