Sinking-rate response of natural assemblages of temperate and subtropical phytoplankton to nutrient depletion

1984 ◽  
Vol 83 (3) ◽  
pp. 293-300 ◽  
Author(s):  
P. K. Bienfang ◽  
P. J. Harrison
Keyword(s):  
Nutrient Depletion ◽  
Sinking Rate

TOR and MAP kinase pathways synergistically regulate autophagy in response to nutrient depletion in fission yeast

Autophagy ◽  
2021 ◽  
pp. 1-16
Author(s):  
Cristina Corral-Ramos ◽  
Rubén Barrios ◽  
José Ayté ◽  
Elena Hidalgo
Keyword(s):  
Map Kinase ◽  
Fission Yeast ◽  
Nutrient Depletion ◽  
Map Kinase Pathways

scholarly journals Nutritional Regulation of the Sae Two-Component System by CodY inStaphylococcus aureus

2018 ◽  
Vol 200 (8) ◽  
Author(s):  
Kevin D. Mlynek ◽  
William E. Sause ◽  
Derek E. Moormeier ◽  
Marat R. Sadykov ◽  
Kurt R. Hill ◽  
...  
Keyword(s):  
Gene Expression ◽  
Virulence Factors ◽  
Virulence Gene ◽  
Nutrient Depletion ◽  
Global Regulator ◽  
Two Component System ◽  
Component System ◽  
Content Type ◽  
Virulence Gene Expression ◽  
Two Component

ABSTRACTStaphylococcus aureussubverts innate defenses during infection in part by killing host immune cells to exacerbate disease. This human pathogen intercepts host cues and activates a transcriptional response via theS. aureusexoprotein expression (SaeR/SaeS [SaeR/S]) two-component system to secrete virulence factors critical for pathogenesis. We recently showed that the transcriptional repressor CodY adjusts nuclease (nuc) gene expression via SaeR/S, but the mechanism remained unknown. Here, we identified two CodY binding motifs upstream of thesaeP1 promoter, which suggested direct regulation by this global regulator. We show that CodY shares a binding site with the positive activator SaeR and that alleviating direct CodY repression at this site is sufficient to abrogate stochastic expression, suggesting that CodY repressessaeexpression by blocking SaeR binding. Epistasis experiments support a model that CodY also controlssaeindirectly through Agr and Rot-mediated repression of thesaeP1 promoter. We also demonstrate that CodY repression ofsaerestrains production of secreted cytotoxins that kill human neutrophils. We conclude that CodY plays a previously unrecognized role in controlling virulence gene expression via SaeR/S and suggest a mechanism by which CodY acts as a master regulator of pathogenesis by tying nutrient availability to virulence gene expression.IMPORTANCEBacterial mechanisms that mediate the switch from a commensal to pathogenic lifestyle are among the biggest unanswered questions in infectious disease research. Since the expression of most virulence genes is often correlated with nutrient depletion, this implies that virulence is a response to the lack of nourishment in host tissues and that pathogens likeS. aureusproduce virulence factors in order to gain access to nutrients in the host. Here, we show that specific nutrient depletion signals appear to be funneled to the SaeR/S system through the global regulator CodY. Our findings reveal a strategy by whichS. aureusdelays the production of immune evasion and immune-cell-killing proteins until key nutrients are depleted.

Lepeophtheirus salmonis (Krøyer, 1837): second nauplius and copepodid locomotor appendages, surface areas and possible appendage functions

Crustaceana ◽  
2013 ◽  
Vol 86 (13-14) ◽  
pp. 1695-1710 ◽  
Author(s):  
Susan E. Allen ◽  
A. G. Lewis
Keyword(s):  
Body Position ◽  
Ventral Surface ◽  
Total Surface Area ◽  
The Body ◽  
Lepeophtheirus Salmonis ◽  
Sinking Rate ◽  
Surface Areas ◽  
Thoracic Legs ◽  
Two Stages ◽  
Suitable Location

Locomotor appendage-body relationships were used to examine whether swimming or reduction in sinking rate is the more important function in the second nauplius and copepodid stages of Lepeophtheirus salmonis (Krøyer, 1837). Except for the similarity in swimming appendage surface areas without setae, the appendages of the two stages are morphologically distinct. Although the nauplius is smaller than the copepodid it has long slender appendages that, with setae, provide greater total surface area than the paddle-shaped copepodid thoracic legs. Copepodid thoracic legs are more similar to those used for swimming by planktonic copepods although with more limited propulsion capability. Naupliar appendages project from the body while copepodid appendages can be folded against the ventral surface, improving hydrodynamic flow as well as body position after attachment to a host. Both copepodid and naupliar appendages are of sufficient size that they should provide escape velocities of more than 100 mm ⋅ s−1. The nature and display of the naupliar appendages suggest they could be used to reduce sinking rate by as much as 64%, reducing the need to swim to maintain a suitable location in the water. Although copepodid thoracic legs could reduce sinking rate by over 40%, their position on the ventral surface and the nature of other appendages suggests a more important use, for orientation and attachment once a host is located.

