scholarly journals Transcriptional response of the photoheterotrophic marine bacterium Dinoroseobacter shibae to changing light regimes

2011 ◽  
Vol 5 (12) ◽  
pp. 1957-1968 ◽  
Author(s):  
Jürgen Tomasch ◽  
Regina Gohl ◽  
Boyke Bunk ◽  
Maria Suarez Diez ◽  
Irene Wagner-Döbler
Keyword(s):  
Marine Bacterium ◽  
Transcriptional Response ◽  
Light Regimes ◽  
Dinoroseobacter Shibae ◽  
Changing Light

scholarly journals Ontogeny of Photosynthetic Performance in Fragaria virginiana under Changing Light Regimes

1979 ◽  
Vol 63 (3) ◽  
pp. 542-547 ◽  
Author(s):  
Thomas W. Jurik ◽  
Jean F. Chabot ◽  
Brian F. Chabot
Keyword(s):  
Photosynthetic Performance ◽  
Light Regimes ◽  
Fragaria Virginiana ◽  
Changing Light

The effect of rapidly changing light on the rate of photosynthesis in largetooth aspen (Populus grandidentata)

1970 ◽  
Vol 48 (4) ◽  
pp. 823-829 ◽  
Author(s):  
D. F. W. Pollard
Keyword(s):  
Bright Light ◽  
Net Photosynthesis ◽  
Ventilation Rate ◽  
Light Regimes ◽  
Fluctuating Irradiance ◽  
Rate Of Photosynthesis ◽  
Light Flecks ◽  
Four Levels ◽  
Forest Floors ◽  
Changing Light

Net photosynthesis by largetooth aspen was measured at each of four levels of irradiance, 3.4, 8.2, 22.6 and 73.1 W m−2 (0.4–0.7 μ), and during interchange of equal periods of these same levels. The periods between interchange ranged from about 0.2 to 300 s. All measurements were made between 17 and 19 °C; ventilation rate across leaves was equivalent to 1.5 m s−1. Photosynthesis was lower during interchange of long periods; depending on the irradiance levels selected, shorter periods led to increases in photosynthesis of up to 50%. Sometimes a recovery in photosynthesis occurred with the longest periods. The greatest changes were observed when one irradiance sequence was well below saturation level and the other was at or above saturation. Measurements of light regimes in three forest types showed that, during moderate winds at least, fluctuations with periods of between 0.1 and 100 s are commonplace. However, the effects of fluctuating irradiance on net photosynthesis may be important for growth and regeneration only where canopy height and spacings result in bright light flecks on other wise dark forest floors.

scholarly journals Phenotypic plasticity in Passiflora suberosa L.(Passifloraceae): induction and reversion of two morphs by variation in light intensity

2006 ◽  
Vol 66 (3) ◽  
pp. 853-862 ◽  
Author(s):  
E. A. Barp ◽  
G. L. G. Soares ◽  
G. Gosmann ◽  
A. M. Machado ◽  
C. Vecchi ◽  
...  
Keyword(s):  
Phenotypic Plasticity ◽  
Light Stress ◽  
Genotypic Diversity ◽  
First Year ◽  
Light Regimes ◽  
Cellular Hypertrophy ◽  
Cell Layers ◽  
Proximate Causes ◽  
Second Year ◽  
Changing Light

Leaf morphology may vary considerably even within a branch of Passiflora suberosa plants. Leaves are of a typical green type in shaded areas, but in open fields turn into violet, and apparently have greater thickness and trichome density. The proximate causes and the adaptive meaning, if any, for the existence of the violet morph are still unknown. By cultivating P. suberosa clones under two light regimes (total and partial exposure to sunlight), we consecutively induced (first year) and then reversed (second year) the appearance of the violet morph. We evaluated the corresponding changes in morpho-anatomic and chemical leaf characteristics. Plants that were grown under partial sunlight had a greater size and did not alter their green color, but those grown under total sunlight changed into violet, were smaller in size and their leaves were tougher, thicker, and had a greater number of trichomes. The violet morph had increased anthocyanins and phenolic derivatives. It also showed cellular hypertrophy, a greater number of cell layers in the mesophyll, and a lignified pericycle. Since these morphs are interchangeable by changing light conditions, we inferred that they are not determined by genotypic diversity, but are mainly a result of a physiological response to light stress, and thus part of P. suberosa phenotypic plasticity.

