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Mesophyll conductance decreases in the wild type but not in an ABA‐deficient mutant (aba1) of Nicotiana plumbaginifolia under drought conditions 下载免费PDF全文
YUSUKE MIZOKAMI KO NOGUCHI MIKIKO KOJIMA HITOSHI SAKAKIBARA ICHIRO TERASHIMA 《Plant, cell & environment》2015,38(3):388-398
Under drought conditions, leaf photosynthesis is limited by the supply of CO2. Drought induces production of abscisic acid (ABA), and ABA decreases stomatal conductance (gs). Previous papers reported that the drought stress also causes the decrease in mesophyll conductance (gm). However, the relationships between ABA content and gm are unclear. We investigated the responses of gm to the leaf ABA content [(ABA)L] using an ABA‐deficient mutant, aba1, and the wild type (WT) of Nicotiana plumbaginifolia. We also measured leaf water potential (ΨL) because leaf hydraulics may be related to gm. Under drought conditions, gm decreased with the increase in (ABA)L in WT, whereas both (ABA)L and gm were unchanged by the drought treatment in aba1. Exogenously applied ABA decreased gm in both WT and aba1 in a dose‐dependent manner. ΨL in WT was decreased by the drought treatment to ?0.7 MPa, whereas ΨL in aba1 was around ?0.8 MPa even under the well‐watered conditions and unchanged by the drought treatment. From these results, we conclude that the increase in (ABA)L is crucial for the decrease in gm under drought conditions. We discuss possible relationships between the decrease in gm and changes in the leaf hydraulics. 相似文献
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Kelly S Swanson Scot E Dowd Jan S Suchodolski Ingmar S Middelbos Brittany M Vester Kathleen A Barry Karen E Nelson Manolito Torralba Bernard Henrissat Pedro M Coutinho Isaac KO Cann Bryan A White George C Fahey Jr 《The ISME journal》2011,5(4):639-649
This study is the first to use a metagenomics approach to characterize the phylogeny and functional capacity of the canine gastrointestinal microbiome. Six healthy adult dogs were used in a crossover design and fed a low-fiber control diet (K9C) or one containing 7.5% beet pulp (K9BP). Pooled fecal DNA samples from each treatment were subjected to 454 pyrosequencing, generating 503 280 (K9C) and 505 061 (K9BP) sequences. Dominant bacterial phyla included the Bacteroidetes/Chlorobi group and Firmicutes, both of which comprised ∼35% of all sequences, followed by Proteobacteria (13–15%) and Fusobacteria (7–8%). K9C had a greater percentage of Bacteroidetes, Fusobacteria and Proteobacteria, whereas K9BP had greater proportions of the Bacteroidetes/Chlorobi group and Firmicutes. Archaea were not altered by diet and represented ∼1% of all sequences. All archaea were members of Crenarchaeota and Euryarchaeota, with methanogens being the most abundant and diverse. Three fungi phylotypes were present in K9C, but none in K9BP. Less than 0.4% of sequences were of viral origin, with >99% of them associated with bacteriophages. Primary functional categories were not significantly affected by diet and were associated with carbohydrates; protein metabolism; DNA metabolism; cofactors, vitamins, prosthetic groups and pigments; amino acids and derivatives; cell wall and capsule; and virulence. Hierarchical clustering of several gastrointestinal metagenomes demonstrated phylogenetic and metabolic similarity between dogs, humans and mice. More research is required to provide deeper coverage of the canine microbiome, evaluate effects of age, genetics or environment on its composition and activity, and identify its role in gastrointestinal disease. 相似文献
4.
