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A Hard Days Night



Molecular analysis revealed diel rhythmicity in the metabolic activity of single-celled microbial eukaryotes (protists) within an eddy in the North Pacific Subtropical Gyre (ca. 100 km NE of station ALOHA). Diel trends among different protistan taxonomic groups reflected distinct nutritional capabilities and temporal niche partitioning. Changes in relative metabolic activities among phototrophs corresponded to the light cycle, generally peaking in mid- to late-afternoon. Metabolic activities of protistan taxa with phagotrophic ability were higher at night, relative to daytime, potentially in response to increased availability of picocyanobacterial prey. Tightly correlated Operational Taxonomic Units throughout the diel cycle implicated the existence of parasitic and mutualistic relationships within the microbial eukaryotic community, underscoring the need to define and include these symbiotic interactions in marine food web descriptions. This study provided a new high-resolution view into the ecologically important interactions among primary producers and consumers that mediate the transfer of carbon to higher trophic levels. Characterizations of the temporal dynamics of protistan activities contribute knowledge for predicting how these microorganisms respond to environmental forcing factors.




A Hard Days Night



Figure 5. Diel trends in relative metabolic activity inferred from changes in mean RNA:DNA ratios among phototrophic/mixotrophic taxonomic groups: (A) dinoflagellates, (B) diatoms, (C) pelagophytes, (D) chlorophytes, and (E) haptophytes. For each time point, the average RNA:DNA ratio for OTUs within the same taxonomic group was calculated to better illustrate relative changes throughout the course of a day (circles). Shading surrounding each line represents the standard mean error of the RNA:DNA ratios for OTUs assigned to each taxonomic group. Total number of OTUs included for analysis and a summary of the OTUs found to have significant diel periodicity are reported in Table 1. Gray shaded regions indicate the dark cycle (night period). To better represent the cyclical nature of the study, 6 a.m. was plotted twice.


Figure 6. Diel trends in relative metabolic activity inferred from changes in mean RNA:DNA ratios among non-phototrophic taxonomic groups: (A) ciliates, (B) MArine STramenopiles (MAST), (C) Syndiniales, and rhizarian groups, (D) acantharia and (E) radiolaria. For each time point, the average RNA:DNA ratio for OTUs within the same taxonomic group was calculated to better illustrate relative changes throughout the course of a day (circles). Shading surrounding each line represents the standard mean error of the RNA:DNA ratios for OTUs assigned to each taxonomic group. Total number of OTUs included for analysis and a summary of the OTUs found to have significant diel periodicity are reported in Table 1. Gray shaded regions indicate the dark cycle (night period). To better represent the cyclical nature of the study, 6 a.m. was plotted twice.


Cyanobacteria are photosynthetic prokaryotes that are influential in global geochemistry and are promising candidates for industrial applications. Because the livelihood of cyanobacteria is directly dependent upon light, a comprehensive understanding of metabolism in these organisms requires taking into account the effects of day-night transitions and circadian regulation. These events synchronize intracellular processes with the solar day. Accordingly, metabolism is controlled and structured differently in cyanobacteria than in heterotrophic bacteria. Thus, the approaches applied to engineering heterotrophic bacteria will need to be revised for the cyanobacterial chassis. Here, we summarize important findings related to diurnal metabolism in cyanobacteria and present open questions in the field.


This film, directed by Richard Lester, was shot over two Sundays in 1959 for a cost of about seventy pounds. Nominated for an Oscar for best live-action short, it features Lester, Spike Milligan, Peter Sellers, Graham Stark, and Bruce Lacey.


This piece was written and produced by critic and filmmaker David Cairns in 2014. Narrated by actor Rita Tushingham, it looks at the influences on and impact of the early work of director Richard Lester.


Now married to property developer Rod Weston, Boyd has written two books, "Wonderful Tonight" and most recently, "My Life in Pictures," She appreciates not being able to "fully realize how unique your position is at the time." She explains that reporters would constantly ask the Beatles how long they would last, and none of them genuinely had any idea.


Behavioral evidence supports the hypothesis that some level of illumination is necessary for A. dorsata foragers to be nocturnally active. Reports show that worker bees can actively forage throughout the night if the moon is at least half full [11, 16]. Furthermore, in cities, A. dorsata may be capable of flying using artificial sky glow from city lights even when the moon is below the horizon [30]. The nocturnal foraging behavior of A. dorsata might therefore be an example of positive light effects on activity, where the light available from the moon or artificial lights stimulate activity at a time the species would not otherwise be active [31]. Regardless, this ability to be active during bright daylight hours as well as dim nighttime hours is impressive, as light intensity decreases by a factor of one million between a sunny day to a full moon night and is therefore even lower on nights when the moon is not full [32].


We recorded nocturnal activity from 5 nights before to 5 nights after the full moon of every month except October and November, where we recorded nocturnal activity from the full moon to 5 nights after the full moon due to delays in obtaining A. dorsata colonies. The colony observed each month is shown, as is the season to which each month belongs. We obtained minimum temperatures for every observation day through an online resource ( ). In addition to the observations focused on the full moon, we also observed Colony 4 for two complete lunar cycles, indicated by the text above; illumination readings were collected every observation night during the January to February lunar cycle (lunar cycle 1).


We recorded the nocturnal and diurnal activity of one A. dorsata colony for two complete lunar cycles: January 21 to February 19, 2019 and March 21 to April 19, 2019 (Fig 1). For each cycle, we began filming on the night of the first full moon (January 21 and March 21, respectively) and recorded for 24 hours until sunset on the following day. These 24-hour recordings were repeated every four to five days, such that we were able to record behavior on the night of every major moon phase in the lunar cycle (full, third-quarter, new, first-quarter, full) as well as one day in between each major phase.


Regressions of number of bee arrivals against number of bee dances per census period are shown for (a) day time periods, (b) twilight time periods (both morning and evening), and (c) night time periods. Strong correlations were found between arrival and dance rates for all diel times (rs > 0.82 for all). Data from all five A. dorsata colonies are included in this analysis.


When examining the effects of moon phase on bee arrival rates, we found that arrival rates varied greatly depending on diel time ( = 437.58, P 0.9) and during twilight (all P > 0.5) were constant across the moon phases. Arrivals rates during the day and during twilight on a given moon phase generally did not differ (P > 0.05), except for on the night of the waning gibbous moon, where twilight arrival rates were higher than daytime arrival rates (P 0.05).


When we examined all data collected from the five colonies observed over the course of the study, bee activity varied significantly with diel time ( = 151.22, P


Boxplots showing arrival rates during each diel time across seasons are shown. Nocturnal arrival rates were higher and diurnal arrival rates were lower in winter compared to spring/summer (P 0.05). In both winter and spring/summer arrival rates were significantly different between every diel time, with twilight having the highest rates. Arrival rates were higher at night than during the day in winter (P 0.6). The significance of all pairwise differences can be found in Table E in S1 File. Data shown here includes all observations from all five focal colonies studied over the course of the investigation. 041b061a72


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