Putative local adaptations modulate the interactions of the carnivorous plant Drosera uniflora Willd (1809) (Droseraceae) with cushion and shrub nurse plants

Cushion and shrub plants are typical high mountain nurse plants. In Magellanic tundras of the Cordillera del Sarao on the coast of Chile, the carnivorous plant Drosera uniflora grows in association with cushions of Donatia fascicularis and the shrubs Chusquea montana var. nigricans and Lepidothamnus fonkii. The different microhabitats for recruitment, in addition to the limited gene flow of D. uniflora, enable us to hypothesise that this plant manifests putative local adaptations, expressed in seed germination and population abundance. Our aim was to evaluate the local adaptation of D. uniflora to cushion and shrub microhabitats by estimating germination and abundance. Local adaptation of seed germination was determined by means of reciprocal transplant experiments. Abundance was determined in small plots located inside, on the edge and outside the nurse plants. Seed origin and growth substrate play a decisive role in D. uniflora germination. Seeds that originate from cushions plant habitat and germinate in the same substrate do so in greater numbers than when those which originate from shrubby habitats. Conversely, seeds that originate from shrubby habitat and germinate in the same substrate do not exhibit significant differences. Abundance was always greater inside than outside of the nurse plants. We concluded that availability and quality of different microhabitats for seed germination and recruitment, together with a limited gene flow, would trigger putative local adaptations in D. uniflora, modulating a long history of interactions with the plants that act as nurse plants.     

Calcium occlusion in plasma membrane Ca2+-ATPase

In this work, we set out to identify and characterize the calcium occluded intermediate(s) of the plasma membrane Ca(2+)-ATPase (PMCA) to study the mechanism of calcium transport. To this end, we developed a procedure for measuring the occlusion of Ca(2+) in microsomes containing PMCA. This involves a system for overexpression of the PMCA and the use of a rapid mixing device combined with a filtration chamber, allowing the isolation of the enzyme and quantification of retained calcium. Measurements of retained calcium as a function of the Ca(2+) concentration in steady state showed a hyperbolic dependence with an apparent dissociation constant of 12 ± 2.2 μM, which agrees with the value found through measurements of PMCA activity in the absence of calmodulin. When enzyme phosphorylation and the retained calcium were studied as a function of time in the presence of La(III) (inducing accumulation of phosphoenzyme in the E(1)P state), we obtained apparent rate constants not significantly different from each other. Quantification of EP and retained calcium in steady state yield a stoichiometry of one mole of occluded calcium per mole of phosphoenzyme. These results demonstrate for the first time that one calcium ion becomes occluded in the E(1)P-phosphorylated intermediate of the PMCA.     

Advantages of granivory in seasonal environments: feeding ecology of an arboreal seed predator in Amazonian forests

Specialized seed predators are uncommon in arboreal vertebrate assemblages, and the hypothesis that consuming seeds of immature fruits – which may be available for relatively long periods compared to mature fruit – could reduce seasonal food scarcity experienced by generalist frugivores remains largely untested. To test this hypothesis, we examined the diet and feeding ecology of bald‐faced saki monkeys Pithecia irrorata in a largely intact forest mosaic of southeastern Peru based on systematic monitoring of five habituated groups over a three‐year period and compared the relative availability of ripe and unripe fruits in their diet. Plant phenology data from individual tree crowns showed that, compared to ripe fruits, immature fruits were available in more tree species, in greater quantities, and for longer periods. Despite pronounced community‐wide seasonal changes in fruit production at our study area, feeding patterns of bald‐faced saki remained largely invariant: fruits comprised approximately 95% of the species’ monthly diet, with seeds alone accounting for 75%, with no major monthly dietary shifts. The flexible exploitation by this species of a consistently available food supply for which it faces little competition likely reduces foraging effort and consumption of less desirable foods, even during prolonged periods of overall fruit scarcity. The relative rarity of immature fruit specialists in tropical forests may reflect the fact that processing the hard pericarps and neutralizing the toxicities of immature seeds present substantial evolutionary hurdles that few arboreal vertebrate species have overcome.     