The aim of this paper is to investigate the effectiveness and cost-effectiveness of three malaria preventive measures (use of treated bednets, spray of insecticides and a possible treatment of infective humans that blocks transmission to mosquitoes). For this, we consider a mathematical model for the transmission dynamics of the disease that includes these measures. We first consider the constant control parameters’ case, we calculate the basic reproduction number and investigate the existence and stability of equilibria; the model is found to exhibit backward bifurcation. We then assess the relative impact of each of the constant control parameters measures by calculating the sensitivity index of the basic reproductive number to the model's parameters. In the time-dependent constant control case, we use Pontryagin's Maximum Principle to derive necessary conditions for the optimal control of the disease. We also calculate the Infection Averted Ratio (IAR) and the Incremental Cost-Effectiveness Ratio (ICER) to investigate the cost-effectiveness of all possible combinations of the three control measures. One of our findings is that the most cost-effective strategy for malaria control, is the combination of the spray of insecticides and treatment of infective individuals. This strategy requires a 100% effort in both treatment (for 20 days) and spray of insecticides (for 57 days). In practice, this will be extremely difficult, if not impossible to achieve. The second most cost-effective strategy which consists of a 100% use of treated bednets and 87% treatment of infective individuals for 42 and 100 days, respectively, is sustainable and therefore preferable. 相似文献
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JASON E. JANNOT ALEXANDER E. KO DUSTIN L. HERRMANN LAURA SKINNER EMILY BUTZEN OLCAY AKMAN STEVEN A. JULIANO 《Ecological Entomology》2009,34(5):644-651
1. Density‐dependent phase polyphenism occurs when changes in density during the juvenile stages result in a developmental shift from one phenotype to another. Density‐dependent phase polyphenism is common among locusts (Orthoptera: Acrididae). 2. Previously, we demonstrated a longitudinal geographic cline in adult body size (western populations = small adults; eastern populations = large adults) in the eastern lubber grasshopper (Romalea microptera) in south Florida. As lubbers are confamilial with locusts, we hypothesised that the longitudinal size cline was partly due to density‐dependent phase polyphenism. 3. We tested the effect of density, population, and density×population interaction on life‐history traits (pronotum length, mass, cumulative development time, growth rate) of, and proportion surviving to, each of the five instars and the adult stage in a 2 × 3 factorial laboratory experiment with two lubber populations, each reared from hatchling to adult at three different densities. 4. The effect of density on life history and survival was independent of the effects of population on life history and survival. Higher densities led to larger adult sizes (pronotum, mass) and lower survivorship. The western population had smaller adult masses, fewer cumulative days to the adult stage, and higher survivorship than the eastern population. 5. Our data suggest that lubber grasshoppers exhibit density‐dependent phase polyphenism initiated by the physical presence of conspecifics. However, the plastic response of adult size to density observed in the laboratory is not consistent with the relationship between phenotypes and adult density in the field. Genetic differences between populations observed in the laboratory could contribute to size and life‐history differences among lubber populations in the field. 相似文献
7.
KO NOGUCHI NICOLAS L. TAYLOR A. HARVEY MILLAR HANS LAMBERS & DAVID A. DAY 《Plant, cell & environment》2005,28(6):760-771
The present authors have shown previously that both respiration rates and in vivo activities of the alternative oxidase (AOX) of leaves of Alocasia odora, a shade species, are lower than those in sun species, thereby optimizing energy production under limited light conditions (Noguchi et al., Australian Journal of Plant Physiology 28, 27–35, 2001). In the present study, mitochondria isolated from A. odora leaves were examined in order to investigate the biochemical basis for the differences in respiratory parameters. Alocasia odora and spinach plants were cultivated under both high and low light intensities, mitochondria were isolated from their leaves, and their respiratory properties compared. Mitochondrial content of leaf extracts from the two species was estimated using fumarase activities and antibody detection of porin (the voltage-dependent anion channel of the outer mitochondrial membrane). On a mitochondrial protein basis, spinach leaves showed higher capacities of the cytochrome pathway and cytochrome c oxidase (COX) than A. odora leaves. However, on a mitochondrial protein basis, A. odora showed higher capacities of AOX, which had a high affinity for ubiquinone when activated by pyruvate. Alocasia odora also had larger amounts of mitochondrial protein per leaf dry weight, even under severely shaded conditions, than spinach. Lower growth light intensity led to lower activities of most pathways and proteins tested in both species, especially glycine-dependent oxygen uptake. In the low light environment, most of the AOX protein in A. odora leaves was in its inactive, oxidized dimer form, but was converted to its reduced active form when plants were grown under high light. This shift may prevent over-reduction of the respiratory chain under photo-oxidative conditions. 相似文献
8.
