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The pink, tubular, nectariferous flowers of Melocactus intortus (Cactaceae) in Puerto Rico are visited by native hummingbirds (Anthracothorax dominicus), but also by invasive honeybees (Apis mellifera) and ants (Solenopsis sp.). We sought to determine if the bees and ants significantly alter the pollination of M. intortus by measuring pollinator effectiveness. Using traditional estimates of effectiveness (visitation rate and seed set), our results show that hummingbirds were the most effective pollinators as expected. Bees and ants were less effective, and their contributions were one‐fourth to one‐tenth of that observed for hummingbirds. We then modified this measure of effectiveness by adding two components, fitness of progeny and temporal availability of visitors, both of which refine estimates of flower visitor effectiveness. With these new estimations, we found that the effectiveness values of all three animal visitors decreased; however, the role of hummingbirds as the principal pollinator was maintained, whereas the effectiveness values of bees and ants approached zero. By these new measures of overall pollinator effectiveness, the invasive honeybees and ants have little effect on the reproductive success of M. intortus. 相似文献
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《Biomarkers》2013,18(7):595-600
AbstractContext: Stroke and/or white matter lesions (WMLs) are significant in Fabry disease. Polymorphisms of angiotensinogen (AGT), AGT Promoter and angiotensinogen II receptor type 1 (AGTR1) are correlated with WMLs.Objectives: We compared AGT. AGT Promoter and AGTR1 genotypes to stroke incidence, Fabry-specific [Mainz Severity Score Index (MSSI)] severity score, and neurologic sub-score (n-MSSI).Methods: Sixty-three Fabry patients and 49 matched controls plus historic controls were genotyped. Institutional Review Board approval was received.Results. C and/or CC alleles of AGT Promoter and AGTR1 were significantly correlated with stroke and n-MSSI.Discussion/conclusion: Findings are suggestive of role of AGT Promoter and AGTR1 genotypes in Fabry phenotypes. 相似文献
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Makoto Tajima Nobuko Sekiguchi Masao Fujimaki 《Bioscience, biotechnology, and biochemistry》2013,77(2):319-320
High phosphate accumulating bacteria were isolated by autoradiography. One isoate, Arthrobacter globiformis PAB-6 accumulated phosphate intracellularly at 20% of dry cell mass in a simple synthetic medium. This amount was 3~7 times higher than type cultures examined. Almost no phosphate was released into the medium after cessation of growth. Fifty percent of total intracellular phosphate was fractionated as nucleic acids, while 20% each was recovered from cold PCA soluble fractions and polyphosphate fractions. The large content of nucleic acids in this bacterium appeared due to increased RNA content, specifically 4 S RNA fraction. 相似文献
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T. R. Shankar Raman 《Journal of biosciences》1997,22(2):203-218
Chital or axis deer (Axis axis) form fluid groups that change in size temporally and in relation to habitat. Predictions of hypotheses relating animal density,
rainfall, habitat structure, and breeding seasonality, to changes in chital group size were assessed simultaneously using
multiple regression models of monthly data collected over a 2 yr period in Guindy National Park, in southern India. Over 2,700
detections of chital groups were made during four seasons in three habitats (forest, scrubland and grassland). In scrubland
and grassland, chital group size was positively related to animal density, which increased with rainfall. This suggests that
in these habitats, chital density increases in relation to food availability, and group sizes increase due to higher encounter
rate and fusion of groups. The density of chital in forest was inversely related to rainfall, but positively to the number
of fruiting tree species and availability of fallen litter, their forage in this habitat. There was little change in mean
group size in the forest, although chital density more than doubled during the dry season and summer. Dispersion of food items
or the closed nature of the forest may preclude formation of larger groups. At low densities, group sizes in all three habitats
were similar. Group sizes increased with chital density in scrubland and grassland, but more rapidly in the latter—leading
to a positive relationship between openness and mean group size at higher densities. It is not clear, however, that this relationship
is solely because of the influence of habitat structure. The rutting index (monthly percentage of adult males in hard antler)
was positively related to mean group size in forest and scrubland, probably reflecting the increase in group size due to solitary
males joining with females during the rut. The fission-fusion system of group formation in chital is thus interactively influenced
by several factors. Aspects that need further study, such as interannual variability, are highlighted. 相似文献
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A respiration-deficient (RD) mutant was isolated from the petite-negative, salt-tolerant yeast Zygosaccharomyces rouxii. One strain among sixteen glycerol-non-utilizing mutants exhibited vigorous liberation of CO2 but no uptake of O2. Furthermore, this strain lacked cytochrome aa3 and had a reduced level of cytochrome b. The few mitochondria found in cells of this strain contained few or no cristae. Salt tolerance and intracellular accumulation of glycerol by the RD strain were almost equal to that of the wild-type strain in media containing NaCl up to 2.5 M. In media with more than 3 M NaCl, the growth of the RD mutant was retarded and the intracellular accumulation of glycerol was depressed in spite of ample production. 相似文献
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Ethylene treatment (approx. 20 l ·1-1 in air for 2 d) of tobacco (Nicotiana tabacum L. cv. Havana 425) plants markedly increases the endo--1,3-glucanase (EC 3.2.1.39) content of leaves. The antigenic form of the enzyme induced is the same one whose production is blocked by treating cultured cells with combinations of auxin (1.1 · 10-5 M -naphthaleneacetic acid) and cytokinin (1.4 · 10-6 M kinetin). Evidence is presented that cultured tobacco cells require ethylene for -1,3-glucanase accumulation: i) ethylene treatment increased the accumulation of \-1,3-glucanase in callus tissues >10 d after subculturing and in cell-suspension cultures; ii) callus tissues can produce ethylene; iii) conditions known to inhibit ethylene production (1 mM CoCl2; 33° C treatment) or ethylene action (approx. 1.6 mmol · 1-1 norbornadiene in air) inhibited -1,3-glucanase accumulation by callus tissues treated for 4 d following subculturing; and, these inhibitory effects were prevented by exogenous ethylene. Combinations of auxin and cytokinin blocked ethylene-induced accumulation of -1,3-glucanase by cell-suspension cultures. The results favor a model in which ethylene induces results favor a model in which ethylene induces 1,3-glucanase accumulation, and auxin and cytokinin inhibit this induction process.Abbreviations NAA
-naphthaleneacetic acid
- NDE
norbornadiene 相似文献