Hydraulic properties of Pinus halepensis,Pinus pinea and Tetraclinis articulata in a dune ecosystem of Eastern Spain

The hydraulic properties of Pinus pinea, Pinus halepensis and Tetraclinis articulata were studied in a coastal dune area from Eastern Spain. The measured variables include vulnerability to xylem embolism (vulnerability curves), hydraulic conductivity and carbon isotopic discrimination in leaves. Leaf water potentials were also monitored in the three studied populations during an extremely dry period. Our results showed that roots had always wider vessels and higher hydraulic conductivity than branches. Roots were also more vulnerable to xylem embolism and operated closer to their hydraulic limit (i.e., with narrower safety margins). Although it was not quantified, extensive root mortality was observed in the two pines during the study period, in agreement with the high values of xylem embolism (> 75%) predicted from vulnerability curves and the water potentials measured in the field. T. articulata was much more resistant to embolism than P. pinea and P. halepensis. Since T. articulata experienced also lower water potentials, safety margins from hydraulic failure were only slightly wider in this species than in the pines. Combining species and tissues, high resistance to xylem embolism was associated with low hydraulic conductivity and with high wood density. Both relationships imply a cost of having a resistant xylem. The study outlined very different water-use strategies for T. articulata and the pines. Whereas T. articulata had a conservative strategy that relied on the low vulnerability of its conducting system to drought-induced xylem embolism, the two pines showed regulatory mechanisms at different levels (i.e., embolism, root demography) that constrained the absorption of water when it became scarce. This revised version was published online in August 2006 with corrections to the Cover Date.     

Long-term consequences of the alteration of the seed dispersal process of Euphorbia characias due to the Argentine ant invasion

The alteration of the seed dispersal process due to the Argentine ant invasion and its consequences on emergence, recruitment, distribution, and survival of seedlings of Euphorbia characias were analyzed. The study was carried out in two zones of Mediterranean cork‐oak secondary forest, one invaded by L. humile and the other non‐invaded. Two cohorts of E. characias seedlings (those emerged in 2001 and those emerged in 2002) were studied in three study plots in each zone. The level of seed loss due to lack of viability, parasitizing, and vertebrate predation did not differ between the two zones. The mean seed sowing depth was lower in the invaded zone (13.5 mm) than in the non‐invaded zone (22.4 mm). This depth difference implies a longer time needed for seedlings to emerge in the non‐invaded zone but not a different emergence percent under laboratory conditions. In the field study plots seedling recruitment did not differ between the two zones, probably due to the trade‐off between the differences in the initial number of seeds released (higher in the non‐invaded zone) and the different emergence proportions (higher in the invaded zone). As for the spatial characteristics of emerged seedlings, no differences in the mean seedling distance to the nearest inflorescence or to the nearest seedling or in the pattern of seedling distribution were found between zones. Seedling survival was assessed once a month until they had reached maturity or until all of them had died. The median seedling survival time was similar between the invaded and the non‐invaded zones. Survival curves also did not differ between zones. The present study suggests a functional equivalence of the Argentine ant after the replacement of the native ant species. Despite the initial differences found, the final reproductive success of E. characias was not altered after the invasion. However, the case of E. characias seems unlikely to be the rule, and the seed dynamics of other species may be altered, i.e. increased or decreased, and thus positively or negatively affected by the invasion.     

Cardiotrophin-1 is expressed in adipose tissue and upregulated in the metabolic syndrome

Adipose tissue is a target for cardiotrophin-1 (CT-1), a cytokine member of the IL-6 family of cytokines that is involved in cardiac growth and dysfunction. However, it is unknown whether adipocytes are a source of CT-1 and whether CT-1 is overexpressed in diseases characterized by increased fat depots [i.e., the metabolic syndrome (MS)]. Thus this work aimed 1) to test whether adipose tissue expresses CT-1 and whether CT-1 expression can be modulated and 2) to compare serum CT-1 levels in subjects with and without MS diagnosed by National Cholesterol Education Program Adult Treatment Panel III criteria. Gene and protein expression of CT-1 was determined by real-time RT-PCR, ELISA, and Western blotting. CT-1 expression progressively increased, along with differentiation time from preadipocyte to mature adipocyte in 3T3-L1 cells. CT-1 expression was enhanced by glucose in a dose-dependent manner in these cells. mRNA and protein CT-1 expression was also demonstrated in human adipose biopsies. Immunostaining showed positive staining in adipocytes. Finally, increased CT-1 serum levels were observed in patients with MS compared with control subjects (127 +/- 9 vs. 106 +/- 4 ng/ml, P < 0.05). Circulating levels of CT-1 were associated with glucose levels (r = 0.2, P < 0.05). Taken together, our data suggest that adipose tissue can be recognized as a source of CT-1, which could account for the high circulating levels of CT-1 in patients with MS.     