Using natural spawning and artificial fertilization, the entire process of development from eggs to juveniles was observed in the sea-star, Asterina batheri Goto.
The breeding season of this animal in Tsukumo Bay and Toyama Bay is estimated to be late summer. The spawned eggs are approximately 430 μm in diameter and float near the surface of sea water. They develop, through a wrinkled blastula stage by holoblastic. radial cleavage, into a pear-shaped brachiolaria bearing 3 blunt brachiolar arms. Metamorphosis takes place while the brachiolariae are swimming. Ten days after fertilization, metamorphosis is complete; the resulting juveniles are about 800 μm in diameter and colored pale brown with a green tint. They bear 2 pairs of tube-feet and a terminal tentacle in each arm.
Development of this species is thus of the direct type, and very similar in every respect to that of Asterina coronata japonica , which is closely related to the present species. 相似文献
The breeding season of this animal in Tsukumo Bay and Toyama Bay is estimated to be late summer. The spawned eggs are approximately 430 μm in diameter and float near the surface of sea water. They develop, through a wrinkled blastula stage by holoblastic. radial cleavage, into a pear-shaped brachiolaria bearing 3 blunt brachiolar arms. Metamorphosis takes place while the brachiolariae are swimming. Ten days after fertilization, metamorphosis is complete; the resulting juveniles are about 800 μm in diameter and colored pale brown with a green tint. They bear 2 pairs of tube-feet and a terminal tentacle in each arm.
Development of this species is thus of the direct type, and very similar in every respect to that of Asterina coronata japonica , which is closely related to the present species. 相似文献
9.
Ike S. Okosun Terrence E. Forrester Charles N. Rotimi Babatunde O. Osotimehin Walinjom F. Munu Richard S. Cooper 《Obesity (Silver Spring, Md.)》1999,7(5):453-462
OKOSUN, IKE S., TERRENCE E. FORRESTER, CHARLES N. ROTIMI, BABATUNDE O. OSOTIMEHIN, WALINJOM F. MUNA, AND RICHARD S. COOPER. Abdominal adiposity in six populations of West African descent: prevalence and population attributable fraction of hypertension. Obes Res. Objectives: The objective of this investigation was to examine the prevalence of abdominal adiposity and its association with the prevalence of hypertension among African descent populations in Nigeria, Cameroon, Jamaica, St. Lucia, Barbados, and the United States (US). Research Method: The data for this investigation were obtained from the International Collaborative Study on Hypertension in Blacks. Hypertension was defined as mean diastolic blood pressure ≥90 mmHg, systolic blood pressure ≥140 mmHg or current treatment with prescribed anti-hypertension medication. Abdominal overweight was defined as waist circumference (WC) ≥94 and ≥80 cm for men and women, respectively. Abdominal obesity was defined as WC ≥102 and ≥88 cm for men and women, respectively. We estimated the site-specific prevalence of abdominal overweight and obesity across age and body mass index cut-points. We also calculated the population attributable fraction (AF) of hypertension due to abdominal adiposity. Results: The prevalence of hypertension in these populations was tightly linked to abdominal adiposity. Increases in abdominal overweight accompanied an increasing degree of Westernization, rising from 6. 4% and 26. 3% in Nigeria, 16. 5% and 62. 8% in Cameroon, 15. 8% and 58. 6% in Jamaica, 14. 3% and 62. 1% in St. Lucia, 21. 4% and 70. 3% in Barbados to 38. 9%, and 76. 4% in the US for men and women, respectively. The corresponding values for abdominal obesity were 1. 6% and 12. 3% in Nigeria, 5. 1% and 38. 9% in Cameroon, 5. 5% and 34. 0% in Jamaica, 2. 7% and 40. 7% in St. Lucia, 7. 8% and 44. 7% in Barbados to 21. 7% and 54. 1% in the US for men and women, respectively. Body mass index-adjusted estimates of AF suggest that in most of these populations, especially in females, avoidance of abdominal overweight or obesity would help to curb the development of hypertension. Discussion: An important public health challenge is to clarify how lifestyle factors influence risks of abdominal adiposity and ultimately the increased risk of cardiovascular diseases. 相似文献
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