实验藏酋猴日粮蛋白质营养水平研究

目的本试验旨在研究不同蛋白水平对实验藏酋猴生长性能和血液生化指标的影响并确定幼年实验藏酋猴的蛋白营养需要量。方法选用15只幼年实验藏酋猴随机分为5个处理组,每个处理3个重复,分别饲喂蛋白水平为11．1％、16．1％、20．5％、24．5％和29．8％的日粮,试验期90d。结果随着日粮中蛋白水平的提高,实验藏酋猴的增重、血清白蛋白、球蛋白、天门冬氨酸氨基转移酶、丙氨酸氨基转移酶和尿素氮含量显著增加（P〈0．05）,而血清总蛋白、甘油三酯、γ-谷氨酰胺转移酶和碱性磷酸酶无显著差异。应用折线法确定幼年实验藏酋猴的蛋白营养需要量为23．69％。结论日粮蛋白水平对实验藏酋猴生长性能有显著影响,从生物学和经济学角度考虑,初步认为在本试验条件下,未成年实验藏酋猴日粮蛋白水平以23．69％最合适。     

Expression of baculovirus anti-apoptotic genes p35 and op-iap in cotton (Gossypium hirsutum L.) enhances tolerance to verticillium wilt

Background

Programmed cell death plays an important role in mediating plant adaptive responses to the environment such as the invasion of pathogens. Verticillium wilt, caused by the necrotrophic pathogen Verticillium dahliae, is a serious vascular disease responsible for great economic losses to cotton, but the molecular mechanisms of verticillium disease and effective, safe methods of resistance to verticillium wilt remain unexplored.

Methodology/Principal Findings

In this study, we introduced baculovirus apoptosis inhibitor genes p35 and op-iap into the genome of cotton via Agrobacterium-mediated transformation and analyzed the response of transgenic plants to verticillium wilt. Results showed that p35 and op-iap constructs were stably integrated into the cotton genome, expressed in the transgenic lines, and inherited through the T₃ generation. The transgenic lines had significantly increased tolerance to verticillium wilt throughout the developmental stages. The disease index of T₁–T₃ generation was lower than 19, significantly (P<0.05) better than the negative control line z99668. After treatment with 250 mg/L VD-toxins for 36 hours, DNA from negative control leaves was fragmented, whereas fragmentation in the transgenic leaf DNA did not occur. The percentage of cell death in transgenic lines increased by 7.11% after 60 mg/L VD-toxin treatment, which was less than that of the negative control lines''s 21.27%. This indicates that p35 and op-iap gene expression partially protects cells from VD-toxin induced programmed cell death (PCD).

Conclusion/Significance

Verticillium dahliae can trigger plant cells to die through induction of a PCD mechanism involved in pathogenesis. This paper provides a potential strategy for engineering broad-spectrum necrotrophic disease resistance in plants.     

Implication of new atherosclerotic carotid plaques in the cardiovascular outcome of patients with rheumatoid arthritis

Early detection of atherosclerosis is of major importance to reduce the increased incidence of cardiovascular (CV) complications observed in patients with rheumatoid arthritis (RA). Prospective studies have shown that an abnormally increased carotid intima-media thickness and the presence of plaques assessed by carotid ultrasound are good markers to predict the development of CV events in these patients. Age, classic CV risk factors, and corticosteroid use are also predictors of new plaque formation in patients with RA. Active treatment of the disease may decrease the inflammatory burden, leading to a reduction in the progression of subclinical atherosclerosis in these patients.     

The ability of rufous hummingbirds Selasphorus rufus to dilute and concentrate urine

Most terrestrial animals face the challenge of having to conserve water in a desiccating environment. Not surprisingly, the ability to produce concentrated urine has been relatively well studied in birds. Nectar-feeding birds are unusual among terrestrial animals in that they often ingest and excrete prodigious water volumes to obtain adequate energy. Thus, they confront the unusual challenge of having to conserve electrolytes. The diluting abilities of birds and the renal mechanisms that may correlate with them have been relatively neglected. To elucidate diluting and concentrating abilities in nectar-feeding birds, we fed rufous hummingbirds Selasphorus rufus an electrolyte-free nectar and a nectar containing a range of NaCl concentrations. Hummingbirds had a spectacular (and possibly unique) diluting ability: when fed on electrolyte-free food they produced excreta containing less than 0.5 mM l⁻¹ each of sodium and potassium. Hummingbirds also had a poor concentrating ability, retaining sodium and chloride when their food (0.632 M l⁻¹ sucrose) contained more than 35 mM l⁻¹ of NaCl. The kidneys of hummingbirds do not appear to be suited for concentrating urine, and possibly contain structural features that give them a unique diluting ability compared with those of birds that do not feed on nectar.