TEM study of a biofilm on copper corrosion

1996 ◽  
Vol 54 ◽  
pp. 220-221
Author(s):  
W. A. Chiou ◽  
N. Kohyama ◽  
B. Little ◽  
P. Wagner ◽  
M. Meshii
Keyword(s):  
Marine Bacterium ◽  
Culture Medium ◽  
Copper Alloys ◽  
Pure Copper ◽  
Localized Corrosion ◽  
Natural Seawater ◽  
Copper Corrosion ◽  
New Approach ◽  
The Past ◽  
Copper Tolerant

The corrosion of copper and copper alloys in a marine environment is of great concern because of their widespread use in heat exchangers and steam condensers in which natural seawater is the coolant. It has become increasingly evident that microorganisms play an important role in the corrosion of a number of metals and alloys under a variety of environments. For the past 15 years the use of SEM has proven to be useful in studying biofilms and spatial relationships between bacteria and localized corrosion of metals. Little information, however, has been obtained using TEM capitalizing on its higher spacial resolution and the transmission observation of interfaces. The research presented herein is the first step of this new approach in studying the corrosion with biological influence in pure copper.Commercially produced copper (Cu, 99%) foils of approximately 120 μm thick exposed to a copper-tolerant marine bacterium, Oceanospirillum, and an abiotic culture medium were subsampled (1 cm × 1 cm) for this study along with unexposed control samples.

Decreasing water pressure cues ‘bailout’ in seaweed-associated crustaceans

2020 ◽  
Vol 653 ◽  
pp. 121-129
Author(s):  
RB Taylor ◽  
S Patke
Keyword(s):  
Water Pressure ◽  
Rapid Change ◽  
Brown Seaweed ◽  
Model System ◽  
Rate Of Change ◽  
Suitable Habitat ◽  
Changing Light ◽  
Surface Increase ◽  
Reduced Water ◽  
Transparent Chamber

Small mobile crustaceans are abundant on seaweeds. Many of these crustaceans rapidly abandon their host if it is detached from the seafloor and floats towards the surface, but the trigger for this ‘bailout’ behaviour is unknown. We tested 2 potential cues, i.e. rapid change in light and rapid change in water pressure, using >1 mm epifauna on the brown seaweed Carpophyllum plumosum as a model system. Bailout occurred in response to reduced water pressure, but not to changing light, as (1) bailout occurred at similar rates in light and dark, (2) bailout occurred on the seafloor when water pressure was reduced within a transparent chamber by the equivalent of ~0.5 m depth or more, and (3) little bailout occurred when water pressure was held constant within the chamber while seaweeds were raised to the surface. Increase in pressure (simulating sinking) did not induce bailout. The rate of bailout increased with increasing magnitude of pressure reduction but was not influenced greatly by the rate of change of pressure within the range tested (up to an equivalent of 0.4 m depth s-1). The use of pressure rather than light as a cue for bailout is consistent with the need for seaweed-associated crustaceans to rapidly abandon a detached host and relocate to suitable habitat during both day and night.

Registered Report: Transcriptional Analysis of Savings Memory Suggests Forgetting Is Due to Retrieval Failure

2020 ◽  
Author(s):  
Robert Calin-Jageman ◽  
Irina Calin-Jageman ◽  
Tania Rosiles ◽  
Melissa Nguyen ◽  
Annette Garcia ◽  
...  
Keyword(s):  
Memory Trace ◽  
Aplysia Californica ◽  
Transcriptional Response ◽  
Transcriptional Analysis ◽  
Retrieval Failure ◽  
Initial Learning ◽  
Rigorous Test ◽  
Stage 1 ◽  
Induced Changes

[[This is a Stage 2 Registered Report manuscript now accepted for publication at eNeuro. The accepted Stage 1 manuscript is posted here: https://psyarxiv.com/s7dft, and the pre-registration for the project is available here (https://osf.io/fqh8j, 9/11/2019). A link to the final Stage 2 manuscript will be posted after peer review and publication.]] There is fundamental debate about the nature of forgetting: some have argued that it represents the decay of the memory trace, others that the memory trace persists but becomes inaccessible due to retrieval failure. These different accounts of forgetting lead to different predictions about savings memory, the rapid re-learning of seemingly forgotten information. If forgetting is due to decay, then savings requires re-encoding and should thus involve the same mechanisms as initial learning. If forgetting is due to retrieval failure, then savings should be mechanistically distinct from encoding. In this registered report we conducted a pre-registered and rigorous test between these accounts of forgetting. Specifically, we used microarray to characterize the transcriptional correlates of a new memory (1 day after training), a forgotten memory (8 days after training), and a savings memory (8 days after training but with a reminder on day 7 to evoke a long-term savings memory) for sensitization in Aplysia californica (n = 8 samples/group). We found that the re-activation of sensitization during savings does not involve a substantial transcriptional response. Thus, savings is transcriptionally distinct relative to a newer (1-day old) memory, with no co-regulated transcripts, negligible similarity in regulation-ranked ordering of transcripts, and a negligible correlation in training-induced changes in gene expression (r = .04 95% CI [-.12, .20]). Overall, our results suggest that forgetting of sensitization memory represents retrieval failure.

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