Behavior of Cu, Ni and Cd during nutrient depletion in a spring bloom in Funka Bay

1998 ◽  
Vol 54 (6) ◽  
pp. 619-627 ◽  
Author(s):  
Isao Kudo ◽  
Katsuhiko Matsunaga
Keyword(s):  
Spring Bloom ◽  
Nutrient Depletion ◽  
Funka Bay

scholarly journals Coccolith dissolution within copepod guts affects fecal pellet density and sinking rate

2018 ◽  
Vol 8 (1) ◽  
Author(s):  
Meredith M. White ◽  
Jesica D. Waller ◽  
Laura C. Lubelczyk ◽  
David T. Drapeau ◽  
Bruce C. Bowler ◽  
...  
Keyword(s):  
Fecal Pellet ◽  
Sinking Rate ◽  
Pellet Density

scholarly journals Roots-eye view: Using microdialysis and microCT to non-destructively map root nutrient depletion and accumulation zones

2017 ◽  
Vol 40 (12) ◽  
pp. 3135-3142 ◽  
Author(s):  
Richard Brackin ◽  
Brian S. Atkinson ◽  
Craig J. Sturrock ◽  
Amanda Rasmussen
Keyword(s):  
Nutrient Depletion

scholarly journals Genetic and phenotypic associations between root architecture, arbuscular mycorrhizal fungi colonisation and low phosphate tolerance instrawberry (Fragaria × ananassa)

2020 ◽  
Author(s):  
Helen Maria Cockerton ◽  
Bo Li ◽  
Eleftheria Stavridou ◽  
Abigail Johnson ◽  
Amanda Karlström ◽  
...  
Keyword(s):  
Arbuscular Mycorrhizal Fungi ◽  
Root System ◽  
Mycorrhizal Fungi ◽  
Root Architecture ◽  
Arbuscular Mycorrhizal ◽  
System Size ◽  
Nutrient Depletion ◽  
Depletion Zone ◽  
Root System Size ◽  
The Relationship

Abstract Background: Phosphate is an essential plant macronutrient required to achieve maximum crop yield. Roots are able to uptake soil phosphate from the immediate root area, thus creating a nutrient depletion zone. Many plants are able to exploit phosphate from beyond this root nutrient depletion zone through symbiotic association with Arbuscular Mycorrhizal Fungi (AMF). Here we characterise the relationship between root architecture, AMF association and low phosphate tolerance in strawberries. The contrasting root architecture in the parental strawberry cultivars ‘Redgauntlet’ and ‘Hapil’ was studied through a mapping population of 168 progeny. Low phosphate tolerance and AMF association was quantified for each genotype to allow assessment of the phenotypic and genotypic relationships between traits. Results: A “phosphate scavenging” root phenotype where individuals exhibit a high proportion of surface lateral roots was associated with a reduction in root system size across genotypes. A genetic correlation between “root system size” traits was observed with a network of pleiotropic QTL were found to represent five “root system size” traits. By contrast, average root diameter and the distribution of roots appeared to be under two discrete methods of genetic control. A total of 18 QTL were associated with plant traits, 4 of which were associated with solidity that explained 46 % of the observed variation. Investigations into the relationship between AMF association and root architecture found that a higher root density was associated with greater AMF colonisation across genotypes. However, no phenotypic correlation or genotypic association was found between low phosphate tolerance and the propensity for AMF association, nor root architectural traits when plants are grown under optimal nutrient conditions.Conclusions: Understanding the genetic relationships underpinning phosphate capture can inform the breeding of strawberry varieties with better nutrient use efficiency. Solid root systems were associated with greater AMF colonisation. However, low P-tolerance was not phenotypically or genotypically associated with root architecture traits in strawberry plants. Furthermore, a trade-off was observed between root system size and root architecture type, highlighting the energetic costs associated with a “phosphate scavenging” root architecture.

Sign in / Sign up

Export Citation Format

Share Document