Effect of temperature on the oviposition rate of Argentine ant queens (Linepithema humile Mayr) under monogynous and polygynous experimental conditions

Data concerning the influence of temperature on a species' physiological parameters can be a useful tool for predicting its potential distribution range, but in the case of the Argentine ant, data based on its physiological needs are too scarce and incomplete to make accurate predictions of this type. In the present study, we offer new and complete data concerning the Argentine ant queen's oviposition rate under a wide range of temperatures in the laboratory. We analyzed the oviposition rate of the Argentine ant (Linepithema humile) at 12 experimental temperatures: 10, 12, 14, 16, 18, 21, 24, 26, 28, 30, 32 and 34 degrees C under monogynous conditions (one queen per nest) and three different polygynous conditions (two, four and eight queens per nest). We found that temperature affected their oviposition rate and that the effect was similar regardless of the number of queens in the nest. Egg laying was at its maximum at 28 degrees C, with variation in the upper and lower temperature limits at which oviposition took place depending on the degree of polygyny. Oviposition rates were negatively correlated with the number of queens in the nest. We also observed a marked variation in the oviposition rate of queens subjected to the same experimental conditions.     

Caleosins: Ca2+-binding proteins associated with lipid bodies

We have previously identified a rice gene encoding a 27 kDa protein with a single Ca²⁺-binding EF-hand and a putative membrane anchor. We report here similar genes termed caleosins, CLO, in other plants and fungi; they comprise a multigene family of at least five members in Arabidopsis (AtClo1–5). Northern hybridization demonstrated that AtClo2–4 mRNAs levels were low in various tissues, while AtClo1 mRNA levels were high in developing embryos and mature seeds. Analysis of transgenic Arabidopsis plants expressing the GUS reporter under control of the AtClo1 promoter showed strong levels of expression in developing embryos and also in root tip cells. Antibodies raised against AtCLO1 were used to detect caleosin in cellular fractions of Arabidopsis and rapeseed. This indicated that caleosins are a novel class of lipid body proteins, which may also be associated with an ER subdomain.     

Hydatid cyst in soft tissues mimicking malignant tumors. Diagnosis by fine needle aspiration cytology

OBJECTIVE: To evaluate the role of fine needle aspiration cytology in the diagnosis of soft tissue hydatid cysts. STUDY DESIGN: Five cases of soft tissue hydatid cyst were diagnosed primarily by fine needle aspiration cytology. RESULTS: In all cases, large fragments of acellular material, finely lamellated, were found. There were no complications related to fine needle aspiration, and histologic studies confirmed the diagnosis of hydatid cyst. CONCLUSION: When acellular, laminated fragments suggestive of a laminated layer are identified on smears, hydatid cyst should be considered in the differential diagnosis, even in atypical locations and in the absence of hooklets, protoscolices or both.     

The fuc1 gene product (20 kDa FUC1) of Pisum sativum has no α-L-fucosidase activity

An -L-fucosidase purified from pea (Pisum sativum L. cv Alaska) epicotyl was previously described as a cell wall enzyme of 20 kDa that hydrolyses terminal -L-fucosidic linkages from oligosaccharide fragments of xyloglucan. cDNA and genomic copies were further isolated and sequenced. The predicted product of the cDNA and the genomic clone (fuc1), was a 20 kDa protein containing a signal peptide and five cysteines. This was the first -L-fucosidase gene to be cloned in plants but its fucosidase activity has not been demonstrated. Here, our biochemical and immuno analyses suggest that fuc1 does not encode an -L-fucosidase. Pea fuc1 expressed in Escherichia coli, insect cells and Arabidopsis thaliana produced recombinant proteins without -L-fucosidase activity. Pea plants had endogenous -L-fucosidase activity, but the enzyme was not recognised by an antibody produced against recombinant FUC1 protein expressed in E. coli. In contrast, the antibody immunoprecipitated a 20 kDa protein which was inactive. By chromatographic analysis of pea protein extracts, we separated -L-fucosidase-active fractions from the 20 kDa protein fractions. We conclude that the -L-fucosidase activity is not attributable to the 20 kDa FUC1 protein. A new function for fuc1 gene product, now named PIP20 (for protease inhibitor from pea) is proposed.     

Does differential seed siring success change over time or with pollination history in wild radish, Raphanus sativus (Brassicaceae)?

Previous work with wild radish has shown that pollen donors sire different numbers of seeds and that the condition of the maternal tissue affects seed paternity, suggesting that both pollen donor characteristics and maternal tissue affect mating. However, because these results are from the greenhouse, it is difficult to know whether they would hold true in the field. Here, we performed hundreds of crosses on several maternal plants to simulate changes during the flowering season of field plants. During the experiment, maternal resource availability changed due to the costs of producing fruits, and we determined the pollination history of a plant by performing crosses in specific orders. Examination of seed paternity showed that there were small differences in pollen donor success at the beginning of the experiment when maternal resources were abundant. Differential pollen donor success was greatest slightly later in the flowering period, but declined toward the end of the experiment. Thus, maternal plants may distinguish most among pollen donors when they have both abundant resources and experience with the differences in quality of available pollen donors. In contrast, there were few significant effects of the recent pollination history of plants on pollen donor success. Finally, despite the changes in mating performance over time, there were strong overall differences in pollen donor success, suggesting that seasonal changes in the field will not eliminate the potential for nonrandom mating.